Note: Descriptions are shown in the official language in which they were submitted.
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DESICCANT BLENDED IN A THERMOPLASTIC
2
3 FIELD OF INVENTION:
4 The present invention relates to packages having desiccating abilities. More
S particularly, the present invention relates to a thermoplastic having a
desiccant blended therein.
6 BACKGROUND OF THE INVENTION:
7 There are many articles that are preferably stored, shipped and/or utilized
in an
8 environment that is as moisture free as possible. Therefore, containers
and/or packages having
9 the ability to absorb excess moisture trapped therein have been recognized
as desirable. One
application in which moisture absorbing containers are desired is for the
shipment and storage of
11 medications whose efficacy is compromised by moisture. The initial
placement of medicines
12 into a sealed moisture free container is usually controllable. Furthermore,
the container for the
13 medicine is selected so that is has a low permeability to moisture.
Therefore, the medication will
14 normally be protected from moisture until it reaches the end user. Once the
medicine is received
by the customer, however, the container must be repeatedly opened and closed
to access the
16 medication. Each time the container is opened and unsealed, moisture
bearing air will most
17 likely be introduced into the container and sealed therein upon closure.
Unless this moisture is
18 otherwise removed from the atmosphere or head space of the container, it
may be detrimentally
19 absorbed by the medication. For this reason, it is a well known practice to
include a desiccating
unit together with the medication in the container.
21 In other instances, moisture may be released from items that have been
placed in
22 containers or sealed in packaging wrap for shipping and/or storage. Prime
examples of such
23 items are food stuffs that release moisture during shipping and storage. In
the instance of
24 containers that are sealed and substantially impermeable to moisture, the
released moisture will
remain within the container. If not removed, this released moisture may have
ill effects on the
26 very item that released the moisture. It has been found that a substantial
amount of moisture is
27 released from certain food products within the first forty-eight (48) hours
after manufacture and
28 packaging. This released moisture will remain until removed. If the
moisture is not removed
29 shortly after its release, it may cause the food to degrade into a
condition that is not saleable
and/or useable. In these cases, desiccants may be included together with the
contained item or
31 items to continually absorb the released moisture until the product is
unpacked. In this way, a
32 . relatively dry environment is maintained about the stored item.
33 The need to eliminate moisture from within sealed containers has been
previously
34 recognized. Early attempts to achieve these goals included the provision of
desiccant materials in
fabric or similar bags that are placed in the containers together and
commingled with the matter
36 being shipped or stored. A consumer related problem, however, exists when
the desiccant is
37 loose and commingled together with consumable items. If not carefully and
thoroughly
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1 processed upon unpacking, the desiccant may not be separated from the
consumables and could
2 harm a person if unknowingly ingested.
3 , Another known mode by which a desiccant may be provided within a container
includes
4 coating.the interior surface of the container vessel with a desiccant
bearing material. Still further,
S it is known to provide desiccating abilities in a container through the use
of layered structures in
6 which a desiccant is "sandwiched" between moisture permeable material that
confines the
7 desiccant. These layered structures often take the form of flexible sheeting
that may be formed
8 into bag type containers into which items requiring a reduced moisture
environment are placed.
9 Several of the known means by which desiccant bearing containers are
constructed
require multiple steps and result in more complex and layered structures than
are desired.
1 I Furthermore, the provision of desiccant capsules together with contained
items is not always
12 satisfactory. As previously explained, commingling of desiccant with food
items and
13 medications is undesirable from a consumer stand point in that the
desiccant may be
14 inadvertently ingested. Still further, if the desiccant is not integrally
constructed with the
container, or at least attached thereto, it may be prematurely removed while
still needed for
16 continued removal of moisture from within the container. Therefore, a need
has been recognized
17 for containers that include a desiccant as an integral component of the
container's body or
18 package. Regarding the included desiccant of the container, it is desired
to enhance its
19 capabilities of moisture absorption with respect to both rate and quantity.
Still further, as in all
manufacturing processes, it is desired to reduce the required steps for
constructing desiccating
21 containers and simplify the resulting structures.
22 SUMMARY OF THE INVENTION:
23 In one embodiment of the present invention, a container, and process for
constructing
24 the container is provided that satisfies the need for more effective
desiccating storage and
shipping containers. The containers of the present invention provide superior
desiccating
26 abilities, while at the same time permitting efficient construction of a
container that has and
27 maintains structural integrity. Furthermore, the present invention provides
a means by which the
28 container may be formed having a substantially unitized and continuous
body. In another
29 embodiment, the present invention may be used to form an insert, integral
or non-integral, for the
container or package in the form of a shaped article such as a sheet, film, or
pellets, for example,
31 in the base or bottom of the container and not capable by itself of
containing the contents of the
32 container.
33 BRIEF DESCRIPTION OF DRAWINGS:
34 Figure I is a cross-sectional view of a desiccating cantainer with an
insert in the form of
a disc molded therein.
36 Figure 2 is a cross-sectional view of a desiccating container with an
insert in the form of
37 a liner molded therein.
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Figure 3 is a partial cross-sectional view of the container body showing a lip
retainer.
2 Figure 4 is a side view of a mold in partial section mounted upon a
rotatable table for
3 transport between injection stations and showing a container and insert
molded therein.
4 Figure 5 is a side view of a mold in partial section showing a container and
insert
molded therein in a single station configuration with two injection ports.
6 Figure 6 is a schematic of the method by which the container is co-molded.
7 Among those benefits and improvements that have been disclosed, other
objects and
8 advantages of this invention will become apparent from the following
description taken in
9 conjunction with the accompanying drawings. The drawings constitute a part
of this
specification and include exemplary embodiments of the present invention and
illustrate various
11 objects and features thereof.
12 DETAILED DESCRIPTION OF THE INVENTION:
13 As required, detailed embodiments of the present invention are disclosed
herein;
14 however, it is to be understood that the disclosed embodiments are merely
exemplary of the
1 S invention that may be embodied in various forms. The figures are not
necessarily to scale, some
16 features may be exaggerated to show details of particular components.
Therefore, specific
17 structural and functional details disclosed herein are nat to be
interpreted as limiting, but merely
18 as a basis for the claims and as a representative basis for teaching one
skilled in the art to
19 variously employ the present invention.
The presently disclosed invention includes and is applicable to the
manufacture of
21 similar containers. The containers O1 disclosed herein, however, are not
limited to vials. It is
22 contemplated that containers O1 constructed according to the present
invention may be larger or
23 smaller than the vials of 4,783,056 and of variable shape. Furthermore, the
caps 14 may be
24 integrally formed with the bodies 12 of the containers O1, or they may be
manufactured as
separate units. Still further, the present invention may be embodied
exclusively within the body
26 of a container 12 or a cap 14 for a container O 1.
27 The material used in the construction of these containers O l typically
provides a barner
28 between the interior 201 and exterior 202 of the container O1 that is
substantially moisture
29 impermeable and most often is a thermoplastic. While it is contemplated
that any thermoplastic
may be utilized, polypropylene is preferred for the constructian of the body
12 of the container
31 O1. Polypropylene is desirable because of its durability, rigidity and
resistance to breakage after
32 being molded into the form of a container 01. Examples of suitable
thermoplastics may be
33 selected from the following groups: polyolefin, polyethylene,
polycarbonate, polyamide,
34 ethylene-vinyl acetate copolymer, ethylene-methacrylate copolymer,
polyvinyl chloride,
polystyrene, polyester, polyester amide, polyacrylic ester. and poIyvinylidene
chloride, acrylic,
36 polyurethane, polyacetal, and polycarbonate. These and other thermoplastics
may be utilized
37 either singularly, or in combinations.
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The present invention includes the manufacture of a container O1 in which the
majority
2 of the container's body l2 is constructed from the base thermoplastic, e.g.
polypropylene,
3 because of its durability and resistance to breakage. To establish and/or
increase a desiccating
4 capacity of the molded container O1, an insert 200 that has been formed from
a desiccant
S entrained thermoplastic is integrally constructed with the body 12 of the
container O 1. The heat
6 molded insert of the present invention consists essentially of the
thermoplastic material with the
7 entrained desiccant. The term "consisting essentially of ' is used herein to
denote that the molded
8 insert may contain other materials so long as they do not materially effect
the moisture removal
9 properties of the insert. For example, the heat molded insert may have also
entrained carbon
black or other coloring agents to provide color or other aesthetic properties
to the insert.
11 The concentration of desiccant entrained (e.g. mixed or blended) within the
insert 200
12 may exceed seventy-five percent (75%) to not greater than eighty percent
(80%) by weight, so
13 that about seventy-five percent (75%) may extend to eighty percent (80%) by
weight. Typically,
14 however, the desiccant concentration in the insert 200 will fall within a
range of forty to seventy-
five (40-75%) desiccant to thermoplastic, by weight. This concentration is
considered to be a
16 high concentration for most thermoplastics. The maximum desiccant bearable
concentrations
17 will vary among the various types of thermoplastics due to their differing
characteristics. In the
18 instance of polyethylene or polypropylene, for example, the maximum
concentration of desiccant
19 will be about seventy-five percent (75%) by weight. As the desiccant
concentrations within the
thermoplastics increase, the performance of the material degenerates to
unacceptable levels. At
21 lower levels of desiccant concentrations, about forty percent (40%) could
extend to as low as
22 thirty percent (30%) where the limits of a viable product are reached.
23 In one embodiment, the insert 200 is located in the base or bottom 203 of
the container
24 body 12 and is exposed to the interior space 201 of the container O 1. The
configuration of this
embodiment is similar to a sample vial. Because the durability and resistance
to breakage is
26 lessened in the higher ranges of desiccant content, it is advantageous to
have the polypropylene
27 used in the construction of the container's body 12 formed about the insert
200 except for at
28 those surfaces to be exposed to the interior 201 of the container O1. A
container O 1 of this
29 configuration provides desired structural integrity while also providing
the greater desiccating
ability of the high desiccant laden insert 200 that is directly exposed to the
interior 201 of the
31 container O1. It is also contemplated that the insert 200 may be included
in the construction of
32 the container's cap 14. In this case, the insert will be integrally formed
with the cap 14 so that an
33 exterior surface of the insert 200 is exposed to the interior 201 of the
container O 1 when installed
34 thereupon.
As a further alternative embodiment, the insert 200 may be less localized, and
extended
36 to a greater degree about a greater portion of the interior surface 204 of
the container body 12. In
37 this instance, the high desiccant bearing thermoplastic forms more of a
liner 205 at the interior
4
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1 surface 204 of the container O 1. To provide maximum desiccating abilities,
the liner 205 may
2 completely cover the interior surface 204 of the container 01; this may
optionally include the
3 interiorly exposed surfaces of a cap 14 of a closed container O 1.
4 One contemplated method for the manufacture of the container O1 includes the
provision of a performed insert 200 about which the thernuoplastic of the
remainder of the body
6 12 of the container O l is injection molded. In this process, it is
important that the insert 200 be
7 affixed to or within the body 12 of the container O 1. This may be achieved
merely by molding
8 the body 12 about the insert 200 so that the two components are mechanically
connected one to
9 the other. The mechanical connection may take the form of a retaining lip
206 formed by the
container body 12 about the insert 200 that effectively fixes the insert 200
with respect to the rest
11 of the body O 1.
12 As shown by the various embodiments of the present invention, the insert of
the present
13 invention is formed by heat molding the desiccant entrained thermoplastic
of the present
14 invention. For example, the insert may be heat molded using any
conventional technique such as
co-extruding, extrusion blow moulding, injection blow molding, reaction
injection moulding or
16 extruding.
17 Alternatively, it is also contemplated that a "shrink-fit" may be achieved
by the body 12
18 forming thermoplastic about the insert 200. A particular example of this
shrink-fit application
19 would be the provision of a desiccant loaded insert 200 constructed from a
base thermoplastic of
polyethylene and a container body 12 molded thereabout from a base
thermoplastic of
21 polypropylene. Upon cooling after being injection molded, palyethylene
shrinks less than
22 polypropylene under similar circumstances. Therefore, if a polypropylene
body is injection
23 molded about a polyethylene insert 200 that has been either previously
formed, or is injection
24 molded contemporaneously with the container body 12, the polypropylene
container body 12 will
shrink about the polyethylene insert 200. This shrink-fit method may be
implemented whether or
26 not the insert 200 is relatively small and localized with respect to the
container body 12 or
27 whether or not the insert 200 is relatively small and localized with
respect to the container body
28 12 or whether the insert 200 takes the form of a previously described liner
205 configuration. In
29 either case, the exteriorly formed container body 12 may shrink about the
insert 200 if the
thermoplastics from which the insert 200 and container body l2 are
appropriately selected. The
31 use of the retaining lip 206 and shrink-fit method of affixing the insert
200 or liner 205 to the
32 container body 12 is used primarily when the materials of construction of
the insert 200 and
33 container body 12 are not compatible. The two components will be considered
incompatible if
34 they do not automatically adhere one to the other as a result of the
manufacturing process.
Alternatively, the insert 200 will be constructed from a material that bonds
to the body
36 12 of the container O 1 when the body 12 is placed thereabout. Therefore,
one method for
37 constructing the insert 200 bearing container O 1 of the present invention
is co-molding. That is,
5
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1 the primary body 12 of the container O l is molded, while the high desiccant
insert 200 is also
2 molded. The two portions are said to be co-molded because they are either
simultaneously or
3 sequentially injection molded in a single process. The process of co-molding
results in the
4 construction of a unitized container body 12 in which the insert 200 is
seamlessly combined with
the body 12. In most instances, the insert 200 and container body 12 adhere
one to the other as a
6 result of a melding together of the base thermoplastics from which each is
constructed at an
7 interface therebetween. The melding action takes place when the insert 200
and container body
8 12 are each injected into the mold 10 sufficiently closely with respect to
time so that each is in at
9 least a semi-molten state while in contact one with the other.
.Alternatively, heat from the
thermoplastic of a body 12 injected about an insert 200 may cause the
contacted portions of the
11 insert 200 to melt slightly and meld with the thermoplastic of the body 12
adjacent thereto. In
12 each case, there will be a phase between the high desiccant concentrate
insert 200 and container
13 body 12 in which the two construction materials blend to some degree
creating a seamless
14 interface and therefore unitized container O1 out of the two components.
In any event, the thermoplastic in which the desiccant is entrained is
moisture
16 permeable to the degree that moisture from the interior 201 of the
container O1 may be
17 transferred to and stored in the desiccant. It is possible that the
thermoplastic from which the
18 insert 200 is manufactured may have a higher moisture permeability than
that from which the
19 remainder of the body 12 of the container O1 is constructed. In this case,
the insert 200 may be
enclosed within the container O1 by a lower moisture permeable thermoplastic
of the container's
21 body 12. In this way, moisture will not readily be transferred from outside
the container O1 to the
22 interior. In view of the possibility of desiring differing moisture
permeabilities in the insert 200
23 and the container body 12, it is contemplated that the two components 200,
12 may be
24 constructed from different materials that are potentially incompatible.
The process of the present invention in which the insert 200 is co-molded
within the
26 primary body 12 of the container O 1 may vary. In a first embodiment of the
molding process, it
27 is contemplated that the mold 10 will move between two injection stations.
An injection
28 assembly that is generally designated by reference numeral 9ti may be
installed and withdrawn
29 from the mold frame 24. At one station, typically the first station, the
insert 200 will be injection
molded. In order to mold the insert 200, a ring shaped barner will be provided
that has a
31 circumference substantially matching the perimeter of a lower end of care
48. It is desired that
32 the thickness of the insert 200 be approximately one-eighth of an inch,
therefore the thickness or
33 height of the barrier ring will likewise be one-eighth of an inch. As the
injection assembly 96 is
34 installed within the mold frame 24, the barrier ring is the leading
component. The ring contacts
the lower surface of the core 48 forming a barner within which thermoplastic
may be injected.
36 High concentrate desiccant thermoplastic is then injected into the interior
of the ring thereby
37 forming the insert 200. The high concentrate desiccant thermoplastic of the
insert 200 may be
b
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t injected at a temperature that is less than the temperature at which the
thermoplastic of the
2 container body l2 is injected. The lowered temperature may be required so
that the desiccant
3 contained therein does not degrade. The necessity of the lowered temperature
may be obviated
4 by using different and/or high-grade desiccants that are not susceptible to
degradation within the
normal temperature ranges of the injection process.
b It is anticipated that the rate of absorption into the insert 200 may be
controlled by the
7 amount of surface area of the insert 200 exposed to the container's O I
interior 201. If greater
8 absorption rates are desired, more surface area of the insert 200 may be
exposed. If it is desired
9 that a more prolonged absorption process be achieved, then less surface area
will be exposed. It
is further contemplated that the rate of absorption by the insert. 200 may be
controlled by
11 encapsulation of the insert 200. If slower rates of absorption are desired,
then the insert 200 can
12 be encased to greater degrees by the thermoplastic that forms the body 12
of the container O1 and
13 which is less permeable to moisture. The rate of absorption may also be
controlled by using
14 different types of thermoplastics having different moisture permeability
rates. Unless otherwise
specified, the moisture permeability rates of the thermoplastics of the
present invention are
16 determined by ASTM test method F 1249-90, entitled "Standard Test Method
for Water Vapor
17 Transmission Rate Through Plastic Film and Sheeting Using a Modulated
Infrared Sensor."
18 Using ASTM F 1249-90 test method, the thermoplastics suitable for the
present invention have a
19 moisture vapor transmission rate of less than about 30g/mil/100 in2/24
hours.
For example, polyethylene typically has a moisture vapor transmission rate of
about 3
21 to about S gm per mil per I 00 square inches per 24 hours. In one
embodiment, the polyethylene
22 that is suitable in the present invention is made by Dow Chemical Co. and
has a tradename of
23 polyethylene 4012. In another example, polypropylene homopolymer typically
has a moisture
24 vapor transmission rate below 10 gm per mil per 100 square inches per 24
hours. In one
embodiment, the polypropylene that is suitable in the present invention is
made by Exxon
26 Chemicals and has a tradename of Escorenea Polypropylene--PP 35056. In a
further example,
27 low density polyethylene butene copolymer typically has a moisture vapor
transmission rate of
28 about 1 to about 2 gm per mil per 100 square inches per 24 hours. In one
embodiment, the low
29 density polyethylene butene copolymer that is suitable in the present
invention is made by Union
Carbide Corp. and has a tradename of GRSN-1539.
31 The amount of moisture that can be absorbed by the insert 200 may be
controlled in
32 several ways. It is contemplated that the amount of moisture absorbable by
the insert 200 may be
33 effected by changing the concentration of desiccant within acceptable
ranges; the greater the
34 concentration, the greater the amount of moisture that can be captured.
In an alternative embodiment, the thermoplastic from which the body 12 is
constructed
36 may also have desiccant entrained and suspended therein, but in lesser
concentrations than the
37 insert 200. It has been found that the concentration of desiccant in the
thermoplastic affects the
7
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1 performance characteristics of the molded container O 1. As an example, it
has been found that
2 while,the plastic will carry relatively high percentages of desiccant,
desirable characteristics such
3 as durability and resistance to breakage may degrade at higher desiccant
concentrations. It has
4 also been found that the plastic may be combined with lower concentrations
of desiccant without
S appreciably degrading the performance of the thermoplastic material in its
molded and solid state.
6 In a typical application, a relatively low concentration will fall within
the rate of five to fifteen
7 percent (5 - I S%) desiccant by weight to thermoplastic, with a preferred
concentration being
8 approximately seven and one-half (7.5%). Additionally, for the purpose of
the disclosure made
9 herein, desiccant-free thermoplastic may also be considered low
concentration thermoplastic. In
another embodiment, the thermoplastic having the lower concentration of
desiccant is molded
11 with the thermoplastic having the higher concentration of desiccant. That
is, the primary body 12
12 of the container O1 is molded, while the high desiccant insert 200 is also
molded. The two
13 portions are said to be co-molded. This process results in a unitized
contained body 12.
14 Various concentrations of desiccant bearing thermoplastic are commercially
available in
pellet form. Custom concentrations may be achieved by dry blending higher
concentration
16 desiccant pellets with lower concentration or desiccant-free pellets of
thermoplastic. When
17 blended in appropriate proportions, any desiccant concentration less than
that of the high
18 concentration desiccant pellets may be accomplished. After the drying
blending process, the
19 resulting mixture of pellets may be injection molded in a typical manner.
The type of desiccants that are suitable for use in the present invention
obtain their
21 moisture adsorbing capabilities through physical adsorption. The adsorption
process is
22 accomplished because of a fine capillary morphology of the desiccant
particles which pulls
23 moisture therethrough. The pore size of the capillaries, as well as the
capillaries' density
24 determine the absorption properties of the desiccant. Examples of these
physical adsorption
desiccants include molecular sieves, silica gels, clays and starches. In
several embodiments, the
26 molecular sieve pore sizes that are suitable for use in the present
invention include between about
27 3 to 15 Angstroms; about 3 to S Angstroms, about 5 to 8; 3 Angstroms; 4
Angstroms; S
28 Angstroms; 8 Angstroms and 10 Angstroms. In one embodiment, the pore size
of silica gel is
29 about 24 Angstroms. Because these types of physical adsorption desiccants
are both inert and
non-water soluble, they are preferred for many applications. Among other
reasons, these
31 innocuous characteristics are particularly compatible with food products
and medicinal products
32 such as pharmaceutical drugs and devices that may be enclosed within
containers formed from
33 the desiccant entrained polymers, or at least exposed thereto. As stated
previously, however, any
34 of the three types may be employed within the polymer bases of the present
invention for the
purposes of producing a desiccant entrained polymer. Suitable desiccating
agents of the present
36 invention include silica gel, molecular sieve and naturally occurring clay
compounds which
37 would also include montmorillimite clay.
8
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1 In another embodiment of the present invention. the desiccant that is
suitable for use in
2 the present invention is zinc chloride. This type absorbs water or moisture
and forms crystals of
3 a stable salt.
4 One of the many advantages of the present invention is that the molded
insert can be
S produced by mixing the components, heating and molding the mixture. The
mixing conditions
6 are chosen so that the desiccant is sufficiently entrained by substantially
uniformly blending in
7 the thermoplastic. For example, the components are mixed using a
conventional mixer, for
8 example, a Hensehel mixer. The present invention does not require further
processing by
9 stretching (e.g. uniaxial or biaxial orientation method) or expanding (e.g.
stretching at fast rates
then exposing the material to its crystalline melt point) to produce a porous
material.
11 The present invention is particularly suited for applications where a
product's (e.g.
12 pharmaceutical drug or device) efficacy may be compromised by a threshold
amount of moisture.
13 Unless the moisture above this threshold amount is removed within a certain
time period, this
14 moisture may detrimentally affect the product. The present invention solves
this problem by
removing this excess moisture within the desired time period. This is achieved
by the present
16 heat molded insert having a combination of: (a) a thermoplastic having
certain moisture vapor
17 transmission rate characteristics; (b) a certain type of desiccant; (c) the
insert having a certain
18 minimum and maximum weight % of desiccant; and (d) the insert having a
minimum moisture
19 adsorption after 8 hours at 10% relative humidity ("Rh") without stretching
or expanding. As a
result, the novel insert has previously unattained moisture adsorption in
packaging applications.
21 Unless otherwise specified, the % Rh is measured at 72°F by the test
method described in
22 Example 1.
23 Desiccant entrained plastic structures, and their constituent compounds
have been
24 described herein. As previously stated, detailed embodiments of the present
invention are
disclosed herein; however, it is to be understood that the disclosed
embodiments are merely
26 exemplary of the invention that may be embodied in various forms. It will
be appreciated that
27 many modifications and other variations that will be appreciated by those
skilled in the art are
28 within the intended scope of this invention as claimed below without
departing from the
29 teachings, spirit and intended scope of the invention.
The present invention will be illustrated in greater detail by the following
specific
31 examples. It is understood that these examples are given by way of
illustration and are not meant
32 to be limited to the disclosure or claims. For example, although the
following examples were
33 tested at 10% and 55% Rh at 72°F, the insert of the present
invention is also suited for other Rh
34 conditions. All percentages in the examples are elsewhere in the
specification are by weight
unless otherwise specified.
36 EXAMPLE 1
9
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1 This example illustrates a desiccant blended in a thermoplastic consisting
essentially of
2 a thermoplastic of polypropylene (Exxon Chemicals, tradename Escorenea
Polypropylene
3 3505G) and a desiccant of molecular sieve (Elf Atochem, tradename
Siliporitea molecular sieves;
4 NK 10). The desiccant and thermoplastic were weighed to achieve the weight
percent of each
shown in the table. The desiccant and thermoplastic were then mixed in a
Henschel FM-200 high
6 intensity mixer. The material was then fed to a Leistritz twin screw
extruder at a temperature in
7 the ten zones ranging from about 200° to 320°F, at about 400
rpm and at about 30 Ibs./hr to
8 produce a pelletized material of about 1 /8 inch diameter. The pelletized
material was fed directly
9 to a hot roll press. A film was formed of desired thickness ( 10 mil).
The film was then evaluated for moisture adsorption of its total weight by
using the
11 following test method (a) the environmental chamber was preset for
72°F and the desired
12 relative humidity ("Rh"); (b) the dish was weighed and the weight recorded;
(c) the scale was
13 then tared to remove the weight of the dish from the balance; (d) the film
was then added to the
14 weighed dish; (e) the material was then weighed and the weight recorded;
(f) the weigh dish
I S with the sample was placed in the environmental chamber; (g) the sample
was left in the
I 6 chamber for the desired time; (h) after the desired time was reached, the
dish with the sample
17 was removed, re-weighed and the weight recorded; and (i) percent of
moisture absorbed per
18 gram of material was calculated by:
19 final weight - original weig_,ht * 100
original weight
21
22 The results are presented in Table I.
SUBSTITUTE SKEET (RULE 26)
CA 02334014 2000-12-O1
WO 99/62697 PCT/US99/11565
1 TABLEI
2 % Moisture Adsorption
3 % desiccant 10% Rh 55%Rh
4 per total weight 8hr 24 hr 8 hr 24
hr
10 .5 .8 .S .6
6 20 .7 1.0 .7 1.3
7 30 .7 1.0 1.5 1.9
8 60 1.5 2.6 3 4.5
9 70 4 6 8 11.5
I 1 EXAMPLE 2
12 This example illustrates a desiccant blended in a thermoplastic consisting
essentially of a
13 thermoplastic of a low density polyethylene butene copolymer (Union
Carbide, tradename 1137)
14 and of a desiccant of molecular sieve (Elf Atochaem, tradename Siliporitea
molecular sieves,
NK10). The desiccant and thermoplastic were prepared in a manner similar to
the method
16 discussed in Example 1 to produce a pellet. The pellet was then formed into
a film by using a
17 platen press. The pellet was placed in the press between 2 sheets of Mylar
film. The pellet was
18 pressed at 425°F at 25 tons for about I S-20 seconds. The desired
thickness was achieved by
19 placing shims inside press. The film was removed and allowed to cool for
about 15-20 seconds
and then placed in a vacuum sealed brown bag. The film was also evaluated by
the same method
21 as discussed in Example 1. The results are presented in Table II.
22 TABLE II
23 % Moisture ption
Adsor
24% desiccant Film 10% Rh 55%Rh
25per total weiehtThickness (mil)8hr 24 hr 8 hr 24 hr
2650 3.5 3 S.5 4.5 7
2750 10 1.5 3 3 5
2860 S 2.5 4.5 3.5 6.5
2960 10 2 3.5 3 5
3070 17 1 2 2 3
3170 30 1 2 1.5 3
3270 53 2 4 3.5 6.5
3380 20 1 2 1.5 3
3480 44 1.5 3 2 4
3580 90 2 3 2.5 4
36
37The previous examples demonstratethat an insert
can be produced,
within the
scope of the
38 present invention, by adjusting the following parameters: (a) type of
thermoplastic; (b) desiccant
39 loading level; (c) thickness of insert; and (d) type of desiccant..
SUBSTITUTE SHEET (RULE 26)
