Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Desci~tion
Method Of Sealing A Tube In A Container
Technical Field
This invention relates generally to a port or dispensing tube for use with
flexible containers and more specifically to a method for attaching such a
tube to a
medical grade or food grade container.
Background Art
In the medical delivery field, beneficial agents are packaged in flexible
containers such as LV. bags and are ultimately delivered through tubing such
as an
administration set to patients to achieve therapeutic effects. Port tubing is
a necessary
feature of the container and provides access to the contents of the container.
LV. bags
are most commonly fabricated from polymers such as polyvinyl chloride,
ethylene
vinyl acetate, or polyolefin alloys, such as those disclosed in commonly
assigned U.S.
Patent No. 5,686,527. The LV. containers usually have two confronting walls or
panels that are attached to one another along a peripheral seam to make a
fluid tight
compartment.
Conventional containers employ port designs from one of two broad
categories, panel ports and edge ports. Panel ports are attached to the
container on a
panel and are often centrally disposed. The panel port extends perpendicularly
from
the face of the panel. Edge ports are attached between the two panels along a
peripheral seam of the container and extend in the plane of the panels.
Panel ports are easily installed but have a number of drawbacks. First, panel
ports, by design, necessitate the use of one or more injection molded parts.
These
injection molded parts are costly, especially at lower production volumes.
Containers
having panel ports also have the undesired tendency to retain a residual
volume of
fluid due to incomplete drainage.
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Edge ports have a different set of design issues. Edge ports are prone to a
manufacturing defect known as "channel leak." Channel leakage occurs along the
port
tube and results from an incomplete seal at the position where the planar
surfaces of
the two panels and the rounded surface of the port tube meet. Channel leakage
is
more likely to occur when the container is fabricated from a sheeting material
that has
a high modulus, and especially when using thin layers of such a stiff
material, as the
material will have a tendency to crease upon folding.
Prior attempts at overcoming the channel leak problems have led to the use of
injection molded parts. These parts are commonly used in containers
constructed
from biaxially oriented nylon, foil, TEFLON~, polyester, and multilayer
structures
containing these polymers or similar inelastic materials. The injection molded
parts
are inserted between the panels and, in most instances, have a tapered outer
profile.
The purpose of the taper is to provide fillet material to the area where
channel leakage
is likely to occur. Again, these injection molded parts are relatively
expensive,
especially in low volume production.
Another design issue with edge port tubes is that a mandrel must be used to
install the edge port. Typically, the mandrel is inserted through an opening
in the port
tube, and into the fluid flow channel of the tubing. The tubing and mandrel
are
positioned between the sidewalls of the container. With the mandrel so
inserted,
2 0 welding dies are used to compress the container sidewalls and tubing to
seal the
tubing between the sidewalls. The mandrel serves several purposes. The mandrel
prevents the tubing interior wall from deforming. The mandrel, along with the
external welding dies, are precisely dimensioned to achieve the desired
compression
forces against the mandrel. One of the drawbacks to using a mandrel is that
the tubing
2 5 material can stick to the mandrel making withdrawal of the mandrel
difficult. Also,
since the mandrel must be threaded through the port tube opening, the tubing
segment
must be of a relatively short length.
The present invention is provided to solve these and other problems.
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Disclosure of Invention
The present invention provides a method for connecting rounded members,
such as port tubes, between planar members, such as the sheet stock of
flexible
containers. The process provides for either sealing without the use of a
mandrel or by
using a mandrel that does not directly contact the interior walls of the
tubing. The
methods disclosed can be used to seal monolayer tubing or multilayered tubing.
The present invention further provides a mandrel that delivers fluid under
pressure to an interior surface of the tubing sidewall. The pressure is
applied in a
radial direction and has sufficient force to cause intimate contact between
the external
periphery of the tubing and the inner surfaces of the container sidewall
during the
sealing process. This method allows for sealing the tubing without collapsing
the
interior sidewall surfaces into contact with one another, and without having
the
mandrel contact the tubing sidewall in the seal area. In a preferred form, the
fluid is
air, but the use of liquids is also contemplated.
The present invention also provides a method of sealing tubing without the use
of a mandrel. In sealing a monolayer tubing without a mandrel, for a given
material or
a material having a given modulus, it is necessary to maintain a critical
ratio of wall
thickness to the inner diameter of the tubing. The wall thickness to ID ratio
is
inversely related to the modulus of the material so that as the modulus of the
material
2 0 increases the required wall thickness to ID may decrease. By maintaining
this critical
ratio, the collapse of the tubing is prevented, and it is possible to cause an
exterior
portion of the monolayer tubing to heat to its melt softening temperature and
to flow
along an unsoftened interior portion of the tubing to provide fillet material
to the
weld, thereby averting channel leakage.
2 5 In a multiple layered tubing, the method of the present invention provides
an
outer layer with a first hardness and an inner layer with a second hardness
that is
greater than the first hardness. The inner layer can, in effect, serve as a
mandrel upon
which the outer layer may be compressed by the dies causing material from the
outer
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layer to flow into interstitial spaces between the container sidewalls and
exterior walls
of the tubing to provide fillet material to the weld.
Brief Description of Drawings
FIG. 1 is a front elevational view of a container having a pair of port tubes
sealed in a perimeter edge of the container in accordance with the present
invention;
FIG. 2 is a schematic cross-sectional view of a two-layered coextruded tube in
accordance with the presentinvention;
FIG. 2a is a cross-sectional view of a three-layered coextruded tube in
accordance with the present invention;
FIG. 2b is a cross-sectional view of a monolayer tubing in accordance with the
present invention;
FIG. 3 is a cross-sectional view showing the port tube in a perimeter edge of
the container between flat welding dies that are open;
FIG. 4 is a cross-sectional view of the port tube of FIG. 3 wherein the dies
are
partially closed;
FIG. 5 is a cross-sectional view of the port tube of FIG. 3 wherein the dies
are
closed;
FIG. 6 is a schematic view of a fluid administration set;
FIG. 7 is a schematic view of a mandrel in accordance with the present
2 0 invention;
FIG. 8 is a diagrammatic view of a method for attaching a dispensing tube to a
flexible container;
FIG. 9 is a schematic view of another embodiment of the mandrel of the
present invention; and
2 5 FIG. 10 is an end view of another embodiment of a mandrel of the present
invention.
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Best Mode for Carrying Out the Invention
While the invention is susceptible of embodiment in many different forms,
there is shown in the drawings, and will herein be described in detail,
preferred
5 embodiments of the invention with the understanding that the present
disclosure is to
be considered as an exemplification of the principles of the invention and is
not
intended to limit the broad aspect of the invention to the embodiments
illustrated.
Referring now to tha drawings, FIG. 1 shows a container assembly, such as a
flexible container, generally designated by the reference numeral 10. The
assembly 10
includes a flexible container 12 having port or dispensing tubes 14 sealed in
a
perimeter edge of the container 12. The container 12 includes a pair of facing
planar
members or sidewalls 16, which are joined at their perimeter edges 18 (FIGS. l
and 3)
to define a fluid compartment 23 therebetween. The planar members 16 can be
constructed from a number of different materials including polyvinyl chloride,
polyolefins, polyolefin copolymers, polyolefin alloys and blends, polyamides,
polyesters and other materials as will be described in greater detail below.
FIG. 2 shows a multilayered port tubing 14, including a first or outer layer
20
and a second or inner layer 22 and a fluid passageway 25. In a preferred form
the
outer layer is a thermoplastic polymer that has a tan delta measured in
accordance
2 0 with ASTM No. D 4065-95 from 0-0.08, more preferably from 0.02-0.075 and
most
preferably from 0.03-0.06 or any combination or subcombination of ranges
therein.
Suitable thermoplastic polymers include polyolefins having a tan delta as set
forth
above. In a preferred form the thermoplastic polymer is an ethylene «-olefin
copolymer wherein the «-olefin comonomer has less than 12 carbons. More
2 5 preferably, the ethylene copolymer is an ultra-low density polyethylene
(ULDPE)
having a density of from about 0.880-0.910 g/cm3 and most preferably are
produced
using a metallocene catalyst system. Such a catalyst is said to be a "single
site"
catalyst because it has a single sterically and electronically equivalent
catalyst position
as opposP~l to the Ziegler-Natta type catalyst which are known to have a
mixture of
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catalyst sites. Such metallocene catalyzed ethylene «-olefins are sold by Dow
under
the tradename AFFINITY, and by Exxon under the tradename EXACT. Ethylene
copolymers produced using vanadium catalyzed systems such as Mitsui's TAFMER
are also suitable.
In a preferred form of the multilayered tubing 14, the inner layer 22 has
sufficient resistance to compression to act as a mandrel. The inner layer 22
of the
tubing 14 should be composed of polyolefins, polyolefin copolymers, polyolefin
alloys, polyamides; polyesters, and polyvinyl chloride (PVC) and block
copolymers,
for example polyester-polyether block copolymers such as those sold under the
trademark HYTREL~. Most preferably, the inner layer 22 is composed of
polyvinyl
chloride or a blend containing polyester-polyether block copolymers, which are
capable of being bonded using solvent bonding techniques.
Figure 2b shows a monolayer tubing of the present invention. The monolayer
tubing may be of the same materials as set forth above for the outer layer 20
of the
multilayered tubing. For a material of Shore A hardness of 70, it is critical
for the
monolayer tubing to have a ratio of wall thickness to inner diameter dimension
that is
greater than 0.20 and more preferably greater than or equal to 0.25. Monolayer
tubings of these types of materials having these critical dimensions allow for
the inner
portion of the tubing to remain in a solid phase and to act, in effect, as a
mandrel
2 0 while allowing the sealing portion of the tubing to flow upon applying
heat and
compression.
As will be discussed in detail below, the tubing 14 may be sealed to the
planar
members 16 using any energy source which causes melting of the sealing layers
or
sealing portion of a monolayer tubing to form a weld between the tubing 14 and
the
2 5 planar members 16. These energy sources may be applied through, but not
limited to,
impulse welding equipment, constant temperature equipment, or by induction
welding
techniques such as radio frequency. Any of these sealing energies whether
causing
heating through induction or conduction shall be collectively referred to as
sealing
energies.
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Disposing of the use of a mandrel is significant for several reasons including
that it adds flexibility to the manufacturing steps for connecting a fluid
administration
set 26 (FIG. 6) to a flexible container. Using a mandrel limits the length of
a port or
dispensing tube as the mandrel must be inserted through a distal end of the
tubing 14
into the fluid passageway 25 and into an area where the tubing 14 is sealed to
the
planar members 16. It is not practical to insert a mandrel through a long
length of
tubing of an administration set 26. Thus, disposing of the need for a mandrel
allows
the tubing 14 to be of a standard length of a port-tube of 0.375-1.0 inches as
shown in
Figure l, or extend from the container 12 to some distal site and serve as a
fluid
administration set 26 as shown in FIG. 6. Also, disposing of a mandrel
alleviates the
problems caused when the tubing sticks to the mandrel. As will be discussed in
greater detail below, the same advantages can be realized by using a fluid
supply line
which can be used to pressurize the fluid passageway 25 of the tubing to, in
effect,
function as a mandrel. As shown in Figure 7, such a mandrel, in a preferred
form, has
a generally J shape.
The planar members 16 may be constructed of any flexible polymeric material
including PVC, polyolefins and polyolefin alloys. The planar members 16 may be
multilayered structures or monolayer structures. In a preferred form, the
planar
members 16 is a multilayered film (Figure 8) having a core layer 80 of a vinyl
alcohol
2 0 copolymer; a solution contact layer 82 of a polyolefin positioned on a
first side of the
core layer; an outer layer 84 positioned on a second side of the core layer
opposite the
solution contact layer 82, the outer layer being selected from the group
consisting of
polyamides, polyesters and polyolefins; and, optionally, a tie layer 86
adhered to each
of the first and second sides of the core layer and positioned between the
solution
2 5 contact layer and the core layer and between the outer layer and the core
layer.
In a preferred form of the planar member 16, the core layer 14 is an ethylene
vinyl alcohol copolymer having an ethylene content of from about 25-45 mole
percent
(ethylene incorporated, as specified in EVALCA product literature). Kuraray
Company, Ltd. produces EVOH copolymers under the tradename EVAL~ which have
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about 25-45 mole percent of ethylene, and a melting point of about 150-195
°C. Most
preferably the EVOH has a ethylene content of 32 mole percent.
The outer layer preferably is a polyamide, polyester, polyolefin or other
material that aids in the transport of water away from the core layer.
Acceptable
polyamides include those that result from a ring-opening reaction of lactams
having
from 4-12 carbons. This group of polyamides therefore includes nylon 6, nylon
10
and nylon 12. Most preferably, the outer layer is a nylon 12.
Acceptable polyamides also include aliphatic polyamides resulting from the
condensation reaction of di-amines having a carbon number within a range of 2-
13,
aliphatic polyamides resulting from a condensation reaction of di-acids having
a
carbon number within a range of 2-13, polyamides resulting from the
condensation
reaction of dimer fatty acids, and amide containing copolymers. Thus, suitable
aliphatic polyamides include, for example, nylon 66, nylon 6,10 and dimer
fatty acid
polyamides.
Suitable polyesters for the outer layer include polycondensation products of
di-
or polycarboxylic acids and di or poly hydroxy alcohols or alkylene oxides.
Preferably, the polyesters are a condensation product of ethylene glycol and a
saturated carboxylic acid such as ortho or isophthalic acids and adipic acid.
More
preferably the polyesters include polyethyleneterphthalates produced by
condensation
2 0 of ethylene glycol and terephthalic acid; polybutyleneterephthalates
produced by a
condensations of 1,4-butanediol and terephthalic acid; and
polyethyleneterephthalate
copolymers and polybutyleneterephthalate copolymers which have a third
component
of an acid component such as phthalic acid, isophthalic acid, sebacic acid,
adipic acid,
azelaic acid, glutaric acid, succinic acid, oxalic acid, etc.; and a diol
component such
as 1,4-cyclohexanedimethanol, diethyleneglycol, propyleneglycol, etc., and
blended
mixtures thereof.
Suitable polyolefins for the outer layer are preferably selected from
homopolymers and copolymers of polyolefins. Suitable polyolefins are selected
from
the group consisting of homopolymers and copolymers of alpha-olefins
containing
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from 2 to about 20 carbon atoms, and more preferably from 2 to about 10
carbons.
Therefore; suitable polyolefins include polymers and copolymers of propylene,
ethylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1, nonene-1 and
decene-1.
Suitable polyolefins further include lower alkyl and lower alkene acrylates
and
acetates and ionomers thereof. The term "lower alkyl" means alkyl groups
having 1-5
carbon atoms such as ethyl, methyl, butyl and pentyl. The term "ionomer" is
used
herein to refer to metal salts of the acrylic acid copolymers having pendent
carboxylate groups associated with monovalent or divalent cations such as zinc
or
sodium.
Most preferably, the inner layer is selected from ethylene a-olefin copolymers
especially ethylene-butene-1 copolymers which are commonly referred to as
ultra-low
density polyethylenes (ULDPE). Preferably the ethylene a-olefin copolymers are
produced using metallocene catalyst systems. Suitable metallocene catalyzed
ethylene
a-olefins are sold by Dow under the tradename AFFINITY, and by Exxon under the
tradename EXACT. The ethylene a-olefins preferably have a density from 0.880-
0.910 g/cc.
Suitable tie layers include modified polyolefins blended with unmodified
polyolefins. The modified polyolefms are typically polyethylene or
polyethylene
copolymers. The polyethylenes can be ULDPE, low density (LDPE), linear low
2 0 density (LLDPE), medium density polyethylene (MDPE), and high density
polyethylenes (HDPE). The modified polyethylenes may have a density from 0.850-
0.95 g/cc.
The polyethylene may be modified by grafting with carboxylic acids, and
carboxylic anhydrides. Suitable grafting monomers include, for example,
malefic acid,
fumaric acid, itaconic acid, citraconic acid, allylsuccinic acid, cyclohex-4-
ene-1,2-
dicarboxylic acid, 4-methylcyclohex-4-ene-1,2-dicarboxylic acid,
bicyclo[2.2.1]hept-
5-ene-2,3-dicarboxylic acid, x-methylbicyclo[2.2.1 ]kept-5-ene-2,3-
dicarboxylic acid,
malefic anhydride, itaconic anhydride, citraconic anhydride, allylsuccinic
anhydride,
citracon:c anhydride, allylsuccinic anhydride, cyclohex-4-ene-1,2-dicarboxylic
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anhydride, 4-methylcyclohex-4-ene-1,2-dicarboxylic anhydride, bicyclo[2.2.1]
hept-5-
ene2,3-dicarboxylic anhydride, and x-methylbicyclo[2.2.1] hept-5-ene-2,2-
dicarboxylic anhydride.
Examples of other grafting monomers include C,-C8 alkyl esters or glycidyl
5 ester derivatives of unsaturated carboxylic acids such as methyl acrylate,
methyl
methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl
methacrylate,
glycidyl acrylate, glycidyl methacrylate, monoethyl maleate, diethyl maleate,
monomethyl maleate, diethyl maleate, monomethyl fumarate, dimethyl fumarate,
monomethyl itaconate, and diethylitaconate; amide derivatives of unsaturated
10 carboxylic acids such as acrylamide, methacrylamide, maleicmonoamide,
malefic
diamide, malefic N-monoethylamide, malefic N,N-diethylamide, malefic N-
monobutylamide, malefic N,N dibutylamide, fumaric monoamide, fumaric diamide,
fumaric N-monoethylamide, fumaric N,N-diethylamide, fumaric N-monobutylamide
and fumaric N,N-dibutylamide; imide derivatives of unsaturated carboxylic
acids such
as maleimide, N-butymaleimide and N-phenylmaleimide; and metal salts of
unsaturated carboxylic acids such as sodium acrylate, sodium methacrylate,
potassium
acrylate and potassium methacrylate. More preferably, the polyolefin is
modified by
a fused ring carboxylic anhydride and most preferably a malefic anhydride.
The unmodified polyolefins can be selected from the group consisting of
2 0 ULDPE, LLDPE, MDPE, HDPE and polyethylene copolymers with vinyl acetate
and
acrylic acid. Suitable modified polyolefin blends are sold, for example, by
DuPont
under the tradename BYNEL~, by Chemplex Company under the tradename
PLEXAR~, and by Quantum Chemical Co. under the tradename PREXAR.
These multilayered films are more fully set forth in United States Patent
2 5 Application Serial No. 08/934,924 which is incorporated herein by
reference and
made a part hereof.
Planar members 16 may also be multilayered or monolayer structures
fabricated from the polyolefin alloys disclosed in commonly assigned U.S.
Patent No.
5,686,527 which is incorporated herein by reference and made a part hereof.
For
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example, it may be desirable to use multiple component polymer alloys, such as
a 3-5
component polymer alloys that are RF responsive or RF susceptible. What is
meant
by RF susceptible is that the material will have a dielectric loss when
excited with a
signal having a frequency between 1 and 60 MHz, and between the temperature
range
of 25-250 °C, greater than or equal to 0.05 and more preferably greater
than or equal
to 0.1
In a first embodiment of an acceptable three component polymer alloy that is
RF responsive, the first component will confer heat resistance and flexibility
to the
composition. This component may be selected from the group consisting of
amorphous polyalpha olefins and preferably is a flexible polyolefin. These
polyolefins should resist distortions to high temperatures up to 121
°C, having a peak
melting point of greater than 130°C and be highly flexible, having a
modulus of not
more than 20,000 psi. Such a flexible polyolefin is sold under the product
designation
Rexene FPO 90007 which has a peak melting point of 145 °C and a
modulus of
11,000 psi. In addition, certain polypropylenes with high syndiotacticity also
posses
the properties of high melting point and low modulus. The first component
should
constitute from 40-90% by weight of the composition.
The second component of the three component composition is an RF
susceptible polymer which confers RF sealability to the composition and may be
2 0 selected from either of two groups of polar polymers. The first group
consists of
ethylene copolymers having 50-85% ethylene content with at least one comonomer
selected from the group consisting of acrylic acid, methacrylic acid, ester
derivatives
of acrylic acid with alcohols having 1-10 carbons, ester derivatives of
methacrylic acid
with alcohols having 1-10 carbons, vinyl acetate, and vinyl alcohol. The RF
2 5 susceptible polymer may also be selected from a second group consisting of
polymers
and copolymers containing at least one monomer or segment of urethane, ester,
urea,
imide, sulfone, and amide. These functionalities may constitute between 5-100%
of
the RF susceptible polymer. The RF susceptible polymer should constitute by
weight
from 5-50% of the composition. Preferably, the RF component is copolymers of
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ethylene methyl acrylate with methyl acrylate within the range of 1 S-25% by
weight of
the polymer.
The final component of the three component compound confers compatibility
between the first two components, and is selected from a styrene and
hydrocarbon
block copolymer and more preferably a styrene-ethylene-butene-styrene block
(SEBS)
copolymer, styrenic block copolymers and most preferably SEBS block copolymer
that is malefic anhydride functionalized. The third component should
constitute by
weight within the range of 5-30% of the composition.
In a second embodiment of the three component polymer alloy, the first
component confers RF sealability and flexibility over the desired temperature
range.
The first component confers high temperature resistance ("temperature
resistant
polymer") and is chosen from the group consisting of polyamides, polyimides,
polyurethanes, polypropylene, and polymethylpentene. Preferably the first
component
constitutes by weight within the range of 30-60% of the composition, and
preferably is
polypropylene. The second component confers RF sealability and flexibility
over the
desired temperature range. The RF polymer is selected from the first and
second
groups identified above with the exception of ethylene vinyl alcohol. The
second
component should constitute by weight within the range of 30-60% of the
composition. The third component ensures compatibility between the first two
components and is chosen from SEBS block copolymers and preferably is malefic
anhydride functionalized. The third component should constitute by weight
within the
range of 5-30% of the composition.
As for four and five component polymer alloys that are RF responsive, the
first
component confers heat resistance. This component may be chosen from
polyolefins,
2 5 most preferably polypropylenes, and more specifically the propylene alpha-
olefin
random copolymers (PPE). Preferably, the PPE's will have a narrow molecular
weight
range. However, by themselves, the PPE's are too rigid to meet the flexibility
requirements. When combined by alloying with certain low modulus polymers,
good
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flexibility can be achieved. Examples of acceptable PPE's include those sold
under
the product designations Soltex 4208, and Exxon Escorene PD9272.
These low modulus copolymers can include ethylene based copolymers such
as ethylene vinyl acetate ("EVA"), ethylene co-alpha olefins, or the so-called
ultra low
density (typically less than 0.90Kg/L) polyethylenes ("ULDPE"). These ULDPE
include those commercially available products sold under the trademarks
TAFMER~
(Mitsui Petrochemical Co.) under the product designation A485, EXACT~ (Exxon
Chemical Company) under the product designations 4023-4024, and INSITE~
technology polymers (Dow Chemical Co.). In addition, poly butene-1 ("PB"),
such as
l0 those sold by Shell Chemical Company under product designations PB-8010, PB-
8310; thermoplastic elastomers based on SEBS block copolymers, (Shell Chemical
Company), poly isobutene ("PIB") under the product designations Vistanex L-80,
L-
100, L-120, L-140 (Exxon Chemical Company), ethylene alkyl acrylate, the
methyl
acrylate copolymers ("EMA") such as those under the product designation EMAC
2707, and DS-1130 (Chevron), and n-butyl acrylates ("ENBA") (Quantum Chemical)
were found to be acceptable copolymers. Ethylene copolymers such as the
acrylic and
methacrylic acid copolymers and their partially neutralized salts and
ionomers, such as
PRIMACOR~ (Dow Chemical Company) and SURLYN~ (E.I. DuPont de Nemours
& Company) are also satisfactory.
2 0 Preferably the first component is chosen from the group of polypropylene
homo and random copolymers with alpha olefins which constitute by weight
approximately 30-60%, more preferably 35-45%, and most preferably 45%, of the
composition and any combination or subcombination of ranges therein. For
example,
random copolymers of propylene with ethylene where the ethylene content is in
an
amount within the range of 1-6%, and more preferably 2-4%, of the weight of
the
polymer is preferred as the first component.
The second component of the four component polymer alloy confers flexibility
and low temperature ductility and is a second polyolefin different than that
of the first
componer_t wherein it contains no propylene repeating units ("non propylene
based
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polyolefin"). Preferably it is selected from the ethylene copolymers including
ULDPE; polybutene, butene ethylene copolymers, ethylene vinyl acetate,
copolymers
with vinyl acetate contents between approximately 18-50%, ethylene methyl
acrylate
copolymers with methyl acrylate contents being between approximately 20-40%,
ethylene n-butyl acrylate copolymers with n-butyl acrylate content of between
20-
40%, ethylene acrylic acid copolymers with the acrylic acid content of greater
than
approximately 15%. Examples of these products are sold under such product
designations as TAFMER~.A-4085 (Mitsui), EMAC DS-1130 (Chevron), Exact
4023, 4024 and 4028 (Exxon). More preferably, the second component is either
ULDPE sold by Mitsui Petrochemical Company under the designation TAFMER~ A-
4085, or polybutene-l, PB8010 and PB8310 (Shell Chemical Co.), and should
constitute by weight approximately 25-50%, more preferably 35-45%, and most
preferably 45%, of the composition and any combination or subcombination of
ranges
therein.
To impart RF dielectric loss to the four component composition, certain
known high dielectric loss ingredients ("RF susceptible polymers") are
included in the
composition. These polymers may be selected from the group of RF polymers in
the
first and second group set forth above.
Other RF active materials include PVC, vinylidine chlorides, and fluorides,
2 0 copolymer of bis-phenol-A and epichlorohydrines known as PHENOXYS~ (Union
Carbide).
The polyamides of the RF susceptible polymer are preferably selected from
aliphatic polyamides resulting from the condensation reaction of di-amines
having a
carbon number within a range of 2-13, aliphatic polyamides resulting from a
condensation reaction of di-acids having a carbon number within a range of 2-
13,
polyamides resulting from the condensation reaction of dimer fatty acids, and
amides
containing copolymers (random, block, and graft). Polyamides are seldom found
in
the layer which contacts medical solutions as they may contaminate the
solution by
leaching out into the solution. However, it has been found by the Applicants
of the
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present invention that the most preferred RF susceptible polymer are a variety
of
dimer fatty acid polyamides sold by Henkel Corporation under the product
designations MACROMELT and VERSAMID, which do not lead to such
contamination. The RF susceptible polymer preferably should constitute by
weight
5 approximately 5-30%, more preferably between 7-13%, and most preferably 10%,
of
the composition and any combination or subcombination of ranges therein.
The fourth component of the composition confers compatibility among the
polar and nonpolar components of the composition (sometimes referred to as a
"compatibilizing polymer") and preferably is styrenic block copolymers with
10 hydrocarbon soft segments. More preferably, the fourth component is
selected from
SEBS block copolymers that are modified by malefic anhydride, epoxy, or
carboxylate
functionalities, and preferably is an SEBS block copolymer that contains
malefic
anhydride functional groups ("functionalized"). Such a product is sold by
Shell
Chemical Company under the designation KRATON~ RP-6509. The compatibilizing
15 polymer should constitute by weight approximately 5-40%, more preferably 7-
13%,
and most preferably 10% of the composition and any combination or
subcombination
of ranges therein.
It may also desirable to add a fifth component of a nonfunctionalized SEBS
block copolymer such as the ones sold by Shell Chemical Company under the
product
designations KRATON G-1652 and G-1657. The fifth component should constitute
by weight approximately 5-40%, and more preferably 7-13% and any combination
or
subcombination of ranges therein.
Another acceptable polymer alloy is a blend of styrene-ethylene-butene-styrene
("SEBS") block copolymer (40%-85% by weight), ethylene vinyl acetate (0-40% by
2 5 weight), and polypropylene ( 10%-40% by weight)
Preferably, the multilayered or monolayer tubing 14 is constructed by an
extrusion process. Other manufacturing methods can also be used to produce a
tube
useful with the present invention although extrusion is preferred.
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16
The multilayered tubing 14 could also include additional layers, if desired.
For
example, it may be desirable to have a tie layer 24 between the inner 22 and
outer
layers 20. (FIG. 2a) The tie layer 24 may be selected from modified
polyolefins, and
modified ethylene and propylene copolymers; such as those sold under the
product
designations ADMER (Mitsui), which is a malefic anhyrdride modified
polypropylene,
PREXAR (Quantum Chemical Co.) and BYNEL (Dupont). The tie layer 24 should
be as thin as practical and have a thickness from 0.0002 inches to 0.003
inches. If
additional layers are used, it.remains important that the hardness of the
inner layer 22
is greater than the hardness of the outer layer 20. Although less critical, it
is also
1 o important that the melt softening temperature range T2 of the inner layer
22 be higher
than the melt softening temperature range T1 of the outer layer 20. Although
it is
possible to form a seal where T1 is greater than or equal to T2 so long as the
method
of welding heats the outer layer to temperature T1 without heating the inner
layer to
temperature T2.
Although a circular-shaped tubing 14 is shown in FIG. 2, other tubing could be
used having other cross-sectional shapes, including oval or polygonal cross-
sections.
To seal a rounded member such as the multilayered tubing 14 between the
planar members 16 of the container 12, the tubing 14 is compressed, without
deflecting the inner layer 22 of the tubing 14 substantially out of round,
using a die
2 0 while applying sealing energies through the die. While the inner layer 22
is not
deflected substantially out of round, the outer layer 20 of the tubing 14 is
compressed.
The sealing process may be carried out using flat dies with an elastomeric
buffer or
shaped welding dies. The dies are typical of those found in industry.
FIG. 3 shows a pair of conventional flat, mating welding dies 32,34 used in
the
heat sealing process. Each die 32,34 has a compressible membrane 36,38
respectively
that has a modulus of elasticity less than that of the tubing. An end portion
14a of the
tubing 14 is positioned between the perimeter edges 18 of the pair of planar
members
16 to define an interface area 26. The interface area 26, as indicated by the
arrows,
includes the area where the planar members 16 bond to the tubing 14. A portion
28 of
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17
each of the planar members 16 extends outward from the interface area 26. It
is of
course possible to apply sealing energies through a single die without
departing from
the spirit of the invention.
As further shown in FIG. 3, the interface area 26 is then positioned between
the pair of flat welding dies 32,34. As shown in FIG. 4, the welding dies
begin to
close to compress the planar members 16 against the end portion 14a of the
tubing 14.
The flexible membranes 36,38 flex around the planar members 16 and the tubing
14.
FIG. S show the welding dies 32,34 fully closed to apply pressure to the
interface area
26. The welding dies 32,34 also apply sealing energies, such as heat, within
to raise
the outer layer to temperature Tl without heating the inner layer to
temperature T2.
As shown in FIG. 5, the welding dies 32,34 fully close and compress the planar
members 16 around the tubing 14. The outer layer 20 of the tubing 14 is
compressed.
Because of the hardness of inner layer 22, even though the welding dies 32,34
are
fully closed; the inner layer 22 is not deflected substantially out of round
(FIG. 5).
As sealing energies are applied to the interface area 26, the outer layer 20
of
the tube 14 begins to melt and outer portions of the outer layer 20 flow
toward end
members 40 of the tubing 14 to supply additional material or fillet material
to the weld
formed in the interface area 26. This improves the weld between the rounded
members 40 and the perimeter edges 18 and further reduces the likelihood of
channel
2 0 leakage.
Specifically, the outer layer 20 of the tubing 14 and perimeter edges 18 of
the
planar members 16 soften and melt together at the interface area 26. Thus, the
planar
members I6 are welded around an entire periphery of the end portion 14a of the
tubing 14. Compressive forces are continually applied until the dies 32,34
contact the
2 5 portion 28 of the planar members, which linearly extend beyond the
interface area 26,
and are welded to each other as well (FIG. S).
After the sealing process is complete, the welding dies 32,34 are opened,
thereby releasing the pressure to the interface area 26. Because the sealing
energy is
applied ~c that the inner layer inner layer 22 does not reach temperature T2,
the inner
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18
layer 22 does not melt. Regardless, because the inner layer 22 is not
collapsed to a
flattened position during the welding process, there is no chance of welding
the inner
22 to itself. After the pressure is released, the tube 14 returns to a
substantially
rounded configuration to provide a pathway for the contents stored in the
container.
An improved weld is provided by compressing the tubing 14 between the
planar members 16 at the time of sealing and melting a portion of the outer
layer 20 of
the tube 14.
In a further attribute of the process, as sealing energy is continually
applied to
the interface area 26 and pressure is applied to the compressed tubing 14, the
outer
layer 20 of the tubing 14 continues to melt, allowing a portion of the outer
layer 20 to
flow and provide fillet material to the weld in the interface area 26. This
further
improves the seal between the outer layer 20 and the planar members 16 because
material can flow to fill any voids or gaps present between the outer layer 20
and
planar members 16.
It should be understood that it is possible to apply sealing energy to a die
prior
to collapsing the tube 14 or afterward depending on the welding techniques
being
used.
The same dies and process described above for sealing multilayered tubing
may also be used to seal the monolayer tubing shown in Figure 2b. For
monolayer
2 0 tubing the dies supply heat to the tubing to melt soften the sealing
portion 90 (Figure
7) of the tubing while the inner portion 92 remains in a relatively solid
state. The melt
softened sealing portion 90 flows along the relatively unsoftened inner
portion 92 of
the tubing to provide fillet material to the weld area.
In a preferred form of the invention, a J-shaped fluid supply line 100 (Figure
7)
2 5 is employed in the sealing process (Figure 8). The fluid supply line 100
functions as a
mandrel, but without requiring an exterior surface 102 of the supply line 100
to
directly contact the tubing sidewall in the interface area 26. The fluid
supply line 100,
which shall be referred to hereafter as mandrel 100, has a descending leg 104,
a
horizontal leg 106, an ascending leg 108, a fluid entry port 110, a fluid exit
port 112
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19
and a fluid passageway 114 connecting the entry and exit ports. An exterior
surface
proximate the fluid exit port 112 tapers 118 to a reduced diameter to fit
within the
fluid passageway 25 of the tubing. In a preferred form, the mandrel 100
delivers air
under pressure to fluid entry port 110 while a portion of the tubing is
crimped 111
either partially or completely to provide axially directed pressure to inflate
the tubing
sidewalls into contact with the sealing dies 32, 34. The air should be
supplied under
pressure within the range of approximately 20-40 psi, more preferably from 25-
35 psi
and most preferably from 2Z-31 psi or any range or subcombination of ranges
therein.
It may also be desirable to include a second fluid passageway 120 in the
mandrel 100 spaced from the first passageway 114 to control the pressure being
supplied the tubing sidewalls. The second fluid passageway 120 can be mounted
in
horizontal or vertical spaced relationship or mounted coaxially. It may also
be
desirable, as shown in Figure 9, to dimension the descending leg 108 of the
mandrel to
fit within the tubing defining air escape passages 122 on one or both lateral
sides of
the mandrel. The air escape passages 122 assist in regulating the pressure
supplied to
the tubing. The air escape passage 122 can also be provided, as shown in
Figure 10,
by positioning a vent 123 in the outer surface of the mandrel.
As shown in Figure 8, the method of using the mandrel 100 in sealing tubing
includes the steps of positioning an end portion of the tubing between
perimeter edges
2 0 of the pair of planar members 16 to define an interface area 26, inserting
the fluid
discharge port of the mandrel into the entry port of the rounded member and
into the
fluid passageway, supplying fluid under pressure through the mandrel 100 into
the
fluid passageway of the tubing to supply a radially directed force to the
inner surface
of the sidewall of the tubing to inflate the tubing, and applying sealing
energy to the
2 5 interface area 26 with the welding die to heat the tubing to a temperature
sufficient to
soften a portion of the rounded member forming a weld between the planar
members
and the tubing in the interface area.
It may also be desirable as shown in Figure 8 to provide a hot 130 and a cold
132 welding die mounted for reciprocating movement with respect to the
interface
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area 26. The hot welding die 130 can be applied first to create a weld and the
cold
welding die 132 can be shuttled to cool the interface area 26.
By way of example, and not limitation, examples of the present invention will
now be given illustrating port or dispensing tubes being sealed between planar
5 members to form fluid containers. The materials in each of these containers
are
- shown in the Table below.
Example 1- a monolayer tubing of ULDPE (Dow PL 8180) was extruded
having an inner diameter of 0.375 inches an outer diameter of 0.438, a wall
thickness
of 0.031 inches and a wall to inner diameter ratio of 0.07. The monolayer
tubing was
10 attached between sidewalls of a multilayer sheeting material having a core
layer 80 of
an ethylene vinyl alcohol copolymer having an ethylene content of 32 mole
percent,
an outer layer of nylon 12 and an inner layer of ULDPE. Tie layers of BYNEL
were
interposed between the core and outer layer and between the core and inner
layers.
The monolayer tubing was inserted between the sheeting material and supplied
with
15 30 psi of pressurized air while a shaped die was closed about the tubing.
The
pressurized air inflated the tubing to come into contact with the welding dies
to create
a weld between the tubing and the sheeting material. The sheeting material was
sealed on four sides to form a fluid tight pouch. The pouch was filled with
water and
no channel leakage was observed.
2 0 Example 2-a multilayered tubing was fabricated by coextruding an outer
layer
of ULDPE (Dow PL 8180) onto an inner layer of PVC (PL 1847). The multilayered
tubing was welded to the sheeting material described in Example 1 and tested
for
channel leakage as described in Example 1. No channel leakage was observed.
Example 3- a monolayer tubing of ULDPE (Dow PL 1880) was extruded
having an inner diameter of 0.188 inches an outer diameter of 0.375, a wall
thickness
of 0.094 inches and a wall to inner diameter ratio of 0.25. The monolayer
tubing was
attached between sidewalk of a multilayer sheeting material having a core
layer 80 of
an ethylene vinyl alcohol copolymer having an ethylene content of 32 mole
percent,
an outer layer of nylon 12 and an inner layer of ULDPE. Tie layers of BYNEL
were
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21
interposed between the core and outer layer and between the core and inner
layers.
The monolayer tubing was inserted between the sheeting material while a shaped
die
was closed about the tubing. The sheeting material was sealed on four sides to
form a
fluid tight pouch. The pouch was filled with water and no channel leakage was
observed.
While specific embodiments have been illustrated and described, numerous
modifications are possible without departing from the spirit of the invention,
and the
scope of protection is only limited by the scope of the accompanying Claims.
