METHOD OF SEALING A TUBE IN A CONTAINER

Abstract: The present invention provides a method of sealing a rounded member (14), having a first fluid passageway (25) defining an inner diameter of the rounded member (14), between planar members (16). The steps include: positioning the rounded member between the planar members (16) to define an interface area (26); providing fluid under pressure to the first fluid passageway (25); and heating the interface area (26) to form a weld between the rounded member (14) and the planar members (16).

Description: Description 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 IN. 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. IN. bags are most commonly fabricated from polymers such as polyvinyl chloride, ethylene vinyl acetate, or polyolefm alloys, such as those disclosed in commonly assigned U.S. Patent No. 5,686,527. The IN. 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. 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, 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 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. 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 sidewalk 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 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. 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 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 present invention; 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 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 FIG. 10 is an end view of another embodiment of a mandrel of the present invention. 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 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 the 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. 1 and 3) to define a fluid compartment 23 therebetween. The planar members 16 can be constructed from a number of different materials including poly vinyl chloride, polyolefins, polyolefm copolymers, polyolefm 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 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 preferably, the ethylene copolymer is an ultra-low density polyethylene (ULDPE) having a density of from about 0.880-0.910 g/cm 3 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 opposed to the Ziegler-Natta type catalyst which are known to have a mixture of 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, polyolefm copolymers, polyolefm 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 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 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. 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 1, 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 polyolefm 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 copolymer; a solution contact layer 82 of a polyolefm 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 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 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, polyolefm 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 6J0 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 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 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 α-olefin copolymers especially ethylene-butene-1 copolymers which are commonly referred to as ultra-low density polyethylenes (ULDPE). Preferably the ethylene -olefin copolymers are produced using metallocene catalyst systems. Suitable metallocene catalyzed ethylene α-olefins are sold by Dow under the tradename AFFINITY, and by Exxon under the tradename EXACT. The ethylene α-olefins preferably have a density from 0.880- 0.910 g/cc. Suitable tie layers include modified polyolefins blended with unmodified polyolefins. The modified polyolefins are typically polyethylene or polyethylene copolymers. The polyethylenes can be ULDPE, low density (LDPE), linear low 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, maleic acid, fumaric acid, itaconic acid, citraconic acid, allylsuccinic acid, cyclohex-4-ene-l ,2- dicarboxylic acid, 4-methylcyclohex-4-ene-l,2-dicarboxylic acid, bicyclo[2.2J]hept- 5-ene-2,3-dicarboxylic acid, x-methylbicyclo[2.2J]hept-5-ene-2,3-dicarboxylic acid, maleic anhydride, itaconic anhydride, citraconic anhydride, allylsuccinic anhydride, citraconic anhydride, allylsuccinic anhydride, cyclohex-4-ene-l,2-dicarboxylic anhydride, 4-methylcyclohex-4-ene-l,2-dicarboxylic anhydride, bicyclo[2.2J] hept-5- ene2,3-dicarboxylic anhydride, and x-methylbicyclo[2.2J] hept-5-ene-2,2- dicarboxylic anhydride. Examples of other grafting monomers include C,-C 8 alkyl esters or glycidyl 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 carboxylic acids such as acrylamide, methacrylamide, maleicmonoamide, maleic diamide, maleic N-monoethylamide, maleic N,N-diethylamide, maleic N- monobutylamide, maleic 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 polyolefm is modified by a fused ring carboxylic anhydride and most preferably a maleic anhydride. The unmodified polyolefins can be selected from the group consisting of ULDPE, LLDPE, MDPE, HDPE and polyethylene copolymers with vinyl acetate and acrylic acid. Suitable modified polyolefm 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 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 polyolefm alloys disclosed in commonly assigned U.S. Patent No. 5,686,527 which is incorporated herein by reference and made a part hereof. For 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 OJ 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 polyolefm. 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 polyolefm 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 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 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 ethylene methyl acrylate with methyl acrylate within the range of 15-25% 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 maleic 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 maleic 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, 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 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 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. 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 polyolefm different than that of the first component wherein it contains no propylene repeating units ("non propylene based polyolefm"). 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-1 130 (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-1, 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, 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 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 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 hydrocarbon soft segments. More preferably, the fourth component is selected from SEBS block copolymers that are modified by maleic anhydride, epoxy, or carboxylate functionalities, and preferably is an SEBS block copolymer that contains maleic anhydride functional groups ("functionalized"). Such a product is sold by Shell Chemical Company under the designation KRATON® RP-6509. The compatibilizing 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 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. 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 maleic 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 important that the melt softening temperature range T2 of the inner layer 22 be higher than the melt softening temperature range Tl of the outer layer 20. Although it is possible to form a seal where Tl is greater than or equal to T2 so long as the method of welding heats the outer layer to temperature Tl 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 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 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. 5 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 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 16 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 portion 28 of the planar members, which linearly extend beyond the interface area 26, and are welded to each other as well (FIG. 5). 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 εc that the inner layer inner layer 22 does not reach temperature T2, the inner 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 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) 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 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 27-31 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 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 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 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 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 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 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. 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 0J 88 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 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 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.

Claims: CLAIMS We Claim: 1. A method of connecting rounded members between planar members comprising the steps of : providing a rounded member having a first end and a second end, a sidewall defining a fluid passageway and an inner surface, the rounded member further having an entry port to the fluid passageway at the first end of the rounded member and a radius; providing a pair of planar members; positioning the planar members in opposed relationship; positioning an end portion of the rounded member between perimeter edges of the pair of the planar members to define an interface area; providing a fluid supply tube having a fluid discharge port; inserting the fluid discharge port of the fluid supply line into the entry port of the rounded member and into the fluid passageway; supplying fluid under pressure through the fluid supply line into the fluid passageway of the rounded member to supply a force to the inner surface of the sidewalls of the rounded member directed along the radius; providing a welding die; and applying sealing energy to the interface area to heat the rounded member to a temperature sufficient to soften a portion of the rounded member forming a weld between the planar members and the rounded member in the interface area. 2. The method of claim 1 wherein the rounded members are of a polymeric material. 3. The method of claim 2 wherein the planar member have a multilayered structure. 4. The method of claim 3 wherein the planar members have a core layer of an ethylene vinyl alcohol copolymer having an ethylene content of about 25-45 mole percent; a solution contact layer of a polyolefm positioned on a first side of the core layer; and an outer layer positioned on a second side of the core layer opposite the solution contact layer, the outer layer being selected from the group consisting of polyamides, polyesters and polyolefins. 5. The method of claim 4 wherein the planar members further comprise: two tie layers, one of each adhered on opposite sides of the core layer and positioned between the solution contact layer and the core layer and between the outer layer and the core layer. 6. The structure of claim 4 wherein the polyamide is 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 amide containing copolymers. 7. The structure of claim 6 wherein the polyamide is selected from the group of polyamides produced in a ring-opening reaction of lactams having from 4-12 carbons. 8. The structure of claim 7 wherein the polyamide is nylon 12. 9. The structure of claim 4 wherein the polyolefm of the solution contact layer is selected from the group consisting of homopolymers and copolymers of alpha- olefins containing from 2 to about 20 carbon atoms. 10. The structure of claim 9 wherein the polyolefm of the solution contact layer is a homopolymer or a copolymer of an alpha-olefin having from 2 to about 10 carbons. 11. The structure of claim 10 wherein the polyolefm is selected from the group consisting of ethylene copolymers, and butene-1 copolymers. 12. The structure of claim 11 wherein the ethylene copolymer of the solution contact layer is an ethylene-butene-1 copolymer. 13. The structure of claim 12 wherein the ethylene copolymer of the solution contact layer is produced using a metallocene catalyst. 14. The structure of claim 5 wherein the tie layer is a polyolefm polymer or copolymer blended with a polyethylene copolymer grafted with a carboxylic acid anhydride or a carboxylic acid. 15. The structure of claim 14 wherein the carboxylic acid anhydride is an unsaturated fused-ring carboxylic acid anhydride. 16. The structure of claim 15 wherein the carboxylic acid anhydride is a maleic anhydride. 17. The method of claim 2 wherein the rounded member is a monolayer polymeric structure. 18. The method of claim 17 wherein the monolayer polymeric structure is a polyolefm. 19. The method of claim 18 wherein the polyolefm is selected from the group comprising homopolymers and copolymers of alpha-olefin copolymers. 20. The method of claim 19 wherein the polyolefin is selected from the group of ethlyene and alpha olefin copolymers. 21. The method of claim 20 wherein the ethylene and alpha-olefin copolymer is produced using a single site catalyst. 22. The method of claim 20 wherein the ethylene and alpha-olefin copolymer is produced using a vanadium catalyst. 23. The method of claim 2 wherein the rounded member has a tan delta measured in accordance with ASTM Standard No. D 4065-95 of from 0-0.08. 24. The method of claim 17 wherein the monolayer structure has a wall thickness and an inner diameter wherein the ratio of the wall thickness to the inner diameter is greater than 0.20. 25. The method of claim 2 wherein the rounded member is a multilayered polymeric structure. 26. The method of claim 25 wherein the multilayered polymeric structure has an outer layer and an inner layer, the outer layer is selected from the group comprising polyolefins and the inner layer is selected from the group comprising polyolefins, polyolefin copolymers, polyolefin alloys, polyamides, polyesters, polyvinyl chloride and polyester-polyether block copolymers. 27. The method of claim 26 wherein the outer layer is an ethylene-alpha olefin copolymer and the inner layer is polyvinyl chloride. 28. A method of sealing a rounded member, having a first fluid passageway defining an inner diameter of the rounded member, between planar members comprising the steps of: positioning the rounded member between the planar members to define an interface area; providing fluid under pressure to the first fluid passageway; and heating the interface area to form a weld between the rounded member and the planar members. 29. The method of claim 28 wherein the step of providing fluid under pressure comprises the step of providing air under pressure. 30. The method of claim 28 wherein the step of providing fluid under pressure comprises the step of providing liquid under pressure. 31. The method of claim 30 wherein the liquid is water. 32. The method of claim 31 further comprising the step of heating the water to below the melting point of the tubing but above the glass transition temperature of the tubing prior to the step of providing the fluid under pressure. 33. The method of claim 28 wherein the step of providing fluid under pressure comprises the steps of: providing a fluid supply line having an outer surface that is dimensioned to fit within the inner diameter of the rounded member, a second fluid passageway and an exit port; supplying pressurized fluid through the second fluid passageway of the supply line to the first fluid passageway; and inhibiting the flow of the pressurized fluid through the first fluid supply line to provide radially directed forces to the rounded member. 34. The method of claim 33 wherein the step of inhibiting the flow of pressurized fluid through the first fluid supply line comprises the step of crimping the rounded member to restrict the flow of fluid through the first fluid passage. 35. The method of claim 28 wherein the step of heating the interface area comprises the step of: providing a die; and generating heat in the interface area with the die sufficient to melt soften the planar members and an outer portion of the tubing to form a weld therebetween. 36. The method of claim 35 wherein the step of generating heat in the interface area with the die comprises the steps of: heating the die; and conducting heat from the die to the interface area. 37. The method of claim 35 wherein the step of generating heat in the interface area with the die comprises the steps of: generating radio frequency energy with the die; directing the radio frequency energy to the interface area to induce heat in the interface area. 38. The method of claim 28 wherein the rounded member has a tan delta as measured by ASTM Standard No. D 4065-95 of from 0-0.08. 39. A method of sealing a monolayer tubing between planar members comprising the steps of: positioning the monolayer tubing between the planar members to define an interface area, the monolayer tubing having a wall thickness and an inner diameter wherein the ratio of the wall thickness to the inner diameter is greater than 0.20.; providing a pair of planar members; positioning the planar members in opposed relationship; positioning an end portion of the rounded member between perimeter edges of the pair of the planar members to define an interface area; providing a welding die; and applying sealing energy to the interface area to heat the rounded member to a temperature sufficient to soften a portion of the rounded member forming a weld between the planar members and the rounded member in the interface area. 40. The method of claim 39 wherein the monolayer polymeric structure is a polyolefin. 41. The method of claim 40 wherein the polyolefin is selected from the group comprising homopolymers and copolymers of alpha-olefin copolymers. 42. The method of claim 41 wherein the polyolefin is selected from the group of ethylene and alpha olefin copolymers. 43. The method of claim 42 wherein the ethylene and alpha-olefin copolymer is produced using a single site catalyst. 44. The method of claim 42 wherein the ethylene and alpha-olefin copolymer is produced using a vanadium catalyst. 45. The method of claim 39 wherein the rounded member has a tan delta measured in accordance with ASTM Standard No. D 4065-95 of from 0-0.08. 46. A method of sealing a multiple layered tubing between planar members comprising the steps of: positioning the multiple layered tubing between the planar members to define an interface area, the multiple layered tubing having an outer layer having a melt softening temperature of Tl and an inner layer having a melt softening temperature of T2; providing a pair of planar members; positioning the planar members in opposed relationship; positioning an end portion of the rounded member between perimeter edges of the pair of the planar members to define an interface area; providing a welding die; and applying sealing energy to the interface area to heat the outer layer to temperature Tl while maintaining the inner layer at a temperature below T2 thereby forming a weld between the planar members and the rounded member in the interface area. 47. The method of claim 46 wherein the outer layer is selected from the group comprising polyolefins and the inner layer is selected from the group comprising polyolefins, polyolefin copolymers, polyolefin alloys, polyamides, polyesters, polyvinyl chloride and polyester-polyether block copolymers. 48. The method of claim 47 wherein the outer layer is an ethylene-alpha olefin copolymer and the inner layer is polyvinyl chloride.

Inventors: BUCHANAN BRADLEY, ROSENBAUM LARRY A, SMITH SYDNEY T, BUCHANAN, BRADLEY, ROSENBAUM, LARRY, A., SMITH, SYDNEY, T.
Applicants: BAXTER INT, BUCHANAN BRADLEY, ROSENBAUM LARRY A, SMITH SYDNEY T, BAXTER INTERNATIONAL INC., BUCHANAN, BRADLEY, ROSENBAUM, LARRY, A., SMITH, SYDNEY, T.
Application year: 2000
Main classification: B29C65
IPC codes: A61J1, B29C65, B29L22, B32B1, B32B27