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`
`Ill lllll lllll lllll lllll lllll 111111111111111111111111111111111
`US007883491B2
`
`(12) United States Patent
`Shah
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7 ,883,491 B2
`Feb.8,2011
`
`(54) EXTRUSION LAMINATE POLYMERIC FILM
`ARTICLE AND GASTRIC OCCLUSIVE
`DEVICE COMPRISING SAME
`
`(76)
`
`Inventor: Tilak M. Shah, 104 Lochberry La.,
`Cary, NC (US) 27511
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 983 days.
`
`(21) Appl. No.: 10/815,282
`
`(22) Filed:
`
`Apr.1, 2004
`
`(65)
`
`US 2005/0222329 Al
`
`Prior Publication Data
`Oct. 6, 2005
`
`(51)
`
`Int. Cl.
`A61M 29100
`(2006.01)
`(52) U.S. Cl .
`................. 604/96.01; 604/99.01; 604/916;
`6041920
`(58) Field of Classification Search .............. 428/411.1,
`428/423.1, 424.2, 473.5; 604/96.01, 99.01,
`604/916, 920
`See application file for complete search history.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`3,901,232 A * 8/1975 Michaels et al . ......... 604/892.l
`5,679,423 A
`10/1997 Shah
`5,713,141 A * 2/1998 Mitchell et al. ................ 36129
`5.738,657 A * 4/1998 Bryant et al.
`............... 604/145
`5,833,915 A
`11/1998 Shah
`6,082,025 A * 7/2000 Bonk et al. .................... 36/29
`6.352,077 Bl
`3/2002 Shah
`6,460,541 Bl
`10/2002 Shah et al.
`
`6,663,646 Bl
`Shah
`12/2003
`6,712,832 B2
`Shah
`3/2004
`6,733,512 B2
`512004
`McGhan
`6,976,950 B2 * 12/2005
`Connors et al. ............... 600129
`7,112,186 B2
`Shah
`912006
`7,455,863 B2
`Hamann
`11/2008
`7.470,251 B2
`12/2008
`Shah
`2004/0186502 Al
`912004 Sampson et al.
`
`FOREIGN PATENT DOCUMENTS
`
`JP
`JP
`JP
`JP
`
`51-090376 A
`51-100833 A
`51-101084 A
`10-127771 A
`
`8/1976
`9/1976
`9/1976
`5/1998
`
`OTHER PUBLICATIONS
`
`Jones, E., "Thermoforming", "Modern Plastics Encyclopedia",
`1970, pp. 15, 17, 51, 600-630, 993-994.
`* cited by examiner
`Primary Examiner-Thao T. Tran
`(74) Attorney, Agent, or Finn-Vincent K. Gustafson;
`Intellectual Property/Technology Law
`
`(57)
`
`ABSTRACT
`
`A multilayer film including a layer of sealing film, having
`main top and bottom surfaces, and a layer of thermoplastic
`polymer film, laminated to the layer of sealing film, on at least
`one of the main top and bottom surfaces. The sealing film has
`a composition and thickness imparting gas barrier character
`to the multilayer film, of which the layer( s) of thermoplastic
`polymer film by themselves lack such gas barrier character.
`Such multilayer film is usefolly employed to form biologi(cid:173)
`cally compatible therapeutic articles such as medical balloons
`that are constmcted to be inflated in vivo.
`
`35 Claims, 2 Drawing Sheets
`
`50 \
`
`80
`
`82
`
`Obalon Therapeutics, Inc. Exhibit 1003 Page 1
`
`

`

`U.S. Patent
`
`Feb.8,2011
`
`Sheet 1of2
`
`US 7,883,491 B2
`
`10 \
`
`FIG.1
`
`..,..,,..------....
`'
`\ _________ ,
`k
`/l
`..,( .......
`........
`I - - - - - - - I
`\
`\
`I
`I I
`I 30
`32 -~1'
`I
`I
`.... ________ ,,,
`I
`I
`I
`I
`
`I /
`
`I
`
`/
`
`-
`
`26
`
`24
`
`20_/
`
`FIG.2
`
`Obalon Therapeutics, Inc. Exhibit 1003 Page 2
`
`

`

`U.S. Patent
`
`Feb.8,2011
`
`Sheet 2of2
`
`US 7,883,491 B2
`
`50
`
`\
`
`62
`
`FIG.3
`
`50
`
`\
`
`64
`
`62
`
`80
`
`FIG.4
`
`Obalon Therapeutics, Inc. Exhibit 1003 Page 3
`
`

`

`US 7,883,491 B2
`
`1
`EXTRUSION LAMINATE POLYMERIC FILM
`ARTICLE AND GASTRIC OCCLUSIVE
`DEVICE COMPRISING SAME
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`This invention relates to an extrusion laminate film, and to
`products fonned therefrom having a gas barrier character. In
`a specific embodiment, the invention relates to a gastric 10
`occlusive device fabricated using such film.
`2. Description of the Related Art
`In the field of polymeric film technology, involving poly(cid:173)
`meric sheet stock or web-form material, typically having a
`thickness of less than about 25 mils, there is a need for 15
`gas-barrier films.
`Such gas barrier films may be employed for containment of
`a speeifie gas when used to fonn gas receptacles, or as a
`packaging, cushioning or preservative structure (e.g., when
`fabricated to contain gas species such as oxygen, nitrogen, 20
`argon, helium, carbon dioxide, water vapor, etc). Still other
`applications relate to the prevention or reduction of gas pas(cid:173)
`sage through the film, such as in instances in which any
`significant penetration of gas through the film may adversely
`impact an article, structure, material or region that is isolated 25
`from an adverse gas environment by the gas barrier film.
`In the aforementioned applications, the film material may
`be susceptible to forces and consequent stresses that cause
`failure of the film, e.g., by cracking, tearing, splitting, stress(cid:173)
`softening, embrittlement or other material failure mecha- 30
`nisms.
`Specific applications of such gas barrier films may include
`the requirement ofbiocompatibility, in which the gas barrier
`film is required to fm1ction in or in connection with a physi(cid:173)
`ological environn1ent, whereby the film may be subjected to 35
`exposure to biological fluids, variations of temperature, pres(cid:173)
`sure and pH, etc.
`There is presently a compelling need in the art for readily
`manufacturable, soft and supple yet durable and reliable gas
`barrier films for manufacture of medical devices as well as a 40
`wide variety of other product articles.
`
`SUMMARY OF THE INVENTION
`
`2
`In another aspect, the invention relates to a gas-retentive
`enclosure comprising a multilayer film, wherein the multi(cid:173)
`layer film comprises:
`a layer of sealing film, having main top and bottom sur(cid:173)
`faces; and
`a layer of them1oplastic polymer film, laminated to the
`layer of sealing film, on at least one of the main top and
`bottom surfaces;
`
`wherein the sealing film has a composition and thickness
`imparting gas barrier character to the multilayer film and
`wherein the layer(s) of thermoplastic polymer film alone
`lacks such gas barrier character
`In another aspect, the invention relates to a gastric occlu(cid:173)
`sive device, comprising:
`a balloon formed of a multilayer film comprising:
`a layer of sealing film, having main top and bottom
`surfaces;
`a layer of thermoplastic polymer film, on at least one of
`the main top and bottom surfaces of the layer of seal(cid:173)
`ing film;
`wherein the sealing film has a composition and thickness
`imparting gas barrier character to the multilayer film
`and wherein the layer(s) ofthennoplastic polymeric
`material alone lacks such gas barrier character; and
`an effervescent material contained in said balloon, and
`arranged for contact with introduced liquid reactive with
`the effervescent material to liberate gas for inflation of
`the balloon.
`A still further aspect of the invention relates to a method of
`therapeutic intervention for treatment of a patient in need of
`such treatment, such method comprising:
`introducing to a physiological locus of a patient in need of
`such therapeutic intervention a balloon fonned of a mul(cid:173)
`tilayer film, wherein the multilayer film comprises:
`a layer of sealing film, having main top and bottom
`surfaces; and
`a layer of thermoplastic polymer film, laminated to the
`layer of sealing film, on at least one of the main top
`and bottom surfaces;
`wherein the sealing film has a composition and thickness
`imparting gas barrier character to the multilayer film
`and wherein the layer(s) of thermoplastic polymer
`film alone lacks such gas barrier character;
`
`The present invention relates to a gas barrier film, as well as 45
`to articles and devices incorporating such gas barrier film.
`In one aspect, the invention relates to a multilayer film
`comprising:
`a layer of sealing film, having main top and bottom sur(cid:173)
`faces; and
`a layer of thennoplastic polymer film, laminated to the
`layer of sealing film, on at least one of the main top and
`bottom surfaces;
`wherein the sealing film has a composition and thickness 55
`imparting gas barrier character to the multilayer film and
`wherein the layer(s) ofthennoplastic polymeric material
`alone lacks such gas barrier character.
`In such multilayer film, the thermoplastic polymer film is
`appropriately selected for the specific barrier service to be 60
`acconunodated by the multilayer film. In a preferred embodi(cid:173)
`ment, wherein the multilayer film is employed as a structural
`component of a medical device, the thermoplastic polymer
`film is selected to exhibit biocompatibility, softness to the
`touch and good weldability (for film welding by welding 65
`techniques such as RF impulse welding, hot bar adhesive
`welding, ultrasonic welding, etc.).
`
`with an effervescent material contained in said balloon, and
`arranged for contact with introduced liquid reactive with the
`effervescent material to liberate gas for inflation of the bal-
`50 loon.
`As used herein, the term "film" means a material in a sheet
`or web form, having a thickness of 50 mils (1.270 mm) or less.
`As used herein, the tenn "extrusion laminated" in reference
`to a film of thermoplastic material means that such film of
`them1oplastic material is deposited as an extruded melt film
`on (one or both sides of) the sealing layer film, so that the
`respective thermoplastic material and sealing layer films are
`consolidated with one another lU1der elevated temperature
`conditions. The laminate preferably is formed under process
`conditions producing substantially uniform thickness of the
`multilayer film, with a thickness variation across the lami(cid:173)
`nated film desirably being less than 20% and more preferably
`being less than 15% of the total thickness of the laminate.
`Other aspects, features and embodiments will be more
`fully apparent from the ensuing disclosure and appended
`claims.
`
`Obalon Therapeutics, Inc. Exhibit 1003 Page 4
`
`

`

`US 7,883,491 B2
`
`3
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a perspective view of a gas barrier film according
`to one embodiment of the invention.
`FIG. 2 is a front elevation view of a gastric occlusive
`device, according to one embodiment of the invention.
`FIG. 3 is a schematic front elevation cross-sectional view
`of a vacuum thennoforming die for use in forming a balloon
`article for fabrication of a gastric occlusive device of the type
`shown in FIG. 2.
`FIG. 4 is a schematic cross-sectional elevation view of a
`radio frequency (RF) welding operation by which two
`vacuum thermofonned half-sections fonned in the assembly
`ofFIG. 3 after being mated with one another for consolidation
`at an edge seam, are welded under heat and pressure condi(cid:173)
`tions effecting bonding of the half-sections to one another.
`
`DETAILED DESCRIPTION OF THE INVENTION,
`AND PREFERED EMBODIMENTS THEREOF
`
`The present invention is based on the discovery of a lami(cid:173)
`nated multilayer film structure having utility as a gas barrier
`film, as useful in the fabrication of a wide variety of end-use
`articles, including, without limitation, gastric occlusion
`devices.
`Thus, while the invention is described more fully herein(cid:173)
`after with reference to an illustrative gastric occlusive device,
`as fabricated from the laminated multilayer film of the inven(cid:173)
`tion, it will be appreciated that the inventive film is suscep(cid:173)
`tible of a wide variety of usages, e.g., in applications in which
`the film must contain a gas at pressure at least equal to pres(cid:173)
`sure of an ambient environment of the article incorporating
`such film, or in which penneation of gas through the film
`would adversely affect a structure, article or material on an
`opposite side of the barrier film from such gas.
`The gas barrier film structure of the invention is a laminate
`including:
`a layer of sealing film, having main top and bottom sur(cid:173)
`faces; and
`a layer of thennoplastic polymer film, lan1inated (e.g.,
`extrusion laminated) to the layer of sealing film, on at
`least one of the main top and bottom surfaces;
`wherein the sealing film has a composition and thickness
`imparting gas barrier character to the multilayer film and
`wherein the layer( s) of thennoplastic polymeric material
`alone lacks such gas barrier character.
`The disclosure of U.S. Pat. No. 6,712,832, issued Mar. 30,
`2004 in the name of Tilak M. Shah for "LOW-PRESSURE
`MEDICAL BALLOONS AND METHOD OF MAKING
`SAME," hereby is incorporated herein in its entirety, for all 50
`purposes.
`As disclosed in such earlier application Ser. No. 09/977,
`644, a low-pressure medical balloon can be fabricated by
`providing a thin film of thermoplastic polymeric material that
`is heated to a sufficient temperature for vacuum fonning
`thereof. A first half-section for the balloon then is formed by
`subjecting the thennoplastic polymeric film to vacuum suc(cid:173)
`tion. A second half-section for the balloon then is formed by
`subjecting a same or different thermoplastic polymeric thin
`film to vacuum suction, following which the first half-section
`of the balloon is bonded to the second half-section along
`respective edges thereof to yield the balloon.
`Such methodology may be employed to fonn a low-pres(cid:173)
`sure balloon article of a non-pillowed, generally spherical or
`flattened spherical character, in which the respective half(cid:173)
`sections of the balloon are readily fabricated and mated to
`form the product balloon article. The balloon article as thus
`
`4
`formed may then be everted (turned inside out) so that the free
`edges (flange or "skirt") of the seam are disposed in the
`interior volume of the balloon.
`The laminate of the present invention is fonned with an
`outer layer (on one or both sides of the sealing film) of a
`thennoplastic polymeric film material, such as polyurethane
`elastomer, polyester ether elastomer, polyamide elastomer,
`etc., having good physical properties for the intended end(cid:173)
`use, but which is gas-penneable to an undesired extent, in
`1 o respect of its intended end-use application. The thermoplastic
`polymer film may have any suitable thickness, e.g., a thick(cid:173)
`ness in a range of from about 2.0 mils to about 20 mils (0.0508
`mm to 0.508 mm), although greater or lesser thicknesses may
`be employed in specific applications of the invention, e.g., a
`15 thickness in a range of from about 2.0 mils to about 5.0 mils
`(0.0508 mm to 0.127 mm).
`The laminate includes a layer of a sealing film. A layer of
`thennoplastic material is laminated, e.g., extrusion lami(cid:173)
`nated, on at least one of the main top and bottom surfaces of
`20 the sealing layer. The sealing film layer has a composition and
`thickness imparting gas barrier character to the laminated
`film structure. In other words, the presence of the sealing film
`effects a diminution of the gas penneability characteristics of
`the laminate (relative to the gas penneability characteristics
`25 of the outer thermoplastic material layer(s) per se), in respect
`of particular gas components or gas mixtures of interest, so
`that the resulting multilayer laminate is suitable for use as a
`gas barrier.
`Polyurethane elastomer is a preferred material of construc-
`30 ti on for the outer layer( s) of the laminated film, although a
`wide variety of other materials, such as polyester ether elas(cid:173)
`tomer, stryenic elastomers, polyan1ide and polyamide elas(cid:173)
`tomers and other film-forming thermoplastic elastoplastics,
`incuding the polymeric families of polyethylene, polypropy-
`35 lene, polyvinylchloride (PVC), polyvinylether (PYE), ethyl(cid:173)
`ene vinyl acetate (EVA) polymers, and combinations of two
`or more of the foregoing, etc., may be employed. The choice
`of a specific thennoplastic material for a given end use appli(cid:173)
`cation, and the choice of extrusion laminating a layer of such
`40 thennoplastic material to only one, or alternatively to both, of
`the surfaces of the sealing film layer, can readily be made
`within the skill of the art, and without undue experimentation,
`based on the disclosure herein.
`The multilayer laminated film of the present invention is
`45 readily processed in the mam1er described in the aforemen(cid:173)
`tioned U.S. patent application Ser. No. 09/977,644, to forn1
`balloon and catheter articles of widely varying types.
`For example, a multilayer extrusion laminated film of the
`invention may be utilized to form low-pressure balloons and
`catheters useful for a wide variety of procedures, such as
`minimally invasive surgery.
`In medical balloon usage, it is important that the balloon
`structure have uniform wall thickness and concentric expan(cid:173)
`sion during inflation, so that the physiological effect is cor-
`55 respondingly uniform and able to be well-standardized and
`quantified.
`The multilayer extrusion laminated films of the invention
`are particularly useful in the fabrication of balloon articles
`such as the gastric occlusive device hereinafter more folly
`60 described. In such application, the extrusion laminated film
`can have a thickness in a range of from about 0.5 to about I 0
`mils (0.0127 mm to 0.254 mm), and more preferably in a
`range of from about 2 mils to about 6 mils (0.0508 mm to
`0.1524 mm), although greater or lesser thicknesses of the
`65 extrusion laminated film may be employed, e.g., a thickness
`in a range of from 0.5 to about 50 mils (0.0127 mm to 1.27
`mm), as appropriate in a specific end-use application.
`
`Obalon Therapeutics, Inc. Exhibit 1003 Page 5
`
`

`

`US 7,883,491 B2
`
`5
`111e sealing film layer, on which at least one outer layer of
`them10plastic material is laminated in the laminated film of
`the invention, may be of any suitable type that is effective to
`impart gas barrier characteristics to the laminate. As indi(cid:173)
`cated, the outer layer can be formed of a material such as a
`polyurethane elastomer or other suitable thermoplastic elas(cid:173)
`tomer.
`The sealing layer in relation to specific outer layer thermo(cid:173)
`plastic materials can be fabricated of any complementary
`material imparting gas barrier characteristics to the overall 10
`laminated film that includes the outer layer(s) and the sealing
`layer. Illustrative sealing layer materials include polyvi(cid:173)
`nylidene chloride (PVDC), collllllercially available from
`Dow Chemical Company under the trademark Saran, polyvi(cid:173)
`nylidene bromide, ethylene vinyl alcohol polymers ( conven- 15
`tionally referred to as "EVOH" polymers), etc.
`T11e sealing film can be of any suitable thickness as
`required for the gas barrier end-use application. Typically,
`when polyvinylidene chloride or EVOH polymers are
`employed to form the sealing film, the sealing film can have a 20
`thickness on the order of from about 0.2 mil to about 6 mil
`(0.00508 mm to 0.1524 mm).
`In an illustrative embodiment, the outer layer of the extru(cid:173)
`sion laminate is fanned of a sealing layer of polyvinylidene
`chloride, having a thickness in a range of from about 0.25 to 25
`about 2.0 mil (0.00635 nun to 0.0508 nun), to which a layer
`of polyurethane elastomer film, having a thickness in a range
`of from about 2.0 mils to about 5.0 mils (0.0508 nun to 0.127
`nun), is extrusion bonded.
`It will be appreciated that when the multilayer laminate of 30
`the invention features two outer layers of thermoplastic poly(cid:173)
`meric material, each laminated to the sealing layer on a
`respective surface of the sealing layer, the outer layers of
`thermoplastic material may be the same as or different from
`one another in composition. For example, a polyurethane 35
`elastomeric film may be extrusion laminated to one face of a
`polyvinylidene chloride film, and a polyethylene film may be
`extrusion laminated to the other face of the polyvinylidene
`chloride film.
`It will also be appreciated that the thermoplastic material 40
`layer may include multiple sub-layers, and that the sealing
`layer may likewise include multiple sub layers, and that these
`respective sub-layers may be compositionally homogeneous
`or alternatively varied in composition along the successive
`sub-layers.
`The lan1inate of the invention may be utilized to form a
`gastric occlusive device, as hereinafter more fully described.
`The gastric occlusive device is a balloon that is fabricated to
`contain a charge of an effervescent material that in the pres(cid:173)
`ence of wateror moisture reacts to form C02 gas. The balloon 50
`containing such effervescent material charge can be injected,
`through the multilayer film via a suitable self-healing seal
`valve therein, with a requisite amount of water or aqueous
`medium. The injected water or aqueous medium then reacts
`with the effervescent material, to generate carbon dioxide as 55
`an inflation gas for the balloon.
`The balloon of the gastric occlusive device thus is inflated
`subsequent to being placed in a gastric locus of a patient. The
`inflated balloon thereafter remains sufficiently gas-tight in
`character so that the inflated volume of the balloon is rela- 60
`tively constant over an extended period of time.
`In one embodiment, the balloon is formed with a degrad(cid:173)
`able seal, which under exposure to a physiological environ(cid:173)
`ment degrades to pennit deflation of the balloon and removal
`thereof from a physiological locus.
`In one preferred dimensional aspect, the gastric occlusive
`balloon has a diameter when inflated of 3 to 5 inches,
`
`6
`although such balloon in the general practice of the invention
`may have any suitable size and dimensional characteristics
`appropriate to the use of the balloon in a specific application
`thereof.
`In a physiological environment, the balloon article of the
`invention must withstand pressures associated with such
`environment, e.g., pressures of 1 to 5 psi. Further, the physi(cid:173)
`ological environment may subject the balloon article to com-
`pressive, tensile and torsional forces.
`Under such conditions in the physiological locus, the mul(cid:173)
`tilayer laminate must be resistant to flex-cracking, particu(cid:173)
`larly when such conditions involve repeated cycles of shape(cid:173)
`deforming stresses. The selection of film thickness of the
`laminate is particularly critical in this respect, since exces(cid:173)
`sively thick films are disproportionately more susceptible to
`flex-cracking, particularly at the seams where adjacent panels
`or sections of a film are bonded to one another.
`Thus, the balloon article incorporates a multilayer laminate
`that has desired characteristics for the intended use applica(cid:173)
`tion. These characteristics may variously include softness to
`the touch (e.g., a Shore D hardness of 65 or less), resistance to
`flex fatigue, and leak-tightness and dimensional stability
`under the range of pressure conditions that may be encoun(cid:173)
`tered in such intended use application.
`Balloon or other gas-retentive or gas barrier articles in
`accordance with the invention can alternatively be formed
`using conventional multilayer barrier films, which are pro(cid:173)
`cessed as described herein. Barrier films including at least one
`layer of urethane material are advantageously processed as
`described herein to form balloon articles from half-sections
`that are produced by vacunm forming, e.g., vacunm thermo-
`forming, and then bonded at their outer periphery to form a
`balloon article without openings in the weld line or any other
`location on the dome of the respective half-sections in the
`finished article.
`Conventional multilayer barrier films of such type may be
`manufactured either by co-extrusion of sealing layer( s) with
`outer layer(s ), with or without adhesive, or by preformed film
`of outer layers adhesive laminated to preformed film of seal(cid:173)
`ing layers. For example, co-extruded films of3-4 layers can
`be utilized.
`Referring now to the drawings, FIG. l is a perspective view
`of an extruded laminate film 10 according to one embodiment
`of the invention.
`The extruded laminate film 10 includes outer film layers 14
`and 16 of thermoplastic material, which have been extrusion
`laminated to a sealing layer film 12.
`The outer film layers 14and16 of thermoplastic material
`may comprise a polyurethane elastomer film, or other ther(cid:173)
`moplastic elastomer film, or any other thermoplastic material
`film that is gas-pervious in character and by itself has inad-
`equate gas barrier character for the desired end use. The
`sealing layer, on which the thermoplastic material layers are
`extrusion laminated, provides a gas barrier film imparting the
`requisite gas-impervious character to the overall laminate for
`the intended use application.
`While the laminate ofFIG. l is shown as comprising three
`layers, i.e., the outer layers of gas-pervious film material and
`the central layer of sealing film material, it will be recognized
`that the invention is not limited to such three-layer film con(cid:173)
`structs, but may comprise two layers, or alternatively more
`than three layers of material, including at least one outer layer
`of gas-pervious film and a sealing film layer imparting gas
`barrier character to the multilayer laminate. In multiple layer
`65 laminated films having three or more layers, the additional
`layers may be formed of any suitable material, to achieve any
`additional required mechanical or chemical resistance prop-
`
`45
`
`Obalon Therapeutics, Inc. Exhibit 1003 Page 6
`
`

`

`US 7,883,491 B2
`
`7
`erties, and such additional layers may be extrusion laminated
`over the sealing film layer and/or outer layer(s), during the
`fabrication of the laminate.
`In a specific embodiment a three-layer film of the type
`shown in FIG. 1 includes outer layers 14 and 16 of polyure(cid:173)
`thane elastomer, having a thickness of about 2 mils (0.0508
`mm), and a sealing layer 12 of polyvinylidene chloride film
`having a thickness of about 1.35 mil (0.0343 mm).
`FIG. 2 is a front elevation view of a gastric occlusive
`device, according to one embodiment of the invention.
`The gastric occlusion device 20 includes a balloon 18
`formed from half-sections 22 and 24, which are joined to one
`another at edge seam 26 to form an enclosed interior volume
`28 of the balloon. The seam 26 may be formed by any suitable
`type of bonding technique. A preferred bonding technique is 15
`radio frequency welding, as discussed hereinafter.
`T11e two pieces of the balloon (half-sections 22 and 24) are
`preferably bonded circumferentially to one another to form a
`360° seal having a seam devoid of any neck or opening
`therein.
`The balloon is shown in its inflated form, in which the
`interior volume 28 contains a head piece 30 bonded to an
`inside surface of the upper balloon half-section 22. Joined to
`the head piece 30 is a gas pill 32 holding an effervescent
`material. The head piece and laminated film are joined to one 25
`another by any suitable bonding means and/or method, and
`their junction suitably includes a self-healing seal valve
`through which water or moisture or other aqueous medium
`may be introduced to contact the effervescent material in the
`gas pill 32, e.g., from an associated catheter or liquid feed 30
`tube (not shown in FIG. 2).
`The effervescent material in the gas pill 32 can be of any
`suitable type that in contact with water, moisture, or physi(cid:173)
`ological media reacts to liberate carbon dioxide or other
`inflating gas forthe balloon, so that the balloon is transformed 35
`from an initial collapsed (deflated) state to the inflated state
`illustratively shown in FIG. 2.
`By way of example, the effervescent material can be a
`mixture of aspirin, sodium bicarbonate and citric acid, or
`other suitable material generating C02 in the presence of 40
`water, moisture or physiological media.
`The balloon may also include a degradable seal if desired,
`which can be successively deteriorated by a physiological
`environment in which the balloon is deployed, so that the
`balloon deflates after a predetermined period of time, and can 45
`be more easily be removed, e.g., mechanically or physiologi(cid:173)
`cally, from the corporeal locus of deployment.
`For example, a degradable seal may be formed of an
`ethelene vinyl acetate (EVA)/hydroxycellulose blended
`material that is progressively degradable to create an opening 50
`in the balloon after a prolonged period of exposure to a
`physiological environment, at a thickness pem1itting the bal(cid:173)
`loon to remain in an inflated state for a period of time suffi(cid:173)
`cient for the desired treatment to be effected. Upon deterio(cid:173)
`ration of the seal, an opening is produced in the balloon that 55
`permits the inflation gas to egress, and the deflated balloon
`may then be readily removed from the corporeal locus in
`which treatment is being carried out.
`FIG. 3 is a front elevation cross-sectional view of a vacuum
`forming assembly 50 for forming a balloon article of the type 60
`shown in FIG. 2.
`The assembly 50 includes a thermoforming die 52. The die
`has a block-like body 52 with a generally hemispherical cav(cid:173)
`ity 54 therein, whose surface 60 communicates through gas
`withdrawal passages therein with the gas extraction plenum
`56. The gas extraction plenum 56 communicates in turn with
`discharge passage 58. The discharge passage 58 can be
`
`8
`coupled with a suitable vacuum source (not shown in FIG. 3),
`such as a vacuum pump, for extraction of gas from the ther(cid:173)
`moforming cavity when overlaid by the extrusion laminate
`film 62. Under the negative pressure imposed by the vacuum
`source, the central portion of the multilayer film 62 is drawn
`into the die cavity as shown, against the die cavity surface 60,
`and the evacuated gas is discharged from the die via the
`discharge passage 58 in the direction indicated by arrow A.
`The extruded laminate film 62 in such processing is at
`10 sufficient temperature for vacuum thermoforming, i.e., a tem(cid:173)
`perature above the softening temperature of the thermoplastic
`polymeric material. Such temperature preferably is above the
`Vicat softening temperature of the thermoplastic polymeric
`laminate material, but below the deformation temperature of
`such laminate material. The Vicat softening temperature of
`polyurethane elastomers, for example, is usually from about
`60° to about 150° C., depending on the nature of the specific
`polymer involved.
`The Vicat softening temperature is readily determinable
`20 within the skill of the art without undue experimentation, for
`any of various other suitable thermoplastic polymeric mate(cid:173)
`rials that may be employed in the extruded laminate.
`By applying negative pressure to the mold cavity so that the
`heated and softened thermoplastic polymeric laminate film is
`induced to conform to the shape of the mold cavity, the
`laminate is vacuum-molded to the required generally hemi-
`spherical shape. In lieu of the female mold structure shown in
`FIG. 3, a male mold may alternatively be employed to form
`the respective half-sections of the ballon article.
`The first and second half-sections of the balloon can be
`formed simultaneously, or they may be formed sequentially.
`The same sheet or web stock of extruded laminate material
`may be employed for such purpose, or different sheets of
`thermoplastic polymeric laminates may be employed, as
`illustrated.
`After thermo-vacuum molding two half-sections of the
`balloon by the arrangement shown in FIG. 3, the half-sections
`can be superimposed and bonded together at their margins
`(edges) by any of various suitable bonding methods, as for
`example the radio frequency welding method that is illus(cid:173)
`trated schematically in FIG. 4.
`FIG. 4 shows a base mold 80 having the superimposed
`multilayer laminate films 62 and 64 arranged in the cavity 82
`so that the generally hemispherical half-sections of such films
`are in register with one another, with the head piece 30 and gas
`pill 32 assembly therebetween.
`The radio frequency welding die 70 is shown disposed
`above the base mold 80 and in position for downward trans(cid:173)
`lation in the direction indicated by arrows M, to weld films 62
`and 64 to one another at the circumferentially extending weld
`region 66 by contact of the circumferentially extending weld-
`ing ring 72 with the superposed film layers. Subsequent to
`such welding, the welded films may be removed from the
`cavity 82, and the welded sphere can be trimmed adjacent the
`outer periphery of the weld region 66, to yield the balloon
`article.
`Although radio frequency welding is a preferred technique
`for bonding of the respective half-sections of the balloon to
`one another, any of various other suitable bonding techniques
`may be employed in the broad practice of the present inven(cid:173)
`tion