Gas impermeable, elastically deformable laminate and inflatable articles formed therefrom

Abstract: An inventive laminate is provided useful in forming inflatable articles, such as rafts and kayaks, automobile safety bags, air craft and life saving jackets/vests, and diving buoyancy compensator vests. The laminate includes an elastomer layer capable of repeated two-dimensional stretch and retraction. Opposed to the elastomer layer is a first substantially gas impermeable layer. The two layers are substantially continuously adhered to one another and maintained in laminated form. Buoyancy compensators formed from the laminate can be repeatedly stretched and retract to accommodate substantial volume increases due to elastic deformations in response to elevated pressures. Because the laminate is elastically deformable, lower inflation pressures can be used in an article such as a buoyancy compensator, which results in a more comfortable garment.

Description: Field of the Invention : The present invention generally relates to inflatable articles formed of a laminate that is gas impermeable and elastically deformable, and particularly relates to a laminate used in forming a buoyancy compensator vest that is more comfortable to the user due to an ability to use lower inflation pressures. Background of the Invention : Divers usually wear jackets, or vests, to achieve neutral or slightly positive buoyancy at various depths. The vest typically includes a buoyancy compensator chamber which the diver can selectively pressurize from the diver's air tank in order to adjust buoyancy under water. The buoyancy compensator normally also has an associated pressure relief valve. Various diving vests with buoyancy compensators are known, such as described by U.S. Patent 4,016,616, issued April 12, 1977, inventor Walters; U.S. Patent 4,561,853, issued December 31, 1985, inventors Faulconer and Langton. However, previous buoyancy compensator devices have tended to be tight, highly inflated in use, and rather uncomfortable, particularly because during exposure to wave impact air is forced out of the associated relief valve which usually means that the chambers are typically inflated to a high pressure level. One approach to increasing diver comfort has been to provide a soft backpack with a liquid-filled bladder that can be secured to a buoyancy compensator, such as is described by U.S. Patent 4,952,095, issued August 28, 1990, inventor Walters. Another approach (a life jacket design) is described by U.K. patent Application 8725209, published May 25, 1988, in which relatively flat inflatable panels are described. However, diver comfort remains an objective for which improvements continue to be sought for diving applications. Materials for making diving suits are known for example from DE-A-1 506 338 and GB-A-2 021 040. In the former document the laminate material comprises an impermeable, elastic sheet of neoprene rubber adhered to an elastomeric fabric (eg. cellular polyurethane or polyester), while the laminate material of the latter document comprises a permeable central core layer of elastomeric fabric sandwiched between two layers of rubber. Further known laminate materials, for use in making upholstered furniture and shoe uppers are known for instance from US-A-3 948 702 and US-A-4 229 472. Summary of the Invention : Accordingly, it is one object of the present invention to provide a laminate that is substantially gas impermeable and elastically deformable and that can be formed into a wide variety of inflatable articles having different stretch and strength needs, Particularly relatively high pressure inflatables having good cycle life. In one aspect of the present invention, an article comprises a laminate that includes an elastomer layer capable of repeated stretch and retraction. Opposed to the elastomer layer is a first substantially gas impermeable layer which is a continuous polymeric film at least 0.0635 mm (2.5 mil) thick, and the two layers are substantially continuously adhered to one another and maintained in laminated form by adhesive means. In a particularly preferred embodiment of the inventive article, the laminate forms an elastically deformable surface for receiving and containing gas therein, such as buoyancy gas as part of a SCUBA diver's vest, a dry suit or a semi-dry suit. Other embodiments for the inventive laminates include various inflatable articles, such as rafts and kayaks, automobile safety bags, diving suits, swimming learning vests, aircraft and life saving jackets and vests, medical therapeutic containers, waders, and the like. Brief Description of the Drawings : Figure 1 illustrates, in cross-section, a laminate embodiment of the invention; Figure 2 is a perspective of a buoyancy compensator with which the inventive laminate is useful; and Figure 3 is a sectional view in the direction of lines 3-3 of Fig. 2 showing a chamber for containing buoyancy compensating gas. Detailed Description of the Preferred Embodiments : Laminates of this invention include an elastomer layer, a substantially gas impermeable layer, and adhesive means for adhering the layers to one another, and can be used to form all or part of a wide variety of articles. With reference to Fig. 1, a laminate embodiment 10 is illustrated with elastomer layer 12, first opposed substantially gas impermeable layer 14, and adhesive means 16 for substantially continuously adhering layers 12, 14 to one another and to form a substantially gas impermeable and elastically deformable surface (actually, two surfaces illustrated as surface 18a and surface 18b). Adhesive means 16 is also for maintaining layers 12, 14 in laminated form when the laminate is repeatedly stretched, such as during inflation. Suitable elastomers for forming elastomer layer 12 include materials formed by elastomeric fibers, such as spandex fibers, in woven, non-woven, or knit fabrics, which can further include one or more of materials such as nylon and polyester or ether based polyester. Preferred fibers are selected from the group consisting of polyester elastomers, polyester/polyether elastomers, polyamide/polyester/polyether elastomers, polyester/polyurethane elastomers, polytetramethylene terephthalate and polyester/polyurethane elastomers. More preferably, the fibers are polyester/polyether elastomers. Preferred polyester/polyether elastomers are described in U.S. Patents 3,763,109, 3,766,146, and 3,651,014. Polyester/polyether elastomers and polyester/polyurethane elastomers are available commercially from E. I. du Pont de Nemours and Company under the trademarks Hytrel and Lycra. A particularly preferred material for elastomeric layer 12 is polyester. Among the various suitable commercially available materials that may be used as elastomer layer 12 are, for example, stretchable Nomex fabric available from du Pont and Antron Cordura mixed with spandex fibers ("Spandura"), also available from du Pont. Fabric weight may vary, depending upon particular applications, with a preferred fabric weight range being on the order of about 93 to about 775 g/m 2 (about three ounces to about twenty-five ounces per square yard), and particularly preferred being about 77.5 to about 496 g/m 2 (about two and one-half ounces to about sixteen ounces per square yard) for forming components of SCUBA diving apparatus, such as a buoyancy compensator. The first opposed substantially gas impermeable layer 14 is a continuous polymeric film. Gas transmission properties are generally a function of film thickness, with films of about 0.0127 mm (0.5 mils) PET (polyethylene terephthalate), for example, typically having an oxygen transmission of about 1.085 cm 3 /100 cm 2 /day (7 cc/100 in 2 /day). Because the film should be substantially gas impermeable in forming the inventive laminate, the film thickness is at least 0.0635 mm (2.5 mils), with preferred thicknesses typically being between about 0.1778 mm (7 mils) to about 0.762 mm (30 mils), more preferably about 0.1778 mm (7 mils) to about 0.4064 mm (16 mils). Such films are flexible, yet provide substantial strengths in preparing inventive laminates. Also, films with reduced permeability to vapors (that is, films that are substantially gas impermeable for a variety of applications contemplated by this invention) can themselves be composites, such as where one layer is a flexible polymer, such as a polyurethane, polyethylene, ether polyurethane, or polypropylene, while another layer is coated on or coextruded and serves as a barrier layer. Barrier layers can generally be viewed as substantially organic based or substantially inorganic based. For example, U.S. Patent 3,442,686, issued May 6, 1969, describes a film composite in which silicon oxide coatings are deposited on polymers to serve as a barrier layer. This produces barrier coatings on even quite thin polymer films of oxygen transmission rate properties on the order of about 0.031 cm 3 /100 cm 2 /day (0.2 cc/100 in 2 /day) and similar water vapor transmission rate properties. The layers 12 and 14 are bonded, or continuously adhered, and maintained in laminated form (that is, do not delaminate) even when the laminate is repeatedly stretched and retracts, such as to accommodate substantial volume increases due to elastic deformations in response to elevated pressures. Thus, the laminate has a good elastic limit for the various applications contemplated without permanent deformation occurring. The substantially gas impermeable layer, as has been described, will tend to also have some stretchability, but it is believed to be the elastomer layer that primarily provides the necessary, preferably two-dimensional, stretch and the essential retraction properties so that the inventive laminate can be repeatedly stretched and retract following elastic deformations in use due to elevated pressures. The particular strength and amount of stretchability desired will depend upon the particular application. However, in forming buoyancy compensators one normally encounters elevated pressures in the range of about 3447 to about 55158 N/m 2 (about 0.5 psi to about 8 psi), which can be readily accommodated by a laminate in accordance with this invention. The adhesive means, or adhesive layer, 16 continuously adheres layers 12, 14 such as by melt bonding or by adhesive bonding, for example by thermal lamination on hot rolled calendaring equipment. Suitable adhesive materials are commercially available, for example, from laminators or combiners, such as Kenyon Laminating Group (Peacedale, Rhode Island) and Uretek (New Haven, Connecticut). A particularly preferred inventive laminate is formed of 100% polyester tubular knit with adhesive from Polyurethane Specialties Co. (Lindhurst, New Jersey) through Kenyon Laminating Group, using a 0.254 mm (10 mil) thick polyurethane ether based film. An adhesive with good resistance to UV, salt water, and within a preferred range of modulus (stretch) between 6,000-10,000 is Uretek, style # nylon 16-71. Particularly preferred adhesive materials for adhesive bonding are liquid polyether urethanes (which can be dissolved in methyl ethyl ketone). For example, such an adhesive material can be substantially continuously spread on film layer 14 and thereafter elastomeric fabric 12 added and adhered in a heat calendar process. Application can be by known techniques, such as by reverse roll head, by floating head, or by knife over roll head. The latter is particularly preferred. The depth at which a solubilized adhesive, such as an ether based polyurethane dissolved in MEK, penetrates the layer to which it is applied is controllable by the time when cure is commenced. The resultant laminates are preferably RF weldable for preparation in a variety of forms. Where even greater strength is required for a particular application, then a second layer (not illustrated), also preferably gas impermeable and also preferably polymeric, may be added so that one of the first layer and second layers is sandwiched between the elastomer layer and the other of the first and second layers. This second layer is preferably adhered in the sandwiched relationship by the same or a different adhesive process as is the first layer. For example, adhesive material 16 can be a solvent based adhesive while the second layer can be calendar heat bonded (that is, fused) to film 14. In the various applications for the inventive laminate 10, either surface 18a or surface 18b can be exposed to the elevated pressure for inflation, although the polymeric layer will typically be exposed to the elevated pressure while the elastomeric layer (defining surface 18a) will be exposed to touch or be adjacent to a wearer's skin for purposes of comfort. Turning to Fig. 2, a buoyancy compensator 20 is illustrated having opposed walls 22, 24 and with which the inventive laminate is usefully employed. For example, either all or part of wall 22 or all or part of opposed wall 24 can be made from inventive laminate 10. With reference to Fig. 3, both walls 22, 24 are illustrated as formed from inventive laminate 10 where buoyancy compensator 20 is illustrated as being formed with chamber 25 between the two walls 22, 24. Thus, as illustrated, the buoyancy compensator 20 can be of a single bag construction. In addition, the buoyancy compensator 20 can be of the type (not illustrated) well known to the art by having a double bag, or double wall, where the outer bag generally provides for the maintenance of pressure within the buoyancy compensator while the inner bag, or bladder, provides a maintenance of the air therein in a sealed relationship. As already noted, either all or part of wall 22 or all or part of opposed wall 24 can be made from inventive laminate 10. In one particularly preferred embodiment, wall 24, which is in contact with the diver's body, is not made from the inventive laminate 10, but rather is made from a soft, strong 100% polyester with a suede-like finish, while the opposed wall 22 is formed from inventive laminate 10. The walls 22, 24 are preferably affixed one to the other to form a chamber for receiving pressurized air, but affixation can also be by various heat sealable processes (such as tape and glue or a vulcanizing hand process). The buoyancy compensator 20 typically has a waist portion 26, which terminates in attachable belt portion 28. The belt 28 has buckles 30 and 32 (or other fastening means) in order to secure the waist portion 26 around a user's waist. Waist portion 26 will preferably be formed of a woven neoprene in combination with a nylon stretch material, which has neutral buoyancy in water. This material is also preferably used for the shoulder portions 34, 36. Shoulder portions 34 and 36 define a neck area 38. A harness 40 (illustrated generally at the back) is constructed to receive a backpack (not illustrated) which snugly fits in harness 40 to provide lumbar support and to cradle the SCUBA air tank 50. The air tank 50 has a valve and a regulator, generally shown as valve and regulator 52. The valve and regulator 52 serve to provide breathing gas to the diver wearing buoyancy compensator 20. Tube 56 is connected to an inflation system 58. The inflation system 58 has a mouthpiece 62 through which a user can inflate the buoyancy compensator orally. Inflation system 58 may comprise a soft-touch power inflator 64, oral inflation button 65, a rapid exhaust valve 66, and an overpressure relief valve 68 which all work together as inflation system 58 and which are preferably surrounded in a protective material, such as a soft elastomer, that conforms to the user's hand and protects the mechanical parts from wear and tear. The soft touch inflator 64 permits control of the air entering the buoyancy compensator 20, while the rapid exhaust valve 66 is readily opened by pulling down on the inflator tube 56. The overpressure relief valve 68 is preferably integrated into the inflation system 58 to allow air to escape quickly in the event of overpressuring the buoyancy compensator 20. Because the inventive laminate 10 is elastically deformable, the portions of such a buoyancy compensator 20 formed from the inventive laminate are more comfortable to the user due to an ability to use lower inflation pressures, particularly because during exposure to wave impact the elastically deformable surface (such as surface 18a and surface 18b) will tend to deform and the garment itself does not need to be inflated to the typical high pressure levels to compensate for wave action. That is, the deformability feature allows larger wave impact without losing air from a chamber formed by the inventive laminate. This results in a substantially more comfortable garment and the uncomfortable "squeeze" sensation of highly inflated prior art buoyancy compensators is avoided. Particularly preferred inventive laminate constructions permit volume increases due to elastic deformation on the order of up to about 100 percent in response to elevated pressures, such as within the range of about 2068 to about 34473 N/m 2 (about 0.3 psi to about 5 psi). As will be appreciated, chambers formed by the inventive laminates 10 will be resistant not just to elevated pressures, but more generally will perform as a substantially gas impermeable membrane for pressure difference with respect to the pressures imposed on surfaces 18a, 18b. That is, laminate 10 is substantially gas impermeable even with the pressure difference between a hypothetical pressure P a (to which surface 18a would be exposed) and a hypothetical pressure P b (to which surface 18b would be exposed). Thus, inventive laminate 10 could be used to form part or all of a diving suit where the internal suit pressure and the external pressure due to water are adjusted to neutral buoyancy over a pressure difference range beginning at about 0 N/m 2 and upwards. Cycle tests with different laminates suggest upper pressure difference values to about 689476 N/m 2 (100 psi) can be accommodated. Where the inventive laminate 10 is forming a membrane between fluids with one fluid in liquid or solid form, then the elastically deformable surface of the laminate can have a volume variable in response to variable fluid densities, such as in medical therapeutic containers where expansion can be due to a liquid-to-solid transformation. Again with reference to Fig. 1, typical and preferred aspects of buoyancy compensator 20 include shoulder areas 34 and 36 that are adjustable by means such as buckles 80 and 82 on adjustment straps. The shoulder areas 34,36, as well as pockets and soft backpack, can be RF welded to save labor cost of sewing with the new laminate 10. Additional attachments, fasteners, and the like features as are well known to the art may be included with the buoyancy compensator 20. For example, hooks, straps, loops, buckles, and the like are usefully included (but not illustrated). The walls 22 and 24 are shown with a sealed periphery 84. As earlier noted with reference to Fig. 3, this seals the outer edges to form an interior chamber between the walls 22 and 24. Buoyancy compensators of the invention can have a plurality of chambers, preferably where such chambers are interconnected and thus at the same pressure. Returning to Fig. 2, heatset areas 86 can take a variety of forms, shapes, and locations on the article and can be provided by radio frequency (RF) welding, ultrasonic welding, thermal heatsealing, or any other suitable sealing process, so that the buoyancy compensator walls 22 and 24 are brought into connection with each other at desired areas of the article to better fit or conform to a user's shape, to accommodate attachments, and the like. Also, the conformation of the buoyancy compensator is retained by the various heatset areas to prevent undue expansion during dives. As will be readily understood, the inventive laminate 10 can be desirably utilized in preparing other articles, particularly other inflatable articles, such as rafts and kayaks, automobile safety bags, diving suits, swimming learning vests, aircraft and lifesaving jackets and vests, medical therapeutic containers, waders, and the like. Other buoyancy compensator vests are also known to the art, such as snorkel buoyancy compensators, for which inventive laminate 10 is readily and desirably adapted. Aspects of the invention will now be further illustrated. EXAMPLE 1 Testing was performed on various laminate 10 embodiments of the invention. Cycle testing was performed by forming laminate 10 embodiments into pressurized air containing chambers (such as illustrated by Fig. 3), and then repeatedly filling and evacuating the chambers with pressures by a machine that can fill to 137895 N/m 2 (20 psi) and can evacuate to subatmospheric. An overpressure valve permits positive pressure variations up to 689476 N/m 2 (100 psi). Chambers formed from various laminates were initially screened, and then selected laminates were tested at over 10,000 cycles of input (10342 N/m 2 (1.5 psi)) and exhaust. A burst test was also used in which pressurized air was input into the chambers up to rupture. Laminates were further subjected to a wash test in which 10 cm by 10 cm (four inch by four inch) laminate pieces were subjected to heavy cycle, standard washing machine washing for 50, 100, or 150 cycles and then examined for wear, possible delamination, and color degradations. Ten out of fifty cycles included bleach, and about one-third of the cycles were with hot water, another about one-third with warm water, and a final about one-third with cold water. All cycles included conventional laundry detergent at manufacturers' suggested use levels. Laminates were yet further subjected to impact tests where a drop weight plate machine with a 6.8 Kg (fifteen pound) drop weight was used to impact the laminate rapidly and to apply uneven stress to different local areas on chambers formed from the laminates. The laminate forming chambers were then visually inspected for any weaknesses due to the impact tests. Preferred laminates of this invention perform well under the just described cycle, burst, wash, and impact testing. Several preferred laminate 10 embodiments of the invention, all successfully passing the tests as above described, were prepared as follows. A laminate embodiment was prepared from 100% knit polyester (style 5270, commercially available from Flynt Amtex, Inc.) weighing 120.9 g/m 2 (3.9 ounces per square yard), and having a 75% stretchability (both length and width). Adhesive used was obtained from Polyurethane Specialties Co. through Kenyon Laminating Group. The substantially gas impermeable layer was 0.254 mm (10 mils) polyurethane film. The polyester knit and polyurethane film were laminated by means of the adhesive through a heat calendar process, and the resulting laminate gave excellent testing results. A second laminate embodiment giving good testing results was formed in a similar manner with a nylon and spandex fabric (170 g (6 oz), 120 warp, and 80 fill) and either 0.1778 mm (7 mils) or 0.4064 mm (16 mils) polyurethane film. Yet another laminate embodiment with good test results used Antron Cordura and spandex (198 g (7 oz), 120 warp, and 95 fill) as the elastomer layer, while the first substantially gas impermeable layer was 0.254 mm (10 mils) polymeric film with a second layer being sandwiched between the elastomer layer and first layer by means of adhesive. The second, sandwiched layer was a stretchable (spandex knit) ballistic type fabric (such as used in bullet-proof vests). A fourth embodiment was prepared where the inventive laminate was formed from 100% stretch polyester as elastomer and adhered to 0.254 mm (10 mils) polyurethane film. This laminate was then used to form one wall of a chamber while the other wall was formed from a 0.254 mm (10 mil) polyurethane film adhered to a non-stretch polyester suede. The two walls were joined into the pressurized air containing chamber by means of a welded joints.

Claims: An article comprising: a laminate including an elastomer layer capable of repeated stretch and retraction, a first opposed substantially gas impermeable layer which is a continuous polymeric film at least 0.0635 mm (2.5 mil) thick, and adhesive means for substantially continuously adhering the layers to one another to form a substantially gas impermeable and elastically deformable surface and for maintaining the layers in laminated form when the laminate is repeatedly stretched. The article as in claim 1 wherein: the elastomer layer is formed by spandex fibers. The article as in claim 1 wherein: the elastomer layer is a woven, non-woven, or knit fabric. The article as in claim 3 wherein the fabric includes spandex fibers. The article as in claim 3 wherein the fabric is formed from spandex fibers and one or more nylon and polyester materials. The article as in claim 1 wherein the adhesive means includes a second layer with one of the first and second layers sandwiched between the elastomer layer and the other of the first and second layers. The article as in claim 6 wherein the second layer includes a continuous polymeric film. The article of claim 1 wherein the surface forms an inflatable article. The article as in claim 1 or claim 8 wherein the elastically deformable surface of the laminate defines a volume variable in response to variable fluid pressures or densities, a maximum volume thereof being increased due to elastic deformation of the laminate. The article as in claim 9 wherein the variable pressures are in a range of between from 2068 to 68947 N/m 2 (0.3 to 10 psi). The article as in claim 10 wherein the maximum volume increase due to elastic deformation is up to 100 percent. The article as in claim 9 wherein an inflatable chamber is formed by at least part of the surface and defines a diver's jacket, vest, suit, or a semi-dry suit. The article as in claim 12 wherein the inflatable chamber includes RF welds defining a shape for the chamber. A buoyancy compensator for providing buoyancy to a diver comprising: at least one chamber for receiving and containing buoyancy compensating gas therein, at least a portion of the chamber formed by an inflatably deformable laminate, the laminate including an elastomer layer, a first opposed substantially gas impermeable layer which is a continuous polymeric film at least 0.0635 mm (2.5 mil) thick, and an adhesive bonding the layers to one another, the laminate being substantially gas impermeable. The buoyancy compensator as in claim 14 wherein the at least one chamber has a maximum volume that is increased due to elastic deformation of the laminate in response to elevated pressure. The buoyancy compensator as in claim 15 wherein the volume increase is up to 100 percent in response to an elevated pressure within the range of 2068 to 68947 N/m 2 (0.3 to 10 psi). The buoyancy compensator as in claim 14 wherein the at least one chamber has opposed walls, at least one wall formed by the laminate. The buoyancy compensator as in claim 17 wherein the opposed walls are bonded together. The buoyancy compensator as in claim 18 wherein the opposed walls are bonded at a plurality of contact points. The buoyancy compensator as in claim 19 wherein the walls are bonded by a RF weld. The buoyancy compensator as in claim 14 wherein there are a plurality of interconnected chambers. The buoyancy compensator as in any one of claims 14 to 21 wherein the laminate further includes a barrier layer.

Inventors: WALTERS WILLIAM D, WALTERS, WILLIAM D.
Applicants: WALTERS WILLIAM D, WALTERS, WILLIAM D.
Application year: 1993
Main classification: B32B5
IPC codes: B32B27, B32B5, B63C11