Patent Publication Number: US-2009220764-A1

Title: Oleophobic laminated article and method

Description:
BACKGROUND 
     The invention is generally directed to a laminated article. In particular, the invention is directed to laminated sheet material having improved oleophobic properties, the method for making the laminated sheet material and components made from the laminated sheet material. 
     Components made from laminated sheet material have many uses and can be made to have various properties. The properties often result from the manufacture of the laminated sheet material and the materials used to make them. The properties can also be modified by chemical treatments. In some applications, components made from the laminated sheet material are useful as vents or filters that allow the flow of gas, such as air through the component, while preventing or restricting the flow of certain liquids, such as water, or oil. 
     The laminated sheet material typically includes one or more porous layers of sheet material that are laminated together. The layers of sheet material may be treated with, or formed using, a material that prevents or resists the flow of selected matter through the layer. For example, a layer of the sheet material may be treated with, or formed using, a hydrophobic material to resist the passage of water through the component made from the laminated sheet material. It may also be desired that one or more layers of the sheet material has oleophobic properties. 
     As the components made from laminated sheet material are used in more diverse applications and in harsher environments, improvements to the laminated sheet material, the methods for making the laminated sheet material and the components are desired. 
     BRIEF DESCRIPTION 
     The invention is an article including a microporous membrane. A porous fabric is laminated to the microprous membrane to form a laminate with a membrane side and a fabric side. A treatment material is applied to the laminate to form a treated laminate. The treated laminate has an oil resistance of at least a number 7 determined by AATCC 118 testing on both the membrane side and the fabric side. The treated laminate also has an air permeability through the treated laminate of at least 0.01 CFM per square foot determined by ASTM D737 testing. The treated laminate is produced by contacting the laminate with a solution of an oleophobic treatment material dissolved in an inorganic solvent. The dissolved oleophobic treatment material is deposited onto the laminate upon removal of the inorganic solvent. 
     Another aspect of the invention is a method of making an article having an improved oleophobic property. The method includes the step of providing a microprous membrane. The method also includes the step of laminating a porous fabric to the microporous membrane to form a laminate with a membrane side and a fabric side. A treatment material is applied to the laminate to provide a treated laminate. The treated laminate has an oil resistance property of at least a number 7 determined by AATCC 118 testing on both the membrane side and the fabric side. The laminate also has an air permeability therethrough of at least 0.01 CFM per square foot determined by ASTM D737 testing. 
    
    
     
       DRAWINGS 
       These and other features, aspects, and advantages of the invention will be better understood when the following detailed description is read with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective representation of laminated sheet material according to one aspect of the invention; 
         FIG. 2  is a perspective representation of a plurality of vents made from the laminated sheet material, illustrated in  FIG. 1 , according to another aspect of the invention; 
         FIG. 3  is an enlarged cross-sectional view of a portion of the laminated sheet material illustrated in  FIG. 1 , taken approximately along the line  3 - 3  in  FIG. 1 ; 
         FIG. 4  is an enlarged perspective view of one of the vents illustrated in  FIG. 2 ; and 
         FIG. 5  is a schematic representation of the system and method used to treat the laminated sheet material, according to another aspect of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Various aspects of the invention relate to a laminated article, methods of making the laminated article and components made from the laminated article. The laminated article is illustrated, by way of example, as laminated sheet material. The components made from the laminated sheet material are illustrated, by way of example, as vents. 
       FIGS. 1 and 3  illustrate a laminated article  20  as sheet material according to one aspect of the invention. The laminated article  20  includes a membrane  22  adhered to a support fabric  24 . The resulting laminated article  20  has a membrane side  42  and a fabric side  44 . 
     The laminated article  20  is hydrophobic on both the membrane side  42  and the fabric side  44 . That is, the laminated article  20  prevents or resists the passage of liquids, such as water, through the laminated article. The laminated article  20  is gas permeable and moisture vapor transmissive. That is, the laminated article  20  permits the passage of gases, such as air, carbon dioxide and water vapor, through it. An oleophobic treatment is applied to the entire laminated article  20  from an inorganic solvent according to one aspect of the invention to provide improved oleophobicity. The addition of the oleophobic treatment increases the resistance of the laminated article  20  to being fouled by oil or oily substances from either the membrane side  42  or the fabric side  44 . 
     The membrane  22  is preferably a microporous polymeric membrane that allows the flow of gases, such as air or water vapor, into or through the membrane  22  and is hydrophobic. A preferred microporous polymeric membrane for use as the membrane  22  includes expanded polytetrafluoroethylene (ePTFE) that has preferably been at least partially sintered. An ePTFE membrane typically comprises a plurality of nodes interconnected by fibrils to form a microporous lattice type of structure, as is known. 
     Surfaces of the nodes and fibrils define numerous interconnecting pores that extend completely through the membrane  22  between the opposite major side surfaces  42 ,  44  of the membrane in a tortuous path. Preferably, the average size of the pores in the membrane  22  is sufficient to be deemed microporous, but any pore size may be used. A suitable average size for the pores in the membrane  22  may be in the range of 0.001 micron to 10 microns, and preferably in the range of 0.005 to 5.0 microns. Typically, the porosity (i.e., the percentage of open space in the volume of the membrane  22 ) of the membrane  22  is between about 50% and about 98%. Often the porosity of the membrane  22  of a laminated article  20  suitable for many filtering applications ranges from about 70% to about 95%, and preferably from about 80% to about 95%. The material and average pore size of the membrane  22  establish the hydrophobicity of the membrane. 
     The membrane  22  is preferably made by extruding a mixture of polytetrafluoroethylene (PTFE) fine powder particles (available from DuPont under the name TEFLON® fine powder resin) and lubricant. The extrudate is then calendered. The calendered extrudate is then “expanded” or stretched in at least one direction and preferably two orthogonal directions, to form the fibrils connecting the nodes in a three-dimensional matrix or lattice type of structure. “Expanded” is intended to mean sufficiently stretched beyond the elastic limit of the material to introduce permanent set or elongation to the fibrils. The membrane  22  is preferably then heated or “sintered” to reduce and minimize residual stress in the membrane material. However, the membrane  22  may be unsintered or partially sintered as is appropriate for the contemplated use of the membrane. An example of suitable membrane  22  properties includes a unit weight of about 0.42 ounce per square yard, an air permeability of about 1.5 CFM, a Mullen Water Entry pressure of about 15 PSI and a moisture vapor transmission rate (MVTR) of about 60,000 grams per square meter per day (gr/m 2 /day). 
     It is known that porous ePTFE membrane  22 , while having excellent hydrophobic properties, is oleophilic. That is, the material making up the membrane  22  is susceptible to contamination by absorbing oil. Once this occurs the contaminated regions of the membrane  22  are considered “fouled” because the pores can be easily wet by a challenge liquid, such as water, and the membrane is no longer considered hydrophobic. 
     Other materials and methods can be used to form a suitable membrane  22  that has an open pore structure. For example, other suitable materials that may be used to form a porous membrane include, but are not limited to, polyolefin, polyamide, polyester, polysulfone, polyether, acrylic and methacrylic polymers, polystyrene, polyurethane, polypropylene, polyethylene, cellulosic polymer and combinations thereof. Other suitable methods of making a microporous membrane  22  include foaming, skiving, casting or laying up fibers or nano-fibers of any of the suitable materials. 
     Some membranes  22 , including, for example, many expanded PTFE membranes suitable for filtering or venting applications, are relatively thin and fragile. A support fabric  24  is included in the laminated article  20  to provide support to the membrane  22 . The support fabric  24  may have other or alternative functions including, for example, restricting or preventing the flow of the same and/or different particles and fluids as the membrane  22  and/or protecting the membrane  22  or other layers in the laminated article  20  from damage. 
     The support fabric  24  is typically made from a porous woven, non-woven or scrim of polymeric material. Often the support fabric  24  is made using a fibrous material, however, other porous materials may also be used. The average pore size of the support fabric  24  is usually larger than the average pore size of the membrane  22 , although this is not necessary in some applications. Thus, in some applications, the support fabric  24  acts to at least partially filter the fluid flowing into or through the laminated article. Typically, the average pore size of the support fabric is about 500 μm (micron) or less and often at least about 0.5 μm. The porosity of the support fabric is often in the range of about 20% to almost 90%. 
     Suitable polymeric materials for the porous support fabric  24  include, for example, stretched or sintered plastics, such as polyesters, polypropylene, polyethylene, and polyamides (e.g., nylon). These materials are often available in various weights including, for example, 0.5 oz/yd 2  (about 17 gr/m 2 ), 1 oz/yd 2  (about 34 gr/m 2 ), and 2 oz/yd 2  (about 68 gr/m 2 ). Woven fabric such as 70 denier nylon woven taffeta pure finish may also be used. Another suitable fabric is a non-woven textile such as a 1.8 oz/yd 2  co-polyester flat-bonded bi-component non-woven media. 
     The support fabric  24  and the membrane  22  are laminated together. The lamination of the support fabric  24  and the membrane  22  can be accomplished by a variety of methods, such as thermal lamination or adhesive lamination.  FIG. 1  illustrates one aspect of a laminated article  20  in which the support fabric  24  and membrane  22  are adhered by thermal lamination. An example of the laminated article  20  is a non-woven polyester support fabric  24  thermally laminated to ePTFE membrane  22 . Another example of the laminated article  20  is a woven taffeta support fabric  24  adhesively laminated to membrane  22 . 
     Improved oleophobic properties of the laminated article  20  are realized according to one aspect of the invention by treating surfaces defining the pores in the membrane  22  and support fabric  24  as well as the surfaces of the membrane side  42  and the fabric side  44  of the laminated article  20  with a fluorinated polymer treatment material, or fluorpolymer. The limiting factor previously has been the lack of an effective way to introduce the treatment material into the pores of the membrane  22  of the laminated article  20  and to evenly coat the surfaces defining its pores. The laminated article  20 , according to one aspect of the invention, has the treatment material coating even the smallest pores of the membrane  22  of the laminated article. The applied treatment material modifies properties of the entire laminated article  20 , such as oleophobicity. 
     It has been found that an inorganic fluid under supercritical conditions can dissolve the preferred fluorinated polymer treatment material. The resulting solution is capable of wetting the laminated article  20  and entering pores in the microporous membrane  22  with the dissolved fluorinated polymer treatment material. The solution with dissolved fluorinated polymer treatment material has a surface tension, viscosity and relative contact angle that permit the dissolved treatment material to be easily carried into the smallest pores of the membrane  22  and the support fabric  24  with the inorganic solvent. 
     The inorganic solvent is preferably carbon dioxide in a supercritical phase. The surface tension of the supercritical carbon dioxide (SCCO 2 ) solution is less than 1 dyne/cm and most preferably less than 0.1 dyne/cm so it can enter very small areas of the laminated article  20  to be treated, such as the pores of the membrane  22 . Supercritical carbon dioxide also has a viscosity of less than about 0.1 centipoise. The viscosity and surface tension of the solution are extremely low so very little resistance to flow is encountered, thus, lending itself to the possibility of entering even the smallest pores of the membrane  22 . Effective treatment is possible even if the laminated article  20  is in a confined state, such as in a tightly wound roll of sheet material. 
     The fluorinated polymer treatment material, or fluoropolymer, is deposited on and around surfaces of the nodes and fibrils that define the interconnecting pores extending through the membrane  22  and pores of the support fabric  24 . This results in a relatively thin and even coating being applied to virtually all the surfaces of the laminated article  20 . Once a predetermined proper amount of fluorinated polymer treatment material is deposited on the laminated article  20  the pores are not dramatically reduced in flow area from that of an untreated laminated article. Improved oleophobic properties are realized on both the membrane side  42  and the fabric side  44  of the laminated article  20 . 
     Examples of suitable fluorinated polymer treatment materials include those having a fluoroalkyl portion or, preferably, a perfluoroalkyl portion. One such fluorinated polymer treatment material is a perfluorakyl acrylic copolymer referred to as Fabati 100 and was designed and synthesized by Micell Technologies, Inc. Fabati 100 was synthesized in MIBK (methyl isobutyl ketone) utilizing TAN (1,1,2,2,-tetrahydroperfluorooctyl acrylate); butyl acrylate; a cross-linking agent TMI (isopropenyl-a,a-dimethylbenzyl isocyanate); Vazo 52 initiator (2,4-dimethyl-2,2′-azobispentanenitrile). The Fabati 100 treatment material is cross-linked by a post-treatment cure with heat. Another suitable perfluorakyl acrylic copolymer is Fabati 200. Fabati 200 is similar to Fabati 100 but does not have the cross-linking agent (TMI) and HBA (4-hydroxybbutyl acrylate) is used instead of butyl acrylate. Thus, the Fabati 200 treatment material does not require post-treatment heating. 
     A variety of inorganic solvents can be used in the solution containing the oleophobic fluorinated polymer treatment material. The term “inorganic solvent” refers to non-aqueous solvents and combinations of non-aqueous solvents, and, in particular, to solvents comprising inorganic compounds. Suitable inorganic solvents include, for example, carbon dioxide (CO2), ammonia (NH 3 ), urea [(NH 2 ) 2 CO], inorganic acids, such as hydrochloric acid, sulfuric acid, carbon tetrachloride and carbon tetrafluoride and oxides of carbon such as carbon dioxide (CO 2 ), carbon monoxide (CO), potassium carbonate and sodium bicarbonate. A choice of solvent or solvents may be affected by a variety of factors including solubility of the treatment material in the solvent, molecular weight of the solvent and polarity of the solvent. In preferred aspects of the invention, the treatment material is completely dissolved in the inorganic solvent. In other aspects of the invention, the treatment material is not fully dissolved in the inorganic solvent. 
     The amount of fluorinated polymer treatment material in the solution may vary over a wide range. Typically, the amount of fluorinated polymer treatment material in the solution affects the resultant oleophobicity of the laminated article  20 . Typically, the amount of fluorinated polymer treatment material, or fluoropolymer, in the solution is about 25 wt % or less and preferably, about 10 wt % or less. For many applications, that the laminated article  20  is used in, the amount of fluoropolymer treatment material in the inorganic solvent ranges from about 0.8 wt % to about 10.0 wt % and preferably, from about 2.0 wt % to about 5.0 wt %. 
     The support fabric  24  and membrane  22  are treated together subsequent to lamination of the support fabric  24  and membrane  22 . Typically, during treatment, the fluorinated polymer solution wets and, preferably, saturates, the support fabric  24  and membrane  22  of the laminated article  20 . The use of an inorganic solvent facilitates the distribution of the fluorinated polymer treatment material throughout the support fabric  24  and membrane  22  of the laminated article. The inorganic solvent is then removed. The fluorinated polymer treatment material attaches to the support fabric  24  and membrane  22  and enhances the oleophobicity at both sides  42 ,  44  of the laminated article  20 . 
     Optionally, the treated laminated article  20  may then be “cured” by heating. The “curing” process increases the oleophobicity by allowing rearrangement of the fluoropolymer into an oleophobic orientation. The curing temperature varies among fluoropolymers. 
     The laminated article  20  has a relatively high moisture vapor transmission rate (MVTR) and air permeability while its oleophobic properties are improved by the treatment material. Both sides  42 ,  44  of the laminated article  20  have an oil hold out rating of at least a number 7 rating as determined by AATCC 118 testing and preferably at least a number 8 rating. The laminated article  20  preferably has a moisture vapor transmission rate (MVTR) of at least 1500 gr/m 2 /day and more preferably at least 15,000 g/m 2 /day measured by JISL-1099B2 testing. The laminated article  20  preferably has an air-permeability of at least 0.01 CFM per square foot of membrane, preferably at least 0.05 CFM per square foot of membrane and more preferably at least 0.15 CFM per square foot of membrane measured by ASTM D737 testing. The laminated article  20  preferably has a Mullen Water Entry pressure of at least 10 PSI, preferably at least 15 PSI and more preferably 30 PSI. 
     The term “oleophobic” is used to describe a material property that is resistant to contamination from absorbing oils, greases, soap, detergent or body fluids, such as perspiration. An “oleophobic property” or “oleophobicity” of the laminated article  20  is typically rated on a scale of 1 to 8 according to AATCC test 118. This test objectively evaluates an article&#39;s resistance to wetting by various standardized challenge liquids having different surface tensions. Eight standard challenge liquids, labeled # 1  to # 8 , are used in the test. The # 1  challenge liquid is mineral oil (surface tension: 31.5 dynes/cm at 25° C.) and the # 8  challenge liquid is heptane (surface tension: 14.8 dynes/cm at 25° C.). Five drops of each challenge liquid are placed on one side of the laminated article  20  to be tested. Failure occurs when wetting of the laminated article  20  by a selected challenge liquid occurs within 30 seconds. 
     The oleophobic rating number of a tested laminated article  20  corresponds to the last challenge liquid successfully tested. The higher the oleophobic number rating, the better the oleophobic property, or oleophobicity, as evidenced by resistance to penetration by challenge liquids of relatively lower surface tension. It was found that both the membrane side  42  and the fabric side  44  of the laminated article  20  were able to pass a challenge by hexane that has a relatively lower surface tension than heptane. Therefore, a new non-standard rating number of “8+” was adopted to indicate that a tested sample resisted penetration of hexane under standard test conditions. Thus, the term “preferably at least a number 8 rating” means that a standard number 8 rating or more is achieved by the tested sample. This is a significant improvement over known laminated articles. 
     The laminated article  20  was evaluated for water-proofness by a Mullen Water Entry Test (ASTM Standard D751-00 Method A). Mullen Water Entry Test is a test method that measures the ability of a fabric to resist leakage by pressure exerted by water. A hydrostatic force is applied to the laminated article  20  that is to be tested and is used to determine the pressure at which the laminated article begins to leak. The water entry pressure is measured in kilopascals or in PSI. 
     The laminated article  20  was mounted in a Mullen Water Entry test apparatus to challenge the membrane side  42 . Water is forced against an unsupported area of a challenge side of the laminated article  20 . The instant the laminated article  20  begins to leak, the inflation pressure drops. The pressure is recorded and is indicative of the resistance of the laminated article  20  to leakage. The membrane side  42  of the laminated article  20  has a Mullen Water Entry of at least 10 PSI, preferably at least 15 PSI and most preferably at least 30 PSI. 
     Sample laminates were treated according to one aspect of the invention. The properties that resulted from the treatment are reported in the following table. Sample laminate 1 has a woven nylon fabric available from Ramsey as part number 1BS196590. The fabric is adhesively laminated to QM0901 membrane available from BHA Group, Inc. Sample laminate 2 has a non-woven polyester fabric available from Freudenberg as part number PE939. The fabric is thermally laminated to QM0902 membrane available from BHA Group, Inc. 
     
       
         
           
               
               
               
               
               
            
               
                   
                   
               
               
                   
                   
                   
                 Mullen Water 
                   
               
               
                   
                 Oil Hold Out 
                 Air 
                 Entry (PSI) 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Membrane 
                 Fabric 
                 Perm 
                 Membrane 
                 Fabric 
                 MVTR 
               
               
                 Sample 
                 Side 
                 Side 
                 (CFM) 
                 Side 
                 Side 
                 g/m 2 /day 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 1 
                 8+ 
                 8+ 
                 0.48 
                 50 
                 14.5 
                 18,000 
               
               
                 2 
                 8   
                 8   
                 0.1 
                 64 
                 52 
                 35,000 
               
               
                   
               
            
           
         
       
     
     Another aspect of the laminated article  20  of the invention is illustrated in  FIG. 2 . A plurality of vents  60  are die cut from the laminated article  20 . Examples of applications in which the vents  60  made from the improved oleophobic laminated article  20  can be used include oil sensors, disk drives, gas sensors, optical sensors, pressure transducers, headlight breather filters, cellular phone filters, battery breathers, numerous automotive and medical vents, breathers or filters and motors. The use of the laminated articles  20  is not restricted to electronic devices. Other applications use vent filters to permit air flow through a port in the housing. Examples of these assemblies include sterile packaging, other packaging, medical devices, chain saw vents, ink-jet cartridges, chemical vents, anti-lock braking system (ABS) vents, and air bags. 
     One application of a vent filter made using the laminated article  20  of the invention is in the context of a headlamp for a vehicle, such as, for example, a car, bus, motorcycle, or truck. A headlamp includes a light source and a housing around the light source to protect the light source from damage and water. Pressure differentials caused, for example, by heating or cooling of the light source, can damage the light source if venting is not provided in the housing. 
     At least one aspect of the laminated article  20  of  FIG. 4  is useful, for example, as a vent  60 . In this embodiment, the laminated article  20  has a portion  62  of the membrane side  42  that is optionally covered with adhesive and another central portion  64  that is not covered. In operation, the vent  60  may be placed over an opening of a component, such as a housing or container, that requires venting. The adhesive portion  62  would engage the component to attach the vent  60  to the component. A gas, such as air, may then flow through the central portion  64  of the vent  60  with contaminants (e.g., particulate matter, water, and/or oily materials) being prevented or restricted from flowing through the central portion of the vent. 
     A system  100  for use in the method of treating the laminated article  20  according to one aspect of the invention is schematically illustrated in  FIG. 5 . The system  100  includes a vessel  102  for treating the laminated article  20 . The vessel  102  is a pressure vessel capable of withstanding pressure up to 5,000 psi (about 345 bar) and elevated temperature in the range of 100° C. (212° F.). The vessel  102  is sized appropriately to treat the desired width and length of laminated article  20 . The vessel  102  is fluidly connected to a supply and circulation pump  104 . A treatment material introduction vessel  106  is located between the vessel  102  and pump  104 . 
     Pump  104  is also connected to a solvent storage container  122 . The storage container  122  houses liquid solvent under pressure and is maintained at a temperature to assure delivery of solvent in a liquid phase to pump  104 . In one aspect of the invention, the solvent is carbon dioxide (CO 2 ). The vessel  102  is also connected to separation and recovery station  122 . The separation and recovery station  122  is connected to a filtration system  124  that is vented to atmosphere. The separation and recovery station  122  is also connected to treatment recovery container  126  for recovering treatment material solids. 
     An untreated article, such as approximately 50 to 80 yards of 58-inch wide laminated sheet material is rolled onto a core  140  and secured at axially opposite ends to hold the roll of sheet material on the core and prevent fluid flow axially out the ends of the roll. The core  140  is made from any suitable material, such as perforated stainless steel. The core  140  and roll of sheet material are placed in the vessel  102 . The core  140  and roll of sheet material are supported in the vessel  102  so the sheet material does not contact the interior wall of the vessel and fluid flow can occur around the entire roll. The sheet material is made from materials that do not dissolve in the selected solvent. 
     Particle solids of the preferred fluorinated polymer treatment material are placed in the treatment introduction vessel  106 . Suitable treatment material has been found to be a perfluorakyl acrylic copolymer available under the tradename Fabati 100 or Fabati 200 from Micell Technologies, Inc. The amount of treatment material depends on the solution concentration desired in the system. For example, 5000 grams of treatment material may be used. The core  140  and roll of sheet material are placed in the vessel  102 . The sheet material is made from materials that do not dissolve in the selected solvent. 
     Liquid solvent, such as the preferred carbon dioxide, flows from the storage container  122 , through the pump  104 , through the treatment material introduction vessel  106  and into the vessel  102  and the associated lines at the storage pressure. Pump  104  is started to circulate the solvent and increase pressure. Pump  104  raises the pressure in the system to a predetermined pressure. The predetermined pressure may be selected to provide optimal solvent properties to the carbon dioxide, such as raising the solvent to a supercritical state. Solvent flows from the pump  104 , through the treatment material introduction vessel  106 . The solvent dissolves treatment material in the treatment material introduction vessel  106  forming a solution that is fed into the vessel  102 . 
     System pressure increases to a desired predetermined pressure. The temperature and pressure of the solvent are controlled as determined by the solubility of the treatment material to be in a phase or condition so the treatment material may dissolve for a desired solute concentration. Pressure and volume of solvent may be increased in a known manner by a make-up supply and pump (not shown). 
     For example, when supercritical carbon dioxide (SCCO 2 ) is at 3600 PSIG or higher pressure and a temperature of 40° C., the preferred treatment material dissolves. The treatment material in the treatment material introduction vessel  106  dissolves in the solvent flowing through it at supercritical conditions. It will also be apparent that the treatment material can be in liquid form and pumped into the system  100 . 
     Flow through the treatment material introduction vessel  106  continues until the desired concentration of the treatment material solute in the solvent is attained. This flow path is maintained until the desired amount of solids in the treatment introduction vessel  106  is dissolved to obtain a desired predetermined concentration of treatment material in the solution. 
     Once the desired system conditions are reached, the treatment material solute and solvent in the solution are circulated through the system  100  for an appropriate predetermined time. The flow path may be any suitable flow path. By way of example, the solution is routed through the pump  104 , through the treatment material introduction vessel  106 , into the interior of the core  140  in the treatment vessel  102 , through the roll of sheet material, into the treatment vessel, and then back to pump. This flow maintenance for a period of time assures that the treatment material is uniformly dissolved in the inorganic solvent and that every surface of the roll of sheet material has been exposed to the treatment material solution. 
     The pressure and/or temperature of the solution are/is then permitted to change to a condition in which the treatment material solute is no longer soluble. The treatment material precipitates out of the solution when it first becomes insoluble. The precipitated treatment material deposits onto the surfaces of the laminated article  20 . The pressure can then be further reduced to atmospheric so the vessel  102  can be opened. The deposited treatment material does not block the pores of the membrane  22  or support fabric  24  so air permeability of the laminated article  20  is not adversely affected. The deposited treatment material covers all or at least substantially all of the surfaces in the sheet material, such as the surfaces defining the pores in the laminated article  20  and the outer surface of the membrane side  42  and the outer surface of the fabric side  44 . 
     Heat may optionally be applied to the treated laminated article  20  if it was treated with a treatment material that included a cross-linking agent, such as Fabati 100. Heat may be applied at about 280° F. (165° C.) heat for about 60 minutes to the laminated article  20  to cross-link the treatment material. 
     Although the aspects herein have been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the systems and techniques herein and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the invention disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow.