Composite material

[0001] The present invention relates to composite materials such as deaeration materials and deaerators including said deaeration materials.

The present invention particularly relates to air-permeable or more generally gas-permeable composites that are oleophobic and repel liquids.

BACKGROUND OF THE INVENTION [0002] There are many types of vents on the market that allow venting of containers while allowing little air flow through the vent. Packaging vents are commonly used to vent consumer and industrial liquid cleaners. These liquid cleaners normally contain organic additives and surfactants that lower the surface tension of the liquid making it easier to wet and adhere to the surface.

[0003] Another difficulty is that many types of newly developed liquid cleaners have an even higher viscosity than previously used. Liquids with higher viscosities are more advantageous because they enable better operation of the liquid cleaning agent, increasing its adhesion and contact time of the liquid with the surface being cleaned. As a result of this higher viscosity and low surface tension, viscous liquids can stick much better to the vents themselves. Because of this, the breathers can easily be blocked by the liquid remaining on the breather surface. Another problem arises when the viscous liquid dries on the surface of the vent leaving an impermeable layer consisting of solid components dissolved in the liquid. Therefore, in the case of highly viscous liquids, the vent may become permanently unusable.

[0004] The problem is also that many liquid cleaning agents emit small amounts of gaseous substances such as oxygen or chlorine, which can cause the containers to overfill after the vent has been blocked by a sticky liquid.

[0005] Viscous oils are another type of fluid that causes problems in automotive venting applications. For example, engine oils have the ability to stick to electronic housings preventing air flow and pressure equalization through the breather.

[0006] US Patent 5,462,586 relates to oil and water repellent gas permeable filters that have internal and external surfaces coated with a compound consisting of a first fluoropolymer having a fluorine containing cyclic aliphatic structure in the main chain and a second fluoropolymer containing polifluoroalkyl groups. Coating in US 5,462,586 should generally not affect the porosity of the porous material. US Patent 5,462,586 is mentioned herein in the literature.

[0007] The object of at least one aspect of the present invention is to eliminate or alleviate at least one or more of the aforementioned problems.

[0008] Furthermore, it is an object of at least one aspect of the present invention to provide a venting composite that can provide sufficient residual gas flow (e.g., air flow) even after contact with a liquid having high viscosity and low surface tension.

SUMMARY OF THE INVENTION [0009] The present invention provides a venting apparatus according to claim 1 and a gas venting method according to claim 22.

[0010] According to a first aspect, there is provided a gas-permeable composite comprising:

(a) a porous polymeric structure having a structure comprising a plurality of through pores and at least one outer surface;

(b) a coating covering at least part of said outer surface;

(c) said coating comprising at least a first and a second component;

(d) said first component comprising oleophobic and hydrophobic fluorinated material; and (e) said second component comprising perfluoropolyether (PFPE), said PFPE comprising end groups selected from the following:

- (O) n - (CR1R2) m - CR3R4R5 where:

R1 = H, F, Cl, Br or I;

R2 = H, F, Cl, Br or I;

R3 = H, F, Cl, Br or I;

R4 = H, F, Cl, Br or I;

R5 = H, F, Cl, Br, I, alkyl or aryl;

n = 0 or 1; and m = 0-10.

[0011] The R5 group may be an alkyl or aryl group.

[0012] Typically, PFPE may have two end groups at opposite ends of the PFPE structure.

[0013] Typically, PFPE may contain two perfluorinated end groups at opposite ends of the PFPE structure, such as -OCF3, -OC2F5 and -OC3F7.

[0014] However, there may be non-perfluorinated end groups, such as those containing H, Cl, Br or I radicals. Examples of non-perfluorinated PFPE end groups (eg, neutral PFPE) may include structures such as:

-CF2R6 R6 = H, Cl, Br or I;

or

-CFR7-CF3 R7 = H, Cl, Br or I.

[0015] The end groups according to the formula - (O) n - (CR1R2) m - CR3R4R5 can be selected from any combination of the following:

- OCF3; -OC2F5; -OC3F7; -OC4F9; -OC5F11; -OC6F13; -OC7F15; -OC8F17; -OC9F19;

- OC10F21;

- OCF2H: -OC2F4H; -OC3F6H, -OC4F8H; -OC5F10H; -OC6F12H; -OC7F14H; -OC8F16H; - OC9F18H; -OC10F20H;

- OCF2Cl; -OC2F4Cl; -OC3F6Cl; -OC4F8Cl; -OC5F10Cl; -OC6F12Cl; -OC7F14Cl;

- OC8F16Cl; -OC9F18Cl; -OC10F20Cl;

- OCF2Br; -OC2F4Br; -OC3F6Br; -OC4F8Br; -OC5F10Br; -OC6F12Br; -OC7F14Br;

- OC8F16Br; -OC9F18Br; -OC10F20Br;

- OCF2I; -OC2F4I; -OC3F6I; -OC4F8I; -OC5F10I; -OC6F12I; -OC7F14I; -OC8F16I;

- OC9F18I; -OC10F20I;

- OCF1H2; -OC2F3H2; -OC3F5H2; -OC4F7H2; -OC5F9H2; -OC6F11H2; -OC7F13H2;

- OC8F15H2; -OC9F17H2; -OC10F19H2;

- OCFCl2; -OC2F3Cl2; -OC3F5Cl2; -OC4F7Cl2; -OC5F9Cl2; -OC6F11Cl2; -OC7F13Cl2;

- OC8F15Cl2; -OC9F17Cl2; -OC10F19Cl2;

- OCF1Br2; -OC2F3Br2; -OC3F5Br2: -OC4F7Br2; -OC5F9Br2; -OC6F11Br2; -OC7F13Br2;

- OC8F15Br2; -OC9F17Br2; -OC10F19Br2;

- OCF1I2; -OC2F3I2; -OC3F5I2; -OC4F7I2; -OC5F9I2; -CC6F11I2; -OC7F13I2; -OC8F15I2;

- OC9F17I2; -OC10F19I2;

- CF3; -C2F5; -C3F7; -C4F9; -C5F11; -C6F13; -C7F15; -C8F17; -C9F19; -C10F21;

- CF2H; -C2F4H; -C3F6H; -C4F8H; -C5F10H; -C6F12H; -C7F14H; -C8F16H; -C9F18H;

- C10F20H;

- CF2Cl; -C2F4Cl; -C3F6Cl; -C4F8Cl; -C5F10Cl; -C6F12Cl; -C7F14Cl; -C8F16Cl; -C9F18Cl; - C10F20Cl;

- CF2Br; -C2F4Br; -C3F6Br; -C4F8Br; -C5F10Br; -C6F12Br; -C7F14Br; -C8F16Br;

- C9F18Br; -C10F20Br;

- CF2I; -C2F4I; -C3F6I; -C4F8I; -C5F10I; -C6F12I; -C7F14I; -C8F16I; -C9F18I; -C10F20I;

- CF1H2; -C2F3H2; -C3F5H2; -C4F7H2; -C5F9H2; -C6F11H2; -C7F13H2; -C8F15H2;

- C9F17H2; -C10F19H2;

- CFCl2; -C2F3Cl2; -C3F5Cl2; -C4F7Cl2; -C5F9Cl2; -C6F11Cl2; -C7F13Cl2; -C18F15Cl2;

- C9F17Cl2; -C10F19Cl2;

- CF1Br2, -C2F3Br2; -C3F5Br2; -C4F7Br2; -C5F9Br2; -C6F11Br2; -C7F13Br2; -C8F15Br2; - C9F17Br2; -C10F19Br2; and

- CF1I2; -C2F3I2; -C3F5I2; -C4F7I2; -C5F9I2; -C6F11I2; -C7F13I2; -C8F15I2; -C9F17I2; - C10F19I2.

[0016] The gas-permeable composite repels oils, water and / or water-based liquids. The gas-permeable composite can be used where the surface of the composite can come into contact with liquids of high viscosity and low surface tension. Therefore, the gas-permeable composite can be used to vent containers (e.g., bottles) containing high-viscosity liquids, preventing excessive or insufficient pressure in the container.

The breather may be in the container lid or lid.

[0017] The gas-permeable composite has the repellent properties of highly viscous liquids, such as industrial cleaners, detergent solutions and oils.

The gas-permeable composite can be used to repel all forms of hydrocarbon-based liquids, such as oils, lubricating oils, diesel oils, hydraulic fluids, gasoline, diesel and the like. Therefore, the composite can be used in the automotive industry, where lubricating oils are used in vehicle engines, gears or axles. The oil and hydrophobic properties of the composite can also be used as a gas filter (e.g. air filter) to prevent or at least reduce air pollution. For example, a gas-permeable composite can be used to protect electronic components in cell phones, computers (such as disk drives), automotive (such as sensors, motors, head lamps) or to vent medical equipment.

[0018] The gas-permeable composite may be substantially waterproof and have a water penetration pressure exceeding about 0.05 bar, 0.1 bar, 0.5 bar, 1.0 bar or 2.0 bar.

[0019] The gas-permeable composite may have an oil class 1, 2, 3, 4, 5, 6 or 7 according to AATCC test method 118-1989. Therefore, the gas-permeable composite is hydrophobic.

[0020] The gas-permeable composite may have air permeability before any contact with a viscous liquid of 1000 Gurley s units, 200 units

Gurley s, 100 Gurley s, 50 Gurley s or 30 Gurley s

[0021] Typically, the gas-permeable composite may have gas flow recovery (e.g.

air flow) above about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or

90% compared to the initial gas flow after exposure to a liquid for a specified period of time, e.g. 5 seconds, 10 seconds, 30 seconds or 60 seconds. Gas flow recovery can be measured after a predetermined waiting time, such as 1 minute, 5 minutes or 10 minutes. In certain embodiments, the gas-permeable composite may have gas flow recovery (e.g. air flow) above about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90% compared to the initial gas flow after exposure to a specific test liquid, such as described hereinafter the "air flow recovery test" in more detail. Exposure is understood as any form of contact between the liquid (e.g. liquid) and the surface of the gas-permeable composite, which includes inverting the liquid in the container onto the surface of the gas-permeable composite or immersing it for a certain time gas-permeable composite in the liquid.

[0022] Hereinafter, the removal of liquid from the surface is commonly referred to as liquid repulsion. Liquid repulsion is understood to mean removing liquid from the contact surface. Thus, a vent that can effectively remove liquid from at least one of its surfaces is hereinafter referred to as a vent with good liquid repellency properties.

[0023] The thickness of the gas-permeable composites may vary from a few to several hundred microns. For example, the composite may have a thickness of about 0.1-5000 μm, about 0.5-1000 μm, about 1-800 μm, about 5-800 μm, about 5-500 μm, about 10-800 μm, about 10-500 μm, about 50-500 μm, about 100-500 μm, about 10-100 μm or about 10-50 gm.

[0024] The composite may also be attached to another or multiple layers, such as any suitable undercoat layer to increase the mechanical integrity of the gas-permeable composite. Therefore, the gas-permeable composite may be formed into, for example, a laminate.

[0025] The coating consists of a combination of first and second components forming a synergistic partnership. The first component may provide a certain degree of oleophobicity to prevent penetration / wetting of liquids with low surface tension of the porous polymeric structure. The second component may assist in the repulsion of liquid coated layers. Liquid repellency can be improved by increasing the overall coating and closing / blocking pores and / or smoothing the outer surface of the polymer structure (typically the second component is a liquid, and the liquid generally creates extremely "smooth" surfaces).

[0026] The ratio and amount of the first and second components may be selected and adjusted to provide the optimal combination of liquid entry pressure and liquid repulsion. Fluid penetration pressure is important to keep liquids out of the pores, i.e. prevent wetting of pores by low surface tension liquids. Liquid repulsion is necessary to remove puddles / drops or liquid layers from the surface of the substance. Both properties are important for recovering the airflow through the breather after contact with liquids.

[0027] It has been found that although the first and second components can be selected to obtain excellent liquid repellency properties, this can have a detrimental effect on the liquid penetration pressure. Therefore, when choosing the first and second components, to achieve optimal liquid repulsion and liquid penetration pressure, balance must be maintained.

[0028] The weight ratio between the first and second components in the resulting coating can be selected from the following ranges: about 1 part by weight of the first component to about 0.01-100 parts by weight of the second component; from about 1 part by weight of the first component to about 0.1-30 parts by weight of the second component; from about 1 part by weight of the first component to about 0.5-20 parts by weight of the second component, from about 1 part by weight of the first component to about 2-20 parts by weight of the second component; from about 1 part by weight of the first component to about 1-10 parts by weight of the second component; from about 1 part by weight of the first component to about 3-7 parts by weight of the second component; or from about 1 part by weight of the first component to about 3-5 parts by weight of the second component.

[0029] The molar ratio between the first and second components in the coating can be selected from the following ranges: about 1 part mole of the first component to about 0.05-15000 parts of the mole of the second component; from about 1 part mole of the first component to about 0.5-10,000 parts by mole of the second component; from about 1 part mole of the first component to about 1-5000 mole parts of the second component.

[0030] The coating covers / closes at least part of the structural functions of the outer and inner surfaces of the porous polymeric structure by means of a thin layer modifying the chemical nature and thereby modifying the surface energy of the porous polymeric structure to prevent the penetration of liquids (e.g. organic liquids) or oils.

[0031] The coating may also form at least one or more or many closed and / or blocked surface portions, for example a thin layer and / or a gas-permeable coating layer on portions of the outer surface of the porous polymeric structure. For example, the expanded PTFE coating layer may cover the nodes and fibrils of the outer surface of the porous polymer structure and may block and / or close some pores of the outer surface of the porous polymeric structure. By outer surface is meant the outermost layer extending around the edge of the porous polymeric structure that can be touched and first comes into contact with the liquid to be repelled. This is the outer layer that is important in repelling liquids. The term "outer layer" is not intended to include the inner structure in the main part of the porous polymeric structure.

[0032] It has been found that for a gas-permeable membrane with the best fluid repellency characteristics, some of the surface pores can be covered / blocked by the coating forming bridging elements between the solid, non-porous regions of the membrane. Without wishing to be bound by theory, it is believed that these bridging elements are at least partly responsible for better liquid repulsion characteristics and a second component, e.g. a liquid, can smooth the surface of a porous polymeric structure.

[0033] The smallest blocked surface portion may have a size substantially equivalent to the pore / opening of the porous substrate. Closed and / or blocked surface portions present on the outer surface of the porous polymeric structure may be from a few μm in size² (square micrometres) up to several hundred μm² and together they can constitute over 1%, 2%, 5%, 7%, 10%, 20%, 30%, 50% of the external surface.

[0034] The coating may also soak up the entire porous polymeric structure in such a way that the other (uncoated) side also becomes oleophobic.

[0035] The coating may penetrate (e.g., soak and / or impregnate) the main part of the porous polymeric structure. However, it is important that part of the coating remains on the outer surface of the porous polymeric structure allowing the formation of closed and / or blocked parts of the surface.

[0036] The coating can both effectively facilitate liquid repellency and prevent or substantially prevent the penetration of low surface tension liquids into the porous polymeric structure and thus maintain the gas's ability to flow through the composite upon contact with the viscous liquid. Therefore, the coating can be used to provide venting with significantly improved fluid repulsion and significantly improved airflow recovery.

[0037] The coating layer covering structural functions and covering / blocking surface pores may have a typical thickness in the range from about 0.001 μm to 5 μm, from about 0.01 μm to 1 μm or from about 0.1 μm to 0.5 μm [ [0038] The coating does not completely block and / or close the porous structure, therefore the composite remains gas-permeable. The coating may block and / or close about 0.1-80%, about 0.1-50%, about 0.1-30%, about 0.5-10% or about 1-5% of the pores of the structure. In certain embodiments, at least about 0.1%, 1%, 5%, 10%, 20%, 30%, 50% or 70% of the surface pores can be blocked and / or closed. The total weight of the coating relative to the weight of the porous polymeric structure may range from about 0.1-1000% by weight, about 0.1-500% by weight, about 0.1-300% by weight, about 1-500% by weight, about 1-200% by weight, about 1-100% by weight, about 1-50% by weight, about 5-100% by weight, about 1-30% by weight, about 5-30% by weight or about 2-15 wt.

[0039] The ratio of the total weight of the coating relative to the weight of the porous polymeric structure may be at least about 3%, 5%, 10% or 20%.

[0040] Typically, the coating may be deposited in a range of about 0.01-1000 g / m2², about 0.05 300 g / m2², about 0.1-800 g / m2², 0.5-500 g / m2², 0.5-300 g / m2², about 1-300 g / m2², about 5-200 g / m2², about 10-100 g / m2², about 0.1-100 g / m2², about 1-50 g / m2² or about 20-50 g / m2². Alternatively, the coating may be deposited in a range of at least about 0.05 g / m2², 0.1 g / m2², 1 g / m2², 10 g / m2², 20 g / m2², 30 g / m2², 40 g / m2², 80 g / m2², 100 g / m2², 500 g / m2² or 1000 g / m2². [0041] Typically, the first component may have a molecular weight in the range of from about 500 amu to about 10,000,000 amu or from about 5,000 amu to about 1,000,000 amu Preferably, the molecular weight of the first component may range from about 10,000 amu to about 1,000,000 000 amu

[0042] The fluorine content of the first component may be at least about 1% by weight, 5% by weight, 10% by weight, 20% by weight or 40 wt. molecular structure of the first component.

[0043] The first component contains any fluorinated material that is both oleophobic and hydrophobic, i.e. repels both oils and water. The first component applied as a coating on the porous substrate prevents oils and liquids with low surface tension from entering the pores of the substrate.

[0044] The first component may contain a fluorinated or perfluorinated form of an ester such as an acrylate or methacrylate. Homo- or copolymers of fluorinated acrylate or methacrylate compounds are well known in the art. Examples of these polymers are described in "Modern Fluoropolymers", edited by John Scheirs, Wiley Series in Polymer

Science, John Wiley &. Sons (Chichester, New York, Weinheim, Brisbane, Singapore,

Toronto), 1997, chapter 26: Fluorinated Acrylic Ester Polymers, which is incorporated herein by reference. Copolymers of fluorinated acrylates or methacrylates may include a number of other vinyl monomers and are selected to achieve the desired characteristics.

[0045] An example of a fluorinated acrylic ester polymer structural element may be as follows:

Rf- (CH2) m-CO2- (CR10-CH2) nR10 = -H, -CH3;

m = 1.2; and

Rf = perfluoroalkyl.

[0046] The first component may also be in the form of a tetrafluoroethylene (TFE) copolymer or terpolymer with optional other fluorinated or non-fluorinated monomers.

[0047] In certain embodiments, the first component may comprise at least one amorphous fluoropolymer, amorphous perfluoropolymer or a combination thereof which may be dissolved in fluorinated solvents or mixtures thereof. Commercially available amorphous perfluoropolymers are known as Teflon® AF (DuPont), Hyflon® AD (Solvay Solexis) and Cytop® (Asahi Glass).

[0048] Teflon AF® is a family of amorphous fluoropolymers produced by DuPont and made by copolymerization of 2,2-bis-trifluoromethyl-4,5-difluoro-1,3, dioxol (PDD) with other fluorine-containing monomers. Currently, commercial grade Teflon® AF are PDD and tetrafluoroethylene (TFE) copolymers and are known as Teflon® AF1600 and Teflon® AF2400 (DuPont).

[0049] The chemical structure of Teflon® AF1600 and Teflon® AF2400 products is as follows:

(CF₂-CF₂)_x- (CF-CF)_s

<img file="PL1985355T3_D0001.tif" />

0, cf₃ cf₃ x / y = about 36/64 for Teflon® AF1600 (64 mole% PDD) x / y = about 17/83 for Teflon® AF2400 (83 mole% PDD) [0050] Hyflon® AD (from Solvay Solexis) is a family of amorphous perfluoropolymers that are made by copolymerization of 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxol (TTD) and tetrafluoroethylene (TFE). Chemical structure of Hyflon AD®60X and Hyflon products

AD®80X is as follows:

OCF₃ - (CF₂-CF₂)-and

<img file="PL1985355T3_D0002.tif" />

x / y = about 40/60 for Hyflon AD®60X (60 mole% TTD) x / y = about 15/85 for Hyflon AD®80X (85 mole% TTD) [0051] Cytop® is a PBVE polymer produced by Asahi Glass (PBVE = poly (heptafluoro-1-butene-trifluoro-vinyl ether)).

[0052] In addition to the already mentioned commercially available fluoropolymers, there are others known in the art. For example, US Patent 6,248,823 B1 describes solvents for amorphous fluoropolymers such as poly (HFP / TFE), poly (TFE / PMVE) or poly (TFE / PMVE / PEVE) [HFP = hexafluoropropene; TFE = tetrafluoroethylene; PMVE = perfluoro (methyl vinyl ether); PEVE = perfluoro (ethyl vinyl ether)]. Patent EP 0 633 257 describes amorphous homo- and copolymers of perfluorodioxoles. US Patent 5,883,177 describes amorphous TTD-based perfluoropolymers that are dissolved in fluorine-containing solvents to provide coating solutions. US Patent 5,663,255 describes novel amorphous TFE-HFP copolymers. US Patent 5,919,878 describes amorphous fluoropolymers containing PEVE. Patents US 6,248,823 B1, EP 0 633 257, US 5,883,177, US 5,663,255 and US 5,919,878 are included in the literature.

[0053] The first component may also contain hydro- and oleophobic polymers containing respectively PFPE blocks or units obtained by chemical reactions of functional PFPE compounds. For example, EP 1 270 631 A1 describes the preparation of PFPE terminated with isocyanate groups that reacted with hydrogenated diols to obtain urethane polymers with PFPE units. Patent EP 1 270 631 A1 is mentioned herein in the literature.

[0054] The above examples for the first component should serve only as examples. In general, the first component is not particularly limited as long as it contains fluorinated material that is both oleophobic and hydrophobic, i.e. it repels both oils and water.

[0055] Typically, the first component may be deposited in a range of about 0.01-1000 g / m2², about 0.05-500 g / m2², about 0.1-400 g / m2², about 0.5-300 g / m2², about 1-200 g / m2², about 5100 g / m2², about 10-500 g / m2², about 5-100 g / m2² or about 20-40 g / m2². Alternatively, the first coating may be deposited in a range of at least about 0.01 g / m2², 0.1 g / m2², 1 g / m2², 10 g / m2², 20 g / m2², 40 g / m2², 100 g / m2², 500 g / m2² or 1000 g / m2².

[0056] The second component may include any form or combination of neutral PFPE. Generally, PFPEs differ in the type of molecular chain end groups. There are PFPEs having neutral, non-reactive end groups. These types of PFPE are called neutral PFPE and are included in the present invention. They are sometimes referred to as apolar or non-polar PFPE. Common end groups of neutral PFPE are -OCF3, -OC2F5 and -OC3F7. However, neutral PFPE may also contain other types of non-perfluorinated end groups, such as those containing H-, Cl-, Br- or I- radicals.

[0057] In addition, PFPE containing in its backbone (i.e. not only as end groups) radicals such as H-, Cl-, Br-, I- or even others can still be regarded as neutral PFPE according to the present invention as long as they are hydrophobic. An example of a repeating unit of H-, Cl, Br and / or I- in a skeleton may be CR1R2CF2CF2O, where R1 and R2 independently have H, Cl, Br, I or C1-C4 perfluoroalkyl.

[0058] Neutral PFPEs differ from functional PFPEs which may have modified polar and reactive end groups. They are commercially available, for example under the trade name Fluorolink® (Solvay Solexis).

[0059] The present invention relates to inert PFPEs. Inert PFPEs are thermally stable, substantially insoluble in water and most solvents, and cannot be released after applying the coating.

[0060] Commercially available PFPEs suitable for the present invention are for example known under the trade names Fomblin®, Galden® (both from Solvay Solexis), Krytox® (DuPont) and Demnum® (Daikin). These compounds are available in substantially pure form and sometimes provided as a microemulsion in water such as Fomblin FE 20C or Fomblin FE 20 EG.

[0061] A general description of PFPE is found in the book "Modern Fluoropolymers," edited by John Scheirs, Wiley Series in Polymer Science, John Wiley &amp; Sons (Chichester, New York, Wienheim, Brisbane, Singapore, Toronto), 1997, chapter 24: Perfluoropolyethers (Synthesis, Characterization and Applications), which is mentioned here in the literature.

[0062] A description of some of the newer types of PFPE obtained by direct fluorination is described in the book Fluoropolymers 1, Synthesis, edited by G. Hougham, PE Cassidy, K. Johns, T. Davidson, Kluwer Academic / Plenum Publishers (New York, Boston, Dordrecht, London, Moscow), chapter 14.3: Perfluoropolyethers, 1999, which is mentioned here in the literature.

[0063] In most cases, inert PFPEs have basic repeating units selected from any of the following or combinations thereof: CF2O; CF2CF2O; CF (CF3) O; CF2CF2CF2O; CF2CF (CF3) O and CF (CF3) CF2O. Some newer types of PFPE may also contain other repeating units (e.g. C (CF3) 2O) or containing more than three carbon atoms: e.g. C4F8O; or C6F12O.

[0064] Some suitable inert PFPE structures that are commercially available are:

Fomblin® Y:

CF3 - [(OCF (CF3) CF2) m- (OCF2) n-] OCF3 where m + n = from 8 to 45 m / n = from 20 to 1000

Fomblin® Z:

CF3 - [(OCF2CF2) m- (OCF2) n-] OCF3 where m + n = 40 to 180 and m / n = 0.5 to 2

Krytox:

CF3CF2CF2O- (CF (CF3) CF2O) n-CF2CF3 where n = from 10 to 60

Demnum:

CF3CF2CF2O- (CF2CF2CF2O) n-CF2CF3 [0065] A common feature of PFPE is the presence of perfluoroalkyl ether residues. PFPE is a synonym for perfluoropolyalkyl ether. Other commonly used synonyms are "PFPE", "PFPE oil", "PFPE fluid" and "PFPAE".

[0066] The second component may contain any suitable inert PFPE available as a liquid, oil or grease, which may not be water or substantially insoluble in water.

[0067] The second component containing the inert PFPE may be a viscous liquid with a viscosity of from about 10 mPa.s to about 1,000,000 mPa.s, from about 10 mPa.s to about 10,000 mPa.s or preferably from about 100 mPa.s up to about 3000 mPa.s. The second component may have a viscosity above about 50 mPa.s, 100 mPa.s, 150 mPa.s, 200 mPa.s, 250 mPa.s or 300 mPa.s.

Typically, the second component may be a viscous liquid with a viscosity above about 100 mPa.s.

[0068] The second component may have a surface tension less than about 40 mN / m, 30 mN / m, 25 mN / m, 20 mN / m, 15 mN / m or 10 mN / m. Typically, the second component may have a surface tension less than about 28 mN / m. [0069] The second component may have a boiling or decomposition point above about 150 ° C, 200 ° C, 250 ° C or 300 ° C, respectively. Typically, the second component may have a boiling or decomposition point above about 200 ° C.

[0070] The second component may have a vapor pressure at a temperature about 20 ° C lower than about

10^-1 mm Hg, 10^-2 mm Hg, 10^-3 mm Hg, 10^-4 mm Hg, 10^-5 mm Hg, 10^-6 mm Hg or preferably -2 lower than 10 mm Hg.

[0071] Typically, the second component may have a molecular weight in the range of from about 500 amu to about 500,000 amu or from about 1000 amu to about 100,000 amu. Preferably, the molecular weight of the second component may range from about 2,000 amu to about 20,000 amu

[0072] The second component may have an average molecular weight of at least about 1000 amu, 10,000 amu, 50,000 amu or 100,000 amu. Preferably, the second component may have an average molecular weight of at least 1000 amu

[0073] Typically, the second component may be deposited in a range of about 0.01-1000 g / m2², about 0.05-500 g / m2², about 0.1-400 g / m2², about 0.5-300 g / m2², about 1-200 g / m2², about 5-100 g / m2², about 1.0-500, about 5-100 g / m2² or about 20-40 g / m2². Alternatively, the second component may be deposited in a range of at least about 0.01 g / m2², 0.1 g / m2², 1 g / m2², 10 g / m2², 20 g / m2², 40 g / m2², 100 g / m2², 500 g / m2² or 1000 g / m2².

[0074] The fluorine content of the second component may be at least about 1% by weight, 10% by weight, 20% by weight or 40 wt. molecular structure of the second component.

[0075] Preferably, the second component may be substantially chemically inert, have high chemical stability, boiling and decomposition temperatures higher than about 150 ° C and 200 ° C, respectively, have low vapor pressure, low surface tension, oleophobic properties and low solubility in popular solvents .

[0076] Typically, the porous polymer structure may have transitions or continuous pores through the material. The passages can be opened on both sides of the porous polymer structure allowing operation as a vent.

[0077] The porous polymeric structure may be selected from any suitable porous structure and may be in the form of a layer with a thickness from about 0.1 Pm to about 5000 Pm, from about 1 Pm to about 500 Pm, or from about 10 Pm to about 400 Pm. In particular embodiments, the porous polymeric structure may have a thickness of about 100 Pm, about 200 Pm, or about 300 Pm. In alternative embodiments, where the porous polymeric structure is e.g. tapes, the thickness of the tape can range from about 10 μm to about 500 μm.

[0078] Typically, the porous polymeric structure may comprise one fluoropolymer or a combination of fluoropolymers. The porous polymeric structure may include polytetrafuoroethylene (PTFE). The porous polymeric structure may comprise one or a combination of suitable fluoropolymers such as PTFE or polyvinylidene fluoride. Alternatively, the porous polymeric structure may also include non-fluorinated polymers such as any one polyolefin (e.g. polyethylene, polypropylene) or a combination thereof, polyamides, polyester, polysulfone, poly (ether sulfone), polycarbonate, polyurethane or combinations thereof.

[0079] In certain embodiments, the porous polymeric structure may be in the form of a membrane.

[0080] The porous polymeric structure can be developed in at least one direction and can therefore be uniaxially or multi-axially expanded. In a particular embodiment, the porous structure may be developed in two directions, such as substantially orthogonal directions, providing a biaxial structure. Therefore, the porous polymeric structure may be uniaxially or biaxially developed, such as uniaxially or biaxially developed polytetrafluoroethylene.

[0081] The porous polymeric structure may be at least partially composed of fibrils and / or knots.

[0082] In one embodiment, the porous polymeric structure may be, for example, a film of porous ePTFE. The layer thickness, density and pore size of the ePTFE used may vary depending on the application.

[0083] Typically, the ePTFE vent may have a thickness in the range from about 5 μm to about 500 μm, a density in the range from about 0.4 to about 1.5 g / cm³ and an average pore size in the range of from about 0.05 to about 10 μm. Preferred embodiments may have a thickness of from about 30 μm to about 350 μm, a density in the range of from about 0.5 to about 1.5 g / cm³ and an average pore size from about 0.1 to about 5 μm.

[0084] A particularly preferred substrate is porous PTFE made by stretching the PTFE tape or film as described in US Patent 3,953,566, which is mentioned herein in the literature. In this procedure, the structure includes an interconnected network of nodes and fibrils connected to nodes, nodes and fibrils, and fibrils forming an internal pore-forming structure.

[0085] The porous polymeric layer may be an ePTFE membrane, such as that described in US Patent 3,953,566, which is mentioned in the literature [0086] In certain embodiments, the gas-permeable composite may comprise a solution-coated ePTFE layer, e.g. about 0.5-2 wt% Teflon® AF (e.g., Teflon® AF 1600) and about 1-20 wt.% PFPE in a suitable solvent, such as a fluorinated organic solvent. In further embodiments, the gas-permeable composite may comprise an already oleophobic treated membrane that has an additional PFPE coating deposited in the second coating step e.g. with a PFPE coating solution in a concentration in the range of about 1-10 wt.

[0087] According to a second aspect, there is provided a gas-permeable composite comprising:

(a) a porous polymeric structure having a structure comprising a plurality of through pores and at least one outer surface;

(b) a coating covering at least part of said outer surface;

(c) said coating comprising at least a first and a second component;

(d) said first component comprising oleophobic and hydrophobic fluorinated material; and (e) said second component comprising a copolymer block, said copolymer block comprising a PFPE backbone.

[0088] The copolymer block may be in the form of an AB or ABA block, where the A or B units may be based on PFPE, for example non-polar PFPE or neutral PFPE. PFPE may include repeating units such as any single or combination of the following: CF2O; CF2CF2O; CF (CF3) O; CF2CF2CF2O; CF2CF (CF3) O; CF (CF3) CF2O;

- (C (CF3) 2O) -; -CF2CF2CF2CF2O-; - (C4F8O) - or - (C6F12O) -.

[0089] The backbone-forming PFPE is covalently bonded to a non-PFPE block, such as any suitable hydrocarbon-based block. The hydrocarbon-based block may be selected from polyolefins (such as polyethylene, polypropylene), polyester, polyurethane, polyamide or other suitable polymeric components.

[0090] An example of a copolymer block comprising PFPE- and poly (; ', - kapi'olactone) blocks is described in the article Polymer 42 (2001) 1771-1779 (M. Toselli, et al.), Which is mentioned herein in the literature.

[0091] According to a third aspect, there is provided a gas-permeable composite comprising:

(a) a porous polymeric structure having a structure comprising a plurality of through pores and at least one outer surface;

(b) a coating covering at least part of said outer surface;

(c) said coating comprising at least a first and a second component;

(d) said first component comprising oleophobic and hydrophobic fluorinated material; and (e) said second component comprising inert perfluoropolyether (PFPE).

[0092] In most cases, inert PFPEs have basic repeating units selected from any of the following or combinations thereof: CF2O; CF2CF2O; CF (CF3) O; CF2CF2CF2O; CF2CF (CF3) O and CF (CF3) CF2O. Some newer types of neutral PFPE may also contain other repeating units (e.g. C (CF3) 2O) or containing more than three carbon atoms: e.g. C4F8O; or C6F12O, [0093] According to a fourth aspect, there is provided a gas-permeable composite comprising:

(a) a porous polymeric structure having a structure comprising a plurality of through pores and at least one outer surface;

(b) a coating covering at least part of said outer surface;

(c) said coating comprising at least a first and a second component;

(d) said first component comprising oleophobic and hydrophobic fluorinated material; and (e) said second component comprising a fluorinated hydrophobic liquid.

[0094] According to a fifth aspect, there is provided a method of forming a gas-permeable composite, said method comprising:

(a) providing a porous polymeric structure having a structure comprising a plurality of through pores and at least one outer surface;

(b) providing a coating on at least part of said outer surface of said porous polymeric structure, wherein said coating comprises at least a first and a second component, wherein said first material comprises a fluorinated oil and hydrophobic material, and said second component comprises a perfluoropolyether (PFPE), said PFPE includes end groups selected from the following:

- (O) n - (CR1R2) m - CR3R4R5 where:

R1 = H, F, Cl, Br or I;

R2 = H, F, Cl, Br or I;

R3 = H, F, Cl, Br or I;

R4 = H, F, Cl, Br or I;

R5 = H, F, Cl, Br, I, alkyl or aryl;

n = 0 or 1; and m = 0 - 10.

[0095] According to a sixth aspect, there is provided a method of forming a gas-permeable composite, said method comprising:

(a) providing a porous polymeric structure having a structure comprising a plurality of through pores and at least one outer surface;

(e) providing coating on at least part of said outer surface of said porous polymeric structure, wherein said coating comprises at least a first and a second component, wherein said first material comprises a fluorinated oil- and hydrophobic material, and said second component comprises a copolymer block, said copolymer block comprising PFPE skeleton.

[0096] The method includes forming a coating, which can be obtained by dissolving the first and second components together in a suitable solvent to form a coating solution, and then depositing the solution on at least a portion of the outer surface of the porous polymeric structure using a suitable technique. The first and second components may form the coating solution in a suitable concentration, such as about 0.1-50 wt.%, About 0.5-30 wt.%, Or about 1-10 wt.%.

[0097] Typically, an organic solvent such as a fluorinated or perfluorinated organic solvent can be used to dissolve the first and second components. The solvent may be a low molecular weight fluorinated or perfluorinated C1 - C20 or C2 - C10 solvent. Suitable solvents are available

TM TM TM TM under the trade names 3M Fluorinert Liquids, 3M Performance Fluids or 3M Novec^™ Fluids. The solvent is intended to evaporate leaving the first and second components to form a coating. The boiling point of the solvent may be below about

150 ° C, 100 ° C or 70 ° C.

[0098] To form the coating, any suitable deposition technique may be used, such as a roller coating process, dipping, spraying, brush coating, high speed coating, deposition using droppers such as pipettes and the like. In alternative embodiments, the first or second component may be pre-deposited in a first step at least on the outer surface of the porous polymeric structure, and then in the second step the remainder of the first or second component is deposited.

[0099] In certain embodiments, the porous polymeric structure may have an oil or hydrophobic precoat formed from the first component. The second component dissolved in the solvent can then be added on the oil- or hydrophobic coating. Depending on the compatibility of the two components, they can be at least partially dissolved with each other or remain separated. For each of the two separate coating steps, any suitable deposition technique can be used, such as roller coating process, dipping, spraying, brush coating, high speed coating, dropping deposition, such as pipettes and the like. The first component comprising the fluorinated oil and hydrophobic material may be further deposited at the plasma coating stage or other gas phase coating stage.

[0100] The first component may be at least partially dissolved in the second component. It should also be noted that there may be a more than two-component and non-solvent component. The first component may be at least partially dissolved in the second component, especially when a weight ratio of the first to the second component is used, such as about 1: 10 (i.e., an excess of the second component). This may for example be the case of the aforementioned amorphous fluoropolymers (as the first component) and neutral PFPE as the second component.

[0101] After the first component is added to the second, the first and second components can simply be mixed together to form an admixture where there are no chemical reactions or substantially no chemical reactions between the components.

[0102] In certain embodiments, the first component may also be considered displaced by the second component rather than dissolved.

[0103] It has been found that by coating with the mixture of said first and second components, it prevents complete clogging of the pores. Total clogging of the pores of the porous structure can be a problem when using a coating solution with a high concentration of high molecular weight polymers such as Teflon® AF. It is surprisingly found in the present invention that although high total concentrations of said first and second components were used in the coating solution, the pores did not close. Without wishing to be bound by theory, it is believed that complete closing of the pores does not occur due to the low molecular weight range of oils (e.g. molecular weight of several thousand grams / mol, more oligomers than polymers) used as the second component. This surprising discovery has significant advantages because some previously known oleophobic materials (e.g. Teflon® AF1600) are extremely expensive and these expensive materials can now be mixed with much cheaper materials such as fluorinated PFPE oils to provide significant technical benefits such as improved liquid repulsion and avoiding total clogging p.

[0104] The first component prior to forming the coating may be in solid and / or amorphous form and may include any suitable fluorinated or perfluorinated oleophobic and hydrophobic oligomer and / or polymer or a combination thereof. The first component can exist as a solid for example at 20 ° C and a pressure of about 1 bar.

[0105] The second component prior to forming the coating is typically in liquid form and may include inert PFPE.

[0106] According to a seventh aspect, there is provided a venting apparatus having holes for venting gas from a closure or container. Said breather apparatus includes:

a gas-permeable venting composite located inside, outside or on said venting apparatus and forming a liquid impermeable seal on said opening. Said gas-permeable composite includes:

(a) a porous polymeric structure having a structure comprising a plurality of through pores and at least one outer surface;

(b) a coating covering at least part of said outer surface;

(c) said coating comprising at least the first and second components (d) said first component comprising a fluorophilic oleophobic and hydrophobic material; and (e) said second component comprising a perfluoropolyether (PFPE), said PFPE comprising end groups selected from the following:

- (O) n - (CR1R2) m - CR3R4R5 where:

1. R1 = H, F, Cl, Br or I;

2. R2 = H, F, Cl, Br or I;

3. R3 = H, F, Cl, Br or I;

4. R4 = H, F, Cl, Br or I;

5. R5 = H, F, Cl, Br, I, alkyl or aryl;

6. n = 0 or 1; and

7. m = 0-10.

[0107] According to an eighth aspect, there is provided a venting apparatus having holes for venting gas from a closure or container. Said breather apparatus includes:

a gas-permeable venting composite located inside, outside or on said venting apparatus and forming a liquid impermeable seal on said opening. Said gas-permeable composite includes:

(a) a porous polymeric structure having a structure comprising a plurality of through pores and at least one outer surface;

(b) a coating covering at least part of said outer surface;

(c) said coating comprising at least the first and second components (d) said first component comprising a fluorophilic oleophobic and hydrophobic material; and (e) said second component comprising a copolymer block, said copolymer block comprising a PFPE backbone.

[0108] The venting apparatus may be used as a vent for containers (e.g. bottles) containing liquids. The breather may be in the container lid or lid.

[0109] Furthermore, the venting apparatus may be used in the automotive industry, where lubricating oils are used in vehicle engines, transmissions or axles.

[0110] In further applications, the venting apparatus may be used to protect electronic components in cell phones, computers (such as disk drives), automotive (such as sensors, motors, head lamps) or to vent medical equipment.

[0111] According to a ninth aspect, a method of venting gas from a closure or container is provided. This method includes:

providing a gas-permeable vent composite located inside, outside, or on said venting apparatus and forming a liquid impermeable seal to said venting apparatus. Said gas-permeable venting composite includes:

(a) a porous polymeric structure having a structure comprising a plurality of through pores and at least one outer surface;

(b) a coating covering at least part of said outer surface;

(c) said coating comprising at least the first and second components (d) said first component comprising a fluorophilic oleophobic and hydrophobic material; and (e) said second component comprising perfluoropolyether (PFPE), said PFPE comprising end groups selected from the following:

- (O) n - (CR1R2) m - CR3R4R5 where:

R1 = H, F, Cl, Br or I;

R2 = H, F, Cl, Br or I;

R3 = H, F, Cl, Br or I;

R4 = H, F, Cl, Br or I;

R5 = H, F, Cl, Br, I, alkyl or aryl;

n = 0 or 1; and m = 0-10.

[0112] According to a tenth aspect, a method of venting gas from a closure or container is provided. This method includes:

providing a gas-permeable venting composite located inside, outside, or on said venting apparatus and forming a liquid impermeable seal on said venting apparatus. Said gas-permeable venting composite includes:

(a) a porous polymeric structure having a structure comprising a plurality of through pores and at least one outer surface;

(b) a coating covering at least part of said outer surface;

(c) said coating comprising at least the first and second components (d) said first component comprising a fluorophilic oleophobic and hydrophobic material; and (e) said second component comprising a copolymer block, said copolymer block comprising a PFPE backbone.

[0113] The method includes venting or filtering gas in: containers (e.g., bottles) containing highly viscous liquids; automotive applications where lubricating oils are used in vehicle engines and transmissions or axles; protection of electronic components in mobile phones, computers (e.g. hard disks) or automotive applications (e.g. sensors, engines, head lamps) and in applications involving medical equipment.

[0114] According to an eleventh aspect, there is provided a gas-permeable composite comprising:

(a) a porous polymeric structure having a structure comprising a plurality of through pores and at least one outer surface;

(b) a coating covering at least part of said outer surface;

(c) said coating comprising at least a first and a second component;

(d) said first component comprising oleophobic and hydrophobic fluorinated material; and (e) said second component comprising a perfluoropolyether (PFPE), said PFPE comprising end groups selected from the following:

- (O) n - (CR1R2) m - CR3R4R5 where:

R1 = H, F, Cl, Br or I;

R2 = H, F, Cl, Br or I;

R3 = H, F, Cl, Br or I;

R4 = H, F, Cl, Br or I;

R5 = H, F, Cl, Br, I, alkyl or aryl; n = 0 or 1; and m = 0-10;

where the gas-permeable composite has a gas flow recovery (compared to the initial / primary gas flow) greater than about 5% after exposure to a viscous liquid having a viscosity above about 10 mPa.s and a surface tension less than about 35 mN / m at a temperature of about 25 ° C.

[0115] According to a twelfth aspect, there is provided a gas-permeable composite comprising:

(a) a porous polymeric structure having a structure comprising a plurality of through pores and at least one outer surface;

(b) a coating covering at least part of said outer surface;

(c) said coating comprising at least a first and a second component;

(d) said first component comprising oleophobic and hydrophobic fluorinated material; and (e) said second component comprising a copolymer block, said copolymer block comprising a PFPE backbone;

where the gas-permeable composite has a gas flow recovery (compared to the initial / primary gas flow) greater than about 5% after exposure to a viscous liquid having a viscosity above about 10 mPa.s and a surface tension less than about 35 mN / m at a temperature of about 25 ° C.

[0116] Typically, the gas-permeable composite may have a gas flow recovery greater than about 5% upon exposure to a viscous liquid having a viscosity in the range of 10-50 mPa.s and a surface tension greater than about 27 mN / m at a temperature of about 25 ° C.

[0117] According to a thirteenth aspect, there is provided a gas-permeable composite comprising:

(a) a layer of a porous PTFE structure with an internal and external surface having penetrations through the structure;

(b) a porous structure comprising a coating on at least part of said outer surface;

(c) said coating comprising at least a first and a second component;

(d) said first component comprising at least one oil- and hydrophobic fluoropolymer that gives the composite an oil class of at least 3;

(e) said second component comprising perfluoropolyether (PFPE), said PFPE comprising end groups selected from the following:

- (O) n- (CR1R2) m-CR3R4R5 where:

R1 = H, F, Cl, Br or I;

R2 = H, F, Cl, Br or I;

R3 = H, F, Cl, Br or I;

R4 = H, F, Cl, Br or I;

R5 = H, F, Cl, Br, I, alkyl or aryl; n = 0 or 1; and m = 0-10;

wherein the gas-permeable composite has a gas flow recovery greater than about 5% upon exposure to a viscous liquid having a viscosity above 25 ° C at a temperature of about 10 mPa.s and a surface tension less than about 35 mN / m.

[0118] According to a fourteenth aspect, there is provided a gas-permeable composite comprising:

(a) a layer of a porous PTFE structure with an internal and external surface having penetrations through the structure;

(b) a porous structure comprising a coating on at least part of said outer surface;

(c) said coating comprising at least a first and a second component;

(d) said first component comprising at least one oil- and hydrophobic fluoropolymer that gives the composite an oil class of at least 3;

(e) said second component comprising a copolymer block, said copolymer block comprising a PFPE backbone;

where the gas-permeable composite has a gas flow recovery (compared to the initial / primary gas flow) greater than about 5% after exposure to a viscous liquid having a viscosity above about 10 mPa.s and a surface tension less than about 35 mN / m at a temperature of about 25 ° C.

[0119] According to a fifteenth aspect, there is provided a gas-permeable composite obtainable by:

(a) providing a porous polymeric structure having a structure comprising a plurality of through pores and at least one outer surface;

(b) coating at least a portion of said outer surface of the porous polymeric structure with a first and second component;

(c) said first component comprising oleophobic and hydrophobic fluorinated material; and (d) said second component comprising perfluoropolyether (PFPE), said PFPE comprises end groups selected from the following:

- (O) n- (CR1R2) m-CR3R4R5 where:

R1 = H, F, Cl, Br or I;

R2 = H, F, Cl, Br or I;

R3 = H, F, Cl, Br or I;

R4 = H, F, Cl, Br or I;

R5 = H, F, Cl, Br, I, alkyl or aryl;

n = 0 or 1; and m = 0-10.

[0120] According to a sixteenth aspect, there is provided a gas-permeable composite obtainable by:

(a) providing a porous polymeric structure having a structure comprising a plurality of through pores and at least one outer surface;

(b) coating at least a portion of said outer surface of the porous polymeric structure with a first and second component;

(c) said first component comprising oleophobic and hydrophobic fluorinated material; and (d) said second component comprising a copolymer block, said copolymer block comprising a PFPE backbone;

[0121] According to a seventeenth aspect, there is provided the use of a gas-permeable composite in a vent or gas filter. Said gas-permeable composite includes:

(a) a porous polymeric structure having a structure comprising a plurality of through pores and at least one outer surface;

(b) a coating covering at least part of said outer surface;

(c) said coating comprising at least a first and a second component;

(d) said first component comprising oleophobic and hydrophobic fluorinated material; and (e) said second component comprising a perfluoropolyether (PFPE), said PFPE comprising end groups selected from the following:

- (O) n - (CR1R2) m - CR3R4R5 where:

R1 = H, F, Cl, Br or I;

R2 = H, F, Cl, Br or I;

R3 = H, F, Cl, Br or I;

R4 = H, F, Cl, Br or I;

R5 = H, F, Cl, Br, I, alkyl or aryl;

n = 0 or 1; and m = 0-10.

[0122] According to an eighteenth aspect, there is provided a gas-permeable composite in a vent or gas filter, said gas-permeable composite comprising:

(a) a porous polymeric structure having a structure comprising a plurality of through pores and at least one outer surface;

(b) a coating covering at least part of said outer surface;

(c) said coating comprising at least a first and a second component;

(d) said first component comprising oleophobic and hydrophobic fluorinated material; and (e) said second component comprising a copolymer block, said copolymer block comprising a PFPE backbone.

[0123] According to the nineteenth aspect, a gas-permeable composite is provided comprising:

(a) a layer of a porous PTFE structure with an internal and external surface having penetrations through the structure;

(b) a microporous structure comprising a coating on at least part of said outer surface;

(c) said coating comprising at least a first and a second component;

(d) said first component comprising at least one or a combination of oil and hydrophobic amorphous fluoropolymers / perfluoropolymers; and

1. (e) said second component comprising perfluoropolyether (PFPE), said PFPE comprising end groups selected from the following:

- (O) n - (CR1R2) m - CR3R4R5 where:

R1 = H, F, Cl, Br or I;

R2 = H, F, Cl, Br or I;

R3 = H, F, Cl, Br or I;

R4 = H, F, Cl, Br or I;

R5 = H, F, Cl, Br, I, alkyl or aryl;

n = 0 or 1; and m = 0-10.

[0124] According to the twentieth aspect, there is provided a gas-permeable composite comprising:

(a) a layer of a porous PTFE structure with an internal and external surface having penetrations through the structure;

(b) a microporous structure comprising a coating on at least part of said outer surface;

1. (c) said coating having at least a first and a second component;

2. (d) said first component comprising at least one or a combination of oil and hydrophobic amorphous fluoropolymers / perfluoropolymers; and

3. (e) said second component comprising a copolymer block, said copolymer block comprising a PFPE backbone.

BRIEF DESCRIPTION OF THE DRAWINGS [0125] Embodiments of the present invention will be described below only by way of examples with references to the accompanying drawings:

Figure 1 shows a venting apparatus according to an embodiment of the present invention:

Figure 2 is a schematic top view of a coated PTFE structure:

Figures 3A-3C show the apparatus and procedure used to perform the air flow recovery test;

Figure 4 is an enlarged view of part of the apparatus shown in Figure 3A;

Figure 5 shows the apparatus and procedure for performing the vertical immersion test referred to as the "liquid repellency test";

Figures 6A and 6B show the test liquid contained in four different test samples 1-4 at t = 0 and t = 15 s, respectively.

Figures 7A and 7B are exploded views of sample 3 shown in Figures 6A and 6B at t = 0 and t = 15 s, respectively.

Figure 8 shows the coating apparatus used to form a gas-permeable composite.

Figures 9-10 are SEM surface images at various scales of enlargement of a gas-permeable composite that has been coated with a 1 wt.% Solution. Teflon® AF1600 in a fluorinated solvent.

Figures 11-13 are SEM images at various scales of magnification of an air-permeable composite that has been coated with a 1 wt.% Solution. Teflon® AF1600 and 10 wt. PFPE in a fluorinated solvent.

Figure 14 is a graph showing the percentage of surface covered with test liquid versus time for gas-permeable composites;

Figure 15 is a graph showing the percentage of air flow recovery and liquid penetration pressure versus wt.% PFPE in the coating solution for gas-permeable composites;

Figure 16 is a graph showing the percentage of air flow recovery versus wt.% PFPE in the coating solution for gas-permeable composites;

Figure 17 is a graph showing the percentage of surface covered with test liquid versus time for gas-permeable composites;

Figure 18 is a graph showing the percentage of air flow recovery and liquid entry pressure versus wt.% PFPE in the coating solution for gas-permeable composites;

Figure 19 is a graph showing the percentage of surface covered with test liquid versus time for gas-permeable composites;

Figure 20 compares SEM images of two samples, the first of which is coated with a 1 wt. Teflon® AF1600 in a fluorinated solvent (image left) and the other is coated with a 1 wt. Teflon® AF1600 and 10 wt. PFPE in a fluorinated solvent (image on the right); and

Figures 21-22 are SEM images at various scales of enlargement of an air-permeable composite that has been coated with a 1 wt.% Solution. Teflon® AF1600 in a fluorinated solvent.

Figures 23-24 are SEM images at various scales of magnification of an air-permeable composite that has been coated with a 1 wt.% Solution. Teflon® AP1600 and 4 wt. PFPE in a fluorinated solvent.

DETAILED DESCRIPTION OF THE INVENTION [0126] Figure 1 is one possible representation of the apparatus of the present invention and generally designated 100. The apparatus 100 includes a cover 102 including a gas-permeable vent 104 (e.g., an air-permeable vent). The gas-permeable vent 104 is centrally located in the cover 102 and allows gas 110 to flow through the vent 104. Although not shown, the gas-permeable vent 104 need not be centrally located in the lid 102. The lid 102 is attached to the container 106 by a screw. The container 106 contains a low surface tension viscous liquid 108. The container 106 can be used as a container for any type of liquid. According to Figure 1, any viscous liquid 109 in contact with the gas-permeable vent 104 is repelled. The cover 102 and the gas-permeable vent 104 contained therein form a liquid-impermeable and gas-permeable seal to the container 106.

[0127] Figure 2 is a schematic top view of a uniaxially developed PTFE structure generally designated 200, which can form the outer layer of a porous composite. The structure of PTFE 200 consists of nodes 210 and fibrils 212 with pores 214 located between the fibrils 212. On the surface of the fibrils 212, between some fibrils 212 and on the top of the nodes 210 there is a coating layer 216 (visible as shading). Coating layer 216 is a combination of a first component comprising an oleophobic and hydrophobic fluorinated material and a second component. The second component includes PFPE. Said PFPE contains end groups selected from the following:

- (O) n - (CR1R2) m - CR3R4R5 where:

R1 = H, F, Cl, Br or I;

R2 = H, F, Cl, Br or I;

R3 = H, F, Cl, Br or I;

R4 = H, F, Cl, Br or I;

R5 = H, F, Cl, Br, I, alkyl or aryl;

n = 0 or 1; and m = 0-10;

Alternatively, the second component is a copolymer block comprising a PFPE backbone.

[0128] Coating layer 216 covers / fills at least some of the pores 214 formed by the space between the fibrils 212. Coating layer 216 can cover / fill at least part 214 on the outermost surface of the PTFE structure 200, but can also partially penetrate / impregnate the main part of the structure PTFE 200. Therefore, coating layer 216 covers nodes 210 and fibrils 212 of the outer surface of the PTFE structure 200 and can block and / or close some pores of the surface 214 of the PTFE structure 200.

DEFINITION OF TERMS [0129] A "gas-permeable composite" is understood to be a porous material that allows air or other gases to pass. It is different from porous materials, where gas permeability is controlled by diffusion mechanisms. [0130] As "oleophobic (coating) component / material" is meant a material that repels oils. Typically, these materials are fluorinated and have surface energies lower than about 26 nm / N, preferably below about 24 mN / m and most preferably below about 20 mN / m.

[0131] An "oleophobic substrate / composite / membrane" is understood to be a porous product that according to the AATCC test method 118-1989 has an oil class of at least 1. This means that the gas-permeable substrate / composite / membrane has a degree of oil repulsion and / or low surface tension liquids.

[0132] As "hydrophobic (coating) component" is meant a material that repels water. Typically, these materials are substantially insoluble in water and have contact angles of water above about 60 °, preferably above about 90 °.

[0133] As "solid" is meant a state of matter that can support loads, has a specific shape and volume, and whose building blocks have a substantially fixed position in space relative to each other, which means a degree of rigidity.

[0134] As "liquid" is meant a state of matter that has the ability to flow under the influence of extremely low shear stresses and take the shape of the vessel that limits it. The term "liquid" also includes all forms of oils and greases.

[0135] By "liquid impermeable seal" is meant a seal that can withstand a water penetration pressure of at least about 0.03 bar without leakage.

[0136] By "outer surface" is meant the outermost layer expanding around the outer edge of the porous polymeric structure that can be touched and first comes into contact with the liquid to be repelled. This outer layer is important in repelling liquids. The term "outer layer" is not intended to include the inner structure in the main body of the porous polymeric structure. [0137] The term "coating" is understood to mean the material covering the surfaces on the "outer surface" of the porous polymeric structure and the internal structure in the main part of the porous polymeric structure. The coating may also form at least one or more or many closed and / or blocked surface portions, e.g. areas with a closed and / or gas-permeable coating layer.

[0138] As "fluorescent material" is meant a material containing at least 1 wt. fluorine [0139] As "neutral PFPE" is meant a perfluoropolyether with neutral or non-reactive end groups. They are sometimes referred to as apolar or non-polar PFPE. Neutral PFPE differs from functional PFPE which contain reactive end groups. Common end groups of neutral PFPE are -OCF3, -OC2F5 and -OC3F7. However, there may also be other types of unperfluorated end groups, such as those containing H-, Cl-, Br- or I- radicals. Examples of unperfluorinated neutral PFPE end groups include structures such as -CF2R (R = H, Cl, Br or I) or -CFR-CF3 (R = H, Cl, Br or I). In addition, PFPE containing in its backbone (i.e. not only as end groups), radicals such as H-, Cl-, I-Br- or even others can still be regarded as neutral PFPE according to the present invention as long as they are hydrophobic.

[0140] A "porous" is a material that allows the passage of gases, especially air. They include materials that contain pores and spaces that form a passage through the entire thickness of the material. Such materials have very small, microscopic spaces in the internal structure that create interconnected air paths (passages) from one surface to another. The passages are open on both sides of the material and can be interconnected internally, for example, by fibrils and nodes.

[0141] As "polymer structure" is meant any form of dimer, trimer or other forms of higher addition compounds, copolymers, block copolymers, terpolymers, branched polymers, crosslinked polymers, low molecular weight polymers or high molecular weight polymers. The "polymer structure" can be formed as a result of a polymerization reaction, such as radical polymerization, condensation or addition, and can contain repeating structural units and / or monomers connected by covalent bonds.

[0142] An "oligomer" is understood to be a relatively small number of monomer units, such as less than about 100 monomer units or less than about 30 monomer units.

[0143] As "component" is meant a chemical molecule, compound and / or composition that can be used as one of the components to form a coating.

Definition of the term "liquid repulsion" [0144] The term "liquid repulsion" serves as a general term for the ability of a surface to repel or remove liquid from a surface when forces such as gravity or surface tension are applied. The term is used regardless of the exact mechanism by which the liquid is repelled or leaves the surface. This implies squeezing the liquid on the surface into the droplets, but also forming a film of liquid on the surface that contracts and / or slides or other suitable mechanism.

[0145] There was also a need for a test method that quantifies the liquid repellency properties of a porous substrate. The test method is described below.

TEST DESCRIPTIONS

Oil grade [0146] The oil grade was determined using the AATCC 118-1989 test method. The higher the oil grade, the better the oil repellency / resistance. A value higher than 1, more preferably 4 or higher is preferred. The oil grade was determined on the side where the coating solution was applied or on the side facing the coating solution bath.

Water penetration pressure [0147] Water penetration pressure provides a method for testing the penetration of water through the membranes. The test sample is placed between a pair of test plates. The bottom plate has the ability to squeeze some of the sample with water. A pH control paper is placed in the upper part of the sample between the plates on the non-compressed side as an indicator of water ingress. The next sample is compressed at a rate of 1 bar / 100 seconds until the pH paper is wetted, which is the first sign of water ingress. Water pressure during breakthrough is recorded as water penetration pressure.

Liquid penetration pressure [0148] The same test method as described for the measurement of the water penetration pressure was used, only the water was replaced with another liquid. In all measurements, the tested liquid contained 68 wt. water, 30% by weight 2-propanol (isopropanol, 99%) and 2 wt. sodium dodecyl sulfate (SDS). A surface tension of 26.5 mN / m and a viscosity of 2.5 mPa.s were measured for this test liquid at 25 ° C (at 50 s shear rate)¹) (this test liquid was used as an approximation to standard liquid cleaners).

Gurley air flow data [0149] The Gurley air flow test measures the time in seconds for 100 cm3 of air flowing through a 1 square inch sample at a water pressure of 4.88 inches. The sample is measured with a Gurley model 4110 density meter (ASTM 0726-58). The sample is placed between the clamping plates. Then the cylinder gently drops. The automatic stopwatch is used to record the time (seconds) required to move the volume described above through the cylinder. This time is Gurley's number.

Pore ​​size [0150] The pore size is determined using a standard PMI porometer, model CFP1500 AEXL. For wetting the pores, use a silicone fluid (personal care silicones, 200 10 cst, Dow Corning). The specific average pore flow size is given as the pore size of the substrates used in the examples.

Surface tension measurement [0151] The surface tension of the fluid tested was determined using a Kmss K-12 tensiometer using Kmss K12 equipment and Wilhelma's plate method. Dipping plates

Wilhelmy was carried out using a standard Kmss flame plate and default software parameters. All given surface tensions refer to a temperature of 25 ° C.

Viscosity measurements [0152] The viscosity of these reference liquids was determined using a Haake rheometer, model RheoStress 1. A plate / cone system (cone designation C35 / 2 Ti) was used in all measurements. All viscosities given refer to a temperature of 25 ° C and a shear rate of 50 s^-1.

Coating deposition assay [0153] Total coating deposition was determined by extraction in hot solvent. For measurement purposes, discs with a diameter of 25 mm of all samples were weighed before and after extraction in hot solvent. Coating deposition was determined from the weight difference of these samples.

[0154] Samples were extracted for several days first in hot perfluorinated solvent FC-77 (from 3M), then in hot perfluorinated solvent HFE-7500 (from 3M) until no more weight loss of the samples was detected.

Air flow recovery test [0155] Figures 3A-3C show the air flow recovery test. Figure 3A is a schematic representation of an apparatus for testing air flow recovery, generally designated 300. The apparatus for testing air flow recovery 300 includes a cylindrical container 302 with a diameter of 80 mm, which can be used to maintain a volume of 100 ml of test liquid 304. As a test liquid based on water containing 3 wt. polyvinylpyrrolidone (from the Aldrich Company, art. no. 437190, average molecular weight 1,300,000 determined by light scattering), 3 wt. Tegoprene® 5847 silicone surfactant (wetting agent from Goldschmidt AG) and 94 wt. deionized water. For the test liquid at 25 ° C, the surface tension was measured 23 mN / m and the viscosity was 13.7 mPa.s (at a shear rate of 50 s^-1). The test liquid must always be freshly prepared on the day of determination. This test liquid was used to characterize all samples and unless otherwise specified, all airflow data after performing the airflow recovery test refer to that test liquid.

[0156] A second liquid (viscous oil) was used only for three samples (Examples 1, 4 and 5) to demonstrate the surface's ability to repel oils. The designation of this oil is "Castrol Transmax Z" (fluid for automatic transmissions from Deutsche Castrol VertriebsgeseHschaft GmbH, Hamburg). Surface tension 29.5 mN / m and viscosity 59.7 mPa.s measured at 25 ° C (50 s shear rate)^-1) [0157] As shown in Figure 3A, there is an adapter 306 through which air can enter the container 302 to measure the initial air flow and residual air flow upon contact with the liquid. Both air flows were measured at a pressure of 1.2 bar (i.e. at an overpressure of 12 mbar compared to ambient pressure) giving air flow in normal / standard units - liters / hour / cm². All of the following airflow recovery test data refers to units that are standard liters / hours / cm² measured at a pressure of 12 mbar.

[0158] The tested membrane is at the upper end 308 of container 302. Figure 4 is an exploded view of the upper end 308 of container 302, which shows a microporous test sample 310 expanding through container neck 302a 302. Container material 302 and neck 302a are constructed of polycarbonate (Makrolon ®).

[0159] The neck radius 302a was 1 mm. The microporous porous sample 310 is fixed in place using an insertion ring 312 and a pressure plate 314. A substantially circular cross-section of a 20mm diameter microporous test sample is exposed to the test liquid 304. If the test sample has a smaller diameter, an adapter plate can be used to seal and locate the plate test or vent on neck 302a. Simple calculations can then be performed to scale the results obtained for these smaller types of microporous test samples. Smaller samples can then be measured with the aid of an apparatus.

[0160] To perform the air flow recovery test, the container 302 shown in Figure 3B is inverted so that the test liquid 304 comes into contact with the microporous test sample 310 for 5 seconds. The height of the liquid column and the test sample is 2 cm. As shown in Figure 3C, the container 302 is returned to its original position, where after waiting exactly 5 minutes the residual air flow was measured. The air flow recovery test was carried out at room temperature.

[0161] The percentage of air flow recovery of the test sample was determined by the following formula: (residual air flow / initial air flow) * 100. Both air flows were determined as described in the air flow recovery test.

Liquid repellency test [0162] Figure 5 shows the apparatus 400 used to perform the liquid repellency test. [0163] On one side of the glass plate 402 (3.4 cm x 8 cm) a double-sided adhesive tape 404 was placed, on which a sample of the tested microporous substrate 406 is attached. [0164] To carry out the liquid repellency test, the glass plate 402 with the attached porous substrate 406 is immersed vertically in bath 408 containing the test liquid 410 for about 1-2 seconds and then pulled out. The test liquid is colored with a few drops (5 drops per 100 g liquid) of the following blue dye solution: Duasyn Cyan FRL 10 liq. (Clariant. Produkte (Deutschland) GmbH, Frankfurt am Main). The test is practically carried out by vertically attaching a glass plate 402 with a sample holder (not shown) and lifting the bath 408 with test liquid 410 until about 80% of the length of the attached porous substrate 406. After immersion for about 1-2 seconds, the bath 408 is quickly removed from the bottom and thin film of the test liquid 410 remain on the outer surface 406a of the porous substrate 406. Sliding and squeezing the liquid film 410 on the outer surface 406a can be recorded with a video camera 412 for evaluation.

[0165] Figures 6A and 6B show a typical parallel assessment of four SarTlples 1, 2, 3, 4 tests. Sample 1 was coated with a 1 wt.% Solution. Teflon® AF1600 in a fluorinated solvent, Sample 2 was coated with a 1 wt. Teflon® A.F1600 and 1 wt. PFPE in a fluorinated solvent, Sample 3 was coated with a 1 wt. Teflon® AF1600 and 5 wt. PFPE and Sample 4 was coated with a 1 wt.% Solution Teflon® AF1600 and 10 wt. PFPE in a fluorinated solvent. The PFPE used was Fomblin® Y LVAC 25/6 (Solvay Solexis; average molecular weight: 3300 u). Figure 6A shows the first snapshot immediately after removal of the bath (t = 0 seconds) and Figure 6B shows the second snapshot after a waiting time of 15 seconds. The test liquid used is a mixture of water, polyvinylpyrrolidone and a silicone surfactant (Tegoprene® 5847) as previously described. The test liquid had a surface tension of 23 mN / m and a viscosity of 13.7 mPa.s (at a shear rate of 50 s^-1) measured at 25 ° C. [0166] Figure 6B shows that Sample 1 is ineffective in repelling the test liquid because the percentage of the covered surface remains almost unchanged after 15 seconds. However, Samples 3-4 coated with increasing amounts of PFPE show much better liquid repellency. Sample 4 has the best liquid repelling properties because after 15 seconds virtually all of the test liquid was pushed away.

[0167] Figures 7A and 7B are enlarged views of images of Sample 3 after a time t = 0 seconds and t = 15 seconds, respectively. The liquid repellency test requires a portion of the area within the area being assessed that is still obscured by the test liquid after a specified time t. In the case of Sample 3, after a waiting time of 1.5 seconds, approximately 50% of the test area is still covered by the test liquid. The area evaluated was 2.5 cm (sample width) x 4.0 cm (distance from the liquid border after t = 0 seconds to the bottom edge).

[0168] Although certain embodiments of the present invention have been described above, uses other than the described embodiments may still fall within the scope of the present invention. For example, any suitable fluorinated oleophobic and hydrophobic material may be used to form the first component, and any suitable second PFPE containing component with the following end groups may be used:

- (O) n - (CR1R2) m - CR3R4R5 where:

R1 = H, F, Cl, Br or I;

R2 = H, F, Cl, Br or I;

R3 = H, F, Cl, Br or I;

R4 = H, F, Cl, Br or I;

R5 = H, F, Cl, Br, I, alkyl or aryl; n = 0 or 1; and m = 0-10.

[0169] Alternatively, the second component may comprise a copolymer block comprising a PFPE backbone.

EXAMPLES [0170] In the examples below, four different developed polytetrafluoroethylene (cPTFE) membranes were used as the porous polymer substrate.

Substrate 1 [0171] An uncoated porous uniaxial expanded polytetrafluoroethylene membrane having a thickness of 308 μm, basis weight 275 g / m 2 was used², porosity 59.3%, average pore size 0.32 μm, air flow 24 Gurley seconds, water penetration pressure 0.93 bar and oil grade 2. A polytetrafluoroethylene membrane can be manufactured as described in US Patent 3,953,566, which is mentioned here in literature

Substrate 2 [0172] An uncoated expanded porous polytetrafluoroethylene membrane commercially available as article number 13883na from WLGore &amp; Associates was used. The polytetrafluoroethylene membrane has a porosity of 53% and has been oleophobically treated with fluoromethacrylate.

[0173] This oleophobic treated ePTFE membrane has a thickness of 1.91 μm, basis weight 205 g / m², porosity 51%, average pore size 0.72 μm, air flow 25 Gurley seconds, water penetration pressure 1.19 bar and oil class 8.

Substrate 3 [0174] A commercially available ePTFE membrane developed biaxially (available from W.

L. Gore &amp; Associates GmbH, Germany, article number GMP 20233). This ePTFE membrane is 25 μm thick, 16 g / m2 basis weight², porosity 71%, average pore size 0.19 μm, air flow 13.4 Gurley seconds, water penetration pressure 4.38 bar and oil class 1.

Substrate 4 [0175] An uncoated, uniaxial expanded polytetrafluoroethylene membrane having a thickness of 106 μm, width 12.0 cm, basis weight 83 g / m was used², porosity 64%, average pore size 0.32 μm, air flow 22 Gurley seconds, water penetration pressure 1.40 bar and oil class 1. Polytetrafluoroethylene membrane can be manufactured as described in US Patent 3,953,566, which is mentioned in the literature .

[0176] The parameters and properties of Substrates 1, 2, 3 and 4 are shown in Table 1 below.

Table 1

<td>No. ground</td><td>Thickness &lt;^^m)</td><td>Weight (G / m²)</td><td>Density (G / cm³)</td><td>Porosity (%)</td><td>Size time PMI MFP AVG &lt;^^m)</td><td>Air flow in Gurley units</td><td>Pressure penetration water (bar)</td><td>Grade oil</td>

<td>Subsoil 1</td><td> 308</td><td> 275</td><td> 0,892</td><td> 59,3</td><td> 0,32</td><td> 24,2</td><td> 0,93</td><td> 2</td>

<td>Subsoil 2</td><td> 191</td><td> 205</td><td> 1,074</td><td> 51,0</td><td> 0,72</td><td> 25,4</td><td> 1,19</td><td> 8</td>

<td>Subsoil 3</td><td> 25</td><td> 16</td><td> 0,636</td><td> 71,0</td><td> 0,19</td><td> 13,4</td><td> 4,38</td><td> 1</td>

<td>Subsoil 4</td><td> 106</td><td> 83</td><td> 0,789</td><td> 64,0</td><td> 0,32</td><td> 22</td><td> 1,40</td><td> 1</td>

[0177] Substrates 1, 2, 3 and 4 were treated to form composites. Two different coating processes were used for processing.

Coating process A - continuous dipping / immersion process [0178] Figure 8 shows the apparatus generally designated 500 used in the coating process A. According to Figure 8, the microporous substrate 502 is passed through the first roller 504 and then through the immersion roller 506 it is passed through bath 508 containing coating solution 510. The rate at which substrate 502 passes through the bath 508 is adjustable (typically about 1 m / min) so the opaque microporous substrate 502 is substantially transparent when pulled out of the bath 508 (as an indication of filling the pores with the coating solution). The coated substrate is then attached to a stretching machine (not shown) and passed through an oven (not shown) for a retention time of 2 minutes to completely remove the solvent. The oven temperature may vary depending on the solvent to be evaporated, for example in the range of about 25-150 ° C. Regarding the described Examples 1-15, the oven temperature was in the range of 80-100 ° C.

Discontinuous coating process B - manual processing of the sample [0179] On one side of the glass plate (2.5 cm x 7.5 cm) a double-sided adhesive tape was placed on which a sample of the test substrate was attached.

[0180] The attached substrate is then held at an angle of about 60 ° above the gutter and saturated with the coating solution by means of a pipette. The coating solution wetted the pores of the substrate almost immediately (i.e., the pores were filled with the coating solution because usually the opaque PTFE membrane became transparent) and excess solution dripped into the trough.

[0181] The coated substrate is then dried for 10 minutes at room temperature in a fume hood and for an additional 5 minutes at 100 ° C in a ventilated oven. [0182] The following Examples were tested for air permeability (reported in Gurley seconds), water penetration pressure, liquid penetration pressure, oil wetting resistance (oil grade), initial air flow and residual air flow after exposure to the test liquid.

Comparative Example 1 [0183] Substrate 1 was coated only with a 1 wt. Teflon® AF1600 in the continuous coating process A. Teflon® AF1600 makes the substrate oleophobic. Teflon® AF1600 coating deposition was about 3.7 g / m2².

[0184] The coating solution was obtained by placing 1 g of tetrafluoroethylene copolymer (TFE) and 2,2-bis-trifluoromethyl-4,5-difluoro-1,3-dioxol (PDD), an amorphous fluoropolymer Teflon® AF1600 (64 mol% PDD) supplied by DuPont in 99 g of perfluorinated solvent PF-5070 (from 3M) to obtain 1 wt. Teflon® AF1600 solution. The mixture was stirred for about 6 hours at room temperature until the Teflon® AF1600 was completely dissolved.

[0185] The obtained coated substrate 1 had an oil class of 6 and was therefore oleophobic.

In addition, coated substrate 1 had an air flow of about 17 Gurley seconds, water penetration pressure about 0.93 bar, and liquid penetration pressure about 0.27 bar. The initial air flow of coated substrate 1 was 3.32 l / h / cm² (measured at a pressure of 12 mbar).

[0186] The residual air flow after the air flow recovery test was 0.0 l / h / cm² (measured at a pressure of 12 mbar). Therefore, there was no airflow recovery after exposure to the test liquid as described in the airflow recovery test. [0187] Figures 9 and 10 show two SEM images of the surface at different magnifications in Example 1.

[0188] All measured data are shown in Table 2 below.

Comparative Example 2 [0189] Substrate 1 was coated with a coating solution of 10 wt. PFPE using the continuous coating process A. The PFPE coating deposition was about 38.2 g / m2².

[0190] The coating solution was obtained by placing 10 g PFPE (Fomblin® Y LVAC 25/6 from Solvay Solexis) in 90 g perfluorinated solvent PF-5070 (from 3M) to obtain 10 wt. PFPE coating solution. The solution was shaken until the PFPE was completely dissolved.

[0191] This coated substrate showed only a very low oil class 2, a Gurley number of about 12.1 seconds, a water entry pressure of about 0.71 bar and a liquid entry pressure of about 0.07 bar. The initial air flow of coated substrate 1 was 4.20 l / h / cm²(measured at 1.2 mbar).

[0192] The residual air flow after the air flow recovery test was about 3.04 L / h / cm² (measured at a pressure of 12 mbar). Therefore, this example in the air flow recovery test showed air flow recovery after exposure to the tested liquid with low surface tension, but a very low oil class and very low liquid penetration pressure. For this reason, the sample will be wetted after prolonged exposure to liquids with low surface tension or after applying some hydrostatic pressure. [0193] All measured data are shown in Table 2 below.

Example 3 [0194] Substrate 1 was coated with a coating solution comprising 1 wt. Teflon® AF1600 and 1 wt. PFPE using the continuous coating process A. The total coating deposition was about 7.5 g / m2².

[0195] The coating solution was obtained by placing 1 g of Teflon® AF1600 and 1 g of PFPE (Fomblin® Y LVAC 25/6) in 98 g of the perfluorinated solvent PF-5070 (from the company 3M) to obtain a coating solution of 1 wt. Teflon® AF1600 / 1 wt. PFPE. The mixture was stirred for about 6 hours at room temperature until the Teflon® AF1600 was completely dissolved.

[0196] The resulting coated Example 3 showed an oil grade 7, air flow of 15.3 Gurley seconds, water penetration pressure about 0.86 bar and liquid penetration pressure about 0.26 bar.

[0197] The residual air flow after the air flow recovery test was 0.0 l / h / cm² (at a pressure of 12 mbar). Therefore, the sample did not show airflow recovery after exposure to the test liquid as described in the airflow recovery test.

[0198] All measured data are shown in Table 2 below.

Example 4 [0199] Substrate 1 was coated with a coating solution comprising 1 wt. Teflon® AF1600 and 5 wt. PFPE (Fomblin® Y LVAC 25/6) using the continuous coating process A. The total coating deposition was about 23.5 g / m2².

[0200] The coating solution was obtained by placing 1 g of Teflon® AF1600 and 5 g of PFPE (Fomblin® Y LVAC 25/6) in 94 g of the perfluorinated solvent PF-5070 (from the company 3M) to obtain a coating solution of 1 wt. Teflon® AF1600 / 5 wt. PFPE. The mixture was stirred for about 6 hours at room temperature until the Teflon® AF1600 was completely dissolved.

[0201] The resulting coated substrate 1 exhibited an oil class of 6, a Gurley number of about 12.5 s, a water penetration pressure of about 0.79 bar and a liquid penetration pressure of about 0.19 bar. The initial air flow of coated substrate 1 was about 3.87 l / h / cm²(measured at a pressure of 12 mbar).

[0202] This sample showed a residual air flow of about 2.79 L / h / cm after the air flow recovery test² (measured at a pressure of 12 mbar). This corresponds to an air flow recovery of 72%.

[0203] For this reason, the sample showed both high liquid penetration pressure, which is important in practical venting applications, and good liquid repellency properties exhibited by high airflow recovery after exposure in an airflow recovery test.

[0204] All measured data are shown in Table 2 below.

Example 5 [0205] Substrate 1 was coated with a coating solution comprising 1 wt. Teflon® AF1600 and 10 wt. PFPE using the continuous coating process A. The total coating deposition was about 42.1 g / m2².

[0206] The coating solution was obtained by placing 1 g of Teflon® 10g and 10 g of PFPE (Fomblin® Y LVAC 25/6) in 89 g of the perfluorinated solvent PF-5070 (from 3M company) to obtain a coating solution of 1 wt. Teflon® AF1600 / 10 wt. PFPE. The mixture was stirred for about 6 hours at room temperature until the Teflon® AF1600 was completely dissolved.

[0207] The resulting coated substrate had an oil class of 5, a Gurley number of about 11 s, a water penetration pressure of about 0.73 bar, and a liquid penetration pressure of about 0.12 bar. The initial air flow of coated substrate 1 was 4.76 l / h / cm²(measured at a pressure of 12 mbar).

[0208] This sample showed a residual air flow of about 3.58 l / h / cm after the air flow recovery test² (measured at a pressure of 12 mbar). This corresponds to an air flow recovery of 75.2%.

[0209] For this reason, the sample showed both high liquid entry pressure and air flow recovery after exposure in an air flow recovery test.

[0210] All measured data are shown in Table 2.

[0211] Figures 11 and 12 show two SEM images of the surface of Example 5 coated with an addition of 10 wt. PFPE for a 1 wt.% Solution Teflon® AF 1600. The surface of Example 5 shows both significantly improved liquid repellency parameters and a clear difference in visual characteristics compared to Example 1. Example 5 shows bridging elements between nodal surface island regions. These bridging elements contain pores (composed of spaces between two fibrils) that are (at least partially) filled or covered with coating elements. There are also visible clusters of covered / covered leeks.

[0212] Figure 13 is a larger enlarged view of Example 5.

[0213] Without wishing to be bound by theory, it is believed that these bridge elements are at least partly responsible for better liquid repulsion characteristics. Another noteworthy point is that although some of the pores have been closed or obstructed, the airflow through the coated composite has not deteriorated and continued to exhibit high airflow values.

[0214]

<td rowspan="3">Air flow recovery test</td><td>% recovery flow air</td><td>ο</td><td> 72,3</td><td>Ο</td><td> 72,0</td><td> 75,2</td>

<td>residual flow air (L / h / cm²) at 12 mbar</td><td>ο</td><td> 3,04</td><td>Ο</td><td>ο t '; &lt;Ν</td><td> 3,58</td>

<td>Initial flow air (L / h / cm²) at 12 mbar</td><td>&lt;Ν</td><td></td><td></td><td> 3,87</td><td>ο t "·" 'Τ</td>

<td></td><td>Pressure penetration liquid (bar)</td><td> 0,27</td><td> 0,07</td><td> 0,26</td><td> 0,19</td><td> 0,12</td>

<td></td><td>Pressure water penetration (bar)</td><td> 0,93</td><td> 0,71</td><td> 0,86</td><td>Ο t ' θ '</td><td> 0,73</td>

<td></td><td>Air permeability (Gurley) (s)</td><td>t '</td><td>&lt;Ν</td><td> 1.5.3</td><td>υη σί</td><td>&lt;Ν</td>

<td></td><td>Grade oil</td><td>Ο</td><td>&lt;Ν</td><td>t '</td><td>ο</td><td></td>

<td></td><td>total coating deposition (g / m²)</td><td>ι&gt;</td><td> 38,2</td><td>υη ι&gt;</td><td> 23,5</td><td> 42,1</td>

<td></td><td>Composition of the coating solution</td><td>1% AF1600</td><td>10% PFPE</td><td>1% AF1600 / 1% PFPE</td><td>1% AF1600 / 5% PFPE</td><td>1% AF1600 / 10% PFPE</td>

<td></td><td>Example</td><td> -</td><td>&lt;Ν</td><td>ΓΌ</td><td>ΧΓ</td><td></td>

[0215] Figure 14 is a graph showing the percentage of surface covered with test liquid versus time using the liquid repellency test in Examples 1, 3, 4 and 5. The described mixture of water, polyvinylpyrrolidone and Tegoprene® 5847 has already been used as the test liquid. For the test liquid at temperature A surface tension of 23 mN / m and a viscosity of 13.7 mPa.s (at a shear factor of 50 s) were measured at 25 ° C^-1). The graph clearly showed that Examples 4 and 5 having both Teflon® AF1600 and PFPE coatings had significantly improved repellency against the test mixture than Example 1 coated only with Teflon® AF1600.

[0216] Figure 15 shows% air flow recovery versus% PFPE oil in the coating solution with reference to Examples 1, 3, 4, 5. In addition, the liquid entry pressure of the samples is plotted. Figure 15 additionally shows the corresponding samples described in Example 2, which were only coated with PFPE oil. The tested liquid for measuring the pressure of liquid penetration was already a mixture of water, 2-propanol and sodium dodecyl sulfate (surface tension: 26.5 mN / m; viscosity: 2.8 mPa.s). Figure 15 clearly shows that with both coating components both much better air flow recovery and high liquid penetration pressure can be achieved.

[0217] Figure 16 shows% air flow recovery versus% PFPE in the coating solution for Examples 1, 4 and 5. This time, viscous oil (Castrol Transmax Z, automatic transmission fluid from Deutsche Castrol VertriebsgeseHschaft GmbH, Hamburg) was used as the test liquid. Again, after adding PFPE to the coating formulation, significant improvement in airflow recovery was recorded. All measured data are collected in Table 3.

Table 3: Results of the air flow recovery test with Castrol Transmax Z gear oil for Examples 1, 4, 5 (Substrate 1).

<td></td><td></td><td colspan="3">Air flow recovery test</td>

<td>Example</td><td>Composition of the coating solution</td><td>Initial air flow (l / h / cm²) at 12 mbar</td><td>Residual air flow (l / h / cm²) at 12 mbar</td><td>% air flow recovery</td>

<td> 1</td><td>1% AF1600</td><td> 3,17</td><td> 1,56</td><td> 49,3</td>

<td> 4</td><td>1% AF1600 / 5% PFPE</td><td> 4,11</td><td> 3,85</td><td> 93,7</td>

<td> 5</td><td>1% AF1600 / 10% PFPE</td><td> 4,76</td><td> 4,58</td><td> 96,2</td>

[0218] The following Examples (Examples 6-9) were made to demonstrate that improved liquid repellency can also be achieved after applying one of the two components first and then the second component in the second coating step. Then fluoromethacrylate was used as the first oleophobic and hydrophobic component.

Examples start with an already oleophobic treated Substrate 2 (Example 6), where more and more PFPE oil is gradually added (Examples 7-9).

Comparative Example 6 [0219] The oleophobic medium 2 was tested without any addition of PFPE. Substrate 2 exhibited an oil class of 8, a Gurley number of about 25.5 s, a water entry pressure of about 1.11 bar, and a liquid entry pressure of about 0.33 bar. The initial air flow of oleophobic substrate 2 was 2.20 l / h / cm² (measured at a pressure of 12 mbar).

[0220] The residual air flow was 0.0 l / h / cm² (measured at a pressure of 12 mbar). Therefore, there was no airflow recovery in the airflow recovery test. All measured data are shown in Table 4 below.

Example 7 [0221] The oleophobic substrate 2 was coated with a coating solution of 1 wt. PFPE using the continuous coating process A. The total coating deposition was about 6.4 g / m2².

[0222] The coating solution was obtained by placing 1 g of PFPE (Fomblin® Y LVAC 25/6 from the company Solvay Solexis) in 99 g of the perfluorinated solvent PF-5070 (from the company 3M) to obtain 1 wt. PFPE coating solution. The solution was shaken until the PFPE was completely dissolved. The resulting coated substrate had an oil class of 8, a Gurley number of about 26 s, a water penetration pressure of about 1.02 bar, and a liquid penetration pressure of about 0.32 bar. The initial air flow of coated oleophobic substrate 2 was 2.15 l / h / cm² (measured at a pressure of 12 mbar).

[0223] The residual air flow was 0.0 l / h / cm² (measured at a pressure of 12 mbar). Therefore, there was no airflow recovery in the airflow recovery test. All measured data are shown in Table 4 below.

Example 8 [0224] The oleophobic substrate 2 was coated with a coating solution of 5 wt. PFPE using the continuous coating process A. The total coating deposition was about 14.5 g / m2².

[0225] The coating solution was obtained by placing 5 g PFPE (Fomblin® Y LVAC 25/6 from Solvay Solexis) in 95 g of perfluorinated solvent PF-5070 (from 3M) to obtain 5 wt. PFPE coating solution. The solution was shaken until the PFPE was completely dissolved. The resulting coated substrate had an oil class of 6, a Gurley number of about 25.4 s, a water penetration pressure of about 1.09 bar, and a liquid penetration pressure of about 0.28 bar. The initial air flow of coated oleophobic substrate 2 was 2.13 l / h / cm² (measured at a pressure of 12 mbar).

[0226] The residual air flow was 1.02 L / h / cm² (measured at a pressure of 12 mbar). Therefore, this example showed in the air flow recovery test both high liquid penetration pressure and air flow recovery about 48% after exposure to the test liquid with low surface tension.

[0227] All measured data are shown in Table 4 below.

Example 9 [0228] The oleophobic substrate 2 was coated with a coating solution of 10 wt. PFPE using the continuous coating process A. The total coating deposition was about 25.8 g / m2².

[0229] The coating solution was obtained by placing 10 g of PFPE (Fomblin® Y LVAC 25/6 from Solvay Solexis) in 90 g of perfluorinated solvent PF-5070 (from 3M) to obtain 10 wt. coating solution. The solution was shaken until the PFPE was completely dissolved. The resulting coated substrate had an oil class of 5, a Gurley number of about 24.4 s, a water penetration pressure of about 1.01 bar, and a liquid penetration pressure of about 0.21 bar. The initial air flow of oleophobic substrate 2 was 2.36 l / h / cm² (measured at a pressure of 12 mbar).

[0230] The residual air flow was 1.20 l / h / cm² (measured at 1.2 mbar). Therefore, this example showed in the air flow recovery test both moderate liquid penetration pressure and 51% air flow recovery after exposure to the test liquid with low surface tension.

[0231] All measured data are shown in Table 4 below.

[0232] Table 4: Summary of measurements in Examples 6 to 9 (Example 6 relates to Substrate 2 that has already been subjected to oleophobic treatment). Examples 7-9 refer to Substrate 2, which was additionally coated with PFPE oil).

<td rowspan="3">Air flow recovery test</td><td>% recovery flow air</td><td>ο</td><td>Ο</td><td>(IN 'Τ</td><td></td>

<td>residual flow air after 5 min (l / h / cm²) at 12 mbar</td><td>ο</td><td>Ο</td><td> 1,02</td><td>&lt;Ν</td>

<td>Initial flow air (L / h / cm²) at 12 mbar</td><td>(Ν</td><td>ΙΖΊ rf</td><td> 2,13</td><td> 2,36</td>

<td rowspan="7"></td><td>Pressure penetration liquid (bar)</td><td> 0,33</td><td> 0,32</td><td> 0,28</td><td> 0,21</td>

<td>Water penetration pressure (bar)</td><td> -</td><td> 1,02</td><td> 1,09</td><td>ο</td>

<td>Air permeability (Gurley) (S)</td><td>κΓ η</td><td> 26</td><td> 25,4</td><td> 24,4</td>

<td>Grade oil</td><td> 00</td><td> 00</td><td>Ο</td><td>ΙΖΊ</td>

<td>Complete deposition of the coating (G / m²)</td><td></td><td></td><td>ΙΖΊ</td><td> 25,8</td>

<td>Composition of the coating solution</td><td>without PFPE</td><td>1% PFPE</td><td>5% PFPE</td><td>10% PFPE</td>

<td>Example</td><td>Ο</td><td></td><td> 00</td><td>ο</td>

[0233] Figure 17 is a graph showing the percentage of surface covered with test liquid versus time using the liquid repellency test in Examples 6, 7, 8 and 9. The described mixture of water, polyvinylpyrrolidone and Tegoprene® was again used as the test liquid

5847 (surface tension 23 mN / m and viscosity 13.7 mPa.s at 25 ° C).

The graph in Figure 17 clearly shows that Examples 8 and 9 having a PFPE coating and the oleophobic substrate ePTFE coating 2 have a much better repellency of the test mixture than Example 6 without an additional PFPE coating.

[0234] Figure 18 is a graph showing both% air flow recovery and liquid entry pressure versus% PFPE in the coating solution for Examples 6, 7, 8 and 9. As a test liquid to measure% air flow recovery, the already described water mixture was reused , polyvinylpyrrolidone and Tegoprene® 5847. The tested liquid for measuring the pressure of liquid penetration was already a mixture of water, 2-propanol and sodium dodecyl sulfate (surface tension: 26.5 mN / m; viscosity: 2.8 mPa.s). The graph in Figure 18 clearly shows that Examples 8 and 9 show much better repellency of the test mixture than Example 6, but still show liquid penetration pressure above 0.2 bar.

[0235] Examples 10 and 11 described below were prepared to demonstrate good liquid repellency using different PFPE oils. In these examples, Krytox® GPL107 (DuPont) and Fomblin® products were tested and compared with each other.

Y LVAC25 / 6 (from Solvay Solexis). In both cases, approximately the same liquid repellency characteristics were achieved.

Example 10:

[0236] Substrate 1 was coated with a coating solution comprising 1 wt. Teflon

AF1600 and 10 wt. PFPE oil (Krytox® GPL107 from DuPont) using the B discontinuous coating process.

[0237] The coating solution was obtained by placing 1 g of Teflon® and 10 g PFPE (Krytox® GPL107 from DuPont) in 89 g of the perfluorinated solvent PF-5070 (from 3M) to obtain a coating solution of 1 wt. Teflon® AF1600 / 10 wt. PFPE. The mixture was stirred for about 6 hours at room temperature until Teflon®

AF1600 was completely dissolved.

Example 11 [0238] Substrate 1 was coated with a coating solution comprising 1 wt. Teflon

AF1600 and 10 wt. PFPE oil (Fomblin® Y LVAC 25/6 from Solvay Solexis) using the B discontinuous coating process.

[0239] The coating solution was obtained by placing 1 g of Teflon® AF1600 and 10 g of PFPE (Fomblin® Y LVAC 25/6 from Solvay Solexis) in 89 g of perfluorinated solvent

PF-5070 (from 3M) to obtain a coating solution of 1 wt. Teflon® AF1600 / 10 wt. PFPE. The mixture was stirred for about 6 hours at room temperature until the Teflon® AF1600 was completely dissolved.

[0240] Figure 19 is a graph showing the percentage of surface covered with test liquid versus time using the liquid repellency test in Examples 10 and 11. The test mixture of water, polyvinylpyrrolidone and Tegoprene® 5847 already used as the test liquid (surface tension 23 mN / m and viscosity 13 , 7 mPa.s at 25 ° C). The graph shows that both types of PFPE oils are approximately similarly effective in improving the liquid repellency of prepared substrates.

[0241] Examples 12 and 13 are examples with a biaxially developed ePTFE membrane (Substrate 3). Also in this case, thanks to the combination of liquid PFPE oil and Teflon® AF polymer, an improvement in air flow recovery was achieved.

Example 12 [0242] Substrate 3 was coated only with the coating solution of 1 wt. Teflon® AF1600 in the continuous coating process A.

[0243] The coating solution was obtained by placing 1 g of Teflon® AF1600 in 99 g of perfluorinated solvent PF-5070 (from 3M company) to obtain a coating solution of 1 wt. Teflon® AF1600. The mixture was stirred for about 6 hours at room temperature until the Teflon® AF1600 was completely dissolved.

[0244] The resulting coated substrate 3 had an oil grade 5. In addition, the coated substrate 12 had an air flow of about 15.6 Gurley seconds, a water entry pressure of about 3.7 bar, and a liquid entry pressure of about 0.69 bar. The initial air flow of coated substrate 3 was 4.85 l / h / cm² (measured at a pressure of 12 mbar).

[0245] The residual air flow was 0.0 l / h / cm² (measured at a pressure of 12 mbar). Therefore, there was no airflow recovery after exposure to the test liquid as described in the airflow recovery test.

[0246] All measured data are shown in Table 5 below.

Example 13 [0247] Substrate 3 was coated with a coating solution comprising 1 wt. Teflon® AF1600 and 10 wt. PFPE oil (Fomblin® Y LVAC 25/6 from Solvay Solexis) using continuous coating process A.

[0248] The coating solution was obtained by placing 1 g Teflon® AF1600 and 10 g PFPE (Fomblin® Y LVAC 25/6 from Solvay Solexis) in 89 g perfluorinated solvent PF-5070 (from 3M) to obtain a 1% coating solution wt. Teflon® AF1600 / 10 wt. PFPE. The mixture was stirred for about 6 hours at room temperature until the Teflon® AF1600 was completely dissolved.

[0249] The resulting coated substrate 3 had an oil grade 4. In addition, coated substrate 3 had an air flow of about 40.6 Gurley seconds, a water penetration pressure of about 2.60 bar, and a liquid penetration pressure of about 0.35 bar. The initial air flow of coated substrate 1 was 3.05 l / h / cm² (measured at a pressure of 12 mbar).

[0250] The residual air flow was 0.25 l / h / cm² (measured at a pressure of 12 mbar). This means 8% air flow recovery after exposure to the test liquid as described in the air flow recovery test.

[0251] All measured data are shown in Table 5 below.

[0252] Table 5: Summary of measurements in Examples 12 and 13 (medium 3 was used to prepare all samples).

Table 5

<td></td><td></td><td></td><td></td><td></td><td></td><td colspan="3">Air flow recovery test</td>

<td>Example</td><td>Composition solution coated.</td><td>Grade oil</td><td>Passing. air (Gurley) (s)</td><td>Pressure penetration water (bar)</td><td>Pressure penetration liquid (bar)</td><td>Pre. flow air (L / h / cm²) at 12 mbar</td><td>Remnant. flow air after 5 min (L / h / cm²) at 12 mbar</td><td>% recovery flow air</td>

<td> 12</td><td>1% AF 1600</td><td> 5</td><td> 15,6</td><td> 3,7</td><td> 0,69</td><td> 4,85</td><td> 0</td><td> 0</td>

<td> 13</td><td>1% AF1600 / 10% PFPE</td><td> 4</td><td> 40,6</td><td> 2,6</td><td> 0,35</td><td> 3,05</td><td> 0,25</td><td> 8,0</td>

[0253] Figure 20 compares the SEM images of Example 12 with Example 13. As already indicated in Example 5 in previous examples. Example 13 also shows that a significant amount of pores are filled or covered by coating ingredients.

[0254] Example 15 below is another example showing both high air flow recovery upon contact with the test liquid and high liquid entry pressure. Example 14 was added for comparison.

Example 14 [0255] Substrate 4 was coated with a 1 wt.% Coating solution. Teflon® AF1600 in the continuous coating process A.

[0256] The coating solution was obtained by placing 1 g of Teflon® AF1600 in 99 g of perfluorinated solvent PF-5070 (from the company 3M) to obtain a coating solution of 1 wt. Teflon® AF1600. The mixture was stirred for about 6 hours at room temperature until the Teflon® AF1600 was completely dissolved.

[0257] The resulting coated substrate 4 exhibited an oil grade 6. In addition, the coated substrate 4 exhibited an air flow of about 13.5 Gurley seconds, a water penetration pressure of about 1.36 bar, and a liquid penetration pressure of about 0.35 bar. The initial air flow of coated substrate 4 was 3.64 l / h / cm² (measured at a pressure of 12 mbar). [0258] The residual air flow was 0.57 L / h / cm² (measured at a pressure of 12 mbar). This means 15.7% air flow recovery after exposure to the test liquid as described in the air flow recovery test.

[0259] Figures 21 and 22 show SEM images of the surface of Example 14, which are coated only with Teflon® AF.

[0260] All measured data are shown in Table 6 below.

Example 15 [0261] Substrate 4 was coated with a coating solution comprising 1 wt. Teflon® AF1600 and 4 wt. PFPE using the continuous coating process A.

[0262] The coating solution was obtained by placing 1 g Teflon® AF1600 and 4 g PFPE (Fomblin® Y LVAC 25/6) in 95 g of perfluorinated solvent PF-5070 (from 3M company) to obtain a coating solution of 1 wt. Teflon® AF1600 / 4 wt. PFPE. The mixture was stirred for about 6 hours at room temperature until the Teflon® AF1600 was completely dissolved.

[0263] The resulting coated substrate 4 exhibited an oil class of 6, a Gurley number of about 13.1 s, a water penetration pressure of about 1.21 bar and a liquid penetration pressure of about 0.25 bar. The initial air flow of coated substrate 1 was 4.95 l / h / cm²(measured at a pressure of 12 mbar).

[0264] This sample showed a residual air flow of about 3.89 L / h / cm² (measured at a pressure of 12 mbar). This corresponds to an air flow recovery of 78.5%.

[0265] For this reason, the sample showed both better air flow recovery with the test liquid, which is demonstrated by the high air flow recovery after exposure in the air flow recovery test and the higher liquid penetration pressure, which is important in practical venting applications.

[0266] Figures 23 and 24 are SEM images of the surface of Example 15 in combination with a Teflon® AF polymer and PFPE oil. Example 15 shows bridging elements between existing nodal regions including coating elements at least partially filling or covering the pores.

[0267] All measured data are shown in Table 6 below.

[0268] Table 6: Summary of measurements in Examples 14 and 15 (medium 4 was used to prepare all samples).

Table 6

<td></td><td></td><td></td><td></td><td></td><td></td><td colspan="3">Air flow recovery test</td>

<td>Example</td><td>Composition solution coated.</td><td>Klas and Oil at</td><td>Let through air (Gurley) (S)</td><td>pRESSURE e penetration water (bar)</td><td>pRESSURE e penetration liquid (bar)</td><td>Pre. flow air and (L / h / cm²) at 12 mbar</td><td>Remnant. flow air and after 5 min (L / h / cm²) at 12 mbar</td><td>% recovery flow at air</td>

<td> 14</td><td>1% AF 1600</td><td> 6</td><td> 13,5</td><td> 1,36</td><td> 0,35</td><td> 3,64</td><td> 0,57</td><td> 15,7</td>

<td> 15</td><td>1% AF1600 / 4% PFPE</td><td> 6</td><td> 13,1</td><td> 1,21</td><td> 0,25</td><td> 4,95</td><td> 3,89</td><td> 78,5</td>