CA2119138A1

CA2119138A1 - Oil, water and sweat repellent microporous membrane materials

Info

Publication number: CA2119138A1
Application number: CA 2119138
Authority: CA
Inventors: James S. Mrozinski; Harold J. Seppala
Original assignee: Individual
Current assignee: 3M Co
Priority date: 1991-10-18
Filing date: 1992-10-16
Publication date: 1993-04-29
Also published as: FI941704A; KR100195808B1; BR9206638A; US5352513A; EP0608366B1; FI941704A0; JPH07500623A; NO300161B1; DK0608366T3; DE69213751D1; NO941391D0; AU666147B2; AU2892092A; DE69213751T2; NO941391L; US5260360A; SG44649A1; ES2091493T3; WO1993008019A1; JP2820795B2

Abstract

The invention discloses an oleophobic, hydrophobic, water repellent, moisture vapor and air permeable, heat sealable, microporous membrane material suitable for garment applications. The membrane material comprises a polyolefin polymer, a processing compound which is miscible with the polymer at its melt temperature but phase separates when the polymer is cooled to or below its melt temperature, and a fluorochemical composition. The membrane material is oriented in at least one direction. The membrane materials retain their repellency and moisture vapor permeable properties for extended periods of time in garment applications which expose the membrane materials to perspiration residues which are known to generally contaminate and ultimately destroy the repellency properties of conventional liquid repellent, moisture vapor permeable treatments.

Description

WO 93/080~9 PCI~US92/08834 211.~ 13 ~ ! ~

OII" WATER AND SWEAT REPELLENT
MICROPOROUS MEMBRANE MATERIALS

S This invention pertains to oleophobic, water repellent, moisture vapor permeable, heat sealable microporous membrane materials.

ACKGROUND of the ~VENTION
Liquid repellent, vapor permeable microporous materials that repel 10 water, oil, and other low surface tension fluids have utility for example, asfabrics for waterprvof garments and tents, as breathable liners for g]oves and clothes, as breathable backin~s for diapers and disposable products, and as protective covers for biological indicators. The ~alue of these materials lies in their ability to repel a wide range of fluids while permitting the rapid transfer 15 of water vapor through the material.
Commercially available fabriGs which have been treated with hydrophobic liquids or polymeric materials such as silicone or fluorocarbon oils or resins to render the fabrics fluid repellent but moisture vapor permeable are well known. While these materials can provide adequate repellency 20 properties along with good moisture vapor transmission properties, their durability is variable as some of the barrier treatments, particularly on microporous substrates, are subject to failure if rubbed, touched, abraded or otherwise contacted or flexed. Additionally, these materials typically do not show long term retention of their repellency properties in garrnent applications25 where they are exposed to perspiration, presumably because the barrier treatments are readily contaminated by perspiration residues.
U.S. Pat. No. 4,194,041 (Gore et al.) is representative of a number of - patents which describe coatings or laminates purported to provide waterproof articles which do not leak when touched and are breathable. This patent 30 describes a layered article for use in waterproof garments or tents comprising at , leastltw~ layers:~ an interior, continuous hydrophilic layer that readily allows water vapor to diffuse therethrough, prevents the transport of surface active agents and contaminating substances such as those found in perspiration, and is ~;
substantially resistant to pressure induced flow of liquid water, and a 35 hydrophobic layer that permits the transmission of water vapor and provides thermal insulating properties even when exposed to rain. The hydrophobic layer is preferably waterproof microporous tetrafluoroethylene (PTFE) or polypropylene, which permits the passage of moisture vapor through the pores ;
.

WO 93/08019 PCr/U5~2/08834 l thereof. The hydrophilic layer transfers moisture vapor therethrough whereupon it passes through the porous hydrophobic layer. Various means of joining the layers are suggested includin~ the application of hydra~lic pressureto force the hydrophilic polymer to penetrate into the surface void spaces of t~e 5 hydrophobic layer.
U.S. Pat. No. 4,443,511 (Worden et al.) discloses a layered watelproof, breath~ble and stretchable article for use in, for example, materialfor protective articles. Also disclosed is a waterproof and breathable elastomeric polytetrafluoroethylene layered article bonded to a stretch fabric.
10 The water proof and breathable elastomeric polytet~fluoroethylene layered article bonde~ to a stretch fabric is described as durable and possessing a moisture vapor transmission rate exceeding 1000 gms/m2 day.
U.S. Pat. No. 4,613,544 (Burleigh) describes a waterproof, moisture vap~r permeable unitary sheet material comprising a microporous polymeric 15 matrix having pores comprising continuous passages extending through its thickness and opening into the opposite surfaces thereof, the passages being sufficiently filled with a moisture vapor perrneable, water impermeable, hydrophilic material to prevent the passage of water and other liquids through the unitary sheet material while readily permitting moisture vapor tr~nsmission 20 therethrough rendering the sheet material breathable. The unitary sheet is m~de by causing a liquid composition comprising the hydrophilic material or precursor thereof to flow into the pores of the matrix, then causing the conversion thereof to solid hydrophilic material.
While these materials alleviate some of the problems known to the art, 25 many require lamination to protect the water repellent, moisture vapor permeable material they use in their constructions while others require void filling which can lower the moisture vapor transmission rate of the material ~nddccrcase its ability to he~ s~l. Joining of mul~iple picces of these materials in a three dimensional garment presents additional problems in tha~ most of these 30 materials are not readily joined together by any means other than sewing which crea;tes needle holes that must be subsequently sealed with seaming tapes or alternative filling techniques to provide a totally waterproof garment. Also, due to the dense nature of the hydrophilic layer, many of these materials are minimally permeable to air.
U.S. Pat. No. 5,025,052 (Crater et al.) describes fluorochemical oxa~olidinone compositions and their use for oil and water` repellency in films,~ fibers, and non-woven webs. i~ orochemica~ oxcl~o/J~//n~n~ ~
co~ oos;t/ons may 1~ ~nc~r~orate~ in the ~/~/ms, ~ers~
rnd novl-wo~en ~e~s by fldd;~'ion ~o fh~ ~o/ym~r m~/t ~i or by top;cal cWlicatio~.

SUB~3TiTUT~ ET
~ .

WO 93/~8019 PC~'U~/08~
211!313~ . 1 U.S. Pat. No. 4,539,256 (Shipman) discloses a rnicroporous sheet material formed by liquid-solid phase separation of a crystallizable thermoplastic polymer with a compound which is miscible with the thermoplastic polymer at the melting temperature of the polymer but phase~
5 separatcs on cooling at or below the cryst~llization temperature of the polymer. < >
U.S. Pat. No. 4,726,989 (Mrozinski) discloses a microporous material similar to that of Shipman but which also incorporates a nucleating agent.
U.S. Pat. No. 4,867,881 (Kinzer) discloses an oriented microporous film formed by liquid-liquid phase 10 separation of a crystalline thermoplastic polymer and a compatible liquid. < >, SummarY oî the In~ention The present invention relates to liquid repellent, moisture vapor and air permeable, microporous membrane materials which comprise an oleophobic, 15 hydrophobic, moisture vapor and air permeable, swea~ contamination resistant,heat sealable, microporous membrare material comprising a crystallizable olefin polymer, a processing compound which is miscible with the olefin polymer at the polymer's melting point but phase separates on cooling to or below the crystallization temperature of the polymer, and a fluorochemical Qil and water 20 repellent compound which is generally solid at room temperature, preferably afluorochemical oxazolidinone compound, said material being oriented in at least one direction.
The microporous membrane materials of the present invention retain their liquid repellency and moisture vapor permeability properties for extended 25 periods even in garment applications which expose the membrane materials to perspiration residues which are known to often contaminate and ultimately destroy repellency propsrties c)f most conventional fluid repellent, moisture vapar permeable materials. Surprisingly, the materials of the invention retain - this contamination resistance to perspiration despite the presence of an 30 oleophilic processing compound. Further, the microporous membrane materials useful in the invention repel mineral oil even when they contain mineral oil.
t The microporous membrane materials of the present invention also possess excellent hand, drape and heat sealability. ~.
:
DETAILED DE~ RIPTION
The liquid repellent, moisture vapor and air permeable, microporous membrane materials of the present invention repel aqueous based liquids including a variety of other liquids such as perspiration which contains oil-based <~ m/cro~rous ~f1~t mafe~i~ is orie~ ed or sfr~fc~ecl>

~- ~ SUB~3Tll UT~ S~EET

WO 93/0801 9 PCI /US9~/08834 ! ~;~
,,:, 211 ~ ~3 ~ - 4 - I -components and prevent penetration of the liquids through the thin (5 to 250 microns) microporous membrane, even when the liquid is propelled against the imembrane material. The microporous membrane materials, while water l -repellent, also have very high moisture vapor permeabilities coupled with 5 significant air permeability properties. 1 ~ -Garrnents comprising the microporous membrane materials of the present invention allow for the transfer of moisture vapor resulting from perspiration through the garment at a rate sufficient to maintain the skin of the wearer in a reasonably dry state under normal use conditions. The 10 microporous membrane materials of the present invention are not subject to contamination by perspiration residues which reduce and ultimately destroy ~he repellency properties of the material. The membrane materials of the present invention can be used in garment applications without a protective overlayer, such as a hydrophilic, e.g., urethane coating.
The microporous membrane materials of the present invention exhibit durability of their fluid repellency properties when subjected to rubbing, touching, folding, flexing or abrasive contacts. The microporous membrane materials of the present invention also display oleophobic properties, resistingpenetration by oils and greases and they are heat sealable. The oleophobicity 20 and heat sealing properties of the membrane materials are most surprising in that the membrane materials contain an oily, oleophilic processing compound which, a priori, one would expect, would promote wet~ing by other oleophilic materials and which also would inhibit heat sealing.
Transport of a liquid challenge through most porous materials or fabrics 25 occurs because the liquid is able to wet the material. A possible route through the material is for the liquid to initially wet the surfaee of the material and to subsequently enter the pore openings at the surface of the material followed by a progressive wetting of and travel through the interconnected pores until finally reaching the opposite surface of the material. If the liquid has difficulty 30 wetting the material, liquid penetration into and through the material will, for the most part, be reduced. A similar phenomena occurs in the pores, where reduced wetability, in turn, reduces pore invasion. Generally the greater the numencal difference between the liquid surface tension of the liquid and the surface energy of the porous material (the latter being lower), the less likely the 35 liquid will wet the porous material.
In the present invention, the addition of a fluorochemical to the ~ ', oleophilic microporous membrane is believed to reduce the surface energy of the membrane despite the presence of the generally oleophilic processing li, wo 93/08019 Pcr/uss2t~g34 :: ~ s 2 1 1 !~ 1 3 ~ ¦
compound. Thereby the numerical difference between the surface energy of the membrane and the surface tension of challenge liquids is increased with the ¦~
overall result that thP microporous membrane containing the fluorochemical is oleophobic despite the presence of the processing compound. ~ I
S The o!eophobic, hydrophobic, moisture vapor permeable, air permeable, heat sealable, micropnrous membrane materials of the presen~
invention comprise a polymeric microporous membrane having a matrix of pores comprising cont~nuous passages extending through the thickness of the membrane and opening into the opposite surfaces of the membrane. ~he 10 polymer used to prepare the mlicroporous membrane contains a fluorochemical oxa~olidinone which migrates to an air interface, thereby lowering the sur~ace energy of the face of the membrane as we~l as the walls of the pores in the membrane, thereby enhancing the hydrophobic properties of th~ microporous membrane as well as rendering the microporous membrane material oleophobic.
The microporous membrane materials of the present in~ention can be tailored to have moisture ~apor permeability rates over a broad range without adversely impacting their water repellencies, but it is preferable to have a moisture vapor transmission rate (MVTR) of at least 700 glm2l24 hrs. and more preferably a MVTPc of at least 100~ glm2124 20 hrs.
The term "water repellent" is used herein to describe microporous membrane materials which are not water wettable and are capable of preventing.
the passage of liquid water through the membrane material by capillary action under varying ambient atmospheric conditions, including water impinging on 25 the surface of the membrane material.
"Moisture vapor perrneable" is used herein to describe microporous membrane materials which readily permit the passage of water vapor through the fabric but which do not allow the passage of liquid water.
The terrn "hydrophobic" is used herein to descnbe microporous 30 membrane materials which are not wet by liquid water or aqueous body fluids such~ as blood, saliva, perspiration and urine, and which are capable of repelling and preventing the passage of liquid water through their structure. `
The term "oleophobic" is used herein to describe microporous ~ -membrane materials which are not wet by oils, greases or body fluids which 35 contain oily components such as perspiration, and are capable of preventing the passage of oils and greases through their structure.

wog3/0801s q~l~lr~3~ -6- PCr/US~/08834 The terrn "heat sealable" is used herein to describe microporous membrane materials which can be sealed together using a hot bar sealer to form a bond having a bond strength of at least 0.1 kg/cm width.
The presen~ invention will be described utilizing the fluorochemical S oxazolidinone but it will be recognized by those skilled in the art that other generally solid fluorochemicals can be used.
The oleophobic, hydrophobic, moisture permeable, air permeable, heat sealable, microporous membrane materials of the present invention can preferably be made by the following steps: (a) melt blending into a 10 homogeneous blend, a mixture comprising about 40 to about 80 parts by weight of a crystallizable olefin polymer, about 20 to 60 parts by weight of a processing compound which will dissolve the polymer at the polymer's melting temperature but which will also phase separate from the polymer on cooling to a temperature at or below the crys~,allization temperature of the polymer, and 15 0.3 to 7 parts by weight of the fluorochemical oxazolidinone; (b) forming a film from the melt blended mixture; (c) cooling the film to a temperature at which phase separation occurs between the compound and the polymer, thereby creating a phase separated film comprising an aggregate of a first phase comprising particles of crystalline olefin polymer in a second phase comprising 20 the processing compound and the fluorochemical oxazolidinone, with adjacent olefin polymer particles being distinct but having a plurality of zones of continuity; and (d) stretching the phase separated film in at least one direc~ion to separate adjacent particles of olefin polymer from one another to provide a network of inter-connected micropores and to permanently attenuate the olefin 25 polymer in the zones Qf continuity to form fibrils. Op,tionally a nucleating agent may also be added in step (a). Such methods are described, for example, in U.S. Pat. No. 4,539,256 (Shipman), U.S. Pat. No. 4,726,989 (Mrozinski) and U.S. Pat. No. 4,863,792 (Mrozinski).
Alternatively, as a subsequent dimension of this invention, if a large 30 weight percent of a generally solid fluorochemical composition, preferably a fluorochemical oxazolidinone can be tolerated (i.e. >5% by weight), it is 'ipossible to topically apply a fluorochemical composition to the microporous membrane material through spray application or dip coating techniques.
Examples of membranes which contain the phase separating processing 35 compound that can be topically treated include crystalline polyolefin membranes described, for example, in U.S. Pat. No. 4,539,256 (Shipman), U.S. Pat. No.

4,726,989 (Mrozinski), U.S. Pat. No. 4,863,792 (Mrozinski) and U.S. Pat.
No. 4,824,718 (Hwang). Further, these fluorochemical compositions can be wo 93/0X01~ Pcrluss2to8834 i~
7 2119~3~ - ~^
topically applied to o~her microporous materials such as stretched polytetrafluoroethylene or particle loaded films which do not contain the processing compound.
The phase sepa~ated films typically are solid and generally transpare~t 5 before stretching and comprise an aggregate of a first phase of particles of olefin polymer in a second phase of the processing compound and the fluorochemical oxazolidinone. The particles may be described as spherulites and aggregates of spherulites of the olefin polymer, with processing compound and the fluorochemical oxazolidinone occupying the space between particles.
10 Adjacent particles of polymer are distinct, but they have a plurality of zones of continuity. That is, the polymer particles are generally substantially, but not totally, su~Tounded or coated by the processing compound and the fluorochemical oxazolidinone. There are areas of contact between adjacent polymer particles where there is a continuum of polymer from one particle to 15 the next adjacent particle in such zones of continuity.
On stretching, the polymer particles are pulled apart, permanently attenuating the polymer in zones of continuity, thereby forming the fibrils and creating minute voids between coated particles which results in a network of interconnected micropores. Such permanent attenuation also renders the article 20 permanently translucent. On stretching, the processing compound and the fluorochemical oxa~olidinone remain coated on or substantially surrounding the surfaces of the resultant fibriltparticle matrix. The degree of coating depends on several factors, including, but not limited to, the affinity of the compound and the fluorochemical oxazolidinone for the surface of the polymer particle, 25 whether the compound is liquid or solid, and whether stretching dislodges or disrupts the coating. After the stretching operation, substantially all of the particles appear to be connected by fibrils and are usually at least partially coated. The size of the micropores is easily controlled by varying the degree ofstretching, the amount of processing compound employed, melt-quench 30 conditions, and heat stabilization procedures. For the most part, the fibrils do not appear to be broken by stretching, but they are permanently stretched beyond their elastic limit so that they do not elastically recover to their original position when the stretching force is released. As used herein, "stretching"
means such stretching beyond the elastic limit so as to introduce permanent set 35 or elongation to the microporous membrane material.
Preferably, the melting and crystallization temperature of an olefin polymer, in the presence of a processing compound, is influenced by both an e~uilibrium and a dynamic effect. At equilibrium between liquid and crystalline Wo 93/08019 PCr/VS92/0~834 ~' 7~ - 8-polymer, thermodynamics re4uire that the chemical potentials of the polymerrepeating unit in the two phases be equal. The temperature at which this condition is satisfied is referred to as the melting tem~erature, which depends upon the composition of the liquid phase. The presence of a diluent, e.g., the processing compound, in the liquid phase will lower the chemical potential of ¦ -the polymer in that phase. Therefore, a lower melting temperature is required to re-establish the condition of equilibrium, resulting in what is known as a melting temperature depression.
The crystallization temperature and melting temperature are equivalent 10 at equilibrium. However, at non-eguilibrium conditions, which are normally the case, the crystallization temperature and melting temperature are dependent on the c~oling rate and heating rate, respectively. Consequently, the terms "melting temperature" and "crystallization temperature," when used herein, are intended to include the e~uilibrium effect of the processing compound as 15 well as the dynamic effect of the rate of heating and cooling.
The microporous membrane materials of the present invention have a microporous structure chasacterized by a multiplicity of spaced, i.e., separatedfrom one another, randomly dis~ersed, non-uniform shaped, equiaxed particles of olefin polymer connected by fibrils which are intimately surrounded by the 20 processing compound and the fluorochemical oxazolidinone. "Equiaxed" means having approximately equal dimensions in all directions.
While the preferred form of the microporous membrane materials of the present invention is a sheet or film form, other article shapes are contemplatedand may be formed. For example, the article may be in the form of a tube or 25 filament or hollow fiber. Other shapes which can be made according to the disclosed process are also intended to be within the scope of the invention.
Nucleating agents as described in U.S. Pat. No. 4,726,989 (Mrozinski) may also be used in the preparation of the microporous membrane materials of the present invention. The use of nucleating agents provides various advantages 30 including lower polymer content and thus higher porosity of the finished article, reduced polymer particle size resulting in more particles and fibrils per unit volume, greater stretchability resulting in longer fibril length, and greatly increased tensile strength of the material. ', Crystallizable olefin polymers suitable for use in the preparation of 35 microporous membrane materials of the present invention are melt processable under conventional processing conditions. That is, on heating, they will easily soften and/or melt to permit processing in conventional equipment, such as an extruder, to form a sheet, film, tube, filament or hollow fiber. Upon cooling A,.. ,.,; i . ~ . ~

wo ~3/08019 PC~/US9~/08834 9 211~13~
the melt under controlled conditions, suitable polymers spontaneously form geometrically regular and ordered crystalline structures. Preferred crystallizable olefin polymers for use in the present invention have a high ¦
degree of crystallinity and also possess a tensile s~ength of at least about 70 S kg/cm2 (lOOOpsi). ~: :
Examples of commercially available suitable polyolefins include polypropylene, block copolymers or copolymers of ethylene and propylene, or other copolymers, such as polyethylene~ polypropylene and polybutylene copolymers which can be used singularly or in a mixture.
Materials suitable as processing compounds for blending with the crvstallizable polymer to mal~e the microporous membrane materials of the present invention are liquids or solids which are not solvents for the crystallizable polymer at room temperature. However, at the melt temperature of the crystallizable polymer the compounds become good solvents for the 15 polymer and dissolve it to forrn a homogene~us solution. The homogeneous solution is extruded through, for example, a film die, and on cooling to or below the crystallization temperature of the crystallizable polymer, the solution phase separatès to form a phase separated film. Preferably, these compounds have a boiling point at atmospheric pressure at least as high as the melting 20 temperature of the polymer. However, compounds having lower boiling points may be used in those instances where superatmospheric pressure may be `
employed to elevate the boiling point of the compound to a temperature at least as high as the melting temperature of the polymer. Generally, suitable compounds have a solubility parameter and a hydrogen bonding parameter 25 within a few units of the values of these same parameters for the polymer.
Some examples of blends of olefin polymers and processing compounds which are useful in preparing microporous ma~erials in accordance with the present invention include: polypropylene with mineral oil, dioctylphthalate, or mineral spirits; and polyethlyene-polypropylene copolymers with mineral oil or 30 mineral spirits. Typical blending ratios are 40 to 80 weight percent polymer and 20 to 60 weight percent blending compound.
A particular combination of polymer and processing compound may include more than one polymer, i.e., a mixture of two or more polymers, e.g., polypropylene and polybutylene, and/or more than one blending compound.
35 Mineral oil and mineral spirits are examples of mixtures of processing compounds, since they are typically blends of hydrocarbon liquids. Similarly, blends of liquids and solids may also serve as the processing compound.

~O 93/08~19 P~/USg2/08834 lo - 21.~ 913 8 ! i Fluorochemical oxazolidinones suitable for use in the present invention are norrnally solid, wa~er-insoluble, fluoroalipha~ic radical-containing 2-oxazolidinone compounds which have one or more 2-oxazolidinone moieties, at least one of which has a monovalen~ fluoroaliphatic radical containing at least3S ~ully fluorinated terrninal carbon atoms bonded to Lhe 5-posiLion carbon atom thereof by an organic linking group, preferably o /(~\
O N--C8F17S02N(C~3)CH2(~ ~H2 are described in IJ.S. Pat No~ 5,025,052 (Crater et al.3. These oxazolidinone compounds are norrnally blended in the polymer/processing compound mixture in the ratio of 1 to 5 weight percent. More preferably the fluorochemical 20 oxazolidinone compounds are added to the polymer/ processing compound mixture in the ratio of 1 to 2 weight percent. ~luorochemical ox~olidinone compounds can be added to the membranes of the present invention in amounts greater than 5 weight percent (i.e. 10 weight percent), but additions in excess of about 2 weight percent typically do not show any performance advantages. It 25 is also expected that additional oil and water repellent fluorochemical compositions would provide comparable properties when added during extrusion at the proper extrusion conditions.
Optionally, these compounds, as well as commonly available well-known oil and water re~ellent fluorochemical compositions, can be topically 30 applied to a microporous membrane material. Typically, topical application ofa fluorochemical compssition requires a higher weight percent add-on, typically 4 to 1~ percent, to achieve comparable water and oil repellency proper~ies as achieved when the fluorochemical oxa~olidinone is incorporated in the polymer melt.l Additionally, post membrane formation application of the fluorochemica 35 composi~ion requires that the composition be dissolved in a solvent and that ~he solvent subsequently be removed from the membrane mate~ial. The solvent should not be a solvent for the polymer or the processing compound. t,.-Certain conventional additive materials, may also be blended in limited quantities with the olefin polymer. Additive levels should be chosen so as not 40 to interfere with the formation of the microporous membrane material or to `
result in unwanted exuding of the additive. Such additives may include, for SUE~3TlTlJT~

. yo93/û8ols rcr/uss /Og834 r 13 ~3 ! 1`
exarnple, dyes, pigmcnts, plasticizers, UV absorbers, antioxidants, bacteriocides, fungicides, ionizing radiation resistant addiLives, and the like.Additive levels should typically be less than about 10% of the weight of the polymer compcnent, and preferably be less than about 2% by weight.
S In the following non-limiting examples, all parts and percentages are by weight unless otherwise indicated. In eYaluating the materials of the invention and the compara~ive materials, the following test methods are used.
~J
orosity Porosity is measured according to ASTM-D-726-58 Method A and is 3 reported in Gurley ~econds/~cc.

~' Bubble Point Bubble point values represent the largest effectiYe pore size rne~sured in microns according to ASTM-F-316-80 and is reported in mierons.

Moisture Vapor Transmission Rate fMVTR!
O Moisture vapor trans<ission rates ~MVTR) were made using ASTM E-~/ G> 96-80 Upright Water Method a~70F¦ 50~ relative hurnidity and are reported 20 in glm2l24hr.

Water Repellency Test ~
The aqueous stain or water repellency of the materials of the invention is measured using a water/isopropyl alcohol test, and the result is expressed in25 terms of a water repellency rating of the material. Materials which are penet~ted by or resistant only to a 100 percent water/zero percent isopropyl alcohol mixture (the least penetrating of the test mixtures~ are given a rating of O, wher~s trc~led ~brics resist~n~ to zcro percent water/100 percent isopropyl alcohol mixture (the most penetrating of the test mixtures) are given a rating of .i 30 10. Other intermediate values ~re determined by use of other water/isopropyl .ji alcohol mixtures, in which the percentage amounts of water and isopropyl alcohol are each multiples of 10. Results are reported as ~n avera~e of replicate ~ testing. The water repellency rating corresponds to the most penetrating -~, mixture which does not penetrate or wet the fabric after 30 seconds contact.
~, Oil Repellencv Test (QR) The oil repellency of materials of the invention is measured by the American Association of Textile Chemists and Colorists (AATCC) Standard :,f .; .
S~ TlTUT~r~

WO 93/08019 PCI`/US92/08834 Test Method No. 118-1983, which test is based on the resistance of treated fabric to penetration by oils of varying surface tensions. Treated fabrics resistant only to NujolTM, a brand of mineral oil and the least penetrating of the test oils, are given a rating of 1, whereas treated fabrics resishnt to hepta~e S (the most penetrating of the test oils) are given a value of 8. C)ther intermediate values are detennined by use of other pure oils or mixtures of oils, as shown inthe following table:

_ Standard Test Liquids AATCC OIL
Repellency - Rating Number Composition NujolTM
2 65: 35 NujolTM: hexadecane by volume 3 n-hexadecane 4 n-tetradecane n-dodecane 6 n-decane 7 n-octane 8 n-heptane _ The rated oil repellency corresponds to the most penetrating oil (or mixture of oils) which does not penetrate or wet the fabric after 30 seconds 25 contact. Higher numbers indicate better oil repellency.

~- Sweat Contamination Resistance Resistance to sweat contamination was measured according to MIL-C-~; 44187B, March 31, 1988, test method 4.5.7 and is reported as being resistant 30 or not resistant.

Heat Seal Bond Strength - Heat seal bond strength was measured by heat sealing two pieces of membrane together on a Sentinal Model 12AS hot bar sealer (Packaging - 35 Industries, Inc., Hyannis, MA) at a temperature of 143C (290F) for 0.75 seconds at 310 kPa (45 psi) pressure and determining the strength of the bond - according to ASTM D751-79 Method A (reported in kilograms per centimeter width).

, .

9 PCr/US9~/()8834 - 13 - 2 1 1 9 ~ 3 ~3 EXAMPI,ES
OXAZOI,IDINONl~ PREPARATIO~
The fluorochemical oxazolidinone (FCO) used in the following examples was similar to those described in U.S. Pat. No. 5,025,052 (Crater ~t 5 al.) Example 1, except that the alcohol and isocyanate reactants used to prepare o the oxa~olidinone were C8F17SO2N(CH3)CH2(:H(CH2Cl)OH a~d OCNC18H37, respectively.

EXAMPLE_1 -A 0.05 mm thick sheet of microporous membrane material was prepared using a thermally induced phase separation technique comprising about 65 parts polypropylene (PP) having a melt flow index of 0.8 dg/rnin ASTM
1238 (available from Himont Incorporated, Wilmington, Delaware under the trade designation PRO-FAX 6723) and about 35 parts mineral oil (MO), 15 (available from AMOCO Oil Company under the trade designation AMQCO
White Mineral Oil ~31 USP Grade). About 1.3 parts fluorocarbon oxazolidinone (FCO) compound and about 0.0S parts Millad 3905 (available - from Milliken Chemical under the trade designation Millad 3905) were added to the PP:MO blend. The PP/MO/FCO/MILLAD composition was melt 20 extruded on a twin screw extruder operated at a decreasing temperature profile of 260 to 193C through a slip gap sheeting die having an orifice of 30.5 x 0.05 cm and qùenched in a water bath maintained at 54C. The phase separated film was continuously oriented or stretched in the machine direction (length) to a 1.25:1 stretch ratio at 50C and followed by a continuous 25 orientation or stretch in the cross machine direction (width) in a tenter oven to a 2.25:1 stretch ratio at 83C and then heat annealed at 121C. Membrane characterization data are reported in Table I.
:
COMPARATIVE EXAMPLE Cl A 0.04 mm thick sheet of microporous membrane material was ~, prep,ared by using the same process and polypropylene/mineral oil/nucleating agent materials as Example 1, but with no FCO compound to provide a comparative membrane material. Membrane characterization data is reported in Table I.

A 0.036 mm thick sheet of microporous membrane material was prepared from the same PP/MO materials used in Example 1, but at a 68:32 wo 93~080l9 P~r/uss~/08834 (PP:MO) weight ratio to which about û.05 parts Millad 390~ and 0.7 parts FCO were added. The PP/MO/FCO/Millad composition was melt extruded as Example 1 but it was quenched in a water bath at 60C and biaxially oriented 1,25 x 1.75 (MD x TD). Membrane characterization data is reported in Table ', 5 I, A 0.08 mm thick sheet of microporous membrane material was prepared from the same PP and mineral oil used in Example l, but at a 55:45 10 PP:MO weight ratio, About 5.5 parts FCO were added to the mixture. The PP/MO/FCO was melt extruded as Example 1, but was biaxially stretched 1,25 x 1,75 (MD x TD), Membrane charactenzation data is reported in Table I.

15 EXAMPLE 4 ~ -;
A 0.09 mm thick sheet of microporous membrane material was prepared from about 54 parts polypropylene/polyethylene copolymer having a melt flow index of 0.4 dg/min ASTM 1238 (available from Himont Incorporated, Wilmington, DE under the trade designation PRO-FAX 7823~ and 20 about 46 parts mineral oil to which about 1.1 parts FCO was added. The PP-PE copolymer/MO/FCO was melt extruded at process conditions similar to Example 1 except at a throughput rate of l l .35 Kg/hour and a stretch ratio of 1.25 x 1.75 (MD x TD). Membrane characterization data is reported in Table I.

A 0.07 mm thick sheet of microporous membrane material was prepared from the same polypropylene and mineral oil used in Example 1, but at a 40:60 weight ratio to which about 0.8 parts FCO were added. The 30 PP/MOIFCO was melt extruded at conditions similar to Example 1 except it was quenched in a, water bath maintained at 47C and biaxially stretched 1.25 by 1.75. Membrane characteri~ation data is reported in Table I.

EXAMPLE 6 'I
A 0.05 thick sheet of microporous membrane material was prepared from the same PP/MO materials used in Example 1, but at an 75:25 PP:MO
weight ratio to which about 1.9 parts FCO were added. The PPIMO/FCO ,composition was melt extruded on a 25 mm twin screw extruder operated at a wo 93~08019 PCr/lJS92~08834 i~
2 1 1 9 1 3 8 ~ ! ~
- 15 - i de~reasing temperature profile of Z60 to 230C through a 7.62 cm circular blown film die. The blown film was length stretched 1.3:1 at 70C.
Membrane characterization data is reported in Table I.

5 COMPARATTVE EXAMPLE C2 ~`
A sheet of microporous membrane ma~erial was prepared by USil'.g the same process and polypropylene/mineral oil/nucleating agent materials as Example 2, but with no oxazolidinone compound to provide a comparative membrane material. Membrane characterization data is reported in Table I.

A sheet of microporous membrane m.aterial was prepared by using the same process and polypropylene/mineral oil/nucleating agent materials as Example 2, except that 1.1 parts FCO was added to the 15 mixture. Membrane characterization da~ is reported in Table I.

TABLE I
EXTRUSION INCORPORATION
MEMBRANE CHARACTERIZ;ATION DATA
. _ Ex. PorosityPore MVTR Water Oil Resis- Heat No. (GurlevSize (glm21 Repel- Repel- tance toSeal ~ec) (,um) 24hr) lency lency Sweat Bond Contami-(kg/
nation cm) . _ _ 370 0.130 987 2 Yes 0.77 C 1 226 0.192 931 2 0 No 0.93 . _ 2 62 0.380 1027 8 1 Yes 0.72 II . I ., 3 96 0.270 1030 9 2 Yes 0.79 I ~
4 205 - 0.380 904 2 Yes - 0.68 1 !
.. l I
110 0.430 793 9 1 Yes 0.29 I ~
. I ~., 6 515 0.460 435 6 2 Yes 0.45 C2 192 986 2 1 No 0.61 _ t.
7 98 1072 9 2 Yes 0.59 _ _ _ . _ ~YO 93/080l9 PCl`tUS92/08834 21191~?8 A 0.05 mm thick sheet of microporous membrane material wasprep~red using a blend of 5~ parts polypropylene (available from Himont Incorporated, Wilmington, Delaware under the trade designation P~O-FAX
6723), 15 parts poly(ethylenetbutylene) copolymer (available from Shell ,~
Chemical under the designation DP 8510), 25.5 parts of a red pigrnented polypropylene (available from Spectrum, formerly C.B. Edwards, under the designation CBE 34227 P Red), 1.5 p~rts FCO which was melt blended with 35 parts mineral oil on a 25 mm twin screw extruder operating under condi~ions 10 similar to those described in Example 6~ The polymer/pigment/FCOlMO blend was extruded through a 7.62 cm circular blown film die and was subsequently length oriented 2:1 at 60C. The porosity was 170 Gurley sec and the pore size was 0.30 ,um.

A 0.04 mm thick sheet of air permeable, perspiration repellent microporous membrane material was prepared using the same materials and process as Example 1, except a blue PP pigment (available from PMS
Consolidated, Somerset, New Jersey under the trade designation BLUE P~93C) 20 was added to color the existing material. The blend ratio of materials was 63.7/1.3/2.0/33.0, PP/FCO/BLUEIMO. The process differences included casting the molten blend maintained at 205C from a slip gap sheeting die with a 38.1 x 0.05 cm orifice onto a smooth steel casting wheel maintained at 66C.
The membrane was then continuously length direction stretched at a ratio of 1.75:1 and continuously width direction stretched 2:1 at 93C and heat annealed at 130C. The porosity was 200 Gurley sec., ~he pore size 0.28 ~m, 3~ > the MVTR 6954 glm21~4 hr a~(100F)and 20% relative humidity and the membrane was resistant to sweat contamination.
Fluorochemical oxa~olidinone compounds can also be topically applied 30 to microporous membrane materials to produce hydrophobic, oleophobic, sweat contamination resistant materials. Generally speaking, a significantly higher add-on of fluorochemical oxazolidinone compound was required to produce repellencies (both oil and water) and resistance to sweat contamination comparable to that obtained with extrusion incorporation of the oxa~olidinone.

A sheet of microporous membrane material was prepared by using the same process and polypropylene/ mineral oillnucleating agent materials as , . - . . ..
~ ~SUE~T~TUT SPIEE~

wo 93/08~19 Pcr/uS92/08834 - l 7 ~
Comparative Example C2 and the FCO was applied to the membrane material by dipping the membrar.e into a 5% solids (w/w) solution of the FCO in isopropyl alcohol (IPA), which was maintained at 66C, for 3 seconds. The microporous membrane material was then placed into a circulating air oven 5 maintained at 100C to evaporate the solvent, leaving the oxa~olidinone intimately surrounding the membrane interstices. The FC0 add-on was approximately 7% by wei~ght. The membrane was resistar~ ~o sweat contamination.

lO EXAMPLE ll A sheet of microporous membrane material of Comparative ~xample 1 was dipped into a 5% solids (w/w) solution of FCO in IPA, which was maintained at 66C, for 3 seconds and dried as in Example lO. The FCO add on was approximately 7.0% by weight. The membrane was resistant to sweat 15 contamination.
Exarnple 12 A sheet of microporous membrane material of Comparative Example i was dipped in a 4% solids (w/w) solution of FCO in IPA which was maintained 20 at 70C for 3 seeonds an~ dried in a circulating air oven at 80C for two minutes. The treated material was tested for oil repellency. The oil repellency value was 2.

Example 13 -A sheet of microporous membrane matenal of Comparative Example 1 was dipped in a 4% solids solution of fluorochemical polymer in a 50/S0 water/IPA mixture. The fluorochemical was prepared as in Example l of U.S.
Pat. No. 4,579,924 exeept that 75.5 parts C8F17S02N(CH3)C2H40CO~H=CH2, 17.3 parts 30 C2HsOc2H4OcocH=cH2~
O ................... ' ', . .
2.5 parts CH2-CHCH20COC(C~I3~=CH2 and.4~.5~parts CH2=C(CH3)COOC2H4N+(C~I3)3Cl- were polymerized. The membrane material was dried at 80C for two minutes. The treated material was tested 35 for oil repellency. The oil repellency value was 2.

Wo 93/08019 Pcr/uss2/o8834 Example 14 A sheet of microporous membrane material of Comparative Example 1 was dipped in a 4% solids solution of a fluorochemical composition in a 50/50 water/IPA mixture maintained at room temperature for 3 seconds. The ~ `
fluorochemical was prepared as in U.S. Pat. No. 3,094,547 (Heine) using 29 , -par$s ~CBFl7so2N(c~2~H3)c2H4o]2pooNH4~ 5 parts C8Fl7so2N(cH2cH3)c2H4opo~oNH4)2 and 0-7 parts ~C8F17SO2N(CH2CH3)C2H4O~3PO, the latter two materials being by-product materials. The membrane material was dried at 80C for two minutes. The 10 treated material was tested for oil repellency. The oil repellency value was 2.

Example 15 A sheet of microporous membrane material of Comparative Example 1 was dipped in a 4% solids solution of fluorochemical polymer in IPA. The 15 fluorochemical was prepared as in U.S. Pat. No. 3,341,497 (Sherman et al.), Examples VI to VIII~ except the components were 50 parts octadecyl methacrylate and 50 parts N-ethyl perfluorooctanesulfon-amidoethyl methacrylate. The membrane material was dried at 80C for two minutes.
The treated material was tested for oil repellency. The oil repellency value was20 2.

xample 16 A sheet of microporous membrane material of Comparative Example 1 - was dipped in a 4% solids solution of fluorochemical polymer in a ~5/5 ethyl 25 acetate/heptane mixture maintained at room temperature for 3 seconds. The fluorochemical was prepared as in U.S. Pat. No. 3,341,497 (Sherman et al.) Examples VI to VIII, except the components were 35 parts octadecyl methacrylate and 65 parts N-ethyl perfluorooctanesulfonamidoethyl methacr,vlate. The membrane material was dried at 80C for two minutes.
30 The treated material was tested for oil repellency. The oil repellency value was 3 .

~ .
Exam~le 17 A 0.03 mm thick sheet of microporous membrane material was prepared for lamination to a polypropylene spunbonded nonwoven using the ` '~
same materials as Example 9, except a polybutylene (PB) copolymer (available 0 93/08019 PCI'/US92/08834 - ~ ;` 19 2 1 ' t, from Shell Chemical Company under the trade designation PP ~510) was added to make a blcnd ratio of 61.8tl.3/2.0/5.0/30, PP/FCO/BLUE/PB/MO.
This composi~ion was rnelt extruded through a circular blown film die having a diameter of 30.5 cm and an orifice of 0.05 cm to form ~2 mil)film :~ 5 with a lay flat width of 91 cm. The membrane was continuously length stretched to a 1.6:1 stretch ratio at 3~C and heat annealed at 119C. The ~28,3~g> membrane was then thermally bonded to ~(1.0 ounce)polypropylene spunbond nonwoven (trademark "Celestra", supplied by Fiberweb). The laminating ~,~ process included running the membrane and nonwoven between a smooth roll 10 and a heated point-bonding roll (approximately 15 percent poin~ contact). Theheat roll was set at 270 F. The pressure applied to the materials was ~, 3~JS~/dm ~SO pounds per lineal inch), Membrane data is set forth in Table !.~ II.

15 Example 18 The membrane of Example 17 was also adhesively bonded to a similar 1.0 ounce PP spunbonded nonwoven. The adhesive used was a polybutylene resin made by Shell, identif~ed as DP9891D Duraflex, spray applied in a ~ random pattern. The adhesive weight applied was approximately 2 gtm2.
r,~ 20 Membrane data is set forth in Table II.

~, TABLE Il ~ .
: Ex.CALIPER% FCO POROSlTY BUBBLEMVT~
: No.(mm) (sec/ socc) POINl' (~Im2t24hr at 100F, ~m) 20 %rh) . _ ~ 25 17 0.03 1.3 221 0.40 ,,~", _ ,'~4~ 18 0.03 1.3 295 û.32 ~151 ~ l _ _ The various modifications and alterations of this invention will be 30 apparent to those skilled in the art without departing from the scope and spirit of this invention and this invention should not be restricted to that set forth herein for illustrative pu~oses.

~UB~TlTUT~ S~IEET
....... ....

Claims

Claims:

1. A microporous membrane material which comprises a crystallizable olefin polymer and an oleophilic processing compound which is miscible with the olefin polymer at the polymer's melting point but phase separates on cooling to or below the olefin crystallization temperature of the polymer, said material being oriented by stretching in at least one direction, said material being characterized by the blending ratio of polyolefin to processing compound being in the range ofabout 40:60 to 80:20 and said membrane material further containing a fluorochemical oxazolidinone compound which is generally solid at room temperature.

2. The material of claim 1 wherein said olefin polymer is polypropylene, block copolymers or copolymers of ethylene and propylene, or other copolymers such as polyethylene, polypropylene and polybutylene copolymers which can be sued singularly or in a mixture.

3. The material of claim 1 wherein said processing compound is a hydrocarbon liquid.

4. The material of claim 1 wherein said processing compound is mineral oil or a mixture of mineral oil and mineral spirits.

5. The material of claim 1 wherein said fluorochemical oxazolidinone is a normally solid, water-insoluble, fluoroaliphatic radical-containing 2-oxazolidinone compound which has one or more 2-oxazolidinone moieties, at least one of which has a monovalent fluoroaliphatic radical containing at least 3 fully fluorinated terminal carbon atoms bonded to the 5-position carbon atom thereof by an organic linking group.

6. The material of claim 1 wherein the fluorochemical oxazolidinone is blended with the polyolefin and processing compound at extrusion and comprises about 0.3 to 7 weight percent of the material.

7. The material of claim 1 wherein the fluorochemical oxazolidinone is blended with the polyolefin and processing compound at extrusion and comprises about 1 to 2 weight percent of the material.

8. The material of claim 5 wherein said fluorochemical oxazolidinone can be represented by the formula:

9. The material of claim 1 wherein the fluorochemical oxazolidinone is topically applied to liquid repellent, moisture vapor permeable, microporous membrane material at a rate of at least 5 percent by weight based on the weight of the material.

10. The material of claim 1 wherein said moisture vapor transmission rate is at least 700 g/m2/24 hours.

11. The material of claim 1 wherein said material can be heat sealed to form a bond strength of at least 0.1 kg/cm width.

12. A layered structure of claim 12 wherein the microporous material of claim 1 and at least one other porous material which does not substantially affect theporosity of the microporous material.

13. The layered structure of claim 12 wherein the microporous material and said at least one other porous material are laminated.

14. A liquid repellent, moisture vapor permeable microporous membrane material which comprises an oleophobic, hydrophobic, moisture vapor and air permeable, heat sealable, microporous membrane material comprising a crystallizable olefin polymer, a process compound which is miscible with the olefin polymer at the polymer's melting temperature but phase separates on cooling to or below the olefin crystallization temperature of the polymer, and a topically applied oil and water repellent fluorochemical composition, said membrane being oriented in at least one direction.