MXPA97006751A - A laminated barrier material not tej - Google Patents

Abstract

The present invention relates to a non-woven fabric comprising: at least one layer formed of fibers, wherein the fibers are subjected to corona discharge include an alcohol repellent formed from a urethane derivative fllurinata

Description

A NON-WOVEN LAMINATED BARRIER MATERIAL FIELD OF THE INVENTION The present invention relates to protective garments. More particularly, the present invention relates to protective garments formed of non-woven fabrics having improved particular barrier properties.

BACKGROUND OF THE INVENTION There are many types of disposable or limited-use protective garments designed to provide barrier properties. Protective clothing must be resistant to penetration by both liquids and / or particles. For a variety of reasons, it is undesirable that liquids and pathogens which can be carried by liquids pass through the garment to make contact with people working in an environment where pathogens are present.

Similarly, it is highly desirable to isolate people from harmful substances, which may be present at an accident site or in a workplace. To increase the likelihood that the protective garment will be worn correctly thereby reducing the opportunity for exposure, workers will benefit from wearing a protective garment that is relatively impervious to liquids and / or particles and that is durable but which is still comfortable as not to reduce the performance of workers. After use, it is usually very costly to decontaminate a protective garment that has been exposed to a dangerous or harmful substance. Therefore, it is important that a protective garment be cost effective to be disposable.

One type of protective garment is monkeys or disposable protective gowns. Monkeys or gowns can be used to effectively isolate a wearer from a harmful environment in ways in which open protective or layer-style garments, such as cloths, gowns and the like are unable to do so. Therefore, monkeys can have many applications where the isolation of a user is desirable.

Disposable protective garments also include disposable surgical garments such as scrubs and disposable surgical drapes. As is generally known, surgical gowns and drapes are designed to greatly reduce, if not prevent, the transmission of biological fluids and contaminants through the surgical garment which can be worn there. In environments of surgical procedures, such sources of fluids include perspiration of the wearer of the gown, the patient's fluids such as blood, saliva, sweat and life supporting fluids such as plasma and salt water .

Many surgical garments were originally made of cotton or linen and were sterilized before use in the operating room. These surgical garments, however, allowed the transmission through them or the "transfer" of many liquids found in surgical procedures. These surgical garments were undesirable, if not unsatisfactory, because the "transfer" established a direct path for the transmission of bacteria from other contaminants to and from the user of the surgical garment. In addition, the garments were expensive, and therefore, the washing and sterilization procedures were required before using them again.

Disposable surgical garments have largely replaced linen surgery gowns. Because many surgical procedures require a high degree of liquid repellency to prevent transfer, the disposable surgical garments for use under these conditions are, to a large extent, made entirely of liquid repellent fabrics.

Therefore, generally speaking, it is desirable that disposable protective garments can be made of some fabrics that are relatively impervious to liquids and / or particulates. These barrier type fabrics must also be suitable for the manufacture of protective clothing at a low cost so that such garments can be disposed of after a single and inexpensive use.

Examples of disposable protective garments, which are generally manufactured from non-woven laminated fabrics to ensure that they are effectively disposable and inexpensive are the coveralls or overalls, surgical gowns and surgical drapes sold by Kimberly-Clark Corporation. . Many of the disposable protective garments sold by Kimberly-Clark Corporation are manufactured from a non-woven three-ply laminate. The two outer layers are formed of spunbonded polypropylene fibers and the inner layer is formed of polypropylene meltblown fibers. The outer layers of spin-bonded material provide abrasion resistant, durable, and strong surfaces. The inner layer is not only water repellent but acts as a breathable filter barrier allowing air and water vapor to pass through the mass of the fabric while filtering out many harmful particles.

In some cases, the material forming the protective garments may include a film layer or a film laminate. Although the formation of protective clothing of a film can improve particle penetration through the mass of the protective garment, such film or film laminates can also inhibit or prevent the passage of air and the passage of moisture vapor. through them. Generally, protective garments formed from materials that do not allow sufficient passage of air and moisture vapor through them become cumbersome to use correctly for extended periods of time.

Although in some cases, film or film laminate materials can provide improved particulate barrier properties compared to non-woven laminated fabrics, non-woven laminated fabrics generally provide greater comfort to the wearer. Therefore, there is a need for inexpensive disposable protective garments, and more particularly for inexpensive disposable protective garments formed of a nonwoven fabric that provides improved particulate barrier properties while also being breathable and therefore comfortable to be worn correctly for extended periods of time. .

SUMMARY OF THE INVENTION The present invention provides a non-woven fabric having improved particular barrier properties.

In one embodiment, the non-woven fabric includes at least one layer which is subjected to corona discharge and an alcohol repellent material, and particularly an alcohol repellent material formed of a flourinated urethane derivative. An antistatic may also be present on the surface of the non-woven fabric.

In another embodiment, the non-woven fabric is a laminate which includes at least two layers wherein at least one of the layers is subjected to a corona discharge. One layer may be formed from spun fibers and the other layer may be formed from meltblown fibers. An antistatic may be present on the surface of at least one of the layers. Also, an alcohol repellent material, and particularly, an alcohol repellent material formed of a flourinated urethane derivative, may be present on the surface of at least one of the layers. In another embodiment, the nonwoven woven laminate is a three layer laminate wherein at least one of the three layers is subjected to a corona discharge. The two outer layers can be formed from spunbonded fibers and the inner layer can be formed from meltblown fibers. An antistatic may be present on the surface of at least one of the layers. Also, an alcohol repellent material, and particularly an alcohol repellent material formed of a flourinated urethane derivative, may be present on the surface of at least one of the layers.

DETAILED DESCRIPTION OF THE INVENTION As used herein, the term "dielectric" means, according to the Encicopledia McGraw-Hill of Science and Technology, 7a. Edition, Copyright 1992, a material, such as a polymer, which is an electrical insulator and which can hold an electric field with a minimum energy decitation. A solid material is bioelectric if its valence band is complete and is separated from the conduction band by at least three eV.

As used here, the terms "narrowing", "Narrow stretch" or "Narrow stretch" refer interchangeably to a method of lengthening a non-woven fabric, generally in the machine direction, to reduce its width in a controlled manner to a desired amount. The controlled stretching can take place under a cold temperature, a room temperature or higher temperatures and is limited to an increase in the overall dimension in the dimension that is being stretched to the elongation required to break the fabric, which in many cases is around from 1.2 to 1.4 times. When it relaxes, the tissue retracts to its original dimensions. Such a process is described, for example, in US Pat. Nos. 4,443,513 issued to Meitner and Notheis and US Patents Nos. 4,965,122, 5,226,992 and 5,336,545 issued to Morman which all are incorporated in the patents of the United States of America. here for reference.

As used herein, the term "smoothing constricted" or "smoothing and constricting" means a stretched stretch carried out without the addition of heat to the material as it is stretched, for example, at room temperature. In smoothing or stretching, a fabric is said to be stretched, for example, by 20%.

As used herein, the term "non-woven fabric" refers to a fabric having a structure of individual fibers or filaments which are interleaved, but not in an identifiably repeatable manner.

As used herein, the term "spunbond fibers" refers to fibers which are formed by extruding the melted thermoplastic material as filaments of a plurality of usually circular and thin capillaries of a spinner with the diameter of the filaments extruded then being rapidly reduced as by, for example, in U.S. Patent No. 4,340,563 to Appel et al., and in U.S. Patent No. 3,692,618 to Dorschner et al. U.S. Patent No. 3,802,817 issued to Matsuki et al., and U.S. Patent Nos. 3,368,992 and 3,341,394 to Kinney, U.S. Patent Nos. 3,502,763 and 3,909,009 issued to Levy, and in U.S. Patent No. 3,542,615 issued to Dobo and others, which are all incorporated herein by reference. rencia. Spunbonded fibers are generally continuous and greater than 7 microns in diameter. As used herein, the term "melt blown fibers" means fibers formed by extruding a melted thermoplastic material through a plurality of capillary matrix vessels, usually circular and thin as melted threads or filaments into a high current stream. speed, usually of heated gas (air) which attenuates the filaments of melted thermoplastic material to reduce its diameter. Then, the melt blown fibers are carried by the gas stream at high speed and are deposited on a collecting surface to form a fabric of meltblown fibers randomly discharged. Melt blowing is described, for example, in U.S. Patent No. 3,849,241 issued to Buntin, and in U.S. Patent No. 4,307,143 issued to Meitner and in U.S. Pat. North America No. 4,707,398 issued to Wisneski and others, all of which are incorporated herein by reference. The fibers formed by meltblowing are generally smaller than 10 microns in diameter.

Polymers and polyolefin polymers are particularly well suited for the formation of fibers or filaments used to form the non-woven fabrics which are useful in the practice of the present invention. Untreated fabrics can be made from a variety of processes including, but not limited to, air placement processes, wet laying processes, hydroentanglement processes, bonding processes with spinning, blow melting of carding and bonding of short fiber and spinning of solution.

As described in more detail below, the entire thickness of the woven non-woven laminate may be subjected to a corona discharge. Alternatively, the individual nonwoven layers which when combined form the nonwoven woven laminate may be separately subjected to a corona discharge. When the entire thickness of the non-woven fabric laminate is subjected to corona discharge, the fibers forming at least one of the non-woven layers are desirably formed of a variety of bioelectric polymers including, but not limited to polyesters, polyolefins, nylon and copolymers of these materials. The fibers forming the other non-woven layers can be formed into a variety of non-dielectric polymers, including but not limited to cellulose, glass, wool and other protein polymers.

When one or more individual nonwoven layers are separately subjected to corona discharge the fibers forming these non-woven layers are desirably formed of the dielectric polymers described above. Those individual nonwoven layers which are not subjected to corona discharge can be formed from the non-dielectric polymers not described.

It has been found that non-woven fabrics formed of thermoplastic-based fibers and particularly polyolefin-based fibers are particularly well suited for the above mentioned applications. Examples of such fibers include spunbond fibers and meltblown fibers. Examples of such non-woven fabrics formed from such fibers are the non-woven polypropylene fabrics produced by the registry official, Kimberly-Clark Corporation.

In one embodiment, the present invention includes a woven non-woven laminate. For example, the woven non-woven laminate may include at least one layer formed of spunbonded fibers and the layer formed of meltblown fibers, such as an unwoven woven laminate bonded by melt spinning (SM). In another embodiment the nonwoven woven laminate may include at least one layer formed of meltblown fibers which is sandwiched between two layers formed of spunbonded fibers such as an unwoven woven laminate spunbonded / blown-formed. melted / joined by spinning (SMS). Examples of these non-woven laminated fabrics are described in United States Patent No. 4,041,203 issued to Brock et al., In United States Patent No. 5,169,706 issued to Collier et al., And in the patent. of the United States of America No. 4,374,888 issued to Bornslaeger, all of which are incorporated herein by reference.

More particularly, the spunbonded fibers can be formed of polypropylene. Suitable polypropylenes for the spunbonded layers are commercially available as PD-9355 from Exxon Chemical Company of Baytown, Texas.

More particularly, meltblown fibers can be formed of polyolefin polymers and more particularly of a mixture of polypropylene and polybutylene. Examples of such meltblown fibers are contained in U.S. Patent Nos. 5,165,979 and 5,204,174 which are incorporated herein by reference. Even more particularly, the meltblown fibers can be formed of a polypropylene and polybutylene mixture wherein the polybutylene is present in the mixture in a range of from 0.5 to 20% of the mixture. A suitable polypropylene is designated as 3746-G by Exxon Chemical Company, of Baytown Texas. One such suitable polybutylene is available as DP-8911 from Shell Chemical Company of Houston Texas. The meltblown fibers may also contain a polypropylene modified to U.S. Patent No. 5,213,881 which is incorporated herein by reference.

The non-woven SMS fabric laminate can be made by depositing in sequence on the mobile forming web first a layer of spunbond fabric, then a meltblown layer and at the last another layer spun-bonded and then joining the laminate in a manner described below. Alternatively, the layers can be made individually, collected in rolls, and combined in a separate bonding step. The non-woven SMS fabric laminates usually have a basis weight of from about 0.1 to 12 ounces per square yard (osy) (from 3 to 400 grams per square meter (gsm)), or more particularly from about 0.75 to about 5 ounces per square yard (25 to 170 gms) and even more particularly from about 0.75 to about 3 ounces per square yard (25 to 100 gms).

Methods for subjecting non-woven fabrics to corona discharge are well known to those skilled in the art. Briefly, corona discharge is achieved by applying a sufficient direct current (DC) voltage to an electric field initiation structure (EFIS) in the vicinity of a structure receiving the electric field (EFRS).

The voltage must be high enough so that the ions are generated in the EFIS and flow from the EFIS to the EFRS.

Both the EFIS and the EFRS are desirably formed of conductive materials. Suitable conductive materials include copper, tungsten, stainless steel and aluminum.

A particular technique for subjecting non-woven fabrics to corona discharge is the technique described in the patent application in the United States of America No. 07 / 958,958 filed on October 9, 1992, which has been assigned to the University. of Tennessee and is incorporated here by reference. This technique involves here submitting the non-woven fabric to a pair of electric fields in which the electric fields have opposite polarities. Each electric field forms a corona discharge. In those cases where the non-woven fabric is a woven non-woven laminate, the full thickness of unwoven woven laminate can be corona-discharged. In other cases, one or more of the individual layers which form the nonwoven woven laminate or the fibers forming such individual layers may be separately subjected to the corona discharge and then combined with other layers in a juxtaposed relationship to form the laminate non-woven fabric. In some cases, the electrical charge on the surface of the woven laminate not hatched prior to corona discharge can be essentially the same as the electrical charge on the surface of the corona discharge treated fabric. In other words, the nonwoven woven laminate surface may not generally exhibit a higher electrical charge after subjecting the fabric to the corona discharge than the electrical charge present on the tissue surface before subjecting it to corona discharge.

The non-woven laminated fabrics can generally be joined in some manner by being produced in order to give them sufficient structural integrity to withstand the rigors of further processing to a finished product. Bonding can be achieved in a number of ways such as hydroentanglement, sewing, ultrasonic bonding, adhesive bonding and thermal bonding. The ultrasonic bonding is carried out, for example, by passing the unwoven woven laminate between a sonic horn and an anvil roll as illustrated in U.S. Patent No. 4,374,888 issued to Bornslaeger.

The thermal bonding of a woven non-woven laminate can be achieved by passing it between the rollers of a calendering machine. At least one of the calendering rollers is heated and at least one of the rollers not necessarily the same as the heated one has a pattern which is printed on the laminate as it passes between the rollers. As the fabric passes between the rollers, it is subjected to pressure as well as to heat. The combination of heat and pressure applied in a particular pattern results in the creation of bonded areas fused in the woven non-woven laminate where the joints thereon correspond to the pattern of the bonding points on the calendering roll.

Several patterns have been developed for the calendering rollers. An example is the Hansen-Pennings pattern of between about 10 to about 25% bonded area with about 100 to 500 joints / square inch as taught in U.S. Patent No. 3,855,046 issued to Hansen and Pennings. Another common pattern is a diamond pattern with slightly off-center diamonds.

The exact calendering temperature and pressure for the bonding of the woven nonwoven laminate depends on the thermoplastics or of which the non-woven fabric is made. Generally for laminated non-woven fabrics formed of polyolefins, preferred temperatures are between 150 and 350 ° F (66 and 177 ° C) and the pressure is between 300 and 1000 pounds per linear inch. More particularly, for polypropylene, the preferred temperatures are between 132 and 160 ° C and the pressure is between 400 and 800 pounds per linear inch.

In those cases where non-woven fabric is used in or around flammable materials and static discharge is a concern, the non-woven fabric can be treated with any number of antistatic materials. In these cases, the antistatic material can be applied to the nonwoven by any techniques including, but not limited to, embedding the non-woven within a solution containing the antistatic material or by spraying the nonwoven with a solution containing the antistatic material. In some cases, the antistatic material can be applied to both the outer nonwoven surfaces and / or the nonwoven mass. In other cases, the antistatic material may be applied to parts of the nonwoven, such as a surface or selected surfaces thereof.

Of particular utility is the antistatic material known as ZELEC®, a phosphate alcohol salt product from Du Pont Corporation. The non-processed fabric can be treated with the antistatic material either before or after subjecting the fabric to the load. In addition, some or all of the layers of material can be treated with the antistatic material. In those cases where only some of the material layers are treated with antistatic material, the untreated layer or layers can be subjected to loading before or after combining with the antistatic layer or layers.

Additionally, in those cases where the non-woven fabric is used around alcohol, the non-woven fabric can be treated with an alcohol-repellent material. In these cases, the alcohol repellent material can be applied to the nonwoven by any number of techniques, including but not limited to the embedment or by spraying the non-woven fabric with a solution containing the alcohol repellent material. In some cases, the alcohol repellent material can be applied to both the nonwoven outer surfaces and the nonwoven mass. In other cases, the alcohol repellent material can be applied to parts of the nonwoven, such as a surface or surfaces selected therefrom.

Of particular utility are the alcohol repellent materials formed from flourinated urethane derivatives, an example of which includes FX-1801. Material FX-1801, formerly called L-10307 is available from 3M Company of St. Paul, Minnesota. The FX-1801 has a melting point of around 138 ° C. The FX-1801 can be added to either the meltblown and / or meltblown layer in an amount from about 0.1 to about 2.0% by weight or more particularly between about 0.25 and 1.0 percent by weight. The FX-1801 material can typically be applied or can be applied internally by adding the FX-1801 to the fiber-forming polymer before the fiber is formed.

Generally, internal additives, such as the alcohol repellent additive FX-1801, suitable for use in the present invention must be non-toxic and have a low volatility. Additionally, the internal additive must be thermally stable at temperatures up to 300 ° C, and sufficiently soluble in the melted or semi-melted fiber to form the polymer. The internal additive must also be sufficiently phase separated so that the additive migrates from the mass of the polymer fiber to the surface of the polymer fiber as the fiber is cooled without requiring the addition of heat.

The layers of the fabric of this invention may also contain fire retardants, to increase fire resistance, pigments to give the layer the same or different colors, and / or chemicals such as amines locked to provide a resistance to ultraviolet light. improved Fire retardants and pigments for thermoplastic polymers bonded by melt spinning and blowing are known in the art and can be internal additives. A pigment, if used, is generally present in an amount of less than 5% by weight of the layer.

EXAMPLES To demonstrate the attributes of the present invention, three non-woven polypropylene samples were prepared and subjected to corona discharge.

SAMPLE 1 Sample 1 included a layer of meltblown material of about 17 grams per square meter between two layers of spin-bonded material of about 18.7 grams per square meter for a final SMS laminate with about f54 grams per square meter of base weight. The spunbonded layers were made of polypropylene copolymer designated as PD-9355 by Exxon Chemical Company.

The melt blown layer was made of designated polypropylene 3746 G from Exxon Chemical and designated polybutylene from P-8911 from Shell in an amount of around 10% by weight. The laminate SMS of sample 1 was narrowed and smoothed by 8% at room temperature, ZELEC® was present on one of the surfaces joined by spinning in an amount of about 0. 03% by weight of the layer bonded by spinning.

The FX 1801 material was present in the melt blown layer in Sample 1. About 1.0% by weight of FX 1801 material was added to the polypropylene polymer prior to fiber formation. As described above during the processing of the polypropylene polymer to form the fibers, the FX 1801 material bloomed to the surface of the formed meltblown fibers.

SAMPLE 2 Sample 2 was an amount of 1.8 ounces per square yard of polypropylene SMS woven nonwoven laminate. The spin-bonded layers were formed from polypropylene resins-Exxon PD 3445 and Simmons PF-301. The white and dark blue pigments, Ampacet 41434 (Ampacet Inc., of N.Y.) and SCC 4402 (Strandrige Color Inc., GA.), Respectively, were added to the polypropylene resins to form one of the spunbonded layers. The other spunbonded layer was formed from these polypropylene resins without pigments. The meltblown layer was formed from the pigment-free Himont PF-015 polypropylene resin.

The meltblown layer had an average basis weight of about .45 ounces per square yard and each layer bonded by spinning had an average basis weight of about .635 ounces per square yard.

A 2.95% solution of FC808 was prepared by adding 0.5% hexanol, 2.95% FC808 and about 96.5% water. The 2.95% solution of FC808 was applied to the spunbonded layer by spraying. The heat was applied to the spunbonded layer until the spunbonded layer was dried. The FC808 material is an alcohol repellent surface treatment consisting of a polymeric flouroaliphatic ester of (20%), water (80%) and ethyl acetate (400 parts / million). FC808 is available from 3M Company of St. Paul Minnesota). Sample 2 did not contain ZELEC®.

SHOW 3 Sample 3 was an amount of 1.5 ounces per square yard of melt blown fabric. Material FC1802 was present in the meltblown fabric in an amount of about 2.4% by weight of the meltblown fabric. FC1802 material, which was available from 3M Company, is an internal additive which was added to the polypropylene polymer before fiber formation. The primary components of FC1802 material are the 8-carbon flourinated alkyl alkoxylates. The 8-carbon flourinated alkyl alkoxylates comprised up to 86% to 89% of the FC1802 solution. Other components of FC1802 include flourinated alkyl sulfonamides of 8 carbons (69% to 10%), flourinated alkyl alkoxylates of 7 carbons (between 2% to 4%) and flourinated alkyl sulfonamide of 7 carbons (between 0.1% to 1% ).

The corona discharge was produced by using a reversible polarity 50/60 Hz power unit, model No. P / N 25A - 120 volt (from Simco Corporation, Hatfield, PA.), Which was connected to the EFIS, and a 50/60 Hz power unit, of .25A, of 120 v model No. P16V (Simco Corporation, Hatfield, PA.), which was connected to the EFRS. The EFIS was a RC-3 master charge loading bar (Simco Corporation) and the EFRS was a 3-inch solid diameter aluminum roller. The corona discharge environment was 71 ° F and 53% relative humidity. As described in the aforementioned United States patent application 07 / 958,958, two sets of EFIS / EFRS were used. The voltage applied to the first set of EFIS / EFRS was 15 KV / 0.0 KV. respectively. The voltage applied to the second set of EFIS / EFRS was 25 KV / 7.5 KV respectively. The separation between the EFIS and the EFRS for each game was one inch.

The surface voltages for each side of each of the samples was measured. An electrostatic voltmeter (model TreK 344, Trek Inc., Median, N.Y.) was used to measure surface voltages. The values reported below are average values. These average values were obtained by taking the average of at least 10 readings on the sides of the samples.

The particulate filtering properties of each of the samples both before and after corona discharge were evaluated. The particulate filtering test was used to evaluate the particulate filtration properties of these samples which is generally known as the NaCl filtration efficiency test (hereinafter the "NaCl test"). The NaCl test was carried out on an automated filter tester, Model Certitest ™ Model # 8110, which is available from TSI Inc., of St. Paul Minnesota. The particulate filtering efficiency of the test cloth is reported as "percent penetration". The "percent penetration" is calculated by the following formula - 100 x (1- (downstream particles / upstream particles)). The upstream particles represent the total amount of approximately 0.1 / xm NaCl aerosol particles that were introduced into the tester. The downstream particles are those particles which have been introduced into the tester and which have been passed through the mass of the test cloth. Therefore, the "percent penetration" value reported in Tables I-V is a percentage of the total amount of particles introduced into a controlled air flow within the tester that passes through the volume of the test fabric. The size of the test was 4.5 inches in diameter.

The air flow can be constant or varied. At about 32 liters per minute of air flow, a pressure difference of between 4 and 5 mm of Water Gage develops between the atmosphere on the upstream side of the test cloth compared to the atmosphere on the downstream side of the test samples.

The filtration test efficiencies for samples 1-3 are reported in tables I-III, respectively TABLE 1 SAMPLE I Pre Download Corona Post Download Corona% Penetration 33.2% 2.57% ? P MM H20 7.0 6.9 Flow at 1 / m 30.7 30.6 Surface Loading -60 Side A -5 Side A - 3 Side B -5 Side B TABLE II SAMPLE 2 Pre Download Corona Post Download Corona X Penetration 63.0% 62.47% V P MM H20 5.4 4.2 Flow at 1 / m 28.5 28.3 Surface Load -1 side A (only) -66 Side A (only) TABLE 3 SAMPLE III Pre Download Corona Post Download Corona % Penetration 53.7% 51.0% V P MM H20 4.6 4.8 Flow in 1 / m 29.8 30.8 Surface Loading - 7 Side A -2 Side A -74 Side B -5 Side B As the "penetration percentage" for sample I was illustrated in Table I, the SMS laminate with the material FX1801 present in the meltblowing layer, after undergoing corona discharge was lower, for more than 10 times, compared to the "percent penetration" for Sample 1 without the corona treatment. In other words, 10 times less particles passed through the mass the fabric with corona discharge compared to the untreated fabric with corona discharge.

As illustrated in Tables II and III, there was very little difference observed in the "percent penetration" between samples 2 and 3 treated with corona discharge and samples 2 and 3 not treated with corona discharge. Even though these results suggest that there is no significant improvement in the particulate barrier properties of any 2 or 3 samples that were achieved with the corona discharge treatment, it is not known whether all materials based on flourinated alkyl alkoxylate or all the polymeric aliphatic flouro ether base materials similarly effect the particulate barrier properties of a corona discharge treated fabric.

When comparing the results of "percent penetration" of Sample 1 treated with corona discharge later (TABLE I) with the results of "percent penetration" of samples 2 and 3 treated with corona discharge (Tables II and III, respectively), it is clear that significantly different and uneted results are achieved. As such, even when the non-woven fabrics were treated with various alcohol repellents, all non-woven fabrics treated with alcohol repellent did not demonstrate the improved particulate barrier properties when subjected to corona discharge. The Applicant has demonstrated that the barrier properties of a woven fabric treated with an alcohol repellent material formed of flourinated urethane derivatives, an example of which includes the FX-1801, are greatly improved when such a nonwoven is subjected to discharge crown.

Table IV reports the "percent penetration" at several test sites of the width of a sample treated with corona discharge at various flow rates.

TABLE IV Flow at 1 / m 9.4 11.8 16.0 31.8 66.9 ? P MM H20 1. 8 2. 1 3. 0 5. 8 13.7 Percent of 4. 12 0. 255 2. 12 3 .74 3 .42 Penetration Table 5 reports the "percent penetration" at several test sites across the width of a sample treated with corona discharge at a constant flow rate.

TABLE V Flow at 1 / m 23. 1 23.1 23.1 ? P MM H20 4. 6 5.0 4.9 Percent of 0. 974 1.00 3.55 Penetration The results in TABLES IV and V indicate that the changes in P MM H20 and the flow rate (1 / m) over the range studied have little effect on the "percent penetration" resulting from the test particles. The differences can be explained in terms of the variations of tissue formation and more particularly, in terms of variations in fiber density. In other words, variations in the "percent penetration" values can result from variations in the fiber density of the particular test sites through the tissue.

Although the invention has been described in detail with respect to the specific modalities thereof, it will be appreciated by those skilled in the art, upon achieving an understanding of the foregoing, that alterations, variations and equivalents to these modalities can easily be conceived. Therefore, the scope of the present invention should be established as that of the annexed clauses and of any equivalent thereto.

Claims (20)

1. A non-woven fabric comprising: at least one layer formed of fibers, wherein the fibers are subjected to corona discharge include an alcohol repellent formed from a flourinated urethane derivative.

2. The non-woven fabric as claimed in clause 1, characterized in that the fibers forming the layers are meltblown fibers which are formed of a mixture of polypropylene and polybutylene.

3. The nonwoven fabric as claimed in clause 2, characterized in that the basis weight of the layer formed of meltblown fibers is about 0.45 ounces per square yard.

4. The non-woven fabric as claimed in clause 1, characterized in that the fibers include an antistatic treatment.

5. The unwoven woven laminate as claimed in clause 2, characterized in that the polybutylene is present in the mixture in a range of from 0.5 to about 20 percent by weight of the mixture.

6. The nonwoven woven laminate comprising at least two layers formed of spunbonded fibers and at least one layer formed of meltblown fibers wherein the layer formed of meltblown fibers is between the two formed fiber layers joined by spinning, and wherein the fibers of at least one of the layers are subjected to corona discharge; Y wherein at least one of the layers includes an alcohol repellent formed of a flourinated urethane derivative.

7. The unwoven woven laminate as claimed in clause 6, characterized in that the fibers formed by meltblowing are formed of a mixture of polypropylene and polybutylene.

8. The unwoven woven laminate as claimed in clause 7, characterized in that the polybutylene is present in the mixture in a range of from 0.5 to 20 percent of the mixture.

9. The unwoven woven laminate as claimed in clause 6, characterized in that the basis weight of the woven non-woven laminate is about 1.8 ounces per square yard.

10. The unwoven woven laminate as claimed in clause 6, characterized in that the basis weight of the layer formed of the meltblown fibers is about 0.45 ounces per square yard.

11. The unwoven woven laminate as claimed in clause 6, characterized in that the melt blowing fibers are subjected to corona discharge.

12. A woven non-woven laminate comprising: at least two layers formed of spunbonded fibers and at least one layer formed of meltblown fibers wherein the layer formed of meltblown fibers is between two layers formed of spunbonded fibers, and wherein fibers forming at least one of the layers is subjected to a corona discharge; Y wherein at least one of the layers formed of spunbonded fibers includes an antistatic treatment and wherein the layer formed of meltblown fibers includes an alcohol repellent formed of a flourinated urethane derivative.

13. The woven non-woven laminate as claimed in clause 12, characterized in that the melt blowing fibers are formed of a mixture of polypropylene and polybutylene.

14. The unwoven woven laminate as claimed in clause 13, characterized in that the polybutylene is present in the mixture in a range of from 0.5 to 20 percent of the mixture.

15. The woven non-woven laminate as claimed in clause 12, characterized in that the basis weight of the woven non-woven laminate is about 1.8 ounces per square yard.

16. The unwoven woven laminate as claimed in clause 12, characterized in that the basis weight of the layer formed of the meltblown fibers is about 0.45 ounces per square yard.

17. The unwoven woven laminate as claimed in clause 12, characterized in that the melt blowing fibers are subjected to corona discharge.

18. The woven non-woven laminate as claimed in clause 12, characterized in that the particulate filtering efficiency is measured by the NaCl filter efficiency test, is improved by more than 10 times on a similar woven non-woven laminate which has not been subjected to corona discharge.

19. The unwoven woven laminate as claimed in clause 12, characterized in that the particulate filtering efficiency is measured by the NaCl filter efficiency test, across the width of the woven non-woven laminate ranging from about 0.974 to around 3.55.

20. The unwoven woven laminate as claimed in clause 12, characterized in that it has been narrowed and smoothed by 8 percent at room temperature.