KR20020071901A - Nonwoven Webs Having Liquid Impermeability - Google Patents

Abstract

The present invention provides a fabric that acts as a barrier to the liquid. The fabric may comprise a coated substrate. More specifically, the present invention provides a liquid impermeable nonwoven web, ie a nonwoven web that is resistant to penetration by liquid impinging on the web. For such fabrics, porous substrates are useful that include fabrics having pores less than about 12 micrometers in diameter and less than about 40 dyne / cm surface free energy. Pore diameter and surface free energy values (1) and the water vapor transmission rates through the fabric greater than about 3000 g / m ^2/24 hours, (2) the spray impact value at a hydrostatic head of about 91 cm about 0.5 g of less than Provide the fabric.

Description

Nonwoven Webs Having Liquid Impermeability

The fabrics included in the garment can provide protection against external elements such as rain or personal protection against liquid dangerous substances such as toxic chemicals. Therefore, it is often desirable for such fabrics reinforced by chemical treatment to provide suitable resilience.

Unfortunately, garments that provide repulsion can often fail to provide breathability. Breathability can be measured at the rate of water vapor transmission. Moisture, such as sweat, may be trapped in the fabric or garment if the fabric does not provide sufficient rate of water vapor passage. Trapped water vapor can reduce the fit of the garment and cause the worker to fail to wear the garment. Thus, a fabric that provides breathability while providing a fluid barrier will be a preferred fabric that is an improvement over conventional fabrics.

<Definition>

As used herein, the term "fabric" refers to a material made from fibers by methods such as weaving, knitting, felt, extrusion, spunbonding and meltblowing. Fabrics include nonwovens, wovens, laminates, coforms and films.

As used herein, the term "grafted" refers to bonding one material to another, such as covalent bonds.

As used herein, the term "woven" refers to a network of intersected and interlaced materials.

As used herein, the term "nonwoven web" refers to a web that has the structure of individual fibers that are interlaced (forming the matrix) in a manner that is not typically identifiable repeating. In the past, nonwoven webs have been formed by a variety of methods known to those skilled in the art, such as meltblowing, spunbonding, wetting, and various bonded carded web methods.

As used herein, the term “spunbond web” is used to extrude a molten thermoplastic material as a filament from a number of typically circular microcapillaries having a diameter of an extruded filament, and then to change the diameter of the extruded filament, for example fluid-stretch or other wells. It means a web formed by rapid reduction by known spunbonding mechanisms. The manufacture of spunbond nonwoven webs is described, for example, in US Pat. No. 4,340,563 to Appel et al.

The term " meltblown web " as used herein extrudes a molten thermoplastic material into a high velocity gas (e.g. air) air stream as molten fibers through a plurality of fine, usually circular die capillaries, and By a high velocity gas stream is meant a web comprising fibers formed by attenuating the fibers of the molten thermoplastic material and reducing their diameter. Thereafter, the meltblown fibers are transported by the high velocity gas stream to be deposited on the collecting surface to form a randomly dispersed fibrous web. Meltblown processes are well known and are incorporated herein by reference, NRL Report 4364, "Manufacture of Super-Fine Organic Fibers" by VA Wendt, EL Boone and CD Fluharty, NRL Report 5265, "An Improved Device for the Formation of Super-Fine Thermoplastic Fibers "by KD Lawrence, RT Lukas and JA Young] and Butin et al., US Pat. No. 3,849,241, issued Nov. 19, 1974. have.

As used herein, the term "cellulose" means a natural carbohydrate high polymer (polysaccharide) of the formula (C ₅ H ₁₀ O ₅ ) _n which is linked by oxygen bonds to form a substantially linear long molecular chain. It consists of anhydroglucose units. Natural sources of cellulose include deciduous, coniferous, cotton, flax, esparto grass, milkweed, straw, jute, hemp and sugarcane dregs.

As used herein, the term "pulp" refers to cellulose processed by treatments such as thermal, chemical and / or mechanical treatments.

As used herein, the term "coform" refers to a material made of nonwoven and pulp fibers.

As used herein, the term "slurry" means an aqueous mixture of insoluble materials such as pulp.

As used herein, the term "fiber" refers to a basic solid form, generally crystalline, which is characterized by a relatively high adhesion and a very high length to diameter ratio, such as hundreds of ones. Examples of natural fibers are wool, silk, cotton and asbestos. An example of a semisynthetic fiber is rayon. Examples of synthetic fibers include spinneret extruded polyamides, polyesters, acrylics and polyolefins.

As used herein, the term "% by weight" refers to the percentage calculated by dividing the weight of the mixture material by the total weight of the mixture and multiplying this share by 100.

As used herein, the term "addition%" refers to the percentage of material added to a substrate after substrate treatment. Addition% is calculated by subtracting the weight before treatment from the weight after treatment and dividing this difference by the weight before treatment. Thereafter, this share is multiplied by 100 to obtain the added%.

As used herein, the term "% reduction in bond strength " calculates the maximum peel load difference between treated and untreated substrates, divides this difference by the maximum peel load of untreated substrate, and multiplies this share by 100 to determine the maximum It means the percent reduction of the peel load.

As used herein, the term "water vapor transmission rate" refers to a constant state of water vapor flow that flows from each surface to a particular parallel surface through a unit area per unit time of a standard object under temperature and humidity of a particular condition, which is " WVTR ".

As used herein, the term "normalized" means to conform to a specification or standard. In the water vapor permeation test procedure, standardization is the calibration of “baseline” vapor permeation at a rate proportional to the standard of 5,000 g / m ² / day for a CELGARD® 2500 microporous film. This standardization corrects for differences in oven air inlet humidity.

As used herein, the term "vapor pressure" means the pressure exerted by a vapor in which the solid or liquid form is in equilibrium.

As used herein, the term "permeable" means the quality or condition of a material that determines the amount of flow through the material per unit time under certain conditions.

As used herein, the term "non-hygroscopic" means that it does not readily absorb and retain moisture.

The term "hygrometer" as used herein refers to a device for measuring humidity in the air.

As used herein, the term "flange" means an edge for attaching to another object.

As used herein, the term "sample" refers to a portion of the product taken for testing and is used as a raw material for test specimens in the laboratory.

As used herein, the term "sample" refers to a specific fraction of a sample to be tested.

Summary of the Invention

The present invention provides a fabric for establishing a barrier to liquids. Fabrics include coated substrates. Water vapor transmission rate of the coated fabric may be exceeding 3000 g / m ^2/24 hours, a water spray (rain) impact value of the hydrostatic head of about 91 cm may be less than about 0.3 g. The coating can be selected from the group consisting of fluorinated monomers, ternary interpolymers (tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, and vinylidene fluoride), such as Dyneon ™ THV fluorinated thermoplastic materials. Can be. The fluorinated monomer may be selected from the group consisting of fluoroacrylates and fluoromethacrylates. Alternatively, the coating may be selected from the group consisting of fluoroacrylate monomers, ternary interpolymers, and siloxanes.

The substrate may also be a nonwoven material, more specifically a meltblown material. The substrate may also be selected from the group comprising polymers, more specifically polyolefins, polyesters, acrylics and polyamides. In addition, the polymer may be polypropylene.

Another embodiment of the invention is a method of making a barrier fabric. The method includes providing a substrate, applying an activator solution to the substrate, and exposing the substrate to electromagnetic radiation to form a barrier fabric. The method may include an additional step of passing the nip prior to radiation exposure of the substrate applied with the solution. Water vapor transmission rate of the barrier fabric may be greater than about 3000 g / m ^2/24 hours, the water spray impact value at a hydrostatic head of about 91 cm may be less than about 0.3 g. The active agent may be a fluorinated monomer, more specifically fluoroacrylate. In addition, the fluorinated monomer may be dissolved in an acetone solvent to form about 1 to about 3 weight percent fluorinated monomer in solution. The substrate may also be selected from the group comprising polymers, more specifically polyolefins, polyesters and polyamides.

Another embodiment of the invention is a fabric that provides a barrier to the liquid. The fabric may comprise a polypropylene substrate. The polypropylene substrate can be coated with fluorinated monomers. Water vapor transmission rate of the fabric may be greater than about 3000 g / m ^2/24 hours, the water spray impact value at a hydrostatic head of about 91 cm may be less than about 0.3 g.

The present invention relates to a nonwoven web. More specifically, the present invention relates to nonwoven webs that are liquid impermeable and resistant to penetration by liquid impingement on the web.

1 is an enlarged cross sectional view of an exemplary die tip.

2 is an enlarged schematic cross-sectional view of another exemplary die tip.

3 is an enlarged schematic cross-sectional view of another exemplary die tip.

4 is an enlarged schematic cross-sectional view of another exemplary die tip.

5 is a bottom perspective view of an exemplary die tip.

DETAILED DESCRIPTION OF THE INVENTION The present invention is now directed to embodiments of the invention, one or more of which are described below. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For example, features shown or described as part of one embodiment may be used in another embodiment to obtain another embodiment. Accordingly, the present invention is intended to embrace such modifications and variations as fall within the scope of the claims and their equivalents. Other objects, features and aspects of the invention are disclosed in the following detailed description or are apparent from the following detailed description. It should be understood by those skilled in the art that the present discussion is merely illustrative of exemplary embodiments and is not intended to limit the broader aspects of the invention as embodied in the exemplary configurations.

While the fabric of the present invention permits the passage of vapor through pores in the fabric, it is desirable to exhibit repulsion against various liquids. Preferably, the present invention facilitates increasing the breathability while providing a liquid barrier using a relatively large pore size fabric.

Untreated fabrics or substrates of the invention can be made from woven materials, nonwoven materials, laminates, and films. Such substrates include natural fibers such as wool, polymers or mixtures thereof. Polymers used to prepare the substrate include polyolefins such as polyethylene, polypropylene and polybutylene, polyesters, polyamides such as nylon, polyethylene terephthalate, polyesters such as acrylic or mixtures thereof. Exemplary materials are sold under the trade names Exxon 3746G, Exxon 3505, manufactured by Exxon Chemical Company, Houston, TX, USA, or HIMONT PF-015, manufactured by Montel Polyolefins, Wilmington, DE, USA. Polypropylene.

In general, the substrates used in the present invention may have several features related to average pore size, average fiber diameter, apparent web density, basis weight and thickness. The average pore size of one exemplary substrate can be less than about 50 microns. Preferably, the average pore size of the substrate can be about 1 to 10 microns. More preferably, the average pore size of the substrate can be about 2 to 8 microns. Pore size can be measured by a capillary flow porometer as described below.

The average fiber diameter of the substrate can be from about 2 microns to about 7 microns as measured by scanning electron micrographs and image analysis. In addition, the apparent web density of the substrate may be from about 0.8 g / cm 3 to about 2 g / cm 3 as measured by dividing the mass by volume (area x thickness). In addition, the basis weight of the substrate may be from about 0.5 osy (17 g / m 2) to about 3 osy (102 g / m 2). Preferably, the basis weight of the substrate may be about 1.5 to 3 osy (51 to 102 g / m 2). The thickness of the substrate may range from about 0.015 in (0.038 cm) to about 0.40 in (1.02 cm).

In one preferred embodiment, the substrate is a meltblown web having a pore size of about 5 to 10 microns. This web may be formed by a meltblown process as disclosed in US Pat. No. 4,526,733 to Lau, incorporated herein by reference.

Several variables such as melting point, air temperature, air pressure, formation height and throughput affect the formation of the meltblown web. With reference to US Pat. No. 4,526,733, the melting point of the polymer in the die is preferably from about 400 ° F. (204 ° C.) to about 550 ° F. (288 ° C.), more preferably from about 430 ° F. (221 ° C.) to about 500 ° F. ( 260 ° C.). Alternatively, the melting point of the polymer in the die is preferably in the range of about 380 ° F. (193 ° C.) to about 700 ° F. (371 ° C.), more preferably about 400 ° F. (204 ° C.) to about 550 ° F. (288 ° C.) Can be. Examples of air pressure and temperature entering the die through the conduits are about 400 ° F. (204 ° C.) to about 550 ° F. (288 ° C.) and about 2 psig (13,800 Pa) to about 20 psig (138,000 Pa), more preferably. And from about 430 ° F. (221 ° C.) to 500 ° F. (260 ° C.) and about 4 psig (27,600 Pa) to about 12 psig (82,760 Pa). Alternatively, examples of the temperature of the air entering the die through the conduits are from about 70 ° F. (21 ° C.) to about 550 ° F. (288 ° C.), more preferably from about 400 ° F. (204 ° C.) to about 550 ° F. (288 ° C.) May range. The temperature difference between the polymer and the introduced air in the die may vary from about 0 ° F. (0 ° C.) to about 500 ° F. (278 ° C.) or alternatively from about 200 ° F. (111 ° C.) to about 300 ° F. (167 ° C.) Can vary.

The forming height, the distance between the exit of the die and the top surface of the belt, ranges from about 3 in (8 cm) to 20 in (51 cm), more preferably from about 5 in (13 cm) to about 9 in (23 cm) Can be. The polymer throughput is about 0.7 (lb / in) / hr (125 (g / cm) / hr) to about 5 (lb / in) / hr (446 (g / cm) / hr), more preferably about 0.7 ( lb / in) / hr (125 (g / cm) / hr) to about 1.5 (lb / in) / hr (268 (g / cm) / hr).

Referring to FIG. 1, an exemplary meltblown process may also include a heating device to warm the die tip. One such exemplary die 10 is shown in FIG. 1. Die 10 may include body 14, die tip 18, and air plates 30A-B. Die tip 18 may be attached to body 14 using any suitable means, such as bolts 28A-B. Air plate 30A-B may be secured in close proximity to die tip 18 using any suitable means, such as bolts 32A-B. Body 14 and die tip 18 may form passages 22 that terminate into narrow cylindrical outlets 26 for discharging the polymeric material. Generally, outlet 26 may be about 0.0145 in (0.0368 cm) in diameter and about 0.1 in (0.254 cm) in length. In addition, die tip 18 and air plate 30A-B may form channels 36A-B for allowing air to pass through outlet 26 to release polymer fibers into gap 38. In this exemplary die 10, the die tip 18 is recessed.

The die tip may include a tip 24, an insulating coating 46, an endothermic coating 46, and a screen filter 20. Insulating coating 46 may be a low thermal conductivity material, such as ceramic paint, and endothermic coating 48 may be a high endothermic material, such as black stove paint.

Air plate 30A-B may include bolts 32A-B, spacing wedges 34A-B and heating device 42A-B. Bolts 32A-B and spaced wedges 34A-B may be used to adjust air plate 30A-B relative to die tip 18. One or more heating devices 42A-B, preferably two heating devices 42A-B can be used. The heating devices 42A-B may be electrical resistance cartridge heaters or electromagnetic radiation emitters. By way of example, the heating devices 42A-B may be quartz glass infrared lamps or emitters, such as those commercially available from Hereaus-Amersil, Norcross, GA. Preferably, these lamps can be as small as possible if they provide sufficient heat. By way of example, these lamps may be 10 millimeters in diameter and may extend longer than the length of the die tip 18. More preferably, these lamps emit 170 watts / in (67 watts / cm). In addition, these lamps may be coated with reflective material 44A-B, such as gold, at about 270 ° around the lamp. The uncoated perimeter of the heating device 42A-B may be located from about 0.01 in (0.03 cm) to about 1 in (2.54 cm) from each side 50A-B of the die tip 18. Preferably, the uncoated circumference of the heating device 42A-B may be located about 0.125 in (0.32 cm) from each side 50A-B of the die tip 18. In addition, the heating devices 42A-B can be recessed in the air plate 30 to minimize the generation of turbulence in the air flow through the channels 36A-B.

When operating the heating devices 42A-B, they typically provide heat near the die tip vertex 24. The heating devices 42A-B can transfer heat to the tip 24 by conduction by radiating heat to the tip 18 close to the die tip vertex 24, or preferably heating elements 42A-B. Heat can be radiated directly to the vertex 24. Radiant heat is absorbed by the endothermic coating 48 to help heat the vertices 24, and the thermal insulation coating 46 to help maintain heat inside the tip 18.

Referring to FIG. 2, another bottom of another exemplary V-shaped die 100 is described. Die 100 may include die tip 118 and die tip vertex 124. The die tip 118 may use one or more buried electric cartridge heaters, but preferably four buried electric cartridge heaters 142A-D. These cartridge heaters 142A-D provide heat to the polymer inside the vertex 124 and are preferably located as close as possible to the vertex 124.

Referring to FIG. 3, another exemplary die 200 is described. Die 200 may include die tip 218 and die tip vertex 224. Preferably, the die tip 218 has one or more passageways extending along the length of the die 200, but preferably four passages 242A-D extend along the length of the die 200. These passages 242A-D may be filled with heated fluid, such as steam, oil, polymer, wax, air or water, which is pumped along the length of the die 200 to draw polymer inside die tip vertex 224. Heat. Preferably, these passages 242A-D are located as close as possible to the die tip vertex 224.

4 and 5, another exemplary die 300 is described. Die 300 may include die tip 318, and die tip 318 may include anode 342, cathode 344, electrical insulation layer 352, and die tip vertex 324. . Current may flow from the electrode 342 through the vertex 324 of the die 300 between the hole 350 and the electrode 344, thereby using a resistor to allow the die tip 318, more preferably the die tip. The vertex 324 can be heated. Alternatively, referring to FIG. 5, electrodes 362 and 364 are located at each end of die 300 to cause a current to flow longitudinally across die 300. Alternating current can be used for one of the electrode sets 342 and 344, or 362 and 364. In some cases, the alternating current may be high frequency.

The present invention can form meltblown webs from materials such as polymers. Examples of the polymer include polyester; Polyolefins such as polyethylene and polypropylene; Polyamides such as nylon; Elastomeric polymers, and block copolymers. The melt flow rate of these materials can be from about 12 to about 1200 decigrams per minute. Examples of polypropylene include those sold under the trade names Exxon 3746G or Exxon 3505 at Exxon Chemical Company, Houston, Texas, or under the trade name HIMONT PF-015 from Montel Polyolefins, Wilmington, Delaware. In addition, these materials may include additives to reduce the viscosity, such as peroxides, or additional materials such as fluoroacrylate monomers may be placed on the die to characterize the extruded polymer. DuPont Corporation, Wilmington, Delaware, is a family of fluoroacrylate monomers under the trade name ZONYL-T®.

Fabrics formed by these meltblown processes can have an average pore size of approximately 50 microns or less. Preferably, these fabrics may have an average pore size of about 1 to about 10 microns. More preferably, these fabrics may have an average pore size of about 2 to about 8 microns. Fabrics having such pore sizes can be made into garments that provide a liquid barrier.

In one preferred embodiment, the solution may be first applied by treatment to the substrate and then the substrate may be grafted by exposure to an electron beam. The solution may comprise an active agent and a solvent. Active agents include fluorinated monomers; Fluorinated polymers such as ternary interpolymers of tetrafluoroethylene, vinylidene fluoride and polytetrafluoropropylene; Perfluorinated polymers; And polyalkyl siloxanes such as organomodified siloxane emulsions. Examples of ternary interpolymers are those sold under the trade name THV-330R from Dyneon LLC, St. Paul, Minn. Examples of siloxane emulsions are those sold under the trade name NUDRY ™ 30 by OSi Specialties Group, Witco Corporation, Sistersville, West Virginia.

Examples of fluorinated monomers include 2-propenoic acid, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyl ester; 2-propenoic acid, 2-methyl-2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyl ester; 2-propenoic acid, pentafluoroethyl ester; 2-propenoic acid, 2-methyl-, pentafluorophenyl ester; Benzene, ethenylpentafluoro-; 2-propenoic acid, 2,2,2-trifluoroethyl ester; And 2-propenoic acid, 2-methyl, 2,2,2-trifluoroethyl ester.

Other fluoroacrylate monomers that may be used in solution are CH ₂ = CROCO (CH ₂ ) _x (C _n F _{2n + 1} ) (where n is an integer from 1 to 8, x is an integer from 1 to 8) , R is H or CH ₃ ). In many instances, the fluoroacrylate monomers may consist of a mixture of homologues corresponding to different values of n.

Monomers of this type can be readily synthesized by those skilled in the chemical art using well known techniques. In addition, many of these materials are commercially available. DuPont Corporation, Wilmington, Delaware, is a family of fluoroacrylate monomers under the trade name ZONYL®. These agents having different distributions of homologues can be used. More preferably, ZONYL® formulations sold under the trade names "TAN" and "TM" can be used in the practice of the present invention.

Solvents used in the present invention may include halogens, ketones, esters such as ethyl acetate, and ethers such as diethyl ether, and water. Halogens may include chloroform, methylene chloride, perchloroethylene, and halogens sold under the trademark FREON® by DuPont Corporation. Ketones may include acetone and methyl ethyl ketone.

The weight percent of active agent in the solution may range from about 0.5 to about 50. Preferably, the weight percent of active agent in the solution may range from about 0.5 to about 30. More preferably, the weight percent of active agent in the solution may range from about 1 to about 10.

After impregnating or saturating the nonwoven substrate with a solution, the substrate is exposed to cell beam radiation to graf the active agent to the substrate, thereby forming a coating. One exemplary electron beam device is Energy Science Inc. of Wilmington, Massachusetts. Manufactured under the trade name CB 150 ELECTROCURTAIN® from Energy Sciences Inc. This device is disclosed in US Pat. Nos. 3,702,412, 3,769,600 and 3,780,308, which are each incorporated herein by reference.

In general, the substrate may be exposed to a cell beam operating at an acceleration voltage of about 80 to about 350 kilovolts. Preferably, the acceleration voltage is about 80 to about 250 kilovolts. More preferably, the acceleration voltage is about 175 kilovolts. The substrate may be irradiated with about 0.1 to about 20 million rods (Mrad). Preferably, the substrate may be irradiated at about 0.5 to about 10 Mrad. More preferably, the substrate can be irradiated at about 1 to about 5 Mrad.

exam

Several tests were performed on samples made according to the invention. These tests include basis weight, pore size, thickness, and water vapor transmission rate (WVTR). Pore size was measured according to ASTM procedure F-316-86, a published test procedure incorporated by reference herein. Pore diameters are measured using capillary flow porometers, Porus Materials, Inc., Ithaca, NY. It applied to the test marketed by (Porous Materials, Inc.).

Thickness test

The thickness of the sample was measured by the Starrett bulk test, which measures the thickness or bulk of the nonwoven or wipe material under a controlled loading pressure of 0.05 lb / in psi. Specimen sizes specified are greater than 3 in × 4 in. The thickness of the knit is usually measured as the distance between the anvil or floor and the pressure foot used to apply the specified pressure. Thickness is one of the basic properties of knitted fabrics and is a useful measure of performance characteristics. The thickness varies considerably with the pressure applied to the specimen at the time of the measurement, so it is essential to specify the pressure when measuring the thickness.

This procedure measures the thickness of the specified area under a controlled loading pressure of 0.05 lb / in ² . Record data to nearly 0.001 in for nonwoven materials and 0.001 mm for wipe materials.

The test is performed in a standard laboratory atmosphere of about 23 ° C. (about 73 ° F.) and is typically measured on the material after ambient conditions are met. For nonwoven products, cut at least 5 in × 5 in specimens from the roll to be tested. For nonwoven products, the test indicator was zeroed and the platen was slowly raised by pressing the foot pedal. The specimen was placed in a circle on the floor, centered, and the foot pedal was relaxed to slowly lower the platen onto the specimen. After 3 seconds, the readings were read and recorded to approximately 0.001 in for nonwoven products. After reading, the readings were zeroed again for further test specimens.

Waterproof test

A standard watering tester is used to test the resistance of the fabric to water impermeability by impact. This test is a useful measure of the anticipated water penetration resistance of fabrics. Water permeability can be applied to any woven or nonwoven fabric, whether waterproof or water repellent. The test can be used to measure or predict the expected water penetration resistance of the fabric and is particularly suitable for measuring the penetration resistance of garment fabrics such as those used in raincoats and the like. The waterproofness of the fabric depends not only on the resilience of the individual fibers, but also on the overall fabric structure. By varying the pressure on the fabric, it can be tested in the fabric under different impacts of water strength.

In this procedure, 8 inch by 8 inch specimens are used as a protective barrier covering a sheet of pre-weighed absorbent blotting paper. The horizontal water fountain with the predetermined hydrostatic head was directed to the specimen for exactly 5 minutes and then the blotting paper was weighed again. The difference between the initial weight and the final weight of the blotting paper is the weight of water that has penetrated through the specimen. The larger the difference, the more water has passed through the fabric, i.e., the lower the water repellency of the fabric. Therefore, the larger the number, the lower the waterproofness.

The test used in this case is performed in accordance with the specifications of US Federal Test Methods Standard 191A, AATCC Standard 35-1980 and ASTN Standard D583. Five specimens from each sample are tested and water is sprayed onto the sample for five minutes. A standard AATCC standard watering tester, available from MICO Instrument Company, Cambridge, Massachusetts, is used. The impact sprinkling tester includes two standard spray nozzles, a specimen holder, a rigid frame for supporting the specimen holder, and a shield for spray interruption between tests. Blotting paper was purchased from James River Paper Company, Richmond, Virginia, and designated as "white AATCC textile blotting paper." Place the test device and adapt the sample to the test atmosphere. The standard atmosphere for testing is air maintained at a relative humidity of about 50 ± 2% and a temperature of about 73 ° F. The adaptation time is 2 hours, but this time can be shortened if equilibrium is reached. Continuous weighing at least 30 minutes apart is considered to have reached equilibrium when the weight increase of the specimen is less than 0.1% of the specimen weight. Specimen size is 8 inches by 8 inches.

<Water vapor transmission rate test>

The water vapor transmission rate (WVTR) was determined using the test method described below. The top of the water cup was sealed with the fabric to be evaluated and placed at a controlled environmental temperature. As a result of evaluating the water in the cup, the vapor pressure inside the cup was relatively higher than the vapor pressure of the environment outside the cup. This difference in vapor pressure causes the vapor inside the cup to flow out of the cup through the test material. This flow rate depends on the permeability of the test material that seals the top of the cup. The water vapor permeation rate was calculated using the difference between the initial cup weight and the final cup weight.

Devices and materials used include cutting dies, hammers, cutting boards, blotter papers, steam measuring cups, scales, trays, ovens, graduated cylinders, microporous films, hygrometers and stopcok greases. The diameter of the cutting die is typically 2.875 inches (7.303 cm) or 3.000 inches (7.620 cm). The cutting die may be of the manual type used for hammers and cutting boards or the mechanical type used in die presses. It is recommended to use a blotter paper (or any suitable stiff and heavy paper) under the sample to make it easier to remove the sample from the die. The blotter can be selected from any type and thickness that can be easily cut using the selected cutting die method.

Wood hammer may be about 5 pounds (2 kg) with soft sides and may not be necessary if using a mechanical die press. The cutting board can be any suitable size and material. The steam measuring cup can be flanged cast aluminum. The cup has a mechanical seal and neoprene gasket and can be 2 inches (5 cm) deep. A representative cup is marketed as part number 681 from the Twin-Albert Instrument Co. of Philadelphia, PA. The balance shall hold a steam measuring cup and be able to measure accurately to ± 0.01 g. The tray should be suitable for use when moving the cup into or out of the oven, preferably a tray capable of placing the maximum number of cups in the oven at one time. The tray is non-hygroscopic and should be a material that can withstand about 100 ° F. (37.7 ° C.) for extended periods of time. The tray should have an appropriate lip in the peripheral protrusions to contain water if spilled. The oven shall be convection type capable of maintaining about 100 ± 1 ° F (37.7 ± 0.6 ° C).

The capacity of the graduated cylinder should be 100 ml. Representative microporous films used as control standards are commercially available under the tradename Celgard ^R 2500 from the Separations Products Division of Hoechst Celanese Corporation, Charlotte, NC. The hygrometer should be in the range of relative humidity or equivalent 0 to 100 ± 3%. Locking head grease sold by THOMAS LUBRISEAL ^R or DOW CORNING HIGH-VACUUM GREASE ^R may be used. Hygrometers and greases are available from Fisher Scientific, Pittsburgh, 15219, USA.

Samples were prepared by selecting samples from clean and dried material. Test specimens were taken from the folded and wrinkled, and any torsion-free sample areas that made these specimens abnormal from the rest of the test material. The number of specimens per sample was chosen to give the desired reliability.

The accuracy of the various devices was confirmed or the device was tested. Balances and ovens used in this method were regularly tested to ensure accuracy and repeatable readability. In general, the assay system has been established and maintained to some extent with reference to the device manufacturer or its literature.

The apparatus and materials were prepared by the following method. The oven was turned on and set to about 100 ° F. (37.7 ° C.). The accuracy of the oven temperature was checked for whether it was maintained at a constant temperature. The steam measuring cup was checked to ensure that it was clean, dry and free of foreign matter. Each test specimen was cut with two specimens per Celgard ^R 2500 control standard tray using a 2.875 inch (7.3 cm) or 3 inch (7.6 cm) diameter die. The specimens have been handled with care to prevent the accumulation of excess moisture, oil or other contaminants on the specimens which may cause erroneous results. Samples were tested without any specific preconditioning, but samples were checked to confirm that there were no surface contaminants.

The test procedure involves labeling each steam measuring cup with appropriate identification information. The graduated cylinder was then charged with about 100 mL of distilled water at room temperature 72 ± 5 ° F. (or 22.2 ± 3.1 ° C.) and poured into the steam measuring cup body. 100 ml of water in the steam measuring cup made 0.75 inch (19 mm) water surface from the top of the cup body. The distance of 0.75 inches (19 mm) from the water surface to the top of the steam measuring cup body was important to maintain reproducible results from test to test. The sealing surface of the vapor measuring cup gasket was coated with grease. An upper flange was placed on the steam measuring cup body by matching the steam measuring cup body flange with the upper flange screw hole. The neoprene gasket was placed in contact with the sample to provide a moisture proof seal around the edge. The screw was inserted into the screw hole and tightened flat by hand. The weight of each loaded vapor measuring cup was measured and recorded as the "previous" weight. Two or more specimens of Celgard ^R 2500 control standard microporous film were prepared for all tested specimen trays. The loaded steam measuring cup was carefully moved to the tray with the surface facing up. Care was taken to avoid "sloshing" water in the cup in contact with the specimen. If the specimen was in contact with water due to "sloshing," the results from that specimen were considered invalid. When testing multiple specimens of the same material, the specimens were randomly placed on a tray to avoid gathering together specimens of the same material. At least two vapor measuring cups containing Celgard ^R 2500 control standards were placed in each specimen tray. After placing the tray containing the specimens in the oven, the time and relative humidity at the oven air inlet were recorded as the "previous" relative humidity. Samples were placed in an oven for 24 hours. Samples were removed from the oven and the time and relative humidity at the oven air inlet were recorded as "after" relative humidity. The weight of the loaded steam measuring cup was measured immediately and recorded as the "after" weight.

Several equations were used to calculate the result. The correction factor for each tray was calculated by the following equation. The weight loss for each cup containing the test standard was calculated by the following formula:

"Before" weight of test standard cup (g)-"After" weight of test standard cup (g)

= Weight loss of test standard cup (g)

The test standard basis ratio was calculated by the formula:

The average of the standard basis ratios (BR) for each tray was calculated as follows:

The correction factor (CF) was calculated as follows:

The standardized WVTR for the specimen was calculated by the following formula. The weight loss for each cup containing sample material was calculated as follows:

"Before" weight of specimen cup (g)-"After" weight of specimen cup (g)

= Weight loss of the specimen cup (g)

The basic specimen ratio was calculated as follows:

The specimen WVTR was calculated as follows:

(Sample ratio) × (CF) = WVTR (standardized)

Practically the method [Method 5524 of the Federal Test Methods Standard No. 191A], a watering impact test was performed and the hydrostatic head value was recorded in cm or inches of water. However, the method was changed as follows. Variations include using five specimens instead of three for each sample, 5 minutes on one of the following hydrostatic heads required at 24 inches (61 cm), 36 inches (91 cm), 48 inches (122 cm). Spraying water.

Substrates were prepared according to the meltblown process described above from polypropylene sold under the trade name HIMONT PF-015 from Montel Polyolefins, Wilmington, Delaware, USA. This substrate was divided into three samples. One sample was used as a control and the other two samples were treated. The aminosiloxane immersed sample was passed through the nip roll twice before drying at room temperature. After immersion in the fluoroacrylate, some samples were immersed and dried by hanging on the hood and the remaining samples were passed through a nip roll.

Two substrates were saturated with an active agent dissolved in a solvent. The substrate was saturated with this solution and allowed to dry for about 12 hours. The nip rolls were operated under pressure of about 2.5 pounds per straight inch (equivalent to about 0.45 kg / straight cm). The substrate was then passed through an electric beam device and irradiated. The sample was then dried to constant weight. Table 1 below describes the samples and conditions upon sample preparation.

Sample number Active agent weight% menstruum Probe (Mrad) One Aminosiloxane 10 water 18 minutes tote 90-132 ℃ 2 Fluoroacrylate 2 Acetone 5 Mrad

The test was done in the control and two samples. The results of the three specimens are listed in Table 2 below.

Sample number Basic weight (osm) Thickness (microns) Average hole diameter (microns) WVTR (g / ㎡ / 24 hours) Watering shock (g at approximately 91cm) Control 2 (70) 0.043 6.4 5128 8.2 One 2 (70) 0.043 8.0 4935 0.2 2 2 (70) 0.043 9.2 4213 0.8

It is preferred to have a fabric having a WVTR of 3000 g / m 2/24 hours or more and a watering impact value of about 0.5 g or less at about 91 cm of hydrostatic head. As shown in Table 2, the WVTR of Sample 1 is greater than 3000 g / m 2/24 hours and the sprinkling impact value is less than 0.3 g at about 91 cm. In addition, the WVTR of Sample 2 exceeds this value, but the sprinkling impact value is about 0.3 g at about 91 cm. The control group has the highest WVTR value, but has a spray shock value greater than Samples 1 and 2.

Other fabrics were also prepared according to the meltblown method described above from polypropylene sold under the trade name Exxon 3746G under the trade name Exxon 3746G of Houston, Texas, USA. The fabric was divided by the samples and the samples were processed by the method of the invention except that one sample was kept as a control. The basis weight of the samples was about 2 osy (70 gsm).

The treated sample was saturated with an active agent dissolved in a solvent. The fabric was saturated with this solution and allowed to dry for about 12 hours. In addition, some fabrics were passed between two rubber nip rollers of a laboratory weaving machine before drying. The nip rolls were operated under pressure of about 2.5 pounds per straight inch (0.45 kg / straight cm). Thereafter, the sample was dried to constant weight. The substrate was then passed through an electric beam device and irradiated.

Table 3 below describes the samples and conditions upon sample preparation.

Sample number Active agent weight% menstruum Probe (Mrad) One Fluoroacrylate 1.0% Acetone 3 2 Fluoroacrylate 1.0 Acetone 5 3 Fluoroacrylate 3.0 Acetone 5 4 Fluoroacrylate 3.0 Acetone 3 5 Fluoroacrylate 3.0 Acetone 5 6 Fluoromethacrylate 3.0 Acetone 3 7 Fluoromethacrylate 3.0 Acetone 3 8 THV-200P 5.0 water 5 9 THV-330R 5.0 water 5 10 Siloxane water 5 11 THV-200P 5.0 water 5 12 THV-200P water 13 Siloxane 5.0 Acetone 5 14 Fluoromethacrylate 5.0 Acetone 5 15 Fluoroacrylate 5.0 Acetone 5

Samples 4, 5 and 7 were passed through a nip roll and all remaining samples were immersed in the solution. These samples were subjected to basis weight, WVTR and watering impact tests. The data in Table 4 below are for three specimens excluding some of the sprinkling impact samples. Samples 11, 12, and 15 are represented by data from one specimen for sprinkling impact, samples 3 and 7 are represented by data from two specimens for sprinkling impact, and Sample 5 is data from four specimens for sprinkling impact. Represented by. A sprinkle impact test was not performed on Sample 14, which was labeled "N / A".

Sample number Basic weight (osm) WVTR (g / ㎡ / 24 hours) Watering shock (g at approximately 91cm) Control 2 (70) 4705 0.49 One 2 (68) 4243 0.22 2 2 (68) 4265 0.47 3 2 (68) 4423 0.28 4 2 (68) 4274 1.3 5 2 (68) 4316 0.23 6 2 (68) 3842 12 7 2 (68) 4274 0.46 8 2 (68) 4158 13 9 2 (68) 4065 0.24 10 2 (68) 4224 0.20 11 2 (68) 4227 5.8 12 2 (68) 4501 12 13 2 (68) 4224 0.23 14 2 (68) 4414 N / A 15 2 (68) 4266 0.28

As shown in Table 4, the WVTRs of Samples 1, 3, 5, 9, 10, 13 and 15 exceed 3000 g / m 2/24 hours and the sprinkling impact value is less than 0.3 g. In comparison, the spray shock value of the control sample is greater than 0.5 g. Thus, the treated fabric of the present invention provides a material with acceptable breathability and barrier protection.

Although the present invention has been described in connection with specific described embodiments, it should not be understood as limiting the subject matter included in the present invention to these specific embodiments. In contrast, the subject matter of the present invention includes all alternatives, modifications and equivalents, which may be included within the spirit and scope of the following claims.

Claims (21)

(a) and the water vapor transmission rate through the substrate greater than about 3000 g / m ^2/24 hours, (b) the watering impact value at the hydrostatic head of about 91 cm is less than about 0.5 g, A substrate having a surface free energy of less than about 40 dynes / cm, characterized in that at least one pore has a minimum size of less than about 12 μm. The porous substrate of claim 1, wherein the fabric is a fibrous nonwoven web. The nonwoven web of claim 2 wherein the fibers of the nonwoven web are coated with a surface free energy reducing material. 4. The nonwoven web of claim 3 wherein the coating is a fluorinated monomer, fluorinated ternary interpolymer, siloxane or polysiloxane. The web of claim 4 wherein the fluorinated monomer is fluoroacrylate or fluoromethacrylate. The web of claim 4 wherein the coating is a fluoroacrylate monomer, a fluoroacrylate terpolymer interpolymer, a siloxane, or a polysiloxane. The liquid impermeable nonwoven web of claim 2, wherein the fibrous nonwoven web is made of a thermoplastic polymer. The nonwoven web of claim 7 wherein the thermoplastic polymer is selected from the group consisting of polyolefins, polyesters, polyurethanes, and polyamides. The nonwoven web of claim 8 wherein the thermoplastic polymer is a polyolefin. 10. The nonwoven web of claim 9 wherein the thermoplastic polymer is polypropylene or polyethylene. (a) coated with a fluorinated monomer effective to bring the surface free energy of the web material to less than about 40 dynes / cm, (b) expose pore diameter and surface free energy values by exposure to heat or ionizing radiation. i) and a water vapor transmission rate greater than about about 3000 g / m ^2/24 hours, ii) the water splash impact value in the hydrostatic head of about 91 cm is less than about 0.5 g A liquid-impermeable nonwoven web, including a polyolefin nonwoven web material, comprising fibers adjusted to achieve a diameter and having pores of about 3 to about 12 micrometers in diameter. (a) providing a nonwoven web of fibers having a pore diameter of about 3 to about 12 μm, (b) coating the fibers with a surface free energy reducing material, (c) the pore diameter value and the surface free energy lowering material value i) and a water vapor permeation rate of the nonwoven web in excess of about 3000 g / m ^2/24 hours, ii) the water splash impact value in the hydrostatic head of about 91 cm is less than about 0.5 g Method for producing a liquid impermeable nonwoven web comprising the step of selecting to be. 13. The method of claim 12, further comprising exposing the coated fiber to heat or ionizing radiation. 13. The method of claim 12, further comprising passing the nip prior to heat or radiation exposure of the coated nonwoven web. The method of claim 12, wherein the surface free energy reducing material is a fluorinated monomer. The method of claim 15, wherein the fluorinated monomer is fluoroacrylate. The method of claim 15, wherein the fluorinated monomer is dissolved in acetone prior to the coating step to provide a solution containing about 1 to about 3 weight percent of the fluorinated monomer. The method of claim 12, wherein the nonwoven web fibers consist of a thermoplastic polymer. 19. The method of claim 18, wherein the thermoplastic polymer is selected from the group consisting of polyolefins, polyesters, polyurethanes, and polyamides. The method of claim 19, wherein the thermoplastic polymer is polyolefin. The method of claim 20, wherein the thermoplastic polymer is polypropylene.