JP2003505229A - Electret filter media with plasma treatment - Google Patents

Abstract

(57) The electret filter media includes an additive or mixture thereof that enhances the charge stability of the media. The filter media achieves an acceptable alpha value over the range of the filtration challenge without a significant decrease in alpha value over time. Suitable charge additives include fatty acid amides and mixtures thereof.

Description

Detailed Description of the Invention

TECHNICAL FIELD The present invention relates to electret filter media with enhanced charge stability.
BACKGROUND OF ET FILTER MEDIA Background of the Invention Electret filter media has long been used in many filtration applications. The electret filter media is one that includes a dielectric insulating polymer fabric that has been treated to have substantially permanent spatially oriented opposite charge pairs or dipoles. Common polymers used in electret filter media include polypropylene, polyethylene, polyesters, polyamides, polyvinyl chloride, and polymethylmethacrylate.

Conventional filter media are substantially devoid of electrostatic charge and the performance of the filter is dependent on shock, impact, and diffusion. The electret filter material provides improved filtration performance over conventional filter materials. It is believed that the presence of oriented dipoles in the electret filter media enhances filter performance by attracting and retaining charged or uncharged particles that the filter media should filter.

Electret filter material is made by a variety of known techniques. One electret filter media manufacturing technique typically involves extruding a polymer with a high melt flow index through a linear array of orifices. An air knife is used to thin the extruded polymer fibers at a ratio of about 300: 1. The thinned fibers, about 1-10 microns in diameter, are collected on a rotating drum or moving belt by applying a suitable vacuum. The fabric is then treated to impart charge pairs or dipoles on the fabric. This charge pair or dipole can be applied to the fibers using, for example, AC and / or DC corona discharge.

One problem associated with electret filter materials is that the charge pairs or dipoles imparted to the filter media are often not stable. In some cases, the charge or its spatial orientation is lost after filtering the impurities for a relatively short time. As a result, the performance of the filter device is significantly lowered in a relatively short time (for example, 20 minutes or less).
National Institute for Safety and Health (The National Institute)
f Safety and Health, NIOSH) established standards for the performance of filters. The NIOSH standard is a 200 mg filtration challenge (cha
Evaluate the filter tool in the carrier after llenge). One filtration challenge of solid aerosol particles evaluates filter performance against sodium chloride particles suspended in air. Another filtration challenge for liquid aerosol particles evaluates filter performance against droplets of dioctyl phthalate (DOP) suspended in air. Electret filter media, generally including sodium chloride test criteria, can maintain charge stability and filter performance when filtering solid aerosols. However, liquid aerosols tend to deplete the charge on electret filter media, thus reducing filter performance even after short periods of filtration.

Accordingly, there is a need for electret filter media with improved charge stability that can maintain acceptable filter performance over time.

SUMMARY OF THE INVENTION The present invention avoids the aforementioned problems by providing a fiber fabric that retains particles and / or oils without significantly reducing filtration performance even after prolonged filtration challenges. . In a particular embodiment, the filter media of the present invention is an oleophobic plasma treated electret polymer fiber fabric (web) which may optionally include charge stabilizing additives such as fatty acid amides. Accordingly, the present invention provides a charge-stabilized electret filter media with improved filtration performance characteristics.

The filter medium of the present invention is an industrial face mask or gas mask, indoor air filter, surgical mask, room air cleaner, cabin air filter, vacuum filter, HVAC filter. , HEPA filters, ASHRAE filters, and ULPA filters, and can be used in a variety of filtration applications. As used herein, "filter" includes any tool that uses the filter media of the present invention to filter air and / or other gases.

The present invention provides a filter media having a meltblown hydrophobic and / or hydrophobic plasma treated electret polymer fiber cloth. In one embodiment, the polymeric fiber fabric is annealed. Typically, hydrophobic and / or oleophobic plasma treated electret filter media are treated with a hydrophobic and / or oleophobic material such as alkylene, acrylate, methacrylate, alkyloxirane, or alkyleneoxirane. Has been done. These hydrophobic and / or oleophobic materials are preferably halogenated, eg fluorinated. The preferred hydrophobic and oleophobic alkylene is hexafluoropropylene. A preferred hydrophobic and oleophobic alkyloxirane is hexafluoropropyloxirane (2-trifluoromethyl-2-fluoro-3,3-difluorooxirane).

The present invention also provides a filter media having a meltblown hydrophobic and / or oleophobic plasma treated electret polymer fiber fabric in which melt-fabricable fatty acid amide is present in the fabric. Typically, the amide is present at a concentration in the range of about 0.01 to about 20% by weight. In some embodiments, the filter media is annealed.

In another aspect, the invention relates to a filter having a filter media having a meltblown hydrophobic and / or oleophobic plasma treated electret polymer fiber cloth. In the preferred embodiment, the filter fabric is annealed.

In yet another aspect, the present invention provides a meltblown sparse fatty acid amide present in the fabric, wherein the amide is present in a concentration ranging from about 0.01 to about 20% by weight. It relates to a filter having a filter media having an oily plasma treated electret polymer-filter cloth. In the preferred embodiment, the filter fabric is annealed.

In yet another aspect, the present invention is directed to a method of making meltblown hydrophobic and / or oleophobic plasma treated electret polymer media. The meltblown polymer fiber fabric is treated to form a substantially permanent charge pair or dipole in the meltblown polymer fabric. The polymer fabric is treated with a plasma having hydrophobic and / or oleophobic reactive species, preferably a plasma containing hexafluoropropylene reactive species. Permanent dipoles, such as electret properties, can be imparted to the fabric by a variety of techniques including AC corona or DC corona discharge and combinations thereof. In a preferred embodiment, this method of manufacture can be modified by heat treating the polymer fabric, such as annealing.

In another aspect, the invention relates to a method of making an electret filter media by providing a meltblown-polymer fiber fabric having charge stabilizing fatty acid amides incorporated into the fibers. The polymer fabric is treated with a plasma having hydrophobic and / or oleophobic reactive species, preferably a plasma containing hexafluoropropylene reactive species. The fabric is then subjected to conditions that cause substantially permanent charge pairs or dipole, electret properties to form in the meltblown polymer fabric. The fatty acid amide is typically present at a concentration in the range of about 0.01 to about 20% by weight. In a preferred embodiment, this method of manufacture can be modified by heat treating the polymer fabric, such as annealing.

Electret polymer fiber fabrics can be made from a variety of polymer materials including polypropylene, polyester, polyamide, polyvinyl chloride, polymethylmethacrylate, and polyethylene. Among them, polypropylene is a more preferable polymer material. The polymer fibers forming the fabric typically have diameters in the range of about 1-20 microns, and the polymer-fiber fabric weighs about 10-520 g / m ² .

The electret filter media of the present invention is characterized by the improved filtration performance and improved charge stability of the electret filter media. In particular, the filter media can provide the desired filterability, as indicated by the alpha value, despite successive filtration challenges. In one embodiment, the filter media passes the NIOSH criteria for Class P95 non-woven filter media. In other embodiments, the filter media passes the NIOSH criteria for classification P99 non-woven filter media. Preferably, the filter media passes the NIOSH criteria for type P100 nonwoven filter media.

Other advantages of the invention will be readily apparent to those skilled in the art when reading the following description.

All weight percentages mentioned herein are based on the total weight of the fabric unless otherwise stated.

The objects, advantages, and features of the present invention will be better understood with reference to the following detailed description when considered in connection with the accompanying drawings, wherein like reference numerals indicate like parts throughout the drawings. .

DETAILED DESCRIPTION OF THE INVENTION The features and other details of the invention will now be described more particularly. This is also what is pointed out in the claims. It will also be appreciated that the particular embodiments of the invention are shown by way of illustration and not as limitations of the invention. The essential features of this invention can be embodied in various embodiments without departing from the scope of the invention.

The present invention is based, at least in part, on the discovery of electret filter media with improved charge stability. This charge stability is evident from acceptable alpha values, including minimal alpha value reduction, when the filter media is subjected to solid and / or liquid aerosol testing. Even if a decrease in alpha occurs, the final alpha value still indicates acceptable filter performance. The filter media of the present invention may optionally include at least one charge stabilizing additive, such as a fatty acid amide or a mixture of two or more fatty acid amides, for hydrophobic and / or oleophobic plasma treated electrets. Includes polymer-fiber cloth. In a preferred embodiment, this fiber cloth is annealed.

The use of reactive or excited gases in the treatment of fibers, such as nonwovens, provides a method of treating surfaces with energetic species that react with the substrate. For example, the surface chemistry of the fibers can be altered to make materials otherwise incompatible with a large number of different materials compatible. The plasma may be used to deposit a hydrophobic and / or oleophobic coating on the nonwoven to improve filter performance, eg, particle and / or oil retention, without significant loss of filter performance. Treatment of non-woven fabrics with plasma activated species eliminates many of the drawbacks associated with conventional gas treatment methods and results that would otherwise be unattainable.

“Hydrophobic” as used herein repels the passage of liquid water or aqueous bodily fluids, such as blood, saliva, sweat and urine, and liquid water through its structure, A non-woven fabric of the present invention is described which can interfere.

As used herein, “oleophobic” is not wet with body fluids including oils, greases or oil components such as sweat, and is capable of impeding the passage of oils and greases through the structure. The nonwoven fabric of the present invention is described. Therefore, the oleophobic treated fiber fabric of the present invention has improved ability to repel oils such as DOP or mineral oil.

The present invention facilitates the use of plasma activated species, such as monomers, for treating fibers or nonwovens in a continuous or batch process, eliminating the drawbacks of conventional surface treatments such as coatings. Exclude.

The method of the present invention continuously provides a plasma activated species in a treatment zone maintained at sub-atmospheric or atmospheric pressure and continuously passes a fiber cloth through the treatment zone, whereby It includes the step of treating the fabric with a plasma activated species such as a fluorinated monomer.

“Continuous” as used herein means that the length of time in any part of the nonwoven is substantially less than the length of time the device is in motion.
Further, as used herein, "continuous" means that the nonwoven to be treated only traverses the treatment zone containing the plasma activated species once during the treatment process of the fabric through the plasma apparatus. This treated nonwoven may be introduced back into the second plasma or may be further treated, for example passed through an AC and / or DC corona discharge or elevated temperature.

By “plasma activated species” according to the present invention is intended a reactive gas species which comprises or is derived from the ionization of an ionizable gas into the primary plasma. As used herein, the term "primary plasma" refers to the excited state of a gas that can be ionized while the gas is under the direct influence of an electromagnetic field or other plasma generator, and also refers to the highest active state of the reaction system. A "plasma" or "primary plasma" is created by introducing an ionizable gas into a vacuum chamber and exciting the gas with, for example, radio frequency (RF) energy. This RF energy converts gas into electrons, ions,
Cleaves into free radicals and metastable excited species. See, Cormia, "Use of Plasma to Reprocess New Materials," cited herein by reference, R & D Magazine (Magazine), July 19, 1990, p. 60, further H. ． Yasuda, "Plasma Polymerization", Academic Press, 1985. Plasma activated species according to the present invention may also include, but are not limited to, electrons, ions, free radicals, metastable species commonly referred to as the afterglow of a plasma. Of course, when referring to "plasma activated species," the term is understood to include at least one plasma activated species.

Various methods suitable for generating plasma species are known to those skilled in the art. These include low temperature plasmas, high temperature plasmas, parallel plate reactors, asymmetric parallel plate reactors and glow discharges, but these should not be considered as limiting the invention. Any method or device capable of generating a plasma is suitable for use in the present invention. The preferred method is a low temperature, low or high vacuum plasma method.

“Treatment zone” refers to the area within the apparatus where the nonwoven fabric is in contact with the primary plasma and / or other plasma active species. In some embodiments, the non-woven fiber cloth is first contacted with an ionizable gas. Thereafter, as the fabric moves to the area under the action of the RF-generating plasma-generating electrode, the fabric comes into contact with the primary plasma as previously defined. The cloth will then come into contact with the primary plasma for the entire length of the plasma-generating electrode, and possibly for some short distance thereafter.

Plasma treatment can be used to modify or surface treat non-woven fiber fabrics by “functionalization”, “coating”, or “grafting”. In the case of "functionalization",
Gases that can be used to generate plasma and plasma active species are not able to polymerize. The electrons and active species generated in the plasma by the ionization of the gas come into contact with the fiber or fabric surface. It is believed that the plasma active species abstracts atoms such as hydrogen or molecules such as methyl groups from the surface of the material, thereby leaving active sites. The active sites generated on the surface react with other active species to generate various chemical functional groups on the fiber or fabric surface.

“Coating” is a technique recognized by introducing a complex gas, such as a volatile hydrophobic and / or oleophobic monomer, into a chamber and causing it to ionize. This produces various active fragments which recombine as a film on the surface of the fiber or fabric and bind very precisely around the fiber or fabric surface.

“Grafting” is a recognized technique and is a trade-off between plasma functionalization and conventional surface chemistry. In this method, a plasma of a noble gas, such as argon or helium, produces free radicals on the surface of the fabric. After plasma activation and before exposure to this atmosphere, the fabric surface is exposed to vapors of unsaturated monomers, for example. Free radicals on the surface react with unsaturated monomers, causing the polymer layer to be grafted onto the activated fabric surface.

The term surface grafting is generally used in contrast to through grafting, in which the graft extends in various ways throughout the original polymer sample. Sul-graft may be referred to as uniform grafting as compared to non-uniform surface grafting.

In the case of through-grafting, the grafted polymer penetrates the substrate in various ways. In surface grafting, the penetration of the graft is limited to the vicinity of the surface, and as a result, changes in properties such as swelling of the grafted polymer in the solvent are limited to the vicinity of the surface. The extent and concentration of penetration near the surface of the grafted polymer depends on the conditions of the grafting reaction.

Examination of plasma treatments reveals that even in the case of surface treatments, the overall properties of the substrate polymer change to some extent, the extent of the change being more or less proportional to the degree of surface treatment. The properties of plasma treated polymer surfaces are also affected by plasma treatment. The surface property can be changed by increasing the degree of plasma treatment. However, this can be achieved without significantly changing the overall properties of the base polymer.

The characteristics of the plasma polymerization method used to generate the composite structure are quite clear from the comparison. Plasma polymerization (on the polymer substrate) modifies the surface with minimal changes to the overall properties of the substrate polymer, while surface grafting by conventional means results in the grafting into the bulky substrate. Tend to change the properties of the substrate as a whole.

When treating polymer-fiber fabrics with plasma, it is not necessary for the plasma treatment to be uniform in all. A thin plasma treated layer, typically on the order of 50 Angstroms, is sufficient for some applications. However, in order to obtain a uniform layer, the layer will generally have a thickness of at least 500 Angstroms and will range in thickness up to about 1 micron. The exact thickness of the applied layer will vary with the size and composition of the fabric being treated, the composition of the layer applied, and the extent to which the fabric is exposed to primary plasma or plasma active species.

Various polymer substrates can be used for the fiber cloth. These include polyolefins such as polyethylene, polypropylene, polyisobutylene, and ethylene-alpha-olefin copolymers, acrylic polymers and copolymers such as polyacrylate, polymethylmethacrylate, ethyl polyacrylate, vinyl chloride polymers and copolymers. , For example polyvinyl chloride, polyvinyl ethers such as polyvinyl methyl ether, polyvinylidene halides such as polyvinylidene fluoride and polyvinylidene chloride, polyacrylonitrile, polyvinyl ketones, polyvinylamines, polyvinylaromatics such as polystyrene, polyvinylesters such as polyacetic acid. Copolymers of vinyl, vinyl monomers with each other and with olefins, such as ethylene-methyl methacrylate copolymers, acrylonitrile- Tylene copolymers, ABS resins, and ethylene-vinyl acetate copolymers, natural and synthetic rubbers such as butadiene-styrene copolymers, polyisoprenes, synthetic isoprene, polybutadiene, butadiene-acrylonitrile copolymers, polychloroprene rubbers, polyisobutylene rubbers, ethylene- Propylene rubber, ethylene-propylene-diene rubber, isobutylene-isoprene copolymer, and polyurethane rubber, polyamide such as nylon 66 and polycaprolactam, polyester,
For example, polyethylene terephthalate, polycarbonate, polyimide, polyether
Ter, fluoropolymers such as polytetrafluoroethylene and fluorinated ethylene propylene.

Typical gases used for plasma treatment of polymer-fiber cloths are carrier gases,
For example, nitrogen, helium, oxygen, carbon dioxide, methane, ammonia, sulfur dioxide,
And nitric oxide, noble gases, reactive monomers, and combinations thereof. Typical reactive monomers have at least one degree of unsaturation, such as vinyl or allyl groups, such as alkylene, or those having an oxirane ring (epoxide), oxetane, or ether ring, such as alkyloxirane, or alkylene. It is oxirane. Therefore, monomeric forms of acrylic, methacrylic, unsaturated amides, dienes, trienes, oxiranes, alkyleneoxiranes, and oxetanes can be used for hydrophobic and / or oleophobic plasma polymerization with meltblown fiber fabrics.

Particularly suitable reactive monomers include those which are halogenated (Br, I, Cl, F) and impart hydrophobicity and / or oleophobicity to the treated fiber fabric. Suitable examples of hydrophobic and / or oleophobic vinyl groups include tetrafluoroethylene, octafluorobutylene and preferably hexafluoropropylene. Examples of hydrophobic and / or oleophobic halogenated alkyloxiranes are, for example, tetrahaloethylene oxide, ie tetrafluoroethylene oxide (2,2,3,3-tetrafluorooxirane), hexahalopropylene oxide, ie hexafluoropropylene oxide (2 -Trifluoromethyl-2-fluoro-3,3-difluorooxirane), hexahalooxetane, i.e. 2,2,3,3,4,4-hexafluorooxetane, and octahalobutylene oxide, i.e. octafluorobutylene oxide. 2,2,3,3,4,5,5-octafluorotetrahydropyran)
including. An example of a hydrophobic and / or oleophobic alkylene luoxirane is hexafluoroallyloxide. A suitable example of a plasma initiated process is US Pat. No. 4,845.
It can be seen at No. 132.

Suitable reactive monomers include unsaturated fluorocarbons such as tetrafluoroethylene, hexafluoropropylene and octafluorobutylene, and oligosilicons such as hexamethyldisiloxane, tetramethyldisiloxane and tetraethylsilane. The use of mixtures of the gases mentioned above, such as helium and hexafluoropropylene, is also conceivable. Of course, the choice of gas is virtually unlimited as long as it ionizes to produce plasma active species.

In operation, polymer-fiber fabrics, with or without charge stabilizing agents, generally have a stable base pressure of about 0.01-, depending on the composition of the untreated fabric material. Place in a chamber degassed to about 760 Torr (atmospheric pressure), preferably about 0.05 to about 0.15 Torr. The operating pressure is generally about 0.01-using a vacuum pump.
It is maintained at 10.0 Torr, more preferably about 0.01-1.0 Torr. The flow rate of the ionizable gas is maintained at about 1-100 liters / minute (lpm), more preferably about 0.1-about 10 lpm is established and maintained. Alternatively, gas flow can be determined in lpm per foot width of fabric material. A suitable processing range when using these units is 1-20 lpm / ft2, more preferably about 2-.
About 20 lpm / width foot, most preferably 3 lpm / width foot.

RF energy is supplied and used to generate a plasma of ionizable gases and plasma-active species in the process chamber, and more particularly in the process zone. Typically, the gas pumped to the process chamber comprises a carrier gas such as helium and a reactive gas such as a monomer. The supply of RF energy is typically about 50-
It provides power in the range of about 5000 Watts, more preferably about 500 to about 3000 Watts. Alternatively, power can be measured in watts / width foot of cloth material. A suitable treatment range when using these units is from 100 to about 1000 watts / width foot, preferably about 500 to about 750 watts / width foot, and most preferably about 6 watts.
50 watts / width foot.

The polymer fabric is about 1 (feet / minute (fpm)) to about 100, preferably about 1.
5 to about 30 fpm at the plasma processing chamber. These factors can be widely varied as the size of the device is adapted to higher production volumes.
As the cloth width increases, the pressure, flow rate, and power values of the ionizable gas will have to be scaled up correspondingly. For example, the rate depends on the reactor design, such as power and electrode area. The preferred speed used to make the fiber fabric of the present invention provided a residence time in the plasma chamber of 45 seconds to 1 minute.

Plasma is typically generated using radio frequency or microwave energy as is known in the art.

The polymer fabric can be further treated to make it electret and may be treated with Stefan (St.
phen) T. It can be manufactured as described in Cox US Pat. No. 09/335002, "Charge Stabilized Electret Filter Media". Various techniques for applying permanent dipoles to polymeric fabrics for making electret filter media are well known. This charging can be done using AC and / or DC corona discharge and combinations thereof. The characteristics of the discharge used depend on the shape of the electrodes, the bipolar nature, the size of the gap, and the gas or gas mixture.
In one embodiment, charging can be achieved simply using an AC corona discharge device. In yet another embodiment, it is useful to use both AC and DC corona discharge devices. In the preferred technique, the polymer fabric is first subjected to an AC corona discharge and then treated with one or more continuous DC corona discharge devices. Charging can also be accomplished using other techniques, including friction-based charging techniques. Typically, the fiber cloth is provided with about 1 to about 30 kV (in the form of energy, eg DC or AC discharge) / cm, preferably about 10 to about 30 kV / cm, suitably about 10 to about 20 kV / cm. Subject to discharge.

It will be appreciated by those skilled in the art that corona devices, AC corona discharge devices and / or DC corona discharge devices can be placed above and below the meltblown fiber fabric to impart electret properties to the fiber fabric. Placement includes placement of colorless polished rolls on either side of the fabric and placement of active electrodes on the top or bottom of either side of the fabric. In one embodiment, only one type of corona discharge device, such as a DC or AC corona discharge device, is placed on the top, bottom, or otherwise both above and below the fabric. In other embodiments, AC or D
The C discharges may be combined and used alternately. The AC or DC corona discharge device can be controlled so that only positive or negative ions are generated.

In one embodiment, a permanent dipole can be applied to the polymer fiber fabric as follows. It is first charged using an AC corona and then using a series of DC corona discharge devices, such as a DC charge bar. The DC corona discharge device is located on alternating surfaces of the passing fabric, each successive DC discharge device having a different polarity,
That is, positive / negative charges are applied. In the preferred embodiment, the DC corona discharge device located above and below the non-woven fabric undergoes an alternating charge change from positive to negative in a series of treatments, eg 2, 4, 6 treatments. DC corona discharge device is positive or negative,
The charge does not change.

An example of a method of producing electret properties in fiber fabrics can be found in US Pat. No. 5,401,446, which is incorporated herein by reference.

The present invention therefore provides a filter media having a meltblown hydrophobic / oleophobic plasma treated electret filter cloth. In one embodiment, the polymeric fiber fabric is annealed. The filter media, typically hydrophobic and / or oleophobic plasma treated, comprises a reactive plasma species, such as preferably halogenated,
For example, it is treated with a plasma containing fluorinated hydrophobic and / or oleophobic alkylene, acrylate, or methacrylate species. The preferred hydrophobic and / or oleophobic alkylene is hexafluoropropylene. The preferred hydrophobic and oleophobic oxirane is hexafluoropropylene oxirane.

The present invention further provides a filter media having a meltblown hydrophobic and / or oleophobic plasma treated electret polymer fiber fabric in which a melt-processible fatty acid amide is present in the fabric. Typically the amide is present at a concentration in the range of about 0.01 to about 20% by weight. The electret filter media treated with the hydrophobic and / or oleophobic plasma has a reactive plasma species, such as preferably halogenated,
For example, it has been treated with a plasma containing fluorinated hydrophobic and / or oleophobic alkylene, acrylate, or methacrylate species. In one embodiment, the filter media is annealed.

In another aspect, the present invention relates to a filter tool wherein the filter media is a meltblown hydrophobic and / or oleophobic plasma treated electret polymer fiber cloth. In this preferred embodiment, the filter cloth is annealed.

In yet another aspect, the invention provides that the filter media comprises a melt processable fatty acid amide, such as a charge stabilizing additive, in the fabric, wherein the amide is from about 0.01 to about 2.
It relates to a filter which is a meltblown hydrophobic and / or oleophobic plasma treated electret polymer fiber cloth present in a concentration in the range of 0% by weight. In the preferred embodiment, the filter cloth is annealed.

Examples of charge stabilizing additives include fatty acid amides derived from fatty acids. As used herein, the term "fatty acid" is known to those skilled in the art and is intended to include saturated or unsaturated straight or branched chain carboxylic acids derived from the hydrolysis of fat.
Examples of suitable fatty acids are lauric acid (dodecanoic acid), myristic acid (tetradecanoic acid), palmitic acid (hexadecanoic acid), stearic acid (hexadecanoic acid), oleic acid ((Z) -9-octadecenoic acid), linolenic acid. ((Z, Z) -9,2-
Octadecadienoic acid), linoleic acid ((Z, Z, Z) -9,12,15-octadecatriene difference) and eleostearic acid ((Z, E, E,)-9,11,13.
-Octadecatrienoic acid). Typically, the amides formed from the above mentioned acids are primary amides prepared by methods well known in the art.

Secondary and tertiary fatty acid amides are suitable as charge stabilizing agents in which the amide nitrogen is substituted with one or more alkyl groups. Secondary and tertiary fatty acid amides can be prepared in a manner well known in the art, for example by esterification of fatty acids followed by amidation reaction with a suitable alkylamine. The alkyl substituent on the amide nitrogen may be a straight or branched chain alkyl group having about 2-12 carbon atoms,
Preferably it has about 2-14, more preferably about 2-6, most preferably about 2. In a preferred embodiment, the fatty acid amide may be a "bis" whose alkylene chain has two nitrogens on two independent amide molecules. For example, alkylenebis fatty acid amides include alkylenebis-stearamide, alkylenebis-palmitamide, alkylenebis-myristamide, and alkylenebis-lauramide. Typically the alkyl chain has 2-8 carbons, preferably 2. This alkyl chain may be linear or branched. Suitable bis fatty acid amides are ethylene bis-stearamide and ethylene bis-palmitamide, such as N, N'-ethylene bis-stearamide and N.
, N'-ethylene bispalmitamide.

In certain embodiments, charge stabilizing additives, such as fatty acid amides, may be present in the polymer-fiber fabric at a concentration in the range of about 0.01 to about 20% by weight. In another embodiment, the charge stabilizing additive is about 2.0 to about 20 in the polymer fiber fabric.
It may be present at a concentration in the range of weight percent. The preferred concentration range of the charge stabilizing additive for the fatty acid amide is from about 5 to about 11% by weight of the fabric, preferably from about 1 to about 8%. Intermediate concentration ranges mentioned above, for example about 2.5 to about 17% by weight, 4.0 to about 15
%, And about 6.0 to about 12.0% are also contemplated to be part of this invention. Also included are concentration ranges, for example, 1-about 6%, 2.5-about 12%, etc., using any combination of the above mentioned upper and / or lower limits.

As mentioned above, one group of useful charge stabilizing additives are fatty acid amides. Examples of suitable fatty acid amides include stearamide and ethylenebis stearamide. The exemplary stearamide is UniChema Chemicals, Inc.
Commercially available as UNIWAX 1750 from electricals, Inc, Chicago, Illinois). ACRAWA
X ^R ) C is Lonza, Inc., Fair Lawn, New J.
ersey) is a commercially available ethylenebis-stearamide. Acrawax C contains N, N′-ethylenebisstearamide (CAS110-30-5) and N, N′-ethylenebispalmitamide (CAS5518-18-3) in a weight ratio of 65/35/2 ( N, N'-ethylene bis-stearamide / N, N'-ethylene bispalmitamide / C14-C18 fatty acid derivative) and include with C14-C18 fatty acid derivative (CAS67701-02-4). For example, its commercial product comprises N, N'-ethylenebisstearamide, N, N'-ethylenebispalmitamide with C14-C18 fatty acids. In one embodiment of the invention, N, N'-
Either ethylene bis-stearamide or N, N'-ethylene bis-palmitamide may be the sole charge stabilizing additive. In other embodiments, C14-C1
The ratio of 8 fatty acids can vary from about 0-20% based on the total amount of bisamide. In yet another embodiment, about 0-100 for each bisamide.
Mixtures of N, N'-ethylenebisstearamide and N, N'-ethylenebispalmitamide falling in the range of% can be used as additive mixtures such as 80/20, 70/30, 50/50.

The polymer used to form the fibers of the fabric can be selected from many suitable polymers. Examples of these polymers include polyethylene, polyesters, polyamides, polyvinyl chloride, and polymethylmethacrylate, and preferably polypropylene.

Those skilled in the art will appreciate that meltblown fiber fabrics are composed of fibers having a relatively wide fiber diameter distribution. The average fiber diameter of the polymers used to form the polymer fiber fabric generally ranges from about 1 to about 20 microns. Depending on the intended use, a more preferred average polymer fiber diameter is in the range of about 1 to about 15 microns, more preferably about 2 to about 4 microns.

The fabric basis weight of the polymer-fiber fabric will vary depending on the requirements of the intended filtration application. Lighter fabric basis weights generally provide better filtration, while filter media having higher basis weights provide higher resistance or pressure drop across the filtration barrier. For many applications, fabric basis weights may range from about 10 to about 520 g / m ² . Preferably, the weight of the fabric is in the range of about 30 to about 400 g / m ² , more preferably about 30 to about 200 g / m ² . One of ordinary skill in the art can readily determine the optimum fabric basis weight by considering factors such as desired filter efficiency and acceptable resistance. Further, the number of layers of polymer-filter cloth used in a given filter application is also about 1.
It can be changed with -10 sheets. Those skilled in the art can easily determine the optional number of sheets to use.

Filter performance is evaluated on different scales. The filter or filter media is desirably characterized by a low permeability of the contaminants to be filtered across the filter. However, at the same time a relatively low pressure drop or resistance across the filter should be considered.
Permeability, often expressed as%, is defined as: Permeability = C / C ₀ where C is the concentration of particles after passing through the filter and C ₀ passes through the filter. The previous particle concentration. Filter efficiency is defined as 100-% transmission. Since it is desirable for an effective filter to keep both the permeability and pressure drop through the filter as low as possible, the filter is the slope of the logarithm of permeability and pressure drop across the filter. It is evaluated by a value called (α): α = −100 log (C / C ₀ ) / DP where DP is the pressure drop across the filter. The steeper the gradient or the higher the alpha value, the better the filtration performance.

In many filtration states it is important to have a high initial alpha value. However, if not so, it is equally important to maintain adequate alpha values during the filtration process. As mentioned above, lowering the alpha value is a problem often encountered in filtration processes. Thus, in many cases it is important to achieve an acceptable alpha value during the filtration process. Some standard tests to evaluate filter performance focus on permeability (as related to alpha value) and resistance after 200 mg loading. Alpha reduction is generally not a problem with filtered gases containing only solids. In fact, for such filtration applications, the alpha value often increases with time. The phenomenon of alpha depletion is more pronounced when filtering gasses containing liquid droplets or a mixture of liquid droplets and solid particles.

The Dioctyl Phthalate (DOP) test for the purpose of the illustration was a T equipped with an oil generator.
An automated filter tool tester purchased from SI was used. This device measures the pressure drop across the filter media and the resulting permeability values on an instant or "load" basis under flow rates of 115 liters per minute (lpm) or less. An instantaneous test is defined as a set of permeability and simultaneous pressure drop readings. The "load" test is defined as a continuous series of pressure drop / permeability measurements made approximately once every minute until the desired challenge is achieved. This challenge is calculated by knowing the flow rate and substance concentration of the test agent, eg DOP.

In the examples provided below, a flow rate of 85 lpm and a test filter area of 170 cm ² was used. The filtration media was placed in the device and sealed for a 200 mg DOP load. Pressure drop and permeability values were recorded approximately every minute until the desired load was achieved. The final transmission and resistance values, as well as the decrease in overall efficiency, fell within the established values for NIOSH.

This DOP test shows that three levels of filter efficiency are 95%, 99% and 99.9.
NIOSH is 42C. F. R. Based on criteria such as those classified in §84. The type of resistance to deterioration of filter efficiency is N (oil,
For example, no resistance to DOP), R (resistance to oil), and P (oil resistance). Therefore, the non-woven filter media of the present invention are R and preferably P95 (95% oil resistance tested), P99 (99% oil resistance tested) and P100 (99.9 tests tested).
Pass the NIOSH classification of 7% oil resistance).

Those skilled in the art recognize the need to balance the particle permeability across the filter with the resistance the filter is subjected to during filtration. It is also necessary to balance the higher initial alpha value with the alpha value after some filtering. The concentration of additive introduced as well as the nature of the additive used in the present invention can be varied to achieve optimum performance of the electret filter media.

The term “inside” as used herein refers to a state in which the melt-processible fatty acid amide is well dispersed in the fibers of the fiber cloth that makes the polymer fiber cloth. For example, melt-fabricable fatty acid amide can be thoroughly mixed with polymer resin into pellets which can be used to extrude fibers containing the amide in the fibrous structure. Those skilled in the art will recognize that fatty acid amides have been incorporated into polymers in various ways. In one example, the fatty acid amides can be combined using a twin screw extruder to make pellets with a concentrated amount of amides. The concentrated pellets may then be combined with the polymer pellets without the amide additive in an extrusion process that gives the desired polymer fiber fabric.

The filter efficiency and properties of the electret filter media of the present invention can also be optimized with further processing techniques. In one embodiment, the polymer fabric incorporating a charge stabilizing additive can be heat treated after the fabric is charged or a permanent dipole is generated. Heat treating the fabric at this stage of the manufacturing process can increase the charge stability of the resulting filter media. The heat treatment is usually about 65-about 230 ° C., preferably about 50-
At a temperature in the range of about 120 ° C, most preferably about 60 to about 90 ° C for about 15 seconds to about 5
Minutes, more preferably about 1 to about 2 minutes. Such post-charge heat treatment techniques are particularly useful for enhancing filter performance.

Preferably the heat treatment is applied to the electret filter tool after permanent dipole charging or formation. Although such heat treatment results in a low initial alpha, the alpha value after some loading of the filter tends to be higher than that achieved with the non-heat treated filter material. The heat treatment of the electret filter is a method known in the art,
For example, it can be achieved by using an infrared heater, a microwave heater, an oil or water heating roller, or a convection oven. Preferably, the heat treatment, e.g. annealing, is carried out by convection, so that a meltblown filter fabric having melt-fabricable fatty acid amides in the fabric can be uniformly annealed.

The post-charge heat treatment is carried out at a temperature in the range of about 65 to about 230 ° C., preferably about 50 to about 120 ° C., most preferably about 60 to about 90 ° C. for about 15 seconds to 5 minutes, preferably about. It is preferably carried out for 1-2 minutes. In general, fatty acid amides appear to be more sensitive to the effects of post-charge thermal treatment than other types of charge stabilizing additives. Thus it is preferred to subject the filter media to a post-charge heat treatment.

Methods of making plasma treated hydrophobic and / or oleophobic electret filter media are also part of this invention. In one embodiment, the present invention provides a hydrophobic and / or
Alternatively, it relates to the production of oleophobic plasma treated electret polymer media. The polymer fabric is treated with a plasma having hydrophobic and / or oleophobic reactive species, preferably a plasma containing hexafluoropropylene reactive species. The meltblown polymer fiber fabric is treated to produce a substantially permanent charge pair or dipole in the meltblown polymer fabric. This permanent dipole has A
It can be applied to the fabric by a variety of techniques including C corona or DC corona discharge and combinations thereof. In a preferred embodiment, this method of manufacture can be modified by heat treating, for example annealing, the polymeric fabric.

In another embodiment, the method comprises making an electret filter media by providing a meltblown-polymer-fiber cloth having charge-stabilizing fatty acid amides incorporated into the fibers. The polymer fabric is treated with a plasma having hydrophobic and / or oleophobic reactive species, preferably a plasma containing hexafluoropropylene reactive species. The plasma treated fabric is exposed to an AC and / or DC corona discharge to produce a substantially permanent charge pair or dipole in the meltblown polymer fabric. Typically, the fatty acid amide is present in the range of about 0.01 to about 20%. In a preferred embodiment, the manufacturing process can be modified by heat treating, for example annealing, the polymeric fabric.

One useful technique for treating the electret fabric of the present invention is illustrated in FIG. As illustrated, the filter media can be made, for example, in extruder 16 by producing a meltblown polymer film fabric from polymer resin 12, such as polypropylene. This resin has an additive 14 for stabilizing the electric charge,
For example, fatty acid amides are optionally included in concentrated form as described above. The resulting fabric 18 is formed by stretching the fibers, for example, in a ratio of about 300: 1 to produce a processing station.
It can be made thinner with the (tion) 20. Then, the cloth is used at any time (AC discharge device, D
Subjected to station 22 discharge treatment, which may be a C discharge device, or a combination thereof, to produce a substantially permanent charge pair or dipole in the meltblown polymer fabric. In some cases, in station 22, it is preferred to use an AC corona discharge device followed by a DC corona discharge. Alternatively, charging may be accomplished using AC corona discharge followed by treatment with one or more continuous DC discharge devices. Charging can also be achieved using other techniques, including friction-based techniques. The charged or uncharged fabric is plasma treated at station 24. The plasma treated electret fiber cloth is then subjected to one or more treatments using AC and / or DC corona discharge in station 26.

After producing and charging the electret filter media, the media can be subjected to heat treatment at station 28, as described above, to improve the charge retention of the media. For example, the heat treatment may be performed at a temperature in the range of about 60 to about 90 ° C for about 1-2 minutes.

It should be appreciated that various process combinations are possible to obtain the desired plasma treated electret polymer fabric. That is, the plasma grafting may be performed after the annealing step; the corona discharge treatment may be performed after the annealing step; the corona discharge may be performed before the plasma treatment; and / or the annealing step. May be performed prior to either plasma treatment and / or corona discharge treatment. Preferably, the polymeric fiber fabric, with or without charge stabilizing agents, is plasma treated, then AC and / or DC corona discharge, and then subjected to a final annealing step.

[0076]   The following examples serve to further describe the invention.

Examples Control Example 1, shown in Table I, is a sample of J & M Laboratories (Laboratories, Da.
A polypropylene meltblown filter fabric made with equipment made from Wsonville, GA) was evaluated. The meltblown was made from Exxon 3546G polypropylene resin containing 1% Acrawax C from Lonza. The meltblown fiber fabric was a 74 inch wide fabric with an average fiber diameter of about 3 microns and a yield of about 3 pounds / hour / inch wide. The fabric was made on a lightweight polypropylene spunbound for support. And this cloth is Simco
Co) and charged with two charging bars and two high voltage supplies. Charging was done at 60 feet / minute. One charged bar was treated on the fabric at -26 kV, 2.2 mA. The other charged bar was treated under +28 kV, 1.4 mA under the cloth. After charging, the sample was DOP loaded.

The test used to determine if the treatment was acceptable was to apply about 1 ml of DOP or mineral oil droplets across the width of the fabric. The treatment was determined to be acceptable when the droplets remained indefinite (due to the treatment) on the fabric surface. If the fabric sample was not properly treated, the droplets would have penetrated into the fabric immediately (untreated polypropylene) or within 5 minutes.

Example 1-A meltblown fabric was prepared under the same conditions as Control Example 1. After the melt-blow production, a 36-inch fiber cloth was plasma-treated under a process gas of hexafluoropropylene containing no carrier gas under 3 lpm. This plasma is 200
It was generated with 0 watts of RF power. The fabric was treated at 15 fpm to give a 1 minute exposure time to the plasma gas. The uniformity of the plasma treatment was evaluated by using mineral oil as described above. It should be noted that, as shown in Table I, Example 1 had alpha performance throughout the test that Control Example 1 reached about 20 minutes after loading.

Example 2-Melt-Blow Fiber Fabric Example 1 (Melt-Blow and Plasma Treated)
Manufactured as in. A 36 inch plasma treated meltblown fiber fabric was then charged under the same conditions as Control Example 1 and then tested against DOP loading. As shown in Table 1, the initial performance values were the same as in Control Example 1, but the alpha reduction was very small.

[0081]

[Table 1]

Examples 3-7 (Tables II, III and IV) -The material samples prepared in Example 2 are
It was placed in a furnace at the temperatures indicated in I, Table III and Table IV and then tested against DOP loading. As a result, it was discovered that heat treatment reduced the initial alpha and smoothed the alpha-decrease curve. Example 5 (150 ° F) had a fairly "flat" DOP alpha curve over a 30 minute load (24 minutes corresponded to the 200 mg load required for the NIOSH mask). It was found that as the heat treatment was increased, the alpha performance decreased and was therefore unsuitable for filter performance.

[0083]

[Table 2]

[0084]

[Table 3]

[0085]

[Table 4]

Example 8 (ah) (Table V) -Sample of Example 2 (plasma treated, charged)
It heated with the manufacturing apparatus (IR heating furnace). Furnace temperature at a line speed of 15 fpm
A fabric temperature of 150 ° F (using temperature indicating tape) was set to be achieved. This gave a residence time in the furnace of approximately 45 seconds. Samples are stacked in 1-8 layers, then DO
P was loaded. Two laminates passed the conditions of P95, three laminates passed P99 and five laminates passed P100.

[0087]

[Table 5]

The pressure drop at mmH ₂ O is a measure of the breathability of a material, such as a facial mask. The lower the value, the lower the resistance of the air passing through the material. Many samples show that the treated textile fabric of the present invention has a very low pressure drop and can be used for a facial mask that is pleasing to the wearer.

Those of ordinary skill in the art will be able to ascertain and ascertain by no more than routine experimentation, examples that are equivalent to the particular embodiments of the invention described herein. These and all other equivalents are intended to be within the scope of the following claims. All printed materials and references cited herein, including in the background of the invention, are hereby incorporated by reference in their entirety.

[Brief description of drawings]

FIG. 1 is a flow sheet illustrating a method for producing a plasma-treated electret filter medium of the present invention.

[Procedure for Amendment] Submission for translation of Article 34 Amendment of Patent Cooperation Treaty

[Submission date] September 18, 2001 (2001.18)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Contents of correction]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Contents of correction]

Electret filter material is made by a variety of known techniques. One electret filter media manufacturing technique typically involves extruding a polymer with a high melt flow index through a linear array of orifices. An air knife is used to thin the extruded polymer fibers at a ratio of about 300: 1. The thinned fibers, about 1-10 microns in diameter, are collected on a rotating drum or moving belt by applying a suitable vacuum. The fabric is then treated to impart charge pairs or dipoles on the fabric. This charge pair or dipole can be applied to the fibers using, for example, AC and / or DC corona discharge. See, for example, Bruno - Ma down-Rifushuttsu (Norman Lifshutz) U.S. Pat. No. 56,456 No. 27, "charge stabilized electret filtration device media."

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Contents of correction]

When treating polymer-fiber fabrics with plasma, it is not necessary for the plasma treatment to be uniform in all. A thin plasma treatment layer, typically on the order of 5 nanometers (nm) , is sufficient for some applications. However, in order to obtain a uniform layer, the layer generally has a thickness of at least 50 nm and a thickness of about 1
Will be in the micron range. The exact thickness of the applied layer will vary with the size and composition of the fabric being treated, the composition of the layer applied, and the extent to which the fabric is exposed to primary plasma or plasma active species.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0042

[Correction method] Change

[Contents of correction]

In operation, polymer-fiber fabrics, with or without charge stabilizing agents, generally have a stable base pressure of about 0.01-, depending on the composition of the untreated fabric material. Place in a chamber degassed to about 760 Torr (atmospheric pressure), preferably about 0.05 to about 0.15 Torr. The operating pressure is generally about 0.01-using a vacuum pump.
It is maintained at 10.0 Torr, more preferably about 0.01-1.0 Torr. The flow rate of the ionizable gas is maintained at about 1-100 liters / minute (lpm), more preferably about 0.1-about 10 lpm is established and maintained. Alternatively, gas flow can be determined in lpm per width meter of fabric material. Suitable processing range in the case of using these units, 3.28-65.6Lpm / width meter, more rather preferably about 6.56- about 65.6Lpm / width main - Torr, and most preferably 9.84lp m / width meter.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0043

[Correction method] Change

[Contents of correction]

RF energy is supplied and used to generate a plasma of ionizable gases and plasma-active species in the process chamber, and more particularly in the process zone. Typically, the gas pumped to the process chamber comprises a carrier gas such as helium and a reactive gas such as a monomer. The supply of RF energy is typically about 50-
It provides power in the range of about 5000 Watts, more preferably about 500 to about 3000 Watts. Alternatively, power can be determined by the width meter of watts / cloth material. A suitable processing range when using these units is 328 to about 3280 watts / width meter , preferably about 1640 to about 2460 watts / width meter , and most preferably about 2130 watts / width meter. is there.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0044

[Correction method] Change

[Contents of correction]

The polymer - cloth, about 0.305 (main - Torr / minute (mpm)) - about 30.5, like municipal district is about 4.57- about 9.14mpm, is supplied to the plasma processing chamber. These factors can be widely varied as the size of the device is adapted to higher production volumes. As the cloth width increases, the pressure, flow rate, and power values of the ionizable gas will have to be scaled up correspondingly. For example, the rate depends on the reactor design, such as power and electrode area. The preferred speed used to make the fabric of the present invention is a residence time in the plasma chamber of 45 seconds -1.
It was a minute.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0046

[Correction method] Change

[Contents of correction]

The polymer - cloth, Ru can be made to have the electret further processing. For producing et les <br/> Kutoretto filtration device medium, polymers with dipole permanent - Various techniques for applying the fabric is well known. This charging can be done using AC and / or DC corona discharge and combinations thereof. The characteristics of the discharge used are
It depends on the shape of the electrodes, the bipolar nature, the size of the gap and the gas or gas mixture. In one embodiment, charging can be achieved simply using an AC corona discharge device. In yet another embodiment, it is useful to use both AC and DC corona discharge devices.
In the preferred technique, the polymer fabric is first subjected to an AC corona discharge and then treated with one or more continuous DC corona discharge devices. Charging can also be accomplished using other techniques, including friction-based charging techniques. Typically, the fiber cloth is about 1-
Subject to a discharge of about 30 kV (form of energy, eg DC or AC discharge) / cm, preferably about 10 to about 30 kV / cm, suitably about 10 to about 20 kV / cm.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0068

[Correction method] Change

[Contents of correction]

The filter efficiency and properties of the electret filter media of the present invention can also be optimized with further processing techniques. In one embodiment, the polymer fabric incorporating a charge stabilizing additive can be heat treated after the fabric is charged or a permanent dipole is generated. Heat treating the fabric at this stage of the manufacturing process can increase the charge stability of the resulting filter media. The heat treatment is usually at a temperature in the range of about 338K-about 503K, preferably about 323K-about 393K, most preferably about 333K-about 363K .
It can be performed for about 15 seconds to about 5 minutes, more preferably for about 1 to about 2 minutes. Such post-charge heat treatment techniques are particularly useful for enhancing filter performance.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Name of item to be corrected] 0070

[Correction method] Change

[Contents of correction]

The post-charge thermal treatment is carried out at a temperature in the range of about 338K-about 503K, preferably about 323K-about 393K , most preferably about 333K-about 363K for about 15 seconds-5 minutes, preferably about 1-. It is preferably performed for 2 minutes. In general, fatty acid amides appear to be more sensitive to the effects of post-charge thermal treatment than other types of charge stabilizing additives. Thus it is preferred to subject the filter media to a post-charge heat treatment.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0074

[Correction method] Change

[Contents of correction]

After producing and charging the electret filter media, the media can be subjected to heat treatment at station 28, as described above, to improve the charge retention of the media. For example, the heat treatment may be performed at a temperature in the range of about 333K to about 363K for about 1-2 minutes.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0077

[Correction method] Change

[Contents of correction]

Examples Control Example 1, shown in Table I, is a sample of J & M Laboratories (Laboratories, Da.
A polypropylene meltblown filter fabric made with equipment made from Wsonville, GA) was evaluated. The meltblown was made from Exxon 3546G polypropylene resin containing 1% Akrawax C from Lonza. The meltblown fiber cloth was a cloth having a width of 1.88 meters with an average fiber diameter of about 3 microns and a production amount of about 53.5 kg / hour / width meter. The fabric was made on a lightweight polypropylene spunbound for support. The fabric was then charged using two charging bars from Simco and two high voltage feeders. Charging was performed at 18.3 meters / minute. One charging bar is -26kV, 2
． The fabric was treated with 2 mA. The other charged bar was treated under +28 kV, 1.4 mA under the cloth. After charging, the sample was DOP loaded.

[Procedure Amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0079

[Correction method] Change

[Contents of correction]

Example 1-A meltblown fabric was prepared under the same conditions as Control Example 1. After the melt-blow production, a 0.914- meter fiber cloth was plasma-treated under a process gas of hexafluoropropylene containing no carrier gas at 3 lpm. The plasma was generated with RF power of 2000 watts. The fabric was treated at 4.57 mpm to give a 1 minute exposure time to the plasma gas. The uniformity of the plasma treatment was evaluated by using mineral oil as described above. It should be noted that, as shown in Table I, Example 1 had alpha performance throughout the test that Control Example 1 reached about 20 minutes after loading.

[Procedure Amendment 13]

[Document name to be amended] Statement

[Correction target item name] 0080

[Correction method] Change

[Contents of correction]

Example 2-Melt-Blow Fiber Fabric Example 1 (Melt-Blow and Plasma Treated)
Manufactured as in. A 0.914 meter plasma treated meltblown fiber fabric was then charged under the same conditions as Control Example 1 and then tested against DOP loading. As shown in Table 1, the initial performance values were the same as in Control Example 1, but the alpha reduction was very small.

[Procedure Amendment 14]

[Document name to be amended] Statement

[Correction target item name] 0082

[Correction method] Change

[Contents of correction]

Examples 3-7 (Tables II, III and IV) -The material samples prepared in Example 2 are
It was placed in a furnace at the temperatures indicated in I, Table III and Table IV and then tested against DOP loading. As a result, it was discovered that heat treatment reduced the initial alpha and smoothed the alpha-decrease curve. Example 5 ( 339k ) was fairly "through the load of 30 minutes (24 minutes corresponded to the 200 mg load required for the NIOSH mask).
It had a "flat" DOP alpha curve. It was found that as the heat treatment was increased, the alpha performance decreased and was therefore unsuitable for filter performance.

[Procedure Amendment 15]

[Document name to be amended] Statement

[Correction target item name] 0086

[Correction method] Change

[Contents of correction]

Example 8 (ah) (Table V) -Sample of Example 2 (plasma treated, charged)
It heated with the manufacturing apparatus (IR heating furnace). The furnace temperature was set to achieve a fabric temperature of 339K (using temperature indicating tape) at a line speed of 4.57 mpm . This gave a residence time in the furnace of approximately 45 seconds. Samples are stacked in 1-8 layers, then DO
P was loaded. Two laminates passed the conditions of P95, three laminates passed P99 and five laminates passed P100.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), OA (BF, BJ , CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, K E, LS, MW, MZ, SD, SL, SZ, TZ, UG , ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, BZ, C A, CH, CN, CR, CU, CZ, DE, DK, DM , DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, K E, KG, KP, KR, KZ, LC, LK, LR, LS , LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, RO, R U, SD, SE, SG, SI, SK, SL, TJ, TM , TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW

Claims (28)

[Claims] 1. A filter media comprising a meltblown oleophobic plasma treated electret polymer fiber cloth. 2. The filter media of claim 1, wherein the oleophobic plasma treatment is an oleophobic alkylene, acrylate, or methacrylate. 3. The filter media of claim 2, wherein the oleophobic alkylene, acrylate, or methacrylate is halogenated. 4. The filter media of claim 3, wherein the halogen is fluorine. 5. The filter media of claim 3, wherein the alkylene halide is hexafluoropropylene. 6. The filter media of claim 1, wherein the filter media has a filter efficiency and degradation value of at least P95. 7. The filter media of claim 1, wherein the polymeric fiber fabric comprises polymeric fibers having a diameter in the range of about 1-20 μm. 8. The filter media of claim 1, wherein the weight of the polymer fiber fabric is in the range of about 10 to about 520 g / m ² . 9. The filter media of claim 1, wherein the fiber cloth is annealed. 10. A gas mask having a filter element comprising the meltblown oleophobic plasma treated electret polymer filter cloth of claim 1. 11. A gas mask having a filter element comprising the annealed, melt-blown oleophobic plasma treated electret polymer filter cloth of claim 9. 12. A melt-blown oleophobic plasma treated electret polymer wherein a melt processible fatty acid amide is present in the fabric, provided the concentration of said amide is in the range of about 0.01 to about 20% by weight. A filter media comprising a fiber cloth. 13. The oleophobic plasma treatment comprises oleophobic alkylene, acrylate.
13. The filter medium according to claim 12, wherein the filter medium is a sheet or a methacrylate. 14. The oleophobic alkylene, acrylate, or methacrylate.
14. The filter media of claim 13, wherein the filter is halogenated. 15. The filter media of claim 14, wherein the halogen is fluorine. 16. The filter media of claim 14, wherein the alkylene halide is hexafluoropropylene. 17. The filter media of claim 12, wherein the filter media has a filter efficiency and degradation value of at least P95. 18. The filter media of claim 12 wherein said polymeric fiber fabric comprises polymeric fibers having a diameter in the range of about 1-20 μm. 19. The filter media of claim 12, wherein the weight of the polymer-fiber cloth is in the range of about 10 to about 520 g / m ² . 20. The filter media of claim 12, wherein the fiber cloth is annealed. 21. A gas mask having a filter element comprising the meltblown oleophobic plasma treated electret polymer filter cloth of claim 12. 22. A gas mask having a filter element comprising the annealed, meltblown oleophobic plasma treated electret polymer filter cloth of claim 20. 23. A meltblown polymer fiber fabric is provided, the meltblown polymer fabric is treated with an oleophobic plasma, and the plasma treated fabric is treated to provide a substantially permanent charge pair or bipolar electrode. A melt-blown oleophobic plasma treated electret filtration comprising the steps of: forming a child in the plasma treated meltblown polymer cloth, thereby producing a meltblown oleophobic plasma treated electret filter media. Manufacturing method of ingredient medium. 24. The method of claim 23, wherein the oleophobic plasma comprises hexafluoropropylene. 25. The method further comprising the step of treating the oleophobic plasma treated electret polymer cloth at elevated temperature, thereby annealing the resulting meltblown oleophobic plasma treated electret filter media. Claim 23
the method of. 26. A meltblown-polymer fiber fabric having a charge stabilizing fatty acid amide incorporated into the fiber is provided, the meltblown polymer fabric is treated with an oleophobic plasma, and treated with the oleophobic plasma. The fabric is treated to produce substantially permanent charge pairs or dipoles in the meltblown polymer fabric, whereby charge-stabilizing fatty acids are present in the fabric. An oleophobic plasma treated electret filtration. A method of making an electret filtration tool medium having a charge stabilizing fatty acid amide, the method comprising the step of producing a tool medium. 27. The method of claim 26, wherein the hydrophobic plasma comprises hexafluoropropylene. 28. The method further comprising the step of treating the oleophobic plasma treated electret polymer fabric at elevated temperature, thereby annealing the resulting meltblown oleophobic plasma treated electret filter media. 27. The method of claim 26, wherein