Patent Application
20090259158
The present invention relates to filter media with iodinated resin incorporated therein, and a method of making the same.
Iodine/resin demand disinfectants are known in the art. For example, U.S. Pat. No. 5,369,452 (“the '452 patent”), to Messier, the entire contents which are hereby incorporated by reference, describes a process for preparing an iodine demand disinfectant resin from an anion exchange resin. The demand disinfectant iodinated resins described in the '452 patent may be in the form of a powder (i.e. Triosyn® T-50 powder) or may be in the form of a bead (i.e. Triosyn® T-50 beads). The iodine demand disinfectant resins described in the '452 patent have a low iodine bleed characteristic since the iodine is tenaciously associated with the resin. As a result, the iodinated resins can be used in various applications as a disinfectant without the concomitant risk of leaching substantial iodide into the environment causing a high level of toxicity.
For example, antimicrobial filters can be made by incorporating an iodinated demand disinfectant in a filter media. The antimicrobial filter media can be used to retain and deactivate a large array of microorganisms. Such filter media have the advantage that the deactivated microorganisms are not released back into the environment after being used. As used in this application the term “antimicrobial filter media” includes any media that has an antimicrobial and filtering effect. Thus, these media can be used for filters per say but can also be use in making wound dressings, clothing and other useful products.
Several methods of incorporating an iodinated resin in a filter media have been described in the prior art. For instance, U.S. Pat. No. 6,224,655 discloses adhering particles of an iodinated resin to the filter media's surface with an adhesive or physically entrapping the particles in the three dimensional matrix structure of the filter media. In published U.S. patent application number 20010045398 entitled “Process For The Immobilisation Of Particles In A Three Dimensional Matrix Structure” the filter media is first produced and then an iodinated resin, is added using alcohol or a partial solvent with a high pulsation vacuum pump that opens the filter media's pores so that the iodinated resin will be physically entrapped therein.
Despite the advantages of these prior art iodinated filter media, there still exists a need to develop highly efficacious antimicrobial filter media that exhibit an even lower toxicity then the prior art iodinated filters.
In accordance with one aspect of the present invention, there is provided a fiber with iodinated resin particles embedded therein.
In another aspect of the present invention, there is provided a filter media made from the fibers which have the iodinated resin particles embedded therein
In yet another aspect of the present invention, there is provided a filter media made from the fibers which have the iodinated resin particles embedded therein and are electrostatically charged.
In addition to the above aspects of the present invention, additional aspects, features and advantages will become better understood with regard to the following description in connection with the accompanying drawings.
The following sections describe exemplary embodiments of the present invention. It should be apparent to those skilled in the art that the described embodiments of the present invention provided herein are illustrative only and not limiting, having been presented by way of example only. All features disclosed in this description may be replaced by alternative features serving the same or similar purpose, unless expressly stated otherwise. Therefore, numerous other embodiments of the modifications thereof are contemplated as falling within the scope of the present invention as defined herein and equivalents thereto.
The present invention comprises antimicrobial fibers that are embedded with a demand disinfectant iodinated resin. It has been found that embedding an iodinated resin into a fiber imparts excellent properties to the fiber which are ideal for the production of biocidal nonwoven and woven articles. Iodinated resin powder can be extruded with various polymers to generate fibers with embedded iodinated resin. These polymers include but are not limited to polypropylene, polyethylene, PBT, nylon, polycarbonate, poly(4-methyl pentene-1), polylactic acid, and polystyrene.
It has further been found, surprisingly, that when the iodinated resin is embedded in the fiber, the amount of iodine that is released into the environment is substantially less than the amount of iodine released when the iodinated resin is in ‘free’ powder form, and hence not associated with a fiber. Moreover, when the fibers with embedded iodinated resin are incorporated into a filter media, the resultant filter leaches negligible amounts of iodide and is thus not toxic. For example, filter media made from a nonwoven material comprising fibers with embedded iodinated resin release less iodine into the environment then when the iodinated resin particles are physically adhered to the nonwoven substrate or introduced into the three-dimensional matrix of the substrate. Accordingly, the innovative nonwoven filters have much broader applicability when compared to antimicrobial nonwoven filters in the prior art.
In a particular embodiment, the filer media may be made from a fiber based material having a fibrous matrix structure; it may be a sponge like material have an open cell matrix structure; it may be flexible or inflexible; etc.
As stated above, in one embodiment, the filter media is a nonwoven fabric. Nonwoven is a type of fabric that is bonded together rather than being spun and woven into a cloth. It may be a manufactured sheet, mat, web or batt of directionally or randomly oriented fibers bonded by friction or adhesion; it may take the form of a type of fabric.
In another embodiment, the filter media may be a nonwoven textile of varying fluffiness, comprising polymer fiber. The polymer may be for example, nylon, polyethylene, polypropylene, polyester, PBT, nylon, polycarbonate, poly (4-methyl pentene-1), polylactic acid, polystyrene or any other polymer suitable for a filter substrate. Additionally, the filter media can be made of materials other than polymer fiber.
The nonwoven material may be of a type suitable for a high efficiency particulate air filter (i.e. a HEPA filter). A suitable nonwoven material may be obtained from Technol Aix en Provence Cedex 03 France (see Canadian patent no. 1,243,801); another suitable material may also be obtained from Minnesota Mining & Manufacturing Co. (3M). The nonwoven material has a three-dimensional structure which should be configured in such a fashion as to provide a matrix capable of entrapping (i.e. physically) the desired active agent. For example if the nonwoven material is based on fibers, the structural fibers of the nonwoven material may be present and distributed in such a fashion as to provide a fibrous matrix structure able to entrap the desired active. In a particularly preferred embodiment, the fibers constituting the nonwoven have the active agent (e.g., iodinated resin) incorporated thereto. Accordingly, the active agent is embedded within the fibers themselves as opposed to occupying the interstitial regions formed from the bonded fibers. Alternatively, the iodinated resin particles may be embedded in the fiber and be physically entrapped within the three-dimensional matrix of the nonwoven material.
Alternative substrates may further include glass fibers and fibers, such as cellulose, that are ultimately formed into a paper-based filter media. Any substrate capable of acting as carrier for the active agent and having dielectric properties or capable of having dielectric properties imparted to it, would be a suitable substrate for the present invention. When substrates that do not have strong dielectric properties are used, such as glass fibers, additives may be provided to improve the dielectric properties of the substrate. The present invention is not limited to a nonwoven material. Other suitable substrates may include spongy materials or foam.
The active agent of the present invention may be, for example, an antimicrobial, an antitoxin, or the like. The antimicrobial may be biostatic and/or biocidal. Biostatic is a material that inhibits the growth of all or some of bacteria spores, viruses, fungi, etc. (having bioactive particles), and a biocidal is a material that kills all or some of bacteria spores, viruses, fungi, etc. Preferably, the biocidal comprises the demand disinfectant iodinated resin particles, such as those disclosed in the '452 patent. The demand disinfectant iodinated resins described may be in the form of a powder (i.e. Triosyn® T-50 powder) or may be in the form of a bead (i.e. Triosyn® T-50 beads). Owing to its ability to be incorporated into a molten mixture of polymer granules, the iodinated resin powder is particularly preferred
In a particularly advantageous embodiment, the filter media with an active agent incorporated thereto is also electrostatically charged. Accordingly, there is a potential across the surface(s) of the media creating a field wherein the field can attract and/or repel charged particles introduced to the media so that in some instances it alters the path of travel of the charged particles. Various methods can be used to incorporate an electric charge into the substrate. The charge may be induced by using a corona, needle punching, chemical enhancement, any other known charge inducing system or method, or a combination of any of the foregoing. Needle punching creates high-level friction thus adding a charge.
In a particular embodiment, to make the electrostatically charged non-woven fabric the formed media, such as felt, is placed into a corona system of about 25Kv, slow pass, until fully charged. The resulting material holds its charge for between about 6 months to 2 years.
Preferably, a high dielectric constant is provided to maintain the charge for an extended period of time. For example, air provides a good dielectric constant, as can be employed in an airspace as described above. Thus, the present invention may be effective even when wet or in a humid environment.
The resulting filter media is an insulating carrier with the active agent embedded in the fibers comprising the media. The media according to the present invention can be produced of different thickness, density and pressure drop. The media described herein can be used in, for example: clothing, wound dressings, air filters, shelters, liners and generally, any filter material.
The present invention additionally provides for a method of manufacturing the electrostatically charged filter media having an active agent incorporated thereon. The substrate itself may be manufactured according to various known methods, such as melt blown, spun blown, air laid, carted, etc. A suitable melt blown system for the above embodiment is the Accuweb provided by Accurate Products Co. of Hillside, N.J.
Prior art incorporation methods using polypropylene require the use of polyethylene to maintain a tackiness to the fibers to hold the solid particulate for a longer amount of time to prevent the particulate from falling off the fibers. In the present invention, the active agent, such as the iodinated resin disclosed in the '452 patent, are embedded in the fibers. Thus, the active agent does not have to adhere to the fibers to be incorporated into the media.
In the present invention, the active agent may be incorporated to the substrate according to various methods. For example, liquid emulsification of the active agent in the melt at increased temperature and increased pressure for mix and melt processes, or incorporation by spraying the active agent after extrusion of non-woven fibers during processing.
Various other methods of embedding the active agent in the fibers of a filter media are also suitable for the present invention. First, soaking a bail of hair-like extruded fibers in an active agent (and using alcohol to achieve the soak) and then creating the felt using pressure and temperature. Second, taking solid polymer granules manufactured with an active agent mixed in an extruder hopper to create a mixture that is then extruded into fine hair-like bails. Felt is then formed through a temperature and pressure process. Third, extruding a substrate, such as a polymer in to a hair-like substance on to which an active agent is sprayed in solid after the extrusion. The active agent may be vaporized like an aerosol. Fourth, the active agent can be injected or sprayed into non-woven fabric as the fabric is being pressurized. Fifth, carting bails of filament and mixing the resulting media with the active agent to generate a sheet having the active agent incorporated therein.
As discussed above, embedding the iodinated resin particles in the fibers of a nonwoven differs from prior art methods where resins are physically entrapped within the three-dimensional matrix of the nonwoven filter media.
In certain embodiments according to the present invention, it may be convenient to extrude a very thin fiber with a diameter less than the diameter of the iodinated resin particulates.
In another embodiment of the present invention, polymer granules are placed in a hopper of an extruder with active agent in dust form prior to extrusion. Thus, the active agent is mixed in the hopper prior to the melt. The two components are mixed, heated and then extruded to form a thin “hair” fiber used to make a felt. The resulting hair in the above embodiments having the active agent incorporated thereto is a bail-like wool. The substrate could be transparent depending on the polymer used. Additionally, a resulting polymer fiber having the active agent incorporated thereto can be treated with water, pressurized and then heated to form a felt. In other embodiments, the resulting polymer fiber having the active agent incorporated thereto can an be air laid, vacuum laid, water laid, etc.
In operation, a contaminated air or fluid stream is introduced to a filter employing the electrostatically charged filter media of the present invention. The air/fluid stream may be forced or drawn through the filter media by means of a pressure gradient. The stream may contain contaminant particles of various sizes to be removed or treated by the filter element. As the stream approaches the filter media, it is directed through the filter media such that the contaminate particles are brought into contact with the filter media and removed from the stream or treated by the active agent as describe elsewhere in this application. This is achieved through the properties of the filter, which causes the particles to follow a convoluted pathway through the filter element, thus increasing the time that the contaminant is in contact with the active agent. This increased contact time increases the effectiveness of the active agent in treating the particles in the stream.
The convoluted path that the particles follow is the result of the added electrostatic properties and the nonwoven properties of the substrate of the filter element. With respect to the electrostatic properties of the filter element, the convoluted pathway of the contaminant particles may be attributed to the particles polar nature. Polar molecules are neutrally charged and are also large in size. Because of the large size, the contaminants have a magnetic moment, which when subjected to an electric field causes the contaminant particle to be diverted from its pathway.
Additionally, the convoluted path of the contaminant particles is attributable to the nonwoven properties of the filter substrate. This is achieved because the nonwoven substrate had no direct and continuous pathway for the stream to pass through. Instead, due to the nonwoven properties, the substrate is made up of a porous material wherein no single pores of the material forms a continuous pathway through the substrate. Therefore, the stream and the particles carried by the stream are continuously diverted through the substrate.
Accordingly, the travel time through the filter is lengthened and the exposure to the active agent is increased.
The present invention can also be used in a manner consistent with existing nonwoven and woven fabrics. Uses in various goods include both durable and disposable goods. For example, nonwovens can be used products such as diapers, feminine hygiene, adult incontinence, wipes, bed linings, automotive products, face masks, air filtration, water filtration, biological fluids filtration, home furnishings and geotextiles. The media described herein can also be used in, for example: clothing, wound dressing, air filter, shelters, and liners. Additional uses include those known in the art for electrostatic filters and antimicrobial or antitoxin filters.
1.) Summary of Method
Triosyn® T-50 powder was added to a linear low density polyethylene (LLDPE) polymer and it was extruded into a fiber. A series of tests were established to compare the properties of Triosyn® (free powder) to a Triosyn®/LLDPE fiber. More specifically, the same quantity (mass) of Triosyn® T-50 powder was applied to both the LLDPE polymer as on a blank swatch of 20-XZPN to hold the Triosyn®/fiber and Triosyn powder. Note that the 50% of the mass of the total weight of the Triosyn®/LLDPE fiber is composed of Triosyn powder, (that is, 50% w/w). Both were placed into a media sandwich of blank 20-XZPN and were air filtration tested to observe the iodine release kinetics. The two swatches contained identical quantities of Triosyn® T-50 powder. The goal was to determine whether the samples would have the same iodine release profile. This quantitative test method is designed to evaluate the iodine release of test articles under an 8 hour work shift and under normal use conditions at the same flow rate.
2.) Detailed Description of Method
Prototype samples are fitted into filter holders and drilled tightly closed, attached to the sampling ports, while one sampling port is kept vacant in order to determine the iodine concentration of the challenge air stream from the chamber. Air is then passed through each sample at the desired flow rate and the quantity of iodine released is determined based on the OSHA standard protocol (Occupational Safety and Health Administration (OSHA) Iodine in Workplace Atmospheres ID#212, 1994). This test method is performed to quantify the iodine release from Triosyn® coated 12.57 cm2 swatches. A High Performance Liquid Chromatograph (HPLC) equipped with an amperometry detector is used to obtain a quantifiable analysis of the iodide ions with the detection limit in the range of 0.008 to 0.0012 ppm iodide (1.3×10-3 mg/m3 to 1.9×10-3 mg/m3).
Sampling ports are connected to midget All-Glass Impingers (AGIs) containing an iodine trapping solution. A vacuum pump is employed to draw the air stream through the test articles and into the midget AGIs at a specified flow rate. The iodine released from the full devices is collected as iodide by the trapping solution contained in the midget AGIs.
A sample of 0.0551 g LLDPE containing 50% w/w Triosyn® T-50 powder (10 μm) was applied onto a blank swatch of 12.57 cm2 20-XZPN. This was covered by a second swatch of the blank 20-XZPN. This was then fitted into a filter holder fabricated for such purposes, closed and placed on the rig for the iodine release kinetics testing.
A second sample was next prepared with the same swatch size, however, 0.0274 g of Triosyn® T-50 powder (10 μm) was applied directly to the blank 20-XZPN, then covered with a blank 20-XZPN. This was then fitted into a filter holder for such purposes, closed and placed on the rig for the iodine release kinetics testing. This sample will serve as the control for this test.
Samples of size 12.57 cm2 are air filtration tested at a flow rate of 5.4 Liters/minutes (LPM). This flow was determined based on the NIOSH (42 CFR (Code of Federal Regulations) Part 84 Approval of Respiratory Protective Devices) recommended flow rate of 85.0 Liters/minute (LPM) for the full device.
A sampling flow rate of 0.5 LPM is used as recommended by the OSHA (Occupational Safety and Health Administration (OSHA). Iodine in Workplace Atmospheres ID#212, 1994).
3.) Testing Procedure
The method used was developed by the Dionex Corporation and validated by Triosyn Research. The HPLC is equipped with an electrochemical integrated amperometry method using an Ag/AgCl reference electrode.
The eluent is composed of 25% 250 mM sodium hydroxide solution and 75% high purity water (4 pressurized eluent bottles) previously vacuum filtered on 0.2 μm nylon filters. The high purity water is degassed prior to use and prior to preparing the basic solution.
The sample analysis is based on the injection of potassium iodide standards using a quadratic equation and the peak areas to obtain the standard curve. The standards that are regularly made are 0.001, 0.0015, 0.0020, 0.005, 0.010, 0.05, 0.100, 1.00 and 1.25 parts per million (ppm) potassium iodide in the trapping media (1.5 mM NaHCO3/Na2CO3). These are made in 100 mL volumetric flasks, from a 1.0 L 100 ppm potassium iodide stock solution in high purity water. A 0.000 ppm standard must also be prepared of the trapping media alone. The standards are stable for 1 month. The samples are analyzed at ambient temperature at a flow rate of 1.5 mL/min with a run time of 5 minutes. Iodide peaks are seen at approximately 2.5 minutes.
An IonPac AS11 Guard column is used in line with an IonPac AS11 Column. The injection volume is 100 μL and the peak retention time is approximately 2.2 minutes for iodide. Columns are changed on a monthly basis. When a column is changed, it is important to start a new sequence with 3 standard curves as well as repeat injections of each standard (2 vials of each standard injected 3 times each). This is a means to monitor stability and reproducibility. Columns that are not in use are stored in 100 mM sodium hydroxide and allowed to equilibrate until needed.
The Detection limit is 1.6×10-3 mg/m3 of iodine which translates into 0.0010 ppm of iodide. The need to have such a low detection limit is driven by the low levels of iodine measured during toxicological tests. Due to the low limit, the HPLC instrument must be continuously monitored for any loss of sensitivity and kept in very good condition. These means can be met by proper maintenance and a keen sense of the life-span of the consumable parts with prompt replacement as necessary.
4.) Calculations
The HPLC instrument is a highly sensitive instrument used to determine very low concentrations of iodide species. It is the only system that could read with great precision, very small amounts of iodide species. The iodine content is calculated from the iodide measured using the following equations as per OSHA #ID-212 standard protocol.
The total amount of iodine in units of mg/m3 is determined using Equation 1 below:
Conc. Of Iodide (mg/L)=Amount mg/L of Iodide from calibration curve of HPLC
Trapping media vol. (L)=Solution volume in impinger in Liters (0.0010 L in midget Impinger)
GF=Gravimetric factor=3 I2/5I−=6/5=1.2
Flow rate (LPM)=Flow of Air passing through impinger (LPM) (0.5 LPM)
Duration of Sampling (min)=Sampling time in minutes m3/1000 L=volume conversion
The total amount of iodine with units in mg comparable to the TUIL is determined from a summation of the iodine measure calculated above in mg/m3 per collection over 8 hours using Equation 2, below:
Iodine(mg)=Conc. Of iodide(mg/m3)×Breath. Rate(m3/hr)×Dur. Of sampling(min)×h/60 min EQUATION 2
Conc. Of Iodine (mg/m3)=Calculated from previous equation
Breathing Rate (m3/hr)=1.6 m3/hr as the breathing rate during moderate activity
Duration of sampling (min)=15 minutes per sampling
Thus, over 8 hours, if collections take place every 15 minutes, a total of 32 samples of iodine in trapping solution are injected on the HPLC for iodide analysis. From the concentration of iodide, the iodine in mg/m3 is calculated (refer to equation #1) per sample, then converted into mg of iodine (refer to equation #2). The sum of all 32 samples of iodine (mg) is then taken to obtain the total amount of iodine.
5.) Results
The results obtained for the iodine release kinetics testing are presented in Table 1.
Table 1 compares the amount of iodine released over an eight hour air filtration test between the Triosyn®-embedded fiber, which is a low density polyethylene (LLDPE) polymer (50% by mass) with embedded 10 micrometer Triosyn® T-50 powder (50% by mass), compared with iodine released from free Triosyn® T-50 powder (10 micrometers). The left side of the table shows the amount of iodine released by the Triosyn®-embedded fiber while the right side of the table shows the amount of Triosyn released from the free Triosyn® powder. The results reveal that the Triosyn®-embedded fiber releases significantly less iodide than the free Triosyn® T-50 powder. The amount of iodine released is almost 30-fold lower in the Triosyn®-embedded fiber than in the Triosyn® T-50 powder.
1.) Summary of Method
Triosyn® T-50 powder was added to a linear low density polyethylene (LLDPE) polymer and it was extruded into a fiber. The stagnation leach properties thus imparted to the Triosyn®/LLDPE fibers were then evaluated against the stagnation leach of the Triosyn® T-50 powder and Triosyn® T-50 resin beads.
2.) Detailed Description of Method
Stagnation leach testing is used as a quality control method to determine the quantity of iodine that leaches into high purity water (reverse osmosis, deionized) over a 48 hour test duration. This test is normally performed on the finished product of Triosyn® beads and is one of the control tests used to certify that the beads are acceptable for use in a range of products. In this case, the test was altered and applied to the Triosyn® powder loaded LLDPE compared to the control, Triosyn® T-50 beads and Triosyn® T-50 powder (10 μm). The results obtained will determine if absorption of the Triosyn® by the LLDPE is occurring and whether over 48 hrs, it will release the same concentration of iodine as its Triosyn® control.
3.) Testing Procedure
4.) Calculations
The stagnation leach standard curve was obtained using the following results presented in Table 2, and plotted on a standard curve. The absorbance for each sample is read on the spectrometer at 530 nm and 700 nm. The maximum absorbance of iodine is seen at 530 nm (top of peak) whereas 700 nm is located at the baseline. The final absorbance is obtained by subtracting A530 nm-A700 nm to obtain the true absorbance for iodine. T his is done because the baseline is not always located at zero absorbance due to shifts that may occur.
Calculations for the concentration of iodine in the samples were performed based on the following equation (Equation 3) obtained from the above standard curve:
y=(21.398x+0.7001)×df EQUATION 3
y=calculated concentration (ppm)
x=Absorbance measured
df=Dilution factor (in our case it was 5)
5.) Results
The results obtained from the Stagnation Leach test atr presented in Table 3. Note that each of the samples contain the equivalent amount of Triosyn®.
The results of a stagnation leach test, which are displayed in Table 3, shows the same trend as the iodide release kinetics study (Table 1). That is, significantly less iodine is released INTO the water solution with the Triosyn®-embedded fiber than with the free Triosyn® T-50 powder. The stagnation leech test was also performed with Triosyn® T-50 polymer resin beads (500 micrometer). Triosyn® T-50 resin beads are produced from strongly basic ion-exchange resin beads, through methods described in the '452 patent. The amount of iodine released was comparable between the Triosyn® T-50 resin beads and the Triosyn®-embedded fibers.
The results from the iodine release kinetic study and the stagnation leach test reveal that the fiber hinders the release of iodine in a Triosyn®-embedded fiber relative to Triosyn® in free powder form. Moreover, the Triosyn®-embedded fiber is capable of holding the iodine to a similar extent to the intact Triosyn® resin beads. These results are applicable to the production of nonwoven and woven articles with antibacterial properties. Such materials must have a high degree of antimicrobial efficiency (high kill-rate) while at the same time minimizing the amount of iodine that leaches into the environment.
1.) Summary of Method
Triosyn® T-50 powder was added to a linear low density polyethylene (LLDPE) polymer and it was extruded into a fiber. The antimicrobial efficacy was determined using the bacterial challenge, Staphylococcus aureus on 1 cm2 swatches of duct tape to which extruded fibers of LLDPE containing 50% Triosyn® T-50 powder (10 μm) were applied. Triosyn® T-50 beads and the LLDPE fibers alone were also assessed. After the required incubation time, the inhibition zone represented by a clear zone in the bacterial lawn surrounding the antimicrobial-containing article was readily obtained. A zone of inhibition is a region of the agar plate where the bacteria stop growing. The more sensitive the microbes are to the test article, the larger the zone of inhibition. If the bacteria is resistant to the test article, the bacteria are expected to grow right up to the test article itself.
2.) Detailed Description of Method
The antibacterial efficacy of polymer fibers composed of LLDPE/Triosyn® was evaluated against a bacterial challenge following a method based on the disk diffusion (Kirby Bauer) protocol, developed to evaluate the susceptibility of microorganisms to antimicrobial agents. For comparison, Triosyn® beads and blank fibers composed of LLDPE alone were also evaluated. The bacterial challenge used was of Staphylococcus aureus (ATCC #6538) bacteria in the growing phase, uniformly inoculated onto a nutrient agar plate onto which the test article will be deposited, and thus exposed to the bacterial challenge.
Staphylococcus aureus is a gram positive vegetative bacterium. Its cellular morphology is roughly spherical with a mean diameter of 0.5 to 1.5 μm. S. aureus is ubiquitous in the environment and is also found in the normal flora of the human skin and nose (20-30% of the general population are carriers); it is an opportunistic pathogen primarily causing healthcare associated infections (HAIs). S. aureus is a hardy organism that withstands desiccation and can survive in dust and on certain surfaces for extended periods of time, but can be inactivated by alcohol. S. aureus is one of the reference test organisms for antimicrobial activity studies, including the standard AOAC Test Method 961.02 (Germicidal spray products as disinfectants) and ASTM Standard Test Method F2101-01 (Evaluating the Bacterial Filtration Efficiency of Medical Face Mask Materials).
Two types of polymer fibers were tested. The LLDPE/Triosyn® fibers were made from pellets composed of 50% (w/w) Triosyn® T50 powder (˜10 microns) and LLDPE, obtained through a poly-compounding process. These pellets were heated and extruded to produce fibers. The blank (negative control) fibers, composed of 100% LLDPE, were produced following the same procedure. Triosyn® T50 beads were also tested. The test articles consisted of fibers or beads placed onto the adherent side of regular duct tape (used here as a support frame) in a tightly-packed parallel arrangement to form 1.0 cm2 samples.
3.) Testing Procedure
The microbiological test method used to assess the antibacterial efficacy of polymer fibers and beads was based on the disk diffusion (Kirby Bauer) protocol, developed to evaluate the susceptibility of microorganisms to antimicrobial agents:
4.) Results
Inhibition Zone results are summarized in Table 4. The ability of the positive control Triosyn® polymer beads to inhibit bacterial growth was demonstrated by the 7.0 mm inhibition zone measured around the Triosyn® resin beads on the S. aureus lawn. The blank LLDPE fibers did not inhibit the growth of S. aureus and thus no zone of inhibition could be observed around the sample. In fact, growth was observed even directly below the blank LLDPE test article. In contrast, the fibers composed of Triosyn®/LLDPE were able to inhibit bacterial growth as a 1.0 mm inhibition zone was observed. Hence, the zone of inhibition using the Triosyn®-embedded fibers was approximately seven times smaller than the zone of inhibition using the Triosyn® T-50 resin beads.
Staphylococcus Aureus Challenge (M08-0144)
The results of the zone of inhibition study reveal that the Triosyn®-embedded fibers can exert a toxic effect on microbes in the region immediately surrounding the fibers. It is surprising that the zone of inhibition is significantly smaller for the Triosyn®-embedded fibers than for the Triosyn® T-50 resin beads and yet is effective in the end product, namely a woven of nonwoven fabric. This observation evidently shows that the Triosyn® resin beads are leaching more iodine than the Triosyn®-embedded fibers. Hence, the fiber serves as an effective barrier to the diffusion of iodine. Despite the fact that the iodine is held tightly to the fibers, the iodine still demonstrates a high degree of antibacterial efficiency, albeit in a highly localized region.
In a nonwoven article, the individual fibers, embedded with the Triosyn® powder (
The results presented in this application have significant implications for the development of antibacterial nonwoven, woven and other fabric like materials. Because the antibacterial effect is highly localized when iodinated resin 3 is embedded in the fibers such as fibers 7 and 8 (see
Uses in various goods include both durable and disposable goods. For example, the antimicrobial fibers of the present invention can be used products such as diapers, feminine hygiene, adult incontinence, wipes, bed linings, automotive products, face masks, air filtration, water filtration, biological fluids filtration, home furnishings and geotextiles. The media described herein can also be used in, for example: clothing, wound dressing, air filter, shelters, and liners. Additional uses include those known in the art for electrostatic filters and antimicrobial or antitoxin filters.
Having now described one or more exemplary embodiments of the invention, it should be apparent to those skilled in the art that the foregoing is illustrative only and not limiting, having been presented by way of example only. All the features disclosed in this specification (including any accompanying claims, abstract, and drawings) may be replaced by alternative features serving the same purpose, and equivalents or similar purpose, unless expressly stated otherwise. Therefore, numerous other embodiments of the additions and modifications thereof are contemplated as falling within the scope of the present invention as defined by the appended claims and equivalents thereto.
This application is a continuation-in-part (CIP) of U.S. application Ser. No. 10/528,005, filed on Mar. 16, 2005, which is a 371 of PCT/IB03/04553, filed on Sep. 8, 2003, which claims the benefit of priority to U.S. Provisional Application Nos. 60/411,006, 60/434,526 and 60/458,800, filed on Sep. 16, 2002, Dec. 19, 2002 and Mar. 28, 2003, respectively, the contents of each are hereby incorporated by reference herein in the entirety. This application also claims the benefit of provisional application 61/068,968, filed on Mar. 11, 2008.
| Number | Date | Country | |
|---|---|---|---|
| 60411006 | Sep 2002 | US | |
| 60434526 | Dec 2002 | US | |
| 60458800 | Mar 2003 | US | |
| 61068968 | Mar 2008 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10528005 | Jun 2006 | US |
| Child | 12381328 | US |
