Patent Application
20140273689
The present invention is directed to medical articles having improved antimicrobial efficacy.
In the United States, hospital-acquired infections, also known as nosocomial infections, cause or contribute to almost 100,000 deaths each year. Disposable medical articles, such as gowns, drapes, shoe covers, wraps, and caps are regularly used to minimize the transmission of such infections. These articles are often worn or used for a short period of time, for example less than ten minutes. This is especially true with isolation gowns, which are typically worn in intensive care units, or worn by clinicians caring for patients with compromised immune systems. Isolation gowns worn by clinicians are typically changed after visiting each patient. Visitors of patients having compromised immune systems also frequently wear isolation gowns. Isolation and surgical gowns are used primarily for three purposes in the relevant art. First, the gowns protect the clinician from the transfer of infectious organisms from the patient to the clinician by forming a physical barrier between the patient and the clinician. Second, the gowns prevent the transfer of infectious microorganisms from the clinician to the patient. Third, the gowns prevent the transfer of organisms from the hospital environment and/or from other patients to the clinician then from the clinician to another patient.
Many of these articles are made with nonwoven materials or fabrics, such as spunbond/meltblown/spunbond (SMS) laminates of polypropylene fibers and can form barriers against microbes and/or fluids. The ability to block the penetration of fluids, such as bodily fluids, is important in a medical environment. Some medical articles, such as medical gowns, are classified into levels of barrier performance based on the AAMI/ANSI PB70 standard, which is a standard developed by the Association for the Advancement of Medical Instrumentation and approved by the American National Standards Institute. In the AAMI/ANSI PB70 standard, the key test for measuring the barrier performance of a material is the Water Resistance: Hydrostatic Pressure Test, AATCC Test Method 127, which was established by the American Association of Textile Chemists and Colorists. The hydrostatic pressure test measures the resistance of a material to the penetration of water under increasing pressure.
There are four levels of barrier performance according to the AAMI/ANSI PB70 standard. Materials having an AAMI Level 1 classification pass a spray impact test and are effective for impact penetration. Examples of materials typically having an AAMI Level 1 classification include basic cover gowns and some isolation gowns. Materials having an AAMI Level 2 classification require a hydrostatic pressure of at least 20 cm H2O for water to penetrate through the material. Examples of materials typically having an AAMI Level 2 classification include articles that offer basic protection and are often used when the amount of exposure to fluids is relatively small and for a short period of time. Materials having an AAMI Level 3 classification require a hydrostatic pressure of at least 50 cm H2O for water to penetrate through the material. Examples of materials typically having an AAMI Level 3 classification include articles that offer increased barrier protection and are often used when the amount of fluid exposure is moderate. Materials having an AAMI Level 4 classification are impervious to water passing through.
Surgical drapes and gowns often have an AAMI Level 4 classification. Isolation gowns may have an AAMI level 1, 2, 3, or 4 rating. Surgical gowns typically have an AAMI level 3 or 4 rating and they typically include a fluorocarbon treatment to impart alcohol repellency. Many surgical drapes are made of SMS fabric that is not completely impervious across the entire drape area. Typically, the non-reinforced SMS portion of the surgical drape is alcohol and fluid repellant and has a hydrostatic pressure of at least 50 centimeters of H2O, Surgical drapes are generally rated AAMI level 4 in the reinforced critical zone surrounding the surgical site. The drape critical zone typically has a liquid impervious absorbent reinforcement adhered to the SMS drape body fabric. The impervious reinforcement often comprises a nonwoven/film bilaminate, where the reinforcement nonwoven is treated to make it absorbent.
Some nonwoven materials are coated with an antimicrobial material to kill microbes that contact the surface of the articles. Antimicrobial activity is measured by determining the log reduction of infectious bacterial counts after exposure to an antimicrobial substance. For example, a 3-log reduction refers to a 99.9% reduction, and a 4-log reduction refers to a 99.99% reduction. However, antimicrobial coatings known in the art are not as fast acting as desired.
There is a need in the art for nonwoven materials which have fast-acting antimicrobial activity. Preferably, the medical articles are able to kill a high number of microbes, such as a 2, 3 or 4 log reduction (99% to 99.99%), within a short period of time, such as fewer than 5 or 10 minutes. Such a material would help reduce the transmission of hospital-acquired infections, as the “quick kill” of microbes could break the chain of infection from one surface to another.
Huang, Wei and Leonas, Karen, Evaluating a One-Bath Process for Imparting Antimicrobial Activity and Repellency to Nonwoven Surgical Gown Fabrics, Textile Res. J. 70(9), 774-782 (2000), relates to nonwoven fabrics having various add-on levels of antimicrobial finish and fluorochemical finish. Huang examined ZONYL® 8300 from Ciba Specialty Chemical Corporation as the fluorochemical finish and polyhexamethylene biguanide (PHMB) as the antimicrobial finish. The antimicrobial efficacy was tested after 24 hours of incubation. Huang found that the effectiveness of the antimicrobial finish was not influenced by the level of the fluorochemical finish.
EP 1943302 is directed to a material substrate having at least part of a surface treated with an antimicrobial composition is described. The antimicrobial composition exhibits at least a 3 log 10 CFU reduction within a period of about 30 minutes after contact with various species of a broad spectrum of microorganisms. The substrate can be a nonwoven material that has good fluid barrier properties, which can be used in protective garments and sheets. Methods for manufacturing and imparting the antimicrobial treatment to the substrate are also provided.
All references cited herein are incorporated by reference in their entirety.
The present invention is directed to an article comprising, a nonwoven material, and a coating contacting the nonwoven material. The coating comprising at least one fluorochemical and at least one antimicrobial agent. The fluorochemical comprises at least one fluoropolymer. The add-on value of the at least one antimicrobial agent on the nonwoven material is less than 0.75%. The coating provides at least a 2-log reduction within 5 minutes when measured using AATCC Method 100.
The present invention is also directed to an article comprising a nonwoven material, and a coating contacting the nonwoven material. The coating comprises at least one fluorochemical and at least one antimicrobial agent. The at least one fluorochemical includes at least one fluoropolymer. The at least one antimicrobial agent is selected from the group consisting of a benzalkonium salt, a benzethonium salt, a octenidine salt, a chlorhexidine salt, free base chlorhexidine, triclosan and combinations thereof. The coating provides at least a 2-log reduction within 5 minutes when measured using AATCC Method 100.
The present invention is directed to articles comprising a material, such as a nonwoven material, and a coating comprising an antimicrobial agent and a fluorochemical having at least one fluoropolymer. The articles may be medical articles, such as gowns, shoe covers, drapes, wraps, caps, facial masks, curtain, lab coats, or any other article that may be used to prevent the transmission of fluids and/or microbes.
In some embodiments, the material may comprise any fabric or materials, including nonwoven materials or fabrics. Nonwoven fabrics refer to a single web, or an assembly or laminate of multiple webs, formed of individual randomly laid fibers, for example using a spunlaid, thermobonded, spunbonded, meltblown or bonded carded web process. A laminate of nonwoven fabrics, such as a spunbond/meltblown/spunbond (SMS) laminate of polypropylene fibers, is an example of one conventional fabric that could be used in the surgical field. Another example is a spunbond/film/spunbond (SFS) laminate. In some embodiments, spunlace (hydroentangled) materials may be used. In some embodiments, the material is about 1 to about 1000 grams per square meter, preferably 10 to 100 grams per square meter, more preferably 20 to 70 grams per square meter (gsm). As used herein, the term “about” means within ±10%, preferably ±5%, more preferably ±1% of the given value.
Any antimicrobial agent and fluorochemical having a fluoropolymer may be chosen such that the combination exhibits synergistic effect of enhancing the antimicrobial efficacy of a coating as compared to a coating having the same antimicrobial agent, but no fluoropolymer. In a preferred aspect of the present invention the combination provides at least a 2-log reduction within 5 minutes.
The antimicrobial agent may include quaternary ammonium salt agents, silver based agents, biguanides, amidines, and phenol derived compounds. Quaternary ammonium salts may include benzalkonium (e.g., benzalkonium chloride (BKC)), benzethonium (e.g., benzethonium chloride (BEC)), octenidine (e.g., octenidine dihydrochloride), cetrimonium (e.g., cetrimonium bromide or cetrimonium chloride), cetylpyridinium (e.g., cetylpyridinium chloride), benzoxonium (e.g., benzoxonium chloride), didecyldimethylammonium (e.g., didecyldimethylammonium chloride), and dodeclonium (e.g., dodeclonium bromide). Example biguanides include polyhexamethylene biguanide (PHMB), free base chlorhexidine and chlorhexidine salts. Example chlorhexidine salts include chlorhexidine gluconate (CHG) and chlorhexidine acetate (CHA). Example amidines include salts of bibrompropamidine, propamidine, hexamidine, and polihexanide. Silver based agents are solutions including elemental silver, such as silver nitrate, and silver salts, such as silver chloride. Phenol derivatives may include triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol or 2,4,4′-trichloro-2′-hydroxy diphenyl ether) and chloroxylenol (4-chloro-3,5-dimethylphenol)), hexachlorophene, policresulen (2-hydroxy-3,5-bis[(4-hydroxy-2-methyl-5-sulfophenyl)methyl]-4-methylbenzenesulfonic acid), phenol, chloroxylenol, and biphenylol.
The fluoropolymers present in the fluorochemical are preferably selected from acrylate copolymers, more preferably acrylate branched copolymers, and still more preferably acrylate branched copolymers having branched fluorininated carbon chains. In an aspect of the present invention the fluoropolymer may be represented by the following formula:
wherein n is 0-50, more preferably 4-20. Example fluorochemicals include UNIDYNE™ TG-5601 and TG-5502 both produced by Daikin Industries, ZONYL® 8300, PHOBOL® 8412, and PHOBOL® 7862, each produced by DuPont. UNIDYNE™ TG-5601 includes 55-65 wt % water, 20-30 wt % fluoroalkyl acrylate copolymer, 1-10 wt % methylethylene bix(oxy)dipropanol, and less than 5 wt % polyoxyethene glycol alkyl ether. UNIDYNE™ TG-5502 includes 62.3 wt % water, 30.0 wt % combination of fluoroalkyl methacrylate copolymer and emulsifiers, and 7.7 wt % tripropylene glycol. ZONYL® 8300 includes 14-20 wt % fluorinated acrylic copolymer, 3-5 wt % hexylene glycol, 1-5 wt % polyethylene glycol monotridecyl ether, and 70-85 wt % water. PHOBOL® 8412 includes 75-83 wt % water, 15-20 wt % perfluoroalkyl acrylic copolymer, 1-5 wt % hexylene glycol, and 1-2 wt % polyethylene glycol monostearate. PHOBOL® 7862 includes 13-30 wt % partially fluorinated acrylic copolymer and 1-3 wt % 2-methylpentane-2,4-diol.
Surprisingly, the fluorochemical in combination with antimicrobial agent has been found to provide improved effective antimicrobial activity as compared to antimicrobial activity without fluorochemical. In an aspect of the present invention, the coating may include more than one of the above fluorochemicals/fluoropolymers and/or more than one antimicrobial agent.
One manner known in the art for quantifying the amount of fluorochemical and antimicrobial agent provided on a nonwoven material is the “add-on level percent.” The add-on level percent is a measure of the additive coated on the fabric relative to the original dry weight of the fabric. The procedure for determining the add-on level percent is as follows. An 8 by 8 inch sample of fabric (alternatively referred herein as a “swatch”) to be coated is cut. The fabric sample is weighed prior to the addition of the coating. The sample of fabric is treated with the coating by submerging fabric into the coating solution for 2 seconds. The fabric sample is then weighed in a tared beaker. The fabric sample is air dried for a minimum of 15 minutes before placing in an oven. The fabric sample is oven dried in a Class A flammable oven for 8 minutes at 105° C. (for Examples 1-25 below) or at 130° C. (for Examples 26-46 below). After cooling, the fabric sample is weighed. The following formula (I) is then used to calculate the add-on level percent for the antimicrobial agent:
In Formula (I) “AM” refers to the antimicrobial agent. The weight pickup and dry weight are the values determined above. The % solids are known based on the antimicrobial solution used.
An equivalent formula, Formula (II), is used to calculate the add-on level percent of fluorochemical.
In formula (II) FC refers to the fluorochemical comprising fluoropolymer. The weight pickup and dry weight are the values determined above. The % solids are known based on the fluorochemical used.
The combination of fluorochemical/fluoropolymer and antimicrobial agent has been found to provide an effective antimicrobial coating on materials, such as nonwoven materials. The combination has been found to provide a synergistic effect, providing a 2, 3, or 4-log reduction of bacteria within five or ten minutes of application. That is, a nonwoven material coated with a combination of fluorochemical and antimicrobial agent is relatively more effective at reducing bacteria (i.e., has a larger log reduction in a shorter amount of time) as compared to a nonwoven material coated with the same amount of antimicrobial agent, but having no fluorochemical.
In some embodiments, the fluorochemical add-on level may be about 0.1% to about 1.5%, more preferably about 0.15% to about 1.0%, still more preferably about 0.2% to about 0.75%, and most preferably about 0.25% to 0.5%. In another aspect of the invention, the fluorochemical add-on level may be less than 0.25%. In some embodiments the antimicrobial agent add-on level may be about 0.2% to about 25.0%, more preferably about 0.4% to about 20.0%, still more preferably about 0.5% to about 15.0%, still more preferably about 0.6% to about 10.0%, still more preferably about 0.7% to about 5.0%, and most preferably about 0.74% to about 2.5%. In another aspect of the present invention, the antimicrobial agent add-on level may be less than 0.75%. In an aspect of the present invention, when more than one fluorochemical/fluoropolymer and/or more than one antimicrobial agent are included, the total add-on level of each component added together may fall in the above ranges.
The fluorochemical/fluoropolymer and antimicrobial agent may be applied to the materials separately or together. For example, in some embodiments, the fluorochemical may be applied first, and then the antimicrobial agent may be applied. In another aspect of the present invention, the fluorochemical may be added to the polypropylene resin that forms the nonwoven material. Then, the antimicrobial agent may be coated over the nonwoven material. In some embodiments, the fluorochemical and antimicrobial agent are combined into one formulation first, and then the combination formulation is applied to the materials. In some embodiments, a liquid formulation comprising the fluorochemical and antimicrobial is prepared and applied to the material. The liquid formulation may comprise one or more solvents, such as an alcohol and/or water. Examples of solvents include, but are not limited to water, ethanol, hexanol, acetone, isopropanol, benzyl alcohol, propylene glycol, glycerol, and polyethylene glycol. In some preferred embodiments, the liquid formulation comprises the fluorochemical and antimicrobial agent in water and alcohol solutions; preferred alcohols include ethanol, hexanol, or octanol. The add-on level calculation discussed above accounts for variations in solution formulations because the particular weight percent of a given solution is multiplied by percent of solids. Particular example formulations, including weight percents of the components, are provided below.
The coating of fluoropolymer and antimicrobial agent may be applied to the materials in any way. Preferably, a coating solution containing the fluorochemical/fluoropolymer and antimicrobial agent is padded, sprayed, or kiss gravure coated onto a material, such as a nonwoven material. The coating may be applied directly to the fibers before bonding. In preferred embodiments, the coating is applied after the nonwoven web is formed and bonded. Other additives, including but not limited to antistats and coating aids to lower the solution surface tension, may be added to the coating solution. In other embodiments, the fabric may be dip-coated or may be coated using a dip and squeeze padding process, using a formulation of fluorochemical or antimicrobial agent.
After the application of the coating, the coated material may be dried, by air drying or by using dryers. For example, air-impingement and flotation dryers may be used. The coated material may also be dried by pulling a heated gas, such as air, through the material while pinning the material to a porous surface such as a drum or belt.
In some embodiments, the articles of the present invention have an antimicrobial efficacy of at least a 2-log reduction of bacteria, preferably at least a 3-log reduction, and more preferably at least a 4-log reduction. In some embodiments, the antimicrobial effect is achieved in less than about 60 minutes, preferably less than about 30 minutes, more preferably less that about 10 minutes, and most preferably less than about 5 minutes.
In some embodiments, the articles of the present invention, which comprise coated materials, have similar barrier properties compared to the same materials in uncoated form. For example, in some embodiments, applying fluorochemical and antimicrobial agent to an SMS nonwoven fabric may decrease the hydrostatic pressure resistance value of the SMS nonwoven fabric (in uncoated form) by no more than about 50%, preferably by no more than about 40%, more preferably by no more than about 30%, and more preferably by no more than about 0 to 10%.
In some embodiments, the hydrostatic pressure of the coated materials (as measured by, for example, the Water Resistance: Hydrostatic Pressure Test, AATCC Test Method 127) is preferably at least 20 cm H2O and more preferably at least 30 cm H2O. In some embodiments, for example, when the coated material is used for surgical gowns, the hydrostatic pressure of the coated materials may be preferably at least 50 cm H2O.
An experiment was conducted to compare the effect of the combination of various fluorochemical and antimicrobial agents. The following coating formulations (Examples 1-25 in Table I) were prepared with deionized water and applied to an 8 by 8 inch fabric swatch of a 34 gsm spunbond/meltblown/spunbond (SMS) nonwoven material according to the add-on percent method described above. The samples were then tested for antimicrobial efficacy and barrier properties.
The antimicrobial efficacy of Examples 1-25 were measured using the American Association of Textile Chemists and Colorists (AATCC) Method 100, after 5 minutes. E. coli, AATCC #11229 and methicillin-resistant Staphylococcus aureus (MRSA), AATCC #43300 a gram-negative and gram-positive organism respectively were used for the testing bacteria. The samples were tested for barrier properties using the Water Resistance Hydrostatic Pressure Test, AATCC 127 test method. The hydrostatic pressure results are an average of two readings. The Hydrostatic Pressure (HP) measures the resistance of fabric to the liquid penetration of water under increasing pressure. There are four levels of AAMI barrier performance, AAMI level 1 does not have a HP requirement. AAMI level 2 requires a HP of at least 20 cm H2O, and AAMI level 3 requires a HP of at least 50 cm H2O. AAMI level 4 is totally impervious and the fabric typically is spunbond-film-spunbond (SFS) fabric, which is more expensive to produce and not as breathable as SMS fabric. The uncoated 34 gsm SMMMS fabric used for our experimentation was rated AAMI level 3, requiring a HP of at least 50 cm H2O.
Table I shows the components of each example and the amount of each component that is added to the non-woven swatch in terms of add-on level. Table II shows the log reduction and hydrostatic pressure results for Examples 1-25.
E. coli
The results show that the combination of fluorochemical/fluoropolymer and antimicrobial agent on the SMS nonwoven material demonstrated higher log reductions within 5 minutes of both E. coli and MRSA and than the comparative SMS nonwoven materials where the same antimicrobial was used without fluorochemical. Compare Examples 6, 9, 13, 17, 20, 24, 31, 37, 42 (no fluorochemical) with Examples 7, 8, 10-12, 14-16, 18, 19, 21-23, and 25 (combination of fluorochemical and antimicrobial). For example, Octenidine/CHG without fluorochemical (Example 9) shows less antimicrobial efficacy within 5 minutes as compared to a combination of Octenidine/CHG and TG-5601 fluorochemical (Examples 10-12). In addition, the barrier properties of the coated SMS nonwoven material, measured by the hydrostatic pressure test, were maintained at a high value.
The previous description is provided to enable any person skilled in the art to practice the various embodiments described herein. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments. Thus, the claims are not intended to be limited to the embodiments shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” All functional equivalents to the elements of the various embodiments described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”
This application claims the benefit of U.S. Provisional Application Ser. No. 61/799,443, filed on Mar. 15, 2013, which is expressly incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61799443 | Mar 2013 | US |
