Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Using disinfecting or sterilizing substance
Reexamination Certificate
2000-11-28
2004-07-27
McKane, E. Leigh (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Using disinfecting or sterilizing substance
C442S123000, C442S164000, C604S360000
Reexamination Certificate
active
06767508
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a nonwoven web having antimicrobial and bactericidal properties. More particularly, the invention is a heterogeneous system including a nonwoven web treated with an alkyl polyglycoside surfactant in contact with an aqueous source of bacteria.
BACKGROUND OF THE INVENTION
Nonwoven fabrics can be used to produce a wide variety of materials suitable for a broad range of applications. For example, nonwovens of light basis weight and open structure are used in personal care items such as disposable diapers. More particularly, such nonwovens can be used as liner fabrics that provide dry skin contact but readily transmit fluids to more absorbent materials which may also be nonwovens of a different composition and/or structure. Nonwovens of heavier weights may be designed with pore structures making them suitable for filtration, absorbent and barrier applications such as wipers or protective garments for medical, veterinary or industrial uses. Even heavier weight nonwovens have been developed for recreational, agricultural and construction uses. These are but a few of the practically limitless examples of types of nonwovens and their uses that will be known to those skilled in the art who will also recognize that new nonwovens and uses are constantly being identified. The present invention has general applicability to nonwovens as will be apparent to one skilled in the art, and it is not to be limited by reference or examples relating to specific nonwovens which are merely illustrative.
There have also been developed different treatments for enhancing specific properties of nonwovens. For example, properties such as wettability by one or more fluids, repellency to one or more fluids, electrostatic characteristics, conductivity, and softness, can be altered or improved through treatment with specific compositions. Still, further enhanced properties of nonwovens are desirable.
In particular, personal care items produced from nonwoven webs typically come in contact with bacteria as part of their intended use. There is thus a need or desire for a nonwoven fabric having effective antibacterial properties.
SUMMARY OF THE INVENTION
The present invention is directed to a heterogeneous antibacterial system, and a method of reducing bacterial growth in a nonwoven web. The heterogeneous antibacterial system includes a nonwoven web treated with an alkyl polyglycoside surfactant. Used to combat an aqueous source of bacteria, the alkyl polyglycoside surface treatment imparts antimicrobial and bactericidal properties to the nonwoven substrate.
The alkyl polyglycoside surfactant solution can be applied to the nonwoven web in dilute concentrations, generally 0.3-20%, by various saturation, spray, printing, and foam methods. The intrinsic antimicrobial and bacteriostatic properties of the surfactant solution are transferred to the nonwoven web, yet the surfactant solution is virtually non-irritating and non-sensitizing to human skin.
The surfactant treated nonwoven with antimicrobial and bactericidal properties can be used in a broad range of hygienic applications. For example, a nonwoven web treated with an alkyl polyglycoside-based formulation can be beneficial as an antibacterial wipe, as a bandage or wound dressing, or as a treatment for personal care materials to promote skin health, such as prevention of diaper rash, or other types of skin irritation. Furthermore, the treated nonwoven web can be placed in a personal care product in a number of strategic locations designed to prevent bacterial activity. The treated nonwoven can be a liner for direct skin contact for skin health benefits or in layers below the liner, such as surge layers, distribution layers, or retention layers, to control the activity of bacteria that causes malodor formation from retained body fluids. The nonwoven web can be made of synthetic and/or natural fibers.
With the foregoing in mind, it is a feature and advantage of the invention to provide a method of reducing bacterial growth in a nonwoven web, resulting from exposure to an aqueous source of bacteria.
It is also a feature and advantage of the invention to provide a heterogeneous antibacterial system including a solid/liquid interface between a nonwoven web and an aqueous source of bacteria.
DEFINITIONS
Within the context of this specification, each term or phrase below will include the following meaning or meanings.
“Average fiber length” refers to a weighted average length of fibers determined using a Kajaani fiber analyzer Model No. FS-100 available from Kaja Oy Electronics in Kajaani, Finland. Under the test procedure, a fiber sample is treated with a macerating liquid to ensure that no fiber bundles or shives are present. Each fiber sample is dispersed in hot water and diluted to about a 0.001% concentration. Individual test samples are drawn in approximately 50 to 500 ml portions from the dilute solution and tested using the standard Kajaani fiber analysis procedure. The average fiber lengths may be expressed by the following equation:
∑
X
i
>
0
k
(
X
i
*
n
i
)
/
n
where k=maximum fiber length,
X
i
=individual fiber length,
n
i
=number of fibers having length X
i
and
n=total number of fibers measured.
“Hydrophilic” or “wettable” describes fibers or the surfaces of fibers which are wetted by the aqueous liquids in contact with the fibers. The fibers or the surfaces of the fibers may have been treated with a surfactant, a surfactant combination, or other finishing agents. The degree of wetting of the materials can, in turn, be described in terms of the contact angles and the surface tensions of the liquids and materials involved. Equipment and techniques suitable for measuring the wettability of particular fiber materials or blends of fiber materials can be provided by a Cahn SFA-222 Surface Force Analyzer System, or a substantially equivalent system. When measured with this system, fibers having contact angles less than 90° are designated “wettable” or hydrophilic, while fibers having contact angles greater than 90° are designated “nonwettable” or hydrophobic.
“Layer” when used in the singular can have the dual meaning of a single element or a plurality of elements.
“Meltblown fiber” means fibers formed by extruding a molten thermoplastic material through a plurality of fine, usually circular, die capillaries as molten threads or filaments into converging high velocity heated gas. (e.g., air) streams which attenuate the filaments of molten thermoplastic material to reduce their diameter, which may be to microfiber diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly dispersed meltblown fibers. Such a process is disclosed for example, in U.S. Pat. No. 3,849,241 to Butin et al. Meltblown fibers are microfibers which may be continuous or discontinuous, are generally smaller than about 0.6 denier, and are generally self bonding when deposited onto a collecting surface. Meltblown fibers used in the present invention are preferably substantially continuous in length.
“Nonwoven” and “nonwoven fabric or web” refer to material and webs of material which are formed without the aid of a textile weaving or knitting process. Nonwoven fabrics or webs have been formed from many processes such as, for example, meltblowing processes, spunbonding processes, air laying processes, and bonded carded web processes. The basis weight of nonwoven fabrics is usually expressed in ounces of material per square yard (osy) or grams per square meter (gsm) and the fiber diameters useful are usually expressed in microns. (Note that to convert from osy to gsm, multiply osy by 33.91.)
“Polymers” include, but are not limited to, homopolymers, copolymers, such as for example, block, graft, random and alternating copolymers, terpolymers, etc. and blends and modifications thereof Furthermore, unless otherwise specifically limited, the term “polymer” shall include all possible geometrical configuration
Yahiaoui Ali
Young Matthew David
Kimberly--Clark Worldwide, Inc.
McKane E. Leigh
Pauley Petersen & Erickson
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