Method and composition for treating substrates for...

Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Coated or impregnated woven – knit – or nonwoven fabric which... – Coating or impregnation is water absorbency-increasing or...

Reexamination Certificate

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Details

C442S171000, C442S392000, C442S400000, C442S401000

Reexamination Certificate

active

06204208

ABSTRACT:

BACKGROUND OF THE INVENTION
Nonwoven fabrics and their manufacture have been the subject of extensive development resulting in a wide variety of materials for numerous applications. For example, nonwovens of light basis weight and open structure are used in personal care items such as disposable diapers 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 wrappers for items to be sterilized, 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. There have also been developed different ways and equipment to make nonwovens having desired structures and compositions suitable for these uses. Examples of such processes include spunbonding, meltblowing, carding, and others which will be described in greater detail below. 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.
It is not always possible to efficiently produce a nonwoven having all the desired properties as formed, and it is frequently necessary to treat the nonwoven to improve or alter properties such as wettability by one or more fluids, repellency to one or more fluids, electrostatic characteristics, conductivity, and softness, to name just a few examples. Conventional treatments involve steps such as dipping the nonwoven in a treatment bath, coating or spraying the nonwoven with the treatment composition, and printing the nonwoven with the treatment composition. For cost and other reasons it is usually desired to use the minimum amount of treatment composition that will produce the desired effect with an acceptable degree of uniformity. It is known, for example, that the heat of an additional drying step to remove water applied with the treatment composition can deleteriously affect strength properties of the nonwoven as well as add cost to the process. It is, therefore, desired to provide an improved treatment process and/or composition for nonwovens that can efficiently and effectively apply the desired treatment without adversely affecting desirable nonwoven web physical properties and achieve the desired results.
It is also known that most conventional surfactants that are water dispersible are not prone to form high-solids (>10 weight %), low viscosity (<100 cp), stable mixtures with water. An additional desire, therefore, is to provide a high-solids treatment bath that is stable without phase separation over an extended period and that exhibits a low viscosity profile at room temperature as well as means to effectively apply the surfactant treatment to impart a durable hydrophilic character to the substrate such as a nonwoven.
It is also known to use skin wellness additives to facilitate healthy skin in the wearer. However, known skin wellness additives (combined with surfactants) often reduce the wettability of the nonwoven web. Skin wellness additives, when used, are often applied sparingly, or in zones, so as not to offset the wettability caused by the surfactants.
SUMMARY OF THE INVENTION
The present invention is directed to an improved composition and method for effectively and efficiently treating nonwovens to impart one or more desired property such as durable wettability and to the resulting improved nonwovens. The process and composition include at least one surfactant in combination with a viscosity modifier and includes subjecting one or both sides of the nonwoven to a neat or high solids treating composition. Drying and its deleterious effects are essentially or completely unnecessary, and the process provides means to uniformly treat one or both sides of the nonwoven to a desired degree without adversely affecting the durability of the result, for example web wettability. In accordance with the process of the invention, a nonwoven fabric is directed to a treating station where a treating composition that is preferably less than about 90% solvent is applied to the fabric by means of coating, dipping, spraying, or the like, in an amount to effectively treat the area of the fabric contacted by the composition. The treated fabric may then be subjected to a similar treatment on the same or the opposite side and minimal drying, if necessary. Moreover, the process of the invention greatly facilitates any cleanup steps that may be required. The resulting treated nonwovens have been shown to be uniformly, durably and effectively treated with reduced composition requirements and minimal or no adverse effects. Preferred treatments include a combination of a surfactant which, itself, is a blend of ethoxylated hydrogenated castor oil and sorbitan monooleate, and a viscosity modifier, an alkyl polyglycoside. These treatments for nonwovens are of particular use for personal care, medical and other applications such as wipers, protective garments, applicators, and others where compositions are applied to a substrate desirably at high solids.
The present invention is also directed to a composition and method for treating nonwovens to impart relatively high rewet (durability) performance for accepting multiple fluid insults and fast fluid intake rates. For this application, the preferred treatments include a combination including at least two surfactants. A first surfactant includes a compound selected from an ethoxylated hydrogenated fatty oil, a monosaccharide, a monosaccharide derivative, a polysaccharide, a polysaccharide derivative and combinations thereof. A second surfactant includes an organosilicon compound. The surfactant combination can be prepared in the form of an aqueous emulsion which is then homogenized. In this embodiment, the second surfactant acts as a powerful emulsifier, flow/viscosity modifier and leveling aid. Nonwovens treated in this fashion are especially useful for diapers, training pants, incontinence garments, and other applications requiring possible exposure to multiple fluid insults.
The present invention is also directed to a composition and method for treating nonwovens to impart the foregoing properties of durable wettability and/or high rewet performance in combination with improved skin wellness. This composition includes at least a first (surfactant) component selected from an ethoxylated hydrogenated fatty oil, a monosaccharide, a monosaccharide derivative, a polysaccharide, a polysaccharide derivative, and combinations thereof; and a skin wellness additive which includes aloe vera. When used in combination with the first surfactant, and optional ingredients listed below, aloe vera can be used to impart its known skin wellness properties, surprisingly without reducing wettability. While skin wellness additives are known, other compositions have had the undesired side effect of reducing wettability. Aloe vera, in combination with the first surfactant described above, overcomes the problem of reduced wettability.


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