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
2001-08-31
2004-04-27
Juska, Cheryl A. (Department: 1771)
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...
C442S152000, C442S153000, C442S164000, C442S165000, C442S170000, C442S171000, C442S172000, C604S359000, C604S360000, C604S364000, C604S367000, C604S370000
Reexamination Certificate
active
06727196
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the use of surfactents which may be inactivated or degraded upon contact with one or more materials possibly in one or more layers of a substrate. The composite material includes a surfactant that can be applied to a substrate such as a nonwoven web such that the surfactant reduces the surface tension of a fluid so that the fluid intake into the substrate is enhanced and such that the surfactant is inactivated upon contacting or passing into another portion of the substrate.
BACKGROUND OF THE INVENTION
Surfactants are well-known compounds that are used in many fields to provide low surface tension to water or other fluids resulting in increased wettability, spreadability, emulsification, dispersion, penetration, and/or improved adhesion. Some surfactants also are known to impart softness characteristics to certain products, such as tissue.
While surfactants may produce a number of desired properties and benefits, prior usage of articles containing surfactants or having surfactants on the surface of the substrate reveals that surfactants frequently have adverse effects on the properties of the materials and/or surroundings to which the surfactants pass. For example, a surfactant is most commonly applied to a surface of a substrate in anticipation of fluid contact; however, after the surfactant is contacted by a fluid, some or all of the surfactant typically dissolves in the fluid and flows into the substrate with the fluid. The presence of the surfactant in the fluid in the substrate may result in reduced fluid flow (wicking) through the substrate due to reduced fluid surface tension which reduces capillary pressure. That is, if the substrate contains a surfactant the surfactant will enhance the passage of a contacting fluid into the substrate. However, the presence of the surfactant in the fluid reduces the wicking force (speed) end thus the substrate directly under the liquid penetration point can become saturated. This saturation will restrict the passage of more fluid into the substrate which may result in leakage and, an undesirable appearance of the product or even adverse contact with the skin of the wearer. The presence of a superabsorbent in the substrate magnifies the problem. As the surfactant containing fluid is being wicked at a slower rate, the fluid has a longer residency time near the superabsorbent near the fluid entry location into the substrate. These superabsorbent particles continue to swell and absorb fluid which eventually will lead to “gel blocking”. More specifically, the phenomenon of gel blocking describes the tendency of hydrogel materials or so-called “superabsorbent materials” to swell in place once wetted and produce gelatinous material which blocks further transmission of the fluid being absorbed. The gelatinous material not only effects the fluid intake or absorption properties or the superabsorbent material, but also inhibits the wicking and dispersion properties of the total absorbent material. Therefore, where the fluid being absorbed contacts the absorbent material in a highly localized area at a rate which exceeds that which the super absorbent material can readily tolerate, much of the absorbent medium frequently is not utilized at all, thus resulting in an inefficient product.
Although the use of surfactants provides some of the properties noted above, the use of surfactants may also create additional problems. For example, certain surfactants have been stated by authorities to have potential long-term harmful characteristics, and may give rise to environmental concerns if not inactivated or degraded before being released into the environment. Furthermore, most frequently used surfactants are not readily degradable, and thus remain surface active long after producing the desired effect on the desired surroundings. While the use of non-degradable or not readily degradable surfactants may provide certain desired properties to a substrate (i.e. reduced surface tension, enhanced or controlled penetration and/or softness), because the surfactants may be non-degradable they not only continue to attempt to impart these properties on their surroundings (including those on which it is not intended or is undesirable to do so), but may, according to authorities, also cause damage (i.e. cell destruction) in the environment long after the product incorporating them has been used, discarded and/or destroyed.
In addition to creating and/or causing environmental problems or concerns, surfactants which are not inactivated or degraded, also may produce less than desirable results if used in some products. That is, the surfactants which are not degraded or inactivated continue, at least to some degree, to impart their characteristics on surrounding fluids and surfaces after the surfactant has achieved its purpose for incorporation. For example, a surfactant is unable to distinguish between when it is desired that the surface tension of a fluid be reduced and when it is undesirable to do so. Consequently, unless degraded, inactivated, or otherwise prevented from doing so, the surfactant will continue to impart its surface tension reducing properties on surrounding fluids and the environment even where it may be undesirable to do so.
This is especially true where the surfactant has been included or incorporated in the product for the purpose of lowering the surface tension of an insulting or contacting fluid. For example, in certain applications, especially in diapers, training pants and the like, where at least some of the surfactant passes from a topsheet or liner of the diaper or training pant to a second layer but is not inactivated or degraded, rewet or backflow of the fluid intended to be removed from the wear surface may occur to some degree, thereby reducing the effectiveness of the product and/or possibly causing leakage. Rewet or backflow is frequently the result of the pressure which is generated by the wearer's actions (i.e. sitting, twisting, etc.) and by the remaining surface activity of the surfactant which has migrated into the product with the fluid (e.g. the surfactant's surface activity inside the article reduces the surface tension of the fluid contained therein and allows or encourages the movement of fluid from inside the article back to the wear surface of the article, thereby defeating the original intent of containing the fluid in the article). The inability to inactivate or degrade a surfactant often reduces the effectiveness of the product, and especially personal care products. Furthermore, as above, the presence of an active surfactant in an absorbent material adversely effects the wicking properties or capillary action (as expressed by Laplace's equation) of the material.
Although some surfactants are known to be degradable, such as those disclosed in U.S. Pat. No. 5,527,560 of Fereshtehkhou et al., U.S. Pat. No. 5,427,696 of Phan et al., U.S. Pat. No. 5,312,522 of Phan et al., and U.S. Pat. No. 5,274,159 of Pellerite et al., these surfactants typically are used as softeners and detergents. The use of pH degradable surfactants in personal care product applications is not known. Furthermore, the surfactants developed as detergents and softeners depend on temperature for their degradability characteristics that are due, presumptively in part, to the fact that a range of temperatures can be expected in the environment or in the environment they are intended to be used in, whereas a specific range of pH cannot be accurately controlled, projected or expected to occur in the environment. Those surfactants which are known to be pH degradable are used in water treatment stations; however, those surfactants do not degrade substantially immediately and are part of a homogeneous solution where the pH of the entire solution is substantially uniform. (See “TRITON SP-Series Surfactants” pamphlet UC-1492, published by Union Carbide Corporation.) It is not known to use pH degradable surfactants in heterogeneous composites.
Thus, there is a need for a surfactant or class of surfacta
Brostin Joel
Cohen Bernard
Morman Michael Tod
Yahiaoui Ali
Juska Cheryl A.
Kimberly--Clark Worldwide, Inc.
Kyriakou Christos S.
Letson William W.
Salvatore Lynda
LandOfFree
Surfactant systems for personal care products does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Surfactant systems for personal care products, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Surfactant systems for personal care products will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3266838