NONWOVEN FABRIC COMPOSITES HAVING ZONES OF DIVERSE PROPERTIES
BACKGROUND OF THE INVENTION
This invention relates generally to the art of nonwoven fabrics, and more particularly to airformed nonwoven fabrics treated so as to have zones of differing properties.
Nonwoven materials have traditionally been utilized for a variety of applications. A major utilization of nonwoven material is in the area of disposable diapers wherein absorbent nonwoven fabrics house super absorbent materials so as to contain large volumes of absorbed material, such as liquids, without significant leakage. Other uses of nonwovens include tampons and sanitary napkins where absorbency is also a critical factor. In these various applications diverse materials are frequently utilized in a uniform manner so as to achieve a desirable end product. While many such materials have performed well for their intended uses, there exists room for improvement in the art.
SUMMARY OF THE INVENTION It is thus a primary object of this invention to provide a novel composite material having zones of differing properties .
It is a further object of this invention to provide a simple, economical process for creating a novel composite material wherein zones of differing properties can be created in one or more desired dimensions of the composite material. It is another object of this invention to provide a novel composite material where flow paths of absorbed liquids may be controlled.
It is a further object of this invention to provide such composite materials where such flow paths may be controlled in a variety of directions or dimensions within the material.
There is an additional object of this invention to provide a process for producing such composite materials having controlled flow paths. These as well as other objects are accomplished by a composite material formed of a nonwoven web of fibrous material having a foam applied material non-uniformly applied to said web so as to provide differing properties between the zones formed only on the nonwoven web and zones formed by the web and foam applied material.
A process is provided wherein a web of nonwoven material is contacted by a foamed material so as to form zones containing such foamed material having differing properties from zones containing only fibrous material .
BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates one embodiment of the composite of this invention illustrating a cross-section of a non-woven web material having zones of differing properties.
Figure 2 illustrates another embodiment of the material of this invention in a cross-section of a non-woven web material showing zones of differing properties. Figure 3 is a perspective view of a web in accordance with this invention.
Figure 4 illustrates another cross-section of a web material wherein edge areas of differing properties have been formed. Figure 5 is a diagrammatic illustration of one process of forming the composite of this invention.
Figure 6 is a diagrammatic illustration of another process of forming a composite wherein the zones of differing properties are formed in the edge areas of the web. Figure 7 is a diagrammatic illustration of a process utilizing multiple applicators for the foam to be applied to the web.
DETAILED DESCRIPTION In accordance with this invention it has been found that a nonwoven material may be treated with a material so as to provide diverse areas having respective but desirable properties in such areas. The material with which the nonwoven material is treated is preferably a foam, since foams remain where applied and neither wick nor migrate at the level typical of other flow materials. An example would relate to the utilization of a foamed material which is hydrophobic while the fibrous material is hydrophilic, thus creating channels or zones in which liquid is contained or can flow. For example, sanitary napkins may have outer zones containing hydrophobic foam applied material while the central area contains the hydrophilic fibrous materials so as to contain liquid only within the central area of the napkin. Likewise, with diaper materials leakage out the edge areas may be prevented by providing a hydrophobic foam applied material impregnating the edge areas of the web.
While specifically directed to the formation of hydrophobic and hydrophilic zones, the invention encompasses the formation of zones with any desired properties. The web material may be, or may be impregnated with, substances providing one set of properties. U.S. Patent Number 4,429,001 to Kolpin et al . , for example, shows one method of impregnating a web with particles of a specific material.
The foamed material applied to the web material to form the zones of differing properties may also contain selected substances to provide a set of other properties.
Further other advantages and features will become apparent from a reading of the following description, given with reference to the various figures of drawing.
Figure 1 of the drawings generally illustrates a cross section of a web 1, the section being taken, e.g., along the transverse direction of a continuous web. Web 1 is formed of a fibrous material and has areas 3, 5 and 7 having only fibrous material present while areas 9 and 11 represent areas which have been impregnated with a hydrophobic foamed material. Areas 9 and 11 are impenetrable to liquid while areas 3, 5 and 7 represent zones where liquid can freely flow. In this instance, high-pressure foam totally impregnates the web in the areas 9 and 11.
The term "foamed" and "foamed material" is used throughout this specification to refer to materials which are applied in the foamed state by conventional foam applicators. Foam is utilized because it generally retains the dimensions as applied and thus provides dimensional stability and predictability. After application, however, the foam applied material loses its foam characteristics.
Figure 2 of the drawings is a further embodiment showing a cross-section of a web 21 with the section being taken along the machine direction of a continuous web. Web 21 is formed having outer layer areas 23 and 25 formed from foamed material. Areas 23 and 25 have been applied in a low pressure process to provide only an outer layer of hydrophobic material .
Figure 3 of the drawings represents yet another embodiment wherein the invention has three-dimensional characteristics. For purposes of description, web 31 of figure 3 has planar dimensions X and Y and a thickness dimension Z.
It is seen from figure 3 that web 31 comprises a layer 33 of fibrous material which has been impregnated at 35 with a foam high-pressure material which extends in both the X and Y directions throughout the thickness in the Z direction to provide hydrophobic properties in that area. Additionally, there is illustrated an area 37 which is a layer of hydrophobic material applied by low pressure foamed material which simply resides above layer 33 to define an area 39 which would be a reservoir for aqueous material .
Figure 4 of the drawings illustrates a cross-section where web 41 has been treated to provide edge areas 43 and 45 with a fibrous area 47 within the central area of web 41. Where edge areas 43 and 45 have been treated with a hydrophobic material and central fibrous area 47 is formed of hydrophilic or super-absorbent material. A seal may be formed about fibrous area 47 so as to contain liquid therein. Figure 5 of the drawings illustrates a process of forming the composite according to this invention. A conventional web of nonwoven fibers is formed on a forming surface, such as a fourdriniere wire, and foam is applied by conventional applicators either in a high-pressure format to impregnate the web or low pressure to simply create a layer in the Z direction if so desired. Additional fiber layers may be provided above the foam material as illustrated at 55. Figure 6 of the drawings illustrates an embodiment wherein a web 61 has foam applications only in the edge areas by foam applicators 63 and 65. This creates generally the type of fabric as illustrated in figure 4. It is understood, however, that wide forming webs may be utilized as illustrated in Fig. 7 of the drawings, which is a top view of a web 71 having a plurality of foam applicators 73, 75, 77 and 79. It is understood that when this application is utilized the web may be slit along the various foam lines to provide a plurality of products having foam only in the edge area.
The product and process of this invention may be carried out with a variety of well known fibrous mat materials and foam materials. Examples of fibrous materials which may be utilized for forming the web are selected from a wide variety of known materials such as wood pulp, polypropylene, polyethylene, polyethylene terphthalate, polyamides, and the like.
Examples of foam applied materials which may be utilized with this invention are fluorocarbons, pigment dispersions, dyes, polymer binders such as ethylene-vinyl acetate, acrylics, etc.
It is understood that the process of this invention may be carried out to produce a composite which not only has channels produced by the non-uniform application of the foam material but which has channels which may direct liquids to desired areas of the composite. Typically, such areas can be, have, or contain highly absorbent material, for example in the nature of powders or other fibers, so as to create a reservoir area for storage of such liquids.
In many situations it may be desirable to have a general uniform appearance of the composite while the composite itself has areas which are non-uniform. In such instances the foam and fibrous mat material will be generally of the same color. In other instances it may be desirable to have them of differing colors so as to emphasize at view varying areas . Additional additives to the web may include surfactants so as to enhance the absorbency characteristics of the web. Dyes, for example, may be contained in the web, in the foam, or both for aesthetic or functional purposes. While the invention has been described herein principally in terms of forming hydrophobic and hydrophilic areas in a web, it is not so limited. The web may be or may be impregnated with materials having any desired characteristics or properties, while the material used to form the zones within the web may have any differing characteristics or properties. For example, antiseptic- containing zones can be created in a material intended for bandaging wounds. In one particular example, zones in a web material designed for use in agriculture may contain herbicidal or insecticidal material . When laid in a field or garden, the material would protect plants from harm while providing other zones within the web where desired plants may be sown without being exposed to the herbicidal material . Other applications include, but are not limited to, use in inkjet pads, anti-skid materials, treatment pads such as acne pads, packaging materials, and the like. Areas of varying adhesives, such as pressure sensitive adhesives, can be formed to create a material which is only selectively sensitive. Fields of application for this invention include any requiring a continuous material having zones with differing properties.
It should also be appreciated that the invention is not limited to the creation of only two differing zones, of whatever configuration. Apparatus such as is illustrated in Figure 7 hereof can be used to apply two or more types of what is called herein foam material. Each foam material may be or contain substances with a wide variety of properties. Thus, for example, a continuous web can be formed which has a hydrophobic zone, a hydrophilic zone, and a dye zone. The area of the dye zone may coincide with either of the other two zones or be entirely separate. Another application may be in sanitary napkins where the process of this invention could, simultaneously or nearly so, create a material having hydrophobic sealing zones and pressure-sensitive adhesive zones .
It is thus seen that a composite material is provided by this invention which has non-uniform characteristics with highly desirable properties. This invention further provides processes for producing such materials with a variety of non- uniform applications of foam material.
Many variations will become apparent to those skilled in the art from a reading of the above description. However, the spirit and scope of this invention is to be limited only by the following appended claims.