Patent Application
20140324009
The present invention relates to apertured and embossed fibrous nonwoven webs which are particularly well adapted for use as intake layers for personal care absorbent articles including, but not limited to, feminine hygiene products. The present invention further relates to equipment and a process for forming such apertured and embossed fibrous nonwoven webs.
Fibrous nonwoven webs are used in a wide variety of applications many of which are single or limited use before disposal takes place. While such nonwoven webs are typically liquid permeable, in certain applications greater permeability is required and so aperturing of the web is also undertaken. This is particularly true with absorbent articles such as personal care absorbent articles including, but not limited to diapers, diaper pants, training pants, adult incontinence products, feminine hygiene products, bandages and the like. In such applications, such fibrous nonwoven webs are often used as bodyside liner materials (also referred to as the topsheet) and/or one or more of the underlying layers.
In many of these applications, feminine hygiene products being a prime example, for such a fibrous nonwoven web to be successful, it should attempt to satisfy a number of criteria. A topsheet in a sanitary napkin is one of the most important materials affecting the consumer's purchasing intention because it is a very critical factor in determining the product appearance and performance. Over the years, consumers' needs and uses for feminine hygiene products have become greater and more complicated. As a result, it has become increasingly more important to differentiate products from one another as to performance, appearance and aesthetic appeal. For this reason, many studies have been conducted relative to the product's overall appearance and performance and specifically the topsheet construction including its fiber composition, degree of perforation, embossing design and post-treatment relative to such attributes as softness, feel, fluid intake, rewet and other performance characteristics. Perforation technology is widely used to provide improved absorbency and absorbent visual cues, and embossing patterns are used to provide improved breathability by lessening the skin contact surface area. However, many of the commercialized embossing patterns are very simple, linear designs, that are not highly differentiated by the consumers and tend to perform the same.
To make a more three-dimensional and visually distinctive pattern, multi-step perforation, embossing and lamination steps are often employed. Practically, in such situations, higher basis weight materials are required to make visually attractive embossing. Further, to make embossing and perforation patterns in the same product, multi-step processes are generally required. For example, often the fibrous nonwoven web is perforated in a first step and then laminated with a non-perforated nonwoven. Next, the combination is typically joined using ultrasonics, adhesives or embossing. Perforation and embossing can be made on the same material in one step without lamination process but it has been found that the embossing pattern can be very easily deformed by the tension and pressure used during the formation process, especially when high basis weight materials are not being used.
There is therefore a need for a fibrous nonwoven web which is pattern embossed and apertured which can be used in a wide variety of applications where such materials are needed for such attributes as fluid intake, improved visual appearance and overall performance. This is particularly the case with fibrous nonwoven webs which are used as topsheets for personal care absorbent articles such as feminine hygiene products including, for example, sanitary napkins. It is an object of the present invention to provide perforated patterns with improved breathability and a more visually distinctive look with no increase in basis weight and process cost, wherein the pattern has a high enough open area to maintain absorbency and breathability and is not easily deformed by the tension and pressure applied during the manufacturing process.
Disclosed herein is a fibrous nonwoven web with a top surface and a bottom surface with the web including a first array of first apertures with each of the first apertures residing in a respective first depression in the web. The first depression has a first depression depth, a first depression density, a first depression open area and a first depression shape with the first array of first apertures defining a first aperture density, a first aperture open area and a first aperture shape. The web also includes a second array of second apertures with each of the second apertures residing in a respective second depression in the web. The second depression has a second depression depth, a second depression density, a second depression open area and a second depression shape. The web also includes a second array of second apertures defining a second aperture density, a second aperture open area and a second aperture shape with the second array of second apertures at least partially surrounding the first array. The second aperture depth is different from the first aperture depth, and at least one of the second aperture density and the second aperture open area respectively is different from the first aperture density and the first aperture open area. The web also includes a third array of third apertures, each of the third apertures residing in a respective third depression in the web with the third depression having a third depression depth, a third depression density, a third depression open area and a third depression shape. The third array of third apertures defines a third aperture density, a third aperture open area and a third aperture shape with the second array at least partially separating the first array from the third array.
In another embodiment of the fibrous nonwoven web at least a portion of one of the first, second and third apertures is located in or adjacent the bottom surface and at least another portion of one of the other of the first, second and third apertures is located intermediate the top surface and the bottom surface.
In a further embodiment, the fibrous nonwoven web can have at least one of the first aperture density and the first aperture open area be respectively greater than the second aperture density and the second aperture open area.
In an embodiment, the fibrous nonwoven web can have the first apertures each define a first major axis and the second apertures each define a second major axis with the second major axis being greater than the first major axis.
Also disclosed herein is an absorbent article which can include a topsheet, a backsheet and an absorbent core disposed between the topsheet and the backsheet. The absorbent article can optionally include one or more additional layers disposed between the topsheet and the absorbent core with at least a portion of the absorbent article comprising the aforementioned fibrous nonwoven web.
In another embodiment, an absorbent article is disclosed which includes a topsheet, a backsheet and an absorbent core disposed between the topsheet and the backsheet and optionally one or more additional layers disposed between the topsheet and the absorbent core. In this embodiment at least a portion of the absorbent article can comprise one of the fibrous nonwoven webs described herein with the fibrous nonwoven web including any one or more of the following features: the second aperture depth is different from the first aperture depth; at least one of the second aperture density and the second aperture open area respectively is different from the first aperture density and the first aperture open area; the second array of second apertures at least partially surrounding the first array; the second array at least partially separates the first array from the third array; the second array has a sinusoidal shape; the first array has a noncircular shape; the third array has a sinusoidal shape; the first, second and third arrays form a repeating pattern and the second and third arrays are in phase with one another; the first, second and third arrays form a repeating pattern and the second and third arrays are out-of-phase with one another; at least one of the third aperture density and the third aperture open area is respectively greater than the second aperture density and the second aperture open area; the second array completely surrounds the first array and at least one of the second aperture open area and the second depression open area is respectively less than the first aperture open area and the first depression open area; and the second array completely surrounds the first array and at least one of the second aperture shape and the second depression shape is respectively different from the first aperture shape and the first depression shape.
With any of the absorbent article combinations described herein the article can have a layer subjacent the topsheet which is darker in color than the topsheet to further assist in stain masking of fluids absorbed by the absorbent article.
In any of the fibrous nonwoven webs described herein the second array can have a sinusoidal shape, optionally, the first array can have a noncircular shape and optionally the third array can have a sinusoidal shape. Still further, the noncircular shape can comprise a leaf-like design.
In an embodiment, the fibrous nonwoven can have the first, second and third arrays form a repeating pattern with the second and third arrays being in phase with one another.
In an embodiment, the fibrous nonwoven web can have the first, second and third arrays form a repeating pattern with the second and third arrays being out-of-phase with one another.
In one embodiment the fibrous nonwoven web has at least one of the third aperture density and the third aperture open area designed to be respectively greater than the second aperture density and the second aperture open area.
In another embodiment, the fibrous nonwoven web has the second array completely surrounding the first array and at least one of the second aperture open area and the second depression open area is respectively less than the first aperture open area and the first depression open area.
In still a further embodiment the fibrous nonwoven web is designed such that the second array completely surrounds the first array and at least one of the second aperture shape and the second depression shape is respectively different from the first aperture shape and the first depression shape.
In yet another embodiment, a film layer can be substituted for the fibrous nonwoven webs described herein and the same first, second and third arrays can be utilized with the film.
A further embodiment can include a fibrous nonwoven web with a top surface and a bottom surface with the web including a first array of first apertures with each of the first apertures residing in a respective first depression in the web. The first depression has a first depression depth, a first depression density, a first depression open area and a first depression shape with the first array of first apertures defining a first aperture density, a first aperture open area and a first aperture shape. The web also includes a second array of second apertures with each of the second apertures residing in a respective second depression in the web. The second depression has a second depression depth, a second depression density, a second depression open area and a second depression shape. The web also includes a second array of second apertures defining a second aperture density, a second aperture open area and a second aperture shape with the second array of second apertures at least partially surrounding the first array. The second aperture depth is different from the first aperture depth, and at least one of the second aperture density and the second aperture open area respectively is different from the first aperture density and the first aperture open area. The web also includes a third array of third apertures, each of the third apertures residing in a respective third depression in the web with the third depression having a third depression depth, a third depression density, a third depression open area and a third depression shape. The third array of third apertures defines a third aperture density, a third aperture open area and a third aperture shape with the second array at least partially separating the first array from the third array. Still further, the fibrous nonwoven web can include any one or more of the following optional features: the second aperture depth is different from the first aperture depth; at least one of the second aperture density and the second aperture open area respectively is different from the first aperture density and the first aperture open area; the second array of second apertures at least partially surrounding the first array; the second array at least partially separates the first array from the third array; the second array has a sinusoidal shape; the first array has a noncircular shape; the third array has a sinusoidal shape; the first, second and third arrays form a repeating pattern and the second and third arrays are in phase with one another; the first, second and third arrays form a repeating pattern and the second and third arrays are out-of-phase with one another; at least one of the third aperture density and the third aperture open area is respectively greater than the second aperture density and the second aperture open area; the second array completely surrounds the first array and at least one of the second aperture open area and the second depression open area is respectively less than the first aperture open area and the first depression open area; and the second array completely surrounds the first array and at least one of the second aperture shape and the second depression shape is respectively different from the first aperture shape and the second depression shape.
Also disclosed herein is a fibrous nonwoven laminate comprising a first fibrous nonwoven web and a second fibrous nonwoven web with the second fibrous nonwoven web defining an upper surface and a lower surface. The first fibrous nonwoven web comprises any one of the aforementioned fibrous nonwoven web combinations with the bottom surface of this fibrous nonwoven web positioned adjacent the upper surface of the second fibrous nonwoven web whereby a first air gap defining a first vertical height and a second air gap defining a second vertical height are formed between the first fibrous nonwoven web and the first fibrous nonwoven web.
A full and enabling disclosure of the present invention is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:
The present disclosure is directed to a fibrous nonwoven web with multiple arrays of embossing designs at least a portion of which terminate in apertures which facilitate fluid flow through the nonwoven web. As a result, the fibrous nonwoven web has a number of applications where fluid absorption and/or transfer are involved. This is particularly true with respect to absorbent articles, wipes and cleaning products. Also disclosed is the equipment and method for making such a nonwoven web material as well as end-use products employing such a material.
Turning to
The foregoing description of an absorbent article (200) is relatively generic in design. If desired, additional optional layers may be added to the article (200) to enhance certain features of the article (200) and the overall performance. Referring to
Directly below the surge layer (203) in the direction of the Z axis there can be placed a transfer layer (205). It too can be formed from the same materials and processes as the surge layer (203) though it will typically have some degree of difference in its functionality when compared to the other layers of the article (200). For example, if the transfer layer (205) is positioned between the surge layer (203) and the absorbent core (206), it may have functionality components of both adjoining layers (203 and 206). Thus, it may have the ability to absorb fluids faster than the absorbent core (206) and its retention capability may be higher than the surge layer (203) but less than the absorbent core (206). Dimensionally, the transfer layer (205) can be as wide and long as its adjacent layers or it can be shorter in either or both directions. Such transfer layers (205), their make-up and there formation are known in the art. If desired, the transfer layer (205) can be attached or unattached to the adjoining layers by such means as, for example, adhesives, thermal and point bonding, embossing, ultrasonic bonding and hydroentangling. The absorbent core (206) may be a single layer construction or it may be made of multiple layers in which case an optional and additional layer or layers (206A) may be employed.
The absorbent core (206) can be suitably constructed to be generally compressible, conformable, pliable, non-irritating to the wearer's skin and capable of absorbing and retaining liquid body exudates. The absorbent core (206) can be manufactured in a wide variety of sizes and shapes and from a wide variety of materials. The size and the absorbent capacity of the absorbent core (206) should be compatible with the size of the intended wearer and the liquid loading imparted by the intended use of the absorbent article (200). Additionally, the size and the absorbent capacity of the absorbent core (206) can be varied to accommodate wearers ranging from infants to adults. The absorbent core (206) may have a length and width that can be less than or equal to the length and width of the absorbent article (200).
In an embodiment, the absorbent core (206) can be composed of a web material of hydrophilic fibers, cellulosic fibers (e.g., wood pulp fibers), natural fibers, synthetic fibers, woven or nonwoven sheets, scrim netting or other stabilizing structures, superabsorbent material, binder materials, surfactants, selected hydrophobic and hydrophilic materials, pigments, lotions, odor control agents or the like, as well as combinations thereof. In an embodiment, the absorbent core (206) can be a matrix of cellulosic fluff and superabsorbent material.
In an embodiment, the absorbent core (206) may be constructed of a single layer of materials, or in the alternative, may be constructed of two or more layers of materials (206 and 206A). In an embodiment in which the absorbent core (206) has two layers, the absorbent core (206) can have a wearer facing layer (206) suitably composed of hydrophilic fibers and a garment facing layer (206A) suitably composed at least in part of a high absorbency material commonly known as superabsorbent material. In such an embodiment, the wearer facing layer of the absorbent core (206) can be suitably composed of cellulosic fluff, such as wood pulp fluff, and the garment facing layer of the absorbent core (206A) can be suitably composed of superabsorbent material, or a mixture of cellulosic fluff and superabsorbent material. As a result, the wearer facing layer (206) can have a lower absorbent capacity per unit weight than the garment facing layer (206A). The wearer facing layer (206) may alternatively be composed of a mixture of hydrophilic fibers and superabsorbent material, though it is generally desirable that the concentration of superabsorbent material present in the wearer facing layer (206) be lower than the concentration of superabsorbent material present in the garment facing layer (206A) so that the wearer facing layer (206) can have a lower absorbent capacity per unit weight than the garment facing layer (206A). It is also contemplated that, in an embodiment, the garment facing layer (206A) may be composed solely of superabsorbent material without departing from the scope of this disclosure. It is also contemplated that, in an embodiment, each of the layers, the wearer facing (206) and garment facing (206A) layers, can have a superabsorbent material such that the absorbent capacities of the two superabsorbent materials can be different and can provide the overall absorbent core (206) with a lower absorbent capacity in the wearer facing layer (206) than in the garment facing layer (206A).
Various types of wettable, hydrophilic fibers can be used in any of the layers of the absorbent core (206). Examples of suitable fibers include natural fibers, cellulosic fibers, synthetic fibers composed of cellulose or cellulose derivatives, such as rayon fibers; inorganic fibers composed of an inherently wettable material, such as glass fibers; synthetic fibers made from inherently wettable thermoplastic polymers, such as particular polyester or polyamide fibers, or composed of nonwettable thermoplastic polymers, such as polyolefin fibers which have been hydrophilized by suitable means. The fibers may be hydrophilized, for example, by treatment with a surfactant, treatment with silica, treatment with a material which has a suitable hydrophilic moiety and is not readily removed from the fiber, or by sheathing the nonwettable, hydrophobic fiber with a hydrophilic polymer during or after formation of the fiber. For example, one suitable type of fiber is a wood pulp that is a bleached, highly absorbent sulfate wood pulp containing primarily soft wood fibers. However, the wood pulp can be exchanged with other fiber materials, such as synthetic, polymeric, or meltblown fibers or with a combination of meltblown and natural fibers. In an embodiment, the cellulosic fluff can include a blend of wood pulp fluff.
The absorbent core (206) can be formed with a dry-forming technique, an air-forming technique, a wet-forming technique, a foam-forming technique, or the like, as well as combinations thereof. A coform nonwoven material may also be employed. Methods and apparatus for carrying out such techniques are known in the art. Suitable superabsorbent materials can be selected from natural, synthetic, and modified natural polymers and materials. The superabsorbent materials can be inorganic materials, such as silica gels, or organic compounds, such as cross-linked polymers. Cross-linking may be covalent, ionic, Van der Waals, or hydrogen bonding. Typically, a superabsorbent material can be capable of absorbing at least about ten times its weight in liquid. In an embodiment, the superabsorbent material can absorb more than twenty-four times its weight in liquid. Examples of superabsorbent materials include polyacrylamides, polyvinyl alcohol, ethylene maleic anhydride copolymers, polyvinyl ethers, hydroxypropyl cellulose, carboxymal methyl cellulose, polyvinylmorpholinone, polymers and copolymers of vinyl sulfonic acid, polyacrylates, polyacrylamides, polyvinyl pyrrolidone, and the like. Additional polymers suitable for superabsorbent material include hydrolyzed, acrylonitrile grafted starch, acrylic acid grafted starch, polyacrylates and isobutylene maleic anhydride copolymers and mixtures thereof. The superabsorbent material may be in the form of discrete particles. The discrete particles can be of any desired shape, for example, spiral or semi-spiral, cubic, rod-like, polyhedral, etc. Shapes such as needles, flakes, and fibers are also contemplated for use herein. Conglomerates of particles of superabsorbent materials may also be used in the absorbent core (206).
The absorbent core (206) can be superposed over the backsheet (204) and can be bonded to the backsheet (204), such as by being bonded thereto with an adhesive. However, it is to be understood that the absorbent core (206) may be in contact with, and not bonded with, the backsheet (204). In an embodiment, a layer, such as but not limited to, a core wrap, can be used to partially or completely envelope the absorbent core (206) layer or layers.
If desired, the absorbent core (206) can optionally be partially or wholly enveloped by what is termed a core wrap (not shown in the drawings), the primary function of which is to contain the materials forming the absorbent core (206), especially when materials such as superabsorbent particles are being used to absorb body exudates. The core wrap can be in contact with and if desired, bonded to the absorbent core (206). Bonding of the core wrap to the absorbent core (206) can occur via any means such as, but not limited to, adhesives. The core wrap may be composed of separate sheets of material which can be utilized to partially or fully encompass the absorbent core (206) and which can be sealed together using a sealing means such as an ultrasonic bonder or other thermochemical bonding means or by the use of an adhesive. The core wrap can include, but is not limited to, natural and synthetic fibers and can be made to be more or less hydrophilic through the use of surfactant chemicals such as are known in the construction of such materials. Suitable materials include, but are not limited to, tissue wraps and meltblown fibrous nonwoven webs.
The backsheet (204) can be breathable and/or liquid impermeable. The backsheet (204) can be elastic, stretchable or non-stretchable. The backsheet (204) may be constructed of a single layer, multiple layers, laminates, spunbond fabrics, films, meltblown fabrics, elastic netting, microporous webs, bonded-carded webs or foams provided by elastomeric or polymeric materials. For example, the backsheet (204) can be constructed of a microporous polymeric film, such as polyethylene or polypropylene or it can be such a film laminated to a fibrous nonwoven web such as a layer of spunbond or a bonded carded web made from, for example, polyolefins such as polyethylene or polypropylene. In an embodiment, the backsheet (204) may be a two layer construction (not shown), including an outer layer material and an inner layer material which can be bonded together such as by a laminate adhesive. Suitable laminate adhesives can be applied continuously or intermittently as beads, a spray, parallel swirls, or the like. In addition, the inner layer can be bonded to the outer layer utilizing ultrasonic bonds, thermal bonds, pressure bonds, or the like. The outer layer of the backsheet can be any suitable material and may be one that provides a generally cloth-like texture or appearance to the wearer. An example of such material can be a polypropylene bonded-carded web. Another example of material suitable for use as an outer layer of a backsheet (204) can be a spunbond polypropylene non-woven web.
The liquid impermeable inner layer of the backsheet (204) (or the liquid impermeable backsheet (204) where the backsheet (204) is of a single-layer construction) can be either vapor permeable (i.e., “breathable”) or vapor impermeable. The liquid impermeable inner layer (or the liquid impermeable backsheet (204) where the backsheet (204) is of a single-layer construction) may be manufactured from a thin plastic film, although other liquid impermeable materials may also be used. The liquid impermeable inner layer (or the liquid impermeable backsheet (204) where the backsheet (204) is of a single-layer construction) can inhibit liquid body exudates from leaking out of the absorbent article (200) and wetting articles, such as bed sheets and clothing, as well as the wearer and caregiver.
Where the backsheet (204) is of a single layer construction, it can be embossed and/or matte finished to provide a more cloth-like texture or appearance. The backsheet (204) can permit vapors to escape from the absorbent article (200) while preventing liquids from passing through. A suitable liquid impermeable, vapor permeable material can be composed of a microporous polymer film or a non-woven material which has been coated or otherwise treated to impart a desired level of liquid impermeability.
The topsheet (202) of the absorbent article (200) may be made from a variety of materials including fibrous nonwoven webs and apertured films, both of which may employ the aperture-embossed pattern shown from the front in
While the aperture-embossed pattern of
In the embodiment shown in
The fibrous nonwoven web (20) of the present invention can be prepared from non-continuous fibers (such as staple fibers), continuous filaments (such as meltblown and spunbond fibers) as well as combinations thereof. Other shorter fibers, such as pulp fibers can also be used. The production methods that may be employed include, but are not limited to, dry staple processes such as carded web techniques (hot thru-air bonded carded web and thermal bonded carded web techniques), meltblowing processes, spunbond processes, hydroentangling process and generally any wet or dry forming processes as well as other fiber extrusion processes. Through air bonded carded webs (TABCW) are particularly well-suitable as they can form bulky webs which include large quantities of vacant, interstitial spaces between the fibers to create a low-density web. As a result, when the depressions and apertures are formed, the resultant web has a more three-dimensional look and feel due to the increased depth and fluids imparted to the web can be quickly absorbed and passed to subjacent layers. The fibers forming the webs can be made from both natural and synthetic materials. Suitable polymers for fiber formation include, but are not limited to, thermoplastic polymeric materials such as polyolefins including, for example, polyethylene and polypropylene as well as polyamides, polyesters and the like. The fibers can be solid or hollow core fibers, shaped fibers, single polymer/component fibers as well as multi-constituent fibers such as bicomponent fibers. The same materials, fibers and webs and web-forming techniques used to form the web (20) and topsheet (202) can be employed for the subjacent layers (203), (205) and vice versa.
Turning to
In one embodiment, to form the visually distinct pattern shown in
As described above, the aperturing and embossing pattern shown in
The wave length of the sine waves used in the arrays (40) and/or (50) can range from about 20 to about 50 millimeters and alternatively from about 30 to about 40 millimeters though wavelengths outside this range are also possible depending on the particular end use. The peak-to-peak wave amplitude can range from about 3 to about 30 millimeters and alternatively from about 5 to about 15 millimeters though amplitudes outside this range are also possible depending on the particular end use.
The number of repeating sinusoidal patterns in a particular array can also be varied. For example, in
Again referring to
The spacing between arrays ((30), (40) and (50)) can be varied. If desired, areas with no embossing and/or aperturing (also sometimes referred to as land area) can be interposed between arrays or within arrays.
The size and shape of the leaf-type pattern in the first array (30) can be varied as to design and shape. Generally the length of the leaf-type shapes will range from about 5 to about 40 millimeters, alternatively from about 10 to about 25 millimeters. Generally, the width of the leaf-type shapes will range from about 3 to about 25 millimeters, alternatively between about 5 and about 15 millimeters. Other sizes can be used depending upon the particular end use of the material.
It should be understood that the fibrous nonwoven web (20) and the individual arrays are not limited to the specific designs shown herein. Each of the arrays can take on a variety of shapes and sizes and fulfill the requirements of the present invention. While the aperturing and embossing pattern shown in
Turning to
Spacing between apertures/depressions within an array can be varied in any direction. Generally, edge-to-edge spacing between depressions as measured at the top surface (22) will range between about 1.0 and about 4.0 millimeters, alternatively between about 1.0 and about 3.0 millimeter, and still further between about 2.0 and about 4.0 millimeters.
The plane of the bottom surface (24) of the fibrous nonwoven web (20) will be defined, at least in part, by the termination point of the depressions with their open apertured ends. Depending on the degree of taper and the depth of the depressions, some of the depressions, with or without apertures, may terminate in and define the plane of the bottom surface (24) of the fibrous nonwoven web (20) while other depressions may terminate at a location intermediate the top surface (22) and the bottom surface (24). In some instances it may be the case that the depressions and apertures within one array partially or as a whole are deeper than the depressions and apertures in another array. For example, with respect to the aperturing and embossing design shown in
To demonstrate the improved fluid handling and stain masking characteristics of the fibrous nonwoven web (20) described herein, three absorbent articles (200) were made with identical constructions except for the topsheet (202). The absorbent articles (200) were in the form of sanitary napkins similar in design to those shown in
Positioned on top of the airlaid upper layer (206) was a smaller two layer TABCW transfer layer (205) in which the upper layer was printed with a purple color so as to be visible through the topsheet (202). Positioned between the purple transfer layer (205) and the topsheet (202) was a surge layer (203) which was also a TABCW structure. The addition of color was different from the commercially available product. Having one of the subjacent layers be darker in color from the layers above served the function of improving the overall stain masking function of the absorbent article (200) and this was evident in all three of the example products shown in
The topsheet on the product shown in
The overall product was embossed with channels (220) as shown in
The second example (
The third example (
To demonstrate the difference in the fluid handling properties of the three examples shown in
The results of the fluid depositions are shown schematically in
The absorbent article examples described above were evaluated with respect to one another and the products employing the fibrous nonwoven web (20) according to the present invention (
Based upon the foregoing information and testing it was demonstrated that improved fluid intake and stain masking as well as other comfort benefits could be achieved when a fibrous nonwoven web according to the present invention was used as a topsheet in conjunction with a personal care absorbent article such as, for example, a feminine hygiene product including a sanitary napkin. It is believed that the improved performance was based on creating a topsheet with three or more different arrays of apertures with varying densities. In addition, by providing embossed depressions with differing vertical heights as measured along the vertical or Z axis (the direction normal to the plane of the product when laid flat), increases in fluid handling were achieved. These differences in vertical height were the result of the size and the depth of the depressions that were created by the embossing and aperturing pins used to form the combination depressions and apertures in in the various arrays of the fibrous nonwoven web (20).
As can be seen in
Generally, the total open area of the first apertures (32) per unit area of the first array (30) of the nonwoven web (20) should be between about 2 and about 20 percent, alternatively between about 3 and about 10 percent and still further between about 4 and about 6 percent. Generally and independent of the first array (30) the total open area of the second apertures (42) per unit area of the second array (40) of the nonwoven web (20) should be between about 1 and about 10 percent, alternatively between about 1 and about 4 percent and still further between about 2 and about 3 percent. Generally and independent of the first array (30) and the second array (40), the total open area of the third apertures (52) per unit area of the third array (50) of the nonwoven web (20) should be between about 2 and about 20 percent, alternatively between about 6 and about 11 percent and still further between about 8 and about 9 percent. Because the apertures themselves reside below the plane of the top surface (22) of the fibrous nonwoven web (20) which forms the topsheet (202), it should be noted that these open areas are for the apertures ((32), (42), (52)) themselves at the bottom of the depressions ((34), (44), (54)) as compared to the total surface area of the array ((30), (40), (50)) being used to calculate the percent open area including the area of the openings in the top surface (22) formed by the depressions ((34),(44),(54)) formed within the particular array ((30), (40), (50)) and the land area between the depressions. Thus, the percent open area would be the total area of the collective apertures divided by the total area of the portion of the array being measured with the quotient being multiplied by 100 to yield the percentage. Note that within an array if any portion of the area or an array chosen meets these parameters, the array as a whole is considered to meet these parameters.
Generally, the total open area of the first depressions (34) per unit area of the first array (30) of the nonwoven web (20) should be between about 3 and about 25 percent, alternatively between about 5 and about 13 percent and still further between about 8 and about 9.5 percent. Generally and independent of the first array (30) the total open area of the second depressions (44) per unit area of the second array (40) of the nonwoven web (20) should be between about 2 and about 30 percent, alternatively between about 5 and about 20 percent and still further between about 10.5 and about 12.5 percent. Generally and independent of the first array (30) and the second array (40), the total open area of the third depressions (54) per unit area of the third array (50) of the nonwoven web (20) should be between about 5 and about 25 percent, alternatively between about 12 and about 18 percent and still further between about 14 and about 16 percent. The percent open area in an array ((30), (40), (50)) is the total surface area of the depressions as measured at the top surface (22) formed by the depressions divided by the total surface area of the top surface (22) of the portion of array being used with the quotient being multiplied by 100 to yield the percentage. Note that within an array if any portion of the area or an array chosen meets these parameters, the array as a whole is considered to meet these parameters.
When describing the dimensions of the apertures and depressions, in addition to open area of the individual apertures and depressions, the size of the apertures and depressions can be quantified in the context of the major axis of the particular aperture or depression. The “major axis” is the length of the longest interior line that can be drawn between two points on the edge of the aperture (or depression when measuring depressions as opposed to apertures) without intersecting or touching a third point on the edge of the aperture (or depression). The major axis of the aperture is measured across the aperture in the bottom of the depression. The major axis of the depression is measured at the top surface (22) of the fibrous nonwoven web (20) which in the product embodiments is the top surface of the topsheet (202). Thus, in the first array (30), the first aperture (32) will have a first major axis and the first depression (34) will have a first major axis. Likewise, the second aperture (42) and the second depression (44) in the second array (40) will each have a second major axis to distinguish them from the first major axes of the first array (30) and the third aperture (52) and the third depression (54) in the third array (50) will each have a third major axis.
Generally, the first major axis of the first apertures (32) in the first array (30) should be between about 0.3 and about 5.0 millimeters, alternatively between about 1.0 and about 2.0 millimeters. Generally and independent of the first array (30), the second major axis of the second apertures (42) in the second array (40) should be between about 0.3 and about 5.0 millimeters, alternatively between about 1.0 and about 3.0 millimeters and still further between about 1.2 and about 2.5 millimeters. Generally and independent of the first array (30) and the second array (40), the third major axis of the third apertures (52) in the third array (50) should be between about 0.3 and about 5.0 millimeters, alternatively between about 1.0 and about 3.0 millimeters and still further between about 1.0 and about 2.0 millimeters. Note that within an array if any portion of the area or an array chosen meets these parameters, the array as a whole is considered to meet these parameters.
As to all the apertures, note that the aperture sizes and shapes can be varied in many ways. In addition to different sized apertures from one array to another, the apertures in one array may have different sizes as well as different shapes. Further the shapes of the apertures can be of any shape or combination of organic and geometric shapes including, but not limited to, circles, ovals, rectangles, squares, diamonds, polygons and irregular-shaped apertures and this is true within an array or as between arrays. Organic shapes are shapes with a natural look and a flowing and curving appearance. For this reason, they are often also referred to as curvilinear shapes. Examples of organic shapes include the shapes of leaves, plants, and animals.
Generally, the first depressions (34) in the first array (30) formed by the embossing should have a first major axis in the top surface (22) of the fibrous nonwoven web (20) between about 0.3 and about 6 millimeters, alternatively between about 1.0 and about 3.5 millimeters and still further between about 1.0 and about 2.4 millimeters. Generally and independent of the first array (30), the second major axis of the second depressions (44) in the second array (40) should be between about 1.0 and about 8.0 millimeters, alternatively between about 2.0 and about 6.0 millimeters and still further between about 3.0 and about 5.0 millimeters. Generally and independent of the first array (30) and the second array (40), the third major axis of the third depressions (54) in the third array (50) should be between about 0.3 and about 6.0 millimeters, alternatively between about 1.0 and about 3.5 millimeters and still further between about 1.0 and about 2.4 millimeters. Note that within an array if any portion of the area or an array chosen meets these parameters, the array as a whole is considered to meet these parameters.
As to all the depressions formed by the embossing, note that the depression sizes and shapes can be varied in many ways. In addition to different sized depressions from one array to another, the depressions in one array may have different sizes as well as different shapes. Further the shapes of the depressions can be of any shape or combination of organic an geometric shapes including, but not limited to, circles, ovals, rectangles, squares, diamonds, polygons and irregular-shaped apertures and this is true within an array or as between arrays. Organic shapes are shapes with a natural look and a flowing and curving appearance. For this reason, they are often also referred to as curvilinear shapes. Examples of organic shapes include the shapes of leaves, plants, and animals.
Generally the basis weight of the fibrous nonwoven web (20) will be between about 20 and about 50 grams per square meter (gsm), alternatively between about 20 and about 35 gsm. This is especially true when the fibrous nonwoven web (20) is being employed as a topsheet or other layer for an absorbent article though basis weights outside these ranges are also possible.
In addition to the foregoing, the fibrous nonwoven webs (20) of the present invention were observed to have a number of desired functions including improved absorbency, improved breathability and a bulkier and thicker feel. The fibrous nonwoven webs (20) were also perceived to be more three-dimensional in design and aesthetically more feminine looking than conventional designs such as shown in
The equipment and process used to form the fibrous nonwoven web (20) resulted in a single step process wherein both the embossed depressions and the apertures were formed in each array in one step. This was accomplished by using a mating male and female roll with the male roll having the pattern shown, for example, in
The embossed depressions and apertures were formed by creating raised areas on the surface of the male role with aperturing pins located on the distal ends of the raised areas. In the case of the first depressions (34) and the third depressions (54) the raised areas were a generally circular design with a diameter, adjacent the base or proximal ends of the raised areas (adjacent the exterior surface of the male roll), of 1.6 millimeters. The raised areas tapered to a point and had a vertical height of 3.0 millimeters. An enlarged view of the resultant aperture and depression formed by these raised areas on the male roll is shown in
In the case of the second depressions (44) the raised areas were of a racetrack design with straight sides and curved ends with a length, adjacent the base or proximal ends of the raised areas (adjacent the exterior surface of the male roll), of 2.9 millimeters and a width of 1.7 millimeters. The raised areas tapered in size towards their distal ends and had a vertical height or 3.0 millimeters. The distal ends of the of the raised areas were capped with elongated knife-like edge with a width of approximately 1.2 millimeters. An enlarged view of the resultant aperture and depression formed by these raised areas on the male roll is shown in
Comparing the depressions and apertures of
Due to the difference in vertical height of the raised areas on the male roll, at least a portion of some of the apertures from the first (30), second (40) and third (50) array will terminate in or adjacent and help define the bottom surface (24) of the fibrous nonwoven web (20). Further, due to the fact that other raised areas on the male roll will have a shorter vertical height, at least a portion of one of the other of the apertures in the first (30), second (40) and third (50) arrays will terminate and therefore be located intermediate the top surface (22) and the bottom surface (24) of the fibrous nonwoven web (20). This in turn helps with air circulation below the bottom surface (24) of the fibrous nonwoven web (20). In addition, that portion of the apertures that are intermediate the top surface (22) and bottom surface (24) will be located above that portion of the apertures that reside in or adjacent the bottom surfaced (24).
The male and female rolls were both driven at the same speed by electric motors. If desired, either or both of the male and female rolls can be heated or cooled to improve the aperturing and embossing process.
While performing the embossing and aperturing in a single step was a preferred process, it is also possible to perform the various steps separately. For example, the embossing could be done first and the aperturing second or vice versa. Additionally, the embossing and aperturing steps for each of the arrays could be done separately though this is considered to be a more complicated process due to indexing and other issues.
Once the fibrous nonwoven web (20) has been formed, it can be directed immediately into a production process such as the formation of a personal care absorbent article 200 such as is shown in
In addition to being formed either in-line or off-line, the fibrous nonwoven web (20) may be subjected to further processing such as, for example, formation into a fibrous nonwoven laminate (300) as described herein and shown in the photo of
The first air gaps (310) will define a first vertical height (311) and the second air gaps (312) will define a second vertical height (313). Depending on the vertical heights of the first (34), second (44) and third (54) depressions, these vertical heights (311) and (313) may be equal to, greater than or less than one another. In addition, when one or more of the arrays ((30), (40), (50)) are formed in the sinusoidal or other continuous form such as is shown in the drawings, one or more of the air gaps ((310), (312)) may also form air channels that extend along all or a portion of the laminate (300). A laminate (300) as described above can also be used as a topsheet (202) or as one of the other layers for an absorbent article (200). The advantage of this material is that it is able to provide increased thickness or bulk as the same basis weight as with other more two-dimensional materials while also improving breathability and decreasing skin contact on the top surface (22) of the web (20) due to the open area provided by the arrays of apertures and depressions.
While the fibrous nonwoven web (20) has been described herein primarily in the context of its use with absorbent articles, wipes and cleaning products, it should be appreciated that it can be used in any applications where a material with such arrays of apertures and depressions can provide beneficial results either alone or as a part or component of an overall product.
It will be recognized that the present invention is capable of many modifications and variations without departing from the spirit and scope thereof. Accordingly, the detailed description and examples set forth herein are meant to be illustrative only and are not intended to limit, in any manner, the scope of the invention as set forth in the appended claims.
This application claims the benefit of priority from U.S. Provisional Application No. 61/817,009 filed on Apr. 29, 2013.
| Number | Date | Country | |
|---|---|---|---|
| 61817009 | Apr 2013 | US |
