The embodiments relate generally to formed films configured to be used in absorptive articles and more particular to a formed film having a base pattern and visible design separately defined at the cellular level. The embodiments further relate to articles that include films of the foregoing nature, as well as methods and structures for manufacturing formed films.
Absorptive articles, such as diapers, feminine napkins, panty liners, incontinence inserts, breast pads, bed pads, ground covers for weed prevention, hygienic or household wipes, and the like, have been utilized that incorporate one or more layers of formed film. The formed film layers have been proposed in a variety of constructions.
The term “film” as used throughout shall refer to thermoplastic polymer webs made from any variety of processes, for example but not limited to thermoplastic polymer webs made from cast and blown extrusion processes. The term “formed film” as used throughout shall refer to films produced by any one of several forming methods. Some exemplary forming methods involve placing a formable web in contact with a forming cylinder having a pattern of perforations or indentations.
Extrusion processes may be used to create a roll of precursor film that is then formed through one of several processes, such as reheat vacuum formed film (RHVFF), direct melt vacuum formed film (DMVFF), hydrojet formed film (HFF), vacuum formed film (VFF) processes and the like. In the DMVFF, RHVFF and VFF processes, the film is fed across a forming cylinder while a pressure differential (e.g., vacuum) is applied. The pressure differential draws the film onto the forming cylinder thereby forming a pattern in or through the film corresponding to the pattern of the forming cylinder. In the HFF process, high-pressure liquid jets are utilized to form the pattern in or through the film.
The patterns on the film are comprised of cells that are grouped into repeating arrangements with the groups of cells nested within one another. Cells of similar shape and size that interconnect in a network are generally referred to as a base pattern. Once a desired base pattern is formed on the film, the film may be combined with various layers of other materials to form a variety of articles.
Absorptive articles have been proposed that contain designs on the surface, where the design is intended to afford an appealing cosmetic appearance, such as to create an association with commonly known items that are fresh, feminine and pleasant, such as flowers. On baby diapers, for example, teddy bears, stars, moons and toys such as rattles and blocks are commonly printed on the backsheet or outer covering.
Heretofore, the designs have been placed on the top side of absorptive articles, visible prior to using the device, through embossing methods. An embossing method generally involves, utilizing heat and pressure, to set a specific design into the surface of a pad. Once the heated, pressurized pad receives the design, the pad is cooled. However, conventional embossing methods have experienced certain drawbacks and limitations.
A need remains for a formed film that includes both a base pattern and visible design. Needs also remain for articles incorporating such formed films and for methods and structures to produce such formed films.
A formed film is provided having a base pattern defined by base cells. The formed film also includes a visible design defined by a series of design cells arranged successively with one another along a contour defining a perimeter of the visible design. The design cells and base cells are positioned in an intervening manner with one another to incorporate the visible design into the base pattern.
An absorbent article is provided that includes a formed film having a base pattern defined by base cells. The formed film also includes a visible design defined by a series of design cells arranged successively with one another along a contour defining a perimeter of the visible design. The design cells and base cells are positioned in an intervening manner with one another to incorporate the visible design into the base pattern.
A forming screen is provided adapted to produce a formed film. The screen includes a mesh body containing a screen base pattern and a screen visible design incorporated within the screen. The screen base pattern is defined by base openings through the mesh body of the screen. The screen visible design is defined by a series of design openings through the mesh body of the screen. The design openings are arranged successively with one another along a contour defining a perimeter of the visible design. The design openings and base openings are positioned in an intervening manner with one another to incorporate the screen visible design into the screen base pattern.
The base and design cells 21 and 23 may constitute apertures extending entirely through the film segment 10 or may be non-perforating thereby only forming a depression into the film segment 10 with the valley of each depression being closed or covered by a membrane.
As used throughout, the term “cell” shall mean an individual depression having a geometric shape defined by the perimeter of the depression. Cells may open entirely through the film segment 10 or may be non-perforating or unapertured. When fluid acquisition is involved, the depression is in the direction away from the side of the material, which will be exposed to the vision of the user and, while in use, contact the user. If a fluid barrier is involved the direction of the depression is optional.
As used throughout, the term “diameter” shall mean the lineal measurement of the major axis of a geometric shape of a cell. Whereas a circle, a square or an equilateral hexagon will have substantially equal measurements in both axes, other suitable geometric shapes shall have a major and a minor axis. The smaller cells may define the base pattern and the larger cells may define the visible design. The ‘diameter’ of significance is in the major axis measurement. The larger cells defining the perimeter of the visible design 12 may also be accentuated by being elongated, in which case the major axis shall determine the ‘diameter’.
As used throughout, the term “base pattern” shall mean a group of one or more cells arranged in a repeating pattern where the groups of cells are nested in close proximity to one another to form an interconnected network. A film may have one or more base patterns. A base pattern may comprise cells of one or more size and/or geometric shape.
As used throughout, the term “visible design” shall mean a recognizable design defined by a series of similar cells. More than one size and shape of cells may be utilized to define the visible design. Examples of visible designs include hearts, roses, ribbons, flowers, toys, moons, stars and the like, or repeating patterns such as wavy lines, herringbone lines, chevrons and the like. The visible design has a perimeter set forth by a series of sequential aligned design cells. In the exemplary embodiments set forth hereafter, the interior area of the visible designs is wholly filled with base cells. Optionally, the interior area of some or all of the visible designs may be filled wholly or partially with design cells as well. Optionally, the interior area of some or all of the visible designs may be filled wholly or partially with filler cells having a size and/or geometric shape that differs from the base cells outside the visible design and that differs from the design cells arranged along the perimeter of the visible design.
The size and/or geometric shape the design cells is visibly distinct from the size and/or geometric shape of the base cells defining the base pattern. The perimeter of a visible design may be open such as in a wavy line, or it may be closed such as in a heart shape design. The visible design may be repeated at regular intervals to form a visible design pattern (e.g., a series of hearts arranged in rows or columns).
As shown in
The geometry of the base cells 21 used to form the base pattern 11 may or may not be the same. Preferably, diameters of the base cells 21 may be equivalent among the interconnected base cells 21 forming a cluster. Depending upon the difference in size between the base and design cells 21 and 23, it may be preferable that the geometries differ between the base and design cells 21 and 23. In the event that similar geometric shapes are used for the base and design cells 21 and 23, the size of design cells 23 should different sufficiently from the size of the base cells 21 to afford a desired contrast there between that is readily visible to a viewer at one to three feet.
By way of example only, a design cell 23 of a size (e.g., area or diameter) at least 2.00 to 3.00 times larger than the base cell 21 affords sufficient contrast to distinguish the base pattern 11 from the visible design 12. Preferably, the design cell 23 may have a diameter ranging anywhere between 2.25 and 2.50 times larger than that of the base cell 21, and most preferably the design cell 23 may have a diameter ranging anywhere between 2.00 and 2.25 times larger than the diameter of the base cell 21. Typically the design cell 23 size is at least about 2.00 times larger than the base cell 21 size, but may be greater than three times larger, such as four times or five times.
The film segment 10 may be utilized with a variety of articles.
The absorbent article 100 has two surfaces, namely a body contacting surface or body surface 118 and a garment contacting surface or garment surface 120. The body surface 118 is intended to be worn against the body of the wearer. The garment surface 120 of the absorbent article 100 is on the opposite side and is intended to be placed adjacent to the wearer's undergarments or clothing when the absorbent article 100 is worn.
The absorbent article 100 includes two center lines, a longitudinal center line 122 and a transverse center line 124. The absorbent article 100 has two spaced apart longitudinal edges 126 and two spaced apart transverse or end edges 128, which together form the periphery 130 of the absorbent article 100. The absorbent core 116 has a top or body facing side 117 (
Topsheet 112 may be compliant, soft feeling and non-irritating to the wearer's skin. The topsheet 12 may be liquid permeable, permitting liquids to readily penetrate through its thickness. The topsheet has a body facing side 133 and a garment facing side 134, two longitudinal or side edges 136 and two end edges 138.
The topsheet 112 may be made of a non-woven material or a vacuum formed film layer, such as film segment 10 (
The topsheet 112 may be any non-woven fabric that is permeable to liquids. A suitable non-woven fabric may be manufactured from a variety of materials including natural fibers (e.g., wool or cotton fibers), synthetic fibers (e.g., polyester, polypropylene) or a combination thereof. The topsheet 112 may be formed from fibers selected from the group consisting of polypropylene, polyester, polyethylene, polyvinylalcohol, starch-based resins, polyurethanes, cellulose and cellulose esters.
Various manufacturing techniques may be used to manufacture no-woven fabric for use in the topsheet 112. For example, the non-woven fabric may be resin bonded, needle punched, spun-bonded, or carded. Carded non-woven fabrics may be thermally bonded, air-thru bonded and spun-laced fabrics. An exemplary non-woven fabric may be a thermally bonded polypropylene fabric.
An exemplary topsheet 112 is a non-woven fabric having a pattern of thermal bond sites. One example of a non-woven fabric has a carded thermally dot-bonded polypropylene web. The thermal bonds of such a fabric are typically rectangular in shape in plan view. The bonds are typically arranged in staggered rows. Another typical non-woven is a spun-bonded polypropylene web with similarly arranged thermal bonds. Still another typical non-woven fabric is a carded polypropylene web that is embossed in accordance with the method taught in U.S. Pat. No. 4,781,710 issued to Megison, et al. This non-woven fabric has embossed and thermal bonded areas that are diamond-shaped in plan view. The diamond-shaped bonds are spaced apart and arranged in a diamond-shaped grid such as is shown in
Preferably, acquisition distribution layer 115 is a perforated thermoplastic film with tapered capillaries which has a run off percent of less than about 10 percent and which has an increased liquid flow rate through the tapered capillaries. The method of making such a film includes a two-fold surface treatment, which is taught by U.S. Pat. Nos. 4,535,020 and 4,456,570 to Thomas et al. entitled, “Perforated Film” and “Treatment of Perforated Film”, respectively. U.S. Pat. Nos. 535,020 and 4,456,570 are incorporated herein by reference. The method teaches that one surface treatment is provided by adding an internal chemical additive, namely a surfactant, to a film forming polyolefin resin. The additive is compounded or otherwise mixed or blended with the resin prior to the film being formed from the resin. After the film is formed the other surface treatment is accomplished by treating the film with a corona discharge treatment, which acts on the chemical additive to provide the perforated film with a zero or near zero percent run off.
The surfactant provides a film surface, which has greater polarizability than the polyolefin film would have without the surfactant being added. Higher surface polarity yields higher wettability. Although the chemically treated film is more polar than untreated film, corona discharge treatment of the film itself provides the desired maximum wettability. Any surfactant which achieves this polarity and which migrates to the surface of the film may be used in the embodiments.
Optionally, the article may be constructed with a layer in the area beneath the topsheet and on top of the core, which provides for both the acquisition and the distribution of fluids, especially secondary fluids that are introduced after initial fluids have previously been absorbed.
Optionally, the film segment discussed above may be used as the topsheet of the article. Here the aesthetically pleasing appearance of a formed film topsheet with visible designs can be well detected. Optionally, the film segments may also serve as part of the acquisition distribution layer. In order for the visible design to remain visible, the topsheet would be translucent. A topsheet may be, but is not limited to, a commonly used nonwoven. The denier and basis weight and fiber diameter of the nonwoven is selected such that the topsheet is translucent to the layer beneath it. A layer of formed film may also be used as the topsheet in this construction. The pigmentation and gauge of the topsheet can be formulated to make the topsheet translucent to the layer underneath it. If desired a topsheet and an acquisition distribution layer comprised of the formed film such as in
Optionally, the formed film may also be used as part of the backsheet barrier layer, in which case the formed film would be unapertured as a barrier layer.
Forming the large diameter cells in a drawn design can be achieved by any of several means. The most common means are those described above where RHVFF, DMVFF, VFL and HFF processes are discussed for the making of formed films. These processes may utilize a formed film pattern cylinder apparatus typically called a “screen”. Screens can be made by several means. Electroplated screens are preferred but screens can be made by etching or laser cutting cylinders. Patterned plates can also be formed by these means, which are then bent and welded into cylinders. Screens can be single ply or multiple plies. Screens can be designed to incorporate the base pattern and visible designs of
While making the formed film segments of
The screen visible design 212 is defined by a series of design openings 223 aligned in series and spaced from one another in a desired arrangement to outline the perimeter of the desired design. The relative orientation and relation of the design openings 223 mirrors that described above in connection with the design cells 23 illustrated in
The screen 200 is comprised of a mesh body 229 formed of interconnecting links 231 surrounding the base and design openings 221 and 223.
The screen 200 is formed upon a cylinder or drum. A film web is introduced onto the screen 200 in a state susceptible to defamation. A pressure differential is introduced across the screen 200, such as having a vacuum drawn inward through the screen toward the central region of the cylinder. As the web is rolled over the screen 200, the pressure differential draws the web down onto the mesh body 229 and into the base and design openings 221 and 223. Should it be desired to form depressions in the web, a lesser pressure differential is utilized. In the event that it is desired to form apertures entirely through the web, a greater pressure differential is utilized.
Once the pattern is formed in the web and the web is removed from the screen 200, the resulting product constitutes a film segment such as illustrated above in connection with
The foregoing methods and structures form films having visible designs incorporated into a base pattern, in which the design cells and base cells are positioned in an intervening manner with one another.
In the exemplary embodiments, two levels of distinction are provided on the film, namely an array of visible designs (defining one level of distinction) and a base pattern (defining another level). Optionally, more than two levels may be incorporated into the film. To incorporate more than two levels, mid-level cells may be interleaved with the design cells and base cells. The mid-level cells would have a shape and/or size that is visibly distinct from the shape and/or size of the base cells and from the shape and/or size of the design cells.
While the various specific embodiments have been described herein, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.
This patent application claims the benefit of priority under 35 U.S.C. 119(e) from U.S. provisional application 60/561,446, entitled “FORMED FILM HAVING A CELLULARLY DEFINED BASE PATTERN AND VISIBLE DESIGN,” filed on Apr. 12, 2004, by Paul E. Thomas and assigned to Tredegar Film Products, which disclosure is incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
60561446 | Apr 2004 | US |