US3262451A - Nonplanar absorbent fibrous pads - Google Patents

Description

July 26, 1966 E. A. MORSE NONPLANAR ABSORBENT FIBROUS PADS 5 Sheets-Sheet 1 Filed Sept. 13, 1962 lNvENToR farm/e0 A. we: BY 0| [3,,

ATTORNEY July 26, 1966 E. A. MORSE NONPLANAR ABSORBENT FIBROUS PADS 3 Sheets-Sheet 2 Filed Sept. 13, 1962 INVENTOR. 4 0M420 ,4 M0225 BY 30* ATTORNEY July 26, 1966 E. A. MORSE 3,262,451

NONPLANAR ABSORBENT FIBROUS PADS Filed Sept. 13, 1962 T'aqE.

5 Sheets-Sheet 3 ATTORNEY United States Patent 3,262,451 N UNPLANAR ABSORBENT FIBROUS PADS Edward A. Morse, Fanwood, N.J., assignor to Johnson & Johnson, a corporation of New Jersey Filed Sept. 13, 1962, Ser. No. 223,488 12 Claims. (Cl. 128-290) This invention relates to preformed articles and more particularly to preformed nonplanar articles containing one or more relatively thick layers of fibrous material for absorbing or padding purposes.

Many different types of articles containing relatively thick layers of fibrous material are used on the body for surgical purposes, for absorbent purposes, as padding, and the like. Examples of such articlesare absorbent dressings, which are used for absorbing the exudate of wounds, sanitary napkins, which are used to absorb menstrual fluid, and lactation pads, which are used to absorb lacteal fluid. In the making of casts for setting broken bones, a fibrous padding is often placed between portions of the cast and the part of the body being placed in the cast.

Usually, such articles are made in a flat or planar form. However, in order to function properly, the articles should be held in intimate contact with the body. In most instances, the configurations of the particular parts of the body against which they are placed in use are not flat. Therefore, in order for the articles to be held in intimate contact with such body parts, they must be distorted from their original planar configurations which are nonplanar. For example, sanitary napkins are customarily made in a flat, rectangular shape. However, the configuration of the vaginal area against which they are placed in use is arcuate. Therefore, the napkins must be distorted from their flat shape into one which approximates the arcuate configuration of the vaginal area. Lactation pads for absorbing lacteal fluid, usually originally flat, are distorted in use into a generally hemispherical shape to conform them to the chest contours.

Distorting of such originally planar articles into shapes which are nonplanar often results in discomfort and in an impairment of their function, particularly if they are used for absorbent purposes. These articles are customarily made from one or more layers of fibrous materials usually enclosed within a woven or non-woven fabric cover. When distorted, the layers are folded and creased. These folds and creases may not only cause discomfort, but may also effect the absorbing effectiveness ofthe article. It would be desirable, therefore, to provide such articles in a preformed shape to eliminate the necessity for distortion.

I have discovered that preformed, nonplanar articles of the foregoing type may be simply and economically provided through the use of shinkable, orientated plastic materials in the form of films, filaments, bands, yarns, webs and the like. The articles may be made by securing to a surface of one or more relatively thick layers of fibrous material, such as a hat of absorbent wood pulp fibers or cotton of the type commenly used for absorbing and padding purposes, a layer of an axially-oriented plastic material of the foregoing type, e.g., a film, sheet, strands, filaments, subjecting the laminate so formed to conditions which cause the oriented plastic material to shrink whereupon the material assumes dimensions smaller than its original dimensions and, in so doing, causes the fibrous layer to which it is secured to assume a nonplanar shape. Articles of different shapes may be obtained, as desired, by appropriate selection of the materials used and by appropriate selection of the treating processes. They may be made economically at high speeds on relatively inexpensive equipment.

The plastic materials which may be employed in the articles of my invention, include axially-oriented films, sheets, threads, filaments, strands and the like of polystyrene, polyvinyl chloride, polypropylene, polyethylene and methyl methacrylate. Such axially-oriented materials are obtained by stretching standard plastic materials, after they are formed by conventional solution casting or extruding techniques, to a larger size in one or more directions, usually accompanied by the application of heat to one or both surfaces of the material, whereupon the material becomes thinner and the molecules comprising the material are rearranged from a generally random arrangement into one which is of a more orderly pattern. Materials of this type are available in the form of films from various sources, .as for example from the Plax Corporation under the names Polyflex and Methaflex; from the Cordite Company under the name Cordite 1,000; from W. R. Grace & Company under the name Cryovac; and from Goodyear Tire and Rubber Company under the name Vitafilm ST. These films may be slit into strands or bands of different widths.

By way of illustrating the invention, I shall refer more specifically to axially-oriented films of plastic materials. It is to be understood, however, that axially-oriented plastic materials in forms other than films may be used in various embodiments of the invention.

Most axially-oriented films currently available are biaxially oriented. A biaxially-oriented film is one which has been stretched both longitudinally and transversely, i.e., stretched in two mutually perpendicular directions. The degree of biaxial orientation may be the same in both directions, or it may be different. As a result of the axial orientation, certain forces are built up into the films, providing, in effect, what might be termed as elastic memory. These forces can be released and the films shrunk from their stretched, axially-oriented sizes to smaller sizes by exposing them to heat. I may utilize this feature of such films in the practice of my invention.

Axially-oriented plastic films can be obtained with varying shrink characteristics. For example, W. R. Grace & Companys S Film, a vinyl chloride-vinylidene chloride copolymer, shrinks about 45% at 205 F.; their D Film, an irradiated, medium density polyethylene, shrinks about 50% at 250 F., and their Y Film, at polypropylene, shrinks about 55% at 310 F. Films which may be shrunk up to of their preshrunk, axially-oriented size are available. The shrink characteristics of the films at different temperatures may also vary. By selectively utilizing these properties of the films, the types of nonplanar articles which may be made in accordance with this invention may be varied as desired. In addition, oriented plastic films can be provided to have controlled amounts of shrinking in one or more directions, i.e., machine direction and transversely thereof, with equal or different degrees of shrinkage in the different directions. These characteristics also lend themselves to the preparation of preformed, nonplanar articles which are shaped in one or more dimensions, and in different ways.

Upon orientation, the films gain in tensile strength. Further, films which are Waterproof or which are soluble in water are available. These features may be suitably employed in the making of various embodiments of the invention.

A preformed, arcuately shaped sanitary napkin which is curved in the direction of its length is a preferred embodiment of an article incorporating the invention. A napkin of this form has the general arcuate configuration of the vaginal area against which it is positioned in use and thus is comfortable to wear, less conspicuous and absorbs fluid more efiiciently.

In accordance with this invention, such a preformed, arcuately shaped sanitary napkin may be made by adhesively bonding an axially-oriented plastic film to a surface of one or more relatively thick, fiat layers or bats of absorbent fibrous material which form components of a sanitary napkin, and then subjecting the composite so formed to heat which causes the film to shrink. When the axially-oriented film shrinks, it causes the layer or layers of absorbent fibrous material to which it is bonded to assume a nonplanar configuration, e.g., to curve. In other forms of the invention, different portions of the axially-oriented plastic film may be selectively shrunk, while other parts remain unshrunk or relatively unshrunk.

In the drawings:

FIG. 1 is a perspective view of an arcuately shaped sanitary napkin incorporating the invention, partly cut away to reveal its inner construction, and with its attachment tabs extended;

FIG. 2 is another form of the invention illustrating in longitudinal section an axially-oriented sheet of plastic film secured to a relatively thick layer of fibrous material and illustrating by the arrows the direction of application of heat to the composite so formed;

FIG. 3 is a view of the composite of FIG. 2 after shrinking the axially-oriented plastic film by heat to cause the composite to assume a non-planar configuration, e.g.,

a curve;

FIG. 4 is a view, in longitudinal section, of another embodiment of the invention which includes an axiallyoriented sheet positioned between and secured to relatively thick layers of absorbent fibrous material of different types and also illustrates by arrows the direction of application of heat;

FIG. 5 is a view of the composite of FIG. 4 illustrating the configuration assumed by the composite after the film is shrunk;

FIG. 6 is a top plan view of a disc-shaped laminate of an axially-oriented plastic film secured to a similarly shaped disc of absorbent material prior to formation into a hernispherically shaped pad;

FIG. 7 is a sectional view of the disc-shaped laminate of FIG. 6 taken along a diameter and further illustrating by the arrows the direction of application of heat thereto;

FIG. 8 is a top plan view, partly cut away, of the laminate of FIG. 7 after heating and shrinking the film; and

FIG. 9 is a side elevational view, partly cut away, of FIG. 8 illustrating its hemispherical shape.

A typical sanitary napkin incorporating the invention is illustrated in FIG. 1. The napkin 10 includes an elongated absorbent pad 12 in the form of a layer of comminuted wood pulp fibers 2 inches wide, 8 inches long, inch thick and weighing about 150 grains having a selectively shrunken, axially-oriented plastic film 14 of polyvinyl chloride, three-quarters of a mil thick, coextensive with and adhesively bonded to the bottom 16, sides 18, and top longitudinal edge portions of the pad. The composite so formed is enclosed within a wrapper of fabric 22, such as a non-woven fabric, which extends beyond the ends of the pad to provide the usual attachment tabs 24. The napkin is arcuately shaped in the direction of its length with the plastic film positioned on the outside of curvature so that when the napkin is placed against the body when worn, the film will be on the side of the napkin away from the body. The film, because of its water-proof properties, acts as a fluid barrier and prevents menstrual fluid absorbed by the pad of wood pulp fibers from striking through the bottom of the napkin.

A napkin of the foregoing type may be made by directing hot air at a temperature of about 250 C. through jets to both sides 18 of the napkins 10 for a period of about six seconds as they move through an oven to heat the film covering the sides. The application of the hot air in this localized manner causes the portion of the film covering the sides of the pad, i.e., the portion upon which 4 the hot air impinges, to shrink. In shrinking, the pad is caused to assume a curved configuration to provide a napkin of the shape illustrated in FIG. 1.

By localizing the application of the heat to the film covering the sides of the pads as they move through an oven, shrinkage of the film occurs primarily in those portions. Some shrinking may also occur in those portions of the film which cover the longitudinal top and bottom edges of the pad. Most of the portion of the film extending across the bottom surface of the pad remains unshrunken or shrunken to a lesser extent than those portions covering the sides of the pad. By maintaining the pads in intimate, face-to-face contact with respect to each other as they pass through a forming oven, the faces of the pads are insulated by adjacent pads, thereby minimizing the exposure of those surfaces to the applied heat. By so directing the application of the heat to the film, while insulating or partially insulating other portions of the film, selective shrinkage of the film and selective curvature of the resulting article may be obtained.

In FIGS. 2 and 3 there is illustrated another curved article incorporating the invention 'which includes a relatively thick, rectangular shaped layer of fibrous material, such as a plurality of superposed layers of cotton cords, having an axially-oriented plastic film 62 secured to it. The arrows in FIG. 2 illustrate that the heat is applied to the film side of the laminate so formed. Upon the application of heat, the film shrinks and in so doing causes the layer of cotton to curve with the film on the inside of curvature, as illustrated in FIG. 3. Articles so formed may be used as padding for casts. If desired, curvature in such articles may be obtained either lengthwise of the layer of fibrous material, or transversely thereof, or in both directions. If an article curved in only one direction is desired, a film oriented essentially or predominately in one direction is used.

In FIGS. 4 and 5 there is illustrated a further embodiment of the invention which includes two layers of fibrous material, one of which is less resistant to being curved than the other. For example, the top layer 64 may be a relatively thick layer of comminuted wood pulp fibers and the bottom layer 68 a layer of cotton fibers of equal thickness. The layer of wood pulp fibers is less resistant to being curved than the layer of cotton fibers. A bi-axially-oriented plastic film 70 is placed between the layers and is bonded to both layers. When the film is heated by the application of heat in the direction of the arrows as illustrated in FIG. 4, the film shrinks, thus curving both layers of fibers. The article is curved with the layer of wood pulp fibers on the inside of curvature since it is less resistant to being curved, and with the layer of cotton on the outside of curvature.

A still further embodiment of the invention is illustrated in FIGS. 6-9. This embodiment is illustrative of the formation of a hernispherically shaped article in accordance with the invention. A disc-shaped layer 72 of fibrous material has a like shaped, multi-axially-oriented film 74 adhesively bonded to one surface. A multi-axially-oriented film is one which has been stretched in a plurality of directions extending radially outwardly from the center of the sheet. Heat is applied to the peripheral portions 76 of the film side of the laminate so formed in the locations designated by the crosses in FIG. 6 and in the direction indicated by the arrows in FIG. 7, while the central portion of the film is insulated. Applying heat to the peripheral portions of the film causes the film in those portions to shrink to provide a hernispherically shaped article of the type illustrated in FIGS. 8 and 9. Articles of this shape may be used as lactation pads and for similar purposes.

Any suitable means may be used to cause shrinkage of the film. Hot air is preferred, although hot water and steam may be suitably employed. Alternatively, instead of applying heat to cause shrinking of the axially-oriented film during the manufacturing operation, the article containing the axially-oriented film may be stored at elevated temperatures which causes shrinking of the film to take place over a somewhat more extended period of time. The amount and rate of shrinkage which occurs is generally related to the time and temperature; greater and more rapid shrinking is obtained when high temperatures are used.

Instead of using films of axially-oriented plastic films whose dimensions are generally the same as the dimensions of the surface or surfaces of the layers of fibrous material to which they are secured, one or more strips of such films may be applied to such surfaces of such layers in different patterns. By Way of example, a preformed, arcuately shaped absorbent fibrous body suitable for use as a sanitary napkin and similar to the embodiment described above but not having a moisture barrier may be provided by applying strips of axially-oriented plastic film only to the sides and longitudinal edge portions of one face of the absorbent fibrous pad, with the other surfaces thereof being free from such film. Shrinking the strips of plastic film will cause the absorbent fibrous pad to which they are bonded to assume a curved configuration. In another form, a plurality of parallel, aligned strands of axially-oriented plastic material suitably positioned on and bonded to a surface of the fibrous material may be used.

The extent to which the film shrinks is governed by factors such as the temperature of the heating medium which causes shrinkage, the time the heat is applied and upon the particular axially-oriented film used. A predetermined degree of shrinkage may be obtained in one ,or more directions with greater or lesser amounts of shrinkage obtained by applying the heat at different temperatures, and for different periods of time, to different portions of the axially-oriented plastic film. By proper selection of the particular axially-oriented film used and by proper control of the application of the heat causing shrinkage of the films, articles of 'various nonplanar configurations may be obtained.

The curvature assumed by the absorbent fibrous layer to which the axially-oriented plastic film is bonded is determined by the resistance to curving of the fibrous layer as Well as by the amount of shrinkage which can be obtained in the plastic film. A relatively thin layer of an absorbent fibrous material which does not greatly resist being curved, such as a layer of wood pulp fibers, will be curved more easily than a similarly sized layer of cotton fibers because cotton fibers tend to resist deformation more than wood pulp fibers. Greater or lesser amounts of curvature in each of the foregoing types of absorbent fibrous bodies may thus be obtained by approximately selecting the particular fibrous material used.

In addition, the ability of the film to cause a layer of fibrous material to curve is influenced by the shrink tension of the film. The term shrink tension is a measurement of the amount of force an axially-oriented film exerts while it shrinks. If, because of the particular absorbent fibrous material used, or because of the amount used, a relatively great amount of force is required to cause the fibrous material to curve, a film having a high shrink tension may be used. On the other hand, if a lesser amount of force is required, a film having a low shrink tension may be used.

If it is desired to use a film which has a low shrink tension to make an article having components which would ordinarily require a film having a high shrink tension to cause curvature, the article may first be performed into essentially its desired form and the film then shrunk. Preforming the article before shrinking the film reduces the resistance to curving and consequently the amount of force the film is required to exert to cause curvature and to hold the article in its curved form.

It is apparent that modifications, variations and changes may be made in the foregoing illustrative embodiments of the invention while still remaining within its spirit.

What is claimed is:

1. A preformed pad suitable for body padding or for absorbing body fluids comprising a relatively thick layer of fibrous material having a nonplanar configuration, and a layer of shrunken, axially-oriented plastic secured to a surface of said layer of fibrous material, the direction of said axial orientation of said shrunken plastic layer extending in the direction in which said fibrous layer is nonplanar, said shrunken plastic layer assisting in maintaining said layer of fibrous material in said nonplanar configuration.

2. A preformed pad in accordance with claim 1 wherein said plastic layer is a film.

3. A preformed pad in accordance with claim 1 wherein said plastic layer is in the form of strands.

4. A preformed pad in accordance with claim 1 wherein portions of said plastic layer are shrunk to a greater extent than other portions.

5. A preformed pad in accordance with claim 1 wherein said nonplanar configuration is a curve and said plastic layer is on the inside of curvature.

6. A preformed pad in accordance with claim 1 wherein said nonplanar configuration is a curve and said plastic layer is on the outside of curvature.

7. A preformed pad in accordance with claim 1 wherein said shrunken plastic layer is a film of plastic initially multi-axially-oriented shrunk in a plurality of axial directions.

8. A preformed pad in accordance with claim 1 wherein said body includes a plurality of superposed layers of fibrous material and said shrunken plastic layer is intermediate said fibrous layers and is secured to adjacent layers.

9. A preformed, arcuately shaped sanitary napkin which includes an absorbent core comprising a relatively thick layer of fibrous material having an arcuate configuration, and a layer of shrunken, axially-oriented plastic secured to a surface of said layer of fibrous material, the direction of said axial orientation of said shrunken plastic layer extending in the direction in which said fibrous layer is arcuate, said shrunken plastic layer assisting in maintaining said layer of fibrous material in said arcuate configuration.

10. A preformed, arcuately shaped sanitary napkin which includes an absorbent core comprising a relatively thick layer of fibrous material having an arcuate configuration, and a layer of shrunken, axially-oriented plastic secured to and covering the sides of said layer of fibrous material, the direction of said axial orientation of said shrunken plastic layer extending in the direction in which said fibrous layer is arcuate, said shrunken plastic layer assisting in maintaining said layer of fibrous material in said arcuate configuration.

11. A preformed, arcuately shaped sanitary napkin which includes an absorbent core comprising a relatively thick layer of fibrous material having an arcuate configuration, and a layer of shrunken, axially-oriented plastic covering the bottom and sides of said layer of fibrous material, the portion of said plastic layer covering said sides being secured thereto, the direction of said axial orientation of said shrunken plastic layer extending in the direction in which said fibrous layer is arcuate, said shrunken plastic layer assisting in maintaining said layer of fibrous material in said arcuate configuration.

12. A preformed, arcuately shaped sanitary napkin which includes an absorbent core comprising a relatively thick layer of fibrous material having an arcuate configuration, and a layer of shrunken, axially-oriented plastic covering the bottom, sides and longitudinal top edges of said layer of fibrous material, the portions of said plastic layer covering said sides and longitudinal top edges being secured thereto, the direction of said axial orientation of said shrunken plastic layer extending in the direction in which said fibrous layer is arcuate, said portions covering said sides and longitudinal top edges assisting in maintaining said layer of fibrous material in said arcuate configuration.

References (Iited by the Examiner UNITED STATES PATENTS Replogle 264-342 Vohrer 264342 Foster 2872 Johnson 128290 8 Ashton et a1. 128290 Ashton et a1 128-290 Weitzman 128-287 Cornwell 128--287 Assistant Examiners.

Claims (1)

1. A PREFORMED PAD SUITABLE FOR BODY PADDING OR FOR ADSORBING BODY FLUIDS COMPRISING A RELATIVELY THICK LAYER OF FIBROUS MATERIAL HAVING A NONPLANAR CONFIGURATION, AND A LAYER OF SHRUNKEN, AXIALLY-ORIENTED PLASTIC SECURED TO A SURFACE OF SAID LAYER OF FIBROUS MATERIAL, THE DIRECTION OF SAID AXIAL ORIENTATION OF SAID SHRUNKEN PLASTIC LAYER EXTENDING IN THE DIRECTION IN WHICH SAID FIBROUS LAYER IS NONPLANAR, SAID SHRUNKEN PLASTIC LAYER ASSISTING IN MAINTAINING SAID LAYER OF FIBROUS MATERIAL IN SAID NONPLANAR CONFIGURATION.

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