US3653382A - Expandable airfelt pad - Google Patents

Abstract

A composite pad composed of a topsheet and a bottom sheet with an absorbent, folded planar airfelt pad disposed therebetween. The absorbent, folded planar airfelt pad consists of a glabrous surfaced and folded airfelt composed of less than textile length fibers such as wood pulp fibers and intended for use as an absorbent layer in disposable articles, for example disposable diapers having a topsheet, an absorbent layer, and a relatively water impermeable backsheet. The glabrous surfaced and folded airfelt provides interface slippage between substantially horizontal folds thereby avoiding tensile stresses and preventing in use rupture failure of the absorbent layer in the disposable articles, while contributing to toilet flushing disposal and absorbency.

Description

1 States atent 1 3,653,382 Easley et a1. [45] Apr. 4, 1972 [54] EXPANDABLE AHRFELT PAD 3,481,337 12/1969 Ruffo ..128/284 [72] Inventors: Charles E. Easley; Charles L. wosaba, H, 3,525,337 8/1970 S1mons et al ..128/290 b th f t', Oh'

o o Cmcmnal 10 Primary Examiner-Charles F. Rosenbaum [73] Assignee: The Procter & Gamble Company, Cincin- Attorney-William S. Shelow, Ill

nati, Ohio 221 Filed: Dec. 22, 1969 [57] ABSTRACT A composite pad composed of a topsheet and a bottom sheet [21] Appl' No" 886,878 with an absorbent, folded planar airfelt pad disposed I therebetween. The absorbent, folded planar airfelt pad con- U.S. slsts ofa glabrous surfaced and folded alrfelt composed of less CL 1 A6lf tha textil length fibers uch as wood fibers and in. [58] Field of Search ..128/284, 286, 287, 290, 296, tended for use as an absorbent layer in disposable articles, for 128/156; 161/116, 122, 123, 130, 1 2 example disposable diapers having a topsheet, an absorbent layer, and a relatively water impermeable backsheet. The [56] References cued glabrous surfaced and folded airfelt provides interface slip- UNITED STATES PATENTS page between substantially horizontal folds thereby avoiding tensile stresses and preventing in use rupture failure of the ab- Gl'een n so -bent layer in the disposable articles contributing to Hervey et 31.. toilet flushing disposal and absorbency 3,430,629 3/1969 Murphy ..128/284 3,441,023 4/1969 128/287 8 Claims, 8 Drawing Figures Rijssenbeek Patented April 4, 1972 3,653,382

2 Sheets-Sheet 2 INVENTORS Charles E. Eosley BY Charles L- Wosobo II ATTORNEY EXPANDABLE AIRFELT PAD BACKGROUND OF THE INVENTION This invention relates to improvements in the use of short fibered airfelt pads as the absorbent layers in disposable articles such as diapers, sanitary napkins and bandages, and the invention provides for rupture preventing use of such airfelt pads in these single use situations wherein the property of disposal by toilet flushing is a desirable attribute. More particularly, the invention provides an improved fluid absorbent, folded airfelt pad and composite pad containing same for use in disposable structures and articles which are subject to in use stresses and strains while in either a dry or moist condition due to their intended function.

Specifically, the invention provides for an absorbent, folded airfelt pad and composite pad containing same, wherein an airfelt prepared from wood fibers is imparted with resistance to in use stresses and strains by a glabrous surfacing and folded structure. The folded structure and glabrous surfacing overcomes the normal lack of tensile and bursting strength in such an airfelt pad by providing an airfelt structure capable of withstanding high strain with low stress levels so that sufficient stress to tear, rupture, bunch or split the pad is not generated.

in referring to airfelts herein, applicants intend reference to sheets which are formed from short wood fibers or similar cellulosic fibers by dispersing the fibers in an air or gaseous stream and depositing them on a moving foraminous receiving media to form minimally cohesive sheets or pads having little or no inherent tensile strength. The term, glabrous surfaced, with reference to airfelt, refers to an airfelt provided with a surface which prevents or minimizes fiber entanglement between surfaces of the airfelt when it is in a folded configuration, whereby surface slippage between folds is enhanced to the extent that the airfelt cannot rupture itself without fold slippage under stress. Processes for the formation of airfelt pads are well-known in the art as exemplified by the processes and apparatus of U.S. Pat. No. 2,618,816, issued to C. G. .Ioa on Nov. 25, 1952 and U.S. Pat. No. 2,689,985, issued to W. H. Burger et al. on Sept. 28, 1954.

Although it has been realized that airfelts have advantage in the manufacture of disposable articles, such as diapers, sanitary napkins, and bandages, in that airfelts are fluid absorbent, bulky, resilient and economically advantageous by nature, certain real problems have been and are encountered in incorporating the advantageous aspects of such airfelts in disposable articles. These problems result from the inherent flimsy nature of a short fibered airfelt in that these airfelts have little or no inherent tensile or bursting strength. In general, the disposable articles wherein such airfelts can be advantageous are structured of one or more layers of non-woven, plastic, creped tissue, and like materials used as top and bottom sheets to contain and cover an airfelt; the airfelt is made part of such a structure to provide the advantageous qualities of fluid absorbency, bulk and resiliency mentioned above.

At the same time, incorporation of these airfelts has in the past been accompanied by problems because it is the intended nature of such disposable articles that they absorb body fluids and are placed in mechanical stress situations during use. Past experience has shown that airfelts in these moist or wet mechanical stressed situations bunch, ball up, shift, rupture, burst and otherwise mechanically fail to stay in place while contributing little or no overall strength to the disposable article. The addition of wet strength additives to such airfelts to provide tensile strength is not desirable since this addition negates the desirable flimsy nature of the airfelt in toilet flushing disposal.

Recognizing the important absorbency and resiliency characteristics, as well as the economic advantages, inherent in airfelt pads for these disposable structures, several methods to improve the flimsy nature of the airfelt pads in disposable articles have been disclosed in the prior art. Examples of these methods are provided by such patents as U.S. Pat. No. 3,395,708, issued to L. R. B. Hervey et al. on Aug. 6, 1968,

U.S. Pat. No. 2,896,618, issued to R. J. Schaeffer on July 28, 1959 and U.S. Pat. No. 2,931,360, issued to F. F. Dexter on Apr. 5, 1960.

The methods disclosed in the prior art have in their various forms provided for the stabilization of airfelt pads and do in some degree prevent the shifting and bunching of said pads; however, there has remained a problem of making an airfelt pad cooperate to best advantage in disposable articles. By cooperation it is intended to convey the meaning that the airfelt is not only prevented from bunching up, shifting, rupturing and tearing to constitute a failure of the disposable article in which it is incorporated, but is provided with such a form that it materially contributes to the stability, resiliency and fluid absorbency of such a structure. The disclosed characteristics of the present absorbent, folded airfelt pad are considered to be of particular importance when such absorbent, folded airfelt pad forms the absorbent layer of a disposable article having a topsheet of controlled hydrophobicity and a plastic bottom sheet such as those disclosed in U.S. Reissue No. 26,151, originally U.S. Pat. No. 3,180,335, issued to R. C. Duncan et al. on Apr. 27, 1965. While the several methods noted above for airfelt pad stabilization are available, applicants are unaware of any prior art method of engendering the present cooperation from an airfelt in a disposable article.

SUMMARY OF THE INVENTION Inasmuch as a practical means of gaining the several advantages of airfelts in disposable articles without suffering the disadvantages resulting from the flimsy nature of such materials was desired, the present absorbent, folded airfelt pad and composite pad method of incorporating an airfelt in a disposable article was developed. In general, the advantageous absorbent, folded planar airfelt pad of the present invention comprises an airfelt prepared from short fibers, i.e. wood fibers, cotton linter fibers and other fibers derived from woody plants, provided with glabrous surfaces and given a folded configuration. These glabrous surfaces permit folding or pleating of the airfelt without entanglement of the airfelt fibers in the adjacent surfaces of substantially horizontal folds, thereby permitting each fold to slip or open at a low stress level when the pad is placed under in use strain loading.

Although this would be possible, it is not intended, and the present glabrous, or slippage, surfaces do not in and of themselves provide the total tensile and bursting strengths necessary for the advantageous incorporation of an airfelt in a disposable structure. To provide such strength would defeat the desirable toilet flushability of the absorbent, folded airfelt pad, wherein such pad is disintegrated by water contact and flushed away. Rather, it is the sum of the airfelt and the cooperation between the absorbent, folded airfelt pad and its surfaces which provides the necessary resistance to mechanical failure.

In this regard one suitable embodiment of the present advantageous absorbent, folded airfelt pad is one wherein both surfaces of an airfelt are provided with a laminant overlay or glabrous surface of, for example, creped tissue prior to folding or pleating. The airfelt with surfaces of creped tissue is then given a cross-machine direction folding treatment to provide the required resiliency in the resultant absorbent, folded airfelt pad structure. This is to say that the glabrous surfaced airfelt pad of the present structure having tissue overlays on each of its surfaces is not itself sufficiently strong to withstand the in use forces to which it is subjected while in a fluid wetted condition, it is only when the present structure is given convoluting folds in the cross-machine direction that such ability to adapt to mechanical stress is attained. In this manner and according to the details and embodiments of the present invention discussed below, an absorbent, folded airfelt pad and composite pad, having the required resistance to strain loading together with a pleasing bulky nature, is prepared according to the present invention.

It is, accordingly, the principle object of this invention to provide an absorbent, folded airfelt pad as an improvement for airfelts to be incorporated in disposable articles of a personal use nature.

Another object of this invention is to provide an absorbent, folded airfelt pad which retains its ability to be easily repulped and flushed after use in a disposable article, but which is possessed of glabrous fiber retaining surfaces and has a pleated or folded form adapted to cooperate with the layers of the conventional disposable articles in which it finds use.

Another object of this invention is to provide an absorbent, folded airfelt pad having glabrous surfaces provided by facing tissue sheets which absorbent, folded airfelt pads provide required resistance to failure not so much by their real tensile strength, but by their cooperative nature in avoiding the setting up of stress concentration points.

It is yet another object of this invention to provide an absor-- bent, folded airfelt with glabrous surfaces and a convoluted or folded form such that stresses applied to the airfelt pad are generalized instead of being focused at a failure point.

It is still a further object of this invention to provide a composite pad exhibiting bulk, resiliency and enhanced fluid absorbency, which composite pad comprises a topsheet and a bottom sheet with an absorbent, folded airfelt pad lying therebetween.

Briefly stated, in accordance with one aspect of this invention, there is provided an absorbent, folded planar airfelt pad, folded in pleated form and provided with glabrous surfaces to allow slippage of the substantially horizontal folds upon application of mechanical stress. There is also provided a composite pad comprising an absorbent, folded airfelt pad disposed between a topsheet and a bottom sheet.

In one specific embodiment, the invention comprises an airfelt composed of wood pulp fibers, which airfelt is surfaced on both of its sides or faces with tissue paper prior to folding the airfelt in the manner described in detail below to provide ability to absorb stress loading during in use situations and thereby to prevent excessive shifting and rupture failure in the resulting absorbent, folded airfelt pad. In other specific embodiments, the weak airfelt can be provided with the required glabrous surfaces by either a surface spraying of water soluble adhesive or a non-woven sheet used as alternates to the tissue paper surfaces. Also combinations of tissue paper, non-woven materials and in situ provision for a glabrous surface can be made.

BRIEF DESCRIPTION OF THE DRAWINGS While the application concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as forming the present invention, it is believed that the invention will be better understood from the accompanying description taken in connection with the accompanying drawing, wherein like numbers refer to like elements in the various figures, in which:

FIG. 1 is an enlarged isometric view ofa preferred embodiment of the composite pad and the absorbent, folded airfelt pad of this invention, illustrating a preferred fold configuration with the absorbent, folded airfelt pad in operative position between a topsheet and a bottom sheet, which topsheet is turned back to reveal the absorbent, folded airfelt pad;

FIG. 2 is an enlarged fragmentary cross sectional view taken along line 22 of FIG. 1 to further illustrate the fold configuration in the absorbent, folded airfelt pad;

FIG. 3 is an enlarged isometric view of another preferred embodiment of the absorbent, folded airfelt pad of this invention, illustrating another fold configuration with the pad in operative position as a composite pad between a turned back topsheet and a bottom sheet;

FIG. 4 is an enlarged fragmentary cross sectional view taken along line 4-4 ofFIG. 3;

FIG. 5 is an enlarged isometric view of yet another preferred form ofthe present absorbent, folded airfelt pad, il-

lustrating another fold ratio in the absorbent, folded airfelt pad with the pad in operative position between a topsheet and a bottom sheet as a composite pad;

FIG. 6 is an enlarged fragmentary cross sectional view of FIG. 5 taken along line 66;

FIG. 7 is an isometric view, illustrating the absorbent, folded airfelt pad and composite pad of FIG. 1 assembled in a pleated disposable diaper; and

FIG. 8 is an isometric view of the diaper illustrated in FIG. 7 placed in the form assumed when he diaper is worn by an infant.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. I of the drawings, there is illustrated a composite pad I and an absorbent, foldedairfelt pad 2, which absorbent, foldedairfelt pad 2 comprises anairfelt 3 which is covered on both its surfaces, to provide the above stated glabrous surfaces, withtissue 4, which can be creped and has a basis weight of about 6 lb. to about 24 lb. per 3,000 sq. ft., preferably about 10 lb. to about 12 lb. per 3,000 sq. ft. Theairfelt 3 has a basis weight of about 8 lb. to about 200 lb. per 3,000 sq. ft., preferably about 24 lb. to about lb. per 3,000 sq. ft. Absorbent, foldedairfelt pad 2 is disposed betweentopsheet 7 andbottom sheet 8 to form composite pad The absorbent, foldedairfelt pad 2 illustrated is provided withfolds 5 having a frequency of about 1 fold to about 4 folds, preferably about 2 folds to about 3 folds, per inch such that the fold ratio, or ratio of folded to nonfolded length, in the absorbent, foldedairfelt pad 2 is about 0.3 to about 0.7 and preferably is about 0.4 to about 0.5 The folded thickness of absorbent, foldedairfelt pad 2 is about 0.030 inch to about 0.250 inch, preferably about 0.070 inch to about 0.150 inch, and can be adjusted by calendering between rolls for an intended disposable article use. Lines ofembossing 6, which are about one-sixteenth inch to about three thirty-seconds inch in width on widely spaced, for example about 1 inch to about 2 inch centers cross thefolds 5 in a generally perpendicular direction and can be provided by roller embossing, as illustrated in FIG. 1. These lines ofembossing 6 are used to maintain the folded integrity of absorbent, foldedairfelt pad 2 for facilitation of its assembly into disposable articles. Various embossing patterns such as diamonds, circles, dots, etc. or like patterns of water soluble adhesives, applied to supply low strength bonds which do not prevent in use extension of thefolds 5, can be employed in place of the lines ofembossing 6 for absorbent, foldedairfelt pad 2 integrity. Thefolds 5 shown in FIG. 1 are preferably oriented in the cross-machine direction ofairfelt 3 and provide expansion for the absorbent, foldedairfelt pad 2 in the machine direction. The illustrated pattern offolds 5 shown in FIG. 1 will provide protection against failure under machine direction in use loading as well as under loading along a diagonal direction which has a lateral component such as the type of loading placed on a diaper by baby leg and buttock movements during crawling and walking. Other fold patterns, for example diagonal folds, in absorbent, foldedairfelt pad 2 can be employed to provide either crossmachine or machine direction expansion in absorbent, foldedairfelt pad 2 or combinations of fold patterns can be employed. It is noted that thetissue 4 layers providing the glabrous surfaces of theairfelt 3 need only provide sufficient tensile strength to enable the pull-out or potential pull-out of thefolds 5 in the absorbent, foldedairfelt pad 2. Thetissue 4 can be creped, and the tensile strength thereof does and is not intended to provide the full in use protection against rupture or bursting failure. Indeed, if it did so, thetissue 4 or other covering material can render the absorbent, foldedairfelt pad 2 so stiff and non-resilient as to negate its usefulness in a disposable article or diaper structure, although such resiliency and stiffness may not negate effectiveness in other disposable articles such as bed pads. Thefolds 5 in absorbent, foldedairfelt pad 2 act by expansion and slippage to prevent in use tenslle stresses from localizing to the extent that rupture or bursting failures are caused.

FIG. 2 further illustrates the nature of the composite pad I as comprising atopsheet 7 and abottom sheet 8 with absorbent, foldedairfelt pad 2 disposed therebetween. The fold configuration of thefolds 5 is readily apparent. In disposable article use,topsheet 7 andbottom sheet 8 are either unattached or only edge attached to absorbent, foldedairfelt pad 2 so that the slippage and expansion offolds 5 can be fully utilized within the disposable article to prevent rupture of absorbent, foldedairfelt pad 2 andairfelt 3.

Referring further to FIG. 3 there is illustrated another em bodiment of composite pad I wherein thefolds 5 in absorbent, foldedairfelt pad 2 are in the form of interlocking T" or Greek letter omega chains. The absorbent, foldedairfelt pad 2 of FIG. 3 is stabilized for handling ease in assembling disposable articles by the above described lines of embossing 6extending across thefolds 5. 1

FIG. 4 further illustrates the interlocking T folds 5 in absorbent, foldedairfelt pad 2 as one preferred embodiment of the present invention.

Referring now to FIG. 5 there is again illustrated a composite pad 1 having an absorbent, foldedairfelt pad 2 disposed between atopsheet 7 and abottom sheet 8. It is noted that thefolds 5 of FIG. 5 have a configuration similar to thefolds 5 in FIG. I with the exception that they overlap less or have a higher fold ratio, as defined above.

FIG. 7 illustrates apleated diaper 9, as an embodiment ofa disposable article, in which composite pad I and absorbent foldedairfelt pad 2 are imminently suited to use. In FIG. 7,bottom sheet 8 is extended outwardly from absorbent, foldedairfelt pad 2 to provide leg seal and waist pinning area forpleated diaper 9.

FIG. 8 illustrates the form ofpleated diaper 9 when placed about an infant in wearing position so thatbottom sheet 8 is on the outside and is available at the infants waist for pinning while absorbent, foldedairfelt pad 2 andtopsheet 7 are interior ofpleated diaper 9.Topsheet 7 is shown in position to contact a babys skin while absorbent, foldedairfelt pad 2 lies below.

In noting major advantages of the present absorbent, foldedairfelt pad 2 and composite pad 1 structures, it is specifically noted that they are structures which provide nonordered resistance to stresses to result in an unexpected increase in apparent rupture or burst resistance over that which would be obtained from the sum rupture or burst resistances of the surface layers and the airfelt. In particular, the absorbent, foldedairfelt pad 2 exhibits a marked increase to rupture and burst stresses over that afforded by eitherairfelt 3 orairfelt 3 together with surfaces oftissue 4. This improvement in tear or burst resistance is realized by forming absorbent, foldedairfelt pad 2 fromairfelt 3 which in other than itstissue 4 surface layers has little or no apparent tear or tensile strength. The absorbent, foldedairfelt pad 2 is folded so that, under the in use loading to which it is subject, any tensile or burst stresses are generalized and absorbed by the structure without approaching its absolute tensile strength. In this regard, it is noted that thetissue 4 surface layers of the absorbent, foldedairfelt pad 2 do not approach the tensile strength which would be required to resist failure. In fact, it is only necessary that thetissue 4 or glabrous surface layers prevent eitherairfelt 3 fiber entanglement at contact surfaces betweenadjacent folds 5 or fiber entanglement interaction between the absorbent, foldedairfelt pad 2 and other disposable article layers,e.g. topsheet 7 andbottom sheet 8 in composite pad 1, which would prevent absorbent, foldedairfelt pad 2 from slipping, stretching or expanding under stress loading. Another advantage of the absorbent, foldedairfelt pad 2 is that, for a given basis weight, it has an apparent bulk resiliency hysteresis with regard to pressure loading and unloading that is difficult or impossible to realize in a nonfolded structure. This hysteresis or springiness under repeated pressure loading is also imparted to composite pad 1. Comparing between pads of equal basis weight, the absorbent, foldedairfelt pad 2 of the present invention exhibits an increased absorbency as compared with a nonfolded structure containing like layers.

In testing the composite pad 1 and absorbent, foldedairfelt pad 2 both a simulated testing of wearer movement in disposable article use and observed results of disposable diapers after infant wear was employed.

In the simulated testing, a test apparatus was employed wherein a 4 by 4 inch sample of the composite pad 1, or absorbent, foldedairfelt pad 2, as prepared for test by wetting with 2 times its dry weight with water and allowing it to sit or equilibrate for I minute, was restrained in compression between two annular, flat metal rings of aluminum with an internal opening diameter of 3.5 inches. The bottom center of the 3.5 inch diameter sample thus restrained rested on a 1.5 inch diameter first plate covered with,.one-sixteenth inch polyurethane foam. A second 1 inch diameter plate covered with one-sixteenth polyurethane foam was centered and pressed down on the top of the sample, disposed on the first or bottom plate, with a pressure of 12.7 lb. per sq. in. and the test sample was additionally wetted with 2 times its dry weight of water and allowed to equilibrate for 1 minute. The first plate, pressing on the bottom surface of the sample under test, was free to rotate in the plane of the sample while the second plate pressing against the top surface was articulated so that it could be rotated within an arc of 45 at a frequency of 55 times per minute. The rotary movement of the first and second plates tended to tear out the restrained test sample in a circle arou nd the articulated 1 inch diameter central pressure plate. A test period in this simulated test with the described rotary articulation was 4 minutes, and the test results were recorded as tear grades from 0 to 3 by inspection, with tear grades greater than I equated to unsatisfactory performance in actual use. The tear grades assigned to individual test samples had the following meaning:

Tear grade 0-no tear around the 1 inch diameter compressed area Tear grade l-tearing in less than a total of around the compressed area Tear grade 2tearing in a total of 90 to around the compressed area Tear grade 3-tearing greater than a total of 180 around the compressed area Having described the composite pad 1 and absorbent, foldedairfelt pad 2 of this invention, the following examples are intended to be further illustrative of the manner in which the products of this invention can be formed and of their uses in disposable articles.

EXAMPLE I An absorbent, folded airfelt pad was formed by first preparing an airfelt from Southern softwood kraft fibers. The airfelt has a basis weight prior to folding of 48 lb. per 3,000 sq. ft., and was enclosed between two sheets of creped tissue paper, each of which tissue paper sheets had a basis weight of l 1.5 lb. per 3,000 sq. ft. The resulting composite material was folded in the fold configuration illustrated in FIGS. 3 and 4 with a fold frequency of 4 folds per inch and a fold ratio of 0.57. The substantially horizontal folds were made to run in the crossmachine direction of the tissue paper enclosing sheets and were held in place, for convenience in handling the resulting absorbent, folded airfelt pad, by l/l6 inch wide embossing lines located on l /sinch centers and running across the folds.

The resulting absorbent, folded planar airfelt pad had a thickness of 0.175 inch, as folded, and was calendered between a rubber roll and a steel roll loaded to 35 lb. per linear inch to reduce the thickness to 0.120 inch. A piece of the absorbent, folded airfelt pad, measuring 16 inches in the fold direction and 12.5 inches in the cross fold direction with a weight of 26 grams, was assembled into a composite pad diaper having a topsheet and a bottom sheet as illustrated in FIGS. 7 and 8. The topsheet was a non-woven rayon fiber material having a basis weight of 13 lb. per 3,000 sq. ft., while the bottom sheet was a polyethylene sheet having a thickness of 0.001 inch.

The diaper was shown to hold 195 grams, or 7.5 times its dry absorbent, folded airfelt pad weight, of water while subjected to a compressive loading of 1 lb. per sq. inch to simulate in use pressures. A simulated test of tear under in use movement, using the test apparatus and method described above, was conducted on the diaper with the result that no tearing, or a tear grade of 0, was recorded. The diaper of this example was also found to be tear resistant, flushable by the method described above and otherwise satisfactory for use when subjected to actual wearing and soiling by an infant.

For comparison, a diaper with an absorbent pad weight of 25 grams was prepared in a similar way from identical materials, with the exception that the airfelt was not folded and additional airfelt was provided for equal weight, was found to hold only 169 grams or 6.5 times it dry weight of water. This comparison diaper had a tear grade of 3, evidencing a tearing of greater than 180 around the oscillated portion and unsatisfactory susceptibility to in use failure.

A composite pad assembled from an absorbent, folded airfelt pad, prepared from airfelt having an unfolded basis weight of 8 lb. per 3,000 sq. ft. and tissue having a basis weight of6 lb. per 3,000 sq. ft., using a fold ratio of 0.3 and a fold frequency of 1 per inch in the manner of this example I will be found to be tear and rupture resistant, absorbent and otherwise satisfactory for disposable article use as a diaper. The absorbent, folded airfelt pad of this example I assembled into a composite pad having a non-woven topsheet and a bottom sheet comprised of a plastic sheet with an outer non-woven layer, will be found suitable for use either as a sanitary napkin or as a bandage.

EXAMPLE II An absorbent, folded airfelt pad was formed by first preparing an airfelt from Southern softwood kraft fibers. The airfelt had a basis weight prior to folding of 48 lb. per 3,000 sq. ft., and was enclosed between two sheets of creped tissue paper, each of which has an unfolded basis weight of 11.5 lb. per 3,000 sq. ft. The resulting composite material was folded in the fold configuration illustrated in FIGS. 1 and 2 with a fold frequency of 2.7 folds per inch and a fold ratio of 0.57. The folds were made to run in the cross-machine direction of the tissue paper enclosing sheets and were held in place by 1/16 inch wide embossing lines located on 1%0 inch centers and running across the folds.

The resulting absorbent, folded airfelt pad cut to measure 16 inches in the folded direction and 12.5 inches in the cross fold direction and having a weight of 26 grams was assembled into a diaper having a topsheet and a bottom sheet as illustrated in FIG. 7. The topsheet was a non-woven rayon fiber material having a basis weight of 13 lb. per 3,000 sq. ft., while the bottom sheet was a polyethylene sheet having a thickness of0.00l inch.

The prepared diaper was shown to hold 200 grams, or 7.7 times its dry weight, of water while subjected to a compressive loading of 1 lb. per sq. in. to simulate in use pressures. A simulated test of tear under in use movement, using the test apparatus and method described above, was conducted on the diaper with the result that no tearing, or a tear grade of 0, was observed. Like the diaper of example I, the diaper of this example ll was found to be tear resistant, flushable by the method described above and otherwise satisfactory for use when subjected to actual wear by an infant.

A composite pad assembled from an absorbent, folded airfelt pad, prepared from airfelt having an unfolded basis weight of 200 lb. per 3,000 sq. ft. and tissue having an unfolded basis weight of 24 lb. per 3,000 sq. ft., with a fold ratio of 0.7 and a fold frequency of 2 per inch, will be found to be tear and rupture resistant, absorbent and otherwise satisfactory for disposable article use as a diaper or a bed pad.

An absorbent, folded airfelt pad was formed by first preparing an airfelt from Southern softwood kraft fibers. The airfelt had an unfolded basis weight of 72 lb. per 3,000 sq. ft., and was enclosed between two sheets of creped tissue paper, each of which tissue paper sheets had a basis weight of l 1.5 lb. per 3,000 sq. ft. The resulting composite material was folded in the fold configuration illustrated in FIGS. 3 and 4 with a fold frequency of3 folds per inch and a fold ratio of0.67. The folds were made to run in the cross-machine direction of the tissue paper enclosing sheets and were held in place by an embossed diamond pattern consisting of 1 inch machine direction by 2 inch cross-machine direction diamonds outlined by embossed lines with a width of three thirty-seconds inch.

The resulting absorbent, folded airfelt pad, cut to measure 16 inches in the fold direction and 12.5 inches in the cross fold direction, had a weight of 30 grams. The so cut piece of absorbent, folded airfelt pad was assembled into a diaper having a topsheet and a bottom sheet as illustrated in FIG. 7. The topsheet was a non-woven rayon fiber material having a basis weight of 13 lb. per 3,000 sq. ft., while the bottom sheet was a polyethylene sheet having a thickness of0.00l inch.

The diaper was shown to hold 231 grams, or 7.7 times its dry weight of water while subjected to a compressive loading of 1 lb. per sq. in. to simulate in use pressures. A simulated test of tear under in use movement, using the test apparatus and method described above, was conducted on the diaper with the result that a tear grade of l was recorded. Although this tear grade of 1 indicates a small amount of tear, less than of total tear around the test periphery, the diaper of this example III was found to be tear resistant, flushable and otherwise satisfactory for use when subjected to actual wear by an infant.

A composite pad prepared in the manner of this example 111, from an absorbent, folded airfelt pad, made from airfelt having an unfolded basis weight of 24 lb. per 3,000 sq. ft. and tissue having an unfolded basis weight of 6 lb. per 3,000 sq. ft., with a fold ratio of 0.4 and a fold frequency of 4 per inch, will be found to be tear and rupture resistant, absorbent and otherwise satisfactory for use as a diaper.

Those skilled in the art of disposable article manufacture will realize that, although the composite pad and absorbent, folded airfelt pad of the present invention have been described primarily in terms of their use in diapers, bandages and sanitary napkins, the possible uses of such pads are multitudinous. ln fact, the such pads can be used wherever the use situation ofa disposable article is such that the article requires or finds advantage in both absorbency and resistance to stress. Such situations are found, for example, in disposable bed clothes, bed pads, dental bibs and surgical drapes.

Therefore, while specific examples of embodiments of the present invention have been described above, it will be apparent that changes and modifications may be made in the described pad structures without departing from the spirit of the invention. It will be further understood that the examples cited and the procedures set forth are intended to be illustrative only and are not intended as limiting this invention, it being intended that all equivalents thereof be included within the scope of the appended claims.

Having thus described the invention, what is claimed is:

1. An absorbent, folded, planar airfelt pad for use in disposable articles, which airfelt pad is comprised of airfelt with glabrous surfaces and has a multiplicity of substantially horizontal folds having a frequency of about 1 to about 4 folds per inch together with a folded to unfolded length of about 0.3 to about 0.7.

2. An absorbent, folded, planar airfelt pad for use in disposable articles, which airfelt pad is comprised of airfelt having a basis weight of about 8 lb. to about 200 lb. per 3,000 sq. ft. with glabrous surfaces of tissue having a basis weight of about 6 lb. to about 24 lb. per 3,000 sq. ft. and has a multiplicity of substantially horizontal folds having a frequency of about 1 to about 4 folds per inch together with a folded to unfolded length ratio of about 0.3 to about 0.7.

3. The absorbent, folded, planar airfelt pad for use in disposable articles ofclaim 2 wherein the folds are stabilized by lines of embossing having a width of about one-sixteenth inch to about three thirty-seconds inch and the absorbent, folded airfelt pad thickness is about 0.030 inch to about 0.250 inch.

4. An absorbent, folded, planar airfelt pad for use in disposable articles, which airfelt pad is comprised of airfelt having a basis weight of about 24 lb. to about 100 lb. per 3,000 sq. ft. with glabrous surfaces of tissue having a basis weight of about 10 lb. to about 12 lb. per 3,000 sq. ft. and has a multiplicity of substantially horizontal folds having a frequency of about 2 to about 3 folds per inch together with a folded to unfolded length ratio of about 0.4 to about 0.5.

5. The absorbent, folded, planar airfelt pad for use in disposable articles ofclaim 4 wherein the substantially horizontal folds are stabilized by lines of embossing having a width of about one-sixteenth inch to about three thirtyseconds inch and the absorbent, folded airfelt pad thickness is about 0.070 inch to about 0.150 inch.

6. A composite pad for use as a disposable article, which composite pad is comprised of a topsheet and a bottom sheet with an absorbent, folded, planar airfelt pad disposed therebetween, which airfelt pad is comprised of airfelt having a basis weight of about 8 lb. to about 200 lb. per 3,000 sq. ft. with glabrous surfaces of tissue having a basis weight of about 6 lb. to about 24 lb. per 3,000 sq. ft. and has a multiplicity of substantially horizontal folds having a frequency of about 1 to about 4 folds per inch together with a folded to unfolded length ratio of about 0.3 to about 0.7.

7. The composite pad for use as a disposable article ofclaim 6 wherein the topsheet is a non-woven sheet, the bottom sheet is a plastic film and the disposable article is a diaper.

8. The composite pad for use in a disposable article ofclaim 6 wherein the topsheet is a non-woven sheet, the bottom sheet is a plastic film with an outer layer of non-woven sheet and the disposable article is a sanitary napkin.

* g;;g UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,653,382 Dated April 4, 197 2 Invent0r(s) Charles E. Easley and Charles L. Wosaba, II

It is certified that error appears in the above-identified patent and that said Letters Patent are'hereby corrected as shown below:

Column 3, line 19, "airfelt with glabrous surfaces" should read airfelt pad with glabrous surfaces-Column 4,line 10, "when he diaper" should read when the diaper-.

Column 4, line 33, after "0.5",insert Column 6, line 19, "one-sixteenth polyurethane" should read one-sixteenth inch polyurethane.

Column 6, line 66, "1 1/8 inch" should read 1 3/8 inch-.

Column 7, line 48, '1 1/8 0 inch" should read 1 3/8 inch-.

Column 7, line 51, "folded" should read fold.

Signed and sealed this 15th day of August 1972.

(SEAL) Attest:

EDWARD M. FLETCHER, JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patent

Claims (8)

1. An absorbent, folded, planar airfelt pad for use in disposable articles, which airfelt pad is comprised of airfelt with glabrous surfaces and has a multiplicity of substantially horizontal folds having a frequency of about 1 to about 4 folds per inch together with a folded to unfolded length of about 0.3 to about 0.7.

2. An absorbent, folded, planar airfelt pad for use in disposable articles, which airfelt pad is comprised of airfelt having a basis weight of about 8 lb. to about 200 lb. per 3,000 sq. ft. with glabrous surfaces of tissue having a basis weight of about 6 lb. to about 24 lb. per 3,000 sq. ft. and has a multiplicity of substantially horizontal folds having a frequency of about 1 to about 4 folds per inch together with a folded to unfolded length ratio of about 0.3 to about 0.7.

3. The absorbent, folded, planar airfelt pad for use in disposable articles of claim 2 wherein the folds are stabilized by lines of embossing having a width of about one-sixteenth inch to About three thirty-seconds inch and the absorbent, folded airfelt pad thickness is about 0.030 inch to about 0.250 inch.

4. An absorbent, folded, planar airfelt pad for use in disposable articles, which airfelt pad is comprised of airfelt having a basis weight of about 24 lb. to about 100 lb. per 3,000 sq. ft. with glabrous surfaces of tissue having a basis weight of about 10 lb. to about 12 lb. per 3,000 sq. ft. and has a multiplicity of substantially horizontal folds having a frequency of about 2 to about 3 folds per inch together with a folded to unfolded length ratio of about 0.4 to about 0.5.

5. The absorbent, folded, planar airfelt pad for use in disposable articles of claim 4 wherein the substantially horizontal folds are stabilized by lines of embossing having a width of about one-sixteenth inch to about three thirty-seconds inch and the absorbent, folded airfelt pad thickness is about 0.070 inch to about 0.150 inch.

6. A composite pad for use as a disposable article, which composite pad is comprised of a topsheet and a bottom sheet with an absorbent, folded, planar airfelt pad disposed therebetween, which airfelt pad is comprised of airfelt having a basis weight of about 8 lb. to about 200 lb. per 3,000 sq. ft. with glabrous surfaces of tissue having a basis weight of about 6 lb. to about 24 lb. per 3,000 sq. ft. and has a multiplicity of substantially horizontal folds having a frequency of about 1 to about 4 folds per inch together with a folded to unfolded length ratio of about 0.3 to about 0.7.

7. The composite pad for use as a disposable article of claim 6 wherein the topsheet is a non-woven sheet, the bottom sheet is a plastic film and the disposable article is a diaper.

8. The composite pad for use in a disposable article of claim 6 wherein the topsheet is a non-woven sheet, the bottom sheet is a plastic film with an outer layer of non-woven sheet and the disposable article is a sanitary napkin.

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