GB2063683A

GB2063683A - Disposable absorbent article

Info

Publication number: GB2063683A
Application number: GB8038560A
Authority: GB
Original assignee: Colgate Palmolive Co
Current assignee: Colgate Palmolive Co
Priority date: 1979-12-03
Filing date: 1980-12-02
Publication date: 1981-06-10
Also published as: ES264633Y; AR240232A1; IE51061B1; PT72110B; PT72110A; CA1153541A; ES264633U; DK477680A; ZA806694B; FR2470590A1; FR2470590B1; DE3044449A1; AU6466580A; BR8007598A; IE802505L; GR72829B; IT1128632B; MX153968A; GB2063683B; AU536507B2

Abstract

An absorbent article comprising, a backing sheet of fluid impervious material, a fluid pervious cover sheet, and a first pad adjacent the cover sheet comprising a loosely formed fibrous mass. The article has a separate second pad intermediate the first pad and the backing sheet, with the second pad comprising a mass of fibres having compressed regions extending throughout a substantial part of the second pad. The average interfibre spacings in the second pad are substantially less than the average interfibre spacings in the first pad, such that the second pad rapidly transmits body fluids to remote locations of the second pad for retention in the areas at a location spaced from the cover sheet. <IMAGE>

Description

SPECIFICATION Disposable absorbent articles The present invention relates to disposable absorbent articles.

Various disposable absorbent articles have been proposed for use in receiving and retaining body fluids. Such articles, e.g. disposable diapers, sanitary napkins and the like, have normally been constructed with a fluid impervious backing sheet, a fluid pervious cover or top sheet, and an absorbent pad intermediate the backing and cover sheets, such as comminuted wood pulp termed in the art as fluff.

Although increasingly popular due to disposability, certain problems associated with the absorbent pads remain and these problems prevent the articles from being totally satisfactory.

First, it is necessary that the pads should be such that body fluids will spread rapidly through the pad from the point of application toward remote locations of the pad in order to minimize pad saturation in localized areas and make maximum use of the capacity of the pad. Second, it is desirable that the pads preferentially retain the body fluids at locations spaced from the cover sheet in order to minimize back wetting through the cover sheet with attendant discomfort to the wearer. Third, the pads should be soft and conformable to the shape of the wearer in order to provide a proper fit of the articles and maximum confort. Finally, the pads should be made in accordance with simplified manufacturing techniques in order to reduce the cost of the disposable articles to the consumer.

In my earlier filed case, G.B. patent specification No. 1547524, there is disclosed, in a disposable absorbent article, having a fluid impervious back sheet and a fluid pervious top sheet, a pad assembly comprising a first loosely formed bat adjacent the cover sheet and a second bat or pad between the first pad and the backing sheet, the second pad having compressed regions throughout a substantial part of the second pad and also having uncompressed areas adjacent said compressed regions. Such a pad is functionally superior to a conventional single pad type disposable product.

In U.S. patent 3,612,055 there is disclosed a single pad diaper construction wherein the one surface not in contact with the top sheet is processed to form a paper-like skin to effect fluid spread to the backside of the diaper.

A principal feature of the present invention is the provision of an absorbent article of simplified construction having improved fluid dispersing and retention capabilities.

The article of the present invention comprises, a backing sheet of fluid impervious material, a fluid pervious cover sheet, and a first absorbent pad adjacent the cover sheet comprising a loosely formed fibrous mass. The article has a separate second absorbent pad intermediate the first pad and the backing sheet, with the second pad comprising a mass of fibres having a compressed region extending throughout a substantial part of the second pad.

The average inter-fibre spacings in the second pad are substantially less than the average interfibre spacings in the first pad.

A feature of the present invention is that the compressed area of the second pad absorbs body fluids from the first pad and rapidly transmits the fluids to remote locations of the second pad.

Another feature of the present invention is that the dispersed fluids are retained in the compressed area of the second pad at a location spaced from the cover sheet.

Thus, an advantage of the present invention is that the pads minimize back wetting of the body fluids through the cover sheet and maintain the cover sheet in a relatively dry condition during use of the article.

Yet another advantage of the present invention is that the pads may be made in a simplified manner and at a reduced cost.

The invention may be put into practice in various ways and a number of specific embodiments will be described to illustrate the invention with reference to the accompanying drawings, in which:~ Figure 1 is a fragmentary front plan view of an absorbent article of the present invention in the form of a disposable diaper; Figure 2 is a fragmentary sectional view taken along the line 2-2 of Figure 1; Figure 3 is a perspective view of the article of Figure 1 as folded into a box-pleat configuration; Figure 4 is a top plan view partly broken away for clarity of another form of disposable diaper.

Referring now to Figures 1 and 2, there is shown a disposable absorbent article generally designated 20 which is illustrated in the form of a disposable diaper. Although for convenience the article of the present invention will be described as a disposable diaper, it will be understood that the principles of the invention are equally applicable to other disposable absorbent articles, such as sanitary napkins and underpads.As shown, the article or diaper 20 has an absorbent pad assembly 21 having a fluid impervious backing sheet 22, such as polyethylene, defining a back surface 23 of the pad assembly, which covers the back surface 28 of the pad 26, a fluid pervious top or cover sheet 24, such as non-woven material, defining a substantial portion of a front surface 25 of the pad assembly, and an absorbent pad generally designated 26 intermediate the backing sheet 22 and the cover sheet 24. With reference to Figure 1, the diaper 20 may have a pair of tape fasteners 38 for securing the diaper about an infant during placement, and the backing sheet 22 may have lateral side margins 32 folded over and secured to the cover sheet 24 such that the margins 32 cover side portions of the pad 26.

As shown in Figures 1 and 2, the absorbent pad 26 has a first absorbent pad or layer 40 located adjacent the cover sheet 24 and second absorbent pad or layer 42 located intermediate the first pad 40 and the backing sheet 22. The pad 26 may have a top wadding sheet 34 covering a front surface 30 of the upper first pad 40 and back wadding sheet 36 covering a back surface 28 of the lower second pad 42. In one form, as shown, a back surface 41 of the first pad 40 may be placed against a front surface 43 of the second pad 42, or, in an alternative form, a fluid per vious sheet, such as a wadding sheet, may be inter posed between the first and second pads 40 and 42, respectively.

The first pad 40 is made from a loosely formed mass of fibres, such as comminuted wood pulp referred to in the art as fluff. Although the first pad may be compacted, if desired, the first pad 40 may have minimal compression in order to obtain a soft, fluffy front pad 40 with relatively large inter-fi bre spacings.

The density of the top pad 40 should be between about 0.03 g/cm3 and about 0.07 glcm3, preferably between about 0.04 g/cm3 and about 0.07 g/cm3 and more preferably between about 0.06 g/cm3 and about 0.07 glcm3. The second lower pad 42 is also made from a mass of fibres, such as comminuted wood pulp, similar to pad 40 but this pad is prepared as by compression or any other suitable conventional means, to a density of between about 0.14 g/cm3 and about 0.22 glcm3, preferably from about 0.16 g/cm3 and 0.20 g/cm3, and more preferably from about 0.18 g/cm3 and 0.20 g/cm3. Within the aforedescribed parameters of densities, it is desirable that the ratio of the density of the lower pad 42 to that of the top pad 40 be from about 1.5:1 to about 7:1, preferably about 2:1 to about 5:1 and more pre ferablyfrom about 2::1 to 4:1. The densities are, of course, simply determined from a given weight of a measured volume (length x width x thickness with the latter measured as described below).

The thicknesses of the pads may vary widely but, in general, they are combined to give an overall thickness of about 40 mils to 1500 mils (about 1 mm to about 40 mm) with ratios of thicknesses of top to bottom pad ranging from about 50:1 to 1:1, preferably 20:1 to 2:1, and more preferably 10:1 to 4:1. All thicknesses are based upon measurements with a load of 4.1 g/cm2 on the pad since without such an applied load the loftiness and resiliency of the fluff pad would give varying values. Density parameters are then based on such thickness determinations.

For infant diapers total pad thickness will, obviously, generally be lower than for adult incontinence pads and diapers and for feminine sanitary napkins.

Typical newborn infant diapers may have total pad thickness of about 1 mm to about 6 mm or about 2mm to about 10 mm depending on the diaper style.

For larger babies, pad thickness totals may range from about 2 mm to about 8 mm or about 3 mm to about 12 mm. Sanitary napkin pad totals typically may range from about 3 mm to about 10 mm, or about 4 mm to about 20 mm or more, e.g. about 6 mm to about 40 mm, again, depending on the particular style of the sanitary napkin.

Further, it may be desirable to point out that total pad fluff weights will, of course, vary considerably as do thicknesses and sizes of the pads. As a guide, such weights may vary from about 10 to 20 grams up to about 100 grams. Again, generally, the ratio of the weights of the top to bottom pads may vary from about 2:1 to 1:2 but preferably will be about the same, particularly as this permits the greatest facility in manufacture. Thus, for example, a single web of fluff can be formed in any of the conventional ways, then split and the one for the bottom layer compres sed as desired in accordance with the present inven tion.

In use, the diaper 20 is secured about an infant by the tape fasteners 38. During voiding, urine passes through the cover sheet 24 into a localized portion of the first pad 40, and due to the relatively small interfibre spacings in the compressed second pad 42, the fluids are rapidly absorbed from the first pad 40 by the second pad 42. Also, the compressed pad 42 transmits the fluids to pad portions which are remote from the point at which the urine was applied to the diaper.Although a relatively large amount of fluff material has been compressed in producing the pad 42 and thus it has a smaller fluid holding capacity than the pad 40 due to the relative size of their interfibre spacings, the rapid spreading of the fluid throughout pad 42 permits the overall pad composite 26to retain substantially as much fluid as an equivalent weight uncompressed pad assembly much like reservoirs which retain the body fluids in localities but due to the more rapid and efficient spreading of the urine there is much less leakage after each urination and also a marked reduction in back wetting thereby maintaining the top sheet 24 in a relatively dry condition.In this manner, the first and second pads 40 and 42, respectively, cooperate to rapidly disperse fluids throughout the second pad 42 while making maximum use of the pad material and maintaining the top sheet 18 in a relatively dry state.

As previously indicated, the first pad 40 is relatively soft and conformable since it is relatively uncompressed. Accordingly, the first and second pads 40 and 42 respectively, provide a pad structure for the diaper which is soft and conformable to the shape of the wearer in order to maximise comfort and provide an excellent fit of the diaper. In addition, the pad 26 of the present invention may be made in a simplified manner by compressing the second pad 42 and by then placing the first pad 40 against the second pad 42 during manufacture of the diaper.

Thus, the diaper is made without the necessity of wetting and drying the compressed regions which would otherwise add to the complexity and cost of manufacture.

Referring to Figure 3, the pad assembly 21 of Figure 1 may be folded along a plurality of longitudinally extending fold lines to define a box-pleat con- - figuration of the diaper. Thus, the diaper is folded along a pairoffirstfold lines 50to define a longitudinally extending central panel 52 and along a pair of second fold lines 54 to define a pair of longitudinally extending first panels 56 intermediate the fold lines 50 and 54 and a pair of outermost panels 58 extending from the second fold lines 54.

Referring to Figure 4, the diaper 60 is of an hourglass configuration having a crotch area 62 and four portions of greater width defining ears 64, 66, 68 and 70. The diaper includes a backing sheet 72, e.g. of polyethylene, and a top sheet 74, similarly as in the box-pleated diaper. An absorbent pad assembly 75 similar to pads 26,40 and 42 of the box-pleated diaper is disposed between the top and backsheets.

Waddings 77 similar to 34 and 36 of the box-pleated diaper may be provided similarly as in the boxpleated diaper. The pad assembly including wadding sheets are of lesser dimensions, as indicated than the top and backsheets which are of similar dimensions.

In a product blind test of 106 users comprising a first standard pad diaper (pad of 36 grams wood fluff of uniform density of 0.1 g/cc- pad size 300 mm x 409 mm) with a second 2-layer pad diaper in accordance with the present invention of similar dimensions and weight as the first diaper but wherein the top pad of the second diaper has a density of 0.06 gicc and the bottom pad a density of 0.2 g/cc, it was found as follows: prefer double fluff prefer nopre Layer std. ference ratio B B B -overall preference 41 21 38 +1.49+ - drier bottom 35 20 45 +1.36 - strength 34 9 57 +1.65+ ~absorption 37 21 42 +1.38 ~overall fit +1.02 - fit at thighs -1.08 ~thickness 33 15 52 +1.44 leakage occurrence 33 40 diaper could absorb if needed.

25 15 The overall preference ratio of +1.49 is statistically equivalent to a +2 sigma preference for the 2-layer pad diaper and indicates at a 95% confidence level that a majority would prefer the 2-layer pad diaper to the conventional single pad diaper.

Claims

1. A disposable absorbent article comprising, a backing sheet of fluid impervious material, a fluid pervious cover sheet, a first absorbent pad adjacent the said cover sheet comprising a loosely formed fibrous mass, and a separate second absorbent pad intermediate the said first pad and backing sheet, the said second pad comprising a mass of fibres, and being more dense than the said first pad throughout.

2. An article as claimed in Claim 1 in which the average interfibre spacings in the second pad are substantially less than the average interfibre spacings in the first pad.

3. A disposable absorbent article comprising, a backing sheet of fluid impervious material, a fluid pervious cover sheet, a first absorbent pad adjacent the said cover sheet comprising a loosely formed fibrous mass, and a separate second absorbent pad intermediate the said first pad and backing sheet, the said second pad comprising a mass of fibres, and being more dense than the said first pad throughout at least part of the second pad with the average interfibre spacings in the said second pad being substantially less than the average interfibre spacings in the said first pad, the said regions rapidly transmitting body fluids to remote locations of the second pad for retention in the said areas at a location spaced from the cover sheet.

4. An article as claimed in Claim 1,2 or 3 in which the combined thickness of the first and second pad varies from 1 to 38 mm.

5. An article as claimed in Claim 1,2,3 or 4 in which the ratio of the density of the second pad to the density of the first pad ranges from 1.5:1 to 7:1.

6. An article as claimed in Claim Sin which the ratio of the densities is from 2:1 to 4:1.

7. An article as claimed in any one of Claims 1 to 6 in which the said more dense part of the second pad extends to the side and end edges of the second pad.

8. An article as claimed in any one of Claims 1 to 7 including a top wadding sheet covering a front surface of the first pad.

9. An article as claimed in any one of Claims 1 to 8 including a back wadding sheet covering a back surface of the second pad.

10. An article as claimed in Claim 9 in which the said back wadding sheet is compressed.

11. An article as claimed in any one of Claims 1 to 10 in which the first pad has a density of from 0.03 to 0.07 g/cm and the second pad has a density of from 0.14to 0.22 g/cm.

12. An article as claimed in any one of Claims 1 to 11 in which the ratio of the first to second pad thicknesses ranges from about 20:1 to about 2:1.

13. An article as claimed in any one of Claims 1 to 12 in longitudinally oriented box-pleated configuration.

14. An article as claimed in Claim 13 substantially as specifically described herein with reference to Figures 1,2 and 3 of the accompanying drawings.

15. An article as claimed in any one of Claims 1 to 12 in a generally hour-glass orwaisted shape or configuration and including elastic means in the lateral central area for better conformability around the legs of a person using same.

16. An article as claimed in Claim 15 substantially as specifically described herein with reference to Figure 4 of the accompanying drawings.