IE45554B1

IE45554B1 - Absorbent articles

Info

Publication number: IE45554B1
Application number: IE1661/77A
Authority: IE
Original assignee: Colgate Palmolive Co
Priority date: 1976-08-09
Filing date: 1977-08-08
Publication date: 1982-09-22
Also published as: BE857608A; JPS5321888A; GB1566594A; DE2734708C2; AU516668B2; AT366243B; BR7704997A; CH619600A5; IT1079991B; FR2361079B1; ES238917Y; JPS6338442B2; CA1092332A; ATA573077A; ZA774047B; NL7708487A; ES238917U; GR67256B; MY8300128A; AU2683677A

Abstract

The absorbent structure has a water-permeable inner layer (28) and a water-impermeable outer layer (24) between which an absorbent basic body (32) is arranged. The basic body (32) has a liquid-absorbing region (58) next to a central part thereof, and a hydrocolloid-containing region (60) spaced apart from the liquid-absorbing region (58). Thus, there is virtually no hydrocolloid in the liquid-absorbing region (58). As a result there is no layer preventing entry of more liquid in the liquid-absorbing region. In addition, remoistening of the liquid in the central region (58) is avoided. The absorbent structure can be used for nappies, clinical substrates or sanitary towels.

Description

The present invention relates to absorbent articles.

Various absorbent articles, such as disposable diapers and sanitary towels, have been proposed for absorbing and retaining body fluids. Such articles have comprised an absorbent pad having a relatively large volume of pad material, in order to provide the necessary absorbency and fluid holding capacity for the articles, whioh adds undesired bulk to the articles, For example, disposable diapers are commonly made from a fluid-impervious backing sheet, a fluid-pervious cover sheet, and an absorbent pad, such as a pad of comminuted wood-pulp known in the art as wood fluff, between the backing and cover sheets. The pads of such conventional disposable diapers are relatively bulky, sometimes resulting in a poor fit and discomfort to the infant.

It has been proposed to include highly absorbent materials, such as hydrocolloid polymers, in the pads. In theory, the hydrooolloid materials should permit a reduction in pad bulk while increasing desirable absorbent and fluid-holding characteristics of the pads, since such materials are capable of absorbing and retaining many times their weight in liquid, such as urine or other body fluids. In practice, the use of such materials in absorbent articles has been limited due to difficulties caused by the nature of the materials.

It has been proposed that the hydrocolloid materials be placed in a central- region of the articles at a location where body fluids, such as urine, are 2. -15 5 51 applied to the articles. However, the hydrocolloid materials swell and become gelatinous when wetted, and it has been found that the wetted materials form a film on the pad which decreases the rate of further . fluid penetration into the pad. Thus, although the materials initially absorb the body fluids, they may later cause saturation and back wetting of the fluids in the central fluid-receiving region of the articles. Moreover, in general it is desirable to retain the body . fluids at a location spaced from the point of application to the articles in order to make maximum use of the pad.

An object of the present invention is the provision of an absorbent article of simple construction which absorbs and retains body fluids in an improved . manner.

According to the present invention an absorbent article comprises a fluid-pervious top sheet, a fluid-impervious backing sheet and an absorbent pad between the top and backing sheets, the pad having a . fluid-receiving region in a central portion of the pad and a hydrocolloid material at a location spaced from the pad throughout its thickness in the fluid-receiving region,/the fluid-receiving region being substantially free of hydrocolloid material. For example, the pad may have hydrocolloid material . positioned in opposed margins of the pad adjacent opposed edges of the pad, and a fluid-receiving region between the pad substantially free of hydrocolloid material in a central portion of the pad between the pad margins. 50. The hydrocolloid material enhances the absorbent 3. and fluid-holding capacity of the pad. Body fluids are retained at pad locations spaced from the fluidreceiving region in order to minimize the possibility of pad saturation in the fluid-receiving region and to . maximize use of the pad material.

Since the fluid-receiving region is substantially free of hydrocolloid material this prevents formation of a film by the hydrocolloid material in this region which would decrease the rate of fluid passage into the pad.

. · The backing sheet may have opposed from margins overlying a front surface and the margins of the pad in order substantially to encapsulate the hydrocolloid material with fluid-impervious raaterial and minimize the possibility of leakage from the pad margins.

. The invention may be performed in various ways, and some embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which:Figure 1 is a fragmentary front plan view of . a disposable diaper embodying the invention; Figure 2 is a fragmentary cross-section taken along the line 2-2 of Figure 1; Figure 3 is a plan view of an alternative form of absorbent pad; . Figure 4 is a perspective view of the diaper of Figure 1 folded into a box-pleat configuration; Figure 5 is a fragmentary cross-section of another embodiment; and Figure 6 is a fragmentary, cross-section of a . further embodiment. 4.

Although for convenience the invention is' described as applied to a disposable diaper, it is applicable also to other absorbent articles, such as sanitary towels and maternity napkins.

. Referring to Figures 1 and 2, there is shown a disposable diaper 20 having an absorbent pad assembly 22. The pad assembly 22 has a fluid-impervious backing sheet 24, such as a sheet of polyethylene, defining a back surface 26 of the diaper, a fluid10. pervious top or cover sheet 28 defining a front surface 30 of the diaper, and an absorbent pad 32 between the top sheet 28 and the backing sheet 24. The absorbent pad 32 has a pad portion 34 comprising a cellulosic material, such as one or more sheets of cellulosic . wadding or comminuted wood pulp known in the art as wood fluff, a back wadding sheet 36 of cellulosic material defining a back surface 38 of the pad 32, and a front wadding sheet 40 of cellulosic material defining a front surface 42 of the pad 32. The front . and back wadding sheets 40 and 36, respectively, provide structural integrity for the pad portion 34 during use of the diaper.

The pad assembly 22 has a pair of side edges 44 and a pair of end edges 46, and the absorbent pad 32 . has a pair of side edges 48 and a pair of end edges 50.

In a preferred form, the side edges 48 of the absorbent pad 32 are located adjacent the side edges 44 of the pad assembly 22, and the backing sheet 24 has lateral side margins 52 folded over and secured to the top . sheet 28 over the pad 32. The diaper may also have . tape fasteners 54 for use in securing the diaper about an infant.

The absorbent pad 32 has a pair of side margins 56 adjacent the pad side edges 48 and extending longi5. tudinally between the end edges 50 of the pad, and a fluid receiving region 58 between the side margins 56 in a central portion of the pad 32. The side margins 56 of the pad 32 contain a hydrocolloid material 60, while the fluid-receiving . region.at the point of applioation of body fluids to the pad 32 is substantially free of hydrocolloid material. In a preferred form, the hydrocolloid material 60 is dispersed in the side margins 56 sub. stantially throughout their length. In an alternative . form, show in Figure 3, the hydrocolloid material is also located in end margins 61 of the pad adjacent the end edges 50 such that the fluid-receiving region is located in a central side margins 55 and between the portion of the pad between the/end margins 61. As . another possibility (not shown), the hydrocolloid material 60 may be located only in the end margins 61.

The hydrocolloid material 60 may be of any _ suitable type, such as (a) hydrolyzed starch poly. acrylonitrile copolymer H-span, Product 35-A-1OO, . Grain Processing Corp., Muscatine, Iowa, U.S,A., disclosed in U.S. Patent No. 3,661,815) (b) Product No.

XD-8589.01L, which is cross-linked, Dow Corning Chemical Co., Midland, Michigan, U.S,A.5 (c) Product No. SGP 502S, General Mills Chemical, Inc., Minneapolis, . Minnesota, U.S.A.,; (d) Product No. 78-3710, National 6. 15554 Starch and Chemical Corp., New York, New York, U.S.A.; (e) a hydrogel base product, Carbowax, of Union Carbide Corp., Charleston, West Virginia, U.S.A.

(CARBOWAX is a trade mark); or (f) base-saponisied . starch-polyacrylonitrile and graft copolymers, United •States Department of Agiculture, Peoria, Illinois, U.S.A., disclosed in U.S. Patent No. 3,425,971. Such hydrocolloid materials have the capability of absorbing many times their weight in liquids such as urine or . other body fluids, and swell and form a gelatinous mass when wetted. In general the hydrocolloid materials useful in the articles of the present invention may be organic or inorganic, are physiologically non-objectionable (non-toxic), and are characterized by swelling in the . presence of water, by a high affinity for water, and by normally at least partially assuming a suspension in the presence of water. It has been found that the materials tend to form a film when wetted which impedes passage of body fluids into the pad if the materials . are located at the point of application of fluids into the pad, thus causing saturation of the pad and possible back wetting through the top sheet in the fluidreceiving region.

With reference to Figures 1 and 2, the front . surface of the pad portion 34 in the side margins 56 may be wetted slightly, and the hydrocolloid 60 may be placed on the wetted front surface of the pad portion 34 after which the front wadding sheet 40 is positioned over the pad portion 34, such that the hydrocolloid . material 60 is located adjacent the front surface 42 7. of the pad 32, the moisture facilitating retention of the material 60 in the side margins 56. In an alternative form, with reference to Figure 6, the hydrocolloid material 60 may be placed against the . moistened back surface of the pad portion 34 after which the back wadding sheet 36 is positioned over the back surface of the pad portion 34, such that the hydrocolloid material 60 is positioned adjacent the back surface 38 of the pad 32. In either event, the . hydrocolloid material 60 is located in the side or • end margins at a position spaced from the fluidreceiving. region 58 of the pad 32.

In use, the diaper is secured about an infant by use of the tape fasteners 54 in a known manner.

. During voiding, the urine passes into the pad 32 in the fluid-receiving region 58 and spreads to the side margins 56 where the hydrocolloid material absorbs and retains the body fluids at a . . location spaced from the fluid-receiving region 58.

. Thus, the body fluids are retained at pad locations spaced from the point of application to the diaper, in order to make maximum use of the pad material. Additionally, the fluid-receiving region 58 of the pad 32 is substantially free of .the hydrocolloid material, . in order to present formation of a film by the wetted hydrocolloid material in the region 58 which would otherwise impede passage of body fluids into the pad, thus minimizing the possibility of fluid saturation in the region 58 and of accompanying back wetting . from the pad through the top sheet to the infant. 8.

Another embodiment of the present invention is illustrated in Figure 5, in which like reference numerals to those used in Figures 1 and 2 designate like parts. In .this embodiment, the lateral margins . 52 of the backing sheet 24 extend a sufficient distance inwardly from the side edges 48 of the pad 32 to overlie the pad side margins 56. Thus, the backing sheet side margins 52 cover the pad margins 56 and the hydrocolloid material 60, such that the backing . sheet 24 forms fluid-impervious pockets which minimize the possibility of leakage from the pad side margins 56 where the fluids are retained by the hydrocolloid material 60.

With reference to Figures 1, 2 and 4, the . diaper may be folded into a box-pleat configuration as follows. The pad assembly 22 is folded along a pair of first fold lines 62 defining a longitudinally extending central panel 64 between the fold lines 62, and a pair of second fold lines 66 defining a pair of inter20. mediate panels 68 between the fold lines 62 and 66 which overlie the central panel 64. The second fold lines 66 also define a pair of outermost panels 70 extending from the second fold lines 66 and overlying the intermediate panels 68. In a preferred form, as shown, . the lateral side margins 56 of the pad 32 are located in the outermost panels 70 of the folded diaper, such that the intermediate panels 68 separate the central panel 64 and the hydrocolloid material 60 retained in the outermost panels 70.

Claims

1. An absorbent article comprising a fluidpervious top sheet, a fluid-impervious backing sheet and an absorbent pad between the top and backing sheets, 5 the pad having a fluid-receiving region in a central portion of the pad and a hydrocolloid material at a location spaced from the fluid-receiving region, the pad throughout its thickness in the /fluid-receiving region being substantially free of hydrocolloid material. 10

2. An absorbent article comprising a fluidpervious top sheet, a fluid-impervious backing sheet and an absorbent pad between tbe top and backing sheets, the pad having a hydrocolloid material positioned in opposed margins of the pad adjacent opposed edges of 15 the pad, and a fluid-receiving region substantially free of hydrocolloid material in a central portion of the pad between the pad margins.

3. An article as claimed in Claim 2 wherein the backing sheet has opposed margins overlying a front 20 surface and the margins of the pad.

4. An article as claimed in Claim 2 or Claim 3 wherein the hydrooolloid material is dispersed in the pad margins substantially throughout their lengths.

5. An article as claimed in any of Claims 2 25 to 4 wherein the pad has a pair of side edges, and in which the said opposed margins are side margins of .10. 4S5S4 the pad adjacent the side edges, the fluid-receiving region being located in a central portion of the pad between the side margins.

6. An article as claimed in any of Claims 2 5 to 4 wherein the pad has a pair of end edges, and in which the said opposed margins are end margins of the pad adjacent the end edges, the fluid-receiving region being located in a central portion of the pad between the end margins. 10

7. An article as claimed in any of the preceding Claims wherein the hydrocolloid material is located adjacent a front Surface of the pad.

8. , An article as claimed in any of Claims 1 to 6 wherein the hydrocolloid material is located adjacent a back surface of the pad.

9. An article as claimed in any of the preceding Claims which is a disposable diaper.

10. An article as claimed in any of Claims 2 to 5 which is a disposable diaper having a pair of 20 first fold lines defining a longitudinal central panel, and a pair of second fold lines defining a pair of intermediate panels between the first and second fold lines and overlying the central panel and defining a pair of outermost panels extending from the second 25 fold lines, which outermost panels include the said margins of the pad. 11. 4355 4

11. An absorbent article substantially as described with reference to Figures 1 and 2, or Figure 3, or Figure 4, or Figure 5, or Figure 6 of the accompanying drawings.