IE45382B1 - Absorbent articles - Google Patents

Description

The present invention relates to absorbent articles for absorbing and retaining body fluids, such as disposable diapers and sanitary towels.

Such srticles often have a bulky absorbent pad in order to provide the necessary absorbency and fluid-holding capacity, for example, disposable diapers are commonly made from a fluid-impervious backing sheet, a fluidpervious cover sheet, and an absorbent pad made from a material such as comminuted wood pulp, known in the art as wood fluff, located between the backing and cover sheets. The pads of such conventional diapers are bulky, particularly in the crotch region, which may result in a poor fit and some discomfort to the infant.

It has been proposed to include more highly absorbent materials, such as hydrocolloid polymers, in the pads. In theory, the hydrocolloid materials permit a reduction in pad bulk while increasing desirable absorbent and fluidholding characteristics of the pads, since such materials are capable of absorbing and retaining many times their weight of liquid, such as urine or other body fluids. In practice, use of such materials in absorbent articles has been limited due to difficulties caused by the nature of the materials. - 2 4 5 3 8 2 It is preferred that the hydrocolloid materials be utilized in a particulate form, such as granules or flakes, since the particles provide a large surface area in relation to their volume. However, it has been found that when placed in the pad, the particles tend to migrate in the pad before the article has been used by the wearer. Particle migration may take place during packaging, storage, transportation or other handling of the articles, from the initial location of the particles to remote parts of the pad where they are less effective.

When wetted, inc· hydrocGlloid materials swell and become gelatinous, and 10 assume a slippery o»· slimy texture which facilitates further migration of the particles when wetted, causing the pad to become unstable. Thus, it has been found that the wetted materials cause the pads to shift, ball, split and shred during use of the articles.

According to tne present invention an absorbent article includes an 15 absorbent pad assembly comprising a.n absorbent pad, a hydrocolloid material, and means for retaining the hydrocolloid material at a plurality of spaced locations on and projecting from a surface of the pad and permitting passage of body fluids to the retained hydrocolloid material.

Thus the present invention provides an absorbent article in which 20 hydrocolloid material is retained at fixed locations on the pad. The retaining means prevents migration of the hydrocolloid material prior to and during use of the article, and prevents movement of the hydrocolloid material into the absorbent pad during use of the article. preventing degradation of the pad by tne wetted hydrocolloid material.

The invention may be performed in various ways, and some embodiments will now be described by way of example with reference to the accompanying drawings, in which:Figure 1 is a fragmentary plan view of an absorbent article embodying 30 the present invention, namely a disposable diaper; · 3 48382 Figure 2 is a fragmentary' sectional view taken along the line 2-2 of Figure 1; Figure 3 is a fragmentary sectional view of another embodiment; Figure 4 is a diagrammatic plan view of a third embodiment; Figure 5 is a diagrammatic plan view of a fourth embodiment; Figure 6 is a diagrammatic plan view of a fifth embodiment; and Figure 7 is a diagrammatic fragmentary plan view of a sixth embodiment.

In the illustrations and descriptions of the several embodiments, like parts are designated by the same reference numerals.

Referring to Figures 1 and 2, there is shown an absorbent article 20 having an absorbent pad assembly 22. For convenience, the article 20 is described in the form of a disposable diaper, although it will be understood that the invention is applicable to other absorbent articles, such as sanitary towels and maternity napkins.

The pad assembly 22 has a fluid-impervious backing sheet 24, such as polyethylene, defining a back or outer surface 26 of the diaper, a fluidpervious top sheet or cover sheet 28 defining a front or inner surface 30 of the diaper, and an absorbent pad 32 positioned 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 article.

As illustrated in Figure 1, 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 of diaper as illustrated, the side edges 48 of the pad 32 are located adjacent the side edges 44 - 4 Α-ΰ 3 9 3 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 lateral side margins of the pad 32. The diaper illustrated has conventional tape fasteners 54 for use in securing the diaper in place about an infant.

The pad assembly 22 has a retaining sheet 56 positioned between the top sheet 28 and the front wadding sheet 40. The material of the retaining sheet is fluid-impervious except for some perforations referred to below.

The retaining sheet 56 is free of attachment to, and spaced from, the wadding sheet 40 in a plurality <'f spaced regions 58, and is attached to the front surface 42 of the wadding sheet 40 in areas 60 surrounding the regions 58.

Thus, the retaining sheet 56 and the front wadding sheet 40 define a plurality of spaced discrete pockets 62 between the retaining sheet 56 and the front wadding sheet 40, on and projecting from the latter. In the embodiment shown in Figures 1 and 2 the pockets 62 have a generally circular shape, and are aligned laterally across and longitudinally along the pad assembly 22.

Although the retaining sheet 56 may be attached to the front wadding sheet 40 by any suitable mearc , such as adhesive, in a preferred form the retaining sheet 56 comprise' a film of thermoplastic material, such as polyethylene, and the film is fused to the front wadding sheet in the areas 60 by suitable means, such as by localised heating. As shown, the areas 60 of the retaining sheet 56 have a plurality of perforations 64 extending through tne sheet 55 to permit passage of body fluids through the perforations 64 into the pad 32. Although the perforations 64 may be formed in any suitable manner, in one form of the invention small perforations are enlarged by heating when the sheet 56 is fused to the pad, in a manner similar to that described in Patent No. 42300 .. In the present embodiment the retaining sheet 56 is imperforate in the regions 58 to prevent passage of fluids between the pockets 62 and the front surface 30 of the pad assembly 22.

The pad assembly 22 has disposed in the pockets 62 a hydrocolloid material 66, such as (a) hydrolyzed starch polyacrylonitrile copolymer H-span, - 5 4S382 product 35-A-100, Grain Processing Corp., Muscatine, Iowa, U.S.A., disclosed in U.S. Patent No. 3,661,815, (b) Product No. XD-8587. OIL, which is cross-linked, Dow Corning Chemical Co., Midland, Michigan, U.S.A., (c) Product No. SGP 502S, General Mills Chemical, Inc., Minneapolis, Minnesota, U.S.A., (d) Product No. 78-3710, National Starch and Chemical Corp., New York, New York, U.S.A., (e) a hydrogel base product, Carbowax, a trademark of Union Carbide Corp., Charleston, West Virginia, U. S. A., or (f) base-saponified starch-polyacrylonitrile and graft copolymers, United States Department of Agriculture, 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 relatively high affinity for water, and by normally at least partially assuming a suspension in the presence of water. Preferably, the hydrocolloid materials are utilized in a particulate form, such as powders, granules or flakes, althougft they may be coated as a solution on one or more of the sheets defining the pockets, if desired.

The retaining sheet 56 and the front wadding sheet 40 retain the hydrocolloid materials 66 in the pockets 62, and prevent migration of the materials 66 into and throughout the pad portion 34 during transportation, storage, or other handling of the articles prior to use. Thus, the materials 66 are retained at desired locations in the pad assembly 22 for maximum benefit during use, and are prevented from migrating to undesired locations in the pad assembly prior to use of the article.

During use of the article 20, body fluids pass through the perforations 64 of the retaining sheet areas 60 and into the pad 32, after which the body fluids are permitted to pass through the front wadding sheet 40 into the pockets 62 for absorption and retention by the hydrocolloid materials 66. The front wadding sheet 40 has a sufficient wet strength to prevent passage of the wetted hydrocolloid - 6 4 5 3 8 2 material 66 through the wadding sheet 40 into the pad portion 34, such that the wadding sheet 40 serves as a second retaining sheet to retain the wetted materials in the pockets during use of the article. Additionally, the wetted materials 66 are prevented from entering the pad portion 34 to eliminate degradation of the pad, such as shifting, balling, splitting, or shredding of the pad portion 34, which otherwise might occur due to the unstable and slippery texture of the wetted materials 66. Moreover the imperforate regions 58 of the retaining sheet 56 prevent passage of the wetted materials 66 to the front surface o‘ the pad assembly, and thus prevent contact of the wetted materials with the wearer's skin.

However, if desired, the regions 58 of the retaining sheet 56 may have small perforations 68, as shown in Figure 3, smaller than the hydrocolloid particles. Thus, the openings 68 permit passage of body fluids into the pockets 62, but are sufficiently small to prevent passage of the wetter materials to the front surface of the article. The particles swell when wetted, further limiting the possibility of passage of the particles through tre openings 68.

Although the resa'ning sheet 56 has been described as being attached to the front surface of tie pad, it will be appreciated that the sheet may be attached to the back surface of the pad.

Figure 4 is a diagrammatic view showing an arrangement of the pockets.

In this embodiment, the regions 58 and the pockets 62 retaining the hydrocolloid materials have a generally circular shape and are arranged in rows only in a longitudinally central zone of the article ?0. For examole, in a disposable ?£ diaper, the pockets 52 may he located in a crotch region 76 at a point of contact cf body fluids during use of the diaper.

However, as shown in Figure 5, if desired the pockets 62 may be provided only adjacent at least one of the end edges 46 of the article, for example, in waistline portions 78 of a disposable diaper. . 7 .

In an alternative form, as shown in Figure 6, the pockets 52 and regions 58 are elongated, and extend laterally between the side edges 44 of ths article 20.

In a further form, as shown in Figure 7, the elongated regions 58 and pockets 62 extend longitudinally between the end edges 46 of the article 20.

In · Patent No. 45381 from which the present application has been divided there is claimed an absorbent article which includes an absorbent assembly comprising a fluid-pervious top sheet, a backing sheet of fluid-impervious material, a plurality of discrete pockets between the top and backing sheets, and hydrocolloid material in the pockets.

Claims (3)

1. An absorbent article which includes an absorbent pad assembly comprising an absorbent pad, a hydrocolloid material, and means retaining the hydrocolloid material at a plurality of spaced locations on and projecting from a surface of the pad and permitting passage of body fluids to the retained hydrocolloid material.

2. An absorbent article as claimed in Claim 1 in which the pad includes a wadding sheet defining the said surface of the pad, and the pad assembly includes a retaining sheet attached to the wadding sheet in areas and defining between the areas pockets projecting from the said surface of the pad, the hydrocolloid material being in the pockets.

3. An absorbent article as claimed in Claim 2 in which the said wadding sheet defines a front surface of the pad, and the retaining sheet is perforated but otherwise fluid-impervious with a plurality of perforations extending through it in the said areas to premit passage of body fluids into the pad.