FR2617682A1 - Nappy-pants with external envelope in fibrous material - Google Patents

Abstract

Nappy-pants whose liquid-impermeable outer envelope 1 is formed from a fibrous material, preferably a nonwoven, which, treated so as to be impermeable to liquids, has the appearance, feel and flexibility of a textile and a tear strength enabling it to withstand forces due to the attachment devices 9 serving to close the nappy-pants.

Description

 PANTY LAYER WITH EXTERNAL FIBROUS MATERIAL.

 The present invention relates to a disposable diaper of the type comprising an outer shell impermeable to liquids, an absorbent mattress disposed on the inner face of the impermeable envelope, an inner sheet permeable to liquids, and devices for clip to close the diaper.

 On known diapers of this type, the outer covering consists of a sheet of plastic, most of the time a sheet of polyethylene. The fastening devices generally consist of two adhesive fastening devices (see for example US Patents 3,180,355, 3,630,201, 4,047,530, 4,049,001, 4,050,453 and French Patent No 74 36 169). Each fastening device generally comprises an adhesive tab fixed on a part of the external envelope of the diaper, in particular on the rear part and coming to stick, when the diaper is closed, on the external face of the other part of the external envelope, in particular of the front part.

 The plastic sheets used to form the outer covering of known diapers must have a minimum thickness determined as a function of the tear resistance that these sheets must offer in order to withstand the forces due in particular to the fastening devices, when closing and during the use of diapers. It turns out that on polyethylene sheets, this minimum thickness is of the order of about 20 μm. However, the polyethylene sheets having such thicknesses have a feel 1, relatively hard and rigid plastic similar to that of paper, lack flexibility and emit a noise similar to the screeching of paper when they undergo deformations. if they are subjected to a treatment (embossing) aimed at removing their plastic smoothness, such sheets retain an appearance, a feel and a lack of flexibility which clearly differentiate them from textile products and which can lead to a certain reluctance to the use of diapers comprising such sheets of plastic material as outer envelopes.

 In addition, until now, the diapers, when they are laid, have a "bent" appearance due to the lack of flexibility in bending and elongation of the outer plastic sheet, as well as the thickness of the mattress. absorbent.

Recently, diapers with thinner mattresses have been found on the market, containing so-called superabsorbent materials. However, these diapers nevertheless retain the "roped" appearance due to the presence of an outer envelope constituted by a sheet of relatively thick plastic material, therefore rigid.

 It often happens that we want to reopen a diaper, for example to check if the child has wet the absorbent mattress, and close it if the absorbent mattress is not yet wet. The same problem of reopening and reclosing the diaper can arise when we want to correct the holding of the diaper, for example in order to tighten it at the waist.

However, it turns out that such an attempt to open on a diaper to be thrown on which the outer envelope is constituted by a sheet of plastic material causes either the tearing of the adhesive tab of the fastening device or the tearing of the area of the sheet to which the adhesive tab adheres, this torn area of the sheet remaining stuck on the adhesive tab.

In either case, it is no longer possible to close the diaper which is thus unusable, although the absorbent mattress may not yet be wet.

 We know from US Patents 3,867,940 and 4,296,750 the use, on disposable diapers provided with adhesive fastening devices, of reinforcement zones placed inside the waterproof sheet forming the envelope. of the diaper, in order to facilitate subsequent peeling and re-gluing of the adhesive fastener on the outside of the waterproof sheet.

 US Patent 4,210,144 provides for using as a reinforcement zone, for the same purpose, a plurality of cords of a hot liquid adhesive, said cords being arranged transversely and spaced from each other. These cords are normally arranged inside the waterproof sheet, between the latter and the absorbent mattress.

 It has also already been proposed (French patent application No. 2,516,757) to glue a plastic reinforcement strip having greater tear resistance than the waterproof outer sheet of a diaper, permanently on the outer face of said sheet, in the areas of the front part provided for receiving the adhesive fasteners when the diaper is closed. This outer band strengthens the waterproof sheet and allows repeated bonding and peeling of the adhesive fasteners.

 The subject of the present invention is a disposable diaper which, while providing the same hygienic effects and in particular the same capacity for absorbing liquids and the same sealing as a usual diaper with an external envelope. made of plastic, has a more pleasant appearance and a softer feel similar to that of a textile, conforms better to the shape of the body and gives on the whole the impression of constituting a textile panty rather than a diaper . A subject of the invention is also a diaper to be thrown away after use with a "textile" appearance and feel allowing repeated closings and openings using conventional adhesive fastening devices.

 On the diaper according to the invention, the cover is formed of a fibrous material which, treated so as to be impermeable to liquids, has the appearance, the feel and the flexibility of a textile and a resistance to tear allowing it to withstand the forces due to the fastening devices.

 Such a diaper, preferably provided with a thin mattress, containing superabsorbent material, conforms perfectly to the body, without "sausage" like the usual diapers.

Indeed, the external envelope, due to the "textile" nature of its fibrous constituent material, has a flexibility clearly greater than that of a plastic sheet having a comparable tear resistance. The treatment which this fibrous material undergoes solely with a view to waterproofing the external envelope and not with a view to strengthening the fibrous material at most negligibly alters this flexibility which still remains much greater than that of an envelope external consisting only of a plastic sheet.

 With its appearance and its "textile" and soft feel, the diaper according to the invention thus resembles, once fitted, more like textile pants than a usual diaper.

 The diaper according to the invention can be equipped with all the usual fastening devices for diapers (for example fasteners of the hook-and-loop type with hooks and loops, adhesive fasteners, etc.).

 If adhesive fasteners are used, it is possible, in order to ensure sufficient adhesion to the outer face of the non-fibrous material of the outer shell, to use a stronger adhesive than on the fasteners intended for diapers. -pants with external envelope in plastic sheet.

 However, according to a preferred embodiment, the fibrous material of the external envelope is treated externally in the zones intended to receive the adhesive portions of the tabs for fixing the fastening devices by adhesive, so as to present in these zones a coherent surface. keep on going.

 Without this treatment of the outer face of fibrous material of the impermeable outer envelope, the adhesion of the adhesive portions of the fixing tabs on the fibrous material would be very reduced since it would only take place on individual fibers and not on a continuous coherent surface. In addition, repeated peeling and re-sticking of the adhesive portions of the fixing tabs would not be possible since on each take-off, fibers would be torn off from the fibrous material and would remain stuck on the adhesive portions of the fixing tabs, which would reduce all the more adhesion of said portions during the following bonding on the fibrous material.

 It should therefore be noted that the treatment of the outer face of the impermeable outer shell on the diaper according to the invention is not comparable, from the function point of view, to the outer reinforcement of an impermeable outer sheet. in plastic material as provided according to French patent application 2,516,757. In fact, according to the present invention, this treatment is not intended to reinforce the tear resistance of the impermeable external envelope, but to create, on the outer face of fibrous material of an impermeable envelope, areas with a continuous coherent surface to allow the adhesive portions of the fastening tabs of the fastening devices to stick detachably to this impermeable envelope.

 On the diaper according to the invention, the impermeable outer covering may consist, for example, of a sheet of fibrous material made impermeable by a treatment affecting the fibrous material over the entire thickness of the sheet, for example a dipping treatment. .

 It is also possible to use an impermeable external envelope constituted by a sheet of fibrous material made impermeable by an internal coating.

 Another possibility is to use a sheet of fibrous material lined internally with a plastic film.

 Preferably, the web of textile material consists of a nonwoven.

 The treatment of the outer face of fibrous material of the impermeable outer envelope, to allow the adhesive bonding and release of the adhesive portions of the fastening tabs of the fastening devices by adhesive, may include, for example, the bonding or welding of at least one piece of plastic sheet on the outside of the waterproof envelope.

 Another possibility consists in coating the external face of the impermeable external envelope in the zones intended to receive the adhesive portions of the fixing tabs.

 This coating can be done cold or preferably hot, using an adhesive in the molten state ("hot melt").

 Finally, if a fibrous material containing thermoplastic fibers is used for the waterproof envelope, it is possible, for example using heated tools applied externally under pressure, to cause a fusion of the fibers of the fibrous material. at least on the external face and thus to produce, without addition of material, a continuous coherent external surface making it possible to receive the adhesive portions of the fixing tabs.

 The treatment area of the outer face of the impermeable outer envelope may be in the form of a transverse strip extending substantially over the entire width of the front part of the impermeable sheet.

 However, it is also possible to have the treatment carried on two separate zones arranged in the vicinity of the two lateral edges of the front part of the diaper.

Referring to the appended schematic drawings, several more illustrative and nonlimiting embodiments of a diaper according to the invention will be described below in more detail; on the drawings
Figure 1 is an external view of a diaper according to the invention arranged flat;
Figure 2 is a section, on a larger scale, along Il-Il of Figure 1;
Figure 3 shows a diaper according to the invention, in the firm state;
Figure 4 is a view similar to that of Figure 1, showing another embodiment of the invention;
Figure 5 is a section, on a larger scale along VV of Figure 4;
Figure 6 is a section similar to that of Figures 2 and 5 showing yet another embodiment of the invention.

 As illustrated "in FIGS. 1, 2 and 3, a diaper according to the invention essentially comprises an outer shell or sheet 1 impermeable to liquids, an absorbent mattress 2 and an inner sheet 3 permeable to liquids.

 The impermeable sheet 1 and the permeable sheet 3 have the same shape and are cut out of an hourglass, so as to define a front part 4 and a rear part 5 separated along the longitudinal axis of the diaper by a part of narrower legs 6 delimited by two opposite lateral notches 7 cut from the two overlapping sheets 1 and 3.

 The absorbent mattress 2 which is arranged between the two sheets I and 3 also has an hourglass shape. The mattress 2 is shorter and narrower than the sheets 1 and 3, so that its transverse edges and its longitudinal edges are set back relative to the transverse edges and to the corresponding longitudinal edges of the sheets 1 and 3.

 In the example shown, elastic elements 8 are fixed for example by gluing in the stretched state to the inner face of the outer sheet 1, in the crotch portion 6, between the longitudinal edges (notches 7) of the sheet 1 and the longitudinal edges of the mattress 2, the elastic elements 8 s1 extending parallel to the longitudinal axis of the diaper.

 Two adhesive fastening devices 9 are furried on the lateral edges of the rear part 5, substantially at the level of the rear transverse edge of the mattress 2.

 By longitudinal lines of glue 10 applied to the inner face of the outer sheet 1, over the entire width of the latter (see FIG. 2), the mattress 2 is fixed to the outer sheet 1 and the permeable inner sheet 3 is fixed to sheet I all around the mattress 2.

 The outer sheet 1 impermeable to liquids consists of a fleece of nonwoven 11- lined with a plastic film 12, the fleece of nonwoven 1 constituting the outer face and the plastic film 12 constituting the inner face of the impermeable sheet 1. The web 11 and the film 12 can be assembled for example by gluing, by welding, by hot calendering, or preferably by extrusion of a film of thermoplastic material, for example polyethylene, directly on the nonwoven. The nonwoven 11 can then advantageously consist of a nonwoven of viscose fibers and or fibers of a thermoplastic material having a softening temperature higher than that of the material of the film 12.

 As illustrated in FIG. 1, a strip of plastic material 13 is permanently bonded to the outer face of the impermeable outer sheet 1, that is to say on the nonwoven 11, transversely to the length of the diaper, over most of the width of the front portion 4. The width of the strip 13 is greater than the width of. fastening devices 9, these widths being measured along the longitudinal axis of the diaper. This bonding is carried out using an adhesive ensuring a bonding force of the strip 13 with the nonwoven 11 which is at least equal to the tearing force of the impermeable sheet 1.

 The strip 13 is made of a material offering a continuous coherent external surface, for example polypropylene.

 The strip 13 permanently fixed to the nonwoven 11 of the impermeable outer sheet 1 of the diaper is intended to receive, in a visible manner in FIGS. 2 and 3, when the diaper is closed, the tongues adhesive fasteners 9.

 As shown above in FIG. 2, each adhesive fastening device 9 comprises, in the usual manner, a fixing tab 15 comprising a fixing portion 16 fixed permanently by means of a layer of adhesive 17 on the external face of the sheet 1, that is to say on the outer face of the nonwoven 11. An anchoring element 18 is fixed permanently by means of a layer of adhesive 19 on the edge of the inner face of the impermeable sheet 1, that is to say on the inner face of the inner sheet 3. On its opposite face, that is to say its inner face, the anchoring element 18 has an anti- adhesive 20, for example silicone-based.

On this non-stick layer 20 is temporarily bonded, until the use of the diaper, the adhesive portion 21 of the fixing tab 15, this portion 21 having a layer of adhesive 22 and being folded, before use of the panty layer, inwards on the non-stick layer 20 of the anchoring element 18. The fixing tab 15 also has, at its free end, a fold 23 facilitating the gripping of the tab 15 for allow the adhesive portion 21 of the anchoring element 18 to take off. Such adhesive fastening devices are well known.

 In FIG. 2, an adhesive fastening device 9 is shown opposite the part of the strip 13 on which it is intended to be glued, the adhesive portion 21 detached from the anchoring element 18 being ready for be fixed on the strip 13.

 Thanks to the presence of this strip 13 on the outer nonwoven 11 of the waterproof sheet 1, the adhesive portion 21 of the fixing tab 15 can be fixed without problem on the sheet 1, despite the fibrous nature of the outer face of this sheet. In fact, the strip 13 offers a continuous coherent surface ensuring very good adhesion, on the sheet L, of the adhesive portion 21 of the tongue 15, and nevertheless allowing repeated peeling and re-sticking of the adhesive portion 21, without risk. damage to the nonwoven 11 by tearing off the fibers of the latter.

 FIGS. 4 and 5 represent a variant of a cover layer according to the invention in which the waterproof outer casing or sheet 31 is formed from a fleece of nonwoven 32 made waterproof by an interior coating 33. Two reception areas 34 for the adhesive portions of the adhesive fastening devices 9 fixed to the rear part 5 are provided on the front part 4 of the diaper. Each of the two reception zones 34 is constituted by a coating of the external face of the external sheet 31, that is to say of the nonwoven 32. The length of each coating zone 34 perpendicular to the direction-- longitudinal of the diaper is chosen so that the zones 34 can receive the adhesive portions of the fixing tabs 9 in all the positions corresponding to the different waistlines for which the diaper is provided.

 FIG. 6 illustrates another variant of diaper in accordance with the invention, with an impermeable outer envelope or sheet 41 constituted by a nonwoven of fibers of thermoplastic material made impermeable by treatment in the bath. Areas 42 for receiving the adhesive portions of the fastening tabs of the adhesive fastening devices are here formed by compression of the nonwoven 41 with heating from the external face, which causes the fibers constituting the nonwoven 41 to melt. , at least on the outer surface of the nonwoven.This fusion of the fibers can be done for example by passing the nonwoven 41 between two rollers, one of which, bearing raised portions corresponding to the zones 42, is heated so that said portions are brought to a temperature higher than the softening temperature of the thermoplastic fibers of the nonwoven 41. By the combined action of heating and compression, the fibers of the nonwoven merge with the outer surface of this the latter so as to constitute, in the zones 42, a coherent and continuous surface on which the adhesive portions of the fastening devices can be glued and peeled repeatedly, without laughing risk of damage to the nonwoven 41.

 The outer sheet according to Figures I to 3, composed of a nonwoven web and a plastic film, can be formed for example by doubling by bonding a nonwoven using a plastic sheet. In this case, the constituent materials of the fibers of the nonwoven and of the film can be chosen as desired.

 On the other hand, in case of assembly of the nonwoven with the hot film, for example by calendering or preferably by extrusion of the film directly on the nonwoven, it is necessary to choose a film constituted by an appropriate thermoplastic material. If a nonwoven consisting of fibers which are not thermoplastic, for example viscose fibers, is used, the film may be made of a thermoplastic material whose softening temperature is sufficiently low for the film to become finding at this temperature does not cause any alteration of the fibers of the nonwoven when it comes into contact with the nonwoven.

 If a nonwoven containing fibers of thermoplastic material is used, it is preferable to use, for the film, a thermoplastic material whose softening temperature is higher than the softening temperature of the thermoplastic material fibers of the nonwoven.

 By way of example, it is possible in this case to use on the one hand a polyethylene film and on the other hand a nonwoven containing for example fibers of polypropylene, polyamide and / or polyester, optionally mixed with non-thermoplastic fibers, for example viscose fibers. The use of well-known "two-component" type fibers for hygiene articles is also possible within the framework of the invention, under the same conditions as those indicated for single-material fibers.

 The nonwovens used in the context of the invention for the external envelope may be nonwovens, preferably carded, in which the fibers are bonded in a manner known per se chemically, thermally and mechanically ( needling).

These nonwovens must be chosen so as to provide the external envelope with its strength, that is to say its resistance to tearing. The internal plastic film 12 of the embodiment of FIGS. 1 to 3 practically does not contribute to the resistance of the envelope and only serves to ensure the impermeability to liquids of the envelope. This film can therefore be very thin, for example less than 10 μm and even less than 51 μm, and thus practically does not affect the flexibility of the nonwoven.

 The waterproof envelope according to the embodiment of FIGS. 4 and 5 can be produced by internal cold or hot coating of a sheet of nonwovens. The external partial coatings of the nonwoven fabric to form the zones for receiving the adhesive portions of the fastening tabs of the fastening devices are preferably made hot using hot melt adhesive when the manufacture of diapers.

 The woven fabric which also here alone provides its strength to the envelope and must be chosen accordingly can be coated internally for example with polymers containing carboxylic groups, in particular latexes resulting from the polymerization or copolymerization of monomers with carboxylic groups such as acrylic or methacrylic acids. Mention may be made, as preferred latex, of dispersions of acrylic copolymers sold under the name "Appretan" by the company Hoechst, RFA.

These latexes can be applied in a pasty form or preferably in the form of a foam so as not to affect the flexibility of the nonwoven.

 Another possibility consists in coating the interior face of the nonwoven using an adhesive-in fusion ("hot melt"), for example according to the coating technique of the company ACUMETER LABORATORIES, Narlborough, MA, USA .

 The nonwoven used for the external envelope of the embodiment of FIG. 6 must comprise fibers of thermoplastic material to allow the production by fusion of the fibers of the reception areas with a continuous coherent external surface for the adhesive fasteners.

 This nonwoven is previously subjected in its thickness to a treatment to make it impermeable to liquids, consisting for example of the application, by impregnation or immersion, of a solution or emulsion such as those commonly used to make hydrophobic non- woven fabrics serving as an internal protective sheet for diapers. On the nonwoven used for the outer covering of the diaper according to the invention, this treatment produces, due to the greater thickness of the nonwoven, a waterproofing for liquids, while the nonwoven may remain permeable to air and vapor.

 I1 should also note that the outer shell of the diaper according to the invention has been defined above as being impermeable to liquids. On the other hand, in all of the embodiments, the envelope can advantageously be permeable to air and to vapor, so as to allow "breathing". This air permeability can for example be obtained by the use of an internal film of microperforated plastic material in the embodiment of FIGS. 1 to 3, or by the use of a mass of microporous coating in the embodiment of FIGS. 4 and 5.

 it should also be noted that the different variants of constitution of the outer shell impermeable to liquids and the different embodiments of the zones for receiving the adhesive portions of the tabs for fixing the fastening devices by adhesive can be combined in different ways from those described and represented. Thus, for example, these reception zones could be formed by external coatings (34) according to FIGS. 4 and 5 on a nonwoven (11) lined internally with a plastic film (12) according to FIGS. 1 to 3.

 In the description, the expression "adhesive fastening device" should be understood to mean a fixing means which can be glued by pressure to a support. All known fastening devices of this type can be used in the context of the invention, but one can also envisage the use of other fastening devices, for example of the hook-and-loop type (with hooks and loops) .

 Finally, the invention is applicable to all types of pants, with or without indentations in the crotch area, with or without elastic at the waist and / or between the legs, with absorbent mattresses of all shapes, etc.

 In all cases, the constitution of the outer waterproof envelope from a sheet of fibrous material, for example a nonwoven, "which gives this envelope both its solidity and great flexibility while providing it with a feel and a 'textile' appearance, leads to a diaper which is distinguished from the usual diapers by its comfort, its ability to marry the shape of the body, its softness to the touch, its textile aspect and, in particular in case of use of a thin absorbent mattress (1 cm or less thick), containing superabsorbent material, by its discretion, the diaper looks more like a textile panty than a usual diaper with an outer covering plastic sheet. The use of an elastic nonwoven for the outer covering makes it possible, with a plastic coating, to obtain an elastic outer covering as a whole, which further improves the adaptation of the diaper to the body. of the user, thus making the diaper even more discreet.

 Finally, if an attached strip 13 (or two strips of reduced length) is attached to the outer face of the sheet of fibrous material, it is possible to provide prints on this strip (color patterns, trademarks, instructions for use, etc.) which can thus be reported very simply on the fibrous outer face of the outer envelope, while corresponding impressions would be difficult or even impossible to produce directly on the fibrous material of the outer envelope.

Claims (11)

 1. Disposable diaper comprising an outer shell (1, 31, 41) impermeable to liquids, comprising a front part (4), a rear part (5) and an intermediate crotch part (6) , an absorbent mattress (2) arranged on the inner face of the impermeable envelope (1), 31, 41), an internal sheet (3) permeable to liquids fixed on the interior face of the impermeable envelope in the uncovered places by the mattress, around the latter, and fastening devices (9) fixed to the waterproof casing, on the opposite lateral edges of the rear part (5), - in order to close the diaper, characterized by the fact that the waterproof envelope (1, 31, 41) is formed of a fibrous material which, treated so as to be impermeable to liquids, has the appearance, the feel and the flexibility of a textile and a resistance to the tear allowing it to withstand the forces due to the fastening devices.  2. Diaper according to claim 1, characterized in that the impermeable envelope is formed of a sheet of fibrous material (11) lined internally with a plastic film (12).  3. Diaper according to claim 1, characterized in that the impermeable envelope is formed from a sheet of fibrous material (32) provided with an inner coating (33).  4. Diaper according to claim 1, characterized in that the impermeable envelope is formed from a sheet of fibrous material (41) # made waterproof by treating the sheet in its thickness.  5. Diaper according to any one of the preceding claims, characterized in that # the web of fibrous material is constituted by a nonwoven.  6, diaper according to any one of the preceding claims, equipped with adhesive fastening devices each comprising a fixing tab which is fixed to the rear part and of which a portion provided with a layer of adhesive sensitive to pressure can be bonded to the outer face of the impregnable cover, in the front part, to close the diaper, characterized in that the fibrous material of the impermeable cover is treated externally in the zones intended to receive the positions adhesive fastening tabs so as to present in these areas a continuous coherent surface.  7. Diaper according to claim 6 characterized in that the treatment in the receiving areas of the adhesive portions consists in bonding at least one sheet (13) on the outer face of the impermeable envelope.  8. Diaper according to claim 6, characterized in that the treatment in the receiving areas of the adhesive portions consists in coating the outer face of the impermeable sheet.  9. Diaper according to claim 6 characterized in that said fibrous material comprises fibers of thermoplastic material and that said treatment in the receiving areas of the adhesive portions consists of compression of said material with heating from the outside, in view of the fusion of the fibers at least on the outer surface of the fibrous material.  10. Diaper according to any one of claims 7 to 9, characterized in that said treatment is carried out on an area corresponding to a transverse strip extending over most of the width of the diaper.  11. Diaper according to any one of claims 7 to 9, characterized in that said treatment is carried out on two separate areas in the vicinity of the two lateral edges of the diaper.