NO742261L - - Google Patents

Description

Disposable diaper.

The present invention relates to an improved disposable nappy which comprises an airy laid upper fiber layer with improved strength and smoothness and is arranged so that a part of this layer can be easily delaminated from the rest of the nappy so that excrement on the removable nappy part can be removed independently of the others diaper components.

Disposable nappies have recently seen a rise in sales, both because they are easy to use and because of their improved functional properties, compared to cloth nappies. A typical disposable diaper comprises a porous top layer that is placed close to the infant's skin, an absorbent pad for soaking up liquid that passes through the top layer, and a moisture-impermeable base cloth that holds the absorbed moisture back into the pad.

One of the problems that has arisen in connection with the known embodiments is the inability to provide an appropriate, light and affordable top layer material that is flexible, soft, comfortable and does not irritate infant skin, while at the same time having sufficient strength and dimensional stability and the desired degree of porosity and wettability. Another problem that has only become more serious in recent times is the disposal of disposable nappies that are contaminated with excrement.

With increasing concern for environmental pollution, various regulations follow from the municipal authorities, which prevent human excrement from being thrown together with solid household waste. It is therefore necessary to free the disposable diaper from excrement because it can be thrown away, and this creates aesthetic as well as sanitary problems.

Devices for removing excrement from the used nappy are known from older patents, but they either require separation of the biodegradable nappy components, e.g. top layer and padding from the waterproof base fabric or removing the entire top layer from the waterproof base fabric. Other patents have described absorbent inserts that can be easily removed by an envelope-like liner for disposal.

I.U.S. patent document no. 3,180,335 (Duneau et al.) describes a disposable diaper in which the waterproof underlay cloth is separated from the absorbent material by tearing the latter from its adhesive edges on the underlay cloth. The nappy according to the latter patent consists of a waterproof base cloth and an absorbent padding which is centrally arranged on the base cloth. The padding comprises many layers of creped cellulose padding and is on

one surface (which should face the child's skin) and on all four short sides enclosed by a non-woven top layer. The top layer is glued to the bottom surface of the padding layers and the side and end parts of the top layer, which are on the side of the waterproof base fabric, are glued to this.

After the nappy has been used and removed from the child, the absorbent padding including the top layer is torn from the adhesive bandage with the base cloth. The padding is then dipped several times in the toilet until the main amount of the crimped padding is dissolved into a mass, and flushed down the toilet, the remaining parts of the padding being retained and these remaining parts (top layer and crimped padding) are then flushed down. With the diaper according to patent document 3,180,335, the tear-off option is achieved at the expense of structural stability, as the components adhere to each other exclusively in the side edge areas. This type of bonding can create areas without contact between the padding and the base fabric, so that urine accumulates on the base fabric when the padding is removed from it. As all absorbent material is torn from the underlay, a relatively large volume must also be flushed out into the sewer system, and this can cause clogging.

U.S. patent 2,649,859 (Hermanson et al.) describes a nappy with a waterproof base cloth on which several creped cellulose layers are centrally arranged. A top layer covers the creped layers and is secured to overfolded side portions of the base fabric. In this way, the base fabric and the top layer form a cover that encloses the creped layers. The nappy according to the latter patent is open at each end and the creped layers can be sealed at the sides. When the nappy is to be thrown away, you grab the top layer and the creped layers at one end of the nappy and tear them off the base cloth to throw them in the toilet.

Also the nappy according to the latter patent means that a large volume of absorbent material must be thrown away and can lead to clogging. Although the crimped layers can be sealed along the sides, the above-mentioned liquid accumulation problem can apply here as well. In addition, the tearing off of the absorbent material from the base fabric creates difficulties, as the sticking area on the sides and the overlapping of the base fabric over the top layer can lead to uneven tear lines on the top layer.

The problem of providing a top layer material of suitable strength and smoothness and at low cost has been solved with some success. U.S. patent 3,612,055 (Mesek et al.) describes a diaper with a layer of a uniform mixture of long and short fibers which is bound together with a resin binder and contains a wetting agent to give the top layer the desired degree of wettability. In such a top layer with an even mixture of long and short fibres, the short fibers are utilized for cost reasons and the long fibers for reasons of strength and smoothness. However, the long fibers in the top layer are not utilized to the maximum, as a significant part of the long fibers are located in the inner part of the top layer material, where they do not contribute to the surface smoothness and only partially to the material's strength.

A recently known improvement in diapers involves the use of a top layer comprising a mixture of long and short fibers with a concentration of long fibers (above the general concentration of long fibers throughout the top layer) in the outer surface of the top layer. Such a concentration of long fibers in the outer surface of the top layer gives increased surface smoothness and strength where it is most needed and utilizes the long fibers in the top layer with greater efficiency. The applicant's U.S. patent application, filed June 7, 1962, describes such diapers and will be discussed below.

According to the present invention, a diaper is provided with a top layer of non-woven material, a portion of which can be easily delaminated from the rest of the diaper structure for independent removal and disposal of excrement. This is achieved with a top layer in the form of a layered or laminate-like fabric with long fibers in the outer surfaces and an inner portion of short fibers that form a weakening plane or a weakening zone that facilitates delamination.

Non-woven materials are structures that usually consist of a collection or web of fibers assembled randomly or systematically by mechanical, chemical or other means. These fibers are well known, as they have become increasingly important in the course of the last approx. 25 years on the consumer market, on the industrial market and in the hospital area.

Fibers are usually classified according to their length. The relatively long fibers, or textile fibers, are longer than approx. 6.35 mm and usually between 12.7 and 63.5 mm long. The term "long fibres" often refers here to textile fibers with a length greater than 6.35 mm and the fibers can be natural or synthetic. The term "short fibres" here refers to fibers for paper production, such as wood pulp fibers or cotton fibres, which are shorter than approx. 6.35 mm. Although one is aware that short fibers are usually significantly less expensive than long fibers, it is also clear that in many cases it is desirable to strengthen a product of short fibers by adding a mixture of long fibers.

Savings can be achieved for diapers made of non-woven fibers by using short fibers. Due to the low tensile strength of products made of short fibres, the use of such fibers exclusively will be impractical, as there is little cohesion strength in the fibrous parts of the nappy when there is not a large amount of binder, which in turn can have an adverse effect on the product's "skin friendliness" and increase the general costs. Known diapers with a top layer of short fibers have been undesirable, not only because of their poor tensile strength, but also because of the bent dust effect in that some fibers '31b stood out from the top layer. The manufacture of non-woven fibers for use in nappy top layers has therefore largely been limited to use ra^i^det*'. 'jninste^a significant percentage of long fibres, due to the deft lack of possibility to produce products from short fibers which exhibit the strength, light weight and softness and "skin friendliness"

which usually distinguishes fabrics made from long fibers.

In the nappy according to the present invention, a top layer of a layered fabric is used with a different concentration of long and short fibers in the different layers of the fabric. In order for the product to have the right fall characteristics and feel comfortable against the skin, it is desirable to arrange long fibers in the outer surface of the top unit, which should be in contact with the infant. It is also desirable to arrange a surface with long fibers close to the absorbent padding so that the disposable diaper will hold together. An outer layer with only or mainly short fibers close to the padding and attached to the base cloth in the edge parts is not desirable, as the base is primarily glued to weak, short fibers in these edge parts and the outer layer can thus tear or separate from the base, while the diaper becomes placed on the child.

In order for excrement to be removed from a used nappy, it is desirable to be able to remove a fibrous part of the nappy that includes the excrement. In previously known diapers, this was done by removing at least the entire top layer, so that it was necessary to have minimal adhesion between the top layer and the adjacent elements, which in turn had an adverse effect on the diaper's function. According to the present invention, excrement is removed by removing an outer part of the top layer by dividing this layer along a weakening plane. It is thereby possible to attach the entire edge part of the top layer to the underlay over the entire installation surface between them.

The top unit used in an embodiment of the invention is consequently produced from two half-thick parts, which are bonded to each other in a laminate-like manner so that they form a composite material. The outer half-thickness part is made of long fibers and short fibers in a given average concentration. In order for this lot to have the desired properties in terms of fall and skin friendliness, the outer surface comprises a mixture of long and short fibers that are enriched with long fibers above the average concentration. In order to reduce the costs to a minimum, the inner surface of the outer part comprises a mixture of long and short fibers which are enriched with short fibers above the average concentration. In the outer half-thickness part, the concentration of long and short fibers gradually decreases (ie there is no sharp interface between one and the other concentration). The term "transitional substance" is used to indicate a substance of the type just mentioned.

The inner half of the top unit is bonded to the surface of the outer half enriched with short fibers and is distinguished by an outer surface opposite the surface bonded to the outer half, which has greater structural stability than the short fiber enriched surface of the outer half. In this way, the composite top unit of the diaper according to this embodiment is provided with outer surfaces of considerable structural integrity and with a somewhat weakened inner portion consisting mainly of inexpensive, short fibers. In a particularly preferred embodiment, the second half is similar to the first half and is connected to this in a mirrored arrangement. The process for producing the top unit includes the use of a combination of techniques, such as fiber covering and controlled binder concentration, so that the top layer can be easily torn off along the inner area which is enriched with short fibres.

As a result of its low tensile strength (compared to the outer areas), the inner area can be torn off along the midplane or along the laminate boundary, so that the outer area, which is enriched with long fibers and on which the excrement is deposited, can be separated from the rest of the nappy. As this outer layer is biodegradable, it can be flushed down a normal toilet and then broken down in a sewage treatment plant, so that pollution problems can be avoided without being affected by legal regulations that have been put forward so that excrement is not to be thrown together with solid waste . As the top layer is delaminated, the amount of fiber material to be thrown into the toilet will be greatly limited and the risk of clogging correspondingly reduced

In other embodiments discussed below, the delaminating "layered" structure is used for the top layer to provide a diaper where excrement can be easily removed without large amounts of fibrous material being thrown away.

As discussed in more detail below, preferred embodiments of the present invention are made of a diaper where the top layer has a half-thickness transition fabric portion, which is improved by the addition of a second fabric that has greater structural stability than the short fiber-enriched surface of the transition fabric, so that the following advantages are achieved: a) the top layer has improved skin comfort properties and better strength in the outer layer, b) the tendency for the short fibers in the interior of the composite unit to pile up is reduced to a minimum, c) the total production costs for the top layer is reduced by using the expensive long fibers in an optimal distribution, d) the inner surface of the top layer which is to be attached to the base cloth has sufficient structural stability not to tear or tear away from the base cloth, e) the top layer is easily delaminated to remove excrement from the other diaper parts and f) the total amount of fiber material that must be thrown into the toilet and then ends up in the sewage treatment system et is reduced to a minimum.

Although the composite top layer used in some embodiments of the present invention is described as being made of two halves, it should be noted that the term "half" does not necessarily mean that each part is approximately the same thickness as the other or approximately 50% of the thickness of the composite layer. The halves may have varying thicknesses, but when this is the case, the thinnest part should comprise at least 20% of the total thickness of the composite layer. Fig. 1 shows an open, unfolded nappy according to the invention in perspective and with some parts removed. Fig. 2 is an enlarged partial cross-section of the diaper according to fig. 1, taken along line 2-2 in fig. 1. Fig. 3 shows the diaper in perspective and on a reduced scale, in the form the diaper has in use.

Fig. 4 is an enlarged, partial cross-section of

the nappy's top layer, taken along line 4-4 in fig. 5.

Fig. 5 shows the production line for the production of the nappy in a simplified schematic representation.

Although the invention can be used in embodiments of many different types, a preferred embodiment example and modifications thereof are shown in the drawing and described in detail in the following. However, this description is to be understood exclusively as an illustration of the principle of the invention and is not intended as a limitation of the invention to the example shown and discussed. The scope of the invention will be drawn up in the claims.

As shown in the drawing and particularly in Figs. 1, 2 and 3, the diaper unit 10, when fully open and laid flat, comprises a lower, waterproof base cloth 12 which has a rectangular shape, a highly water absorbent fiber padding 14, which is also rectangular in shape , but is smaller than the waterproof cloth and arranged centrally thereon, as well as an overlapping top layer 16 of fibrous material, which is also rectangular, the same size as the waterproof layer and in contact with the latter in the edge portions of the diaper which continue along the circumference, outside the absorbent padding ,

i.e. in the parts 16b and 12b in the top layer 16 and the base fabric 12, respectively. The padding 14 has an integrated, continuous, paper-like, densified and very compact lower fiber layer 18 which comprises parallel, spaced-apart densified

■■in parts 19 in the form of parallel lines which can continue through the entire cross-section of the quilting. The densified layer 18 is attached to the base fabric 12 by adhesive^drop lines above the

approached the entire construction surface. The edge portions 16b and 12b are also attached to each other by drop lines 22 of adhesive.

In the preferred design of the invention, the waterproof cloth 12 is made of polyethylene with a thickness of approx. 0.025 mm. The cloth can be smooth or embossed in relief to have better drape properties and feel more comfortable. Other suitable, flexible waterproof cloths that can be used according to the invention are. e.g. a polyethylene terephthalate cloth with a thickness of approx. 0.012 mm.

The padding 14 is made of loosely densified, short cellulose fibres, such as wood pulp fibers or cotton linters, held together by known, mutual fiber bonding which does not require adhesive. Briefly, this padding consists of a close-knit, hanging web with a small volume of loosely densified cellulose fibres, preferably finely divided wood pulp fibers in the form of so-called "down".

The paper-like densified layer 18 of padding 14 is formed by lightly wetting a surface of the padding and subsequently applying pressure to it. The characteristics of the wadding and its densified layer and the method for producing these are described in U„S. patent document no. 3,017,304, dated 16 January 1962. The thickened, densified parts 19 are formed by further densification of the padding while it is still moist, as discussed in more detail below.

The combined density of the padding 14, including its densified layer 18, must be over approx. 0.07 g/crn^ and preferably between approx. 0.10 and 0.15 g/cm^. The mentioned density values apply to the nappy, as it is produced.'During storage and handling, the thickness of the padding will increase to some extent, so that the density is reduced.

The top layer 16 is generally made of a given concentration of fibers in the form of short cellulose fibers, such as wood pulp fibers or cotton linters, in amounts of approx. 50% to approx. 98% and the rest in the form of long textile fibres, such as rayon, polyester, cellulose acetate, nylon fibres, etc.

The top layer 16 is preferably formed by joining two transition materials 30 and 30' (Fig. 4). As structural integrity is a main consideration in the formation of the top layer for a diaper according to the invention, in any preferred embodiment of the invention a transition fabric is lined to the second fabric so that the surface of the transition fabric which is enriched with long fibers becomes an outer surface 15 of the top layer. The inner surface 15' of the top layer has greater structural stability than the short fiber-enriched surface of the transition fabric, so that it can be adhered to the waterproof cloth 12 in the edge areas.

Each half of the top layer 16 is preferably formed using an air laying process, e.g. as stated in the U.S. patent application no. This method produces two separate transitional substances which are lined together for formation

of the top layer, with opposite outer surfaces 15 and 15' and a central part 17. The transition zones between the surfaces 15 and 15' and the central part 17 (formed by the inner rafts 13 and 13') are distinguished by decreasing

concentrations of long fibers from the outer surfaces towards the middle part of the product.

The surfaces 15 and 15' comprise a larger proportion by weight of long fibers and a smaller proportion by weight of short cellulose fibers (compared to the average concentration of these fibers in each transition material) in mixture. The central part 17 preferably comprises a larger proportion by weight of short cellulose fibers and a smaller proportion by weight of long textile fibers (compared to the average concentrations of these fibers in each transition material) in mixture. It should be noted that while the middle portion is designated as element 17 for identification reasons, in reality there is no sharp boundary between this and surfaces 13 and 13' as the composition changes gradually.

Each transition fabric is generally made of a given average concentration of short fibers, such as wood pulp fibers or cotton linters, and a given average concentration of long fibers, such as rayon, polyester, cellulose acetate, nylon fibers, etc. The average concentration of long fibers can vary between 2% and 50%, preferably between 10% and 25%, the remaining fibers consisting of short fibers - e.g. blends of 25% rayon fibers and 75% wood pulp fibers.

The proportion of long fibers in the enriched surface of the transition substance is increased by at least 30% of the average concentration, while the proportion of long fibers is reduced by the same value in the wood mass-enriched surface. In the above-mentioned example with an average concentration of 25% rayon fibers and 75% wood pulp fibers, the waterproof cloth 12 and, the top layer 16, together with a part of the padding 14 folded inwards in a first fold, so that a part of the waterproof cloth appears as the top layer in the board. This sub-unit is then folded outwards along each edge into a second fold which covers the first folded portion and allows the edge portions of the top layer to appear as the top layer of the double fold.

In the preferred embodiment, each comprises a double tray

at the edge of the nappy approx. 1/3 of the resulting transverse dimension of the folded diaper and approx. 1/3 of the width of the folded nappy remains unfolded and uncovered in the middle.

The nappy is held in the folded position by means of two small central binder points arranged between the main part of the nappy and the folded sides 16b of the top layer, a binding center point being arranged on each folded nappy side. When the nappy is to be put on the child, the folds on one side of each binder point are opened and the open part of the nappy is placed under the child's end, while the folded part is lofted towards the crotch. The diaper's final form is shown in perspective on a reduced scale in fig. 3. In one form of the invention, as illustrated in fig. 3, the diaper is provided with adhesive loops 26. Each such loop has one end attached to the base fabric 12 and a free end, where the adhesive material is covered by a cover layer. The cover layers are removed to expose the adhesive surface, when the nappy is put on the child, as shown in fig. 3, and the free ends of the adhesive tapes are attached to opposite corners of the nappy.

Suitable fiber structures for the padding 14 for use according to the invention are produced from short cellulose fibers which are obtained by grinding or mincing densified wood pulp fibers or cotton linters. The waddings are originally formed by air-blowing the cellulose fibers on a substrate to a total weight of approx. 67.8 g/cm 2 - 339 g/m 2 , after which the air-blown fibers are subjected to strong compression. The dense, compressed, paper-like layer is produced by wetting a surface of cellulose wadding with a fine water spray, whereupon the moistened wadding is subjected to pressure. The formation of the densified layer on the cellulose wadding is believed to be due to the formation of strong hydrogen bonds between moistened fibers that are in contact with each other, similar to the bonds between the fibers in paper. With an appropriate choice of the amount of applied moisture and with an appropriate choice of the degree of compression, the properties of the compacted layer can be varied as desired. The thickness, density, strength and other properties of

the densified layer depends on the uniformity with which the moisture is applied, the depth of penetration of the moisture and the degree of compression of the fibers. By applying a fine water spray of approx. 0.0015 cnr- z /cm p track surface and a subsequent pressure effect of approx. 2.8 kg/cm, a suitably densified, continuous, paper-like layer 18 is obtained on the surface of the wetted web. The thickened and densified parts 19 can be achieved by subjecting the web to additional pressure, e.g. using an embossing roller, while the web is still damp. The extra applied pressure is preferably several times greater than the pressure applied to form the densified layer 18.

The short fibers used for the production of the padding 14 according to the invention are usually exclusively fibers of wood pulp or cotton linters. However, other cellulose fibers can also be used, as can mixtures of cellulose fibers and other fibers, such as silk, wool, nylon and cellulose acetate. Highly purified kraft paper pulp fibers have proven very satisfactory for most areas of application.

The nappy according to the invention can be assembled in a device as schematically indicated in fig. 5. A roll of short fibers 41 is arranged for feeding a source of short cellulose fibers to a molle 42, from which a fiber strbm is blown onto the belt 43 as a layer 44, weighing between approx. 67.8 and approx. 339 g/m .

The air-blown layer passes under a compacting roll 46, from which it emerges with sufficient firmness for a self-supporting web without the stbtte of the belt 43. The web then passes between a pair of calendering rolls 47 for further compaction and then under the die 48, which deposits a fine moist- heat spray on the upper surface of the track. The wetted web then passes between a further set of calendering rollers 49, which exert strong pressure against it to form a layer 51 on the surface which constitutes the densified layer 18.

The applied amount of moisture can vary between approx. 0.0005 and approx. 0.03 cnr ■z water/cm p of web surface, depending on the desired thickness of the paper-like densified layer. For thinner webs and for very thin, paper-like layers, less water is used and for thicker webs and thicker compressed layers, larger amounts of water are used.

The pressure exerted by the rollers 49 can vary from approx. 0.35 to approx. 7.03 kg/cm . In the case of a common embodiment, it is provided

3 2

the track with approx. 0.0015 cn<r>water per cm track surface and subjected to a pressure of approx. 0.7 - 3.5 kg/cm 2 to achieve a densified, continuous, paper-like layer of uniform thickness on the surface of the web. The amount of moisture is chosen so that the web is still moist after the formation of the layer 51. The web can then pass

between an embossing roller 52 and a counter roller 53 to form the thickened, densified parts 19. The roller 52 has several rib-like projections 54 which run along the circumference at an axial distance from each other. These ribs 54 press against the previously formed layer 51. Because of the remaining moisture in the web and that

octane pressure which extends from the ribs 54, thickened densified parts 19 are formed.

The pressure exerted by the protrusions 54 on the embossing roller also causes depressions or air openings 20 (fig. 2) flush with the densified part 19. As will be seen from fig. 2, the non-densified parts of the densified layer 18 are mixed with the loosely densified padding 14 in a largely flat contact layer 21 and the densified and thickened parts extend over the contact layer 21 into the loosely compressed padding 18, so that the absorbent padding has a three-dimensional reinforcing effect.

When the outer skin and the thickened portions are formed, the absorbent web comes into contact with a web of top layer material 16 and is supported by this, while being cut with the cutting member. 56 to single paddings 14. Polyethylene film is fed to the unit from a roll 58, at the same time lines of adhesive are applied by the applicator 59. As discussed above, the adhesive is applied in parallel lines or drops between the waterproof fabric and the densified layer of the padding (or the top layer in the edge portions of the diaper) . If desired, adhesive can be applied as a continuous layer between the polyethylene film and the padding, but such an arrangement easily leads to excessive stiffness. The adhesive can also be applied in other fabrics, such as dots with a mutual distance or another form of so-called "oy bindings". Tight adhesion between the fabric and the padding is required, so that no point on the polyethylene fabric should be longer than approx. 50.8 mm from the nearest adhesive point. If adhesion is not so tight, the polyethylene fabric can be separated from the compacted layer and create significant areas where uncontrolled large amounts of free, liquid urine can collect.

After the top material and the polyethylene cloth are quickly in contact with opposite surfaces of the absorbent paddings, the unit is subjected to compression by rollers 60 and 61 which form the diaper unit, after which the individual diapers are separated by the cutting member 62.

If desired, the adhesive application member 59 can be dispensed with and adhesion between the polyethylene layer and the fibrous layers can be achieved by heat sealing. using a suitable sealing means in the production line.

As shown in fig. 4, the top layer according to the invention is formed by air-laying two separate transition materials 30 and 30' which are then placed over each other by a jointing means 77

in the form of a roller over which the two substances are placed. After the two lanes have been superimposed, they are processed. with a binder, such as the above-mentioned type.

Halves 30 and 30' of the top layer 16, as discussed above, are preferably produced according to the method described

in the above-mentioned patent application no. The halves are produced first at positions 69 and 69', which are operated in the same way and are designated accordingly. The halves are produced on process paths that are mirror images of each other, so that the formed substances on

the lanes move towards each other. During the description of this method, only one station will be discussed in more detail, but it will be obvious that the discussion also applies to the other station.

The half part 30 is produced by first feeding short cellulose fibers 70 and long textile fibers 71 to a fiber opening and mixing device which has the form of two separate, counter-rotating shredders 74 and 75, as mentioned in the above-mentioned claim. The fibers 70 and 71 are fed to the openings 74 and 75 at the desired speed, so that a web 30 is formed with the desired overall fiber concentration. The rippers 74 and 75 open the fibers from the sources 70 and 71 and the fibers are allowed to float in separate gas drums which are driven against each other and combine to form a gaseous carrier stream. When regulating the guide plate 68, which controls the mutual influence of the air stream from the agitators 74 and 75, to ensétillation above the central line of the agitators, the fibers from each individual stream will cross each other. With this device, the fibers from the ripper 75 tend to be deposited on an upstream portion of the perforated belt 90 and the fibers from the ripper 74 tend to be deposited further downstream on the deposited fibers from the ripper 75. The deposited fibers are densified on the belt 90 by means of the suction box 91, which by means of suction slits draws air through the belt 90 and the deposited fibers at high speed. The half part 30 is distinguished by a main surface 15 near the belt 90 which is enriched with long fibers and a second main surface 13 which is enriched with short fibres. The concentrations of long

and short fibers decrease through the path 30 with increasing distance from the enriched surfaces.

The webs 30 and 30' from the apparatus 69 and 69' are fed towards each other by the conveyors 76, 76' to a joining device 77, where the webs are placed against each other so that the joined web is distinguished by outer surfaces 15 and 15' which are enriched with long fibers .

The combined web is then fed by a transport bridge 78 to a tying station, where they can be tied through using a

binder and a surfactant of the types discussed above from the source 79. The left roller of the conveyor 78 is located directly below and flush with the joining roller 77, as

that the joined web passes between the roller grip for roller 77 and the left roller. The binder is applied to one surface of the web from

source 79 and the bonded web then pass over a suction source 80,<!>which draws the binder through the web and removes any excess binder solution.

The jointed web from which the top layer 16 is to be cut is then used by being fed through the using station 81. The using station is preferably two stages a) a first step which is calculated to promote use throughout the entire depth of the joined web and a diagram indicated by a box 82 and b) a second stage which is intended to apply heat to the outer surface of the web and is illustrated by a series of alternately counter-rotating steam cans 83 and 84.

When the web is used by applying heat to the web surface, a tendency occurs in the binder to migrate towards the heat source when the water carrier evaporates. Surface heating as the only application method can induce so much binder migration that it has adverse consequences for the strength of the internal parts of the composite web. It is therefore preferred that part of the heating is carried out in a way that provides heat in the interior of the web, such as dielectric heating, infrared heating or heating with a strong hot air current that brings heat to the interior of the web by convection.

The relative evaporation proportions achieved in the first and second heating stages depend on the desired properties of the final web. It is desirable that the migration is sufficient for the main fleets, so that the desired strength is achieved

and abrasion resistance on the surface and weakens the middle part of the fabric sufficiently to facilitate delamination of the fabric during tear-off. It is not desirable that the middle part of the fabric weakens so much that partial lamination can take place during normal use of the fabric as a top layer in a nappy.

When the application is complete, the final path is brought

in contact with the absorbent padding material by means of the roller 85.

For some purposes it may be desirable to tie through each half web separately and then tie them together.

For this purpose, tying stations, like the one mentioned, will be placed near the conveyors 30 and 30', which will of course be perforated belts. With this type of device, the mentioned bonding station will be removed and a bonding agent application device can be placed between the tracks 30 and 30' above the joining device 77, for applying bonding agent in the joining surface..

As mentioned above, the second track halves can be of a number of different types, as long as the outer surface (above the surface that is combined with the mass-enriched surface for the first track half) has greater structural integrity than the mass-enriched surface of the transition track.

Although in a preferred embodiment two superimposed transition substances 30 and 30' are used, it should be noted that the transition substances can be different in terms of the nature of the long or short fibers used, the average concentration, the thickness or the degree of enrichment. at each surface.

For some purposes, it may be advantageous to use fibers of different lengths in the halves due to the different stress the opposite sides of the composite web are exposed to and the different demands placed on the sides. The outer surface 15 (which is to come into contact with the infant's skin) can e.g. be rich in long rayon fibres, which provide the desired strength in combination with smoothness. Opposite surfaces located in the interior of the diaper, where smoothness is not so important, can be rich in fibers of water-insoluble polyyinyl alcohol, which, despite being rougher, can be used to provide the desired strength in a more efficient way due to their excellent bonding properties. Alternatively, the fabric can be rich in long polyester fibers on the outer surface to become very smooth and rich in less expensive long fibers on the opposite surface.

The diaper produced with the apparatus according to fig. 5ter is particularly useful for delamination and disposal of excrement, as the individual fibers in the top layer are deposited on the perforated belts 90 and 90' in a roofing manner in the longitudinal direction of the webs. This capping effect, as discussed in U.S. patent document 3,483,051 calls for a top layer that resists tearing in one direction, but can be torn evenly in the direction of roofing.

Once excrement has gotten on the nappy, it is removed from the infant in the usual way, after the adhesive tapes 26 have been removed from each side of the waterproof cloth 12. The nappy is placed on a flat surface or over a toilet and one grabs an edge of the outer part 15 with one hand and the waterproof duct 12 with the other hand. The top layer is then pulled so that the outer part 15 tears off or delaminates along the middle plane due to the poor tensile strength in the inner part which is enriched with short fibres. • When the outer part has started to separate at an edge, you grasp the separated part and the outer part is delaminated from the inner part of the top layer and the other diaper parts. As the outer part 15 is characterized by a greater concentration of long fibers, it has sufficient strength to carry excrement that may be deposited on it

and can be folded up and put in the toilet to be flushed down. The other parts of the nappy, including the waterproof cloth, vat-

the die and the rest of the top layer can be disposed of by placing in a suitable container. In this way, only a small amount of fibrous material has to be flushed down the sewer system and the clogging problems are thereby greatly reduced.

When producing the nappy according to the present invention using the method shown in fig. 5, the belts 90, 90' are moved towards each other and the halves formed on them, f are folded together with the outer surfaces, i.e. the surfaces which are rich in short fibres. If desired, however, the belt 90' can be arranged so that it moves in the same direction as the belt 90, while the fiber sources 70' and 71' are placed in reverse with respect to the belt movement, so that the short fibers are substantially deposited upstream and enriched in the surface in contact with the belt. In this case, the web formed on the belt 90' will have to be taken off the belt and transferred to the top of the web produced on the belt 90, so that the surface rich in short fibers which was originally in contact with the belt 90' comes in contact with the short-fiber-rich upper surface of the web of the belt.90.

The top layer according to the invention can also be produced on a single belt, instead of on two belts, such as the belts 90 and 90'. The fiber sources 70' and 71' can be moved together with the rippers 74', 75' and the guide plate 68' so that they cover the belt 90 at a location downstream of the comparable elements 70, 71, 74, 75 and 68. In this case, a stream rich in long fibers crossed from the snatcher 75 will be deposited first, then a strbm enriched in short fibers crossed from the snatcher 74 will be deposited, then a third strbm enriched in short fibers crossed from the snatcher 74' and finally a fourth strbm, enriched in long fibers crossed over from the ripper 75' are deposited.

In a further method for producing a layered top layer of long - short - long fibres, which can also be delaminated along the short fiber layer for the removal of excrement, a single, perforated belt similar to the belt 90 is used,

on which three separate spoilers are arranged. In this method, the first ripper deposits a layer of long fibers,

other rippers then deposit short fibers further downstream and then a layer of long fibers is deposited on the short fiber layer even further downstream. The layered path is then led to a tie-

intermediate station and a drying station, as mentioned above. Finally, the web enters the diaper production line at the position of the roller 85 in FIG. 5.

When producing the above-mentioned layered web, the strippers can, if desired, be arranged close together, so that they deposit fibers in places close to each other, so that some mutual mixing takes place, and some short fibers are placed in the long fiber-enriched middle part. There should, however, be a decided difference in the concentrations of long and short fibers in the middle part of the web and the opposite outer parts, in the same way as in the case of a web made by joining separate half-web parts. Preferably, the concentration of long fibers in each of the outer 25% of the thickness is at least 1.5 times the concentration of long fibers in the 50% central part and preferably at least twice said concentration.

Further alternative embodiments of the top layers according to the present invention can be used using a single transition material which, in the short fiber-enriched surface, is joined with another half with greater structural stability than the bulk-enriched surface for the transition material. Among alternative second half portions of particular interest are: any of 1) a web of uniformly mixed composition throughout the thickness or one of two different forms of webs of non-uniform composition throughout the thickness, nemsbig 2) a web of an outer surface of short fibers, where the other outer surface consists of long fibers and an intermediate layer is evenly mixed of short and long fibers or 3) a web of two fiber layers, one with short and one with long fibers, where. the layers are blended only in the join.

If variants 2) and 3) are used as the second half which is joined to the mass-enriched surface of the transition fabric to form the top layer, it is the short fiber surface of the second half that is joined to the transition fabric, so that the surface with the long fibers remains an outer surface in the unit.

In addition to the above-mentioned products that can be used as the second half, the invention also includes 4) a thin layer made exclusively of long fibers. The latter embodiment is not normally preferred because it is expensive.

It will be obvious to the person skilled in the art that variations and modifications of the particular embodiments mentioned can be used without leaving the scope of the invention as defined in the claims.

Claims (24)

1. Multi-layer gout diaper, characterized by" , that it comprises: a porous, laminated top layer which is brought into contact with the infant's skin and which comprises two superimposed, tied, non-woven halves, where each half has a . main surface facing outwards in said top layer, the first of said non-woven halves being distinguished by a given average concentration of long fibers and short fibers, where said first half comprises an excess of long fibers in relation to said average concentration in said main surface that faces outwards in the top layer, and has an excess of short fibers in relation to said average concentration in the opposite main surface and has a transition of fiber concentrations between the main rafts, where every second half is connected to the first half on the surface where the concentration of short fibers is in excess of said average concentration, on its main surface facing outwards in the top layer has greater structural integrity than said f orbonded surface of said first half, a very porous, loosely densified cellulose wadding in contact with the outer surface of said second half and a waterproof backing cloth glued to the surface of said wadding on the opposite side of the top layer. 2. Diaper as specified in claim 1, characterized in that the top layer and the waterproof:- base fabric have the same extent, while the padding has smaller dimensions than the top layer and the base fabric and is centrally arranged between them and that the edge parts of the top layer and the base fabric extend beyond the padding, are glued together. 3. Diaper as stated in claim 1, characterized in that said second half comprises a non-woven material which has a concentration of long fibers on its outer surface that is greater than the concentration of long fibers in said connecting surface between the second and first half . 4. Diaper as stated in claim 1, character, characterized by the fact that the second half is distinguished by a given average concentration of long and short fibers, and that the second half has an excess of long fibers in relation to said average concentration in said main surface and has short fibers in excess of said average concentration in the second surface and a transition of fiber concentrations between said surfaces. 5. Diaper as stated in claim 4, characterized in that the long fibers for said first and second halves are mutually different. 6. Diaper as specified in claim 4, characterized in that the long fibers in said first and second half are of the same fiber material. 7. Diaper as stated in claim 4, characterized in that the short fibers in the first and second half are of the same fiber material. 8. Diaper as stated in claim 4, characterized in that the short fibers in the first and second halves are mutually different. 9. Diaper as specified in claim 4, characterized in that the given average concentration of long and short fibers in the first and second half is the same 10. Diaper as stated in claim 4, characterized in that the given average concentration of long and short fibers in the first and second half is different. 11. Diaper as stated in claim 4, characterized in that the concentration of long and. short fibers in the surfaces for the first and second half, where the concentrations of long fibers are in excess in relation to the given average concentration, is the same. 12. Diaper as stated in claim 4, characterized in that the concentration of long and short fibers in the surfaces of the first and second half, where the said concentrations are in excess in relation to the given average concentration for each half, are different. . 13. Diaper as specified in claim 4, characterized in that the first and second halves have the same thickness. 14. Diaper as specified in claim 4, characterized in that the first and second halves have different thicknesses. 15. Multi-layer nappy, characterized in that it comprises: a porous top layer which is brought into contact with the infant's skin, where the top layer comprises an inner part with predominantly short fibers and outer parts with a greater proportion of long fibers than said inner part, a very porous, absorbent padding that has a smaller extent than the top layer, in installations with a surface of the top layer and a waterproof base fabric that has the same extent as the top layer and is adhered to the surface of the wadding none on the opposite side of the top layer and to the edges of the top layer outside the padding. 16. Diaper as stated in claim 15, characterized in that the top layer comprises a given average concentration of long fibers of regenerated cellulose and short fibers of natural cellulose, the top layer having a mixture of fibers over its entire thickness and the mixture varying from a minimal concentration of long fibers in a middle part to a maximum concentration of long fibers in opposite main surfaces of the top layer with transitions of fiber concentrations at an increasing distance from the middle layer towards the outer rafts. 17. Diaper as stated in claim 16, characterized in that the maximum concentrations of long fibers in opposite main surfaces of the top layer are identical concentrations. 18. Diaper as stated in claim 16, characterized in that the top layer is bonded through with a binder which gives the top layer reduced wettability compared to a top layer of unbound fibres. 19. Diaper as stated in claim 16, characterized in that the wadding is a very porous, lSLst densified cellulose wadding. 20. Multi-s gout nappy, characterized in that it comprises a porous top layer which is brought into contact with the infant's skin, and which comprises an inner part of predominantly short fibers and outer parts with a greater proportion of long fibers than said inner part, a highly porous, absorbent padding in contact with one surface of the top layer and a waterproof base fabric glued to the surface of said padding on the opposite side of the top layer. 21. Multi-layer diaper as stated in claim 20, characterized in that the concentration of long fibers in each 25% outer part of the top layer is at least 1.5 times the concentration of long fibers in the middle 50% part. 22. Method for removing excrement comprising the following steps: a diaper with a delaminating top layer is placed on the child, the diaper is removed after excrement has gotten on it, one layer of the top layer is delaminated from another, so that the excrement on an outer part of the top layer separated from the other parts of the nappy, and the excrement and said part of the top layer are thrown away separately from the other parts of the nappy. 23. Method as stated in claim 22, characterized in that the top layer is formed with two non-woven, fibrous halves, that the fibers in each half are arranged in a roofed overlap, the roofed overlap having the opposite orientation in the two halves, and that the delamination is carried out by that the top layer splits along the roofing surface. 24. Method as stated in claim -22, characterized in that the top layer comprises long and short fibers with a predominance of short fibers in the middle part of the top layer and that the delamination is carried out by tearing off the top layer along the middle part with predominantly short fibers.