DE2536925A1 - DISPOSABLE DIAPER - Google Patents

Description

MÜLLER-BORE GKOENING DEUFEL SCHÖN HERTEL

PAT E N TAXWÄLT K

DR. WOLFQANS MOUER-ΒΟΗέ HANS W. GROENINQ, DIPL-ING. DR. PAUl. DEUFEL, DIPL.-CH6M. DR. ALFRED SCHÖN, DIPL.-CHEM. WERNER HERTEL, DIPL.-PHYS,

J / J 10-46

JOHNSON & JOHNSON, New Brunswick, New Jersey, U.S.A.

Disposable diaper

Disposable diapers are versus washable and reusable Diapers are much more comfortable, especially when used outside the home. In the last few years many different disposable diapers have been proposed and some of them have successfully established themselves in the market.

In the usual disposable diaper, at least two fiber layers and at least one impermeable plastic layer are used the outer layer provided to prevent the passage of urine into the '

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8 üCNCHEJ. "80 · SIBBERTSTR. 4 · POB 8607S0 · KABEL ·! 1IO ^- EBOPAT · TEL ·. (089) 471079 · TELEX S-S26

Avoid bedding or outer clothing when the diaper is in use. The reason for using at least two fiber layers lies in having the properties desired for the layer in contact with the child's skin vary widely with the properties desired for that part of the diaper that is not in comes into direct contact with the child's skin. For the layer that comes into contact with the child's skin, which is generally referred to as the topsheet, the desired properties are strength, softness, and freedom over Lint and dust build-up. The layer of the diaper opposite the child's skin at a distance is said to be desirable properties have high absorbency and low cost. The latter properties are found in nonwovens, which are made from loosely compacted short cellulose fibers, such nonwovens having a very low overall strength and have a substantial tendency towards loss of fibers due to scattering.

From the standpoint of cost and ease of manufacture, it would be advantageous to have a single fiber layer which could fulfill the functions of both the top layer resting on the child's skin and the absorbent layer. However, so far, both the function of the topsheet and the function of the absorbent have been satisfactorily implemented Layer not possible with the help of a single fiber layer.

According to the invention, a highly porous, loosely compacted Fleece, which consists at least mainly of short cellulose fibers, with a liquid resin binder on certain local. Parts treated to provide a surface with the desired strength and softness as well as spaced apart To create reinforcements of the loosely compacted fleece. In particular, the invention provides a multi-layer disposable diaper

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with only one fiber layer in front, consisting of (1) a highly porous fleece, which is at least mainly made of composed of short cellulose fibers and (2) a water-impermeable Outer layer, which is adjacent to a surface of the fleece and with this on adhesive areas arranged at a distance is connected, wherein the fibers of the nonwoven are connected to each other by a resin binder, which is the Outer layer covers the opposite surface and extends through the fleece in spaced linear areas extends.

It was found that after solidification of the liquid resin binder on that of the water-impermeable underside Layer opposite surface improves the strength and softness of the fleece surface. It was also found that after solidification of the liquid resin binder, which through the fleece in the spaced linear Areas pushed through or moved through in any other way, the overall strength of the fleece without noticeable Reduction in the absorption capacity is increased.

In a preferred embodiment of the invention, a paper-like, compacted, highly compacted layer or Skin formed on the loosely compacted fleece on the surface adjacent to the water-impermeable sub-layer which is opposite the surface to which the resin binder is applied. The paper-like, compacted, highly compacted cellulose fiber layer or skin forms a whole with the loosely compacted fleece is made by slightly moistening the surface of the fleece on which the skin is to be formed, whereupon the fleece is pressed together between pressure rollers. The paper-like, compacted skin is much higher Density than the rest of the loosely compacted fleece and therefore tends to. Urine from the rest of the loosely compacted

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Fleece away and away from the delivery point to the sides into the skin and to the edges of the fleece to distribute. This is how a limited amount of urine becomes like this as far away from the child's skin as possible. Of the The purpose of the paper-like, compacted skin and the way in which it is produced is detailed in US Pat. No. 3,612,055, Issued October 12, 1971 based on U.S. Patent Application 6,864 filed January 29, 1970.

The fibers of the loosely compacted fleece can completely consist of short ellulose fibers or short cellulose fibers with long textile fibers either uniformly over the entire thickness of the fleece or not uniformly with different ones relative proportions of short fibers and long textile fibers in different parts of the thickness of the fleece can be combined as will be described in detail below.

The invention is illustrated by way of example in the drawing. Show it:

'Fig. 1 is a plan view of a disposable diaper according to FIG Invention;

Figure 2 is an enlarged, broken away cross-sectional view of the preferred embodiment of the disposable diaper according to the invention according to section line 2-2 in FIGS

Fig. 3 is an enlarged fragmentary cross-sectional ¹ view showing another embodiment of the disposable diaper according to the invention is used in a fiber blend and varying their play at different depths or "thicknesses of the nonwoven fabric.

In the figures, the diaper 10 consists of a lower water, impermeable layer 11, which is rectangular in shape, and from a water highly absorbent nonwoven fabric 12, the

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can also be right-angled and extends equally like the impermeable layer. The fleece and the impermeable layer stick to one another at adhesive points 13, which are shown in FIG. are shaded and extend along the side edges of the impermeable layer and the batt.

On the surface of the fleece adjacent to the impermeable layer there is a paper-like compressed surface Layer 14 which is an integral part of the fleece and serves to improve its strength. Also owns the paper-like, compacted skin has a greater suction power against urine excretions than the loosely compacted remainder of the fleece and tends to suck the urine inwards and quickly drain it away into the loosely compacted part of the fleece. On the free surface of the fleece, i.e. the surface that is opposite the paper-like, compacted layer 14, there is a soft skin 16 covered by the surface fibers of the nonwoven fabric and which are connected to each other by a resin binder. A series of grooves 17 are located located in the skin 16, which is the case in that shown in the drawings special embodiment creates a diamond-shaped pattern, how. Fig. 1 shows. Immediately below each groove 17 is a binder wall 18 which extends through the thickness of the fleece extends therethrough. The binder walls are in spaced linear areas that are sufficient lie close to one another in order to enable the strength of the fleece to be strengthened. The binder walls 18 have generally a distance of from 12.7 to about 38.1 mm from one another.

The fleece 12 is made of loosely compacted short cellulose fibers, such as wood pulp fibers or cotton linters or mixtures thereof. In the main part of the fleece volume (the part outside of the compacted layer 14, the Binder-impregnated layer 16 and the binder walls 18), the cellulose fibers in a known manner are mainly

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held together by inter-fiber bonds. In short this is a coherent outside of the paper-like layer 14 and the resin-bound layers 16 and 18 Low density web made from a mass of loosely compacted cellulose fibers, preferably comminuted wood pulp fibers in the form of so-called "fluff" or flaky layer.

The term "short pasers" as used here refers to fibers less than about 6.35 mm (1/4 ") in length as opposed to" long fibers "or" long textile fibers ", which are longer than about 6.35 mm (1/4 ") and generally between about 12.7 and 63.5 mm (1/2 and 2 1/2") long. The former are much less expensive than the latter. The classification of the fibers in length can be made by are carried out according to the Clark Classification procedure, the is described in the test manual of "The Technical Association of Pulp and Paper Industry" (TÄPPI-T233 SU64).

The composite density of the fleece 12 including its compacted layer. 14 and including its resin impregnated Parts 16 and 18 should be above about 0.07 g / cra and preferably between about 0.10 and 0.15 g / cm-. the aforementioned density values are applied to the diaper as it is produced is applied. During storage and treatment, the blank or the thickness of the fleece increases by up to to a certain extent, resulting in decreased densities.

An important aspect of the invention is creation a selectable wettability between different parts of the fiber fleece, such that the amount of liquid dispensed optionally from the resin impregnated layer 16 into the unimpregnated parts of the web and then from the unimpregnated, loosely compacted parts are sucked into the compacted layer within the fleece body.

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The least wettable part of the fleece is the resin-impregnated one Layer 16 as the resin binder tends to be hydrophobic. Meanwhile, the wettability of the resin impregnated Layer with water even desirable. The water repellent property of the layer 16 is not desirable because they can prevent the liquid from penetrating the loosely compacted absorbent part of the fleece behind the layer. just like a tent roof fabric can hold back the ingress of rainwater. For this reason, the resin binder becomes a Wetting agents, such as an anionic surfactant, are added to change its water-repellent properties and reduce. Urine permeates layer 16 after treatment with a resin binder containing a wetting agent one, but the layer remains less wettable than unimpregnated parts of the fleece.

When the diaper is used and the child wearing it excretes urine, the urine leaks through the relatively unwettable ones Binder-impregnated fibers in layer 16 and into the highly wettable fibers in the body of nonwoven 12. The urine then runs into the compacted layer, which is made of the same highly wettable fibers as the body of the fleece 12 is manufactured, but has a better absorbency for the urine due to its higher density. The urine in the compacted Layer spreads over a substantial area in the compacted layer before a substantial amount in the body of the fleece flows back and then spreads over a substantial part in the fleece body before any substantial amounts flow back through the layer 16. Thus, the diaper of the invention keeps the urine from the skin of the Keep child away for as long as possible in the same way as the more complicated and costly diapers that are made up assemble a plurality of fiber components.

The diaper is on its outer surface with respect to the binder and in the spaced linear areas

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also firm and resistant to scattering effects.

The type of binder material used in accordance with the invention is not critical. Binder materials can either thermoplastic or thermosetting, the latter being preferred for diapers that are heat sterilizable meant to be. The binder material is preferred in the form of an aqueous emulsion "or latex.

A binder that has been used successfully is a self crosslinking one Latex of a polyethyl acrylate that contains small amounts of acrylonitrile and a crosslinking monomer, which is commercially available under the trademark 2600X120. The latex binder preferably has a low viscosity less than 5 cp.

Applying the binder composition to the surface of the fleece to the inside of the fleece without penetration of the binder can be done in the form of a fine spray. Preferably the binder is applied in the form of a foam. Due to its nature, the foam wets the entire surface of the fleece without spreading into the interior of the fleece. The foam cells break on the fibrous surface and form after curing, a network of bonded fibers on the entire surface of the fleece.

As stated above, the 'binder composition contains a surfactant to reduce the water-repellent effect on the fibers treated with the binder to avoid. In addition, the surfactant can act as a suds generator when the binder composition to be used in the form of a foam.

Suitable surfactants are the aromatic sulfonates, fatty sulfates, and sulfated oils, sulfated esters, Petroliums.ulfonate, carboxylic acid soaps, quaternary ammonium compounds, amine salts. Like. Specific surfactants 609810/0861

Substances that are suitable for the production of foam are Dodecylbenzenesulfonate, sodium stearylsulfoproprionate, lauryl alcohol sulfonate, Monostearylethylenediamine and trimethylammonium methyl sulfate. A typical surfactant known as has been found suitable is the ionic sulfonated alkyl ester, which is traded under the trademark Trition GR-5. The amount of the surfactant used can be in proportion vary widely from 0.18 to about 5 percent by weight of the binder, although it is preferred for manufacture of the foamed binder to use from about 0.5% to 2 1/2% of the surfactant.

The desired distribution of binder in that in the diaper according to The nonwoven used in the invention is obtained by compressing the web made from the nonwoven between a soft pressure roller (on the dry side of the fleece) and a pressure roller, which is provided with grooves, which the im Corresponding spaced linear areas in which the binder is to be distributed (on the side of the with the binder wetted fleece). The compression in the local ~ Lich fixed linear areas pushes the liquid binder material from the surface of the web into its body and through its entire thickness.

Suitable apparatus for making the web is similar to that disclosed in U.S. Patent 3,444,859 on May 20, 1969 to Frank Kalwaites, except for the fact that the foam is only on one side of the Web is applied and the pressure rollers are of the type described above, one roller being soft and the other is grooved.

In the preferred embodiment, in which the fleece has a compressed, comprises a paper-like layer, the layer is preferably formed on the web from which the nonwoven was made

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the application of the binder is produced.

The backsheet can be placed in precise alignment with the web before the binder and local pressure is applied to force the binder into and through the web. In. this case becomes the binder after exercising come into contact with the underlayer in the print areas from pressure and, after curing, the fleece with the Glue the lower layer together in the locally fixed areas.

In another embodiment, the application of the binder takes place, the local pressure for the penetration and penetration of the binder into the web and curing of the binder takes place before the backsheet is applied to the web. In this In this case, the web and the underlayer are glued together independently of the linear areas of the web that contains the binder. The bonding of the web to the lower layer can be discontinuous by means of lines, points or other Adhesive areas take place, which are distributed over the entire contact area between the web and the backing layer. There can be marginal adhesive areas either completely around the outer edge of the diaper or (as shown in Fig. 1) only be provided on the side edges.

In a further embodiment of the invention, long Textile fibers in conjunction with short cellulose fibers in the loosely compacted fleece are used to provide an additional To achieve strength and a better grip. The textile fibers can be in a length range of about 12.7 mm (1/2 ") up to about 63.5 mm (21/2 ") and can be either uniform or have non-uniform lengths. Suitable textile fibers are those made from rayon, polyester, cellulose acetate, and polyamide etc. '.

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The long textile fibers can be uniform with short fibers mixed using the air laying technique in proportions by weight up to about 25%, as described in U.S. Patent 3,663,348 is described.

Optionally, and as shown in Figure 3, the textile fibers are mixed unevenly, so that the proportion of short and long fibers varies in different depths or thicknesses. With such a non-uniform mixture, it is preferable to have an enriched concentration of textile fibers of surface 26 is opposite to backsheet 21 so that strength and softness on the outer surface are present. The surface 26 has grooves 27 similar to the grooves 17 in Fig. 2 and is made in resin to a shallow depth impregnated near the surface 26.

The remainder of the fleece 22 has a smaller proportion of long fibers and has spaced apart resin impregnated fibers Areas 28 similar to the areas' 18 in FIG. 2. The fleece is glued to the lower layer on areas 23 similar to areas 13 in FIG.

Nonwovens with properties of the nonwoven 22 can be produced using any desired method. According to a preferred Method is a separate supply of short and long fibers to each of two counter-rotating lick rollers (lickerins) used, of which the fibers are taken up in separate gas streams and thrown against each other that they are cross over before the fibers are placed on a perforated belt under the lick rollers.

Web of the type described have a concentration of long fibers that make up the total concentration at surface 26 exceeds, as well as a concentration of short fibers, which the total concentration at the -

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Area, as well as a gradual transition of concentration between these surfaces.

In a further embodiment of the invention that can Fleece 22 instead of a substantially uniform thickness / as shown in the drawing, on its in cross section middle part thicker and thinner at its side edges. A fleece of this type has the advantage that it is more comfortable when it is put on a child, and that the maximum absorption force in that part of the The diaper is concentrated, which is most likely the point of wetting.

Nonwovens with a shaped cross-sectional contour with an elevation in the central part can be used in various ways getting produced. For example, the process of the above-mentioned U.S. Patent 3,444,869 can be carried out by supplying two pulp lanes modified to a hammer mill 12 compared to only a single pulp lane 11 and arranged centrally for this purpose will. The opening under the hammer mill and above the conveyor belt can optionally be diamond-shaped or octagonal, so that the center line of the conveyor 13 lies below the opening for a longer period of time than the sides of the conveyor belt and in this way a greater deposition of fibers is achieved in this area.

In the embodiment of the invention described above the resinous binder only on the surface of the Fleece applied, which is opposite to the surface adjacent to the sub-layer. In certain cases, however, it may be desirable be to apply the resinous binder on both surfaces of the fleece before the fleece with the underlayer in Is brought into contact so that the application of pressure in the local linear areas removes the liquid binder of both

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Surfaces into the interior of the fleece and through it into those local areas. In this embodiment a smaller amount of the binder is required on the surface opposite the underlayer, because the binder is pressed inward from both surfaces. This embodiment can be preferred with binders, which tend to give the outer surface a rough feel when it is on the surface in larger ones Quantities is used.

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Claims (1)

MÜLLER-BOR ^ GROEJiING DEUFEL SCHÖN HERTEL patintaxwAlte. ; 19th August 1975 Johnson & Johnson, New Brunswick, N.J., U.S.A. OR. WOLFQANQ MÖLLER-BORS HANS W. SROENINQ, DIPU-INa DR. PAUU DEUFEL, DIPl CHEM. DR ALPREO SCHÖN, DIPU-CHEM. WERNER HERTSU DIPL.-PHYS. Our files: J / J 10-46 Claims 11 multi-layer disposable diaper characterized by (1) a highly porous fleece (12), consisting of at least mainly short cellulose fibers and (2) a water-impermeable lower layer "(11 y 21), 'that of a surface (14; 23) of the fleece adjacent and connected to this in spaced-apart adhesive areas (18; 28), the fibers of the fleece are connected to one another by an adhesive binder which covers the surface (16) opposite the lower layer (11; 21) and extending through the thickness of the web in spaced linear regions (18; 28). 2. Disposable diaper according to claim 1, characterized in that the fleece (12; 22) has a compressed, paper-like layer (14) which is adjacent to the impermeable layer (11). 3. Disposable diaper according to claim 1, characterized in that the lower layer (11) is glued to the fleece (12) by means of the binder in the spaced linear areas (18). 609810/0881 4. Disposable diaper according to claim 1, characterized in that the lower layer (11) with the fleece (12) by a special Adhesive is glued in the edge areas (13) of contact between the lower layer and the fleece. 5. Disposable diaper according to claim 1, characterized in that the binder contains a surfactant. 6. Disposable diaper according to claim 1, characterized in that the binder is a heat-curable material. 7. Disposable diaper according to claim 1, characterized in that the highly porous fleece (12) consists entirely of short fibers. 8. Disposable diaper according to claim 1, characterized in that the highly porous fleece is composed of short and long fibers is. 9. Disposable diaper according to claim 8, characterized in that the short and long fibers are uniformly mixed. 10. Disposable diaper according to claim 8, characterized in that the fleece has different proportions of short and long fibers in different parts of the thickness of the same with a maximum Concentration of the long fibers on the surface opposite the sub-layer. 11. A method of making a disposable diaper, characterized by applying a liquid resin binder to a surface of a highly porous fleece made of short cellulose fibers, by compressing the web in spaced linear areas to move the binder through the Thickness of the fleece in this area, through solidification of the binder and through gluing of the first-mentioned surface opposite surface of the fleece with a water-impermeable underlayer. 609810/0861 12. The method according to claim 11, characterized in that the liquid: resin binder is used as a foam. 13. The method according to claim 11, characterized in that the liquid resin binder is an aqueous latex made of a thermosetting material. 14. The method according to claim 11, characterized in that the liquid resin binder contains a surfactant. 60 9 810/0861