Covering structure for absorbent hygienic-sanitary products, and an absorbent product having such a covering

COVERAGE STRUCTURE FOR HYGIENIC-SANITARY PRODUCTS

ABSORBENT AND ABSORBENT PRODUCT THAT HAS SUCH COVERAGE

Utility Model Field

The present utility model generally relates to absorbent sanitary products such as women's sanitary towels, baby bibs and diapers, incontinent adult pads, surgery locks and tampons, medication tampons, bandages , absorbent plasters, etc.

Such products, which are designed to absorb and retain body fluids such as menstrual fluids, urine, blood and exudation, are used every day as disposable products, ie products that are intended to be thrown away. after use. Due to their practical and hygienic nature, they are increasingly used and have practically replaced all devices that can be reused after a wash, such as bandages, swaddles, etc., of conventional type.

The absorbent core of the product is a pad (padding or padding) of porous material which can absorb and retain a large amount of fluid. The core may be divided into an upper face to face the user's body and a lower face /

^Κ--intended to be directed towards the external environment.

The absorbent core is coated with a cover sheet or cover structure which generally has different characteristics on the upper face and the lower face.

The foil or cover structure applied to the upper face (topsheet) must in fact be permeable to body fluids in order to facilitate its flow into the absorbent core. On the other hand, the sheet or cover structure applied to the underside (lining sheet) must be impermeable to fluids in order to protect the wearer's clothes, preventing them from getting wet.

The formation of an upper cover sheet or structure with optimum use characteristics is one of the main problems to be solved in improving the absorbent product qualities.

The top covering sheet or structure has in fact to perform various functions, often of an antagonistic nature.

In particular, it should allow easy penetration of body fluids into the absorbent pad or core while isolating the wearer's skin from the absorbed fluids to prevent maceration of the skin itself.

<img file="PT8522U_D0001.tif" />

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It is very important then that the topsheet or structure gives the user a feeling of surface dryness even when the product core has absorbed a considerable amount of fluid.

In the past, it has been proposed to use nonwoven (i.e. non-woven, according to current English minology) sheets made of non-absorbent or hydrophobic fibers, such as synthetic fibers, for the upper cover structure. . Thus, it is possible to prevent the wearer's skin from being exposed to prolonged contact with a damp cover, as is the case when the absorbent product is covered with a woven or non-woven textile fabric made of absorbent or hydrophilic fibers such as cotton, rayon, etc.

It has also been proposed to use for the upper cover an absorbent product consisting of a film of plastic material (itself impervious to body liquids) made permeable through perforations of varying shapes and sizes, with different distributions and densities depending on the requirements required. for use.

However, such known cover structures have disadvantageous side effects, such as, in the case of nonwoven synthetic fiber-based textiles, a residual tendency to retain and absorb body fluids on the surface of the absorbent product and, in the case of non-woven film. perforated plastics, an unpleasant tactile feeling given to the user by the non-textile material.

Object of the Utility Model The object of the present utility model is to provide a cover structure for sanitary and sanitary products, particularly for use as the top face cover structure (as defined above) of such products, having the following characteristics:

an overall look and feel to the user substantially equal to the look and feel provided by a textile product;

the ability to facilitate the penetration of body fluids within the absorbent core of the product, particularly in relation to menstrual fluids;

a tendency of the upper surface of the product to remain substantially clean itself, even when the product core has already absorbed a certain amount of fluid;

the possibility of preventing fluid already absorbed by the core from flowing back out of the product back into the user's body; and

an ability to isolate moisture contained in the absorbent core.

Utility Model Summary

According to the present utility model, the object specified above is achieved with a cover structure for sanitary absorbent products, characterized in that it is perforated and comprises:

an upwardly facing top layer of the absorbent product comprising a textile fabric of fibers of nonwoven hydrophobic material;

- an intermediate layer consisting of a film of hydrophobic material; and

a lower layer facing inwardly of the absorbent product comprising a textile fabric of nonwoven hydrophobic fiber material.

The present utility model also provides an absorbent sanitary product with an absorbent core having an upper face and a lower face, characterized in that it includes a cover structure of the above-specified type applied in direct contact with the upper face.

Description of the Utility Model The present utility model will now be described, by way of example only and not limitation, with reference to the accompanying drawings, whose figures represent

<img file="PT8522U_D0002.tif" />

Fig. 1 schematically an absorbent sanitary product according to the present utility model;

<td colspan="2"></td><td>THE</td><td>fig ·</td><td> 2,</td><td colspan="2">a cut made</td><td colspan="2">by line (II-II)</td><td>gives</td>

<td>fig ·</td><td> 1;</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td>THE</td><td>fig ·</td><td> 3,</td><td>one</td><td>cut made</td><td>through the</td><td>line III-III</td><td>gives</td>

<td>fig ·</td><td> 1;</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td>THE</td><td>fig ·</td><td> 4,</td><td>an</td><td colspan="2">sectional view,</td><td colspan="2">on a larger scale</td>

1 of one of the absorbent product elements shown in FIGS. 1 to 3;

Fig. 5 is a view substantially analogous to the view of FIG. 4 illustrating a possible variant of the present utility model; and

Fig. 6 schematically the manufacturing process of the elements illustrated in FIGS. 4 and 5.

The following detailed description is given with specific reference to a sanitary sanitary product for a ladies sanitary napkin.

However, the present utility model is not limited to this possible use and can be advantageously applied to all absorbent sanitary products and in particular to baby bibs and diapers for incontinent adults, for surgical locks and medication tampons, bandages, absorbent plasters, etc.

In fig. 1 to 3 an absorbent product has the global reference (1) and consists, as indicated above, of a ladies sanitary napkin.

The product (1) consists essentially of an elongate absorbent pad or core (2) in which an upper face (3) (intended to face the wearer's body) and a lower face ( 4) (intended to face outwards).

The absorbent pad or core (2) is completely surrounded by a sheet or cover structure (5), made of a strip that is closed forming a tube, whose opposite edges are overlapped and joined together by strips of adhesive material (6). or by heat sealing or ultrasonic hard welding.

The cover structure (5) is then also closed at both ends of the pad (2) by heat sealing or ultrasonic welding at the two extreme zones (7), which are generally arcuate and open side to side. . However, this operation can also advantageously be done by glues.

Also interposed between the cushion (2) and the cover structure (5), corresponding to the underside (4) and sides of the cushion, a sheet (8) of impermeable material to prevent absorbed fluids. by the cushion (2) can leave the cushion itself and dirty the wearer's clothes.

Of course, it is also possible to make the outer cover of the cushion (2) using two different cover structures, of which the one to be applied to the upper face (3) is perforated and has the stratified structure which will be described in more detail. further on, while the structure intended to be applied to the underside (4) is generally an impermeable structure.

The following description is therefore given with specific reference to the upper cover structure of the product (1), that is, the cover structure intended to be applied to the upper surface (3) of the pad (2) in direct contact with the own cushion (2).

The cushion (2) is usually - in a known manner - made of pneumatically treated wood cellulose fibers to form a very porous material, generally referred to as air felt or fluff.

This material is preferred because it is inexpensive and has very good hydrophilic characteristics as well as good absorption of liquids.

The weight of the absorbent pad 2 may vary widely depending on the type of absorbent product (sanitary napkin, disposable diapers, etc.) and, by way of example, may vary between 200 and 1200 g / m2. The so-called bulkiness of the pillow (2) may be chosen from 7 cm 3 / g to 25 cm 3 / g.

Of course, lower voluminosities lead to higher rates of fluid diffusion in the pad due to the lower mean value of the capillary tubes forming between cellulosic fibers, while higher voluminosities lead to overall fluid absorption. bigger.

Even the nature and manufacturing process of cellulose fibers influences fluid absorption and retention processes in the pad. Particularly preferred are cellulosic fibers from coniferous woods that are chemically purified, preferably without the addition of substances which may reduce the bonds between the fibers.

Best results were obtained by dry defibration of chemical cellulose sheets sold under the tradename NBF FLUFF by Weyerhaeuser Corporation of Tacoma (USA).

As best seen in FIGS. 4 and 5, the cover structure (5) [which is applied in direct contact with the upper face of the cushion (2)] is drilled, provided with holes (9) disposed in an ordered or pseudorandom array, and generally a stratified configuration.

This configuration can be seen to consist essentially of three layers, that is:

- an upper or outer layer (10) intended to face outwardly of the absorbent product (1) consisting of

It is made of a textile fabric of fibers of nonwoven hydrophobic material;

an intermediate layer or core (11) consisting of a film of hydrophobic material; and

a lower or inner layer (12) intended to face the absorbent pad (2), consisting, like the upper layer (10), of nonwoven textile fabric of fibers of hydrophobic material.

For the upper layer 10, which is intended to come into contact with the user's skin, it is preferred to use a nonwoven polypropylene fiber textile. This choice is preferred for the safety, non-absorbency and low cost characteristics of the fibers themselves.

The intermediate layer 11 is preferably comprised of a soft white low density polyethylene film. It is also possible to use films of other types for the core layer, such as, for example, polypropylene films.

It is also considered preferable to use a nonwoven textile made of polypropylene fibers for layer (12) which comes into direct contact with the absorbent pad (2). Of course, synthetic fibers may be used for the upper and lower layers, for example CHISSO ES two-component fibers manufactured by the Japanese company CHISSO.

The total thickness of the cover structure, indicated by (S), may vary within the range of 200 to 700 micrometers. This choice provides a good compromise between the requirement to obtain good fluid penetration in the pad (2) and the requirement to prevent subsequent reflux of fluids from the absorbent product (1). In addition, this choice provides good insulation of the moisture contained in the absorbent pad during use.

Particularly good results have been obtained with a thickness (S) of between 250 and 550 micrometers. The currently preferred choice is a value of (S) substantially 350 micrometers.

basic overall weight of the cover structure (5) when using a non-woven polypropylene fiber textile for the outer layers (10) and (12) and a soft, white, low-density polyethylene film for core layer 11 may range from 20 to 60 g / m2.

More particularly, the basic weight of the layers

<td colspan="2">individual may</td><td colspan="3">vary within</td><td colspan="2">following limits:</td>

<td> - 7</td><td>The</td><td> 40</td><td>g / m2,</td><td>for</td><td>The</td><td>upper layer (10);</td>

<td> - 5</td><td>The</td><td> 30</td><td>g / m2,</td><td>for</td><td>The</td><td>intermediate layer (11);</td>

<td> - 7</td><td>The</td><td> 30</td><td>g / m2,</td><td>for</td><td>The</td><td>bottom layer (12).</td>

At present, the particularly preferred overall basis weight is 40 g / m2, with values ​​of 20 g / m2 for the top layer (10), 10 g / m2 for the core layer (11) and 10 g / m2 for the top layer. bottom layer (12).

/ 11

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As indicated above, the holes (9) in the cover structure (5) may be arranged in a regular square, rectangular, rhombic or hexagonal array, or in a pseudorandom array.

The embodiment illustrated in fig. 4 refers to square holes 9 whose sides have a length L in FIG. 4 of about 0.7 mm. However, the embodiment of fig. 5, refers to circular or slightly elliptical holes.

The distance between adjacent holes, corresponding to the distance (T) separating the middle planes of the walls separating two adjacent holes, is about 1.4 mm.

As a whole the open area of ​​the cover structure, (5) [i.e., the ratio between the surface occupied by the holes (9) and the total surface of the structure] is about 25%.

Of course, it is possible to use hole layouts with a different square configuration.

The choice of a square array of square holes (fig. 4) or circular or slightly elliptical holes (fig. 5) is however considered to be preferable at present, as this choice gives the cover structure (5), and in particular to the outwardly facing surface of the product (1), an appearance substantially the same as that of an ordinary woven textile, which is particularly pleasant to the wearer.

The hole diameters (9) may differ from those indicated above.

In general, for application to sanitary napkins for ladies, the diameters of the holes (9) [it is to be understood that this term means the maximum hole size in the general plane of the extension of the structure (5)] are chosen from the range of 0.4 and 1.5 mm, preferably by choosing values ​​within the range of 0.6 to 0.9 mm.

The open area of ​​the roof structure may vary depending on the usage requirements and strength characteristics of the materials used. Typically it is within the range of 10Z to 50% with reference to the total surface of the roof structure.

In general, as will be seen later, the holes 9 are made by puncturing from the face of the cover structure which is intended to face out of the product. Thus, the face (13a) of the upper layer (10) of each wall or partition (13) of the structure (5) between two adjacent holes (9) facing outwardly of the product can generally be bent with the convexity facing outside the frame 5 as clearly seen in FIGS. 4 and 5.

This curved configuration facilitates the penetration of fluids into the holes (9) and thus their absorption by the absorbent pad fibers (2). Thus, it tends to slide the fluids into the holes (9), preventing them from parking on the outer surface of the cover structure (5). This allows for a cleaner cover structure that does not tend to absorb body fluids.

The formation of holes 9 by punching or punching also has the effect of producing some compaction of the fibers of the upper layer 10 which are closer to the outer surface of the layer itself.

In other words, in each of the partition or partition walls (13), the upper layer (10) includes a surface portion (10a) of more compact fibers and an inner portion (10b) of looser fibers.

The higher relative density of the outer portion 10a means that this portion is to some extent impervious to body fluids, or at least tends to absorb body fluids to a lesser extent.

The softer and more absorbent inner portion 10b is thus completely protected from the outside by the more compacted portion 10a on one side and the hydrophobic film 11 on the other side.

During use, the absorption of body fluids by the inner portion 10b is extremely low. It has also been noted that the density gradient of the material between the surface portion 10a and the interior portion 10b means that the latter practically absorbs no fluid from the outside.

The outermost part of the cover structure (5) according to the present invention, that is, the part intended to be in direct contact with the wearer's skin, thus has a reduced tendency to absorb body fluids. This outer surface is therefore virtually dry during use, which contributes to the user having a pleasant feeling of cleanliness.

The intermediate core layer (11), which is comprised of a film of impermeable material, also acts as a barrier that prevents the fluids absorbed by the pad (2) from migrating again outside the product (1).

The most obvious difference between the cover structure illustrated in fig. 4 and the variant of fig. 5 is that the outer surface of layer 10 is more curved in the embodiment of FIG. 5, which allows better penetration of body fluids into the absorbent pad (2). Another difference already noted is that the holes 9 are circular or slightly oblique rather than square with a diameter (L ') of the order of 0.8 mm. The upper layer (10) is also thicker than that of the lower layer (12). Partial covering action of the lower region of each hole (9) by the intermediate layer (11) is also evident. This covering is caused by the edges (15) of the film (11) that are formed during the drilling of the holes.

<img file="PT8522U_D0004.tif" />

(9) perforated and which may even project to the cushion (2) beyond the surface of the cover structure.

In each case (fig. 4 and fig. 5), the lower layer 12 has the function of embodying the cover structure 5, contributing to the isolation of the wearer from the fluids and moisture absorbed by the pad (2). .

The surface of the bottom layer 12 facing outwardly of the pad 2, the surface indicated with 13b, is substantially flat.

This contributes to keeping the structure (5) in firm contact with the absorbent pad (2), particularly when the layers or glue points are applied between the surface (13b) and the outer surface of the pad (2).

The close adhesion of the outer cover (5) to the absorbent pad (2) plays a considerable role in ensuring that fluids flowing to the side of the surface (5) are not, as it were, trapped within the holes (9). ) but dragged into the cushion (2).

This drag action of the fluids must be guaranteed not only immediately when the product is put on but also after prolonged use for a certain period of time, ie after the product (1) has already been subjected to normal stresses. use.

It is therefore very important to get a contact

<img file="PT8522U_D0005.tif" />

substantially continuous and effective between the cover structure (5) and the pad (2). Taking into account the nature of the cushion (2), which is made up of separate and unconnected fibers, it is extremely advantageous to be able to provide flat surfaces, such as surfaces (13b), which allow the use of adhesives to improve adhesion. connection between the cover structure (5) and the absorbent pad (2). For this purpose, aqueous solution adhesives or heat fusible adhesives may be used, for example, lightly applied by known spreading processes.

More particularly, where glues in aqueous solution or aqueous suspension are used, the barrier function of the intermediate film (11) reduces the risk of the glue penetrating towards the outer surface of the structure (5) and then coming into contact with the glue. wearer's skin.

In the case of aqueous emulsion cold adhesives or heat fusible adhesives, it is in fact customary to use rubber based adhesives which maintain their adhesion and pressure adhesion characteristics for a long time.

Fig. 6 schematically depicts a device that can be used for the manufacture of a cover structure as illustrated in FIGS. 4 and 5.

The device, with global reference (20), comprises two cards (21) and (22), each of which continuously provides a web of polypropylene fibers.

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The mantle provided by the card 21 is for forming the upper layer 10 and therefore has the same reference in FIG. 6

Similarly, the blanket provided by card (22) is indicated by (12) as it is intended to form the lower layer (12) of the cover structure (5).

A low density, preferably milk white, polyethylene film intended to form the intermediate layer (11) is continuously unrolled from a spool, generally indicated by (23).

The mats (10) and (12) and the film (11) are provided for two counter-rotating cylinders (24), in such an arrangement that the film (11) interposes between the mats (10) and (12). .

Cylinders (24), whose peripheral speeds are adjusted to match the feed speed of the mats (10) and (12) and the film (11), compress the mats (10) and (12) against opposite faces of the film (11), joining the mats (10) and (12) and the film (11) in a single strand (5 ') with a stratified structure.

This is in the presence of a functional device generally used in the manufacture of stratified structures, such as, for example, cover sheets, cushion-type paving, etc. Naturally, in the present case, the pressure exerted by the cylinders 24 must be adjusted to prevent excessive crushing of the materials used.

The film (11) may then be attached to the mats (10) and (12) by means of an adhesive or by localized melting of the film (11), achieved by heating the rollers (24), etc.

The stratified strip 5 'is then directed to a drilling station of general designation 25 consisting of two overlapping cylinders 26 and 27 rotating in opposite directions with parallel axes.

The lower cylinder 27, which functions as a rotating support of the strip 5 ', has a generally smooth surface.

However, the upper cylinder (26) has teeth or protrusions arranged in a pattern corresponding to that of the set of holes (9) to be obtained in the strip (5).

The teeth or protrusions of the cylinder (26) penetrate the strip (5), giving the strip itself the perforated structure of the cover (5), as well as its shape and strength.

The operating principle of the unit (25) must be regarded as generally known. The use of this solution for the manufacture of the perforated structure (5) from the stratified strip (5 ') has the dual advantage of generally curving the face (13a) of the walls of the partitions (13) separating the walls. holes (9) and intended

<img file="PT8522U_D0006.tif" />

facing away from the product, while also favoring the formation of the more compact zone (10a).