manufacturing such tampon

The present invention refers to a tampon, in particular to a hygienic tampon. In accordance to the International patent classification, such inventions belong to human necessities, namely to hygiene, and in particular to catamenial tampons and accessories therefor.

It is an object of the invention, how to improve the sliding ability on the outer surface of a tampon equipped with ribs and grooves, by which such tampon would however still have to be manufactured of the same raw materials, by using the same manufacturing equipment and by performing essentially the same processing steps like in manufacturing any other modern and seriously commercialized tampon, and by which the other essential properties of such tampon should not be hindered, which in particular refers to maintaining its absorbency for liquids including a specific absorption capacity and the rate of absorption, preventing of leakage as well as maintaining of buckling strength and stability of dimensions of such tampon. A tampon, which is described in EP 0 422 660, consists of a nonwoven fibrous blank, which is obtained by means of winding of a nonwoven fibrous strip around its transversal axis, by which appropriately cylindrical blank is formed, which is then radially compressed by means of corresponding jaws e.g. in a corresponding press according to DE 19 825 877 into a shape of a tampon. Such tampon is approximately cylindrical, although radially inwards directed grooves are pressed on its surface, which extend in the axial direction i.e. parallel to said longitudinal axis of the tampon. Such tampons are generally known to those skilled in the art as so called "digital tampons". A rib is available between each two neighboring grooves, wherein the diameter of such tampon is determined by the circumferential portions of said ribs, while the bottom portions of said groove determine a highly compressed core on the tampon. In a subsequent step of manufacturing such tampon is slightly compressed in the area of said ribs, by means of which then the lateral portions of ribs become convex, upon which the lateral flanks of each neighboring ribs shall contact each other, so that closely to said core a tubular and parallel with the longitudinal axis of the tampon extending cavity is formed between each pair of ribs. Such concept should lead to certain advantages, e.g. to increasing of buckling strength and in particular to increasing of specific absorption capacity and the absorption rate in the longitudinal direction of the tampon. Said buckling strength is important by inserting the tampon and has some influence on perception of consumers in view of reliability. In addition to said buckling strength it is however also very important by inserting the tampon that the outer surface thereof, which is during the use of such tampon in contact with mucosa, shall be as smooth as possible, so that the coefficient of friction on said outer surface should be the lowest possible. As proposed in EO 1 014 910, a smooth outer surface may be achieved during compression of a fibrous material into a shape of tampon, by which the pressure needs to be essentially higher than in compression of previously known tampons. Thanks to such extremely high pressure, stability of the shape of the tampon should be essentially improved, and at the same time the outer surface of the tampon should also be smooth. In accordance with said source the tampons may be manufactured, which are approximately cylindrical and are moreover without any ribs and groves on the outer surface, so that the specific absorption capacity of such tampons i.e. absorptiveness per quantity of fibers is then essentially lower than by tampons with ribs and grooves on the outer surface.

As described in US 4,981,884, stability of dimensions of a tampon may also be achieved by heating of pressing jaws, by means of which the fibrous material is formed into each tampon. Also in such case, at least approximately cylindrical tampon without any ribs and grooves on its outer surface may be manufactured, and the specific absorption capacity is then quite similar like by a previously mentioned tampon according to EP 1 014 910.

A further possible approach in view of providing a smooth outer surface of a tampon is described in WO 01/01910 Al, wherein the outer surface of such tampon is surrounded with a perforated covering layer on the basis of artificial fibers, which are as such unable to absorb the liquid, but the sliding ability is herewith be essentially improved. Due to the fact that said covering layer is perforated, the liquid is allowed to be transferred towards the interior of the tampon, where the liquid is then absorbed by appropriately absorptive natural fibers. The presence of said covering layer in a classic mass production process makes such process much more complicated, in particular when transporting throughout the machine is taken into consideration, and EP 1 244 402 has proposed the use of a non-ionic surfactant. As a consequence of such improving the sliding ability, the specific absorption capacity and in particular the absorption rate are then essentially reduced.

A still further approach in view of improvement of the sliding ability is proposed in EP 1 035 819 or US2003/0105444 Al, where during the step of winding natural fibrous material by forming an essentially cylindrical blank, of which then by means of radially compression by jaws a tampon is formed, a previously smoothed covering layer is attached onto said layer of natural fibers and is upon that wound together with said layer of natural fibers into said blank. A tampon is then formed by means of radial compression, which is along its complete circumference surrounded with a covering layer, wherein such tampon like e.g. a tampon according to EP 0 422 660 also comprises a plurality of ribs and grooves on its outer surface, so that in addition to satisfactory stability of the shape and buckling strength also acceptable absorption capacity and absorption rate are then achieved. Said smoothing of the covering layer having a two-component fibrous structure is performed by means of calendaring between appropriately heated rollers, by which the artificial fibers are plasticized and in such plasticized state also essentially, by which the liquid permeability of such smoothed covering layer is reduced in such extend that the covering layer becomes practically hydrophobic. As previously described, such smoothed covering layer is present along the complete circumference of such manufactured tampon, namely both on outer surfaces of the ribs, which during the use of the tampon stay in contact with mucosa, and also in the area of grooves between each pair of ribs. Also the practical experience shows that thanks to such performed smoothing of the covering layer, the sliding ability on the outer surface of the tampon is definitively improved, but at the same time the process of absorption of the liquid into the tampon is also essentially changed due the presence of such at least partially hydrophobic covering layer in the area of grooves between the ribs. And because said smoothed and hydrophobic covering layer is also present between the ribs, the progress of the liquid in the axial direction of the tampon is much more intensive than the progress of the liquid in the radial direction towards the absorbent core, which should actually able to absorb an essential quantity of the liquid. It is therefore obvious that despite to expected storing the liquid such tampon shows tendency of transferring the liquid in its axial direction, which unavoidable leads to flowing out the liquid (which is known to those skilled in the art as the "leakage") on the opposite side of the tampon, which is absolutely undesired. And although the sliding ability would be still further improved e.g. by using a special fibrous structure of the covering layer according to EP 1 988 202 Al, by maintaining such covering layer around the complete circumferential area of the tampon and without essentially amending the concept of the tampon as such, the problem of preventing the leakage due to undesired process of absorption in view of tendency to transfer the liquid in axial instead of in radial direction would still remain completely unresolved.

The present invention refers to a hygienic tampon having improved sliding ability on its outer surface, wherein such tampon comprising an absorbent core consisting of absorbent natural or artificial fibers, as well as a of a continuous covering layer, which contains thermoplastic fibers which are approximately uniformly distributed across the surface thereof and by which said core is surrounded around its complete circumferential area, wherein the first end portion of such tampon is optionally narrowed and formed with a slightly rounded tip, while the second end portion thereof is equipped with a string intended for easier removing the tampon after the use, and wherein such tampon is due to at least approximately radial compression on its surface provided with appropriate number i.e. at least two to ten radial grooves, which extend at least approximately parallel to each other in the longitudinal direction of the tampon or are inclined at certain angle with respect to said longitudinal direction and which are equidistantly apart from each other distributed in the circumferential direction of the tampon, so that between each two neighboring grooves there is a rib having a slightly rounded convex outer surface, so that such outer surfaces of all ribs together form at least approximately cylindrical outer surface of the tampon.

In accordance with the invention and in order to assure improved sliding ability on its outer surface, such tampon is smoothed exclusively in the area of convex outer surfaces of each available ribs, by which on said outer surface of the tampon the friction coefficient is reduced and the sliding ability is correspondingly improved.

Consequently said covering layer of the tampon consists either of two-component fibers, where at least the outer component thereof consists of a thermoplastic material, or of a mixture of fibers, where at least a portion of these fibers represent thermoplastic fibers, and is at least in the area of convex outer surfaces of the ribs smoothed by heating said thermoplastic fibers or a thermoplastic component of said fibers up to the temperature of plasticizing of the thermoplastic material of fibers by simultaneously establishing a smooth uniform compression towards the outer surface of the covering layer in the radial direction regarding the tampon. In accordance with one of possible embodiments, said covering layer consists of two-component fibers, which are formed with a core on the basis of polyester (PES) and with a wrapper on the basis of high density polyethylene (PE) or optionally of a mixture of fibers of the same content, where the ratio PE : PES = 34% : 66% up to PE : PES = 50% : 50%, and where the specific surface density of such two-component fibers is 12 to 20 g/m 2 and preferably around 16 g/m 2 , wherein said covering layer is smoothed in the area of convex outer surfaces of the ribs by means of plasticizing said polyethylene (PE) component of fibers at the temperature within the range between 120°C and 180°C, preferably between 122°C and 148°C, by simultaneously exposing such plasticized fibers on the outer surface of the covering layer (2) to a smooth uniform compression acting inwardly in the radial direction regarding the tampon.

A further object of the invention is a process of manufacturing a hygienic tampon having improved sliding ability on its outer surface, wherein such process comprising steps of

- preparing of appropriately thick layer of a non-woven fabric on the basis of natural or synthetic fibers for the purposes of forming an absorbent core;

- preparing of appropriately thick layer of a non-woven fabric for the purposes of forming a covering layer of the tampon, in which the content of fibers is determined in such manner that fibers are either two-component fibers in which one component consists of a thermoplastic material, or at least a portion of fibers are thermoplastic fibers;

- cutting said fabric into a strip intended to form said absorbent core and having a width adjusted to the length of the tampon and the length adjusted to each desired diameter of the tampon; - cutting said fabric into a strip intended to form said covering layer and having a width adjusted to the length of the tampon and the length adjusted to each desired diameter or circumference of the tampon;

- assembling said strip intended to form the absorbent core and said strip intended to form the covering layer by means of overlapping said strip of the covering layer over a pre-determined area of the strip of the core, wherein this step also includes appropriate placing a string, which is intended for removing the tampon after the use thereof;

- winding said strip intended to form a core around the transversal axis of the strip, by which at least approximately cylindrical blank is formed, which is across the complete circumferential area or at least across the majority of said circumferential area surrounded by continuously extending strip intended to form the covering layer, wherein the diameter of such blank is adjusted by taking into consideration each expected diameter of the tampon, and wherein the length of such blank is adjusted with respect to each expected length of the tampon;

- introducing said blank into appropriate press in order to perform a radial compression thereof by means of appropriate jaws and to obtain at least cylindrical tampon having a narrowed and slightly rounded tip on its one end portion and a desired number, which corresponds to the number of jaws, of radial grooves, which are pressed in the circumferential surface of the tampon and extend at least essentially parallel to each other either in the longitudinal direction of the tampon or are inclined with respect to said longitudinal direction, and which are equidistantly spaced from each other in the circumferential direction of the tampon, so that a rib is formed between each two neighboring grooves, which is equipped with a slightly rounded convex outer surface, so that convex surfaces of all ribs form an essentially cylindrical outer surface of the tampon; and - smoothing said outer surface of the tampon exclusively in the area of said convex outer surfaces of the ribs by means of pushing such formed tampon throughout a conical passage of a die in the axial direction thereof, by which the tampon is exposed to a slight compression acting radially inwards.

In accordance with the proposed invention, said step of smoothing the outer surface of the tampon is performed as smoothing of the outer surface of the covering layer consisting either at least partially of thermoplastic fibers, which are uniformly distributed across the surface area thereof, or of two-component fibers comprising outwardly located component on the basis of thermoplastic material, wherein exclusively in the area of said convex outer surfaces of the ribs on the tampon said thermoplastic fibers or a thermoplastic component of fibers are/is heated on the temperature of plasticizing of said thermoplastic fibers or said thermoplastic component of fibers, upon which such plasticized fibers are exposed to a slight and uniform compression, which is acting radially inwards with respect to the tampon.

In a preferred mode of the process of the invention, the covering layer consisting of fibers having a core of polyester (PES) wrapped by high density polyethylene (PE) component, wherein the ratio PE : PES = 34% : 66% up to PE : PES = 50% : 50%, or optionally of two-component mixture of fibers of the same content of said materials, and wherein the surface density of such two-component fabric is

12 to 20 g/m 2 and preferably around 16 g/m 2 , is smoothed in the area of convex outer surfaces of the ribs by means of heating said thermoplastic fibers up to the temperature of plasticizing said polyethylene (PE) fibers or a polyethylene (PE) component of said fibers by simultaneously exposing such plasticized fibers on the outer surface of the covering layer to a slight and uniform compression, which is acting inwardly in the radial direction regarding the tampon. For the purposes of said plasticizing of the polyethylene (PE) component, said fibers are heated up to the temperature within the range between 120°C and 180°C, preferably between 122°C and 148°C, upon which such plasticized fibers are exposed to a slight uniform compression, which is acting inwardly in the radial direction regarding the tampon.

The invention will be described on the basis of an embodiment, which is shown in the attached drawings, where

Fig. 1 is a schematically shown cross-section of a tampon according to the invention;

Fig. 2 schematically indicates the initial phase of manufacturing the tampon according to Fig. 1, namely winding the fibrous fabric together with a covering layer placed on, by which the blank is formed;

Fig. 3 illustrates the final stage of manufacturing the tampon according to Fig. 1 , namely compression of the blank according to Fig. 2 in the radial direction, which is then followed by smoothing of outer surfaces of ribs on such obtained tampon.

A tampon according to the invention (Fig. 1), which may either be a digital tampon adapted for inserting by means of fingers, or an applicator tampon adapted for inserting by means of appropriate requisite like a tampon applicator known to those skilled in the art, normally consist of an absorbent core 1 , which is along its complete circumference surrounded with a covering layer 2, which should improve the sliding ability of the outer surface of the tampon. Said absorbent core 1 of the tampon consists of a non-woven fabric on the basis of correspondingly absorbent natural and/or synthetic fibers, wherein e.g. cotton fibers can be used as natural fibers and e.g. rayon can be used as synthetic fibers. Also said covering layer 2 is generally formed of appropriately thick layer of non- woven fibers, which are however determined in such a manner that liquid is allowed to pass through said layer of fibers and that in particular the best possible sliding ability is achieved, namely the lowest possible coefficient of friction on the outer surface of the tampon.

The invention provides that the covering layer 2 consists of thermoplastic fibers, in particular of two-component fibers, which include at least one outwardly located thermoplastic component, or e.g. of a mixture of one-component fibers, where at least a portion of fibers represent thermoplastic fibers. Regarding the tampon according to Fig. 1, two-component fibers are used, where the core consisting of polyester (PES) is surrounded with a thermoplastic wrapper consisting of high- density polyethylene (PE), wherein the ratio is PE : PES = 34% : 66% up to PE : PES— 50% : 50%, and wherein a specific density of such fabric per surface unit is

12 to 20 g/m 2 and preferably at least approximately 16 g/m 2.

The tampon is manufactured in such a manner that in the first stage appropriately thick layer of said fabric is prepared for the purposes of forming a core 1, by means of which then a strip 10 is formed, which has appropriate length and width is formed. The width of said strip 10 is adapted to the length of the tampon, while the length of said strip is determined in accordance with each desired diameter of a blank for manufacturing a tampon, and consequently to each expected diameter of each tampon as such. Upon that, said strip 10 is equipped with a not shown string and also with a strip 20, which is used for the purposes of forming a covering layer 2 of the tampon, and wound around its transversal axis into appropriate roller, by which approximately cylindrical blank 100 is obtained, the length of which at least approximately corresponds to the width of said strip 10 and which is then pressed in its radial direction or in at least approximately radial direction by means of appropriately shaped jaws 31, 32, which are equidistantly arranged in the circumferential direction of said blank 100, and by means of appropriate machine 3, which is known to those skilled in the art and can be e.g. one of commercially available machines manufactured by Swiss company Ruggli AG, by which a tampon is obtained which is on the one end portion formed with a narrowed and rounded tip and on the other end portion equipped with a not shown string, which makes removing the tampon after the use thereof much easier. The shape of such manufactured tampon, which is commercially available and is at present widely used, is known among others also from the patent literature and is of that reason here neither precisely explained in the description nor presented in the drawing.

Thanks to said radial compression, such manufactured tampon (Fig. 1) comprises a plurality of grooves 1 1', 12', 13', 14', 15', 16', 17', 18', which extend in the longitudinal direction thereof and are equidistantly arranged in the circumferential direction thereof, where a rib 11", 12", 13", 14", 15", 16", 17", 18" having a slightly rounded convex outer surface 1 10", 120", 130", 140", 150", 160", 170", 180" is available between each two neighboring grooves 11', 12', 13', 14', 15', 16', 17', 18'. In the shown embodiment of the tampon according to Fig. 1, eight grooves 11 ', 12', 13', 14', 15', 16', 17', 18' and eight a ribs 11", 12", 13", 14", 15", 16", 17", 18" are available on the surface of the tampon, wherein each neighboring ribs 1 1", 12", 13", 14", 15", 16", 17", 18" may also abut each other in the area of their side flanks. The absorbent core 1 is essentially compressed in the central area 19 of the tampon. In this, those skilled in the art should understand that the number of grooves 1 1', 12', 13', 14', 15', 16', 17', 18' may also be different and is generally between 2 and 10, or optionally even more.

As mentioned, said absorbent core 1 is surrounded with a covering layer 2 around the complete circumference of the tampon. This means that said covering layer 2 extends continuously and without interruptions along the complete circumference of the tampon and is present both within said grooves 1 Γ, 12', 13', 14', 15', 16', 17', 18' and also in the area of said ribs 1 1", 12", 13", 14", 15", 16", 17", 18" including with convex outer surfaces 1 10", 120", 130", 140", 150", 160", 170", 180" thereof, which together form at least approximately cylindrical outer surface of the tampon. Previously described fibrous material as such, although not specially smoothed or otherwise treated, generally meets the requirements of commonly expected sliding ability of the outer surface of the tampon, by which the coefficient of friction is still rather high, but at the same time its permeability for liquids is also perfect.

In order to ensure essentially improved sliding ability and correspondingly low coefficient of friction on the outer surface of the tampon, during the manufacturing process by means of the radial compression of the blank 100 by means of jaws 31, 32 (Fig. 3), by which a tampon is obtained with a core 1, grooves 11 ', 12', 13', 14', 15', 16', 17', 18' and ribs 1 1", 12", 13", 14", 15", 16", 17", 18" with convex outer surfaces 1 10", 120", 130", 140", 150", 160", 170", 180" and being surrounded with a covering layer 2 around its complete circumference, such tampon is promptly upon performing said radial compression transferred throughout a conical passage 330 of appropriately heated die 33. Depending on each desired composition or combination of fibers of the covering layer 2, said die 33 is heated in the shown embodiment according to Fig. 3 by means of electric heating means 34 in such extent that the temperature on the inner surface of said conical passage 330 is 120°C to 180°C, and preferably from 122°C to 148°C.

When a previously formed tampon is e.g. by means of a pin 35 transferred throughout a conical passage 330 of appropriately heated die 33, only the convex outer surfaces 110", 120", 130", 140", 150", 160", 170", 180" of the ribs 11", 12", 13", 14", 15", 16", 17", 18" are brought into contact with the surface of the passage 330 of the heated die 33. Thanks to said composition of the fibrous material in the covering layer 2 of the tampon, where the fibers consist of a core of PE and the wrapper of PES, or the fibers of PES and fibers of PE are mixed, during such treatment of the tampon in accordance with the invention at the temperature between 122°C and 148°C, or generally between 120°C and 180°C said of PE fibers or PE component of fibers are then plasticized. Since in such state the tampon is also transferred throughout said conical passage 330 of the heated die 33, the tampon is exposed to slight and uniform compression in the area of the outer convex surfaces 1 10", 120", 130", 140", 150", 160", 170", 180" of the ribs 1 1", 12", 13", 14", 15", 16", 17", 18", which is acting towards the surface of the covering layer 2 i.e. radially inwards with respect to the tampon as such, which in combination with previously indicated plasticizing results in smoothing of the covering layer 2 solely in the area of said convex outer surfaces 1 10", 120", 130", 140", 150", 160", 170", 180" of the ribs 11", 12", 13", 14", 15", 16", 17", 18" but not also in the area of side flanks of the ribs 11", 12", 13", 14", 15", 16", 17", 18" and grooves 1 , 12', 13', 14', 15', 16', 17', 18', where the structure of said covering layer 2 remains completely unchanged, by which in the lastly mentioned areas also the permeability for liquids and capability of transferring the liquid towards the absorbent core 1 remains completely unchanged.