GB2150033A

GB2150033A - Absorbent pads

Info

Publication number: GB2150033A
Application number: GB08429648A
Authority: GB
Inventors: Kurt Stemmler
Original assignee: Winkler & Dunnebier Maschinenfabrik und Eisengiesserei & Co KG GmbH
Current assignee: Winkler & Dunnebier Maschinenfabrik und Eisengiesserei & Co KG GmbH
Priority date: 1983-11-26
Filing date: 1984-11-23
Publication date: 1985-06-26
Also published as: GB2150033B; GB8429648D0; SE8405349D0; FR2555894A1; SE460015B; DE3342963A1; SE8405349L

Abstract

An absorbent pad, particularly for use in sanitary towels, is produced of flocculent material in a suction drum apparatus. The resultant pad provides an integrated shell of flocculent material surrounding an internal superabsorbent layer. A suitable apparatus comprises a suction drum (3) having shaped recesses on its surface. At a first station (5) flocculent material is applied to partially fill the recess, at a second station (17) superabsorbent material is added and at the third station (6) further flocculent material is added to fill the recess. <IMAGE>

Description

SPECIFICATION Absorbent pads This invention in its various aspects relates to absorbent pads for the absorption of body fluids e.g. in sanitary towels, to processes for the production of such pads, and to apparatus for the production of such pads.

Difficulties are experienced in the production of absorbent pads, for example for sanitary towels, baby and adult diapers, and incontinent pads, in order to ensure that they have adequate absorption capacity for body fluids without being too bulky and unwieldy.

Another difficulty is to produce a pad of a shape which matches the shape of the human anatomy closely enough to ensure comfort for the wearer.

It has been proposed to try to overcome the first difficulty, by increasing the absorption capacity of the pads, by the introduction of so-called superabsorbent agents or flow spreaders. In practice this has so far been carried into effect only with pads made from a continuous strip or web of flocculent material.

To this end, longitudinally spaced sections of superabsorbent material are applied to an elongate web, as a rule by scattering a superabsorbent expanding agent of particulate form, whereafter the web is folded back on itself by folding along one of its lateral edges.

In this way a kind of endless sandwich is produced with longitudinally spaced sections of superabsorbent material in its interior. This endless web is subsequently parted off, in between the spaced sections, to form discrete pads, by cross cutting. Although the superabsorbent material is inboard of each end of the parted pad, the two layers of the folded web are not integrated at the ends or on one side, and it possible for particulate material to come out of the pad. Also cross cutting tends to compress the ends of pad during the cutting operation.

The requirement for a shape of pad which closely matches the human anatomy can be met either by complicated cutting, folding and upsetting of a flocculent web or more simply by shaping the pads on a rotary suction drum.

A drum of this kind is basically a hollow cylinder whose interior is maintained at a negative pressure to provide suction at its periphery and whose external surface is formed around its periphery with a series of shaping recesses each corresponding to the required pad shape. The bases of the recesses are formed of mesh and are in air-conveying communication with the drum interior. The flocculent material, which as a rule is a hydro- philic cellulose, which has been reduced in an appropriate mill, is brought to the drum surface by means of an airstream, and is sucked through into the recesses by the suction applied to the mesh-like bases thereof and eventually fills the recesses completely.Flocculent material which is applied in excess of the volume of the recess is removed by combing in a subsequent working step for example by means of rotating brushes, and an absorbent pad is therefore produced which, in shape and size, corresponds to the shaping recess in the drum surface. Unfortunately the absorption capacity for body fluids, particularly in sanitary towels, of pads produced in this way by the formation of a pad entirely from flocculent material, is determined by the quantity of cellular flocculent material it contains. In practice this is found to be limited and therefore has not achieved the desired result.

Amongst its objects therefore the present invention aims to provide an absorbent pad of flocculent material for the absorption of body fluids, for example for use in sanitary towels, in which the pads both have a better shape for matching that of the human anatomy, and also an improved absorption capacity. It is also amongst the objects of the present invention to provide an improved process and an improved apparatus for the production of such pads.

According to one aspect of the present invention an absorbent pad for the absorption of body fluids, e.g. sanitary towels, comprises a pad body and a core of superabsorbent material, the pad body being of an integrated nature and entirely embracing the core on all sides.

According to another aspect of the present invention an absorbent pad for the absorption of body fluids, e.g. for sanitary towels, comprises a flocculent envelope and a core of superabsorbent material, the envelope substantially or entirely embracing the core on all sides with the flocculli of the envelope forming a substantially integral shell.

Such pads have the advantage over prior proposals that the superabsorbent material is retained within the pad, and also this design of pad lends itself to production by the suction method, so avoiding a cutting step, with the consequent disadvantages outlined above.

Whilst a single type of flocculent material may be used, it is advantageous, in many applications, for the pad body to have floculent layers of different characteristics. For example the pad body may have a flocculent layer on one side which is capable of conveying body fluids faster that a second flocculent layer of the pad on the opposite side, and/or the layer on said opposite side has a body fluid storage capacity per unit volume which is higher than the capacity in the layer on the one side.

According to another aspect of the present invention a process for the production of absorbent pads for the absorption of body fluids, e.g. in sanitary towels comprises building up the pad in at least three stages comprising: (i) the formation of a first body, of flocculent material, (ii) applying to, or forming in situ, on the first body, a second body, of superabsorbent material which lies inboard of an entire peripheral region of the first body, and (iii) the formation, in situ, of a third body, of flocculent material, which overlies the second body and said peripheral region of the first body.

Conveniently the formation at stage (iii) causes substantial or complete integration of the flocculent first and third bodies in said peripheral region.

As discussed above, the pad may be formed of different flocculent materials. Thus it may be arranged that the flocculent material employed to form the first and third bodies have different abilities to convey body fluid and/or different body fluid storage capacities per unit volume of the layers.

The three stages may be carried out on a rotating suction drum formed in its external rotary surface with shaping recesses substantially of the intended form of the final absorbent pad, and means being provided in three successive zones, through which each recess in turn passes, respectively to introduce a first quantity of flocculent material less than that needed to fill the shaping recess, the superabsorbent material, and a second quantity of flocculent material sufficient to fill the recess completely.

Accordingly to yet another aspect of the present invention apparatus for the production of absorbent pads for the absorption of body fluids e.g. in sanitary towels, comprises a suction drum having its interior connected to a source of suction, and its exterior formed around its periphery with shaping recesses with the lower side of each shaping recess communicating with the interior of the drum, and three successive stations disposed around the drum and serving (a) at a first station for applying a flocculent material to an aligned recess, without filling that recess (b) at a second station, following the first station, for applying superabsorbent material to the flocculent material applied to the recess at the first station, and (c) at a third station for applying further flocculent material to fill the recess.

The station for applying the superabsorbent material may take different forms, e.g. it may be a scattering device, or it may be a sheet inserter.

A flock mill may be included which is common to the first and third stations, and a flock distributor for distributing the flocculent material from the flock mill to each of the first and third stations. Alternatively the first and third stations may be arranged to apply flocculent material of different body fluid conveying ability and/or different body fluid storage capacity per unit volume of the flocculent material.

The invention also embraces an absorbent pad when produced by the above defined process and/or apparatus.

The invention may be carried into practice in a number of ways but one specific embodiment will now be described with reference to the accompanying drawings in which:~ Figure 1 is a diagrammatic illustration of an apparatus according to one aspect of the present invention for the production of absorbent pads; Figure 2 diagrammatically illustrates a long.

itudinal cross section of one suction recess on the periphery of a rotary suction drum of the apparatus of Fig. 1, and Figure 3 is a transverse cross section of the absorbent pad on the line 3-3 of Fig. 2.

Referring to Fig. 2, the process according to the invention for the production of novel absorbent pads which are better shaped to fit the human anatomy and which have a better absorbency, involves the production of the pad in three stages whereby a first flocculent layer 20 is drawn into a recess 2 formed by a curved piece of mesh-like material 21 formed in the periphery of a rotary suction drum as will be described in relation to Fig. 1. After the first layer of flocculent material 20 is introduced into the recess, a second layer, of superabsorbent material 22, is introduced, and finally a third layer 23, again of flocculent material, is introduced to complete the filling of the recess 2.It is to be noted that the super-absorbent layer 22 both as seen in longitudinal section in Fig. 2, and in transverse section in Fig. 3, does not extend to the periphery of the recess 2 so that a peripheral region generally indicated at 24 of the first flocculent layer 20 completely surrounds the super-absorbent layer 22. In this way, when the second flocculent layer 23 is applied, there is an interface between the two flocculent layers 20 and 23, but, due to the suction method of application, the flocculli of the two layers tend to integrate in the region 24 to provide an integrated flocculent envelope or shell entirely surrounding the intermediate superabsorbent layer 22.

Referring to Fig. 1, the apparatus diagramatically shown therein includes a suction drum 1 which is a hollow cylinder and whose peripheral surface is formed with the shaping recesses 2 for the formation of the required shape of absorbent pads. The suction drum has a suction box 3 therein, the box being connected by a line 4 to a source of suction not shown. The pressure inside the drum outside the suction box is normal atmospheric pressure. Situated externally of the drum are two spaced stations 5 and 6 for the application of flocculent material, each station comprising a large volume tube through which an airflow conveys cellulose flocculent material to the generated surface of the drum in the respective regions embraced by the stations 5 and 6. In this way, the flocculent material is conveyed to the recesses 2 in each of the stations 5 and 6.The hydrophilic cellulose flocculent material is obtained from an endless cellulose web 8 by means of a mill 7 shown here in only very diagrammatic form. A blower 9 disposed adjacent the mill 7 produces the air stream necessary to convey the flocculent material to the stations 5 and 6.

The stream of flocculent material is divided into two separate components or flows by means of a flock distributor 10 which takes the form of a pipe junction, the distribution ratio being adjustable as required by means of a pivoted flap to vary the flow to the different stations 5 and 6.

Between the stations 5 and 6 i.e. at an intermediate region around the periphery of the drum there is a gap through which the generated surface of the drum 1 is accessible, and, disposed in this region, is a further station 17 for the application of superabsorbent material which, in the specific embodiment shown, is a device for scattering superabsorbent expanding agent or flow spreader onto the upper surface of the central region of the first flocculent layer 20. In an alternative arrangement, cut strips of superabsorbent material may be similarly applied to the central region of the upper surface of the first flocculent layer 20.

Positioned upstream of the three stations 5, 1 7 and 6 is a combing device 11 which is adapted to remove surface flocculent material projecting from the recesses 2 after these clear the second station 6 for the aplication of flocculent material. The combing device 11 has rotating hackles 12 and returns the surplus material thus removed through a line 13 to the blower 9 for reuse.

The finished absorbent pads 14 are removed from the recesses 2 by a suction roller 1 5 and deposited on a conveyor belt 16 from which they are transferred for subsequent processing.

It will be appreciated from the description that the absorbent pads produced by this apparatus and method have the advantage of the introduction of a superabsorbent layer in a pad which has otherwise been individually manufactured with its two flocculent layers.

These layers are preferably integrated at their interface by the suction method of manufacture to produce both a strong construction and one which the ends of the pads are not sufferring from the compression previously caused by cross cutting of a strip of material.

Whilst the apparatus of Fig. 1 envisages the application to the recess of first and second layers 20 and 23 respectively of the same type of flocculent material, in an alternative construction, the two stations 5 and 6 are connected to separate sources of flocculent material, thereby to produce flocculent layers 20 and 23 of different characteristics. For example one layer may have a better ability to convey body fluid inwardly towards the superabsorbent layer and in this case (or alternatively) the other flocculent layer may be produced from flocculent material which has a higher storage capacity for body fluid per unit volume than the first layer. In this instance it will be appreciated that the first layer, having the better conveyancy, is that which would normally be closest to the wearer.

The individual pads conveyed away from the apparatus of Fig. 1 can undergo processing of a conventional nature, for example the introduction of the pads into surrounding absorbent paper envelopes with the interposition, if required, on the intended outer face of the pad of an impermeable protective plastics layer.

Claims

1. An absorbent pad for the absorption of body fluids e.g. for sanitary towels, comprising a pad body and a core of superabsorbent material, the pad body being of an integrated nature and entirely embracing the core on all sides.

2. An absorbent pad for the absorption of body fluids, e.g. for sanitary towels, comprising a flocculent envelope and a core of superabsorbent material, the envelope substantially or entirely embracing the core on all sides with the flocculli of the envelope forming a substantially integral shell.

3. An absorbent pad as claimed in claim 2 in which the pad body has flocculent layers of different characteristics.

4. An absorbent pad as claimed in claim 3 in which the pad body has a flocculent layer on one side which is capable of conveying body fluids faster than a second flocculent layer of the pad on the opposite side, and/or the layer on said opposite side has a body fluid storage capacity per unit volume which is higher than the capacity in the layer on the one side.

5. A process for the production of absorbent pads for the absorption of body fluids e.g. in sanitary towels, comprising building up the pad in at least three stages comprising: (i) the formation of a first body, of flocculent material, (ii) applying to, or forming in situ on, the first body, a second body, of superabsorbent material which lies inboard of an entire peripheral region of the first body, and (iii) the formation, in situ, of a third body, of flocculent material, which overlies the second body and said peripheral region of the first body.

6. A process as claimed in claim 5 in which the formation at stage (iii) causes substantial or complete integration of the flocculent first and third bodies in said peripheral region.

7. A process as claimed in claim 5 or claim 6 in which the flocculent material em ployed to form the first and third bodies have different abilities to convey body fluid and/or different body fluid storage capacities per unit volume of the layers.

8. A process as claimed in any one of claims 5 to 7 in which the three stages are carried out on a rotating suction drum forward in its external rotary surface with shaping recesses substantially of the intended form of the final absorbent pad, and means being provided in three successive zones, through which each recess in turn passes, respectively to introduce a first quantity of flocculent ma terial less than that needed to fill the shaping recess completely, the superabsorbent ma terial, and a second quantity of flocculent material sufficient to fill the recess completely.

9. A proces as claimed in claim 8 in which the quantity of flocculent material sup plied in the first zone fills the recess to substantially one third of its capacity.

10. A process as claimed in any one of claims 5 to 9 in which the superabsorbent material is formed in situ at stage (ii) in the form of scattered material.

11. A process as claimed in any one of claims 5 to 9 in which the superabsorbent material is applied at stage (ii) in sheet form.

12. Apparatus for the production of absor bent pads for the absorption of body fluids, e.g. in sanitary towels, comprising a suction drum having its interior connected to a source of suction, and its exterior formed around its periphery with shaping recesses with the lower side of each shaping recess communi cating with the interior of the drum, and three successive stations disposed around the drum and serving (a) at a first station for applying a flocculent material to an aligned shaping recess, without filling that recess (b) at a second station, following the first station, for applying superabsorbent material to the flocculent material applied to the recess at the first station, and (c) at a third station for applying further flocculent material to fill the recess.

13. Apparatus as claimed in claim 12 in which the station for applying the superabsor bent material is a scattering device.

14. Apparatus as claimed in claim 12 in which the station for applying the superabsor bent material is a sheet inserter.

15. Apparatus as claimed in any one of claims 12 to 14 including a flock mill which is common to the first and third stations, and t aflock flow distributor for distributing the flocculent material from the flock mill to each of the first and third stations.

16. Apparatus as climed in any one of claims 12 to 14 in which the first and third stations are arranged to apply flocculent material of different body fluid conveying ability and/or different body fluid storage capacity per unit volume of the flocculent material.

17. An absorbent pad for the absorption of body fluids when produced by a process or apparatus according to any one of the preceding claims.

18. An absorbent pad for the absorption of body fluids e.g. for sanitary towels substantially as described herein with reference to Fig. 2 of the accompanying drawings.

19. A process for the production of absorbent pads for the absorption of body fluids, e.g. for sanitary towels, substantially as described herein with reference to the accompanying drawings.

20. Apparatus for the production of absorbent pads for the absorption of body fluids e.g. for sanitary towels, substantially as described herein with reference to the accompanying drawings.