Patent Application
20110114660
The present invention relates to a dispenser for absorbent articles in the form of sanitary napkins, panty liners, interlabial products, tampons, baby diapers or incontinence protectors.
In order to enable a user of sanitary napkins or the like to bring with her a daily supply of sanitary napkins in a handbag or the like, sanitary napkins are often packaged in individual packages. However, for several reasons, the need for a sanitary napkin may unexpectedly arise and there is therefore a need for having supplies of such articles available in public places such as in public toilets, in shopping centres or the like, in hospitals, in pubs and restaurants, in hotels, in airports, in aeroplanes, busses and trains, in offices, etc.
This need has to some extent been solved by dispensers for absorbent articles such as sanitary napkins. Such dispensers typically comprise a housing comprising a store of absorbent articles, said housing having an outlet through which the articles are dispensed.
WO 99/26576 discloses a dispenser for interlabial devices which is of simple construction. The interlabial devices are arranged as a continuous array of individually packaged devices joined together by frangible connections.
U.S. Pat. No. 6,254,582 discloses a supply of panty liner pads formed by a continuous longitudinal array of pad segments forming a strip. The strip has locally weakened zones to facilitate tearing off segments from the strip without the use of a cutting tool. The strip is wrapped upon itself into a roll so that pressure sensitive positioning adhesive strips are placed into contact with release surfaces formed on the strip, thereby protecting the adhesive prior to use without the need for release paper.
WO 2005/051261 describes a dispenser for absorbent articles from a roll. The dispenser comprises means for separating absorbent articles from a release material, and means for storing the portion of release material from which said absorbent articles have been separated.
It is known to provide sanitary napkins with garment-facing surfaces which have a high coefficient of friction, so as to improve the adherence of the napkins to the wearer's underwear. High-friction surfaces may be used alone or in combination with garment adhesive. An example of a sanitary napkin with a high-friction garment-facing surface is provided in EP 1 493 411. However, the present invention is not concerned with absorbent articles which themselves have integral high-friction surfaces.
To allow controlled dispensing of the articles, dispensers such as those described above comprise friction means which deliver an absorbent article from a stack or roll to the outlet. This means relies on frictional contact with the absorbent article to remove it from the stack or roll and to convey it towards the outlet.
One particular problem which can occur in dispensers such as those described above is that frictional contact between the friction means and the sanitary napkin to be dispensed is not sufficient, and the friction means does not grip the leading sanitary napkin. This is especially relevant when the sanitary napkins are supplied in a stack. As it is the weight of the remaining napkins in a vertical stack which presses the leading sanitary napkin against the friction means, there often comes a point at which there is insufficient frictional force between the friction means and the leading sanitary napkin. The dispenser then becomes blocked, or fails to deliver an absorbent article.
This problem is further compounded by the fact that many absorbent articles such as sanitary napkins are packaged in some way or have some sort of cover which has a low coefficient of friction with the surroundings. For instance, sanitary napkins which have garment adhesive on their garment-facing surface often have release papers which have been treated with e.g. silicone so that they can be released from the adhesive when required. The presence of the silicone coating on the release paper reduces the friction forces with the components of the dispenser.
The present invention addresses the above-mentioned problems, and thus provides a dispenser for dispensing an absorbent article, said absorbent article being arranged in a stack or a roll of absorbent article, in which at least a portion of each absorbent article is covered by a cover wrapper. The dispenser comprises a housing, said housing comprising an outlet through which the absorbent articles are dispensed; support means for supporting said stack or roll and friction means which is arranged to make contact with the cover wrapper of a leading absorbent article and deliver said leading absorbent article from said stack or roll towards the outlet. The friction means has a friction material comprising that surface of the friction means which is arranged to make contact with the cover wrapper. The friction material has a static coefficient of friction against the surface of the cover wrapper as measured by the method described herein of at least 0.4, preferably at least 0.6, most preferably at least 1.0.
Suitably, the dispenser is adapted to support absorbent articles arranged in a stack. The friction means may comprise a belt. In one embodiment, the dispenser further comprises an electric motor, control unit and activator for said control unit, arranged such that activation of the activator by a user causes the electric motor to drive the friction means and dispense an absorbent article. Suitably, there is an in-built time delay such that—after a user has activated the activator and a first absorbent article has been dispensed—a certain minimum time expires before a second absorbent article can be dispensed, such as e.g. at least 30 seconds, at least 60 seconds, at least 120 seconds, at least 300 seconds or at least 600 seconds. The activator may be selected from the group consisting of a push-button, a lever, a wheel, an IR sensor, a camera, a coin-operated device and a magnetic sensor.
The dispenser according to the invention may be arranged such that—after delivering the leading absorbent article from said stack or roll towards the outlet—the friction means reverses its direction of movement a short distance, e.g. between 5-15 mm.
The absorbent article may be a sanitary napkin or panty liner, and is preferably a sanitary napkin.
In relation to the present invention, the term “absorbent article” is used to describe an article which is worn in contact with the body, in the anogenital region, and used to absorb bodily exudates such as faeces, urine or menstrual blood.
The absorbent articles of the present invention are “disposable”, i.e. they are not intended to be cleaned or reused, but are rather discarded after use.
The term “leading sanitary napkin” or “leading absorbent article” is used to describe that sanitary napkin or absorbent article which is next to be dispensed upon activation of the dispenser. The term “following sanitary napkin” or “following absorbent article” is used to describe that sanitary napkin or absorbent article which lies after the leading sanitary napkin or leading absorbent article in the dispenser.
The invention will now be described with reference to the appended schematic Figures, in which
a-3c illustrate the workings of the dispenser according to one embodiment;
The absorbent articles 20 to be dispensed by the dispenser 10 may be sanitary napkins, panty liners, interlabial products, tampons, baby diapers or incontinence protectors, of which sanitary napkins and panty liners are preferred. In the following, the invention is described in relation to a sanitary napkin, but is also applicable to the other absorbent articles listed above. Typically, such absorbent articles 20 comprise a liquid-permeable topsheet, a liquid impermeable backsheet and an absorbent body located between said topsheet and said backsheet. The absorbent article 20 may also comprise one or more layers which are designed to improve the handling of bodily waste e.g. transfer, distribution, surge or acquisition layers, which are usually located between the topsheet and the absorbent core.
The dispenser 10 comprises a housing 11. The housing may be formed in one or more sections, such as a front 11a and rear section 11b as shown in
The housing 11 comprises an outlet 12, through which absorbent articles 20 are dispensed. The outlet 12 shown in
The stack 15 or roll 16 of absorbent articles 20 are supported within the dispenser 10 on support means 13. In the case of the stack 15 of articles shown in
The stack 15 or roll 16 of absorbent articles can be considered as comprising a leading absorbent article 20′, a following absorbent article, and further absorbent articles. As described above, the term “leading absorbent article” is used to describe the absorbent article which is next to be dispensed upon activation of the dispenser (e.g. that lying at the top or bottom of a stack 15, or outermost on a roll 16).
At least a portion of each absorbent article 20 in a stack 15 or roll 16 is covered by a cover wrapper 22. Preferably, the entirety of each absorbent article 20 is covered by a cover wrapper 22, as shown in
In addition to the above-mentioned components, the housing 11 of the dispenser comprises friction means 30 which is arranged to make contact with the cover wrapper 22 of a leading absorbent article 20′. The leading absorbent article 20′ may be supported on the friction means 30, as shown in
Additional means for delivering the absorbent article 20 towards the outlet 12 may be present between the friction means 30 and the outlet 12. For instance, the absorbent article may have to pass along one or more chutes or channels or over one or more rollers or belts before being dispensed from the dispenser 10 through the outlet 12.
The surface of the friction means 30 which makes contact with the cover wrapper 22 of the leading absorbent article 20′ comprises a friction material 31. The friction material 31 may be integral with the friction means 30 (i.e. it may comprise the outer surface of the friction means 30) or it may comprise a separate component. For example, if the friction means 30 is a cylinder or wheel, the friction material 31 may be the outer surface of said cylinder or wheel, or it may be a sleeve located on the cylinder or wheel.
The surface of the cover wrapper 22 which contacts the friction means 30 has a static coefficient of friction against the friction material 31 as measured by the method described herein of at least 0.4, preferably at least 0.6, most preferably at least 1.0.
Friction forces are categorized as either static or kinetic. Static friction is generally understood as the force required to start an object moving against another, while kinetic friction is the force required to maintain movement, once initiated. The present invention relates solely to static friction.
The coefficient of friction between two surfaces relates the frictional force exerted on an object (e.g. that required to initiate movement) to the normal force exerted between the two surfaces (e.g. the weight of an object resting on a surface). The coefficient of static friction is typically greater than that of kinetic friction.
The static friction force must be overcome by an applied force before an object will move. Multiplying the coefficient of static friction by the normal force provides the maximum possible friction force between two surfaces before sliding begins: Fmax=μsN. Before any sliding occurs, the friction force takes any value from zero up to Fmax. Any force smaller than Fmax attempting to slide one surface over the other will be opposed by a frictional force of equal magnitude and opposite direction. Any force larger than Fmax, will overcome the force of static friction and cause sliding to occur. When sliding occurs, kinetic friction is applicable, and static friction is no longer relevant.
A dispenser 10 in which the surface of the cover wrapper 22 which contacts the friction means 30 has the minimum static coefficient of friction against the friction material 31 set out above addresses the problems associated with the prior art. In particular, the tendency of the friction material 31 to slip against the cover wrapper 22 is reduced. In this way, effective and reliable dispensing of absorbent articles 20 can be obtained, as the number of times a dispenser 10 fails to dispense an absorbent article 20 through slippage of the two contact surfaces is reduced.
Problems relating to friction between the cover wrapper 22 of the sanitary napkin 20 and the friction means 30/friction material 31 also arise in the case of a roll 16. In order for a sanitary napkin 20 to be dispensed, the roll 16 must be set in rotary motion, and its rotational inertia must therefore be overcome. When a roll 16 is new, and contains many sanitary napkins 20, it has relatively high rotational inertia. The present invention has realised—in such cases—that a sufficiently high static coefficient of friction must be present between the leading sanitary napkin 20′ and the friction material 31 for effective dispensing.
The dispenser 10 according to the invention may be operated in a number of ways. The dispenser may be manually operated, so that e.g. a lever, push-button or wheel is used to drive the friction means 30 mechanically.
Advantageously, the dispenser 10 is operated electrically, and therefore comprises an electric motor 17, a control unit 18 and activator 19 for said control unit 18. These components are arranged such that activation of the activator 19 by a user causes the electric motor 17 to drive the friction means 30 and dispense an absorbent article 20. A suitable activator 19 for the control unit 18 may be a push-button, a lever, a wheel, an IR sensor, a camera, or a magnetic sensor. The activator 19 may also be a coin-operated device.
The control unit 18 comprises the necessary circuitry to receive a signal from the activator 19 and to send a signal to the electric motor 17. The control unit 18 may introduce an in-built time delay, so that—after a user has activated the activator 19 and a first absorbent article 20 has been dispensed—a certain minimum time expires before a second absorbent article can be dispensed. The time delay may be e.g. at least 30 seconds, at least 60 seconds, at least 120 seconds, at least 300 seconds or at least 600 seconds. This time delay discourages the theft of large numbers of sanitary napkins 20 from the dispenser 10, as a potential thief will have to wait a long time to be able to collect more than a few absorbent articles 20.
An electrically-operated dispenser 10 requires a power source, which is illustrated as batteries 25 in
It is also advantageous that the dispenser 10 according to the invention is arranged such that—after delivering said leading absorbent article 20′ from said stack 15 or roll 16 towards the outlet 12—the friction means 30 reverses its direction of movement. This is illustrated in
The static coefficient of friction between two materials is measured according to DIN test method 53375 (November 1996). A simplified diagram of the apparatus used in the test method is shown in
The apparatus consists of a sledge 110 which is adapted to be pulled over a horizontal table 112 by means of an inelastic nylon cord 114. The sledge 110 is 64 mm wide, 63 mm long and has a mass of 200 g. A tensile tester 116 is attached to the remote end of the nylon cord 114, via a spring 115. The tensile tester 116 used in these experiments is an Instron 4301 apparatus, with a static load cell of maximum load 10N, connected to a computer for recording, calculating and storing the results. The spring 115 was obtained from Stock Spring in Lesjöfors, Sweden (Art. No. 3285) and has a force constant of 0.204N/mm. In this particular case, the nylon cord 114 runs through a pulley 117 to change the direction of action.
A sample of cover wrapper 22 having the same width as the sledge 110 is placed on the underside of the sledge 110, so that the entire lower surface of the sledge 110 is covered by cover wrapper material. The cover wrapper 22 is folded over the leading edge of the sledge 110 in the direction of travel, and secured to the upper surface of the sledge 110 with double-sided sticky tape, allowing the back part to hang free. The sledge 110 and cover wrapper 22 are conditioned for 4 h at 50±5% RH and 23±1° C.
The table 112 consists of the friction material 31 defined in the present invention; i.e. that surface of the friction means 30 which makes contact with the cover wrapper 22 in the dispenser 10. A sample of the friction material 31 with dimensions corresponding to those of the table 112 is flattened out and fastened with double-sided tape to the table 112.
The sledge 110 and cover wrapper 22 are placed on the friction material 31, with the nylon cord 114 directed towards the pulley 117, such that the sample of cover wrapper 22 lies flat. The tensile tester 116 is zeroed with the sledge 110 lying on the friction material 31, without load. The cord 114 is tightened to 0.05N, and the tensile tester is zeroed again. The tensile tester 116 is started, and begins pulling on the nylon cord 114, via spring 115. The tensile tester 116 records the force required to start movement of the sledge 110.
After each test, a new cover wrapper 22 and friction material 31 were used. Five tests were carried out for each friction material. The results are presented by the apparatus as a chart, with time on the x-axis and force on the y-axis. The peak y-value of the curve is used to calculate the coefficient of static friction.
The static coefficient of friction μs is calculated as follows:
wherein Fs=the force require to overcome adhesive friction. Fs is calculated by:
F
s
=F−Δ
in which F is the force in Newtons obtained during the tests and Δ is calculated by:
in which v is the pulling speed (=100 mm/60 s), D is the spring constant of the spring (=0.204N/m≈2.105 g/s2), m is the mass of the sledge (=200 g) and g is the gravitational acceleration constant (9.81 m/s2). Δ is a measure of the inertia of the sledge, which produces an inertia force at the beginning of the sledge's movement. The value of the adhesive friction Fs is therefore changed by the small amount Δ.
Furthermore FN is obtained by;
F
N
=w×g
wherein w is the mass of the sledge (=200 g) and g is the gravitational acceleration constant (9.81 m/s2).
In the following experiments, the cover wrapper material was a 30 gsm blown polyethylene film which is commercially available from M&W Verpackungen, supplier code KC 5080.010.
Eight different samples of friction material were used, which are shown in Table 1 (
Table 2 shows the static coefficient of friction obtained for friction materials 1-8 using the method described above.
The ability of the friction materials 1-8 to dispense sanitary napkins from a stack was modelled using the apparatus shown in
The apparatus shown in
A front 211 spindle and a rear spindle 212 are arranged in parallel at the bottom of the housing 210, such that they extend laterally across the housing 210, as shown in
The front of the housing 210 is cut away in front of the front spindle 211 in a direction parallel to the extension of the spindles 211, 212, to provide an outlet 213 for the leading sanitary napkin 20′. The outlet 213 in this apparatus extends the entire width of the housing, and extends to a distance of approximately 13 mm above the surface defined by the upper edges of the spindles 211, 212.
A strip of friction material 31 is provided having a width of 34 mm, and a length which is at least long enough to pass over both spindles and hang down at the front and rear of the apparatus and allow both gripping and 25 mm of movement during dispensing as described below. The strip is passed over the front and rear spindles 211, 212 as shown in
A stack of 35 sanitary napkins is placed within the housing 210, so that the leading sanitary napkin 20′ makes contact with and is supported by the friction material 31, as shown in
The strip of friction material 31 is pulled tightly across the spindles 211, 212, and—while maintaining the tension in the friction material 31—the front and rear ends of the friction material 31 are pulled alternately, so as to move the friction material 31 through the housing 210. The friction material 31 moves enough to dispense a single sanitary napkin 20 (ca. 25 mm), and is then returned to its original position.
When moving forwards, the friction material 31 has a static coefficient of friction with the cover wrapper 22 of the leading sanitary napkin 20′ which is sufficient to drag the leading sanitary napkin 20′ from under the stack 15 and deliver it through the outlet 213.
The friction material 31 is moved back and forth repeatedly until all sanitary napkins 20 are dispensed from the housing 210. If a sanitary napkin 20 fails to be dispensed upon pulling the friction material forward (e.g. it does not grip the friction material 31) a “fail” is recorded. The “failed” napkin is removed manually and the test continued.
Each test is repeated five times for each friction material 31. The results are shown in Table 3.
The friction materials 7 and 8 were not suitable as a friction material for the dispenser, as they failed to dispense a number of products. Other materials were suitable friction materials for the dispenser. Material 6 gripped products well, but had the tendency to gather dirt. Materials 1-5 generally functioned well. It is noticeable that problems often occurred in dispensing the last absorbent article, as there was no stack pressure acting upon it.
The invention has been described with reference to a number of embodiments. However, the scope of the invention should be defined by the appended claims. In particular, the dispenser of the invention may also be used to dispense other absorbent articles such as panty liners, interlabial products, tampons, baby diapers or incontinence protectors.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/SE07/50851 | 11/15/2007 | WO | 00 | 5/17/2010 |
