Patent Description:
For manufacturing an absorbent article such as diaper, there has been a technique in which a partial area in an absorbent core is made have different thickness from the other area in the core. In the technique, one of the two fiber stacking drums forms a first absorbent layer; another of the two fiber stacking drums forms a second absorbent layer, which has a smaller area than the first absorbent layer; and the first and second absorbent layers overlap with each other, thereby producing an absorbent core, which has a partial area thicker than the rest. <CIT> discloses a method for manufacturing an absorbent article. The method comprises a first absorbent layer and a second absorbent layer having the same thickness formed on a first drum and a second drum, respectively. The method comprises a step of passing the first absorbent layer over a belt member, and passing the second layer over the first layer after passing the first layer over the belt member. In this manner, the first absorbent layer and second absorbent layer are laminated together onto the belt member.

Since the convention technique overlaps the two layers by simply putting the one on the other, the two layers are likely to be out of alignment during transporting or using the absorbent article.

It is an object of the present invention to provide a method and an apparatus for manufacturing an absorbent core having portions that are different in thickness, the different thickness portions being prevented from out of alignment.

The above object is achieved by the present invention according to claims <NUM>, <NUM> and <NUM>.

A first method for manufacturing an absorbent core uses a feed device <NUM>, a first drum <NUM>, and a second drum <NUM>,.

With this first method, the thick portion C2 stacked on the second drum <NUM> is transferred to the first drum <NUM>, and then the thin portion C1 is stacked on the first drum <NUM>. Thus, the thin portion C1 is stacked around the thick portion C2, and the thin portion C1 and the thick portion C2 are unlikely to be out of alignment with each other.

A second method for manufacturing an absorbent core uses a feed device <NUM>, a first drum <NUM>, and a second drum <NUM>,.

With this second method, the thin portion C1 is formed on the first drum <NUM>, and then the thick portion C2 on the second drum <NUM> is transferred from the second drum <NUM> to the inhibition area a3 (an area where the thin portion C1 is not formed) of the first drum <NUM>, the thick portion C2 and the thin portion C1 fitting with each other. Thus, the thin portion C1 is positioned around the thick portion C2. Therefore, the thin portion C1 and the thick portion C2 are unlikely to be out of alignment.

An apparatus of the present invention includes:.

With this apparatus of the present invention, the thick portion C2 formed on the second drum <NUM> is transferred to the first drum <NUM> and placed on an area where the thin portion C1 is not formed. Thus, the thin portion C1 is stacked so as to surround the thick portion C2. Therefore, the thin portion C1 and the thick portion C2 are unlikely to be out of alignment.

In the first method of the present invention, it is preferred that the thick portion C2 on the second drum <NUM> is placed in the first area α1 of the first drum <NUM> by being sucked and made to cling to the first area α1 in a state where the fiber F of the thin portion C1 is not yet stacked in the first area α1.

In this case, the thick portion C2 on the second drum <NUM> is placed on the first area α1 of the first drum <NUM> and sucked in the first area α1, so the thick portion C2 is more likely to be out of alignment.

In the second method of the present invention, it is preferred that, in the step of forming the thick portion C2 on the second drum <NUM>, the thick portion C2 is formed so as to coincide with a planar shape of the inhibition area a3 of the first drum <NUM>.

In this case, it is possible to transfer the thick portion C2 to the inhibition area a3, with the thick portion C2 being coincided with the inhibition area a3 in shape.

In the second method of the present invention, in the step of forming the thin portion C1 on the first drum <NUM>, the fiber F may not be stacked in the inhibition area a3.

In the methods of the present invention, in the step of forming the thin portion C1, the thin portion C1 may continuously be formed along the outer circumferential portion <NUM> of the first drum <NUM> so as to form the absorbent core C, which is continuous.

In this case, the continuous absorbent core C is cut in an individual wearable article unit.

In the methods of the present invention, the absorbent core C is formed such that a surface of the thick portion C2 protrudes more than (higher than) a surface of the thin portion C1.

In the case where the device of the present invention is applied to the first method of the present invention, the second drum <NUM> makes contact with the first drum <NUM> at the point P, with the thick portion C2 placed between the first drum <NUM> and the second drum <NUM>, such that the thick portion C2 stacked on the second drum <NUM> is passed (transferred) from the second drum <NUM> to the first drum <NUM> in a state where the thin portion C1 is not yet stacked on the first drum <NUM>.

On the other hand, in the case where the device of the present invention is applied to the second method of the present invention, the second drum <NUM> makes contact with the first drum <NUM> at the point P, with the thick portion C2 placed between the first drum <NUM> and the second drum <NUM>, such that the thick portion C2 stacked on the second drum <NUM> is transferred from the second drum <NUM> to an inhibition area a3 of the first drum <NUM> in a state where the thin portion C1 is stacked on the first drum <NUM> in the first area α1 other than (except) the inhibition area a3, where stacking of the fiber F of the thin portion C1 is inhibited and the fiber F of the thin portion C1 is not stacked.

Any feature illustrated and/or depicted in conjunction with one of the aforementioned aspects or the following embodiments may be used in the same or similar form in one or more of the other aspects or other embodiments, and/or may be used in combination with, or in place of, any feature of the other aspects or embodiments.

The present invention will be understood more clearly from the following description of preferred embodiments taken in conjunction with the accompanying drawings. Note however that the embodiments and the drawings are merely illustrative and should not be taken to define the scope of the present invention. The scope of the present invention shall be defined only by the appended claims. In the accompanying drawings, like reference numerals denote like components throughout the plurality of figures.

An absorbent core manufactured by the device of the present invention is used as a core for such as disposable underwear, diapers, and incontinence pads. The core may be in hourglass shape in planar view.

As shown in <FIG>, a manufacturing device includes a feed device <NUM>, a first drum <NUM>, and a second drum <NUM>.

The feed device <NUM> includes a cylindrical case <NUM> and a defibrating machine <NUM>. The defibrating machine <NUM> defibrates (comminutes) pulp fed from the upstream to produce fluff pulp (fiber). The fluff pulp filled in the case <NUM> passes through a first duct portion <NUM> and a second duct portion <NUM>, and is stacked on an outer circumferential portion <NUM> of the first drum <NUM> and an outer circumferential portion <NUM> of the second drum <NUM> due to negative pressure from respective suction chambers (not shown) of the first and second drums <NUM>, <NUM>. The defibration and stacking described above are well-known technique in the art, and they are disclosed in <CIT>, for example.

Note that high molecular compound particles (super absorbent polymer particles), as it is called SAP, having high absorbing capacity may be added as a construction material for the absorbent core.

The first and second drums <NUM>, <NUM> are in an approximately cylindrical shape, and are formed by plural segments (not shown) as in the well-known art. The first drum <NUM> and the second drum <NUM> are provided with the first duct portion <NUM> and the second duct portion <NUM>, respectively. These drums <NUM>, <NUM> continuously rotate in the circumferential direction R, and suck the fiber F fed from the feed device <NUM> from the outer circumferential portions <NUM>, <NUM> of these drums <NUM>, <NUM> toward the respective inside suction chambers (not shown). Thus, the fiber F is continuously clung to and stacked on a predetermined first area α1 in the outer circumferential portion <NUM> and a predetermined second area α2 in the outer circumferential portion <NUM>.

The suction chambers are provided to the respective drums <NUM>, <NUM> so as to correspond to a predetermined suction section T1 along the circumferential direction R. Each suction chamber is connected to a negative pressure source (not shown) so that the chamber is in negative pressure. The suction chambers are positioned close to the inside of the outer circumferential portion <NUM>, <NUM> of the respective drums <NUM>, <NUM>. Thus, the fiber F is clung to and stacked on the drums <NUM>, <NUM> during the suction section T1.

On the other hand, each drum <NUM>, <NUM> is provided with a non-suction section T2, in which the outer circumferential portion <NUM>, <NUM> of the drums does not pass by the suction chamber.

In the present embodiment, the first area α1 of the first drum <NUM> is continuously provided in the circumferential direction R of the first drum <NUM>, whereas the second area a2 of the second drum <NUM> is intermittently provided at regular intervals in the circumferential direction R of the second drum <NUM>. In general, each area α1, α2 is formed in a concave drum surface. The concave surface, a basic construction and a detailed construction of a drum are well known, and they are disclosed in <CIT>, <CIT>, and <CIT>, for example.

As shown in <FIG>, the second area α2 is provided so as to be embraced in the first area α1. For example, in the present embodiment, the intermittently-provided second area α2 is smaller in the circumferential direction R and the width direction D than the continuously-provided first area α1, and is provided so as to be embraced. In the second drum <NUM> of <FIG>, an area in the outer circumferential portion <NUM> other than the second area a2 is an inhibition area a4, where the stacking of the fiber F is inhibited.

Note that the first area α1 may be in hourglass shape in planar developed view and may be non-continuous.

In the first area α1 of <FIG>, a thin portion C1 of <FIG> is formed. In the second area a2 of <FIG>, a thick portion C2 of <FIG> is formed.

The first and second duct portions <NUM>, <NUM> of <FIG> are connected to the case <NUM> of the feed device <NUM>, and guide the fiber F from the feed device <NUM> to the outer circumferential portion <NUM> of the first drum <NUM> and the outer circumferential portion <NUM> of the second drum <NUM>, respectively. A part of the outer circumferential portion <NUM>, <NUM> of each of the first and second drums <NUM>, <NUM> faces the end of the respective first and second duct portions <NUM>, <NUM>.

At least a part of the suction section T1 of each drum <NUM>, <NUM> faces an end opening of the respective duct portions <NUM>, <NUM>. Note that a dome 31D, 32D extending along a drum may be formed at the end of each duct portion.

The thick portion C2 is more bulky and thicker than the thin portion C1. Such thickness deference between the thin portion C1 and the thick portion C2 is gained by differentiating negative pressure amount in the chambers, or differentiating the suction periods, for example.

The first drum <NUM> and the second drum <NUM> contact with each other at a hand-over point P via the thick portion C2 therebetween. At the point P, the first drum <NUM> is set in the suction section T1, whereas the second drum <NUM> is set in the non-suction section T2.

Note that the first drum <NUM> and the second drum <NUM> may be so close to each other that the second drum <NUM> can pass the thick portion C2 to the first drum <NUM> without contacting with each other via the thick portion C2.

At the downstream of the first drum <NUM>, a first conveying portion <NUM> is provided. The first conveying portion <NUM> conveys a first web W1 (a carrier web) for conveying the absorbent core C formed by the thin portion C1 and the thick portion C2. At the further downstream of the first conveying portion <NUM>, a second conveying portion <NUM> is provided. The second conveying portion <NUM> conveys a second web W2 that is used for sandwiching the absorbent core C in between the first web W1 and the second web W2. Note that the first conveying portion <NUM> conveys the first web W1 along the first drum <NUM> so as to sandwich the absorbent core C in between the first web W1 and the first drum <NUM>.

Each conveying portion <NUM>, <NUM> may include guide rollers, unwinding rollers for web, and anvil rolls that convey and cut the absorbent core C sandwiched in between a pair of webs. Note that a web may have water absorbency and water permeability.

The hand-over point P described above is provided between the first duct portion <NUM> and the second duct portion <NUM>. At the point P, the first drum <NUM> and the second drum <NUM> contact with each other via the thick portion C2 therebetween, and the thick portion C2 stacked on the second area a2 is handed over from the second drum <NUM> to an area in the first drum <NUM>, wherein the thin portion C1 is not formed in the area.

Next, a method for manufacturing the absorbent core C will be described.

First, when the second drum <NUM> faces the second duct portion <NUM> in the suction section T1, the fiber F produced by the feed device <NUM> is clung to and stacked on the second area a2 to form the thick portion C2. The thick portion C2 is conveyed to the hand-over point P while being sucked on the outer circumferential portion <NUM> of the second drum <NUM> at regular intervals.

At the hand-over point P, the thick portion C2 is transferred from the second drum <NUM> to the first area α1 of the first drum1. That is, at the point P, the second drum <NUM> is set in the non-suction section T2, whereas the first drum <NUM> is set in the suction section T1.

Thus, the thick portion C2 on the second drum <NUM> is placed on the first area α1 of the first drum <NUM>.

Note that, in the present embodiment, the thick portion C2 is sucked and placed on (transferred to) the first area α1 in a state where the fiber F is not stacked on the first area α1.

A part of the first drum <NUM>, having received the thick portion C2, rotates in the circumferential direction R and faces the first duct portion <NUM>. There the fiber F produced by the feed device <NUM> is clung to and stacked on the first area α1, thereby producing the continuous thin portion C1 around the thick portion C2. At this stacking, the fiber F may be slightly stacked on the thick portion C2 in the first area α1.

Note that, in the present embodiment, the absorbent core C, in which the thin portion C1 is continuous along the outer circumferential portion <NUM> of the fist drum <NUM>, is formed in the step of forming the thin portion C1.

As a result, the absorbent core C shown in <FIG> is formed on the outer circumferential portion <NUM> of the first drum <NUM>. The formed absorbent core C passes by the dome 31D of the first duct portion <NUM>, and then transferred to the first web W1 guided by the first conveying portion <NUM> in the non-suction section, and conveyed.

Thereafter, the absorbent core C is sandwiched in between the first web W1 and the second web W2 conveyed by the second conveying portion <NUM>. The sandwiched absorbent core C is cut in an individual wearable article unit.

Note that, as shown in <FIG>, the absorbent core C is formed so that the surface of the thick portion C2 protrudes more than the surface of the thin portion C1.

The embodiment <NUM> will be mainly described for different part from the embodiment <NUM>.

In the present embodiment, an inhibition area α3 is provided in the first drum <NUM> in addition to the first area α1. In the inhibition area a3, the stacking of the fiber F is inhibited (prevented). For weakening negative pressure suction, the mesh porosity in the outer circumferential portion <NUM> in the inhibition area a3 may be set to be small. The first drum <NUM> and the second drum <NUM> contact with each other at the hand-over point P as follows.

The both drums contact at the point P so that the thick portion C2 stacked on the second drum <NUM> is passed (handed over) from the second drum <NUM> to the inhibition area α3 of the first drum <NUM>. The hand-over is performed in a state where the fiber F is clung to and stacked on the first area α1, except the inhibition area a3, of the first drum <NUM> while the fiber F is not stacked on the inhibition area a3, where stacking of the fiber F is inhibited.

Next, a method for manufacturing an absorbent core C will be described.

First, the thin portion C1 is formed on the first drum <NUM> in an area other than the inhibition area a3, where stacking of the fiber F is inhibited. The thin portion C1 has a smaller grammage (thinner thickness) than the thick portion C2. At the forming the thin portion C1, the fiber F may not be stacked on the inhibition area a3.

On the other hand, the thick portion C2 is formed on the second drum <NUM> by stacking the fiber F fed from the feed device <NUM> on the second area a2. The thick portion C2 is formed on the second drum <NUM> so as to coincide with the inhibition area a3 of the first drum <NUM> in planar shape.

Thereafter, at the hand-over point P, the thick portion C2 on the second drum <NUM> is transferred to the inhibition area a3 of the first drum <NUM>, and the thick portion C2 fits into the thin portion C1. As a result, the continuous absorbent core C of <FIG> is produced, being sandwiched in between a pair of the webs W1, W2 as similar to the aforementioned embodiment <NUM>.

Although the preferred embodiments have been described above with reference to the drawings, a person skilled in the art would easily arrive at various changes and modifications within an obvious range through this specification.

For example, each duct portion <NUM>, <NUM> is connected to different defibrating machines.

Also, the absorbent core C is formed on the drum in an intermittent manner in the circumferential direction R.

Therefore, such changes and modifications are interpreted to be within the scope of the present invention determined from claims.

Claim 1:
A method for manufacturing an absorbent core (C) of a disposable wearable article,
wherein the method uses a feed device (<NUM>), a first drum (<NUM>), and a second drum (<NUM>),
the feed device (<NUM>) feeds crushed fiber (F),
the first drum (<NUM>) is provided with a first area (α1), where the crushed fiber (F) is sucked and made to cling to an outer circumferential portion (<NUM>) of the first drum (<NUM>) and stacked, and
the second drum (<NUM>) is provided with a second area (α2), where the crushed fiber (F) is sucked and made to cling to an outer circumferential portion (<NUM>) of the second drum (<NUM>) and stacked, the second area (α2) being smaller than the first area (α1),
the first area (α1) of the first drum (<NUM>) is continuously provided in the circumferential direction (R) of the first drum (<NUM>), and the second area (α2) of the second drum (<NUM>) is intermittently provided at regular intervals in the circumferential direction (R) of the second drum (<NUM>); wherein the method comprises:
a step of forming a thick portion (C2) on the second area (α2) of the second drum (<NUM>) by stacking the fiber (F) fed from the feed device (<NUM>);
a step of transferring the thick portion (C2) to a predetermined position in the first area (α1); and
a step of forming a thin portion (C1) on the first area (α1) of the first drum (<NUM>) by stacking the fiber (F) fed from the feed device (<NUM>) around the transferred thick portion (C2) with the transferred thick portion (C2) placed on the first area (α1).