Apparatus for producing composite sheet

The present invention relates to an apparatus for manufacturing a composite sheet, which is composed of two sheet-like objects, and one sheet-like object forms a large number of convex portions. The present invention also relates to a method for manufacturing a composite sheet using this manufacturing apparatus.

A spunbonded non-woven fabric is point-bonded to at least one side of an elastic material to form a composite non-woven fabric, and the composite non-woven fabric is pulled in a predetermined direction to apply a load, and then the load is removed to cause the spunbonded non-woven fabric to sag. A bulky composite non-woven fabric is known (see Patent Document 1). This composite non-woven fabric is used as a side belt for pants-type diapers. As a method for obtaining a composite sheet having a large number of convex portions, in addition to the method described in Patent Document 1, the methods described in Patent Documents 2 and 3 are also known.

However, since the nonwoven fabric described in Patent Document 1 causes slack by utilizing the plastic deformation of the spunbonded nonwoven fabric, fluffing of fibers occurs in the slack portion. Therefore, when such a non-woven fabric is used as the surface sheet of the absorbent article, the fluffy fibers irritate the skin and the wearing feeling of the absorbent article is deteriorated. Since this non-woven fabric is not designed as a surface sheet of an absorbent article in the first place, even if it is used as a surface sheet of an absorbent article, a sufficient liquid leakage prevention effect cannot be expected. In particular, it cannot be expected to prevent leakage of loose stools and menstrual blood, which are highly viscous liquids.

Further, since the slack in the non-woven fabric is caused by the plastic deformation of the spunbonded non-woven fabric, it is not easy to always generate the slack with a constant size and good reproducibility.

<patcit num="1"><text>Japanese Unexamined Patent Publication No. 5-59655</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 10-245757</text></patcit><patcit num="3"><text>Japanese Unexamined Patent Publication No. 2-18036</text></patcit>

<p> Therefore, an object of the present invention is to provide a composite sheet manufacturing apparatus that eliminates the above-mentioned drawbacks in manufacturing the conventional composite sheet.</p>

<p> In the present invention, the first and second sheet-like objects are partially joined to form a large number of joints, and the first sheet-like object protrudes in a portion other than the joint portion. It is a manufacturing apparatus for a composite sheet having a large number of convex portions having a hollow inside, and the manufacturing apparatus includes a first roll having an uneven peripheral surface and the first roll. A second roll having a concavo-convex shape and a meshing concavo-convex shape on the peripheral surface is provided, and at least the first roll so as to alternately form concavo-convex portions along the rotation direction of the roll. In addition, a plurality of gears are attached to a rotating shaft to form a roll, and gaps having a predetermined width are formed between the gears at a predetermined number of gears, and the gaps are used to rotate the roll. The above object is achieved by providing an apparatus for manufacturing a composite sheet that communicates with a suction path formed in a first roll so as to extend in the axial direction.</p><p> Further, the present invention is a method for manufacturing a composite sheet using the manufacturing apparatus, wherein the first sheet-like material is bitten into the meshing portion between the first roll and the second roll, and the sheet-like material is engaged. The first sheet-like material is held in the state of being unevenly shaped on the peripheral surface of the roll by suction through the suction path formed in the first roll. Provided is a method for producing a composite sheet in which objects are superposed and a second sheet-like object is joined to a first sheet located on a convex portion in a first roll.</p>

<p> According to the manufacturing apparatus of the present invention, it is possible to easily manufacture a composite sheet having convex portions having a desired pitch and size, particularly convex portions having a small pitch. It is also easy to reliably form a large number of small protrusions. In addition, the convex portion can be formed with a constant size and good reproducibility. Furthermore, the pitch and size of the convex portion can be freely changed by a simple operation of changing the combination and width of the gears. The composite sheet produced by the manufacturing apparatus of the present invention is particularly preferably used as a surface sheet for an absorbent article. When used as a surface sheet, the sheet has excellent liquid leakage prevention properties and also has high concealing properties for absorbed liquids.</p>

Hereinafter, the present invention will be described based on the preferred embodiment with reference to the drawings. First, an example of a composite sheet manufactured by using the manufacturing apparatus of the present invention will be described. FIG. 1 shows an enlarged view of a main part of an example of a composite sheet manufactured by using the manufacturing apparatus of the present invention. The composite sheet produced according to the present embodiment is suitably used as the surface sheet 1 arranged on the skin contact surface of an absorbent article such as a sanitary napkin or a disposable diaper. The surface sheet 1 shown in FIG. 1 is composed of two sheet-like objects. The surface sheet 1 has an upper layer 2 as a first sheet-like object facing the wearer's skin side and a lower layer 3 as a second sheet-like object arranged on the absorber side. The upper layer 2 and the lower layer 3 are typically composed of various non-woven fabrics and films. Examples of the non-woven fabric include non-woven fabrics manufactured by the card method, spunbonded non-woven fabrics, melt-blown non-woven fabrics, spunlaced non-woven fabrics, needle punched non-woven fabrics and the like. When a film is used, it is preferable to perforate the film and provide a large number of holes so that the liquid can permeate.

The upper layer 2 and the lower layer 3 are partially joined at a large number of joints 4. The upper layer 2 projects toward the wearer's skin side at a portion other than the joint portion 4 and forms a convex portion 5. The inside of the convex portion 5 is hollow.

In the present embodiment, the bottom surface of the convex portion 5 is rectangular. The convex portion 5 is a flat rectangular parallelepiped or a quadrangular pyramid with a rounded ridge as a whole. On the other hand, the joint 4 is also rectangular.

The protrusions 5 and the joints 4 are arranged alternately and in a row in one direction. In this embodiment, as shown in FIG. 1, convex portions 5 and joint portions 4 are alternately arranged along the X direction in the figure to form a row. This direction coincides with the flow direction in the manufacturing process of the surface sheet 1 and coincides with the longitudinal direction of the absorbent article when the surface sheet 1 is incorporated into the absorbent article or a direction orthogonal to the longitudinal direction thereof. The rows consisting of the convex portions 5 and the joint portions 4 are arranged in multiple rows in the Y direction in FIG.

In the surface sheet 1, when focusing on any one convex portion in one row, in the left and right rows adjacent to the row, the convex portion is not located at a position adjacent to the one convex portion. .. "The convex part is not located at the position adjacent to one convex part" means that the convex part is not located at the exact same position in the adjacent row when focusing on one convex part. Means. That is, it means that the convex portions are not arranged so that the convex portions between the adjacent rows are completely connected with respect to the Y direction in FIG. Therefore, at a position adjacent to one convex portion, both a part of the convex portion and a part of the joint portion may be present, or only the joint portion may be present. If the convex portions are arranged so as to be completely continuous with respect to the Y direction, an apparently long convex portion extending in the Y direction is formed, and in that case, the liquid flows out along the long extending convex portion. It becomes easy and causes liquid leakage.

In the present embodiment, the joints are arranged at intervals of half a pitch in two adjacent rows. Therefore, when focusing on any one joint in one row, the one joint is a closed recess formed by being surrounded by convex portions in the front-rear and left-right directions. That is, the joints are arranged in a houndstooth pattern. Therefore, the convex portions are also arranged in a houndstooth pattern.

By arranging the convex portion 5 and the joint portion 4 in this way, liquid leakage is extremely effectively prevented in the absorbent article provided with the surface sheet 1. Specifically, when the surface sheet 1 is used as, for example, a disposable diaper, particularly a surface sheet for a diaper for a young child who excretes loose stool, which is a highly viscous excrement, the following effects are exhibited. Since loose stool has a high viscosity, it is generally difficult for the surface sheet to permeate quickly, and it tends to stay on the surface sheet and cause a cross flow. On the other hand, according to the surface sheet of the present embodiment, the loose stool is trapped in the closed recess formed by being surrounded by the convex portion 5, so that the lateral flow is less likely to occur and the loose stool is captured. As a result, downward movement (that is, toward the absorber) is promoted. As a result, leakage of loose stool is prevented. Further, since the convex portion 5 has a hollow inside, it also has a concealing effect that the color of loose stool absorbed by the absorber is attenuated when viewed from the surface sheet side. These effects are similarly exhibited when the surface sheet 1 of the present embodiment is used as the surface sheet of a sanitary napkin for absorbing menstrual blood, which is a highly viscous excrement similar to loose stool.

The manufacturing method of the surface sheet 1 will be described with reference to the manufacturing apparatus shown in FIGS. 2 to 5. As shown in FIG. 2, in the manufacturing apparatus of the present embodiment, the first roll 11 having a concavo-convex peripheral surface and the concavo-convex shape that meshes with the concavo-convex shape of the first roll 11 are rotated. It has a second roll 12 on the surface and an anvil roll 14. The first roll 11 and the second roll 12 are arranged so that the uneven portions on the peripheral surfaces of the respective rolls mesh with each other. Further, the first roll 11 and the anvil roll 14 are arranged so that the top of the convex portion of the peripheral surface of the first roll 11 is in contact with the peripheral surface of the anvil roll 14.

FIG. 3 shows a perspective view of a main part of the first roll 11, and FIG. 4 shows an exploded perspective view of a part thereof. The first roll 11 is formed by combining a plurality of first gears 11a and second gears 11b made of spur gears of the same module and concentrically attaching these gears to the rotating shaft 15 to form a roll. is there. Each of the gears 11a and 11b has the same tooth width. The center of each of the gears 11a and 11b is open, and the rotating shaft 15 is inserted into the opening. A notch (not shown) is formed in each of the gears 11a and 11b and the rotating shaft 15, and a key (not shown) is inserted into the notch. This prevents idling of the gears 11a and 11b.

The first gear 11a and the second gear 11b have the same diameter of the tip circle. The number of teeth of the first gear 11a is an integral multiple of the number of teeth of the second gear 11b. Specifically, the number of teeth of the second gear 11b used in the present embodiment is 7, while the number of teeth of the first gear 11a is 21, which is an integral multiple of the number of teeth.

In the first roll 11, one first gear 11a is arranged on each side of one second gear 11b, and a group of gears in which these three gears are paired. There are multiple 16 sets. In each gear group 16, the first gear 11a and the second gear 11b are arranged so that the teeth of the gears 11a and 11b are parallel to each other in the rotation axis direction of the roll. As a result, in each gear group 16, convex portions 17 and concave portions 18 are alternately formed along the rotation direction of the roll 11. Does the convex portion 17 have teeth of each of the three gears (that is, two first gears 11a and one second gear 11b) formed in parallel in the rotation axis direction of the roll 11? (Indicated by reference numeral 17a in FIG. 3), or the teeth of the two first gears 11a are formed in parallel in the direction of the rotation axis of the roll (indicated by reference numeral 17b in FIG. 3). On the other hand, the recess 18 is formed between the teeth of the two first gears 11a. The width of the convex portion 17 determines the dimension of the convex portion 5 of the surface sheet 1 in the Y direction.

Two or more sets of gear groups 16 are used. The gear groups 16 are arranged so that the pitches of the uneven portions of the adjacent gear groups 16 and 16 are different from each other. In the present embodiment, the uneven portions of the adjacent gear groups 16 and 16 are deviated by half a pitch.

In each gear group 16, a plurality of gap portions 19 are formed between the two first gears 11a at regular intervals along the rotation direction of the roll 11. Each gap 19 is formed by two first gears 11a and a second gear 11b located between them. More specifically, each gap 19 is defined by two opposing sides of the first gear 11a and two adjacent teeth on the second gear 11b. Therefore, the number of gaps 19 is formed to be the same as the number of teeth of the second gear 11b. The gap 19 is open to the outside in the recess 18 described above.

The first gear 11a is formed with a plurality of openings 20 so as to surround the central opening into which the rotating shaft 15 is inserted. Each opening 20 has the same diameter and is formed at a position equidistant from the center of the gear. The angles formed by the adjacent openings 20 and 20 and the center of the gear are the same. The number of openings 20 in each gear 11a is the same as the number of teeth in the second gear 11b. When assembling each gear group 16, the first and second gears 11a and 11b are arranged so that each opening 20 is located between adjacent teeth in the second gear 11b. When the gear groups 16 are assembled in this way and the gear groups 16 are arranged so that the pitches of the uneven portions are different from each other, the openings 20 of the first gears 11a are in the rotation axis direction of the roll 11. A plurality of suction paths 21 extending in the direction of the rotation axis are formed inside the roll 11. Then, each suction path 21 communicates with the gap portion 19 described above.

At least one end of the suction path 21 leads to a suction source (not shown) such as a blower or a vacuum pump. Therefore, when the suction source is operated to perform the suction operation, air is sucked from the gap 19 through the suction path 21.

A method for manufacturing a composite sheet using a manufacturing apparatus having the above configuration will be described. First, as shown in FIG. 2, the upper layer 2 is drawn out from the original fabric 2'of the upper layer 2. The lower layer 3 is drawn out from the original fabric 3'of another lower layer 3. The fed upper layer 2 is engaged with the meshing portion between the first roll 11 and the second roll 12 to form the upper layer 2 with unevenness. In this case, the first roll 11 is sucked as described above. The suction is controlled so as to be performed from the meshing portion between the first roll 11 and the second roll 12 to the confluence portion between the upper layer 2 and the lower layer 3. Therefore, the upper layer 2 formed by the meshing of the first roll 11 and the second roll 12 has the roll as shown in FIG. 5 by the attractive force of the gap portion 19 formed in the first roll 11. It adheres to the peripheral surface of the surface, and the uneven shape is maintained. If suction is not performed, the upper layer 2 will be lifted from the peripheral surface of the first roll 11, and as a result, a sheet having a desired uneven shape cannot be obtained.

Next, under the state where the upper layer 2 is continuously brought into close contact with the peripheral surface of the first roll 11 (see FIG. 5), as shown in FIG. Is sandwiched between the first roll 11 and the anvil roll 14. At this time, both the first roll 11 and the anvil roll 14 or only the anvil roll 14 are heated to a predetermined temperature. As a result, the upper layer 2 located on the convex portion of the first roll 11, that is, above the teeth of each gear, is joined to the lower layer 3 by heat fusion.

Instead of bonding the upper layer 2 and the lower layer 3 by heat fusion, these layers may be bonded by bonding with an adhesive or ultrasonic bonding.

By the above method, the surface sheet 1 shown in FIG. 1 can be obtained. The manufacturing apparatus of the present embodiment has an advantage that the convex portions can be formed at a desired pitch and at a constant size with good reproducibility, unlike the technique described in Patent Document 1 described in the section of the prior art. Further, since the peripheral surface shape of the uneven roll to be used is not impaired by providing the gap portion 19 between the gears, there is an advantage that a large number of small convex portions can be reliably formed particularly at a small pitch. Furthermore, the pitch and size of the convex portion can be freely changed by a simple operation of changing the combination and width of the gears. It is advantageous to be able to form a large number of small convex portions having a small pitch from the viewpoint of obtaining a surface sheet having a good touch, a high cushioning feeling, and a good visual impression.

The surface sheet 1 thus obtained is used for absorbent articles such as disposable diapers, sanitary napkins, and incontinence pads. The absorbent article is generally configured to have a liquid-permeable front sheet, a liquid-impermeable back sheet, and a liquid-retaining absorber interspersed between the two sheets. Further, the obtained sheet can be used for applications other than the front surface sheet of the absorbent article, for example, the back sheet of the absorbent article, the base sheet of the fastening tape in a disposable diaper provided with the fastening tape, and the landing tape to which the fastening tape is engaged. It can also be used as a base sheet for a wing, a panel material for a loop member of a mechanical fastener, a cleaning sheet, a cleaning sheet, and the like in a sanitary napkin provided with a wing.

The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the gear groups 16 in the first roll 11 are arranged so that the pitches of the uneven portions in the gear group are shifted by half pitches from each other, but are arranged at pitches other than half pitches. May be good. Alternatively, in the first roll 11, the teeth of the first gear 11a and the second gear 11b are parallel to the rotation axis direction of the roll, and the uneven portions along the rotation direction of the roll alternate and the entire width direction of the roll. It may be continuously formed over. In this case, a composite sheet in which convex portions and concave portions extending in the same direction are alternately formed can be obtained.

Further, in the above-described embodiment, a set of gear groups is composed of two first gears 11a and one second gear 11b located between them, but the configuration of the gear group is Not limited to this, at least one first gear 11a can be arranged on at least one side of at least one second gear 11b, and a set of gears can be formed by this.

Further, in the above-described embodiment, the gap portion 19 is formed by interposing the second gear 11b between the two first gears 11a, but the method for forming the gap portion is not limited to this. For example, a gap portion may be formed by using a gear having a shape in which the second gear 11b is integrated with the first gear 11a.

Further, in the above-described embodiment, the structure of the first roll 11 has been described, but the second roll 12 may also have the same structure as the first roll 11. Of course, as long as it has a shape that meshes with the first roll 11, it may have a structure different from that of the roll 11. However, in any case, the suction operation is not performed on the second roll 12.

Further, in the above-described embodiment, the first gear 11a and the second gear 11b are configured to have the same tooth width, but may have different tooth widths. Further, the tooth width of the gear in one gear group may be different from the tooth width of the gear in the other gear group.

Further, in the above-described embodiment, the first gear 11a and the second gear 11b have the same tooth tip circle diameter, but the tooth tip circle diameter of the second gear 11b is that of the first gear 11a. May be smaller than.

Further, in the above embodiment, the number of teeth of the first gear 11a is an integral multiple of the number of teeth of the second gear 11b, but it does not necessarily have to be an integral multiple.

<figref num="1">It is a perspective view which shows the main part of an example of the composite sheet manufactured by using the manufacturing apparatus of this invention in an enlarged manner.</figref><figref num="2">It is a schematic diagram which shows one Embodiment of the manufacturing apparatus of this invention.</figref><figref num="3">It is a perspective view which shows the main part of the 1st roll in FIG.</figref><figref num="4">It is an exploded perspective view of a part of the roll shown in FIG.</figref><figref num="5">It is a figure which shows the state which the 1st sheet-like object is held in the 1st roll while the uneven shape is formed.</figref>

Code description

1 Surface sheet (composite sheet) 2 Upper layer (1st sheet-like material) 3 Lower layer (2nd sheet-like material) 4 Joint 5 Convex part 11 1st roll 11a 1st gear 11b 2nd gear 12th Roll of 2 15 Rotating shaft 16 Gear group 17 Convex 18 Concave 19 Void 20 Opening 21 Suction path