JP4070661B2 - Absorber manufacturing method - Google Patents

Description

【００５３】
表１に示す結果から、実施例においては、得られた吸収体に、吸収容量を他の部位よりも高めた部位が十分に形成されており、該部位の吸収性能が十分に発揮されることが判る。これに対して、比較例の吸収体は、前側が高坪量にならなかったり（比較例１）、パルプ／ポリマー重量比が前後で大きく異なったりして、所望の前漏れ防止性能が発揮されなかった。
また、実施例で得られた吸収体を用いることにより、高吸水性ポリマーの使用量を抑えつつ、使い捨ておむつの漏れ防止性を向上させることができることが判る。
【００５４】
【発明の効果】
本発明の吸収体の製造方法によれば、吸収容量を部分的に高く設計した部位を有し、該部位の吸収性能を十分に発現させることのできる吸収性能に優れた吸収体を、効率的且つ経済的に製造することができる。
【図面の簡単な説明】
【図１】図１は、本発明で製造される吸収体の例を、使い捨ておむつの一部として用いた状態を示す平面図であり、使い捨ておむつを表面シート側から見た状態を示す一部破断図である。
【図２】図２は、図１の吸収体を単独で示す図で、図２(a)は平面図、図２(b)は図２(a)のＸ−Ｘ線断面を模式的に示す断面図である。
【図３】図３は、本発明の実施に好ましく用いられる吸収体の製造装置を示す概略図である。
【図４】図４は、集積用凹部並びに第１及び第２吸引領域の配置の一例を示す図で、図４(a)は集積用凹部の俯瞰図、図４(b)は図４(a)のＹ−Ｙ線断面を模式的に示す断面図である。
【図５】図５は、第１及び第２吸引領域の他の配置を示す図である。
【符号の説明】
１ 使い捨ておむつ
２ 表面シート
３ 裏面シート
４ 吸収体
５ 回転（積繊）ドラム
５０ 集積用凹部
５１ 第１吸引領域
５２ 第２吸引領域
５３ 第１吸引領域と第２吸引領域の境界部[0001]
BACKGROUND OF THE INVENTION
The present invention has an area where the absorption capacity is designed to be partially high, and an absorber excellent in absorption performance capable of sufficiently expressing the absorption performance of the area is manufactured efficiently and economically. The present invention relates to a method for producing an absorbent body.
[0002]
[Prior art and problems to be solved by the invention]
Generally, the absorbent capacity of an absorbent article is designed according to its application. For example, disposable diapers are intended for a wide range of users, from newborns to adults who need nursing care, and it is necessary to design an absorption capacity for each of them.
[0003]
For example, since most of the excrement is soft stool, it can be designed to enhance the fecal absorption performance from the central part of the diaper longitudinal direction to the rear part (back side) in order to deal with soft stool. In addition, for infants and adults, in order to cope with a large amount of urination, the urine absorption performance from the central part in the longitudinal direction to the front part (abdominal side) may be designed. In the former case, since it is for a newborn, there is not much leakage even if the overall absorption capacity is not designed to be too high. On the other hand, in the latter case, since the amount of urination is the center and the amount is large, it is necessary to increase the absorption capacity from the central part in the longitudinal direction of the diaper to the front part. As described above, there are known methods in which a polymer is pattern-dispersed or an absorber structure in which only the front is stacked in two layers.
[0004]
However, when a pattern of highly water-absorbing polymer is sprayed, equipment for pattern spraying is required, and an apparatus for accurately aligning the spray pattern with the sheet base material to be sprayed is necessary. There is a problem that the position of the spray pattern is difficult to detect on the production line. In some cases, polymer leakage from a polymer-rich site or gel blocking may occur, and the expected absorption capacity may not be exhibited.
As an absorber in which only the front is stacked in two layers, an absorber in which a separately manufactured upper-layer absorber is laminated on a part of a lower-layer absorber or a part of an absorber composed of a single layer is folded back into two layers. The former is known, but the former requires, for example, a plurality of fiber stacking devices in order to produce two types of absorbers, and the latter requires a folding device, etc. In any of the absorbers, manufacturing facilities are complicated, and it is impossible to provide an inexpensive and high-performance absorber. Furthermore, if the polymer in the upper absorber absorbs and swells and gel blocking occurs, the liquid may not smoothly move to the lower absorber, resulting in absorption of polymers, pulp fibers, etc. in the forward direction. Absorption performance commensurate with the amount of the functional material cannot be obtained, which may cause leakage in some cases. In addition, in the case of an absorbent body in which only the front is stacked in two layers, there may be a feeling of strangeness when worn due to a difference in rigidity at the boundary with the rear single layer structure.
[0005]
As a manufacturing method in which a predetermined portion has a high basis weight, Japanese Patent Application Laid-Open No. 62-206071 (Patent Document 1) provides a concave portion having a specific shape in a part of a flat plate on which a fiber material is deposited. A technique in which the lower part of the recess is devised so that a high pressure is applied is disclosed. However, this publication only describes the deposition of the fiber material, and does not consider a mixed system of superabsorbent polymer and pulp. In addition, in this method, since a concave portion having an inclined portion that does not have an opening is provided in a portion having a high basis weight, no direct suction force is generated at the portion, and the flat portion and the concave portion of the plate It is likely to be a physically discontinuous sediment structure. In addition, since the airflow is disturbed in the inclined portion, the mixing ratio is disturbed in the mixed system of the superabsorbent polymer and the pulp, and the desired absorption performance cannot be obtained.
[0006]
Japanese Patent Laid-Open No. 2000-234255 (Patent Document 2) provides a plurality of suction regions having different aperture ratios on the bottom surface of the concave portion for accumulation, and sucks and deposits raw materials in these suction regions to obtain height and density. A method for producing a fiber molded body having different regions is described. However, this publication does not specifically describe the case where it is produced with a mixed system of a superabsorbent polymer and pulp fiber, and also provides a step in the recess to control the height and density. There is no description of the control. In addition, the absorber may be broken by the stepped portion when the absorber is transported.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 62-206071 [Patent Document 2]
Japanese Patent Laid-Open No. 2000-234255
Therefore, an object of the present invention is to provide an absorbent body having a portion designed to have a partly high absorption capacity, and capable of fully expressing the absorption performance of the portion, with simple equipment and efficiently. Another object of the present invention is to provide a method for producing an absorbent body that can be produced economically.
[0009]
[Means for Solving the Problems]
The present invention supplies the superabsorbent polymer and the pulp fiber in a scattered state, and sucks and deposits it in the concave portion for accumulation having a large number of suction holes on the bottom surface, and deposits of the superabsorbent polymer and the pulp fiber. A method of manufacturing an absorbent body, wherein the absorbent body is manufactured by releasing from the concave portion for accumulation, wherein a first suction region having a higher opening area ratio and an opening than the first suction region are formed in a bottom surface portion of the concave portion for accumulation. A second suction area having a low area ratio is provided, the opening area ratio R1 of the first suction area is 40 to 80%, the opening area ratio R2 of the second suction area is 2 to 20%, and the ratio of both opening area ratios (Rl / By providing a method for producing an absorbent body, wherein R2) is in the range of 70/30 to 99/1, and the superabsorbent polymer and the pulp fiber are deposited in both suction regions. Is achieved.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on preferred embodiments thereof.
First, the preferable example of the absorber manufactured by the manufacturing method of the absorber of this invention is demonstrated. The absorbent body 4 shown in FIGS. 1 and 2 is an absorbent body for the disposable diaper 1. The disposable diaper 1 includes a liquid-permeable top sheet 2, a liquid-impermeable back sheet 3, and a liquid-retaining absorbent 4 interposed between both sheets 2 and 3, and is formed substantially vertically long. From one end in the longitudinal direction toward the other end, a back side portion A disposed on the wearer's back side when worn, a crotch portion B disposed on the crotch, and a ventral side portion C disposed on the abdomen side In order. The disposable diaper 1 is a so-called unfolded disposable diaper, and has fastening tapes 11 for fastening diapers on the left and right side edges of the back side A, and the corresponding landing tape 12 is attached to the outside of the abdominal side C. Has on the surface.
[0011]
The absorbent body 4 is composed of a superabsorbent polymer and pulp fibers, and each of the superabsorbent polymer and the pulp fibers has a high basis weight region 41 in which the basis weight is higher than the low basis weight region 42 which is another part. is doing. In addition, the expression containing a superabsorbent polymer and pulp fiber includes both the case where a component other than the superabsorbent polymer and pulp fiber is included and the case where a component other than the superabsorbent polymer and pulp fiber is not included. It is.
The high basis weight region 41 is formed at a position biased toward the one end 4a side of the side disposed on the abdomen side of the wearer when the diaper 1 is worn among the longitudinal ends of the absorbent body 4, and more specifically. In the diaper 1, it forms in the site | part (site ranging from the crotch part B to the abdominal side part C) facing the wearer's urination part.
[0012]
The high basis weight region 41 and the low basis weight region 42 are formed in a physically continuous integral structure. That is, both regions form a single structure, and there is no interface that connects separate absorbers between the two regions. The thickness of the absorber 4 in the high basis weight region 41 is slightly thicker than the thickness of the absorber 4 in the low basis weight region 42.
[0013]
The cross-sectional structure (cross-sectional structure in the thickness direction) of the absorber 4 across both regions 41 and 42 is a conventional two-layer absorber, that is, an absorber in which a separately manufactured upper-layer absorber is laminated on a lower-layer absorber. Or, it is different from the cross-sectional structure of the absorber in which a part of the absorber composed of a single layer is folded to form a two-layer part. Specifically, there is no discontinuity between the high basis weight region and the low basis weight region as shown in FIG.
As shown in FIG. 2B, the absorbent body 4 includes a plurality of layers each having a high basis weight region 41 and a low basis weight region 42 in the thickness direction. Specifically, each of the regions 41 and 42 includes an upper layer 41a mainly composed of pulp fibers in the thickness direction, an intermediate layer 41b mainly composed of a superabsorbent polymer, and a lower layer 41c mainly composed of pulp fibers. ing. Each of the plurality of layers 41a to 41c has an integral structure that is physically continuous over both regions.
In the prior art, there is a physical discontinuity between the high basis weight portion and the low basis weight portion. In the present invention, a major difference is that there is no physically discontinuous region between the high basis weight region and the low basis weight region.
[0014]
The absorbent body 4 has a basis weight difference between the high basis weight region 41 and the low basis weight region 42. More specifically, in the high basis weight region 41 and the low basis weight region 42, when viewed in plan, the basis weight changes abruptly at the boundary surface between the two regions, and a difference in basis weight occurs between the two regions. This is due to the fact that in both regions, the density is kept almost constant and the amount of pulp fibers and superabsorbent polymer is higher in the high basis weight region than in the low basis weight region. In order to obtain such a structure, a device on the manufacturing technique as described later is important.
[0015]
The difference in basis weight between the two regions 41 and 42 is 20 to 600 g / m ² , especially 30 to 200 g / m ² , and it is easy to obtain a rigidity difference that does not give the wearer a sense of incongruity. It is preferable because an appropriate fit property is given to a predetermined part of the wearer and an effect that it is easy to wear is obtained.
In addition, the basic weight of each area | region is measured as follows.
<Measurement method of basis weight>
Measurement pieces having the same area of 3 cm × 3 cm or more (preferably 5 cm × 5 cm or more) in plan view from each region are collected, the area and weight of each measurement piece are measured, and the basis weight (weight / area) Was calculated. Five measurement pieces are collected from both regions, preferably five from each region.
[0016]
The basis weight difference between the two areas is calculated from the average value of the basis weight of the measurement piece in the high basis weight area and the average value of the basis weight of the measurement piece in the low basis weight area.
The basis weight of both regions can be determined as appropriate according to the application of the absorbent body and is not particularly limited. However, for example, the basis weight of the high basis weight region is 200 to 400 g / m ² , and is low. The basis weight of the basis weight region is 100 to 300 g / m ² .
[0017]
In the absorbent body 4, the mixing ratio of the superabsorbent polymer and the pulp fiber is substantially the same in the high basis weight region and the low basis weight region. This is because such a configuration makes it difficult for a difference in absorption rate between the high basis weight region and the low basis weight region to occur, and also causes problems such as gel blocking on one side.
Specifically, the blending ratio (%) of each of the superabsorbent polymer and the pulp fiber in the high basis weight region 41, and the blending ratio of the superabsorbent polymer and the pulp fiber in the low basis weight region. The difference from (%) is within a range of ± 5%. The blending ratio (%) is a value indicating the blending ratio of the superabsorbent polymer or the pulp fiber as a percentage (%) with respect to the total amount of the superabsorbent polymer and the pulp fiber. For example, when the mixing ratio (the former: the latter) of the superabsorbent polymer and pulp fiber in the high basis weight region 41 is 54:46, the blending ratio of the superabsorbent polymer in the region 41 is 54%. The blending ratio of the fiber is 46%. At this time, if the blending ratio of the superabsorbent polymer in the low basis weight region 42 is 55%, the polymer blending ratio (%) in the high basis weight region 41 and the polymer blending ratio in the low basis weight region 42 The difference from the blending ratio (%) is -1% (54% -55%).
[0018]
Moreover, as for the absorber 4, the density of a high basic weight area | region and a low basic weight area | region is substantially the same. Specifically, the density ratio (high basis weight region / low basis weight region) of both regions 41 and 42 is 0.9 to 1.1. By making it within this range, it is easy to design the absorption performance in both regions, and the design is so easy that the difference in rigidity does not give a sense of incongruity between the two regions. The density of each region is measured as follows.
<Density measurement method>
When the high basis weight region and the low basis weight region have a sufficient size, each region is sampled, the volume and weight are measured, and the density is calculated.
When one of the two regions does not have a sufficient size (for example, when a plurality of high basis weight regions having a plane area of less than 1 cm ² are scattered in the low basis weight region), Dimension of 3 cm × 3 cm or more (preferably 5 cm × 5 cm or more) of any 5 parts of the above (however, the high basis weight region and the low basis weight region should be included in at least one of the parts) Collect the same area and measure the volume and weight. The density (weight / volume) is calculated for each measurement piece. In this case, if the difference in density between the measurement pieces is within ± 5%, the density of the high basis weight region and the low basis weight region is substantially the same.
[0019]
In order to make the absorbent body 4 have substantially the same density in the high basis weight region and the low basis weight region, the mixing ratio of the superabsorbent polymer and the pulp fiber is changed to both regions 41, by applying a manufacturing method as described later. 42, and a compression treatment is performed so that substantially different pressure is not applied to both regions 41 and 42 (according to the thickness difference between the high basis weight region and the low basis weight region). It is pressed with a plate having a step or the like) or is not compressed. The illustrated absorber 4 has a substantially uniform density throughout the entire area.
[0020]
The mixing ratio of the superabsorbent polymer in each of the regions 41 and 42 is measured as follows.
<Measurement method of mixing ratio of polymer and pulp fiber>
Cut out 5 points so that the high basis weight region and the low basis weight region of the absorbent body always include one point (that is, the high basis weight region and the low basis weight region are included one by one in the cut out 5 points). Cut out), the polymer and the pulp fiber are separated from each other by sieving or the like, and the respective weights of the polymer and the pulp fiber are measured. The mixing ratio is averaged for both regions. Any separation means may be used as long as the two can be almost completely separated, and various means can be used. For example, the weight before and after scattering may be measured by using a difference in particle size and sieving with a fine mesh, or by placing under an air volume such that only pulp is scattered using the difference in weight.
[0021]
When a polyacrylic acid-based polymer is used as the water-absorbing polymer, a particularly preferable method is to cause the polymer in the sample containing pulp fiber and the water-absorbing polymer to have a low molecular weight, and the low molecular weight generated by the low molecular weight. In this method, the components are separated and removed, the weight of the residue after removing the low molecular components is quantified, and the content of the fibers and the water-absorbing polymer in the sample is calculated using the quantified weight.
[0022]
Specifically, samples are taken from each of the regions 41 and 42, dried at 90 ° C. for 8 hours or more, equilibrated at room temperature, and accurately weighed.
Each sample is filled in a mesh bag, which is accurately weighed in advance, and the mesh bag is immersed in an aqueous solution containing 4% by weight ascorbic acid and 0.02% by weight riboflavin. Fully in the sample. Next, the mesh bag is taken out from the aqueous solution, and the sample is subjected to a low molecular weight treatment with sunlight (ultraviolet rays) for 8 hours × 3 days. To do. When the color of the polymer colored by riboflavin has not disappeared or when the slimy feeling at the time of washing with water has not disappeared, the mesh bag is again immersed in the aqueous solution, and the low molecular weight treatment by sunlight is repeated. The processing is terminated when the color of the polymer has completely disappeared for all the samples and the slimy feeling during washing has disappeared.
[0023]
After the mesh bag is sufficiently washed with water, it is dehydrated by centrifugation for 10 minutes at a speed of 800 rpm with a centrifuge. Next, after drying at 90 ° C. for 18 hours or more and equilibrating at room temperature, the weight of the mesh bag containing the residue is weighed (hereinafter, this weight is also referred to as post-treatment weight).
And the value obtained by subtracting the weight of the mesh bag from the weight after the treatment is the pulp fiber content in the sample, and the value obtained by subtracting the weight of the pulp fiber from the sample weight measured in advance is the content of the water-absorbing polymer. And
[0024]
The absorbent body 4 having the above configuration has a high water absorption capacity by providing a high basis weight region 41 in a portion where a high absorption capacity is required and providing a low basis weight region 42 in a portion where the required absorption capacity is relatively low. Absorbent materials such as water-soluble polymers and pulp fibers, and the absorption capacity realized by them can be effectively utilized in the most effective manner. And the high basic weight area | region 41 aiming at the high absorption capacity | capacitance is formed from the single structure which has not laminated | stacked absorbers (namely, the basic structure is the same as the absorber structure of a low basic weight area | region, Therefore, the absorption performance in the region can be efficiently expressed. That is, in the conventional two-layer structure in which another absorber structure is loaded on the absorber structure of the low-absorption capacity portion, the superabsorbent polymer swells greatly in contact with excrement in the upper-layer absorber. Then, although the excrement may be prevented from smoothly transferring to the lower-layer absorber (gel blocking), the high basis weight region 41 is formed from a single structure like the absorber 4 having the above configuration. In this case, excreta is easily introduced in the entire thickness direction, and even the polymer existing below is effectively used.
Moreover, since the high basic weight area | region 41 and the low basic weight area | region (other parts) are formed in the physically continuous integral structure, unlike the absorber of the conventional 2 layer structure, the high basic weight area | region 41 Since a large difference in rigidity is unlikely to occur between the low basis weight region 42 and the low basis weight region 42, the wearer is less likely to feel uncomfortable when used in an absorbent article such as a diaper.
[0025]
Further, since the mixing ratio of the superabsorbent polymer and the pulp fiber is substantially the same in both regions, not only can the density be made uniform, but also the design of the absorption performance on the absorbent body becomes very easy. This is because even if the density is the same, if the mixing ratio of the superabsorbent polymer and the pulp fiber is different, the absorption rate and absorption capacity of the absorbent body may be locally undesirable, As a result, various problems such as urine leakage and polymer leakage may be induced.
[0026]
Next, one preferable embodiment of the manufacturing method of the absorber of the present invention will be described. The absorbent body manufacturing apparatus shown in FIG. 3 is an absorbent body manufacturing apparatus preferably used for carrying out the present invention. In the present embodiment, the absorber 4 having the above configuration is manufactured using the apparatus shown in FIG.
The absorbent body manufacturing apparatus shown in FIG. 3 includes a rotating drum (stacking drum) 5 having a plurality of concave portions for accumulation 50 having a plurality of suction holes on the bottom surface on the outer peripheral surface, and the outer peripheral surface of the rotating drum 5. And a raw material supply means 6 for scattering and supplying the absorber raw material, the raw material is sucked and deposited in the respective accumulation recesses 50, and the deposits of the raw materials are sequentially released from the respective accumulation recesses 50. Thus, the absorber 4 is continuously manufactured.
[0027]
The rotating drum 5 has a plurality of accumulation recesses 50 at predetermined intervals on the outer peripheral surface thereof, and the ring-shaped portion having the accumulation recesses 50 rotates in the direction of arrow A in FIG. ing. The interior of the rotary drum 5 is partitioned into a plurality of chambers that can be adjusted to different pressures, and each chamber located behind the portions 54, 55, and 56 where the raw material is deposited in the accumulation recess 50 is maintained at a negative pressure. The Further, the other part of the chamber is set to a positive pressure, and the deposit of the raw material in the accumulation concave portion 50 is discharged from the accumulation concave portion 50 at the positive pressure portion. When the negative pressures on the back sides of the parts 54 to 56 are the same, a common room can be provided on the back sides of the parts 54 to 56.
[0028]
The raw material supply means 6 is configured to supply a superabsorbent polymer and pulp fibers as a raw material for manufacturing the absorber 4 in a scattered state to the outer peripheral surface of the rotary drum 50. Specifically, the first and second pulp fiber supply devices 61 and 62 supply pulp fibers, respectively, and the polymer supply device 63 supplies a superabsorbent polymer. Both pulp fiber supply devices 61 and 62 respectively pulverize the sheet-like raw material pulp by a known mechanism, and cause the generated pulp fibers to follow the air flow generated in the duct 64 on the outer peripheral surface of the rotary drum 5. Supply. The polymer supply device 63 introduces a superabsorbent polymer into the air flow by a known mechanism and supplies it to the outer peripheral surface of the rotary drum 5.
The superabsorbent polymer and pulp fiber supplied from the raw material supply means 6 are sucked and deposited in the respective accumulation recesses 50 by the action of the negative pressure of the rotary drum 5 and conveyed to a predetermined portion, and then each accumulation recess. From 50, the mold is released on the conveyor belt 7 sequentially.
[0030]
As shown in FIG. 4, a first suction region 51 having a high opening area ratio and a second suction region 52 having a lower opening area ratio than the first suction area 51 are provided on the bottom surface of each accumulation recess 50. Yes. The first suction region 51 and the second suction region 52 correspond to the high basis weight region 41 and the low basis weight region 42 of the absorbent body 4 described above, respectively.
In the present invention, it is not necessary to provide a step as thickness adjusting means at the boundary between the suction region 51 and the second suction region 52. The step as the thickness adjusting means is a step for forming a thick part and a thin part in the absorber. A step that does not affect the thickness of the absorber is not a step as thickness adjusting means.
[0031]
In the present invention, the ratio (R1 / R2) between the opening area ratio R1 of the first suction region 51 and the opening area ratio R2 of the second suction region 52 is set in the range of 70/30 to 99/1.
If the ratio (R1 / R2) of the opening area ratio of both the regions 51 and 52 is less than 70/30, the difference in the opening area ratio is too small, and a high basis weight region and a low basis weight region are not formed (that is, Not only does the difference in basis weight hardly occur), but also in a certain range, the pulp / polymer mixing ratio may not be uniform (the certain ratio is that the ratio (R1 / R2) is 70). / 30 or less and a ratio area excluding the vicinity of 50/50).
On the other hand, if the ratio (R1 / R2) of the opening area ratio is more than 99/1, the opening area ratio R2 of the second absorption region 52 becomes too low, and the pulp / polymer mixture is laminated in the second suction region. In particular, a heavy polymer tends to concentrate on the first suction region, and the pulp / polymer ratio is extremely unevenly distributed.
[0032]
From the viewpoint that the pulp / polymer mixing ratio can be kept uniform with high probability, the ratio of the opening area ratio (R1 / R2) of the first and second suction regions is more preferably 75/25 to 95/5. .
[0033]
In the present invention, the opening area ratio R1 of the first suction region 51 is set to 40 to 80%, and the opening area ratio R2 of the second suction region 52 is set to 2 to 20%.
When the opening area ratio R1 of the first suction region is less than 40%, a desired air volume is not generated, the polymer is stalled, and the polymer is not sufficiently mixed with the pulp. On the other hand, if it exceeds 80%, the air volume becomes excessive, and the accumulation recesses are likely to be clogged with pulp / polymer.
When the opening area ratio R2 of the second suction region is less than 2%, stable fiber stacking of the absorber is impaired, and shape defects, breakage, and turning are likely to occur. If it exceeds 30%, a low basis weight region is not formed.
[0034]
Further, for the purpose of obtaining an absorbent body having a uniform pulp / polymer mixing ratio and an excellent shape retention, the opening area ratio R1 of the first suction region is preferably 45 to 58%, and the pulp / polymer mixing ratio is uniform. The opening area ratio R2 of the second suction region is preferably 3 to 18% from the viewpoint that it is easy to make uniform even if the amount of the polymer is increased.
[0035]
Here, the opening area ratio R of each suction region is defined by assuming that the area of each suction region (including the area of the suction holes) is S1, and the total opening area of the suction holes existing in each suction region is S2. It is a value given by the following equation (1).
Opening area ratio R = (S2 / S1) × 100 (1)
[0036]
As a method of making the opening area ratios different between the first suction area 51 and the second suction area 52, (1) the suction holes have the same size (diameter, etc.), but the suction holes have different pitches. (2) The suction hole pitch is the same in both areas, but the suction hole size (diameter, etc.) is different. (3) The suction hole pitch and size are different in both areas. The method to make is mentioned. In the embodiment described later, the method (1) is used.
The average diameter of the suction holes is preferably in the range of 0.05 to 0.5 mm in both the regions 51 and 52, and the diameters of all the suction holes are substantially in the above range. preferable. The suction hole is preferably a perfect circle, but the diameter in the case of an ellipse is calculated from the opening area assuming a perfect circle.
In the illustrated apparatus, the bottom surface of the accumulation recess is made of punching metal provided with a number of circular suction holes by punching, and the shape connecting the center points of adjacent suction holes is a triangular shape.
[0037]
In order to manufacture the absorber using the above-described manufacturing apparatus, the rotary drum 5 is rotated at a constant speed in the direction of arrow A, and is positioned behind the portions 54, 55, and 56 where the raw material is deposited in the accumulation recess 50. Each chamber in the rotary drum 5 is set to a negative pressure, and a suction force is applied to each suction hole. Thereby, an air flow capable of conveying the raw material in a scattered state is provided in the duct 64 of the raw material supply means 6. Cause it to occur.
When the raw materials are introduced into the duct 64 by the raw material supply means 6, they are scattered and supplied toward the rotating drum 5. Then, they are sucked and deposited in each accumulation recess 50. Incidentally, the dispersion of the superabsorbent polymer and the pulp fiber in a mixed state means that at least a part is mixed in the scattered state, and in this embodiment, the super absorbent polymer and the pulp fiber are supplied from the respective supply ports. The pulp and polymer are each scattered and at least partially mixed to move toward the accumulation recess and accumulate.
[0038]
When sucking and depositing the superabsorbent polymer and the pulp fiber in the collecting recess 50, the first and second suction regions 51 and 52 are exposed to the atmospheric pressure from the back side of the bottom surface of the collecting recess 50. Applying a vacuum pressure reduced by 1 to 20 kPa, particularly a vacuum pressure reduced by 5 to 15 kPa, makes the basis weight of both regions different while keeping the pulp / polymer mixing ratio substantially constant (the pulp / polymer is unevenly distributed). And it is difficult to form a physically discontinuous boundary between the two regions.
As a method of applying the vacuum pressure in the above range, a method in which the vacuum pressure in the chamber on the back side of the portion 54 where the pulp fiber from the first pulp fiber supply device 61 is deposited is within the above range, a portion where the superabsorbent polymer is deposited. 55, the method of setting the vacuum pressure of the room on the back side of the above-mentioned range, and the method of setting the vacuum pressure of the room on the back side of the portion 56 where the pulp fibers from the second pulp fiber supply device 62 are deposited are in the above range. It is preferable that the vacuum pressure in the chamber on the back side of all the portions 54 to 56 where the water-absorbing polymer and / or the pulp fibers are sucked and deposited is within the above range. In the method of setting the pressure in the chamber on the back side of the portion 54 on which the pulp fiber from the first pulp fiber supply device 61 is deposited in the above range, the applied pressure is set because the absorbent component is not deposited in the accumulation recess 50. It is preferable because it can be measured accurately.
[0039]
In the present embodiment, the pulp fibers, the superabsorbent polymer, and the pulp fibers are generally deposited in this order in each accumulation recess 50, and a certain shape is given to the deposit. Then, the deposit in the accumulation recess 50 is sequentially released under the rotary drum 5. By continuously rotating the rotating drum 5 and repeating the suction deposition of the raw material and the release of the deposit, the absorber 4 is efficiently and continuously produced.
[0040]
According to the manufacturing method of the absorbent body of the present embodiment, the absorbent body as described above, that is, an absorption having a part designed to have a partially high absorption capacity and capable of sufficiently expressing the absorbent performance of the part. Thus, the absorber excellent in performance can be manufactured efficiently and economically with simple equipment.
[0041]
As the superabsorbent polymer, various known polymers can be used without particular limitation. For example, sodium polyacrylate, (acrylic acid-vinyl alcohol) copolymer, sodium polyacrylate cross-linked product, (starch- Acrylic acid) graft copolymers, (isobutylene-maleic anhydride) copolymers and saponified products thereof, polyaspartic acid, and the like. In addition to the superabsorbent polymer and pulp fiber, the absorbent material is made of rayon fiber, hydrophilic fiber such as cotton and cellulose acetate, polyolefin fiber such as polyethylene and polypropylene, condensed fiber such as polyester and polyamide, chloride Fibers of vinyl monomer polymers such as vinyl and vinyl acetate may be used. In addition, the absorber may be covered with a cover sheet made of a mount or a liquid-permeable nonwoven fabric.
[0042]
When using other fibers in addition to pulp fibers as the raw material of the absorbent, the ratio of the water-absorbing polymer and the polymer to the total weight of the total fibers (% by weight) and the ratio of the total weight of the total fibers to the total weight (% by weight ) Is preferably within a range of ± 5% between the high basis weight region and the low basis weight region. The total content of the water-absorbing polymer and pulp fiber in the absorbent body is preferably 70 to 100%, particularly preferably 80 to 100%.
[0043]
In the above-described embodiment, the absorbent body for the deployable disposable diaper has been described as an example. However, the absorbent body manufactured in the present invention is a pants-type disposable diaper, a sanitary napkin, an incontinence pad, a panty liner, and the like. The absorbent body used in the absorbent article may be used as an absorbent body in drip sheets, kitchen absorbent sheets, household cleaning sheets, pet sheets and the like.
Moreover, the manufacturing apparatus of an absorber can replace with what comprises two pulp fiber supply apparatuses, and can also use what supplies a pulp fiber in a duct from one place with a single pulp fiber supply apparatus.
[0044]
[Example 1]
(1) Production of Absorber An absorbent body having the form shown in FIG. 2 was produced using a superabsorbent polymer and pulp fibers as raw materials and using an absorbent production apparatus having the structure shown in FIG.
The shape of the concave portion for accumulation and the arrangement of the first and second suction areas are the same as those shown in FIG. 4A. The opening area ratio of the first suction area 51 is 56%, and the second suction area 52 The opening area ratio was 5%. The diameter of the suction holes is distributed within a range of 0.1 to 0.3 mm in both the regions 51 and 52, and the average diameter of the suction holes is 0.2 mm in both the regions 51 and 52. Met. In addition, the pressure of each room located in the back side of the site | parts 54-56 in FIG. 3 was made into the vacuum pressure which pressure-reduced 8-11 kPa with respect to atmospheric pressure, and this pressure was made to act on a 1st and 2nd suction area | region.
The area of each suction region was as shown in Table 1. In Table 1, “abdominal side” and “back side” correspond to the first suction region and the second suction region, respectively. The pulp fiber amount and superabsorbent polymer amount per absorber were 14 g and 12 g in this order. As the superabsorbent polymer, a polyacrylic acid-based polymer was used.
[0045]
[Examples 2 and 3]
An absorbent body was manufactured in the same manner as in Example 1 except that the opening area ratio of the second suction region 52 was changed to 10% or 18%.
[0046]
[Comparative Example 1]
An absorbent body was manufactured in the same manner as in Example 1 except that the opening area ratio of the first suction region 51 was changed to 50% and the opening area ratio of the second suction region 52 was changed to 25%. However, the amount of water-absorbing polymer per absorber was 14 g.
[0047]
[Comparative Example 2]
An absorbent body was manufactured in the same manner as in Example 1 except that the opening area ratio of the bottom surface portion of the accumulation recess was 40% over the entire bottom surface portion.
[0048]
Example 4
An absorbent body was manufactured in the same manner as in Example 2 except that the arrangement of the first and second suction regions was changed to the arrangement shown in FIG. In Table 1, “T region” and “Y region” correspond to the first suction region and the second suction region, respectively.
[0049]
(2) About the absorber obtained by the absorber Example and the comparative example, the site | part (high basic weight area | region 41, "abdominal side" in Table 1, or "T area | region") corresponding to the 1st suction area | region, and 2nd suction | inhalation Table 1 shows the measured or calculated basis weights of pulp fibers and polymers in the region corresponding to the region (low basis weight region 42, “abdominal side” or “Y region” in Table 1).
[0050]
(3) Evaluation of absorbent body Disposable diapers were manufactured using the absorbent bodies obtained in the examples and comparative examples. The configuration of the disposable diaper was the same as that of a commercially available disposable diaper manufactured by Kao Corporation (trade name “Merry's Pants Lean Smart”) except that the absorbent bodies obtained in Examples and Comparative Examples were used. The absorber was arrange | positioned so that a high basic weight area | region may be located in the belly side of a diaper.
About the obtained disposable diaper, in order to evaluate the difficulty of leaking, the forward value was measured as follows. The results are shown in Table 1.
[0051]
[Measurement method of the previous value]
Put a pants-type diaper manufactured using each absorber on a human body model that has a model urination part on the front side, and put the physiological saline at a rate of 10 g / sec from the model urination part with the front side on the floor (collapsed). Inject into diapers. Every time 50 g was flown, the operation of passing again for 10 seconds and reflowing was repeated, and the weight until leakage from the front side (waist opening) was measured.
[0052]
[Table 1]

[0053]
From the results shown in Table 1, in the examples, in the obtained absorbent body, a portion having a higher absorption capacity than other portions is sufficiently formed, and the absorption performance of the portion is sufficiently exhibited. I understand. On the other hand, the absorbent body of the comparative example does not have a high basis weight on the front side (Comparative Example 1), and the pulp / polymer weight ratio is greatly different between before and after, and the desired pre-leakage prevention performance is exhibited. There wasn't.
Moreover, it turns out that the leakage prevention property of a disposable diaper can be improved by suppressing the usage-amount of a superabsorbent polymer by using the absorber obtained in the Example.
[0054]
【The invention's effect】
According to the method for producing an absorbent body of the present invention, an absorbent body having a portion designed to have a partly high absorption capacity and capable of sufficiently expressing the absorbent performance of the portion is efficiently produced. And it can be manufactured economically.
[Brief description of the drawings]
FIG. 1 is a plan view showing a state in which an example of an absorbent body manufactured according to the present invention is used as a part of a disposable diaper, and a part showing a state when the disposable diaper is viewed from a top sheet side. FIG.
2 is a diagram showing the absorber of FIG. 1 alone, FIG. 2 (a) is a plan view, and FIG. 2 (b) is a schematic cross-sectional view taken along line XX of FIG. 2 (a). It is sectional drawing shown.
FIG. 3 is a schematic view showing an absorbent body production apparatus preferably used in the practice of the present invention.
4 is a diagram showing an example of the arrangement of the stacking recesses and the first and second suction regions, FIG. 4A is an overhead view of the stacking recesses, and FIG. It is sectional drawing which shows the YY line cross section of a) typically.
FIG. 5 is a diagram showing another arrangement of the first and second suction regions.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Disposable diaper 2 Top sheet 3 Back sheet 4 Absorber 5 Rotation (stacking) drum 50 Concave part 51 1st suction area 52 2nd suction area 53 Boundary part of 1st suction area and 2nd suction area

Claims (5)

Supplying the superabsorbent polymer and pulp fiber in a scattered state, sucking and depositing the superabsorbent polymer and the pulp fiber in the stacking recess having a large number of suction holes on the bottom surface, It is a manufacturing method of an absorber which molds from the inside and manufactures an absorber,
A first suction region having a high opening area ratio and a second suction region having a lower opening area ratio than the first suction area are provided on the bottom surface of the accumulation recess, and an opening area ratio R1 of the first suction region is set to 40 to 80. %, The opening area ratio R2 of the second suction area is 2 to 20%, and the ratio (Rl / R2) of both opening area ratios is in the range of 70/30 to 99/1 . An absorber having the same pressure reduced by 1 to 20 kPa with respect to atmospheric pressure from the back side of the bottom surface of the recess, and depositing the superabsorbent polymer and the pulp fiber in both suction regions Manufacturing method.   The manufacturing method of the absorber of Claim 1 which does not provide the level | step difference as a thickness adjustment means in the boundary part of a 1st suction area | region and a 2nd suction area | region. The method for producing an absorbent body according to claim 1 or 2 , wherein the superabsorbent polymer and the pulp fiber are scattered in a mixed state. The first suction area and the second suction area have the same size of the suction holes, but the opening area ratios are made different from each other by changing the pitch of the suction holes. The manufacturing method of the absorber in any one. The first suction region and the second suction region have the same pitch of the suction holes, but have different opening area ratios by making the sizes of the suction holes different from each other. The manufacturing method of the absorber in any one.

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