JP7513826B2 - Absorbent body and its manufacturing equipment - Google Patents

Description

The present invention relates to a manufacturing method and manufacturing apparatus for absorbent bodies for various absorbent articles, including disposable diapers and sanitary napkins. The present invention also relates to absorbent bodies.

Various absorbent articles, including disposable diapers and sanitary napkins, generally have an absorbent body capable of absorbing and retaining liquid. The absorbent body generally contains hydrophilic fibers such as pulp and particles of water-absorbing polymer. The manufacture of absorbent bodies made of these materials generally involves a step of spraying water-absorbing polymer particles. The spraying step of water-absorbing polymer particles is broadly divided into continuous spraying and intermittent spraying. For example, Patent Document 1 describes a method of manufacturing a sheet-shaped absorbent body by intermittently spraying water-absorbing polymer particles between two sheets of material. In this document, a part of the continuously sprayed particles is removed to the outside using an excluding means, so that the particles are sprayed intermittently. The document describes that the particles are discharged by a high-pressure air flow from a high-pressure air injection device. The particles discharged to the outside are then collected and supplied again to the particle spraying step.

International Publication No. 2014/104115

According to the technology described in Patent Document 1, the particles that have been removed to the outside are collected and resupplied using an excluding means, resulting in a good yield. However, when the particles are removed to the outside, an external force may be applied to the particles, causing them to be crushed and atomized. If the atomized particles are resupplied, the resupplied particles are removed again and repeatedly subjected to an external force, which further promotes the atomization of the particles and gradually reduces the average particle size. A smaller particle size may lead to a decrease in absorption performance, such as liquid retention and absorption capacity. Resupplying particles with such reduced absorption performance is one of the factors that hinder the stable production of absorbents with the desired absorption performance.

In addition, the technology described in Patent Document 1 involves intermittent dispersion of particles while allowing them to fall freely. Therefore, if a high-pressure air flow is used to remove the particles, the high-pressure air flow may disrupt the free-falling state of the particles, hindering the stable supply of particles.

Therefore, the objective of the present invention is to reliably consume the removed and recovered water-absorbent polymer particles in the manufacturing method of the absorbent body, thereby suppressing the progression of atomization.

Another object of the present invention is to stably cause the powder to fall continuously while periodically and reliably removing the powder that falls continuously during the manufacturing process of an article that contains powder.

The present invention provides a method for producing an absorbent body by carrying out a manufacturing process of a first absorbent core containing a first water-absorbing polymer and a manufacturing process of a second absorbent core containing a second water-absorbing polymer in parallel, and laminating the first absorbent core and the second absorbent core obtained thereby, in which the manufacturing process of the first absorbent core includes a continuous supplying process of the first water-absorbing polymer, and the manufacturing process of the second absorbent core includes a process of intermittently supplying the second water-absorbing polymer to a base sheet by continuously supplying the second water-absorbing polymer while periodically removing the continuously supplied second water-absorbing polymer midway through the supply, and the second water-absorbing polymer removed in the manufacturing process of the second absorbent core is recovered and transported to the continuous supplying process in the manufacturing process of the first absorbent core.

The present invention also provides an apparatus for manufacturing an absorbent body including a first absorbent core including a first water-absorbent polymer and a second absorbent core including a second water-absorbent polymer, the apparatus comprising:
a first water-absorbent polymer supply section that supplies a first water-absorbent polymer to the first absorbent core;
a second absorbent polymer supply section for supplying a second absorbent polymer to the second absorbent core;
a recovery means for periodically recovering the removed second water-absorbing polymer;
A re-supply means for conveying the second water-absorbing polymer recovered by the recovery means to the first water-absorbing polymer supply section;
The present invention provides an apparatus for manufacturing an absorbent body having the above structure.

The present invention further provides an absorbent body including a first absorbent core containing a first water-absorbent polymer and a second absorbent core containing a second water-absorbent polymer laminated together,
the second absorbent core has a portion along the longitudinal direction in which the abundance ratio of the second water-absorbent polymer is lower than that of the surrounding area;
At least a portion of the first water-absorbing polymer is composed of a water-absorbing polymer of the same quality as the second water-absorbing polymer;
The first water-absorbing polymer has an average particle size smaller than the average particle size of the second water-absorbing polymer to provide an absorbent body.

According to the present invention, the particles of the water-absorbent polymer that are rejected and collected during the manufacturing process of the absorbent body are reliably consumed, so that the progress of atomization of the particles is effectively suppressed.
In particular, according to the present invention, during the manufacturing process of the absorbent body, the powder falling continuously can be removed periodically and reliably, while the powder can be caused to fall continuously and stably.

FIG. 1 is a schematic perspective view of an example of an absorbent body produced by the production method of the present invention. FIG. 2 is a cross-sectional view showing a schematic cross section taken along line II of FIG. Figure 3(a) is a diagram showing an example of a pattern of the joint between the core wrap sheet and the second core in the absorbent body of the present invention, and Figure 3(b) is a diagram explaining the positional relationship between the area in which the second absorbent polymer is present in the second absorbent core and the first absorbent core. FIG. 4 is a schematic diagram showing an overall configuration of a production apparatus that can be used to carry out the production method of the present invention. FIG. 5 is a diagram illustrating the recovery process of the second water-absorbing polymer and the transport process to the first core manufacturing process. FIG. 6 is a diagram showing an example of the configuration of the scattering means. FIG. 7 is a plan view showing a schematic example of an adhesive application pattern on a core wrap sheet. FIG. 8 is a plan view that shows a schematic state immediately before two base sheets are superimposed on each other below the spreading means in the second core manufacturing section. FIG. 9 is a plan view showing an example of a spray pattern in which the water-absorbent polymer is intermittently sprayed onto the base sheet in the second core manufacturing section. FIG. 10 is a graph showing the relationship between polymer particle size and water retention under pressure. FIG. 11 is a schematic cross-sectional view showing a measuring device for measuring the water retention amount under pressure of a polymer particle diameter. FIG. 12 is a schematic overall view (corresponding to FIG. 4) of another production apparatus that can be used to carry out the production method of the present invention. FIG. 13 is a diagram (corresponding to FIG. 5) for explaining the recovery step of the second water-absorbing polymer and the transport step to the first core manufacturing step. FIG. 14 is a diagram (corresponding to FIG. 6) showing another example of the configuration of the dispersing means. Figure 15(a) shows the test results of inspecting the non-sprayed width of the second absorbent polymer when suction is on, and Figure 15(b) shows the test results of inspecting the non-sprayed width of the second absorbent polymer when suction is off. FIG. 16 is a block diagram illustrating the schematic configuration of a control system of the manufacturing apparatus. FIG. 17 is a diagram for explaining the configuration of the main parts of still another manufacturing apparatus that can be used to carry out the manufacturing method of the present invention.

The present invention will now be described based on preferred embodiments thereof with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. The drawings are essentially schematic, and the ratios of the dimensions may differ from the actual ones.

1 and 2 show an absorbent body 1, which is an example of an absorbent body that is the object of the manufacturing method of the present invention. FIG. 4 shows an outline of a manufacturing method of the absorbent body 1, which is an example of the manufacturing method of the present invention, and a manufacturing apparatus 10, which is an embodiment of a manufacturing apparatus that can be used to carry out the manufacturing method. The absorbent body 1 is used to absorb and retain bodily fluids such as urine, feces, menstrual blood, and sweat in an absorbent article (not shown) having a longitudinal direction X corresponding to the front-to-rear direction of the wearer and a transverse direction Y perpendicular thereto. The absorbent body 1 has an absorbent core 2 containing a water-absorbent material, and a liquid-permeable core wrap sheet 5 that covers the outer surface of the absorbent core 2.

As shown in FIG. 1, the absorbent body 1 and the absorbent core 2 that constitutes it are elongated in the vertical direction X, with the longitudinal direction of both coinciding with the vertical direction X and the width direction of both (the direction perpendicular to the longitudinal direction) coinciding with the horizontal direction Y. The vertical direction X also coincides with the conveying direction (hereinafter also referred to as "MD", an abbreviation for Machine Direction) during the manufacture of the absorbent body 1, and the horizontal direction Y coincides with the conveying cross direction (hereinafter also referred to as "CD", an abbreviation for Cross Machine Direction) that is perpendicular to the MD.

The absorbent core 2 has a first absorbent core 3 made of at least absorbent polymer and fibrous material, and a second absorbent core 4 that is in contact with the skin-facing surface 3a or the non-skin-facing surface 3b of the first absorbent core 3 and is thinner than the first absorbent core 3. In this specification, the "skin-facing surface" refers to the surface of the absorbent or its constituent members (e.g., the first absorbent core 3, the second absorbent core 4) that faces the skin of the user when in use (when the absorbent article in which the absorbent is incorporated is worn), i.e., the side that is relatively closer to the user's skin, and the "non-skin-facing surface" refers to the surface of the absorbent or its constituent members that faces the opposite side from the skin when in use, i.e., the side that is relatively farther from the user's skin.

In this embodiment, as shown in Figures 1 and 2, the second absorbent core 4 is in contact with the non-skin facing surface 3b of the first absorbent core 3. In this embodiment, the first absorbent core 3 is disposed closer to the skin of the user than the second absorbent core 4, and therefore the first absorbent core 3 comes into contact with the body fluid to be absorbed by the absorbent body 1 before the second absorbent core 4 does.

In this embodiment, the core wrap sheet 5 is a single sheet. The core wrap sheet 5 covers the entire skin-facing surfaces of the absorbent core 2 (the skin-facing surface 3a of the first absorbent core 3 and the skin-facing surface 4a of the second absorbent core 4), and extends outward in the horizontal direction Y from both side edges of the absorbent core 2 along the vertical direction X. The extended portions are wrapped around the non-skin-facing surface of the absorbent core 2, covering the entire non-skin-facing surface of the absorbent core 2 (the non-skin-facing surface 4b of the second absorbent core 4).
As shown in Fig. 2, an overlapping portion is formed at the center in the horizontal direction Y of the non-skin facing surface of the absorbent core 2, where both side edges (tips of the extended portions) of the core wrap sheet 5 along the vertical direction X overlap each other. The core wrap sheet 5 may be a liquid permeable sheet, such as paper or nonwoven fabric. The core wrap sheet 5 and the second absorbent core 4 are directly joined by a joint 6 without the first absorbent core 3 being interposed therebetween.

The first absorbent core 3 is disposed between the core wrap sheet 5 and the second absorbent core 4. The first absorbent core 3 is shorter in at least one of the length in the longitudinal direction X and the length in the lateral direction Y than the second absorbent core 4, and the first absorbent core 3 is not disposed on the peripheral portion of the surface of the second absorbent core 4 on which the first absorbent core 3 is disposed (the skin-facing surface 4a in the illustrated embodiment), and the second absorbent core 4 is exposed in a portion where the first absorbent core 3 is not disposed.
1, in this embodiment, the first absorbent core 3 is shorter than the second absorbent core 4 in both the length in the longitudinal direction X and the length in the lateral direction Y, and the entire periphery (contour line) of the first absorbent core 3 is located inward from the periphery (contour line) of the second absorbent core 4. Therefore, the periphery (non-placement portion of the first absorbent core 3) of the skin-facing surface 4a (placement surface of the first absorbent core 3) of the second absorbent core 4 is covered with the core wrap sheet 5 and is in a state where it can come into contact with the core wrap sheet 5.

1, the first absorbent core 3 has a length (width) in the horizontal direction Y that is not constant over the entire length in the vertical direction X, and one end side in the vertical direction X has a longer length in the horizontal direction Y and is wider than the other end side. The absorbent body 1 is usually arranged in an absorbent article such that, of both end sides in the vertical direction X of the first absorbent core 3, this relatively wider end side in the vertical direction is located on the abdominal side (front side) of the wearer of the absorbent article.
As shown in FIG. 2, the first absorbent core 3 contains a water-absorbent polymer and a fibrous material 3F. The fibrous material 3F is preferably a water-absorbent fiber. Examples of the water-absorbent fiber include natural fibers such as wood pulp, such as softwood pulp and hardwood pulp, and non-wood pulp, such as cotton pulp and hemp pulp; modified pulp, such as cationic pulp and mercerized pulp (all of which are cellulosic fibers); and hydrophilic synthetic fibers, and one of these may be used alone or two or more may be mixed together. The first absorbent core 3 typically contains cellulosic fibers as the fibrous material 3F. The first absorbent core 3 contains, as the water-absorbent polymer, a first water-absorbent polymer 3P and a recovered second water-absorbent polymer 4P, which will be described below.
As will be apparent from the manufacturing method described later, at least a portion of the first water-absorbent polymer 3P contained in the first absorbent core 3 is composed of a water-absorbent polymer of the same quality as the second water-absorbent polymer.

In this embodiment, the first absorbent polymer 3P contained in the first absorbent core 3 is generally particulate, but may be fibrous. The shape of the particulate first absorbent polymer 3P is not particularly limited, and may be, for example, spherical, blocky, bale-shaped, or irregular. The first absorbent polymer 3P is typically mainly composed of a polymer or copolymer of acrylic acid or an alkali metal salt of acrylic acid.

The first absorbent core 3 has a portion along the longitudinal direction X where the content ratio of the first water-absorbing polymer 3P is lower than that of the surrounding area. As shown in Figs. 1 and 2, the portion includes a form in which the core-forming material of the first absorbent core 3 is not present over the entire thickness direction of the first absorbent core 3. Therefore, in the following description, the portion is referred to as a forming material absent portion 3N. In the illustrated form, the forming material absent portion 3N is formed symmetrically with respect to a virtual line (not shown) that divides the first absorbent core 3 (absorbent body 1) in half in the transverse direction Y and extends in the longitudinal direction X, and a pair is formed on both sides of the virtual line. Each of the pair of forming material absent portions 3N has a long shape (specifically, a rectangular shape) in the longitudinal direction X in a plan view. The forming material absent portion 3N functions as a flow path for the body fluid to be absorbed by the absorbent body 1, promotes the diffusion of the body fluid in the planar direction, and can contribute to effective use of the absorption performance of the absorbent body 1.
In addition, the non-forming material portion 3N also functions as a deformation-inducing portion (flexible axis) when the first absorbent core 3 is deformed, such as by bending, due to external forces such as body pressure, thereby reducing the discomfort felt when wearing an absorbent article comprising the absorbent body 1 and improving the wearing comfort and fit.
Since the non-forming material portion 3N plays such a role, it is preferable that the non-forming material portion 3N is disposed in a portion of the first absorbent core 3 where bodily fluids tend to concentrate (i.e., the portion that is likely to receive bodily fluids first) and where the non-forming material portion 3N is likely to receive external forces such as body pressure. From this viewpoint, the non-forming material portion 3N is preferably disposed in a portion that corresponds to the crotch area of the wearer when the absorbent article in which the absorbent body 1 is incorporated is worn, specifically, at least in the center of the first absorbent core 3 in the longitudinal direction X.

The non-existent forming material portion 3N is a portion formed by intentionally impeding the stacking of the core-forming material, which includes the fiber material 3F and the first absorbent polymer 3P, during the stacking process during the production of the first absorbent core 3.
In this embodiment, as shown in Fig. 2, the core wrap sheet 5 and the second absorbent core 4 (more specifically, the base sheet 4S described below) are joined in the forming material absent portion 3N. With this configuration, the shape retention of the first absorbent core 3 is improved, and the shape of the first absorbent core 3 is less likely to collapse before and after absorbing body fluids, thereby further improving the absorption performance of the absorbent body 1.

As shown in FIG. 2, the second absorbent core 4 includes two opposing base sheets 4S and a second absorbent polymer 4P disposed between the two base sheets 4S, and the two base sheets 4S are bonded to each other with an adhesive. The adhesive used in the second absorbent core 4 is applied in a predetermined pattern to the opposing surfaces (the surfaces on which the second absorbent polymer 4P is disposed) of the two base sheets 4S, as described below. The adhesive used in the second absorbent core 4 can be any adhesive that is used to bond components in absorbent articles, without any particular restrictions, and can be, for example, a hot melt adhesive.

The base sheet 4S may be a sheet-like material capable of fixing the second water-absorbing polymer 4P, and may be liquid-permeable or liquid-impermeable. Examples of the base sheet 4S include fiber structures such as nonwoven fabric, woven fabric, knitted fabric, and paper, as well as resin films, foams, and nets. These may be used alone or in combination of two or more.
The base sheet 4S is typically composed of a nonwoven fabric. As the nonwoven fabric constituting the base sheet 4S, fabrics produced by various manufacturing methods can be used without particular limitation, and examples thereof include air-through nonwoven fabric, heat-rolled nonwoven fabric, spunlace nonwoven fabric, spunbonded nonwoven fabric, meltblown nonwoven fabric, and spunbonded-meltblown-spunbonded (SMS) nonwoven fabric. These nonwoven fabrics may be hydrophilic nonwoven fabrics made of fibers that have been subjected to a hydrophilization treatment.
The two base sheets 4S may be the same or different. In the latter case, for example, one of the two base sheets 4S that is relatively closer to the skin of the wearer of the absorbent article (closer to the first absorbent core 3 in this embodiment) is liquid permeable, and the other that is farther from the skin of the wearer (first absorbent core 3) is liquid impermeable. From the viewpoint of the balance between the thinning of the absorbent body and sufficient strength for practical use, the basis weight of one base sheet 4S is preferably 5 g/m ² or more, more preferably 7 g/m ² or more, and preferably 50 g/m ² or less, more preferably 40 g/m ² or less.
In the first absorbent core 3 and the second absorbent core 4, the distribution form of the first absorbent polymer 3P and the second absorbent polymer 4P is not particularly limited, and they may be distributed uniformly throughout the core, or may be unevenly distributed in only a part of the core. However, the former is preferred from the viewpoint of improving various performance properties such as liquid absorbency and flexibility.

As shown in Fig. 3(a), the core wrap sheet 5 and the second absorbent core 4 are directly joined by a joint 6 without the first absorbent core 3 being interposed. In this embodiment, the first absorbent polymer 3P is the same as the second absorbent polymer 4P, but the first absorbent polymer 3P has an average particle size smaller than that of the second absorbent polymer 4P. In this specification, the average particle size of the absorbent polymer refers to the median diameter. The median diameter is measured, for example, by a laser diffraction type dry particle size distribution measuring device.
In this embodiment, as shown in Fig. 3(b), the length L2 of the region in which the second absorbent polymer 4P is present in the second absorbent core 4 is greater than the length L1 in the longitudinal direction X of the first absorbent core 3. Therefore, even if the small-diameter first absorbent polymer 3P separates from the first absorbent core 3, it is received by the second absorbent core 4, which is preferable because it prevents the first absorbent polymer 3P from falling off the absorbent core 2.
In addition, since the length L2 of the area in which the second absorbent polymer 4P is present is greater than the length L1 of the first absorbent core 3 in the longitudinal direction X, this is preferable because it allows the second absorbent core 4 to reliably absorb body fluids that leak from the first absorbent core 3.

The absorbent body 1 is used as an absorbent body for an absorbent article. The term "absorbent article" as used herein broadly includes articles used to absorb body fluids discharged from the human body (urine, loose stools, menstrual blood, sweat, etc.), such as disposable diapers, sanitary napkins, sanitary shorts, incontinence pads, etc.
An absorbent article typically comprises an absorbent body, a liquid-permeable top sheet arranged closer to the wearer's skin than the absorbent body, and a liquid-impermeable or impermeable back sheet arranged farther from the wearer's skin than the absorbent body.

Next, a method for manufacturing the absorbent body of the present invention will be described with reference to the drawings, taking the above-mentioned method for manufacturing the absorbent body 1 as an example.
4 is an overall schematic diagram of a manufacturing apparatus 10 which is one embodiment of a manufacturing apparatus that can be used to implement the manufacturing method of the absorbent body 1. The manufacturing apparatus 10 is configured to include a first absorbent core manufacturing section (hereinafter referred to as the "first core manufacturing section") 20 which manufactures the first absorbent core 3, a first conveying section 30 which receives and conveys the first absorbent core 3 manufactured in the first core manufacturing section 20, a second absorbent core manufacturing section (hereinafter referred to as the "second core manufacturing section") 40 which manufactures the second absorbent core 4, and a second conveying section 50 which receives and conveys the second absorbent core 4 manufactured in the second core manufacturing section 40.
In the following, the conveying direction (flow direction) of the core wrap sheet 5 (absorbent body 1) will be referred to as MD1, the conveying direction (flow direction) of the base sheet 4S (4S1, 4S2) will be referred to as MD2, MD3, and the conveying direction (flow direction) of the second absorbent core 4 will be referred to as MD4.

In the manufacturing method using the manufacturing apparatus 10, the manufacturing process of the first absorbent core containing the first absorbent polymer 3P is carried out in the first core manufacturing section 20, and the manufacturing process of the second absorbent core containing the second absorbent polymer 4P is carried out in the second core manufacturing section 40. In the manufacturing method in this embodiment, the manufacturing process of the first absorbent core and the manufacturing process of the second absorbent core are carried out in parallel, and the first absorbent core 3 and the second absorbent core 4 obtained thereby are laminated.

The first core manufacturing section 20 comprises a fiber stacking drum 21 having a plurality of accumulation recesses (not shown) formed at predetermined intervals on its outer peripheral surface 21S, and a duct 22 that continuously supplies core forming material (in this embodiment, fiber material 3F and a first absorbent polymer 3P) to the outer peripheral surface of the fiber stacking drum 21 by entraining it in an air flow.
The duct 22 has an upstream end (not shown) of the air flowing therethrough that is connected to the introduction device 60 , and a downstream end that covers a portion of the outer circumferential surface 21</b>S of the fiber stacking drum 21 .
The introduction device 60 includes a fiber supply section 61 that defibrates a raw material sheet mainly composed of fibrous material 3F and supplies the fibrous material 3F into the duct 22, and a first water-absorbing polymer supply section 62 that carries out a process of continuously supplying a first water-absorbing polymer 3P into the inside of the duct 22.

The fiber stacking drum 21 is composed of a cylindrical drum main body 210 made of a rigid metal body, and an outer peripheral member 211 that is arranged on top of the outer periphery of the drum main body 210 and forms the outer peripheral surface 21S of the fiber stacking drum 21.
The outer peripheral member 211 receives power from a prime mover such as a motor and is driven to rotate in the direction of arrow R1 in Fig. 4 around a horizontal axis of rotation, while the drum body 210 is fixed and does not rotate. The inside of the drum body 210 is divided into a plurality of spaces A, B, and C in the circumferential direction. A pressure reduction mechanism (not shown) for reducing the pressure inside the drum body 210 is connected to the drum body 210, and the spaces A to C can be maintained at negative pressure by driving the pressure reduction mechanism.

In the fiber-stacking drum 21, the space A, the outer periphery of which is covered by the duct 22, is made into a fiber-stacking zone in which the core-forming material can be stacked by suction from the inside. When the outer peripheral member 211 is rotated in the direction of the arrow R1 while the space A is maintained at a negative pressure, the negative pressure in the space A acts on the bottom of the accumulation recess (not shown) formed in the outer peripheral member 211 while the accumulation recess passes over the space A, and air is sucked through a number of suction holes formed in the bottom. By suction through these suction holes, the core-forming material conveyed through the duct 22 is guided to the accumulation recess and stacked on its bottom, forming the first absorbent core 3, which is the accumulated fiber.
On the other hand, space B of the fiber stacking drum 21 is usually set to a negative pressure weaker than that of space A or zero pressure (atmospheric pressure), and space C is set to zero pressure or positive pressure since it is an area including the transfer position of the fiber stack in the stacking recess and the area before and after it. The stacking recess has a shape corresponding to the shape to be imparted to the first absorbent core 3 to be manufactured. As described above, in this embodiment, the first absorbent core 3, which is the object of manufacture in the first core manufacturing section 20, has a forming material absent portion 3N, so that the portion of the bottom of the stacking recess corresponding to the forming material absent portion 3N protrudes radially outward of the fiber stacking drum 21 compared to the peripheral portion, thereby preventing the core forming material from being stacked in that portion.

The first absorbent core 3 formed in the accumulation recess is transported to the bottom of the fiber stacking drum 21 by the rotation of the outer peripheral member 211, and is released from the accumulation recess by the air discharge device 23 and transferred to the first conveying section 30.

5, the first water-absorbent polymer supply section 62 includes a first supply tank 63 for continuously supplying the first water-absorbent polymer 3P to the duct 22, and a first storage tank 64 for storing the first water-absorbent polymer 3P to be supplied to the first supply tank 63. The first supply tank 63 is a sealed container, communicated with a part of the duct 22, and configured to be able to supply the first water-absorbent polymer 3P into the duct 22. The first supply tank 63 also functions as a relay tank for storing the second water-absorbent polymer 4P to be collected and transported to the manufacturing process of the first absorbent core.
The first water-absorbing polymer 3P stored in the first storage tank 64 is supplied to the first supply tank 63 by a first water-absorbing polymer supplying means 65 such as a screw feeder.

Returning to Figure 4, the first conveying section 30 is equipped with a conveying means 31 capable of conveying while sucking the object on the conveying surface, and the conveying means 31 is composed of an endless conveyor belt 32 that rotates in the direction of arrow R2 in Figure 4, and a suction box 33 as a suction means installed within the circular orbit of the conveyor belt 32.
The conveyor belt 32 forms a conveying surface for conveying objects and has air permeability. The conveyor belt 32 is made of, for example, a mesh belt having a large number of suction holes (not shown).
The suction box 33 is disposed at a position opposite to the air discharge device 23 across the conveyor belt 32 , and is capable of sucking in the air blown out from the air discharge device 23 .
A core wrap sheet 5 is previously supplied onto the conveyor belt 32 before the first absorbent core 3 is released from the accumulation recess and placed on the conveyor belt 32. The first absorbent core 3 released from the accumulation recess is transported to the second transport section 50 while being placed on the core wrap sheet 5.
The first transport section 30 also includes a pressing roll 36 that presses the first absorbent core 3 arranged on the core wrap sheet 5 toward the core wrap sheet 5. The first absorbent core 3 is compressed in the thickness direction by the pressing roll 36 before being supplied to the second transport section 50 (before the second absorbent core 4 is stacked thereon).

In the manufacturing apparatus 10, the core wrap sheet 5 is continuously unwound from a roll of raw material 5R in which the long core wrap sheet 5 is wound into a roll shape, and supplied onto the conveyor belt 32 of the first conveying section 30.While being supplied to the conveyor belt 32, adhesive 34A, 35A (see Figure 7) is applied by application means 34, 35 to the surface (upper surface) of the core wrap sheet 5 on the conveyor belt 32 where the first absorbent core 3 will be placed (adhesive application process).
The adhesive application step is a step of applying adhesives 34A, 35A to the placement surface (upper surface) of the core wrap sheet 5 on which the first absorbent core 3 is placed before placing the first absorbent core 3 on the core wrap sheet 5 transported in one direction (before the first core placement step is performed). Specifically, in the adhesive application step, as shown in Fig. 4, adhesive 34A is continuously applied by application means 34 to both side portions 5B, 5B of the CD on one surface (upper surface on the conveyor belt 32) of the core wrap sheet 5, and adhesive 35A is continuously applied by application means 35 to the central portion 5A of the CD on the one surface.
In this embodiment, the application means 34 is disposed upstream of the application means 35 in the MD1, and therefore the adhesive 34A is applied to the core wrap sheet 5 prior to the adhesive 35A. The central portion 5A in the CD of the core wrap sheet 5 is the portion where the first absorbent core 3 manufactured in the first core manufacturing department 20 is disposed, and the side portions 5B, 5B are each folded back toward the first absorbent core 3 and overlapped with the first absorbent core 3 (see FIG. 7).

In the adhesive application step of this embodiment, the application patterns of the adhesives 34A, 35A are different between the central portion 5A and both side portions 5B, 5B of the CD on the arrangement surface (upper surface) of the core wrap sheet 5 on which the first absorbent core 3 is placed. Specifically, as shown in Fig. 7, the adhesive 34A is applied in a continuous line shape extending in MD1 (the longitudinal direction of the core wrap sheet 5) in a plan view on both side portions 5B, 5B, and the adhesive 35A is applied in a spiral shape extending in MD1 in a plan view on the central portion 5A.
On one side of the core wrap sheet 5 after the adhesives 34A, 35A have been applied, on each of the side portions 5B, 5B, a plurality of (four in FIG. 7) application portions of the adhesive 34A that are continuous in plan view are arranged in a line in the CD, and on the central portion 5A, a plurality of (five in FIG. 7) application portions of the adhesive 35A that are spiral in plan view are arranged in a line in the CD. The portion of the core wrap sheet 5 where the adhesive 34A is applied in a continuous line is a portion where the adhesive 34A is so-called "solid coating", and the adhesive 34A is attached to the entire area of the portion.
On the other hand, in the portion of the core wrap sheet 5 where the adhesive 35A is applied in a spiral shape, the adhesive 35A extends in the MD1 so as to draw a spiral, and the applied and non-applied portions of the adhesive 35A are alternately present in the CD1. Note that the application pattern of the adhesives 34A and 35A is not limited to the one shown in the figure, and can be set arbitrarily.

As shown in FIG. 4, the manufacturing process of the second absorbent core carried out in the second core manufacturing section 40 includes a water-absorbent polymer spraying process in which an adhesive is applied to one side of the base sheet 4S, which is a long sheet transported in one direction, and then the second water-absorbent polymer 4P is continuously supplied while periodically removing the continuously supplied second water-absorbent polymer 4P midway, thereby intermittently supplying the second water-absorbent polymer 4P to the base sheet 4S, spraying and adhering it, and a process in which another long base sheet is superimposed on one side of the base sheet 4S to obtain a long second absorbent core 4. The water-absorbent polymer may also be sprayed on this "another long base sheet".

To explain further, in the second core manufacturing department 40, adhesives 41A, 42A (see Figure 8) are applied to each of the two base sheets 4S that constitute the second absorbent core 4 by application means 41, 42, and then a second water-absorbing polymer 4P is sprayed onto the adhesive-coated surface of at least one of the two sheets by spraying means 43, and then the two sheets 4S are overlapped with each other with their adhesive-coated surfaces facing inwards to produce a long second absorbent core 4.
In Fig. 4, one of the two base sheets 4S (the base sheet in contact with the first absorbent core 3) is designated as 4S1, and the other is designated as 4S2. In other words, the manufacturing process of the second absorbent core includes a step of intermittently supplying the second water-absorbent polymer 4P between the base sheets 4S1 and 4S2, which are two long sheets continuously transported in the same direction.

More specifically, in the second core manufacturing section 40, the long base sheet 4S1 is continuously unwound from a raw web 4R1 in which the long base sheet 4S1 is wound in a roll, and adhesive 41A is applied to one side of the base sheet 4S1 (the surface facing the other base sheet 4S2) by application means 41. In parallel with this, the base sheet 4S2 is continuously unwound from a raw web 4R2 in which the long base sheet 4S2 is wound in a roll, and adhesive 42A is applied to one side of the base sheet 4S2 (the surface facing the other base sheet 4S1) by application means 42.
In this embodiment, as shown in Fig. 8, the adhesive 41A applied to the base sheet 4S1 in contact with the first absorbent core 3 is applied in a spiral shape extending in the conveying direction (longitudinal direction) MD2 of the base sheet 4S1 in a plan view, and the adhesive 42A applied to the base sheet 4S2 on which the second water-absorbing polymer 4P is directly sprayed is applied (so-called solid coating) to almost the entire area of one side of the base sheet 4S2. On one side of the base sheet 4S1 after the adhesive 41A is applied, a plurality of adhesive application portions (eight in Fig. 8) in a spiral shape in a plan view are arranged in a line in CD, and the adhesive 41A is applied in a spiral shape to almost the entire area of the one side. The application patterns of the adhesives 41A and 42A are not limited to those shown in the figure, and can be set arbitrarily.

As shown in Figures 4 and 6, the spraying means 43 is disposed at a position spaced above the base sheet 4S onto which the second water-absorbing polymer 4P is to be sprayed. The second water-absorbing polymer 4P sprayed from the spraying means 43 falls by its own weight and adheres to one side of the base sheet 4S (4S2) being conveyed below the spraying means 43. In this embodiment, the second water-absorbing polymer 4P is sprayed onto one of the base sheets 4S1 and 4S2, but the second water-absorbing polymer 4P may be sprayed onto the base sheets 4S1 and 4S2.
The spraying means 43 is not particularly limited in configuration as long as it can accurately spray a predetermined amount of particles of the second water-absorbing polymer 4P at a predetermined position on the base sheet 4S being transported. For example, in this embodiment, as shown in Figures 5 and 6, the spraying means 43 includes a hopper 431 capable of storing the second water-absorbing polymer 4P, which is a powder, therein and having a discharge port 431a for the second water-absorbing polymer 4P, and a transporting means 432 located below the hopper 431 and transporting the second water-absorbing polymer 4P discharged from the discharge port 431a to a spraying position and spraying it.
The conveying means 432 has a receiving means 433 that receives the second absorbent polymer 4P discharged from the discharge outlet 431a, and a vibration generating means 434 that vibrates the receiving means 433, and by vibrating the receiving means 433 with the vibration generating means 434, the second absorbent polymer 4P on the receiving means 433 can be conveyed to the spraying position.

5, the present embodiment includes a second water-absorbent polymer supplying section 162 that supplies the second water-absorbent polymer 4P to the hopper 431. The second water-absorbent polymer supplying section 162 includes a second supply tank 163 that continuously supplies the second water-absorbent polymer 4P to the hopper 431, a second storage tank 164 that stores the second water-absorbent polymer 4P to be supplied to the second supply tank 163, and a second water-absorbent polymer supplying means 165 that supplies the second water-absorbent polymer 4P in the second storage tank 164 to the second supply tank 163.
The second supply tank 163 is a sealed container, and its bottom is in communication with the hopper 431 via the conveying path 166. The second water-absorbing polymer 4P in the second supply tank 163 is supplied to the hopper 431 via the conveying path 166.
An adjustment valve 169 is provided in the conveying path 166 as an adjustment means for adjusting the cross-sectional area of the path to adjust the supply amount of the second water-absorbing polymer 4P to the hopper 431. As the adjustment valve 169, either a butterfly valve that opens and closes a valve body by manual operation or a solenoid valve that opens and closes a valve body by electronic control may be used, but in this embodiment, a solenoid valve is used.
The second water-absorbing polymer supplying means 165 includes a vacuum conveying device 167 provided in the second supply tank 163, and a supply path 168 connecting the vacuum conveying device 167 and the second storage tank 164. One end of the supply path 168 is connected to the suction side of the vacuum conveying device 167, and the other end is connected to the second storage tank 164. The second water-absorbing polymer 4P stored in the second storage tank 164 is an unused second water-absorbing polymer 4P.
According to such a second water-absorbing polymer supplying means 165, when the vacuum conveying device 167 is operated, the unused second water-absorbing polymer 4P in the second supply tank 163 is supplied to the second supply tank 163 via the conveying path 166 accompanied by a gas flow, and is stirred and mixed with the existing second water-absorbing polymer 4P in the second supply tank 163.

In the second core manufacturing section 40, as shown in FIG. 4, the long second absorbent core 4 obtained through the spraying process of the second absorbent polymer 4P by the spraying means 43 is introduced between nip rolls 44, 45 and compressed in the thickness direction, and then adhesive is applied to one side of the second absorbent core 4 (the side facing the first absorbent core 3) by the application means 46.
In this embodiment, the adhesive is applied in a spiral shape extending in the conveying direction (longitudinal direction) MD4 of the second absorbent core 4 in plan view. After the adhesive is applied, a plurality of adhesive application portions (e.g., five adhesive application portions) in a spiral shape in plan view are arranged in the CD on one side of the second absorbent core 4. The adhesive application pattern is not limited to the above and can be set arbitrarily. The long second absorbent core 4 with adhesive applied to one side in this way is transported to the second transport section 50 and overlapped on the first absorbent core 3.

In this embodiment, in the water-absorbent polymer spraying step performed in the second core manufacturing unit 40, the second water-absorbent polymer 4P is intermittently sprayed on one side of the base sheet 4S2 so that non-attached regions 4N of the second water-absorbent polymer 4P are intermittently arranged in the conveying direction MD3 of the base sheet 4S2, as shown in Fig. 9. By such intermittent spraying of the second water-absorbent polymer 4P, the attached regions 4M and non-attached regions 4N of the second water-absorbent polymer 4P are alternately arranged in the conveying direction MD3 (the longitudinal direction of the base sheet 4S2) on one side of the base sheet 4S2.
The reason why the second water-absorbent polymer 4P is intermittently sprayed onto the base sheet 4S (4S2) in this manner is to facilitate the cutting of the second absorbent core 4 (absorbent body 1) which is carried out after this spraying step. That is, the process after obtaining the long second absorbent core 4 may be 1) a process of directly transporting the long second absorbent core 4 to the second conveying section 50, and a long absorbent body 1 is obtained through a folding process of the core wrap sheet 5 by the folding means 56 described later, and the long absorbent body 1 is cut to a predetermined product unit length, or 2) a process of cutting the long second absorbent core 4 to a predetermined product unit length in the second core manufacturing section 40 after the long second absorbent core 4 has passed between the nip rolls 44, 45 and after adhesive has been applied, to obtain a sheet of the second absorbent core 4, and the sheet of the second absorbent core 4 is transported to the second conveying section 50. However, since a water-absorbent polymer is generally very hard, if the second water-absorbent polymer 4P is present at the cutting position of the second absorbent core 4 (absorbent body 1) in 1) or 2), poor cutting may occur.

In this embodiment, in order to prevent poor cutting of the second absorbent core 4 (absorbent body 1), the second absorbent polymer 4P is not sprayed at the intended cutting position of the long second absorbent core 4. That is, when cutting the long second absorbent core 4 in 1) or 2), the second absorbent core 4 is cut at the non-attached region 4N of the second absorbent polymer 4P. Therefore, the second absorbent core 4 obtained by cutting the long second absorbent core 4 has a portion in the longitudinal direction where the abundance ratio of the second absorbent polymer is lower than the surrounding area. The portion is located in the front and rear end regions in the longitudinal direction of the second absorbent core. In this embodiment, as shown in FIG. 4, the long second absorbent core 4 is conveyed to the second conveying section 50 as is without being cut, and 1) is adopted.

The method of intermittently spraying the second water-absorbent polymer 4P onto the base sheet 4S employs a method in which the spraying of the second water-absorbent polymer 4P from the spraying means 43 is continuous, and the flow of the second water-absorbent polymer 4P from the spraying means 43 toward the base sheet 4S is appropriately blocked.

In this intermittent spraying process, in this embodiment, in the second absorbent polymer spraying process in the second core manufacturing section 40, the second absorbent polymer 4P that falls continuously toward the base sheet 4S (4S2) from a spraying means 43 for the second absorbent polymer 4P arranged at a position spaced apart from the base sheet 4S (4S2) is periodically removed, and the second absorbent polymer 4P is intermittently sprayed.
In this embodiment, as shown in Figures 4 and 6, the second core manufacturing section 40 is provided with a recovery means 47 for the second water-absorbing polymer 4P between the spraying means 43 and the base sheet 4S (4S2) transported below it.
The recovery means 47 recovers the second absorbent polymer 4P that was periodically removed and not supplied between the base sheets 4S (4S2) in the manufacturing process of the second absorbent core, and conveys it to the continuous supply step in the manufacturing process of the first absorbent core. The recovery of the second absorbent polymer 4P and the process of conveying it to the continuous supply step in the manufacturing process of the first absorbent core will be described later. The second absorbent polymer that is recovered and conveyed to the manufacturing process of the first absorbent core will be referred to as the "recovered second absorbent polymer 4P1" below.

The second conveying section 50 is equipped with a conveying means 51 capable of conveying the object on the conveying surface while sucking it. The conveying means 51 of the second conveying section 50 is configured to include a breathable conveyor belt 52 that moves on a predetermined circular track in the direction of the arrow R3 in FIG. 4, and suction boxes 53, 54 as suction means installed in the circular track. The conveyor belt 52 forms a conveying surface for the object, and the object (a laminate of the core wrap sheet 5, the first absorbent core 3 and the second absorbent core 4) is placed on the upper surface of the conveyor belt 52. The conveyor belt 52 is, for example, made of a mesh belt having a large number of suction holes (not shown). When the suction boxes 53, 54 are operated, the object on the conveyor belt 52 (conveying surface) is sucked through the suction holes (not shown).

As shown in FIG. 4, the second conveying section 50 is equipped with a pressing roll 55 that presses the stack of the first absorbent core 3 and the second absorbent core 4 from the second absorbent core 4 side (upper surface side) after the second absorbent core 4 manufactured in the second core manufacturing section 40 is supplied onto the first absorbent core 3. The pressing roll 55 is disposed on the opposite side of the suction box 53, sandwiching the core wrap sheet 5 (first absorbent core 3) being conveyed, at or near the junction of the second absorbent core 4 in the conveying path of the core wrap sheet 5.

As shown in FIG. 4, the second conveying section 50 is provided with a folding means 56 for the core wrap sheet 5 downstream of the pressure roll 55 in the MD. The folding means 56 is installed on a part of the orbit of the conveyor belt 52, and is disposed corresponding to the location of the suction box 54. The folding means 56 is provided with a known folding mechanism for folding back the both side portions 5B, 5B of the core wrap sheet 5 being conveyed, i.e., the extensions from both side edges along the MD of the absorbent core 2 (a laminate of a first absorbent core 3 and a second absorbent core 4) placed on the core wrap sheet 5, toward the absorbent core 2.

The first absorbent cores 3 manufactured in the first core manufacturing section 20 are intermittently arranged in MD1 at the central portion 5A of the upper surface of a long core wrap sheet 5 being transported in one direction (the direction indicated by the symbol MD1) by a first transport section 30. Adhesives 34A, 35A have been applied in advance to substantially the entire upper surface of the core wrap sheet 5 by application means 34, 35, and the arranged first absorbent cores 3 are adhered to the upper surface of the core wrap sheet 5.
The core wrap sheet 5 to which the first absorbent core 3 is adhered is pressed against the core wrap sheet 5 by a pressing roll 36 provided in the first conveying section 30, compressing the first absorbent core 3 in the thickness direction and conveying it to the second conveying section 50.
The core wrap sheet 5 having the first absorbent core 3 transported to the second conveying section 50 is overlapped with the second absorbent core 4 to which adhesive has previously been applied by the application means 46 at the joining position P1, and the core wrap sheet 5 and the second absorbent core 4 are joined together to form an integrated unit.

In the second conveying section 50, a long second absorbent core 4 is joined onto the first absorbent core 3 arranged in the central portion 5A of the CD of the long core wrap sheet 5, and then a folding means 56 folds both side portions 5B, 5B of the CD of the core wrap sheet 5 back toward the central portion 5A (second absorbent core 4 side) so as to wrap (roll up) the second absorbent core 4, thereby obtaining a long absorbent body 1.
The long absorbent body 1 obtained in the above manner is then cut to a predetermined product unit length by a cutting means (not shown), to produce the absorbent body 1 as shown in Fig. 1. As described above, at the intended cutting position in the long absorbent body 1, there are non-attached regions 4N of the second absorbent polymer 4P due to intermittent spraying of the second absorbent polymer 4P constituting the second absorbent core 4, and by cutting the long absorbent body 1 at the non-attached regions 4N, cutting defects are unlikely to occur, and the operation of cutting to product unit lengths can be performed smoothly.

The recovery step of the second water-absorbent polymer 4P and the step of transporting it to the continuous supply step in the manufacturing process of the first absorbent core will be described.
As shown in Figures 5 and 6, the recovery means 47 includes a recovery box 472 having an opening 471 through which the second absorbent polymer 4P, which is a powder that continuously falls from the spraying means 43, passes, and a shutter 473 that serves as a blocking means for periodically blocking the opening 471.
In addition to the recovery means, the manufacturing apparatus 10 is also provided with a re-supply means 474 for transporting and supplying the second absorbent polymer 4P accumulated in the recovery box 472 to the first supply tank 63 in the manufacturing process of the first absorbent core.
The recovery box 472 is hollow and is disposed in a range including the drop position of the second water-absorbing polymer 4P that falls continuously from the spraying means 43. An opening 471 is formed in the bottom 472a of the recovery box 472 at the drop position of the second water-absorbing polymer 4P that falls continuously. A duct 477 that serves as a guide path for guiding the second water-absorbing polymer 4P that falls continuously from the spraying means 43 into the recovery box 472 is disposed above the opening 471. The second water-absorbing polymer 4P that falls continuously is introduced into the recovery box 472 through the duct 477, passes through the opening 471, and is continuously supplied between the base sheet 4S1 and the base sheet 4S2 that are long sheets located below the opening 471.

The shutter 473 is disposed inside the recovery box 472. The shutter 473 is configured to be slidable between a position where the opening 471 is opened and a position where the opening 471 is closed. The shutter 473 is normally in a position where the opening 471 is opened, and when it is time to block the opening 471, it is moved by a driving means (not shown) to block the opening 471. The timing to block the opening 471 is the timing to form a non-attached region 4N (see FIG. 9) of the second water-absorbing polymer 4P on one side of the base sheet 4S2. When the timing to block the opening 471 has passed, the shutter 473 is returned by the driving means to a position where the opening 471 is opened, and the position is maintained until the next timing to block it.
The collection box 472 is disposed so as to be inclined with respect to the falling direction of the second water-absorbing polymer 4P. In this embodiment, in FIG. 6, the right end 472b, which is one end, is disposed so as to be located lower than the left end 472c, which is the other end. The end 472b constitutes a depositing portion. Therefore, when the opening 471 is closed by the shutter 473, the second water-absorbing polymer 4P, which is prevented from falling from the opening 471 by the shutter 473, is received on or around the shutter 473, and slides down to the end 472b side and deposits. The end 472b is formed so as to be tapered in the inclination direction, so that the second water-absorbing polymer 4P, which slides down the bottom 472a and deposits at the end 472b, can be easily collected in the tapered portion.

Incidentally, if the second water-absorbing polymer 4P collected and accumulated in the collection box 472 is re-supplied to the second supply tank 163, it will fall from the hopper 431 and be used to manufacture the second water-absorbing polymer 4P, so that the yield of the second water-absorbing polymer 4P will be good. However, when the second water-absorbing polymer 4P, which is a particle, is discharged to the outside, an external force is applied to the particle, so that the particle may be crushed and atomized. For example, when the supply of the second water-absorbing polymer 4P between the base material sheets is blocked using the shutter 473 as in this embodiment, the second water-absorbing polymer 4P, which is continuously falling, collides with the shutter 473 which moves to open and close, so that the second water-absorbing polymer 4P tends to be crushed and atomized. For example, when the second water-absorbing polymer 4P is spherical, the spherical second water-absorbing polymer 4P is crushed to become a non-spherical shape.
If the atomized second water-absorbent polymer 4P is re-supplied to the hopper 431, the chances of collision with the shutter 473 increase, accelerating the atomization and gradually reducing the average particle size. The reduction in particle size of the second water-absorbent polymer 4P may lead to a reduction in absorption performance, such as the ability to retain bodily fluids. Re-supplying such particles with reduced absorption performance is one of the factors that hinder the stable production of absorbents with the desired absorption performance.

Fig. 10 is a diagram showing the results of measuring the relationship between the particle size of polymer particles and the water retention capacity under pressure (hereinafter referred to as "water retention capacity under pressure"). In Fig. 10, the horizontal axis indicates the size of the particle size, and the vertical axis indicates the water retention capacity under pressure. For the measurement, water-absorbent polymers 22P with average particle sizes of 100 μm, 300 μm, and 500 μm were produced, and the water retention capacity under pressure was measured using a measuring device shown in Fig. 11.
A measuring device for carrying out the method for measuring the water retention under pressure will be described with reference to FIG.
As shown in Fig. 11 (1), a column 210A is prepared in which a mesh 213 (250 mesh) is attached to the bottom opening 212 of a vertically standing cylinder 211A (inner diameter 30 mm). 0.500 g of water-absorbent polymer 22P (particles) is placed in the column to a uniform thickness. Next, a weight 221 (a weight capable of applying a pressure of 2.0 kPa) with an outer diameter slightly smaller than 30 mm is placed on the water-absorbent polymer 22P.
100 mL of physiological saline 231 (0.9% by mass sodium chloride water) at room temperature (20±5° C.) is poured into a 100 mL beaker 230. Then, the column 210A is immersed in the physiological saline 231 so that the mesh 213 does not touch the bottom of the beaker 230, and is left in this state for one hour.
Thereafter, the column 210A is removed from the beaker 230, and the water is drained for 15 minutes with a weight 221 placed on the water-absorbent polymer 22P as shown in Fig. 11 (2). The temperature of the test atmosphere is room temperature (20 ± 5°C).
Then, the water retention capacity under pressure is calculated according to the following formula (1).

According to Figure 10, the trend of the measurement results is that the smaller (finer) the particle size of the water-absorbent polymer is, the lower the water retention capacity under pressure, which may cause a decrease in the absorption performance of the absorbent body.

Therefore, in this embodiment, the second absorbent polymer 4P that has been collected and accumulated in the collection box 472 is collected and transported by a re-supply means 474 to the manufacturing process for the first absorbent polymer (first supply tank 63) rather than to the manufacturing process for the second absorbent core (second supply tank 163).
5, the re-supply means 474 includes a vacuum transport device 475 provided in the first supply tank 63, and a recovery path 476 connecting the vacuum transport device 475 and the recovery box 472. One end 476a of the recovery path 476 is connected to the suction side of the vacuum transport device 475, and the other end 476b is connected to an end 472b of the recovery box 472.
In such a re-supply means 474, when the vacuum conveying device 475 is operated, the second water-absorbent polymer 4P accumulated in the recovery box 472 is accompanied by a gas flow and is supplied as the recovered second water-absorbent polymer 4P1 to the first supply tank 63. As a result, in the first supply tank 63, the first water-absorbent polymer 3P and the recovered second water-absorbent polymer 4P1 are agitated and mixed by the air flow.
That is, in the manufacturing process of the first absorbent core, the first absorbent polymer 3P is supplied from the first storage tank 64 to the first supply tank 63, and the recovered second absorbent polymer 4P1 recovered and transported from the manufacturing process of the second absorbent core is also supplied, so that a mixture of the first absorbent polymer 3P and the recovered second absorbent polymer 4P1 is continuously supplied from the first supply tank 63 to the duct 22.

Thus, according to the manufacturing method of this embodiment, the second absorbent polymer 4P that is at risk of being atomized and that has been used once in the second manufacturing process and then recovered is not returned to the second manufacturing process, but is returned to the first manufacturing process as recovered second absorbent polymer 4P1, where it is mixed with the first water absorbent polymer 3P and used to manufacture the first water absorbent polymer 3P.
Therefore, the particles of the second absorbent polymer 4P that are rejected and collected in the manufacturing process of the absorbent body 1 (the manufacturing process of the second absorbent core 4) are reliably consumed, so that the progress of atomization of the particles of the absorbent polymer is effectively suppressed and the yield of the second absorbent polymer 4P can be reduced. In addition, since the progress of atomization of the particles of the absorbent polymer can be suppressed, an absorbent body having the desired absorption performance can be stably manufactured.

According to the manufacturing method of this embodiment, the manufacturing process of the second absorbent core includes a step of intermittently supplying the second absorbent polymer 4P between the base sheets 4S1 and 4S2, which are two long sheets that are continuously conveyed, so that non-attached areas 4N of the second absorbent polymer 4P are formed in the conveying direction CD of the base sheets. Therefore, the second absorbent core 4 (absorbent body 1) can be cut at the non-attached areas 4N, thereby preventing cutting failures.

According to the manufacturing method of this embodiment, the recovered second water-absorbent polymer 4P1 recovered and transported from the manufacturing process of the second absorbent core is supplied from the first storage tank 64 to the first supply tank 63 to which the first water-absorbent polymer 3P is supplied, mixed with the first water-absorbent polymer 3P, and continuously supplied from the first supply tank 63 to the manufacturing process of the first absorbent core. Therefore, the first water-absorbent polymer 3P and the recovered second water-absorbent polymer 4P1 are well mixed in the first absorbent core 3, so that deterioration of the performance of the first absorbent core 3 can be suppressed. Therefore, an absorbent having the desired absorption performance can be stably manufactured.
When the second absorbent polymer 4P is spherical, the absorbent polymer supplied by the first supply tank 63 is a mixture of the first absorbent polymer 3P and the pulverized non-spherical second absorbent polymer 4P. Thus, the first absorbent core 3 includes the first absorbent polymer 3P and the pulverized non-spherical second absorbent polymer 4P. In other words, the first absorbent polymer 3P in the first absorbent core 3 contains the pulverized non-spherical water-absorbing polymer.

If the ratio of the recovered second absorbent polymer 4P1 transported from the second absorbent core manufacturing process and supplied to the first supply tank 63 to the amount of the first absorbent polymer 3P supplied from the first storage tank 64 to the first supply tank 63 is too large, the influence of the fine powder contained in the recovered second absorbent polymer 4P1 may result in the absorbency of the first absorbent core 3 being lower than that of the first absorbent polymer 3P alone.
Therefore, the amount of recovered second absorbent polymer 4P1 relative to the amount of first absorbent polymer 3P supplied to the first supply tank 63 is 1/3 or less, preferably 1/5 or less, and more preferably 1/6 or less, taking into consideration the absorption performance and particle size of the recovered second absorbent polymer 4P1.
In this way, by specifying the amount of recovered second absorbent polymer 4P1 supplied to the first supply tank 63 to be at least 1/3 or less, the influence of the fine powder contained in the recovered second absorbent polymer 4P1 can be suppressed, and the deterioration of the absorbent performance of the first absorbent core 3 can be suppressed.

The ratio of the recovered second absorbent polymer 4P1 supplied to the first supply tank 63 and the first absorbent polymer 3P in the first supply tank 63 can be adjusted by adjusting the supply amount of the first absorbent polymer 3P supplied from the first storage tank 64 to the first supply tank 63 and the supply amount of the recovered second absorbent polymer 4P1 transported from the recovery box 472 by the resupply means 474. For example, if the supply amount of the first absorbent polymer 3P supplied from the first storage tank 64 to the first supply tank 63 is a fixed supply, the value of the transport amount of the recovered second absorbent polymer 4P1 by the resupply means 474 can be adjusted by increasing or decreasing the driving time of the vacuum transport device 475.

In this embodiment, the first water-absorbent polymer 3P and the second water-absorbent polymer 4P are made of the same kind of material, from the viewpoint that the first water-absorbent polymer 3P and the second water-absorbent polymer 4P are mixed in the first supply tank 63 and used to manufacture the first absorbent core 3. Specifically, a water-absorbent polymer of the same kind of material as the first water-absorbent polymer 3P is used as the second water-absorbent polymer 4P.
In this way, by using the first water-absorbent polymer 3P and the second water-absorbent polymer 4P made of the same kind of material, it is possible to suppress the deterioration of the performance of the first absorbent core 3. Therefore, it is possible to more stably manufacture an absorbent body having the desired absorption performance.

According to the manufacturing method of this embodiment, when the second absorbent polymer is continuously dropped and intermittently dropped from the opening 471, the shutter 473 is used to periodically close the opening 471 during the drop, so that the intermittent dropping of the second absorbent polymer 4P can be performed reliably. Therefore, the non-adherent region 4N of the second absorbent polymer 4P can be more reliably formed in the conveying direction CD of the base sheet, and cutting defects can be more reliably prevented.

According to the manufacturing method of this embodiment, the recovered second absorbent polymer 4P1 recovered in the manufacturing process of the second absorbent core is transported to the continuous supply process in the manufacturing process of the first absorbent core by entraining it in a gas flow, so that the external force applied to the absorbent polymer is smaller than that applied in a transport method that applies mechanical force, such as a screw conveyor, and this prevents the recovered second absorbent polymer 4P1 from being atomized during transport, thereby suppressing the deterioration of the performance of the first absorbent core 3. This makes it possible to more stably manufacture absorbents with the desired absorption performance.

In this embodiment, in the manufacturing process of the first absorbent core, the first absorbent polymer 3P and the second absorbent polymer (recovered second absorbent polymer 4P1) are both mixed with the fiber material 3F and used to manufacture the first absorbent core 3. Therefore, in the manufacturing process of the first absorbent core, the first absorbent polymer 3P and the second absorbent polymer (recovered second absorbent polymer 4P1) are not removed. As a result, the fine powder contained in the second absorbent polymer is reliably consumed without being removed or recovered, so further atomization is suppressed, and an absorbent body having the desired absorption performance can be manufactured more stably.

Next, another embodiment of the present invention will be described with reference to FIGS.
As shown in FIGS. 12 to 14, in the production apparatus 10, the recovery means 47 for the second water-absorbing polymer 4P includes an accumulation section .

The accumulation section 48 is for recovering and accumulating the second water-absorbent polymer 4P accumulated in the recovery box 472. As shown in Fig. 13 and Fig. 14, the accumulation section 48 includes an accumulation tank 481 and a recovery path 482 formed of piping that connects the accumulation tank 481 and the recovery box 472. The accumulation tank 481 has a capacity sufficient to store the second water-absorbent polymer 4P stored in the recovery box 472.
One end 482a of the recovery path 482 is connected to an upper end 481a of the storage tank 481 via a seal member so as to communicate with the inside of the storage tank 481. The other end 482b of the recovery path 482 is connected to an end 472b at which the second water-absorbing polymer 4P accumulates in the recovery box 472 via a seal member so as to communicate with the inside of the recovery box 472.

A changeover valve 483 is provided at the bottom 481b of the storage tank 481 as a valve that can alternatively select a transport path for the second water-absorbing polymer 4P stored in the storage tank 481. As the changeover valve 483, a butterfly valve that opens and closes a valve body by manual operation, or a solenoid valve that opens and closes a valve body by electronic control can be used. In this embodiment, a solenoid valve is used.
The switching valve 483 is operated when selecting whether the second water-absorbent polymer 4P stored in the storage tank 481 is to be subjected to the conveying process or discharged from the storage tank 481. For this reason, a three-way valve is used for the switching valve 483. The switching valve 483 has one port on the inlet side and two ports on the discharge side. One port on the discharge side of the switching valve 483 is connected to a discharge path 484 connected to a discharge container (not shown), and the other port on the discharge side is connected to a recovery path 476. The switching valve 483 is normally set to a valve position so as to guide the second water-absorbent polymer 4P in the storage tank 481 to the re-supply path 491.

The storage tank 481 is provided with sensors for detecting the storage state of the second water-absorbing polymer 4P in the tank. The sensors are a sensor (upper sensor) 111 installed in the upper part 481c of the storage tank 481, a sensor 113 installed near the top of the storage tank 481, and a sensor (lower sensor) 112 installed in the lower part 481d of the recovery tank. The vicinity of the top here refers to the range from the upper end 481a of the storage tank 481 to the recovery box 472. More specifically, it is the range from the upper end 481a to the recovery box 472, including the recovery path 482. In this embodiment, the sensor 113 is installed in the upper end 481a of the storage tank 481.
The sensor 111 detects whether the second water-absorbent polymer 4P in the storage tank 481 has reached a planned storage amount. The sensor 113 detects whether the second water-absorbent polymer 4P in the storage tank 481 has reached a storage limit amount. The sensor 112 detects whether the storage amount of the second water-absorbent polymer 4P in the storage tank 481 has reached a minimum storage amount.
Further, a sensor 115 is provided in the transport path from the recovery box 472 to the accumulation section 48. Specifically, in this embodiment, the sensor 115 is provided on the recovery path 482 located between the end 472b of the recovery box 472 and the on-off valve 496. The sensor 115 detects whether or not the second water-absorbent polymer 4P is clogged in the recovery path 482. The sensor 115 may be a capacitance sensor or a paddle-type sensor that detects the passage of the second water-absorbent polymer 4P from the amount of rotation of a detection paddle provided in the recovery path 482.

For sensors 111-113, a light-transmitting optical sensor is used. For this reason, each sensor has a light-emitting section and a light-receiving section, and at least the light-emitting surface and the light-receiving surface are arranged inside storage tank 481. Each sensor is configured to output by receiving detection light irradiated from the light-emitting section with the light-receiving section, and is of a type in which the output changes when the second water-absorbent polymer 4P is detected and when it is not detected. For sensors 111-113, instead of optical sensors, a capacitance sensor or a paddle-type sensor that has a detection paddle provided in recovery path 482 and detects the degree of passage of second water-absorbent polymer 4P from the amount of rotation of the paddle can be used.

As shown in FIG. 14, the sensor 114 is installed near the opening 471 of the recovery means 47. The sensor 114 detects whether the second water-absorbing polymer 4P is passing through the opening 471 properly. The vicinity of the opening 471 is a range in which the amount of the second water-absorbing polymer 4P passing through the opening 471 can be detected, and in this embodiment, the sensor 114 is attached to the outer surface of the bottom 472a with the detection surface facing downward from the opening 471.

In this embodiment, the second absorbent polymer 4P is collected by the accumulation section 48, and the second absorbent polymer 4P accumulated in the collection box 472 is introduced into the accumulation tank 481 through the collection path 482 and stored therein. Therefore, the removed second absorbent polymer 4P does not overflow from the collection box 472. As a result, the second absorbent polymer 4P accumulated in the collection box 472 is prevented from leaking and falling from the opening 471. As a result, uneven distribution of the second absorbent polymer 4P can be prevented.

In this embodiment, as shown in Figs. 12 and 13, the second absorbent polymer 4P stored in the storage tank 481 is transported to the first supply tank 63 by the resupply means 474. As shown in Fig. 13, the resupply means 474 includes a vacuum transport device 475 provided in the first supply tank 63 and a recovery path 476 connecting the vacuum transport device 475 and the storage tank 481. One end 476a of the recovery path 476 is connected to the suction side of the vacuum transport device 475, and the other end 476b is connected to the bottom 481b (see Fig. 14) of the storage tank 481 via the switching valve 483 so as to be able to communicate with it. In more detail, the other end 476b of the recovery path 476 is connected to the other discharge side port of the switching valve 483, and is configured to transport the second absorbent polymer 4P using air flow and positive pressure.

However, when the second absorbent polymer 4P collected and stored in the accumulation tank 481 is transported by the resupply means 474 in association with the gas flow, a phenomenon may occur in which the falling state of the second absorbent polymer 4P, which falls freely from the spraying means 43, is disturbed. This phenomenon may hinder the stable supply of the second absorbent polymer 4P to the spray target area. This phenomenon may be one factor in the variation of the second absorbent polymer 4P sprayed on the base sheet 4S, and may also affect the formation of the non-adherent area 4N.

Therefore, in this embodiment, the removal of the second water-absorbing polymer 4P and the recovery of the second water-absorbing polymer 4P are spatially separated. As for when to block the separation, it is set to when the second water-absorbing polymer 4P is transported to the above-mentioned continuous supply process. This is because it is presumed that the influence of the suction of the air flow generated during the continuous supply process and the associated pulsation act on the inside of the recovery box 472 via the accumulation tank 481 and affect the second water-absorbing polymer 4P that falls freely toward the opening 471.
For this reason, the manufacturing apparatus 10 in this embodiment is provided with an on-off valve 496 as an isolating means for spatially isolating the removal of the second water-absorbing polymer 4P from the recovery of the second water-absorbing polymer 4P. The on-off valve 496 is disposed between the shutter 473 for removing the second water-absorbing polymer 4P and the accumulation section 48 for recovering the removed second water-absorbing polymer 4P. Specifically, the on-off valve 496 is disposed between the recovery box 472 and the accumulation section 48 and is disposed in a recovery path 482 connected to both of them, so that the recovery path 482 can be opened and closed. The on-off valve 496 opens the recovery path 482 in normal times, and allows the introduction of the second water-absorbing polymer 4P discharged from the recovery box 472 into the recovery path 482. On the other hand, when the vacuum conveying device 475 of the resupply means 474 is operated to convey the second water-absorbing polymer 4P, the on-off valve 496 is closed.

According to this embodiment, even when the vacuum transport device 475 is operated to transport the recovered second absorbent polymer 4P1 by the resupply means 474, the recovery path 482 is closed by the on-off valve 496. Therefore, the recovery box 472 and the storage tank 481 of the storage section 48 are spatially isolated from each other, so that the second absorbent polymer 4P is less susceptible to the suction action and pulsation of the air flow generated on the resupply means 474 side. As a result, in the manufacturing process of the absorbent body 1 containing the second absorbent polymer 4P, the second absorbent polymer 4P can be stably continuously dropped while the continuously falling second absorbent polymer 4P is periodically and reliably removed. This leads to good formation of the non-adherent region 4N.

15 is a diagram showing the results of testing the non-sprayed width of the falling second water-absorbing polymer 4P when the vacuum transport device 475 is operated to generate suction force (suction always on) and when it is not operated to generate suction force (suction always off). Fig. 9(a) shows the measurement results when suction is always on, and Fig. 9(b) shows the test results when suction is always off. In both figures, the vertical axis shows the non-sprayed width, and the horizontal axis shows the number of tests.
The inspection method employed is to image the second absorbent core 4 with an image inspection machine and measure the non-spread width of the second absorbent core 4 from the image. Note that the non-spread width of the second absorbent core 4 may be inspected using a capacitance sensor instead of the image inspection machine.

The maximum value (MAX), minimum value (MIN), average value (Ave.) and standard deviation of the non-spray width were calculated and compared from the test results of Figures 15(a) and 15(b), and the difference in standard deviation (3σ) was more significant than the difference between the maximum value (MAX), minimum value (MIN) and average value (Ave.). Specifically, when the suction was always on, the standard deviation (3σ) was 20.2 mm, but when the suction was always off, the standard deviation (3σ) was 9.6 mm, resulting in smaller variation in the non-spray width when the suction was always off.
From these results, it can be confirmed that by turning on/off the re-supply means 474 (vacuum conveying device 475) during the manufacturing process of the absorbent body 1, spatially isolating the removal of the second absorbent polymer 4P from the recovery of the second absorbent polymer 4P, which leads to stable continuous falling of the second absorbent polymer 4P and successful formation of the non-adherent regions 4N.

Next, the configuration and control content of the control system of the manufacturing apparatus 10 in this embodiment will be described.
FIG. 16 is a block diagram for explaining the schematic configuration of the control system of the manufacturing apparatus 10. As shown in FIG. 16, the manufacturing apparatus 10 includes a control means 100. The control means 100 includes a CPU 101, which is a central processing unit, a RAM 102 and a ROM 103, which are storage units, and a timer 104, which is a measuring unit. Although not shown in the figure, the control means 100 includes input and output interfaces to which the means and devices to be controlled and the sensors serving as the detection means can be connected via signal lines. The input interface is connected to sensors 111, 112, and 113 installed in the storage tank 481, a sensor 114 installed near the opening 471 of the recovery box 472, and a sensor 115 installed on the recovery path 482, which is a transport path between the recovery box 472 and the accumulation unit 48, via signal lines, and the detection results (output) of each sensor are transmitted to the control means 100.
To the output side interface, the spraying means 43, the warning display unit, the adjustment valve 169, the vacuum transport device 167 and the vacuum transport device 475, the drive motor for opening and closing the shutter 473, the switching valve 483 and the opening and closing valve 496 are connected via signal lines. Although not shown in the figure, the output side interface is connected to each drive unit other than those mentioned above, such as the first core manufacturing unit 20, the first transport unit 30, the second core manufacturing unit 40 and the second transport unit 50, and it is possible to control the start and stop of operation by commands from the control means 100. The start of operation refers to a state in which the drive system of the manufacturing apparatus 10 is operated to manufacture the absorbent body 1 by the manufacturing apparatus 10, and the stop of operation refers to the stop of operation of all drive systems in order to stop the production of the absorbent body 1.

Each control mode will be explained below, but in each control mode, it is assumed that the manufacturing apparatus 10 is already in operation (control mode 1).
Control form 1 is a control based on the measurement time of the timer 104 without using sensors. In control form 1, the conveying process is started every time the measurement time t measured by the timer 104 reaches a set time t1 previously set in, for example, the ROM 102, and the removal of the second water-absorbing polymer 4P and the recovery of the second water-absorbing polymer 4P are spatially isolated. Specifically, when the measurement time t becomes equal to or greater than the set time t1, a signal is sent from the control means 100 to the opening/closing valve 496 to control the valve to close, and the vacuum conveying device 475 is operated.

In this way, when the set time t1 is reached, the vacuum conveying device 475 is operated and the on-off valve 496 is controlled to close, so that the recovery box 472 and the storage tank 481 of the storage section 48 are spatially isolated from each other at the set time t1, making them less susceptible to the effects of the suction action and pulsation of the air flow generated on the resupply means 474 side. As a result, in the manufacturing process of the absorbent body 1 containing the second absorbent polymer 4P, the second absorbent polymer 4P is stably continuously dropped while the continuously falling second absorbent polymer 4P is periodically and reliably removed. This leads to the formation of the non-attached region 4N being performed well. In addition, since the on-off valve 496 is automatically closed by the control means 100, there is no spatial isolation, and the second absorbent polymer 4P can be continuously dropped more stably.

(Control Form 2)
In the control form 2, the amount of the second water-absorbing polymer 4P stored in the storage tank 481 equipped with a sensor is detected by the sensor. By detecting the amount of the second water-absorbing polymer 4P stored in the storage tank 481 by the sensor, the amount of the second water-absorbing polymer 4P stored in the storage tank 481 can be accurately known, and control appropriate to the amount of storage can be performed.

(Control Form 3)
In control form 3, a sensor 111 installed in the upper part 481c of the storage tank 481 is used to detect whether the second water-absorbent polymer 4P in the storage tank 481 has reached the planned storage amount. In this control form, when the sensor 111 installed in the upper part 481c of the storage tank 481 detects the second water-absorbent polymer 4P, the control means 100 determines that the planned storage amount has been reached. Since the output of the sensor 111 changes when it detects the second water-absorbent polymer 4P, the control means 100 (CPU 101) determines that the planned storage amount has been reached when there is a change in the output from the sensor 111.
In control form 3, when it is detected that the second absorbent polymer 4P in the storage tank 481 has reached the planned storage amount, the vacuum transport device 475 is operated to start transporting the second absorbent polymer 4P to the first supply tank 63, and the opening/closing valve 496 is controlled to close so as to spatially isolate the recovery box 472 and the storage tank 481 of the storage section 48.
Therefore, when the second absorbent polymer 4P in the storage tank 481 reaches the planned storage amount, the second absorbent polymer 4P in the storage tank 481 is transported to the first supply tank 63 as recovered second absorbent polymer 4P1 and reused, while the second absorbent polymer 4P can be continuously dropped stably.
In this control form, when it is detected that the second water-absorbing polymer 4P in the storage tank 481 has reached the planned storage amount, the vacuum transport device 475 is operated at that time and the on-off valve 496 is controlled to be closed, but it is not necessary to control immediately after detection, and it may be controlled after a certain time has passed (delay control). In this case, a certain time is stored in the ROM 103 in advance, and the timer 104 starts measuring from the time when the sensor 111 detects that the planned storage amount has been reached, and when the certain time has passed, the vacuum transport device 475 is operated and the on-off valve 496 is controlled to be closed. In this way, by introducing delay control, it is possible to eliminate the transient output of the sensor 111 and the variation in the sensor output, thereby improving the control accuracy.

(Control Form 4)
In control form 4, the sensor 113 installed near the top of the storage tank 481 detects whether the second water-absorbent polymer 4P in the storage tank 481 has reached its storage limit. In this control form, when the sensor 113 installed near the top detects the second water-absorbent polymer 4P, the control means 100 determines that the second water-absorbent polymer 4P has been stored up to its storage limit. The control means 100 (CPU 101) determines that the storage limit has been reached from a change in output when the sensor 113 detects the second water-absorbent polymer 4P.
In this control mode, when the second water-absorbing polymer 4P in the storage tank 481 reaches its storage limit, the control means 100 stops the operation of all drive systems to stop the operation of the manufacturing apparatus 10 at that point.
Therefore, the second water-absorbing polymer 4P recovered from the storage tank 481 can be prevented from overflowing into the recovery passage 482 outside the tank.
In this control form, the warning display unit may be operated before or after the operation of the drive system of the manufacturing apparatus 10 is stopped to warn that the accumulation tank 481 is at its storage limit.

(Control Form 5)
In the control form 5, the sensor 112 installed in the lower part 481d of the storage tank 481 detects whether the storage amount of the second water-absorbing polymer 4P in the storage tank 481 has reached the minimum storage amount. The control means 100 continues the normal operation state to collect the second water-absorbing polymer 4P transported from the recovery box 472 in the storage tank 481 until the storage amount of the second water-absorbing polymer 4P reaches the minimum storage amount. Then, when it is detected by the sensor 112 that the storage amount has reached the minimum storage amount, the control means 100 stops the operation of the vacuum transport device 475 at that time to stop the transport of the second water-absorbing polymer 4P to the first supply tank 63, and controls the opening and closing valve 496 to spatially isolate the recovery box 472 and the storage tank 481 of the storage section 48.
In this way, the operation of the vacuum transfer device 475 is stopped to avoid the vacuum transfer device 475 from running idle, so that damage to the vacuum transfer device 475 can be prevented.

(Control Form 6)
In the control form 6, the transfer destination of the second water-absorbing polymer 4P in the storage tank 481 can be alternatively selected by using the changeover valve 483 provided at the bottom 481b of the storage tank 481. As described above, the changeover valve 483 constituted by a three-way valve is usually set to a position of the valve body so as to transfer the second water-absorbing polymer 4P to the first supply tank 63.
For example, when the sensor 113 detects that the storage amount in the accumulation tank 481 has reached the storage limit amount, a signal is sent from the control means 100 to the switching valve 483 to switch the position of the valve body to the discharge path 484 connected to the discharge container, thereby discharging the second absorbent polymer 4P in the accumulation tank 481 from the tank, thereby eliminating the need to stop the operation of the manufacturing apparatus 10 and preventing a decrease in productivity.
Alternatively, in the case where cleaning of the inside of the storage tank 481 is assumed, the control means 100 is provided with a cleaning mode and a switch for activating said mode, and when the switch is operated to set the cleaning mode, the position of the valve body is controlled to switch to the side of the discharge path 484 connected to the discharge container, thereby emptying the inside of the storage tank 481.

(Control Form 7)
In the seventh control mode, the sensor 114 installed near the opening 471 formed in the recovery box 472 detects the properness of the passage of the second water-absorbent polymer 4P. When the second water-absorbent polymer 4P passes through the opening 471 properly, the control means 100 controls the transport of the second water-absorbent polymer 4P in the storage tank 481 to the first supply tank 63, and when it detects that the second water-absorbent polymer 4P does not pass through the opening 471 properly, it controls the dropping of the second water-absorbent polymer 4P to stop at that point. Specifically, it controls the operation of a drive motor (not shown) to move the shutter 473, which opens and closes to intermittently supply the second water-absorbent polymer 4P, to a closed position.
Whether the second water-absorbing polymer 4P has properly passed through the opening 471 or not can be detected by setting in advance in the ROM 103 the output from the sensor 114 when the second water-absorbing polymer 4P has properly passed and comparing the output from the sensor 114 with the set value. It is preferable to set an allowable range for the output from the sensor 114 when the second water-absorbing polymer 4P has properly passed, rather than a single value, and to determine that the second water-absorbing polymer 4P has not properly passed when the output from the sensor 114 exceeds the allowable range, since this can avoid overly sensitive control.

(Control Form 8)
In the eighth control mode, the sensor 115 installed in the recovery path 482 that communicates between the recovery box 472 and the accumulation section 48 can detect whether or not the recovery path 482 is clogged with the second water-absorbent polymer 4P.
Whether the second water-absorbing polymer 4P has clogged the recovery passage 482 or not can be detected by setting in advance in the ROM 103 the output from the sensor 115 in a normal state when not clogged, and comparing the output from the sensor 115 with the set value. When the sensor 115 detects clogging in the recovery passage 482, it is assumed that the second water-absorbing polymer 4P has clogged the recovery passage 482 due to a malfunction of the on-off valve 496 installed downstream of the sensor 115 in the conveying direction, or a malfunction of any of the sensors 111 to 113. Therefore, when the sensor 115 detects clogging in the recovery passage 482, it is preferable to control the control means 100 to stop the operation of the manufacturing apparatus 10.

In control form 3-5, by performing the delay control described in control form 2, it is possible to eliminate the variation in each transient output and sensor output, thereby improving control accuracy.

The manufacturing apparatus 10 described in each of the above-mentioned embodiments is based on the premise of a new installation, but the concept of the present invention can also be applied to existing manufacturing apparatuses. An example is shown in FIG. 17. In the manufacturing apparatus 10A shown in FIG. 17, the water-absorbent polymer supplied to the first supply tank 63 and the second supply tank 163 is the same type, and the second storage tank 164 described in the manufacturing apparatus 10 is used as a shared storage tank 164A. The vacuum conveying device 475 and the vacuum conveying device 167 are connected to conveying paths 203 and 204 along which the water-absorbent polymer is conveyed from the storage tank 164A via a path switching valve 201.
In addition, the storage tank 481 described in the manufacturing apparatus 10 is configured to have a re-supply means 474A by connecting the other end 476Ab of the recovery path 476A that communicates the transport path 204 and the storage tank 481. A switching valve 207 for switching the transport path is provided at the connection part of the transport path 204 and one end 476Aa of the recovery path 476A. The switching valve 207 is capable of switching between a path for guiding the second water-absorbing polymer 4P recovered in the storage tank 481 to the first transport path 204A that transports the second water-absorbing polymer 4P from the recovery path 476A to the vacuum transport device 475, and a path for transporting the second water-absorbing polymer 4P from the recovery path 476A to the storage tank 164A to the second transport path 204B.

Even in the manufacturing apparatus 10A having such a configuration, by switching the switching valve 207 to the first conveying path 204A side, the recovered second water-absorbing polymer 4P can be conveyed to the first supply tank 63 as the recovered second water-absorbing polymer 4P1, so that the recovered second water-absorbing polymer 4P1 can be recycled. In addition, by switching the switching valve 207 to the second conveying path 204B while the path switching valve 201 is switched so that the conveying path 204 and the vacuum conveying device 167 are in communication, the recovered second water-absorbing polymer 4P can be conveyed to the vacuum conveying device 167 as the recovered second water-absorbing polymer 4P1, so that the recovered second water-absorbing polymer 4P1 can be recycled. In this case, when the recovered second water-absorbing polymer 4P1 is conveyed, the opening/closing valve 496 is closed, so that the recovery path 482 is blocked by the opening/closing valve 496, and the recovery box 472 and the storage tank 481 of the storage unit 48 can be spatially isolated. As a result, the same effect as that described in the above embodiment is achieved.

While the present invention has been described above based on its preferred embodiments, the present invention is not limited to the above-described embodiments and can be modified as appropriate without departing from the spirit of the present invention.
For example, the first absorbent core 3 does not have to have a non-forming material portion 3N, and even if the first absorbent core 3 has a non-forming material portion 3N, the number of such portions is not limited to the number in the embodiments.
In the above embodiment, the first absorbent core 3 is a pile of fibers including the fiber material 3F, the first water-absorbent polymer 3P, and the second water-absorbent polymer (recovered second water-absorbent polymer 4P1), but it may be composed of water-absorbent polymers like the second absorbent core 4. Even in this case, the second absorbent polymer 4P, which is prevented from falling and pulverized and atomized by the shutter 473 on the side intermittently supplied by the opening and closing operation of the shutter 473, i.e., in the manufacturing process of the second absorbent core, is re-supplied as the recovered second water-absorbent polymer 4P1 to the manufacturing process of the first absorbent core, thereby achieving the same effect as in the above embodiment.
When the particle size of the first absorbent polymer 3P used in the first absorbent core 3 is smaller than that of the second absorbent polymer 4P, the performance difference due to the difference in particle size between the two can be suppressed by making the particle size of the recovered second absorbent polymer 4P1 and the particle size of the first absorbent polymer 3P close to each other. As a result, it is expected that the performance deterioration of the first absorbent core 3 can be suppressed, which is preferable because it leads to more stable production of an absorbent body having the desired absorption performance.

In addition, in the above embodiment, a vacuum transport device 475 that utilizes positive pressure is used as the driving source of the resupply means 474 that transports the second absorbent polymer 4P from the accumulation section 48 to the first supply tank 63 as the recovered second absorbent polymer 4P1, but the driving source of the resupply means 474 may be a type that uses negative pressure to suck and transport the second absorbent polymer 4P from the accumulation tank 481.

Furthermore, in the above embodiment, the second absorbent polymer 4P stored in the storage tank 481 is transported as the recovered second absorbent polymer 4P1 to the manufacturing process of the first absorbent core (first supply tank 63) and recycled, but the method of recycling the second absorbent polymer 4P is not limited to this method. For example, depending on the degree of atomization of the second absorbent polymer 4P by pulverization, the second absorbent polymer 4P may be returned to the second supply tank 163 and reused in the manufacturing process of the second absorbent core, rather than being returned to the manufacturing process of the first absorbent core (first supply tank 63). Even in this case, it is preferable because the second absorbent polymer 4P removed by the shutter 473 can be recycled.

With respect to the embodiment of the present invention described above, the following method for manufacturing an absorbent body is further disclosed.

＜1＞
A method for producing an absorbent body, comprising: carrying out a manufacturing step of a first absorbent core containing a first water-absorbent polymer and a manufacturing step of a second absorbent core containing a second water-absorbent polymer in parallel; and laminating the first absorbent core and the second absorbent core thus obtained,
The process for producing the first absorbent core includes a continuous supply of a first water-absorbing polymer;
The manufacturing process of the second absorbent core includes a step of continuously supplying a second water-absorbent polymer while periodically removing the continuously supplied second water-absorbent polymer during the supply, thereby intermittently supplying the second water-absorbent polymer to a base sheet;
A method for producing an absorbent body, comprising recovering the second water-absorbent polymer removed in the step of producing the second absorbent core, and transporting the recovered second water-absorbent polymer to the continuous supply step in the step of producing the first absorbent core.

＜2＞
The manufacturing method according to <1> above, wherein the manufacturing process of the second absorbent core includes a step of intermittently supplying the second water-absorbent polymer between two long sheets continuously conveyed in the same direction.
＜3＞
In the manufacturing process of the first absorbent core, the first absorbent polymer is supplied from the first storage tank to the first supply tank, and the second absorbent polymer recovered and transported from the manufacturing process of the second absorbent core is supplied to the first supply tank, thereby continuously supplying a mixture of the first absorbent polymer and the second absorbent polymer from the first supply tank.
＜4＞
In the manufacturing process of the first absorbent core,
The manufacturing method described in <3> above, wherein in the first supply tank, the first absorbent polymer and the second absorbent polymer recovered in the manufacturing process of the second absorbent core are agitated and mixed with an air flow.
＜5＞
The manufacturing method described in <4> above, wherein the amount of the second absorbent polymer recovered in the manufacturing process of the second absorbent core and supplied to the first supply tank is 1/3 or less of the amount of the first absorbent polymer supplied to the first supply tank.
＜6＞
In the manufacturing process of the first absorbent core,
The manufacturing method according to any one of <1> to <5>, further comprising: defibrating a raw material sheet mainly composed of a fibrous material, and supplying the fibrous material into a duct.

＜７＞
The process for producing the second absorbent core includes a step of continuously dropping a second water-absorbing polymer through the opening;
The manufacturing method described in any one of <1> to <6> above, wherein the opening is periodically blocked by a blocking means, thereby periodically preventing the continuously falling second absorbent polymer from passing through the opening, thereby causing the second absorbent polymer to fall intermittently, and removing the second absorbent polymer that is prevented from passing through the opening.
＜8＞
In the manufacturing process of the second absorbent core,
The manufacturing method described in <7> above, wherein the second water-absorbing polymer, which is prevented from falling through the opening by the blocking means, slides down to the accumulation section and accumulates therein.
＜9＞
The manufacturing method described in any one of <1> to <8> above, wherein the second absorbent polymer recovered in the manufacturing process of the second absorbent core is entrained in a gas flow and transported to the continuous supply step in the manufacturing process of the first absorbent core.
＜10＞
A conveying means is provided below the hopper capable of storing the second water-absorbing polymer, and conveys the second water-absorbing polymer discharged from the discharge port of the hopper to a spraying position and sprays the second water-absorbing polymer;
The conveying means includes a receiving means for receiving the second water-absorbing polymer discharged from the discharge port, and a vibration generating means for vibrating the receiving means,
In the manufacturing process of the second absorbent core,
The manufacturing method according to any one of <1> to <9>, wherein the receiving means is vibrated by the vibration generating means, thereby transporting the second water-absorbing polymer on the receiving means to a spraying position.
<11>
The manufacturing method according to any one of <1> to <10> above, wherein the first water-absorbing polymer and the second water-absorbing polymer are made of the same kind of material.

＜12＞
The method for producing the first absorbent core according to any one of <1> to <11>, wherein in the step of producing the first absorbent core, neither the first nor the second water-absorbing polymer is removed.
＜13＞
When the second water-absorbing polymer is transported to the continuous supply step, the removal of the second water-absorbing polymer and the recovery of the second water-absorbing polymer are spatially separated.
＜14＞
In the recovery of the second water-absorbing polymer, the removed second water-absorbing polymer is stored in a storage tank.
＜15＞
The manufacturing method according to the above item <13> or <14>, wherein, each time the measurement time measured by the measuring means reaches a preset time, the second water-absorbing polymer is conveyed to the continuous supply step, and the removal of the second water-absorbing polymer and the recovery of the second water-absorbing polymer are spatially separated.
＜16＞
In the recovery of the second water-absorbing polymer, the removed second water-absorbing polymer is stored in a storage tank equipped with a sensor;
The manufacturing method according to any one of <13> to <15>, wherein the amount of the second water-absorbing polymer stored in the storage tank is detected by the sensor.

＜１７＞
The sensor is installed at an upper portion of the storage tank;
The sensor detects whether the second water-absorbing polymer in the storage tank has reached a planned storage amount;
When it is detected that the storage amount of the second absorbent polymer reaches a planned storage amount, the second absorbent polymer is transported to the continuous supply step at that time or after a certain time has elapsed, and the removal of the second absorbent polymer and the recovery of the second absorbent polymer are spatially separated.
＜18＞
the sensor is located near a top of the storage tank;
The sensor detects whether the second water-absorbing polymer in the storage tank has reached a storage limit amount;
The manufacturing method according to <16> or <17>, wherein, when it is detected that the storage amount of the second water-absorbing polymer has reached a storage limit amount, the operation is stopped at that time or after a certain time has elapsed.
＜19＞
The sensor is installed at a lower portion of the storage tank;
While conveying the second water-absorbing polymer in the storage tank, the sensor detects whether or not the amount of the second water-absorbing polymer stored in the storage tank has reached a minimum storage amount;
When it is detected that the storage amount of the second water-absorbing polymer has reached a minimum storage amount, the transport of the second water-absorbing polymer to the continuous supply step is stopped at that time or stopped after a certain time has elapsed, and the removal of the second water-absorbing polymer and the recovery of the second water-absorbing polymer are spatially connected to each other in the manufacturing method described in any one of <16> to <18>.
＜20＞
A valve is provided at the bottom of the storage tank to selectively select a transport path for the second water-absorbing polymer stored in the storage tank;
The second water-absorbing polymer stored in the storage tank is subjected to the continuous supply process or the discharge process to the outside of the storage tank by switching the valve.
＜21＞
In removing the second water-absorbing polymer, a sensor is placed near the opening,
a sensor detects whether the second water-absorbing polymer has properly passed through the opening;
The manufacturing method according to any one of <1> to <20>, wherein, when it is detected that the second absorbent polymer has not passed through the opening properly, the falling of the second absorbent polymer is stopped at that point or after a certain period of time has elapsed.

＜22＞
The manufacturing method according to any one of <13> to <21>, wherein a sensor installed in the transport path from the removal of the second absorbent polymer to the recovery of the second absorbent polymer detects whether or not the second absorbent polymer is clogged in the transport path.
＜23＞
An apparatus for manufacturing an absorbent body including a first absorbent core including a first water-absorbent polymer and a second absorbent core including a second water-absorbent polymer, the apparatus comprising:
a first water-absorbent polymer supply section that supplies a first water-absorbent polymer to the first absorbent core;
a second absorbent polymer supply section for supplying a second absorbent polymer to the second absorbent core;
a recovery means for periodically recovering the removed second water-absorbing polymer;
A re-supply means for conveying the second water-absorbing polymer recovered by the recovery means to the first water-absorbing polymer supply section;
An apparatus for manufacturing an absorbent body comprising:
＜24＞
The manufacturing apparatus described in <23>, wherein the re-supply means comprises a recovery path connecting a first supply tank provided in the first water-absorbing polymer supply section and a recovery box provided in the recovery means, and a vacuum conveying device provided in the first supply tank.
＜25＞
The manufacturing apparatus according to <24>, wherein a sensor is installed in the recovery path.
＜26＞
The re-supply means is configured to convey the second water-absorbing polymer to the first water-absorbing polymer supply section by entraining it in a gas flow. The manufacturing apparatus according to any one of <23> to <25>.

＜27＞
a second absorbent core comprising a second water-absorbing polymer and a base sheet;
The manufacturing apparatus according to any one of <23> to <26>, further comprising the recovery means between the second water-absorbing polymer spraying means and the base sheet transported below the second water-absorbing polymer spraying means.
＜28＞
The manufacturing apparatus according to any one of <23> to <27>, wherein the recovery means comprises a recovery box in which the second absorbent polymer is accumulated, a storage section in which the second absorbent polymer accumulated in the recovery box is recovered and stored, and an opening/closing valve that spatially isolates the recovery box from the storage section.
＜29＞
The manufacturing apparatus described in <28> above, wherein the recovery box is provided with an opening through which the continuously falling second water-absorbing polymer passes, and a blocking means for periodically blocking the opening.
＜30＞
The manufacturing apparatus according to <29>, further comprising a sensor disposed in the vicinity of the opening.
＜31＞
The manufacturing apparatus according to any one of <28> to <30>, wherein the recovery box is hollow and is arranged in a range including a falling position of the continuously falling second water-absorbing polymer.

＜32＞
The manufacturing apparatus according to any one of <28> to <31>, wherein the collection box is arranged so as to be inclined with respect to a falling direction of the second water-absorbing polymer.
＜33＞
The manufacturing apparatus described in <32>, wherein a lower end of the recovery box is tapered in the inclined direction.
＜34＞
The manufacturing apparatus according to any one of <28> to <33>, wherein the accumulation unit includes an accumulation tank, and the accumulation tank and the recovery box are connected by a recovery path.
＜35＞
The manufacturing apparatus according to any one of <28> to <34>, wherein the sensor is installed between the recovery box and the on-off valve.
＜36＞
The manufacturing apparatus described in any one of <28> to <35>, wherein a switching valve is installed at the bottom of the storage tank, which can alternatively select a transport path for the second absorbent polymer stored in the storage tank.

＜３７＞
The manufacturing apparatus according to any one of <28> to <36>, wherein the storage tank is provided with a sensor for detecting a storage state of the second water-absorbing polymer in the storage tank.
＜３８＞
The manufacturing apparatus according to <37>, wherein the storage tank has the sensor on an upper portion of the storage tank.
＜３９＞
The manufacturing apparatus according to <37>, wherein the storage tank has the sensor at a top portion of the storage tank.
＜40＞
The manufacturing apparatus according to <37>, wherein the storage tank has the sensor at a lower portion of the storage tank.
＜41＞
The manufacturing apparatus according to any one of <28> to <40>, wherein the second absorbent polymer stored in the storage tank is transported to the first absorbent polymer supply section by the resupply means.
＜42＞
The manufacturing apparatus according to any one of <23> to <41>, further comprising a control means including a central processing unit, a storage unit, and a measuring means.

＜43＞
An absorbent body in which a first absorbent core containing a first water-absorbing polymer and a second absorbent core containing a second water-absorbing polymer are laminated,
the second absorbent core has a portion along the longitudinal direction in which the abundance ratio of the second water-absorbent polymer is lower than that of the surrounding area;
At least a portion of the first water-absorbing polymer is composed of a water-absorbing polymer of the same quality as the second water-absorbing polymer;
An absorbent body, wherein the average particle size of the first water-absorbent polymer is smaller than the average particle size of the second water-absorbent polymer.
＜44＞
The absorbent body according to <43>, wherein the second absorbent core comprises two opposing base sheets and a second water-absorbing polymer interposed between the two base sheets.
＜45＞
The absorbent body according to <43> or <44>, wherein the second absorbent core has, in its front and rear end regions in the longitudinal direction, the region in which the abundance ratio of the second water-absorbent polymer is lower than that of the surrounding area.
＜46＞
The second water-absorbing polymer is spherical;
The absorbent body according to any one of <43> to <45>, wherein the first water-absorbing polymer in the first absorbent core contains a pulverized non-spherical water-absorbing polymer.
＜47＞
The absorbent body according to any one of <42> to <46>, wherein the second absorbent core is thinner than the first absorbent core 3.

＜48＞
The absorbent body according to any one of <43> to <47>, wherein the second absorbent core is in contact with a non-skin facing surface of the first absorbent core.
＜49＞
The first absorbent core is shorter than the second absorbent core in at least one of the length in the longitudinal direction and the length in the lateral direction,
An absorbent body as described in any one of <43> to <47>, wherein the peripheral portion of the surface of the second absorbent core on which the first absorbent core is placed is a portion where the first absorbent core is not placed and the second absorbent core 4 is exposed.
＜50＞
The first absorbent core is shorter in both the longitudinal and lateral directions than the second absorbent core;
The absorbent body according to any one of <43> to <49>, wherein the entire peripheral edge of the first absorbent core is located inward from the peripheral edge of the second absorbent core.
＜51＞
The absorbent body according to any one of <43> to <50>, wherein the first absorbent core has a longer length in the horizontal direction at one end side in the vertical direction than at the other end side.
＜52＞
The absorbent body according to any one of <43> to <51>, wherein the first absorbent core has a region along the longitudinal direction where the core-forming material of the first absorbent core is not present over the entire area in the thickness direction of the first absorbent core.
＜53＞
The absorbent body according to any one of <43> to <52>, wherein the length of the region in which the second water-absorbing polymer is present in the second absorbent core is greater than the length of the first absorbent core in the longitudinal direction.

Reference Signs List 1 absorbent body 2 absorbent core 3 first absorbent core 3F fibrous material 3N part where forming material is not present 3P first water-absorbing polymer 4S (4S1, 4S2) two base sheets 4P second water-absorbing polymer 4P1 recovered second water-absorbing polymer 10 absorbent body manufacturing device
20: Manufacturing section for first absorbent core 22: Duct 40: Manufacturing section for second absorbent core 43: Spreading means 47: Recovery means 63: First supply tank 431: Hopper 431a: Discharge port 432: Conveying means 433: Receiving means 471: Opening 472: Recovery box 473: Shutter

Claims (8)

An absorbent body in which a first absorbent core containing a first water-absorbing polymer and a second absorbent core containing a second water-absorbing polymer are laminated,
the second absorbent core has a portion along the longitudinal direction in which the abundance ratio of the second water-absorbent polymer is lower than that of the surrounding area;
At least a portion of the first water-absorbing polymer is composed of a water-absorbing polymer of the same quality as the second water-absorbing polymer;
The average particle size of the first water-absorbing polymer is smaller than the average particle size of the second water-absorbing polymer;
An absorbent body, wherein the first water-absorbent polymer comprises a ground non-spherical water-absorbent polymer. The absorbent body according to claim 1, wherein the second absorbent core comprises two opposing base sheets and a second water-absorbing polymer interposed between the two base sheets. The absorbent body according to claim 1 or 2, wherein the second absorbent core has a region in its front and rear end regions in the longitudinal direction where the content of the second water-absorbent polymer is lower than that of the surrounding area. 4. The absorbent body according to claim 1, wherein the second water-absorbing polymer is spherical. An apparatus for manufacturing an absorbent body including a first absorbent core including a first water-absorbent polymer and a second absorbent core including a second water-absorbent polymer, the apparatus comprising:
a first water-absorbent polymer supply section that supplies a first water-absorbent polymer to the first absorbent core;
a second absorbent polymer supply section for supplying a second absorbent polymer to the second absorbent core;
a recovery means for periodically recovering the removed second water-absorbing polymer;
A re-supply means for conveying the second water-absorbing polymer recovered by the recovery means to the first water-absorbing polymer supply section;
An apparatus for manufacturing an absorbent body comprising: The manufacturing apparatus according to claim 5, wherein the resupply means comprises a recovery path connecting a first supply tank provided in the first water-absorbent polymer supply section and a recovery box provided in the recovery means, and a vacuum conveying device provided in the first supply tank. The manufacturing device according to claim 6, wherein a sensor is installed in the recovery path. The manufacturing apparatus according to any one of claims 5 to 7, wherein the resupply means is configured to transport the second water-absorbing polymer to the first water-absorbing polymer supply section by entraining it in a gas flow.

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