JP4786758B2 - Method for thinning a collection of water-absorbing materials and a collection of thin water-absorbing materials obtained by the method - Google Patents

Description

  The present invention relates to a method for thinning an aggregate of water-absorbent materials that can be used as a water-absorbent core material in disposable body fluid treatment articles such as disposable diapers, sanitary napkins, and urine absorbing pads, and the thickness obtained by the method. The present invention relates to an assembly of thin water-absorbing materials.

  It is well known to use aggregates of water-absorbing materials including pulverized pulp and other hydrophilic fibers as water-absorbing core materials in disposable body fluid treatment products, including hydrophilic fibers and highly water-absorbing polymer particles. It is also well known to use aggregates of water-absorbing materials. In addition, since the core material containing the hydrophilic fiber tends to be bulky, it is well known or known to use the core material by compressing the core material in the thickness direction to make the core material thin. .

FIG. 16 is a diagram showing one conventional example of a process for producing a water-absorbent core material. In the illustrated process, a second web 524, which is a continuous body of tissue paper, is supplied to the peripheral surface 551a of the suction roll 551 from the upstream in the machine direction MD. Suction 556 acts on the peripheral surface 551a toward the center of the suction roll 551. The second web 524 enters the water absorbent material supply portion 552 and is sucked into the concave portion 553 formed in the peripheral surface 551 a by the action of the suction 556 of the roll 551. Further, in the supply portion 552, the ground pulp 521 and the highly water-absorbing polymer particles 522 are accumulated inside the concave portion 553 by the action of the suction 556 to form a water-absorbing material aggregate 560. The assembly 560 exiting the supply unit 552 is sandwiched by a first web 523 which is a continuous body of tissue paper supplied from above and a second web 524 on which the assembly 560 is placed, so that the first composite web is sandwiched. It becomes 561 and proceeds in the machine direction MD, and is compressed by a pair of press rolls 550 to become a second composite web 562 having a required thickness. The thickness is adjusted by changing the gap between the pair of press rolls 550. The second composite web 562 that has passed through the press roll 550 is cut between the adjacent assemblies 560 to form individual water-absorbing core members 513.

  The core material of the disposable diaper in the invention described in US Pat. No. 3,938,522 (Patent Document 1) contains pulverized pulp, and the pulverized pulp running in the machine direction as a web is calender roll. After being compressed, the water is sprinkled and again compressed with a calendar roll.

The invention described in Japanese Patent No. 2512415 (Patent Document 2) is an air-made dry mixture of hydrophilic fibers and discrete particles of a hydrogel of a water-insoluble cross-linked polymer, about 0.15 to An absorbent structure having a density of 1 g / cm ³ , a water content of less than about 10% by weight and a Gurley stiffness value of less than 2 g, is flexible and substantially unbonded. is there. According to the method for producing an absorbent structure according to the present invention, the dry mixture of air-made hydrophilic fibers and water-insoluble hydrogel particles can be compressed until the density is about 0.15 to 1 g / cm ^3. is necessary.

U.S. Pat. No. 3,938,522 Japanese Patent No. 2512415

  If the collection of water-absorbing materials used in body fluid treatment products contains hydrophilic fibers, they tend to be thick, so wear the body fluid treatment product with the assembly as thin as possible. It is preferable to have a good wearing feeling that is not bulky. However, when the aggregate is compressed to the required thickness according to the prior art, the aggregate is reduced to a thickness much smaller than the required thickness, taking into account the thickness recovery after compression. Must be compressed. If the aggregate contains superabsorbent polymer particles when compressed in such a manner, the shape of the superabsorbent polymer particles collapses, exposing the polymer component having a low crosslink density inside the particles, and absorbing water. In some cases, the highly water-absorbing polymer particles easily form a gel block. The aggregate in which the gel block is formed may not function as a water-absorbing material because the superabsorbent polymer particles confined in the gel block cannot contact the body fluid. In some cases, the core material containing the body significantly reduces the amount of absorbed body fluid and the absorption rate. Not only that, excessive compression on the aggregate may cause the hydrophilic fibers or the hydrophilic fibers and the superabsorbent polymer particles to adhere to each other in a part of the aggregate to form a particularly dense part. For this reason, the core material may become uneven in flexibility and water absorption.

  An object of the present invention is to provide a novel method for thinning an aggregate of water-absorbing materials including hydrophilic fibers and highly water-absorbing polymer particles, and to provide a thin water-absorbing material obtained by the method. The provision of aggregates.

  The present invention for solving the above-described problems includes a first invention relating to a method for reducing the thickness of an aggregate of water-absorbing materials, and an aggregate of water-absorbing materials manufactured by the method and having a reduced thickness. And the second invention according to the present invention.

  The first invention is directed to a method in which an aggregate of water-absorbing materials including hydrophilic fibers and highly water-absorbing polymer particles has a thickness direction, and the aggregate is thinned in the thickness direction. is there.

In such a method, the first invention is characterized in that the aggregate is used in a disposable body fluid treatment article, and includes pulverized pulp as the hydrophilic fiber, and the aggregate is treated with a breathable sheet and a breathable sheet. A composite containing at least one of the air permeable sheet and the air permeable liquid permeable sheet and the aggregate is formed by sandwiching with one of the liquid sheets, and is opposed in the thickness direction of the aggregate. The composite is interposed between a pair of flexible breathable supports, and the composite is compressed by the pair of breathable supports, and the first is one of the pair of breathable supports. a permeable support body temperature the complex of water higher than the boiling point through the high pressure steam vapor pressure of 0.1 to 2.0 MPa, the composite arranged at a pitch of 0.5~10mm Traversed, by injecting in the thickness direction from a plurality nozzles having a diameter of 0.1 to 2 mm, thinning the aggregate without collapse of the superabsorbent polymer particles, in.

In one embodiment of the first invention, the high-pressure steam is one of wet steam, saturated steam, and dry steam.

In another embodiment of the first invention, the high-pressure water vapor that has been sprayed onto the composite and passed through the composite is sucked by the action of vacuum pressure.

In another one of the embodiments of the first invention, the pair of breathable supports are opposed to the one of the pair of breathable supports while running in one direction at a speed of 5 to 500 m / min. the high pressure steam for injecting a range of 1.23kg ^{/ m 2} ~0.03kg ^/ m 2 of the surface area of the complex.

In another one of the embodiments of the first invention, in the one direction, the pair of breathable supports are in a horizontal direction and a vertical direction in a state where the composite is interposed between the two supports. And the site | part which drive | works in either direction of the inclined direction between these both directions is contained .

According to still another embodiment of the first invention, a 10 to 75 plain weave mesh belt mesh using at least a first breathable support a polyolefin sulfide resin of the pair of permeable support member.
In one embodiment of the first invention, each of the pair of breathable supports is an endless belt.

In another embodiment of the first invention, the composite is mechanically compressed in the thickness direction to preliminarily thin the composite, and then the composite is joined to the pair of breathable supports. The high-pressure steam is jetted onto the composite while being compressed by the above.

In another embodiment of the first invention, the composite is thinned in advance by mechanically compressing the composite using at least a pair of press rolls.

  In another embodiment of the first invention, the aggregate includes 98 to 10% by weight of the hydrophilic fibers and 2 to 90% by weight of the superabsorbent polymer particles.

  In another embodiment of the first invention, the superabsorbent polymer particles are polyacrylic acid, polyacrylic acid salt, starch acrylonitrile graft copolymer, polyvinyl alcohol, polyvinyl ether, polyacrylamide, carboxymethylcellulose, natural Any particle of polysaccharide.

  In another one of the embodiments of the first invention, one of the breathable sheet and the breathable liquid-permeable sheet is either tissue paper or nonwoven fabric.

Among the inventions, the second invention is characterized in that the water-absorbing material manufactured by the method according to the first invention, having a reduced thickness, is used for disposable body fluid treatment products . It is in a collection of materials.

According to the method for thinning the aggregate of water-absorbing material according to the present invention and the aggregate of the thin water-absorbing material obtained by the method, the composite containing the aggregate of the water-absorbing material is compressed. Since high-pressure water vapor having a temperature equal to or higher than the boiling point of water is jetted onto the composite, the entire water-absorbing material aggregate in the thickness direction is quickly heated / humidified or heated to Can be thinned. The hydrophilic fibers in the aggregate when high-pressure steam is injected are easily deformed without being compressed at a high pressure, and are unlikely to return to the original shape. Aggregates containing such hydrophilic fibers also quickly become thin and do not return to their original thickness. When compressing the composite containing the aggregate, it is also possible to prevent the shape of the superabsorbent polymer particles contained in the aggregate from collapsing. The aggregate of thin water-absorbing materials that can prevent the collapse of the shape of the superabsorbent polymer particles is difficult to form a gel block even if the superabsorbent polymer particles absorb water. Can be prevented from occurring.

The partial fracture top view of a disposable diaper. The figure which shows the II-II line | wire cut surface of FIG. The figure which shows an example of the manufacturing process of the core material containing the aggregate | assembly of a water absorbing material. The figure which shows another example of the manufacturing process of a core material. The figure which shows the measuring method of weighted absorption rate. The figure which shows the undulation state of the surface of the aggregate | assembly of the water absorbing material in an Example. The figure which shows the undulation state of the surface of the aggregate | assembly of the water absorbing material in a comparative example. The figure which shows distribution of the height from the reference surface in an aggregate | assembly of the water absorbing material of an Example and a comparative example to an upper surface. The photograph which expanded the surface of the aggregate of the water absorptive material in an example 50 times. The photograph which expanded the surface of the aggregate of the water absorptive material in an example 100 times. The photograph which expanded the surface of the aggregate of the water absorbing material in a comparative example 50 times. The photograph which expanded the surface of the aggregate of the water-absorbing material in a comparative example 100 times. The figure which shows the relationship between absorption time and specific volume. The figure which shows the relationship between weighted absorption time and specific volume. The figure which shows the relationship between a ventilation resistance index and a specific volume. The figure which shows the prior art example of a core material manufacturing process.

  The method for thinning the aggregate of water-absorbing materials according to the present invention with reference to the accompanying drawings, and the details of the aggregate of water-absorbing materials manufactured by the method and having a reduced thickness will be described below. It is as follows.

  FIG. 1 is a partially cutaway plan view of an open-type disposable diaper 1 in which an example of a thin water-absorbing material aggregate according to the present invention is used as a body fluid-absorbing core material 13. The diaper 1 has a longitudinal direction A and a width direction B orthogonal to each other, a rectangular chassis 2 formed to be long in the longitudinal direction A, and attached to a front portion of the chassis 2 and extending in the width direction B. A pair of front wings 3 and a pair of rear wings 4 attached to the rear portion of the chassis 2 and extending in the width direction B are included. In the front-rear direction A of the chassis 2, a crotch region 6 is formed between the front wing 3 and the rear wing 4. A front waistline region 7 is formed in front of the crotch region 6. A rear waistline region 8 is formed.

  The chassis 2 includes a liquid-permeable top sheet 11, a liquid-impermeable back sheet 12, and a body fluid-absorbing core material 13 interposed between the two sheets 11 and 12, and the back sheet 12 is a non-woven fabric with a good touch. The outer sheet 14 is made of a metal. The top sheet 11 and the back sheet 12 extend from the peripheral edge portion 51 of the core member 13 and overlap each other, and are joined via a hot melt adhesive 41a. The top sheet 11, the back sheet 12, and the outer sheet 14 form both side edge portions 18 and front and rear end edge portions 21 and 22 of the chassis 2 at portions extending from the core member 13. Each of the side edges 18 is formed with a breakwater 31 by a sheet piece that is long in the front-rear direction A. The breakwater 31 is bonded to the side edge 18 via the hot melt adhesive 32a and to the front edge 21 via the hot melt adhesive 32b. The top sheet 11 is located inside the chassis 2 with respect to the front edge 34, the rear edge 36 joined to the rear edge 22 via the hot melt adhesive 32c, and the base 33. And a free edge portion 37 which overlaps with the elastic member 39 in a stretched state via a hot melt adhesive (not shown) inside a sleeve 38 formed on the free edge portion 37. Yes.

  Further, at both side edges 18 of the chassis 2, leg elastic members 41 extending in the front-rear direction A are located between the outer sheet 14 and the base edge 33 of the leakage breaker 31, and the outer sheet via the hot melt adhesive 41 a. 14 is attached. At the front edge 21 of the chassis 2, a front waistline elastic member 42 extending in the width direction B is provided between the top sheet 11 and the back sheet 12, and a hot melt adhesive is applied to at least one of these sheets 11, 12. (Not shown). At the rear end edge 22 of the chassis 2, a rear waistline elastic member 43 extending in the width direction B is located between the top sheet 11 and the back sheet 12, and hot melt bonding is performed on at least one of the sheets 11 and 12. It joins via the agent (not shown).

  The chassis 2 thus formed has a front wing 3 attached to a side edge 18 in the front waist area 7 so as to extend in the width direction B, and a side edge in the rear waist area 8. A rear wing 4 is attached to 18 so as to extend in the width direction B. A tape fastener 46 is attached to the rear wing 4. When the diaper 1 is worn, the tape fastener 46 extends in the width direction B as indicated by the phantom line, and uses the adhesive 47 applied to the inner surface of the tape fastener 46 to apply the outer surface or front of the chassis 2. It can be fixed to the outer surface of the wing 3 in a peelable manner.

FIG. 2 is a diagram showing a cut surface of the core material 13 along the line II-II in FIG. 1, and the thickness direction of the core material 13 is indicated by a double-headed arrow C. FIG. The line II-II in FIG. 1 coincides with the center line MM that bisects the size of the chassis 2 in the front-rear direction A. The core material 13 has an air-permeable and liquid-permeable upper surface on the upper and lower surfaces of the compressed aggregate 20 in a state in which the water-absorbing material including the hydrophilic fibers 21 and the highly water-absorbing polymer particles 22 is compressed and thinned. This is a composite of the compressed aggregate 20, the upper surface sheet 23, and the lower surface sheet 24 formed by covering with the sheet 23 and the breathable lower surface sheet 24.

  The hydrophilic fiber 21 occupies 98 to 10% by weight of the compressed aggregate 20, and the hydrophilic fiber 21 includes, for example, natural fibers such as pulverized pulp and cotton fibers, semi-synthetic fibers such as rayon fibers, and hydrophilicity. A processed thermoplastic synthetic fiber or the like, and a short fiber having a fiber length of 2 to 80 mm is used. The hydrophilic fiber 21 can be replaced with a hydrophobic thermoplastic synthetic fiber having a fiber length of 20 to 80 mm and not hydrophilized, with a limit of 15% of the weight of the compressed aggregate 20, In some cases, the diffusion property of body fluid in the compressed aggregate 20 can be improved by the thermoplastic synthetic fiber.

  The superabsorbent polymer particles 22 occupy 2 to 90% by weight of the compressed aggregate 20 and are acrylic acid, acrylate, starch acrylonitrile graft copolymer, polyvinyl alcohol, polyvinyl ether, polyacrylamide, carboxymethylcellulose, natural Known or well-known polymer particles such as polysaccharides can be used. Generally known shapes of these polymers include non-spherical shapes other than spherical shapes, fibrous shapes, etc., and any shape can be used as long as it can be mixed with the hydrophilic fibers 21. The water-absorbing polymer particles 22 can be used. That is, the superabsorbent polymer particle 22 in the present invention means a superabsorbent polymer having a shape that can be mixed with the hydrophilic fiber 21. In the present invention, when the superabsorbent polymer particles 22 can be mixed with the hydrophilic fibers 21, the superabsorbent polymer particles 22 can be mixed with the hydrophilic fibers 21 in addition to the superabsorbent polymer particles 22. In the compressed aggregate 20 of the water-absorbing material, in other words, in the core material 13 of FIG. 2, the case where the particles 22 are unevenly distributed in any part in the front-rear direction A, the width direction B, and the thickness direction C is included.

The top sheet 23 is used so as to face the top sheet 11, and the bottom sheet 24 is used so as to face the back sheet 12. The top sheet 23 and the bottom sheet 24 have a basis weight which is a mass per unit area. there a 10 to 30 g / tissue paper and a basis weight of m ² is 5 to 40 g / m ² nonwoven, breathable sheet material is easy permeation of later steam or air permeable and liquid-permeable sheet, Material is used. For example, the top sheet 23 is required to be breathable and liquid permeable so that the body fluid can be easily transferred from the top sheet 11 to the compressed assembly 20. On the other hand, the lower surface sheet 24 can suppress the transfer of body fluid from the compressed assembly 20 toward the back sheet 12 in addition to the case of the air permeable and liquid permeable material in the same manner as the upper surface sheet 23. In addition, it may be required to be liquid-permeable or non-liquid-permeable than the top sheet 23. The upper surface sheet 23 and the lower surface sheet 24 extend from the peripheral edge of the compressed assembly 20 and overlap each other, and act so that the compressed assembly 20 can maintain its shape.

  FIG. 3 is a diagram showing an example of a process when manufacturing the compressed assembly 20 and the core material 13 including the compressed assembly 20 based on the method according to the present invention. In FIG. 3, the machine direction MD, which is the flow direction of each material, and the up-down direction TD, which is a direction corresponding to the thickness direction C of the core material 13 and orthogonal to the machine direction MD, are indicated by arrows. A direction orthogonal to the machine direction MD and the up-down direction TD is a cross direction CD (not shown). 3 includes first to fifth steps 101 to 105. In the first step 101 located on the upstream side in the machine direction MD, it is a continuous body of the lower surface sheet 24 in FIG. Alternatively, the second sheet web 224 that is air permeable and liquid permeable is continuously supplied in the machine direction MD using the transport roll 200 that rotates in the machine direction MD.

  The second step 102 includes a suction drum 151 that rotates in the machine direction MD, and a hooded water-absorbing material supply unit 152 that is formed so as to cover the suction drum 151. On the peripheral surface 151a of the suction drum 151, concave portions 153 having a shape substantially matching the planar shape of the core member 13 are formed at a required pitch in the circumferential direction. When the suction drum 151 rotates and the recess 153 enters the supply unit 152, the suction 156 due to vacuum pressure acts on the recess 153. The supply part 152 is a part which supplies the water absorbing material in this invention with respect to the suction drum 151, Comprising: The pulverized pulp supply part 157 for supplying the pulverized pulp 21a as the hydrophilic fiber 21 which comprises a water absorbing material. And a superabsorbent polymer particle supply part 158 for supplying superabsorbent polymer particles 22 of the constituents of the superabsorbent material, and pulverized pulp 21a toward the recess 153 entering the supply part 152 And the superabsorbent polymer particles 22 can be supplied so as to form a mixed state or a laminated state. The second sheet web 224 that has advanced from the first step 101 is placed on the peripheral surface 151 a of the suction drum 151 and enters the supply unit 152, and is deformed to follow the shape of the recess 153 under the action of the suction 156. Then, the surface of the recess 153 is covered. After the recess 153 is covered with the second sheet web 224 in this way, the pulverized pulp 21a and the superabsorbent polymer particles 22 are supplied. The hooded supply unit 152 is formed in a closed structure so that the suction 156 works effectively, but between the peripheral surface 151a of the suction drum 151, the advancement of the second seat web 224, A gap is formed to allow the water-absorbing material assembly 160 to be described later to advance.

In the third step 103, the second sheet web 224 placed on the transport roll 200 moves away from the peripheral surface 151a of the suction drum 151 in the machine direction MD. On the second sheet web 224, the aggregates 160 of the water-absorbing material that have a shape following the recess 153 and are in an uncompressed state are arranged intermittently in the machine direction MD. The aggregate 160 is formed by the pulverized pulp 21a and the superabsorbent polymer particles 22 that are supplied to and accumulated in the recesses 153 in the second step 102. In the third step 103, the first sheet web 223 that is a continuous body of the upper surface sheet 23 and is air permeable or air permeable and liquid permeable is continuously supplied from above in the drawing and cooperates with the second sheet web 224. Thus, the assembly 160 is sandwiched, and the assembly 160 that is intermittently aligned with the first sheet web 223 and the second sheet web 224 forms a first composite 161 .

The fourth step 104 in FIG. 3 includes a breathable first and second mesh conveyor belts 171 and 172, a steam injection unit 173, and a steam suction unit 174 arranged vertically so as to form a pair in the drawing. Contains. The pair of first and second mesh conveyor belts 171 and 172 cause the first composite 161 including the assembly 160 to travel in the machine direction MD while being compressed in the thickness direction of the assembly 160 which is the vertical direction D in the figure. for, a permeable supporting member for assembly 160 and the first complex 161, the parallel running portion 175 supports these, for example, 5 to 500 m / min speed parallel to the machine direction MD each other Running. The first and second mesh conveyor belts 171 and 172 have a gap between the upstream upper roll 176 and the upstream lower roll 177 rotating in the machine direction MD, and a gap between the downstream upper roll 178 and the downstream lower roll 179. By adjusting, the dimension of the gap d in the vertical direction TD in the parallel traveling portion 175 can be set to a required value. With the first and second mesh conveyor belts 171 and 172 having such dimensions set, the assembly 160 and the first composite 161 in the fourth step 104 can be compressed to a required thickness. In the drawing, a steam traveling unit 175 and a steam suction unit 174 are arranged on the parallel running unit 175 extending horizontally so as to face each other with the pair of first and second mesh conveyor belts 171 and 172 interposed therebetween. For example, nozzles (not shown) having a diameter of 0.1 to 2 mm are provided in the steam injection unit 173 at a pitch of 0.5 to 10 mm, more preferably 0.5 to 5 mm, and still more preferably 0.5 to 3 mm . 1 are arranged in a crossing direction CD (not shown) orthogonal to the machine direction MD and the vertical direction TD so as to cross the composite 161 , and each nozzle has a boiling point equal to or higher than the boiling point of water generated in the steam boiler 180. The water vapor having the temperature is supplied through the pipe 182 as high-pressure water vapor adjusted to a vapor pressure of, for example, 0.1 to 2.0 MPa by the pressure control valve 181. From each nozzle, the high-pressure steam (not shown) is passed through the first mesh conveyor belt 171 to the first composite 161 in a state compressed by the first and second mesh conveyor belts 171 and 172. Is injected. The amount of water vapor sprayed onto the assembly 160 included in the first composite 161 is an amount adjusted according to the traveling speed of the first and second mesh conveyor belts 171 and 172, and For the assembly 160 when the second mesh conveyor belts 171 and 172 are traveling at 5 to 500 m / min, the assembly facing the first mesh conveyor belt 171 via the first sheet web 223. it is preferred to injection in the range of 1.23kg ^{/ m 2} ~0.03kg ^/ m 2 of the surface area of 160. In the thickness direction C of the assembly 160, the water vapor sequentially passes through the first mesh conveyor belt 171, the first composite 161 , and the second mesh conveyor belt 172, and is subjected to vacuum pressure suction by the steam suction unit 174. Recovered under action. The first composite 161 injected with water vapor proceeds in the machine direction MD, is separated from the first and second mesh conveyor belts 171 and 172, becomes the second composite 162, and proceeds to the fifth step 105.

In the fourth step 104, the first and second mesh conveyor belts are used to prevent the first composite 161 from being locally compressed by the first and second mesh conveyor belts 171 and 172. For at least one of 171, 172, a flexible one that can be easily deformed in the vertical direction TD can be used. For the first and second mesh conveyor belts 171 and 172, a metal wire mesh belt formed of stainless alloy or bronze, or a plastic mesh belt formed of polyester fiber or aramid fiber may be used. In addition, a metal belt formed of a perforated metal plate can be used instead of the mesh belt. When the aggregate 160 or the like extremely dislikes the mixing of metal powder, it is preferable to use a plastic mesh belt. Further, when a plastic mesh belt is required to have high heat resistance, it is preferable to use a mesh belt made of polyphenylene sulfide resin. The 10-75 mesh plain weave mesh belt using polyphenylene sulfide resin is flexible and can be used for both the first mesh conveyor belt 171 and the second mesh conveyor belt 172. It is an example. In the fourth step 104, it is preferable to take appropriate heat retention measures or provide a drain discharge mechanism in the steam injection portion 173 and the pipe 182. By doing so, the drain generated in the steam injection unit 173 or the like is ejected from the nozzle and excessive moisture is contained in the first composite 161 , or the first when the tissue paper is formed. It is possible to prevent the seat web 223 from being damaged. The water vapor sprayed toward the first composite 161 may be dry steam that does not include liquid components that are moisture, may be saturated steam, or may be wet steam that includes liquid components. When the water vapor is wet vapor or saturated vapor, the hydrophilic fibers 21 can be easily wetted and deformed. If the hydrophilic fiber 21 is the fluff pulp 21a, the dry steam can vaporize the water contained in the fluff pulp 21a, and the hydrophilic fiber 21 can be easily deformed by the vaporized water. . In addition, if the hydrophilic fiber 21 is a thermoplastic synthetic fiber, the thermoplastic synthetic fiber can be easily deformed by the heat of dry steam. The steam injection unit 173 may be provided with a heating mechanism to change the steam into superheated steam and spray it. It is preferable that the steam suction unit 174 has a pipe that allows the sucked high-pressure steam to go to an exhaust blower (not shown) after passing through the steam separator. In the present invention, the positions of the steam injection part 173 and the steam suction part 174 in the fourth step 104 are switched, that is, the steam injection part 173 is on the lower side and the steam suction part 174 is on the upper side in FIG. It can also be implemented in an embodiment. Further, in the fourth step 104, when it is not necessary to recover the high-pressure steam that has passed through the first complex 161 , the present invention can be implemented without disposing the steam suction 174.

In the fifth step 105, the second composite 162 separated from the first and second mesh conveyor belts 171 and 172 is placed on the transport roll 200 and travels in the machine direction MD. Cut between the bodies 160 to form individual core members 13. However, the assembly 160 becomes the compression assembly 20 (see FIG. 2) that is compressed by the first and second mesh conveyor belts 171 and 172 and the water vapor to reduce the thickness, and the first and second sheet webs 223 are formed. , 224 become the upper and lower surface sheets 23, 24 in the core material 13. Although not shown, in the fifth step 105, the second composite 162 is wound into a roll shape to form a continuous body of the core material 13, and the continuous body may be supplied to a production line for disposable diapers. it can. In the fifth step 105, an apparatus for drying the second composite 162 may be provided.

The compressed aggregate 20 in the core material 13 of FIG. 2 obtained through the process of FIG. 3 is a first assembly of the water absorbent material aggregate 160 that is a mixture of the hydrophilic fibers 21 and the highly water absorbent polymer particles 22. Since the high-pressure steam is jetted onto the aggregate 160 while being compressed by the mesh conveyor belt 171 and the second mesh conveyor belt 172, the pulverized pulp 21a, for example, the hydrophilic fiber 21, is heated and humidified. Or it deform | transforms rapidly in a heating state, loses the repulsive force with respect to the compression force by the 1st, 2nd mesh conveyor belts 171 and 172, and tends to have a shape close to the shape when compressed. Further, the hydrophilic fibers 21 are easily accessible by the action of moisture in the water vapor, and the shape when the hydrophilic fibers 21 are compressed is easily maintained by the interaction of the adjacent hydrophilic fibers 21. It becomes possible. In addition, compared with the case where the first composite 161 is sprayed with water according to the prior art and then the first composite 161 is compressed with a press roll or the like, the high-pressure steam used in the present invention is the first composite Since passing through 161 is much easier than sprayed water, the entire assembly 160 in the thickness direction can be quickly heated and humidified. According to the process of FIG. 3 in which high-pressure steam is utilized in this way, the gap d between the first and second mesh conveyor belts 171 and 172 for obtaining the second composite 162 from the first composite 161 It is possible to obtain the second composite 162 having the required thickness by setting the value close to the thickness required for the second composite 162 without excessively reducing the thickness.

The ratio between the thickness of the second composite 162 and the gap d is a value that means the thickness recovery rate r after compression of the first composite 161 , and the recovery rate r is the first composite 161. The degree of the effect of the high-pressure steam in the fourth step 104 with respect to the compression of. That the recovery rate r is close to 1 means that the thickness of the second composite 162 is close to the gap d. According to the present invention using the fourth step 104, the recovery rate r tends to be close to 1. On the other hand, when the first composite 161 is to be thinned only by being compressed with a press roll as in the prior art, or when the first composite 161 is to be thinned by being sprayed with water after being sprayed on the first composite 161 The recovery rate r tends to be a value much larger than 1. For example, in the conventional technique in which the first composite 161 is thinned to a required thickness only by compressing with a press roll, the gap d must be set to a value much smaller than the required thickness. Due to such a difference between the present invention and the prior art, in the present invention, the occurrence of the problem that the superabsorbent polymer particles 22 are collapsed by excessively compressing the aggregate 160 and the first composite 161 of the water absorbent material. Can be prevented.

Moreover, in this invention, when the process of FIG. 3 which compresses the 1st composite body 161 using high pressure water vapor | steam and the flexible 1st, 2nd mesh conveyor belts 171 and 172 is adopted, water-absorbing material Even if the aggregate 160 has a locally thick portion, the compressive force due to water vapor and the compressive force due to the first and second mesh conveyor belts 171 and 172 are concentrated on the particularly thick portion. There is nothing. For example, when the aggregate 160 has a portion where the superabsorbent polymer particles 22 are unevenly distributed, and the thickness of the aggregate 160 in the portion is particularly thick due to the presence of the superabsorbent polymer particles 22, this water absorbency. When the first composite 161 including the material assembly 160 is compressed with a press roll, the compressive force of the press roll is concentrated on the thickened portion, and the particle shape of the highly water-absorbing polymer particles 22 is collapsed, There may be a problem that the water-absorbing polymer particles 22 and the hydrophilic fibers 21 are strongly adhered, or the hydrophilic fibers 21 are excessively adhered to each other. However, when the first and second mesh conveyor belts 171 and 172 are used to compress the first composite 161 so that its thickness does not become extremely thin, water vapor is sprayed onto the first composite 161. Since the compressive force can be prevented from concentrating on a particularly thick part of the first composite 161, it is possible to prevent the occurrence of the problem of collapsing the shape of the superabsorbent polymer particles 22, However, it is possible to obtain a flexible core 13 having a high absorption rate.

  Incidentally, when the shape of the superabsorbent polymer particle 22 is, for example, spherical, a polymer component having a low crosslink density inside the particle may be exposed due to the collapse of the shape, which means that the highly absorbed polymer This is a cause of facilitating the formation of gel blocks by the water-absorbing polymer particles 22. The highly water-absorbing polymer particles 22 confined inside the gel block have almost no opportunity to come into contact with body fluids, and thus cannot function as a water-absorbing material. In addition, the formation of the gel block changes the superabsorbent polymer particles 22 from a small particle size to a large particle size. Therefore, the formation of the gel block lowers the original water absorbing ability of the aggregate 160 of the water absorbent material or makes the aggregate 160 poor in flexibility. It is not preferable that the shape of this is collapsed. In addition, when the superabsorbent polymer particles 22 and the hydrophilic fibers 21 are in close contact with each other and the fibers 21 may cover the surfaces of the particles 22, the fibers 21 are separated from the superabsorbent polymer particles 22 and body fluid. This makes it difficult to quickly absorb water in the highly water-absorbing polymer particles 22, so that the core material 13 cannot quickly use the highly water-absorbing polymer particles 22 for water absorption. Furthermore, excessively close contact between the hydrophilic fibers 21 delays the entry of moisture to be absorbed between the fibers, thereby reducing the water absorption rate of the aggregate 160.

The process of FIG. 3 according to the present invention can be partially modified. For example, the first composite 161 can be supplied to the fourth step 104 on a conveyor belt instead of the transport roll 200. Further, the second composite 162 can be supplied in the machine direction MD on the conveyor belt instead of the transport roll 200. The process of FIG. 3 also supplies the first sheet web 223 in the machine direction MD instead of the second sheet web 224 in the first process 101, and the second process instead of the first sheet web 223 in the third process 103. A sheet web 224 can be fed in the machine direction MD. In the illustrated example, the second sheet web 224 and the first and second composite webs 161 running horizontally in the machine direction MD in the first step 101, the third, fourth, and fifth steps 103, 104, and 105 are also shown. , 162 can make a part of the traveling process vertical or inclined. These changes may be appropriately selected in consideration of the space of the factory where the process of FIG. 3 is to be performed.

FIG. 4 is a process diagram similar to FIG. 3 illustrating the embodiment of the present invention. Only the third process 103 is different from the process of FIG. In the third step 103 of FIG. 4, a pair of first press rolls 401a and 401b and a pair of second press rolls 402a and 402b for lightly compressing the first composite 161 in advance by mechanical means are provided. Is provided. A pair of first press roll 401a, a roll gap _{e 1} and a pair of second rolls 402a of 401b, the roll gap _{e 2} of 402b, the first first complex 161 is a pair, the second mesh conveyor belts 171 and 172 It is set so that the 1st composite 161 can be compressed to such an extent that it can enter smoothly. The lower limits of the gaps e ₁ and e ₂ are set so as not to be smaller than the gap between the upstream upper roll 176 and the upstream lower roll 177 in the fourth step, and the first press rolls 401a and 401b. In addition, excessive compression of the first composite 161 by the second press rolls 402a and 402b is avoided. By doing so, collapse of the shape of the superabsorbent polymer particles 22 contained in the aggregate 160 is prevented. The first composite 161 that has exited the second step 102 in FIG. 3 tends to increase in volume as the content ratio of the hydrophilic fibers 21 increases, and the first composite 161 that has a larger volume has a smaller gap d. When entering between the first and second mesh conveyor belts 171 and 172, the assembly 160 receives a force in the direction in which the assembly 160 is pushed back to the upstream side in the machine direction MD, and the shape of the assembly 160 of the water absorbent material is distorted. There is. However, after the first composite 161 is compressed by the first press rolls 401a and 401b and the second press rolls 402a and 402b in the third step 103 of FIG. 4, the pair of first and second mesh conveyor belts 171 is used. , 172, it becomes easy to manufacture the core material 13 having a small thickness while preventing an abnormality such as distortion from occurring in the shape of the assembly 160.

  Various changes can be made to the third step 103 in FIG. For example, one of the pair of first press rolls 401a and 401b and the pair of second press rolls 402A and 402b can be omitted. Further, a press roll can be further added to the third step 103.

The steps illustrated in FIGS. 3 and 4 include the step of sucking the water vapor jetted from the steam jetting unit 173 by the steam suction unit 174, but the present invention can also be carried out without sucking the steam. It is. For example, the steam suction unit 174 is not necessary when the sprayed steam easily passes through the web because the basis weight of the target web for steam injection is small or the traveling speed in the machine direction MD is low. Sometimes. Further, the thin compressed aggregate 20 manufactured by the method according to the present invention as illustrated by the steps of FIGS. 3 and 4 and the core member 13 including the compressed aggregate 20 are illustrated in FIG. In addition to the disposable diaper 1, it can be used as a thin compressed assembly or core material in disposable body fluid treatment products such as sanitary napkins and urine absorbing pads. Furthermore, in the present invention described with reference to the steps of FIGS . 3 and 4 in which the compressed aggregate 20 having a small thickness is continuously manufactured from the aggregate 160, the single aggregate 160 or the aggregate 160 is made of a breathable sheet. It can also be carried out on a single complex that is coated. In that case, instead of the pair of breathable supports made of the first and second mesh conveyor belts 171 and 172 that run in the machine direction MD, they move away from each other in the vertical direction TD without running in the machine direction MD. A single assembly 160 or a single composite is compressed by a pair of breathable supports that move in the manner described above, and water vapor is sprayed toward them, thereby producing a thin assembly 160 or a compressed assembly 20. can do.

(Examples 1-3)
In the first to third steps in FIG. 3, pulverized pulp is used as the hydrophilic fiber at a rate of 240 g / m ² , and the superabsorbent polymer particles include spherical particles and aggregates of spherical particles ( SA60S manufactured by Co., Ltd. was used at a rate of 240 g / m ² , and the first sheet web was formed of a core-sheath type composite fiber having a core of polypropylene, a sheath of polyethylene, a fineness of 2 dtex, and a fiber length of 51 mm. Using a through-air nonwoven fabric with a basis weight of 25 g / m ² , and using a tissue paper with a basis weight of 18 g / m ² as the second sheet web, the thickness is 0.18 mm and the cross direction with the machine direction The 1st composite web containing the aggregate | assembly of a water absorbing material whose dimension is 300 mm and 200 mm was obtained. The first composite web is advanced to the fourth step of FIG. 3 at a speed of 5 m / min, and a pair of flexibility adjusted to the gap shown in the following (1) to (3) in the horizontal running section of the fourth step. Led between mesh conveyor belts. For each mesh conveyor belt, a 30-mesh plain weave mesh belt formed of polyphenylene sulfide resin was used. On the first composite web, 0.7 MPa high-pressure steam was jetted from a nozzle in which nozzles having a diameter of 0.5 mm were arranged in a crossing direction at a pitch of 2 mm in the steam jetting unit to obtain a second composite web. The second composite web was naturally dried at room temperature and then cut to obtain core materials of Examples 1 to 3 in which a compressed water-absorbing material aggregate was sandwiched between a through-air nonwoven fabric and tissue paper. The obtained core material was evaluated after 24 hours or more had elapsed after production. The gaps of the mesh conveyor belt are as described in (1) to (3) below.

Mesh Conveyor Belt Gap (1) 1.6 mm: Example 1
(2) 1.2 mm: Example 2
(3) 0.8 mm: Example 3

(Comparative Examples 1-3)
In the process of FIG. 16 , a first composite web having the same composition and shape as the first composite used in Examples 1 to 3 was obtained, and the first composite web was 5 m / min at room temperature of 20 ° C. A second composite web was obtained by feeding between a pair of press rolls while traveling in the machine direction at a speed. Each press roll has a diameter of 300 mm, and the first composite web is compressed by adjusting the press pressure so that a linear pressure of 1.5 kN / cm acts on the width of the aggregate of water-absorbing materials. did. The gap between the pair of press rolls was set as follows (1) to (3). For each gap was evaluated that passed the second a core material obtained from the composite web 24 hours or more after production as a core material of Comparative Example 1-3.

Press roll gap (1) 0.6 mm: Comparative Example 1
(2) 0.5 mm: Comparative Example 2
(3) 0.35 mm: Comparative Example 3

In addition, in the core materials of Examples 1 to 3 and the core materials of Comparative Examples 1 to 3, the aggregate is obtained by using a through-air nonwoven fabric that can be easily peeled off from the aggregate of the water-absorbing material as the top sheet. When observing the surface, the effect of the peeling on the surface state of the aggregate could be made small enough to be ignored.

(Evaluation of core material)
About the core material of an Example and a comparative example, (1) Basis weight, (2) Thickness, (3) Thickness recovery rate after compression, (4) Absorption time, (5) Absorption time under load, (6 The surface smoothness, (7) ventilation resistance and (8) surface state were evaluated and observed according to the following procedures.

(1) Basis weight a. The core material was cut into 100 × 100 mm to determine the weight. A value obtained by subtracting the basis weight of the first sheet web and the second sheet web from the value 100 times the weight was defined as the basis weight (g / m ² ) of the aggregate of water-absorbing materials.
b. The measurement results are shown in Table 1.

(2) Thickness a. The core material was cut into 100 × 100 mm, and the thickness under a load of 3 gf / cm ² was measured with a dial gauge. A value obtained by subtracting the thicknesses of the first sheet web and the second sheet web from the thickness was defined as the thickness of the aggregate of the water-absorbing material.
b. The specific volume (cc / g) of the core material was calculated from the basis weight of (1) and the thickness of (2).
c. Table 1 shows the thickness and specific volume.

(3) Thickness recovery after compression a. For each of the core materials of the example and the comparative example, the ratio of the thickness measured in the above (2) and the gap d of the mesh conveyor belt was obtained as the thickness recovery rate r after compression, and the results are shown in Table 1. .
b. Since the core material of the example has a small thickness recovery rate r after compression, the core material has a required thickness even if the gap d of the mesh conveyor belt is not set small like the core material of the comparative example. I understood that.

(4) Absorption time a. After the first sheet web was peeled off from the aggregate of water-absorbing materials forming the core material, the core material was cut into 150 × 150 mm to obtain specimens.
b. The specimen was placed on a horizontal surface such that the second sheet web was the lower surface, and the tip of the autoburette was set at a position 20 mm from the upper surface in the center of the specimen.
c. Next, 10 cc of artificial urine was dropped from the tip of the autoburette at a rate of 120 cc / min.
d. The time from the start of dropping the artificial urine until the artificial urine was absorbed by the specimen until the upper surface of the specimen became white was measured, and the time was defined as the absorption time (seconds). A short absorption time means a high absorption rate.
e. The distance at which the artificial urine diffused in the machine direction and the crossing direction on the upper surface of the specimen was also measured.
f. The measurement results are shown in Table 1.
g. As artificial urine, the following was mixed or dissolved in 10 liters of ion-exchanged water.
200g of urea
Sodium chloride 80g
Magnesium sulfate 8g
Calcium chloride 3g
Blue No. 1 dye 1g
h. In Table 1, when the sample specimen of the example and the sample specimen of the comparative example have the same thickness, the sample specimen of the example tended to have a higher water absorption speed. Further, the specimens of the examples tended to increase the absorption rate even though the specimens were thinner than the specimens of the comparative examples.

(5) Weighted absorption time a. The same specimen as that used in the measurement of the absorption time in (4) was prepared as a specimen.
b. A 40 × 40 mm water-permeable nonwoven fabric piece (Benryse PS140 manufactured by Asahi Kasei Co., Ltd.) was placed in the center of the upper surface of the specimen.
c. The specimen and measuring tool were set as shown in FIG. 5 , and the tip of the autoburette was set at a position 20 mm above the upper surface of the specimen within the transparent cylinder shown in the figure.
d. 20 cc of artificial urine was dropped at a rate of 120 cc / min.
e. Subsequently, the inside of the cylinder was observed, and the time from the start of dropping the artificial urine to the time when the artificial urine was absorbed by the test piece was measured, and the time was defined as the absorption time under load (seconds). A short weighted absorption time means a fast weighted absorption rate.
f. The distance at which the artificial urine diffused in the machine direction and the crossing direction on the upper surface of the specimen was also measured.
g. The measurement results are shown in Table 1.

(6) Surface smoothness a. A core material obtained by cutting the core material into 100 × 100 mm and peeling the through-air nonwoven fabric used as the first sheet web in the core material manufacturing process from the aggregate of water-absorbing materials was used as a test specimen. The specimen is placed on a horizontal reference surface with the bottom surface of the core facing down, and the height from the reference surface to each part of the top surface of the specimen is measured to cope with undulations on the top surface. The height change was determined, and the quality of the surface smoothness of the aggregate of water-absorbing materials was judged based on the difference in the degree of the change.
b. High-precision shape measurement system (component equipment: high-precision stage, KS-1100) and high-speed / high-precision CCD laser displacement meter (component equipment: controller is LK-G3000V set, sensor head) Used LK-G30).
c. The stage conditions were set as follows.

Measurement range: 40000 μm × 40000 μm
Measurement pitch: 20 μm
Movement speed: 7500μm / sec

d. The conditions of the measurement head (LK-G3000) were set as follows.
Measurement mode: Measurement object Installation mode: Diffuse reflection Filter: Average 4 times Sampling cycle: 200 μs
e. The data obtained by the specimen a was processed using shape analysis software (KS-H1A). In the processed data, the Z coordinate was extracted by repeating one of the 16 positions for each of the X and Y coordinates, and transferred to Excel (Excel) of Microsoft's spreadsheet software. With this software, the X, Y, and Z coordinates were graphed as a contour graph. In addition, histogram processing of all Z-axis data was performed using the same software add-in function.
f. These measurements and treatments were performed on the core material of Example 3 and Comparative Example 3, and the results are shown in FIGS . 6 and 7 visualize the change in the undulations on the surface of the specimen, and the vertical axis Z indicates the height from the reference plane to the upper surface of the specimen. However, FIGS. 6 and 7 show the measurement points extracted by repeating one in 16 locations for each of the X and Y coordinates in order to avoid the fact that the graph becomes complicated and it becomes difficult to observe the change in undulation. Shows the result of extracting the Z coordinate value at each measurement point of 1280 μm and processing the value with Excel by extracting one measurement point from the four measurement points instead of all of the measurement points. ing. According to the data processing method employed in the present invention, when the measurement result is shown as a line graph, for example, the X coordinate is fixed and the Y coordinate is changed, and the change of the value of the Z coordinate corresponding to the Y coordinate is indicated. the line graph of it can be shown in different colors for each value of the fixed X-coordinate, in FIGS. 6 and 7 the line graph is shown in all black. FIG. 8 shows the height from the reference plane to the upper surface of the specimen on the horizontal axis for each specimen, and the detected frequency (unit: times) of the height on the vertical axis. The sample specimen of the example had a smaller change in undulation on the upper surface than the sample specimen of the comparative example, and the surface smoothness was good.

(7) Ventilation resistance a. The core material was cut into a circle having a diameter of 88 mm, and the first sheet web and the second sheet web were peeled from the aggregate of water-absorbing materials to obtain specimens.
b. Kato Tech Co., Ltd. breathability tester: KES-F8-APL is used, standard ventilation rate: set to 2 cm / s, the ventilation resistance value of the specimen is measured, and the resistance value is measured under dry conditions. did.
c. The specimen was allowed to absorb 20 cc of artificial urine and left for 1 minute, and the ventilation resistance value of the specimen was measured in the same manner as b, and the ventilation resistance value under wet conditions was measured.
d. Each of the airflow resistance values was divided by the basis weight of the specimen and compared as the airflow resistance index.
e. Table 2 shows the measurement results for the examples and comparative examples.

(8) Surface condition a. The core material was cut to 100 × 100 mm, and the first sheet web formed of the through-air nonwoven fabric was peeled from the aggregate of the water-absorbing material to obtain a test piece.
b. About the upper surface of the test piece from which the first sheet web was peeled, 50 × and 100 × photographs were taken using a real surface view VE-7800 manufactured by Keyence Corporation, and the surface state was observed with the photograph.
c. The specimens of Example 3 and Comparative Example 3 were observed. 9 and 10 are 50 and 100 times photographs of the core material of Example 3, and FIGS. 11 and 12 are 50 and 100 times photographs of the core material of Comparative Example 3, respectively.
d. According to these FIGS. 9-12 , in the core material of the comparative example 3, collapse of the shape of a superabsorbent polymer particle is recognized. That is, the particles are separated, and in the separated particles, there is evidence of collapse on the spherical surface. Further, the superabsorbent polymer particles and the pulp fibers are very close to each other, and the pulp fibers are also very close to each other. In the core material of Example 3, no collapse of the shape was observed in the superabsorbent polymer particles, there was a gap between the particles and the pulp fibers, and there was a gap between the pulp fibers.

FIG. 13 shows the relationship between the absorption time and the specific volume in Table 1. In the core material of the example having the same specific volume and the core material of the comparative example, a lot of gaps between the hydrophilic fibers 21 and a gap between the hydrophilic fibers 21 and the superabsorbent polymer particles 22 are formed. The core material 13 (see FIGS. 9 and 10 ) of the embodiment that tends to have a preferable tendency that the absorption speed becomes faster.

FIG. 14 is a diagram showing the relationship between the weighted absorption time and the specific volume in Table 1. As far as the core materials of the examples and comparative examples that are the objects of observation are concerned, the core material tends to shorten the absorption time under load as the specific volume increases, that is, the absorption rate under load tends to increase. It was. The tendency was almost the same in Examples and Comparative Examples.

FIG. 15 is a diagram showing the relationship between the ventilation resistance index and the specific volume in Table 2. When the specific volume was the same, the core material of the example and the core material of the comparative example had a tendency that the airflow resistance index of the core material of the example was lower than the airflow resistance index of the core material of the comparative example. This tendency was the same when the core material was in dry conditions and when it was in wet conditions. The core material of an Example with a low airflow resistance index means that the gas flow resistance inside the core material is small and the core material has good air permeability and liquid permeability.

13 Core material 21 Hydrophilic fiber 22 Superabsorbent polymer particle
23 Breathable sheet, breathable liquid-permeable sheet (top sheet)
24 Breathable sheet, Breathable liquid-permeable sheet (lower surface sheet)
160 aggregate
161 complex (first complex)
171 Breathable support (first mesh conveyor belt)
172 Breathable support (second mesh conveyor belt)
223 Breathable sheet, Breathable liquid-permeable sheet (first sheet web)
224 Breathable sheet, Breathable liquid-permeable sheet (second sheet web)
MD Machine direction TD Thickness direction

Claims (13)

An assembly of a water-absorbing material comprising hydrophilic fibers and highly water-absorbing polymer particles has a thickness direction, and the assembly is thinned in the thickness direction,
The assembly is used for disposable body fluid treatment products, and includes ground pulp as the hydrophilic fiber,
Sandwich the assembly with either a breathable sheet or a breathable liquid-permeable sheet to make a composite containing at least one of the breathable sheet and the breathable liquid-permeable sheet and the aggregate, The composite is interposed between a pair of flexible air permeable supports opposed to each other in the thickness direction of the assembly, and the pair of air permeable is compressed by the pair of air permeable supports. High-pressure steam having a temperature equal to or higher than the boiling point of water and having a vapor pressure of 0.1 to 2.0 MPa is applied to the composite through the first air-permeable support that is one of the supports , across the composite arranged at a pitch of 10 mm, by spraying in the thickness direction from a plurality nozzles having a diameter of 0.1 to 2 mm, the collector without collapse of the superabsorbent polymer particles Said method characterized by thinning the body.   The method according to claim 1, wherein the high-pressure steam is wet steam, saturated steam, or dry steam.   The method according to claim 1, wherein the high-pressure steam after being sprayed onto the complex and passed through the complex is sucked by an action of a vacuum pressure. The high-pressure steam is applied to the surface area of the composite facing the one of the pair of breathable supports while the pair of breathable supports travels in one direction at a speed of 5 to 500 m / min. the method according to any one of claims 1 to 3 injection in the range of ^{23kg / m 2 ~0.03kg / m 2} .   In the one direction, the pair of breathable supports is either a horizontal direction, a vertical direction or an inclined direction between the two directions with the composite interposed between the two supports. The method according to claim 4, further comprising a part traveling in the direction of.   The method according to any one of claims 1 to 5, wherein at least the first breathable support of the pair of breathable supports is a 10-75 mesh plain weave mesh belt using a polyolefin sulfide resin.   The method according to claim 1, wherein each of the pair of breathable supports is an endless belt.   The composite is mechanically compressed in the thickness direction to thin the composite beforehand, and then the high-pressure steam is injected onto the composite while compressing the composite with the pair of breathable supports. The method according to claim 1.   9. The method of claim 8, wherein the composite is pre-thinned by mechanically compressing the composite using at least a pair of press rolls.   The method according to claim 1, wherein the aggregate includes 98 to 10% by weight of the hydrophilic fibers and 2 to 90% by weight of the superabsorbent polymer particles.   The superabsorbent polymer particles are particles of any one of polyacrylic acid, polyacrylate, starch acrylonitrile graft copolymer, polyvinyl alcohol, polyvinyl ether, polyacrylamide, carboxymethylcellulose, and natural polysaccharides. 11. The method according to any one of 10.   The method according to any one of claims 1 to 11, wherein one of the air-permeable sheet and the air-permeable and liquid-permeable sheet is one of tissue paper and nonwoven fabric. An aggregate of water-absorbing materials, which is manufactured by the method according to any one of claims 1 to 12 and has a small thickness, and is used for a disposable body fluid treatment article .