JP4519095B2 - Absorbent articles - Google Patents

Description

  The present invention relates to absorbent articles such as disposable diapers, sanitary napkins, and incontinence pads.

  Absorbents for absorbent articles using continuous filament spread tows are known. For example, an absorber comprising a tow layer of crimpable acetate fibers and a pulverized pulp layer laminated on one side of this layer, in which both layers are integrated by pressing in the thickness direction of the absorber, is known. (See Patent Document 1). According to this absorber, the diffusibility of body fluid is improved. However, since acetate fibers have a lower water absorption capacity than pulp, a large amount of pulverized pulp must be used to increase the absorption capacity of the absorber. As a result, the absorber becomes thick, and the wearing feeling of the absorbent article is lowered.

  Also, it is known that the water-absorbing core is composed of an upper layer, a lower layer and an absorbent layer located between both layers, and a fiber layer made of acetate fiber tow is disposed on the spray layer of the superabsorbent polymer as the absorbent layer. (See Patent Document 2). A part of the superabsorbent polymer is bonded to the lower layer by an adhesive, and another part is housed in the fiber layer of the tow. In this water-absorbent core, although a part of the superabsorbent polymer is accommodated in the fiber layer of the tow, most of the superabsorbent polymer is bonded to the lower layer. That is, a fiber layer of tow and a spray layer of superabsorbent polymer exist separately. As a result, when the water absorbing core is deformed during wearing of the absorbent article due to the wearer's movement, the structure is easily broken.

  As an absorption layer having a continuous filament tow, one in which the tow extends in the thickness direction of the absorption layer is also known (see Patent Document 3). According to Patent Document 3, the excrement moves from the top to the bottom through the gap between the fibers of the tow and can be separated from the wearer's skin, so that it does not cause stuffiness or rash. Has been. In order for this absorption layer to have such a structure, the length of the tow needs to be long to some extent. Therefore, the absorption layer becomes thick.

  Apart from these technologies, the present applicants have previously proposed an absorbent article provided with an absorbent body including crimped fibers (see Patent Document 4). According to this absorbent article, twisting of the absorber is prevented, and the absorbability, wearing feeling, and fit are improved. Short fibers are generally used as the crimped fibers contained in the absorber.

JP-A-57-160457 Special table 2004-500165 gazette JP 2001-276125 A JP 2004-159786 A

  Therefore, the objective of this invention is providing the absorbent article which can eliminate the fault which the prior art mentioned above has.

  The present invention relates to an absorbent body in which an absorbent core comprising a long fiber web having hydrophilicity and crimps and a superabsorbent polymer embedded and supported in the web is coated with a sheet of fiber material. The above object is achieved by providing an absorbent article comprising:

  According to the present invention, it is possible to reduce the thickness and weight of the absorbent body of the absorbent article while maintaining the same absorption capacity as that of a conventional absorbent body. Moreover, even if a wearer performs intense operation | movement, the structure of an absorber is hard to be destroyed. In particular, when a superabsorbent polymer is contained in the absorbent body, the dropout is unlikely to occur.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The absorbent article of the present invention is mainly used for absorbing and holding excretory body fluids such as urine and menstrual blood. The absorbent article of the present invention includes, for example, disposable diapers, sanitary napkins, incontinence pads, etc., but is not limited thereto, and widely includes articles used for absorbing liquid discharged from the human body. .

  The absorbent article of the present invention typically includes a top sheet, a back sheet, and a liquid-retaining absorbent body disposed between both sheets. As the top sheet and the back sheet, materials usually used in the technical field can be used without particular limitation. For example, as the surface sheet, liquid permeable sheets such as various nonwoven fabrics and perforated films subjected to a hydrophilic treatment can be used. As the back sheet, a liquid-impermeable or water-repellent sheet such as a thermoplastic resin film or a laminate of the film and a nonwoven fabric can be used. The back sheet may have water vapor permeability. The absorbent article may further include various members according to specific uses of the absorbent article. Such members are known to those skilled in the art. For example, when applying an absorbent article to a disposable diaper or a sanitary napkin, a pair or two or more pairs of three-dimensional guards can be disposed on the left and right sides of the topsheet.

  FIG. 1 shows a schematic diagram of an embodiment of an absorbent body according to the present invention. The absorbent body 1 of the present embodiment is characterized by being thin and having a low basis weight while having a sufficient absorption capacity. The absorbent body 1 having such a feature includes a long fiber web (hereinafter referred to as a web) 2 containing a superabsorbent polymer 3 and a pulp pile or non-woven fabric (hereinafter collectively referred to as both pile layers). The absorbent core 5 provided with 4 is covered with a fiber material sheet (hereinafter also referred to as a fiber sheet) 6. In FIG. 1, the upper surface is a surface facing the wearer's skin, and the lower surface is a surface facing the back sheet.

  FIG. 2 schematically shows an exploded perspective view of the absorbent body 1 shown in FIG. FIG. 1 shows a state of a cross section at the center in the longitudinal direction in FIG. In FIG. 2, the fiber sheet 6 is omitted. As shown in FIG. 2, the long fiber web 2 has a vertically long rectangular shape extending in the longitudinal direction of the absorbent body 1. The pulp fiber layer 4 has a T-shape whose length matches the length of the web 2. The T-shaped pulp stacking layer 4 is incorporated into the absorbent article such that the horizontal portion 4a is located on the front side of the absorbent article (that is, the wearer's stomach side). The web 2 is arranged in a rectangular shape with the same width as the leg portion 4b on the upper side of the T-shaped leg portion 4b of the fiber stack layer 4 having a T shape.

  The long fibers constituting the web 2 have hydrophilicity. What is used in the present invention as a long fiber having hydrophilicity is a long fiber that is inherently hydrophilic, and inherently has no hydrophilicity, but is hydrophilic by being subjected to a hydrophilic treatment. Both of the long fibers to which is given are included. Preferred long fibers are inherently hydrophilic long fibers, and nylon, acrylic, acetate, and rayon long fibers are particularly preferable. In particular, acetate, which is a fiber having a moisture content of less than 10%, is particularly preferable because it retains its bulkiness even when wet. As the acetate, cellulose triacetate and cellulose diacetate are preferable. Here, the moisture content is a value measured in an environment of 25 ° C. and a relative humidity of 65%.

  In the present specification, the hydrophilic web refers to one having a Klem water absorption measured in the orientation direction of preferably 20 mm or more, more preferably 30 mm or more. The measurement of Klem water absorption is performed, for example, as follows. The superabsorbent polymer is removed from the portion of the absorber 1 containing the superabsorbent polymer, and the crimped rate of the long fiber in the absorber 1 is maintained, and the web of the long fiber is used to absorb the Krem. Measure the degree. For the measurement, ion-exchanged water colored with 0.3% red No. 2 (external addition) is used. The height from the water surface 30 seconds after the setting is taken as the Klem water absorption. The Klem water absorption is measured according to JISP8141 (1996) “Test method for water absorption by the Krem method of paper and paperboard”. As the measurement direction, only the longitudinal direction of the absorber 1 is measured. The test piece has a width of 15 mm. The average value of the measured values of the three test pieces is taken as the Krem water absorption. Depending on the test piece, the Klem water absorption varies in the width direction. In this case, a value obtained by substantially averaging (visually) the width direction is taken as the measurement value.

When the operation of removing the superabsorbent polymer from the absorbent body is performed, the web density ρ1 in the absorbent body may be different from the web density ρ2 after the superabsorbent polymer is removed. Therefore, before removing the superabsorbent polymer from the absorber, the density ρ1 of the web in the absorber is measured in advance, and the density ρ2 of the web after the superabsorbent polymer is removed is measured in advance. After adjusting the state of the web after the superabsorbent polymer is removed so as to be the same as the density ρ1, the water absorption of Klem is measured. In order to adjust the density ρ2 to the density ρ1, for example, the web after the superabsorbent polymer is removed may be compressed, and the Klem water absorption is measured in that state. The density ρ1 was, for example, 0.03 to 0.05 g / cm ³ .

The density ρ1 (g / cm ³ ) of the web in the absorber is calculated from the basis weight (g / cm ² ) of the web and the thickness (cm) of the web. The basis weight of the web is calculated from the weight (g) after removing the superabsorbent polymer from the absorbent body and the area (cm ² ). On the other hand, the thickness of the web is measured by the following method. A wrinkle is extended by applying a load of 24.5 kPa to the absorbent body taken out from the absorbent article in advance for 12 hours. Next, a weight is placed on an acrylic plate having a size of 5 cm × 5 cm on the absorber, and the thickness is measured under a state where a load of 0.245 kPa is applied. Specifically, a cross section of the absorber is cut out with a razor blade, the range of the absorber including the web is observed with a 10-fold stereo microscope, and the thickness of the web in the absorber is measured. The number of measurement points is 5, and the average value is the thickness. If the measured value fluctuates by 20% or more, delete the data and add another measured value.

As the long fiber, a crimped one is used. The long fiber has a crimp rate (JIS L0208) of preferably 10 to 90%, more preferably 10 to 60%, and still more preferably 10 to 50%. By forming a web from crimped long fibers, it becomes easy to stably embed and support a large amount of superabsorbent polymer in the web, even when a large amount of superabsorbent polymer is used. The extreme movement and dropout are less likely to occur. There is no particular limitation on the means for crimping the long fibers. Further, the crimp may be two-dimensional or three-dimensional. The crimp rate is defined as a percentage of the difference between the length A when the long fiber is stretched and the length B of the original long fiber with respect to the length A when stretched, and is calculated from the following equation: .
Crimp rate = ((A−B) / A) × 100 (%)

  The length of the original long fiber means a length in which both ends of the long fiber are connected with a straight line when the long fiber is in a natural state. The natural state means a state in which one end of the long fiber is fixed to a horizontal plate and hung downward by its own weight. The length when the long fiber is stretched refers to the length at the minimum load when the long fiber is stretched until there is no crimp.

  The crimp rate of the long fibers is as described above, and the number of crimps is preferably 2 to 25, particularly 4 to 20, especially 10 to 20 per cm.

  There is no restriction | limiting in particular in the fiber diameter of a long fiber. In general, satisfactory results are obtained by using long fibers of 1 to 10 dtex, in particular 1.7 to 7.8 dtex. In addition, when it is desired to give the absorbent body kinking resistance or cushioning properties, it is particularly preferable to use fibers of 2.1 to 7.2 dtex. In the present invention, the long fiber means a fiber having a fiber length of preferably 70 mm or more, more preferably 80 mm or more, and even more preferably 100 mm or more when the fiber length is measured by the average fiber length measurement method (Method C) of JIS L1015. Say. However, when the total length of the web to be measured is less than 100 mm, preferably 50% or more, more preferably 70% or more, more preferably 80% or more of the fibers in the web extend over the entire length of the web. In this case, it is assumed that the fibers of the web are long fibers. The long fibers used in the present invention are generally called continuous filaments. A bundle of continuous filaments oriented in one direction is generally called a tow. Therefore, the long fiber in the present invention is a concept including a continuous filament. The web in which the long fibers are oriented is a concept including a bundle of long fibers (so-called tow) as a raw material for forming the web and a tow layer of continuous filaments. In addition, fibers (cut fibers) in which part of the long fibers are cut and the fiber length is less than the above value may be mixed in the absorbent body.

  The superabsorbent polymer is embedded and supported in the web. The buried support refers to a state in which the superabsorbent polymer enters the space formed by the crimped long fibers, and the polymer is not easily moved or dropped even by vigorous movement of the wearer. . At this time, the long fibers are entangled or caught in the superabsorbent polymer, or the superabsorbent polymer is attached to the long fiber due to its own stickiness. The space formed by the long fiber is easily deformed even when stress is applied from the outside, and the entire long fiber can absorb the stress, thereby preventing the space from being destroyed. A part of the superabsorbent polymer is embedded and supported in the web 2. Depending on the manufacturing conditions of the absorbent body 1, almost all of the superabsorbent polymer may be uniformly embedded and supported in the web 2.

  The superabsorbent polymer 3 is generally in the form of particles, but may be fibrous. When a particulate superabsorbent polymer is used, if the shape is an irregular type, a block type, or a bowl type, it can be embedded and supported at a basis weight of the same amount to 10 times the web. it can. Further, in the case of a spherical particle aggregation type or a spherical type, it can be embedded and supported with a basis weight of the same amount or more and 5 times or less with respect to the web. For these particle shapes, it is desirable to select the former when it is particularly desired to achieve both high absorption and thinning, and the latter when importance is placed on the texture (reduction of the feeling of shaving of the superabsorbent polymer). The superabsorbent polymer 3 is embedded and supported in the web 2. FIG. 1 shows a state in which the superabsorbent polymer 3 is biased and exists in a portion extending from the center in the thickness direction to the lower portion of the web 2. In some cases, almost all of the polymer 3 is evenly embedded and supported in the web 2. “Uniform” means that when the superabsorbent polymer is completely uniformly arranged in the thickness direction or the width direction of the absorbent body 1 and when a part of the absorbent body 1 is taken out, This refers to the case where the variation in the abundance has a distribution within twice the basis weight. Such a variation is caused by rarely supplying a superabsorbent polymer excessively and producing a part with an extremely high spraying amount in manufacturing an absorbent article. In other words, the “uniform” includes cases where inevitably variations occur, and does not include cases where the superabsorbent polymer is distributed so as to intentionally vary.

  When the superabsorbent polymer 3 is present in a biased state as shown in FIG. 1, the diffusibility of the liquid is high and the liquid absorbability of the entire absorbent body is high. Is preferred. Contrary to FIG. 1, when the superabsorbent polymer 3 is biased and present in the region extending from the center in the thickness direction of the web 2 to the upper part, the liquid spot absorbability is high. It is suitable as an incontinence pad for use and an absorbent body of a sanitary napkin.

  Since the long fiber has crimps, the long fiber has a large number of spaces capable of holding particles. The superabsorbent polymer is retained in the space. As a result, even if a large amount of superabsorbent polymer is sprayed, the extreme movement or dropout is less likely to occur. Moreover, even if a wearer performs intense operation | movement, the structure of the absorber 1 becomes difficult to be destroyed. Depending on the superabsorbent polymer used, the crimp rate and the amount of long fibers used are adjusted as appropriate. Even in the conventional absorbent body, if the amount of the fiber material is increased, a large amount of the superabsorbent polymer can be retained, but in this case, the basis weight and thickness of the absorbent body are increased. On the other hand, in the present invention, it is easy to make the amount of the superabsorbent polymer relatively large with respect to the amount of the fiber material. Specifically, the basis weight of the superabsorbent polymer is preferably not less than the basis weight of the long fibers, more preferably not less than 2 times, more preferably not less than 3 times when viewed from the whole absorbent body. As a result, the absorber 1 is made thinner and has a lower basis weight. The upper limit value of the ratio of the basis weight of the superabsorbent polymer to the basis weight of the long fiber is determined from the viewpoint of extreme movement of the superabsorbent polymer and prevention of falling off. Although depending on the degree of crimp of the long fibers, if the upper limit is about 10 times, the superabsorbent polymer is unlikely to move or drop out even if the wearer performs a violent operation.

  The supportability of the superabsorbent polymer on the long fiber web is related to the network structure formed by the web and the physical properties of the superabsorbent polymer. From the viewpoint of the network structure, in the present invention, the steric regularity of the web, that is, the web is controlled by controlling the crimp rate, fineness, density, etc. of the web so that the supportability of the superabsorbent polymer is expressed. I have to. In the present invention, since the constituent fibers of the web are not bonded to each other, the size of the network formed on the web can be changed to such an extent that the superabsorbent polymer can be retained. Since the size of the mesh in the web can be changed, the supportability of the polymer becomes higher compared to the case where the superabsorbent polymer is supported on a fiber assembly having a bonding point such as a nonwoven fabric. The size of the mesh can be determined by, for example, (a) applying a superabsorbent polymer in a state where a fiber is tensioned and then releasing the tension, or (b) controlling the web tension in advance. It can be controlled by spraying a superabsorbent polymer under a state in which a shrinkage ratio is expressed, and further applying tension or pressure to the web.

  On the other hand, the physical properties of the superabsorbent polymer related to the supportability of the superabsorbent polymer include shape, particle size distribution, particle size, bulk density, surface properties, internal friction coefficient, fluidity, dispersibility, moisture content, charging Properties, adhesion, and cohesion. Among these, the particle size distribution and particle size of the superabsorbent polymer are closely related to the above-described web network structure. The carrying ability of the superabsorbent polymer is also affected by the number of collisions between the polymer and the long fibers inside the absorbent body when an external force or vibration is transmitted to the absorbent body due to the movement of the wearer. The higher the number of collisions, the higher the absorbency of the polymer, and the higher absorbability polymer screens according to the network formed by the long fibers, resulting in lower supportability. The number of collisions is affected by the fluidity of the polymer. The number of collisions increases as the fluidity of the superabsorbent polymer increases. In addition, the superabsorbent polymer which has high fluidity and has once escaped from the restraint of the web easily moves and becomes difficult to be supported on the web.

  Regarding the flowability of the superabsorbent polymer, comparing the bulk type superabsorbent polymer and the spherical aggregate type polymer, the spherical aggregate type superabsorbent polymer is more fluid than the bulk type superabsorbent polymer. High nature. As a result, the bulk type superabsorbent polymer has higher supportability than the spherical particle aggregate type superabsorbent polymer. In addition, since the superabsorbent polymer of the spherical particle agglomeration type has a smooth surface, the degree of friction with the fiber and catching on the fiber is lower than that of the bulky type superabsorbent polymer. Also from this viewpoint, the bulk type superabsorbent polymer has higher supportability than the spherical particle aggregate type superabsorbent polymer. As described above, the present invention has been devised in terms of the crimp rate of the long fibers, the shape of the superabsorbent polymer, the mixing ratio of the long fibers and the superabsorbent polymer, the method for supporting the superabsorbent polymer on the long fiber web, and the like. The absorber which is the effect of this can be made thin. In addition, the structure of the absorbent body is not easily destroyed by the wearer's action, and the superabsorbent polymer does not easily fall off.

  The following method can be used as an evaluation method to the extent that the superabsorbent polymer is buried and supported. The central part in the longitudinal direction of the web produced to 100 mm × 200 mm is cut to obtain a 100 mm × 100 mm test piece. This cut surface is directly below, and vibration is applied to the left and right 20 times at a speed of once / second with an amplitude of 5 cm. The weight of the polymer dropped from the cut surface is measured. When the weight of the dropped superabsorbent polymer is 25 wt% or less, particularly 20 wt% or less, especially 10 wt% or less, based on the total amount of the superabsorbent polymer present in the test piece, It can be said that this is a state in which the extreme movement and dropout of the functional polymer are difficult to occur.

As an evaluation of the extent to which the superabsorbent polymer is buried and supported, a mobility measured by the following method can be employed in addition to the above-described dropout evaluation test. First, an initial weight W0 of a 100 mm × 100 mm measurement sample used for the measurement of the drop-off evaluation test is measured in advance. The measurement sample after the measurement of the drop-off evaluation test is finished is cut in a direction perpendicular to the direction in which the long fibers extend, and is divided into two equal parts. The weight of each of the two halves divided into two is measured, and the weight of the halved fragment having the larger variation from 1/2 of the initial weight W0 of the measurement sample is adopted as the weight W1 for calculating the transfer rate. To do. For example, assuming that the weights of two fraction pieces are W1 ′ and W1 ″, if these W1 ′ and W1 ″ satisfy the following expression, W1 = W1 ′.
| W1'-W0 / 2 |> | W1 "-W0 / 2 |
Using the value of W1 determined in this way and the value of the initial weight W0 of the measurement sample, the movement rate is calculated from the following equation.
Movement rate (%) = {1-W1 / (W0 / 2)} × 100
When the value of the migration rate thus measured is 40% or less, particularly 30% or less, particularly 20% or less, it can be said that the migration of the superabsorbent polymer is difficult to occur.

  In a simple manner, the following evaluation method can be performed on the test piece subjected to the above-described drop-off evaluation test. 50 g of physiological saline (0.9 wt% NaCl) is evenly sprayed on the test piece subjected to the test for dropout evaluation, and the way of swelling of the test piece is visually observed. When the variation in the thickness of the test piece is within 2 times, it can be said that it is difficult for the superabsorbent polymer to move or drop off.

  In each of the evaluation methods described above, when the web is viewed in the horizontal direction, the test piece is sampled from a region where the superabsorbent polymer is dispersed with the same basis weight.

  In the absorbent body 1 according to the present embodiment, the long fibers constituting the web 2 are oriented in one direction in the plane direction of the absorbent body 1. When the liquid is absorbed by the absorbent body 1 due to the orientation of the long fibers in one direction, the liquid diffuses preferentially in the orientation direction of the long fibers. That is, it diffuses preferentially in the planar direction of the absorber. Conversely, diffusion in the direction perpendicular to the orientation direction of the long fibers is suppressed. When long fibers are oriented in the longitudinal direction of the absorbent article, liquid leakage (lateral leakage) from the side of the absorbent article is effectively prevented.

  The orientation of the long fiber may be as long as the vector connecting the start point and end point of the long fiber is oriented in the plane direction. Including the ones that face (direction). More specifically, the degree of orientation of the long fibers is preferably 1.2 or more, particularly 1.4 or more in terms of the degree of orientation. In this embodiment, the degree of orientation is measured using a Microwave molecular orientation analyzer MOA-2001A manufactured by KANZAKI. The sample size is 100 mm in the longitudinal direction and 50 mm in width, and the average value of three points is the degree of orientation. When the sample size is less than this size, measurement is performed by arranging a plurality of samples so as not to overlap each other.

  When the long fibers are oriented in the longitudinal direction of the absorbent article, it is preferable that the absorbent body does not have a linear bond line that crosses the orientation direction of the long fibers. When such an adhesive line exists, smooth diffusion of the liquid in the orientation direction of the long fibers is interrupted, which may cause side leakage.

  When long fibers are oriented in the width direction of the absorbent article, diffusion in the longitudinal direction of the absorbent article is suppressed, and spot absorptivity is obtained. In this case, in order to prevent liquid leakage (lateral leakage) from the side, the absorbent body preferably has a linear bonding line that crosses the orientation direction of the long fibers. “Linear” means a continuous line that suppresses permeation of liquid, and it is not necessary that individual seal lines and the like are continuous without interruption. For example, if the liquid movement can be prevented by arranging the intermittent seal lines in layers, it is linear. In addition to the linear shape, the linear shape may be a curved shape or a broken line shape. The width of the line is preferably about 0.2 to 15 mm.

  The bonding line may be formed only in the web 2. Alternatively, an adhesive line may be formed over the entire thickness direction of the absorbent body 1 including the fiber sheet 6. Furthermore, you may form including a surface sheet. In any case, it is preferable that an adhesive line is formed at least in the longitudinal center of the absorbent article. Moreover, the adhesion line may be formed outward from both side edges in the width direction of the absorbent body. By providing an adhesive line in this way, even if the liquid moves in the web due to capillary action, it will not contact the adhesive line and prevent further movement, so liquid leakage from the side is unlikely to occur. Become.

  In the absorbent body 1 according to this embodiment, a fiber stack layer 4 of pulp is laminated on the lower side of the web 2. The pulp fiber layer 4 may or may not contain a superabsorbent polymer. The pulp accumulation layer 4 is obtained by depositing pulp fibers, or is made of a nonwoven fabric using pulp fibers as a raw material. When the pulp stacking layer 4 is obtained by depositing pulp fibers, the stacking layer should be the same as that used as an absorbent in a conventional absorbent article. Can do. In the case where the pulp stacking layer 4 is made of a nonwoven fabric made from pulp fibers, for example, an airlaid nonwoven fabric can be used as the nonwoven fabric. By arranging the fiber pile layer 4 on the lower side of the web 2, the fiber pile layer 4 acts as a primary stock layer of the excreted liquid, so that the liquid excretion rate is high (for example, urine is excreted). Even if it is), liquid leakage can be effectively prevented. From the viewpoint of making this effect even more remarkable, the superabsorbent polymer embedded and supported in the web 2 is biased and embedded on the back sheet facing surface side of the web 2 as shown in FIG. It is preferable. Further, in addition to containing the superabsorbent polymer in the web 2, the liquid leakage effect becomes more remarkable by containing the superabsorbent polymer in the fiber stack layer 4 of the pulp. In addition, since the superabsorbent polymer contained in the web 2 acts as a hygroscopic agent, an increase in humidity in the wearing is suppressed during wearing of the absorbent article, and the effect of making it difficult to be steamed is also exhibited.

  As the pulp contained in the fiber stack layer 4, natural pulp such as wood pulp or synthetic pulp made of synthetic resin such as polyethylene can be used. Either natural pulp or synthetic pulp may be used, or both may be used. Since natural pulp is generally a material having high liquid absorbency, the liquid absorption capacity of the absorbent body 1 can be increased by using natural pulp. On the other hand, since synthetic pulp has a property of melting when heated to a predetermined temperature, the synthetic fiber is melted by heating the laminated fiber layer 4 or the absorbent core 5 containing the synthetic pulp or the entire absorbent body 1, thereby absorbing the absorbent body. The strength as a whole can be increased. When natural pulp is used as the pulp, the pulp accumulation layer 4 is mainly made by depositing pulp fibers. On the other hand, when synthetic pulp is used as the pulp, the fiber pile layer 4 is mainly made of a nonwoven fabric such as an airlaid nonwoven fabric.

Since the absorption state of the present invention is thin, the superabsorbent polymer is blended in the absorber at high density. For this reason, it is effective to use the following superabsorbent polymers used in the above-described embodiments in order to maintain and improve the absorption performance. First, the amount of physiological saline absorbed by centrifugal dehydration is 30 g / g or more, particularly 30 to 50 g / g, which prevents the amount of polymer used and the gel feeling after liquid absorption from being lowered. This is preferable. The amount of absorption of the superabsorbent polymer by centrifugal dehydration is measured as follows. That is, 1 g of superabsorbent polymer was swollen with 150 ml of physiological saline for 30 minutes, then placed in a 250 mesh nylon mesh bag, dehydrated with a centrifuge at 143 G (800 rpm) for 10 minutes, and the total weight after dehydration was determined. taking measurement. Next, the amount of water absorption (g / g) by centrifugal dehydration is calculated according to the following formula.
Water absorption by centrifugal dehydration method = (total weight after dehydration−weight of nylon mesh bag−weight of highly absorbent polymer when dried−weight of nylon mesh bag liquid remaining) / weight of highly absorbent polymer when dried

Furthermore, the superabsorbent polymer used in each of the above-described embodiments has a gel passage occurrence that the liquid passage time measured by the following method is 20 seconds or less, particularly 2 to 15 seconds, especially 4 to 10 seconds. In addition, it is preferable from the viewpoint of preventing the deterioration of the absorption performance due to it and preventing the leakage due to the lack of liquid due to the lack of absorption. The measurement of the liquid transit time is as follows. That is, 0.5 g of the superabsorbent polymer was placed in a cylindrical tube having a cross-sectional area of 4.91 cm ² (inner diameter: 25 mmφ) and an openable / closable cock (inner diameter: 4 mmφ). Fill with water and swell the superabsorbent polymer with the saline until it reaches saturation. After the swollen superabsorbent polymer settles, the cock is opened and 50 ml of physiological saline is allowed to pass through. The time required for 50 ml of the physiological saline to pass through is measured, and this time is taken as the liquid passage time. The liquid transit time is one of the indices that reflect the gel strength of the superabsorbent polymer. The shorter the liquid passage time, the stronger the gel strength.

  Further, it is more preferable to use a superabsorbent polymer having a high liquid passing rate under a load. As the superabsorbent polymer, a polymer having a flow rate of 30 to 300 ml / min, preferably 32 to 200 ml / min, more preferably 35 to 100 ml / min is used. When the value of the liquid flow rate is less than 30 ml / min, the superabsorbent polymers saturated and swollen by the liquid absorption adhere to each other under load, and the passage of the liquid is hindered, so that gel blocking easily occurs. The larger the value of the flow rate, the better from the viewpoint of preventing the occurrence of gel blocking. When the liquid flow rate exceeds 300 ml / min, the fluidity of the liquid in the absorber is too high, especially when a large amount of excreta is excreted at one time, or in older infants or adults. When the excretion rate is high as described above, the liquid may not be sufficiently fixed and leakage may occur when the absorber is further thinned. In general, increasing the liquid flow rate increases the degree of crosslinking of the superabsorbent polymer, lowering the absorption capacity per unit weight of the superabsorbent polymer, and a large amount of superabsorbent polymer must be used. I must. From these viewpoints, the upper limit value of the flow rate is determined.

  The measurement of the flow rate of the superabsorbent polymer 21 is performed under a 2.0 kPa load. This load substantially corresponds to the body pressure applied to the absorbent body while wearing the absorbent article. A specific method for measuring the flow rate is described in paragraph 0005 of Japanese Patent Laid-Open No. 2003-235889, for example. In the present invention, measurement is performed by changing 0.200 g, which is the weight of the sample used in the measurement method described in this publication, to 0.32 g. Specifically, the flow rate is measured by the following procedure.

[Measurement method of flow rate]
A filtration cylindrical tube provided with a wire mesh (aperture 150 μm) and a thin tube (inner diameter 4 mm, length 8 cm) with a cock (inner diameter 2 mm) at the lower end of a vertically standing cylinder (inner diameter 25.4 mm). prepare. With the cock closed, 0.32 g of a measurement sample adjusted to a particle size of 850 to 150 μm is put into the cylindrical tube. Next, 50 ml of 0.9% by weight physiological saline is poured into the cylindrical tube. After standing for 30 minutes from the start of pouring physiological saline, a cylindrical rod (21.2 g) having a mesh opening of 150 μm and a diameter of 25 mm and having a wire mesh at the tip is inserted into the filtration cylindrical tube. Make the measurement sample touch. After 1 minute, a 77.0 g weight is attached to the cylindrical rod and a load is applied to the measurement sample. After another 1 minute, open the cock. The time (T1) (second) until the liquid level of the physiological saline solution reaches the 20 ml scale line from the 40 ml scale line is measured. Using the measured time T1 (seconds), the liquid passing time is calculated from the following equation. In the formula, T0 is a time measured without putting a measurement sample in the filtering cylindrical tube.
Flow rate (ml / min) = 20 × 60 / (T1-T0)

  A more detailed method for measuring the flow rate is described in paragraphs 0008 and 0009 of JP-A-2003-235889. The measuring device is described in FIGS. 1 and 2 of the publication.

  The superabsorbent polymer that can be used in each of the above-described embodiments is not particularly limited as long as it satisfies the above-mentioned characteristics. Specifically, for example, sodium polyacrylate and (acrylic acid-vinyl alcohol) Examples thereof include a polymer, a crosslinked polyacrylic acid soda, a (starch-acrylic acid) graft polymer, a (isobutylene-maleic anhydride) copolymer and a saponified product thereof, potassium polyacrylate, and cesium polyacrylate. In order to satisfy the above-described characteristics, for example, the crosslink density inside and on the surface of the superabsorbent polymer may be adjusted, or a crosslink density gradient may be provided on the particle surface. Alternatively, the superabsorbent polymer particles may be non-spherical amorphous particles. In particular, by adopting a reverse phase suspension polymerization method using an anionic surfactant described in Japanese Patent No. 2721658 relating to the earlier application of the present applicant as a dispersant, it has a desired liquid flow rate. A superabsorbent polymer 21 is obtained. Alternatively, the method described in JP-A-7-18495, column 7 line 28 to column 9 line 6 can be used.

  The absorbent body of the present invention having a long fiber web has a sparse structure with large gaps between fibers compared to a conventional absorbent body mainly composed of flap pulp, so that the absorbent body is permeable to liquid. It is also a good thing. Therefore, when the absorption rate of the superabsorbent polymer is slow, the liquid may pass through the absorber before being absorbed by the superabsorbent polymer, and may not be sufficiently absorbed by the absorber. From this viewpoint, it is preferable that the superabsorbent polymer contained in the web has a sufficiently high absorption rate. Thereby, the liquid can be reliably held in the absorber. The absorption rate of a superabsorbent polymer is generally expressed in the art by the measured value of the DW method. The absorption rate (ml / (0.3 g · 30 sec)) by the DW method is measured using an apparatus (Demand Wettability Tester) generally known as an apparatus for performing the DW method. Specifically, the superabsorbent polymer to be measured is placed on a polymer spray table (70 mmφ, No. 2 filter paper placed on the glass filter No. 1) with the saline level set at an equal water level. Spray 0.3g. The amount of water absorption at the time of spraying the superabsorbent polymer is set to 0, and the amount of water absorption after 30 seconds (this absorption amount is measured by a burette scale indicating the amount of decrease in the physiological saline water level) is measured. The value of the obtained absorption amount is taken as the water absorption rate. The absorption rate can be designed by the shape, particle size, bulk density, degree of crosslinking, etc. of the superabsorbent polymer.

  In an embodiment in which the absorber does not contain pulp or the content in the absorber is 30% by weight or less, the absorption rate measured according to the DW method is 2 to 10 ml / (0.3 g · 30 sec), especially 4 A superabsorbent polymer of ˜8 ml / (0.3 g · 30 sec) is preferably used. In addition, the superabsorbent polymer having such an absorption rate has been avoided in the conventional absorbent body mainly composed of fluff pulp because it causes gel blocking and consequently liquid leakage. is there. On the other hand, in the present embodiment, the web has a sparse structure, so the liquid is taken into the web and the speed of the taken-in liquid is high, so it has a high absorption speed. Even if a superabsorbent polymer is used, gel blocking hardly occurs, and conversely, liquid leakage is effectively prevented. Here, the weight of the absorbent body includes the weight of the covering sheet that wraps the absorbent body.

  In addition to the above-described pulp fibers, the pulp accumulation layer 4 includes short fibers of natural or (semi) synthetic hydrophilic fibers such as rayon, cotton, lyocell, tencel, acetate, polyvinyl alcohol fiber, and acrylic. It may be.

  As shown in FIG. 1, the absorbent core 5 including the web 2 and the pulp fiber layer 4 is entirely covered with a fiber sheet 6. In the present embodiment, one fiber sheet 6 is used. The fiber sheet 6 covers the upper surface and both left and right side surfaces of the absorbent core 5. Furthermore, the left and right side portions of the fiber sheet 6 are wound around the lower surface side of the absorbent core 5 and overlap at the center portion in the width direction on the lower surface of the core 5. Thus, the lower surface of the absorbent core 5 is also covered with the fiber sheet 6.

  By covering the absorbent core 5 with the fiber sheet 6, it is possible to effectively prevent extreme movement and dropping of the superabsorbent polymer 3 contained in the core 5. Furthermore, since the handling property as the whole absorber 1 becomes favorable, it can be easily conveyed by itself. Moreover, since it can be easily cut or cut into a desired shape, an absorbent body corresponding to the shape of the absorbent article can be easily produced.

  In particular, by joining the absorbent core 5 and the fiber sheet 6 by a predetermined means, the absorbent body 1 has high rigidity due to the joint between the absorbent core 5 and the fiber sheet 6 and the rigidity of the fiber sheet 6 itself. Thereby, the handling property is further improved. Examples of means for joining the absorbent core 5 and the fiber sheet 6 include adhesion by an adhesive and heat fusion.

  As the fiber sheet 6, a material having a strength sufficient to prevent the superabsorbent polymer from dropping off and a material that does not hinder the permeation of excreted liquid is appropriately used. For example, tissue paper or a non-woven fabric having liquid permeability can be used. The nonwoven fabric may be subjected to a hydrophilic treatment or a hole opening treatment as necessary. Further, a slit may be formed. Alternatively, the fiber sheet 6 may be embossed and the sheet 6 may be softened. When using a non-woven fabric as the fiber sheet 6, the non-woven fabric is, for example, a fiber using a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate alone, or a composite fiber using a plurality of these resins as a raw material. Can be used. Examples thereof include a thermal bond nonwoven fabric, a spunbond nonwoven fabric, a spunbond-meltblown-spunbond nonwoven fabric, a spunbond-meltblown-meltblown-spunbond nonwoven fabric, a needle punched nonwoven fabric, a spunlace nonwoven fabric, and an airlaid nonwoven fabric. In these non-woven fabrics, hydrophilic fibers such as rayon, cotton, lyocell, tencel, acetate, and natural pulp can be coexisted.

  Next, the preferable manufacturing method of the absorber 1 which concerns on this embodiment is as follows. First, a long fiber tow having the crimp rate described above is prepared. The web is obtained by opening the tow with a predetermined means while being conveyed in a state of being stretched in the longitudinal direction by applying tension. For the opening, for example, an air opening device using compressed air can be used. Since the long fibers have crimps, when the tension is applied, the long fibers are easily stretched in the longitudinal direction. A superabsorbent polymer is spread on the opened web. At the time of spreading, the web is transferred onto a vacuum conveyor while the transport speed of the opened web is reduced. The web is untensioned on the vacuum conveyor. Thereby, the stretched state of the web is released, and the long fibers return to the crimped state. Moreover, the thickness of the web becomes larger than that in the stretched state, and the embedded supportability of the superabsorbent polymer is improved. Under this condition, the superabsorbent polymer is sprayed. The long fibers in the crimped state have voids that can accommodate the superabsorbent polymer between the fibers. The superabsorbent polymer is buried and supported in the voids. Thereby, the superabsorbent polymer having a desired basis weight can be buried and supported. In contrast, when the web is stretched under tension, there is not enough space between the fibers to accommodate the superabsorbent polymer, making it easy to successfully embed and support the superabsorbent polymer. Not. At the same time as the dispersion of the superabsorbent polymer, it is effective to promote suction of the polymer by carrying out suction from the surface of the web opposite to the surface where the polymer is dispersed. By appropriately adjusting the degree of suction, the polymer distribution in the thickness direction of the web can be changed.

  In addition to the air opening device or instead of the air opening device, a tow is passed between a roll in which a large number of disks are incorporated at predetermined intervals around the axis and a smooth receiving roll. The tow can be opened. By doing so, the density and density of the long fibers are generated in the web, and an uneven structure can be obtained. By dispersing the superabsorbent polymer on the web having such a concavo-convex structure, a part of the superabsorbent polymer falls into the concave portion, and then the width of the web is narrowed to increase the height between the adjacent convex portions. The absorbent polymer is sandwiched and further buried in the web.

Prior to the application of the superabsorbent polymer to the web, various adhesives such as a hot melt adhesive are applied to the web by a contact method such as a roll coater method or a screen printing method, or a non-contact method such as a spray method. For the coating, spray-type coating that allows easy switching of each pattern and adjustment of the amount of the adhesive in a non-contact manner is preferable, and spray coating that can successfully perform dotted adhesion is preferably used. Examples of the spray method include a slot spray method, a curtain spray method, a melt blown method, and a spiral spray method. The adhesive is preferably applied in such a low amount that it does not impede the permeation of the liquid. From this viewpoint, the coating amount of the adhesive is preferably ³ to 30 g / m ² , particularly 5 to 15 g / m ² .

  After the application of the adhesive is completed, the superabsorbent polymer is spread on the web. As a result, the superabsorbent polymer is retained in the space formed by the crimped long fibers. After the superabsorbent polymer is sprayed, the web is compressed with a roll, a belt, or the like, so that the superabsorbent polymer is embedded in the web. In this way, the superabsorbent polymer is buried and supported in the web.

  An absorbent core is obtained by laminating the web obtained in this manner and a pile fiber layer separately produced using a fiber pile device. Separately from this operation, each adhesive such as a hot melt adhesive is applied discontinuously on one surface of the fiber sheet. And an absorption core is mounted in a coating surface, and this core is coat | covered with a fiber sheet. In this way, the absorbent body 1 is obtained.

  The form of the covering of the absorbent core 5 by the fiber sheet 6 is not limited to that shown in FIG. 1, and for example, the form shown in FIGS. In the absorbent body 1 shown in FIG. 3A, the upper surface of the absorbent core 5 is covered with the first fiber sheet 6a, and the lower surface and the left and right side surfaces of the core 5 are covered with the second fiber sheet 6b. The left and right side portions of the second fiber sheet 6b are wound up on the upper surface side of the absorbent core 5, and overlap the left and right side portions of the first fiber sheet 6a. The absorbent core 1 shown in FIG. 3B has the absorbent core 5 covered with a single fiber sheet 6 in the same manner as the absorbent body shown in FIG. However, in the absorbent body shown in FIG. 1, the left and right sides of the fiber sheet 6 overlap on the lower surface of the absorbent core 5, whereas in the absorbent body 1 shown in FIG. The portion only covers the left and right side portions on the lower surface of the absorbent core 5, and the center portion in the width direction on the lower surface is not covered with the fiber sheet 6.

  When the absorbent body 1 is used in a disposable diaper for infants, the thickness is preferably 1 to 4 mm, more preferably 1.5 to 3 mm, regardless of the form of the absorbent body 1. belongs to. When used for a sanitary napkin, the thickness is preferably 0.5 to 3 mm, more preferably 1 to 2 mm. When used as an incontinence pad, it is preferably 0.5 to 4 mm, more preferably 1 to 3 mm.

From the viewpoint of easily realizing the thickness, the basis weight of the web 2 in the absorbent body 1 according to the present embodiment is 120 to 400 g / m ² when the absorbent body 1 is used for a disposable diaper for infants, for example. In particular, 150 to 300 g / m ² is preferable. When used for a sanitary napkin, it is preferably 35 to 200 g / m ² , particularly 50 to 150 g / m ² . When used for an incontinence pad, it is preferably 35 to 500 g / m ² , particularly 50 to 400 g / m ² .

From the same viewpoint, the basis weight of the piled fiber layer 4 of the pulp in the absorbent body 1 according to the present embodiment is the same as that of the absorbent body 1 regardless of whether or not the laminated fiber layer 4 includes a superabsorbent polymer. When used for a disposable diaper for infants, it is preferably ²⁰ to 300 g / m ² , particularly 50 to 200 g / m ² . When used for a sanitary napkin, it is preferably ²⁰ to 500 g / m ² , particularly 50 to 300 g / m ² . When used for an incontinence pad, it is preferably ²⁰ to 500 g / m ² , particularly 50 to 300 g / m ² .

The basis weight of the fiber sheet 6 is not critical in the present invention as compared to the basis weight of the web 2 and the basis weight of the pulp stacking layer 4. The basis weight of the fiber sheet 6 is about 5 to 80 g / m ² , particularly about 10 to 50 g / m ² suffices.

  Next, another embodiment of the present invention will be described. Regarding the points that are not particularly described with respect to the other embodiments, the description of the above-described embodiments is appropriately applied. 4 to 9, the same members as those in FIGS. 1 to 3 are denoted by the same reference numerals.

  The absorber 1 shown in FIG. 4 includes an upper layer absorber 1a and a lower layer absorber 1b. The upper absorbent body 1a is formed by coating an absorbent core made of a hydrophilic long fiber web 2 with a single first fiber sheet 6a. The web 2 contains a superabsorbent polymer 3. The lower layer absorbent body 1b is formed by covering an absorbent core composed of a pulp pile layer 4 with a single second fiber sheet 6b. The fiber stack layer 4 may or may not contain a superabsorbent polymer.

  The first and second fiber sheets 6a and 6b may be of the same type or different types. Their basis weights may be the same or different.

  According to the absorbent body 1 of this embodiment, the upper layer absorbent body 1a including the long fiber web 2 and the lower layer absorbent body 1b including the pulp stacking fiber layer 4 are separately manufactured to manufacture absorbent articles. Since it is only necessary to laminate both absorbers sometimes, there is an advantage that the manufacturing process is not complicated.

  The absorbent body 1 shown in FIG. 5 is similar to the absorbent body shown in FIG. 4 in that it includes an upper layer absorbent body 1a and a lower layer absorbent body 1b. The difference between the two is that, in the absorbent body shown in FIG. 4, each absorbent body 1a, 1b is covered with one fiber sheet, whereas in the absorbent body 1 shown in FIG. The points 1a and 1b are covered with two fiber sheets.

  In each absorber 1a, 1b, the absorption core is covered with two fiber sheets from the upper and lower surfaces, and the fiber sheets extending from the left and right edges of the absorption core are joined to each other. Also in this embodiment, the same effect as the embodiment shown in FIG. 4 is produced.

  In the present embodiment, the two first fiber sheets 6a, 6a constituting the upper absorbent layer 1a may be the same type or different types. Their basis weights may be the same or different. The same applies to the two second fiber sheets 6b, 6b constituting the lower layer absorbent body 1b.

  The absorbent body 1 shown in FIG. 6 includes a first absorbent body 1c in which an absorbent core made of a hydrophilic long fiber web 2 is covered with a single first fiber sheet 6a. The web 2 contains a superabsorbent polymer. A pulp accumulation layer 4 is laminated below the first absorbent body 1c. The fiber stack layer 4 may or may not contain a superabsorbent polymer. And the whole laminated body of the 1st absorber 1c and the fiber pile layer 4 of a pulp is coat | covered with the 1st 2nd fiber sheet 6b. According to this embodiment, since the web 2 containing the superabsorbent polymer 3 is doubly covered with the first fiber sheet 6a and the second fiber sheet 6b, the superabsorbent polymer is more effectively dropped off. Is prevented.

  In an absorbent body 1 shown in FIG. 7, an absorbent core 5 includes a long fiber web 2 and a pulp stacking layer 4. The superficial absorbent polymer 3 may or may not be contained in the pulp stacking fiber layer 4. Similarly, the superabsorbent polymer 3 may or may not be contained in the web 2.

  The pulp accumulation layer 4 is covered with the web 2. The web 2 is covered with the fiber sheet 6. According to the absorber 1 of this embodiment, the compression recovery property of an absorber becomes favorable. Moreover, the absorption speed of the excreted liquid increases and the shape retention of the absorbent body 1 also increases. In particular, when an air laid nonwoven fabric is used as the fiber stack layer 4 of pulp, these effects become remarkable. The air-laid nonwoven fabric generally tends to have a hard texture due to its production method. However, the hardness of the air-laid nonwoven fabric can be reduced by coating the air-laid nonwoven fabric with a web 2 of long fibers.

  When an airlaid nonwoven fabric is used as the pulp stacking fiber layer 4, the nonwoven fabric may be subjected to a hole opening treatment as necessary. Further, a slit may be formed. Alternatively, the nonwoven fabric may be embossed and the nonwoven fabric may be softened.

  As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to the said embodiment. For example, in the absorbent body 1 of the embodiment shown in FIGS. 4 and 5, the absorbent bodies 1d to 1f shown in FIGS. 8 (a) to 8 (c) are used as the upper-layer absorbent body instead of the upper-layer absorbent body 1a. May be. The same applies to the first absorbent body 1c in the absorbent body 1 of the embodiment shown in FIG.

  In the absorbent 1d shown in FIG. 8A, a long fiber web 2 is folded in three along the longitudinal direction in an inwardly folded state, and the superabsorbent polymer 3 is placed inside the trifolded web 2. Is retained. These are entirely covered with the fiber sheet 6. In the absorbent body 1e shown in FIG. 8B, the long-fiber web 2 and the fiber sheet 6 are folded in three along the longitudinal direction thereof along the longitudinal direction thereof. In which the superabsorbent polymer 3 is held. The absorbent body 1f shown in FIG. 8 (c) has a long fiber web 2 folded in a meandering manner along the longitudinal direction thereof, and a superabsorbent polymer at a portion near the upper surface of the tri-folded web 2. 3 is buried and carried. These are entirely covered with two fiber sheets 6a and 6b. The two fiber sheets 6a and 6b may be the same type or different types. Their basis weights may be the same or different.

  Further, the shapes of the long fiber web 2 and the pulp accumulation layer 4 are not limited to those shown in FIG. 2, and may be, for example, the shapes shown in FIGS. 9A to 9E.

  Further, in the embodiment shown in FIG. 1, the width of the web 2 containing the superabsorbent polymer 3 and the pulp stacking layer 4 is the same, but they may be different from each other. For example, as shown to Fig.10 (a), the web 2 containing the superabsorbent polymer 3 may protrude so that it may extend from the width direction both ends of the fiber pile layer 4 of a pulp. Conversely, as shown in FIG. 10 (b), the pulp accumulation layer 4 may extend so as to extend from both side edges in the width direction of the web 2 containing the superabsorbent polymer 3. The absorbent body of the embodiment shown in FIG. 10A is preferably applied to a disposable diaper for infants in particular. Since the web 2 containing the superabsorbent polymer 3 is flexible, even if the width of the web 2 is widened, there is little discomfort in the crotch region. Therefore, it is possible to achieve both improved absorption performance and comfortable fit and fit to the body. The absorbent body according to the embodiment shown in FIG. 10A is desirably used in a region such as an abdomen or a buttock where the area is desired to be widened to secure the absorption amount. In particular, when the absorbent body is applied to a target tape corresponding area of a spreadable diaper having a fastening tape, and the area is widened in the area, the thickness and rigidity of the target tape corresponding area are made uniform over almost the entire area. be able to. This is important in the sense of improving the operability during fastening.

  Further, in the embodiment shown in FIG. 1, the width of the fiber sheet 6 is the same as the width of the absorbent core 5, but instead, the fiber sheet 6 is slack as shown in FIG. So as to extend in the width direction from both side edges of the absorbent core 5. In this embodiment, the slack part 6a which consists of the fiber sheet 6 which does not contain the adhesive agent in the outer side of the both-sides edge of the absorption core 5 is formed. By allowing the fiber sheet 6 to protrude from both side edges of the absorbent core 5 so as to have the slack portion 6a, the fiber sheet 6 can be provided with a space for the absorbent core 5 to expand due to liquid absorption. This has the effect of preventing the absorption core 5 from causing swelling inhibition when a large amount of urine is absorbed.

  The effect similar to the effect which the absorber of embodiment shown to Fig.11 (a) show | plays is also show | played by the absorber shown to FIG.11 (b) and (c). In each of the absorbent bodies shown in FIGS. 11B and 11C, the fiber sheet 6 has pleats. In the absorbent body shown in FIG. 11 (b), pleats P folded into the interior of the absorbent core 5 are formed between the web 2 and the fiber stack layer 4. In the absorbent body shown in FIG. 11 (b), pleats P projecting laterally from both side edges of the absorbent core 5 are formed.

  In the embodiment shown in FIG. 11 (a) to FIG. 11 (c), the number and size (amplitude) of the sagging portions 6a and the pleats P are not limited, the amount of superabsorbent polymer, the amount of web and fibers, It can be appropriately increased or decreased according to the elongation of the fiber sheet 6.

  Each of the manufacturing methods for obtaining the absorbent body according to the embodiment shown in FIGS. 11B and 11C includes a step of folding the fiber sheet 6 into a Z shape. That is, in manufacturing the absorbent body according to the embodiment shown in FIG. 11B, first, the web 2 is laminated on the fiber sheet 6, and the superabsorbent polymer is sprayed on the web 2. Next, a part of the side edge of the web 2 is wrapped with the fiber sheet 6, and the sheet 6 is folded back outward and folded into a Z shape. Subsequently, after the laminated fiber layer 4 is laminated on the web 2, the whole is wrapped with the fiber sheet 6.

  In the manufacture of the absorbent body according to the embodiment shown in FIG. 11C, first, the web 2 is laminated on the fiber sheet 6, and the superabsorbent polymer is sprayed on the web 2. Next, the fiber stack layer 4 is laminated on the web 2 on which the superabsorbent polymer is dispersed. Subsequently, the fiber sheet 6 is folded in a Z shape in the vicinity of the side edge of the laminate of the web 2 and the stacked fiber layer 4. And the side edge of this laminated body is wrapped, and also the whole laminated body is further wrapped with the fiber sheet 6.

  As another modified example of the present invention, the laminated relationship between the long fiber web 2 and the pulp stacking layer 4 is opposite to the embodiment described so far, and the pulp stacking layer 4 is placed on the long fiber web 2. May be arranged. Further, a plurality of laminates of the long fiber web 2 and the pulp pile layer 4 may be laminated. Moreover, the shape of the laminated fiber layer 4 of a pulp can be made into various shapes, for example, in the absorber shown in FIGS. 1-6, a part of the laminated fiber layer 4 is isolate | separated, or a laminated fiber layer 4 may have a notch (dart).

[Example 1]
First, a crimped acetate long fiber tow was prepared. The fiber diameter of this long fiber was 2.1 dtex, and the total fiber amount of tow was 25,000 dtex. The tow was opened using an air opening device under elongation to obtain a spread web. Further, the web was wound by passing a spread web between a roll in which a large number of disks were incorporated around the axis at predetermined intervals and a smooth receiving roll. Thereafter, the web was adjusted to a width of 100 mm, transferred to a vacuum conveyor in a state where the conveyance speed was reduced, and the web tension on the vacuum conveyor was relaxed to develop crimps. At this time, the web was 26 g / m ² , the crimp rate of long fibers in the web was 30%, and the number of crimps per 1 cm was 15. As a result, the space between the long fibers was widened to facilitate the entry of the superabsorbent polymer, and the web was thickened to improve the embedding supportability of the superabsorbent polymer. A superabsorbent polymer (260 g / m ²⁾ was sprayed on the web to obtain a web in which the polymer particles were embedded and supported in the spread web.

Next, an air-through nonwoven fabric having a basis weight of 25 g / m ² was used as the surface sheet. The air-through nonwoven fabric was composed of a core-sheath type composite fiber (thickness: 2.1 dtex, surface treatment with a surfactant and liquid permeability) having a core made of polypropylene and a sheath made of linear low density polyethylene. A porous film having a basis weight of 20 g / m ² as a backsheet, used was composite by bonding a polypropylene spunbond nonwoven fabric having a basis weight of 20 g / m ² hot melt 1.5 g / m ^2. The porous film is obtained by uniformly forming 100 parts by weight of a linear low density polyethylene resin having a density of 0.925 g / cm ³ , 150 parts by weight of calcium carbonate, and 4 parts by weight of an ester compound as a third component. The film was uniaxially stretched twice in the longitudinal direction. Other than that, according to the manufacturing method of a normal disposable diaper, the disposable diaper of the structure shown in FIG.1 and FIG.2 was obtained. The absorber was arranged so that the orientation direction of the web coincided with the longitudinal direction of the diaper.

[Example 2]
In Example 1, the amount of the superabsorbent polymer sprayed was 110 g / m ² to obtain a web in which the polymer particles were embedded and supported in the spread web. Next, 100 parts by weight of the opened fluff pulp and 100 parts by weight of the superabsorbent polymer are uniformly mixed in an air stream and stacked on a T-shaped mold, and the total basis weight is 300 g / m ² . Got the body. The T-shaped mold had a leg width of 100 mm, a length of 100 mm, a horizontal frame width of 125 mm, and a length of 100 mm. The basis weights of the fluff pulp and the superabsorbent polymer in the piled body were 150 g / m ² , respectively. The web was stacked on the piled fiber, and the whole was wrapped with a tissue paper having a basis weight of 16 g / m ² and spray-coated with a hot melt adhesive to obtain an absorbent. Thereafter, a disposable diaper was obtained in the same manner as in Example 1.

[Examples 3 to 5]
In Example 2, the fiber diameter of the long fibers is 6.7 dtex, the total fiber amount of the tow is 17,000 dtex, the crimp rate of the long fibers in the web is 24%, the number of crimps per cm is 10, and the web A laminate was obtained in the same manner as in Example 2 except that the average basis weight was 30 g / m ² . Furthermore, the tissue paper coating method on the laminate was changed to FIGS. 3 (a), 4 and 11 (a). Except these, it carried out similarly to Example 2, and obtained the disposable diaper.

[Comparative Example 1]
100 parts by weight of the opened fluff pulp and 100 parts by weight of the superabsorbent polymer were uniformly mixed in an air stream to obtain a mixture having a total basis weight of 520 g / m ² . The basis weights of the fluff pulp and the superabsorbent polymer were 260 g / m ² , respectively. The obtained mixture was wrapped with a tissue paper having a basis weight of 16 g / m ² to obtain an absorbent. Between the mixture and tissue paper, 5 g / m ² of hot melt pressure-sensitive adhesive was spray-coated and adhered. The basis weight of the entire absorbent body was 562 g / m ² and the thickness was 4.3 mm. Except these, it carried out similarly to Example 1, and obtained the disposable diaper.

[Comparative Example 2]
As in Comparative Example 1, 100 parts by weight of the opened fluff pulp and 100 parts by weight of the superabsorbent polymer were uniformly mixed in an air stream to obtain a mixture having a total basis weight of 300 g / m ² . The basis weights of the fluff pulp and the superabsorbent polymer were 150 g / m ² , respectively. Other than that was carried out similarly to the comparative example 1, and obtained the absorber. The basis weight of the entire absorbent body was 342 g / m ² and the thickness was 2.6 mm. A disposable diaper was obtained in the same manner as in Comparative Example 1 except that this absorber was used.

    [Evaluation]

[Performance evaluation]
The absorption capacity of the absorbers obtained in Examples and Comparative Examples was measured by the following methods, and the structural stability and flexibility were evaluated. The results are shown in Table 1 below.

[Absorption capacity]
The obtained absorbent body is fixed to a 45 ° inclined plate, and a certain amount of physiological saline is repeatedly injected into the position 200 mm from the upper end of the absorbent body at regular intervals, and the lower end of the absorbent body The amount of injection until leakage from the part was compared. The relative value when the absorption capacity of Comparative Example 1 was 1.0 was calculated using the following formula.
Absorption capacity (relative value) = (absorption capacity of sample) / (absorption capacity of comparative example 1)

[Structural stability]
(1) At the time of drying The center part of the absorber produced to 100x200 mm was cut | disconnected, and the absorber of 100x100 mm was obtained. The amount of polymer dropped from the cut surface was measured when the vibration was applied 20 times at an amplitude of 5 cm and a speed of 1 sec / sec with the cut surface directly below. The embedding supportability of the superabsorbent polymer was evaluated according to the following criteria.
Of the mixed superabsorbent polymers,
○: The ratio of the superabsorbent polymer that has dropped off is 10% or less.
(Triangle | delta): The quantity of the superabsorbent polymer which dropped out exceeds 10% and is 25% or less.
X: The amount of the superabsorbent polymer dropped off exceeds 25%.
(2) When wet The surface of the absorber cut to 100 × 200 mm was almost uniformly absorbed with 200 g of physiological saline, and then it was visually determined whether or not the absorber was destroyed when the absorber was gently lifted.
○: The ratio of the superabsorbent polymer dropped off is 10% or less, and the absorber is not destroyed.
(Triangle | delta): The ratio of the superabsorbent polymer which dropped out exceeds 10% and is 25% or less, and there is no destruction of an absorber.
X: The ratio of the superabsorbent polymer dropped off exceeds 25%, or the absorber is destroyed.

[Flexibility]
The flexibility of the absorber was evaluated using a handleometer. The measured value of the handleometer indicates that the smaller the value, the better the ease of wearing and the better the fit. The measurement method using the handle-o-meter is as follows. Measurement is performed according to JIS L1096 (flexibility measurement method). An absorbent body cut by 150 mm in the longitudinal direction and 50 mm in the width direction is arranged in a direction perpendicular to the groove on a support base in which a groove having a width of 60 mm is carved. The force required when the center of the absorber is pushed by a blade having a thickness of 2 mm is measured. The apparatus used in the present invention is a texture testing machine (handle-of-meter method), HOM-3 type, manufactured by Daiei Scientific Instruments. The average value of the three points is taken as the measured value. Based on the measured values obtained, the flexibility was evaluated according to the following criteria.
○: The measured value of the handle-o-meter is 2N or less.
(Triangle | delta): The measured value of a handle ohm meter exceeds 2N and is 4N or less.
X: The measured value of the handle o meter exceeds 4N.

Example 6
In this example, the relationship between the crimp rate of the long fiber web and the loading rate of the superabsorbent polymer was examined. The fiber diameter of this long fiber was 2.1 dtex. This long fiber tow was conveyed under elongation and opened using an air opening device to obtain a spread web. Next, the web was wound through a spread web between a roll in which a large number of disks were incorporated around the axis at predetermined intervals and a smooth receiving roll. Thereafter, the web was adjusted to a width of 100 mm, transferred to a vacuum conveyor in a state where the conveyance speed was reduced, and the web tension on the vacuum conveyor was relaxed to develop crimps. The tension of the web was controlled to prepare a web of acetate long fibers having various crimp rates. As a result, the space between the long fibers was widened to facilitate the entry of the superabsorbent polymer, and the web was thickened to improve the embedding supportability of the superabsorbent polymer. A superabsorbent polymer was sprayed on the web, and the superabsorbent polymer was buried and supported in the spread web. The basis weight of the web was 26 g / m ² . The spreading basis weight of the polymer was 260 g / m ² . As the polymer, a bulk type having an average particle size of 330 μm was used. The above-described structural stability (when dry) test was performed on the absorbent body thus obtained. The weight of the superabsorbent polymer supported on the web after the test is divided by the weight of the superabsorbent polymer blended in the web before the test and multiplied by 100, and the obtained value is multiplied by the superabsorbent polymer. The loading ratio (%). The results are shown in Table 2.

Drawing 1 is a mimetic diagram showing the cross section of one embodiment of the absorber concerning the absorptive article of the present invention. FIG. 2 is an exploded perspective view of the absorbent body shown in FIG. FIG. 3A and FIG. 3B are schematic views (corresponding to FIG. 1) showing another embodiment of the absorbent body shown in FIG. FIG. 4 is a schematic view (corresponding to FIG. 1) showing a cross section of another embodiment of an absorbent body according to the absorbent article of the present invention. FIG. 5 is a schematic view (corresponding to FIG. 1) showing a cross section of another embodiment of an absorbent body according to the absorbent article of the present invention. FIG. 6 is a schematic view (corresponding to FIG. 1) showing a cross section of another embodiment of an absorbent body according to the absorbent article of the present invention. FIG. 7 is a schematic view (corresponding to FIG. 1) showing a cross section of another embodiment of an absorbent body according to the absorbent article of the present invention. FIG. 8A to FIG. 8C are schematic diagrams showing other forms of the upper absorbent layer in the absorbent body shown in FIGS. 4 and 5 and the first absorbent body in the absorbent body shown in FIG. . Fig.9 (a) thru | or FIG.9 (e) are the exploded perspective views of other embodiment of the absorber which concerns on the absorbent article of this invention. 10 (a) and 10 (b) are schematic views (corresponding to FIG. 1) showing a cross section of another embodiment of the absorbent body according to the absorbent article of the present invention. Fig.11 (a) thru | or (c) are the schematic diagrams (FIG. 1 equivalent view) which shows the cross section of other embodiment of the absorber which concerns on the absorbent article of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Absorbent body 2 Hydrophilic long fiber web 3 Superabsorbent polymer 4 Pulp fiber layer 5 Absorbent core 6 Fiber material sheet

Claims (4)

In an absorbent article comprising a topsheet, a backsheet, and a liquid-retaining absorbent disposed between both sheets,
The absorbent body has a hydrophilic and crimped long fiber web, a pulp pile or non-woven fabric laminated on the lower side of the web, and a superabsorbent embedded in the web. absorbent core comprising a polymer, Ri Na is covered with a sheet of fibrous material,
The sheet is folded between the web and the stacked fiber layer, and a pleat is formed on the sheet,
The absorber absorbent article that has been placed so that the product繊層or the nonwoven fabric facing the backsheet.   The absorbent article according to claim 1, wherein the long fibers are oriented in a planar direction of the absorbent body. The absorptive article according to claim 1 or 2 in which said pile layer or said nonwoven fabric does not contain a superabsorbent polymer. It is a manufacturing method of the absorptive article according to claim 1,
Laminating a web made of long fibers having hydrophilicity and crimps on a sheet of fiber material in a rectangular shape;
A superabsorbent polymer is spread on the web,
Wrapping part of the both side edges of the web with the sheet and folding the sheet back to the outside and folding it into a Z shape,
Laminating a laminated fiber layer or a nonwoven fabric on the web,
The manufacturing method of the absorbent article which wraps this laminated fiber layer or this nonwoven fabric with this folded sheet | seat .

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