JP3980043B2 - 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 separated in the thickness direction.

  Further, the superabsorbent polymer bonded to the lower layer may inhibit the liquid absorption due to the influence of the adhesive. Accordingly, since the absorption efficiency per unit weight of the superabsorbent polymer is lowered, the addition amount of the superabsorbent polymer must be increased more than necessary to increase the absorption capacity. That is, in order to efficiently use the superabsorbent polymer, it is necessary to develop a loose fixing method.

  Moreover, in the said patent document 2, the pressure applied to the inside of an absorber becomes very high by slight absorption and swelling of a superabsorbent polymer, and a superabsorbent polymer becomes impossible to swell any more. As a result, the absorber that can sufficiently contribute to absorption is only the central portion of the absorber, and high absorption performance cannot be maintained.

  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, since 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, 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.

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

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

The present invention is an absorbent article comprising an absorbent body comprising a hydrophilic long fiber web and a superabsorbent polymer embedded and supported in the web,
The superabsorbent polymer has different particle sizes on the top sheet side and the back sheet side of the web ,
The superabsorbent polymer achieves the above object by providing an absorbent article in which the particle size on the back sheet side of the web is larger than the particle size on the top sheet side .

  According to the present invention, since the particle size of the superabsorbent polymer is different between the top sheet side and the back sheet side of the absorber, the liquid absorption rate can be increased. In addition, it is possible to reduce the thickness and basis weight while maintaining the same absorption capacity as that of the conventional absorber. Moreover, even if a wearer performs intense operation | movement, the structure of an absorber is hard to be destroyed.

  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 schematically shows the structure of an absorbent body according to an embodiment of the absorbent article of the present invention. Note that this embodiment is intended only to help understanding of the present invention and is outside the scope of the present invention. The absorber 1 of the present embodiment is characterized by a high liquid absorption rate. It is also characterized by being thin and having a low basis weight while having sufficient absorption capacity. The absorbent body 1 having such characteristics includes a long fiber web (hereinafter referred to as a web) 2 and particles of a superabsorbent polymer 3 embedded and supported in the web 2. In FIG. 1, the upper surface is a surface facing the top sheet, and the lower surface is a surface facing the back sheet.

  Here, the surface sheet side means a range from the surface of the web 2 facing the surface sheet to a half thickness. The particle size on the surface sheet side means the particle size when the average particle size of the superabsorbent polymer is obtained by observing the cross section of the absorber within the range of 10 times with a stereoscopic microscope. As a place for measuring the cross section, the absorber is cut into two parts in the width direction so as to be divided into three equal parts in the longitudinal direction, and one of the same cut parts is selected, and a total of two cross sections are measured. And In each cross section, when the superabsorbent polymer is not perfectly spherical, the average value of the minor axis and the major axis is defined as the particle diameter of the superabsorbent polymer. The back sheet side means a range from the surface of the web 2 facing the back sheet to a half thickness. The particle size on the back sheet side means the particle size obtained by the same method as the particle size measurement method on the top sheet side.

  When measuring only the size relationship of the particle size of the superabsorbent polymer, in place of the measurement method described above, 5% copper sulfate aqueous solution is absorbed to improve the visibility of the superabsorbent polymer in the web 2. Sprinkle over the whole body, leave it for 10 minutes, wipe off excess moisture with a paper towel, and then measure by visually observing only the surface of the absorbent body facing the top sheet.

  When viewed in the thickness direction of the web 2, the superabsorbent polymer embedded and supported in the web 2 has a distribution in its particle size. As shown in FIG. 1, the superabsorbent polymer 3 has different particle sizes on the top sheet side and the back sheet side of the web 2. Specifically, the superabsorbent polymer 3 includes a relatively large particle size polymer (hereinafter referred to as a large diameter polymer) 3a and a relatively small particle size polymer (hereinafter referred to as a small diameter polymer) 3b, The large-diameter polymer 3a is biased toward the top sheet side of the web 2, and the small-diameter polymer 3b is biased toward the back sheet side of the web 2.

  The distribution of the particle size of the superabsorbent polymer 3 in the thickness direction of the web 2 may be changed stepwise or continuously. When the particle size changes in a stepped manner, the polymers present on the surface sheet side need not all have the same particle size. The same applies to the polymer present on the back sheet side. In short, it is only necessary that the average particle size of the polymer existing on the top sheet side is larger than the average particle size of the polymer existing on the back sheet side.

  When the large-diameter polymer 3a is biased toward the top sheet side and the small-diameter polymer 3b is biased toward the back sheet side, the absorbent 1 has an increased liquid absorption rate. The reason is as follows. In general, the larger the particle size of the superabsorbent polymer, the smaller the surface area per unit weight and the slower the liquid absorption rate. In addition, since a superabsorbent polymer having a large particle size is difficult to close-pack, a large number of large spaces are formed between the superabsorbent polymer particles. Therefore, the liquid that has permeated the top sheet and reached the absorber 1 flows down toward the bottom of the absorber 1 without being immediately absorbed by the large-diameter polymer 3a that is biased toward the top sheet. Moreover, the long fiber web 2 has a sparse structure with large gaps between the fibers compared to the fluff pulp piles that have been widely used in conventional absorbents, and allows the liquid to permeate quickly. Have Accordingly, the liquid quickly reaches the back sheet side where the small diameter polymer 3b is biased. Since the small diameter polymer 3b has a high surface area and a high liquid absorption rate, the liquid is quickly absorbed by the small diameter polymer 3b. Moreover, since the small diameter polymer 3b is easy to close-pack, a large number of fine voids are formed between the superabsorbent polymer particles, thereby improving the space holding force. Excess liquid that has not been absorbed by the small-diameter polymer 3b is absorbed by the large-diameter polymer 3a that is biased toward the topsheet. In the present embodiment, the absorption rate is increased by such a liquid absorption mechanism. In addition, the liquid quickly penetrates the absorbent body 1 in the thickness direction, and the liquid trying to return to the surface sheet side is absorbed by the large-diameter polymer 3a, and moreover, there is little liquid remaining between the large-diameter polymers 3a. The liquid residue on the surface sheet side of the body 1 and liquid return from the absorbent body are reduced, and the absorbent body 1 exhibits a dry feeling. Furthermore, since the large-diameter polymer 3a has a larger space between the particles than the small-diameter polymer 3b, even if the large-diameter polymer 3a absorbs and swells and increases its volume, Since the increase in volume can be absorbed in the space, gel blocking is less likely to occur.

  In addition, even in the case of adjusting the particle size distribution of the superabsorbent polymer as described above in a large amount of fluff pulp piles widely used in conventional absorbent bodies, the liquid passage speed of fluff pulp is long fiber web. Compared to the above, it is extremely slow, and the pulp sags when wet, so an improvement in absorption rate cannot be expected.

  From the above viewpoint, the large-diameter polymer 3a that is biased toward the topsheet side preferably has an average particle size of 300 to 700 μm, particularly 350 to 500 μm. On the other hand, the small-diameter polymer 3b biased toward the back sheet side preferably has an average particle size of 50 to 300 μm, particularly 100 to 250 μm. The method for measuring the particle size of the superabsorbent polymer is as described above. Further, the difference in the particle size of the superabsorbent polymer between the top sheet side and the back sheet side of the web 2 can be confirmed, for example, by observing the cross section of the web 2 with a microscope. Alternatively, it can be confirmed by injecting water or physiological saline into the web 2 to swell the superabsorbent polymer and observing the size of the superabsorbent polymer after swelling with the naked eye. This is because the size of the superabsorbent polymer after swelling is proportional to the size before swelling.

  From the viewpoint of more effectively preventing the gel blocking described above, the superabsorbent polymer 3 preferably has a high gel strength. One of the indexes representing the strength of the gel strength of the superabsorbent polymer is the liquid passage speed under 0.6 kPa pressure. When the superabsorbent polymer 3 having a liquid passage speed of 150 to 1500 g / min, particularly 300 to 750 g / min is used, the occurrence of gel blocking and a decrease in the absorption performance due to the occurrence of gel blocking are prevented. This is preferable in that prevention of leakage due to lack of liquid due to not being in time is prevented.

The liquid passage speed under the pressure is measured by the following method. First, 0.5 g of the superabsorbent polymer is put into 100 g of physiological saline, and the superabsorbent polymer is swollen until it reaches a saturated state. Next, the swollen superabsorbent polymer is 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). After filling with water and settling of the superabsorbent polymer, put a glass filter (made by Shibata Kagaku, inner diameter 23 mm, pore size 160-250 μm) on the superabsorbent polymer, and absorb a lot of glass beads with a diameter of 1 mm. The cock is opened with a pressure of 0.6 kPa applied to the functional polymer, 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 speed. The liquid passing speed is one of the indexes reflecting the gel strength of the superabsorbent polymer. The shorter the liquid passage speed, the stronger the gel strength.

  The superabsorbent polymer 3 is uniformly embedded and supported in the web 2 over the entire area in the thickness direction of the web 2. The buried support means that the superabsorbent polymer enters the space formed by the long fibers, particularly the space formed by the crimped long fibers, and the polymer moves or falls off even when the wearer moves violently. The state where it is difficult to occur. 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 fibers is easily deformed even when stress is applied from the outside, and the entire long fibers can absorb the stress, thereby preventing the space from being destroyed. The term “uniform” means that the superabsorbent polymer is completely uniform in the thickness direction or width direction of the absorbent body 1 and when a part of the absorbent body 1 is taken out. The case where the variation in the abundance of 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 above “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 long fiber which comprises the web 2 has a crimp, this long fiber has many space which can hold | maintain particle | grains. 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 this embodiment, 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 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. Measure the weight of polymer dropped from the cut surface. When the weight of the dropped superabsorbent polymer is 25% by weight or less, particularly 20% by weight or less, especially 10% by weight or less based on the total amount of the superabsorbent polymer originally present in the test piece ( In other words, the weight of the superabsorbent polymer held in the test piece is 75% by weight or more, particularly 80% by weight or more, based on the total amount of superabsorbent polymer originally present in the test piece, In particular, when the content is 90% by weight or more (this value is referred to as a supporting rate), it can be said that the superabsorbent polymer is hardly moved or dropped off.

  The following evaluation method can also be performed on the test piece subjected to the drop evaluation test. 50 g of physiological saline (0.9 wt% saline) is evenly sprayed on the test piece subjected to the test for dropout evaluation, and the way the test piece swells 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.

As the superabsorbent polymer 3, the same polymer that has been used for conventional absorbent articles can be used without particular limitation. Specifically, for example, polyacrylic acid soda, (acrylic acid-vinyl alcohol) copolymer, crosslinked polyacrylic acid soda, (starch-acrylic acid) graft polymer, (isobutylene-maleic anhydride) copolymer, and Examples thereof include saponified products, potassium polyacrylate, and cesium polyacrylate. In order to satisfy the liquid passing speed under pressure, for example, a crosslinking density gradient may be provided on the surface of the superabsorbent polymer particles. Alternatively, the superabsorbent polymer particles may be non-spherical amorphous particles. Specifically, the method described in JP-A-7-18495, column 7 line 28 to column 9 line 6 can be used. The basis weight of the superabsorbent polymer 3 in the web 2 is preferably 50 to 1000 g / m ² , particularly preferably 100 to 500 g / m ² .

  In addition to the superabsorbent polymer 3, other particles such as activated carbon, silica, alumina, titanium oxide, various viscosity minerals (zeolite, sepiolite, bentonite, cancrinite, etc.), etc. are contained in the web 2. Deodorant and antibacterial agent) can coexist. As the inorganic particles, those partially substituted with metal sites can be used. Alternatively, various organic and inorganic buffering agents, that is, acetic acid, phosphoric acid, citric acid, succinic acid, adipic acid, malic acid, lactic acid, or salts thereof may be used alone or in combination, or various amino acids may be used. The function of these components is to suppress the smell of excreta absorbed by the absorber and the smell derived from the material. In addition, various organic and inorganic buffering agents have the effect of neutralizing excrement, for example ammonia generated by decomposition of urine, to keep the diaper neutral to weakly acidic, thereby allowing excretion from the diaper to the skin. Even if there is a liquid return of an object, the influence on the skin can be reduced. Further, since various organic and inorganic buffer agents have a function of neutralizing alkali such as ammonia, when a fiber having an ester bond in a molecular structure such as an acetate fiber is used as a long fiber constituting the web 2. Can also be expected to prevent the fiber from being damaged due to the decomposition of the ester bond by alkali.

  In addition, hydrophilic fine powder or short fibers can coexist in the web for the purpose of improving liquid retention and absorption rate, and improving dryness. Examples of hydrophilic fine powders or short fibers include fibrillated or non-fibrillated cellulose powder, carboxymethyl cellulose and its metal salt, carboxyethyl cellulose and its metal salt, hydroxyethyl cellulose and its derivatives, silk powder, nylon powder, Examples include short fibers such as rayon, cotton, and wool. Among these, it is preferable to use cellulose powder because the above effects can be improved to the maximum. The hydrophilic fine powder or short fiber may be sprayed on the web before spraying the superabsorbent polymer, or may be mixed with the superabsorbent polymer and sprayed on the web at the same time.

  The web 2 in which absorption is buried and supported by the superabsorbent polymer 3 is composed of long fibers having 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%.

As the long fiber, it is preferable to use a crimped one. 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. For example, the relationship between the crimp rate of the long fibers in the web and the loading rate of the superabsorbent polymer described above is as shown in Table 1 below, and the crimp rate of the long fibers is within a specific range. It can be seen that the loading of the superabsorbent polymer is very high. The fiber diameter of the long fiber used at this time 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 thus obtained absorber was subjected to a structural stability (when dry) test described later. 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 values in Table 1 vary depending on the fiber diameter and fiber amount of the long fibers used and the mixing ratio of the superabsorbent polymer, the shape of the superabsorbent polymer, the hygroscopicity, and the like.

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 fibers are stretched and the length B of the original long fibers 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 1.0 to 7.8 dtex, in particular 1.7 to 5.6 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.

  In the absorbent body 1, 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, and a part of the long fiber is in the vertical direction (twist or entanglement between the start point and end point) (the thickness of the absorber) 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 the present embodiment, the degree of orientation is measured using Microwave molecular orientation analyzer MOA-2001A manufactured by KANAKA. 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. Or 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.

  The preferable manufacturing method of the absorber 1 is as follows. First, the long fiber tow 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. When the long fibers have crimps, the long fibers are easily stretched in the longitudinal direction by applying a tension. 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. When the long fiber is crimped, it returns 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. Simultaneously with the dispersion of the superabsorbent polymer, suction is carried out from the surface of the web opposite to the surface where the polymer is dispersed, thereby promoting the buried support of the polymer. It is important to supply the superabsorbent polymer to the web in a state where the tension of the opened web is relaxed.

The average interfiber distance of the fibers constituting the web is preferably within plus or minus σ, more preferably within 0.5σ of the average particle diameter of the superabsorbent polymer. σ represents the standard deviation of the average particle diameter. The average interfiber distance of the web is calculated by the following formula.

  In the calculation of the average interfiber distance, the constituent fibers of the web are regarded as circular regardless of the cross-sectional shape. In the case of an irregular cross-sectional shape, the average value of the long axis and the short axis is taken as the fiber diameter. In the case of Y-shape or C-shape, the circumscribed circle is the fiber diameter.

  When spraying the superabsorbent polymer, a spraying device having a hood on the vacuum conveyor can be used in combination. Air is sucked into the hood by the action of a vacuum conveyor. The superabsorbent polymer supplied from the superabsorbent polymer feeder is conveyed to the air stream and the particles are sized. This is because particles having a large particle size are transported farther under the force of air in the airflow. The sized superabsorbent polymer is embedded and supported in the web in order from the smallest particle size by suction of a vacuum conveyor.

  In general, the superabsorbent polymer 3 is not an aggregate of particles having the same particle diameter but an aggregate of particles having various particle diameters, and has a particle size distribution taking a distribution form such as a normal distribution. Therefore, when the superabsorbent polymer 3 is spread on the spread web, the spread web functions like a sieve, and the superabsorbent polymer 3 having a large particle size is captured in the vicinity of the web spraying surface. The smaller the diameter of the superabsorbent polymer 3, the lower the web. As described above, since suction is performed from the surface opposite to the dispersion surface of the polymer 3 on the web, the particles are further sized in the airflow when the superabsorbent polymer 3 is supplied. Therefore, the superabsorbent polymer 3 having a smaller particle size is more likely to enter the lower part of the web. In this way, the superabsorbent polymer 3 is buried and supported from the spraying surface of the polymer 3 on the web to the opposite surface, and the particle size of the polymer 3 gradually decreases.

Once the web is sprayed with a superabsorbent polymer, use a tissue paper or various non-woven fabrics coated with various adhesives, such as hot melt adhesives, using a contact method such as a roll coater method or screen printing method, or a non-contact method such as a spray method. Wrap the web. For the coating, spray-type coating that can easily switch between the respective patterns and adjust the amount of the adhesive without contact is preferable, and it is preferable to use spray-coating that can successfully perform dotted adhesion. 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 .

  By compressing the web with a roll, a belt, or the like, the superabsorbent polymer 3 and the long fibers are securely bonded, and the embedding of the superabsorbent polymer 3 in the web becomes more remarkable. In this way, the superabsorbent polymer is buried and supported in the web 2 so as to have a particle size distribution in the thickness direction of the web.

  The web 2 has a high fiber amount region (hereinafter referred to as a high fiber amount region) Fa and a low fiber amount region (hereinafter referred to as a low fiber amount region) respectively extending in the orientation direction of the long fibers in order to screen out the superabsorbent polymer. ) Fb. These regions Fa and Fb are alternately arranged in parallel in a direction orthogonal to the orientation direction of the long fibers. The high fiber amount region Fa refers to a region where the fiber amount per unit area is relatively high when viewed in a cross section in the thickness direction of the web. The low fiber amount region Fb is a region where the amount of fibers per unit area of the web is relatively low.

  The high fiber amount region Fa makes it difficult to pass the superabsorbent polymer in the web thickness direction as compared with the low fiber amount region Fb, and makes the separation of the superabsorbent polymer by sieving more complete. Thus, on the back sheet side of the web, it is not necessary that the superabsorbent polymer having a small particle size is uniformly distributed, and may be unevenly distributed in part.

  The width of each of the high fiber amount region Fa and the low fiber amount region Fb (that is, the length in the direction orthogonal to the orientation direction of the long fibers) is not critical in the present embodiment, and the widths of these regions Fa and Fb are It may be the same or different. When the widths of the two regions Fa and Fb are different, the width of the high fiber amount region Fa may be larger than the width of the low fiber amount region Fb or, conversely, the width of the low fiber amount region Fb. However, the width may be larger than the width of the high fiber amount region Fa. Depending on the production method of the web 2, in the extreme case, the width of the low fiber amount region Fb may be much smaller than the width of the high fiber amount region Fa.

  Although it depends on the production method of the web 2, the high fiber amount region Fa and the low fiber amount region Fb have a width of 0.5 to 20 mm, particularly 2 to 10 mm. It is preferable from the point of being visually recognizable and the point of improvement in absorbability. The stripe pattern is advantageous because it gives the user a visual dry feeling.

In the high fiber amount region Fa and the low fiber amount region Fb, the fiber amounts in these regions may be changed stepwise or may be continuously changed. Fiber weight in the high fiber content region Fa is preferably from 10 to 200 g / m ^2, and still more preferably from 20 to 100 g / m ^2. On the other hand, amount of fibers in the low fiber content region Fb is preferably at 20 g / m ² or less, more preferably 3 to 10 g / m ^2. The fiber amount W1 in the high fiber amount region Fa is larger than the fiber amount W2 in the low fiber amount region Fb. Preferably, the fiber amount W1 in the high fiber amount region Fa is twice or more the fiber amount W2 in the low fiber amount region Fb. It is.

  As another method for forming the distribution of the superabsorbent polymer having a small particle diameter on the back sheet side by utilizing the sieving action of the web, there is a method of changing the basis weight, constituent fibers or density of the web. For example, there is a method of providing a region having a high thickness by overlapping another web having a different opening width on a part of the web. In this method, separation of the superabsorbent polymer is promoted in a region where the thickness is high, and a distribution of the superabsorbent polymer having a small particle diameter can be formed on the back sheet side. It is preferable to overlap the web so that the central portion in the width direction is thick from the viewpoint that the screening of the superabsorbent polymer becomes clear at the central portion in the width direction. As a result, the superabsorbent polymer having a large particle diameter allows the liquid to permeate quickly on the skin side, and the superabsorbent polymer having a small particle diameter on the back sheet side allows the liquid to be fixed quickly. Further, since the superabsorbent polymer is present in the peripheral portion of the absorber without being sieved, the liquid permeation is relatively slow compared to the central portion, and leakage can be suppressed.

  As another method, there is a method of laminating two or more types of webs made of fibers having different thicknesses. In this method, the skin side is formed of a web made of thicker fibers, and the back sheet side is formed of a web made of thinner fibers. Also in this case, the widths of the webs can be different. A web made of thick fibers has a large average interfiber distance, and only a larger superabsorbent polymer remains on the web. By combining with a web made of thin fibers, a particle size distribution in the thickness direction can be formed. it can. You may use the web from which a crimp rate differs in an upper and lower layer.

  Instead of each of the above methods, a part of the web is pre-compressed to increase the density, sieving is suppressed, and conversely, only a part of the web is compressed after the superabsorbent polymer is sprayed. For example, a method for accelerating burial in the web may be used.

  As described above, a web that does not contain a superabsorbent polymer may be laminated on the web in which the particle size distribution in the thickness direction is formed. Moreover, you may provide the web layer which does not contain superabsorbent polymer by winding up or lowering the both ends of the web which are not spraying superabsorbent polymer. That is, the present invention includes the concept that a web layer that does not contain a superabsorbent polymer exists on the outermost surface on the skin side or the back sheet side.

  The fiber amount of the web can be obtained by measuring the weight of the web cut into 100 cm × 100 cm and calculating the basis weight when the fiber amount distribution region is sufficiently large. On the other hand, when it is difficult to measure the weight by cutting the sample into a specific size, such as when the fiber amount of the web is distributed in a stripe shape, the following method is obtained as an alternative method. An absorber is prepared in a state where a load of 24.5 kPa is applied in advance for 12 hours to remove the effects of thickness recovery, wrinkles, and the like. First, the weight of the absorber cut into 10 cm × 10 cm is measured, and the basis weight of the entire absorber is calculated. In addition, the amount of the superabsorbent polymer is quantified, and the basis weight of the superabsorbent polymer is subtracted from the basis weight of the entire absorber to calculate the average basis weight of the fibers in the absorber. The amount of the superabsorbent polymer in the absorber is determined by measuring the weight and area of the entire absorber, then immersing the absorber in an ascorbic acid solution and exposing it to sunlight to dissolve the superabsorbent polymer, and washing with water. It can calculate by calculating | requiring the amount of residual fibers. Next, the absorber is cut out in a direction perpendicular to the orientation direction of the long fibers, and an area corresponding to a width of 50 mm is divided and imaged and captured as image data. An individual imaging range is 5 mm × 5 mm, and this is enlarged 25 times to capture each imaging range continuously. The obtained image is processed using image analysis processing software (Image-Pro plus, Media Cybernetics), and the area occupied by the fibers (that is, the sum of the cross-sectional areas of the individual fibers) is calculated for each image. The measurement is an average of 5 points. The area occupied by the fiber when the thickness of the web is assumed to be constant is calculated from the average basis weight of the fiber measured in advance and the cross-sectional area of one fiber (this area is referred to as the average area). A region in which the measured fiber occupies an area that is equal to or greater than the average area is defined as a high fiber amount region, and a region that is less than the average area is defined as a low fiber amount region.

  According to the above method, the superabsorbent polymer is embedded and supported in the web 2 so as to have a particle size distribution in the thickness direction of the web by a simple operation of using only one kind of polymer. It is possible to use two or more kinds of polymers having different particle size distributions and to carry the polymer embedded and supported by a method different from the above method, but in that case, the process becomes complicated and it is not easy to increase the production efficiency. . In addition, when two or more kinds of polymers are used, the absorption characteristics of the polymer in a mixed state become complicated due to different absorption characteristics, and it is not easy to obtain an absorber having desired absorption characteristics. .

  The absorbent body 1 thus obtained is thin and has a high absorption capacity. For example, when the absorbent body 1 is used in a disposable diaper for infants, it is preferable that the absorbent body 1 has a thickness of 1 to 4 mm, particularly 1.5 to 3 mm. 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. The absorbent article provided with the absorbent body 1 having a thickness in this range is preferably as thin as 1 to 10 mm. The thicknesses of the absorbent body 1 and the absorbent article are measured under a state where a weight is placed on an acrylic plate having a size of 5 cm × 5 cm on the absorbent body 1 or the absorbent article and a load of 0.245 kPa is applied. In this embodiment, the thickness was measured using an LK080 class 2 laser displacement meter manufactured by Keyence Corporation. The number of measurement points was an average of 5 points, and when the measurement value fluctuated 20% or more, the data was deleted and another measurement value was added. A 24.5 kPa load was applied to the sample in advance for 12 hours to keep wrinkles extended.

From the viewpoint of easily realizing the thickness, basis weight of the absorbent body 1, in the case of using the absorbent body 1, for example, in a disposable diaper for infants, 120~400g / m ^2, in particular 150 to 300 g / m ² It is preferable that 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 .

  2 to 4 show an unfolded disposable diaper as an example of an absorbent article including the absorbent body of the present embodiment. The diaper 10 is characterized in that solid guards extending in the longitudinal direction of the diaper 10 are doubled on both sides thereof. The diaper 10 has a top sheet 11 and a back sheet 12. The absorber 1 is disposed between these sheets 11 and 12. A water-repellent outer layer sheet 13 made of a nonwoven fabric is disposed on the outer surface of the back sheet 12. Leg flaps 20 extend laterally from the left and right side edges of the absorbent body 1.

  An elastic strand 21 extending in the longitudinal direction of the diaper 10 is arranged in an extended state on the side edge of the leg flap 20 to form a leg gather 22. Between the leg gather 22 and the side edge part of the absorber 1, the 1st solid gather 23 and the 2nd solid gather 24 which have a base end part on the leg flap 20 are each distribute | arranged. That is, two sets of a pair of opposing three-dimensional gathers are arranged. The first three-dimensional gathers 23 are arranged near the leg gathers, and the second three-dimensional gathers 24 are arranged near the absorber. The three-dimensional gathers 23 and 24 extend in the longitudinal direction of the diaper 10. Elastic strands 25 are arranged in a stretched state at the free ends of the three-dimensional gathers 23 and 24. Each of the three-dimensional gathers 23 and 24 is composed of one sheet made of a water-repellent nonwoven fabric or the like.

  The base end portion of the second three-dimensional gather 24 is joined to the topsheet 11. On the other hand, the base end portion of the first three-dimensional gather 23 is joined to the back sheet 12. Further, the elastic strands 21 in the leg gathers 22 are sandwiched and fixed by the outer layer sheet 13 and the extension part in which the first three-dimensional gathers 23 extend laterally from the base end part.

  These three gathers located on the leg flaps 22 adjust the contraction force of each gather so that the contraction force of the outermost gather is larger than the contraction force of the gathers located inward. It is preferable. That is, when the contraction force of the leg gather 22 is L1, the contraction force of the first three-dimensional gather 23 is L2, and the contraction force of the second three-dimensional gather 24 is L3, it is preferable that L1> L2, L3. In particular, it is preferable that the gather contraction force gradually decreases from the outermost gather to the inside. That is, it is preferable that L1> L2> L3. The reason is as follows.

  The conventional design method for absorbent articles is to reduce the thickness of the absorbent article and make it difficult to leak liquids, thereby increasing the shrinkage force of gathers and leaving a gap between the wearer's body and the absorbent article. Based on the idea of not. However, if the contraction force of the gathers is too strong, the marks are likely to touch the skin. In addition, when the thin and flexible or absorbent body is used as in the present embodiment, the absorbent article contracts due to the contraction force of the gathers, making it difficult to wear. If the gather contraction force is too strong, a downward force due to the contraction force acts on the absorbent article during mounting of the absorbent article, and a shift tends to occur. On the other hand, by using two or more pairs of leg gathers and a pair of opposing three-dimensional gathers and having the contraction force as described above, the above-described inconveniences that occur in conventional absorbent articles can be avoided.

  The gather contraction force is measured by the following method. A gather is cut from the absorbent article and used as a measurement sample. A hysteresis curve of the measurement sample is drawn using Tensilon ORIENTEC RTC-1150A. The stress at the return of this hysteresis curve is defined as the contraction force. The speed of pulling and returning is 300 mm / min. The initial length of the sample is 100 mm, and the maximum elongation is 100 mm (twice the original length). The stress at the time of return of the hysteresis curve is a measured value when the sample is returned 50 mm from the maximum elongation. The measurement is an average of 5 points. In the case of a sample whose maximum elongation is less than 100 mm, the elongation is up to 50 mm, and the value at that time is the measured value.

  In order to adjust the contraction force of each gather, for example, methods such as changing the thickness of the elastic body, changing the elongation rate of the elastic body, changing the number of elastic bodies, etc. are used alone or in combination.

  In the diaper 10 in which the expansion / contraction force of the gather is adjusted as described above, in the wearing state (or the relaxed state), as shown in FIG. 4, the rising height differs depending on the contraction force of the gather. is doing. That is, the leg gather 22 which is the gather with the strongest contractile force has the highest rise height, and the second solid gather 24 which is the gather with the weakest contractile force has the lowest rise height. The first three-dimensional gather 23 whose contraction force is intermediate between the leg gather 22 and the second three-dimensional gather 24 is also in the middle between the leg gather 22 and the second three-dimensional gather 24. In short, the higher the gather contraction force, the higher the rising height. The reason for this is that the gather with higher contraction force is more likely to shrink in the wearing state (or relaxed state) of the diaper 10, and the gather is more likely to rise as the area of the shrinkage is larger.

  In order for the rising height of the gathers to increase sequentially from the inside to the outside of the leg flap 20, the length t 1 from the base end portion to the free end in the first three-dimensional gather 23 is the same as that in the second three-dimensional gather 24. It is preferable that the length is longer than the length t2 from the base end portion to the free end. In addition, this makes it difficult for the second three-dimensional gather 24 to cover the top sheet 11.

  Further, the length t1 from the base end portion to the free end in the first three-dimensional gather 23 is larger than the distance t3 between the base end portion of the first three-dimensional gather 23 and the base end portion of the second three-dimensional gather 24. Is preferred. By doing so, the space formed between the first three-dimensional gather 23 and the second three-dimensional gather 24 becomes larger, and the liquid accumulated between the base ends of both gathers beyond the second three-dimensional gather 24 is further increased. It is difficult to get over the one-dimensional gather 23, and both the first three-dimensional gather 23 and the second three-dimensional gather 24 can fit the body when worn. In this embodiment, the base end of the first three-dimensional gather 23 and the base end of the second three-dimensional gather 24 are different in position, but the positions of the base ends of the two gathers 23 and 24 are the same. Thus, both gathers 23 and 24 may be raised from the same position.

  As shown in FIG. 2, in the compatible body gathers 23 and 24, the elastic strands 25 are arranged over the entire length in the longitudinal direction of the diaper 10, and the stretchable region of the compatible body gathers 23 and 24 is the entire length in the longitudinal direction of the diaper 10. Over. On the other hand, in the leg gather 22, the elastic strand 21 is distribute | arranged only to the crotch part of a diaper, and the expansion / contraction area | region of the leg gather 22 becomes only a crotch part of a diaper. The reason for this is that when the elastic strand 21 of the leg gather 22 extends to the abdomen and / or the dorsal side of the diaper, the abdomen and / or dorsal side contracts, which causes the diaper 10 to be worn. Sometimes, the operability of the fastening tape 26 tends to be reduced, or the fastening operability of the fastening tape 26 to a target tape or landing tape (not shown) to which the fastening tape 26 is fastened is likely to be lowered. Because it becomes.

  Although not shown in FIGS. 2 to 4, a sheet different from the surface sheet 11 may be disposed between the surface sheet 11 and the absorber 1. Such another sheet is generally called a sub-layer sheet. The sublayer sheet is arranged for the purpose of smoothing the permeation of the liquid from the top sheet 11 to the absorber 1 and suppressing the liquid return. Furthermore, it arrange | positions in order to suppress the deterioration of the touch resulting from the superabsorbent polymer of the large particle size distribute | arranged to the web skin side. For this purpose, the sublayer sheet is preferably a bulky sheet having a certain thickness. Accordingly, a space through which the liquid permeates from the top sheet 11 toward the absorber 1 is secured, so that the liquid can be smoothly transmitted. From this viewpoint, the sublayer sheet is preferably made of a hydrophilic non-woven fabric or a hydrophilic short fiber aggregate having a thickness of 0.1 to 5 mm, particularly 0.2 to 3 mm. As the nonwoven fabric, it is preferable to use an air-through nonwoven fabric or an airlaid nonwoven fabric from the viewpoint of easily obtaining a bulky material. A hydrophilic short fiber aggregate is also bulky, and fibers having a slightly lower hydrophilicity than natural pulp are preferable. For example, HBA pulp (bulky pulp), curly cellulose pulp, triacetate short fiber, diacetate short fiber cross-linked between fibers or within the fiber may be used alone or mixed, or laminated on tissue paper or various nonwoven fabrics. be able to.

  A synthetic fiber layer may be disposed on the lower side of the web 2. The synthetic fiber layer is composed of a synthetic fiber fused to form a sheet. The web 2 and the synthetic fiber layer are joined. For example, if the synthetic resin constituting the synthetic fiber and the long fiber material constituting the web 2 are not compatible, a part of the long fiber constituting the web 2 may penetrate the synthetic fiber layer. Alternatively, by entering into the synthetic fiber layer, the long fiber and the synthetic fiber layer are caught, whereby the web 2 and the synthetic fiber layer are joined. When the synthetic resin of the synthetic fiber and the long fiber material constituting the web 2 are compatible, the web 2 and the synthetic fiber layer 4 can be joined by fusion bonding. Alternatively, they may be joined by a commonly used adhesive such as hot melt. Even if the absorbent body 1 is deformed due to the movement of the wearer due to the synthetic fiber layer bonded to the lower side of the web 2, the small particle size contained in the back sheet side of the web 2. Of the superabsorbent polymer 3 is effectively prevented. Moreover, it becomes difficult to give a user a gel feeling peculiar to the superabsorbent polymer 3 which has swollen upon absorption. Since the synthetic fiber layer has fine voids between the fibers so as not to allow the superabsorbent polymer to pass therethrough and thereby has air permeability, the air permeability of the web 2 is not impaired.

  Synthetic fibers preferably have an average fiber length of 0.1 to 80 mm, more preferably 0.5 to 60 mm, and even more preferably 1.5 to 51 mm, and belong to a range generally called short fibers. Can be used. This fiber has a fineness of preferably 0.1 to 7.8 dtex, more preferably 0.5 to 5.6 dtex, and still more preferably 0.9 to 3.4 dtex. For example, single fibers such as polyethylene, polypropylene, polyethylene terephthalate, and composite fibers containing two or more of these resins can be used. Examples of the composite fiber include a core-sheath type and a side-by-side type. The cross-sectional shape of the synthetic fiber is circular, atypical, C-shaped, hollow, or the like.

  Synthetic pulp can also be used as the synthetic fiber. As the synthetic pulp, for example, a material made of a thermoplastic resin such as polyethylene, modified polyethylene, or polypropylene is preferably used. Synthetic pulp has an average fiber length of preferably 0.1 to 10 mm, more preferably 0.5 to 5 mm, and even more preferably 0.9 to 1.5 mm, similar to natural pulp such as wood pulp. It is preferable because it can be handled easily.

The synthetic fiber layer 4 has a basis weight of 3 to 30 g / m ² , particularly 5 to 20 g / m ² , especially 8 to 15 g / m ^2. This is preferable from the viewpoint of reducing gel feeling, preventing skin troubles and uncomfortable feeling during wearing. A three-dimensional shape may be imparted to the synthetic fiber layer by embossing or the like.

  In the embodiment shown in FIGS. 2 to 4, the base end portion of the first three-dimensional gather 23 and the base end portion of the second three-dimensional gather 24 are both located on the leg flaps 20. As shown in FIG. 5, the base end portion of the second three-dimensional gather 24 may be positioned on the absorber 1. And it is preferable to form a hole (not shown) in the junction part of the base end part of the 2nd three-dimensional gather 24, and the surface sheet 11. FIG. By configuring in this way, the liquid staying between the second three-dimensional gather 24 and the first three-dimensional gather 23 over the second three-dimensional gather 24 is reabsorbed by the absorber 1 through the holes. become. In order to form a hole in the joint portion between the base end portion of the second three-dimensional gather 24 and the topsheet 11, for example, ultrasonic joining may be used to form the joint portion. According to ultrasonic bonding, both bonding and hole formation can be performed simultaneously.

  In the embodiment shown in FIGS. 2 to 4, the second solid gather 24, the first solid gather 23, and the leg gather 22 are arranged in this order on the leg flap 20 from the inside to the outside. However, these three gathers can also be arranged as in the embodiment shown in FIG. In the embodiment shown in FIG. 6, the leg gathers 22, the second solid gathers 24, and the first solid gathers 23 are arranged in this order on the leg flaps 20 from the inside to the outside. That is, in the present embodiment, the leg gathers 22 are arranged on the innermost side. On the other hand, in the embodiment shown in FIGS. 2 to 4, the leg gathers 22 are arranged on the outermost side. Also in this embodiment, it is preferable that the gather contraction force gradually decreases from the outermost gather to the inner side, as in the embodiment shown in FIGS. That is, when the contraction force of the leg gather 22 is L1, the contraction force of the first three-dimensional gather 23 is L2, and the contraction force of the second three-dimensional gather 24 is L3, it is preferable that L2> L3> L1. The reason for this is the same as that of the embodiment shown in FIGS.

  FIG. 7 is an example in which the absorbent body of the present embodiment is applied to a pants-type disposable diaper. FIG. 7 is an exploded perspective view showing a state in which the left and right side seal portions of the pant-type disposable diaper are opened and stretched to a plane. The diaper 10 has the absorptive main body 30 and the outer layer sheet | seat 31 arrange | positioned on the outer side.

  8 is a cross-sectional view in the width direction at the crotch part of the absorbent main body 30 shown in FIG. The absorbent main body 30 has a top sheet 11 and a back sheet 12. The absorber 1 is disposed between these sheets 11 and 12. And the above-mentioned outer layer sheet | seat 31 is joined to the outer side of the back surface sheet 12. FIG. Although not shown, the above-described sublayer sheet may be disposed between the top sheet 11 and the absorber 1. The outer layer sheet 31 is obtained by bonding and fixing an elastic member 32 in an extended state in the width direction between two water-repellent sheets made of nonwoven fabric. However, the elastic member 32 is arranged so as not to cross over the absorbent main body 30. The front and rear end portions 33 of the outer layer sheet 31 are folded back to cover the front and rear end portions of the absorbent main body 30.

  In the absorptive main body 30, a pair of first three-dimensional gathers 23 and a pair of second three-dimensional gathers 24 are arranged at positions outside the left and right side edges of the absorbent body 1. That is, two sets of a pair of opposing three-dimensional gathers are arranged. However, leg gathers are not arranged in the absorbent main body 30. Leg gathers are also not arranged on the outer layer sheet 31.

  In the absorptive main body 30, the first three-dimensional gathers 23 are arranged on the outer side, and the second three-dimensional gathers 24 are arranged on the inner side (near the absorber). The three-dimensional gathers 23 and 24 extend in the longitudinal direction of the absorbent main body 30. Elastic strands 25 are arranged in a stretched state at the free ends of the three-dimensional gathers 23 and 24. The base end portion of the second three-dimensional gather 24 is joined to the topsheet 11. On the other hand, the base end portion of the first three-dimensional gather 23 is joined to the extended portion and the back sheet 12 in which the second three-dimensional gather 24 extends laterally from the base end portion.

  In the present embodiment, the contraction force of each three-dimensional gather is adjusted so that the contraction force of the first three-dimensional gather 23 located outward is larger than the contraction force of the second three-dimensional gather 24 positioned inward. Is preferred. That is, when the contraction force of the first three-dimensional gather 23 is L2, and the contraction force of the second three-dimensional gather 24 is L3, it is preferable that L2> L3. The reason for this is the same as that of the embodiment shown in FIGS.

  In the wearing state (or relaxed state) of the diaper 10, the first three-dimensional gather 23, which is the gather with the strongest contracting force, has the highest rising height, and the second three-dimensional gather 24, which is the gather with the weakest contracting force, rises. Is the lowest. The reason for this is also the same as that of the embodiment shown in FIGS. From this viewpoint, it is preferable that the length from the base end portion to the free end in the first three-dimensional gather 23 is larger than the length from the base end portion to the free end in the second three-dimensional gather 24.

  In the embodiment shown in FIGS. 7 and 8, each of the three-dimensional gathers 23 and 24 is composed of one sheet. Instead, as in the embodiment shown in FIG. 9, the two three-dimensional gathers 23 and 24 may be configured by a single sheet made of a water-repellent nonwoven fabric or the like. In the embodiment shown in FIG. 9, the second three-dimensional gather 24 is formed from one side edge of one sheet. Furthermore, in a portion adjacent to the second three-dimensional gather 24, the sheet is folded in two so that the folding line extends in the longitudinal direction of the absorbent main body 30, and a first three-dimensional gather 23 is formed in which two sheets are stacked. Elastic strands 25 are arranged inside the folding line. By setting it as such a structure, it becomes difficult for the 1st three-dimensional gather 23 to let a liquid pass. Therefore, even if the liquid gets over the second three-dimensional gather 24 and the liquid stays between the second three-dimensional gather 24 and the first three-dimensional gather 23, the liquid is less likely to leak outside through the first three-dimensional gather 23.

  Next, another embodiment of the present invention will be described with reference to FIGS. 10 (a) and 10 (b). Regarding the points that are not particularly described with respect to these embodiments, the description regarding the above-described embodiments is appropriately applied. 10A and 10B, the same members as those in FIG. 1 are denoted by the same reference numerals.

  In the embodiment shown in FIG. 10 (a), a pulp fiber layer 4 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 prominent, 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.

  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.

  In the embodiment shown in FIG. 10 (b), the web 2 containing the superabsorbent polymer 3 is covered with the fiber sheet 5. In the present embodiment, one fiber sheet 5 is used. The fiber sheet 5 covers the upper surface and both left and right side surfaces of the web 2. Furthermore, the left and right side portions of the fiber sheet 5 are wound around the lower surface side of the web 2 and overlap at the center portion in the width direction on the lower surface of the web 2. Thereby, the lower surface of the laminate is also covered with the fiber sheet 5.

  By covering the web 2 with the fiber sheet 5, extreme movement and dropping off of the superabsorbent polymer 3 contained in the web 2 can be effectively prevented. 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.

  As the fiber sheet 5, a material having a strength sufficient to prevent the superabsorbent polymer from falling off and that does not hinder the permeation of excreted liquid is appropriately used. Moreover, the fiber sheet 5 is comprised from the substantially non-water-absorbing fiber. The fiber sheet 5 is preferably made of a nonwoven fabric. The nonwoven fabric may be subjected to a hydrophilic treatment or a hole opening treatment as necessary. Further, a slit may be formed. As the non-woven fabric, for example, a fiber using a thermoplastic resin such as polyethylene, polypropylene, or 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 the embodiment shown in FIG. 1, the large diameter polymer 3a is biased on the top sheet side and the small diameter polymer 3b is biased on the back sheet side, but the absorbent article included in the scope of the present invention has this relationship. it is obtained by upside down. In other words, toward the backsheet side of the particle size of the web 2, that is greater than the particle size of the surface sheet side. By disposing the large-diameter polymer 3a on the back sheet side, the liquid is diffused more inside the absorber, so that it is possible to cope with a particularly high urine output. In addition, since the small-diameter polymer on the top sheet side has a high absorption rate, there is less liquid remaining in the top sheet, and there is an effect of improving the dry feeling of the surface. In order to express these effects, it is preferable to prevent gel blocking of the small-diameter polymer biased toward the top sheet side and increase the liquid passage speed. From this viewpoint, it is preferable to use a highly absorbent polymer having a high absorption and a high gel strength. For example, it is preferable to use a liquid passing speed under the pressure of 0.6 kPa described above that is 150 to 1500 g / min.

  As the superabsorbent polymer, it is more preferable to use a polymer having a high liquid passing rate under a load of 2.0 kPa. This load substantially corresponds to the body pressure applied to the absorbent body while wearing the absorbent article. Alternatively, when the excretion rate is fast as seen in an adult example, the value of the liquid passing rate is 30 to 300 ml / min, preferably 32 to 200 ml / min, as an absorbent polymer further thinning the absorber. The thing of 35-100 ml / min is used preferably. 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 fluid flowability in the absorber is too high, especially when a large amount of excreta is excreted at once, or when the infant is older, Not enough and may cause leaks. 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.

  A specific method for measuring the liquid flow rate under a load of 2.0 kPa is described, for example, in paragraph 0005 of JP-A-2003-235889. 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 liquid flow rate under 2.0 kPa load]
A filtering cylindrical tube provided with a wire mesh (mesh size 150 μm) and a narrow 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 wire mesh with an opening of 150 μm and a diameter of 25 mm at the tip was inserted into the filtration cylindrical tube, and the wire mesh and 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 the time measured without putting the 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.

In order to minimize the packing density of the superabsorbent polymer, it is preferable to reduce the amount of superabsorbent polymer used. Such a superabsorbent polymer preferably has a physiological water absorption of 30 g / g or more, particularly 30 to 50 g / g by centrifugal dehydration. 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

  As the superabsorbent polymer that can be used in the above-described embodiments, those described above can be used without particular limitation. 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 is obtained.

  The absorbent article of the present invention provided with an absorbent body having a long fiber web has a sparse structure with a large gap between fibers compared to a conventional absorbent body mainly composed of flap pulp. As a result, the absorber according to the present invention also has good liquid permeability. 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 the present invention, in an embodiment in which the absorbent does not contain pulp or the content in the absorbent 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. In particular, a superabsorbent polymer of 4 to 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.

  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, you may coat | cover the whole absorber 1 shown to Fig.10 (a) with the fiber sheet 5, as shown in FIG.10 (b).

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples.

[Example 1]
First, an acetate long fiber tow having crimps 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 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 crimp rate of the 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 was sprayed on the web, and the superabsorbent polymer was buried and supported in the spread web. The web was wrapped with tissue paper having a basis weight of 16 g / m ² to obtain an absorbent. The upper and lower surfaces of the web and the tissue paper were bonded with a hot melt pressure-sensitive adhesive having a basis weight of 5 g / m ² . The basis weight of the web was 26 g / m ² and the basis weight of the superabsorbent polymer was 260 g / m ² .

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 molding 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. Otherwise, a disposable diaper was obtained in accordance with a normal disposable diaper manufacturing method. The absorber was arranged so that the orientation direction of the web coincided with the longitudinal direction of the diaper.

[Example 2]
Similar to Example 1, a web in which a superabsorbent polymer was embedded and supported was obtained. However, the basis weight of the superabsorbent polymer was 110 g / m ² . Separately, 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 piled body having a total basis weight of 300 g / m ² . This laminated fiber was laminated with the web containing the superabsorbent polymer produced previously to obtain a laminate. The laminated fiber and the web were bonded with a hot melt pressure-sensitive adhesive having a basis weight of 5 g / m ² . This laminate was wrapped with tissue paper having a basis weight of 16 g / m ² to obtain an absorbent. The upper and lower surfaces of the laminate and the tissue paper were bonded with a hot melt pressure-sensitive adhesive having a basis weight of 5 g / m ² . Except these, it carried out similarly to Example 1, and obtained the disposable diaper.

Example 3
Between the absorbent body of Example 1 and the surface sheet, a core-sheath composite fiber comprising a polyethylene terephthalate core and a polyethylene terephthalate modified with a sheath (3.4 dtex in thickness, surface hydrophilized with a surfactant, liquid permeable A disposable diaper was obtained in the same manner as in Example 1 except that an air-through nonwoven fabric having a basis weight of 30 g / m ² was provided as a sublayer.

Example 4
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, A laminate was obtained in the same manner as in Example 2 except that the average basis weight of the web was 30 g / m ² . Other than that was 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 body. 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]
In Comparative Example 1, a mixture having a total basis weight of 300 g / m ² was obtained. At this time, the basis weight of the fluff pulp and the superabsorbent polymer was 150 g / m ² . 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 2.7 mm. Except these, it carried out similarly to Example 1, and obtained the disposable diaper.

[Comparative Example 3]
In Comparative Example 1, 100 parts by weight of the opened fluff pulp and 200 parts by weight of the superabsorbent polymer were mixed in an air stream to obtain a mixture having a total basis weight of 375 g / m ^2. The functional polymer dropped out and a laminate was not obtained.

[Comparative Example 4]
After opening the same web as in Example 1, a web was obtained by spreading 260 g / m ² of a superabsorbent polymer in a state where the web tension was not relaxed and no crimp was developed. The superabsorbent polymer was not embedded and supported in the web but remained on the web surface. The web was wrapped with tissue paper having a basis weight of 16 g / m ² to obtain an absorbent. The upper and lower surfaces of the laminate and the tissue paper were bonded with a hot melt pressure-sensitive adhesive having a basis weight of 10 g / m ² . Except these, it carried out similarly to Example 1, and obtained the disposable diaper.

[Performance evaluation]
The absorbent capacity and the liquid return amount of the absorbent bodies of disposable diapers obtained in Examples and Comparative Examples were measured by the following methods, and dry feeling, structural stability and flexibility were evaluated. The results are shown in Table 2 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)

[Liquid return amount and dry feeling]
160 g of colored physiological saline is injected into the central portion in the width direction at a position 150 mm from the longitudinal edge on the ventral side of the diaper using a funnel. Red No. 1 is used for coloring, and the amount of pigment added is 50 ppm (0.5 g for 10 liters of physiological saline). Ten minutes after the completion of injection, filter paper No. Put 10 sheets of 4A on the diaper. A pressure of 3.43 kPa is applied from the top of the filter paper for 2 minutes to allow the filter paper to absorb the physiological saline. The weight of the filter paper is measured, and the increase in weight is taken as the liquid return amount. Three measurements are taken.

In addition, before measuring the amount of liquid return, we asked 10 mothers the impression of the surface condition of the diaper regarding dryness. The dry feeling was determined based on Comparative Example 1. Based on the mother's impression and liquid return amount, the dry feeling of diapers was evaluated according to the following criteria.
A: More than half of the mothers answered that they had a dry feeling of Comparative Example 1 or more, and the liquid return amount was 0.2 g or less.
○: More than half of the mothers answered that they had a dry feeling equivalent to that of Comparative Example 1, and the liquid return was more than 0.2 and 0.3 g or less.
(Triangle | delta): The mother who answered that there is a dry feeling does not reach half, or a liquid return exceeds 0.3g.
X: More than half of mothers answered that there was no dry feeling, and liquid return exceeded 0.4g.

[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 the absorber would not be destroyed when the absorber was gently lifted. Also, the weight of the dropped superabsorbent polymer was measured, and the weight of the dropped superabsorbent polymer when dried was divided by the centrifugal retention per unit weight of the dropped superabsorbent polymer measured separately. calculate. Furthermore, the ratio of the superabsorbent polymer dropped off from the relationship with the blending amount of the superabsorbent polymer is calculated. The amount of the superabsorbent polymer blended was determined by immersing the absorbent to be analyzed in advance in an ascorbic acid aqueous solution and exposing it to sunlight for a sufficient amount of time to completely decompose the superabsorbent polymer. Let Washing with water and decomposition are repeated, the superabsorbent polymer is completely dissolved and then dried, and the blending amount of the superabsorbent polymer can be estimated from the difference in the weight of the absorber before the decomposition.
○: 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 orthogonal 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 Kagaku Seiki Seisakusho. 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.

  As is clear from the results shown in Table 2, it can be seen that the absorbers of the examples have a high absorption capacity and a small liquid return amount. It can be seen that the structural stability is high and the flexibility is also good.

It is a schematic diagram which shows the structure of the absorber which concerns on one Embodiment of the absorbent article of this invention. It is a top view which shows the expansion | deployment type disposable diaper as one Embodiment of the absorbent article of this invention. It is the III-III sectional view taken on the line in FIG. It is a principal part enlarged view in the mounting state (relaxed state) of the diaper shown in FIG. It is sectional drawing (FIG. 3 equivalent view) which shows another embodiment of the diaper shown in FIG. It is sectional drawing (FIG. 3 equivalent view) which shows another embodiment of the diaper shown in FIG. It is a disassembled perspective view which shows the underpants type disposable diaper as another embodiment of the absorbent article of this invention. It is width direction sectional drawing of the crotch part of the absorptive main body in the diaper shown in FIG. It is width direction sectional drawing (FIG. 8 equivalent figure) of the crotch part of the absorptive main body which shows another embodiment of the diaper shown in FIG. It is a schematic diagram (figure 1 equivalent view) which shows other embodiment of the absorber in the absorbent article of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Absorber 2 Web 3 Superabsorbent polymer 3a Large diameter polymer 3b Small diameter polymer 4 Stacked fiber layer 5 Fiber sheet 10 Disposable diaper

Claims (6)

An absorbent article comprising an absorbent body comprising a hydrophilic long fiber web and a superabsorbent polymer embedded and supported in the web,
The superabsorbent polymer has different particle sizes on the top sheet side and the back sheet side of the web ,
The superabsorbent polymer is an absorbent article in which the particle size on the back sheet side of the web is larger than the particle size on the top sheet side . The absorptive article according to claim 1 by which a sublayer sheet is arranged between an absorber and a surface sheet. The absorbent article according to claim 1 or 2, wherein the superabsorbent polymer has a liquid passage speed under a pressure of 0.6 kPa of 150 to 1500 g / min. The absorbent article according to any one of claims 1 to 3, wherein a three-dimensional guard extending in the longitudinal direction of the absorbent article is doubled on both sides. The absorbent article according to any one of claims 1 to 4, wherein the long fibers are crimped and the crimp rate is 10 to 90%. The absorbent article according to any one of claims 1 to 5, wherein the long fibers are oriented in a planar direction of the absorbent body.

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