JP2007105494A - Absorbent article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absorbent article having an absorbent body which is thinned and reduced in weight, while keeping an absorbent capacity being substantially the same as that of a conventional absorbent body. <P>SOLUTION: An absorbent article has an absorbent member 1 containing a web 2 of hydrophilic long fibers. The long fibers have a crimp percentage of 20% to 90% and are oriented in the planar direction of the absorbent member 1. The web 2 has a superabsorbent polymer embeddedly supported therein. The absorbent member 1 preferably has two or more webs 2 and a superabsorbent polymer layer 3 sprinkled between the webs 2 and 2 with part of the superabsorbent polymer being embeddedly supported in the web 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to absorbent articles such as disposable diapers, sanitary napkins, and incontinence pads. Moreover, this invention relates to the absorber used for an absorbent article, and its manufacturing method.

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

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

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

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

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

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

  The present invention is an absorbent article comprising an absorbent comprising a hydrophilic long fiber web, the long fibers having a crimp rate of 20 to 90% and oriented in the planar direction of the absorbent. The above object is achieved by providing an absorbent article in which a superabsorbent polymer is embedded and supported in the web.

  Further, the present invention comprises a plurality of hydrophilic long-fiber webs having a crimp rate of 20 to 90%, and a superabsorbent polymer layer dispersed between the webs. Is partially embedded and supported in the web, and provides an absorbent body in which the webs are bonded in a dotted pattern.

Furthermore, the present invention is a method for producing an absorbent body comprising a superabsorbent polymer in a web composed of long fibers having crimps,
A step of opening the web in a state in which the web is stretched and stretched in the longitudinal direction; and a step of supplying the superabsorbent polymer to the web in a state in which the tension of the opened web is relaxed. The manufacturing method of the absorber containing is provided.

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

  Hereinafter, the present invention will be described based on preferred embodiments thereof. 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-permeable or water-repellent sheet such as a thermoplastic resin film or a laminate of the film and a nonwoven fabric can be used. The back sheet may have water vapor permeability. The absorbent article may further include various members according to specific uses of the absorbent article. Such members are known to those skilled in the art. For example, when applying an absorbent article to a disposable diaper or a sanitary napkin, a pair or two or more pairs of three-dimensional guards can be disposed on the left and right sides of the topsheet.

  FIG. 1 shows a schematic diagram of an embodiment of an absorbent body according to the present invention. The absorbent body 1 of the present embodiment is characterized by being thin and having a low basis weight while having a sufficient absorption capacity. The absorbent body 1 having such characteristics mainly includes a long fiber web (hereinafter referred to as web 2) and a superabsorbent polymer spray layer (hereinafter referred to as polymer layer 3). The absorber 1 includes a plurality of webs 2, and a polymer layer 3 is located between the webs 2 and 2. The web needs to have at least two layers, but the upper limit is not particularly limited, and an appropriate number of webs is used depending on the specific application of the absorbent article. Since the absorbent body 1 according to the present invention is characterized by being thin and having a low basis weight, the upper limit of the number of webs is naturally determined from this viewpoint.

Long fibers are hydrophilic. 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 particularly preferred are acetate and rayon long fibers. In particular, acetate is particularly preferable because it retains bulkiness even when wet. As the acetate, cellulose triacetate and cellulose diacetate are preferable.

In addition, a crimped fiber is used as the long fiber. The long fiber has a crimp rate (JIS L0208) of 20 to 90%, preferably 40 to 90%, more preferably 50 to 80%. By forming a web from crimped long fibers, it becomes easy to stably and highly embed a superabsorbent polymer in the web. If the web is composed only of long fibers that do not have crimps or have a small degree of crimp, and this is used as an absorbent body, when a large amount of superabsorbent polymer is used, its extreme movement and dropout may occur. It is easy to happen. On the other hand, if long fibers with a too high crimp rate are used, it is not easy to allow the superabsorbent polymer to enter between the long fibers. It is easy to happen. 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 when the long fiber is stretched and the length of the original long fiber to the length 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.

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

  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 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.

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

  As described above, since the long fiber has crimps, it has a large number of spaces capable of holding particles. The superabsorbent polymer is retained in the space. As a result, even if a large amount of superabsorbent polymer is sprayed, the extreme movement or dropout is less likely to occur. Moreover, even if a wearer performs intense operation | movement, the structure of the absorber 1 becomes difficult to be destroyed. Depending on the superabsorbent polymer used, the crimp rate and the amount of long fibers used are adjusted as appropriate.

The absorbent body 1 having the above structure is thin and has a low basis weight. Appropriate values are selected for the thickness and basis weight of the absorbent body 1 according to the specific application of the absorbent article. For example, when used as an absorbent body for disposable diapers for infants, the web 2 preferably has a basis weight of 5 to 200 g / m ² , particularly 10 to 100 g / m ² . In this case, the basis weight of the web 2 may be the same or different. On the other hand, the spreading basis weight of the superabsorbent polymer is preferably 50 to 500 g / m ² , particularly preferably 100 to 300 g / m ² . The basis weight of each polymer layer 3 may be the same or different.

When used as an absorbent body of a sanitary napkin, each web 2 has a basis weight of 5 to 100 g / m ² , particularly preferably 10 to 50 g / m ² . On the other hand, the spreading basis weight of the superabsorbent polymer is preferably 10 to ²⁰⁰ g / m ² , particularly preferably 15 to 100 g / m ² . When used as an absorbent body for an incontinence pad, each web 2 preferably has a basis weight of 5 to 200 g / m ² , particularly 10 to 100 g / m ² . On the other hand, the spreading basis weight of the superabsorbent polymer is preferably 10 to 500 g / m ² , particularly preferably 15 to 350 g / m ² .

  When the basis weight of the web 2 is relatively small and the basis weight of the polymer layer 3 is relatively large in relation to the basis weight of each layer, the superabsorbent polymer extends over the entire thickness direction of the web 2. It will be buried and carried. As a result, the distinction between the adjacent polymer layers 3 and 3 and the webs 2 and 2 is not apparent, and the superabsorbent polymer may be distributed over the entire thickness direction of the absorbent body 1. That is, the present invention relates to a matrix composed of a hydrophilic long fiber web having a crimp rate of 20 to 90%, and a superabsorbent polymer uniformly embedded and dispersed throughout the thickness direction of the matrix. Including an embodiment of an absorber having

Since the superabsorbent polymer is stably held in the space formed by the crimped long fibers, the absorbent body 1 according to this embodiment can hold a large amount of the superabsorbent polymer. Even in the conventional absorbent body, if the amount of the fiber material is increased, a large amount of the superabsorbent polymer can be retained, but in this case, the basis weight and thickness of the absorbent body are increased. On the other hand, in the present invention, the amount of the superabsorbent polymer is 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 wt% or less, particularly 20 wt% or less, especially 10 wt% or less, based on the total amount of the superabsorbent polymer present in the test piece, It can be said that this is a state in which the extreme movement and dropout of the functional polymer are difficult to occur.

  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% NaCl) is evenly sprayed on the test piece subjected to the test for dropout evaluation, and the way of swelling of the test piece is visually observed. When the variation in the thickness of the test piece is within 2 times, it can be said that it is difficult for the superabsorbent polymer to move or drop off.

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

  When the superabsorbent polymer is not sufficiently embedded in the web, hot melt adhesives, various binders (such as acrylic emulsion adhesives), sugar derivatives such as carboxymethylcellulose and ethylcellulose, polyethylene, polypropylene, polyethylene terephthalate, etc. These thermoplastic resins and the like can be appropriately added to the web. Furthermore, you may use together the sheet | seat etc. which gave uneven | corrugated processing or flocking.

The total basis weight of the web and the polymer layer 3 in the absorbent body 1 according to the present embodiment is preferably 120 to 400 g / m ² , particularly 150 to 300 g / m when the absorbent body 1 is used for, for example, a disposable diaper. The value is ² . 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 .

  The dispersion state in the thickness direction of the superabsorbent polymer in the absorbent body 1 is as described above, and examples of the dispersion state in the planar direction include the following. First, a typical sprayed state includes a state in which the superabsorbent polymer is sprayed uniformly in the plane direction. As another spraying state, as shown to Fig.2 (a) and (b), the state sprayed so that a superabsorbent polymer may be biased to the front side of an absorber is mentioned. In FIG. 2A, the spreading basis weight is the same in the width direction of the absorber, and the spreading basis weight is higher toward the front side of the absorber. In FIG.2 (b), the superabsorbent polymer is spread | dispersed so that it may become a U-shape opened toward the back side of the absorber. The absorber in which the superabsorbent polymer is dispersed so as to be biased toward the front side of the absorber has a high effect of preventing liquid leakage from the front side of the body. Such an absorbent body is particularly useful as an absorbent body of a pants-type disposable diaper.

  In the absorbent body shown in FIG. 3, the superabsorbent polymer is dispersed so as to be biased toward the rear side of the absorbent body. Specifically, the superabsorbent polymer is sprayed so as to have a U-shape opening toward the front side of the absorber. The absorber in which the superabsorbent polymer is dispersed so as to be biased toward the rear side of the absorber has a high effect of preventing liquid leakage from the rear side of the body. Such an absorbent body is particularly useful as an absorbent body for disposable diapers for low-age infants and bedridden people.

  In the absorber shown in FIG. 4, the superabsorbent polymer is not sprayed on the peripheral region of the absorber, and the superabsorbent polymer is sprayed on the central region surrounded by the peripheral region. Since the superabsorbent polymer is not sprayed on the peripheral region of the absorber, it is possible to effectively prevent the superabsorbent polymer from falling off the absorber.

  In addition to or instead of the superabsorbent polymer spraying state shown in FIGS. 2 to 4, the superabsorbent polymer spraying state can be changed in the width direction of the absorbent body 1. For example, the spreading basis weight of the superabsorbent polymer in the center part in the width direction of the absorbent body can be made higher than the spreading basis weight of the superabsorbent polymer in both side parts in the width direction. By doing in this way, the liquid leak from a wearer's leg periphery can be prevented effectively. Such an absorber is suitable as an absorber of a disposable diaper. On the other hand, the spreading basis weight of the superabsorbent polymer at both sides in the width direction of the absorber can be made higher than the spreading basis weight of the superabsorbent polymer at the center portion in the width direction. By doing in this way, the spot absorptivity of an absorber can be improved. Such an absorbent body is suitable as an absorbent body for incontinence pads for light incontinence and sanitary napkins. When changing the dispersion state of the superabsorbent polymer in the width direction of the absorbent body 1, it is preferable that at least the crotch part of the absorbent body 1 has the above-described structure.

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

  The degree of orientation of the long fibers is preferably 1.2 or more, particularly 1.4 or more in terms of the degree of orientation. In this embodiment, the degree of orientation is measured using a Microwave molecular orientation analyzer MOA-2001A manufactured by KANZAKI. The sample size is 100 mm in the longitudinal direction and 50 mm in width, and the average value of three points is the degree of orientation. When the sample size is less than this size, measurement is performed by arranging a plurality of samples so as not to overlap each other.

  One means for further preventing side leakage is to use a linear long fiber web. This is because such a long fiber is superior in liquid diffusibility in the orientation direction of the long fiber as compared with a long fiber web having crimps. From this point of view, it is preferable that a part of the crimped long fibers in at least one of the plurality of webs 2 is stretched and kept in a linear state. For example, when the absorbent body 1 has a two-layer web 2, it is excreted by stretching a part of the web 2 on the surface sheet side, for example, a crimped long fiber located in the center in the longitudinal direction to make it linear. The liquid can be preferentially guided in the front-rear direction of the absorber.

  Alternatively, in addition to the web 2 made of crimped long fibers, the same effect can be obtained by further using a hydrophilic long fiber web having no crimps. For example, two layers of webs 2 made of crimped long fibers can be used, and a web made of long fibers without crimps can be arranged on the upper layer via a polymer layer.

  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 0.2 to 15 mm.

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

  In the absorbent body according to the present embodiment, since the superabsorbent polymer is held in the space formed by the crimped long fibers, the polymer is unlikely to move or fall off and the wearer is intense. The absorber 1 is less likely to be destroyed by the operation. In order to make these effects more prominent and to reduce the “sharpness” that occurs when the superabsorbent polymers rub against each other, in the absorbent body 1 according to the present embodiment, the webs 2 and 2 that overlap each other. Is glued. In this case, the overlapping webs 2 and 2 are adhered in a dotted pattern so that the preferential diffusion of the liquid in the orientation direction of the long fibers described above is not inhibited. Adhering in the form of scattered dots means that the shape of the bonding points does not have great anisotropy, and such bonding points are evenly distributed over the entire area in the plane direction of the web 2. Say. As a typical bonding mode, there is a mode in which the overlapping webs 2 and 2 are bonded by a large number of dot-shaped small bonding points. For example, a method of applying a hot melt pressure-sensitive adhesive by a spray method may be used as the dotted adhesive. Examples of the spray method include a slot spray method, a curtain spray method, a melt blown method, and a spiral spray method. When such a coating method is used, not only the webs 2 are bonded to each other, but also the web 2 and a part of the superabsorbent polymer may be bonded.

  The absorbent body 1 according to the present embodiment may be composed only of a laminate of the web 2 and the polymer layer 3, or the laminate may be wrapped with, for example, paper such as tissue paper or non-woven fabric. Further, a dry pulp sheet or a fluff pulp stacking layer may be disposed on the upper and lower surfaces of the laminate of the web 2 and the polymer layer 3, respectively, and the whole of the laminate may be wrapped with paper or non-woven fabric such as tissue paper. It may be rare. When the absorbent body 1 is used in a disposable diaper, the thickness of the absorbent body 1 is preferably 1 to 4 mm, more preferably 1.5 to 3 mm, regardless of the form of the absorbent body 1 described above. is there. 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 thickness of the absorber 1 is measured under a state where a weight is placed on an acrylic plate having a size of 5 cm × 5 cm on the absorber 1 and a load of 2.5 g / cm ² 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 250 g / cm ² load was previously applied to the sample for 12 hours to keep the wrinkles extended.

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

  As another method of the above production method, there is a method in which the web 2 made of opened long fibers is stretched to a predetermined length, and a superabsorbent polymer is sprayed in that state. In this case, it is not necessary to stretch the long fibers completely, and it is sufficient to stretch the superabsorbent polymer so that it is stably embedded and held in the web 2.

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

  After the application of the adhesive is completed, the superabsorbent polymer is spread on the web 2. Overlay the web 2 prepared separately after the completion of spraying. Next, the stretched state of the long fiber is released. As a result, the stretched long fibers contract. As a result, the superabsorbent polymer is retained in the space formed by the shrinkage of the long fibers. In this way, the superabsorbent polymer is buried and supported in the web 2. As a result, the two webs 2 are bonded in the form of dots.

  Alternatively, after the superabsorbent polymer is sprayed on the web 2, a plurality of intermediates obtained by releasing and contracting the stretched state of the web 2 are prepared, and finally the intermediates are superposed. The absorber 1 can also be obtained. In this case, since the polymer layer 3 is positioned on the uppermost layer of the absorbent body 1, there is a concern that the superabsorbent polymer may move or drop out. However, the absorbent body may be made of tissue paper or nonwoven fabric. Such an inconvenience can be avoided by wrapping the whole 1.

  When the absorbent body 1 is in the form shown in FIG. 7 (c) or FIG. 7 (d) described later, that is, a product of a long fiber web embedded with a superabsorbent polymer, pulp and a superabsorbent polymer. In the case of a laminated body with a fine body, the following manufacturing method can be employed.

  The apparatus shown in FIG. 5 can be used for manufacturing. The apparatus 10 shown in FIG. 5 includes a stacking drum 12 having a hood 11. The stacking drum 12 has a large number of recesses 13 on its peripheral surface. A plurality of the concave portions 13 are provided at predetermined intervals along the rotation direction of the fiber stacking drum 12. The bottom surface of the recess 13 is made of a breathable material. The inside of the stacking drum 12 is connected to a suction device (not shown), and air is sucked into the drum 12 from the outside of the drum 12 through the breathable material. A partition (not shown) is provided in the stacking drum 12 for air suction. In FIG. 5, when the recess 13 is located in the area indicated by the symbol A, suction through the bottom of the recess 13 is performed. Suction is not performed when the recess 13 is located in the region indicated by the symbol B.

  The pulp and superabsorbent polymer supplied from a pulp and superabsorbent polymer supply device (not shown) are conveyed to the air flow and deposited in the recess 13. Separately from this, the web is opened using a fiber opening device (not shown) while transporting in a state where tension is applied to the web of the long fiber web and stretched in the longitudinal direction. The opened web 14 is conveyed while being held on the circumferential surface of the stacking drum 12. The pulp and superabsorbent polymer piles 15 deposited in the recesses 13 located in the region indicated by the reference symbol B are released from the suction state in the region and transferred onto the web 14. When transferring the stacked fiber 15, the suction box 16 is disposed on the surface of the web 14 opposite to the transfer surface of the stacked fiber 15, and suction is performed to reliably transfer the stacked fiber 15. In this way, the stacked fiber 15 is laminated on the web 14.

  The supply amount of the pulp and the superabsorbent polymer to the stacking drum 12 is a large excess of the superabsorbent polymer supply amount compared to the pulp supply amount. By providing such a difference in the supply amount of both, in the fiber stack 15 formed in the recess 13, the pulp and the superabsorbent polymer are mixed in substantially equal amounts. The polymer is deposited on the surface of the stacked fiber 15. The excess superabsorbent polymer deposited on the surface of the stacked fiber 15 is embedded and supported in the web 14 by transferring the stacked fiber 15 to the web 14. In order to effectively carry out the embedment, the web 14 after being opened is sucked by the suction box 17 before the web 14 is held by the peripheral surface of the stacking drum 12, thereby reducing the conveyance tension. deep. Thereby, the stretched state of the web is released, and the long fibers return to the crimped state. Under this condition, an excessive amount of superabsorbent polymer is transferred from the laminated body 15 to the web 14. The superabsorbent polymer is buried and supported in the gaps between the long fibers in a crimped state. The superposed absorption of the superabsorbent polymer is further ensured by suction by the suction box 16 installed on the downstream side of the stacking drum 12.

  By the above method, it is possible to easily manufacture an absorbent body composed of a laminate of the long fiber web 14 in which the superabsorbent polymer is embedded and supported, and the laminated fiber 15 containing the pulp and the superabsorbent polymer. The above method is an efficient method in that the superabsorbent polymer can be contained in both the web 14 and the fiber stack 15 by supplying the superabsorbent polymer once.

  Moreover, according to the above method, there exists an advantage that the particle size of the excess superabsorbent polymer deposited on the surface of the pile 15 can be controlled. Superabsorbent polymers generally have a particle size distribution. When the superabsorbent polymer is transported to the air stream, the ease of transport differs due to the difference in particle size. As a result, the polymer on the small particle size side in the particle size distribution curve is easily mixed in the pulp, and the polymer on the large particle size side is easily deposited on the surface of the pile 15. That is, a relatively small particle size polymer exists in the stacked fiber 15, and a relatively large particle size polymer exists in the web 14. When the absorbent body 1 composed of the web 14 and the fiber stack 15 provided with such a difference in the particle size of the polymer is used in the form shown in FIG. There is an advantage of becoming.

  Next, another embodiment of the present invention will be described with reference to FIGS. Regarding points that are not particularly described with respect to these embodiments, the description in detail regarding the embodiment shown in FIG. 1 is applied as appropriate. Moreover, in FIGS. 6-10, the same code | symbol is attached | subjected to the same member as FIGS. 1-4.

  The absorber 1 shown in FIG. 6A is composed of a single-layer web 2. The superabsorbent polymer is uniformly embedded and supported in the web 2. Similarly to the absorbent body 1 shown in FIG. 6A, the absorbent body 1 shown in FIGS. 6B and 6C is also composed of a single-layer web 2. However, in the absorbent body 1 shown in FIGS. 6B and 6C, the superabsorbent polymer is biased and carried with respect to the thickness direction of the web 2. Specifically, in the absorbent body 1 shown in FIG. 6 (b), the superabsorbent polymer is biased and embedded in the web 2 on the skin facing surface side of the web 2. On the other hand, in the absorbent body 1 shown in FIG. 6C, the superabsorbent polymer is biased and embedded in the web 2 on the non-facing surface side of the web 2. In the absorbent body 1 shown in FIGS. 6B and 6C, the abundance of the superabsorbent polymer may change continuously in the thickness direction of the web 2 or may change stepwise. Good. The absorbent body 1 shown in FIG. 6 (b) is suitable as an absorbent body for light incontinence pads and sanitary napkins because of its high spot absorptivity. The absorbent body 1 shown in FIG. 6C is suitable as an absorbent body for disposable diapers because of its high liquid diffusibility and high liquid absorbability throughout the absorbent body.

  The absorbent body 1 shown in FIG. 7A has a structure in which a web 2 is overlaid on a fluff pulp stacking layer 4. A superabsorbent polymer is embedded and supported in the web 2. In the absorbent body 1, the fluff pulp stacking layer 4 acts as a primary stock layer of the excreted liquid, so even if the liquid excretion rate is high (for example, when urine is excreted), the liquid Leakage can be effectively prevented. From this point of view, it is preferable that the superabsorbent polymer embedded and supported in the web 2 is biased and embedded in the surface of the web 2 that is not facing the skin. However, the superabsorbent polymer can be dispersed as shown in FIGS. 6 (a) and 6 (b). This absorber 1 is suitable as an absorber of a disposable diaper.

  The absorbent body 1 shown in FIG. 7B has a structure in which a plurality of laminated bodies 5 each having a web 2 stacked on a fluff pulp stacking fiber layer 4 are laminated. The absorbent body 1 having this structure has a higher liquid leakage preventing effect than the absorbent body 1 shown in FIG.

  The absorbent body 1 shown in FIG. 7 (c) is obtained by mixing a superabsorbent polymer in the fluff pulp pile fiber layer 4 in the absorbent body 1 shown in FIG. 7 (a). The absorber having this structure has a higher effect as a primary stock layer of the liquid by the fluff pulp stacking layer 4. As is obvious to those skilled in the art, it is possible to form a laminate as shown in FIG. 7B using the absorber 1 shown in FIG. Furthermore, it is also possible to form a laminate as shown in FIG. 7B by using the absorber shown in FIGS. 7A and 7C.

  The absorbent body 1 shown in FIG. 7D is obtained by inverting the stacking relationship between the fluff pulp stacking layer 4 and the web 2 in the absorbent body shown in FIG. 7C. When the wearer's body pressure is applied to the absorbent article, for example, the absorbent article having the absorbent body 1 has good absorbability when the wearer is in a sleeping position or a sitting position.

  The absorber 1 shown to Fig.8 (a) and (b) has the structure where the webs 2 and 2 were distribute | arranged on the upper and lower sides of the pile fiber layer 4 of a fluff pulp, respectively. In the absorbent body shown in FIG. 8A, in each web 2, the superabsorbent polymer is biased and carried on the skin non-facing surface side of the web 2. On the other hand, in the absorbent body shown in FIG. 8B, in the upper web 2, the superabsorbent polymer is biased and buried on the skin non-facing surface side of the web 2, while the lower side In the web 2, the superabsorbent polymer is biased and carried on the skin facing surface side of the web 2. According to the absorber shown to Fig.8 (a), a liquid can be temporarily stocked. In addition, since the diffusing layer is on the skin contact surface side and the absorber intermediate region, the liquid that could not be absorbed on the upper layer side can be further diffused on the lower layer side. Therefore, the use efficiency of the superabsorbent polymer is increased, and as a result, it has a characteristic that a large amount of high-speed liquid can be absorbed quickly. Therefore, the absorbent body according to the present embodiment is suitably used as, for example, a pants-type diaper, training pants or rice pants for an infant having a relatively high age. On the other hand, since the absorbent body shown in FIG. 8B is a mechanism for fixing the liquid stocked in the fluff pulp stacking fiber layer 4 with the upper and lower superabsorbent polymers, it is difficult to cope with a very high speed liquid. However, the space on the most non-skin contact surface side exhibits cushioning properties and can be designed to take advantage of the texture of the diaper. Furthermore, since the final fixing position of the liquid is in the central part in the absorber thickness direction, the liquid has a characteristic that the liquid return is small. Therefore, the absorbent body of the present embodiment is suitably used as a diaper for infants of low-age infants that are strongly required to be gentle to the skin and soft.

  The absorbent body 1 shown in FIG. 9 has a structure in which a hydrophilic long fiber web 6 not containing a superabsorbent polymer is disposed below the web 2 in which the superabsorbent polymer is embedded and supported. ing. When the long fibers of the web 6 are crimped, particularly when the web 6 has the above-described crimp rate, the web 6 acts as a cushion layer against pressing in the thickness direction. A feeling of wear improves.

  In the absorbent body 1 shown in FIG. 10, a long fiber web 2 is folded in three along the longitudinal direction in an inwardly folded state, and the superabsorbent polymer 3 is held inside the trifolded web 2. It is what. The absorbent article provided with the absorbent body 1 having such a configuration has an advantage that the supportability of the superabsorbent polymer is further improved. In addition to this, even when the absorbent article is touched from any side of the top sheet side and the back sheet side, it is difficult to give a feeling of shaving caused by the superabsorbent polymer, and the absorbent article is soft and soft. There is also an advantage that it can be granted. Also, the overlapping of the webs increases the thickness and improves the soft feeling. Furthermore, the fit to the body is improved. Furthermore, it also functions as a primary stock of liquid, and is effective in quickly absorbing liquid and preventing leakage.

  In the absorbent body 1 shown in FIG. 10, a hydrophilic short fiber, a superabsorbent polymer, a thermoplastic synthetic pulp or various binders (polyvinyl acetate, acrylic emulsion, etc.) are placed inside a tri-folded web 2. An airlaid absorber comprising: Since the air-laid absorbent body has high rigidity, there is an advantage that the absorbent article is firm. In particular, there is an advantage that the absorption rate under pressure is fast. On the other hand, since the air-laid absorbent body has high rigidity, there is a possibility that a discomfort during wearing or a skin trouble due to rubbing may occur, and a soft feeling may not be sufficient. Therefore, by covering a part or the whole of the airlaid absorber with the web 2, it is possible to reduce the demerit of hardness while taking advantage of the features of the airlaid absorber.

By the way, sanitary napkins and incontinence pads generally have a smaller product size (area) than paper diapers and the like. Therefore, an absorption region having a high absorption capacity may be provided in a part of the product to impart spot absorption. When using the absorber which concerns on each above-mentioned embodiment as a high absorption area | region, it is preferable that this high absorption area | region forms a convex shape as a whole. In that case, it is preferable that the web 2 has a basis weight of 100 to 1000 g / m ² , particularly 200 to 500 g / m ² . On the other hand, the spreading basis weight of the superabsorbent polymer is preferably 50 to 1000 g / m ² , particularly preferably 100 to 500 g / m ² .

The density of the web in each of the aforementioned embodiments is preferably 0.005 to 0.20 g / m ³ , more preferably 0.01 to 0.10 g / m ³ . If the density is within this range, the permeation rate of the liquid can be controlled to an appropriate range commensurate with the absorption rate of the superabsorbent polymer. Moreover, the softness of the absorber can be maintained. Furthermore, the fiber spacing of the web can be set to an appropriate range, and the supporting performance of the fine superabsorbent polymer can be improved.

  The superabsorbent polymer used in each of the above-described embodiments has a water absorption of 30 g / g or more, particularly 30 to 50 g / g, based on the centrifugal dehydration method. It is preferable from the point which prevents that the gel feeling after liquid absorption falls. The amount of absorption of the superabsorbent polymer by centrifugal dehydration is measured as follows. That is, 1 g of superabsorbent polymer was swollen with 150 ml of physiological saline for 30 minutes, then placed in a 250 mesh nylon mesh bag, dehydrated with a centrifuge at 143 G (800 rpm) for 10 minutes, and the total weight after dehydration was determined. taking measurement. Next, the amount of water absorption (g / g) by centrifugal dehydration is calculated according to the following formula. Water absorption by centrifugal dehydration method = (total weight after dehydration−weight of nylon mesh bag−weight of highly absorbent polymer when dried−weight of nylon mesh bag liquid remaining) / weight of highly absorbent polymer when dried

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

  The superabsorbent polymer that can be used in each of the above-described embodiments is not particularly limited as long as it satisfies the above-mentioned characteristics. Specifically, for example, sodium polyacrylate and (acrylic acid-vinyl alcohol) Examples thereof include a polymer, a crosslinked polyacrylic acid soda, a (starch-acrylic acid) graft polymer, a (isobutylene-maleic anhydride) copolymer and a saponified product thereof, potassium polyacrylate, and cesium polyacrylate. In order to satisfy the above characteristics, for example, a crosslink 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 absorbent body of the present invention having a long fiber web has a sparse structure with large gaps between fibers compared to a conventional absorbent body mainly composed of flap pulp, so that the absorbent body is permeable to liquid. It is also a good thing. Therefore, when the absorption rate of the superabsorbent polymer is slow, the liquid may pass through the absorber before being absorbed by the superabsorbent polymer, and may not be sufficiently absorbed by the absorber. From this viewpoint, it is preferable that the superabsorbent polymer contained in the web has a sufficiently high absorption rate. Thereby, the liquid can be reliably held in the absorber. The absorption rate of a superabsorbent polymer is generally expressed in the art by the measured value of the DW method. The absorption rate (ml / 0.3 g · 30 sec) by the DW method is measured using an apparatus (Demand Wettability Tester) generally known as an apparatus for performing the DW method. Specifically, the superabsorbent polymer to be measured is placed on a polymer spray table (70 mmφ, No. 2 filter paper placed on the glass filter No. 1) with the saline level set at an equal water level. Spray 0.3g. The amount of water absorption at the time of spraying the superabsorbent polymer is set to 0, and the amount of water absorption after 30 seconds (this absorption amount is measured by a burette scale indicating the amount of decrease in the physiological saline water level) is measured. The value of the obtained absorption amount is taken as the water absorption rate. The absorption rate can be designed by the shape, particle size, bulk density, degree of crosslinking, etc. of the superabsorbent polymer.

  In an embodiment where the absorber does not contain pulp or the content in the absorber is 30% by weight or less, the absorption rate measured according to the DW method is 2-10 ml / 0.3 g · 30 sec, in particular 4-8 ml. A superabsorbent polymer of /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 described above, a superabsorbent polymer having a short liquid passage time or a superabsorbent polymer having a high absorption rate may be used alone. Absorbent polymers may be mixed or coexisted. For example, the superabsorbent polymer S1 having a relatively short liquid passage time and the superabsorbent polymer S2 having a relatively long liquid passage time may be mixed and used. In this case, when the superabsorbent polymer S1 and the superabsorbent polymer S2 are compared, the superabsorbent polymer S2 has higher absorption capacity and absorption speed, but has low resistance to gel blocking. By making the superabsorbent polymer S1 and the superabsorbent polymer S2 coexist, the superabsorbent polymer S1 that is hard (that is, gel blocking is unlikely to occur) enters between the superabsorbent polymer S2 having a high absorption performance. Can be used more efficiently. As another example, there is a method in which a superabsorbent polymer S3 having a relatively high absorption rate and a superabsorbent polymer S4 having a relatively low absorption rate coexist. In this case, the superabsorbent polymer S3 is arranged on the back sheet side, and the superabsorbent polymer S4 is arranged on the top sheet side, thereby further increasing the liquid uptake speed of the absorbent and fixing the liquid. Can be increased. As another example, the same effect can be obtained by arranging the superabsorbent polymer S1 having a short liquid passage time on the top sheet side and the superabsorbent polymer S3 having a high absorption rate on the backsheet side.

  By using the absorbent polymer having the specific absorption performance described above, the amount of liquid return is further reduced even though the absorbent body of the present invention is thin and soft. The amount of liquid return is preferably 1 g or less, more preferably 0.5 g or less, and even more preferably 0.25 g or less. The method for measuring the liquid return amount is as follows. In the case of an infant paper diaper (M size), 160 g of colored physiological saline is injected into the central portion in the width direction at a position 150 mm from the abdominal edge 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. If the size of the diaper is different, change the injection amount of physiological saline and the pressure condition of the filter paper as follows. In the case of baby diapers, pressurization of the filter paper is unified at 3.43 kPa, and the amount of physiological saline injected is changed according to the size of the diaper (new baby, S size is 120 g, other sizes are 160 g). On the other hand, in the case of absorbent articles for adults including sanitary products, the pressure on the filter paper is unified at 5.15 kPa. In the case of a sanitary product, the liquid to be injected is horse blood 10 g instead of physiological saline.

  In addition to the superabsorbent polymer, other particles such as activated carbon, silica, alumina, titanium oxide, various viscosity minerals (zeolite, sepiolite, bentonite, cancrinite, etc.), etc. are contained in the web. Agents and antibacterial agents) 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.

  Joining the long fibers that make up the web for the purpose of improving the web shape retention, improving the web compression recovery, making the web less likely to sway, and improving the web transportability. It is preferable to do. For joining long fibers, for example, a water-soluble adhesive such as polyvinyl acetate or acrylic emulsion can be used.

  When long fibers are made of acetate, an agent capable of dissolving and plasticizing acetate, such as triacetin, is sprayed on the web after spraying the superabsorbent polymer to dissolve and plasticize the acetate, thereby joining the long fibers together. Can do.

  As shown in FIG. 11, another method for joining long fibers includes a method in which a synthetic pulp of a thermoplastic resin is dispersed in a web and then heated to melt the synthetic pulp. The synthetic pulp 7 can be sprayed on the web simultaneously with or before the superabsorbent polymer spraying. When spraying, it is preferable to suck from the surface of the web opposite to the spray surface so that the synthetic pulp and the superabsorbent polymer are sufficiently distributed in the web. When the long fibers are made of a thermoplastic resin, it is preferable to use a synthetic pulp made of a thermoplastic resin having a melting point lower than that of the thermoplastic resin.

  It is also preferable to produce the absorbent body 1 as shown in FIG. 12 by embossing the absorbent body shown in FIG. In the absorbent body 1 shown in FIG. 12, a large number of portions 8 where the web is consolidated by embossing are formed. As a result, there are high and low fiber density portions in the web. Accordingly, there is a difference in capillary force between the high fiber density portion and the low fiber density portion, and the absorbent body 1 has higher liquid drawability than the absorbent body shown in FIG.

  As another method for improving the web shape retention, a sheet material such as paper or non-woven fabric is applied to the side of the web on and / or under the web, or in addition to or in place of this. Alternatively, a method of overlapping or covering a plurality of sheets, joining the web and the sheet material with an adhesive, or heat-sealing can be mentioned. According to this method, a sheet-like absorbent body in which a web is sandwiched and fixed between a pair of sheet materials can be obtained. Such a sheet-like absorber has high rigidity due to the bonding with the sheet material and the rigidity of the sheet material itself, thereby improving the handling property, and can be easily transported by itself. . Moreover, since this sheet-like absorber can be easily cut or cut into a desired shape, an absorber according to the shape of the absorbent article can be easily produced.

  As another method for improving the web shape retention, there is a method in which the long fibers constituting the web and the mesh are integrated by entanglement. In this method, the web is laminated on one or both sides of the mesh body, and then the long fibers constituting the web are formed into the mesh body by hydroentanglement (spun lace) or punching with a needle with a hook at the tip (needle punch). Entanglement. After entanglement, a superabsorbent polymer is sprayed and embedded in the web. As the net-like body, for example, a synthetic resin lattice net or a perforated film in which a large number of holes are formed can be used. When using a grid-like net, the wire diameter is preferably 0.1 to 3 mm, and the distance between the lines is preferably 2 to 30 mm. When using a perforated film, the opening diameter is preferably 4 to 40 mm, and the gap between the holes is preferably 1 to 10 mm.

  The absorptive article of the present invention provided with the absorber of each above-mentioned embodiment may have two or more sets of a pair of solid gathers which counter mutually. For example, as shown in FIG. 13, an elastic strand 21 extending in the longitudinal direction of the absorbent article is arranged in an extended state on the side edge of the leg fluff 20 that extends laterally from the side edge of the absorbent body 1. 22, and further, a first three-dimensional gather 23 and a second three-dimensional gather 24 having a base end portion are disposed between the leg gather 22 and the side edge of the absorber 1. The first three-dimensional gathers 23 are arranged near the leg gathers, and the second three-dimensional gathers 24 are arranged near the absorber.

  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 invention, 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. Moreover, it is preferable that the stretchable region of the leg gathers 22 is only the crotch part of the absorbent article.

  In the absorbent article shown in FIG. 13, two sets of leg gathers and a pair of opposing three-dimensional gathers are used. Instead of this, in the absorbent article of the present invention including the absorbent body of each embodiment, two or more pairs of opposing three-dimensional gathers may be used without using leg gathers. For example, in FIG. 14, two sets of three-dimensional gathers, that is, a first three-dimensional gather 23 and a second three-dimensional gather 24 are used. Also in this case, it is preferable that the shrinkage force of the three-dimensional gather is gradually reduced from the outer side in the width direction toward the inner side for the same reason as described above.

  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]
An absorbent for use in baby disposable diapers was produced. First, a crimped acetate long fiber tow was prepared. The crimp rate of the long fibers was 70%, the number of crimps per 1 cm was 15, the fiber diameter was 2.1 dtex, and the total fiber amount of tow was 25,000 dtex. The tow was opened to a width of 100 mm using an air opening device and then stretched to ½ of the maximum extension length to obtain an opening web. Under this condition, a hot melt adhesive was spray coated on the upper surface of the spread web. The coating amount was 5 g / m ² . Subsequently, the superabsorbent polymer particles were uniformly sprayed in a layered manner with a spraying basis weight of 130 g / m ² on the coated surface of the hot melt adhesive. After spreading, the spread state of the spread web was released. As a result, the spread web contracted and the superabsorbent polymer particles were embedded and held in the spread web.

Thereafter, the same operation as this operation was repeated once more to obtain a laminate composed of two web layers and two polymer layers. A fluff pulp layer having a basis weight of 50 g / m ² was disposed on the obtained laminate, and a fluff pulp layer having a basis weight of 100 g / m ² was disposed below the laminate. Subsequently, the whole was wrapped with a tissue paper having a basis weight of 16 g / m ² to obtain an absorbent body. The basis weight of the entire absorbent body was 488 g / m ² and the thickness was 2.2 mm. The basis weight of each web was 13 g / m ² .

[Example 2]
In Example 1, an absorbent body was obtained in the same manner as in Example 1 except that the web was not bonded with a hot melt pressure-sensitive adhesive. The basis weight of the entire absorbent body was 443 g / m ² and the thickness was 2.7 mm.

Example 3
In Example 2, an absorbent body was obtained in the same manner as in Example 2 except that fluff pulp layers were not provided above and below the laminate, and the basis weight of each web was set to 60 g / m ² . The basis weight of the entire absorbent body was 422 g / m ² and the thickness was 1.9 mm.

Example 4
Similar to Example 1, a layer in which particles of superabsorbent polymer were embedded and held in the opened web was obtained. The basis weight of the web was 25 g / m ² and the basis weight of the superabsorbent polymer was 180 g / m ² . Furthermore, 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 150 g / m ² . The web carrying these superabsorbent polymers and a layer of a mixture in which pulp / superabsorbent polymer was uniformly mixed were laminated (interlayer was bonded with hot melt 5 g / m ² ) to obtain a laminate. Next, the laminate was wrapped with a tissue paper having a basis weight of 16 g / m ² (the upper and lower surfaces of the laminate and the tissue paper were bonded with a hot melt of 5 g / m ² ) to obtain an absorbent body. The basis weight of the entire absorber was 402 g / m ² and the thickness was 2.0 mm.

Example 5
First, an acetate long fiber tow having crimps was prepared. The crimp rate of the long fibers was 70%, the number of crimps per 1 cm was 15, the fiber diameter was 2.1 dtex, and the total fiber amount of tow was 25,000 dtex. The tow was conveyed under extension 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. 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 and 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 . The basis weight of the entire absorber was 488 g / m ² and the thickness was 2.1 mm.

[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.

[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.

[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.

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

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

[Structural stability]
(1) At the time of drying The center part of the absorber produced to 100x200 mm was cut | disconnected, and the absorber of 100x100 mm was obtained. The amount of polymer dropped from the cut surface was measured when the vibration was applied 20 times at a speed of 1 cm / second with an amplitude of 5 cm 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.
○: 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 1, it can be seen that the absorbent body of each example has a stable structure of the absorbent body although the use ratio of the fiber material is smaller than that of the absorbent body of the comparative example. . It can also be seen that it has a high absorption capacity despite being thin, low basis weight and flexible.

Drawing 1 is a mimetic diagram showing one embodiment of an absorber in an absorptive article of the present invention. Fig.2 (a) and (b) are the schematic diagrams which show another embodiment of the absorber in the absorbent article of this invention. FIG. 3 is a schematic view showing another embodiment of the absorbent body in the absorbent article of the present invention. FIG. 4 is a schematic view showing another embodiment of the absorbent body in the absorbent article of the present invention. FIG. 5 is a schematic view showing a preferred apparatus for producing an absorbent body in the absorbent article of the present invention. Fig.6 (a)-(c) is a schematic diagram which shows another embodiment of the absorber in the absorbent article of this invention. Fig.7 (a)-(d) is a schematic diagram which shows another embodiment of the absorber in the absorbent article of this invention. Fig.8 (a) and (b) are the schematic diagrams which show another embodiment of the absorber in the absorbent article of this invention. FIG. 9 is a schematic view showing another embodiment of the absorbent body in the absorbent article of the present invention. FIG. 10 is a schematic view showing another embodiment of the absorbent body in the absorbent article of the present invention. FIG. 11 is a schematic view showing another embodiment of the absorbent body in the absorbent article of the present invention. FIG. 12 is a schematic view showing another embodiment of the absorbent body in the absorbent article of the present invention. FIG. 13 is a schematic diagram showing the structure of the cross section in the width direction in one embodiment of the absorbent article of the present invention. FIG. 14 is a schematic view (corresponding to FIG. 13) showing the structure of the cross section in the width direction in another embodiment of the absorbent article of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Absorbent body 2 Web 3 Polymer layer 4 Fluff pulp fiber layer 5 Laminate 6 Long fiber web not containing superabsorbent polymer

Claims (15)

  An absorbent article comprising an absorbent body comprising a hydrophilic long fiber web, the long fibers having a crimp rate of 20 to 90% and oriented in the planar direction of the absorbent body, An absorbent article in which a superabsorbent polymer is embedded and supported in a web.   The absorbent article according to claim 1, wherein the superabsorbent polymer is embedded and supported uniformly in the web.   The absorbent article according to claim 1, wherein the superabsorbent polymer is embedded and supported on the skin-facing surface side of the web in a biased manner.   The absorbent article according to claim 1, wherein the superabsorbent polymer is biased and embedded in the web on the non-skin facing side of the web.   The absorbent article according to any one of claims 1 to 4, wherein a basis weight of the superabsorbent polymer is not less than a basis weight of the long fiber web.   The absorbent body includes a plurality of the webs and a layer of a superabsorbent polymer dispersed between the webs, and a part of the superabsorbent polymer is embedded and supported in the web. The absorbent article according to any one of 5 above.   The absorbent article according to claim 6, wherein the overlapping webs are bonded in a dotted pattern.   The absorbent article according to claim 6 or 7, wherein a part of the long fibers in at least one layer of the plurality of webs is stretched.   The absorbent article according to any one of claims 1 to 8, further comprising a long-fiber web having hydrophilicity that does not have crimps.   The absorbent article according to any one of claims 1 to 5, wherein the absorbent body has a structure in which the web is stacked on a fluff pulp stacking layer.   The absorbent article according to claim 10, wherein the absorbent body has a structure in which a plurality of laminated bodies formed by stacking the web on a fluff pulp piled-up layer.   The absorbent article according to claim 10 or 11, wherein the fluff pulp pile layer further comprises a superabsorbent polymer. The long fibers are oriented in the longitudinal direction of the absorbent article, and the absorbent body does not have a linear adhesive line that crosses the orientation direction of the long fibers, or the long fibers are absorbent. The absorbent article according to any one of claims 1 to 12, wherein the absorbent article is oriented in the width direction of the article, and the absorbent body has a linear adhesive line that crosses the orientation direction of the long fibers.   A plurality of webs of hydrophilic long fibers having a crimp rate of 20 to 90%, and a layer of superabsorbent polymer dispersed between the webs, wherein a part of the superabsorbent polymer is An absorbent body embedded and supported in a web, and wherein the webs are bonded in the form of dots. A method for producing an absorbent body comprising a superabsorbent polymer in a web comprising crimped long fibers,
A step of opening the web in a state in which the web is stretched and stretched in the longitudinal direction; and a step of supplying the superabsorbent polymer to the web in a state in which the tension of the opened web is relaxed. The manufacturing method of the absorber containing.

Images