RU2600437C2 - Absorbent element and absorbent article obtained using said absorbent element - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: first layer has weight ratio of polymer and hydrophilic fibres (weight of polymer/weight of hydrophilic fibres) of 1 or more, and second layer has a high content of absorbent polymer and higher content of hydrophilic fibres in comparison with first layer. Third layer has lower content of absorbent polymer and lower content of hydrophilic fibres in comparison with second layer. In third layer weight ratio of absorbent polymer and hydrophilic fibres (weight of absorbent polymer/weight of hydrophilic fibres) is 0.5 or less. First layer, second layer and third layer are continuous in thickness direction. Absorbent element has a recessed portion extending through thickness of second layer and third layer in a state five minutes after adding aqueous sodium chloride solution with concentration 0.9 weight percentage in amount of 2,000 g/m². Also disclosed is an absorbent article comprising a top sheet located on side facing skin, back sheet arranged on side not facing skin, and an absorbent element described above, located between top sheet and back sheet.

EFFECT: disclosed is an absorbent element including absorbent polymer and hydrophilic fibres and having a first layer, a second layer and a third layer.

19 cl, 1 tbl, 11 dwg

Description

The present invention relates to an absorbent element and an absorbent article in which this absorbent element is used.

Known absorbent element having a concave-convex design, and an absorbent product that includes such an absorbing element. For example, in the following Patent Source 1, a disposable diaper is disclosed, including an inner sheet, an outer sheet, and an absorbent member. The absorbent element has a first part located on the side of the inner sheet and having a high content of absorbing polymer, a second part located on the side of the outer sheet and having a lower content of absorbing polymer compared to the first part, and spaces extending through the second part to the first part. The disposable diaper of Patent Source 1 is configured to prevent blocking due to gel formation.

In Patent Source 2, a single-use diaper is disclosed, comprising an absorbent core having a particle layer containing mainly polymer particles with ultra-high absorption capacity and a fiber layer containing mainly ground pulp and located on the particle layer. The absorbent core is divided, and the particle layer is open to impact on the divided surface. According to Patent Literature 2, even when the particle layer is blocked due to gel formation, a fiber layer located under the particle layer can be used.

LIST OF LINKS

PATENT LITERATURE

Patent Source 1: JP 2009-119154A

Patent Source 2: JP 11-216161A

None of Patent Sources 1 and 2 mentioned the effective solution to the problem of blocking due to gel formation from the absorbent polymer. Since in the disposable diaper according to Patent Source 1, in particular, the second part, having spaces extending through it, has a low content of absorbing polymer and a high content of hydrophilic fibers, the second part loses its thickness upon absorption of the fluid released by the body, which leads to narrowing data spaces. As a result, even though blocking due to gel formation is prevented, there is not expected to be sufficient spreading of the fluid released by the body, so that the degree of re-wetting in the fluid inlet area is increased and the feeling of dryness is weakened. In a disposable diaper according to Patent Source 2, a layer of fibers formed mainly from crushed cellulose and located under a layer of particles also loses its thickness upon absorption of the fluid released by the body. As a result, sufficient spreading of the fluid released by the body is not expected, and dryness is reduced.

The present invention relates to the development of an absorbent element that meets the above requirements.

The invention relates to an absorbent element comprising an absorbent polymer and a hydrophilic fiber and having a first layer and a second layer. The first layer has a weight ratio of polymer to hydrophilic fibers (weight of the absorbing polymer / weight of hydrophilic fibers) of 1 or more, and the second layer has a higher content of absorbing polymer and a higher content of hydrophilic fibers compared to the first layer. The first and second layers are continuous in the thickness direction. The absorbing element has a recessed portion passing through the thickness of the second layer in a state 5 minutes after adding an aqueous solution of sodium chloride with a concentration of 0.9 weight percent in an amount of 2000 g / m ² .

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a disposable diaper when viewed from the side of the top sheet, with a partial tear, showing an example of an absorbent article of the invention in which a first embodiment of an absorbent element of the invention is used.

FIG. 2 is a section taken along line I-I in FIG. one.

FIG. 3 is a plan view of an absorbent member in the disposable diaper of FIG. 1 after absorption of physiological saline, when viewed from the back of the sheet.

FIG. 4 is a section taken along line II-II of FIG. 3.

FIG. 5 is a plan view of an absorbent member in the disposable diaper of FIG. 1 before absorption of physiological saline, when viewed from the back of the sheet.

FIG. 6 is a section taken along line III-III of FIG. 5.

FIG. 7 is a schematic illustration of a device for manufacturing a first embodiment of an absorbent element according to the invention.

FIG. 8 is a schematic cross-section of a portion (a recessed portion) of the peripheral surface of a rotating drum shown in FIG. 7.

FIG. 9 is a schematic sectional view illustrating an absorbent material housed in a recessed portion of the rotary drum shown in FIG. 7.

FIG. 10 is a plan view of a second embodiment of an absorbent element according to the invention before absorption of physiological saline when viewed from the side of the top sheet.

FIG. 11 is a section taken along line IV-IV in FIG. 10.

The invention will be described based on preferred embodiments with reference to FIG. 1-6. FIG. 1 shows an absorbent element 4A as a first embodiment of an absorbent element according to the invention used in a disposable diaper 1 as one embodiment of an absorbent article according to the invention. FIG. 1 is a plan view of a disposable diaper 1 as viewed from the side of the top sheet, with a partial tear. FIG. 2 shows a section taken along line I-I in FIG. 1. FIG. 3 is a plan view of an absorbent member 4A used in the disposable diaper of FIG. 1, after absorption of physiological saline. FIG. 4 is a section taken along line II-II of FIG. 3. FIG. 5 is a plan view of an absorbent member 4A used in the disposable diaper of FIG. 1, before absorption of physiological saline. FIG. 6 is a section taken along line III-III of FIG. 5.

As shown in FIG. 1, the disposable diaper 1 of this embodiment (hereinafter referred to simply as the diaper 1) includes a top sheet 2 located on the side facing the skin, a back sheet 3 located on the side not facing the skin, and an elongated absorbent element 4A according to the first embodiment (hereinafter referred to simply as the absorption element 4A) located between the sheets 2 and 3. As shown, the diaper 1 is bilaterally symmetrical with respect to the longitudinal center line CL.

As shown in FIG. 1, the diaper 1 has a front part A and a rear part B along a longitudinal direction (a direction parallel to the center line CL, also called a direction Y or a longitudinal direction Y), and a crotch part intermediate between parts A and B. The front part A is a part placed on the side of the abdomen of the wearer when worn, the back part B is the part placed on the back side of the wearer when worn, and the crotch part C is the part placed around the wearer's crotch when worn. The crotch portion C is located in the middle in the longitudinal direction (in the middle in the Y direction). The direction perpendicular to the longitudinal direction Y is the transverse / lateral direction (also called the X direction or the transverse X direction) of the diaper 1.

As used herein, the term “skin side” refers to the side of the diaper 1 forming member, such as the top sheet 2, which faces the wearer's skin while worn. The term “non-skin side” refers to the side of the diaper forming member 1, such as the top sheet 2, which faces away from the skin of the wearer while wearing.

As shown in FIG. 1, the front portion A and the rear portion B of the diaper 1 have lateral edges located transversely behind the lateral edges of the crotch portion C. Each lateral edge of the crotch portion C is concave inward laterally. Thus, the diaper 1 has a narrowed portion, an average in the longitudinal direction. Both the top sheet 2 and the back sheet 3 extend outward from both sides and both longitudinally defined ends of the absorbent element 4A. As shown in FIG. 2, the top sheet 2 has a smaller width in the transverse direction X as compared with the back sheet 3. The top sheet 2 and the back sheet 3 are bonded to each other in their zones located outside the periphery of the absorbing element 4A, either directly or indirectly (with any another element located between them), thereby ensuring a strong retention of the absorbing element 4A between them.

As shown in FIG. 1, the diaper 1 is a diaper of the so-called disclosed type and has two fastening tapes 7 on opposite side edges of the rear part B and a receiving tape 8 on the outer side (not facing the skin side) of the front part A, on which the fastening tapes 7 must be fixed . As shown in FIG. 1, the diaper 1 has a sheet 62 forming a standing cuff and attached to each side of the top sheet 2 along the longitudinal direction Y. Each sheet 62 forming a standing cuff has an elastic member 61 attached to it in a state in which it is stretched in the direction Y to thereby form two standing cuffs 6 (see Fig. 2). As shown in FIG. 1, the diaper 1 has a plurality of leg elastic members 63 designed to form leg cuffs and placed in a state in which they are stretched in the Y direction, laterally opposite sides extending in the Y direction. When tightening, the elastic members 63 for the legs form cuffs for the legs. The diaper 1 also has waist elastic elements 64, designed to form an elastic waist and placed in a state in which they are stretched in the X direction, in each of its end parts opposite in the longitudinal direction. When tightened, the waist elastic members 64 form an elastic waistband.

As shown in FIG. 4, the absorbent element according to the invention comprises an absorbent polymer 41 and hydrophilic fibers 42. As shown, the absorbent element according to the invention has a first layer 4F and a second layer 4S. The absorbent element 4A of the first embodiment further has a third layer 4T. As shown, in the absorbent member 4A, the second layer 4S is located on the non-skin side of the first layer 4F, and the third layer 4T is located on the non-skin side of the second layer 4S. The first layer 4F, the second layer 4S and the third layer 4T are continuous in the thickness direction (also called hereinafter the direction T or the direction T of the thickness). In other words, the first layer 4F, the second layer 4S, and the third layer 4T are integrally formed. As used herein, the expression “formed as a unit” should mean that the first layer 4F, the second layer 4S and the third layer 4T are formed without the possibility of separation, and no bonding means such as adhesive bonding or bonding are used fusion. With the first layer 4F, the second layer 4S and the third layer 4T, formed integrally with each other, the absorbent element 4A provides continuity, which makes it possible to smoothly move the body fluids. A method for forming such a structure of the absorbent element 4A will be described later.

The first layer 4F of the absorbent element according to the invention has in its dry state the weight ratio of the absorbing polymer 41 and the hydrophilic fibers 42 — the weight of the absorbing polymer / weight of the hydrophilic fibers is 1 or more, preferably 1.2 or more, more preferably 1.5 or more, preferably 5 or less, more preferably 3 or less, even more preferably 1.8 or less, and in particular, preferably from 1 to 5, more preferably from 1.2 to 3, even more preferably from 1.5 to 1.8 . As used herein, the term “dry state” refers to the state of the absorbing element before an aqueous solution of sodium chloride with a concentration of 0.9 weight percent is added to it (hereinafter also referred to as the state before absorption), or the state after as an aqueous solution of sodium chloride with a concentration of 0.9 weight percent was added thereto, followed by removal of the water contained therein. The mass (bulk, mass 1 m ² ) of the absorbent polymer 41 in the first layer 4F is preferably 50 g / m ² or more, more preferably 80 g / m ² or more, and preferably 500 g / m ² or less, more preferably 300 g / m ² or less, even more preferably 110 g / m ² or less. In particular, the mass (bulk) of the absorbent polymer is preferably from 50 to 500 g / m ² , more preferably from 80 to 300 g / m ² , even more preferably from 80 to 110 g / m ² . The mass (bulk) of hydrophilic fibers 42 in the first 4F layer is preferably 20 g / m ² or more, more preferably 40 g / m ² or more, even more preferably 50 g / m ² or more and preferably 300 g / m ² or less, more preferably 200 g / m ² or less, even more preferably 80 g / m ² or less. In particular, the mass (bulk) of the hydrophilic fibers 42 in the first layer 4F is preferably from 20 to 300 g / m ² , more preferably from 40 to 200 g / m ² , even more preferably from 50 to 80 g / m ² .

The second layer 4S of the absorbent element according to the invention has in its dry state a higher content of the absorbing polymer and a higher content of hydrophilic fibers compared to the first layer 4F and in the absorbing element 4A has a weight ratio of the absorbing polymer 41 and the hydrophilic fibers 42 (weight of the absorbing polymer / weight hydrophilic fibers) of 1 or more. The second layer 4S of the absorbing element 4A preferably has a weight ratio of the absorbing polymer 41 and the hydrophilic fibers 42 — the weight of the absorbing polymer / weight of the hydrophilic fibers is 1 or more, more preferably 1.2 or more, more preferably 1.5 or more and 5 or less , more preferably 3 or less, even more preferably 2 or less, and in particular, preferably from 1 to 5, more preferably from 1 to 3, even more preferably from 1.2 to 2. The mass (bulk) of the absorbent polymer 41 in second layer 4S pre titelno is 60 g / m ² or more, more preferably 100 g / m ² or more, still more preferably 170 g / m ² or more, and preferably 700 g / m ² or less, more preferably 400 g / m ² or less, even more preferably 200 g / m ² , in particular preferably from 60 to 700 g / m ² , more preferably from 100 to 400 g / m ² , even more preferably from 170 to 200 g / m ² . The mass (bulk) of the hydrophilic fibers 42 in the second layer 4S is preferably 30 g / m ² or more, more preferably 60 g / m ² or more, even more preferably 90 g / m ² or more and preferably 400 g / m ² or less, more preferably 300 g / m ² or less, even more preferably 150 g / m ² or less. In particular, the mass (bulk) of the hydrophilic fibers in the second 4S layer is preferably from 30 to 400 g / m ² , more preferably from 60 to 300 g / m ² , even more preferably from 90 to 150 g / m ² .

The third layer 4T of the absorbent element 4A has in its dry state a lower content of the absorbing polymer and a lower content of hydrophilic fibers compared to the second layer 4S and has a weight ratio of the absorbing polymer 41 and hydrophilic fibers 42 (weight of the absorbing polymer / weight of hydrophilic fibers) 0.5 or less. The weight ratio of the absorbing polymer to the hydrophilic fibers of the third 4T layer is preferably 0.05 or more, more preferably 0.1 or more, even more preferably 0.15 or more and preferably 0.5 or less, more preferably 0.4 or less, even more preferably 0.2 or less, and in particular, preferably from 0.05 to 0.5, more preferably from 0.1 to 0.4, even more preferably from 0.15 to 0.2. The weight (basic weight) of the absorbent polymer 41 in the third layer 4T is 0 g / m ² or more, preferably 5 g / m ² or more, more preferably 10 g / m ² or more and preferably 50 g / m ² or less, preferably 40 g / m ² or less, more preferably 15 g / m ² , in particular preferably 0 to 50 g / m ² , more preferably 5 to 40 g / m ² , even more preferably 10 to 15 g / m ² . The mass (bulk) of hydrophilic fibers 42 in the third 4T layer is 0 g / m ² or more, preferably 10 g / m ² or more, more preferably 50 g / m ² or more, and preferably 150 g / m ² or less, more preferably 100 g / m ² or less, even more preferably 70 g / m ² or less. In particular, the mass (bulk) of the hydrophilic fibers in the third 4T layer is preferably from 0 to 150 g / m ² , more preferably from 10 to 100 g / m ² , even more preferably from 50 to 70 g / m ² .

The method for determining the bulk of the first layer 4F, the second layer 4S and the third layer 4T:

The mass values of the first layer 4F, the second layer 4S and the third layer 4T are determined as follows.

Ten pieces with a size of 1 cm ² are cut from randomly selected parts of the absorbent element 4A in a state before absorption (before adding an aqueous solution of sodium chloride with a concentration of 0.9 weight percent) by means of a razor blade with one cutting edge supplied by Feather Safety Razor Co., Ltd. Each cut piece is then cut into thin layers along a border that is open to impact on the cut surface, which is formed by any of the methods described below, to separate the first layer from the cut piece. The absorbing polymer is removed from the thin layer, and the hydrophilic fibers and the absorbing polymer are separated from each other, each of these materials is weighed by using an electronic scale GR-300 from A & D Co., Ltd. (precision: up to the fourth digit after the decimal point). After being cut by a razor blade with one cutting edge, each cut piece is divided into absorbing polymer and hydrophilic fibers by using a sieve with 2 mm openings. The mass of the absorbing polymer and the mass of hydrophilic fibers are divided by the area of the cut piece to obtain the corresponding values of the main mass in the first 4F layer. The bulk values of the absorbing polymer and hydrophilic fibers in the second 4F layer and the third 4T layer are obtained in the same way.

The boundary between the first layer 4F and the second layer 4S is located at a place where both the content of the absorbing polymer and the content of hydrophilic fibers are increased in the manufacture of the absorbing element. In the case where there is a third layer 4T, as in the absorbent element 4A, the boundary between the second layer 4S and the third layer 4T is in a place where the weight ratio of the absorbing polymer and hydrophilic fibers is reduced to 0.5 or less in the manufacture of the absorbing element.

The boundaries between adjacent layers in the finished absorbent element can be clearly defined as follows. The thickness of the absorbent element and the depth of the recessed portion are measured as shown in FIG. 6 and the thickness / depth ratios are divided into three cases AC.

Case A, when the depth of the recessed section is from 30% to 80% of the thickness of the absorbing element (thickness of the protruding section).

Referring to FIG. 6. In the cross section of the absorbent element, a straight line connecting the bottoms (the deepest points of the lower parts) of the adjacent recessed sections 44 is considered as the boundary between the first layer 4F and the second layer 4S for convenience. In the case where the absorbent element has a third layer 4T, like the absorbent element 4A, the thickness of the absorbent element 4A is divided into equal quarters by dividing lines in the cross section of the absorbent element. One of the dividing lines, which is farthest from the first layer 4F, is considered as the boundary between the second layer 4S and the third layer 4T for convenience.

Case B, when the depth of the recessed portion is more than 80% of the thickness of the absorbing element (thickness of the protruding portion).

Referring to FIG. 6. In the cross section of the absorbent element, the thickness of the absorbent element is divided into equal quarters by dividing lines. One of the dividing lines, which is farthest from the side of the absorbing element, on which the recess of the recessed portion is open, is considered as the boundary between the first layer 4F and the second layer 4S for convenience. In the case where the absorbent element has a third layer 4T, the thickness of the absorbent element is divided into equal quarters by dividing lines in the cross section of the absorbent element. One of the dividing lines, which is closest to the side of the absorbent element, on which the recess of the recessed portion is open, is considered as the boundary between the second layer 4S and the third layer 4T for convenience.

Case C, when the depth of the recessed section is less than 30% of the thickness of the absorbing element (thickness of the protruding section).

Referring to FIG. 6. In the cross section of the absorbent element, the thickness of the absorbent element is divided into equal quarters by dividing lines. One of the dividing lines, which is closest to the side of the absorbent element, on which the recess of the recessed portion is open, is considered as the boundary between the first layer 4F and the second layer 4S for convenience. In the case where the absorbent element has a third layer 4T, the thickness of the absorbent element is divided into equal tenths by dividing lines in the cross section of the absorbent element. One of the dividing lines, which is closest to the side of the absorbent element, on which the recess of the recessed portion is open, is considered as the boundary between the second layer 4S and the third layer 4T for convenience.

In the case where the boundaries cannot be clearly determined using the above methods, or in the case of the finished product, an aqueous solution of sodium chloride with a concentration of 0.9 weight percent is supplied. The cut piece is then cut into first, second, and third layers by means of a razor blade with one cutting edge, supplied by Feather Safety Razor Co., Ltd., along the boundaries open to the surface of the cut, which are determined by any of the methods described hereinafter. Each of the layers thus separated is dried to remove the water contained therein and subjected to a process of measuring the average weights of the absorbing polymer and hydrophilic fibers. The amount of remaining sodium chloride after drying is so small that it can be neglected.

In the case where the dried thin layer is very difficult to separate into an absorbing polymer and hydrophilic fibers, the thin layer immediately after cutting into thin layers and before drying can be divided into an absorbing polymer and hydrophilic fibers by sorting in ion exchange water using, for example, steam tweezers or a laboratory spatula, followed by drying and measurement to obtain their average masses.

The boundaries between adjacent layers can be clearly defined as follows. An aqueous solution of sodium chloride with a concentration of 0.9 weight percent (physiological saline solution) is added to the absorbing element in an amount of 2000 g / m ² . After 5 minutes from the moment of addition, the absorbing element in the state after absorption shown in FIG. 4, inspected from the side of its cut surface. The thickness of the absorbing element and the depth of the recessed portion are measured, and the thickness / depth ratios are divided into three cases AC.

Case A, when the depth of the recessed section is from 30% to 80% of the thickness of the absorbing element (thickness of the protruding section).

Referring to FIG. 4. In the cross section of the absorbing element after adding physiological saline, a straight line connecting the bottoms (the deepest points of the lower parts) of the adjacent recessed sections 44 (described hereinafter) is considered as the boundary between the first layer 4F and the second layer 4S for convenience. In the case where the absorbent element has a third layer 4T, like the absorbent element 4A, the thickness of the absorbent element 4A is divided into equal quarters by dividing lines in the cross section of the absorbent element (see Fig. 4). One of the dividing lines, which is farthest from the first layer 4F, is considered as the boundary between the second layer 4S and the third layer 4T for convenience.

Case B, when the depth of the recessed portion is more than 80% of the thickness of the absorbing element (thickness of the protruding portion).

In cross section (see Fig. 4) of the absorbing element after adding physiological saline, the thickness of the absorbing element is divided into equal quarters by dividing lines. One of the dividing lines, which is farthest from the side of the absorbing element, on which the recess of the recessed portion is open, is considered as the boundary between the first layer 4F and the second layer 4S for convenience. In the case where the absorbent element has a third layer 4T, the thickness of the absorbent element is divided into equal quarters by means of dividing lines in section (see Fig. 4) of the absorbent element. One of the dividing lines, which is closest to the side of the absorbent element, on which the recess of the recessed portion is open, is considered as the boundary between the second layer 4S and the third layer 4T for convenience.

Case C, when the depth of the recessed section is less than 30% of the thickness of the absorbing element (thickness of the protruding section).

In cross section (see Fig. 4) of the absorbing element after adding physiological saline, the thickness of the absorbing element is divided into equal quarters by dividing lines. One of the dividing lines, which is closest to the side of the absorbent element, on which the recess of the recessed portion is open, is considered as the boundary between the first layer 4F and the second layer 4S for convenience. In the case where the absorbent element has a third 4T layer, the thickness of the absorbent element is divided into equal tenths by dividing lines. One of the dividing lines, which is closest to the side of the absorbent element, on which the recess of the recessed portion is open, is considered as the boundary between the second layer 4S and the third layer 4T for convenience.

As shown in FIG. 4, the absorbent element according to the invention has recessed portions 44 passing through the thickness of the second 4S layer (in the T direction) 5 minutes after the addition of an aqueous solution of sodium chloride with a concentration of 0.9 weight percent in an amount of 2000 g / m ² (in the state after absorption). The absorbent element 4A has recessed portions 44 extending through the thickness of the second layer 4S (in the T direction) even before the addition of an aqueous solution of sodium chloride (physiological saline), as shown in FIG. 6. Since the absorbent element 4A has a third layer 4T, as indicated above, the recessed portions 44 extend not only through the thickness of the second layer 4S, but also through the thickness of the third layer 4T (in the T direction), as shown in FIG. 6. As used herein, the term “recessed region” means a groove formed on the skin side or the skin side of the absorbent element and covers a through hole through the entire thickness of the absorbent element.

As shown in FIG. 3 and 5, the absorbent member 4A consists of a block portion 401 having a plurality of recessed portions 44 and protruding portions 43 delimited by a plurality of recessed portions 44 and a peripheral portion 402 located around the periphery of the block portion 401. As shown in FIG. 2, the protruding portions 43, which form the assembled block 401 of the absorbent element 4A in the diaper 1, protrude from the side of the top sheet 2 toward the side of the back sheet 2. The peripheral portion 402 also projects from the side of the top sheet 2 towards the back side sheet 3. As shown in FIG. 2, each of the recessed portions 44 (44Y) that form the block portion 401 of the absorbent element 4A when assembled in the diaper 1 has a recess extending from the side of the back sheet 3 toward the side of the upper sheet 2. Accordingly, the absorbent element 4A has a three-dimensional a profile on its side not facing the skin, and a flat surface on its side facing the skin. It should be noted that the recessed portions 44 of the absorbent element 4A are not formed as a result of the embossing process. Therefore, the bulk and density of the absorbent material (including aqueous polymer 41 and hydrophilic fibers 42) of the recessed portions 44 are equal to the bulk and density of the absorbent material of the protruding portions 43 or less than the bulk and density of the absorbent material of the protruding portions 43. In that case when the bulk and density of the absorbing material of the recessed sections 44 are equal to the bulk and the density of the absorbing material of the protruding sections 43 or less than the bulk and the density of nonperturbing material protruding portions 43, it is possible to smooth moving body fluid. A method for forming such a structure of the absorbent element 4A will be described later. A specific description with respect to the bulk, density and the like for the protruding portions 43 and the recessed portions 44 will be given later.

As shown in FIG. 3 and 4, the recessed portions 44 of the absorbent member 4A include a plurality of continuous rectilinear recessed portions 44X extending in the transverse direction X, and a plurality of continuous rectilinear recessed portions 44Y extending in the longitudinal direction Y. As shown in FIG. 1 and 3, the block portion 401 has a generally mesh configuration formed by rectilinear recessed portions 44X extending in the transverse direction X and rectilinear recessed portions 44Y extending in the longitudinal direction Y, and each portion delimited by the rectilinear recessed portions 44X and 44Y (corresponding mesh), is a protruding portion 43. The block portion 401 of the absorbent element 4A is rectangular and has a greater length in the longitudinal direction Y, and the peripheral portion 402 is surrounded the entire periphery of the block portion 401 having a predetermined width.

For use in disposable diapers, the absorbent element 4A preferably has a total length in the Y direction of 150 to 600 mm and a total width in the X direction of 20 to 200 mm in the pre-absorption state.

The block portion 401 preferably has a length in the longitudinal direction Y of between 80% and 100% of the total length of the absorbent element 4A in the pre-absorption state.

The block portion 401 preferably has a width in the transverse direction X comprising from 60% to 100% of the total width of the absorbent element 4A in the pre-absorption state.

For use in disposable diapers, the block portion 401 preferably has a total length in the longitudinal direction Y of 150 to 600 mm and a total width in the transverse direction X of 20 to 200 mm in the pre-absorption state.

For use in disposable diapers, each of the portions of the peripheral portion 402, longitudinally terminated, in the pre-absorption state, preferably has a size in the Y direction of 5 to 50 mm, which is equal to the size of each of the side portions of the peripheral portion 402 defined in the direction X, in a condition before absorption.

The dimensions, bulk values and the like of the protruding portions 43 and the recessed portions 44 (44X and 44Y) are described in more detail below.

For use in an absorbent article, for example, such as a disposable diaper, the straight, deep portions 44 extending in the transverse direction X preferably have a width L1 (see FIG. 1) of 0.5 to 20 mm in the pre-absorption state, for reasons associated with the formation of free spaces and maintaining the effect of sufficient spreading of the fluid and the rapid absorption of the fluid.

For use in an absorbent article, such as for example a disposable diaper, the rectilinear recessed portions 44Y extending in the longitudinal direction Y preferably have a width L2 (see FIG. 1) of 0.5 to 20 mm in the pre-absorption state, for reasons related to providing sufficient free spaces and maintaining the effect of sufficient fluid spreading and rapid absorption of the fluid.

The widths L1 and L2 are values measured in the lower part of the recessed portions of the concave-convex structure of the absorbent element 4A.

As shown in FIG. 1 and 3, the protruding portions 43 in the diaper 1 are rectangular and have a longer length in the longitudinal direction Y in a plan view. Despite the fact that in the diaper 1, the protruding sections 43 have a rectangular shape in a plan view, the rectangle can be rounded at four corners, or the shape in a plan view can be a polygon, an oval, a combination of them, or the protruding sections 43 can be attached another form.

For use in an absorbent article, for example, such as a disposable diaper, the protruding portions 43 in the diaper 1 preferably have a size L3 (see FIG. 1) in the longitudinal direction Y of 15 to 300 mm and a size L4 (see FIG. .1) in the transverse direction X, comprising from 5 to 50 mm in the pre-absorption state, for reasons related to the sufficient absorption of the fluid released by the body and the reduction of re-wetting in the fluid inlet zone.

For use in an absorbent article, such as for example a disposable diaper, the bulk of the absorbent material (including the bulk of the hydrophilic fibers and the bulk of the absorbent polymer) of the recessed portions 44 (44X and 44Y) is preferably 0% to 80% of the bulk of the absorbent the material of the protruding portions 43 in a dry state for reasons related to providing spaces and maintaining the effect of sufficient spreading of the fluid and rapid absorption of the fluid.

In particular, the bulk of the recessed portions 44 (44X and 44Y) is preferably 0 to 400 g / m ² in the dry state, and the bulk of the protruding portions 43 is preferably 200 to 600 g / m ² in the dry state.

The values of the bulk of the protruding sections 43 and the recessed sections 44 are determined as follows.

The method of determining the values of the bulk of the protruding sections 43 and indented sections 44:

The bulk of the protruding sections 43 and the bulk of the recessed sections 44 are determined as follows.

The absorbent member 4 is cut along the boundaries between the protruding portions 43 and the recessed portions 44 with a single cutting edge razor blade from Feather Safety Razor Co., Ltd. to obtain ten protruding portions 43. Each of the ten protruding portions 43 was weighed by using an electronic scale GR-300 from A&D Co., Ltd., (accuracy: up to the fourth decimal place) to obtain the average mass of the protruding section, which was divided by the average area of the protruding section to calculate the bulk of the protruding sections 43.

The absorber 4 was cut along the borders extending in the longitudinal direction Y between the protruding portions 32 and the recessed portions 44Y at a length of 100 mm at a predetermined width of the recess 44 (44Y) by using a razor blade with one cutting edge from Feather Safety Razor Co ., Ltd. to obtain five stripe-shaped recessed sections 44 (44Y). Each of the cut five recessed sections 44 (44Y) is weighed by using an electronic scale GR-300 from A&D Co., Ltd. (accuracy: up to the fourth digit after the decimal point) to obtain the average mass of the recessed section, which was divided by the average area of the recessed section to obtain the bulk of the recessed sections 41 (44Y). The bulk of the recessed sections 44 (44X) is obtained in the same manner as the bulk of the recessed sections 44 (44Y).

For use in disposable diapers, it is preferable that the absorbent element 4A, in the state before absorption, has a thickness of 0.5 mm or more, preferably 1 mm or more, more preferably 5 mm or more and 20 mm or less, preferably 10 mm or less more preferably 5.5 mm or less, in particular from 0.5 to 20 mm, more preferably from 1 to 10 mm, even more preferably from 5 to 5.5 mm, for reasons related to absorbency and abutment the body of the carrier (matching the shape of the bodies carrier).

Preferably, the recessed portions 44 (44X and 44Y) in the pre-absorption state have a depth of 20% or more, preferably 25% or more, more preferably 70% or more and 100% or less, preferably 80% or less, more preferably 75% or less, more specifically from 20% to 100%, more preferably from 25% to 80%, even more preferably from 70% to 75% of the thickness of the absorbent element 4A, that is, the thickness of the protruding sections 43, for reasons related to providing spaces and maintaining the effect of sufficient spreading yaemoy body fluid.

More precisely, it is preferable that the recessed portions 44 (44X and 44Y) in the pre-absorption state have a depth of 0.1 mm or more, preferably 0.2 mm or more, more preferably 3 mm or more and 20 mm or less, preferably 10 mm or less, more preferably 4 mm or less, in particular from 0.1 to 20 mm, more preferably from 0.2 to 10 mm and even more preferably from 3 to 4 mm. The depth of the recessed sections 44 (44X and 44Y) is equal to the difference obtained by subtracting the thickness of the recessed sections 44 (44X and 44Y) from the thickness of the absorbent element 4A (i.e., the thickness of the protruding sections 43).

When measuring the thickness of the protruding portions 43 and the recessed portions 44 (44X and 44Y), the absorbent element 4A in the state before being absorbed is cut with a razor along both the longitudinal direction Y and the transverse direction X, and measurements are performed on the cut surface in the absence of load applied to patterned. The thickness of the protruding section 43 represents the maximum thickness of the protruding section 43, and the thickness of the recessed section 44 (44X or 44Y) represents the minimum thickness of the recessed section 44. In the case where the thickness cannot be measured with the naked eye, the incision surface of the sample can be examined under a VHX microscope -1000 from Keyence with 10-50x magnification.

For use in a disposable diaper for reasons related to adhering to the body of the carrier (matching the shape of the body of the carrier) after absorption of the body fluid, the absorption element 4A preferably has a thickness of 1 mm or more, more preferably 8 mm or more, even more preferably 9 mm or more and 30 mm or less, preferably 11 mm or less, more preferably 9.5 mm or less, more precisely 1 to 30 mm, preferably 8 to 11 mm, more preferably 9 to 9, 5 mm in status 5 minutes after the addition of the aqueous sodium chloride solution with a concentration of 0.9 weight percent in an amount of 2000 g / m ² (in a state after absorption).

The recessed portions 44 (44X and 44Y) preferably have, after absorption, a depth of 20% or more, more preferably 50% or more, even more preferably 65% or more and 100% or less, preferably 80% or less, more preferably 75% or less, in particular 20% to 100%, preferably 50% to 80%, more preferably 65% to 75% of the thickness of the absorbent element 4A (i.e., the thickness of the protruding portions 43).

In particular, the thickness of the recessed portions 44 (44X and 44Y) in the post-absorption state is preferably 0.2 mm or more, more preferably 2 mm or more, even more preferably 5.5 mm or more and preferably 30 mm or less, more preferably 10 mm or less, even more preferably 7.5 mm, in particular preferably from 0.2 to 30 mm, more preferably from 2 to 10 mm, even more preferably from 5.5 to 7.5 mm.

The protruding sections 43 of the absorbent element 4A of the diaper 1 have a density equal to the density of the recessed sections 44 (44X and 44Y) or higher than the density of the recessed sections 44 (44X and 44Y).

For use in an absorbent article, such as a disposable diaper, it is preferred that the recessed portions 44 (44X and 44Y) have a density of 30% to 100% of the density of the protruding portions 43 in the pre-absorption state for reasons of security spaces and maintaining the effect of sufficient spreading of the fluid released by the body and rapid absorption.

In particular, the density of the recessed portions 44 (44X and 44Y) in the pre-absorption state is preferably from 0.01 to 1.2 g / cm ³ , and the density of the protruding portions 43 in the pre-absorption state is preferably from 0.01 to 1.2 g / cm ³ .

The density values of the protruding portions 43 and the recessed portions 44 (44X and 44Y) are calculated by dividing the corresponding ground mass values obtained by the method described above by the corresponding thickness values obtained by the method described above.

The absorbent element 4A of the first embodiment is wrapped in a hydrophilic intermediate sheet 5, as shown in FIG. 2. The absorbent element 4A having a longer length in the longitudinal direction Y is wrapped in one intermediate sheet 5 so that the intermediate sheet 5 covers both side edges of the absorbent element 4A and extends on itself on the side of the absorbing element 4A facing the back sheet. Thus, in the diaper 1, the intermediate sheet 5 is located between the absorbent element 4A and the upper sheet 2, as well as between the absorbent element 4A and the back sheet 3.

In the diaper 1, the recessed portions 44 (44X and 44Y) and the intermediate sheet 5 define spaces 9. Since the absorbent element 4A having a concave-convex structure is wrapped by the intermediate sheet 5, spaces 9 are formed between the recessed sections 44 (44X and 44Y) and the intermediate sheet 5. As previously discussed, in the diaper 1 shown in FIG. 1 and 3, the recessed portions 44 (44X and 44Y) are formed as a whole with a mesh configuration on the side of the absorbent element 4 facing the back sheet, the protruding portions 43 are formed in areas corresponding to the mesh cells, and the recessed portions 44 surround each protruding portion 43. Accordingly as shown in FIG. 1-4, spaces 9 include a plurality of spaces 9X formed by recessed portions 44x, the recesses of which “extend” towards the side of the top sheet and the intermediate sheet 5, and spaces 9Y formed by recessed portions 44Y, the recesses of which “extend” in the direction to the side of the top sheet and the intermediate sheet 5. The spaces 9X extend continuously in the transverse direction X in agreement with the recessed portions 44X, and the spaces 9Y extend continuously in the longitudinal direction Y Ovano with recessed areas 44Y.

As described previously, the absorbent element 4A comprises an absorbent polymer 41 and hydrophilic fibers 42, and the absorbent element 4A is characterized by an absorbent polymer 41 contained therein. In particular, the absorbing polymer 41, in particular, is characterized by a low rate of passage of fluid under load, a low absorption rate determined by the DW (Demand Wettability) method (hereinafter also referred to as the absorption rate of physiological saline solution (Demand Wettability Test - The Demand Wettability method was first described by Bernard M. Lichstein, INDA, 2nd Annual Symposium on Nonwoven Product Development, March 5 & 6, 1974) at the initial stage, and the increased rate of absorption of physiological saline after a specified period of time. The “DW absorption rate” or “physiological saline absorption rate” referred to herein is the absorption rate determined by the Demand Wettability (DW) method using the demand wettability tester, widely known as a device used to implement the DW method.

The absorption polymer 41 will be described in detail.

In order for the absorption polymer 41 to exhibit high absorption capacity and to prevent leakage of body fluid, the absorption capacity of the absorption polymer 41 is preferably 30 g / g or more, more preferably 31 g / g or more, and preferably 50 g / g or less, more preferably 45 g / g or less, even more preferably 40 g / g or less, in particular preferably 30 to 50 g / g, more preferably 30 to 45 g / g, even more preferably 31 to 40 g / g. The absorption capacity of the absorption polymer 41 is determined by centrifugation retention determination in accordance with JIS K7223 (JIS - Japanese Industrial Standard). The centrifugation retention capacity of an absorbing polymer is a characteristic property correlated with absorbency (absorption coefficient). Typically, an absorbent polymer having a higher centrifugal retention capacity has a higher absorbency.

The method for determining retention capacity during centrifugation (absorption capacity)

The centrifugal retention capacity is determined in accordance with JIS K7223 (1996). A rectangle with a width of 10 cm and a length of 40 cm, cut from a nylon woven material (mesh size: 250 mesh; supplied by Sanriki Seisakusyo Co., Ltd., under the trade name “Nairon Ami”), fold in half along the transverse center line, and both sides are heat-sealed to make a nylon bag with a width of 10 cm (internal width: 9 cm) and a length of 20 cm. The absorbent polymer to be analyzed and having a precisely defined mass of 1.00 g is uniformly placed in the lower part of the nylon bag. The bag and contents are soaked in physiological saline (an aqueous solution of sodium chloride with a concentration of 0.9 weight percent) at 25 ° C. After soaking for 1 hour, the bag is removed from physiological saline, suspended vertically for 1 hour to drain, and then subjected to dehydration using a centrifuge (Tokugata H-130C from Kokusan Co., Ltd.) at 143G (800 rpm) for 10 minutes. The mass of the dehydrated sample is measured, based on which the centrifugal retention capacity (absorption capacity) is calculated in accordance with the formula:

Centrifugal retention capacity (g / g) = (a'-b-c) / C

where a 'is the total mass of the sample and nylon bag after dehydration by centrifugation; b is the mass of the nylon bag before water absorption, and c is the mass of the sample before water absorption (in the dry state). The measurement is performed five times (n = 5). The maximum and minimum values are discarded, and the average value for the remaining three measured values is taken. The measurement is performed in an environment with a temperature of 23 ± 2 ° C and a relative humidity of 50 ± 5%. The sample is kept in the medium for at least 24 hours before measurement.

Preferably, the absorption polymer 41 has an absorption capacity under a load of 2.0 kPa of 20 g / g or more and not more than 40 g / g, preferably not more than 35 g / g, so that the absorption element 4A can absorb the fluid secreted by the body in a reliable manner without allowing fluid to flow over its surface even under pressure while worn. That is, the absorption capacity under load (2.0 kPa) is preferably only 20 to 40 g / g, more preferably 20 to 35 g / g. A load of 2.0 kPa is almost equivalent to the pressure acting on the absorbent element while wearing the absorbent article. Absorption capacity under load is a measure of how much fluid is capable of absorbing the absorbing polymer at a pressure applied to the absorbing element while wearing the absorbent article.

The method of determining the amount of absorption under load:

The method and apparatus described in JP 2003-235889A are used. A plastic cylindrical tube (inner diameter: 30 mm; height: 60 mm), closed at one end with a nylon mesh (mesh size: 63 μm; JIS Z8801-1: 2000), is held upright with a nylon mesh located at the bottom and a sample ( absorbing polymer), the exact weight of which is 0.50 g, is placed on a nylon mesh with an almost uniform thickness. A load with an outer diameter of 29.5 mm and a thickness of 22 mm is placed on the sample to apply a load of 2.0 kPa to the sample. The tube containing the sample and the load is mounted vertically in a Petri dish (diameter: 120 mm) containing 60 ml of physiological saline, so that the nylon mesh is at the bottom. After soaking for 60 minutes, the tube and contents are removed, drained for 15 minutes and weighed to determine the amount of physiological saline absorbed by the sample. The amount of absorbed physiological saline is divided by 0.5 to obtain the absorption volume (g / g) of the sample under load. The measurement is performed five times (n = 5). The maximum and minimum values are discarded, and the average value for the remaining three measured values is taken. The measurement is performed in an environment with a temperature of 23 ± 2 ° C and a relative humidity of 50 ± 5%. The sample is kept in the medium for at least 24 hours before measurement.

In order for the absorbent polymer 41 to be ready to undergo gel blocking near the surface of the absorbent element 4A facing the skin under pressure while worn to reduce re-wetting after completion of absorption of the body fluid, it is preferred that the absorbent polymer 41 has a passage speed liquids under a load of 2.0 kPa of less than 1 ml / min, more preferably from 0 to 0.9 ml / min. The rate of passage of fluid under load is a measure used to evaluate the rate of spreading and penetration of a fluid in an absorbent element.

The method for determining the speed of passage of fluid under load:

The speed of passage of fluid under load is determined by using the method and device described in JP 2003-235889A. 0.32 ± 0.005 g of an absorbing polymer sample and physiological saline (an aqueous solution of sodium chloride with a concentration of 0.9 weight percent) in an amount sufficient to swell the absorbing polymer, for example at least 5 times, are placed in a 100 ml glass beaker exceeding the saturation capacity of the absorbing polymer, and left to stand for 30 minutes. Separately prepare a filter cylinder (inner diameter: 25.4 mm) equipped with a metal mesh (mesh size: 150 μm, sintered stainless steel 30SUS filter with biological column supplied by Sansyo Co., Ltd.) and a narrow tube ( inner diameter: 4 mm, length: 8 cm) with a tap (inner diameter: 2 mm). The cylinder with the tube closed by the tap is held upright, and the entire contents of the beaker (containing the swollen sample) is poured into it. A round rod (diameter: 2 mm), at one end of which a metal mesh is attached, having a mesh cell size of 150 μm and a diameter of 25 mm, is inserted into the filter cylinder with a metal mesh located below until it enters into contact with the sample. The load is placed in the cylinder to apply a load of 2.0 kPa to the sample. After keeping the system left in this state for 1 minute, the valve is opened and the time T1 (s) is measured, so that the liquid level drops from the mark on the scale corresponding to 60 ml to the mark on the scale corresponding to 40 ml ( that is, the time required to pass 20 ml of saline solution). The fluid flow rate under a load of 2.0 kPa is calculated in accordance with the following formula by means of a time T1 (s) thus measured. In the formula, T0 is the time required for 20 ml of saline to pass through a metal mesh of the same filtration cylinder that does not contain any sample.

The speed of the fluid (ml / min) = 20 × 60 / (T1-T0)

The measurement is performed five times (n = 5). The maximum and minimum values are discarded, and the average value for the remaining three measured values is taken. The measurement is performed in an environment with a temperature of 23 ± 2 ° C and a relative humidity of 50 ± 5%. The sample is kept in the medium for at least 24 hours before measurement. More details regarding the method for determining the fluid passage rate are given in JP 2003-235889A, paragraphs [0008] and [0009]. The device used to perform the measurements is shown in FIG. 1 and 2 of the same document.

In order for the absorption polymer 41 to rapidly absorb the fluid released by the body at a later stage to reduce re-wetting and to reduce the amount of time that the skin of the carrier is moistened, the absorption polymer 41 preferably has a physiological saline absorption rate (absorption rate determined by the DW method) component 40 ml / (g · 10 min) or more, more preferably 42 ml / (g · 10 min) or more and 60 ml / (g · 10 min) or less, more preferably 55 ml / (g · 10 min ) or less, in particular and from 40 to 60 ml / (g * 10 min), more preferably from 42 to 55 ml / (g * 10 min). The rate of absorption of physiological saline solution characterizes the behavior of the absorbing polymer, which absorbs and absorbs the fluid secreted by the body or takes the fluid secreted by the body into the spaces between adjacent particles of the absorbing polymer, and serves as an indicator characterizing the preservation of the shape of the absorbing element during manufacture and after absorption of the liquid, in particular, maintaining shape after absorption of the fluid released by the body.

In order for the absorbent polymer 41 to have low absorbency at the initial stage to ensure that it is ready to receive the fluid released by the body into each of the layers 4F, 4S and 4T of the absorbent element and to spread the fluid in the direction in the plane (XY direction), the absorbent polymer 41 preferably has an absorption rate determined by the DW method of 5 ml / (g · 1 min) or more, more preferably 8 ml / (g · 1 min) or more and 13 ml / (g · 1 min) or less, in particular from 4 to 13 ml / (g · 1 min), more preferably from 8 d 13 ml / (g * 1 min).

The method for determining the absorption rate of physiological saline solution (demand absorption rate):

The rate of absorption of physiological saline is determined by using the method and device described in JP 6-136012A, namely, Demand Wettability Tester. In particular, the level of the liquid, which is a physiological saline solution, must be combined with the surface of the stand (diameter: 70 mm, glass filter No. 1, on which filter paper No. 2 is placed), and 0.3 g of the absorbing polymer, which must be subjected tested, sprinkled on a stand. Determine the absorption of water after 1 minute and 10 minutes by reading the readings on the scale of the burette, showing the drop in the level of the liquid, which is a physiological saline solution. The absorption of water at the time of scattering of the absorbing polymer is taken equal to zero. The amount of water absorbed thus measured is considered as the absorption rate of physiological saline / absorption rate determined by the DW method. The measurement is performed five times (n = 5). The maximum and minimum values are discarded, and the average value for the remaining three measured values is taken. The measurement is performed in an environment with a temperature of 23 ± 2 ° C and a relative humidity of 50 ± 5%. The sample is kept in the medium for at least 24 hours before measurement.

The absorption polymer 41 preferably has an average particle size of 100 μm or more, more preferably 200 μm or more, and more preferably 500 μm or less, more preferably 500 μm or less, in particular 100 to 1000 μm, more preferably 200 to 500 μm for reasons related to preventing falling out of the product, wearing comfort and preventing slipping. The shape of the particles is not particularly limited and may be spherical, rounded, like grapes, bag-shaped, or they may have a different shape.

An absorbent polymer 41 having the above characteristics is obtained, for example, by polymerizing at least one of the monomers described below. If necessary, the polymerization product is crosslinked. The polymerization process is not particularly limited, and various processes known as processes for producing absorbing polymers, such as slurry phase inverse polymerisation and aqueous solution polymerization, can be selected. In accordance with the need, the resulting polymer is crushed, sieved or surface treated.

The monomers used to prepare the absorbent polymer 41 are water soluble compounds having a polymerizable unsaturated group. Examples of such monomers include vinyl monomers having a polymerizable unsaturated group, such as unsaturated carboxylic acids of the olefin series and their salts, esters of unsaturated carboxylic acids of the olefinic series, unsaturated sulfonic acids of the olefinic series and their salts, unsaturated phosphoric acids of the olefinic series and their salts, esters of unsaturated phosphoric acids of the olefin series, unsaturated amines of the olefin series, unsaturated ammonium salts of the olefin series and unsaturated amides lefinovogo series.

Examples of unsaturated carboxylic acids of the olefin series and their salts include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and fumaric acid, and salts of these acids and alkali metals and ammonium salts of these acids.

Examples of olefinic unsaturated carboxylic acid esters include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, polyethylene glycolmono (meth) acrylate and phenoxypolyethylene glycol (meth) acrylate.

Examples of sulfonic acids of the olefinic series and their salts include vinyl sulfonic acid, allyl sulfonic acid, styrene sulfonic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, 2- (meth) acryloethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid and their

Examples of unsaturated phosphoric acids of the olefin series and their salts include (meth) acryloyl polyoxyethylene esters of phosphoric acids and their salts.

Examples of unsaturated olefin amines include N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide.

Examples of unsaturated ammonium salts of the olefin series include quaternary ammonium salts of the unsaturated amines of the olefin series described above.

Examples of unsaturated olefin amides include (meth) acrylamide, derivatives of (meth) acrylamide such as methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide and N, N-dimethyl (meth) acrylamide, and vinyl methylacetamide.

Other monomers include unsaturated monomers containing a nonionic hydrophilic group such as vinyl pyridine, N-vinyl pyrrolidone, N-acryloyl piperidine, N-acryloyl pyrrolidine and N-vinyl acetamide.

As used herein, the term “(meth) acrylate” refers to acrylate or methacrylate; the term “(meth) acrylamide” refers to acrylamide or methacrylamide, and the term “(meth) acryloyl” refers to acryloyl or methacryloyl.

Of these monomers, unsaturated carboxylic acids of the olefinic series and their salts are preferred. Acrylic acid, methacrylic acid and their alkali metal salts, alkaline earth metals or ammonium salts are more preferred. Acrylic acid, alkali metal salts (e.g. lithium, sodium or potassium) of acrylic acid and ammonium salt of acrylic acid are particularly preferred.

Examples of suitable crosslinking agents include polyallyl compounds, such as N, N-diallyl acrylamide, diallylamine, triallylamine, diallyl methacrylamide, diallyl phthalate, diallyl maleate, diallyl terephthalate, triallyl cyano triethyl triethyl triallyl triethyl triallyl triethyl triallyl triethyl triallyl triethyl triallyl triethyl triallyl triethyl triallyl triethyl triallyl triallyl triethyl triallyl triethyl triallyl triallyl triallyl triallyl triallyl triallyl triallyl triallyl triallyl triallyl trial polyvinyl compounds such as divinylbenzene, N, N'-methylene bis (meth) acrylamide, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, trimethylol propane tri (meth) acrylate, trimethylolpropane-di (meth) acrylate, tri (meth) acrylate of glycerol, a copolymer of glycerol acrylate and methacrylate modified with ethylene oxide trimethylolpropantry (meth) acrylate, tetra (meth) acrylate pentaerythritol and hexa (meth) acrylate dipentaerythritol; polyglycidyl ethers such as diglycidyl ether of ethylene glycol, diglycidyl ether of polyethylene glycol, diglycidyl ether of glycerol and polyglycidyl ether of polyglycerol; halogen epoxy compounds such as epichlorohydrin, epibromohydrin and -methylepichlorohydrin; polyaldehydes such as glutalaldehyde and glyoxal; polyols, such as glycerin, polyvinyl alcohol and polyesters modified silicones; polyamines such as ethylenediamine, diethylene triamine, triethylenetetramine, tetraethylene pentamine, pentaethylene hexamine, polyethyleneimine, polyvinylpyrrolidone and amino-modified silicones; hydroxyvinyl compounds such as glycidyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxylpropyl (meth) acrylate and glycidyl (meth) acrylate; polyisocyanate compounds such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate; multifunctional oxazoline compounds, such as 1,2-ethylene bisoxazoline; carbonic acid derivatives such as urea, thiourea, guanidine, dicyandiamide and 2-oxazolidinone; alkylene carbonate compounds such as 1,3-dioxolan-2-one, 4-methyl-1,3-dioxolan-2-one, 4,5-dimethyl-1,3-dioxolan-2-one, 4,4-dimethyl -1,3-dioxolan-2-one, 4-ethyl-1,3-dioxolan-2-one, 4-hydroxymethyl-1,3-dioxolan-2-one, 1,3-dioxan-2-one, 4 methyl-1,3-dioxan-2-one, 4,6-dimethyl-1,3-dioxan-2-one and 1,3-dioxopan-2-one; and polyvalent metal compounds having a cation, for example, calcium, magnesium, zinc, aluminum, iron, zirconium or titanium compounds, such as hydroxides, inorganic salts (eg, chlorides) and organometallic salts. Polyhydric alcohols are also useful, including ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, 1,3-propanediol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, polypropylene glycol, glycerol, polyglycerol 2 -1,4-diol, 1-3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexane dimethanol, 1,2-cyclohexanol, trimethylol propane, diethanolamine, triethanolamine, polyoxypropylene , block copolymer of oxyethylene and oxypropylene, penetaerythritol and sorbitol. These crosslinking agents can be used either individually or in combination of two or more of these crosslinking agents.

In preparing the absorbent polymer, the polymer particles can be surface treated by using a polymer compound having a functional group, such as polyethyleneimine, polyvinyl alcohol and polyallylamine. The polymer compound can be used either by itself or in combination with the above crosslinking agents. A crosslinking agent having two or more polymerizable unsaturated groups, or a crosslinking agent having two or more reactive groups can be used in an amount specified in accordance with the specified characteristics of the resulting absorbent polymer. A preferred amount of such a crosslinking agent is 0.001 weight percent or more, more preferably 0.01 weight percent or more and 20 weight percent or less, more preferably 1 weight percent or less, in particular 0.001 to 20 weight percent, more preferably 0 , 01 to 1 weight percent, relative to the entire composition of the monomers (polymerizable (s) monomer (s)) other than a crosslinking agent having two or more polymerizable unsaturated groups). When using a crosslinking agent or an aqueous solution thereof, a hydrophilic organic solvent may be used, or an acid or pH buffer may be used in combination.

Examples of surface treatment agents include surface modification oils, such as modified silicones; polyvalent metal compounds such as aluminum sulfate, aluminum-potassium alum (double salt of potassium sulfate and aluminum sulfate), aluminum-ammonium alum (double salt of ammonium sulfate and aluminum sulfate), aluminum-sodium alum (double salt of sodium sulfate and aluminum sulfate) , (poly) aluminum chloride and their hydrates; cationic compounds such as alkylamines and dialkylamines and their salts; polycationic compounds such as polyethyleneimines, polyvinylamines, polyallylamines and their salts, and particulate inorganic compounds such as silica, alumina, titanium oxide, zinc oxide and bentonite. They can be used either individually or in combination of two or more of these compounds.

In the present invention, it is necessary that the polymer is surface treated to such an extent that blocking due to gel formation occurs when the utilization rate of the absorbing polymer, which has the same value as the degree of swelling in the invention, reaches from 50% to 70% . Upon receipt of the absorbing polymer in the reaction system, various additives can be used, provided that no negative effects are created. Examples of useful additives include dispersants, such as starch cellulose, derivatives of starch cellulose, polyvinyl alcohol, polyacrylic acid (or salts), crosslinked polyacrylic acid (or salts), polyethylene glycol and polyvinylpyrrolidone; polymerization inhibitors such as quinones; kinetic chain transmitters (regulators of the degree of polymerization) and agents that promote the formation of chelate compounds.

Examples of hydrophilic fibers that form the absorbent element 4A together with the absorbent polymer 41 include (1) natural cellulose fibers, such as wood pulp fibers, for example, bleached softwood kraft pulp (NBKP) fibers, bleached hardwood kraft fibers cellulose (LBKP), bleached softwood sulphite cellulose (NBSP) fibers and thermomechanical cellulose (TMP) fibers, cotton cellulose fibers, bast fibers such as paper tree fiber, paper tree bark fiber and Gampi fiber, and cellulose ny fibers from non-wood plant materials, for example, from straw, bamboo, kenaf and flax; (2) cellulose hydrate fibers, such as viscose and copper-ammonia; (3) hydrophilic synthetic fibers, such as polyvinyl alcohol fiber and polyacrylonitrile fiber; and (4) synthetic fibers, such as polyethylene terephthalate (PET) fiber, polyethylene (PE) fiber, polypropylene (PP) fiber, and polyester fiber that have been hydrophilic by surfactants. The hydrophilic fiber is preferably natural cellulose fiber or hydrated cellulose fiber, more preferably wood pulp fiber. The term "cellulosic fiber" as used herein is intended to encompass bleached cellulose obtained without the use of elemental chlorine (ECF - elementary chlorine-free) and bleached cellulose obtained without any chlorine (TCF - totally chlorine-free), upon receipt which essentially no chlorine compound is used in the bleaching process. The hydrophilic fibers listed above can be used either individually or in combination of two or more of these hydrophilic fibers.

In the diaper 1, the absorbent element 4A is attached to the top sheet 2 and the back sheet 4 by means of an adhesive (for example, hot-melt non-solvent adhesive) applied between them with some pattern, for example, in the form of dots, spirals and stripes.

Next will be described a method of manufacturing an absorbent element 4A used in the diaper 1, that is, an absorbent element 4A having protruding sections 43 (with a high bulk and a high density) and recessed portions 44 (with a low bulk and a low density) formed as one whole.

FIG. 7 illustrates one embodiment of a method for manufacturing an absorbent element 4A and a device used for this. A device for manufacturing an absorbent element 4A includes a rotary drum 50 rotatable in the direction shown by arrow R1, a duct 60 for supplying an absorbent material 45 comprising an absorbent polymer 41 and hydrophilic fibers 42, which are the starting material for manufacturing the absorbent element 4A, to the peripheral surface of the rotating drum 50, the transfer roller 70, driven into rotation in the direction shown by the arrow R2, which is located diagonally below and gave further downstream of the rotary drum 50, the vacuum box 65 located between the duct 60 and the transfer roller 70 along the circumference of the rotary drum 50, the mesh belt 75 as a breathable sheet-shaped element extending between the vacuum box 65 and the rotary drum 50 and between the transfer roller 70 and the rotary drum 50, and a vacuum conveyor 80 located under the transfer roller 70.

As shown in FIG. 7, the rotary drum 50 is a cylindrical element driven by power from a drive device, such as an engine, to rotate an element that forms the outer peripheral surface of the drum around a horizontal axis. The space 56 in which rarefaction can be created is formed in the non-rotating part inside the rotating drum 50 (from the axis of rotation). Space 56 is connected to a known device (not shown) for creating a vacuum, such as a suction fan. The rarefaction apparatus operates to maintain negative pressure in the space 56. On the other hand, other spaces 57 and 58 inside the rotary drum 50 (from the axis of rotation) are connected to tubes not shown, which allow the suction of outside air.

As shown in FIG. 7, the rotary drum 50 has a plurality of recessed zones 51 with a shape corresponding to the shape of the absorbent element 4A to be obtained. The recessed areas 51 are located on the outer peripheral surface of the drum 50 at equal intervals in the direction R1. Each recessed area 51 has a mesh plate 52 having a large number of holes, as the bottom and elements 53 with minimum breathability, made of metal or polymer, located at its bottom, as shown in FIG. 8. Elements 53 with minimal breathability protrude outward from the mesh plate 52 and are arranged so that they correspond to the shapes and locations of the recessed sections 44 (44X and 44Y). As shown in FIG. 8, zones 54 of the mesh plate 52, which are limited only by the minimal permeability elements 53 thus arranged, correspond to the protruding portions 43, and the area 55 of the mesh plate 52, continuously surrounding the zone 54, corresponds to the peripheral portion 402. The outer peripheral surface of the rotary drum 50, different from the recessed zones 51, formed by a rigid, airtight, made of metal frame of the rotating drum 50.

As shown in FIG. 5, the duct 60 has an output end portion covering that portion of the peripheral outer surface of the rotary drum 50, which is located above the inner space 56 in which negative pressure is maintained. The opposite end (not shown) of the duct 60 has a device for supplying fibrous material. A device for supplying fibrous material includes a shredder designed to shred the sheet-like wood pulp to pulp pulp and feed the shredded cellulose (hydrophilic fibers) into the box, and an absorbing polymer input element for introducing the absorbing polymer into the stream in the box 60.

The transfer roller 70 has a cylindrical breathable outer peripheral portion that rotates in the R2 direction due to power from a drive device such as an engine. The space 71 in which rarefaction can be created is formed in the non-rotating part inside the transfer roller 70 (on the side of the axis of rotation). Space 71 is connected to a known device (not shown) for creating a vacuum, such as a suction fan. The rarefaction apparatus operates to maintain negative pressure in space 71.

The vacuum box 65 is located between the downstream end 601 of the box 60 and the transfer roller 70 along the rotation direction R2. The vacuum box 65 has a box shape and has an open portion that opens toward the rotating drum 50, on its side facing the rotating drum 50. The vacuum box 65 is connected to a known device (not shown) for creating a vacuum, such as a suction fan, by means of a chimney 67. A negative pressure generating apparatus is operable to maintain negative pressure in the interior of the vacuum box 65.

The mesh tape 75 is an air-permeable (having holes) tape forming an endless tape that continuously moves along a predetermined path and is guided by a plurality of freely rotating rollers and a transfer roller 70. The mesh tape 75 is driven by rotation of the transfer roller 70. The mesh tape 75 is in contact with the outer peripheral surface of the rotary drum 50 when it passes in front of the opening of the vacuum box 65, and near the place where the transfer shaft to 70 and the rotary drum 50 are located closest to each other, the mesh tape 75 is separated from the outer peripheral surface of the rotary drum 50 and moves to the transfer roller 70.

The vacuum conveyor 80 includes a breathable belt 83 covering the drive roller 81 and the driven roller 82, and a vacuum box 84 located opposite the transfer roller 70, with the breathable belt 83 located between the vacuum box 84 and the transfer roller 70.

Next, a method for continuously manufacturing an absorbent element 4A (absorbent element 4) by using the above-described device will be illustrated.

The rarefaction devices connected to the space 56 in the rotary drum 50 and to the vacuum box 65 function to maintain negative pressure in the space 56 and in the vacuum box 65. The negative pressure created in the space 56 causes the formation of an air stream in which the absorbing material 45 is transferred to the outer peripheral surface of the rotary drum 50. Next, the rotary drum 50 and the transfer roller 70 rotate, and the vacuum conveyor 80 is driven. The fibrous material feeding device is operable to first feed the cellulose (hydrophilic fiber) divided into fibers into the duct 60. The cellulose (hydrophilic fiber) is entrained by the air flow passing through the duct 60 and is supplied to the outer peripheral surface of the rotary drum 50 in a dispersed state .

When the recessed area 51 of the rotary drum 50 moves along the portion covered by the duct 60, cellulose (hydrophilic fiber) is sucked into the recessed area 51 of the rotary drum 50. As shown in FIG. 9, cellulose (hydrophilic fiber) is gradually deposited on the mesh plate 52 in each of the zones 54 and in the zone 55 of the recessed zone 51. The resulting deposited material 40T becomes the third 4T layer.

After that, the absorbing polymer is introduced into the box 60 in addition to cellulose (hydrophilic fiber) divided into fibers. The absorbent material 45 is captured by the air flow passing through the duct 60 and is supplied to the outer peripheral surface of the rotating drum 50 in a dispersed state. The feed absorbent material 45 is a mixture having a weight ratio of absorbent polymer to cellulose (hydrophilic fibers) (weight of absorbent polymer / weight of cellulose (hydrophilic fibers)) of 1 or more.

When the recessed zone 51 moves along the portion covered by the duct 60, the absorbent material 45 (a mixture of fibrous material and the absorbent polymer) is sucked onto the deposited material 40T of the recessed area 51 of the rotary drum 50. As shown in FIG. 9, the absorbent material 45 is gradually deposited on the deposited material 40T, which has been deposited on the mesh plate 52 in each of the zones 54 and in the region 55 of the recessed zone 51. The thus deposited material 40S deposited on the deposited material 40T becomes the second layer 4S.

Subsequently, the fiberized cellulose (fibrous material) and the absorbent polymer are additionally fed into the duct 60. The absorbent material 45 is captured by the air flow passing through the duct 60 and is supplied to the outer peripheral surface of the rotary drum 50 in a dispersed state. The feed absorbent material 45 is a mixture having a weight ratio of absorbent polymer to cellulose (hydrophilic fibers) (weight of absorbent polymer / weight of cellulose (hydrophilic fibers)) of 1 or more. The absorbent material 45 supplied in this step has a lower absorbent polymer content and a lower content of cellulose (hydrophilic fibers) compared to the absorbent material 45, which was fed to form the precipitated material 40S.

When the recessed area 51 moves along the portion covered by the duct 60, the absorbent material 45 (a mixture of fibrous material and the absorbent polymer) is sucked onto the deposited material 40S of the recessed area 51 of the rotary drum 50. As shown in FIG. 9, the absorbent material 45 is gradually deposited on the deposited material 40S, which was deposited on the mesh plate 52, in each of the zones 54 and in the region 55 of the recessed zone 51. The thus deposited material 40F, which was deposited on the deposited material 40S, becomes the first layer 4F. In the resulting deposited material 46, consisting of three layers of deposited material 40T, 40S, and 40F, portions 46a formed from absorbent material 45 on the elements 53 with minimal air permeability (portions corresponding to the elements 53 with minimal air permeability) have a relatively small amount of precipitated absorbent material 45, and other sections 46b (areas corresponding to zones 54) have a relatively large amount of deposited absorbent material 45. The deposited material 46 acquires a general the convex structure.

The rotary drum 50 rotates further, and when the recessed zone 51 moves to a position opposite the vacuum box 65, the deposited material 46 present in the recessed zone 51 is sucked onto the mesh belt 75 under the action of the suction force acting from the side of the vacuum box 65. The deposited material 46 located in the recessed area 51, moves in this state to a place located immediately in front of the place where the transfer roller 70 and the rotating drum 50 are located closest to each other, and directly before this place is removed from the recessed zone 51 and moves to the transfer roller 70 and is sucked onto the mesh belt 75.

Thus, the deposited material 46, having a concave-convex structure, moves to the transfer roller 70 together with the mesh belt 75 and moves to the moving position from the transfer roller to the vacuum conveyor (the lowest position of the transfer roller 70), being held by suction on the mesh the tape 75, which is moved on the transfer roller 70, while in the indicated position, it moves to the vacuum conveyor 80 under the action of the suction force acting from the side of the vacuum box 84.

In the device for manufacturing the absorbent element of this embodiment, the intermediate sheet 5 of sanitary paper or hydrophilic nonwoven material is introduced onto the vacuum conveyor 80 before the deposited material 46 is placed on the vacuum conveyor 80, so that the deposited material 46 is placed on the intermediate sheet 5. The intermediate sheet 5 are bent by means of a bending plate not shown to wrap the deposited material 46. The deposited material 46 wrapped in the intermediate sheet 5 is cut with equal intervals for the continuous manufacture of blanks 49 of the absorbing elements, each of which has a length of the absorbing element 4A.

In the device for manufacturing an absorbent element according to this embodiment, the resulting absorbent element blank 49 is compressed by means of a pressing device 90 to reliably reduce the thickness of the deposited material 46 forming the absorbent element blank 49 to produce a predetermined absorbent element 4A (absorbent element 4). As shown in FIG. 7, the pressing device 90 includes two smooth rollers 91 and 92 and is configured to compress the material introduced into the area between the rollers 91 and 92 on both sides in the thickness direction (in the vertical direction).

When the deposited material 46 is compressed by means of a pressing device 90, sections 46b (sections corresponding to zones 54) and section 46c (section corresponding to zone 55) having a relatively large amount of absorbent material and greater thickness are compressed more strongly than sections 46a (sections, corresponding to elements 53 with minimal breathability) having a relatively small amount of absorbent material 45 and a small thickness. As a result, in the absorbent member 4A (absorbent member 4) made by using the above-described apparatus, portions 46b (portions corresponding to zones 54 or protruding portions) and portion 46c (corresponding to zone 55) of the deposited material 46 become protruding portions 43 and a peripheral portion, respectively 402, which have a relatively high density, while sections 46a (areas corresponding to elements 53 with minimal breathability) of the deposited material 46 become deepened kami 44 having a relatively low density.

The materials forming the disposable diaper 1 of this embodiment will be described.

The top sheet 2, the back sheet 3, and the standing cuff sheet 62 may be made of any material commonly used in absorbent articles, such as disposable diapers. For example, the topsheet 2 may be formed from a liquid-permeable nonwoven material, a perforated film, or from a laminate thereof. The back sheet 3 may be formed of a polymer film or of a laminate of a polymer film and non-woven material. The sheet 62 forming the standing cuffs may be formed from a stretch film, a nonwoven fabric, a woven fabric, or a laminated sheet thereof.

The fastening tape 7 may be made of any material commonly used in absorbent articles, such as disposable diapers. For example, a male mechanical fastener element such as Magic Tape® from Kuraray Fastening Co., Ltd., Quicklon® from YKK Corp. can be used. and Magicloth® from Kanebo Bell Touch, Ltd.

The intermediate sheet 5 for wrapping the absorbent member 4A may be a core wrapping sheet formed of a hydrophilic sheet, such as a permeable sanitary paper (tissue paper) or a permeable non-woven material.

The elastic element 61 for the formation of standing cuffs, the elastic element 63 for the legs and the waist elastic element 64 may be a thread of elastic materials such as natural rubber, polyurethane, copolymers of styrene and isoprene, copolymers of styrene and butadiene, a copolymer of ethylene and α-olefin, such as copolymers of ethyl acrylate and ethylene.

The effects and advantages achieved by using the absorbent element 4A (the first embodiment of the absorbent element according to the invention) will be considered.

As shown in FIG. 6, the absorption element 4A, in the pre-absorption state, has a second layer 4S continuous from the first layer 4F having a weight ratio of absorption polymer 41 to hydrophilic fibers 42 (weight of absorption polymer / weight of hydrophilic fibers) of 1 or more, wherein the second layer 4S has a higher absorbent polymer content and a higher content of hydrophilic fibers than the first 4F layer. Therefore, when the body fluid is absorbed, the absorption polymer 41 of the second layer 4S tends to have a pronounced swelling compared to the absorption polymer 41 of the first layer 4F, as shown in FIG. 4. As a result, the swollen particles of the absorbent polymer 41 will tend to overlap each other at the inner walls of the recessed portions 44 passing through the thickness of the second layer 4S, thereby guaranteeing the presence of spaces 9, as shown in FIG. 4. In the presence of spaces 9, guaranteed in a similar way after the absorption of the fluid released by the body, it is possible to further spread the fluid released by the body to the outside through the spaces 9. Adequate spreading of the fluid released by the body will reduce re-wetting in the area of the fluid inlet (near the outlet the body of the fluid), resulting in increased dryness. In particular, the absorbent element 4A according to the first embodiment has a second layer 4S formed on the non-skin side of the first layer 4F, recessed portions 44 are formed by forming indentations from the non-skin side towards the skin side of the absorbent element 4A, and the skin side of the absorbent element 4A is formed by the first layer 4F. That is, the first layer 4F is located on the skin-facing side on top of the recessed portions 44. Therefore, after absorbing the body fluid, the absorption polymer 41 of the first layer 4F, the content of which is less than the content of the absorption polymer 41 in the second layer 4S, will swell and block. due to gel formation, later than the absorbent polymer 41 of the second layer 4S, in the fluid entry zone (near the entry point of the fluid released by the body), as shown in FIG. 4. Thus, the fluid released by the body in spaces 9 is effectively prevented from moving back to the side facing the skin, re-wetting in the fluid inlet area is further reduced, and dryness is further increased. The absorption element 4A has a third layer 4T continuously extending from the second layer 4S. In the dry state, when the second layer 4S has a weight ratio of absorbent polymer 41 and hydrophilic fibers 42 (weight of absorbent polymer / weight of hydrophilic fibers) of 1 or more, the third layer 4T has a lower absorbent polymer content and lower hydrophilic fiber content compared to with a second layer 4S and has a weight ratio of absorbent polymer 41 to hydrophilic fibers 42 (weight of absorbent polymer / weight of hydrophilic fibers) of 0.5 or less. Consequently, rich in hydrophilic fibers, the third 4T layer functions efficiently in the sections of the absorbing element that are end-to-end, contributing to the additional spreading of the fluid released by the body to the outside under the action of capillary forces.

In the present invention, the absorbent element is designed to reliably block it due to gel formation and has the following four characteristics: (1) providing a structure with channels (spaces 9) to allow as much liquid to spread as possible before the absorbing polymer 41 is undergo blocking due to gel formation (formation of a second 4S layer having recessed portions 44 with more absorbing polymer 41); (2) placing more absorbent polymer 41 compared to hydrophilic fibers 42 in the first layer 4F and the absence of any recesses (spaces) in the first layer 4F so that blocking due to gel formation occurs mostly in the first layer 4F; (3) the use of an absorbent polymer 41, which has a large absorption capacity under load and a low fluid velocity so that the absorbent polymer 41 can exhibit high absorption capacity under load and then lose fluid permeability (showed blocking due to gel formation); and (4) the use of an absorbent polymer 41 having a low absorption rate at an initial stage and an increased absorption rate at a later stage.

Since the second layer 4S of the absorbent element 4A according to the first embodiment is such that it has a weight ratio of absorbent polymer 41 to hydrophilic fibers (weight of absorbent polymer / weight of hydrophilic fibers) of 1 or more, particles of absorbent polymer 41 swollen by the body fluid tend to overlap each other on the inner walls of the recessed portions 44 passing through the thickness of the second layer 4S, thereby guaranteeing the presence of spaces 9, considered above and shown in FIG. four.

The absorption polymer 41 used in the absorption element 4A according to the first embodiment has the above absorption capacity and the above absorption volume under a load of 2.0 kPa and a liquid passage rate under a load of 2.0 kPa of less than 1 ml / min . With this specification, the absorbent polymer 41 is easily blocked by gel formation in the first layer 4F upon absorption of the fluid released by the body, which is effective to further reduce re-wetting in the fluid entry zone and to further increase dryness.

Since the absorbent polymer 41 used in the absorbent element 4A according to the first embodiment is formed so that it has the predetermined above physiological saline absorption rates determined by the DW method, the absorbent polymer 41 has a low absorption rate at the initial stage of absorption of the body fluid and therefore, it is able to slow down the occurrence of blocking due to gel formation in the first 4F layer. At a later stage of absorption of the fluid released by the body, blocking due to gel formation occurs in the first 4F layer to further reduce re-wetting in the fluid entry zone and to further increase dryness.

The effects and advantages achieved through the use of a diaper 1 (one embodiment of an absorbent article of the invention) using an absorbent element 4A will be considered.

As indicated previously, since the absorbent element 4A after absorbing the fluid released by the body provides the ability to sufficiently spread the fluid released by the body and reduce re-wetting in the fluid inlet area (near the inlet of the fluid released by the body), a disposable diaper 1 in which the absorbent is used element 4A has increased dryness after absorption of the fluid released by the body and creates increased comfort for the wearer during use tions.

The disposable diaper 1 in which the absorbent member 4A is used has an intermediate sheet 5 between the absorbent member 4A and the back sheet 3, so that the recessed portions 44 (44X and 44Y) of the absorbent member 4A and the intermediate sheet 5 form spaces 9, as shown in FIG. . 2. Since the intermediate sheet 5 is hydrophilic, the fluid released by the body located in the spaces 9, the presence of which is guaranteed by taking advantage of the blocking due to gel formation, after absorption of the fluid released by the body, easily flows further outward through the intermediate sheet 5 Thus, the comfort of the wearer during use is further enhanced.

In the presence of recessed portions 44, the diaper 1, in which the absorbent element 4A is used, remains soft and exhibits excellent ability to adhere to the wearer's body even during movements, for example, when walking and when the wearer sits down.

The absorption element 4B, as a second embodiment of the absorption element in accordance with the invention, will now be described based on FIG. 10 and 11.

The description of the absorbent element 4B of the second embodiment will be mainly limited by the differences from the absorbent element 4A of the first embodiment. In all other respects, the description relating to the absorbent element 4A is appropriately applied to the absorbent element 4B.

As shown in FIG. 11, the absorption element 4B has a first layer 4F and a second layer 4S similar to the absorption element 4 and further has a third layer 4T. As shown, the second layer 4S of the absorbent element 4B is located on the skin side of the first layer 4F, and the third layer 4T of the absorbent element 4B is located on the skin side of the second layer 4S. The third layer 4T, the second layer 4S and the first layer 4F are continuous in the thickness direction T and are formed as a whole.

As shown in FIG. 11, the absorbent element 4B has recessed portions 44 passing through the thickness of the second layer 4S and the third layer 4T before adding an aqueous solution of sodium chloride with a concentration of 0.9 weight percent (physiological saline solution). As shown in FIG. 10, the absorbent member 4B does not have any peripheral portion 402, but has only a block portion 401 having a plurality of recessed portions 44 and a protruding portion 43.

As shown in FIG. 11, the absorbent member 4B has a protruding portion 43 that forms the block portion 401 and which protrudes from the non-skin side to the skin side of the absorbent element 4B, and has recessed portions 44 that form the block portion 401, while they are recessed from the skin side toward the non-skin side of the absorbent member 4B. Accordingly, the absorbent element 4B has a three-dimensional profile on its side facing the skin, and a flat surface on its side not facing the skin.

As shown in FIG. 10, the plurality of recessed portions 44 are aligned in the longitudinal direction Y at the same interval to form a “column” 44B extending in the longitudinal direction Y. In the absorbent member 4B, the plurality of columns 44B are arranged in a certain order in the transverse direction X. As shown in FIG. 11, in the absorbent member 4B, the columns 44B are formed so that, when viewed from the side in the transverse direction, the recessed sections 44 of one column 44B will be located in the same place as the recessed sections 44 of another column 44B that is adjacent to this one column 44B in the transverse direction X.

The number of columns 44B of the recessed portions 44 in the block portion 401 is preferably 1 to 5. In the case of the absorbent element 4B, this number is 3.

The number of recessed portions 44 forming one column 44B is preferably from 1 to 10. In the case of the absorption element 4B, this number is 3.

The distance L5 (see FIG. 10) between adjacent columns 44B, defined in the transverse direction X, is preferably 5 to 50 mm for use in an absorbent article, such as for example a disposable diaper.

For use in an absorbent article, such as a disposable diaper, the individual recessed portions 44 preferably have a L6 dimension in the transverse X direction of 1 to 25 mm and a L7 dimension in the longitudinal Y direction of 15 to 500 mm.

Although the individual recessed portions 44 of the absorbent member 4B are rectangular in plan view and have a longer length in the longitudinal direction Y, as shown in FIG. 10, the rectangle can be rounded at four corners, or the shape in the plan view can be a polygon, an oval, a combination thereof, or the recessed portions 44 can be given a different shape.

The description relating to the bulk, density, and the like of the protruding portion 43 and the recessed portion 44 of the absorbing element 4A is applicable to the corresponding characteristics of the absorbing element 4B.

When the above absorbent element 4B is used in the disposable diaper 1, the recessed portion 44 of the absorbent element 4B has a recess extending from the side of the top sheet 2 toward the side of the back sheet 3.

The effects and advantages achieved by using the absorbent element 4B of the second embodiment will be considered.

The description relating to effects from the absorbing element 4B will be greatly limited by differences from effects from the absorbing element 4A. In all other respects, the description relating to effects from the absorbing element 4A is applicable accordingly for effects from the absorbing element 4B.

The materials forming the absorbent element 4B are the same as the materials of the absorbent element 4A.

The diaper 1, which uses the absorbent element 4B, does not have any irregularities on the side facing the skin, and does not create any discomfort for the wearer. The diaper 1 has the ability to keep its shape well after absorbing the fluid secreted by the body without local bulging and has a neat appearance in the crotch part when worn.

The absorption element in accordance with the present invention is in no way limited to the absorption elements 4A and 4B of the first and second embodiments, and various changes can be made therein. The constituent elements of the absorbent elements 4A and 4B can be practiced in appropriate combinations without departing from the spirit and scope of the invention.

For example, while the absorbent elements 4A and 4B of the above embodiments have recessed portions 44 extending through the thickness of the second layer 4S (in the T direction) before supplying an aqueous solution of sodium chloride (physiological saline), as shown in FIG. 6 and 11, recessed portions 44 may not be formed in this state. In other words, it is only necessary that the presence of recessed portions 44 pass through the thickness of the second 4S layer five minutes after the addition of an aqueous solution of sodium chloride with a concentration of 0.9 weight percent in an amount of 2000 g / m ² .

While the absorbent articles 4A and 4B of the above embodiments have a third layer 4T with a skin-side or a non-skin side of the second layer 4S, the presence of a third layer 4T is not significant.

While the disposable diaper 1 using the absorbent element 4A or 4B of the above embodiments has an absorbent element 4A or 4B wrapped in the intermediate sheet 5, the absorbent element may not be wrapped in the intermediate sheet 5.

While the intermediate sheet 5 is what is called a core wrapping sheet, it can be replaced, for example, by what is called a hydrophilic sheet forming a sublayer and located between the top sheet 2 and the absorption element 4A or 4B so as to close skin side of the absorbent element 4A or 4B.

While the absorbent article that uses the absorbent element 4A or 4B of the above embodiments is a disposable diaper type, it can be a stretchable disposable diaper or other absorbent article such as a sanitary pad, incontinence pad , or panty liner for daily use. The following absorbent elements and absorbent articles are disclosed in connection with the above-described embodiments.

(1) An absorption element comprising an absorption polymer and hydrophilic fibers and having a first layer and a second layer, in which:

the first layer has a weight ratio of polymer to hydrophilic fibers (polymer weight / weight of hydrophilic fibers) of 1 or more, and the second layer has a higher absorption polymer content and a higher content of hydrophilic fibers compared to the first layer,

the first layer and the second layer are continuous in the thickness direction, and

the absorbing element has a recessed portion passing through the thickness of the second layer in a state five minutes after adding an aqueous solution of sodium chloride with a concentration of 0.9 weight percent in an amount of 2000 g / m ² .

(2) The absorbent element according to (1), having a recessed portion extending through the thickness of the second layer before adding an aqueous solution of sodium chloride.

(3) The absorption element according to (1) or (2), having a recessed portion and a protruding portion delimited by the recessed portion, wherein the bulk and density of the absorbent material of the recessed portion are equal to or less than the bulk and density of the absorbent material of the protruding portion.

(4) The absorption element according to any one of paragraphs (1) to (3), further having a third layer,

the third layer has a lower content of the absorbing polymer and a lower content of hydrophilic fibers compared to the second layer and a weight ratio of the absorbing polymer and hydrophilic fibers (weight of the absorbing polymer / weight of hydrophilic fibers) of 0.5 or less,

wherein the first layer, the second layer and the third layer are continuous in the thickness direction, and

the recessed portion extends through the thickness of the second and third layers.

(5) The absorption element according to any one of (1) to (4), wherein the second layer has a weight ratio of absorption polymer to hydrophilic fibers (weight of absorption polymer / weight of hydrophilic fibers) of 1 or more.

(6) The absorbing element according to any one of (1) to (5), wherein the recessed portion has a depth of 20% to 100% of the thickness of the absorbing element in the state before absorption.

(7) The absorbent element according to any one of (3) to (6), wherein the recessed portion has a bulk of 0% to 80% of the protruding portion.

(8) The absorbent element according to any one of (1) to (7), having a thickness of from 0.5 to 20 mm in the state before absorption.

(9) The absorption element according to any one of (1) to (8), wherein the absorption polymer has an absorption capacity of 30 to 50 g / g, an absorption capacity under load of 2.0 kPa of 20 to 40 g / g, the rate of fluid passage under a load of 2 kPa, which is less than 1 ml / min, and the absorption rate of physiological saline, determined by the Demand Wettability (DW) (demand absorption rate), from 40 to 60 ml / (g ·10 min).

(10) The absorption element according to any one of paragraphs (1) to (9), wherein the absorption polymer has an absorption capacity of 30 to 50 g / g, an absorption capacity under load of 2.0 kPa of 20 to 40 g / g, the rate of fluid passage under a load of 2 kPa, which is less than 1 ml / min, and the absorption rate determined by the DW method , between 42 and 55 ml / (g · 10 min).

(11) An absorbent member according to any one of (1) - (10), wherein the absorbent polymer has an absorption rate as defined by DW, of 5 to 13 ml / (g * 1 min).

(12) An absorbent member according to any one of (1) - (11), wherein the absorbent polymer has an absorption rate as defined by DW, of from 8 to 13 ml / (g * 1 min).

(13) The absorbent element according to any one of (1) to (12), wherein the ratio of the bulk of the second layer to the bulk of the absorbent polymer of the first layer (weight of the second layer / weight of the first layer) is preferably 1.6 or more, more preferably 2.0 or more, even more preferably 2.1 or more.

(14) The absorption element according to any one of (1) to (13), wherein the ratio of the bulk of the absorbent polymer of the second layer to the bulk of the absorbent polymer of the first layer (second layer / first layer) is preferably 2.5 or less, more preferably 2.3 or less, even more preferably 2.25 or less.

(15) The absorption element according to any one of (1) to (14), wherein the difference in the bulk of the absorbent polymer of the first layer and the bulk of the absorbent polymer of the second layer (second layer is the first layer) is preferably 45 g / cm ² or more, more preferably 70 g / cm ² or more, even more preferably 90 g / cm ² or more.

(16) The absorption element according to any one of (1) to (15), wherein the difference in the bulk of the absorbent polymer of the third layer and the bulk of the absorbent polymer of the second layer (second layer is the first layer) is preferably 150 g / cm ² or less, more preferably 120 g / cm ² or less, even more preferably 100 g / cm ² or less.

(17) The absorbent element according to any one of (1) to (16), wherein the ratio of the bulk of the absorbent polymer of the second layer to the bulk of the absorbent polymer of the third layer (second layer / third layer) is preferably 15 or more, more preferably 17 or more.

(18) The absorbent element according to any one of (1) to (17), wherein the ratio of the bulk of the absorbent polymer of the second layer and the bulk of the absorbent polymer of the third layer (second layer / third layer) is preferably 20 or less, more preferably 19 or less.

(19) The absorbent element according to any one of (1) to (18), wherein the difference in the bulk of the absorbent polymer of the third layer and the bulk of the absorbent polymer of the second layer (second layer — third layer) is preferably 150 g / cm ² or more, more preferably 160 g / cm ² or more.

(20) The absorbent element according to any one of (1) to (19), wherein the difference in the bulk of the absorbent polymer of the third layer and the bulk of the absorbent polymer of the second layer (second layer — third layer) is preferably 200 g / cm ² or less, more preferably 180 g / cm ² or less.

(21) The absorbent element according to any one of (1) to (20), wherein the ratio of the bulk of the hydrophilic fibers of the second layer to the bulk of the hydrophilic fibers of the third layer (second layer / third layer) is preferably 1.4 or more.

(22) The absorbent member according to any one of (1) to (21), wherein the ratio of the bulk of the hydrophilic fibers of the second layer to the bulk of the hydrophilic fibers of the third layer (second layer / third layer) is preferably 1.6 or less.

(23) An absorbent member according to any one of (1) - (22), wherein the difference between the bulk of the hydrophilic fibers of the third layer and the bulk of the second layer of hydrophilic fibers (second layer - the third layer) is preferably 25 g / cm ² or more.

(24) The absorbent element according to any one of (1) to (23), wherein the difference in the bulk of the absorbent polymer of the third layer and the bulk of the absorbent polymer of the second layer (second layer — third layer) is preferably 35 g / cm ² or less.

(25) An absorbent article comprising a top sheet located on the side facing the skin, a back sheet located on the side not facing the skin, and an absorbent member according to any one of (1) to (24), located between the top sheet and back sheet.

(26) The absorbent article of claim 25, wherein the second layer is located on the skin side of the first layer, and

the recessed portion is recessed from the side of the top sheet toward the side of the back sheet.

(27) The absorbent article according to paragraph 25, wherein the second layer is located on the non-skin side of the first layer, and

the recessed portion is recessed from the side of the back sheet toward the side of the top sheet.

(28) An absorbent article according to any one of (25) to (27), further comprising a hydrophilic intermediate sheet located between the absorbent member and the top sheet.

(29) An absorbent article according to any one of (25) to (28), further comprising a hydrophilic intermediate sheet located between the absorbent member and the back sheet.

(30) The absorbent article according to paragraph 28 or 29, wherein a space is formed between the recessed portion and the intermediate sheet.

EXAMPLES

The present invention will be further illustrated in more detail with reference to Examples, but it should be understood that the invention is not considered to be limited by these examples.

Synthesis of absorbent polymer A:

In a reactor with a capacity of 5 liters, equipped with a stirrer (with a fixed blade), a counterflow condenser, an inlet for dropping monomer, an inlet for nitrogen gas and a thermometer, polyoxyalkylene ether of phosphoric acid ester was added as a dispersing agent in an amount of 0.09% (as active component) relative to the weight of acrylic acid, and 1500 ml of n-heptane was added thereto. The mixture was stirred at 300 rpm in a nitrogen atmosphere and heated to 90 ° C.

Separately, 80% acrylic acid (from Toa Gosei Co., Ltd.) and ion-exchanged water were charged into a three-necked vessel with a capacity of 2 liters. During ice cooling, a 48% aqueous sodium hydroxide solution (from Asahi Glass Co., Ltd.) was added dropwise to this vessel to obtain 1054 g of an aqueous sodium acrylate solution (degree of neutralization: 72%; concentration: approximately 48%) as an aqueous solution of monomer. A solution of 0.25 g of sodium N-acylglutamate (Amisoft GS-11F, from Ajinomoto Co., Inc.) dissolved in 3.0 g of ion exchange water was added to the aqueous monomer solution, followed by stirring for some time. The resulting solution was divided into two parts, each of which weighed 528 g, and these parts were called aqueous solution A of monomer and aqueous solution B of monomer.

Then 0.06 g of 2,2'-azobis (2-amidinopropane) dihydrochloride (V-50, from Wako Pure Chemical Industries, Ltd.), 0.20 g of polyethylene glycol (PEG6000) (from Kao Corp.) and 14 g of ion exchange water was mixed to obtain an aqueous initiator / catalyst solution (A). Separately, 0.57 g of sodium persulfate (from Wako Pure Chemical) was dissolved in 10 g of ion exchange water to prepare an aqueous initiator / catalyst solution (B). In addition, an aqueous solution of titanium citrate was prepared (molar ratio of citric acid to Ti: 2.0; amount of Ti: 0.015% relative to acrylic acid).

An initiator / catalyst aqueous solution (A) was added to the monomer A aqueous solution A to obtain monomer A. An initiator / catalyst (B) aqueous solution and 2.4 g of an aqueous titanium citrate solution were added to the monomer aqueous solution B to prepare monomer B.

After confirming that the internal temperature of the 5-liter reactor is 90 ° C, monomer A and monomer B were added successively one after another to it drop by drop from the inlet element designed to allow the monomer to drip by using a microtube pump for a period of of approximately 60 minutes for polymerization. After completion of the dropwise addition, the reaction mixture was subjected to azeotropic dehydrogenation to bring the water content in the absorbing polymer (hydrogel) to 60%. A solution of 0.16 g of ethylene glycol diglycidyl ether (Denacol EX0810, from Nagase Chemtex Corp.) dissolved in 10 g of water was added as a crosslinking agent to the reaction system, followed by azeotropic dehydrogenation to bring the water content in the hydrogel to 50% over a period of approximately 1.5 hours.

A quaternary ammonium salt (Quatamin 86W, from Kao Corp.) diluted with water in an amount of 1% of the hydrogel solids was added to the hydrogel. After cooling, cyclohexane was removed and the product was dried under reduced pressure to obtain an absorbing polymer, which was sieved through a sieve with a sieve mesh size of 850 μm to remove large particles.

5.0 g of the resulting polymer particles and 12 balls of zirconia with a diameter of 10 mm were placed in a test tube with a screw cap with a capacity of 50 ml. The tube was capped, placed on a table type bead mill (V-1, from Irie Shokai Co., Ltd.) and milled for 10 minutes. Grinding treatment was performed 4 times to obtain a total of 20 g of polymer particles. One hundred parts of polymer particles was mixed in a dry state with 0.5 parts of Aerosil 200 (from Nippon Aerosil Co., Ltd.). The resulting absorbent polymer was sieved to remove large particles to obtain an absorbent polymer A having an average particle size of 415 μm.

Absorbing polymer A had an absorption capacity of 38 g / g, a absorption capacity under load of 2.0 kPa of 24 g / g, a liquid flow rate under load of 2.0 kPa of 0 ml / min, and a speed the absorption of physiological saline, determined by the DW method, comprising 46 ml / (g · 10 min) at a later stage (after 10 minutes) and 11 ml / (g · 1 min) at the initial stage (after 1 minute). These physical quantities were determined by the methods described above.

Synthesis of absorbent polymer B:

In a reactor with a capacity of 5 liters, equipped with a stirrer (with a fixed blade), a counterflow condenser, an inlet element for dripping monomer, an inlet element for gaseous nitrogen and a thermometer, sodium was charged polyoxyethylene (cf. EO = 3 mol) C12 alkyl ether sulfate (Emal 20C from Kao Corp.) as a dispersant in an amount of 0.09% relative to the weight of acrylic acid, and 1600 ml of cyclohexane was added. Nitrogen gas was blown into the reactor, and the mixture was stirred with a fixed paddle at 300 rpm and heated to 76 ° C.

Separately, 80% acrylic acid (from Toa Gosei) and ion exchange water were charged into a three-necked vessel with a capacity of 2 liters. During ice cooling, a 48% aqueous sodium hydroxide solution (from Asahi Glass Co., Ltd.) was added dropwise to this vessel to prepare 1054 g of an aqueous sodium acrylate solution (degree of neutralization: 72%; concentration: approximately 48%) as an aqueous solution of monomer. A solution of 0.18 g of sodium N-acylglutamate (Amisoft GS-11F, from Ajinomoto Co., Inc.) dissolved in 3 g of ion exchange water was added to the aqueous monomer solution, followed by stirring for some time. The resulting solution was divided into three parts: an aqueous solution of monomer A weighing 264 g, an aqueous solution of B monomer weighing 264 g, and an aqueous solution of C monomer weighing 528 g.

Then 0.12 g of 2,2'-azobis (2-amidinopropane) dihydrochloride (V-50, from Wako Pure Chemical Industries), 0.20 g of polyethylene glycol (PEG6000) (from Kao Corp.) and 14 g of ion-exchange water mixed to obtain an aqueous initiator / catalyst solution (A). Separately, 0.49 g of sodium persulfate (from Wako Pure Chemical) was dissolved in 10 g of ion exchange water to prepare an aqueous initiator / catalyst solution (B). In addition, an aqueous solution of titanium citrate was prepared (molar ratio of citric acid to Ti: 1.0; amount of Ti: 0.015% relative to acrylic acid).

To an aqueous solution of monomer A, 7.2 g of an aqueous initiator / catalyst solution (A) was added to prepare monomer A. To an aqueous solution of Monomer, 7.2 g of an aqueous solution of initiator / catalyst (A) and 1.5 g of an aqueous solution of titanium citrate to prepare monomer B. To an aqueous solution of monomer C was added 10.5 g of an aqueous solution of initiator / catalyst (B) and 3 g of an aqueous solution of titanium citrate to prepare monomer C.

After confirming that the internal temperature of the 5-liter reactor was 77 ° C, monomer A, monomer B and monomer C, each of which was left to stand for at least 5 minutes, were added successively one by one to the reactor dropwise from an inlet member designed to drip monomer by using a microtube pump for a period of approximately 60 minutes to polymerize. After completion of the polymerization, the reaction mixture was subjected to azeotropic dehydrogenation by using a dehydrogenation tube to bring the water content in the absorbing polymer (hydrogel) to 60%. A solution of 0.20 g of ethylene glycol diglycidyl ether (Denacol EX0810, from Nagase Chemtex) dissolved in 10 g of water was added as a crosslinking agent to the reaction system, followed by azeotropic dehydrogenation to bring the hydrogel water content to 40% over a period of approximately 1.5 hours.

A quaternary ammonium salt (Quatamin 86W, from Kao Corp.) diluted with water in an amount of 1% of the hydrogel solids was added to the hydrogel. After cooling, cyclohexane was removed and the product was dried under reduced pressure to obtain an absorbing polymer, which was sieved through a sieve with a sieve mesh size of 850 μm to remove large particles.

5.0 g of the resulting polymer particles and 12 balls of zirconia with a diameter of 10 mm were placed in a test tube with a screw cap with a capacity of 50 ml. The tube was closed with a lid, placed on a table-type bead mill (V-1, from Irie Shokai) and milled for 10 minutes. Grinding treatment was performed 4 times to obtain a total of 20 g of polymer particles. One hundred parts of polymer particles was mixed in a dry state with 0.5 parts of Aerosil 200 (from Nippon Aerosil). The resulting absorbent polymer was sieved to remove large particles to obtain an absorbent polymer B having an average particle size of 390 μm.

The absorbing polymer B had an absorption capacity of 39 g / g, a absorption capacity under load of 2.0 kPa of 20 g / g, a liquid flow rate under load of 2.0 kPa of 0.3 ml / min, and the rate of absorption of physiological saline, determined by the DW method, of 48 ml / (g · 10 min) at a later stage (after 10 minutes) and 16 ml / (g · 1 min) at the initial stage (after 1 minute) . These physical quantities were determined by the methods described above.

Synthesis of absorbent polymer C:

The absorption polymer was synthesized in the same manner as the absorption polymer B, except for changing the amount of dispersing agent, namely sodium polyoxyethylene (cf. EO = 3 mol) C12 alkyl ether sulfate (Emal 20C from Kao Corp.), from 0.09% to 0.11% relative to the weight of acrylic acid; changing the amount of crosslinking agent, namely, ethylene glycol diglycidyl ether (Denacol EX0810, from Nagase Chemtex), from 0.20 g to 0.25 g and changing the duration of grinding in a ball mill from 10 minutes to 5 minutes. Large particles were removed by sieving to obtain an absorbent polymer C having an average particle size of 360 μm.

The absorption polymer C had an absorption capacity of 35 g / g, a absorption capacity under load of 2.0 kPa of 24 g / g, a fluid flow rate under load of 2.0 kPa of 17 ml / min and a speed the absorption of physiological saline, determined by the DW method, comprising 51 ml / (g · 10 min) at a later stage (after 10 minutes) and 20 ml / (g · 1 min) at the initial stage (after 1 minute). These physical quantities were determined by the methods described above.

EXAMPLE 1

The absorption element shown in FIG. 5 and 6, but not having a third layer, was manufactured using the device shown in FIG. 7.

Absorption polymer A was used as the absorption polymer, and fiberized cellulose (fluff pulverized pulp) was used as the hydrophilic fiber. The resulting absorbent element is specifically described below. The first layer 4F of the absorbent element in the dry state had an absorbent polymer content (bulk) of 80 g / m ² and a hydrophilic fiber content (main mass) of 50 g / m ² and an absorbent weight ratio polymer and hydrophilic fibers (weight of absorbing polymer / weight of hydrophilic fibers) of 1.6. The second layer 4S of the absorbent element in the dry state had a content (bulk) of the absorbent polymer constituting (component) 180 g / m ² and a content (bulk) of hydrophilic fibers constituting (constituent) 150 g / m ² and the weight ratio of the absorbent polymer and hydrophilic fibers (weight of the absorbing polymer / weight of hydrophilic fibers) of 1.2.

The absorption element in the state before absorption had a total length of 385 mm and a total width of 125 mm. The block part of the absorbing element in the state before absorption had a length in the longitudinal direction Y of 375 mm and a total width in the transverse direction X of 105 mm. The peripheral portion 402 in the pre-absorption state had a dimension in the Y direction of 10 mm in each of its longitudinal ends and a dimension in the X direction of 10 mm in each of its side portions.

In the pre-absorption state, the recessed portions 44X, which formed the block portion and extended in the transverse direction X, had a width L1 of 5 mm, and the recessed portions 44y, which formed the block portion and extended in the longitudinal direction Y, had a width L2 of 5 mm . In the pre-absorption state, the protruding portions 43 that formed the block portion had a longitudinal dimension L3 (length) of 40 mm and a lateral dimension L4 (width) of 15 mm.

In the dry state, the recessed portions 44 (44X and 44Y) had a bulk of 130 g / m ² , and the protruding portions 43 had a bulk of 460 g / m ² .

In the state before absorption, the absorbent element had a thickness of 5.0 mm, the recessed portions 44 (44X and 44Y) had a depth of 3.5 mm, which was 70% of the thickness of the absorbing element.

In the state after absorption (5 minutes after adding an aqueous solution of sodium chloride with a concentration of 0.9 weight percent in an amount of 2000 g / m ² ), the absorbing element had a thickness of 9.5 mm, the recessed sections 44 (44X and 44Y) had a depth component of 7.0 mm, which was 74% of the thickness of the absorbing element. Measurements of the thickness and depth in the state after absorption were performed as follows.

The method of measuring the thickness of the absorbing element and the depth of the recessed portion in the state after absorption:

The absorbent element was placed on a horizontal smooth surface of the glass plate so that its side having a concave-convex structure was turned down and its flat side was turned up. An aqueous solution of sodium chloride with a concentration of 0.9 weight percent was supplied in an amount of 2000 g / m ² by using a burette when dripping it from above onto the flat side of the absorbent element. Five minutes later, the absorbent element was cut vertically with a sharp razor. The thickness of the absorbing element and the depth of the recessed portion were measured on the surface of the section. The thickness of the absorbent element was measured in the thickest part, and the thickness of the recessed sections was measured in the thinnest part. Measurements were performed three times. The average value for the three measured values is shown in table 1.

EXAMPLE 2

The absorption element of Example 2 was made in the same manner as in Example 1, except for the use of the absorption polymer B as the absorption polymer.

In the state before absorption, the thickness of the absorbing element was 5.0 mm, and the depth of the recessed sections 44 (44X and 44Y) was 3.5 mm, and this value was 70% of the thickness of the absorbing element.

In the state after absorption (5 minutes after adding an aqueous solution of sodium chloride with a concentration of 0.9 weight percent in an amount of 2000 g / m ² ), the thickness of the absorbing element was 10.2 mm, and the depth of the recessed sections 44 (44X and 44Y) was 7 , 5 mm, while this value was 74% of the thickness of the absorbing element.

EXAMPLE 3

The absorbent element of Example 3 was made in the same manner as in Example 1, except for using the absorbing polymer C as the absorbing polymer.

In the state before absorption, the thickness of the absorbing element was 5.0 mm, and the depth of the recessed sections 44 (44X and 44Y) was 3.5 mm, and this value was 70% of the thickness of the absorbing element.

In the state after absorption (5 minutes after adding an aqueous solution of sodium chloride with a concentration of 0.9 weight percent in an amount of 2000 g / m ² ), the thickness of the absorbing element was 9.1 mm, and the depth of the recessed sections 44 (44X and 44Y) was 6 , 7 mm, while this value was 74% of the thickness of the absorbing element.

EXAMPLE 4

The absorption element according to Example 4 was made in the same manner as in Example 1, except for changing the weight ratios of the absorbing polymer and hydrophilic fibers in the first layer 4F and the second layer 4S. As the absorbing polymer, absorbing polymer A was used, similarly to Example 1.

In particular, the first layer 4F of the absorbent element in a dry state had an absorbent polymer content (bulk) of (g) 110 g / m ² , a hydrophilic fiber content (ground mass) of (g) 80 g / m ² , and a weight the ratio of the absorbing polymer and hydrophilic fibers (weight of the absorbing polymer / weight of hydrophilic fibers) of 1.38.

The second layer 4S of the absorbent element in the dry state had a content (bulk) of the absorbent polymer constituting (component) 140 g / m ² , a content (main mass) of hydrophilic fibers constituting (constituent) 120 g / m ² , and a weight ratio of the absorbing polymer and hydrophilic fibers (weight of absorbent polymer / weight of hydrophilic fibers) of 1.17.

In the state before absorption, the thickness of the absorbing element was 4.5 mm, and the depth of the recessed sections 44 (44X and 44Y) was 2.3 mm, and this value was 51% of the thickness of the absorbing element. In the state after absorption (5 minutes after adding an aqueous solution of sodium chloride with a concentration of 0.9 weight percent in an amount of 2000 g / m ² ) the thickness of the absorbing element was 8.8 mm, and the depth of the recessed sections 44 (44X and 44Y) was 5 , 0 mm, while this value was 57% of the thickness of the absorbing element.

EXAMPLE 5

The absorbent element of Example 5 was made in the same manner as in Example 1, except for changing the weight ratios of the absorbing polymer and hydrophilic fibers in the first layer 4F and the second layer 4S. As the absorbing polymer, absorbing polymer A was used, similarly to Example 1.

In particular, the first layer 4F of the absorbent element in a dry state had an absorbent polymer content (bulk) of (g) 110 g / m ² , a hydrophilic fiber content (ground mass) of (g) 80 g / m ² , and a weight the ratio of the absorbing polymer and hydrophilic fibers (weight of the absorbing polymer / weight of hydrophilic fibers) of 1.38.

The second layer 4S of the absorbent element in the dry state had a content (bulk) of the absorbent polymer constituting (component) 140 g / m ² , a content (main mass) of hydrophilic fibers constituting (constituent) 120 g / m ² , and a weight ratio of the absorbing polymer and hydrophilic fibers (weight of absorbent polymer / weight of hydrophilic fibers) of 1.17.

In the state before absorption, the thickness of the absorbing element was 3.0 mm, and the depth of the recessed sections 44 (44X and 44Y) was 0.5 mm, and this value was 17% of the thickness of the absorbing element.

In the state after the absorption (in 5 minutes after adding an aqueous solution of sodium chloride at a concentration of 0.9 weight percent in an amount of 2000 g / m ²⁾ of the absorbent element thickness was 8.8 mm, and the depth of the recessed sections 44 (44H and 44Y) was 5 , 0 mm, while this value was 57% of the thickness of the absorbing element.

EXAMPLE 6

The absorbent element of Example 6 was manufactured in the same manner as in Example 1, except that the absorbent element had a third layer and that the weight ratio of the absorbing polymer and hydrophilic fibers in the second layer 4S was changed. As the absorbing polymer, absorbing polymer A was used, similarly to Example 1.

In particular, the second layer 4S of the absorbent element in the dry state had an absorbent polymer content (bulk) of (g) 170 g / m ² , a hydrophilic fiber content (gross) of (g) 90 g / m ² , and a weight the ratio of the absorbing polymer and hydrophilic fibers (weight of the absorbing polymer / weight of hydrophilic fibers) of 1.89.

The third layer 4T of the absorbent element in the dry state had an absorbent polymer content (bulk) of 10 g / m ² , a hydrophilic fiber content (main mass) of 60 g / m ² , and a weight ratio of absorbent polymer and hydrophilic fibers (weight of absorbent polymer / weight of hydrophilic fibers) of 0.17.

In the state before absorption, the thickness of the absorbing element was 5.2 mm, and the depth of the recessed sections 44 (44X and 44Y) was 3.7 mm, and this value was 71% of the thickness of the absorbing element.

In the state after absorption (5 minutes after adding an aqueous solution of sodium chloride with a concentration of 0.9 weight percent in an amount of 2000 g / m ² ), the thickness of the absorbing element was 9.2 mm, and the depth of the recessed sections 44 (44X and 44Y) was 6 , 7 mm, while this value was 73% of the thickness of the absorbing element.

EXAMPLE 7

The absorption element shown in FIG. 10 and 11, but not having a third layer, was manufactured using the device shown in FIG. 7.

Absorption polymer A was used as the absorption polymer, and fiberized cellulose (fluff pulverized pulp) was used as the hydrophilic fiber. The resulting absorbent element is described below specifically.

The first layer 4F of the absorbent element in a dry state had an absorbent polymer content (bulk) of 100 g / m ² and a hydrophilic fiber content (main mass) of 80 g / m ² and an absorbent weight ratio polymer and hydrophilic fibers (weight of the absorbing polymer / weight of hydrophilic fibers) of 1.25.

The second layer 4S of the absorbent element in the dry state had an absorbent polymer content (bulk) of 200 g / m ² and a hydrophilic fiber content (main mass) of 150 g / m ² and a weight ratio of absorbent polymer and hydrophilic fibers (weight of absorbing polymer / weight of hydrophilic fibers) of 1.3.

The absorption element (block part) in the state before absorption had a length of 380 mm and a width of 120 mm.

In the pre-absorption state, the distance L5 between the columns 44B adjacent in the transverse direction, each of which consisted of a plurality of recessed sections 44, was 20 mm, and the distance L8 between the columns 44B adjacent in the longitudinal direction was 30 mm. In the pre-absorption state, each of the recessed portions 44 had a size (width) L6 in the transverse direction of (component) 20 mm and a size (length) L7 in the longitudinal direction of (component) 100 mm.

In the dry state the recessed portions 44 have a basis weight of 180 g / m ^2, and the projecting portion 43 has a basis weight is 530 g / m ^2.

In the state before absorption, the absorbent element had a thickness of 5.5 mm, the recessed sections 44 had a depth of 3.2 mm, which was 58% of the thickness of the absorbing element.

In the state after absorption (5 minutes after adding an aqueous solution of sodium chloride with a concentration of 0.9 weight percent in an amount of 2000 g / m ² ), the absorbing element had a thickness of 8.5 mm, the recessed sections 44 had a depth of 5.8 mm, which was 68% of the thickness of the absorbing element.

EXAMPLE 8

The absorbent element of Example 8 was manufactured in the same manner as in Example 7, except for changing the weight ratios of the absorbing polymer and hydrophilic fibers in the first layer 4F and the second layer 4S of the absorbing element. As the absorbing polymer, absorbing polymer A was used, similarly to Example 7.

In particular, the first layer 4F absorbing element in a dry state had a content (the bulk) of the absorbent polymer constituent (component) 125 g / m ^2, the content (basis weight) of hydrophilic fibers constituting the (component) of 100 g / m ^2, and the weight the ratio of the absorbing polymer and hydrophilic fibers (weight of the absorbing polymer / weight of hydrophilic fibers) of 1.25.

The second layer 4S of the absorbent element in the dry state had a content (bulk) of the absorbent polymer constituting (constituent) 160 g / m ² , a content (main mass) of hydrophilic fibers constituting (constituent) 125 g / m ² , and a weight ratio of the absorbing polymer and hydrophilic fibers (weight of absorbent polymer / weight of hydrophilic fibers) of 1.28.

In the state before absorption, the thickness of the absorbing element was 3.5 mm, and the depth of the recessed sections 44 was 0.5 mm, while this value was 14% of the thickness of the absorbing element.

In the state after absorption (5 minutes after adding an aqueous solution of sodium chloride with a concentration of 0.9 weight percent in an amount of 2000 g / m ² ) the thickness of the absorbing element was 7.8 mm, and the depth of the recessed sections 44 was 4.5 mm, this value was 58% of the thickness of the absorbing element.

EXAMPLE 9

The absorption element of Example 9 was manufactured in the same manner as in Example 7, except that the absorption element had a third layer and that the weight ratio of the absorption polymer and hydrophilic fibers in the second layer 4S was changed. As the absorbing polymer, absorbing polymer A was used, similarly to Example 7.

In particular, the second layer 4S of the absorbent element in the dry state had a content (bulk) of the absorbent polymer constituting (component) 190 g / m ² , a content (bulk) of hydrophilic fibers constituting (constituent) 90 g / m ² , and weight the ratio of the absorbing polymer and hydrophilic fibers (weight of the absorbing polymer / weight of hydrophilic fibers) is 2.11.

The third layer 4T of the absorbent element in the dry state had an absorbent polymer content (bulk) of 10 g / m ² , a hydrophilic fiber content (main mass) of 60 g / m ² , and a weight ratio of absorbent polymer and hydrophilic fibers (weight of absorbent polymer / weight of hydrophilic fibers) of 0.17.

In the state before absorption, the thickness of the absorbing element was 5.5 mm, and the depth of the recessed sections 44 was 3.2 mm, and this value was 58% of the thickness of the absorbing element. In the state after absorption (5 minutes after adding an aqueous solution of sodium chloride with a concentration of 0.9 weight percent in an amount of 2000 g / m ² ) the thickness of the absorbing element was 8.3 mm, and the depth of the recessed sections 44 was 5.6 mm, this value was 67% of the thickness of the absorbing element.

Comparative Example 1

The absorbent element according to Comparative Example 1 was manufactured in the same manner as in Example 1, except for changing the weight ratios of the absorbing polymer and hydrophilic fibers in the first layer 4F and the second layer 4S. As the absorbing polymer, absorbing polymer A was used, similarly to Example 1.

In particular, the first layer 4F of the absorbent element in a dry state had an absorbent polymer content (bulk) of (g) 150 g / m ² , a hydrophilic fiber content (gross) of (g) 50 g / m ² , and a weight the ratio of the absorbing polymer and hydrophilic fibers (weight of the absorbing polymer / weight of hydrophilic fibers) of 3.0.

The second layer 4S of the absorbing element in the dry state had a content (bulk) of the absorbent polymer constituting (constituent) 80 g / m ² , a content (main mass) of hydrophilic fibers constituting (constituent) 150 g / m ² , and a weight ratio of the absorbing polymer and hydrophilic fibers (weight of absorbent polymer / weight of hydrophilic fibers) of 0.53.

In the state before absorption, the thickness of the absorbing element was 4.2 mm, and the depth of the recessed portions was 2.0 mm, and this value was 48% of the thickness of the absorbing element.

In the state after absorption (5 minutes after adding an aqueous solution of sodium chloride with a concentration of 0.9 weight percent in an amount of 2000 g / m ² ), the thickness of the absorbing element was 8.5 mm, and the depth of the recessed sections was 1.5 mm, while this value was 18% of the thickness of the absorbing element. Recessed areas did not pass through the thickness of the second layer.

Reference Example 2

The absorbent element according to Comparative Example 2 was manufactured in the same manner as in Example 1, except for changing the weight ratios of the absorbing polymer and hydrophilic fibers in the first layer 4F and the second layer 4S and changing the thickness of the absorbing element and the depth of the recessed portions. As the absorbing polymer, absorbing polymer A was used, similarly to Example 1.

In particular, the first layer 4F of the absorbent element in the dry state had an absorbent polymer content (bulk) of (g) 80 g / m ² , a hydrophilic fiber content (bulk) of (g) 50 g / m ² , and a weight the ratio of the absorbing polymer and hydrophilic fibers (weight of the absorbing polymer / weight of hydrophilic fibers) of 1.6.

The second layer 4S of the absorbent element in a dry state had a content (bulk) of the absorbent polymer constituting (constituent) 120 g / m ² , a content (main mass) of hydrophilic fibers constituting (constituent) 100 g / m ² , and a weight ratio of the absorbing polymer and hydrophilic fibers (weight of the absorbing polymer / weight of hydrophilic fibers) of 1.2.

In the state before absorption, the thickness of the absorbing element was 3.5 mm, and the depth of the recessed sections was 0.5 mm, while this value was 14% of the thickness of the absorbing element.

In the state after absorption (5 minutes after adding an aqueous solution of sodium chloride with a concentration of 0.9 weight percent in an amount of 2000 g / m ² ), the thickness of the absorbing element was 7.0 mm and the depth of the recessed sections was 1.0 mm, while this value was 14% of the thickness of the absorbing element. Recessed areas did not pass through the thickness of the second layer.

Reference Example 3

The absorbent element according to Comparative Example 3 was made in the same manner as in Example 7, except for changing the weight ratios of the absorbing polymer and hydrophilic fibers in the first layer 4F and the second layer 4S. As the absorbing polymer, absorbing polymer A was used, similarly to Example 7.

In particular, the first layer 4F of the absorbent element in the dry state had an absorbent polymer content (bulk) of (g) 160 g / m ² , a hydrophilic fiber content (gross) of (g) 80 g / m ² , and weight the ratio of the absorbing polymer and hydrophilic fibers (weight of the absorbing polymer / weight of hydrophilic fibers) of 2.0.

The second layer 4S of the absorbent element in the dry state had a content (bulk) of the absorbent polymer constituting (constituent) 100 g / m ² , a content (main mass) of hydrophilic fibers constituting (constituent) 150 g / m ² , and a weight ratio of the absorbing polymer and hydrophilic fibers (weight of absorbent polymer / weight of hydrophilic fibers) of 0.67.

In the state before absorption, the thickness of the absorbing element was 5.5 mm, and the depth of the recessed sections was 2.2 mm, while this value was 40% of the thickness of the absorbing element.

In the state after absorption (5 minutes after adding an aqueous solution of sodium chloride with a concentration of 0.9 weight percent in an amount of 2000 g / m ² ) the thickness of the absorbing element was 7.2 mm and the depth of the recessed sections was 1.4 mm, while this value was 19% of the thickness of the absorbing element. Recessed areas did not pass through the thickness of the second layer.

Rating features:

Absorbent articles were manufactured using absorbent elements according to Examples 1-9 and Comparative Examples 1-3 in accordance with the method below. Absorbent articles were evaluated for liquid spreading and rewet characteristics. The assessment was carried out in an environment with a temperature of 20 ° C and a relative humidity of 60%. The results obtained are shown in table 1.

Production of an absorbent product:

Each of the absorbent elements according to Examples 1-9 and Comparative Examples 1-3 was wrapped in thin paper having a bulk of 16 g / m ² with hot-melt adhesive, applied to the thin paper. Hot-melt solvent-free adhesive was melted with an iron to hold the absorbent element and tissue paper together. A wrapped absorbent element was placed between the top sheet and the back sheet with a side having recessed portions that was facing the back sheet to make the absorbent article. The top sheet and back sheet used in Merries products (trade name) from Kao Corp. were used.

(1) Evaluation of the characteristics of the liquid spreading

An absorbent article made using each of the absorbent elements according to Examples 1-9 and Comparative Examples 1-3 was placed on a smooth horizontal surface of a glass plate. A cylinder with an inner diameter of 35 mm was installed in the middle in the transverse direction and at a distance from the front end of the absorbing element of 200 mm. A 40 g portion of an aqueous sodium chloride solution with a concentration of 0.9 weight percent was poured while holding the liquid at a height of 10 mm. Ten minutes after the start of absorption, another part with a weight of 40 g was poured. The pouring operation was repeated 4 times to pour just 160 g of an aqueous solution of sodium chloride. Ten minutes after the start of the fourth pouring, the liquid spreading area was measured. The liquid spreading characteristics were evaluated as follows based on the liquid spreading area:

A: The spreading area of the liquid in the absorbent element is 270 cm ² or more.

B: The area of liquid spreading in the absorbent element is 250 cm ² or more and less than 270 cm ² .

C: The spreading area of the liquid in the absorbent element is less than 250 cm ² .

(2) Evaluation of re-wetting

An absorbent article made using each of the absorbent elements of Examples 1-9 and Comparative Examples 1-3 was placed on a smooth horizontal surface of a glass plate. A cylinder with an inner diameter of 35 mm was installed in the middle in the transverse direction and at a distance from the front end of the absorbing element of 150 mm. A load of 2.0 kPa was applied to the entire absorbent article, and a portion of an aqueous solution of sodium chloride with a concentration of 0.9 weight percent having a mass of 40 g was poured while holding the liquid at a height of 10 mm. Ten minutes after the start of absorption, another part with a weight of 40 g was poured. The pouring operation was repeated 4 times to pour just 160 g of an aqueous solution of sodium chloride. Ten minutes after the start of the fourth pouring, a stack of 10 cut sheets (100 mm  100 mm) of filter paper (No. 4A, supplied by Advantech Tokyo Kaisha, Ltd.) was placed on the absorbent element, while the center of this foot was aligned with the pouring place . A load of 3.5 kPa was applied to it by means of an acrylic resin plate measuring 100 mm per 100 mm. After a time of application of a load of 2 minutes, the weight (W2) of the filter paper was measured, and the value characterizing re-wetting was calculated by the formula below. The re-wetting characteristics were evaluated based on the re-wetting value in accordance with the rating system below.

The value characterizing re-wetting (g) = the mass of filter paper after applying the load (W2) - the initial mass of filter paper (W1)

A: The value characterizing re-wetting is less than 0.2 g.

B: The value characterizing re-wetting is 0.2 g or more and less than 1.0 g.

C: The value characterizing re-wetting is 1.0 g or more and less than 1.5 g.

D: The value characterizing re-wetting is 1.5 g or more.

(3) Estimation of absorption time

In the rewetting test described above, the time required for the absorbing element to fully absorb the liquid poured in the fourth pouring was recorded. The recorded absorption time was evaluated as follows. The shorter the required absorption time was, the better this characteristic was considered.

A: The absorption time is less than 80 seconds.

B: The absorption time is 80 seconds or more and less than 120 seconds.

C: The absorption time is 120 seconds or more and less than 180 seconds.

D: The absorption time is 180 seconds or more.

Table 1-1 unit of measurement Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Reference Example 2 Used absorbent polymer polymer A polymer B polymer C polymer A polymer A polymer A polymer A polymer A Absorbing element 1st layer Absorbing polymer (p) g / m ² 80 80 80 110 110 80 150 80 Hydrophilic fiber (f) g / m ² fifty fifty fifty 80 80 fifty fifty fifty p / f - 1,6 1,6 1,6 1.38 1.38 1,6 3.0 1,6 2nd layer Absorbing polymer (p) g / m ² 180 180 180 140 140 170 80 120 Hydrophilic fiber (f) g / m ² 150 150 150 120 120 90 150 one hundred p / f - 1,2 1,2 1,2 1.17 1.17 1.89 0.53 1,2 3rd layer Absorbing polymer (p) g / m ² - - - - - 10 - - Hydrophilic fiber (f) g / m ² - - - - - 60 - - p / f - - - - - - 0.17 - - After absorption The thickness of the absorbing element (t1) mm 9.5 10,2 9.1 8.8 8.8 9.2 8.5 7.0 Depth of Depth (d1) mm 7.0 7.5 6.7 5,0 5,0 6.7 1,5 1,0 d1 × 100 / t1 % 74 74 74 57 57 73 eighteen fourteen Before takeover The thickness of the absorbing element (t2) mm 5,0 5,0 5,0 4,5 3.0 5.2 4.2 3,5 Depth of Depth (d2) mm 3,5 3,5 3,5 2,3 0.5 3,7 2.0 0.5 d2 × 100 / t2 % 70 70 70 51 17 71 48 fourteen Evaluation results Liquid spreading characteristic - BUT BUT BUT AT AT BUT FROM FROM Re-wetting - BUT BUT AT AT AT BUT D FROM Absorption time - BUT FROM AT AT FROM BUT FROM D

Table 1-2 (continued) unit of measurement Example 7 Example 8 Example 9 Reference Example 3 Used absorbent polymer polymer A polymer A polymer A polymer A Absorbing element 1st layer Absorbing polymer (p) g / m ² one hundred 125 one hundred 160 Hydrophilic fiber (f) g / m ² 80 one hundred 80 80 p / f - 1.25 1.25 1.25 2.0 2nd layer Absorbing polymer (p) g / m ² 200 160 190 one hundred Hydrophilic fiber (f) g / m ² 150 125 90 150 p / f - 1.33 1.28 2.11 0.67 3rd layer Absorbing polymer (p) g / m ² - - 10 - Hydrophilic fiber (f) g / m ² - - 60 - p / f - - - 0.17 - After absorption The thickness of the absorbing element (t1) mm 8.5 7.8 8.3 7.2 Depth of Depth (d1) mm 5.8 4,5 5,6 1.4 d1 × 100 / t1 % 68 58 67 19 Before takeover The thickness of the absorbing element (t2) mm 5.5 3,5 5.5 5.5 Depth of Depth (d2) mm 3.2 0.5 3.2 2.2 d2100 / t2 % 58 fourteen 58 40 Evaluation results Liquid spreading characteristic - BUT AT BUT FROM Re-wetting - AT AT AT D Absorption time - AT FROM AT FROM

As is evident from the results shown in Table 1, absorbent articles having absorbent elements according to Examples 1-9 have better liquid spreading characteristics compared to absorbent articles having absorbent elements according to Comparative Examples 1-3. In addition, absorbent articles having absorbent elements according to Examples 1-9 exhibit shorter absorption times, reduced re-wetting, i.e. better re-wetting characteristics, compared to absorbent articles having absorbent elements according to Comparative Examples 1-3. Thus, it is expected that absorbent articles having absorbent elements according to Examples 1-9 will provide increased dryness and increased comfort for the user.

INDUSTRIAL APPLICABILITY

The absorbent element according to the invention is able to preserve spaces after absorption of the fluid released by the body, has a short absorption time, and it is expected that the absorbent element according to the invention will have sufficient liquid spreading characteristics. The absorbent element according to the invention is intended to be blocked due to gel formation in a reliable manner, so that the blocking phenomenon due to gel formation will be effectively used to reduce re-wetting in the inlet area of the fluid released by the body and to increase dryness.

Claims (19)

1. An absorbent element comprising an absorbent polymer and hydrophilic fibers and having a first layer, a second layer and a third layer,
wherein the first layer has a weight ratio of polymer to hydrophilic fibers (polymer weight / weight of hydrophilic fibers) of 1 or more, and the second layer has a higher absorption polymer content and a higher content of hydrophilic fibers compared to the first layer,
the third layer has a lower content of the absorbing polymer and a lower content of hydrophilic fibers in comparison with the second layer, while in the third layer the weight ratio of the absorbing polymer and hydrophilic fibers (weight of the absorbing polymer / weight of hydrophilic fibers) is 0.5 or less
the first layer, the second layer and the third layer are continuous in the thickness direction, and
the absorbing element has a recessed section passing through the thickness of the second layer and the third layer in a state five minutes after adding an aqueous solution of sodium chloride with a concentration of 0.9 weight percent in an amount of 2000 g / m ² . 2. The absorbent element according to claim 1, having a recessed section and a protruding section bounded by a recessed section, wherein the bulk and density of the absorbing material of the recessed section are equal to or less than the bulk and density of the absorbing material of the protruding section. 3. The absorbent element according to claim 1, having a recessed portion extending through the thickness of the second layer, before adding an aqueous solution of sodium chloride. 4. The absorbent element according to claim 1, wherein the second layer has a weight ratio of absorbent polymer to hydrophilic fibers (weight of absorbent polymer / weight of hydrophilic fibers) of 1 or more. 5. The absorbing element according to claim 1, in which the recessed portion has a depth of 20% to 100% of the thickness of the absorbing element in the state before absorption. 6. The absorbent element according to claim 2, in which the recessed portion has a bulk of 0% to 80% of the protruding portion. 7. The absorbent element according to claim 1, having a thickness of from 0.5 to 20 mm in the state before absorption. 8. The absorbing element according to claim 1, in which the absorbing polymer has an absorption capacity of 30 to 50 g / g, absorption capacity under a load of 2.0 kPa, 20 to 40 g / g, and a liquid a load of 2 kPa of less than 1 ml / min; and an absorption rate determined by the DW method of 40 to 60 ml / (g · 10 min). 9. The absorption element according to claim 1, wherein the absorption polymer has an absorption rate determined by the DW method of 5 to 13 ml / (g · 1 min). 10. The absorption element according to claim 1, in which the ratio of the main mass of the absorbing polymer of the second layer and the main mass of the absorbing polymer of the first layer (second layer / first layer) is 1.6 or more. 11. The absorbent element according to claim 1, wherein the ratio of the bulk of the absorbent polymer of the second layer to the bulk of the absorbent polymer of the first layer (second layer / first layer) is 2.5 or less. 12. The absorbent element according to claim 1, wherein the difference between the bulk of the absorbent polymer of the first layer and the bulk of the absorbent polymer of the second layer (second layer is the first layer) is 45 g / cm ² or more. 13. The absorption element according to claim 1, wherein the difference between the bulk of the absorbent polymer of the first layer and the bulk of the absorbent polymer of the second layer (second layer is the first layer) is 150 g / cm ² or less. 14. An absorbent article comprising a top sheet located on the side facing the skin, a back sheet located on the side not facing the skin, and an absorbent member according to claim 1, located between the top sheet and the back sheet. 15. The absorbent product according to claim 14, in which the second layer is located on the side of the first layer facing the skin, and
the recessed portion is recessed from the side of the top sheet toward the side of the back sheet. 16. An absorbent product according to claim 14, in which the second layer is located on the side of the first layer, not facing the skin, and
the recessed portion is recessed from the side of the back sheet toward the side of the top sheet. 17. The absorbent article of claim 14, further comprising a hydrophilic intermediate sheet located between the absorbent member and the top sheet. 18. The absorbent article of claim 14, further comprising a hydrophilic intermediate sheet located between the absorbent member and the back sheet. 19. An absorbent product according to claim 17 or 18, in which the recessed portion and the intermediate sheet form a space between themselves.

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