JP2003033396A - Disposable diaper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disposable diaper which prevents a wearer from strong wet feeling even at the moment immediately after urination to the disposable diaper. SOLUTION: This disposable diaper 1 has a contact face to the skin of a diaper wearer and another contact face to a wear. A surface sheet 2 providing the contact face to the skin has therein a body fluid-absorbing core 4. The core 4 has in the thickness direction thereof a first absorption layer 21, a second absorption layer 23, and a third absorption layer 22 in sequence. In a crotch area 8 of the diaper 1, the first absorption layer 21 and the third absorption layer 22 have the same width and the second absorption layer 23 has a width which is 1/3 to 2/3 of the above width. The second absorption layer 23 has second high absorption polymer grains 42 whose water absorption time is shorter than that of first high absorption polymer grains 27 and whose water retension magnification is lower than that of the grains 27 which grains are included in the first absorption layer 21 and the third absorption layer 23.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a disposable diaper.

[0002]

2. Description of the Related Art A disposable diaper disclosed in Japanese Patent Laid-Open No. 63-256701 has an absorbent body between a surface non-woven fabric which comes into contact with the skin of a diaper wearer and a polyethylene sheet which comes into contact with clothes. This absorber is one in which the polymer layer and the pulp layer are in a laminated state, immediately below the surface nonwoven fabric, a pulp layer and a layer of polymer powder having a slow absorption rate and strong gel strength are formed in order from top to bottom, Immediately above the polyethylene sheet, a pulp layer and a layer of polymer powder having a high absorption rate and a low gel strength are formed in order from top to bottom.

[0003]

In the diaper of the prior art described above, since the pulp layer and the polymer powder layer having a slow absorption rate are located in the vicinity of the wearer's skin, the urine absorbed in the pulp layer. Is not immediately absorbed by the layer of polymer powder immediately below, and as a result tends to stay near the skin. In such a diaper in which a polymer powder having a low absorption rate is placed in the vicinity of the skin, the diaper wearer often has a strong feeling of wetness immediately after urination. When the disposable diaper is for adults in particular, the amount of urine discharged once is large, and if the urine is not absorbed promptly, a strong sensation of moistening is given to the diaper wearer for a long time.

The present invention relates to improvement of a disposable diaper using superabsorbent polymer particles, and an object thereof is to provide a disposable diaper capable of giving a so-called dry feeling without giving a strong wet feeling immediately after urination. I have to.

[0005]

In order to solve the above problems, the present invention is intended to have a skin contact surface and a clothes contact surface, and the length direction of the skin contact surface is the front waist circumference. A disposable diaper in which a body fluid absorbent core is provided inside a liquid-permeable surface sheet that forms a skin contact surface and that comprises a region, a back waist region, and a crotch region located between these regions.

The features of the present invention in such a disposable diaper are as follows. The core has a first absorbent layer, a second absorbent layer, and a third absorbent layer in the thickness direction of the core from the skin contact surface to the clothing contact surface. The first absorbent layer is an absorbent comprising any of upper tissue paper in contact with the surface sheet, upper pulverized pulp in contact with the upper tissue paper from below, and a mixture of upper pulverized pulp and first superabsorbent polymer particles. Material, the second absorbent layer includes second superabsorbent polymer particles distributed adjacent to each other to the extent that a gel block can be formed when absorbing water, and the third absorbent layer includes a lower pulverized pulp and the first crushed pulp. Including a mixture with superabsorbent polymer particles. The first superabsorbent polymer particles have a water absorption time of 30 seconds or more and 3
While having a water retention capacity of 5 g / g or more, the second superabsorbent polymer particles have a water absorption time of 25 seconds or less and 35 g / g.
It has the following water retention ratio. In the crotch region and its vicinity, the widths of the first absorbent layer and the third absorbent layer are substantially the same, and the second absorbent layer is 1/3 of the width of these first and third absorbent layers. Has a width of ⅔ and is located in the central portion in the width direction of these first and third absorption layers,
The third absorbent layer is overlapped with the outer sides of both sides of the second absorbent layer.

The present invention has the following preferred embodiments. (1) Almost all of the absorbent material is covered with the upper tissue paper. (2) The third absorbent layer is entirely covered with tissue paper. (3) The second absorbent layer is located between the upper tissue paper and the tissue paper covering the third absorbent layer. (4) The second absorbent layer is located between the absorbent material and tissue paper that covers the third absorbent layer. (5) The second absorption layer is located between the third absorption layer and tissue paper that covers the third absorption layer.

In the present invention, the water absorption time of superabsorbent polymer particles such as the first and second superabsorbent polymer particles is measured as follows. 5 in a 100 ml beaker
While stirring 0 g of 0.9% saline, 2 g of superabsorbent polymer particles are added thereto. After the addition, stirring is continued, and the time until the liquid surface of the saline solution becomes flat due to the swollen superabsorbent polymer particles is measured, and the time is defined as the water absorption time.

In the present invention, the water retention capacity of the superabsorbent polymer particles is measured as follows. About 1g
The superabsorbent polymer particles of 1 are soaked in 0.9% saline and left for 1 hour. Then, the superabsorbent polymer particles are centrifuged at 850 rpm (150 G) for 90 minutes.
Dehydrate for 2 seconds and determine the weight after dehydration. The ratio of the weight after dehydration to the weight before immersion in the saline solution is calculated and used as the water retention ratio.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The details of the disposable diaper according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a partially cutaway plan view of a disposable diaper 1. The diaper 1 is an open type, and the liquid-permeable surface sheet 2 forms a contact surface with the skin of the wearer of the diaper 1.
And a liquid-impermeable back sheet 3 that forms a contact surface for the wearer's clothes, and a body fluid-absorbent core 4 interposed between these sheets 2 and 3. Front and back sheets 2, 3
Extend from the peripheral edge of the core 4, overlap with each other, and are joined to each other to form front and rear end edge flaps 11 and 12 and side edge flaps 13. The diaper 1 has a front waistline region 6, a back waistline region 7, and a crotch region 8 located between these two regions 6 and 7 in the length direction (vertical direction in the drawing) of the rear torso region. A tape fastener 14 is attached to the side edge flap 13 in the surrounding area 7. Front and rear edge flaps 1
1, 12 and the side edge flap 13 in the crotch region 8, the waist elastic members 15 and 16 and the leg elastic members 17 are attached in an extended state to the inner surfaces of at least one of the front and back sheets 2 and 3. There is.

2 and 3 are lines II-II and I of FIG.
It is drawing which shows the II-III line cut surface. As will be apparent by also referring to FIG. 1, the core 4 is formed in a so-called hourglass shape in which the width is wide in the front and rear waist regions 6, 7 and narrow in the crotch region 8. The core 4 has an upper absorption layer 21 closer to the topsheet 2, a lower absorption layer 22 closer to the backsheet, and an intermediate absorption layer 23 interposed between these layers 21 and 22. The upper absorption layer 21 and the lower absorption layer 22 have the same width and have the hourglass shape. The middle absorbent layer 23 has a width that is 1/3 to 2/3 of the width of the upper and lower absorbent layers 21, 22 in the crotch region 8, and has a substantially uniform width around the front crotch region 8 as a center. It extends to the region 6 and the rear waist region 7. However, front and rear waist area 6,
The width of the intermediate absorption layer 23 in 7 can be made wider or narrower than the width of the crotch region 8.

The upper absorbent layer 21 is composed of an upper crushed pulp 26 or an absorbent material aggregate 28 composed of the mixed upper crushed pulp 26 and the first superabsorbent polymer particles 27, and an upper tissue paper 29. Assembly 28 is top surface 3
1 and the lower surface 32. The upper tissue paper 29
At least the upper surface 31 of the both surfaces 31, 32 is covered and is in contact with the topsheet 2 from below. Assembly 2
8, the ground pulp 26 has a basis weight of 50 to 300 g /
m ² , more preferably used in the range of 150 to 250 g / m ² , the first superabsorbent polymer particles 27 have a basis weight of 0 to
100 g / ^{m 2,} more preferably in the range of 10 to 50 g / ^{m 2.} Such first superabsorbent polymer particles 2
For 7, a polymer having a high water retention capacity of 35 g / g or more is used, and the polymer particles 27 have a long water absorption time of approximately 30 seconds or more. However, the upper absorption layer 21
It is possible to omit the first superabsorbent polymer particles 27 and form only the upper crushed pulp 26.

The lower absorbent layer 22 is an assembly 3 of the mixed lower ground pulp 33 and the first superabsorbent polymer particles 27.
4, the assembly 34 is covered with a lower tissue paper 36 for retaining its shape.
The lower absorbent layer 22 is in contact with the backsheet 3 from above via the lower tissue paper 36. The lower pulverized pulp 33 is used in a range of a basis weight of 150 to 350 g / m ² , more preferably 200 to 300 g / m ² , and the first superabsorbent polymer particles 27 have a basis weight of 40 to 200 g / m ² , more preferably. It is used in the range of 60 to 150 g / m ² .

The middle absorbent layer 23 is formed by the second super absorbent polymer particles 42 and is located immediately below the top of the lower tissue paper 36. The second superabsorbent polymer particles 42 have a short water absorption time of 25 seconds or less,
This has a low water retention capacity of about 35 g / g or less. The second super absorbent polymer particles 42 have a basis weight of 50.
To 200 g / m ² , more preferably 80 to 120 g / m
Used in the range of ² . In the intermediate absorption layer 23, the large number of second superabsorbent polymer particles 42 have a weight of 5-10.
It is preferable that adjacent particles 42 are distributed so as to come into contact with each other to form a gel block when water is absorbed twice. Outside the both side edges of the intermediate absorption layer 23, the upper absorption layer 2
1 and the lower absorption layer 22 are overlapped with each other via the lower tissue paper 36.

In the diaper 1 having the core 4 formed in this way, the urine that has permeated the surface sheet 2 is diffused in a plane in the upper tissue paper 29 of the upper absorbent layer 21, and is further absorbed through the upper crushed pulp 26. Transition below layer 21. The first superabsorbent polymer particles 27 contained in the upper absorbent layer 21 have a slow absorption rate and do not immediately catch excreted urine. In the widthwise central part of the core 4,
Urine from the upper absorption layer 21 is rapidly captured by the second superabsorbent polymer particles 42 having a high absorption rate,
The two swell and come into contact with each other, beginning to form gel blocks. By capturing urine by the polymer particles 42, the core 4
The upper part of the central part becomes dry. On both sides of the core 4,
Urine migrates from the upper absorbent layer 21 to the lower absorbent layer 22, further laterally in the lower absorbent layer 22, and below the intermediate absorbent layer 23. Both side portions of the core 4 are in a dry state as the urine is absorbed by the large amount of upper and lower crushed pulp 26, 33 and moves downward. The urine absorbed by these crushed pulps 26 and 33 is captured by the first superabsorbent polymer particles 27 with the passage of time.

The second super-absorbent polymer particles 42 forming the core 4 have a high water absorption rate of 25 seconds or less, but the polymer particles having such a property saturate in a short time, so that they are repeatedly absorbed. The water retention tends to be poor, and the water retention capacity is generally low. For example, the water retention rate of the second superabsorbent polymer particles 42 having a water absorption rate of 25 seconds or less is about 35.
It is g / g or less. Therefore, if the water-absorbent polymer particles of the core 4 are only the second super-absorbent polymer particles 42 as described above, a large amount of urine cannot be absorbed even if the urine is rapidly absorbed, and the polymer particles 42 are not absorbed. When pressure is applied, the urine located in the vicinity of the superabsorbent polymer particles 42, which cannot be absorbed, is extruded, and a so-called rewet phenomenon occurs to give a diaper wearer a feeling of wetness. However, the first superabsorbent polymer particles 27 having a slow absorption rate of 30 seconds or more are
Generally has a high water retention capacity. For example, the water retention capacity of the first superabsorbent polymer particles 27 having a water absorption rate of 30 seconds or more is approximately 35 g / g or more. In the core 4 in which the first and second superabsorbent polymer particles 27 and 42 are used together, the body pressure acts on the core 4 immediately after the urine is excreted by the cooperation of the polymer particles 27 and 42. By such time, the surface of the core 4 can be kept in a dry state for a long time, and the wearer of the diaper 1 does not feel wet. In particular, when the intermediate absorption layer 23 absorbs urine and forms a gel block, even if the lower absorption layer 22 located below the intermediate absorption layer 23 receives body pressure and releases urine, Can be prevented from seeping out to the surface of the core 4.

The intermediate absorption layer 23 acting in this way is
By being sandwiched between the upper absorption layer 21 and the lower absorption layer 22, urine can be captured from both upper and lower surfaces. The basis weight of the second superabsorbent polymer particles 42 in the absorbent layer 23 is such that almost all of the second superabsorbent polymer particles 42 are consumed when both surfaces thereof are gel-blocked, and most of the urine is still absorbed between the two surfaces. It is set up so that there is nothing left over.

FIG. 4 is a drawing similar to FIG. 2 showing an example of the embodiment of the present invention. Core 4 in this diaper 1
Then, the intermediate absorption layer 23 made of the second superabsorbent polymer particles 42 is formed between the lower surface 32 of the upper absorption layer 21 and the lower tissue paper 36. Such core 4
The urine diffused in the lower tissue paper 36 can be captured on the lower surface side of the intermediate absorption layer 23. When the lower tissue paper 36 having good diffusibility is brought into contact with the intermediate absorption layer 23 in this manner, urine that goes downward outside the side edge of the intermediate absorption layer 23 is quickly captured by the lower surface of the intermediate absorption layer 23. can do.

FIG. 5 is also a drawing similar to FIG. 2 showing an example of the embodiment of the present invention. In the core 4 of the diaper 1, the aggregate 28 of the upper absorbent layer 21 is covered with the upper tissue paper 29, and the intermediate absorbent layer 23 is located between the upper tissue paper 29 and the lower tissue paper 36. By sandwiching the intermediate absorption layer 23 between the tissue papers 29 and 36 having good diffusibility, the absorption layer 23
The urine is quickly supplied to the upper and lower surfaces.

[0021]

EFFECTS OF THE INVENTION The body fluid absorbent core of the disposable diaper according to the present invention comprises a second super absorbent polymer particle having a high water absorption rate but a low water retention rate and a first super absorbent polymer particle having a low water absorption rate but a high water retention rate.
In combination with the superabsorbent polymer particles, the second superabsorbent polymer particles are densely arranged near the skin contact surface in the crotch region of the diaper, and the first superabsorbent polymer particles are provided below the second superabsorbent polymer particles. The diaper does not give the diaper wearer a strong sense of dampness even if a large amount of urine is excreted at one time.

[Brief description of drawings]

FIG. 1 is a partially cutaway plan view of a disposable diaper.

FIG. 2 is a view showing a cross section taken along line II-II of FIG.

FIG. 3 is a view showing a cross section taken along line III-III of FIG.

FIG. 4 is a drawing similar to FIG. 2 showing an example of an embodiment.

FIG. 5 is a drawing similar to FIG. 2, showing another example of the embodiment.

[Explanation of symbols]

1 disposable diapers 2 Top sheet 4 core 6 front waist area 7 Rear waist area 8 inseam 21 1st absorption layer (upper absorption layer) 22 3rd absorption layer (lower absorption layer) 23 Second Absorption Layer (Middle Absorption Layer) 26 Upper crushed pulp 27 First super absorbent polymer particles 29 Upper tissue paper 33 Lower ground pulp 36 Lower tissue paper 42 Second super absorbent polymer particles

Continued front page    (72) Inventor Katsumi Mizutani             1531-7 Wadahama Takasuka, Toyohama Town, Mitoyo District, Kagawa Prefecture               Unicharm Corporation Technical Sen             Inside F term (reference) 3B029 BA05 BA15                 4C098 AA09 CC03 CE06 DD05 DD06                       DD23

Claims (6)

[Claims] 1. A skin contacting surface and a clothing contacting surface, wherein the skin contacting surface comprises a front waistline region, a back waistline region, and a crotch region located between these two regions. A disposable diaper in which a bodily fluid-absorbent core is provided inside a liquid-permeable surface sheet that forms a skin-contacting surface, wherein the core is first in a thickness direction of the core from the skin-contacting surface toward the clothing-contacting surface. An upper tissue paper having an absorbent layer, a second absorbent layer, and a third absorbent layer, the first absorbent layer contacting the surface sheet, and upper crushed pulp and upper crushed pulp contacting the upper tissue paper from below. Second superabsorbent polymer particles, which comprises an absorbent made of any one of a mixture with the first superabsorbent polymer particles and is distributed adjacent to each other to the extent that the second absorbent layer can form a gel block when absorbing water. Including the third absorption layer Comprising a mixture of lower ground pulp and the first superabsorbent polymer particles, wherein the first superabsorbent polymer particles have a water absorption time of 30 seconds or more and a water retention ratio of 35 g / g or more, while the second high Absorbing polymer particles have a water absorption time of 25 seconds or less and 35 g /
g has a water retention ratio of g or less, the width of the first absorbent layer and the third absorbent layer are substantially the same in the crotch region and its vicinity, and the second absorbent layer is It has a width of ⅓ to ⅔ of the width of the third absorption layer, and is located in the central portion in the width direction of these first and third absorption layers,
The disposable diaper characterized in that the third absorbent layer is overlapped with the outer side edges of the second absorbent layer. 2. The disposable diaper according to claim 1, wherein substantially the entire absorbent material is covered with the upper tissue paper. 3. The disposable diaper according to claim 1, wherein the third absorbent layer is entirely covered with tissue paper. 4. The disposable diaper according to claim 1, wherein the second absorbent layer is located between the upper tissue paper and the tissue paper covering the third absorbent layer. 5. The second absorbent layer comprises the absorbent material and the third absorbent material.
The disposable diaper according to any one of claims 1 to 3, which is located between a tissue paper covering the absorbent layer. 6. The disposable diaper according to claim 1, wherein the second absorbent layer is located between the third absorbent layer and tissue paper covering the third absorbent layer.