JP3222494B2 - Absorbent articles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to absorbent articles such as disposable diapers for infants, adults and incontinent persons, and sanitary napkins for women.

[0002]

2. Description of the Related Art Conventionally, there have been proposed many techniques relating to improvements in diffusivity, flexibility, thinness, etc. of absorbent articles used for sanitary napkins, disposable diapers and the like.
For example, Japanese Patent Publication No. 52-41999 discloses a technique for providing a novel absorbent, and Japanese Patent Publication No. 52-44154 discloses a technique for obtaining a thin absorber by using a predetermined compression body. ing.

Further, Japanese Patent Application Laid-Open No. 61-191359 discloses an absorber for improving liquid diffusivity by embossing cotton wool. Further, Japanese Unexamined Patent Publication No.
-85943, JP-A-61-85944,
Japanese Patent Application Laid-Open No. 2-1137 discloses a technique of an absorber having a flexibility by using a material having a predetermined composition in order to fit the crotch.

[0004]

However, the above-mentioned thin absorbers of the prior art certainly have excellent simplicity and compactness due to their characteristics, but have a problem of poor absorption. Further, the conventional absorbent having liquid diffusibility is excellent in preventing so-called lateral leakage, but has a problem in that it is inferior in absorbency and workability.

[0005] Furthermore, the conventional absorbent body having flexibility is excellent in the fit between the inseams, but has a problem that the liquid diffusibility and the absorbability are not sufficient. That is, according to the above-mentioned prior art, there is a problem in that an absorbent article that sufficiently satisfies the three requirements of excellent liquid diffusivity and liquid returnability and excellent fit cannot be obtained.

[0006] Accordingly, an object of the present invention is to provide an absorbent article which sufficiently satisfies the three requirements of excellent liquid diffusivity and liquid return properties and excellent fit.

[0007]

SUMMARY OF THE INVENTION The present invention relates to an absorbent article comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorber disposed between the two sheets. The body is composed of an aggregate of fibers and is composed of two layers, an upper layer on the top sheet side and a lower layer on the back sheet side, wherein the upper layer is hydrophilic, and the lower layer is a liquid.
A retention, the upper layer has a non-existent gap portion of each successive tubular fiber spreading direction of the overlapping direction and a layer of the upper layer and the lower layer, the diameter of the air gap in the overlapping direction of the layer Has a peak in the range of 200 μm to 1000 μm, and the distribution of the diameter of the void in the direction in which the layer spreads is 10 μm.
The above object has been achieved by providing an absorbent article having a peak at 0 μm or less and the lower layer having a physiological saline absorption capacity of 100 g / 100 cm ² or more.

[0008] The distribution of the diameter of the voids in the direction of layer overlap is 2
The reason for having a peak between 00 μm and 1000 μm is that if it is smaller than 200 μm, the flow path of the liquid in the gap is too narrow to obtain a sufficient amount of liquid absorption, and if it is larger than 1000 μm, This is because the passage is too wide and the liquid returns. The reason that the distribution of the diameter of the voids in the layer spreading direction is limited to have a peak at 100 μm or less is that the voids in the layer spreading direction are 100 μm or less.
If it is larger, sufficient diffusion of the liquid by the capillary force cannot be obtained in the void.

The absorption capacity of the lower physiological saline is 10
The reason why the amount is set to 0 g / 100 cm ² or more is that if the amount is less than 0 g / 100 cm ^{2, the} liquid absorption by the lower layer cannot be sufficiently achieved.

[0010]

According to the absorbent article of the present invention, the liquid such as body fluid on the top sheet side of the absorber is absorbed by the upper layer of the hydrophilic absorber. Since a predetermined gap is formed in the upper layer of the absorber, the liquid is quickly diffused and transferred by the gap in the entire spreading direction of the upper layer and the entire overlapping direction. Therefore, the liquid on the top sheet side is quickly absorbed by the upper layer of the absorber and moves to the lower layer side.

In the upper layer, the liquid which has moved in the direction in which the layers are overlapped is absorbed and held in the lower layer, so that the once absorbed liquid is prevented from returning and leaking. Further, in the upper layer, a void having a predetermined cylindrical diameter is formed, so that diffusion and absorption of the liquid absorbed by the void can be performed at a high speed and reliably.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, a disposable diaper will be described as an example of an absorbent article. As shown in FIG. 2, the disposable diaper 1 includes a main body 5 having a liquid-permeable top sheet 2, a liquid-permeable back sheet 3, and an absorber 4 disposed between these two sheets. Is divided into a wearer's abdomen 6 and a back 7 when worn ,
The back part 7 is provided with a pair of tape fasteners 8, and is fixedly mounted on the back sheet side of the abdomen part 6. Further, the main body 5 is provided with an elastic member 9 along the side edge thereof so as to form a leg gather so as to fit around the leg when worn.

The absorbent article 4 of the absorbent article according to this embodiment is
As shown in FIG. 1, the upper layer 4a is composed of an upper layer 4a on the top sheet 2 side and a lower layer 4b on the back sheet 3 side. The upper layer 4a is hydrophilic and the lower layer 4b is
The upper layer is a uniform cylindrical void portion 1 which is continuous in the direction in which the two layers overlap and the direction in which the layers spread.
As shown in FIG. 1, these gaps 11 and 12 have a gap 11 and a gap 12 in the direction in which the upper and lower layers overlap and spread.
Are continuously extended like a mesh.

The cylindrical diameter of the void portion 11 in the layer overlapping direction is 200 μm to 1000 μm, preferably 200 μm to 500 μm, and in this embodiment 250 μm.
m to 350 μm. As shown in FIG. 2, the voids 12 extending in the direction in which the layers extend are two-dimensionally extended in the vertical and horizontal directions, and the cylindrical diameter of the horizontal voids 12 a is the same as that of the vertical voids 12 b. In this embodiment, the cylindrical diameter of the vertical gap 12b is 10 μm to 2 μm.
0 μm, and the cylindrical diameter of the lateral gap 11 is 30 μm.
m to 40 μm.

Here, the vertical direction refers to the longitudinal direction of the absorbent article 4, and the horizontal direction refers to the width direction of the absorbent body of the absorbent article 4. As described above, by making the cylindrical diameter of the horizontal void portion 12b larger than the vertical cylindrical diameter, it is possible to obtain the effect of controlling liquid diffusion in the absorber width direction and preventing lateral leakage.

For the upper layer 4a, hydrophilic fibers are used, and if the fibers have such properties, the liquid on the top sheet side is easily absorbed, and the absorption speed can be increased. As the hydrophilic fibers of the upper layer 4a, defibrated pulp, cellulosic fibers,
Alternatively, thermoplastic fibers such as polyamide fibers and polyester fibers that have been subjected to a hydrophilic treatment are used.

The thickness of the upper layer 4a satisfies the following equation. (Thickness under pressure when wet / thickness when dry)> 0.5 The thickness under pressure when wet is 5% after saturation with physiological saline.
The thickness when pressed at 0 g / cm ² . In the above formula, (thickness under pressure when wet / thickness when dry) is preferably 0.
6 or more, and 0.8 in this embodiment.

(Thickness under pressure when wet / thickness when dry)
Has a thickness satisfying such a value,
A so-called thin absorber can be obtained. Such a thin absorbent body is excellent in simplicity and compactness as an absorbent body, and can also enhance the fit to a diaper wearer. The density of the upper layer is 0.1 to 0.5 g / cm ³ .

The overall thickness of the absorber 4 in which the upper layer 4a and the lower layer 4b are overlapped with each other is such that when the absorber is dried,
It is 6 mm or less, preferably 5 mm to 3 mm, and in this embodiment, 3 mm to 4 mm. The lower layer 4b has a physiological saline absorption capacity of 100 g / 100 cm ² or more, preferably 100 g / 100 cm ^{2 to} 160 g / 100 cm ² ,
In this embodiment, 100 g / 100 cm ^{2 to} 130 g / 10
0 cm ² .

The material used for the lower layer 4b is preferably a combination of a hydrophilic fiber and a polymer water-absorbing polymer.
The hydrophilic fibers are particularly preferably defibrated pulp, cellulosic fibers, or those obtained by hydrophilizing thermoplastic fibers, and the polymer water-absorbing polymer is a saponified product of a starch-acrylic acid (salt) graft copolymer. , A crosslinked product of sodium carboxymethyl cellulose, an acrylic acid (salt) polymer and the like are particularly preferred. In this embodiment, defibrated pulp and acrylic acid (salt) polymer are used.

Needless to say, the upper layer and the lower layer are not limited to different materials, and the same effect can be obtained even with the same material. Next, the operation of the present embodiment will be described. In the disposable diaper 1 as an absorbent article according to the present embodiment, the liquid absorbed from the liquid-permeable surface material is first absorbed by the upper layer 4a. Since the upper layer 4a is made of a hydrophilic material, it has excellent wetting characteristics, and the fiber space diameter does not decrease over time and the absorption rate does not decrease.

In the upper layer 4a, the liquid diffuses and moves vertically and horizontally at a high speed in the gap 11 in the layer overlapping direction and in the gap 12 in the layer spreading direction. Thereby, the liquid on the top sheet 2 side is quickly absorbed. Further, the liquid diffused in the upper layer 4a is mainly absorbed and held in the lower layer 4b via the voids 11 in the direction in which the layers overlap. Therefore, the upper layer 4a
Since the liquid moves to the lower layer 4b, the upper layer 4a does not lose its function continuously, and the absorption rate does not decrease even after a lapse of time.

In the following, specific examples and comparative examples are listed together with their comparative experiments and their results to clarify the effects of the present invention. Example 1 In the upper layer, a nylon fiber having a diameter of 9 μm was twisted into a weft yarn having a diameter of 400 μm, and a polyester fiber having a diameter of 20 μm was twisted into a warp yarn having a diameter of 500 μm. The lower layer is made of acrylic acid polymer powder 190 g / m ² , pulp 13
Using a mixture obtained by uniformly mixing 0 g / m ² , they were integrally joined to form an absorber.

Example 2 Cellulose fibers made of viscose pulp, spunbond nonwoven fabric (basis weight 30 g /
m ² ) was used, and as the lower layer, an acrylic acid polymer powder of 190 g / m ² was uniformly mixed, and these were integrally joined to form an absorber.

COMPARATIVE EXAMPLE Pulp having a basis weight of 200 g / m ² was 300 (width) × 410.
(Length) x 5 (thickness) mm, 5 g of acrylic acid polymer powder on the center surface is 150 (width) x 410 (length) mm
, And then folded back inward on both sides to the center to form an absorbent body overlapping each other.

The following experiments were conducted on the products of Examples and Comparative Examples according to the above Examples and Comparative Examples. The results are shown in Table 1 below.

[0027]

[Table 1] Here, each measurement item in the above table will be described.

Absorbent Absorption Time A sample is placed on a plane, a petri dish having five holes (diameter 3 mm) is placed at the bottom of the center of the sample, and a load of 80 is applied to the petri dish.
g, 150 g of physiological saline was injected at a time, and the time until all the liquid was absorbed was defined as 0 when the physiological saline was put in the petri dish, and the absorption time was taken as the absorber absorption time.

Diffusion area A sample was placed on the slope (45 °), and 1
A total of 150 g of 50 g of physiological saline was injected three times at 5 minute intervals into a 75 mm point in the 40 mm width direction, and the spread state of the liquid 3 minutes after injection was defined as the diffusion area. Fluid return amount 150 g of physiological saline was absorbed into the sample, pressurized after a certain time, and the amount of physiological saline returned from the inside was measured.

Leakage absorption Amount was attached to a baby model designed and manufactured based on an infant weighing 10 kg, and the leakage prevention effect was evaluated. In other words, physiological saline was injected in 50 g increments every 10 minutes, and the amount of absorption (pre-leakage value) absorbed before spilling from the abdomen in the prone position and the amount of absorption absorbed before spilling from the crotch in the sideways position. The amount (crotch leakage value) was measured.

The samples are the same as those in Examples 1 and 2 and Comparative Example except that a 150 (width) x 410 (length) center of a 330 (width) x 450 (length) polyethylene sheet is used. And the absorber of the comparative example was placed. An elastic elastic member is placed 30 mm outside of both ends of the absorber and covered with a nonwoven fabric of the same size as the polyethylene sheet to produce a diaper. The diaper was used as a sample.

[0032]

According to the absorbent article of the present invention, it is possible to sufficiently satisfy the three requirements of excellent liquid leakage prevention, liquid return, and fit.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view in an overlapping direction of layers showing a characteristic portion of an example product 1 in an enlarged manner.

FIG. 2 is a cross-sectional view of a layer in a spreading direction showing a characteristic portion of an example product 1 in an enlarged manner.

FIG. 3 is a plan view of the disposable diaper according to the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disposable diaper 2 Top sheet 3 Back sheet 4 Absorber 4a Upper layer 4b Lower layer 11 Gap in the overlapping direction of layers 12 Gap in the spreading direction of layers

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-168948 (JP, A) JP-A-3-173562 (JP, A) JP-A-1-239101 (JP, A) 40846 (JP, U) Japanese Utility Model Showa 60-97120 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61F 13/53 A61F 13/15 A61F 13/49

Claims (5)

(57) [Claims] 1. An absorbent article comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorber disposed between these two sheets, wherein the absorber comprises a fiber aggregate. The top sheet side upper layer and the back sheet side lower layer. The upper layer is hydrophilic, and the lower layer is a liquid holding layer.
A sex, the upper layer has a non-existent gap portion of the overlapping direction and each successive tubular fiber spreading direction of the layer between the upper layer and the lower layer, the layer overlaps the direction of the diameter of the gap portion of the The distribution has a peak between 200 μm and 1000 μm,
The distribution of the diameter of the voids in the spreading direction of the layer is 100 μm
An absorbent article having the following peaks, wherein the lower layer has a physiological saline absorption capacity of 100 g / 100 cm ² or more. 2. The absorbent article according to claim 1, wherein the thickness of the upper layer satisfies the following expression. (Thickness under pressure when wet / thickness when dry)> 0.5 The thickness under pressure when wet is 5% after saturation with physiological saline.
The thickness when pressed at 0 g / cm ² . 3. The voids in the spreading direction of the layer are two-dimensionally distributed in the horizontal and vertical directions, respectively, and the horizontal cylindrical diameter of the voids is larger than the vertical cylindrical diameter. The absorbent article according to claim 1, wherein 4. The absorbent article according to claim 1, wherein said upper layer and said lower layer are integrally joined. 5. The absorbent article according to claim 1, wherein the thickness of the absorbent when dried is 6 mm or less.