JP3101010B2 - 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 an absorbent article represented by a sanitary napkin, a disposable diaper, a pad for incontinent persons and the like. And the body fluid is selectively diffused in the vertical direction (longitudinal direction of the absorbent article), thereby suppressing the liquid diffusion in the lateral direction (end portion) of the absorber and significantly improving lateral leakage prevention. And a highly absorbent article.

[0002]

BACKGROUND OF THE INVENTION Hitherto, many proposals have been made for absorbent articles aimed at improving the absorbability of bodily fluids, and many improvements have been made. Most of these improvements were to improve the absorption rate, prevent the liquid from returning from the absorber to the surface, and prevent leakage. For example, as for the material of the absorber, as the material of the absorber, instead of a hydrophilic absorbent paper or pulp that absorbs and retains the liquid in a physical micro space, the liquid is physically and chemically acting, that is, It has been proposed to improve absorption capacity and prevent liquid return after absorption by causing a superabsorbent polymer to absorb and retain a liquid by utilizing ionic osmotic pressure. In fact, with this proposal, the absorbency has been improved, and at present, absorbents using a combination of pulp and a superabsorbent polymer are used for most absorbent articles.

[0003] However, even with these absorbent articles,
It is still not sufficient for leakage prevention. Such facts are suggested by leaks as the number one complaint about absorbent articles in market research. In other words, the type of super-absorbent polymer that absorbs and retains a liquid by osmotic pressure has a limit on the absorption rate of bodily fluids, and furthermore, it cannot absorb bodily fluids unless the super-absorbent polymer is wetted by bodily fluids. Is
It had to be used in combination with pulp with a high absorption rate.

However, even if pulp is used in combination, the pulp spreads in the longitudinal direction (longitudinal direction of the napkin) because the liquid diffuses in the same direction and the liquid can spread easily in the lateral (end) direction. While a sufficient absorption space is left in the absorber of (1), the liquid reaches the end portion and leaks easily.
In addition, pulp (although it exhibits some compression and bending recovery when dry) has an extremely low strength when wet,
Because they exhibit little recoverability, when stress is applied to the wet pulp, the pulp undergoes compressive deformation (hereinafter referred to as "yoke") and its absorption space is significantly reduced. In addition, the liquid absorbed and held in the pulp is essentially retained in the fiber gap, and can be easily moved.
Once absorbed, bodily fluids gradually diffuse with distorted blood, and even under very normal use environment, even if the amount of menstrual blood excreted is small, menstrual blood moves to the end and leads to leakage Things are increasing. In addition, the twist and settling of the pulp cause a gap between the pulp and the body, and the body fluid often flows on the surface without being absorbed by the body.

[0005] Thus, there are roughly two ways of improving the drawbacks of the conventional pulp absorber. That is, one is to give directionality to the way of liquid dispersion of pulp, and to minimize the movement of liquid to the edge, and the other is to absorb the main body not pulp, but also to wet the structure when wet. It has been replaced with another stable material. The former, as a method of suppressing the diffusion so that the absorbed liquid is selectively diffused in the vertical direction, by controlling the fiber density in the pulp layer, mainly,
The high-density part and the low-density part which are continuous in the longitudinal direction give a vertical stripe pattern (or a pattern similar thereto) which is alternately arranged in the width direction of the product. It diffuses in the direction. Methods for imparting a density difference are described in, for example, JP-A-55-151960 and JP-A-62-22.
A technique described in, for example, Japanese Patent Publication No. 1348 is proposed.

[0006] The absorber (first prior art) described in JP-A-55-151960 partially increases the amount of laid pulp during laying of pulp and then compresses the entire pulp layer to a constant thickness. As a result, the portion where the pile amount is increased becomes the high-density portion. The sanitary napkin described in Japanese Patent Application Laid-Open No. 62-221348 (second prior art) includes a liquid-permeable surface material, an absorbent mainly composed of pulverized pulp, and a liquid-impermeable backsheet (made of nonwoven fabric). A laminated body), and an absorbent paper, a crushed pulp layer, an absorbent diffusion layer made of absorbent cotton formed into a sheet by water needling, a polymer absorbent layer,
A shielding layer provided with a menstrual covering effect by absorbent paper is integrated with a linear emboss, and the above effect is provided.

[0007] As a method of the latter, a material other than pulp is used to realize stable diffusion suppression even during liquid absorption.
JP-A-61-28003 and JP-A-62-17
The technology described in Japanese Patent No. 0246 and the like has been proposed. The absorbent described in JP-A-61-28003 (third prior art) is a core in which a powdery or fibrous superabsorbent polymer is substantially uniformly distributed and bonded to a nonwoven fabric made of hydrophilic fibers. And a pulverized pulp layer 3 laminated on at least one surface of the core layer, wherein the core layer has a vertical stripe pattern in which high and low fiber density portions are alternately arranged in the width direction of the article. It is.

The absorber (fourth prior art) described in Japanese Patent Application Laid-Open No. Sho 62-170246 has a structure in which polymer particles are mixed in a fiber web. The area not to be formed is spaced in the width direction of the fiber web and forms a vertical stripe pattern continuous in the longitudinal direction, and is intended to quickly vertically diffuse the absorbed liquid in the polymer-free portion.

[0009]

However, in the first and second prior arts described above, embossing the pulp absorber is essentially crushing the absorption space, and the absorber is essentially crushed. It is not preferable because it lowers the total absorption amount. In addition, in this method, in the point that the absorber is twisted or set when wet, it is not different from the conventional absorber, and the diffusion control of the liquid is not effectively performed under the actual use environment, and the original purpose is achieved. It could not be an absorber.

Even in the case of the third prior art, the fact that the pulp is partially responsible for the absorption and retention of the liquid is the same as the first and second prior arts described above. The osmotic pressure of the capillary changes due to twisting and settling,
Since the capillary osmotic pressure level of the core layer is easily exceeded, liquid diffusion as originally designed is hardly realized.
Further, in the fourth prior art, although the design of liquid diffusion is relatively easy in that the absorption is not based on pulp, in reality, the wettability level of the entire portion where the polymer is laminated is significantly reduced, As a result, a sufficient effect on liquid absorption cannot be expected.

As described above, in the case of the pulp alone or the absorbent in which the pulp is combined in some form, the physical properties of the pulp portion change remarkably at the time of mounting, and the initial diffusion control design does not function at all. Further, in the case where regions having different structures are alternately arranged in the width direction on a fibrous web having a stable structure even when wet, the result is that the liquid is selectively retained in a part of the structure, and the liquid is actually absorbed mainly. Is only a part of the absorber, it is not possible to use the absorption space efficiently,
Not only is it uneconomical, but it does not provide sufficient absorption for practical use.

That is, in the above-described prior art, the liquid cannot be effectively diffused in the vertical direction even after the liquid has been absorbed as well as in the initial stage of use, and the movement of the liquid to the end cannot be effectively suppressed. There is a problem. Therefore, an object of the present invention is to provide a liquid absorption device that more effectively diffuses a liquid in a vertical direction than in a horizontal direction thereof, and effectively suppresses the movement of the liquid to an end portion. An object of the present invention is to provide an absorbent article having a high prevention effect.

[0013]

SUMMARY OF THE INVENTION The present invention relates to an absorbent article having a liquid-permeable surface material, a liquid-retentive absorber, and a liquid-impermeable leakproof material, wherein at least a part of the absorber is used. A porous body having a three-dimensional skeletal structure is used. The porous body is uniaxially stretched and then thermoformed, and has a ratio of the capillary osmotic pressure in the longitudinal direction to the capillary osmotic pressure in the width direction (the former / The above object has been achieved by providing an absorbent article characterized in that the latter is 1.2 or more.

The present invention will be described in more detail. The absorbent article of the present invention has a three-dimensional skeletal structure, at least the surface of the skeleton is hydrophilic, and has anisotropic liquid spreading. It is an important requirement that the structure be provided as at least a part of the absorber. If this requirement is satisfied, the material of the skeletal structure is not particularly limited, and any material may be used. For example, porous bodies made of synthetic polymers such as polyurethane, polystyrene, polyethylene, polyester, polyvinyl alcohol, butadiene styrene rubber, and nitrile butadiene rubber, porous bodies made of polysaccharides such as cellulose, and synthetic fibers (polyethylene, polypropylene, polyethylene terephthalate) Etc.) by heat bonding or an adhesive.

In order to impart a suitable liquid spreading anisotropy to the skeleton structure among these porous materials, there are the following methods. First, a first method is to impart anisotropy to the structure when the porous body is formed. For example, there is a method in which the liquid is easily spread in the direction of orientation by appropriately orienting the synthetic fiber when the synthetic fiber is bonded by heat bonding or an adhesive. Second
Is a method of imparting anisotropy to a structure by stretching a thermoformable porous body and heating or heat-compressing the porous body.

In any case, the degree of anisotropy is not particularly limited. However, in order to have an effect on the leakproofness in practical use, the spread of the liquid must be different from that in the maximum direction and that in the minimum direction. It is desirable that the ratio be at least 1.2 or more. When the anisotropy of diffusion of the liquid is equal to or less than this, even if the absorbent article is configured by taking the above-mentioned easy diffusion direction in the longitudinal direction of the absorber, an absorption space is left in the vertical direction at the time of liquid absorption. At this time, the liquid reaches the end portion, and leakage occurs before the absorbing power is sufficiently exhibited, which is not preferable. In order to avoid this, it is necessary to increase the width of the absorbent body in the lateral direction, but this is not realistic because it results in significantly impairing the feeling of wearing the absorbent article.

The degree of stretching when imparting anisotropy by stretching is not particularly limited. However, in order to provide a difference in capillary osmotic pressure for exhibiting the above-described absorption performance, at least 1.2 times or more is required. Stretching is necessary, and more preferably 1.5 times or more. As the degree of stretching increases, the difference in capillary osmotic pressure increases and the anisotropy increases, but excessive stretching results in breakage of the stretched material or, if the absorption space becomes too small, lowers the absorbency. Although the upper limit of the degree of stretching varies depending on the material to be stretched, for example, a fibrous web in which crimped synthetic fibers are roughly fixed, or a porous body made of butadiene styrene rubber having an elastic structure itself, is about 50 times. Stretching is possible, but the limit of stretching suitably used for processing is about 20 times.

When heating is required during the processing, the heating condition is 50 to 300 ° C., preferably 80 to 230 ° C.
It is. If the temperature is lower than 50 ° C., molding cannot be performed in a short time, which is not practical. If the temperature is higher than 300 ° C., the material is significantly deteriorated and the structure cannot be maintained. Further, when compression is applied during heating, the liquid absorption of the three-dimensional skeletal structure can be easily increased because the pores are narrowed and the capillary osmotic pressure is increased. The degree of compression is 0.2
The above is preferable, and 0.4 or more is more preferable. If it is less than 0.2, it is excessively crushed, and the absorption space is lost, so that the absorption performance cannot be exhibited. Also, if it is too hard, the feeling of use is poor.

Here, the compression ratio is defined as in the following equation (1). Compression ratio = (Thickness after recovery after compression becomes stable) /
(Thickness before stretching and compression) ··· (1) The combination of the porous body and the superabsorbent polymer to form an absorbent member complements each other's functions and is the original purpose. Is very effective in achieving That is, the superabsorbent polymer has excellent ability to fix and hold the liquid inside, and can absorb a large amount of menstrual blood several tens times its own weight while suppressing the diffusion of the liquid, as described above. Combination with other materials is required. For pulp that has been conventionally used as this material, as described above, the capillary osmotic pressure increases during wetting (due to twisting and twisting), making it difficult for the liquid to transfer to the polymer. Can not be demonstrated. When the above skeletal structure is used in place of pulp, this material does not change its structure even when wet, and can maintain stable physical properties, so that the liquid transferability to the polymer can be designed at an early stage. It is possible for the polymer to exhibit its absorption performance to the maximum. On the other hand, in order to further increase the effect of the present invention, the use of the superabsorbent polymer prevents unnecessary spreading of the liquid by fixing the liquid by the polymer, and prevents the liquid from migrating to the end. It is very effective because it suppresses strongly. Also,
The liquid in the skeletal structure is transferred to the polymer, and the absorption space in the skeletal structure is regenerated, whereby an absorber that constantly absorbs the liquid quickly can be realized.

The method of combining the skeletal structure with the polymer is not particularly limited. For example, a method of spraying a polymer on the lower layer of the skeletal structure or preparing and installing an absorbent sheet composed of the polymer and absorbent paper can be used. In order to sufficiently exhibit the liquid absorbing and fixing effects of the polymer, it is desirable that the polymer is dispersed as uniformly as possible in the absorption space while keeping the polymer and the skeletal structure in close contact. Specifically, for example, a method of dispersing the polymer in advance at the time of forming the skeletal structure, or a method of stretching and dispersing the polymer before molding, or dividing the skeletal structure into upper and lower two layers or more multilayers A method of dispersing a polymer between the layers and forming after stretching (hereinafter referred to as “stretching / molding”) can be considered.

The use of a porous material which expands during liquid absorption to form the above-mentioned absorbent member is extremely thin in the initial stage of liquid absorption, realizes a high fitting property by absorption, and allows the lower layer to extend from the upper expanded portion to the lower layer. Since the capillary osmotic pressure continuously increases up to the swelling portion, the liquid can be promptly transferred to the lower layer, which is more effective. Among these porous bodies, there are the following three methods for obtaining a preferable volume expansion.

The first is a method of obtaining a three-dimensional skeletal structure in which the skeleton itself absorbs and expands a liquid. For example, a hydrophilic polyurethane foam having expandability and fine particles capable of absorbing and expanding liquid are combined. Examples include composite foams such as polyolefin, polyvinyl alcohol, and rubber substances, and foams of copolymers with carboxylate or sulfonate, a monomer having a sulfate group, a phosphate group, or a phosphonate group.

In the second method, even if the skeleton itself does not absorb and expand, the foam and the fiber assembly made of a synthetic polymer are compressed using a water-soluble binder or the like and then dried and molded to absorb the liquid. A structure that expands in volume can be obtained. In this structure, the water-soluble binder dissolves when absorbing the liquid, and expands in a specific direction in the compressed direction, so it is easy to control the direction of expansion,
By controlling the dissolution rate of the binder, the expansion rate can also be controlled.

The third method incorporates the above two methods and combines the two methods, that is, the skeletal structure in which the skeleton itself expands and has a directionality in volume expansion is used as a liquid. It is preferable because it has excellent holding properties and can easily control the direction of expansion, expansion ratio, expansion speed, and the like. For example, a skeletal structure obtained by compression-drying the absorbent expanded polyurethane foam obtained by the first method using a water-soluble binder or the like can be preferably used.

In order to impart structural anisotropy to these liquid-expandable porous bodies, there are a method of providing anisotropy at the time of forming the porous bodies as described above and a method of performing post-processing and thermoforming. Either may be used. The skeleton structure requires that at least the surface of the skeleton is hydrophilic, and when the material constituting the skeleton is a hydrophobic material, the skeleton structure is used after imparting hydrophilicity with a surfactant.

Such a surfactant is not particularly limited as long as it is a hydrophilic surfactant having a lipophilic group and a hydrophilic group, but an anionic surfactant and an addition mole of ethylene oxide can be used. Higher numbers of nonionic surfactants are preferred. As a surfactant preferably used,
For example, sulfosuccinates, alkyl ether sulfates, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenol ethers, glycerin fatty acid esters and the like can be mentioned. These may be used alone or as a mixture of those appropriately selected from them. Usually, a material that can impart the above-mentioned hydrophilicity (cos θ) at 0.05 to 1% by weight to the sheet is more preferable.

If the skeleton itself is made of a hydrophilic material, there is no need for treatment with a surfactant, and the hydrophilicity during long-term use and re-absorption is stable, which is more preferable. The hydrophilicity is quantified as a degree of hydrophilicity by a powder method (the measuring method is described in Examples described later), and the degree of hydrophilicity (cos θ) is preferably more than 0, more preferably 0.3 or more. . If the hydrophilicity is less than this,
The liquid does not easily penetrate into the skeletal structure, and does not become a practically usable absorber.

Further, the capillary osmotic pressure (see Examples for the measuring method), which is the liquid drawing force of the skeletal structure, is preferably 2000 dyn / cm ² or more in order to obtain higher absorbency.
000 dyn / cm ² or more is more preferable. By designing the capillary osmotic pressure in this region, for example, even in a situation where the absorbent article is mounted at a low mounting pressure such as a bed and the liquid flow is likely to occur, the liquid is stably sucked and leaked. Can be realized. However, in the case of constituting an absorber by combining an absorbent polymer and a skeleton structure, the capillary osmotic pressure of the skeleton structure is excessively large.
As a result of increasing the amount of liquid that cannot be transferred to the polymer while being incorporated in the skeletal structure, the liquid is completely fixed,
This is not always preferable from the viewpoint of suppressing liquid diffusion. Considering the liquid transfer property to the polymer, the capillary osmotic pressure of the skeletal structure is desirably 15,000 dyn / cm ² or less. Therefore, the capillary osmotic pressure of the skeletal structure assuming the composite of the polymer is 4000 dyn / cm ² or more.
Most preferably, it is 500 dyn / cm ² or less.

The skeletal structure can provide a sufficient effect when used alone as an absorber, but may be combined with pulverized pulp or other absorbing members. When combined with another absorbing member, in order to more effectively exhibit the liquid diffusion anisotropy of the skeletal structure, it is necessary to install the uppermost layer of the absorber, that is, immediately below the liquid-permeable surface material. Most preferably, it can be used. As the skeletal structure, only one kind or two or more kinds of skeletal structures may be laminated.

The liquid-permeable surface material and liquid-impermeable backsheet used in the absorbent article of the present invention are not particularly limited, and those used in conventionally known absorbent articles can be used.

[0031]

According to the absorbent article of the present invention, the absorbent has a hydrophilic porous body having a three-dimensional skeleton structure having anisotropy in a specific direction (see FIG. 6). By making the easy direction (the direction in which the average capillary diameter decreases, for example, the stretching direction) the longitudinal direction of the absorber, the liquid is selectively vertically diffused and the liquid is less likely to move in the lateral direction (the end direction of the absorber). Therefore, it is rich in leakproofness.

[0032]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples of the present invention, but the present invention is not limited to these Examples. In the following examples, sanitary napkins will be described by way of example, but the present invention can be similarly applied to disposable diapers and the like.

First, a three-dimensional skeleton structure and a surface sheet used in the present example and comparative example were prepared in the following manner. (1) Creation of three-dimensional skeletal structure Three-dimensional skeletal structure A Commercially available polyurethane foam 1 (trade name: Everlight Scott HXW, manufactured by Bridgestone Corp.) 4 mm thick was cut into a width of 100 mm and a length of 200 mm, and a nonionic surfactant alkyl glycoside (Kao Corp.) Made) 0.75Wt%
As shown in FIG. 12, as shown in FIG. 12, after stretching 1.5 times only in the length direction A on the Teflon plate 2, it was fixed with an adhesive tape 3, and further, as shown in FIG. A stainless steel plate 4 having a thickness of 1.5 mm was placed, and a Teflon plate was further placed on the stainless steel plate 4 and heat-pressed at a temperature of 120 ° C. and a pressure of 30 kg for 5 minutes using a laboratory press (manufactured by Toyo Seiki). The removed foam material slightly recovered in thickness, and finally a three-dimensional skeletal structure A having a thickness of 2 mm was obtained.

2. Three-dimensional skeletal structure B Polyethylene-polypropylene composite fiber (trade name ES
C, manufactured by Chisso Co., Ltd.) 2 deniers are evenly piled, and a heat bonding method using a composite fiber as a binder fiber (a hot air at 140 ° C. is passed through a card web to melt and fix the fibers to each other) to obtain a basis weight of 120 g / A fiber assembly having a thickness of 5 mm ² and a thickness of 5 mm was cut out to a width of 100 mm and a length of 200 mm, and a nonionic surfactant alkyl glycoside (manufactured by Kao Corporation) was 0.75 Wt%.
Attach. Further, similarly to the above-described three-dimensional skeleton structure A,
After stretching 1.5 times only in the length direction on the Teflon plate 2 and fixing it, a stainless steel plate 4 with a thickness of 1.5 mm is installed as a spacer on all sides, and the Teflon plate 2 is further covered from above, and a lab press machine (Toyo Seiki Co., Ltd.) At a temperature of 120 ° C and a pressure of 30k
g for 5 minutes. The thickness of the removed fiber assembly was also slightly recovered, and finally, a 2.2 mm three-dimensional skeletal structure B was obtained.

3. Three-dimensional skeletal structure C polyethylene-polypropylene composite fiber (trade name ES
C, manufactured by Chisso Corporation) 2 deniers are evenly piled, and the basis weight is 240 g / by a thermal bonding method using a composite fiber as a binder fiber (a hot air of 140 ° C. is passed through a card web to melt and fix the fibers). A fiber assembly having a thickness of 5 mm ² and a thickness of 5 mm was cut out to a width of 100 mm and a length of 200 mm, and a nonionic surfactant alkyl glycoside (manufactured by Kao Corporation) was 0.75 Wt%.
Attach. Further, similarly to the above-described three-dimensional skeleton structure A,
After stretching 1.5 times only in the length direction on the Teflon plate 2 and fixing it, a stainless steel plate 4 with a thickness of 1.5 mm is installed as a spacer on all sides, and the Teflon plate 2 is further covered from above, and a lab press machine (Toyo Seiki Co., Ltd.) At a temperature of 120 ° C and a pressure of 30k
g for 5 minutes. The thickness of the removed fiber assembly was also slightly recovered, and finally a three-dimensional skeletal structure C of 2.3 mm was obtained.

4. Three-dimensional skeletal structure D Commercially available polyurethane foam (trade name: Everlight Scott HXW, manufactured by Bridgestone Corporation) 2 mm thick and 1 width
Two pieces having a thickness of 00 mm and a length of 200 mm, to which 0.75 Wt% of nonionic surfactant alkyl glycoside (manufactured by Kao Corporation) were adhered, were laminated, and as shown in FIG. After uniformly spraying 0.5 g of Poise SA-20 (manufactured by Kao Corporation) as the superabsorbent polymer 6 between the layers 5, 5, the length is spread on the Teflon plate 2 in the same manner as the three-dimensional skeleton structure A described above. It is fixed after stretching 1.5 times only in the vertical direction, a stainless steel plate 4 having a thickness of 1.5 mm is installed as a spacer on all sides, and a Teflon plate 2 is further covered from above, and a lab press machine (manufactured by Toyo Seiki) 5 at a temperature of 120 ° C and a pressure of 30 kg
Heat pressed for minutes. The removed foam material also slightly recovered in thickness, and finally a three-dimensional skeletal structure D having a thickness of 2 mm was obtained.

5. Three-dimensional skeletal structure E Commercially available polyurethane foam (trade name: Everlight Scott HXW, manufactured by Bridgestone Corporation) 2 mm thick and 1 width
After cutting to a length of 00 mm and a length of 250 mm and adhering 0.75 Wt% of a nonionic surfactant alkyl glycoside (manufactured by Kao Corporation), it was appropriately drained and dried to obtain a three-dimensional skeletal structure E.

6. Three-dimensional skeletal structure F Commercially available polyurethane foam (trade name: Everlight Scott HXW, manufactured by Bridgestone Corp.) 4 mm thick and 1 width
A three-dimensional skeletal structure F was obtained by cutting out a piece of 00 mm and a length of 250 mm and attaching 0.75 Wt% of a nonionic surfactant alkyl glycoside (manufactured by Kao Corporation).

Capillary osmotic pressure (dyn / cm ² ), hydrophilicity (cos
Measurement of θ) Capillary osmotic pressure and hydrophilicity were measured using a measuring device shown in FIG. First, the three-dimensional skeleton structures A to E are vertically (x
(Axis) 250mm, horizontal (y-axis) cut to 20mm (slice)
Then, ten measurement pieces 8 are prepared. Further, in order to view the liquid diffusion anisotropic products of the respective samples, the skeletal structures A to E are cut (sliced) into a vertical (x-axis) of 20 mm and a horizontal (y-axis) of 250 mm and sampled.

Next, the measuring piece 8 is hung so that the support 9 is not loosened, and both ends are fixed. Also, 300 × 100
A physiological saline solution 16 is put into a rectangular parallelepiped container 10 having a size of 50 mm (length × width × depth) to a height of 40 mm, and the measuring piece 8 is immersed in the saline solution 11. After immersing the measuring piece 8, the maximum liquid suction height after 60 minutes is measured. The same measurement is performed for the ten measurement pieces 8, the average value is calculated, and the obtained average value is substituted for the average wicking height h ₆₀ mm into the equation (2) below to obtain the capillary osmotic pressure P. (Dyn / cm ² ) was determined for the vertical and horizontal directions.

Capillary osmotic pressure P = ρgh ₆₀ ...
(2) P; capillary osmotic pressure (dyn / cm ² ) ρ; specific gravity of physiological saline (g / cm ² ) g; 9.8 × 10 ² cm / sec ² h ₆₀ ; after 60 minutes of physiological saline Absorption height (cm) Next, the physiological saline solution 11 was replaced with ethanol (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.), and the measuring piece 8 after 60 minutes absorbed ethanol in the same manner as above. And measure 10
The average value of the measurement pieces 8 at the points is taken as the height of absorption h ₆₀ ′ of ethanol after 60 minutes. The hydrophilicity cosθ (θ; contact angle between the physiological saline and the measurement piece) between the physiological saline and the measurement piece was determined by the following equation (3).

The method of calculating the hydrophilicity cos θ is as follows.
This is an application of a technique called the powder method. cos θ = h ₆₀ × r ₁ × ρ ₁ / h ₆₀ '× r ₂ × ρ ₂ (3) h ₆₀ ; height of absorption of physiological saline after 60 minutes (cm) r ₁ ; Surface tension (dyn / cm) ρ ₁ ; Specific gravity of ethanol (g / cm ³ ) h ₆₀ ′; Absorption height of ethanol after 60 minutes (cm) r ₂ ; Surface tension of physiological saline (dyn / cm) ρ ₂ ; Specific gravity of physiological saline (g / cm ³ ) Measurement of aspect ratio of liquid spread The aspect / width ratio of liquid spread is measured using the apparatus shown in FIG. First, the three-dimensional skeleton structures A to E are vertically (x-axis) 120
As shown in FIG. 8, the measuring piece 8 is cut from the four sides so that the measuring piece 8 is not loosened by acrylic plates 33, 33 having a length of 100 mm, a width of 100 mm, and a thickness of 10 mm. . Take a physiological saline solution into a pipette and gently drop one drop (0.04 g) from 10 mm above the measurement piece. One minute later, the maximum vertical / horizontal length of the liquid surface spread on the measurement piece is measured as shown in FIG. 11, and the vertical / horizontal spread ratio of the liquid spread is obtained using the equation shown in the following equation (4). . In addition,
The longitudinal direction of the measuring piece is the same as the longitudinal direction of the absorbent article to be finally used. Ratio of vertical / horizontal spread of liquid spread = maximum spread in vertical direction (20) / maximum spread in horizontal direction (20) roll (4) Preparation of surface sheet Alkyl phosphate and sorbitan fatty acid ester Polyethylene with 0.34 wt% of surfactant mixed with
FIG. 4 shows a laminate obtained by laminating a low-density polyethylene 13 (manufactured by Mitsui Petrochemical Industries, Ltd.) to a thickness of 25 g on a dry heat-bonded nonwoven fabric having a basis weight of 25 g / m ₂ using polypropylene composite fiber 12 (manufactured by Chisso Corporation). As shown in the figure, a surface sheet having a formation density of the concave portions 14 of 52 / cm ² was obtained.

The opening 1 of the side wall 15 in the recess 14
The size of 6 was 0.1 to 0.2 mm ² . Table 1 below shows the composition and physical properties of the three-dimensional skeleton structure described above.

[0044]

[Table 1]

In this example, an absorbent article was manufactured using the three-dimensional skeleton structure A as shown in FIG. That is, the three-dimensional skeletal structure A is 175 mm long (x-axis) and 7 mm wide (y-axis).
It is cut into a rectangular parallelepiped having a thickness of 0 mm and a thickness (z-axis) of 2 mm (see FIGS. 5 and 6) to form an absorber 22 (here, the stretching direction of the three-dimensional skeletal structure A is defined as a vertical direction (x-axis)). . Next, the absorbent 22, a liquid-impermeable leakproof sheet 23 laminated with polyethylene, a surface sheet 24 as a liquid-permeable surface material, and a hot-melt pressure-sensitive adhesive 25 for preventing slippage were used as shown in FIG. A napkin (Product 1 of the present invention) was prepared. In FIG. 1, reference numeral 26 denotes release paper, and reference numeral 27 denotes a fixing melt.

Embodiment 2 In this embodiment, a three-dimensional skeletal structure B is used as the absorber 22.
A sanitary napkin (product 2 of the present invention) shown in FIG. 1 was prepared in the same manner as in Example 1 except that the napkin was used. Example 3 In this example, a three-dimensional skeletal structure C was used as the absorber 22.
A sanitary napkin (product 3 of the present invention) shown in FIG. 1 was prepared in the same manner as in Example 1 except that the napkin was used.

Embodiment 4 In this embodiment, a three-dimensional skeletal structure D is used as the absorber 22.
A sanitary napkin (product 4 of the present invention) shown in FIG. 1 was prepared in the same manner as in Example 1 except for using. Example 5 In this example, as shown in FIG. 2, an absorbent article was manufactured using the three-dimensional skeletal structure A. That is, the vertical (x-axis) 175
Absorbent sheet cut to a length of 175 mm and a width of 70 mm under the absorber 22 a using a three-dimensional skeletal structure A cut into a rectangular parallelepiped having a width of 70 mm, a width of 70 mm (y-axis) and a thickness of 2 mm (z-axis). 22b was set as the overlapping absorber 22. The absorbent holding sheet 22b is made of absorbent papers 22c and 22 having a basis weight of 33 g / m ^2.
The superabsorbent polymer 22d sprayed at a basis weight of 40 g / m ² is sandwiched between c. Next, this absorber 2
2. Using a liquid-impermeable leakproof sheet 23 laminated with polyethylene, a surface sheet 24 as a liquid-permeable surface material, and a hot-melt adhesive 25 for preventing slippage, a sanitary napkin shown in FIG. 5) was created.

Example 6 In this example, a three-dimensional skeleton structure D and a three-dimensional skeleton structure E were used as the absorber 22, and an absorbent article was manufactured as shown in FIG. That is, vertical (x-axis) 175 mm, horizontal (y-axis)
Under the three-dimensional skeletal structure E (2a) cut into a rectangular parallelepiped having a thickness of 70 mm and a thickness (z axis) of 2 mm, a three-dimensional skeletal structure D (22c) cut into the same shape was overlapped to form an absorber 22.
Next, a liquid-impermeable leakproof sheet 23 obtained by laminating polyethylene on the absorber 22, a surface sheet 24 as a liquid-permeable surface material, and a hot-melt adhesive 25 for preventing displacement.
Was used to prepare the sanitary napkin (Product 6 of the present invention) shown in FIG.

Comparative Example 1 In this comparative example, a three-dimensional skeleton structure F was used as the absorber 22, and the size of the absorber was 175 mm in length (x-axis) and 175 mm in width (y-axis).
Except for a rectangular parallelepiped with 70 mm axis and 4 mm thickness (z axis),
A sanitary napkin (comparative product 1) having the same configuration as that shown in FIG. 1 was prepared in the same manner as in Example 1.

Comparative Example 2 In this comparative example, instead of the three-dimensional skeleton structure A as the absorber 22, a density of 0.06 g / cm ² and a basis weight of 300 g /
A sanitary napkin (comparative product 2) shown in FIG. 1 was prepared in the same manner as in Example 1 except that a pulp sheet having an m ² and a thickness of 5 mm was used.

Next, the product 1 of the present invention in Examples 1 to 6
In order to see the absorption performance of each of the sanitary napkins of Comparative Examples 1 and 2 and Comparative Examples 1 and 2, a leak test was carried out by the following method, and the anisotropy of liquid spread during exercise was measured for each sanitary napkin. And the results are shown in Table 2 below.
It was shown to. (1) Leakage test The sanitary napkins for testing obtained in the examples and comparative examples were attached to a movable female waist model 29 as shown in FIG. 10 and shorts were turned on, followed by 100 steps / min (50 m / m).
Minutes) at a walking speed of 10 minutes. Thereafter, 3 g of defibrillated horse blood is injected into the tube 30 while walking, followed by 10 minutes of walking at the same speed, and 3 g of defibrillated horse blood is injected while walking, followed by 10 minutes of walking, and defibrillation again. Inject 3 g of horse blood while walking, and walk for 10 minutes.

The number of leaked samples out of the 10 samples in the above process was counted, and the result was defined as the number of leaked samples. (2) Liquid Spread Anisotropy During Exercise As in the case of the leak test, the sanitary napkin 31 for testing obtained in Examples and Comparative Examples was attached to the movable female waist model 29 as shown in FIG. And then 10
They were allowed to walk for 10 minutes at a walking speed of 0 steps / min (50 m / min). Thereafter, 3 g of defibrillated horse blood was injected into the tube 24 while walking, and after walking at the same speed for 10 minutes, the napkin was taken out and decomposed, and the anisotropy of the liquid spread in the absorber 22 was determined as shown in FIG. As shown in the vertical direction 20
And the length in the horizontal direction 23, (length in the vertical direction 20) /
(Length 21 in the horizontal direction).

In the liquid spreading anisotropy of the above (1) and (3), when the absorber is formed by a plurality of three-dimensional skeleton structure layers, each of the three-dimensional skeleton structure layers Was measured and indicated.

[0054]

[Table 2]

According to the results shown in Table 2, the products 1 to 6 of the present invention using the hydrophilic three-dimensional skeleton structure having anisotropic structure and thus having anisotropic liquid diffusivity. It can be seen that is excellent in suppressing the transfer of the liquid to the end of the absorbent body at the time of rest and at the time of exercise, thereby making it difficult to leak.
In addition, it can be seen that an ultra-thin absorbent article can be formed and can be worn extremely comfortably as compared with a conventional pulp absorbent.

[0056]

According to the absorbent article of the present invention, at the time of absorbing a liquid, the liquid is more effectively diffused into the absorber in the vertical direction than in the horizontal direction, and the movement of the liquid to the end is effectively prevented. , The leakage prevention effect can be enhanced. That is, because the structure of the absorber has anisotropy, when the body fluid is absorbed, it has anisotropy in liquid spreading, and because the liquid is selectively vertically diffused, liquid diffusion to the end is suppressed, This realizes an absorber that is very hard to leak.

[Brief description of the drawings]

FIG. 1 is a lateral sectional view of a sanitary napkin which is an embodiment of the absorbent article of the present invention.

FIG. 2 is a diagram corresponding to FIG. 1 showing another embodiment of the absorbent article of the present invention.

FIG. 3 is a diagram corresponding to FIG. 1 showing another embodiment of the absorbent article of the present invention.

FIG. 4 is an enlarged perspective view showing a top sheet of a sanitary napkin.

FIG. 5 is a perspective view showing the stretching and compression directions of the three-dimensional skeletal structure.

FIG. 6 is a perspective view showing the stretching and compression directions of the three-dimensional skeletal structure.

FIG. 7 is a perspective view showing a measuring device used for measuring hydrophilicity and capillary osmotic pressure.

FIG. 8 is a perspective view showing a measuring device used for measuring a spreading ratio (length / width) of a liquid spreading surface.

FIG. 9 is a perspective view showing a movable female waist model used for measurement of a dynamic liquid return amount and a leak test.

FIG. 10 is a perspective view showing a state in which a sanitary napkin for testing is attached to a movable female waist model.

FIG. 11 is a diagram showing a method of measuring a liquid spreading ratio.

FIG. 12 is a view showing a method of stretching and fixing a porous body during production of a three-dimensional skeletal structure.

FIG. 13 is a diagram showing a method of compressing and compressing a porous body during production of a three-dimensional skeletal structure.

FIG. 14 is a cross-sectional view showing one example of a three-dimensional skeletal structure.

[Explanation of symbols]

 22 Absorber 23 Leak-proof sheet (leak-proof material) 24 Surface sheet (surface material)

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-141945 (JP, A) JP-A-62-170246 (JP, A) JP-A-61-28003 (JP, A) JP-A-5-2005 200064 (JP, A) Fully open 1986-36616 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61F 13/15-13/84

Claims (9)

(57) [Claims] 1. An absorbent article having a liquid-permeable surface material, a liquid-retentive absorber and a liquid-impermeable leakproof material, wherein at least a part of the absorber has a three-dimensional skeleton structure. A porous body having uniaxially stretched and then thermoformed, wherein the ratio of the capillary osmotic pressure in the longitudinal direction to the capillary osmotic pressure in the width direction (the former / the latter) is 1.2 or more. Absorbent articles characterized by the following. 2. The absorbent article according to claim 1, wherein said porous body is uniaxially stretched, and further heated and compression molded. 3. The absorbent article according to claim 1, wherein the porous body has a highly absorbent polymer. 4. The absorbent article according to claim 1, wherein said porous body comprises at least two layers, and a superabsorbent polymer is provided between said layers. 5. The absorbent article according to claim 1, wherein the porous body expands with anisotropy in volume when absorbing the liquid. 6. The porous body has a capillary osmotic pressure of 2000 dyn /
The absorbent article according to claim 1, wherein the absorbent article has a size of not less than cm ² . 7. The absorbent article according to claim 1, wherein the hydrophilicity of the surface of the porous body is 0.3 or more. 8. The absorbent article according to claim 1, wherein said porous body is a fiber aggregate. 9. The absorbent article according to claim 1, wherein said porous body is a foam.