JP3331069B2 - Diffusible absorbent paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to absorbent paper which is a constituent material of absorbent articles such as sanitary napkins and disposable diapers. More specifically, the present invention relates to crosslinked cellulose fibers having a high bulk and high liquid absorbability. The present invention relates to a diffusible absorbent paper that can absorb and diffuse and hold a liquid.

[0002]

2. Description of the Related Art
Many proposals have been made for absorbent articles for the purpose of improving body fluid absorbency, and many improvements have been made. Most of these improvements were to improve the liquid absorption rate, prevent the liquid from returning from the absorber to the surface material, prevent the liquid from leaking, and reduce the stickiness of the absorbent article to the body.

[0003] For example, regarding the material of the absorber, instead of using hydrophilic absorbent paper or pulp that absorbs and retains the liquid in the physical fine space, the liquid is subjected to a physicochemical action, that is, It has been proposed to use a highly absorbent polymer that improves the liquid absorption capacity by absorbing and retaining the liquid by ionic osmotic pressure and that prevents liquid return after liquid absorption. By using a superabsorbent polymer, the absorbency of a liquid is improved, and at present, an absorbent using both pulp and a superabsorbent polymer is used for most absorbent articles.

However, even with such absorbent articles, prevention of liquid leakage is still not sufficient, as suggested by the fact that liquid leakage is the first complaint about absorbent articles.

That is, a superabsorbent polymer that absorbs and retains a liquid by ionic osmotic pressure has a limit in the absorption rate of a liquid, and a superabsorbent polymer cannot absorb a liquid unless it is wet with a liquid. Has to be used in combination with pulp or the like having a high liquid absorption rate. However, pulp has a problem in that when a flexible fluff absorbing layer is formed as an absorber, the pulp absorbs liquid locally and has poor diffusivity for efficiently using the entire absorber.

[0006] Further, pulp exhibits some degree of compressive recovery and bending recovery when dry, but has an extremely low strength when wet and hardly exhibits such recoverability. Therefore, when stress is applied to wet pulp, Pulp undergoes compression deformation (hereinafter referred to as
The liquid absorption space is significantly reduced.
As a result, the liquid once absorbed easily returns to the body side with the twist, causing stickiness and liquid leakage.

[0007] In addition, the liquid absorption space is reduced due to the twist, so that the movement resistance when the liquid moves to the polymer increases. As a result, not only does the liquid absorption efficiency of the polymer decrease, but also the resorbing speed of the absorber as a whole after being distorted significantly decreases, often causing liquid leakage.

In order to improve the diffusivity of these fluff pulp and the reduction of the liquid absorption space due to twisting, a proposal has been made to improve the diffusivity and liquid return by compressing / densifying the pulp. Has been reported by However, these proposals do not solve the essential problem that the strength of the pulp is extremely reduced when wet, and conversely, the distance between the fibers of the pulp becomes too close, and the liquid is converted to the polymer. The movement resistance when moving is greatly increased, and as a result, there arises a disadvantage that the liquid absorption efficiency of the polymer is deteriorated.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an absorbent paper comprising fibers having sufficient strength, which suppresses the compression deformation of the fibers when wet and does not lose bulkiness. Another object of the present invention is to provide an absorbent paper having high permeability and high diffusivity.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, the use of specific cellulose fibers has resulted in an absorbent paper having high absorbency, high strength and bulkiness. It was found that it could be obtained.

The present invention has been made based on the above-mentioned findings, and is intended to crosslink intracellular and / or intermolecular cellulose fibers having a fiber roughness of 0.30 to 2 mg / m with a crosslinking agent.
20 to 80 parts by weight of a bulky crosslinked cellulose fiber having a compressive residual strain of less than 40% when wet and a hydrophilic fine fiber 8
The above object has been achieved by providing a diffusible absorbing paper characterized by comprising 0 to 20 parts by weight.

The diffusible absorbent paper of the present invention is particularly preferably used for absorbent articles of absorbent articles such as sanitary napkins, incontinence pads and disposable diapers.

First, the bulky crosslinked cellulose fiber used in the present invention will be described.

The bulky crosslinked cellulose fiber used in the present invention is a cellulose fiber having a fiber roughness of 0.30 to 2 mg / m , in which the inside and / or the inside of the molecule is crosslinked with a crosslinking agent. As the cellulose fiber, any of natural cellulose fibers such as wood pulp and cotton and regenerated cellulose fibers such as rayon and cupra may be used. From the viewpoint of cost, wood pulp is preferably used, and conifer pulp (NBKP) is particularly preferably used. These cellulose fibers may be used alone or in combination of two or more.

Examples of the crosslinking agent used for crosslinking the cellulose fibers include N-methylol compounds such as dimethylol ethylene urea and dimethylol dihydroxyethylene urea; and polycarboxylic acids such as tricarballylic acid citrate and butanetetracarboxylic acid. Polyols such as dimethylhydroxyethylene urea; and polyglycidyl ether-based crosslinking agents. These crosslinking agents may be used alone or in combination of two or more.

The amount of the crosslinking agent used is 100
It is preferable that the amount be 0.2 to 20 parts by weight based on parts by weight. If it is less than 0.2 parts by weight, the crosslinking density is low,
The modulus of elasticity at the time of wetness is low, and twist / settling may occur. When the amount exceeds 20 parts by weight, the cellulose fibers become too rigid, and when stress is applied, the fibers may become brittle. .

In order to crosslink cellulose fibers using such a crosslinking agent, for example, an aqueous solution of the crosslinking agent to which a catalyst is added as necessary is impregnated with the cellulose fibers, and the aqueous solution of the crosslinking agent has a designed adhesion amount. Or by heating to a crosslinking temperature, or spraying an aqueous solution of a crosslinking agent onto a cellulose fiber by spraying or the like so as to have a designed adhesion amount, and then heating to a crosslinking temperature to cause a crosslinking reaction.

The bulky crosslinked cellulose fiber used in the present invention is a cellulose fiber in which the inside and / or between the molecules of the cellulose fiber are crosslinked. As a result, when the bulky crosslinked cellulose fiber is wet with a liquid, twisting and settling do not occur. Further, the bulky crosslinked cellulose fiber itself hardly absorbs liquid due to crosslinking, and as a result, the fiber itself hardly swells, so that it can be kept stable. In the present invention, the synergistic effect of these two makes it possible to further stably maintain the distance between the bulky crosslinked cellulose fibers even when the fibers are wet with a liquid. Therefore, in the present invention, the bulky crosslinked cellulose fibers are preferably crosslinked both inside and between molecules of the cellulose fibers.

In the present invention, the fiber roughness is 0.30 to 0.30.
Crosslink cellulose fibers at 2 mg / m . Preferably
Has a fiber roughness of 0.33 to 1 mg / m . Cellulose fibers having a fiber roughness of less than 0.3 mg / m are thin and supple, so that the effect of crosslinking is hardly exhibited. Fiber roughness 2mg / m
Cellulose fibers in excess of, the rigidity is too high.

In the present invention, “fiber roughness” means
It is used as a measure to express the thickness of a fiber having a non-uniform fiber thickness, such as wood pulp. For example, a fiber roughness meter (FS-200, KAJAANI ELEC
TRONICS LTD.).

Examples of cellulose fibers having a fiber roughness of 0.30 to 2 mg / m include softwood kraft pulp (“ALBACEL” (trade name) manufactured by Federal Paper Board Co., and “PT Inti Indorayon Utama”). INDORAYON
(Trade name)).

Generally, in an absorbent paper used in an absorbent article, the closer the fiber cross section is to a perfect circle, the smaller the movement resistance when the liquid moves in the absorbent paper. Also,
As the cross-sectional shape of the cellulose fiber is closer to a perfect circle, the effect of crosslinking when crosslinking with a crosslinking agent is more likely to be exhibited. Therefore, in the present invention, it is more preferable that the cross-sectional shape of the cellulose fiber to be cross-linked is close to a perfect circle. Specifically, the roundness of the cellulose fiber is preferably 0.5 or more, and more preferably 0.55 to 1.0.
That is, in the present invention, degree of fiber roughness of the cellulose fibers of performing cross-linking is 0.30~2mg / m, and, more advantageous effects if roundness is 0.5 or more is obtained.

As described above, in the present invention, it is preferable to use wood pulp as the cellulose fiber.
Generally, the cross section of wood pulp is flat due to delignification treatment, and most of its roundness is less than 0.5. In order to make the roundness of such wood pulp 0.5 or more, for example, the wood pulp may be mercerized to swell the cross section of the wood pulp.

As described above, the crosslinked cellulose fibers used in the present invention include mercerized crosslinked mercerized pulp obtained by mercerizing ordinary wood pulp and having a roundness of 0.5 or more. Pulp is preferred.

The mercerized crosslinked pulp can be obtained by, for example, mercerizing the above-mentioned wood pulp having a fiber roughness of 0.30 to 2 mg / m to increase the roundness of the cross section, and then cross-linking the pulp. It is also possible to obtain a commercially available mercerized pulp and crosslink it.

Commercially available mercerized pulp usable in the present invention includes "FILTRANIER" (trade name) manufactured by ITT Rayonier Inc. and "POROSANIER" manufactured by the company.
(Product name) and the like.

It is preferable that the bulky crosslinked cellulose fiber used in the present invention has a small twist / set when wet with a liquid. That is, it is preferable that the residual strain when the bulky crosslinked cellulose fiber is compressed when wet is small. The smaller the compression set is, the better the compression set is. Specifically, the compression set of the bulky crosslinked cellulose fiber when wet is 40%.
Der than% is, it is favorable preferable less than 35%. The residual compression set of the bulky crosslinked cellulose fiber when wet is 40.
Above percentages, twist / settling when the liquid absorption rate and the liquid absorption capacity at the time of absorbing the liquid wet decreased greatly ing.
As a result, the liquid absorbing space is reduced, the distance between the fibers is difficult ing to stably maintain the bulky crosslinked cellulose fibers becomes dense.

It is possible to stably reduce the compression set of cellulose fiber by 4%.
In order to maintain the distance between the cellulose fibers to be less than 0% and to keep the distance between the cellulose fibers stable, it is important to adjust the thickness of the bulky crosslinked cellulose fibers in addition to crosslinking the cellulose fibers. The reason is that the thicker the bulky crosslinked cellulose fiber is, the easier it is to stabilize the residual compression set of the bulky crosslinked cellulose fiber at a low value when wet, and the distance between fibers is not reduced. Because. Since the thickness of the bulky crosslinked cellulose fiber depends on the thickness of the cellulose fiber to be crosslinked, the thickness of the bulky crosslinked cellulose fiber may be adjusted by appropriately adjusting the thickness of the cellulose fiber. As described above, the fiber roughness is a measure of the thickness of the fiber, so in the present invention,
A bulky crosslinked cellulose fiber having a fiber roughness of 0.30 to 2 mg / m, which is obtained by crosslinking the inside and / or the inside of a cellulose fiber with a crosslinking agent, and has a compressive residual strain of 40 when wet.
That use of less than%. In particular, the fiber roughness is 0.30
A bulky crosslinked cellulose fiber obtained by crosslinking the inside and / or the inside of a cellulose fiber having a circularity of 2 mg / m and a roundness of 0.5 or more with a crosslinking agent, and having a compression residual strain of less than 40% when wet. It is preferable to use

Next, the diffusive absorbing paper of the present invention will be described. In addition, about the point which does not specifically detail about a bulky bridge | crosslinked cellulose fiber, the above description is suitably applied. The diffusible absorbent paper of the present invention is characterized in that the bulky cellulose fibers 20 described above are used.
To 80 parts by weight, preferably 30 to 70 parts by weight, and 80 to 20 parts by weight, preferably 70 to 70 parts by weight of hydrophilic fine cellulose fibers.
-30 parts by weight. Its basis weight is preferably 2
0 to 60 g / m ² , more preferably 20 to 50 g
/ M ² . In the diffusible absorbent paper, if the bulky crosslinked cellulose fiber is less than 20 parts by weight or the hydrophilic fine fiber exceeds 80 parts by weight, a strong tightening force acts between the fibers at the time of paper making, and the liquid absorption space is reduced, so that the liquid absorbing space is substantially reduced. Or the space where it can diffuse. Further, in the diffusible absorbent paper, if the bulky crosslinked cellulose fiber exceeds 80 parts by weight or the hydrophilic fine fiber is less than 20 parts by weight, the distance between the fibers becomes large, and the ability to diffuse body fluid becomes insufficient. Not preferred.

As the hydrophilic fine fibers, fibers having a hydrophilic fiber surface and a large surface area can be used, preferably having a fiber roughness of less than 0.2 mg / m, more preferably 0.01 to 0.01 mg / m. 0.2 mg / m, and the roundness is preferably less than 0.5, more preferably 0.1 to 0.4.
Or fiber surface area of preferably 1.0 m ² / g or more, more preferably hydrophilic fibers is 1-20 m ² / g are preferably exemplified. Such hydrophilic fine fibers generally have a fiber length of 0.5 to 15 mm.

The hydrophilic fine fibers used in the present invention are not particularly limited as long as they have the above physical properties.
For example, cellulose fibers such as wood pulp, cotton, rayon, and the like, and synthetic fibers having a hydrophilic group such as acrylonitrile and polyvinyl alcohol are exemplified. In particular, wood pulp can be preferably used because it is very inexpensive and the surface area of the fiber can be controlled by controlling the beating conditions. As such wood pulp, NBKP (for example, Skeena cellulose Co.
Finely beaten “SKEENA PRIME” (trade name) manufactured by LBKP (“PREE” manufactured by Waferuser Paper Co., Ltd.)
IME ALBERT ASPEN HANDWOOD "(trade name)) and straw pulp. The above-described hydrophilic fine fibers can be used alone or in combination of two or more.

Most of the conventional absorbent papers used in absorbent articles are those obtained by wet-making natural pulp such as ordinary softwood pulp, and the absorbent paper obtained by wet-making such natural pulp is In the dewatering / wet-pressure / drying process during papermaking, when water is dewatered from the paper layer and the paper layer is dried, very strong tightening between the pulp fibers is caused by the interfacial tension and the hydrogen bond acting on the pulp fibers. Power works. Since the distance between the pulp fibers is reduced by the tightening force, the conventional absorbent paper has a very slow absorption / permeation of the liquid, and further, the liquid absorption space is reduced, so that the liquid permeability is deteriorated. I was On the other hand, in the diffusible absorbent paper of the present invention, by blending the bulky crosslinked cellulose fibers, the hydrogen bonding acting between the fibers during wet papermaking is suppressed, and the tightening force acting between the fibers is reduced. The liquid absorption space is enlarged, and the flow of the liquid to absorb, transmit, and diffuse the liquid is controlled.

The diffusible absorbent paper of the present invention preferably contains up to 30 parts by weight of a heat-fusible adhesive fiber. If the amount of the heat-fusible adhesive fiber exceeds 30 parts by weight, the hydrophilicity of the diffusible absorbent paper is reduced, and the diffusivity and permeability of the liquid are undesirably reduced. By including the heat-fusible adhesive fiber in the diffusive absorbent paper, the effect of further stabilizing the fiber space when wet is further produced. More preferably, the diffusible absorbent paper contains up to 20 parts by weight, particularly preferably 2 to 20 parts by weight, of the hot-melt adhesive fiber.

As the hot-melt adhesive fibers, fibers which are melted by heating and adhere to each other can be used. Specifically, for example, polyolefin fibers such as polyethylene, polypropylene and polyvinyl alcohol, polyester fibers, polyethylene fibers -Polypropylene conjugate fiber, polyethylene-polyester conjugate fiber, low melting point polyester-polyester conjugate fiber, polyvinyl alcohol-polypropylene conjugate fiber having a hydrophilic fiber surface, polyvinyl alcohol-polyester conjugate fiber, and the like. When using a conjugate fiber, any of a core-sheath type conjugate fiber and a side-by-side type conjugate fiber can be used. These heat fusible adhesive fibers can be used alone or in combination of two or more. Examples of the heat-fusible adhesive fiber preferably used in the present invention include polyvinyl alcohol and polyester.

The hot-melt adhesive fiber generally has a fiber length of 2 to 60 mm and a fiber diameter of 0.5 to 3 denier.

The method for producing the diffusible absorbent paper is not particularly limited, and for example, a commonly used wet or dry papermaking method can be used. When using the wet papermaking method,
The bulky crosslinked cellulose fibers and hydrophilic fine fibers and, if necessary, the hot-melt adhesive fibers are dispersed in water, and if necessary, other components are added to form a slurry, and the slurry is made into a paper using a paper machine. I do. After papermaking,
If necessary, calendaring and creping can be performed.

Examples of the other components include dialdehyde starch, sponge, sodium carboxymethylcellulose and the like. These components are:
0 to 20 parts by weight can be added.

The thus-produced diffusible absorbent paper has a thickness of 0.2 to 0.8 m under a load of 2.5 g / m ^2.
m is preferable. The reason for this is that the thickness is 0.
When the thickness is less than 2 mm, the space for diffusing the liquid may be small and the ability may be insufficient. When the thickness is more than 0.8 mm, the thickness may be too large and the body fluid may not be easily transmitted to the superabsorbent polymer. Particularly preferably, the thickness is 0.3 to 0.6 mm.

Further, in the present invention, the diffusible absorbent paper needs to have a function of rapidly diffusing a liquid over a wide area. Accordingly, the diffusible absorbent paper preferably has a Klemm absorption height of 50 mm or more after 1 minute with respect to physiological saline and 100 mm or more after 10 minutes.
If the Krem absorption height is less than these values, the diffusivity of the liquid may be poor, which is not preferable. More preferably, the Krem absorption height after 1 minute with respect to physiological saline is 6
0 to 120 mm. The creme absorption height after 10 minutes is 120 to 300 mm. The method of measuring the Krem absorption height will be described later.

As described above, the diffusible absorbing paper needs to have a function of rapidly diffusing the liquid, and in addition, it is desirable that the liquid absorbing speed is high. That is, the diffusible absorbent paper preferably has a passage time of 10 g of an 85% by weight aqueous glycerin solution of 100 g or less, and more preferably 10 to 8 g
It is preferably 0 seconds. Such diffusible absorbent paper exhibits particularly excellent performance with respect to liquid diffusion and absorption.
The method for measuring the passage time of 10 g of the 85% by weight glycerin aqueous solution will be described later.

The diffusible absorbent paper of the present invention is particularly preferably used as an absorbent in absorbent articles such as sanitary napkins, incontinence pads and disposable diapers. That is, an absorbent article comprising a liquid-permeable surface material, a liquid-impermeable leakproof material, and a liquid-retentive absorber interposed between the surface material and the leakproof material. A body comprising the diffusible absorbent paper of the present invention is obtained.

As an example of the absorbent article, the sanitary napkin shown in FIG. 1 will be described as an example. The sanitary napkin 10 shown in FIG. 1 has a liquid-permeable surface material 1 and a liquid-impermeable leakproof material 3. And a liquid-holding absorber 2 interposed between the surface material and the leak-proof material.

More specifically, the sanitary napkin 10 is formed substantially vertically long, and when the sanitary napkin 10 is worn, the surface material 1 is located on the side in contact with the skin, and the leakproof material 3 is provided. The absorber 2 is interposed between the surface material 1 and the leak-proof material 3. In addition, as shown in FIG. 1, the back surface, all side surfaces and the peripheral edge of the front surface of the absorber 2 are covered with a leak-proof material 3, and the entire surface thereof is covered with a surface material 1. The central part of the surface of the absorber 2 is directly covered with the surface material 1, so that the body fluid is directly transmitted to the absorber 2. On the back side of the surface material 1, three adhesive portions 4 are formed linearly in the longitudinal direction, and the adhesive portions 4 are protected by a release paper 5. In addition, in FIG. 1, 6 is a joining part by hot melt.

The absorbent 2 is composed of the super absorbent polymer 2
b is covered with the above-mentioned diffusible absorbing paper 2d, and is further covered with absorbing liquid 2c having high liquid permeability.

A sanitary napkin 10 having such a configuration
In, the bodily fluid that has passed through the absorbent paper 2c is smoothly absorbed into the interior of the absorbent body 2, is diffused throughout the absorbent body 2 by the diffusible absorbent paper 2d, and is completely fixed by the highly absorbent polymer 2b.

Another embodiment of the absorbent article using the diffusible absorbent paper of the present invention is shown in FIG. 2 using a sanitary napkin as an example.
This will be described with reference to FIG. Although the same points as those in FIG. 1 are not particularly described in detail, the description in detail with reference to FIG. 1 is appropriately applied. In FIG. 2, the same members as those in FIG. 1 are denoted by the same reference numerals.

In the sanitary napkin 10 shown in FIG. 2, the absorbent 2 scatters a superabsorbent polymer 2b between a plurality of diffusible absorbent papers 2d and wraps the absorbent with a highly liquid absorbent absorbent paper 2c. It is formed over. By using the absorbent body 2 having such a configuration, even when the superabsorbent polymer 2b absorbs a body fluid and swells, the particles of the superabsorbent polymer 2b are less likely to agglomerate. The gel blocking of the absorbent polymer 2b can be suppressed, and the fluidity between the particles of the superabsorbent polymer 2b can be improved.

In the present invention, if the absorbent body 2 having the structure shown in FIG. 2 is used, an absorbent article exhibiting high absorption performance can be obtained even during high excretion.
Particularly preferred.

An absorbent article using the diffusible absorbent paper of the present invention has excellent high absorption performance, especially excellent reabsorption rate / retention capacity during repeated excretion even if it is thinner than conventional absorbent articles. It can be obtained, has high excretion, and is very comfortable without liquid return, stickiness and leakage even when worn for a long time. In addition, by using the diffusible absorbent paper of the present invention, which is mainly composed of the above-mentioned crosslinked cellulose fiber and controls the absorption / transmission / diffusion performance of body fluid, it becomes possible to obtain an absorber having extremely high absorption performance very easily.

[0050]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but it goes without saying that the scope of the present invention is not limited to these Examples. In the following description, “parts” means “parts by weight” unless otherwise specified.

[Production Example 1] Fiber roughness of 0.36 mg / m
And mercerized pulp with a fiber cross-section of roundness of 0.80 (trade name: "POROSANIER-J", ITT Rayonier Inc.
Dimethylol dihydroxyethylene urea (trade name; "Sumitex Resin NS-19") as a crosslinking agent.
, A Sumitomo Chemical Co., Ltd.) 5% by weight and a metal catalyst (trade name: "Sumitex Accelerator X-110", a product of Sumitomo Chemical Co., Ltd.) 3% by weight.
g and the mercerized pulp was impregnated with a crosslinking agent. Next, after removing excess cross-linking agent aqueous solution from the mercerized pulp such that the amount of the cross-linking agent aqueous solution with respect to the mercerized pulp is 200% by weight, the mixture is heated at 135 ° C. for 10 minutes in an electric dryer, and Was crosslinked between cellulose molecules and between pulp fibers to obtain a mercerized crosslinked pulp. This is referred to as a cellulose fiber (A).

[Production Example 2] Fiber roughness of 0.35 mg / m
The softwood clat pulp NBKP (trade name: "INDORAYON", PT Inti Indo
dimethylol dihydroxyethylene urea (trade name; “Sumitex Re
sin NS-19 ", 5% by weight of Sumitomo Chemical Co., Ltd., and 5% by weight of a metal catalyst (trade name:" Sumitex Accelerator X-110 ", Sumitomo Chemical Co., Ltd.) The kraft pulp was impregnated with a crosslinking agent.
Next, the amount of the crosslinking agent aqueous solution with respect to the pulp is 2
After removing the excess aqueous solution of the crosslinking agent from the pulp so as to be 00% by weight, the mixture was heated at 135 ° C. for 10 minutes in an electric dryer to crosslink cellulose molecules and pulp fibers in the pulp to obtain a crosslinked pulp. Was. This is referred to as a cellulose fiber (B).

[Production Example 3] Fiber roughness of 0.78 mg / m
A cross-linking reaction was performed in the same manner as in Production Example 1 except that rayon having a roundness of the fiber cross section of 0.68 and a length of 8 mm (trade name: "Corona SB Rayon", manufactured by Daiwabo Rayon Co., Ltd.) was used. To obtain a crosslinked rayon fiber. This is referred to as a cellulose fiber (C).

[Comparative Production Example 1] The fiber roughness was 0.18 mg /
m, softwood kraft pulp NBKP (trade name: "SKEENA PRIME", Skeena
Crosslinking reaction was carried out in the same manner as in Production Example 1 except that Cellulose Co.) was used to obtain a crosslinked pulp. This is referred to as a cellulose fiber (D).

[Comparative Production Example 2] The fiber roughness was 0.18 mg /
m, softwood kraft pulp NBKP (trade name: "SKEENA PRIME", Skeena
Cellulose Co.) was prepared. This is referred to as a cellulose fiber (E).

[Comparative Production Example 3] The fiber roughness was 0.24 mg /
m, softwood kraft pulp NBKP (trade name: "HARMAC-R", MacMillan)
Bloedel Ltd.) was prepared. This is referred to as a cellulose fiber (F).

The fiber roughness, the roundness of the fiber cross-section, and the residual compression set when wet were measured by the following methods for the cellulose fibers (A) to (F). Table 1 shows the results.

<Measurement of Fiber Roughness> Fiber roughness meter FS-20
0 (manufactured by KAJAANI ELECTRONICS LTD.).
First, in order to determine the true weight of the cellulose fiber, the cellulose fiber is dried in a vacuum dryer at 100 ° C. for 1 hour to remove water present in the cellulose fiber.
Approximately 1 g of cellulose fiber at ± 0.1 g accuracy
Measure accurately. Next, the cellulose fibers were completely disintegrated in 150 ml of water with a mixer attached to a fiber roughness meter so as not to damage the cellulose fibers.
Was diluted with water until the solution reached, 50 ml was accurately weighed from the obtained diluent, and this was used as a fiber roughness measurement solution. The fiber roughness was determined according to the operation procedure of the fiber roughness meter.

<Measurement of Roundness> The roundness of the cellulose fiber cross section was measured by first slicing the cellulose fiber perpendicularly to the cross-sectional direction so that the area of the cross-section of the cellulose fiber did not change, and then using an electron microscope. A photograph is taken and the cross-sectional photograph is taken by an image analyzer (manufactured by Nippon Avionics Co., Ltd .; trade name;
"Avio EXCEL"), and the roundness of the cross section of the cellulose fiber was determined using the following equation. In addition, the roundness was determined by measuring 100 points of an arbitrary cellulose fiber cross section and calculating an average value thereof.

(Equation 1)

<Measurement of Compressive Residual Strain when Wet> A crosslinked cellulose fiber was sheeted to a size of 50 mm × 50 mm at a basis weight of 500 g / m ² , and 5.0 ± 0.5 g under a load of 5 g / cm ^2.
Adjusted to be the thickness L ₀ of 0.1 mm. Next, assuming that body fluid is excreted, 12.5 g of physiological saline (approximately 10 times the sheet weight) is applied almost uniformly to the entire sheet to make the entire sheet wet. Thereafter, in a Tensilon compression tester, the compression area was 10 cm ² (radius 1.78).
cm disk), compression speed 10mm / min, maximum load 200
g / cm ² (ie, a total of 2000 g),
Depressurize at a constant speed. At this time, the physiological saline overflowing from the pulp by the compression is absorbed and removed by a tissue or the like. This operation was repeated 10 times in total, and the thickness L ₁ under a load of 5 g / cm ² after compression measurement was determined, and the compression residual strain was determined using the following equation.

(Equation 2)

[0061]

[Table 1]

As is evident from Table 1, the fiber roughness was 0.1%.
By cross-linking cellulose fibers of 3 mg / m or more,
It can be seen that it becomes possible to keep the compression set during wetting at less than 40%. However, the fiber roughness is 0.3mg / m
With respect to the following cellulose fibers and crosslinked cellulose fibers obtained by crosslinking cellulose fibers having a fiber roughness of 0.3 mg / m or less, the residual compression set when wet cannot be maintained at less than 40%. This indicates that the cellulose fibers are very easily crushed when compressed when wet. Therefore, when absorbing body fluid, it is impossible to maintain the fiber space formed by the cellulose fibers, and it is not preferable because the distance between the fibers cannot be stably maintained.

Example 1 Cellulose fiber (A) (70 parts by weight) and hydrophilic fine fibers having a fiber roughness of 0.18 mg / m 2
Kraft pulp N with a roundness of 0.32 for fiber cross section
BKP (Product name: "SKEENA PRIME", Skeena Cellulose
Co., Ltd.) and 30 parts by weight in water, respectively, and mixed in water. The paper was made using a paper machine and then dried to obtain a basis weight of 40 g / m ^2.
Was obtained. This is designated as an absorbent sheet (A).

Example 2 75 parts by weight of cellulose fiber (B) and 0.18 mg / m of fiber roughness as hydrophilic fine fibers
Kraft pulp N with a roundness of 0.32 for fiber cross section
BKP (Product name: "SKEENA PRIME", Skeena Cellulose
Co., Ltd.) and 25 parts by weight in water, respectively, were mixed in water, paper-made using a paper machine, and then dried to obtain a basis weight of 40 g / m ^2.
Was obtained. This is designated as an absorbent sheet (B).

Example 3 Cellulose fiber (A) 40 parts by weight and hydrophilic fine fiber having a fiber roughness of 0.18 mg / m 2
Kraft pulp N with a roundness of 0.32 for fiber cross section
BKP (Product name: "SKEENA PRIME", Skeena Cellulose
Co., Ltd.) and 60 parts by weight, respectively, were dispersed and mixed in water, paper-made using a paper machine, and then dried to obtain a basis weight of 40 g / m ^2.
Was obtained. This is designated as an absorbent sheet (C).

Example 4 60 parts by weight of a cellulose fiber (A) and a fiber fineness of 0.18 mg / m 2 as a hydrophilic fine fiber
Kraft pulp N with a roundness of 0.32 for fiber cross section
BKP (Product name: "SKEENA PRIME", Skeena Cellulose
Co.) 37 parts by weight and a thickness of 1 as a hot-melt adhesive fiber
Denier 3mm long polyvinyl alcohol (Product name:
3 parts by weight of FibriBond (manufactured by Sansho Co., Ltd.) were dispersed and mixed in water, paper-made using a paper machine, and then dried to obtain a diffusible absorbent paper having a basis weight of 40 g / m ² . This is designated as an absorbent sheet (D).

Comparative Example 1 Cellulose fiber (E) 100
A part by weight was dispersed in water, paper was formed using a paper machine, and then dried to obtain a paper having a basis weight of 40 g / m ² . This is designated as an absorbent sheet (E). The absorbent sheet (E) does not contain crosslinked cellulose fibers.

[Comparative Example 2] Fiber roughness of 0.35 mg / m
The softwood clat pulp NBKP (trade name: "INDORAYON", PT Inti Indo
rayon Utama) 60 parts by weight, and softwood kraft pulp NBKP (trade name: "SKEENA PRI") having hydrophilic fine fibers of 0.18 mg / m in fiber roughness and 0.32 in roundness of fiber cross section
ME ", were dispersed and mixed and SkeenaCellulose made Co.) 40 parts by weight water respectively, after papermaking with a paper machine and dried to obtain a diffusing absorbent paper having a basis weight of 40 g / m ^2. This is designated as an absorbent sheet (F). The absorbent sheet (F) does not contain crosslinked cellulose fibers.

Comparative Example 3 Cellulose fiber (D) (60 parts by weight) and hydrophilic fine fiber having a fiber roughness of 0.18 mg / m
Kraft pulp N with a roundness of 0.32 for fiber cross section
BKP (Product name: "SKEENA PRIME", Skeena Cellulose
Co.) (40 parts by weight) was dispersed and mixed in water, and the paper was made using a paper machine, and then dried to obtain a basis weight of 40 g / m ^2.
Was obtained. This is designated as an absorbent sheet (G).

[Comparative Example 4] 10 parts by weight of cellulose fiber (B) and 0.18 mg / m of hydrophilic fine fiber
Kraft pulp N with a roundness of 0.32 for fiber cross section
BKP (Product name: "SKEENA PRIME", Skeena Cellulose
90 parts by weight in water, respectively, and mixed by dispersion in water. After papermaking using a paper machine, the paper was dried, and the basis weight was 40 g / m ^2.
Was obtained. This is designated as an absorbent sheet (H).

[Comparative Example 5] 30 parts by weight of cellulose fiber (B) and 0.18 mg / m of fiber roughness as hydrophilic fine fibers
Kraft pulp N with a roundness of 0.32 for fiber cross section
BKP (Product name: "SKEENA PRIME", Skeena Cellulose
Co.) 30 parts by weight, thickness as hot-melt adhesive fiber 1.
1 denier, 5 mm long PET (trade name: "TMOTNSB"
And 40 parts by weight (manufactured by Teijin Limited) are dispersed and mixed in water, and the paper is made using a paper machine, and then dried to obtain a basis weight of 40 g.
/ M ² . This is designated as an absorbent sheet (I).

2.5 of the above absorbent sheets (A) to (I)
The thickness under a load of g / m ^{2, the} height of absorption of Krem in physiological saline (after 1 minute and 10 minutes), and the passage time of an 85% by weight aqueous glycerin solution were measured by the following methods. Table 2 shows the results.

<Krem absorption height (after 1 minute and 10 minutes)
> Krem absorption height was measured using the apparatus shown in FIG.
First, the absorbent sheet was cut into a length of 300 mm and a width of 20 mm to produce a measurement piece 11 shown in FIG. Next, as shown in FIG. 3, the measurement piece 11 was hung so that the support 12 did not slack, and both upper and lower ends were fixed. Also, 300 × 10
A physiological saline solution 14 was placed in a rectangular parallelepiped container 13 of 0 × 50 mm (length × width × depth) as a measuring solution to a depth of 40 mm, and the measuring piece 11 was immersed in the physiological saline solution 14. One minute after immersing the measuring piece 11, the height of the measuring liquid absorbed by the measuring piece 11 and the height of the measuring liquid absorbed by the measuring piece 11 after 10 minutes were measured. . It performs the same respective 10 points of measurements to obtain an average Klemm absorption height after 1 minute of each taking a value h _1, and Klemm absorption height h ₁₀ after 10 minutes.

<Measurement of passage time of 85% by weight glycerin aqueous solution> The passage time of an 85% by weight glycerin aqueous solution was measured using the apparatus shown in FIG. First, the absorbent sheet was cut into a length of 50 mm and a width of 50 mm to prepare a measurement piece 15 shown in FIG. Next, as shown in FIG. 4, the measurement piece 15 was clamped and fixed from both upper and lower sides using glass tubes 16 and 17 having an inner diameter of 35 mm. At this time, it was fixed from both sides with clips (not shown) via the silicone rubber 18 so that the liquid would not seep out during the measurement. Glycerin 8 as the measuring solution
10 g of the 5% by weight aqueous solution 19 was placed in a 10 ml beaker 20 and gently poured into the glass tube 16. Glycerin 85
After injecting the weight% aqueous solution 19, the time required for the surface of the measurement piece to appear by 50% or more with respect to the opening area of the glass tube 6 was determined, and this was defined as the liquid passage time. In addition, the measurement liquid (85% by weight glycerin aqueous solution) was prepared as follows. Glycerin [Wako Pure Chemical Industries, Ltd.] 85 g in 15 g of deionized water
g, and then mixed with Edible Blue No. 1 [Tokyo Kasei Kogyo Co., Ltd.]
0.01 g was added, and the measurement liquid was colored blue.

[0075]

[Table 2]

As is clear from the results shown in Table 2, according to the diffusible absorbent paper using the crosslinked cellulose fibers and the hydrophilic fine fibers, the liquid can be quickly transmitted and the liquid can be rapidly diffused. Becomes possible.

[Embodiments 5 to 8] As shown in FIG.
Absorbent sheets (A) to (D) are used as diffusible absorbent paper 2d having a width of 75 mm and a width of 190 mm, and hot melt (trade name: Topco P-618B, Toyo Petrolite Co., Ltd.) is spirally formed thereon. After spraying at a basis weight of 10 g / m ² , 0.5 g of the highly absorbent polymer 2b is spread almost uniformly over a width of 75 mm (spread basis weight of about 38 g / m ² ), wrapped and integrated, and the absorbent polymer Sheet. Further, the absorbent paper 2c was cut into a length of 175 mm and a width of 130 mm, and the absorbent polymer sheet was wrapped and integrated to form an absorbent 2. The obtained absorber 2 was rolled up using polylam waterproofing paper (length 205 mm, width 95 mm) as a leak-proof material 3. The absorbent paper 2c has high liquid permeability. The absorbent paper 2c has a fiber roughness of 0.36 mg /
m, mercerized pulp with a fiber cross-section of roundness of 0.80 (trade name: "POROSANIER-J", ITT Rayonier Inc.
95 parts by weight and polyvinyl alcohol of 1 denier thickness and 3 mm length (trade name: Fibribond, Sansho Co., Ltd.)
5 parts by weight) were dispersed and mixed in water, paper-made using a paper machine, and then dried. The basis weight was 40 g / m ² .

Next, the above-described absorbent body 2 wound up with the leak-proof material 3 was wrapped around the surface material 1 to produce a sanitary napkin having the structure shown in FIG.

As the surface material 1, one having the structure shown in FIG. 5 was used. That is, a laminate obtained by laminating a low-density polyethylene 121 (manufactured by Mitsui Petrochemical Co., Ltd.) having a thickness of 25 μm from a polyethylene / polypropylene composite fiber (manufactured by Chisso Corporation) to a dry heat-bonded nonwoven fabric 122 having a basis weight of 25 g / m ^2. This was cut into a length of 205 mm and a width of 170 mm. On the surface of the nonwoven fabric 122,
0.34% by weight of a mixed surfactant of an alkyl phosphate and a sorbitan fatty acid ester is adhered. In this surface material, as shown in FIG. 5, the size of the opening 124 in the wall 123 is 0.1 to ² mm ² and the density of the holes is 52 holes / cm ² .

With respect to these sanitary napkins, the blood absorption time, the dynamic fluid return amount, and the number of leaks were measured by the following methods. Table 3 shows the results.

[0081]

Comparative Examples 6 to 10 Sanitary napkins were produced in the same manner as in Examples 5 to 8, except that the absorbent sheets (E) to (I) were used. And the number of occurrences of leakage was measured by the method described below. Table 3 shows the results.

<Absorption time (5 g), reabsorption time (10
g), Measurement of dynamic liquid return amount> As shown in FIG. 6, the sanitary napkin 30 obtained in each of Examples and Comparative Examples was placed horizontally,
An acrylic plate 32 having an inlet 31 having a diameter of 10 mm is placed, and a weight 33 is placed on the sanitary napkin 30 for testing so that a load of 5 g / cm ² is applied. Next, defibrinated horse blood (manufactured by Nippon Biotest Laboratory Co., Ltd.) 5
g, and the absorption time (sec) until the liquid is completely absorbed is determined. After the solution was completely absorbed, the solution was allowed to stand for 20 minutes, 5 g of defibrillated horse blood was injected again, the reabsorption time (10 g) was determined, and the solution was similarly allowed to stand for 20 minutes.

Thereafter, an absorbent made of softwood pulp having a basis weight of 30 g / m ² cut into a width of 75 mm and a width of 195 mm was used.
Sheets, the upper surface of the sanitary napkin 30 for testing (skin contact surface side)
8 and the movable female waist model 40 shown in FIG.
After putting on the shorts to which the sanitary napkin 30 was attached as shown in (1), the person was allowed to walk at a walking speed of 100 steps / min (50 m / min) for 1 minute. After walking, sanitary napkin 30
And 10 absorbers were taken out, and the weight of the defibrated horse blood absorbed by the absorber was determined as a liquid return amount (g). The measurement was carried out for each of the five points, and the respective average values were obtained, which were taken as the absorption time, the re-absorption time, and the dynamic liquid return amount.

<Leak Test (Number of Leaks Occurred)> The sanitary napkin 30 for testing obtained in the examples and comparative examples is shown in FIG.
As shown in Fig. 5, the user was mounted on the movable female waist model 40, and after putting on shorts, the subject was allowed to walk at a walking speed of 100 steps / min (50 m / min) for 10 minutes. Then, while walking, the defibrillated horse blood was transferred to the sanitary napkin 30 by a tube.
g for 20 minutes at the same speed after injection,
After that, when 5 g of defibrillated horse blood was injected and the patient was allowed to walk for 20 minutes, the number of leaked samples out of 10 samples was counted.

[0085]

[Table 3]

As is clear from the results shown in Table 3, the absorbent article using the diffusible absorbent paper of the present invention has a re-absorption time of up to 10 g which is assumed to be worn for a long time and excreted in a large amount.
1 to 38 seconds, and the liquid return amount is 0.2 to 0.4 g
It can be seen that this is also particularly superior to the comparative example containing a large amount of the polymer. In addition, the number of times of occurrence of leakage, even if absorbed up to 10 g, the absorbent article using the diffusible absorbent paper of the present invention has excellent performance with a small number of times of occurrence of 1 to 2 times, In the absorbent article using the absorbent sheet of the comparative example, the tested sample showed considerable leakage, indicating that it was inferior to the absorbent article using the diffusible absorbent paper of the present invention.

[0087]

The diffusible absorbent paper of the present invention has a small swelling when wet, can stably maintain the distance between the fibers, and has a performance of rapidly permeating the liquid and a rapid liquid permeation. It also has the ability to diffuse to the surface. Further, the absorbent article comprising the diffusible absorbent paper of the present invention has a high liquid holding capacity and a high transmission speed,
Moreover, it has excellent repetitive absorption. Therefore, even when worn for a long time or when excreted in large quantities, liquid return and liquid leakage are small.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross section in a width direction of an absorbent article provided with a diffusible absorbent paper of the present invention.

FIG. 2 is a diagram showing a cross section in a width direction of an absorbent article provided with the diffusible absorbent paper of the present invention.

FIG. 3 is a schematic diagram showing a device for measuring a Krem absorption height.

FIG. 4 is a schematic diagram showing an apparatus for measuring the passage time of 10 g of an 85% by weight aqueous solution of glycerin.

FIG. 5 is a partially enlarged schematic view of a surface material.

FIG. 6 is a schematic sectional view showing an outline of measurement of absorption time.

FIG. 7 is a schematic diagram showing a movable female waist model.

8 is a schematic diagram showing a state in which a sanitary napkin is attached to the crotch of the movable female waist model shown in FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Surface material 2 Absorber 2b Superabsorbent polymer 2c Absorbing paper 2d Diffusible absorbing paper 3 Leakproofing material 4 Adhesion part 5 Release paper 6 Joining part 10 Sanitary napkin

──────────────────────────────────────────────────続 き Continuation of the front page Examiner Shigemi Sawamura (56) References JP-A-6-287886 (JP, A) JP-A-7-189197 (JP, A) JP-A-3-206176 (JP, A) JP-A-8-13370 (JP, A) JP-A-6-121175 (JP, A) JP-A-6-141760 (JP, A) JP-A-7-197400 (JP, A) JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D21H 11/00-27/42 A41B 13/00-17/00 A61F 13/00-13/84

Claims (11)

(57) [Claims] 1. A cellulose fiber having a fiber roughness of 0.30 to 2 mg / m, which is cross-linked by a cross-linking agent within and / or between molecules, and has a compressive residual strain of less than 40% when wet. A diffusible absorbent paper comprising 20 to 80 parts by weight of a bulky crosslinked cellulose fiber and 80 to 20 parts by weight of a hydrophilic fine fiber. 2. The diffusible absorbent paper according to claim 1, having a basis weight of 20 to 60 g / m ² . 3. The thickness under a load of 2.5 g / m ² is 0.2.
The diffusible absorbent paper according to claim 1, which has a thickness of about 0.8 mm. 4. The diffusible absorbent paper according to claim 1, wherein the Klemm absorption height after 1 minute with respect to physiological saline is 50 mm or more, and the Krem absorption height after 10 minutes is 100 mm or more. 5. The diffusible absorbent paper according to claim 1, wherein the passage time of 10 g of an 85% by weight aqueous glycerin solution is 100 seconds or less. 6. The diffusible absorbent paper according to claim 1, wherein the roundness of the cellulose fiber is 0.5 or more. 7. The diffusible absorbent paper according to claim 6, wherein the cellulose fiber is pulp. 8. The diffusible absorbent paper according to claim 7, wherein the pulp is mercerized pulp. 9. The fiber fineness of the hydrophilic fine fibers is 0.2 mg /
2. The diffusible absorbent paper according to claim 1, wherein the average particle diameter is less than m. 10. The diffusible absorbent paper according to claim 1, wherein the roundness of the hydrophilic fine fibers is less than 0.5. 11. The diffusible absorbent paper according to claim 1, further comprising up to 30 parts by weight of a heat-fusible adhesive fiber.