JPH08232189A - Absorbent paper and its production - Google Patents

Abstract

PURPOSE: To provide absorbent paper large in liquid-absorbing space, high in liquid absorption permeability, and high in liquid diffusivity. CONSTITUTION: This absorbent paper 11 is composed of bulky cellulose fibers 12 and hydrophilic fine fibers or fine powder 13. In this paper 11, the proportion of the hydrophilic fine fibers or fine powder on one side of this paper is higher than that on the other side. Besides, this paper 11 has the following characteristics the average fiber length of the cellulose fibers is 1-20mm; the average fiber length of the hydrophilic fine fibers is 0.02-0.5mm; and the average particle diameter of the hydrophilic: fine powder is 0.02-0.5mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to absorbent paper and a method for manufacturing the same, and more particularly to absorbent paper having excellent liquid absorption permeability and liquid diffusivity and a method for manufacturing the same.

[0002]

2. Description of the Related Art Regarding absorbent articles such as disposable diapers, sanitary napkins and pads for incontinence, many techniques aimed at improving the absorbability of body fluids have been proposed and improved. Has been done. And
Most of these improvements were in improving the liquid absorption rate, preventing the liquid from returning from the absorber to the surface material, preventing liquid leakage, and reducing the stickiness of the absorbent article to the body.

For example, regarding the material of the absorbent body, instead of using hydrophilic absorbent paper or pulp which absorbs and holds the liquid in the physical fine space, the liquid is subjected to a physicochemical action, that is, It has been proposed to use a super-absorbent polymer that improves the liquid absorption capacity by absorbing and holding the liquid by ionic osmotic pressure and prevents the liquid from returning after absorbing the liquid. By using a superabsorbent polymer, the liquid absorbency is improved, and at present, most absorbent articles use an absorbent body in which pulp and a superabsorbent polymer are used in combination.

However, even with such an absorbent article, liquid leakage prevention is still insufficient, as suggested by the fact that the first dissatisfaction with the absorbent article is liquid leakage.

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

[0006] Further, while pulp exhibits a certain degree of compression recovery and bending recovery when it is dried, its strength is extremely reduced when it is wet, and it hardly shows those recovery properties. Therefore, when stress is applied to the wet pulp, The pulp is compressed and deformed (hereinafter referred to as “break”), and the liquid absorption space is significantly reduced. As a result, the once absorbed liquid easily returns to the body side due to the twist, which causes stickiness and liquid leakage.

Further, the liquid absorption space is reduced due to this twisting, whereby the movement resistance when the liquid moves to the polymer is increased. As a result, not only the liquid absorption efficiency of the polymer is lowered, but also the re-absorption rate of the entire absorbent body after twisting is significantly reduced, which often causes liquid leakage.

In order to improve the poor diffusibility of these fluff pulps and the reduction of the liquid absorption space due to twisting, a technique for improving the diffusivity and the liquid return property by compressing / densifying the pulp is also used. Have been reported up to. However, these techniques do not solve the essential problem that the strength of pulp becomes extremely low when it gets wet, and conversely, the distance between fibers of pulp becomes too close, so that liquid becomes a polymer. The movement resistance at the time of movement greatly increases, resulting in a disadvantage that the liquid absorption efficiency of the polymer deteriorates. That is, in the absorber made of fluff pulp, the liquid absorbency and the diffusibility were not compatible with each other, and the absorbency / leak prevention property was still insufficient.

On the other hand, most of the above-mentioned absorbent paper is absorbent paper obtained by wet-making natural pulp. However, the absorbent paper manufactured by such a method has a strong interfacial tension between water and pulp due to hydrogen bond during pulp dehydration and drying during dehydration / wet pressure / drying process during papermaking. Works. Due to this tightening force, the pulp fibers are tightly tightened. As a result, the absorbent paper obtained by wet papermaking of pulp fibers not only has a very slow liquid absorption / permeation, but also the pulp fiber space that substantially absorbs the liquid is extremely reduced.

There has also been attempted a method of improving the bulkiness of the absorbent paper by creping or embossing the absorbent paper. However, in such a method, only the apparent thickness of the absorbent paper is improved, the liquid absorption space composed of pulp fibers is hardly increased, and the liquid absorption / permeability is not improved.

Also, an absorbent paper mainly composed of bulky cellulose fibers has been proposed. Since such an absorbent paper has a large fiber-to-fiber distance, it is excellent in the liquid absorption rate and the liquid transmission rate, but is inferior in the liquid diffusivity. Therefore, the liquid stays on the surface of the absorbent paper, and the surface of the absorbent paper lacks the slat feel. Furthermore, if pressure is applied while absorbing the liquid, liquid return easily occurs. On the other hand, absorbent paper mainly composed of softwood pulp or hardwood pulp having a small fiber diameter has also been proposed. Since such absorbent paper has a high density, it is excellent in liquid absorbability and liquid diffusibility due to the capillary phenomenon, but it is inferior in liquid permeability, so that the liquid remains retained on the surface of the absorbent paper and the salat of the absorbent paper surface is Lack of feeling. As described above, it is difficult to develop the liquid absorbing and transmitting properties and the liquid diffusing property with only one sheet of absorbent paper.

Attempts have also been made to manufacture bulky absorbent paper by using a dry method such as the air ray method for manufacturing the absorbent paper.
That is, bulky absorbent paper is manufactured by depositing pulp in bulk and binding it with an appropriate binder. According to this method, it is possible to obtain absorbent paper having a very low density when dried, a large distance between pulp fibers, and a large liquid absorption space. Such an absorbent paper has a large liquid absorbing space even when absorbing liquid, but has a drawback that its diffusivity is very poor. Further, when the absorbent paper is under pressure while being wet with a liquid, there is a problem in that, like the fluff pulp, twisting / sagging occurs.

Cellulose non-woven fabrics such as rayon spunbond are also used as absorbent paper. Since the non-woven fabric is composed of single fibers, the function of the non-woven fabric absorbent paper is such that the liquid diffusivity and the liquid absorptivity are in a contradictory relationship. That is, the diffusibility of the liquid tends to be improved by decreasing the fiber diameter of the single fiber, but this also reduces the distance between the fibers, and therefore the liquid absorption and permeability is deteriorated. On the contrary, when the fiber diameter of the single fiber is increased, the liquid absorption and permeability are improved, but the liquid diffusibility is deteriorated. As described above, the absorbent paper using the non-woven fabric cannot satisfy both the liquid diffusibility and the liquid absorption and permeability.

Japanese Patent Laid-Open No. 4-89053 discloses a highly absorbent and ultrathin structure in which an absorbent body is formed by combining various absorbent papers having different liquid absorption and liquid diffusivity and a highly absorbent polymer. Absorbent articles are disclosed. However, in such absorbent articles, temporary absorption / permeation / permeation /
Since each function of the absorbent article of diffusion / holding is assigned to each of the constituent members such as the absorbent paper and the superabsorbent polymer forming the absorbent body, there is a drawback that the structure of the absorbent body becomes complicated, and the cost is reduced. There is a problem called up.

Therefore, an object of the present invention is to provide an absorbent paper having a large liquid absorbing space, a high liquid absorbing and transmitting property, and a high liquid diffusing property, and a manufacturing method thereof.

[0016]

Means for Solving the Problems As a result of intensive studies, the inventors of the present invention have found that an absorbent paper obtained by combining specific fibers and providing a gradient in the abundance ratio has liquid diffusibility and liquid absorption / permeability. It was found that they have both properties of.

The present invention has been made based on the above findings, and is an absorbent paper containing bulky cellulose fibers and hydrophilic fine fibers or hydrophilic fine powders, wherein the hydrophilic fine fibers are Alternatively, the hydrophilic fine powder has an abundance ratio on one surface side of the absorbent paper higher than an abundance ratio on the other surface side, and the average fiber length of the bulky cellulose fibers is 1 to 20 mm, An average fiber length of the hydrophilic fine fibers is 0.02 to 0.5 mm, and an average powder particle diameter of the hydrophilic fine powder is 0.02 to 0.5 mm. The above-mentioned object is achieved by providing an absorbing paper.

Further, the present invention is a preferred method for producing the absorbent paper of the present invention, wherein the bulky cellulose fibers having an average fiber length of 1 to 20 mm and the average fiber length of 0.02 to 0.02.
A step of forming a slurry by dispersing hydrophilic fine fibers having a diameter of 0.5 mm or hydrophilic fine powder having an average powder particle diameter of 0.02 to 0.5 mm in water to form a slurry; Disclosed is a method for producing absorbent paper, which comprises the steps of spraying the paper wire on the papermaking wire to form a paper layer on the papermaking wire, and dehydrating and drying the paper layer.

The absorbent paper of the present invention is useful as a puerperium pad, a breast milk pad, an underpad, a sweat absorbing sheet, an absorbent turban for a perm, a drip sheet, a medical pad and an undersheet for a bed. It is useful as an absorbent body for absorbent articles such as napkins and disposable diapers.

[0020]

As described above, the absorbent paper of the present invention contains bulky cellulose fibers and hydrophilic fine fibers or hydrophilic fine powder. The above-mentioned bulky cellulose fiber forms a bulky network structure in the absorbent paper of the present invention. On the other hand, the hydrophilic fine fibers or hydrophilic fine powders have a higher abundance ratio on one side of the absorbent paper of the present invention than on the other side. As a result, the surface side where the hydrophilic fine fibers or the hydrophilic fine powder is present in a low proportion is excellent in the liquid absorption rate and the local liquid absorbency, and at the same time, the liquid permeation is high. On the other hand, the surface side having a high proportion of the hydrophilic fine fibers or the hydrophilic fine powder, because the hydrophilic fine fibers or the hydrophilic fine powder has a high surface area, Excellent liquid diffusivity. Therefore, it is possible to quickly diffuse the liquid that has permeated the surface side where the hydrophilic fine fibers or the hydrophilic fine powder is present in a low proportion. As described above, the absorbent paper of the present invention has both a liquid absorbing and transmitting property and a liquid diffusing property even though it has a single structure. Thus, since the absorbent paper of the present invention has the liquid absorption / diffusion gradient in its single structure, the liquid absorption rate is high, and the liquid spot absorptivity as well as the liquid permeability and diffusion. It has excellent properties and, as a result, has a very high surface slatiness.

According to the method for producing absorbent paper of the present invention, the difference in fiber length and fiber diameter between the bulky cellulose fiber and the hydrophilic fine fiber or the hydrophilic fine powder is utilized. As a result, a gradient can be provided particularly easily with respect to the abundance ratio of the hydrophilic fine fibers or the hydrophilic fine powder in the thickness direction of the absorbent paper of the present invention. As a result, the absorbent paper can be easily manufactured by a single process.

Further, an absorbent article constituted by using the absorbent paper of the present invention has a function of the absorbent paper, from a liquid-permeable surface material to a super-absorbent polymer present in a liquid-retaining absorber. The flow of liquid can be idealized, it has extremely high absorbency, there is little liquid leakage, and it is extremely thin, which makes it easy to wear.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the absorbent paper of the present invention will be described in detail with reference to the drawings together with a preferable manufacturing method thereof. Here, FIG. 1 is a schematic view showing a cross section in the thickness direction of the absorbent paper of the present invention, and FIG. 2 is a schematic view showing a state of liquid absorption / diffusion by the absorbent paper of the present invention.

As shown in FIG. 1, the absorbent paper 11 of the present invention is
The bulky cellulose fiber 12 and the hydrophilic fine fiber 13 or the hydrophilic fine powder 13 are included, and the hydrophilic fine fiber 13 or the hydrophilic fine powder 13 is one surface of the absorbent paper 11. The abundance ratio on one side is higher than the abundance ratio on the other side, the average fiber length of the bulky cellulose fibers 12 is 1 to 20 mm, and the average fiber length of the hydrophilic fine fibers 13 is 0.02. Is 0.5 mm, and the average particle diameter of the hydrophilic fine powder 13 is 0.0.
It is characterized in that it is 2 to 0.5 mm.

As shown in FIG. 1, the hydrophilic fine fibers 13 or the hydrophilic fine powder 13 contained in the absorbent paper 11 of the present invention has a gradient in the distribution in the thickness direction of the absorbent paper 11. have. That is, in the thickness direction of the absorbent paper 11, the hydrophilic fine fibers 13 or the hydrophilic fine powders 13 are present on the one surface side of the absorbent paper 11 on the other surface side. It is higher than the ratio. In the following description, of the surfaces of the absorbent paper 11, the surface having a lower proportion of the hydrophilic fine fibers 13 or the hydrophilic fine powder 13 is referred to as the “surface”,
The surface having a higher abundance ratio of the hydrophilic fine fibers 13 or the hydrophilic fine powder 13 is referred to as a "back surface".

As shown in FIG. 2, the absorbent paper 11 of the present invention is
Since the bulky cellulose fibers 12 are mainly contained in the area from the “front surface” to the vicinity of the “front surface”, the liquid (indicated by an arrow in FIG. 2) is quickly absorbed and the “back surface” is formed.
It has the function of quickly permeating liquid. That is, this region mainly functions as an "absorption-permeation layer" for the liquid.
On the other hand, since the hydrophilic fine fibers 13 or the hydrophilic fine powder 13 is the main component from the “back surface” to the vicinity of the “back surface”, the liquid that has permeated from the “front surface” is quickly diffused. It has the function of That is, this region primarily functions as a "diffusion layer" for liquids. As described above, the absorbent paper 11 of the present invention is characterized by having both the absorption and transmission layer and the diffusion layer in a single structure, and as a result,
It has a high liquid absorbency, and its surface is extremely dry after absorbing the liquid (feeling of slat).

As mentioned above, the "front surface" and the "back surface".
There is a large difference in the diffusibility of the liquid between. That is, on the "back surface" side (diffusion layer) where the hydrophilic fine fibers or the hydrophilic fine powder is the main component, the liquid diffuses quickly. On the other hand, on the "surface" side (absorption / permeation layer) where the bulky cellulose fiber is the main component, the absorption and transmission of liquid is rapid, but the diffusion of liquid is not so rapid. That is, the absorbent paper of the present invention has a diffusion gradient with respect to the diffusion of the liquid in the thickness direction. Therefore, for example, when the diffusion area when the absorbent paper of the present invention absorbs 1 g of physiological saline is adopted as a measure of the diffusibility of the liquid, the diffusion area on the "back surface" side is the "front surface".
It is larger than the diffusion area on the side. In the present invention, the ratio of the diffusion area on the "back surface" side to the diffusion area on the "front surface" side in the absorbent paper of the present invention is preferably 1.2 or more, and more preferably 1.5 to. 20 and particularly preferably 2 to 20. The details of the method for measuring the diffusion area will be described later.

The presence ratio of the hydrophilic fine fibers or the hydrophilic fine powder in the absorbent paper of the present invention may be gradually increased from the "front surface" to the "back surface". The thickness may increase stepwise.

On the other hand, the above-mentioned bulky cellulose fibers may be present uniformly in the thickness direction of the absorbent paper of the present invention, but it is more preferable that the "back surface" side of the absorbent paper of the present invention is "more". The existence ratio is higher on the "front surface" side. That is, it is preferable that the abundance ratio of the bulky cellulose fibers has a gradient in the thickness direction of the absorbent paper of the present invention. The existence ratio may be gradually increased from the “rear surface” to the “front surface”, or may be increased stepwise with a certain thickness as a boundary.

More specifically, the "back surface" of the absorbent paper of the present invention.
From the side to a depth of about 1/3 in the thickness direction, the hydrophilic fine fibers or the hydrophilic fine powder is preferably about 5 to about 70% by weight, more preferably about 5% by weight based on the total amount. 1
0 to about 50% by weight is present, and the diffusion layer mainly composed of the hydrophilic fine fibers or the hydrophilic fine powder is formed. On the other hand, the bulky cellulosic fibers are preferably contained in an amount of about 60 to about 100% by weight, based on the total amount thereof, at a depth of about 2/3 in the thickness direction from the "surface" side of the absorbent paper of the present invention. It is preferably present in an amount of about 70 to about 97% by weight, and the absorptive and permeable layer mainly composed of the bulky cellulose fiber is formed.

As described above, the distribution of the bulky cellulose fiber and the hydrophilic fine fiber or the hydrophilic fine powder may be gradually increased in the thickness direction of the absorbent paper of the present invention. Alternatively, the thickness may increase stepwise with a certain thickness as a boundary. And, in the absorbent paper of the present invention, both the bulky cellulose fibers and the hydrophilic fine fibers or the hydrophilic fine powder have a gradient in the distribution in the thickness direction of the absorbent paper. In a preferred embodiment, liquid absorption and permeability and liquid diffusivity can be more significantly exhibited.

As described above, the absorbent paper of the present invention mainly has a "front surface" side for absorbing and transmitting liquid and a "rear surface" side for diffusing liquid. Therefore, when using the absorbent paper of the present invention, it is preferred that the "front" side of the absorbent paper be the side that comes into contact with the liquid first.

In the absorbent paper of the present invention, the compounding ratio of the above-mentioned bulky cellulose fiber and the above hydrophilic fine fiber or the above hydrophilic fine powder is not particularly limited, but the above bulky cellulose fiber is 50 to 97 parts by weight based on 100 parts by weight of the absorbent paper of the present invention is preferably contained.
It is even more preferable that the content is 0 to 95 parts by weight. If the blending ratio of the above-mentioned bulky cellulose fibers is less than 50 parts by weight, the bulky network structure may be insufficient and an absorbent paper having both transmission and diffusion may not be obtained. If the blending ratio exceeds 97 parts by weight,
The blending ratio of the hydrophilic fine fibers or the hydrophilic fine powder becomes low, and the diffusibility becomes insufficient. Therefore, the above range is preferable.

The hydrophilic fine fibers or the hydrophilic fine powder is preferably contained in an amount of 3 to 50 parts by weight, preferably 5 to 30 parts by weight, based on 100 parts by weight of the absorbent paper of the present invention. It is even more preferable. If the blending ratio of the hydrophilic fine fibers or the hydrophilic fine powder is less than 3 parts by weight, the diffusivity becomes insufficient, and the blending ratio of the hydrophilic fine fibers or the hydrophilic fine powder is insufficient. When it exceeds 50 parts by weight, the compounding ratio of the hydrophilic fine fibers or the hydrophilic fine powder on the "surface" side increases and the permeability becomes insufficient. Therefore, the above range is preferable.

If desired, the absorbent paper of the present invention may contain heat-meltable adhesive fibers which are melted by heating and adhered to each other. By adding such a heat-meltable adhesive fiber, it is possible to maintain the structural stability of the absorbent paper of the present invention when it is wet.

It is preferable to add 2 to 30 parts by weight, and more preferably 3 to 20 parts by weight of the above-mentioned heat-meltable adhesive fiber based on 100 parts by weight of the absorbent paper of the present invention. If the amount added is less than 2 parts by weight, the strength of the absorbent paper of the present invention becomes insufficient when the liquid is actually absorbed, and the bulky cellulose fiber and the hydrophilic fine fiber or the hydrophilicity in the absorbent paper of the present invention are added. In some cases, the mixing state with the fine powder is changed and the diffusion gradient cannot be maintained. On the other hand, if the addition amount exceeds 30 parts by weight, the hydrophilicity of the entire absorbent paper may be lowered, and the liquid absorption rate and the liquid diffusing ability may become insufficient, so the above range is preferable.

Other optional components that can be added to the absorbent paper of the present invention include, for example, other pulps such as softwood pulp, hardwood pulp and straw pulp, and dialdehyde starch, sponge and carboxymethyl cellulose as a strong auxiliary agent. Can be mentioned. These components can be added in an amount of 0 to 20 parts by weight based on 100 parts by weight of the absorbent paper of the present invention.

The basis weight of the absorbent paper of the present invention is not particularly limited, but is preferably 10 to ²⁰⁰ g / m ² , and 20
More preferably, it is about 150 g / m ² . Basis weight is 1
If it is less than 0 g / m ² , the absorbent paper may be too thin to exhibit the functions of transmission and diffusion. If the basis weight exceeds 200 g / m ² , the absorbent paper may be thicker. It may be difficult for smooth passage of liquid such as passing, diffusion and diffusion to occur, so the above range is preferable.

The thickness of the absorbent paper of the present invention is not particularly limited, but the thickness under a load of 2.5 g / m ² is preferably 0.2 to 2 mm, more preferably 0.2 to 1 mm. preferable. If the thickness is less than 0.2 mm, the absorbent paper may be too thin to exhibit the functions of transmission and diffusion. If the thickness exceeds 2 mm, smooth transmission of liquid, transmission and diffusion, may occur. Since it may be difficult to occur, the above range is preferable.

In a preferred embodiment of the absorbent paper of the present invention, 50 to 97 parts by weight of the bulky cellulose fiber, and the hydrophilic fine fiber or the hydrophilic fine fiber are used based on 100 parts by weight of the absorbent paper. Includes 3 to 50 parts by weight of powder.

In a particularly preferred embodiment of the absorbent paper of the present invention, based on 100 parts by weight of the absorbent paper, 70 to 95 parts by weight of the bulky cellulose fiber, the hydrophilic fine fiber or the hydrophilic fine fiber is used. 5 to 30 parts by weight of fine powder, and 2 to 30 parts by weight of the above heat-meltable adhesive fiber;
The basis weight of the absorbent paper is 10 to 200 g / m ² .

The absorbent paper of the present invention is preferably produced by the method described below. That is, the absorbent paper of the present invention,
As shown in FIG. 3, the above-mentioned bulky cellulose fibers 12 having an average fiber length of 1 to 20 mm and an average fiber length of 0.02 to
A step of dispersing the hydrophilic fine fibers 13 of 0.5 mm or the hydrophilic fine powder 13 having an average powder particle diameter of 0.02 to 0.5 mm in water to form a slurry 14. A step of spraying the slurry 14 on the papermaking wire 15 to form a paper layer 16 on the papermaking wire 15;
And a step of dehydrating and drying the paper layer 16 described above.

Thus, the absorbent paper of the present invention is preferably produced by the wet papermaking method. The wet paper machine is not particularly limited, and for example, a round net paper machine, a former paper machine, and a Fourdrinier paper machine can be used.

The papermaking method will be described in more detail with reference to FIG. 4, which is an enlarged view of the portion (a) of FIG. When the slurry 14 is sprinkled on the papermaking wire 15, the water in the slurry 14 is removed through the papermaking wire 15 and at the same time the paper layer 16 is formed on the papermaking wire 15.
Is formed. In the paper layer 16, the bulky cellulose fibers 12 form a bulky network structure 17 in the thickness direction as shown in FIG. On the other hand, since the hydrophilic fine fibers 13 or the hydrophilic fine powder 13 in the slurry 14 is finer than the bulky cellulose fibers 12, it passes through the network structure 17 together with water, and Deposit on the papermaking wire 15. As a result, the hydrophilic fine fibers 13 or the hydrophilic fine powder 13 has a gradient in the distribution in the thickness direction of the absorbent paper 11. That is, as shown in FIG. 4, of the surface of the paper layer 16, the papermaking wire 1
The hydrophilic fine fibers 1 on the side in contact with 5
3 or the existence ratio of the hydrophilic fine powder 13 is higher than the existence ratio on the other surface.

As described above, in the preferred method for producing absorbent paper of the present invention, the bulky cellulose fiber 12 is used.
And the hydrophilic fine fibers 13 or the hydrophilic fine powder 13 are used to make use of the difference in fiber length and fiber diameter between the hydrophilic fine fibers 13 in the thickness direction of the absorbent paper of the present invention.
Alternatively, a gradient is provided in the existing ratio of the hydrophilic fine powder 13.

The concentration of the bulky cellulose fibers 12 in the slurry is preferably 0.02 to 1% by weight, more preferably 0.03 to 0.7% by weight, based on the total amount of the slurry. Is. If the concentration of the bulky cellulose fibers 12 is less than 0.02% by weight, the desired permeation rate becomes insufficient, or the amount of waste water for obtaining the desired basis weight becomes too large, resulting in energy loss. If the concentration of the bulky cellulose fiber 12 exceeds 1% by weight, the dispersibility of the fiber deteriorates,
Since unevenness of the paper layer may occur, the above range is preferable.

On the other hand, the concentration of the hydrophilic fine fibers 13 or the hydrophilic fine powder 13 in the slurry is preferably 0.00 based on the total amount of the slurry.
2 to 0.5% by weight, and more preferably 0.003
Is about 0.3% by weight. The concentration of the hydrophilic fine fibers 13 or the hydrophilic fine powder 13 is 0.002% by weight.
If the content is less than the above, the desired diffusivity may not be obtained, and if the concentration of the hydrophilic fine fibers 13 or the hydrophilic fine powder 13 exceeds 0.5% by weight, the "surface" is obtained. The hydrophilic fine fibers 13 or the hydrophilic fine powder 13 may be present on the side as well, and the desired diffusion gradient may not be obtained, so the above range is preferable.

The concentration of the above-mentioned heat-meltable adhesive fiber which is optionally used in the absorbent paper of the present invention in the above-mentioned slurry is preferably 0.001 to 0.3% by weight, and 0.002 to 0.002% by weight. More preferably, it is 0.2% by weight. If the above concentration is less than 0.001% by weight, the purpose of keeping the structure of the absorbent paper stable may not be achieved, and if the above concentration exceeds 0.3% by weight, the hydrophilicity of the entire absorbent paper will be reduced. In some cases, the above range is preferable.

As described above, in the preferred method for producing absorbent paper of the present invention, when the slurry 14 is sprinkled on the papermaking wire 15, the bulky cellulose fiber 1 is obtained.
The bulky network structure 17 composed of 2 is formed, and the hydrophilic fine fibers 13 or the hydrophilic fine powders 13 pass through the space in the bulky network structure 17 and are deposited on the papermaking wire 15. . For this purpose, it is important to make the average fiber length of the hydrophilic fine fibers 13 or the average powder particle diameter of the hydrophilic fine powder 13 larger than the mesh of the papermaking wire 15. When the average fiber length of the hydrophilic fine fibers 13 or the average powder particle diameter of the hydrophilic fine powder 13 is smaller than the mesh 15 of the papermaking wire, the hydrophilic fine fibers 13 or the hydrophilic fine particles 13 Since the fine powder 13 of No. 3 passes through the papermaking wire 15, a gradient is provided in the abundance ratio of the hydrophilic fine fibers 13 or the hydrophilic fine powder 13 in the thickness direction of the absorbent paper of the present invention. This is not preferable because it is no longer possible. If the mesh of the papermaking wire 15 is too small, the hydrophilic fine fibers 13 or the hydrophilic fine powder 13 will be clogged on the papermaking wire 15, which is not preferable. Therefore, the opening diameter of the papermaking wire is 22 to 300 μm (580 to 50 mesh).
Is preferable and 45 to 250 μm (330 to 6
0 mesh) is more preferable (new JIS (1
987)).

According to the above-described preferred method for producing the absorbent paper of the present invention, a gradient is provided in the distribution of the hydrophilic fine fibers 13 or the hydrophilic fine powder 13 in the thickness direction of the absorbent paper of the present invention. It can be provided particularly easily. The degree of such a gradient depends on the speed (water removal speed) when the paper layer 16 formed on the papermaking wire 15 is dehydrated.
That is, although depending on the papermaking speed and the basis weight of the absorbent paper, when the dehydration speed is low, the degree of the gradient becomes small, and as a result, in the thickness direction of the absorbent paper of the present invention, the hydrophilic fine fibers are used. 13 or the hydrophilic fine powder 13 may be distributed almost uniformly. On the other hand, when the dehydration rate is high, the degree of the gradient becomes large, which is preferable, but a large amount of energy is required to increase the dehydration rate. Considering these, in the present invention, the dehydration rate is preferably ² ml / [cm ² · sec] or more, more preferably 3 to 30 ml / [cm ² · sec]. At the time of dehydration, for example, a suction box used in an ordinary wet paper machine can be used.

According to the above-mentioned method, it is possible to manufacture the absorbent paper which can exhibit the liquid absorption and the permeability and the liquid diffusivity in one papermaking process, and the papermaking process can be simplified. .

Although the method for producing the absorbent paper of the present invention has been described based on its preferred embodiment, the method for producing the absorbent paper of the present invention is not limited to the above-mentioned embodiment, and other embodiments, for example, dry papermaking. The absorbent paper of the present invention can also be produced by a method or the like.

As another manufacturing method, a fiber web is formed from bulky cellulose fibers, and then hydrophilic fine fibers or hydrophilic fine powder is sprinkled on the web, and then dried and integrated. By doing so, an absorbent paper having a bulky cellulose fiber layer on one side and a hydrophilic fine fiber or hydrophilic fine powder-based layer on the other side can be obtained. According to this method, it is possible to manufacture an absorbent paper in which the abundance ratio of the bulky cellulose fiber and the hydrophilic fine fiber or the hydrophilic fine powder in the thickness direction changes stepwise.

Next, the bulky cellulose fibers used in the absorbent paper of the present invention will be described in detail.

In the absorbent paper of the present invention, it is preferable that a network structure of the bulky cellulose fiber is formed. Such a network structure is a particularly preferred structure because it quickly absorbs liquid and allows liquid to quickly permeate to the "back" side. For this purpose, the bulky cellulose fibers 13 have an average fiber length of 1 to 20 mm.
The average fiber length is preferably 2 to 1
The average fiber length is 0 mm, and the more preferable average fiber length is 2 to 5 mm. If the average fiber length is less than 1 mm, the above bulky network structure cannot be formed, and the hydrophilic fine fibers or the hydrophilic fine powder may pass through between the bulky network structures. Can not. When the average fiber length exceeds 20 mm, dispersibility in water deteriorates and a uniform network structure cannot be formed.

As the bulky cellulose fiber, any cellulose fiber may be used as long as it is bulky.
As the cellulose fiber, for example, natural cellulose such as wood pulp or cotton, regenerated cellulose such as rayon or cupra can be used. From the viewpoint of cost, it is preferable to use wood pulp, and particularly softwood kraft pulp is preferably used. These cellulose fibers may be used alone or in combination of two or more.

A preferable example of the bulky cellulose fiber is a crosslinked cellulose fiber obtained by crosslinking the inside and / or the inside of the cellulose fiber. Such crosslinked cellulose fibers are preferable because they can maintain a bulky structure even in a wet state. A more preferable bulky cellulose fiber is
A crosslinked pulp, and a more preferable bulky cellulose fiber is a crosslinked pulp obtained by crosslinking a pulp having an average fiber length of 2 to 5 mm.

The method for crosslinking the cellulose fibers is not particularly limited, and examples thereof include a crosslinking method using a crosslinking agent. Examples of such cross-linking agents include N-methylol compounds such as dimethylol ethylene urea and dimethylol dihydroxy ethylene urea; polycarboxylic acids such as citric acid, tricarballylic acid and butane tetracarboxylic acid; polyols such as dimethyl hydroxyethylene urea. ;
Examples thereof include cross-linking agents for polyglycidyl ether compounds. In particular, a cross-linking agent of a polycarboxylic acid or a polyglycidyl ether-based compound that does not generate formalin or the like which is harmful to the human body during cross-linking is preferable.

The amount of the cross-linking agent used is preferably 0.2 to 20 parts by weight with respect to 100 parts by weight of the cellulose fiber. If the amount used is less than 0.2 parts by weight, the cross-linking density of the cellulose fibers is low, so the elastic modulus may decrease significantly when wet, and if the amount used exceeds 20 parts by weight, the cellulose fibers will be Since the cellulose fiber may become too rigid and become brittle when stressed, the above range is preferable.

In order to crosslink the above-mentioned cellulose fibers with the above-mentioned crosslinking agent, for example, an aqueous solution of the above-mentioned crosslinking agent is impregnated with the above-mentioned cellulose fibers by adding a catalyst to the aqueous solution of the above-mentioned crosslinking agent to design an aqueous solution of the crosslinking agent. The cellulose fibers are dehydrated so that the adhesion amount is obtained, and then heated to the crosslinking temperature, or
Alternatively, an aqueous solution of a cross-linking agent is sprayed onto the above-mentioned cellulose fibers by spraying or the like so as to have a designed adhesion amount, and then heated to a cross-linking temperature to cause a cross-linking reaction.

The bulky cellulose fibers preferably have an average fiber length of 1 to 20 mm and a fiber roughness of 0.3 mg / m or more. Such cellulose fibers are preferable because the cellulose fibers are accumulated in a bulky state and the bulky network structure is easily formed.

In the present invention, the "fiber roughness" means a fiber having a non-uniform thickness, such as wood pulp.
It is used as a scale representing the thickness of the fiber, and for example, a fiber roughness meter (F manufactured by KAJANNI ELECTRONICS LTD.
S-200).

As described above, with respect to the fiber roughness, the bulky cellulose fiber preferably has a fiber roughness of 0.3 mg / m or more, more preferably 0.3 to 10.
2 mg / m, more preferable fiber roughness is 0.32-1
It is mg / m.

Examples of cellulose fibers having a fiber roughness of 0.3 mg / m 2 or more include softwood kraft pulp [Federal Pa]
"ALBACEL" (brand name) made by per Board Co., and PTI
"INDORAYON" (product name) made by ntiIndorayon Utama]
Etc.

The bulky cellulose fiber preferably has a roundness of the fiber cross section of 0.5 to 1. Cellulose fibers having a roundness of the fiber cross section of 0.5 to 1
It is preferable because the liquid has a low resistance to movement and a high liquid permeation rate. More preferably, the roundness is 0.55 to 1. The method for measuring the roundness of the fiber cross section will be described later.

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 the delignification treatment, and most of the roundness thereof is less than 0.5. In order to make the roundness of such a wood pulp 0.5 or more, for example, the wood pulp having an average fiber length of 1 to 20 mm may be mercerized to swell the cross section of the wood pulp.

As described above, the roundness of the fiber cross section is 0.5 to
As the cellulose fiber of 1, mercerized pulp having a circularity of 0.5 to 1 obtained by mercerizing wood pulp is preferable. Examples of commercially available mercerized pulps that can be used in the present invention include ITT Rayoni
er Inc.'s "FILTRANIER" (product name) and the company's "PO"
ROSANIER ”(brand name) and the like.

In the present invention, it is also preferable to use a crosslinked mercerized pulp obtained by crosslinking the above mercerized pulp by the above method.

In the present invention, the average fiber length is 2
Cellulose fibers (pulp) having a fiber roughness of 0.3 mm / m or more and a roundness of the fiber cross section of 0.5 to 1 are also preferable.

More preferable bulky cellulose fibers have an average fiber length of 2 to 5 mm and a fiber roughness of 0.3 mg.
/ M or more and the roundness of the cross section of the fiber is 0.5 to 1, which is crosslinked by the above-mentioned method.

Particularly preferred bulky cellulose fibers have an average fiber length of 2 to 5 mm and a fiber roughness of 0.3.
A pulp having a mg / m or more is mercerized to have a circularity of a fiber cross section of 0.5 to 1, and then crosslinked by the above-mentioned method.

Next, the hydrophilic fine fibers and the hydrophilic fine powder used in the absorbent paper of the present invention will be described in detail.

The surface of the hydrophilic fine fibers is hydrophilic, and the average fiber length thereof is 0.02 to 0.5 mm, preferably 0.03 to 0.3 mm. On the other hand, the hydrophilic fine powder has a hydrophilic surface and an average powder particle size of 0.02 to 0.5 mm, preferably 0.03 to 0.3.
mm. The average fiber length of the hydrophilic fine fibers is 0.0
If the average particle size of the hydrophilic fine powder is less than 2 mm or less than 0.02 mm, the hydrophilic fine fiber or the hydrophilic fine powder may be used in the above-described preferred method for producing the absorbent paper of the present invention. Will slip through the papermaking wire, and the hydrophilic fine fibers or the hydrophilic fine powder cannot be deposited on the papermaking wire. Further, when the average fiber length of the hydrophilic fine fibers exceeds 0.5 mm or the average powder particle diameter of the hydrophilic fine powder exceeds 0.5 mm, the above-mentioned absorbent paper of the present invention is preferable. In the manufacturing method, the hydrophilic fine fibers or the hydrophilic fine powder cannot pass through the network structure formed by the bulky cellulose fibers and cannot be deposited on the papermaking wire. In the present invention,
Since the hydrophilic fine fibers and the hydrophilic fine powder are not generally clearly distinguished and used,
Both expressions are used for convenience.

The hydrophilic fine fibers and the hydrophilic fine powder are not particularly limited as long as the above requirements are satisfied. For example, cellulose fiber and cellulose powder such as pulp, cotton and rayon; hydrophilic synthetic fiber such as polyacrylonitrile and polyvinyl alcohol; inorganic fiber and inorganic powder such as kaolin, bentonite and hydrotalcite can be used. . These hydrophilic fine fibers and the above hydrophilic fine powders may be used alone or in combination of two or more. Further, the hydrophilic fine fibers and the hydrophilic fine powder may be mixed and used.

As the hydrophilic fine fibers and the hydrophilic fine powder, commercially available products can be used.
For example, pulp floc (trade name) manufactured by Sanyo Kokusaku Pulp Co., Ltd., which is obtained by beating wood pulp such as softwood pulp and hardwood pulp, then mechanically crushing and then separating with a sieve of 0.5 mm or less, etc. To be As another example, cellulose fine fibers (powder) obtained by mechanically crushing cellulose fibers such as wood pulp, then hydrolyzing with acid, and then mechanically crushing (manufactured by Sanyo Kokusaku Pulp Co., Ltd.) K
C Flock (trade name) and Avicel (trade name) manufactured by Asahi Kasei Co., Ltd.]. In addition, as commercially available inorganic fine fibers, hydrous magnesium silicate fibers [ATE PLUS ML-30 (trade name) manufactured by Mizusawa Chemical Industry Co., Ltd.]
Etc. Among these commercially available products, cellulose fine fibers and cellulose fine powder obtained by pulverizing pulp into fine particles can be obtained at a lower cost and can be preferably used.

Next, the above-mentioned heat-meltable adhesive fiber which is optionally used in the absorbent paper of the present invention will be described in detail.

Examples of the heat-meltable adhesive fibers include polyolefin fibers such as polyethylene, polypropylene and polyvinyl alcohol, polyester fibers, polyethylene-polypropylene composite fibers, polyethylene-polyester composite fibers, low melting point polyester-polyester composite fibers, Examples thereof include polyvinyl alcohol-polypropylene composite fibers having a hydrophilic fiber surface, and polyvinyl alcohol-polyester composite fibers.
When the conjugate fiber is used, both the core-sheath type conjugate fiber and the side-by-side type conjugate fiber can be used. These heat-meltable adhesive fibers may be used alone or in combination of two or more.
Examples of the heat-meltable adhesive fiber preferably used in the present invention include polyvinyl alcohol fiber soluble in hot water and core-sheath type polyester fiber.

The above-mentioned heat-meltable adhesive fiber has an average fiber length of preferably 2 to 60 mm, particularly preferably 3 to 20 mm. When the average fiber length is less than 2 mm, the strength of the absorbent paper becomes insufficient, and when the average fiber length exceeds 60 mm, the strength cannot be evenly dispersed in water and the strength becomes uneven. Therefore, the above range is preferable. The heat-meltable adhesive fiber has a fiber diameter of preferably 0.1 to 3 denier, particularly preferably 0.5 to 2 denier. If the fiber diameter is less than 0.1 denier, the strength of the fibrous body will be insufficient and the strength of the entire absorbent paper cannot be expressed. If the fiber diameter exceeds 3 denier, the strength of the absorbent paper will decrease due to the decrease in the number of bonded fibers. Since it becomes insufficient, it is preferable to set it in the above range.

Next, an absorbent article as one example of using the absorbent paper of the present invention will be described with reference to FIGS. 5 and 6.

Here, FIG. 5 is a schematic view showing a cross section in the width direction of a sanitary napkin as one embodiment of the absorbent article. FIG. 6 is a schematic diagram showing a cross section in the width direction of a sanitary napkin as another embodiment of an absorbent article (equivalent to FIG. 5).
Is.

The absorbent article comprises a liquid-permeable surface material, a liquid-impermeable leak-proof material, and a liquid-retaining absorber interposed between the surface material and the leak-proof material. The absorbent body is characterized by comprising the absorbent paper of the present invention and a superabsorbent polymer.

A sanitary napkin 10 as one embodiment of an absorbent article shown in FIG. 5 is a liquid-permeable surface material 21, a liquid-impermeable leakproof material 23, and the surface material and the leakproof material. It is provided with a liquid-retaining absorber 22 interposed therebetween.

More specifically, the sanitary napkin 10 described above.
Is substantially vertically long, and when the sanitary napkin 10 is worn, the surface material 21 is located on the side in contact with the skin, and the leak preventer 23 is located on the side in contact with the underwear. The absorber 22 is interposed between the surface material 21 and the leak preventer 23.

Further, as shown in FIG. 5, the absorber 22 has the lower surface, all side surfaces, and the peripheral edge portions of the upper surface, which are the leakage preventive materials 2 described above.
It is covered by 3. Furthermore, the entire surface of the combination of the absorber 22 and the leak preventer 23 is the surface material 2 described above.
It is covered by 1. As a result, the absorber 22
The central portion of the upper surface of is directly covered with the surface material 21. Therefore, the liquid directly permeates the absorber 22 through the surface material 21.

On the side of the surface material 21 that does not come into contact with the skin, three adhesive portions 24 are formed in a stripe shape in the longitudinal direction. The adhesive section 24 is protected by a release paper 25. In FIG. 5, reference numeral 26 is an adhesive for fixing the surface material 21, the absorber 22, and the leak preventer 23 to each other.

The surface material 21 is not particularly limited as long as it allows liquid to pass through to the absorbent body 22, but a material having a feeling close to that of underwear is preferable. Examples of such a surface material include, for example, woven fabric, non-woven fabric, and porous film of thermoplastic resin. In particular, an apertured film made of polyolefin such as low density polyethylene can be preferably used.

The apertured film can be manufactured, for example, by the following method. That is, a polyolefin such as low-density polyethylene is melted and extruded from a T die to form a film on the spiral braided wire net 31 made of the wire rod 31a shown in FIGS. 7A and 7B. Then, by aspirating such a film, FIG.
The apertured film 42 having the apertures 44 shown in (A) is obtained. As shown in FIGS. 8 (B) and 8 (C), the perforated film 42 has a large number of tops 45 each having a convex curved surface.
And a large number of apertures 44 located between the tops 45.

The leakage preventive material 23 is not particularly limited as long as it is liquid impermeable, but a material having moisture permeability and a feeling close to that of underwear is preferable. The liquid impermeable leak preventer having moisture permeability is, for example, a thermoplastic resin to which a filler of an inorganic compound or an organic compound is added, is melt-extruded from a T die or a circular die to form a film, and then, It can be obtained by uniaxially or biaxially stretching the film.

As shown in FIG. 5, the absorbent body 22 of the absorbent article.
Comprises at least the absorbent paper 22A of the present invention and the superabsorbent polymer 22B. Since the absorbent body 22 is extremely thin, a comfortable wearing feeling can be obtained, and furthermore, the absorbent body 22 is highly absorbent and liquid leakage does not easily occur.

More specifically, the above superabsorbent polymer 22
B is wrapped inside the absorbent paper 22A of the present invention, and the super absorbent polymer 22B is sandwiched between the absorbent paper 22A of the present invention. In this case, it is preferable to sandwich the superabsorbent polymer 22B between the absorbent papers 22A of the present invention so that the superabsorbent polymer 22B contacts the "back surface" of the absorbent paper 22A of the present invention. With such a configuration, the liquid that has passed through the surface material 21 is quickly absorbed and permeated by the “surface” of the absorbent paper 22A of the present invention,
The "rear surface" of the absorbent paper 22A is more smoothly reached.
The liquid that has reached the "back surface" of the absorbent paper 22A is diffused throughout the absorbent paper 22A of the present invention and then fixed to the superabsorbent polymer 22B.

As described above, in the above-mentioned absorbent article, the absorption / permeation / diffusion / holding of the liquid is carried out very smoothly. As a result, the absorbent article can more reliably immobilize the liquid, and further, the liquid does not remain on the surface material 21 and the liquid does not return to the surface material 21. Further, when the absorbent body 22 is composed of only one sheet of absorbent paper 22A and the superabsorbent polymer 22B, the absorbent article can be made extremely thin and have a comfortable fit.

The superabsorbent polymer 22B is preferably a polymer capable of absorbing and retaining 20 times or more of its own weight of liquid and capable of gelling. The super absorbent polymer 22B
The shape is not particularly limited, and for example, a spherical shape, a flaky shape, or a particle shape can be used. Examples of such superabsorbent polymers include starch-acrylic acid (salt) graft copolymers, saponified starch-acrylonitrile copolymers, crosslinked sodium carboxymethyl cellulose and acrylic acid (salt) polymers. Can be mentioned.

Another embodiment of an absorbent article as one example of using the absorbent paper of the present invention will be described with reference to FIG. 6 by taking a sanitary napkin as an example. The same points as those in FIG. 5 will not be described in detail, but the description in detail regarding FIG. 5 will be applied as appropriate. Further, in FIG. 6, the same members as those in FIG. 5 are designated by the same reference numerals.

The absorbent body 22 in the sanitary napkin 10 as another embodiment of the absorbent article shown in FIG. 6 includes two absorbent papers 22A and 22C of the present invention and the superabsorbent polymer 22B. The super absorbent polymer 22B is sandwiched between the absorbent papers 22A and 22C of the present invention. In this case, the absorbent paper 22A has its "back surface".
Is preferably in contact with the superabsorbent polymer 22B. Further, it is preferable that the "back surface" of the absorbent paper 22C is also in contact with the superabsorbent polymer 22B.
Particularly preferably, the "back surface" of the absorbent paper 22A is in contact with the superabsorbent polymer 22B, and the "back surface" of the absorbent paper 22C is in contact with the superabsorbent polymer 22B. With such a structure, absorption / permeation / diffusion / holding of liquid can be performed extremely smoothly.

Although the absorbent article as one of the usage examples of the absorbent paper of the present invention has been described based on its preferred embodiment, the absorbent article is not limited to the above-mentioned embodiment and may be, for example, a paper diaper. It goes without saying that it can be similarly applied to other absorbent articles such as a hygene pad, a medical pad, an incontinence pad and a breast milk pad.

[0096]

EXAMPLES Next, the absorbent paper of the present invention and its manufacturing method will be described in more detail with reference to Examples and Comparative Examples.

First, the production of bulky cellulose fibers, hydrophilic fine fibers and hydrophilic fine powders used in Examples and Comparative Examples will be described. In the following description, “%” and “part” represent “% by weight” and “part by weight”, respectively, unless otherwise specified.

Production Example 1 Production of Cellulose Fibers The average fiber length is 2.35 mm and the fiber roughness is 0.36 mg.
/ M, and the roundness of the fiber cross section is 0.80, mercerized pulp ["POROSANI manufactured by ITT RAYONIER INC.
ER-J "(trade name)] 100 g, 5% dimethylol dihydroxyethylene urea [crosslinking agent," Sumitex Resin NS-19 "(trade name) manufactured by Sumitomo Chemical Co., Ltd.] and 3% metal salt Catalyst [Sumitex manufactured by Sumitomo Chemical Co., Ltd.
AcceleratorX-110 "(trade name)]
The mercerized pulp was dispersed in 00 g to impregnate the crosslinking agent.

Then, the aqueous solution of the cross-linking agent was separated from the mercerized pulp until the amount of the aqueous solution of the cross-linking agent with respect to the mercerized pulp reached 200%, and then heated in an electric dryer at 135 ° C. for 10 minutes, The cellulose in the mercerized pulp was crosslinked to obtain a mercerized crosslinked pulp. This is designated as cellulose fiber (A).

Production Example 2 Production of Cellulose Fiber The average fiber length is 2.56 mm and the fiber roughness is 0.35 mg.
/ M and the roundness of the fiber cross section is 0.28, except for using 100 g of coniferous wood pulp [[INDORAYON] (trade name) manufactured by PT Inti Indorayon Utama]
The same operation as in Production Example 1 was performed to obtain a crosslinked pulp. This is designated as cellulose fiber (B).

Production Example 3 Production of Cellulose Fibers The average fiber length is 2.35 mm and the fiber roughness is 0.36 mg.
/ M, and the roundness of the fiber cross section is 0.80, mercerized pulp ["POROSANI manufactured by ITT RAYONIER INC.
ER-J ”(trade name)] was prepared. This is designated as cellulose fiber (C).

Production Example 4 Production of Cellulose Fibers The average fiber length is 2.38 mm and the fiber roughness is 0.32 mg.
/ M and the roundness of the fiber cross section is 0.30 [[High Bulk Addi made by Weyerhauser Paper
tive HBA-S ”(trade name)] was prepared. This is designated as cellulose fiber (D).

Production Example 5 Production of Cellulose Fiber The average fiber length is 2.56 mm and the fiber roughness is 0.24 mg.
/ M and the roundness of the fiber cross section was 0.34, a softwood kraft pulp [“HARMAC-R” (trade name) manufactured by MacMillan Bloedel Ltd.] was prepared. This is designated as cellulose fiber (E). The cellulose fiber (E) is not crosslinked.

Production Example 6 Production of Cellulose Fiber The average fiber length is 2.56 mm and the fiber roughness is 0.35 mg.
/ M and the roundness of the fiber cross section was 0.28, a softwood clato pulp [“INDORAYON” (trade name) manufactured by PT Inti Indorayon Utama] was prepared. This is called cellulose fiber (F). The cellulose fiber (F) is not crosslinked.

Production Example 7 Production of Cellulose Fiber The average fiber length is 0.75 mm and the fiber roughness is 0.13 mg.
/ M and the roundness of the fiber cross section is 0.35, the hardwood kraft pulp ["BAHIA SU manufactured by BAHIA SUL Co.
L CELULOSE SA "(trade name)] was used to obtain a crosslinked pulp in the same manner as in Production Example 1. This is designated as cellulose fiber (G).

The average fiber length, the fiber roughness and the roundness of the fiber cross section of the above cellulose fibers (A) to (G) were measured by the following methods. Table 1 shows the results.

<Measurement of Average Fiber Length and Fiber Roughness> It was measured using a fiber roughness meter FS-200 (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.
And dried for 1 hour to remove water present in the cellulose fiber.

Accurately weigh approximately 1 g of cellulose fibers to an accuracy of ± 0.1 mg. Next, in order not to damage the cellulose fiber, the cellulose fiber was completely disintegrated in 150 ml of water with a mixer attached to the fiber roughness meter, diluted with water to 5000 ml, and diluted with 50 ml of the diluted solution. Was accurately measured and used as a fiber roughness measuring solution, and the average fiber length and the fiber roughness were determined according to the operation procedure of the fiber roughness meter. As the average fiber length, a value calculated by the following formula based on the above operation was used.

[0109]

[Equation 1]

<Measurement of Roundness of Fiber Cross Section> To measure the roundness of the cross section of cellulose fiber, first, the cellulose fiber is sliced perpendicularly to the cross section direction so that the area of the cross section of the cellulose fiber does not change, A cross-section photograph was taken with a microscope, and the cross-section photograph was analyzed by an image analyzer [“Avio EXCEL” (trade name) manufactured by Nippon Avionics Co., Ltd.), and the roundness of the cellulose fiber cross section was obtained using the formula shown below. . The roundness was an average value obtained by measuring 100 cross sections of an arbitrary cellulose fiber.

[0111]

[Equation 2]

[0112]

[Table 1]

[Production Example 8] Production of hydrophilic fine fibers Cellulose fine fibers having an average fiber length of 0.23 mm obtained by acid-hydrolyzing selected pulp, washing with water and drying, and then mechanically pulverizing it [Sanyo Kokusaku "KC Flock W-50" (trade name) manufactured by Pulp Co., Ltd. was prepared. This is referred to as hydrophilic fine fiber (A).

[Production Example 9] Production of hydrophilic fine fibers Cellulose fine fibers having an average fiber length of 0.12 mm obtained by acid hydrolysis of selected pulp, washing with water and drying, and then mechanical pulverization [Sanyo Kokusaku "KC Flock W-100" (trade name) manufactured by Pulp Co., Ltd. was prepared. This is a hydrophilic fine fiber (B).

[Production Example 10] Production of hydrophilic fine fibers Hydrous magnesium silicate fine fibers having an average fiber length of 0.03 mm ["Adeplus ML-3 manufactured by Mizusawa Chemical Industry Co., Ltd.]
0 "(trade name)] was prepared. This is a hydrophilic fine fiber (C).

[Production Example 11] Production of hydrophilic fine fibers [0116] Hardwood kraft pulp having an average fiber length of 0.75 mm [BAHIA
"BAHIA SUL CELULOSE SA (trade name)" manufactured by SUL Co. was prepared and used as hydrophilic fine fibers (D).

[Production Example 12] Production of hydrophilic fine fibers Softwood kraft pulp having an average fiber length of 2.34 mm [Skeena
"SKEENA PRIME" (trade name) manufactured by Cellulose Co. was prepared. This is a hydrophilic fine fiber (E).

[Example 1]Manufacture of absorbent paper Cellulose fiber (A) concentration is 0.16%, hydrophilic fine
Fine fiber (A) concentration is 0.03% and thickness is 1 denier
Polyvinyl alcohol fiber with an average fiber length of 3 mm
Fibrous bond manufactured by Sansho Co., Ltd.
Name), hereinafter referred to as "PVA" fiber], is 0.0
1% (0.2% as a whole slurry)
These were uniformly dispersed in water to obtain a slurry. This
Rally wire opening diameter 90μm (166 mesh)
Spray on the wire mesh paper wire of
A paper layer was formed. 6 ml using a suction box
/〔cm ²・ Sec] was used to dehydrate this paper layer. Next
Then, after drying the paper layer with a dryer, remove the crepe.
80% / m 2 basis weight²The absorbent paper of this
Absorbent paper is based on 100 parts by weight of absorbent paper
(A) 80 parts, hydrophilic fine fiber (A) 15 parts, top
The PVA fiber contained 5 parts.

Example 2 Production of absorbent paper Cellulose fiber (B) concentration was 0.16%, hydrophilic fine fiber (B) concentration was 0.034%, and the PVA fiber concentration was 0. Absorbing paper having a basis weight of 80 g / m ² was obtained by performing the same operations as in Example 1 except that these were uniformly dispersed in water to form a slurry so that the amount became 006%. This absorbent paper contained 80 parts of the cellulose fibers (B), 17 parts of the hydrophilic fine fibers (B), and 3 parts of the PVA fibers based on 100 parts of the absorbent paper.

Example 3 Production of Absorbent Paper Cellulose fiber (D) concentration was 0.15%, hydrophilic fine fiber (A) concentration was 0.04%, and thickness was 1.1 denier on average. The concentration of polyethylene terephthalate fiber having a fiber length of 5 mm [heat-melting adhesive fiber, "TMOTNSB" (trade name) of Teijin Ltd., hereinafter referred to as "PET" fiber] is 0.
The same operation as in Example 1 was carried out except that these were uniformly dispersed in water to form a slurry so as to be 01%.
An absorbent paper having a basis weight of 80 g / m ² was obtained. This absorbent paper contained 75 parts of the cellulose fibers (D), 20 parts of the hydrophilic fine fibers (A), and 5 parts of the PET fibers based on 100 parts of the absorbent paper.

Example 4 Production of absorbent paper Cellulose fibers (D) had a concentration of 0.17%, hydrophilic fine fibers (C) had a concentration of 0.02%, and the PVA fibers had a concentration of 0. These were uniformly dispersed in water to obtain a slurry to obtain a slurry of 01%. This slurry was sprinkled on a wire netting paper wire having a wire opening diameter of 26 μm (518 mesh) to form a paper layer on the wire netting paper wire. Using a suction box, 6 ml / [cm ² · sec
] The paper layer was dehydrated at a speed of. Then, after the paper layer was dried with a dryer, 10% of crepe was applied to obtain an absorbent paper having a basis weight of 80 g / m ² . This absorbent paper contained 85 parts of the cellulose fibers (D), 10 parts of the hydrophilic fine fibers (C), and 5 parts of the PVA fibers based on 100 parts of the absorbent paper.

Example 5 Production of Absorbent Paper Cellulose fiber (C) concentration was 0.16%, hydrophilic fine fiber (A) concentration was 0.03%, and the PET fiber concentration was 0. Absorbing paper having a basis weight of 80 g / m ² was obtained by performing the same operation as in Example 1 except that these were uniformly dispersed in water to form a slurry so as to be 01%. This absorbent paper is based on 100 parts of absorbent paper and contains cellulose fibers (C).
80 parts, hydrophilic fine fibers (A) 15 parts, the above PE
It contained 5 parts of T-fiber.

Comparative Example 1 Production of Absorbent Paper The same operation as in Example 1 was carried out except that cellulose (E) was used instead of the cellulose fiber (A), and the basis weight was 80 g /
An absorbent paper of m ² was obtained.

Comparative Example 2 Production of Absorbent Paper The same operation as in Example 2 was carried out except that cellulose (G) was used instead of the cellulose fiber (B), and the basis weight was 80 g /
An absorbent paper of m ² was obtained.

Comparative Example 3 Production of Absorbent Paper Cellulose fiber (F) concentration was 0.16%, hydrophilic fine fiber (D) concentration was 0.03%, and the PET fiber concentration was 0. Absorbing paper having a basis weight of 80 g / m ² was obtained by performing the same operation as in Example 1 except that these were uniformly dispersed in water to form a slurry so as to be 01%. This absorbent paper is based on 100 parts of absorbent paper based on cellulose fiber (F)
80 parts, hydrophilic fine fibers (D) 15 parts, the above PE
It contained 5 parts of T-fiber.

Comparative Example 4 Production of Absorbent Paper Cellulose fiber (G) concentration was 0.16%, hydrophilic fine fiber (E) concentration was 0.03%, and the PET fiber concentration was 0. Absorbing paper having a basis weight of 80 g / m ² was obtained by performing the same operation as in Example 1 except that these were uniformly dispersed in water to form a slurry so as to be 01%. This absorbent paper is based on 100 parts of absorbent paper and contains cellulose fibers (G).
80 parts, hydrophilic fine fibers (E) 15 parts, the above PE
It contained 5 parts of T-fiber.

Comparative Example 5 Production of Absorbent Paper Cellulose fibers (D) had a concentration of 0.08%, hydrophilic fine fibers (E) had a concentration of 0.04%, and the PET fibers had a concentration of 0. Absorbing paper having a basis weight of 80 g / m ² was obtained by performing the same operations as in Example 1 except that these were uniformly dispersed in water to form a slurry so that the amount became 08%. This absorbent paper is based on 100 parts of absorbent paper based on cellulose fiber (D).
40 parts, hydrophilic fine fibers (E) 20 parts, the above PE
It contained 40 parts of T-fiber.

[Comparative Example 6]Manufacture of absorbent paper Adjust the concentration of cellulose fiber (E) to 0.2%,
Except that this is uniformly dispersed in water to form a slurry,
Perform the same operation as in Example 1 to obtain a basis weight of 80 g / m. ²Absorption of
Got the paper. Is this absorbent paper only cellulose fiber (E)?
It consists of

Comparative Example 7 Production of Absorbent Paper Example 1 except that the hydrophilic fine fibers (D) were uniformly dispersed in water to form a slurry so that the concentration of the hydrophilic fine fibers (D) was 0.2%. The same operation as above was performed to obtain an absorbent paper having a basis weight of 80 g / m ² . This absorbent paper consists of hydrophilic fine fibers (D).
Made of chisel.

The following measurements were performed on the absorbent papers obtained in Examples 1 to 5 and Comparative Examples 1 to 7. The results are shown in Table 2.

<Measurement of Absorption Time> As shown in FIG. 9, the absorption paper 51 (200 mm × 75 mm) is placed horizontally and the diameter is 10 mm.
An acrylic plate 52 having an injection port 54 of mm is placed thereon, and a weight 53 is further placed on the acrylic plate 52 so that the weight of the absorbent paper 51 is 5 g /
A load of cm ² was applied. Next, 6 g of defibrinated horse blood [manufactured by Japan Biotest Institute Co., Ltd.] was injected from the injection port 54,
The time until the defibrinated horse blood was completely absorbed was measured.
The absorption time was defined as the average of 5 measurements.

<Measurement of Diffusion Area> As shown in FIG. 10, the absorbent paper 51 (200 × 75 mm) was placed horizontally so that the “front side” was the upper side, and the diameter was measured from the microtube pump 60. Tube 61 with 2 mm inlet
Through 1g of saline solution 62 at a speed of 1g / 10 seconds
Was injected into the absorbent paper 51. The distance between the tip of the tube 61 and the absorbent paper was about 10 mm. Saline is 0.0
It was colored with 1% food blue No. 1 (Tokyo Chemical Industry Co., Ltd.) and used. About 1 minute after injection of physiological saline, the diffusion area (cm ² ) on the “surface” of the absorbent paper was accurately traced and measured by an image analyzer. The same operation is performed by horizontally setting the absorbent paper 51 so that the “rear surface” of the absorbent paper 51 is on the upper side, accurately tracing the diffusion area (cm ² ) of the “rear surface”, and using the image analysis device. It was measured. Next, the diffusion area ratio between the "front side" and the "back side" of the absorbent paper was obtained by rounding off to the second decimal place according to the following formula.

[0133]

(Equation 3)

<Evaluation of Surface Condition after Absorption of Liquid> As shown in FIG. 10, the absorbent paper 51 (200 × 75 mm) was placed horizontally so that the “front surface” was the upper side, and the microtube pump was used. From 60, 3 g of physiological saline was injected into the absorbent paper 51 at a speed of 1 g / 10 seconds through a tube 61 having an inlet having a diameter of 2 mm. Approximately 1 minute after the injection of physiological saline, a sensory evaluation of the "latency" of the "surface" of the absorbent paper was performed. The same operation was performed by horizontally installing the absorbent paper 51 so that the "back surface" of the absorbent paper 51 was on the upper side. The evaluation criteria are as follows.

◯: There is almost no physiological saline solution retained on the absorbent paper, and there is a feeling of slat. Δ: A little saline is retained on the absorbent paper, but there is some sensation of slat. X: A considerable amount of physiological saline remains on the absorbent paper, and it feels sticky.

[0136]

[Table 2]

As is clear from the results shown in Table 2, the absorbent paper of the present invention has a fast absorption time, has a liquid diffusion gradient, and is excellent in slatiness. On the other hand, the absorbent paper in the comparative example has a diffusion area ratio of 1 because there is no diffusion gradient related to the diffusibility of the liquid in the thickness direction.

Next, production of an absorbent article as one example of using the absorbent paper of the present invention will be described.

Reference Example 1 Production of Absorbent Article A sanitary napkin 10 shown in FIG. 5 was produced. The absorbent paper (length 195 mm, width 160 mm) obtained in Example 1 was used as the absorbent paper 22A. In the area of length 195 mm and width 70 mm on the "rear surface" side of the absorbent paper 22A, the super absorbent polymer 22B
Was dispersed substantially uniformly so that the sprayed amount was 50 g / m ² . Next, the absorbent paper 22A is folded inward, and the high-absorbent polymer 22B is wrapped with the absorbent paper 22A.
2 was manufactured (therefore, the "front surface" side of the absorbent paper 22A corresponds to the outside of the absorbent body 22). The width of the absorber 22 was 75 mm. As the superabsorbent polymer 22B, sodium polyacrylate [Polymer Q (trade name) of Kao Corporation] was used. The absorbent body 22 was wrapped with polyethylene laminated paper (leak-proof material 23), and the combination of the absorbent body 22 and the leak-proof material 23 was further wrapped with the surface material 21. Then, the surface material 21, the absorber 22, and the leak preventer 23 were fixed to each other with an adhesive 26. In addition, as the surface material 21, as shown in FIG.
The perforated film shown in (A) to (C) was used. The perforated film is formed by melt extruding low-density polyethylene from a T-die to form a film on the spiral woven wire mesh shown in FIGS. 7 (A) and (B), and then sucking the film. . Further, on the lower surface side of the sanitary napkin 10, three adhesive portions 24 were formed in a stripe shape in the longitudinal direction. The adhesive section 24 is protected by a release paper 25.

[Reference Examples 2-5 and Comparative Reference Examples 1-7] Production of Absorbent Articles Instead of the absorbent paper obtained in Example 1, the absorbent articles obtained in Examples 2-5 and Comparative Examples 1-7. Except for using each paper,
The same operation as in Reference Example 1 was performed to produce a sanitary napkin.

With respect to the sanitary napkins obtained in Reference Examples 1 to 5 and Comparative Reference Examples 1 to 7, absorption time by the following method,
The dynamic liquid return amount and the leak test (number of leak occurrences) were measured. Table 3 shows the results.

<Absorption time and amount of dynamic liquid return> In the apparatus for measuring the liquid absorption time of absorbent paper shown in FIG. 9, the sanitary napkin 10 is placed horizontally instead of the absorbent paper 51, and the diameter is 10 mm.
Place the acrylic plate 52 having the injection port 54 of
Place a weight 53 on top of it and put 5 on the sanitary napkin 10.
A load of g / cm ² was applied. Next, 6 g of defibrinated horse blood (manufactured by Japan Biotest Institute Co., Ltd.) was injected from the injection port 54, and the time until the defibrinated horse blood was completely absorbed was measured.

After the defibrinated horse blood is completely absorbed, it is allowed to stand for 20 minutes. Then, this sanitary napkin 10
Paper (length 195 mm x width 75 mm,
Ten sheets of the basis weight of 30 g / m ² ) were stacked and the sanitary napkin 10 and the paper in this state were mounted on the female waist model 70 shown in FIG. 11 as shown in FIG. Next, the female waist model 70 was fitted with shorts, and then walked at a walking speed of 100 steps / minute (50 m / minute). After walking, the sanitary napkin 10 and 10 sheets of paper were taken out, and the weight of defibrinated horse blood absorbed in the paper was measured. This is defined as the dynamic liquid return amount (g).

The absorption time and the dynamic liquid return amount were measured 10 times, and the average value was used as the absorption time and the dynamic liquid return amount.

<Leak Test (Number of Leak Occurrences)> Reference Examples 1 to 1
5 and the sanitary napkins obtained in Comparative Reference Examples 1 to 7 were attached to the female waist model 70 shown in FIG. 11 as shown in FIG. Next, the female waist model 70 was fitted with shorts, and then walked at a walking speed of 100 steps / minute (50 m / minute).

After that, 3 g of defibrinated horse blood was injected into the sanitary napkin through the tube 71 while walking, and then the patient was allowed to walk at the same speed for 10 minutes (total amount of 3 g). After injecting 3g into
At the time of walking at the same speed for 10 minutes (total amount of 6 g), after further injecting 3 g of defibrinated horse blood into the sanitary napkin, at the same speed of walking for 10 minutes (total amount of 9 g), the number of samples was 10 at each time point. The number of leaks was counted.

[0147]

[Table 3]

As is clear from the results shown in Table 3, the absorbent article comprising the absorbent paper of the present invention has a very simple structure, but has a quick liquid absorption time and a liquid return amount. It is extremely high performance with few leaks and few leaks. This is because the absorbent paper of the present invention has an absorption / diffusion gradient of liquid in its single structure, so that it absorbs liquid quickly and the liquid permeates smoothly through the absorbent paper.
Moreover, this is because the liquid is sufficiently diffused on the "rear surface" side of the absorbent paper.

[0149]

Since the absorbent paper of the present invention has a liquid absorption / diffusion gradient in its single structure, the liquid absorption rate is high, and the liquid spot absorptivity and liquid permeability and It has excellent diffusibility, and as a result, the surface has a very high feeling of slat. Further, according to the method for manufacturing absorbent paper of the present invention, the absorbent paper can be easily manufactured by a single process. Further, the absorbent article using the absorbent paper of the present invention has extremely high absorbency, little liquid leakage, is extremely thin, and is excellent in wearing feeling.

[Brief description of drawings]

FIG. 1 is a schematic view showing a cross section in the thickness direction of an absorbent paper according to the present invention.

FIG. 2 is a schematic diagram showing the state of liquid absorption / diffusion by the absorbent paper of the present invention.

FIG. 3 is a schematic diagram showing a preferred method for producing the absorbent paper of the present invention.

FIG. 4 is an enlarged view of part (a) of FIG.

FIG. 5 is a schematic view showing a cross section in the width direction of a sanitary napkin as an embodiment of an absorbent article using the absorbent paper of the present invention.

FIG. 6 is a schematic view (corresponding to FIG. 5) showing a cross section in the width direction of a sanitary napkin as another embodiment of an absorbent article using the absorbent paper of the present invention.

FIG. 7 is a view showing a spiral braided wire mesh for producing a liquid-permeable surface material.

FIG. 8 is a schematic diagram showing a liquid-permeable surface material.

FIG. 9 is a schematic diagram showing an absorption time measuring device.

FIG. 10 is a schematic view showing a device for measuring a diffusion area.

FIG. 11 is a schematic view showing a female waist model.

FIG. 12 is a schematic diagram showing a state in which an absorbent article is attached to a female waist model.

[Explanation of symbols]

 10 Sanitary Napkins 11 Absorbing Paper 12 Bulky Cellulose Fibers 13 Hydrophilic Fine Fibers or Hydrophilic Fine Powders 14 Slurry 15 Paper Making Wire 16 Paper Layer 17 Network Structure 21 Liquid Permeable Surface Material 22 Liquid Retaining Absorber 23 Liquid impermeable leak preventer 24 Adhesive part 25 Release paper 26 Adhesive

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location D21H 17/20 A61F 13/18 303 D21H 3/32 A

Claims (12)

[Claims] 1. An absorbent paper containing bulky cellulose fibers and hydrophilic fine fibers or hydrophilic fine powder, wherein the hydrophilic fine fibers or hydrophilic fine powder is the absorbent paper. The abundance ratio on one surface side is higher than the abundance ratio on the other surface side, and the average fiber length of the bulky cellulose fibers is 1 to 20 mm.
And the average fiber length of the hydrophilic fine fibers is 0.02 to 0.5.
mm, and the hydrophilic fine powder has an average powder particle size of 0.02 to 0.5 mm. 2. 50 to 97 parts by weight of the bulky cellulose fiber, and 3 to 50 parts of the hydrophilic fine fiber or the hydrophilic fine powder based on 100 parts by weight of the absorbent paper.
The absorbent paper according to claim 1, comprising parts by weight. 3. A heat-melting adhesive fiber is further included; 70 to 95 parts by weight of said bulky cellulose fiber based on 100 parts by weight of said absorbent paper, said hydrophilic fine fiber or said hydrophilic fine powder. 5 to 30 parts by weight, and comprises 2 to 30 parts by weight of the thermally fusible bonding fibers; and the basis weight of the absorbent sheet is 10 to 200 g / m ^2, according to claim 1 or 2 absorbent sheet according. 4. The absorbent paper according to claim 1, wherein the bulky cellulose fibers have a fiber roughness of 0.3 mg / m or more. 5. The absorbent paper according to claim 4, wherein the bulky cellulose fibers have an average fiber length of 2 to 5 mm. 6. The absorbent paper according to claim 4, wherein the bulky cellulose fiber is a crosslinked pulp. 7. The absorbent paper according to claim 4, wherein the bulky cellulose fiber is pulp having a roundness of 0.5 to 1 in a fiber cross section. 8. The absorbent paper according to claim 1, wherein the hydrophilic fine fibers are cellulose fibers, and the hydrophilic fine powder is cellulose powder. 9. The absorbent paper according to claim 1, wherein a diffusion area ratio between the front surface side and the back surface side when the absorbent paper absorbs 1 g of physiological saline is 1.2 or more. 10. Bulky cellulose fibers having an average fiber length of 1 to 20 mm and hydrophilic fine fibers having an average fiber length of 0.02 to 0.5 mm or an average powder particle size of 0.02.
A step of dispersing 0.5 mm of hydrophilic fine powder in water to form a slurry; a step of spraying the slurry on a papermaking wire to form a paper layer on the papermaking wire; A process for producing absorbent paper, comprising the steps of dehydrating and drying the layer. 11. The dehydration rate is 2 ml / [cm ² · sec.
] The method of Claim 10 which is the above. 12. The method according to claim 10, wherein the opening diameter of the papermaking wire is 22 to 300 μm.