WO2022224955A1

WO2022224955A1 - Absorbent sheet and absorbent article

Info

Publication number: WO2022224955A1
Application number: PCT/JP2022/018162
Authority: WO
Inventors: 良寛田中; 健司石黒; 陽一鈴木
Original assignee: 花王株式会社
Priority date: 2021-04-19
Filing date: 2022-04-19
Publication date: 2022-10-27
Also published as: CN220327595U; JP2022165417A

Abstract

The absorbent sheet (1) according to the present invention is provided with a first fiber sheet (11), a second fiber sheet (12), and an absorbent layer (1A) disposed between these fiber sheets (11), (12). The absorbent layer (1A) contains particles of a water-absorbent polymer (13) and does not contain water-absorbent fiber. The first fiber sheet (11) contains a deodorant and/or an antibacterial agent. The water retention rate of the second fiber sheet (12) is higher than the water retention rate of the first fiber sheet (11). The present invention also provides an absorbent article that is provided with the absorbent sheet (1).

Description

Absorbent sheet and absorbent article

The present invention relates to absorbent sheets and absorbent articles.

For the purpose of improving liquid absorbency, antibacterial properties, and deodorant properties, sheet-like articles containing water-absorbing polymers and absorbent articles comprising the same have been developed.

The applicant proposed an absorbent article in which an antibacterial sheet containing a sparingly water-soluble antibacterial agent and cellulose fibers is arranged on the skin-facing surface of the absorbent core (see Patent Document 1).

Patent Document 2 describes a hydrophobic nonwoven fabric having a water resistance of at least 150 mmH ₂ O or more, a hydrophilic sheet having moisture diffusibility, and an average particle size interposed between the hydrophobic nonwoven fabric and the hydrophilic sheet. A water-absorbing and water-resistant sheet having a three-layer structure is disclosed, which is composed of an SAP layer made of SAP particles having a diameter of 500 μm or less.

Patent Document 3 discloses a water-absorbent sheet structure having a structure in which an absorbent layer containing a water-absorbent resin and an adhesive is sandwiched from above and below the absorbent layer by nonwoven fabrics, wherein the water-absorbent resin is The content is 100 to 1000 g/m ² , the weight average particle diameter of the water absorbent resin is 50 to 800 μm, and the particle diameter velocity index of the water absorbent resin is 0.12 sec/μm or less, and the peel strength of the water absorbent sheet structure. is 0.05 to 3.0 N/7 cm. The document also describes that this water absorbent sheet structure can be applied to absorbent articles.

JP 2015-89487 A JP-A-2002-325799 US2012/0328861 A1

The present invention relates to absorbent sheets.
The absorbent sheet preferably comprises a first fibrous sheet, a second fibrous sheet, and an absorbent layer disposed between these fibrous sheets.
The first fiber sheet preferably contains at least one of a deodorant and an antibacterial agent.
The absorbent layer preferably contains water-absorbing polymer particles and does not contain water-absorbing fibers.
It is preferable that the water retention rate of the second fibrous sheet is higher than that of the first fibrous sheet.

The present invention also relates to an absorbent article comprising the absorbent sheet.

FIG. 1 is a cross-sectional view schematically showing one embodiment of the absorbent sheet of the present invention. FIG. 2 is a cross-sectional view schematically showing another embodiment of the absorbent sheet of the present invention. 3 is a perspective view schematically showing the absorbent sheet shown in FIG. 2. FIG. 4(a) and 4(b) are cross-sectional views schematically showing one embodiment of the absorbent article of the present invention, respectively.

Detailed description of the invention

Since the absorbent article described in Patent Document 1 includes an antibacterial sheet, it is possible to fully exhibit antibacterial properties, but there is room for improvement in terms of allowing the sheet to exhibit both liquid absorbency and deodorant properties. was there.

In addition, the water-absorbent sheets described in Patent Documents 2 and 3 cannot be said to exhibit sufficient liquid absorbency and deodorizing properties after liquid absorption in actual use.

Accordingly, the present invention relates to an absorbent sheet that is excellent in liquid absorbency, deodorant properties, and deodorant properties, and an absorbent article comprising the sheet.

The present invention will be described below based on its preferred embodiments with reference to the drawings. FIG. 1 shows one embodiment of the absorbent sheet of the present invention.

The absorbent sheet 1 shown in FIG. 1 comprises a first fiber sheet 11, a second fiber sheet 12, and an absorbent layer 1A arranged between the

fiber sheets

11,12. The absorbent layer 1A contains particles of the water-absorbent polymer 13 and does not contain water-absorbent fibers. In the absorbent layer 1A shown in the figure, a plurality of particles of the water absorbent polymer 13 are arranged in the sheet surface direction. The absorbent sheet 1 shown in FIG. 1 is preferably open at its periphery. There are no other members on the outer surfaces of the first fiber sheet 11 and the second fiber sheet 12 shown in FIG. Arrangement on the outer surface of each

fiber sheet

11, 12 is not prevented.

The first fiber sheet 11 and the second fiber sheet 12 are configured such that their water retention rates are different from each other. Specifically, the water retention rate of the second fiber sheet 12 is higher than the water retention rate of the first fiber sheet 11 . Since each fiber sheet has such physical properties, it becomes difficult for the first fiber sheet 11 side to retain body fluids, and the body fluids are easily transferred to the absorbent layer 1A and the second fiber sheet 12 side. At the same time, it is possible to reduce the generation of odors derived from bodily fluids. In addition, on the side of the second fiber sheet 12, the body fluid absorbed by the fiber sheet 12 can be retained, and the retained fluid can be gradually absorbed into the absorbent layer 1A.

It is also preferable to use the outer surface of the absorbent sheet 1 on the side of the first fiber sheet 11 as a liquid-receiving surface, which is the surface with which the absorbent sheet 1 first comes into contact with liquid. With such a configuration, compared to the case where the outer surface on the side of the second fiber sheet 12 is used as the liquid receiving surface, the second fiber sheet 12 retains the body fluid while the water-absorbing polymer 13 By utilizing the gel blocking caused by the swelling caused by the absorption of liquid, it is possible to block the passage of air passing through the absorbent sheet 1 in the thickness direction. As a result, it is possible to effectively reduce the release of body fluid-derived odors to the outside while effectively exhibiting liquid absorbency. In particular, as will be described later, the first fiber sheet 11 contains at least one deodorant and an antibacterial agent. Therefore, the above-mentioned effects are further exhibited. The term "liquid absorbency of the absorbent sheet" as used herein mainly means that the amount of liquid returning to the absorbent article is reduced when the absorbent sheet is incorporated in the absorbent article.

From the viewpoint of further improving liquid absorption and deodorizing properties, the water retention rate C1 of the first fiber sheet 11 is preferably 10% by mass or more, more preferably 100% by mass or more, and still more preferably 200% by mass or more, It is preferably 300% by mass or less, more preferably 290% by mass or less, and even more preferably 280% by mass or less.
From the viewpoint of efficiently reducing the release of liquid-derived odors to the outside while efficiently exhibiting liquid absorbency and liquid retention, the water retention rate C2 of the second fiber sheet 12 is such that C1 < C2. As conditions, it is preferably 500% by mass or more, more preferably 550% by mass or more, still more preferably 600% by mass or more, preferably 1500% by mass or less, more preferably 1200% by mass or less, and still more preferably 900% by mass or less. is.
The water retention rates C1 and C2 of the

fiber sheets

11 and 12 can be appropriately adjusted, for example, by changing the basis weight and thickness of the fiber sheets, or the material of the fibers forming the fiber sheets.

In addition, from the viewpoint of further expressing the deodorant property, the difference (C2-C1) between the water retention rate C1 of the first fiber sheet 11 and the water retention rate C2 of the second fiber sheet 12 is, on the condition that C1 < C2, It is preferably 200% by mass or more, more preferably 250% by mass or more, still more preferably 350% by mass or more, preferably 900% by mass or less, more preferably 800% by mass or less, and still more preferably 700% by mass or less.

The water retention rate of the fiber sheet can be measured by the following method. Specifically, the fiber sheet to be measured is taken out from the absorbent sheet 1 while being careful not to change the thickness of the fiber sheet. When the fiber sheet to be measured is bonded to another member with an adhesive, the adhesive is solidified by cooling means such as cold spray and then taken out. When the water-absorbing polymer 13 is adhered to the fiber sheet to be measured, the water-absorbing polymer 13 is removed after solidifying the adhesive using a cold spray or the like. The extraction method up to this point is common to other measurement methods in this specification.
Then, the fiber sheet to be measured is cut into a size of 100 mm square to obtain a sample, and the mass W1 (g) of this sample is measured.
These procedures are performed in an environment of temperature 15 to 35° C. and humidity 20 to 70% RH.

Next, the sample is immersed in physiological saline under the environment for 2 minutes, then taken out, suspended and left for 10 minutes. After that, the mass W2 (g) of this sample is measured. Then, the water retention rate is calculated from the following formula (I).
The above measurements are performed 10 times for each sample, and the arithmetic mean value thereof is defined as the water retention rate (% by mass) in the present invention.
Water retention rate (% by mass) = 100 × [(sample mass W2 [g] after immersion) - (sample mass W1 [g] before immersion)] / (sample mass before immersion W1 [g]) (I )

The

fiber sheets

11 and 12 used in the present invention are typically aggregates of fibers and have a thickness of 5 mm or less measured under a pressure of 1.7 kPa. Both of these

fiber sheets

11 and 12 preferably do not contain a water-absorbent polymer, and are preferably composed only of aggregates of fibers. Each of the

fiber sheets

11 and 12 is independently shape-retained by entangling, joining, or fusing the constituent fibers, or a combination thereof. The thickness of the fiber sheet can be measured using, for example, a laser displacement meter. "Not containing a water-absorbent polymer" means that the

fiber sheets

11 and 12 do not intentionally contain a water-absorbent polymer, but for example, fine particles of polymer derived from the water-absorbent polymer 13 are added to the

fiber sheets

11 and 12. Unavoidable contamination means acceptance. Specifically, in the present specification, the

fiber sheets

11 and 12 contain the water-absorbent polymer independently in each of the

fiber sheets

11 and 12, preferably 10% by mass or less, more preferably 5% by mass or less, More preferably, it is handled as containing 3% by mass or less.

The constituent fibers of each of the

fiber sheets

11 and 12 independently include, for example, wood pulp, natural pulp such as cotton and hemp, modified pulp such as mercerized pulp and chemically crosslinked pulp, polyolefin such as polyethylene and polypropylene, Synthetic fibers containing at least one type of resin among polyesters such as polyethylene terephthalate, regenerated fibers such as rayon, cupra and tencel, or fibers obtained by subjecting these fibers to hydrophilic treatment or hydrophobic treatment. fibers.

The form of each of the

fiber sheets

11 and 12 is paper, woven fabric, or non-woven fabric. Each of the

fiber sheets

11 and 12 may independently be a single layer or multiple layers. Each of the

fiber sheets

11 and 12 may be composed of only one fiber assembly (regardless of whether it is a single layer or multiple layers), or a first fiber assembly and a fiber assembly different from the first fiber assembly. It may have a multi-ply laminate structure in which sheet materials other than the body or fiber assembly are overlaid. From the viewpoint of improving the liquid absorbency of the absorbent sheet 1, each of the

fiber sheets

11 and 12 is preferably a single-layer sheet.

The absorbent layer 1A is a layer that mainly absorbs and retains liquid in contact with the absorbent sheet 1. As described above, the absorbent layer 1A contains particles of the absorbent polymer 13 and does not contain absorbent fibers. With such a configuration, it is possible to reduce the amount of free water derived from body fluids that remains without being absorbed by the water-absorbing polymer 13, so that the liquid absorbency can be improved.

A hydrogel material capable of absorbing and retaining water can generally be used for the water-absorbent polymer 13, and for example, a polymer or copolymer of acrylic acid or an alkali metal salt of acrylic acid can be used. Examples thereof include polyacrylic acid and its salts and polymethacrylic acid and its salts, specifically partial sodium salts of acrylic acid polymers. The shape of the water-absorbing polymer 13 is not particularly limited, and may be, for example, spherical, tufted, massive, bale-shaped, fibrous, amorphous, or a combination of these particles. From the viewpoint of improving the uniformity of spraying of the water-absorbing polymer 13 at the time of manufacturing the absorbent sheet 1 and improving the liquid absorption performance, it is preferable to use particles of the same shape as the water-absorbing polymer 13, and the particles are aggregated or spherical particles. It is also preferable that

Examples of water-absorbing fibers that are not included in the absorbent layer 1A include the above-mentioned wood pulp, natural pulp, mercerized pulp, modified pulp, and hydrophilic synthetic fibers. "Not containing water-absorbent fibers" means that the absorbent layer 1A does not contain water-absorbent fibers intentionally, but water-absorbent fibers such as fibers derived from the

fiber sheets

11 and 12 are inevitably mixed into the absorbent layer 1A. To do means to allow. Specifically, in this specification, the absorbent layer 1A is treated as containing preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less of water-absorbing fibers.

The first fiber sheet 11 preferably contains at least one kind of deodorant and antibacterial agent. By containing such an agent, it is possible to reduce the perception of unpleasant odors originating from body fluids and reduce the generation of odors. As a result, the effect of efficiently reducing the release of body fluid-derived odors to the outside due to the difference in water retention rate between the

fiber sheets

11 and 12, and the effect of the first fiber sheet 11 containing a deodorant or an antibacterial agent. The above-mentioned effect resulting from the inclusion works synergistically, and the deodorizing property can be further improved. In particular, when the outer surface of the first fiber sheet 11 is used as the liquid-receiving surface, body fluid comes into contact with the first fiber sheet 11 earlier, so that the effect of reducing unpleasant odors is efficiently achieved. be done.

A deodorant is a substance that can exert a deodorizing effect by directly acting on odors (odorous substances) by adsorbing, neutralizing, or decomposing them. Examples of deodorants used in the present invention include water-insoluble deodorants such as porous particles and water-soluble deodorants such as water-soluble compounds. These can be used singly or in combination.

A porous particle as a deodorant is a particle having a large number of pores at least on the particle surface, and is capable of capturing, adsorbing and/or containing volatilizing odor components in the pores. Materials for the porous particles include organic compounds, inorganic compounds, polymers thereof, and combinations thereof.

Specific examples of such porous particles include acrylic polymers such as porous methacrylic acid polymers and porous acrylic acid polymers, aromatic polymers such as porous divinylbenzene polymers and porous pyridine copolymers, and copolymers thereof. Synthetic porous polymers other than the above water-absorbing polymers such as polymers; Natural porous polymers such as chitin and chitosan; Zinc oxide, activated carbon, silica, silicon dioxide (silica gel), calcium silicate, aluminosilicate compounds, high silica Metal-supporting porous materials such as zeolite (hydrophobic zeolite), sepiolite, cancrinite, zeolite, and inorganic porous materials such as hydrated zirconium oxide can be used. These can be used singly or in combination. These porous particles can be carried, for example, on the surface or inside of the fibers that make up the fiber sheet, or held between the constituent fibers.

In addition, the water-soluble compound as a deodorant is an agent that neutralizes acidic or alkaline odorous components derived from body fluids, or exerts a deodorant effect due to pH buffering. Examples of such agents include water-soluble organic compounds such as weak acids, conjugate bases thereof, mixtures thereof or salts thereof, weak bases, conjugate acids thereof, or mixtures thereof, and salts thereof. Specific examples of water-soluble compounds as deodorants include weak acids such as citric acid, and salts thereof such as water-soluble metal salts such as Na, K and Ca. Examples of weak bases include polyhydroxyamine compounds such as tris(hydroxymethyl)aminomethane.

The antibacterial agent is an agent that suppresses or kills the growth and growth of bacteria that contribute to the generation of unpleasant odors caused by bodily fluids such as urine and menstrual blood. and the growth of intestinal bacteria, and the activity of enzymes derived from these bacteria. Examples of such antibacterial agents include inorganic antibacterial agents and organic antibacterial agents. These can be used singly or in combination.

Examples of inorganic antibacterial agents include fine particle powders and acicular crystals in which one or more kinds of ions and salts of antibacterial metals such as silver, zinc, copper, iron, magnesium, calcium, aluminum, antimony, and bismuth are supported on a carrier. One or more selected from Examples of the carrier include one or more selected from zeolite, silica gel, low-molecular glass, calcium phosphate, zirconium phosphate, silicate, titanium oxide, and the like.

The organic antibacterial agent includes one or more selected from cationic antibacterial agents, anionic antibacterial agents and nonionic antibacterial agents. These organic antimicrobial agents are preferably water soluble.

Anionic antibacterial agents include piroctone olamine [1-hydroxy-4-methyl-6-(2,4,4-trimethylpentyl)-2(1H)-pyridone monoethanolamine salt], potassium oleate, 1 One or more selected from sodium-pentasulfonate, sodium 1-decanesulfonate, sodium butylnaphthalenesulfonate, sodium dodecylsulfate, sodium dodecylbenzenesulfonate, sodium hexadecylsulfate and the like. All of these are examples of water-soluble anionic antibacterial agents.

Examples of nonionic antibacterial agents include one or more selected from chlorhexidine hydrochloride, chlorhexidine gluconate, triclocarban, triclosan, isopropylmethylphenol, halocarban, paraoxybenzoic acid ester, and the like. All of these are examples of water-soluble nonionic antibacterial agents.

Cationic antibacterial agents include those containing quaternary ammonium salts. The quaternary ammonium salt can be used without any particular limitation. Antimicrobial agents can be these quaternary ammonium salts. All of these are examples of water-soluble cationic antibacterial agents.

More preferably, the first fiber sheet 11 contains at least a water-soluble antibacterial agent among at least one of the deodorant and the antibacterial agent described above. By including such an antibacterial agent in the first fiber sheet 11, the water-soluble antibacterial agent can be easily dissolved in the moisture of the body fluid when the first fiber sheet 11 and the body fluid come into contact with each other. As a result, the growth of odor-causing bacteria can be efficiently suppressed, and the deodorizing properties can be further improved. In particular, when the outer surface of the first fiber sheet 11 is used as the liquid-receiving surface, body fluids come into contact with the first fiber sheet 11 earlier, so that the effect of reducing unpleasant odors is more pronounced. be done.
In order to make the first fiber sheet 11 contain the water-soluble antibacterial agent, for example, an aqueous solution of the antibacterial agent is carried on the first fiber sheet 11 by a method such as spraying, spraying, immersion, or dropping. good.
As long as the effect of the present invention is exhibited, the above-mentioned deodorant and antibacterial agent may be contained in the second fiber sheet 12 in addition to the first fiber sheet 11, but the manufacturing cost is reduced. It is preferable that the first fiber sheet 11 contains only the first fiber sheet 11 from the viewpoint of reducing the amount and improving the odor resistance and deodorant properties.

From the viewpoint of further improving deodorizing properties and ensuring safety, at least one of piroctone olamine and benzalkonium salts is more preferable as the water-soluble antibacterial agent that is suitably used in the present invention.

From the viewpoint of reducing the perception of unpleasant odors derived from bodily fluids and reducing the generation of odors, the content of the deodorant in the

fiber sheets

11 and 12 is preferably 0.05 g/m ² independently. Above, more preferably 0.1 g/m ² or more, still more preferably 0.2 g/m ² or more.
From the same point of view, the content of the antibacterial agent in the

fiber sheets

11 and 12 is preferably 0.05 g/m ² or more, more preferably 0.1 g/m ² or more, and still more preferably 0.2 g/m 2 or more. ² or more.

In the absorbent sheet 1 having the above structure, the water retention rate of the second fiber sheet 12 is higher than that of the first fiber sheet 11, so that the second fiber sheet 12 can easily retain the liquid and absorb the liquid. Liquid absorbency can be enhanced in combination with the layer. In addition, since the liquid is less likely to be retained in the first fiber sheet 11, the liquid can be easily transferred to the absorbent layer 1A side, and the liquid absorbency can be improved, and the unpleasant odor caused by the residual liquid can be reduced. can be made Furthermore, by using gel blocking caused by swelling of the water-absorbing polymer accompanying the absorption of liquid, ventilation in the thickness direction of the sheet is likely to be inhibited. Also, it is possible to suppress the emission of unpleasant odors to the outside through the first fiber sheet 11 .
In addition, by including at least one of a deodorant and an antibacterial agent in the first fiber sheet 11, the odor of the body fluid itself and the unpleasant odor caused by the body fluid coming into contact with the first fiber sheet 11 can be eliminated. It is possible to suppress the generation and improve the deodorizing and deodorizing properties.
As will be described later, each of the advantages described above can be obtained when an absorbent article including the absorbent sheet 1 is formed, specifically, the outer surface of the absorbent sheet 1 on the side of the first fiber sheet 11 is the liquid receiving surface. When the absorbent sheet 1 is arranged as a constituent member of an absorbent article, the emission of unpleasant odors to the outside through the first fiber sheet 11 is suppressed, and the deodorizing and deodorizing properties are improved. It is advantageous in that it can be enhanced.

From the viewpoint of making it easier to pass liquid in the sheet thickness direction, further increasing the utilization efficiency of the water-absorbent polymer 13, realizing high liquid absorbency, and making it easy to easily incorporate deodorants and antibacterial agents. From the viewpoint of improvement, the first fiber sheet 11 is preferably paper. Paper refers to a product made by agglutinating vegetable fibers such as pulp and other fibers, preferably by a wet process, in accordance with the provisions of JIS P0001.

Regarding the second fiber sheet 12, the second fiber sheet 12 is preferably a nonwoven fabric, more preferably a nonwoven fabric containing hydrophilic fibers. By using such a fiber sheet, the absorbed liquid is easily retained in the second fiber sheet 12, so that the liquid absorbability and deodorant properties can be more effectively exhibited. Moreover, the water retention rate of the second fiber sheet 12 can be increased more easily.
The hydrophilic fibers that can be used in the second fiber sheet are preferably rayon, cupra, tencel, etc., from the viewpoint of enhancing the entanglement with other fibers during the production of the fiber sheet and from the viewpoint of expressing high liquid retention. regenerated fiber.

The second fiber sheet 12 is formed by fusing the constituent fibers from the viewpoint of improving the liquid retention property, further increasing the liquid absorption property of the absorbent sheet 1, and further reducing the release of unpleasant odors derived from the liquid. It is preferably a nonwoven fabric having a predetermined ratio or less of points, or a nonwoven fabric having no fusion points.
Specifically, the second fiber sheet 12 is preferably a nonwoven fabric, and preferably has 30 or less fusion points between constituent fibers, more preferably 20 or less points, and still more preferably 10 or less points. Alternatively, the second fibrous sheet 12 is preferably a non-woven fabric having no fusing points. With such a configuration, the degree of freedom of movement of the constituent fibers can be increased, and water can be retained between the constituent fibers, so that the water retention rate of the second fiber sheet 12 can be further increased. can be done. As a result, the liquid absorption and deodorant properties of the absorbent sheet 1 are further improved.
For such a nonwoven fabric, for example, a spunlaced nonwoven fabric or an air-through nonwoven fabric may be used, or a nonwoven fabric containing two or more types of fibers, ie, a fiber containing a high melting point component and a fiber containing a low melting point component, may be used. can be easily obtained by As the spunlaced nonwoven fabric, a heat-sealed nonwoven fabric may be used on the condition that the number of fusion points between the constituent fibers is equal to or less than the number described above. As a heat-sealing means, an air-through method of blowing hot air or a heat embossing roll can be used. Fibers containing a high melting point component include fibers containing a thermoplastic resin such as polyethylene terephthalate (PET). Fibers containing a low-melting-point component include, for example, fibers containing a thermoplastic resin such as polyethylene (PE). Fibers using these thermoplastic resins may be used as single fibers or as composite fibers. As the composite fiber, for example, a core-sheath type composite fiber, a side-by-side composite fiber, or the like can be used. From the standpoint of enhancing liquid retention to further enhance the liquid absorbency of the absorbent sheet 1 and further reducing the emission of unpleasant odors derived from the liquid, core-sheath type conjugate fibers are used as constituent fibers of the nonwoven fabric. is preferably used.

Further, when an air-through nonwoven fabric is used as the first fiber sheet 11, the air-through nonwoven fabric is used for the purpose of making the water retention rate C1 of the first fiber sheet 11 lower than the water retention rate C2 of the second fiber sheet 12. can be embossed.

The number of fusion points between fibers is the number of fusion points present in one fiber, and is defined in units of "points/fiber". The number of fiber fusion points is measured by the following method. First, a measurement piece cut out by the same method as described above is placed on a sample stage of a scanning electron microscope (SEM) on which a carbon tape is placed and fixed. Next, from the SEM image obtained by enlarging the fiber by 150 times, the total number of portions where the intersection points of the fibers are fused together is counted. A fused portion is a portion where the boundary between fibers is unclear.
Based on the same SEM image, the length of the displayed fiber is measured from all the displayed fibers. This operation is performed from five SEM images. Separately, an SEM image magnified 35 times is obtained, 50 fibers are extracted, and the arithmetic average fiber length is taken as the fiber length of one fiber. By dividing the total fused points in the screen of the 140x SEM image by the total fiber length in the screen of the 140x SEM image and multiplying by the length of each fiber in the 35x SEM image, The number of fusion points per fiber can be measured.

Even when an external force such as body pressure is applied to the paper, the thickness of the paper itself does not easily change, and as a result, the liquid holding power of the paper does not easily change. Therefore, when paper is used as the first fibrous sheet 11, the water retention rate C1 of the first fibrous sheet 11 is less likely to be affected by the external force applied during use of the absorbent sheet, resulting in stable and excellent liquid absorption. can be obtained.
In addition, the air-through nonwoven fabric and rayon per se have excellent liquid holding power. In particular, a nonwoven fabric containing rayon as a constituent fiber has a sufficiently high liquid holding power, so that a high water retention rate C2 can be maintained even when an external force such as body pressure is applied to the nonwoven fabric. Therefore, if an air-through nonwoven fabric or a nonwoven fabric containing rayon as a constituent fiber is used as the second fiber sheet 12, the water retention rate C2 of the second fiber sheet 12 is less likely to be affected by external force applied during use of the absorbent sheet. It becomes possible to stably obtain excellent liquid absorbency.
For the above reasons, from the viewpoint of obtaining an absorbent sheet with excellent liquid absorbency, the first fiber sheet 11 is paper and the second fiber sheet 12 is an air-through nonwoven fabric, or rayon is used as a constituent fiber. It is preferable that the first fiber sheet 11 is paper and the second fiber sheet 12 is a spunlaced nonwoven fabric containing rayon as a constituent fiber.

From the viewpoint of enhancing liquid retention to further enhance the liquid absorbency of the absorbent sheet 1 and further reducing the release of unpleasant odors derived from the liquid, the basis weight of the first fiber sheet 11 is preferably 10 g/m ² or more, more preferably 13 g/m ² or more, still more preferably 15 g/m ² or more, preferably 25 g/m ² or less, more preferably 20 g/m ² or less, still more preferably 18 g/m ² It is below.
From the same point of view, the basis weight of the second fiber sheet 12 is preferably 25 g/m ² or more, more preferably 30 g/m ² or more, still more preferably 35 g/m ² or more, and preferably 60 g/m ² . Below, more preferably 50 g/m ² or less, still more preferably 45 g/m ² or less.

Another embodiment of the absorbent sheet 1 is shown in FIGS. In the following description, only the portions different from the above-described embodiment will be described, and the above description will be appropriately applied to other portions. Also, the same reference numerals are given to the same members as in the above-described embodiment.

The absorbent sheet 1 shown in FIGS. 2 and 3 comprises a first fiber sheet 11, a second fiber sheet 12, and an absorbent layer 1A arranged between the

fiber sheets

11,12. Absorbent layer 1A comprises a plurality of particles of water-absorbing polymer 13 . In addition to this, it is preferable that the first fiber sheet 11 and the second fiber sheet 12 are bonded together with an adhesive 15 . With such a structure, the adhesive strength between the two

fiber sheets

11 and 12 is high, and the strength of the absorbent sheet 1 can be increased. The adhesive 15 shown in FIG. 2 is placed on the surfaces of the

fiber sheets

11 and 12 facing the water-absorbing polymer 13 . Both the outer surfaces of the first fiber sheet 11 and the second fiber sheet 12 shown in the figure are free of the adhesive 15 and other members.

In particular, when both the

fiber sheets

11 and 12 are bonded to each other by the adhesive 15, the first fiber sheet 11 and the second fiber sheet 12 are bonded to each other without the absorbent polymer 13 in the absorbent layer 1A. A portion 17 directly joined by 15 (hereinafter also simply referred to as “directly joined portion 17”), and a portion 18 where both

fiber sheets

11 and 12 are joined by an adhesive 15 via a water-absorbent polymer 13. (Hereinafter, this is also referred to as “indirect bonding portion 18”.). With such a configuration, the water-absorbent polymer 13 can be held at a predetermined position on the absorbent sheet 1 , and unintended movement or uneven distribution of the water-absorbent polymer 13 can be further reduced. Liquid absorbency can be further enhanced.

The direct bonding sites 17 shown in FIGS. 2 and 3 are formed in the gaps between the particles of the water-absorbing polymer 13 in the region where the water-absorbing polymer 13 is arranged. In the direct bonding portion 17, when viewed in cross section in the sheet thickness direction, the adhesive 15 forms a columnar shape and directly bonds the two

fiber sheets

11 and 12 together. As shown in FIG. 3, the direct bonding sites 17 are formed in a plurality of regular or irregular scattered dots when the absorbent sheet 1 is viewed in the plane direction of the sheet.

Further, as shown in FIG. 2, when the absorbent sheet 1 is viewed in cross section, the indirect joint site 18 includes the site where the adhesive 15 is applied on the first fiber sheet 11, the site where the water-absorbing polymer 13 exists, and the site where the water-absorbent polymer 13 exists. 2 are portions where the adhesive 15 is applied on the fiber sheet 12 and overlapped in the thickness direction.

As the adhesive 15, it is preferable to use one having flexibility that can be stretched according to the swelling change accompanying the liquid absorption of the water-absorbent polymer 13. Examples of such raw materials include (co)polymers of vinyl monomers such as 2-ethylhexyl acrylate, butyl acrylate, ethyl acrylate, cyanoacrylate, vinyl acetate, and methyl methacrylate (ethylene-vinyl acetate copolymers, etc.). ), etc., silicone adhesives containing polydimethylsiloxane polymer, etc., natural rubber adhesives including natural rubber, etc., polyisoprene, chloroprene, etc. Isoprene adhesive, styrene-butadiene copolymer (SBR), styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-butadiene-styrene block copolymer Examples include rubber-based adhesives such as styrene-based adhesives containing one or more polymers (SEBS), styrene-ethylene-propylene-styrene block copolymers (SEPS), and the like. These may be used alone or in combination of two or more.

As shown in FIG. 2, when the adhesive 15 is applied to the surfaces of the

fiber sheets

11 and 12 facing the water-absorbent polymer 13, the adhesive applied to the first fiber sheet 11 and The adhesive applied to the second fiber sheet 12 may be of the same type or of a different type.

Among these, the

fiber sheets

11 and 12 are excellent in flexibility and stretchability, and the state in which the

fiber sheets

11 and 12 are directly joined is maintained even after swelling of the water-absorbent polymer, and the shrinkage force is developed to make both the

fiber sheets

11 , 12, it is preferable to use a rubber-based adhesive as the adhesive 15, and it is more preferable to use a styrene-based adhesive among the rubber-based adhesives.

From the viewpoint of achieving both flexibility of the adhesive and adhesion to the sheet, the adhesive 15 is preferably a hot-melt adhesive. Hot-melt adhesives include, for example, the various adhesives described above, tackifiers such as petroleum resins and polyterpene resins, plasticizers such as paraffin oils, and, if necessary, phenol-based, amine-based, phosphorus-based, Antioxidants such as benzimidazoles may be included.

Further, as shown in FIG. 2, adhesive 15 is applied to each of the surface of the first fiber sheet 11 facing the water-absorbing polymer 13 and the surface of the second fiber sheet 12 facing the water-absorbing polymer 13. It is preferable that With such a configuration, the adhesive applied to each of the

fiber sheets

11 and 12 is bonded together to efficiently form the direct bonding portion 17 on the absorbent sheet 1, and the water absorbent polymer 13 can be supported at an appropriate position and securing a space in which the water-absorbent polymer 13 can swell. In addition, since the adhesive 15 can easily exist in the gaps between the fibers constituting the

fiber sheets

11 and 12, peeling at the interfaces between the

fiber sheets

11 and 12 and the adhesive 15 can be prevented. It also has the advantage of being less likely to occur.

As shown in FIGS. 2 and 3, it is preferable that the coating area of the adhesive 15 on the second fiber sheet 12 is larger than the coating area of the adhesive 15 on the first fiber sheet 11 . With such a configuration, the water-absorbing polymer 13 is uniformly held on the second fiber sheet 12 having a coating area of the adhesive 15 larger than that of the first fiber sheet 11, and the water-absorbing polymer While suppressing unintended movement and falling off of 13, the adhesive 15 coating area is secured from the side of the first fiber sheet 11 smaller than the second fiber sheet 12, liquid permeability is ensured, and liquid absorbency is improved. can be further enhanced.

In order to vary the coating area of the adhesive, for example, the first fiber sheet 11 may be coated with a non-coated portion of the adhesive 15, such as spiral coating, summit coating, or omega coating. For the second fiber sheet 12, a method such as spray coating or coater coating, which can continuously apply the adhesive 15 to the sheet surface, can be used. When the adhesive is applied in this manner, the adhesive 15 is arranged so that the first fiber sheet 11 has a non-coated portion of the adhesive 15 on the surface facing the second fiber sheet 12. . Further, the second fiber sheet 12 has an adhesive 15 distributed over the entire area of the opposing surface of the first fiber sheet 11 .

The adhesive coating areas of the above-described

fiber sheets

11 and 12 are compared by laminating the

fiber sheets

11 and 12 having the same shape and area so that no sheet overlaps. . For the coating area of the adhesive 15, for example, the area where the adhesive 15 is present is visualized using an ink toner or the like on the surfaces of the

fiber sheets

11 and 12 on which the adhesive 15 is adhered. can be calculated using image processing software or the like. If it is difficult to distinguish, the measurement may be performed after peeling off both sheets using a cold spray or the like.

Focusing on the portions of the

fiber sheets

11 and 12 to which the adhesive 15 is applied, the first basis weight of the adhesive 15 applied to the first fiber sheet 11 is the same as that applied to the second fiber sheet 12 . It is preferably higher than the second basis weight of the applied adhesive 15 . With such a configuration, it is easy to form the direct bonding portion 17 with the second fiber sheet 12 via the adhesive 15 applied to the first fiber sheet 11, and the second Since the water-absorbent polymer 13 can be held in an appropriate position through the adhesive 15 applied to the fiber sheet 12, the liquid absorption performance can be further improved.

From the same point of view, the first basis weight is preferably 400 g/m ² or less, more preferably 250 g/m ² or less, still more preferably 100 g/m ² or less, and 20 g/m ² or more is realistic. be. The second basis weight is preferably 30 g/m ² or less, more preferably 15 g/m ² or less, still more preferably 10 g/m ² or less, and more preferably 2 g/m ² or more.

The above-described first basis weight and second basis weight are respectively measured and calculated for only the coated portions of the

fiber sheets

11 and 12 where the adhesive 15 is coated. Specifically, after separating the

fiber sheets

11 and 12 from the absorbent sheet 1, the mass A1 (g) of the first fiber sheet 11 with the adhesive 15 attached thereto is measured. Ink toner or the like is used to visualize the portion of the adhesive 15 on the side of the first fiber sheet 11 to which the adhesive 15 is attached, and in this state, image processing software is used. , the total area S (m ² ) of the portion where the adhesive 15 is present is measured. Next, the first fiber sheet 11 is immersed in an organic solvent, and the mass A2 (g) of the fiber sheet after dissolving the adhering adhesive 15 is measured. The first basis weight (g/m ² ) can be calculated from the formula “(A1−A2)/S”. Similarly, the second basis weight (g/m ² ) can be calculated for the second fiber sheet 12 in the same manner as described above.

The absorbent sheet 1 of the embodiment shown in FIGS. 1 and 2 and 3 described above may be used as it is. In this case, one absorbent sheet 1 may be used, or a plurality of absorbent sheets may be used in a laminated state. When using a plurality of absorbent sheets 1, only the absorbent sheet 1 of the embodiment shown in FIG. 1 or only the absorbent sheet 1 of the embodiment shown in FIGS. The absorbent sheet 1 of the above embodiment and the absorbent sheet 1 of the embodiment shown in FIGS. 2 and 3 may be used in combination.

The absorbent sheet 1 of the embodiment shown in FIGS. 1, 2 and 3 described above can be used as a constituent member of an absorbent article. Examples of absorbent articles include, but are not limited to, disposable diapers, incontinence pads, sanitary napkins, panty liners, and the like. It broadly encompasses articles used to absorb liquids.

Absorbent articles typically have a longitudinal direction along the front-rear direction of the wearer and a width direction orthogonal to the longitudinal direction, and include a topsheet and a backsheet. A liquid-retaining absorber is provided between the sheets. The absorbent article of the present invention can be provided with the absorbent sheet 1 described above as an absorbent body. Examples of absorbent articles include incontinence pads, sanitary napkins, and disposable diapers. When the absorbent sheet 1 is used as a constituent member of the absorbent article from the viewpoint of improving the liquid absorbency of the absorbent article, the absorbent sheet 1 may be used in one sheet or a plurality of sheets in a folded state. , a plurality of sheets may be used in a laminated state. Alternatively, in addition to the absorbent sheet 1, an absorbent body other than the absorbent sheet may be further laminated for use. When the absorbent sheet 1 is laminated with an absorbent body other than the absorbent sheet, the absorbent body is preferably arranged at least in the central region of the absorbent sheet 1 . Other absorbents include, for example, a pile of hydrophilic fibers such as cellulose such as pulp, and a mixed pile of hydrophilic fibers and a water-absorbing polymer.

The surface sheet used for the absorbent article is the surface facing the skin of the wearer wearing the absorbent article when the absorbent article is worn in a proper position (hereinafter, this is also referred to as the "skin facing surface". ) side, and the back sheet constitutes the side facing away from the skin of the wearer wearing the absorbent article (hereinafter also referred to as "non-skin facing side"). is a sheet. As the topsheet and the backsheet used in absorbent articles, those conventionally used in absorbent articles can be used without particular limitation. As the surface sheet, for example, various liquid-permeable nonwoven fabrics, perforated films, and the like can be used. As the back sheet, a liquid-impermeable or water-repellent resin film, a laminate of a resin film and a non-woven fabric, or the like can be used.

The absorbent used in absorbent articles has an absorbent core. The absorbent core is composed of, for example, a pile of hydrophilic fibers such as cellulose such as pulp, a mixed pile of hydrophilic fibers and a water-absorbing polymer, and a pile of water-absorbing polymer. At least the skin-facing surface of the absorbent core may be covered with a liquid-permeable core-wrap sheet, or the entire surface including the skin-facing surface and the non-skin-facing surface may be covered with the core-wrap sheet. . As the core wrap sheet, for example, a thin paper made of hydrophilic fibers, a liquid-permeable nonwoven fabric, or the like can be used.

In addition to the above-mentioned topsheet, backsheet and absorbent body, depending on the specific application of the absorbent article, leak-proof cuffs extending along the longitudinal direction are arranged on both sides along the longitudinal direction of the side facing the skin. may A leak-tight cuff generally has a proximal end and a free end. The leak-proof cuff has a base end on the skin-facing side of the absorbent article and stands up from the skin-facing side. The leak-tight cuff is constructed from a liquid-resistant or water-repellent and breathable material. An elastic member made of rubber thread or the like may be arranged in a stretched state at or near the free end of the leak-proof cuff. When the pants-type absorbent article is worn, the contraction of the elastic member causes the leak-proof cuff to stand up toward the wearer's body, and the liquid excreted on the topsheet spreads across the width of the absorbent article. Directionally outward leakage is effectively prevented.

When the absorbent sheet 1 is used as a constituent member of an absorbent article, it is preferable that the first fiber sheet 11 in the absorbent sheet 1 is arranged so as to include the liquid receiving surface. That is, it is preferable to arrange the absorbent sheet 1 so that the first fiber sheet 11 is arranged on the side facing the skin. By arranging the absorbent sheets in this manner, both the ability to draw liquid from the top sheet and the ability to retain liquid in the absorbent sheet are improved, resulting in an absorbent article with high liquid absorption. In addition, by holding the absorbed liquid in the second fiber sheet 12 located on the non-skin facing side, it is possible to reduce the diffusion of unpleasant odors derived from the liquid to the outside. Furthermore, since the liquid adhered to and permeated through the topsheet can be easily drawn into the absorbent sheet, and the dryness of the topsheet can be improved, there is an advantage that the feeling of use of the absorbent article by the wearer is improved. .

A cross-sectional view of an embodiment in which the absorbent sheet 1 is used as a constituent member of an absorbent article is schematically shown in FIGS. 4(a) and 4(b).
As shown in FIG. 4( a ), the absorbent article 50 includes a topsheet 51 arranged on the skin-facing side, a backsheet 52 arranged on the non-skin-facing side, and a topsheet 51 and a backsheet 52 . and an absorbent sheet 1 arranged between. As shown in the figure, the absorbent article 50 is preferably arranged such that one absorbent sheet 1 is folded back so that the second fiber sheets 12 face each other. In this case, one continuous first fiber sheet 11 constitutes the skin-facing surface and the non-skin-facing surface of the absorbent sheet 1 . With such a structure, the second fiber sheet 12 holding the liquid can be arranged inside the absorbent article, so that the absorbed liquid can be confined inside. In addition, the gel blocking caused by the swelling of the water-absorbing polymer 13 obstructs the flow path of the air passing through the absorbent sheet 1 in the thickness direction, thereby confining the odor. As a result, the unpleasant odor originating from the liquid retained in the second fiber sheet 12 is effectively prevented from diffusing to the outside, further improving the deodorant property of the absorbent article.

Also, as shown in FIG. 4(b), the absorbent article 50 preferably has two absorbent sheets 1 arranged in a laminated state such that the second fiber sheets face each other. In this case, the first fiber sheet 11 of one absorbent sheet 1 is arranged on the skin facing side, and the first fiber sheet 11 of the other absorbent sheet 1 is arranged on the non-skin facing side. With such a structure, the absorbed liquid and odor can be confined inside the article, and the unpleasant odor derived from the liquid retained in the second fiber sheet 12 can be diffused to the outside. is effectively prevented, and the deodorant property of the absorbent article is further improved.

The absorbent sheet 1 shown in FIG. 1 described above is formed by joining the

fiber sheets

11 and 12 by a known joining method such as embossing, for example, in a state in which a water-absorbent polymer is placed between the

fiber sheets

11 and 12. can be manufactured by This allows the particles of the water-absorbing polymer 13 to be retained between the two

fiber sheets

11,12.

Moreover, the absorbent sheet 1 shown in FIGS. An adhesive 15 is applied to each of the one surface of the . Next, particles of the water-absorbing polymer 13 are sprayed from the polymer spraying section 150 onto the surface of the second fiber sheet 12 coated with the adhesive 15 . After that, the

fiber sheets

11 and 12 are overlapped so that the adhesive-coated surfaces of the

fiber sheets

11 and 12 face each other to obtain a laminate. This laminate may be subjected to a pressing process as necessary. As a result, the absorbent sheet 1 in which the water absorbent polymer 13 is arranged between the

fiber sheets

11 and 12 can be manufactured.

Although the present invention has been described above based on its preferred embodiments, the present invention is not limited to the above embodiments.

The following absorbent sheets and absorbent articles are further disclosed with respect to the above-described embodiments.

<1>
comprising a first fibrous sheet, a second fibrous sheet, and an absorbent layer disposed between the fibrous sheets;
The first fiber sheet contains at least one of a deodorant and an antibacterial agent,
The absorbent layer contains particles of a water-absorbent polymer and does not contain water-absorbent fibers,
An absorbent sheet in which the water retention rate of the second fibrous sheet is higher than the water retention rate of the first fibrous sheet.

<2>
The absorbent sheet according to <1> above, wherein the first fiber sheet is paper.
<3>
The above <1> or <2>, wherein the second fiber sheet is a nonwoven fabric having 30 or less fusion points between constituent fibers per fiber, or a nonwoven fabric having no such fusion points. absorbent sheet.
<4>
The absorbent sheet according to any one of <1> to <3>, wherein the first fiber sheet contains a water-soluble antibacterial agent.
<5>
The absorbent sheet according to any one of <1> to <4> above, wherein the first fiber sheet has a water retention rate of 10% by mass or more and 300% by mass or less.

<6>
The absorbent sheet according to any one of <1> to <5> above, wherein the second fiber sheet has a water retention rate of 500% by mass or more.
<7>
The absorbent sheet according to any one of <1> to <6>, wherein the second fiber sheet has a water retention rate of 500% by mass or more and 1500% by mass or less.
<8>
The difference (C2-C1) between the water retention rate C1 of the first fiber sheet and the water retention rate C2 of the second fiber sheet is 200% by mass or more, provided that the water retention rate C2 is higher than the water retention rate C1. The absorbent sheet according to any one of <1> to <7>, which is 900% by mass or less.
<9>
The first fiber sheet and the second fiber sheet according to any one of <1> to <8> above, wherein both do not contain a water-absorbing polymer and are composed only of an assembly of fibers. absorbent sheet.
<10>
The first fibrous sheet and the second fibrous sheet are each independently a sheet whose shape is retained by entangling, joining or fusing the constituent fibers, or a combination thereof, the <1> to <9> The absorbent sheet according to any one of <9>.

<11>
The water-absorbing polymer is at least one of polyacrylic acid and its salts and polymethacrylic acid and its salts,
The absorbent sheet according to any one of the above <1> to <10>, which is preferably a block-shaped particle that is a partial sodium salt of an acrylic acid polymer.
<12>
including porous particles as the deodorant,
The porous particles include at least one of synthetic porous polymers, natural porous polymers, and inorganic porous substances excluding the water-absorbing polymer,
The synthetic porous polymer is one or more selected from porous methacrylic acid polymer, porous acrylic acid polymer, porous divinylbenzene polymer, porous pyridine copolymer, and copolymers thereof,
The natural porous polymer is one or more selected from chitin and chitosan,
The inorganic porous material includes zinc oxide, activated carbon, silica, silicon dioxide (silica gel), calcium silicate, aluminosilicate compounds, high silica zeolite (hydrophobic zeolite), sepiolite, cancrinite, zeolite, and hydrated zirconium oxide. The absorbent sheet according to any one of <1> to <11>, which is one or more selected from:

<13>
The deodorant contains one or more selected from water-soluble organic compounds and salts thereof,
The absorption according to any one of <1> to <12>, wherein the water-soluble organic compound is one or more selected from weak acids, weak acid conjugate bases, weak bases, weak base conjugate acids, and mixtures thereof. sex sheet.
<14>
Including an inorganic antibacterial agent as the antibacterial agent,
Any one of the above <1> to <13>, wherein the inorganic antibacterial agent is one or more selected from fine particle powder and needle crystals in which one or more of antibacterial metal ions and antibacterial metal salts are supported on a carrier. 1. The absorbent sheet according to 1.
<15>
The absorbent sheet according to <14> above, wherein the carrier is one or more selected from zeolite, silica gel, low-molecular-weight glass, calcium phosphate, zirconium phosphate, silicate and titanium oxide.
<16>
Containing a water-soluble organic antibacterial agent as the antibacterial agent,
The absorbent sheet according to any one of <1> to <15>, wherein the organic antibacterial agent contains at least one selected from cationic antibacterial agents, anionic antibacterial agents and nonionic antibacterial agents.

<17>
The anionic antibacterial agents are selected from piroctone olamine, potassium oleate, sodium 1-pentasulfonate, sodium 1-decanesulfonate, sodium butylnaphthalenesulfonate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate and sodium hexadecyl sulfate. The absorbent sheet according to <16> above, which is one or more selected.
<18>
The absorption according to <16> or <17> above, wherein the nonionic antibacterial agent is one or more selected from chlorhexidine hydrochloride, chlorhexidine gluconate, triclocarban, triclosan, isopropylmethylphenol, halocarban, and parahydroxybenzoate. sex sheet.
<19>
The cationic antibacterial agent comprises a quaternary ammonium salt,
Any one of <16> to <18> above, wherein the quaternary ammonium salt is one or more selected from alkylpyridinium salts, benzethonium salts, benzalkonium salts, monoalkyltrimethylammonium salts and dialkyldimethylammonium salts. The absorbent sheet described in .
<20>
The absorbent sheet according to any one of <1> to <19>, wherein the antibacterial agent contains at least one of piroctone olamine and benzalkonium salt.

<21>
The second fiber sheet is made of hydrophilic fibers,
The absorbent sheet according to any one of <1> to <20> above, including regenerated fibers as the hydrophilic fibers.
<22>
The absorbent sheet according to any one of <1> to <21>, wherein a spunlaced nonwoven fabric is used as the second fiber sheet.
<23>
Any one of <1> to <22> above, wherein the constituent fibers of the nonwoven fabric constituting the second fiber sheet include two or more types of fibers, ie, a high-melting-point component fiber and a low-melting-point component fiber. absorbent sheet.
<24>
The absorbent sheet according to any one of <1> to <23>, wherein the first fiber sheet and the second fiber sheet are bonded to each other with an adhesive.

<25>
The first fibrous sheet and the second fibrous sheet are divided into a portion in which both sheets are directly joined by the adhesive without passing through the water-absorbing polymer in the absorbent layer, and the above-mentioned The absorbent sheet according to <24> above, which has a portion joined with an adhesive.
<26>
The portions of the first fiber sheet and the second fiber sheet that are directly bonded by the adhesive have regular or irregular scattered dots when the absorbent sheet is viewed in the plane direction of the sheet. The absorbent sheet according to <25>, wherein a plurality of absorbent sheets are formed in a shape.
<27>
The portion where the first fiber sheet and the second fiber sheet are joined by the adhesive through the water-absorbent polymer is the adhesive in the first fiber sheet when the absorbent sheet is viewed in cross section. The absorbent sheet according to <25> or <26> above, wherein the coated portion, the water-absorbent polymer-present portion, and the adhesive-coated portion of the second fiber sheet overlap in the thickness direction. .

<28>
The absorbent according to any one of <24> to <27>, wherein the adhesive coating area in the second fiber sheet is larger than the adhesive coating area in the first fiber sheet. sheet.
<29>
The adhesive is arranged on the first fiber sheet so that the surface facing the second fiber sheet has a non-coated portion of the adhesive,
The absorbent sheet according to any one of <24> to <28>, wherein the second fiber sheet has the adhesive applied over the entire opposing surface of the first fiber sheet.
<30>
Any one of <24> to <29>, wherein the basis weight of the adhesive applied to the first fiber sheet is higher than the basis weight of the adhesive applied to the second fiber sheet. The absorbent sheet described in .
<31>
The basis weight of the adhesive applied to the first fiber sheet is 20 g/m ² or more and 400 g/m ² or less,
The absorbent sheet according to <30> above, wherein the basis weight of the adhesive applied to the second fiber sheet is 2 g/m ² or more and 30 g/m ² or less.
<32>
The absorbent sheet according to any one of <1> to <31>, wherein the second fiber sheet does not contain the water absorbent polymer.
<33>
The fact that the second fiber sheet does not contain the water-absorbent polymer means that the water-absorbent polymer is contained in the second fiber sheet in an amount of 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less. The absorbent sheet according to <32> above, which is contained in an amount of not more than mass %.

<34>
The method for producing an absorbent sheet according to any one of <1> to <33>,
applying an adhesive to at least one of the first fiber sheet and the second fiber sheet;
Sprinkling a water-absorbent polymer on the surface of the fiber sheet coated with the adhesive,
A method for producing an absorbent sheet, wherein the two fiber sheets are superimposed such that the adhesive-coated surfaces of the two fiber sheets face each other.
<35>
applying the adhesive to each of one surface of the first fiber sheet and one surface of the second fiber sheet;
The method for producing an absorbent sheet according to <34> above, wherein particles of a water-absorbing polymer are dispersed on the adhesive-coated surface of the second fiber sheet.

<36>
An absorbent article comprising the absorbent sheet according to any one of <1> to <33>.
<37>
The absorbent article according to <36> above, wherein the first fiber sheet in the absorbent sheet is arranged on the side facing the skin.
<38>
One absorbent sheet is arranged in a folded state so that the second fiber sheets face each other, or two absorbent sheets are arranged so that the second fiber sheets face each other The absorbent article according to <36> or <37>, wherein the absorbent article is arranged in a state of being layered in a layer.

The present invention will be described in more detail below with reference to examples. However, the scope of the invention is not limited to such examples.

[Example 1]
An absorbent sheet having the same basic structure as the absorbent sheet 1 shown in FIG. 1 was produced. Specifically, paper was used as the first fiber sheet. As the second fiber sheet, 80% of rayon fiber and core-sheath fiber having a core made of polypropylene (PP) and a sheath (fiber surface) made of PE (hereinafter also referred to as "PP/PE fiber") : A spunlaced nonwoven fabric was used which was blended at a mass ratio of 20%, entangled by a spunlace method, and fused by heat treatment by blowing hot air. A deodorant composed of an organic compound and an organic antibacterial agent were carried on the first fiber sheet by external addition treatment using a spray so that the content shown in Table 1 was obtained. Thereafter, 1.05 g of bulk water-absorbing polymer (SAP) was sprinkled over the entire surface between the two fiber sheets. Example 1 was obtained by bonding both fiber sheets with a hot-melt adhesive. The basis weight of the paper was 16 g/m ² and the thickness was 0.1 mm. The spunlace nonwoven fabric had a basis weight of 38 g/m ² and a thickness of 0.4 mm. There were 15 fusion points between constituent fibers in the spunlace nonwoven fabric. The water retention rate of the paper and the spunlace nonwoven fabric was measured according to the method described above, and the results obtained are shown in Table 1.

〔evaluation〕
The absorbent sheet obtained in Example 1 was evaluated for liquid absorbency and deodorizing properties by the following methods. Those results are shown in Table 1.

<Evaluation of Liquid Return Amount>
The absorbent sheet obtained in Example 1 was placed horizontally so that the first fiber sheet faced vertically upward. From the side of the first fiber sheet, 20 g of artificial urine was injected into the central area of the fiber sheet using a funnel. As artificial urine, 1.940% by weight of urea, 0.795% by weight of sodium chloride, 0.111% by weight of magnesium sulfate, 0.062% by weight of calcium chloride, 0.198% by weight of potassium sulfate, water (96.887%) and polyoxyethylene lauryl ether (0.007% by mass) were mixed to adjust the surface tension to 53±1 dyne/cm (23° C.). The injection rate was 2 g/s. After injection, it was left unpressurized for 3 minutes. Next, on the first fiber sheet, a filter paper (manufactured by Advantec Toyo Co., Ltd., No. 2, diameter 70 mm) and a 5 cm × 10 cm acrylic plate are placed, and a 1 kg weight is placed thereon. and pressurized for 5 seconds. After that, the weight, the acrylic plate and the filter paper were removed, and the mass of the filter paper was measured. The mass of the filter paper before and after the test was calculated, and the value was defined as the liquid return amount.
The amount of liquid return is closely related to the absorption performance of the absorbent sheet, especially the dry feeling of the skin-facing surface (first fiber sheet), and the smaller the amount of liquid return, the higher the absorption performance of the absorbent sheet. means that

<Evaluation of deodorant property and deodorant property>
The absorbent sheet obtained in Example 1 and 10 mL of human urine were placed in a weighing bottle, mixed, and allowed to stand for 6 hours to obtain a sample. The urine odor of this sample was sensory evaluated by five monitors according to the following evaluation criteria, and the arithmetic mean value of the obtained values was taken as the urine odor sensory value. It means that the lower the urine odor sensory value, the higher the deodorant performance.

<Urine odor evaluation criteria>
4 points: Strong urine odor.
3 points: Odor distinguishable from urine odor.
2 points: Weak urine odor.
1 point: Slight odor indistinguishable from urine odor.
0 points: Odorless.

[Example 2]
A fiber web made of 100% core-sheath fiber (hereinafter also referred to as "PET/PE fiber") having a core of PET and a sheath (fiber surface) of PE is subjected to an air-through treatment to form a non-woven fabric, and an air-through non-woven fabric is obtained. Obtained. An absorbent sheet was produced in the same manner as in Example 1, except that the obtained air-through nonwoven fabric was used as the second fiber sheet. The air-through nonwoven fabric had a basis weight of 25 g/m ² and a thickness of 0.2 mm. In addition, the water retention rate of the air-through nonwoven fabric was measured according to the method described above. Furthermore, according to the evaluation method similar to that of Example 1, the liquid return amount, deodorant property and deodorant property of the obtained absorbent sheet were evaluated. Table 1 shows the results obtained.

[Example 3]
The air-through nonwoven fabric obtained in Example 2 was further subjected to heat embossing. An absorbent sheet was produced in the same manner as in Example 2, except that the obtained air-through nonwoven fabric was used as the first fiber sheet. The air-through nonwoven fabric had a basis weight of 18 g/m ² and a thickness of 0.15 mm. In addition, the water retention rate of the air-through nonwoven fabric was measured according to the method described above. Furthermore, according to the evaluation method similar to that of Example 1, the liquid return amount, deodorant property and deodorant property of the obtained absorbent sheet were evaluated. Table 1 shows the results obtained.

[Example 4]
Paper was used as the first fiber sheet. Also, a fiber web composed of 100% PET/PE fibers was subjected to an air-through treatment to form a non-woven fabric, thereby obtaining an air-through non-woven fabric. The obtained air-through nonwoven fabric was used as the second fiber sheet. An absorbent sheet was produced in the same manner as in Example 1 except for these. The basis weight of the paper was 14 g/m ² and the thickness was 0.1 mm. The air-through nonwoven fabric had a basis weight of 25 g/m ² and a thickness of 0.3 mm. In addition, the water retention rates of the paper and air-through nonwoven fabric were measured according to the method described above. Furthermore, according to the evaluation method similar to that of Example 1, the liquid return amount, deodorant property and deodorant property of the obtained absorbent sheet were evaluated. Table 1 shows the results obtained.

[Comparative Example 1]
A spunbond nonwoven fabric made of 100% PP fibers and a meltblown nonwoven fabric made of 100% PP fibers were laminated to obtain a spunbond-meltblown-meltblown-spunbond nonwoven fabric (hereinafter also referred to as "SMMS nonwoven fabric"). An absorbent sheet was produced in the same manner as in Example 1, except that the obtained SMMS nonwoven fabric was used as the second fiber sheet. The SMMS nonwoven fabric had a basis weight of 15 g/m ² and a thickness of 0.12 mm. In addition, the water retention rate of the SMMS nonwoven fabric was measured according to the method described above. Furthermore, according to the evaluation method similar to that of Example 1, the liquid return amount, deodorant property and deodorant property of the obtained absorbent sheet were evaluated. Table 1 shows the results obtained.

[Comparative Example 2]
An absorbent sheet was produced in the same manner as in Example 1, except that the same paper as the first fiber sheet was used as the second fiber sheet. In addition, according to the evaluation method similar to that of Example 1, the liquid return amount, deodorant property and deodorant property of the obtained absorbent sheet were evaluated. Table 1 shows the results obtained.

As is clear from the results shown in Table 1, the absorbent sheets obtained in Examples had a lower amount of liquid return, which is an evaluation item related to liquid absorbency, compared to the absorbent sheets obtained in Comparative Examples. I understand.

According to the present invention, an absorbent sheet with excellent liquid absorbency, deodorizing properties and deodorizing properties and an absorbent article comprising the sheet are provided.

Claims

comprising a first fibrous sheet, a second fibrous sheet, and an absorbent layer disposed between the fibrous sheets;
The first fiber sheet contains at least one of a deodorant and an antibacterial agent,
The absorbent layer contains particles of a water-absorbent polymer and does not contain water-absorbent fibers,
An absorbent sheet in which the water retention rate of the second fibrous sheet is higher than the water retention rate of the first fibrous sheet.
The absorbent sheet according to claim 1, wherein the first fibrous sheet is paper.
The absorbent according to claim 1 or 2, wherein the second fiber sheet is a nonwoven fabric having 30 or less fusion points between constituent fibers per fiber, or a nonwoven fabric having no such fusion points. sheet.
The absorbent sheet according to any one of claims 1 to 3, wherein the first fiber sheet contains a water-soluble antibacterial agent.
The absorbent sheet according to any one of claims 1 to 4, wherein the water retention rate of the first fiber sheet is 10% by mass or more and 300% by mass or less.
The absorbent sheet according to any one of claims 1 to 5, wherein the second fiber sheet has a water retention rate of 500% by mass or more.
The absorbent sheet according to any one of claims 1 to 6, wherein the second fiber sheet has a water retention rate of 500% by mass or more and 1500% by mass or less.
The difference (C2-C1) between the water retention rate C1 of the first fiber sheet and the water retention rate C2 of the second fiber sheet is 200% by mass or more, provided that the water retention rate C2 is higher than the water retention rate C1. The absorbent sheet according to any one of claims 1 to 7, which is 900% by mass or less.
The absorbent according to any one of claims 1 to 8, wherein the first fiber sheet and the second fiber sheet do not contain a water-absorbing polymer and are composed only of an assembly of fibers. sex sheet.
Claims 1 to 9, wherein the first fiber sheet and the second fiber sheet are sheets whose shape is maintained independently by entangling, joining or fusing constituent fibers, or a combination thereof. Absorbent sheet according to any one of.
The water-absorbing polymer is at least one of polyacrylic acid and its salts and polymethacrylic acid and its salts,
The absorbent sheet according to any one of claims 1 to 10, which is an agglomerated particle, preferably an acrylic acid polymer partial sodium salt.
including porous particles as the deodorant,
The porous particles include at least one of synthetic porous polymers, natural porous polymers, and inorganic porous substances excluding the water-absorbing polymer,
The synthetic porous polymer is one or more selected from porous methacrylic acid polymer, porous acrylic acid polymer, porous divinylbenzene polymer, porous pyridine copolymer, and copolymers thereof,
The natural porous polymer is one or more selected from chitin and chitosan,
The inorganic porous material includes zinc oxide, activated carbon, silica, silicon dioxide (silica gel), calcium silicate, aluminosilicate compounds, high silica zeolite (hydrophobic zeolite), sepiolite, cancrinite, zeolite, and hydrated zirconium oxide. The absorbent sheet according to any one of claims 1 to 11, which is one or more selected from.
The deodorant contains one or more selected from water-soluble organic compounds and salts thereof,
The absorbent sheet according to any one of claims 1 to 12, wherein the water-soluble organic compound is one or more selected from weak acids, weak acid conjugate bases, weak bases, weak base conjugate acids, and mixtures thereof. .
Including an inorganic antibacterial agent as the antibacterial agent,
The inorganic antibacterial agent is one or more selected from fine particle powder and needle-like crystals in which one or more kinds of antibacterial metal ions and antibacterial metal salts are supported on a carrier, according to any one of claims 1 to 13. The absorbent sheet described in .
The absorbent sheet according to claim 14, wherein the carrier is one or more selected from zeolite, silica gel, low molecular weight glass, calcium phosphate, zirconium phosphate, silicate and titanium oxide.
Containing a water-soluble organic antibacterial agent as the antibacterial agent,
The absorbent sheet according to any one of claims 1 to 15, wherein the organic antibacterial agent contains one or more selected from cationic antibacterial agents, anionic antibacterial agents and nonionic antibacterial agents.
The anionic antibacterial agents are selected from piroctone olamine, potassium oleate, sodium 1-pentasulfonate, sodium 1-decanesulfonate, sodium butylnaphthalenesulfonate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate and sodium hexadecyl sulfate. 17. The absorbent sheet according to claim 16, which is one or more selected.
The absorbent sheet according to claim 16 or 17, wherein the nonionic antibacterial agent is one or more selected from chlorhexidine hydrochloride, chlorhexidine gluconate, triclocarban, triclosan, isopropylmethylphenol, halocarban and paraoxybenzoic acid ester.
The cationic antibacterial agent comprises a quaternary ammonium salt,
The quaternary ammonium salt is one or more selected from alkylpyridinium salts, benzethonium salts, benzalkonium salts, monoalkyltrimethylammonium salts and dialkyldimethylammonium salts, according to any one of claims 16 to 18. absorbent sheet.
The absorbent sheet according to any one of claims 1 to 19, wherein the antibacterial agent contains at least one of piroctone olamine and benzalkonium salt.
The second fiber sheet is made of hydrophilic fibers,
The absorbent sheet according to any one of claims 1 to 20, comprising regenerated fibers as said hydrophilic fibers.
The absorbent sheet according to any one of claims 1 to 21, wherein a spunlaced nonwoven fabric is used as the second fiber sheet.
The absorbent according to any one of claims 1 to 22, wherein the nonwoven fabric constituting the second fiber sheet contains two or more types of fibers, ie, a high melting point component fiber and a low melting point component fiber. sheet.
The absorbent sheet according to any one of Claims 1 to 23, wherein the first fiber sheet and the second fiber sheet are bonded to each other with an adhesive.
The first fibrous sheet and the second fibrous sheet are divided into a portion in which both sheets are directly joined by the adhesive without passing through the water-absorbing polymer in the absorbent layer, and the above-mentioned 25. The absorbent sheet according to claim 24, having portions joined by an adhesive.
The portions of the first fiber sheet and the second fiber sheet that are directly bonded by the adhesive have regular or irregular scattered dots when the absorbent sheet is viewed in the plane direction of the sheet. 26. The absorbent sheet according to claim 25, which is formed in a plurality of shapes.
The portion where the first fiber sheet and the second fiber sheet are joined by the adhesive through the water-absorbent polymer is the adhesive in the first fiber sheet when the absorbent sheet is viewed in cross section. 27. The absorbent sheet according to claim 25 or 26, wherein the coated portion of the second fiber sheet, the portion where the water-absorbent polymer is present, and the adhesive-coated portion of the second fiber sheet overlap each other in the thickness direction.
The absorbent sheet according to any one of claims 24 to 27, wherein the area of the second fiber sheet to which the adhesive is applied is larger than the area of the adhesive to be applied to the first fiber sheet.
The adhesive is arranged on the first fiber sheet so that the surface facing the second fiber sheet has a non-coated portion of the adhesive,
The absorbent sheet according to any one of Claims 24 to 28, wherein the second fiber sheet has the adhesive applied over the entire surface facing the first fiber sheet.
The basis weight of the adhesive applied to the first fiber sheet is higher than the basis weight of the adhesive applied to the second fiber sheet, according to any one of claims 24 to 29. absorbent sheet.
The basis weight of the adhesive applied to the first fiber sheet is 20 g/m 2 or more and 400 g/m 2 or less,
The absorbent sheet according to claim 30, wherein the basis weight of the adhesive applied to the second fiber sheet is 2 g/ m2 or more and 30 g/ m2 or less.
The absorbent sheet according to any one of claims 1 to 31, wherein the second fiber sheet does not contain the water absorbent polymer.
The fact that the second fiber sheet does not contain the water-absorbent polymer means that the water-absorbent polymer is contained in the second fiber sheet in an amount of 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less. 33. The absorbent sheet according to claim 32, wherein the content is mass % or less.
A method for producing an absorbent sheet according to any one of claims 1 to 33,
applying an adhesive to at least one of the first fiber sheet and the second fiber sheet;
Sprinkling a water-absorbent polymer on the surface of the fiber sheet coated with the adhesive,
A method for producing an absorbent sheet, wherein the two fiber sheets are superimposed such that the adhesive-coated surfaces of the two fiber sheets face each other.
applying the adhesive to each of one surface of the first fiber sheet and one surface of the second fiber sheet;
35. The method for producing an absorbent sheet according to claim 34, wherein particles of water-absorbent polymer are dispersed on the adhesive-coated surface of the second fiber sheet.
An absorbent article comprising the absorbent sheet according to any one of claims 1 to 33.
The absorbent article according to claim 36, wherein the first fiber sheet in the absorbent sheet is arranged on the side facing the skin.
One absorbent sheet is arranged in a folded state so that the second fiber sheets face each other, or two absorbent sheets are arranged so that the second fiber sheets face each other 38. The absorbent article of claim 36 or 37, wherein the absorbent article is arranged in a laminated state.