JP6930424B2 - Absorbent article - Google Patents

Description

The present invention relates to an absorbent article.

In recent years, various studies on absorbent articles such as disposable diapers have been promoted. Examples of such a technique include those described in Patent Documents 1 and 2.

Patent Document 1 relates to an absorbent article having an absorbent core, a core wrap sheet covering the absorbent core, and a liquid-permeable outer layer sheet covering the core wrap sheet. Specifically, it is characterized by using a core wrap sheet made of thin paper containing metal-supported cellulose fibers in which specific metal particles are supported on oxidized cellulose fibers having a carboxyl group or a carboxylate group on the surface. Is. Patent Document 2 relates to an absorbent article comprising a surface sheet, a back sheet, and an absorber interposed between the surface sheet and the back sheet. Specifically, it is characterized by using an absorber containing a metal-supporting cellulose fiber obtained by supporting specific metal particles on an oxide cellulose fiber having a carboxyl group or a carboxylate group on the surface.

JP-A-2015-43940 Japanese Unexamined Patent Publication No. 2015-84870

For absorbent articles, it is required to improve the balance between water absorption and deodorant property.

According to the present invention, the following inventions are provided.
[1] A back sheet, a top sheet, and an absorber arranged between the back sheet and the top sheet are provided.
The absorber is an absorbent article containing a phosphoric acid group or a phosphorylated cellulose fiber having a substituent derived from a phosphoric acid group.
[2] The absorbent article according to [1], wherein the phosphorylated cellulose fiber contains fine fibers having a fiber width of 1000 nm or less.
[3] The method according to [1] or [2], which comprises one or more metal components selected from the group consisting of Ag, Au, Pt, Pd, Cu and Zn supported on the phosphorylated cellulose fiber. Absorbent article.
[4] The absorber is any one of [1] to [3], which is composed of an absorbent main body containing the phosphorylated cellulose fiber and a water-absorbent resin, and a coating member covering the absorbent main body. The absorbent article described in 1.
[5] The absorber is composed of an absorbent main body containing a water-absorbent resin and a coating member that covers the absorbent main body and contains the phosphorylated cellulose fiber [1] to [3]. The absorbent article according to any one of.

According to the present invention, it is possible to realize an absorbent article having an excellent balance between water absorption and deodorant property.

It is sectional drawing which shows the absorbent article which concerns on this embodiment. It is a graph which shows the relationship between the amount of hydroxide dropped with respect to a fiber raw material, and the electric conductivity.

Hereinafter, the present invention will be described in more detail. The description of the materials, methods, numerical ranges, etc. described in the present specification is not intended to be limited to the materials, methods, numerical ranges, etc., and other materials, methods, and numerical ranges. It does not exclude the use of.

FIG. 1 is a schematic cross-sectional view showing an absorbent article 100 according to the present embodiment.
The absorbent article 100 according to the present embodiment includes a back sheet 30, a top sheet 20, and an absorber 10 arranged between the back sheet 30 and the top sheet 20. The absorber 10 contains a phosphoric acid group or a phosphorylated cellulose fiber having a substituent derived from the phosphoric acid group.

The inventor of the present invention includes a phosphorylated cellulose fiber having a phosphoric acid group or a substituent derived from a phosphoric acid group in the absorbent body 10 constituting the absorbent article 100, thereby absorbing water and deodorizing the absorbent body 10. It was newly found that the balance of the above can be improved. As described above, according to the present embodiment, it is possible to realize an absorbent article having an excellent balance between water absorption and deodorant property.

Hereinafter, the absorbent article 100 according to the present embodiment will be described in detail.

As shown in FIG. 1, the absorbent article 100 includes, for example, a liquid-permeable top sheet 20, a liquid-impermeable back sheet 30, and an absorber 10 interposed between the top sheet 20 and the back sheet 30. I'm out. Further, the absorbent article 100 has, for example, a pair of side sheets 50 on the left and right side portions of the absorber 10. Further, the absorbent article 100 includes, for example, a cover sheet 60 that covers the back sheet 30 from the skin non-contact surface side. The absorbent article 100 according to the present embodiment is applied to an article worn on a wearer for the purpose of absorbing and retaining body fluid, such as a disposable diaper, a sanitary napkin, a urine absorbing pad, or an absorbent pad. be able to.

The top sheet 20 is a sheet-like member that comes into direct contact with the skin of the wearer's inseam and allows a liquid such as urine to permeate through the absorber 10. Therefore, the top sheet 20 is made of a highly flexible liquid permeable material. The top sheet 20 is arranged so as to cover the absorber 10 from the skin contact surface side. The top sheet 20 and the absorber 10 may be fixed with a known adhesive such as a hot melt adhesive.

Examples of the liquid permeable material constituting the top sheet 20 are a woven fabric, a non-woven fabric, or a porous film. Further, as the top sheet 20, a fiber of a thermoplastic resin such as polypropylene, polyethylene, polyester, or nylon may be subjected to a hydrophilic treatment to form a non-woven fabric. Examples of the non-woven fabric constituting the top sheet 20 include those obtained by processing natural fibers such as cotton by a processing method such as a spunbond method, a spunlace method, a thermal bond method, a melt blown method, or a needle punch method. Among the non-woven fabric processing methods, the non-woven fabric formed by the spunbond method is excellent in flexibility and drapeability. Further, the thermal bond method has an advantage that a bulky and soft non-woven fabric can be obtained.

The back sheet 30 is a sheet-like member for preventing the liquid that has passed through the top sheet 20 and is absorbed by the absorber 10 from leaking out. Therefore, the back sheet 30 is made of a liquid-impermeable material. The back sheet 30 is arranged so as to cover the absorber 10 from the skin non-contact surface side. The back sheet 30 and the absorber 10 may be fixed with a known adhesive such as a hot melt adhesive.

An example of the liquid-impermeable material constituting the back sheet 30 is an olefin resin sheet such as polyethylene or polypropylene, and a sheet material having at least a liquid-shielding property is used. Further, as the back sheet 30, a microporous breathable resin sheet obtained by kneading an inorganic filler in an olefin resin such as polyethylene or polypropylene to form a sheet and then stretching the sheet can also be used. can. In addition, as the back sheet 30, a laminated non-woven fabric sheet in which a non-woven fabric is laminated on a polyethylene sheet or the like, or a non-woven fabric sheet in which a waterproof film is interposed to ensure substantial liquid impermeableness can also be used. In particular, it is preferable to use a microporous polyethylene film in which a plurality of fine pores of 0.1 μm or more and 4 μm or less are formed as the back sheet 30.

The absorber 10 is a member for absorbing a liquid such as urine and holding the absorbed liquid. The absorber 10 is arranged between the top sheet 20 and the back sheet 30 and has a function of absorbing the liquid that has passed through the top sheet 20. Further, the absorbent body 10 is configured by, for example, covering the absorbent layer 12 with the core wrap sheet 14.

The shape of the absorber 10 is preferably an hourglass shape. The hourglass type means that the absorber 10 has an extending portion extending outward in the width direction on the front body side and the back body side. Since the hourglass-shaped absorber 10 has extended portions formed at the four corners on the front body side and the back body side, the crotch portion in the center of the longitudinal direction is curved or refracted inward of the absorber 10. A constricted part is formed. By forming the absorber 10 into an hourglass shape as described above, the central portion of the absorber 10 in the longitudinal direction has a constricted shape that matches the shape of both legs of the wearer, so that the disposable diaper has a good wearing feeling. Can be. However, the shape of the absorber 10 is not limited to the hourglass shape, and may be a rectangular shape, an elliptical shape, or a gourd shape.

The absorbent layer 12 constituting the absorbent body 10 contains, for example, hydrophilic fibers and a highly water-absorbent resin (SAP). Hydrophilic fibers include, for example, one or more of wood fluff pulp, synthetic fibers, and polymer fibers. The core wrap sheet 14 is made of, for example, a non-woven fabric having excellent breathability and liquid permeability. The type of the non-woven fabric is not particularly limited, and for example, known non-woven fabrics such as spunbonded non-woven fabric, needle punched non-woven fabric, spunlace non-woven fabric, and air-through non-woven fabric can be appropriately adopted. Further, a known tissue paper may be used for the core wrap sheet 14.

As described above, the absorber 10 contains a phosphorylated cellulose fiber having a phosphoric acid group or a substituent derived from a phosphoric acid group (hereinafter, may be simply referred to as a phosphoric acid group). This makes it possible to improve the balance between water absorption and deodorant property in the absorbent article 100. In the present embodiment, the content of the phosphorylated cellulose fiber in the absorber 10 is preferably 10 parts by weight or more and 70 parts by weight or less, for example, assuming that the total of the hydrophilic fiber and the highly water-absorbent resin is 100 parts by weight. More preferably, it is 20 parts by weight or more and 50 parts by weight or less. Thereby, the balance between water absorption and deodorant property can be improved more effectively.

As an example of the present embodiment, the absorber 10 is composed of an absorbent main body (absorbent layer 12) containing phosphorylated cellulose fibers and a water-absorbent resin, and a coating member (core wrap sheet 14) that covers the absorbent main body. It may be configured. In this case, the absorber 10 is composed of an absorbent layer 12 containing, for example, wood fluff pulp formed of phosphorylated cellulose fibers as hydrophilic fibers. Further, in the absorbent body 10, phosphorylated fine cellulose fibers may be added to the absorbent layer 12 containing, for example, hydrophilic fibers and a highly water-absorbent resin.
The content of the phosphorylated cellulose fiber contained in the absorbent body (absorbent layer 12) should be large from the viewpoint of improving water absorption and deodorant property, but an upper limit may be set in some cases. By setting the content of the phosphorylated cellulose fiber contained in the absorbent body (absorbent layer 12) to less than 5% by mass of the entire absorbent body, for example, the absorbent body can be absorbed without impairing the operability during manufacturing. It is possible to improve the balance between the water absorption and the deodorant property of the article 100.

As another example of the present embodiment, the absorbent body 10 covers the absorbent main body (absorbent layer 12) containing the water-absorbent resin and the covering member (core wrap sheet) containing the phosphorylated cellulose fiber. 14) and, there are cases where it is composed of. In this case, the covering member may be formed of a non-woven fabric obtained by papermaking phosphorylated cellulose fibers, or phosphorylated fine cellulose fibers may be added to the non-woven fabric constituting the covering member.
By reducing the content of phosphorylated cellulose fibers contained in the covering member (core wrap sheet 14) that coats the absorbent body to less than 5% by mass of the entire covering member, for example, the operability at the time of manufacturing the core wrap sheet is impaired. It is possible to improve the balance between the water absorption and the deodorant property of the absorbent article 100.

The phosphoric acid group contained in the phosphorylated cellulose fiber is a divalent functional group obtained by removing the hydroxyl group from the phosphoric acid. Specifically, it is a group represented by _{−PO 3} H _2. Substituents derived from phosphoric acid groups include substituents such as polycondensation groups of phosphoric acid groups, salts of phosphoric acid groups, and phosphoric acid ester groups. Further, in the specification of the present application, the phosphoric acid group or the substituent derived from the phosphoric acid group may be a nonionic substituent or an ionic substituent represented by the following formula (1). ..

In equation (1), a, b, m and n each independently represent an integer (where a = b × m); α ⁿ (an integer of n = 1 to n) and α'are independent of each other. Represents R or OR. R is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched chain hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched chain hydrocarbon group. , Aromatic groups, or inducing groups thereof; β is a monovalent or higher cation consisting of an organic or inorganic substance.

In the present embodiment, the content of the phosphoric acid group of the phosphorylated cellulose fiber or the substituent derived from the phosphoric acid group is, for example, 0.1 mmol / g or more. The content of the phosphoric acid group or the substituent derived from the phosphoric acid group is preferably 0.5 mmol / g or more, and more preferably 0.8 mmol / g or more. On the other hand, the content of the phosphoric acid group of the phosphorylated cellulose fiber or the substituent derived from the phosphoric acid group can be, for example, 3.5 mmol / g or less. This makes it possible to more effectively improve the balance between water absorption and deodorant property in the absorbent article.

The amount of the phosphoric acid group introduced into the cellulose fiber can be measured by the conductivity titration method. In the present embodiment, the amount of introduction can be measured by determining the change in electrical conductivity while adding, for example, an aqueous sodium hydroxide solution.

In the conductivity titration, the addition of alkali gives the curve shown in FIG. Initially, the electrical conductivity drops sharply (hereinafter referred to as the "first region"). After that, the conductivity begins to increase slightly (hereinafter referred to as "second region"). After that, the increment of conductivity increases (hereinafter referred to as "third region"). The boundary point between the second region and the third region is defined by the point at which the second derivative value of the conductivity, that is, the amount of change in the increment (slope) of the conductivity is maximized. That is, three regions appear. Of these, the amount of alkali required in the first region is equal to the amount of strong acid groups in the slurry used for titration, and the amount of alkali required in the second region is equal to the amount of weakly acidic groups in the slurry used for titration. Become equal. When the phosphoric acid group causes condensation, the weakly acidic group is apparently lost, and the amount of alkali required for the second region is smaller than the amount of alkali required for the first region. On the other hand, the amount of strongly acidic groups is the same as the amount of phosphorus atoms regardless of the presence or absence of condensation. When it is said, it means the amount of strongly acidic groups.

In the present embodiment, the introduction of the phosphoric acid group into the cellulose fiber can be carried out by reacting the fiber raw material with a compound having a phosphoric acid group and / or a salt thereof (hereinafter, referred to as "Compound A"). .. This reaction may be carried out in the presence of urea and / or a derivative thereof (hereinafter referred to as "Compound B"). This makes it possible to efficiently introduce a phosphoric acid group into the hydroxyl group of the cellulose fiber.

The phosphoric acid group introduction step always includes a step of introducing a phosphoric acid group into cellulose, and may optionally include an alkali treatment step described later, a step of washing excess reagents, and the like.

The fiber raw material is not particularly limited, but pulp is preferably used because it is easily available and inexpensive. Examples of the pulp include wood pulp, non-wood pulp, and deinked pulp. Examples of wood pulp include broadleaf kraft pulp (LBKP), coniferous kraft pulp (NBKP), sulfite pulp (SP), dissolved pulp (DP), soda pulp (AP), unbleached kraft pulp (UKP), and oxygen bleached craft. Examples thereof include chemical pulp such as pulp (OKP). Further, semi-chemical pulp such as semi-chemical pulp (SCP) and chemiground wood pulp (CGP), mechanical pulp such as crushed wood pulp (GP) and thermomechanical pulp (TMP, BCTMP) and the like can be mentioned, but are not particularly limited. Examples of the non-wood pulp include cotton pulp such as cotton linter and cotton lint, non-wood pulp such as hemp, straw and bagasse, and cellulose, chitin and chitosan isolated from sea squirts and seaweed, but are not particularly limited. .. Examples of the deinked pulp include deinked pulp made from used paper, but the deinking pulp is not particularly limited. As the pulp of the present embodiment, one of the above types may be used alone, or two or more types may be mixed and used. Among the above pulps, wood pulp containing cellulose and deinked pulp are preferable in terms of availability. Among wood pulps, chemical pulp has a large cellulose ratio, so the yield of fine fibrous cellulose during fiber refining (defibration) is high, the decomposition of cellulose in the pulp is small, and the fine fibers with a large axial ratio are fine. It is preferable in that fibrous cellulose can be obtained. Of these, kraft pulp and sulfite pulp are most preferably selected.

As an example of the method of allowing the compound A to act on the fiber raw material in the coexistence of the compound B, a method of mixing the powder or the aqueous solution of the compound A and the compound B with the fiber raw material in a dry state or a wet state can be mentioned. Another example is a method of adding a powder or an aqueous solution of Compound A and Compound B to a slurry of a fiber raw material. Of these, since the reaction uniformity is high, a method of adding an aqueous solution of compound A and compound B to a dry fiber raw material, or adding a powder or aqueous solution of compound A and compound B to a wet fiber raw material. The method is preferred. Further, compound A and compound B may be added at the same time or separately. Alternatively, compound A and compound B to be tested in the reaction may be added as an aqueous solution first, and the excess chemical solution may be removed by squeezing. The form of the fiber raw material is preferably cotton-like or thin sheet-like, but is not particularly limited.

Compound A used in this embodiment is a compound having a phosphoric acid group and / or a salt thereof.
Examples of the compound having a phosphoric acid group include, but are not limited to, phosphoric acid, a lithium salt of phosphoric acid, a sodium salt of phosphoric acid, a potassium salt of phosphoric acid, an ammonium salt of phosphoric acid, and the like. Examples of the lithium salt of phosphoric acid include lithium dihydrogen phosphate, dilithium hydrogen phosphate, trilithium phosphate, lithium pyrophosphate, and lithium polyphosphate. Examples of the sodium salt of phosphoric acid include sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate, and sodium polyphosphate. Examples of the potassium salt of phosphoric acid include potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, potassium polyphosphate and the like. Examples of the ammonium salt of phosphoric acid include ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, and ammonium polyphosphate.

Of these, from the viewpoints of high efficiency of introducing phosphoric acid groups, easy improvement of defibration efficiency in the defibration step described later, low cost, and easy industrial application, sodium phosphate and sodium phosphate A salt, a potassium salt of phosphoric acid, or an ammonium salt of phosphoric acid is preferable. Sodium dihydrogen phosphate or disodium hydrogen phosphate is more preferred.

Further, the compound A is preferably used as an aqueous solution because the uniformity of the reaction is enhanced and the efficiency of introducing the phosphoric acid group is increased. The pH of the aqueous solution of compound A is not particularly limited, but is preferably 7 or less because the efficiency of introducing a phosphoric acid group is high, and more preferably 3 or more and pH 7 or less from the viewpoint of suppressing hydrolysis of pulp fibers. The pH of the aqueous solution of the compound A may be adjusted, for example, by using a compound having a phosphoric acid group that exhibits acidity and an alkalinity in combination and changing the amount ratio thereof. The pH of the aqueous solution of the compound A may be adjusted by adding an inorganic alkali or an organic alkali to the compound having a phosphoric acid group and showing acidity.

The amount of compound A added to the fiber raw material is not particularly limited, but when the amount of compound A added is converted into the phosphorus atomic weight, the amount of phosphorus atom added to the fiber raw material is preferably 0.5% by mass or more and 100% by mass or less. It is more preferably mass% or more and 50 mass% or less, and most preferably 2 mass% or more and 30 mass% or less. When the amount of phosphorus atom added to the fiber raw material is within the above range, the yield of phosphorylated cellulose fiber can be further improved. By setting the addition amount of phosphorus atoms to the fiber raw material to 100% by mass or less, the production cost can be suppressed. On the other hand, the yield can be increased by setting the addition amount of phosphorus atoms to the fiber raw material to be equal to or higher than the above lower limit value.

Examples of the compound B used in this embodiment include urea, thiourea, biuret, phenylurea, benzylurea, dimethylurea, diethylurea, tetramethylurea, benzorainurea, and hydantin. Of these, urea is preferable because it is low in cost, easy to handle, and easy to form a hydrogen bond with a fiber raw material having a hydroxyl group.

Compound B is preferably used as an aqueous solution like compound A. Further, since the uniformity of the reaction is enhanced, it is preferable to use an aqueous solution in which both compound A and compound B are dissolved. The amount of compound B added to the fiber raw material is preferably 1% by mass or more and 300% by mass or less.

In addition to Compound A and Compound B, amides or amines may be included in the reaction system. Examples of amides include formamide, dimethylformamide, acetamide, dimethylacetamide and the like. Examples of amines include methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, hexamethylenediamine and the like. Among these, triethylamine in particular is known to act as a good reaction catalyst.

It is preferable to perform heat treatment in the phosphoric acid group introduction step. The heat treatment temperature is, for example, preferably 50 ° C. or higher and 250 ° C. or lower, and more preferably 100 ° C. or higher and 200 ° C. or lower. Further, a vacuum dryer, an infrared heating device, and a microwave heating device may be used for heating.

During the heat treatment, when the fiber raw material slurry containing the compound A contains water and the fiber raw material is allowed to stand for a long time, the water molecules and the dissolved compound A move to the surface of the fiber raw material as it dries. do. Therefore, the concentration of the compound A in the fiber raw material may be uneven, and the introduction of the phosphoric acid group to the fiber surface may not proceed uniformly. In order to suppress the occurrence of uneven concentration of compound A in the fiber raw material due to drying, a very thin sheet-shaped fiber raw material is used, or the fiber raw material and compound A are kneaded and / or stirred with a kneader or the like and dried by heating or reducing the pressure. The method of drying may be adopted.

The heating device used for the heat treatment is preferably a device capable of constantly discharging the water retained by the slurry and the water generated by the addition reaction of fibers such as phosphoric acid groups to the hydroxyl groups to the outside of the device system. For example, a ventilation type oven. Etc. are preferable. If the water in the apparatus system is constantly discharged, the hydrolysis reaction of the phosphate ester bond, which is the reverse reaction of the phosphate esterification, can be suppressed, and the acid hydrolysis of the sugar chain in the fiber can also be suppressed. , Fine fibers with a high axial ratio can be obtained. Although the heat treatment time is affected by the heating temperature, it is preferably 1 minute or more and 300 minutes or less after the water is substantially removed from the fiber raw material slurry, and more preferably 1 minute or more and 200 minutes or less. It is preferable, but is not particularly limited.

In the present embodiment, after the phosphorylation treatment step, the obtained phosphoric acid group-introduced fiber can be subjected to an alkali treatment. The alkaline treatment method is not particularly limited, and examples thereof include a method of immersing the phosphate group-introduced fiber in an alkaline solution.
The alkaline compound contained in the alkaline solution is not particularly limited, but may be an inorganic alkaline compound or an organic alkaline compound. The solvent in the alkaline solution may be either water or an organic solvent. The solvent is preferably a polar solvent (water or a polar organic solvent such as alcohol), and more preferably an aqueous solvent containing at least water.
Further, among the alkaline solutions, an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide is particularly preferable because of its high versatility.

The temperature of the alkaline solution in the alkaline treatment step is not particularly limited, but is preferably 5 ° C. or higher and 80 ° C. or lower, and more preferably 10 ° C. or higher and 60 ° C. or lower. The immersion time in the alkaline solution in the alkaline treatment step is not particularly limited, but is preferably 5 minutes or more and 30 minutes or less, and more preferably 10 minutes or more and 20 minutes or less. The amount of the alkaline solution used in the alkaline treatment is not particularly limited, but is preferably 100% by mass or more and 100,000% by mass or less, and 1,000% by mass or more and 10,000% by mass or less with respect to the absolute dry mass of the phosphate group-introduced fiber. Is more preferable.

In order to reduce the amount of the alkaline solution used in the alkaline treatment step, the phosphate group-introduced fibers may be washed with water or an organic solvent before the alkaline treatment step. After the alkali treatment, it is preferable to wash the alkali-treated phosphoric acid group-introduced fiber with water or an organic solvent before the defibration treatment step in order to improve the handleability.

The phosphorylated cellulose fiber contained in the absorber 10 can include, for example, fine fibers having a fiber width of 1000 nm or less. Thereby, the absorbability of the absorbent article can be improved more effectively. In the present embodiment, it is preferable that the absorber 10 contains monofilament-like phosphorylated cellulose fibers having a fiber width of 1000 nm or less. The fiber width of the phosphorylated cellulose fiber can be determined by, for example, image analysis by TEM, SEM, or AFM. The lower limit of the fiber width of the fine fibers can be, for example, 2 nm.
The average fiber width of the fine fibers can be, for example, 2 nm or more and 1000 nm or less, and more preferably 2 nm or more and 100 nm or less. Thereby, the balance between water absorption and deodorant property can be improved more effectively. The average fiber width of the fine fibers contained in the absorber 10 can be calculated from, for example, 100 arbitrary single fibrous fine fibers contained in the absorber 10 selected and the average value of the fiber widths thereof. ..

The fiber length of the fine fibers is not particularly limited, but is preferably 0.1 μm or more and 1000 μm or less, more preferably 0.1 μm or more and 800 μm or less, and particularly preferably 0.1 μm or more and 600 μm or less. By setting the fiber length within the above range, destruction of the crystal region of the fine fiber can be suppressed. The fiber length of the fine fiber can be obtained by image analysis by, for example, TEM, SEM, or AFM.

The phosphorylated cellulose fiber contained in the absorber 10 preferably contains fine fibers having a fiber width of 1000 nm or less in an amount of 50% by mass or more, more preferably 70% by mass or more, and 90% by mass, based on the entire phosphorylated cellulose fiber. It is particularly preferable to contain% or more. On the other hand, the upper limit of the content of the fine fibers contained in the phosphorylated cellulose fibers is not particularly limited, but may be, for example, 100% by mass. This makes it possible to more effectively improve the balance between the water absorption and the deodorant property of the absorbent article 100. On the other hand, the content of the fine fibers in the entire phosphorylated cellulose fibers may be less than 50% by mass. In the present embodiment, for example, an embodiment in which the phosphorylated cellulose fibers contained in the absorber 10 do not contain fine fibers having a fiber width of 1000 nm or less can be adopted. Here, the term "not containing fine fibers" refers to a case where the content of fine fibers in the entire phosphorylated cellulose fibers is 5% by mass or less. As a result, the handleability of phosphorylated cellulose can be improved and the cost can be reduced. The content of the fine fibers in the entire phosphorylated cellulose fibers may be 0% by mass.

The fine fibers can be obtained, for example, by defibrating a phosphorylated cellulose raw material. In the defibration treatment step, the fibers are usually defibrated using a defibration treatment device to obtain a fine fibrous cellulose-containing slurry, but the treatment device and the treatment method are not particularly limited. As the defibration processing apparatus, a high-speed defibrator, a grinder (stone mill type crusher), a high-pressure homogenizer, an ultra-high pressure homogenizer, a high-pressure collision type crusher, a ball mill, a bead mill and the like can be used. Alternatively, as the defibration processing device, use a wet crushing device such as a disc type refiner, a conical refiner, a twin-screw kneader, a vibration mill, a homomixer under high-speed rotation, an ultrasonic disperser, or a beater. You can also. The defibration processing apparatus is not limited to the above. Preferred defibration treatment methods include a high-speed defibrator, a high-pressure homogenizer, and an ultra-high-pressure homogenizer, which are less affected by crushed media and less likely to cause contamination.

At the time of the defibration treatment, it is preferable to dilute the fiber raw material with water or an organic solvent alone or in combination to form a slurry, but the fiber raw material is not particularly limited. As the dispersion medium, a polar organic solvent can be used in addition to water. Preferred polar organic solvents include, but are not limited to, alcohols, ketones, ethers, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc) and the like. Examples of alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, t-butyl alcohol and the like. Examples of the ketones include acetone, methyl ethyl ketone (MEK) and the like. Examples of ethers include diethyl ether and tetrahydrofuran (THF). The dispersion medium may be one kind or two or more kinds. Further, the dispersion medium may contain a solid content other than the fiber raw material, for example, urea having a hydrogen bond property.

The absorbent article 100 contains, for example, one or more metal components selected from the group consisting of Ag, Au, Pt, Pd, Cu and Zn, which are supported by the phosphorylated cellulose fibers contained in the absorber 10. be able to. In the present embodiment, the metal component can be supported on the phosphorylated cellulose fiber by, for example, contacting the phosphorylated cellulose fiber with an aqueous solution of the metal compound. The metal component is supported by being bonded to, for example, a phosphoric acid group contained in a phosphorylated cellulose fiber or a substituent derived from a phosphoric acid group by a coordination bond, a hydrogen bond, or an ionic bond. The state of coupling can be analyzed by, for example, X-ray photoelectron spectroscopy or infrared spectroscopy.

In the present embodiment, the metal component can be supported as follows, for example.
First, the phosphorylated cellulose fiber is brought into contact with an aqueous solution containing the compound of the metal component, and the phosphoric acid group of the phosphorylated cellulose fiber or a substituent derived from the phosphoric acid group is bonded to the metal compound. As a result, metal components such as metal ions are supported on the phosphorylated cellulose fibers. Here, for example, an aqueous solution of a metal compound may be added to a dispersion of phosphorylated cellulose fibers, or an aqueous solution of a metal compound may be dropped and impregnated into a fiber layer containing phosphorylated cellulose fibers. As the aqueous solution of the metal compound, for example, an aqueous solution of a metal salt or an organometallic compound can be used. Metal salts include, for example, metal component complexes (complex ions), halides, nitrates, sulfates, and acetates. The metal salt is preferably water-soluble.
The concentration of the aqueous metal compound solution is not particularly limited, but is preferably 10 parts by mass or more and 80 parts by mass or less, and more preferably 30 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the phosphorylated cellulose fiber. The contact time of the metal compound may be adjusted as appropriate. The temperature at the time of contact is not particularly limited, but is preferably 20 ° C. or higher and 40 ° C. or lower. Further, the pH of the liquid at the time of contact is preferably 2.5 or more and pH 13 or less.

Then, the metal compound bonded to the phosphorylated cellulose fiber obtained above can be reduced. As a result, metal components such as metal particles obtained by reduction are supported on the surface of the phosphorylated cellulose fiber. The reduction reaction may be carried out by a known method, but it is preferable to carry out the reduction reaction while reducing the metal compound so as not to cleave the bond between the metal compound and the phosphate group. In the present embodiment, the reduction treatment can be carried out by, for example, a gas phase reduction method using hydrogen or a liquid phase reduction method using a reducing agent such as an aqueous solution of sodium borohydride. Conditions such as time and temperature in the gas phase reduction are appropriately adjusted, and for example, the reaction can be carried out at 50 ° C. or higher and 60 ° C. or lower for about 1 hour or more and 3 hours or less. The reaction temperature in the liquid phase reduction is, for example, preferably 4 ° C. or higher and 40 ° C. or lower, and more preferably room temperature. In this embodiment, it is not necessary to carry out the treatment for reducing the metal compound.

In addition, the absorbent article 100 can further contain inorganic compound particles having functions such as antibacterial and deodorant. This makes it possible to further enhance the deodorant function of the absorbent article 100 and impart an antibacterial function. Examples of the inorganic compound particles include silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), iron oxide (Fe ₂ O), yttrium oxide (Y ₂ O ₃ ), indium oxide (In O), and zinc oxide (In O). ZnO), magnesium oxide (MgO), titanium dioxide (TiO ₂ ), cerium dioxide (CeO ₂ ), trimanganese tetroxide (Mn ₃ O ₄ ), niobium pentoxide (Nb ₂ O ₅ ), silicon dioxide (SiC), One or more selected from boron carbide (B ₄ C), aluminum nitride (AlN), titanium boride (TiB ₂ ), zeolite, hydroxyapatite, and nanoplatinum-silica particles with metal nanoparticles bonded to silica. Can be included. Examples of the metal nanoparticles include gold, silver, copper, aluminum, nickel, cobalt, iron, platinum, ruthenium, zinc, panadium, rhodium, palladium, osmium, and iridium.

In the present embodiment, for example, one or both of the absorption layer 12 and the core wrap sheet 14 can contain the inorganic compound particles. In this case, at least a part of the inorganic compound particles can exist in a state of being attached to the cellulose fibers contained in, for example, the absorption layer 12 or the core wrap sheet 14. As for the absorption layer 12 or the core wrap sheet 14 containing the inorganic compound particles, for example, the inorganic compound particles themselves or a commercially available antibacterial agent or deodorant containing the same is added to the absorption layer 12 or the core wrap sheet 14. Can be obtained by

The constitution of the absorbent article according to the present invention is not limited to that described in the present embodiment. For example, in the absorbent article, a liquid-permeable surface sheet may cover both sides of the absorber 10 so that urine or the like can be absorbed from both the front surface and the back surface of the absorbent article. Further, the configuration of the absorber 10 is not limited to that described above.

Hereinafter, the present invention will be specifically described with reference to examples. The present invention is not limited to these examples.

(Example 1)
[Phosphorylation]
As coniferous kraft pulp, pulp made by Oji Paper (solid content 93%, paper density 208 g / m) ²A Canadian standard drainage level (CSF) of 700 ml) was used, which was separated into sheets and measured according to JIS P8121. 100 parts by mass of the above coniferous kraft pulp is impregnated with a mixed aqueous solution of ammonium dihydrogen phosphate and urea, and squeezed to 49 parts by mass of ammonium dihydrogen phosphate and 130 parts by mass of urea, and impregnated with a chemical solution. Obtained pulp. The obtained chemical-impregnated pulp was dried in a dryer at 105 ° C. to evaporate the water content and pre-dried. Then, it was heated for 10 minutes with a blower dryer set at 140 ° C., and a phosphoric acid group was introduced into the cellulose in the pulp to obtain phosphorylated pulp. As the absolute dry mass of the obtained phosphorylated pulp, 10000 parts by mass of ion-exchanged water was poured with respect to 100 parts by mass, and the mixture was stirred and uniformly dispersed, and then filtered and dehydrated to obtain a dehydrated sheet twice. Repeatedly, phosphoric acid-modified cellulose fibers were obtained. The obtained phosphoric acid-modified cellulose fiber had an introduction amount of a phosphoric acid group of 0.98 mmol / g.

The amount of the phosphate group introduced was measured by diluting cellulose with ion-exchanged water so that the content was 0.2% by mass, treating with an ion-exchange resin, and titrating with an alkali. In the treatment with an ion exchange resin, a strongly acidic ion exchange resin (Amberjet 1024: Organo Corporation, which has been conditioned) with a volume of 1/10 is added to a slurry containing 0.2 mass% cellulose and shaken for 1 hour. rice field. Then, it was poured onto a mesh having a mesh size of 90 μm to separate the resin and the slurry. In the titration using alkali, the change in the value of electrical conductivity exhibited by the slurry was measured while adding a 0.1 N sodium hydroxide aqueous solution to the fibrous cellulose-containing slurry after ion exchange. That is, the amount of alkali (mmol) required in the first region of the curve shown in FIG. 2 was divided by the solid content (g) in the slurry to be titrated to obtain the amount of substituent introduced (mmol / g).

[Alkaline treatment and cleaning]
Next, 5000 ml of ion-exchanged water was added to 100 g of cellulose into which a phosphoric acid group was introduced, and the mixture was stirred and washed, and then dehydrated. The dehydrated pulp was diluted with 5000 ml of ion-exchanged water, and a 1N aqueous sodium hydroxide solution was added little by little until the pH became 12 or more and 13 or less with stirring to obtain a pulp dispersion. Then, this pulp dispersion was dehydrated, and 5000 ml of ion-exchanged water was added for washing. This dehydration washing was repeated once more.

[Machine processing]
Ion-exchanged water was added to the pulp obtained after washing and dehydration to prepare a pulp dispersion having a solid content concentration of 1.0% by mass. This pulp dispersion was treated with a high-pressure homogenizer (Panda Plus 2000, manufactured by NiroSoavi) to obtain a cellulose dispersion. In the treatment using the high-pressure homogenizer, the homogenizing chamber was passed 5 times at an operating pressure of 1200 bar. Further, this cellulose dispersion was treated with a wet atomizer (Ultimizer manufactured by Sugino Machine Limited) to obtain a fine fibrous cellulose dispersion. In the treatment using the wet atomizer, the treatment chamber was passed 5 times at a pressure of 245 MPa. The average fiber width of the fine fibrous cellulose contained in the fine fibrous cellulose dispersion was 4 nm.

[Ion exchange treatment and metal ion support]
The obtained fine fibrous cellulose was diluted with ion-exchanged water so that the content was 0.2% by mass, and then treated with an ion-exchange resin. In the treatment with an ion exchange resin, a strongly acidic ion exchange resin (Amberjet 1024: Organo Corporation, conditioned) with a volume of 1/10 is added to a slurry containing 0.2 mass% fine fibrous cellulose and shaken for 1 hour. Processing was performed. Then, it was poured onto a mesh having a mesh size of 90 μm to separate the resin and the slurry. Next, silver nitrate (I) was added so as to be twice the amount of the phosphoric acid group introduced, and the mixture was stirred for 30 minutes to obtain a fine fibrous cellulose-containing slurry carrying silver ions as a metal component.

[Washing and slurry preparation]
Next, the obtained slurry was filtered and washed to remove nitrate ions remaining in the system. Specifically, a PTFE membrane filter having a pore size of 1.0 μm is placed on a glass filter, the filter is moistened with IPA, the slurry is poured, and the pressure is reduced at a decompression degree of −0.09 MPa (absolute vacuum degree of 10 kPa). Filtration was performed. After confirming that a deposit of fine fibrous cellulose carrying silver ions was formed on the PTFE membrane filter, the same amount of water as the original slurry was poured and the process of vacuum filtration was repeated twice.
The obtained fine fibrous cellulose deposit carrying silver ions was diluted with ion-exchanged water so that the content was 1.0% by mass, and a washed fine fibrous cellulose-containing slurry carrying silver ions was obtained. Obtained.

[Creation of absorption layer]
The fluff pulp (dry weight 80 parts by mass) obtained by defibrating the dry pulp sheet (NBKP) and the highly absorbent resin (SAP) (dry weight 20 parts by mass) were mixed. Next, the washed fine fibrous cellulose-containing slurry carrying silver ions was sprayed evenly with a spray so that the dry weight was 30 parts by mass, and the mixture was allowed to stand for natural drying. The basis weight of the absorption layer at this time was 200 g / m ^2, and a core wrap sheet (NBKP) having a basis weight of 20 g / m ^{2 was laminated on this absorption layer to obtain an absorber.}

(Example 2)
An absorber was obtained by the same procedure as in Example 1 except that the absorption layer was prepared as follows.

[Creation of absorption layer]
The fluff pulp (dry weight 80 parts by mass) obtained by defibrating the dry pulp sheet (NBKP) and the highly absorbent resin (SAP) (dry weight 20 parts by mass) were mixed. The basis weight of the absorption layer at this time was set to 200 g / m ² . Next, the washed fine fibrous cellulose-containing slurry in which silver ions were carried on a core wrap sheet (NBKP) having a basis weight of 20 g / m ^{2 was sprayed evenly so as to have a dry weight of 30 parts by weight.} After allowing to stand and air-drying, the obtained core wrap sheet was laminated on an absorbent layer to obtain an absorbent body.

(Example 3)
The procedure was the same as in Example 1 except that a fine fibrous cellulose-containing slurry carrying copper ions as a metal component was prepared by using copper (II) nitrate instead of silver nitrate (I) to support the metal component. Obtained an absorber.

(Example 4)
An absorber was obtained by the same procedure as in Example 1 except that the steps of ion exchange treatment and metal ion support and the steps of washing and slurry preparation were not performed.

(Example 5)
Phosphorylated cellulose fibers were obtained by performing a phosphorylation step and an alkali treatment and washing step in the same manner as in Example 1. Next, 30 parts by mass of the obtained phosphorylated cellulose fiber, fluff pulp (80 parts by mass by mass) obtained by defibrating a dry pulp sheet (NBKP), and a highly absorbent resin (SAP) (dry weight 20). By mass) was mixed. The basis weight of the absorption layer at this time was set to 200 g / m ² . A core wrap sheet (NBKP) having a basis weight of 20 g / m ^{2 was laminated on this absorbent layer to obtain an absorber.}

(Example 6)
A phosphorylated cellulose fiber carrying silver ion as a metal component was obtained by the same procedure as in Example 1 except that the mechanical treatment step was not performed. Next, an absorber was obtained by the same procedure as in Example 5 except that the phosphorylated cellulose fiber carrying the silver ion was used as the phosphorylated cellulose fiber.

(Example 7)
An absorber was obtained by the same procedure as in Example 6 except that the absorption layer was prepared as follows.
[Creation of absorption layer]
The fluff pulp (dry weight 80 parts by mass) obtained by defibrating the dry pulp sheet (NBKP) and the highly absorbent resin (SAP) (dry weight 20 parts by mass) were mixed. The basis weight of the absorption layer at this time was set to 200 g / m ² . Next, 30 parts by mass of a phosphorylated cellulose fiber-containing slurry carrying silver ions and 70 parts by mass of NBKP were mixed to prepare a core wrap sheet having ^{a basis weight of 20 g / m 2.} An absorber obtained by laminating the obtained core wrap sheet on an absorption layer was obtained.

(Comparative Example 1)
The procedure was the same as in Example 1 except that the phosphorylation step and the alkali treatment and washing steps were not performed.

(Comparative Example 2)
[Oxidation]
10000 parts by mass of undried coniferous bleached kraft pulp equivalent to 100 parts by mass of dry mass, 1.6 parts by mass of 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) and 10 parts by mass of sodium bromide It was dispersed in parts by mass. Then, a 13 mass% sodium hypochlorite aqueous solution was added to 1.0 g of pulp so that the amount of sodium hypochlorite was 3.5 mmol, and the reaction was started. During the reaction, a 1.0 M aqueous sodium hydroxide solution was added dropwise to keep the pH at 10 to 11, and when no change was observed in the pH, the reaction was considered to be completed, and a carboxyl group was introduced into the pulp. After dehydrating this pulp slurry to obtain a dehydrated sheet, 5000 parts by mass of ion-exchanged water is poured, stirred and uniformly dispersed, and then filtered and dehydrated to obtain a dehydrated sheet. The process is repeated twice to obtain carboxyl. A group-modified cellulose fiber was obtained. The obtained carboxyl group-modified cellulose fiber had a carboxyl group introduction amount of 1.01 mmol / g. Using the carboxyl group-modified cellulose fiber thus obtained, the steps after the mechanical treatment were carried out in the same manner as in Example 1 to obtain a sheet.

(Evaluation of water absorption)
For each Example and Comparative Example 1, the water absorption was measured by the Bilek method measured according to JIS L 1907. As a result, all of the examples showed excellent water absorption as compared with Comparative Examples 1 and 2. Examples 1 to 4 showed even better water absorption as compared with Examples 5 to 7.

(Deodorant evaluation)
A 1.2 mL syringe is used to insert saturated gas of an aqueous ammonia solution (2 mL of ammonia water: 2 mL of water) into a gas bag with a cock containing four 5 cm x 5 cm absorber test pieces, and then 1 air is blown by an air pump. .5 L was filled. The saturated gas was collected from the gas phase of a closed container containing an aqueous ammonia solution. The concentration of ammonia gas in the gas bag after filling with saturated gas and air was 80 to 90 ppm. Next, the aspirator and the rubber tube were connected to the detector tube, and the rubber tube was connected to the gas bag. Then, the ammonia gas concentration in the gas bag was measured 15 minutes after the air was filled.
⊚: Very good residual concentration is 1/3 or less of the initial level ○: Normal Residual concentration is 1/2 to 3/1 of the initial level
X: Poor residual concentration was 1/2 or more of the initial level. As a result, ⊚ was obtained in Examples 1 to 3 and 6 and 7, and ◯ was obtained in Examples 4 and 5 and Comparative Examples 1 and 2. As described above, it can be seen that an excellent deodorizing effect is obtained in the examples in which the metal component is supported.

(Manufacturing of absorbent articles)
An absorbent article was obtained by arranging any of the absorbers obtained in Examples 1 to 7 between the top sheet and the back sheet and integrally adhering them with a hot melt adhesive. Here, a polypropylene spunbonded non-woven fabric having a basis weight of 25 g / m ^{2 was used as a top sheet, and a polyethylene film having a basis weight of 30 g / m 2} was used as a back sheet. When the absorbent body of any of the examples was used, an absorbent article having an excellent balance between water absorption and deodorant property was realized.

10 Absorber 12 Absorbent layer 14 Core wrap sheet 20 Top sheet 30 Back sheet 50 Side sheet 60 Cover sheet 100 Absorbent article

Claims (4)

A back sheet, a top sheet, and an absorber arranged between the back sheet and the top sheet are provided.
The absorber is composed of an absorbent body containing a highly water-absorbent resin and a coating member that covers the water-absorbent body, and the absorbent body or the coating member has a fiber width of 1000 nm or less. An absorbent article comprising fine phosphorylated cellulose fibers having an acid group or a substituent derived from a phosphoric acid group. The absorbent article according to claim 1, which comprises one or more metal components selected from the group consisting of Ag, Au, Pt, Pd, Cu and Zn, which are supported on the phosphorylated cellulose fibers. The absorbent article according to claim 1 or 2, wherein the absorbent body is composed of an absorbent main body containing the phosphorylated cellulose fiber and a water-absorbent resin, and a coating member covering the absorbent main body. The absorbent body according to claim 1 or 2, wherein the absorbent body is composed of an absorbent main body containing a water-absorbent resin and a coating member covering the absorbent main body and containing the phosphorylated cellulose fiber. Goods.

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