WO2017099078A1

WO2017099078A1 - Absorbent article

Info

Publication number: WO2017099078A1
Application number: PCT/JP2016/086231
Authority: WO
Inventors: 豪盤指; 速雄伏見; 久美田平; 浩己山本
Original assignee: 王子ホールディングス株式会社
Priority date: 2015-12-08
Filing date: 2016-12-06
Publication date: 2017-06-15
Also published as: JPWO2017099078A1; JP6930424B2

Abstract

The problem of the present invention is to realize an absorbent article having an excellent balance of water absorptivity and deodorizing property. The absorbent article (100) according to the present invention is equipped with a back sheet (30), a top sheet (20), and an absorbent body (10) disposed between the back sheet (30) and the top sheet (20); the absorbent body (10) includes phosphorylated cellulose fibers having phosphate groups or substituents derived from phosphate groups.

Description

Absorbent articles

The present invention relates to an absorbent article.

In recent years, various studies on absorbent articles such as disposable diapers are underway. 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 that covers the absorbent core, and a liquid-permeable outer layer sheet that covers the core wrap sheet. Specifically, it is characterized by using a core wrap sheet made of thin paper containing metal-carrying cellulose fibers in which specific metal particles are supported on oxidized cellulose fibers having a carboxyl group or a carboxylate group on the surface. It is. Patent Document 2 relates to an absorbent article including a top sheet, a back sheet, and an absorbent body interposed between the top sheet and the back sheet. Specifically, an absorbent body including metal-supporting cellulose fibers formed by supporting specific metal particles on oxidized cellulose fibers having a carboxyl group or a carboxylate group on the surface is used.

Japanese Patent Laid-Open No. 2015-43940 Japanese Patent Laying-Open No. 2015-84870

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

According to the present invention, the following inventions are provided.
[1] A back sheet, a top sheet, and an absorber disposed between the back sheet and the top sheet,
The said absorber is an absorbent article containing the phosphorylated cellulose fiber which has a phosphate group or a substituent derived from a phosphate group.
[2] The absorbent article according to [1], wherein the phosphorylated cellulose fiber includes fine fibers having a fiber width of 1000 nm or less.
[3] The material according to [1] or [2], comprising 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 articles.
[4] The absorber is composed of an absorbent main body containing the phosphorylated cellulose fiber and a water absorbent resin, and a covering member that covers the absorbent main body. The absorbent article as described in 1.
[5] The absorbent body includes an absorbent main body containing a water-absorbing resin and a covering member that covers the absorbent main body and includes the phosphorylated cellulose fibers [1] to [3]. The absorbent article as described in any one of.

According to the present invention, an absorbent article having an excellent balance between water absorption and deodorant can be realized.

It is a cross-sectional schematic diagram which shows the absorbent article which concerns on this embodiment. It is a graph which shows the relationship between the amount of NaOH dripping with respect to a fiber raw material, and electrical conductivity.

Hereinafter, the present invention will be described in more detail. Note that the descriptions of materials, methods, and numerical ranges described in this specification are not intended to be limited to the materials, methods, and numerical ranges, and other materials, methods, and numerical ranges are not intended. It does not exclude the use of such as.

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 absorbent body 10 disposed between the back sheet 30 and the top sheet 20. The absorber 10 includes phosphorylated cellulose fibers having a phosphate group or a substituent derived from a phosphate group.

The inventor of the present invention includes a phosphoric acid cellulose fiber having a phosphate group or a substituent derived from a phosphoric acid group in the absorbent body 10 constituting the absorbent article 100, whereby the water absorption and deodorizing properties of the absorbent body 10 are obtained. It has been found that the balance can be improved. Thus, according to the present embodiment, it is possible to realize an absorbent article having an excellent balance between water absorption and deodorant properties.

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 absorbent body 10 interposed between the top sheet 20 and the back sheet 30. It is out. Moreover, the absorbent article 100 has a pair of side seats 50 on the left and right sides of the absorbent body 10, for example. Further, the absorbent article 100 includes a cover sheet 60 that covers the back sheet 30 from the skin non-contact surface side, for example. The absorbent article 100 according to the present embodiment is applied to an article worn by a wearer for the purpose of absorbing and holding body fluid, such as a disposable diaper, a sanitary napkin, a urine absorption pad, or an absorption pad. be able to.

The top sheet 20 is a sheet-like member that is in direct contact with the skin of the wearer's crotch and allows liquid such as urine to pass through the absorbent body 10. For this reason, the top sheet 20 is made of a liquid-permeable material having high flexibility. The top sheet 20 is disposed so as to cover the absorbent body 10 from the skin contact surface side. The top sheet 20 and the absorbent body 10 may be fixed by 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 nonwoven fabric, or a porous film. Moreover, as the top sheet 20, it is good also as using the thing which hydrophilized the fiber of thermoplastic resins like polypropylene, polyethylene, polyester, or nylon, and made it the nonwoven fabric. Moreover, as a nonwoven fabric which comprises the top sheet 20, what processed natural fibers, such as cotton, by processing methods, such as a spun bond method, a spun lace method, a thermal bond method, a melt blown method, or a needle punch method, is mentioned. Of the nonwoven fabric processing methods, nonwoven fabrics formed by the spunbond method are excellent in flexibility and drape. The thermal bond method has an advantage that a bulky and soft nonwoven 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 absorbed by the absorber 10 from leaking out. For this reason, the backsheet 30 is comprised with a liquid-impermeable material. The back sheet 30 is disposed so as to cover the absorbent body 10 from the non-skin contact surface side. The back sheet 30 and the absorbent body 10 may be fixed by a known adhesive such as a hot melt adhesive.

An example of the liquid impervious material constituting the back sheet 30 is an olefin resin sheet such as polyethylene or polypropylene, and at least a sheet material having liquid shielding properties is used. Further, as the back sheet 30, a microporous air-permeable resin sheet obtained by kneading an inorganic filler in an olefin resin such as polyethylene or polypropylene and molding the sheet and then stretching the sheet may be used. it can. In addition, as the backsheet 30, a laminated nonwoven fabric sheet in which a nonwoven fabric is laminated on a polyethylene sheet or the like, or a nonwoven fabric sheet having substantial liquid impermeability through a waterproof film can be used. In particular, a microporous polyethylene film in which a plurality of fine pores of 0.1 μm or more and 4 μm or less are formed is preferably used as the back sheet 30.

The absorber 10 is a member for absorbing liquid such as urine and holding the absorbed liquid. The absorber 10 is disposed between the top sheet 20 and the back sheet 30 and has a function of absorbing liquid that has passed through the top sheet 20. Moreover, the absorber 10 is comprised by encapsulating the absorption layer 12 with the core wrap sheet | seat 14, for example.

The shape of the absorber 10 is preferably an hourglass shape. The hourglass shape means that the absorbent body 10 has extended portions extending toward the outside in the width direction on the front body side and the back body side. The hourglass-shaped absorber 10 is formed with extended portions at the four corners on the front body side and the back body side, so that it is curved or refracted toward the inside of the absorber 10 in the crotch part at the center in the longitudinal direction. A constricted portion is formed. By making the absorbent body 10 into an hourglass shape as described above, the longitudinal center portion of the absorbent body 10 is constricted in accordance with the shape of the legs of the wearer, so that the disposable diaper has a good wearing feeling It 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 includes, for example, hydrophilic fibers and a superabsorbent resin (SAP). The hydrophilic fiber includes, for example, one or more of wood fluff pulp, synthetic fiber, and polymer fiber. The core wrap sheet 14 is made of, for example, a nonwoven fabric excellent in air permeability and liquid permeability. The kind of the nonwoven fabric is not particularly limited, and for example, a known material such as a spunbond nonwoven fabric, a needle punched nonwoven fabric, a spunlace nonwoven fabric, or an air-through nonwoven fabric can be appropriately employed. The core wrap sheet 14 may be a known tissue paper.

As described above, the absorbent body 10 includes phosphorylated cellulose fibers having a phosphate group or a substituent derived from a phosphate group (hereinafter sometimes simply referred to as a phosphate group). Thereby, it becomes possible to improve the balance of water absorption and deodorant property in the absorbent article 100. In the present embodiment, the content of the phosphorylated cellulose fiber in the absorbent body 10 is preferably 10 parts by weight or more and 70 parts by weight or less, for example, with the total of the hydrophilic fiber and the superabsorbent resin being 100 parts by weight, More preferably, it is 20 parts by weight or more and 50 parts by weight or less. Thereby, the balance of water absorption and deodorant property can be improved more effectively.

As an example of this embodiment, the absorbent body 10 includes an absorbent main body (absorbing layer 12) containing phosphorylated cellulose fibers and a water absorbent resin, and a covering member (core wrap sheet 14) that covers the absorbent main body. The case where it is comprised is mentioned. In this case, the absorbent body 10 is composed of an absorbent layer 12 including, for example, wood fluff pulp formed from phosphorylated cellulose fibers as hydrophilic fibers. Moreover, as for the absorber 10, the phosphorylated fine cellulose fiber may be added to the absorption layer 12 containing a hydrophilic fiber and a highly water-absorbent resin, for example.
The content of the phosphorylated cellulose fiber contained in the absorbent main body (absorbing layer 12) is preferably large from the viewpoint of improving water absorption and deodorizing properties, but an upper limit value may be provided in some cases. Absorbency without impairing operability at the time of manufacture of an absorber body by making content of phosphorylated cellulose fiber contained in an absorptive body (absorption layer 12) less than 5 mass% of the whole absorptive body, for example. It becomes possible to improve the balance between water absorption and deodorant property of the article 100.

As another example of the present embodiment, the absorbent body 10 includes an absorbent main body (absorbing layer 12) containing a water absorbent resin, and a covering member (core wrap sheet) that covers the absorbent main body and includes phosphorylated cellulose fibers. And 14). In this case, the covering member may be formed of a non-woven fabric obtained by paper-making phosphorylated cellulose fibers, or phosphorylated fine cellulose fibers may be added to the non-woven fabric constituting the covering member.
Impairing the operability during the production of the core wrap sheet by making the content of the phosphorylated cellulose fiber contained in the covering member (core wrap sheet 14) covering the absorber less than 5% by mass of the entire covering member, for example. Therefore, it is possible to improve the balance between water absorption and deodorant of the absorbent article 100.

The phosphoric acid group possessed by the phosphorylated cellulose fiber is a divalent functional group that corresponds to the phosphoric acid obtained by removing the hydroxyl group. Specifically, it is a group represented by —PO ₃ H ₂ . The substituent derived from the phosphate group includes substituents such as a group obtained by polycondensation of a phosphate group, a salt of a phosphate group, and a phosphate ester group. In the present specification, the phosphate group or the substituent derived from the phosphate group may be a nonionic substituent or an ionic substituent represented by the following formula (1). .

In formula (1), a, b, m and n each independently represent an integer (where a = b × m); α ⁿ (an integer from 1 to n) and α ′ are each independently R or OR is represented. R represents a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched hydrocarbon group. , An aromatic group, or a derivative group thereof; β is a monovalent or higher cation composed of an organic substance or an inorganic substance.

In the present embodiment, the phosphoric acid group of the phosphorylated cellulose fiber or the content of the substituent derived from the phosphoric acid group is, for example, 0.1 mmol / g or more. The content of the substituent derived from the phosphate group or the phosphate 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 a substituent derived from the phosphoric acid group can be, for example, 3.5 mmol / g or less. Thereby, it becomes possible to improve the balance of water absorption and deodorant property in an absorbent article more effectively.

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

Conductivity titration gives the curve shown in Fig. 2 when alkali is added. Initially, the electrical conductivity rapidly decreases (hereinafter referred to as “first region”). Thereafter, the conductivity starts to increase slightly (hereinafter referred to as “second region”). Thereafter, the conductivity increment increases (hereinafter referred to as “third region”). The boundary point between the second region and the third region is defined as the point at which the twice differential value of conductivity, that is, the amount of change in conductivity increment (slope) is maximized. That is, three areas appear. Among these, the amount of alkali required in the first region is equal to the amount of strongly acidic groups in the slurry used for titration, and the amount of alkali required in the second region is the amount of weakly acidic groups in the slurry used for titration. Will be equal. When the phosphoric acid group undergoes condensation, apparently weakly acidic groups are lost, and the amount of alkali required in the second region is reduced compared to the amount of alkali required in the first region. On the other hand, the amount of strongly acidic groups coincides with the amount of phosphorus atoms regardless of the presence or absence of condensation, so that the amount of phosphate groups introduced (or the amount of phosphate groups) or the amount of substituent introduced (or the amount of substituents) is simply When said, it represents the amount of strongly acidic group.

In the present embodiment, introduction of phosphate groups into cellulose fibers can be performed by reacting a fiber raw material with a compound having a phosphate group and / or a salt thereof (hereinafter referred to as “compound A”). . This reaction may be performed in the presence of urea and / or a derivative thereof (hereinafter referred to as “compound B”). Thereby, a phosphoric acid group can be efficiently introduced into the hydroxyl group of the cellulose fiber.

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

Although it does not specifically limit as a fiber raw material, It is preferable to use a pulp from the point of being easy to acquire and cheap. Examples of the pulp include wood pulp, non-wood pulp, and deinked pulp. Examples of wood pulp include hardwood kraft pulp (LBKP), softwood kraft pulp (NBKP), sulfite pulp (SP), dissolved pulp (DP), soda pulp (AP), unbleached kraft pulp (UKP), oxygen bleached craft Chemical pulps such as pulp (OKP) are listed. Moreover, semi-chemical pulps such as semi-chemical pulp (SCP) and chemi-ground wood pulp (CGP), mechanical pulps such as ground wood pulp (GP), thermomechanical pulp (TMP, BCTMP) and the like can be mentioned, but are not particularly limited. Non-wood pulp includes cotton pulp such as cotton linter and cotton lint, non-wood pulp such as hemp, straw and bagasse, cellulose isolated from sea squirts and seaweed, chitin, chitosan, etc., but is not particularly limited. . The deinking pulp includes deinking pulp made from waste paper, but is not particularly limited. The pulp of this embodiment may be used alone or in combination of two or more. 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 refinement (defibration) is high, and the degradation of cellulose in the pulp is small, and the fineness of long fibers with a large axial ratio is high. It is preferable at the point from which fibrous cellulose is obtained. Of these, kraft pulp and sulfite pulp are most preferably selected.

An example of a method for causing compound A to act on the fiber raw material in the presence of compound B is a method of mixing powder or an aqueous solution of compound A and compound B with a dry or wet fiber raw material. Another example is a method in which powders and aqueous solutions of Compound A and Compound B are added to the fiber raw material slurry. Among these, since the uniformity of the reaction is high, a method of adding an aqueous solution of Compound A and Compound B to a dry fiber material, or a powder or an aqueous solution of Compound A and Compound B to a wet fiber material The method is preferred. Moreover, the compound A and the compound B may be added simultaneously, or may be added separately. Moreover, you may add the compound A and the compound B first used for reaction as aqueous solution, and remove an excess chemical | medical solution by pressing. The form of the fiber raw material is preferably cotton or thin sheet, but is not particularly limited.

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

Among these, phosphoric acid, sodium phosphate, from the viewpoint of high phosphate group introduction efficiency, easy defibration efficiency in the defibration process described later, low cost, and easy industrial application. A salt, or a potassium salt of phosphoric acid or an ammonium salt of phosphoric acid is preferable. Sodium dihydrogen phosphate or disodium hydrogen phosphate is more preferable.

Also, the compound A is preferably used as an aqueous solution because the uniformity of the reaction is increased and the efficiency of introducing a phosphate 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 introduction of phosphate groups is increased, and more preferably pH 3 or more and pH 7 or less from the viewpoint of suppressing the hydrolysis of pulp fibers. The pH of the aqueous solution of Compound A may be adjusted by, for example, using a phosphoric acid group-containing compound that exhibits acidity and an alkalinity, and changing the amount ratio thereof. You may adjust pH of the aqueous solution of the compound A by adding an inorganic alkali or an organic alkali to the thing which shows acidity among the compounds which have a phosphoric acid group.

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 to 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. More preferably, they are more than 50 mass% and most preferably 2 mass% or more and 30 mass% or less. If the addition amount of the phosphorus atom with respect to a fiber raw material exists in the said range, the yield of a phosphorylated cellulose fiber can be improved more. Manufacturing cost can be suppressed because the addition amount of the phosphorus atom with respect to a fiber raw material shall be 100 mass% or less. On the other hand, a yield can be raised by making the addition amount of the phosphorus atom with respect to a fiber raw material more than the said lower limit.

Compound B used in this embodiment includes urea, thiourea, biuret, phenylurea, benzylurea, dimethylurea, diethylurea, tetramethylurea, benzoleinurea, hydantoin and the like. Among these, urea is preferable because it is easy to handle at low cost and easily forms a hydrogen bond with a fiber raw material having a hydroxyl group.

Compound B is preferably used as an aqueous solution like Compound A. Moreover, since the uniformity of reaction increases, it is preferable to use the 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 is known to work as a good reaction catalyst.

In the phosphate group introduction step, it is preferable to perform heat treatment. The heat treatment temperature is preferably 50 ° C. or higher and 250 ° C. or lower, for example, and more preferably 100 ° C. or higher and 200 ° C. or lower. Moreover, you may use a vacuum dryer, an infrared heating apparatus, and a microwave heating apparatus for a heating.

During the heat treatment, while water is contained in the fiber raw material slurry to which compound A is added, if the time for allowing the fiber raw material to stand still becomes long, the compound A dissolved with water molecules moves to the fiber raw material surface with drying. To do. Therefore, the concentration of the compound A in the fiber raw material may be uneven, and the introduction of phosphate groups on the fiber surface may not proceed uniformly. In order to suppress the occurrence of uneven density of the compound A in the fiber raw material due to drying, a very thin sheet-like fiber raw material is used, or heat drying or decompression while kneading or / and stirring the fiber raw material and compound A with a kneader or the like. What is necessary is just to take the method of drying.

The heating device used for the heat treatment is preferably a device that can always discharge the moisture retained by the slurry and the moisture generated by the addition reaction of the fibers such as phosphate groups to the hydroxyl group of the fiber, such as a blower oven. Etc. are preferred. If water in the system is always discharged, the hydrolysis reaction of the phosphate ester bond, which is the reverse reaction of the esterification, can be suppressed, and the acid hydrolysis of the sugar chain in the fiber can also be suppressed. A fine fiber having a high axial ratio can be obtained. Although the time for the heat treatment is also affected by the heating temperature, it is preferably 1 minute or more and 300 minutes or less, preferably 1 minute or more and 200 minutes or less after the moisture is substantially removed from the fiber raw material slurry. Although it is preferable, it is not particularly limited.

In this embodiment, an alkali treatment can be performed on the obtained phosphate group-introduced fiber after the phosphorylation treatment step. Although it does not specifically limit as a method of an alkali treatment, For example, the method of immersing a phosphate group introduction | transduction fiber in an alkaline solution is mentioned.
The alkali compound contained in the alkali solution is not particularly limited, but may be an inorganic alkali compound or an organic alkali compound. The solvent in the alkaline solution may be either water or an organic solvent. The solvent is preferably a polar solvent (polar organic solvent such as water or alcohol), and more preferably an aqueous solvent containing at least water.
Of the alkaline solutions, a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution is particularly preferred because of its high versatility.

The temperature of the alkaline solution in the alkali 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. Although the immersion time in the alkaline solution in the alkali treatment step is not particularly limited, it is preferably 5 minutes or longer and 30 minutes or shorter, and more preferably 10 minutes or longer and 20 minutes or shorter. Although the usage-amount of the alkaline solution in an alkali treatment is not specifically limited, It is preferable that it is 100 mass% or more and 100,000 mass% or less with respect to the absolute dry mass of a phosphate group introduction | transduction fiber, and is 1000 mass% or more and 10000 mass% or less. It is more preferable.

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

The phosphorylated cellulose fiber contained in the absorbent body 10 can contain fine fibers having a fiber width of 1000 nm or less, for example. Thereby, the absorptivity in an absorptive article can be improved more effectively. In the present embodiment, it is preferable that the absorbent body 10 includes single-fiber phosphorylated cellulose fibers having a fiber width of 1000 nm or less. The fiber width of the phosphorylated cellulose fiber can be determined by image analysis using, for example, TEM, SEM, or AFM. The lower limit of the fiber width of the fine fibers can be set to 2 nm, for example.
The average fiber width of the fine fibers can be, for example, 2 nm to 1000 nm, and more preferably 2 nm to 100 nm. Thereby, the balance of water absorption and deodorant property can be improved more effectively. In addition, the average fiber width of the fine fibers contained in the absorbent body 10 can be calculated from, for example, 100 arbitrary monofilament-like fine fibers contained in the absorbent body 10 and the average value of the fiber widths. .

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, it is possible to suppress the breakage of the crystal region of the fine fiber. The fiber length of the fine fibers can be determined by image analysis using, for example, TEM, SEM, or AFM.

The phosphorylated cellulose fiber contained in the absorbent body 10 preferably contains 50% by mass or more, more preferably 70% by mass or more, and more preferably 90% by mass of fine fibers having a fiber width of 1000 nm or less with respect to the entire phosphorylated cellulose fiber. % Or more is particularly preferable. On the other hand, the upper limit value of the content of the fine fibers contained in the phosphorylated cellulose fiber is not particularly limited, but can be set to 100% by mass, for example. Thereby, it becomes possible to improve the balance of water absorption and deodorant property of the absorbent article 100 more effectively. On the other hand, the content of fine fibers relative to the entire phosphorylated cellulose fiber may be less than 50% by mass. In the present embodiment, for example, a mode in which the phosphorylated cellulose fiber included in the absorbent body 10 does not include fine fibers having a fiber width of 1000 nm or less can be employed. Here, not containing fine fibers refers to the case where the content of fine fibers with respect to the entire phosphorylated cellulose fiber is 5% by mass or less. Thereby, the handling property improvement of phosphorylated cellulose and cost reduction can be achieved. In addition, 0 mass% may be sufficient as content of the fine fiber with respect to the whole phosphorylated cellulose fiber.

The fine fiber can be obtained, for example, by subjecting a phosphorylated cellulose raw material to a fibrillation treatment. In the defibrating process, the fiber is usually defibrated using a defibrating apparatus to obtain a fine fibrous cellulose-containing slurry, but the processing apparatus and the processing method are not particularly limited. As the defibrating apparatus, a high-speed defibrator, a grinder (stone mill type pulverizer), a high-pressure homogenizer, an ultra-high pressure homogenizer, a high-pressure collision type pulverizer, a ball mill, a bead mill, or the like can be used. Alternatively, as a defibrating apparatus, a device for wet grinding such as a disk type refiner, a conical refiner, a twin-screw kneader, a vibration mill, a homomixer under high-speed rotation, an ultrasonic disperser, or a beater should be used. You can also. The defibrating apparatus is not limited to the above. Preferable defibrating treatment methods include a high-speed defibrator, a high-pressure homogenizer, and an ultra-high pressure homogenizer that are less affected by the grinding media and less worried about contamination.

In the defibrating treatment, it is preferable to dilute the fiber raw material with water and an organic solvent alone or in combination to form a slurry, but there is no particular limitation. As the dispersion medium, in addition to water, a polar organic solvent can be used. Preferable polar organic solvents include alcohols, ketones, ethers, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc), and the like, but are not particularly limited. Examples of alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, and t-butyl alcohol. Examples of ketones include acetone and methyl ethyl ketone (MEK). Examples of ethers include diethyl ether and tetrahydrofuran (THF). The dispersion medium may be one type or two or more types. Further, the dispersion medium may contain a solid content other than the fiber raw material, such as urea having hydrogen bonding property.

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

In the present embodiment, for example, a metal component can be supported as follows.
First, an aqueous solution containing the compound of the above metal component is brought into contact with the phosphorylated cellulose fiber to bond the phosphoric acid group of the phosphorylated cellulose fiber or a substituent derived from the phosphoric acid group and the metal compound. Thereby, metal components, such as a metal ion, will be carry | supported by the phosphorylated cellulose fiber. 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. Examples of the metal salt include metal component complexes (complex ions), halides, nitrates, sulfates, and acetates. The metal salt is preferably water-soluble.
Although the density | concentration of metal compound aqueous solution is not specifically limited, 10 mass parts or more and 80 mass parts or less are preferable with respect to 100 mass parts of phosphorylated cellulose fibers, and 30 mass parts or more and 60 mass parts or less are more preferable. You may adjust suitably the time which a metal compound is made to contact. Although the temperature at the time of making it contact is not specifically limited, 20 to 40 degreeC is preferable. Moreover, the pH of the liquid at the time of contact is preferably 2.5 or more and pH 13 or less.

Next, 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 performed by a known method, but is preferably performed so as not to cleave the bond between the metal compound and the phosphate group while reducing the metal compound. In this embodiment, the reduction treatment can be performed by, for example, a gas phase reduction method using hydrogen and a liquid phase reduction method using a reducing agent such as a sodium borohydride aqueous solution. Conditions such as time and temperature in the gas phase reduction are appropriately adjusted. For example, the reaction can be performed at 50 to 60 ° C. for 1 to 3 hours. The reaction temperature in the liquid phase reduction is preferably 4 ° C. or more and 40 ° C. or less, and more preferably room temperature. In the present embodiment, the treatment for reducing the metal compound may not be performed.

Moreover, the absorbent article 100 can further include inorganic compound particles having functions such as antibacterial and deodorizing, for example. Thereby, it becomes possible to improve the deodorizing function of the absorbent article 100 and to provide 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 (InO), and zinc oxide ( 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 carbide (SiC), One or more selected from boron carbide (B ₄ C), aluminum nitride (AlN), titanium boride (TiB ₂ ), zeolite, hydroxyapatite, and nanoplatinum-silica particles in which metal nanoparticles are bound 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, iridium and the like.

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

In addition, the structure of the absorbent article concerning this invention is not restricted to the thing as described in this embodiment. For example, the absorbent article may have a liquid-permeable surface sheet covering both surfaces of the absorbent body 10 so that urine can be absorbed from both the front and back surfaces of the absorbent article. Further, the configuration of the absorbent body 10 is not limited to the above-described one.

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 softwood kraft pulp, it was used Oji Paper Co., Ltd. Pulp (Canadian Standard Freeness of solids 93% basis weight 208g / m ² and the sheet-like disaggregated is measured according to JIS P8121 (CSF) 700ml). 100 parts by mass of the above-mentioned softwood kraft pulp is impregnated with a mixed aqueous solution of ammonium dihydrogen phosphate and urea, and compressed to 49 parts by mass of ammonium dihydrogen phosphate and 130 parts by mass of urea. Pulp was obtained. The obtained chemical solution-impregnated pulp was dried with a dryer at 105 ° C. to evaporate the moisture and pre-dried. Then, it heated for 10 minutes with the ventilation dryer set to 140 degreeC, the phosphate group was introduce | transduced into the cellulose in a pulp, and the phosphorylated pulp was obtained. The step of pouring 10000 parts by mass of ion-exchanged water with respect to 100 parts by mass as the absolute dry mass of the obtained phosphorylated pulp, stirring and dispersing uniformly, and then performing filtration and dehydration to obtain a dehydrated sheet twice Repeatedly, phosphoric acid-modified cellulose fibers were obtained. The obtained phosphoric acid-modified cellulose fiber had a phosphate group introduction amount of 0.98 mmol / g.

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

[Alkali treatment and cleaning]
Next, 5000 ml of ion-exchanged water was added to 100 g of cellulose into which phosphate groups had been introduced, and after stirring and washing, dehydration was performed. The pulp after dehydration was diluted with 5000 ml of ion-exchanged water, and while stirring, a 1N sodium hydroxide aqueous solution was added little by little until the pH became 12 or more and 13 or less to obtain a pulp dispersion. Thereafter, this pulp dispersion was dehydrated and washed by adding 5000 ml of ion exchange water. This dehydration washing was repeated once more.

[Machine processing]
Ion exchange water was added to the pulp obtained after washing and dewatering to obtain a pulp dispersion having a solid content of 1.0% by mass. This pulp dispersion liquid was processed using a high-pressure homogenizer (Panda Plus 2000, manufactured by NiroSoavi) to obtain a cellulose dispersion liquid. In the treatment using the high-pressure homogenizer, the homogenizing chamber was passed 5 times at an operating pressure of 1200 bar. Furthermore, this cellulose dispersion was processed using a wet atomizer (manufactured by Sugino Machine, Optimizer) to obtain a fine fibrous cellulose dispersion. In the treatment using the wet atomizer, the treatment chamber was passed five 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 loading]
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, 1/10 by volume of a strongly acidic ion exchange resin (Amberjet 1024: Organo Corporation, conditioned) is added to the 0.2 mass% fine fibrous cellulose-containing slurry and shaken for 1 hour. Processed. Thereafter, the mixture was poured onto a mesh having an opening of 90 μm to separate the resin and the slurry. Subsequently, silver nitrate (I) was added so that it might become 2 times the amount of phosphate group introduction | transduction, and it stirred for 30 minutes, and obtained the fine fibrous cellulose containing slurry which carry | supported the silver ion as a metal component.

[Washing and slurry preparation]
Subsequently, 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, and the slurry is poured, and the pressure is reduced at a reduced pressure of −0.09 MPa (absolute vacuum 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 filtration under reduced pressure was repeated twice.
The obtained fine fibrous cellulose deposit carrying silver ions was diluted with ion-exchanged water to a content of 1.0% by mass, and washed fine fibrous cellulose-containing slurry carrying silver ions was obtained. Obtained.

[Create Absorbing Layer]
Fluff pulp (dry weight 80 parts by mass) obtained by defibrating the dry pulp sheet (NBKP) and superabsorbent 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 would be 30 parts by mass, and left to stand for natural drying. The basis weight of the absorbent 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 absorbent layer to obtain an absorbent body.

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

[Create Absorbing Layer]
Fluff pulp (dry weight 80 parts by mass) obtained by defibrating the dry pulp sheet (NBKP) and superabsorbent resin (SAP) (dry weight 20 parts by mass) were mixed. The basis weight of the absorbent layer at this time was 200 g / m ² . Next, the washed fine fibrous cellulose-containing slurry supporting silver ions on a core wrap sheet (NBKP) having a basis weight of 20 g / m ² was sprayed evenly by spray so that the dry weight was 30 parts by weight. After leaving still and air-drying, the obtained core wrap sheet was laminated | stacked on the absorption layer, and the absorber was obtained.

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

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

(Example 5)
In the same manner as in Example 1, phosphorylated cellulose fibers were obtained by performing a phosphorylation step and an alkali treatment and washing step. Next, 30 parts by mass of the phosphorylated cellulose fiber obtained, fluff pulp (dry weight 80 parts by mass) obtained by defibrating the dry pulp sheet (NBKP), and superabsorbent resin (SAP) (dry weight 20) Parts by mass). The basis weight of the absorbent layer at this time was 200 g / m ² . An absorbent body was obtained by laminating a core wrap sheet (NBKP) having a basis weight of 20 g / m ² on this absorbent layer.

(Example 6)
A phosphorylated cellulose fiber carrying silver ions as a metal component was obtained in the same procedure as in Example 1 except that the mechanical treatment step was not performed. Subsequently, the absorber was obtained by the same procedure as Example 5 except having used the phosphorylated cellulose fiber which carry | supported the said silver ion as a phosphorylated cellulose fiber.

(Example 7)
An absorber was obtained by the same procedure as in Example 6 except that the absorbent layer was prepared as follows.
[Create Absorbing Layer]
Fluff pulp (dry weight 80 parts by mass) obtained by defibrating the dry pulp sheet (NBKP) and superabsorbent resin (SAP) (dry weight 20 parts by mass) were mixed. The basis weight of the absorbent layer at this time was 200 g / m ² . Next, 30 parts by mass of 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 absorbent body obtained by laminating the obtained core wrap sheet on the absorbent layer was obtained.

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

(Comparative Example 2)
[Oxidation]
Undried softwood bleached kraft pulp equivalent to 100 parts by weight of dry weight, 1.6 parts by weight of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), 10 parts by weight of sodium bromide, and 10000 water Dispersed in parts by mass. Subsequently, 13 mass% sodium hypochlorite aqueous solution was added so that the quantity of sodium hypochlorite might be 3.5 mmol with respect to 1.0 g of pulp, and reaction was started. During the reaction, a 1.0 M aqueous sodium hydroxide solution was added dropwise to maintain the pH at 10 to 11, and when no change in pH was observed, the reaction was considered to be complete 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 was poured, stirred and dispersed uniformly, filtered and dehydrated, and the process of obtaining a dehydrated sheet was repeated twice. A group-modified cellulose fiber was obtained. The resulting 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 mechanical processing were carried out in the same manner as in Example 1 to obtain a sheet.

(Water absorption evaluation)
About each Example and the comparative example 1, water absorption was measured by the birec method measured according to JISL1907. As a result, all of the examples showed excellent water absorption relative to Comparative Examples 1 and 2. Examples 1 to 4 showed even better water absorption than Examples 5 to 7.

(Deodorization evaluation)
Saturated gas of ammonia aqueous solution (2 mL of ammonia water: 2 mL of water) was inserted into a gas bag with a cock containing four test pieces of 5 cm × 5 cm absorbers with a 1.2 mL syringe, and air was further evacuated with an air pump. .5L filled. The saturated gas was collected from the gas phase in a sealed container containing an aqueous ammonia solution. The ammonia gas concentration in the gas bag after filling with saturated gas and air was 80 to 90 ppm. Next, the suction tube and the rubber tube were connected to the detection tube, and the rubber tube was connected to the gas bag. And the ammonia gas density | concentration in the gas bag after progress for 15 minutes after filling with air was measured.
◎: Very good Residual concentration is 1/3 or less of initial ○ ○: Normal Residual concentration is 1/2 to 3/1 of initial
X: Poor The residual concentration was 1/2 or more of the initial value. As a result, the results of Examples 1 to 3 and 6, 7 were evaluated as ◎, and Examples 4, 5 and Comparative Examples 1 and 2 were evaluated as ◯. Thus, in the Example which carry | supported the metal component, it turns out that the outstanding deodorizing effect is acquired.

(Manufacture of absorbent articles)
Between the top sheet and the back sheet, any one of the absorbent bodies obtained in Examples 1 to 7 was disposed, and these were integrally bonded with a hot melt adhesive to obtain an absorbent article. Here, a polypropylene spunbond nonwoven 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. In the case of using the absorbent body of any of the examples, an absorbent article having an excellent balance between water absorption and deodorant was realized.

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

Claims

A back sheet, a top sheet, and an absorber disposed between the back sheet and the top sheet,
The said absorber is an absorbent article containing the phosphorylated cellulose fiber which has a phosphate group or a substituent derived from a phosphate group.
The absorbent article according to claim 1, wherein the phosphorylated cellulose fiber includes fine fibers having a fiber width of 1000 nm or less.
The absorbent article according to claim 1 or 2, comprising one or more metal components selected from the group consisting of Ag, Au, Pt, Pd, Cu and Zn supported on the phosphorylated cellulose fiber.
The absorbent body according to any one of claims 1 to 3, wherein the absorbent body includes an absorbent main body including the phosphorylated cellulose fiber and a water-absorbent resin, and a covering member that covers the absorbent main body. Absorbent article.
The absorbent body according to any one of claims 1 to 3, wherein the absorbent body includes an absorbent main body containing a water-absorbing resin, and a covering member that covers the absorbent main body and includes the phosphorylated cellulose fiber. Absorbent article as described in 1.