JP6045278B2 - Absorbent material and absorbent article - Google Patents

Description

  The present invention relates to an absorbent article such as a diaper, a sanitary article, and a pet hygiene article, and an absorbent material of an absorbent body used for the absorbent article.

  A method for producing a self-crosslinking alkylcellulose derivative in which an alkylcellulose derivative is produced by irradiating a mixture of a raw material alkylcellulose derivative and water is known as a conventional technique (for example, Patent Document 1). Using this alkyl cellulose derivative, a biodegradable water-absorbing resin or a high-strength gelled product can be obtained.

JP 2001-2703 A

  However, the gelled product produced using the alkylcellulose derivative produced by the production method described in Patent Document 1 has a low body fluid absorption rate for use in absorbent articles such as diapers, sanitary products, and pet hygiene products. In some cases, the amount of absorbed body fluid is small.

The present invention employs the following configuration in order to solve the above problems.
That is, the absorptive material of the present invention contains cellulose hydrogel particles of cellulose hydrogel prepared by crosslinking alkyl cellulose derivatives and a surfactant.
Moreover, the absorbent article of the present invention includes the above-described absorbent material, and an absorbent body that absorbs body fluids to be used, and a liquid-permeable sheet that covers one surface of the absorbent body and transmits body fluids to be used. And a liquid-impermeable sheet that covers the other surface of the absorber and does not transmit the body fluid of what is used.

  According to the present invention, it is possible to obtain an absorbent material and an absorbent article that absorb body fluid quickly and absorb a large amount.

FIG. 1 is a partially broken plan view of a sanitary napkin according to a first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a cross section along line AA of the sanitary napkin in the first embodiment of the present invention shown in FIG. FIG. 3 is a diagram illustrating an example of a pulverizer used for producing an absorbent material. FIG. 4 is a diagram for explaining a nylon mesh bag used for measuring the amount of absorption. FIG. 5 shows an electron scanning micrograph of the absorptive material in Example 1. 6 shows an electron scanning micrograph of the absorptive material in Example 9. FIG.

-First embodiment-
The absorbent article of the first embodiment of the absorbent article according to the present invention will be described taking a sanitary napkin as an example. 1 is a partially cutaway plan view of a sanitary napkin according to the first embodiment of the present invention, and FIG. 2 is an AA view of the sanitary napkin according to the first embodiment of the present invention of FIG. It is a schematic cross section which shows a line cross section. As shown in FIGS. 1 and 2, the sanitary napkin 1 is disposed between a liquid-permeable surface material 2, a liquid-impermeable leak-proof sheet 3, and the surface material 2 and the leak-proof sheet 3. The absorbent body 4 and the covering material 5 that covers the absorbent body 4 are provided.

(Surface material)
The surface material 2 is a liquid-permeable sheet that transmits body fluid. In order to improve the feel when the user wears the sanitary napkin 1, the surface material 2 is provided on the surface in contact with the user's skin. Therefore, it is preferable that the surface material 2 has a function of improving the touch. For example, the surface material 2 is made of fine fibers, the surface material 2 has a smooth surface, and the surface material 2 needs to have a high degree of freedom with respect to deformation.

  As the surface material 2, a nonwoven fabric is generally used. The nonwoven fabric used for the surface material 2 can be formed by an air-through method using a known card web. The manufacturing method of the nonwoven fabric used for the surface material 2 is not limited to the above-described air-through method. For example, a needle punch, a spunlace method, a fiber made of an adhesive or a fiber itself is made into a stable sheet by entanglement of a fiber web. Binder bonding for fixing the web by melting, thermal bonding method, spunbond method for sealing with filament fibers, wet method for forming a sheet by papermaking, and the like may be used.

  The fibers used for the nonwoven fabric of the surface material 2 are, for example, linear low density polyethylene (LLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), polypropylene, polybutylene and the like. Copolymers Ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), ethylene-acrylic acid copolymer (EAA), polyolefins such as ionomer resins, polyethylene terephthalate (PET) Polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyester such as polylactic acid, polyamide such as nylon, and the like.

  Further, the fibers of the nonwoven fabric of the surface material 2 do not need to be fibers composed of a single component, but are composite fibers such as core / sheath fibers, side-by-side fibers, and island / sea fibers. May be. Considering thermal adhesiveness, the nonwoven fabric fibers of the surface material 2 are particularly preferably composite fibers composed of a core portion and a sheath portion. The cross-sectional shape of the fibers of the nonwoven fabric is not limited to a circle, but may be an irregular shape such as a triangular shape, a square shape, or a star shape. Further, the core portion of the nonwoven fabric fiber may be hollow, or the nonwoven fabric fiber may be porous. The cross-sectional area ratio between the core and the sheath in the core / sheath structure of the nonwoven fabric is not particularly limited, but is preferably 80/20 to 20/80, and preferably 60/40 to 40 / 60 is more preferable. When the cross-sectional area ratio between the core part and the sheath part in the core part / sheath part structure of the nonwoven fabric becomes the cross-sectional area ratio on the side where the cross-sectional area of the core part is larger than 80/20, the adhesion between the fibers is When the cross-sectional area ratio between the core part and the sheath part in the core part / sheath part structure of the nonwoven fabric fiber becomes a cross-sectional area ratio on the side where the cross-sectional area of the sheath part becomes larger than 20/80. In the thermal bonding process between fibers, most of the fibers may melt.

  The fineness of the fiber used for the nonwoven fabric of the surface material 2 is preferably 1.0 to 20 dtex, more preferably 1.2 to 4.4 dtex. Moreover, the fiber length of the fiber used for the nonwoven fabric of the surface material 2 is preferably 5 to 75 mm, and considering the card suitability, the fiber length of the fiber used for the nonwoven fabric of the surface material 2 is more preferably 25 to 51 mm.

The basis weight of the fiber used for the nonwoven fabric of the surface material 2 is preferably 10 to 100 g / m ² , and the viewpoint of suppressing so-called rewet back in which the liquid absorbed by the absorbent body 4 oozes out and the liquid permeability of the nonwoven fabric. From the viewpoint of properties and the like, it is more preferably 20 to 35 g / m ² . The density of the fiber used for the nonwoven fabric of the surface material 2 is preferably 0.001 to 0.2 g / cm ³ , and more preferably 0.015 to 0.08 g / cm from the viewpoint of rewet back and liquid permeability. ³ . The thickness of the nonwoven fabric of the surface material 2 under a load of 3 g / cm ² is preferably 0.1 to 3 mm, and more preferably 0.5 to 2 mm from the viewpoint of rewet back and liquid permeability.

(Leak-proof sheet)
The leak-proof sheet 3 is a liquid-impermeable sheet that does not transmit body fluid, and is provided to prevent excreted body fluid from leaking outside. The material of the leak-proof sheet 3 is not particularly limited as long as it is a material that does not transmit the excreted body fluid. For example, a waterproof nonwoven fabric, a plastic film made of polyethylene or the like, a composite material of a nonwoven fabric and a plastic film, or the like can be used for the leak-proof sheet 3.

(Absorber)
The absorber 4 has a function of absorbing and holding the excreted body fluid. Absorbent body 4 includes cellulose hydrogel particles of cellulose hydrogel prepared by crosslinking alkyl cellulose derivatives, hydrophilic fibers reaching the inside from the outside of the cellulose hydrogel particles, and an absorbent containing a surfactant. Contains sexual materials.

(Alkyl cellulose derivatives)
Alkyl cellulose derivatives include, for example, alkyl cellulose, carboxyalkyl cellulose, hydroxyalkyl cellulose, and combinations thereof. Alkyl cellulose derivatives also include cellulose salts, ie salts in alkyl cellulose, carboxyalkyl cellulose, hydroxyalkyl cellulose or combinations thereof.

  Examples of the cellulose salt include monovalent metal salts such as alkali metal salts (lithium salts, sodium salts, potassium salts, rubidium salts, cesium salts, etc.), ammonium salts, and amine salts. The alkyl group-containing cellulose salt is preferably, for example, an alkali metal salt, particularly a sodium salt.

(Carboxyalkyl cellulose)
Carboxyalkyl cellulose is obtained by replacing the hydrogen of the hydroxyl group of cellulose with a carboxymethyl group, a carboxyethyl group, or a carboxypropyl group. Particularly preferred carboxyalkyl celluloses are carboxymethyl cellulose and carboxyethyl cellulose. In the carboxyalkyl cellulose, 20% or more, preferably 40% or more of the carboxyl groups are alkali metal salt, ammonium salt or amine salt. When the ratio of forming the salt is less than 20%, it becomes difficult to form a uniform mixture or aqueous solution with water. There is no particular upper limit on the ratio of salt formation, and 100% salt may be formed.

(Hydroxyalkyl cellulose)
Hydroxyalkyl cellulose is obtained by reacting hydrogen of a hydroxyl group of cellulose with, for example, ethylene oxide or propylene oxide. Therefore, the group substituted for hydrogen is a hydroxyethyl (—C ₂ H ₄ OH) group, a hydroxyisopropyl group (—C ₃ H ₆ OH), a hydroxy-n-propyl group (—C ₃ H ₆ OH), It is a polyoxyalkylene ether substituent obtained by further reacting 1 to 10 molecules of ethylene oxide, propylene oxide or the like at the hydroxy end. Particularly preferred hydroxyalkylcelluloses are hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose and hydroxyethylmethylcellulose. In the hydroxyalkyl cellulose, 20% or more, preferably 40% or more, more preferably 50% or more of the hydroxyl groups are alkali metal salts. When the ratio of forming the salt is less than 20%, it becomes difficult to form a uniform mixture or aqueous solution with water. There is no particular upper limit on the ratio of salt formation, and 100% salt may be formed.

(Alkyl cellulose)
Alkyl cellulose is one in which the hydroxyl group hydrogen of cellulose is partially substituted with a methyl group, an ethyl group, or a propyl group. Particularly preferred alkyl celluloses are methyl cellulose and ethyl cellulose. The alkyl cellulose has an alkyl etherification degree of 66% or less, preferably 50% or less, and more preferably 33% or less. Alkyl cellulose used as a raw material is 40% or more, preferably 50% or more of the remaining hydroxyl group is an alkali metal salt. When the ratio of forming the salt is less than 40%, it becomes difficult to form a uniform mixture or aqueous solution with water. There is no particular upper limit on the ratio of salt formation, and 100% salt may be formed.

  The alkyl cellulose derivative is not particularly limited in the average degree of polymerization, but is, for example, 10 to 7000, preferably 50 to 6000, and more preferably 200 to 4000.

  The average degree of etherification of the alkylcellulose derivative (referred to as the degree of substitution for replacing hydrogen of the hydroxyl group of cellulose with a carboxyalkyl group, hydroxyalkyl group, or alkyl group) is, for example, 0.5 or more, preferably 0. .8 or more, more preferably 1.0 or more, and a maximum of 3. When the average degree of etherification is less than 0.5, sufficient crosslinking does not occur.

  As the alkyl cellulose derivative, those produced by a known method, in particular, commercially available products can be used.

  Carboxyalkyl cellulose is produced by various methods such as a conventional slurry method (high liquid ratio method) and a kneader method (low liquid ratio method), for example, a step of reacting cellulose and alkali to produce alkali cellulose (mercelization). And a step (carboxyalkylation step) of producing carboxyethylcellulose by hydrolysis of ester after reaction with carboxymethylcellulose or acrylic ester by reaction of alkali cellulose with monochloroacetic acid. Produced.

  Hydroxyalkyl cellulose is obtained, for example, by reacting an alkylene oxide with a hydroxyl group of cellulose. Hydroxyethyl cellulose is obtained by reacting ethylene oxide, and hydroxypropyl cellulose is obtained by reacting propylene oxide with the hydroxyl group of cellulose. Those obtained by further reacting with an alkylene oxide can also be used. For example, ethyl hydroxyethyl cellulose is obtained by further reacting hydroxyethyl cellulose with ethylene oxide.

  Alkyl cellulose is produced, for example, by reaction of alkali cellulose with alkyl chloride or dialkyl sulfuric acid. Methyl cellulose is obtained, for example, by a reaction between alkali cellulose and methyl chloride or dimethyl sulfate, and ethyl cellulose is obtained by a reaction between alkali cellulose and ethyl chloride or diethyl sulfate.

  The cellulose hydrogel particles preferably have a porous structure. Thereby, the quantity which a cellulose halide gel particle can absorb a bodily fluid increases. In addition, since the speed at which the body fluid permeates into the porous structure of the cellulose halide gel particles is faster than the speed at which the body fluid diffuses through the cellulose hydrogel particles, the absorption of the body fluid of the cellulose hydrogel particles becomes faster.

(Surfactant)
The surfactant is not particularly limited as long as the hydrophilic surface of the cellulose hydrogel particles can be made hydrophobic. For example, surfactants include ionic surfactants such as anionic surfactants, cationic surfactants and amphoteric surfactants, and nonionic surfactants. Since the surface of the cellulose hydrogel particles is often charged, the surfactant is preferably an ionic surfactant. Further, since the surface of the cellulose hydrogel particles is often negatively charged, the ionic surfactant is more preferably a cationic surfactant.

  When the surface of the cellulose hydrogel particles is in a hydrophilic state, the body fluid attached to the surface of the cellulose hydrogel particles may remain on the surface of the cellulose hydrogel particles. In this case, it may be difficult for the body fluid adhered to the surface of the cellulose hydrogel particles to penetrate into the cellulose hydrogel particles. As a result, the absorption of the bodily fluid of the absorber 4 may be delayed, and the amount of absorption of the bodily fluid may be reduced.

  The cellulose hydrogel particles preferably contain a surfactant inside. Thereby, the body fluid adhering to the surface of the cellulose hydrogel particle becomes easy to penetrate into the inside of the cellulose hydrogel particle. Therefore, the absorption of body fluid by the absorbent material can be accelerated.

  The content of the surfactant in the absorbent material is preferably 0.5 to 3.0 parts by weight with respect to 100 parts by weight of cellulose hydrogel particles, and more preferably with respect to 100 parts by weight of cellulose hydrogel particles. 0.5 to 2.0 parts by weight. If the content of the surfactant is less than 0.5 parts by weight, the effect of making the surface of the cellulose hydrogel particles hydrophobic may be too small. When the content of the surfactant is more than 3.0 parts by weight, the hydrophobicity of the surface of the cellulose hydrogel particles becomes too high, and the liquid absorption of the cellulose hydrogel particles may be delayed.

(Anionic surfactant)
Examples of the anionic surfactant include fatty acid soap, alkenyl succinic acid salt, alkylbenzene sulfonic acid sodium salt, alkyl naphthalene sulfonic acid sodium salt, alkyl sulfate ester sodium salt, polyoxyethylene alkyl ether sulfate sodium salt, dialkyl sulfosuccinate. Examples thereof include sodium salts, sodium alkyl phosphates, polycarboxylic acid type polymer surfactants, and the like.

(Cationic surfactant)
Cationic surfactants include dioleyldimethylammonium chloride, alkyltrimethylammonium chloride, alkyldimethylbenzylammonium chloride, and the like. Since dioleyldimethylammonium chloride can strongly bind to the surface of negatively charged cellulose hydrogel particles, the cationic surfactant is preferably dioleyldimethylammonium chloride.

(Amphoteric surfactant)
Examples of amphoteric surfactants include alkyl betaines and amide butines.

(Nonionic surfactant)
Nonionic surfactants include sucrose fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, sorbitan fatty acid esters, and the like. The nonionic surfactant is preferably a sucrose fatty acid ester.

(Cellulose hydrogel)
The cellulose hydrogel is a gel (crosslinked gel or crosslinked product) in which an alkylcellulose derivative is self-crosslinked by radiation. The radiation will be described later. Cellulose hydrogels are usually gels that are self-crosslinked in the absence of a crosslinking agent. Cellulose hydrogel is biodegradable. However, the cellulose hydrogel may be a gel crosslinked by a crosslinking agent or heating instead of radiation.

  The cellulose hydrogel is preferably selected from the group consisting of an alkylcellulose hydrogel, a carboxyalkylcellulose hydrogel, a hydroxyalkylcellulose hydrogel or a combination thereof, more preferably a methylcellulose hydrogel, an ethylcellulose hydrogel, a carboxyethylcellulose hydrogel, It is selected from the group consisting of hydroxyethylcellulose hydrogel, hydroxypropylcellulose hydrogel or combinations thereof.

  The gel fraction of the cellulose hydrogel is 1 to 70%, preferably 3 to 50%, more preferably 5 to 40%. If the gel fraction of the cellulose hydrogel is less than 1%, crosslinking is insufficient, and if it exceeds 70%, crosslinking proceeds too much, resulting in insufficient water absorption.

The gel fraction is a ratio of insoluble matter when the product is immersed in a large amount (for example, 10 to 100 times the product) of distilled water for 48 hours and then filtered through a 20 mesh stainless steel wire mesh. It is calculated by.
Gel fraction (%) = (W ₂ / W ₁ ) × 100 (W ₁ represents the dry weight of the alkyl cellulose derivative used, and W ₂ represents the dry weight of the insoluble matter after filtration of the crosslinked product. Represents.)

For example, a biodegradable alkyl cellulose such as carboxymethyl cellulose rapidly biodegrades when washed with water or discarded in soil. Therefore, since it is not necessary to incinerate when it is discarded, CO ₂ emissions can be reduced.

(Cellulose hydrogel particles)
The particle size of the cellulose hydrogel particles is not particularly limited as long as the absorbent material can absorb 0.9% physiological saline or artificial menstrual blood.

(Hydrophilic fiber)
Examples of hydrophilic fibers include pulp fibers, rayon fibers, cotton, acetate, cellulose acetate, acrylic fibers having micropores, and synthetic resin fibers subjected to a hydrophilic treatment. Particularly preferred hydrophilic fibers are pulp fibers.

  It is preferable that the hydrophilic fibers reach the inside from the outside of the cellulose hydrogel particles. Thereby, the path | route for drawing in a user's bodily fluid to the inside of an absorptive material can be ensured, and the water absorption speed of an absorptive material can be made quick. Moreover, it is preferable that the hydrophilic fiber of an absorptive material coat | covers the cellulose hydrogel particle. As a result, the density of the surface of the cellulose hydrogel particles can be reduced, and when the absorbent material absorbs body fluid or the like, the surface of the absorbent material swells first, and it takes a very long time to penetrate into the interior. This can be suppressed.

  The weight ratio between the cellulose hydrogel particles and the hydrophilic fibers is preferably 1: 1 to 1: 2. If the weight ratio between the cellulose hydrogel particles and the hydrophilic fibers is shifted to a side where the cellulose hydrogel particle side is less than 1: 1, the liquid retention amount of the absorbent material may be reduced. In addition, when the weight ratio between the cellulose hydrogel particles and the hydrophilic fibers is shifted to the side where the cellulose hydrogel is more than 1: 2, the absorption of the absorbent material may not be accelerated.

  The absorber 4 may further contain sodium polyacrylate (SAP). The water retention performance of the absorbent material can be improved by the water retention effect of SAP. The addition amount of SAP is the same weight as a hydrophilic fiber, for example.

(Coating material)
The covering material 5 prevents the absorber 4 from collapsing and falling apart by covering the absorber 4. The covering material 5 is a liquid-permeable sheet, preferably a tissue. In addition, when the absorbent body 4 does not collapse without the covering material 5, the sanitary napkin 1 may not have the covering material 5.

(Manufacturing method of absorbent material)
Next, the manufacturing method of the absorptive material contained in the absorber 4 is demonstrated. The method for producing an absorbent material includes a step of mixing an alkyl cellulose derivative and water to prepare an aqueous solution of alkyl cellulose derivative, a step of adding a surfactant to the aqueous solution of alkyl cellulose derivative to prepare a surfactant-containing mixture, A step of producing a cellulose hydrogel by irradiating a surfactant-containing mixture with radiation, and mixing with hydrophilic fibers while cutting the cellulose hydrogel, and the cellulose hydrogel particles of the cellulose hydrogel and the mixture of the hydrophilic fibers And a step of drying the mixture at a temperature of 100 ° C. or lower.

  An alkylcellulose derivative aqueous solution is prepared by mixing an alkylcellulose derivative and water. Since the alkyl cellulose derivative has been described above, the description of the alkyl cellulose derivative is omitted.

(water)
Examples of water mixed with the alkyl cellulose derivative include city water, industrial water, degassed water, deionized water, gel filtered water, distilled water, and the like, and preferably contain no oxygen or ions. is there.

  The proportion of the alkylcellulose derivative in the alkylcellulose derivative aqueous solution is preferably 10 to 80% by weight. In the case of an alkylcellulose derivative such as carboxymethylcellulose, decomposition is prioritized by radiation, but in the presence of water, a hydroxy radical generated from water is generated, and self-crosslinking is considered to proceed through this radical. The mixed state of the alkyl cellulose derivative and water in the alkyl cellulose derivative aqueous solution is a paste-like paste, even if the alkyl cellulose derivative contains water as moisture, and is preferably as uniform as possible. When the proportion of the alkylcellulose derivative in the aqueous alkylcellulose derivative is less than 10% by weight, crosslinking is difficult to occur, and when the proportion of the alkylcellulose derivative in the aqueous alkylcellulose derivative is greater than 80% by weight, the alkylcellulose derivative is decomposed. Become more.

  Next, a surfactant is added to the alkyl cellulose derivative aqueous solution to prepare a surfactant-containing mixture. The surfactant-containing mixture may be an aqueous solution or a paste mixture, but is preferably a paste mixture.

(Surfactant)
As described above, the surfactant added to the alkylcellulose derivative aqueous solution is not particularly limited as long as the hydrophilic surface of the cellulose hydrogel particles can be made hydrophobic. For example, the surfactant added to the alkyl cellulose derivative aqueous solution includes ionic surfactants such as anionic surfactants, cationic surfactants and amphoteric surfactants, and nonionic surfactants. Since the surface of the cellulose hydrogel particles is often charged, the surfactant added to the aqueous alkyl cellulose derivative is preferably an ionic surfactant. Further, since the surface of the cellulose hydrogel particles is often negatively charged, the ionic surfactant added to the alkyl cellulose derivative aqueous solution is preferably a cationic surfactant.

  The addition amount of the surfactant is preferably 0.5 to 3.0 parts by weight with respect to 100 parts by weight of the alkyl cellulose derivative, more preferably 0.5 to 2 parts with respect to 100 parts by weight of the alkyl cellulose derivative. 0.0 part by weight. When the addition amount of the surfactant is less than 0.5 parts by weight, the effect of making the surface of the cellulose hydrogel particles hydrophobic may be too small. If the amount of the surfactant added is more than 3.0 parts by weight, the surface of the cellulose hydrogel particles may become too hydrophobic, and the liquid absorption rate may decrease.

  Since the surfactant is added before the surfactant-containing mixture is irradiated with radiation to produce the cellulose hydrogel, the surfactant can be present not only on the surface of the cellulose hydrogel particles but also inside. As described above, this allows the body fluid attached to the surface of the cellulose hydrogel particles to easily penetrate into the cellulose hydrogel particles, and the absorption of the body fluid by the absorbent material can be accelerated.

  Next, a cellulose hydrogel is produced by irradiating the surfactant-containing mixture with radiation. Since the cellulose hydrogel has been described above, the description of the cellulose hydrogel is omitted.

(radiation)
Examples of the radiation applied to the surfactant-containing mixture include α rays, β rays, γ rays, X rays, electron beams, ultraviolet rays, and the like. Particularly preferred radiation is gamma rays, electron beams, and X-rays.

  The amount of radiation to be irradiated is 0.1 to 50 kGy, preferably 0.3 to 20 kGy, more preferably 0.5 to 10 kGy in terms of γ-ray. If the radiation dose is less than 0.1 kGy, crosslinking will not occur and water absorption will be insufficient, and if it exceeds 50 kGy, crosslinking will proceed too much and water absorption will be insufficient.

  When irradiation is performed in the absence of oxygen, the irradiation can be carried out efficiently (that is, at a low radiation dose). This is because irradiation with radiation in the presence of oxygen increases the rate at which the alkylcellulose derivative undergoes oxidative decomposition.

  The alkyl cellulose derivative may be cross-linked by a cross-linking agent or heating instead of radiation.

  Next, the cellulose hydrogel is mixed with hydrophilic fibers while cutting to produce a mixture of cellulose hydrogel particles and hydrophilic fibers of the cellulose hydrogel. When mixing cellulose hydrogel and hydrophilic fiber, by mixing cellulose hydrogel and hydrophilic fiber while cutting the cellulose hydrogel, the hydrophilic fiber of the absorbent material is removed from the outside of the cellulose hydrogel particles. While reaching the inside, the cellulose hydrogel particles can be coated. As an apparatus for performing such mixing, for example, a pulverizer that includes a pulverizing cutter and performs pulverization by rotating the pulverizing cutter is preferably used. Examples of such a crusher include Wonder crush / mil D3V-10 manufactured by Osaka Chemical Co., Ltd. and Grindmix GM200 manufactured by Lecce Co., Ltd. FIG. 3 shows an example of a pulverizer that includes a pulverization cutter and performs pulverization by rotating the pulverization cutter.

  The crusher 10 includes a container lid 12 provided with a handle 11, a crushing tank 15 having a crushing cutter 13 and a fastening screw 14 for fixing the crushing cutter 13 to a rotating shaft (not shown), and a main body 16. . A rotating shaft (not shown) extends perpendicularly to the bottom 17 of the crushing tank 15. The sample to be mixed is put into the crushing tank 15. The crushing cutter 13 is provided at the bottom 17 of the crushing tank 15 and has two substantially rectangular blades extending in the direction perpendicular to the rotation axis. One substantially rectangular blade is convexly curved in the direction of the container lid 12, and the other substantially rectangular blade is convexly curved in the direction of the bottom 17 of the crushing tank 15. As the grinding cutter 13 rotates, the sample in the grinding tank 15 is crushed. When two or more kinds of samples are put into the crushing tank 15, the two or more kinds of samples in the crushing tank 15 are pulverized and mixed.

  In one embodiment of the present invention, cellulose hydrogel and hydrophilic fibers are put into the crushing tank 15, the crushing tank 15 is sealed with the container lid 12, and then the crushing cutter 13 is rotated at a high speed, for example, 25000 rpm. By mixing, cellulose hydrogel and hydrophilic fiber are mixed. And the mixture containing a cellulose hydrogel particle and the hydrophilic fiber which has reached | attained the inside from the exterior of a cellulose hydrogel particle can be obtained.

  In addition, if the cellulose hydrogel and the hydrophilic fiber can be mixed while cutting the cellulose hydrogel, the mixing device for mixing the cellulose hydrogel and the hydrophilic fiber is not limited to the pulverizer 10.

  When the cellulose hydrogel and the hydrophilic fiber are mixed, the weight ratio between the cellulose hydrogel and the hydrophilic fiber is preferably 1: 1 to 1: 2. If the weight ratio between the cellulose hydrogel and the hydrophilic fiber is shifted to a smaller amount on the cellulose hydrogel side than 1: 1, the liquid retention amount of the absorbent material may be reduced. In addition, when the weight ratio between the cellulose hydrogel and the hydrophilic fiber is shifted to a larger amount of the cellulose hydrogel than 1: 2, the absorption of the absorbent material may not be accelerated.

  Next, the mixture of cellulose hydrogel particles and hydrophilic fibers is dried at a temperature of 100 ° C. or lower.

(Dry)
Drying of the mixture of cellulose hydrogel particles and hydrophilic fibers can be performed using an appropriate apparatus such as a dryer (such as a constant temperature dryer). Further, the drying may be performed in an air or oxygen atmosphere, an inert atmosphere (helium, argon, nitrogen), or in the air. Moreover, you may perform drying under atmospheric pressure or pressurization. In addition, after applying water, you may perform a drying process (conventional drying processes, such as natural drying, reduced pressure drying, and hot-air drying). The drying temperature of the cellulose hydrogel is preferably 20 ° C. or higher and 100 ° C. or lower, more preferably 30 ° C. or higher and 80 ° C. or lower. When the drying temperature is lower than 20 ° C., the cellulose hydrogel does not dry well. When the drying temperature is higher than 100 ° C., there is a problem of performance deterioration due to thermal decomposition.

  In addition, when mixing a cellulose hydrogel and a hydrophilic fiber, you may add a sodium polyacrylate (SAP) further. The water retention performance of the absorbent material can be improved by the water retention effect of SAP. The addition amount of SAP is the same weight as a hydrophilic fiber, for example.

  In addition, even if the absorbent material of the absorber 4 is produced by adding hydrophilic fibers such as pulverized pulp to a mixture of cellulose hydrogel and hydrophilic fibers produced by drying at a temperature of 100 ° C. or less. Good. The amount of hydrophilic fibers added to the mixture is, for example, the same weight as the mixture.

-Second Embodiment-
A sanitary napkin will be described as an example of the absorbent article according to the second embodiment of the present invention. Similarly to the sanitary napkin 1 of the first embodiment, the sanitary napkin of the second embodiment includes a liquid-permeable surface material, a liquid-impermeable leak-proof sheet, a surface material, and a leak-proof sheet. And an covering member that covers the absorber. Hereinafter, with respect to the absorbent article according to the second embodiment of the present invention, portions different from the absorbent article according to the first embodiment of the present invention will be mainly described.

(Absorber)
The absorbent body of the sanitary napkin of the second embodiment has a function of absorbing and holding excreted body fluid. An absorber contains the absorptive material containing the cellulose hydrogel particle | grains of the cellulose hydrogel produced by bridge | crosslinking an alkyl cellulose derivative, and surfactant. Unlike the absorbent material of the sanitary napkin of the first embodiment, the absorbent material of the sanitary napkin of the second embodiment does not include hydrophilic fibers.

(Surfactant)
The surfactant is not particularly limited as long as the hydrophilic surface of the cellulose hydrogel particles can be made hydrophobic as in the surfactant in the absorbent material of the sanitary napkin of the first embodiment. For example, the surfactant includes an ionic interface such as an anionic surfactant, a cationic surfactant and an amphoteric surfactant, as in the surfactant in the absorbent material of the sanitary napkin of the first embodiment. Activators and nonionic surfactants can be mentioned. Since the surface of the cellulose hydrogel particles is often charged, the surfactant is preferably an ionic surfactant. Further, since the surface of the cellulose hydrogel particles is often negatively charged, the ionic surfactant is more preferably a cationic surfactant.

  When the surface of the cellulose hydrogel particles is in a hydrophilic state, the body fluid attached to the surface of the cellulose hydrogel particles may remain on the surface of the cellulose hydrogel particles. In this case, it may be difficult for the body fluid adhered to the surface of the cellulose hydrogel particles to penetrate into the cellulose hydrogel particles. As a result, the absorption of the bodily fluid of the absorber 4 may be delayed, and the amount of absorption of the bodily fluid may be reduced. In particular, if the surface of the cellulose hydrogel particles swells due to the body fluid remaining on the surface of the cellulose hydrogel particles, it may become more difficult to penetrate into the cellulose hydrogel particles. Moreover, under high humidity, cellulose hydrogel particles may be bonded to each other, and the absorbability of the absorbent material may be deteriorated.

  Also in 2nd Embodiment, it is preferable that the cellulose hydrogel particle contains surfactant in the inside. Thereby, the body fluid adhering to the surface of the cellulose hydrogel particle becomes easy to penetrate into the inside of the cellulose hydrogel particle. Therefore, the absorption of body fluid by the absorbent material can be accelerated.

  The content of the surfactant in the absorbent material is preferably 0.5 to 2.0 parts by weight with respect to 100 parts by weight of the cellulose hydrogel particles. If the content of the surfactant is less than 0.5 parts by weight, the effect of making the surface of the cellulose hydrogel particles hydrophobic may be too small. When the content of the surfactant is more than 2.0 parts by weight, the hydrophobicity of the surface of the cellulose hydrogel particles becomes too high, and the liquid absorption of the cellulose hydrogel particles may be delayed.

(Manufacturing method of absorbent material)
Next, the manufacturing method of the absorptive material contained in the absorber of the sanitary napkin of 2nd Embodiment is demonstrated. The method for producing an absorbent material includes a step of mixing an alkyl cellulose derivative and water to prepare an aqueous solution of alkyl cellulose derivative, a step of adding a surfactant to the aqueous solution of alkyl cellulose derivative to prepare a surfactant-containing mixture, The step of producing a cellulose hydrogel by irradiating the surfactant-containing mixture with radiation, the step of making the cellulose hydrogel fine by cutting the cellulose hydrogel, and the step of producing the cellulose hydrogel particles at 100 ° C. or less Drying at a temperature.

  Also in the second embodiment, since the surfactant is added before the surfactant-containing mixture is irradiated with radiation to produce the cellulose hydrogel, the surfactant is not only applied to the surface of the cellulose hydrogel particles but also to the inside. Can exist. As described above, this allows the body fluid attached to the surface of the cellulose hydrogel particles to easily penetrate into the cellulose hydrogel particles, and the absorption of the body fluid by the absorbent material can be accelerated.

  In the manufacturing method of the absorptive material contained in the absorbent body of the sanitary napkin of the second embodiment, the step of finely cutting the cellulose hydrogel to produce cellulose hydrogel particles is the same as that of the first embodiment. Since it is different from the manufacturing method of the absorptive material contained in the absorbent body of the sanitary napkin, the above steps will be mainly described.

  The cellulose hydrogel is finely cut by cutting to produce cellulose hydrogel particles. For example, a pulverizer similar to the pulverizer described in the first embodiment is preferably used as an apparatus that can be finely cut by cutting the cellulose hydrogel.

  For example, after putting cellulose hydrogel into the crushing tank 15 of the crusher 10 described in the first embodiment and sealing the crushing tank 15 with the container lid 12, the crushing cutter 13 is rotated at a high speed, for example, 25000 rpm. By rotating, the cellulose hydrogel is cut to make the cellulose hydrogel fine to produce cellulose hydrogel particles.

  If the cellulose hydrogel can be made fine by cutting the cellulose hydrogel, the device for making the cellulose hydrogel fine is not limited to the pulverizer 10 described in the first embodiment.

  The absorbent article of the present invention includes absorbent articles used by animals other than humans such as pets in addition to absorbent articles used by humans. Animals that use absorbent articles, including non-human animals such as humans and pets, are referred to as “uses”.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

  In Examples and Comparative Examples, the water absorption rate, water absorption rate and water retention rate in 0.9% physiological saline, and the absorption rate, rewetting amount and blood retention rate in artificial menstrual blood were measured as follows.

(Water absorption rate in 0.9% physiological saline)
(1) Add 27.0 g of sodium chloride (reagent grade 1) to a 3 L beaker, and add ion exchange water to the 3 L beaker so that the total mass of sodium chloride and ion exchange water is 3000.0 g. It was. Then, sodium chloride-containing ion-exchanged water was stirred until all sodium chloride was completely dissolved to prepare 0.9% physiological saline.
(2) 0.9% physiological saline was placed in a 1 L beaker, and a 1 L beaker containing 0.9% physiological saline was placed in a water bath set at a temperature of 25 ° C. ± 1 ° C. And it was left until the temperature of 0.9% physiological saline in a 1 L beaker reached 25 ° C. ± 1 ° C.
(3) 30 g of 0.9% physiological saline contained in a 1 L beaker was taken out and added to a 100 mL beaker containing a rotor (length: 30 mm, diameter: 8 mm).
(4) A 100 mL beaker containing 30 g of 0.9% physiological saline was placed on a magneck stirrer (MITAMURA RIKEN KOGYO INC. MAGMIX STIRRER (AC100W)). Then, the rotational speed of the rotor was adjusted so that the rotational speed of the rotor was 600 ± 30 rpm while measuring the rotational speed of the rotor using a non-contact type tachometer (LINE SEIKI TM-4000). .
(5) 2.00 g of absorbent material was added into a 100 mL beaker with rotating rotor. Then, using the stopwatch, the time from when the absorbent material was added to the 100 mL beaker until the liquid surface of the absorbent material-containing physiological saline in the 100 mL beaker became flat was measured. This measured time becomes the water absorption rate in 0.9% physiological saline. When the absorbent material absorbs 0.9% physiological saline, the movement of the liquid surface of the absorbent material-containing physiological saline stops, so that the liquid surface of the absorbent material-containing physiological saline becomes flat. The shorter the water absorption rate, the faster the absorbent material can absorb the liquid.
(6) The above test is repeated five times, and the average value of the five measurement results is the water absorption rate of the sample in 0.9% physiological saline.

(Absorption rate and retention rate in 0.9% saline)
(1) 0.9% physiological saline prepared in the same manner as 0.9% physiological saline used when measuring the water absorption rate in 0.9% physiological saline was prepared.
(2) 1000 mL of 0.9% physiological saline was placed in a 2 L beaker, and the liquid temperature was measured.
(3) A 250-mesh nylon mesh (N-NO.250HD, manufactured by NBC Kogyo Co., Ltd.) was cut into a size of 200 mm × 200 mm, and the mass (x (g)) was measured. Then, as shown in FIG. The part of the BB dashed line was folded, and the nylon mesh 21 was folded in half. As shown in FIG. 4B, after placing the folded portion on the right side, the heat seal 22 is formed at a position 5 mm above the lower end, a position 5 mm left from the right end, and a position 5 mm right from the left end. Thus, a nylon mesh bag 24 having an open upper end 23 was produced. The pulverized absorbent material (y (g)) whose mass was measured in advance was put in the nylon mesh bag 24 to form a heat seal (not shown), and the open upper end 23 of the nylon mesh bag 24 was closed.
(4) While the upper end 23 of the bag containing the absorbent material is facing upward, the bag containing the absorbent material is immersed until it touches the bottom of a 2 L beaker containing 0.9% physiological saline, and left for 1 hour. did. In addition, the side of the upper end 23 of the bag containing an absorbent material was fixed to the edge of the 2 L beaker using a clothespin.
(5) After leaving, the bag containing the absorbent material is pulled up, and the center of the short side of the bag containing the absorbent material (5 mm below the upper end 23 and 50 mm inside both lateral ends) is washed. After pinching with scissors, draining was performed for 15 minutes.
(6) After removing the clothespin from the bag containing the absorbent material, the weight (z ₁ (g)) of the bag containing the absorbent material was measured.
(7) Absorption capacity was calculated from the following equation.
Absorption capacity (g / g) = ((z ₁ −x) −y) / y
(8) The bag containing the absorbent material measured in (6) was dehydrated for 90 seconds with a centrifuge. The centrifuge used was a separator type H130 manufactured by Kokusan Centrifugal Co., Ltd. The rotation speed of the centrifuge was 850 rpm (centrifugal force was 150 G).
(9) The weight (z ₂ ) of the bag containing the absorbent material after dehydration was measured.
(10) The water retention magnification was calculated from the following equation.
Water retention magnification (g / g) = ((z ₂ −x) −y) / y
(11) The water absorption capacity (CMC water storage capacity) of the cellulose hydrogel in the absorbent material can be calculated by the following formula.
CMC water retention ratio (g / g) = (Water retention ratio of absorbent material− (7.6 × component ratio of hydrophilic fiber (wt%) / 100)) / (component ratio of hydrogel (wt%) / 100)
Here, the water retention amount of the hydrophilic fiber (pulp) alone is 7.6 g / g.
(12) The above test is repeated five times, and the average value of the five measurement results is the absorption and retention ratios of the sample in 0.9% physiological saline.

(Absorption rate in artificial menstrual blood)
0.1 g of an absorbent material was placed on an aluminum foil cup having a diameter of 3 cm, and 2 mL of artificial menstrual blood was dropped at a dropping rate of 1 mL / second. Then, the time (water absorption rate) until the artificial menstrual blood was completely absorbed by the absorbent material and the artificial menstrual blood disappeared from the surface of the absorbent material was measured.

(Rewet amount in artificial menstrual blood)
0.1 g of an absorbent material was placed on an aluminum foil cup having a diameter of 3 cm, and 2 mL of artificial menstrual blood was dropped and left for 2 minutes. Then, a non-woven fabric of 30 g / m ² is placed on the absorbent material that has absorbed artificial menstrual blood, a filter paper (35 × 50 mm) is further placed thereon, and a load of 30 g / cm ² is applied to the filter paper. A weight was placed on it. Three minutes after placing the weight, the weight of the filter paper was measured, and the amount of increase relative to the weight of the filter paper before placing on the nonwoven fabric was defined as the rewet amount.

(Blood retention magnification in artificial menstrual blood)
The retention rate in artificial menstrual blood was calculated from the rewetting amount in the artificial menstrual blood using the following formula.
Blood retention ratio (g / g) = (2 (g) −rewetting amount (g)) / 0.1 (g)
The mass of 2 mL of artificial menstrual blood is 2 g. Further, 0.1 (g) is the mass of the absorbent material.

(Method for producing artificial menstrual blood)
The artificial menstrual blood used in the above test was prepared as follows.
In a plastic container A, 320 ± 2 g of glycerin (Wako Pure Chemical Industries, Ltd., Wako Grade 1) is added, and sodium carboxymethylcellulose (NaCMC) (chemicals manufactured by Wako Pure Chemical Industries, Ltd.) 32.0 ± 0.3 g The solution A was prepared by stirring for 10 minutes at a rotational speed of about 600 rpm with a stirrer. Next, the solution A prepared previously was added little by little while stirring 3 liters of ion-exchanged water in another polycontainer B with a stirrer (manufactured by HSIANGTAIMACHINERY INDUSTRY CO. LTD.) At a rotation speed of about 1100 rpm. Further, the polycontainer A was added while washing with 1 liter of ion exchange water. Into the solution B thus obtained, 40 g of sodium chloride (NaCl) (reagent special grade manufactured by Wako Pure Chemical Industries, Ltd.) and sodium hydrogen carbonate (NaHCO ₃ ) (Wako first grade manufactured by Wako Pure Chemical Industries, Ltd.) 16 g Was added little by little with stirring, and after the addition was completed, the mixture was stirred for about 3 hours. Next, 32 g of edible dye preparation (manufactured by Koyo Prodac Co., Ltd.): Red No. 102) and 8 g of edible dye preparation (manufactured by Koyo Prodac Co., Ltd.): Red No. 2) were added to the solution C obtained by the above adjustment. Food dye preparation (manufactured by Koyo Productac Co., Ltd .: Yellow No. 5) was added while stirring, and then stirred for about 1 hour to obtain artificial menstrual blood. It was 22-26 mPa * s when the viscosity of the obtained artificial menstrual blood was measured with the viscosity measuring device (Bismetron type | formula VGA-4 by Shibaura system company).

Example 1
Carboxymethylcellulose row scan sodium (manufactured by Daicel Chemical Industries Part Number: 1380) and were mixed with ion-exchanged water, carboxymethyl cellulose row scan (hereinafter, referred to as CMC) concentration of was prepared 20 wt% aqueous CMC solution. 0.67 g of dioleyldimethylammonium chloride (2-OLR) 75 wt% solution (manufactured by NOF Corporation, a cationic surfactant) was added to and mixed with 50 g of CMC aqueous solution to prepare a paste-like mixture. The ratio of 2-OLR added to the CMC aqueous solution was 1.0 part by weight with respect to 100 parts by weight of CMC. CMC hydrogel was prepared by irradiating the paste mixture with γ rays at 10 kGy. CMC hydrogel is cut into 1 cm square using scissors, and the cut CMC hydrogel, 50 g, and 10 g of pulp fiber are pulverized (Osaka Chemical Co., Ltd., Wonder crush / mill, D3V-10). The mixture was crushed and mixed for 30 seconds to prepare a CMC mixture. The weight ratio of the CMC hydrogel and the pulp fiber added was 1: 1. The pulverized and mixed CMC mixture was dried with hot air at 60 ° C., and then the dried CMC mixture was passed through a 20-mesh sieve to produce Example 1.

(Example 2)
Example 2 was produced in the same manner as Example 1. However, the amount of the absorbent material used for the measurement was 80% by weight with respect to the amount of Example 1. For example, 1.60 g of an absorbent material was used for the measurement of the water absorption rate in physiological saline, and 0.08 g of the absorbent material was used for the measurement of the absorption rate, rewet amount and blood retention magnification in artificial menstrual blood.

Example 3
Example 3 was prepared in the same manner as Example 1 except that the amount of 2-OLR 75 wt% solution added was 0.33 g. The proportion of 2-OLR added to the CMC aqueous solution was 0.5 parts by weight with respect to 100 parts by weight of CMC.

Example 4
Example 4 was prepared in the same manner as Example 1, except that the amount of 2-OLR 75 wt% solution was 1.33 g. The ratio of 2-OLR added to the CMC aqueous solution was 2.0 parts by weight with respect to 100 parts by weight of CMC.

(Example 5)
Example 5 was produced in the same manner as in Example 1 except that the amount of pulp fiber charged into the pulverizer was 20 g. The weight ratio of CMC hydrogel to pulp fiber was 1: 2.

(Example 6)
Instead of 0.67 g 2-OLR 75 wt% solution, 20 g sucrose fatty acid ester 2.5 wt% solution (Daiichi Kogyo Seiyaku, DK ester, nonionic surfactant) was added, Example 6 was produced by the same method as Example 1. The ratio of the sucrose fatty acid ester added to the CMC aqueous solution was 1.0 part by weight with respect to 100 parts by weight of CMC.

(Example 7)
Example 7 was prepared in the same manner as Example 1 except that the amount of 2-OLR 75 wt% solution added was 1.33 g and the amount of pulp fibers charged into the grinder was 20 g. . The ratio of 2-OLR added to the CMC aqueous solution was 2.0 parts by weight with respect to 100 parts by weight of CMC. Moreover, the weight ratio of CMC hydrogel and pulp fiber was 1: 2.

(Example 8)
Example 8 was prepared in the same manner as Example 1 except that the amount of 2-OLR 75 wt% solution added was 2.0 g. The ratio of 2-OLR added to the CMC aqueous solution was 3.0 parts by weight with respect to 100 parts by weight of CMC.

Example 9
Except that no addition of hydrophilic fibers, Example 9 was prepared in the same manner as in Example 1.

(Example 10)
Example 10 was produced in the same manner as Example 9. However, the amount of the absorbent material used for the measurement was 80% by weight with respect to the amount of Example 1. For example, 1.60 g of an absorbent material was used for the measurement of the water absorption rate in physiological saline, and 0.08 g of the absorbent material was used for the measurement of the absorption rate, rewet amount and blood retention magnification in artificial menstrual blood.

(Example 11)
Example 11 was prepared in the same manner as Example 1 except that the amount of 2-OLR 75 wt% solution added was 0.33 g and no hydrophilic fiber was added. The proportion of 2-OLR added to the CMC aqueous solution was 0.5 parts by weight with respect to 100 parts by weight of CMC.

(Example 12)
Example 12 was prepared in the same manner as Example 1 except that the amount of 2-OLR 75 wt% solution added was 1.33 g and no hydrophilic fiber was added. The ratio of 2-OLR added to the CMC aqueous solution was 2.0 parts by weight with respect to 100 parts by weight of CMC.

(Example 13)
20 g of sucrose fatty acid ester 2.5 wt% solution (Daiichi Kogyo Seiyaku Co., Ltd., DK ester, nonionic surfactant) added instead of 0.67 g 2-OLR 75 wt% solution and hydrophilic fiber Example 13 was made in the same manner as Example 1 except that was not added. The ratio of the sucrose fatty acid ester added to the CMC aqueous solution was 1.0 part by weight with respect to 100 parts by weight of CMC.

(Comparative Example 1)
Comparative Example 1 was prepared in the same manner as Example 1 except that the hydrophilic fiber and surfactant were not added.

(Comparative Example 2)
Comparative Example 2 was prepared in the same manner as Example 1 except that no surfactant was added.

(Comparative Example 3)
Comparative Example 3 was prepared in the same manner as in Example 1 except that no surfactant was added and the amount of pulp fiber charged into the grinder was 20 g. The weight ratio of CMC hydrogel to pulp fiber was 1: 2.

(Comparative Example 4)
In place of 0.67 g of 2-OLR 75 wt% solution, 20 g of sucrose fatty acid ester 2.5 wt% solution (Daiichi Kogyo Seiyaku Co., Ltd., DK ester, nonionic surfactant) was added to the grinder Comparative Example 4 was produced in the same manner as in Example 1 except that the amount of input pulp fiber was 20 g. The ratio of the sucrose fatty acid ester added to the CMC aqueous solution was 1.0 part by weight with respect to 100 parts by weight of CMC. Moreover, the weight ratio of CMC hydrogel and pulp fiber was 1: 2.

(Comparative Example 5)
Comparative Example 5 was prepared in the same manner as in Example 1 except that the amount of 2-OLR 75 wt% solution added was 2.0 g and the amount of pulp fiber charged into the grinder was 20 g. . The ratio of 2-OLR added to the CMC aqueous solution was 3.0 parts by weight with respect to 100 parts by weight of CMC. Moreover, the weight ratio of CMC hydrogel and pulp fiber was 1: 2.

(Comparative Example 6)
Comparative Example 6 was prepared in the same manner as in Example 1 except that no surfactant was added and no hydrophilic fiber was added.

(Comparative Example 7)
Example 7 was prepared in the same manner as Example 1 except that the amount of 2-OLR 75 wt% solution added was 2.00 g and no hydrophilic fiber was added. The ratio of 2-OLR added to the CMC aqueous solution was 3.0 parts by weight with respect to 100 parts by weight of CMC.

(Comparative Example 8)
Instead of 0.67 g 2-OLR 75 wt% solution, 40 g sucrose fatty acid ester 2.5 wt% solution (Daiichi Kogyo Seiyaku, DK ester, nonionic surfactant) was added and hydrophilic fiber Comparative Example 8 was prepared in the same manner as in Example 1 except that was not added. The ratio of the sucrose fatty acid ester added to the CMC aqueous solution was 2.0 parts by weight with respect to 100 parts by weight of CMC.

  In the examples and comparative examples of the first embodiment in which the absorbent material includes hydrophilic fibers, the water absorption rate, the water absorption rate and the water retention rate in 0.9% physiological saline, and the absorption rate, rewetting amount and retention rate in artificial menstrual blood. The test results of blood magnification are shown in Table 1 below.

  In Examples 1 to 5, the absorption rate in 0.9% physiological saline of 27 seconds or less, the water absorption rate in 0.9% physiological saline of 18 times or more, and 0.9% physiological saline of 12 times or more It had a water retention ratio. Examples 1 to 5 further had an absorption rate when 2 mL of artificial menstrual blood of 87 seconds or less was dropped and a blood retention rate of 8 or more times of artificial menstrual blood. In Examples 6 and 8, although absorption of artificial menstrual blood was slightly delayed, Examples 6 and 8 had an absorption rate in 0.9% physiological saline of 27 seconds or less and 0.9% physiological rate of 18 times or more. It had a water absorption rate in saline, a water retention rate in 0.9% physiological saline of 12 times or more, and an absorption rate when 2 mL of artificial menstrual blood of 87 seconds or less was dropped. In Example 7, although the water retention ratio in 0.9% physiological saline was slightly small, Example 7 had an absorption rate in 0.9% physiological saline of 27 seconds or less and 0.9% of 18 times or more. It had a water absorption rate in physiological saline, an absorption rate when 2 mL of artificial menstrual blood of 87 seconds or less was dropped, and a blood retention rate in artificial menstrual blood of 8 times or more.

  In Comparative Examples 1 and 2, 0.9% physiological saline absorption and artificial menstrual blood absorption were slow. In Comparative Examples 3 and 4, the 0.9% physiological saline was absorbed rapidly, but the 0.9% physiological saline water absorption capacity and water retention capacity were small. The retention rate in the artificial menstrual blood of Comparative Example 5 was low.

  By comparing Examples 1 to 8 with Comparative Example 1, the surfactant and the hydrophilic fiber can improve the water absorption rate of 0.9% physiological saline and the absorption rate of menstrual blood in the absorbent material. all right. Moreover, it turned out that the water retention magnification of CMC gel becomes large.

  By comparing Examples 1 to 4 and Comparative Example 2, it was found that the water absorption rate and menstrual blood absorption rate of 0.9% physiological saline in the absorbent material were further improved by the surfactant.

  By comparing Example 2 and Comparative Example 2, the absorption rate and water absorption in 0.9% physiological saline equal to or higher than that of Comparative Example 2 were obtained by comparing Example 2 with Example 2 in an amount of 80% by weight. It was found that the magnification and the water retention ratio, the absorption rate and the blood retention ratio in artificial menstrual blood can be obtained. That is, it was found that by replacing the comparative example 2 with the example 2, an absorber having good characteristics can be produced with a small amount of the absorbent material. Thereby, an absorber can be made thin or the raw material cost of an absorber can be made cheap.

  By comparing Examples 1 to 7 and Comparative Example 5, it was found that the retention rate of artificial menstrual blood may be reduced if the amount of surfactant added is too large.

  From Example 6, the surfactant capable of improving the absorption rate of the absorbent material in 0.9% physiological saline, the water absorption rate and the water retention rate, and the absorption rate and blood retention rate in artificial menstrual blood is a cationic interface. It was found that the above properties of the absorbent material can be improved by a nonionic surfactant without being limited to the active agent.

  From the above experimental results, Examples 1 to 8 and Comparative Examples 1 to 5 will be further discussed below.

(Examples 1-5, 7, 8)
FIG. 5 shows an electron scanning microscope (SEM) photograph of the absorbent material in Example 1. As shown in the SEM photograph in FIG. 5, CMC hydrogel particles obtained by crosslinking by radiation irradiation were entangled with pulp fibers and dried to obtain an absorbent material integrated with the fibers. Moreover, it turned out that the pulp fiber has reached the inside from the outside of the CMC hydrogel particles. The surface area of the absorbent material is increased by entanglement of the CMC hydrogel particles with the hydrophilic fiber, the density of the surface of the CMC hydrogel particles is lowered, and a vacant wall is secured on the surface of the absorbent material. As a result, a route for drawing 0.9% physiological saline or artificial menstrual blood into the absorbent material could be secured. For this reason, it is thought that the water absorption of the absorptive material became quick.

  The surface of the CMC hydrogel particles can be negatively charged due to the hydroxyl groups and carboxyl groups on the surface of the CMC hydrogel particles. Dioleyldimethylammonium chloride is a cationic surfactant and is positively charged, so dioleyldimethylammonium chloride can be strongly adsorbed on the surface of CMC hydrogel particles. As a result, the surface of the CMC hydrogel particles is expected to be hydrophobic. Therefore, the surface of the CMC hydrogel particles can be in a water-repellent state, and the surface of the CMC hydrogel particles can be in a dry state. Thus, it is expected that the penetration of 0.9% physiological saline adhering to the surface of the CMC hydrogel particles or the inside of the CMC hydrogel particles in artificial menstrual blood was promoted.

(Example 6)
Sucrose fatty acid esters are nonionic surfactants. Since the nonionic surfactant is not positively or negatively charged, the sucrose fatty acid ester is adsorbed on the surface of the CMC hydrogel particles by hydrogen bonds between the hydroxyl groups and carboxyl groups on the surface of the CMC hydrogel particles. It is expected that Even when a nonionic surfactant is used, by making the surface of the CMC hydrogel particles water repellent, 0.9% physiological saline attached to the surface of the CMC hydrogel particles or CMC hydrogel in artificial menstrual blood It is expected that penetration into the gel particles was promoted.

(Comparative Example 1)
Since the surface of the CMC hydrogel particles is hydrophilic, the 0.9% physiological saline and artificial menstrual blood held between the CMC hydrogel particles remain held between the CMC hydrogel particles. It is expected that it did not penetrate quickly into the interior of the CMC hydrogel particles. Further, since there is no hydrophilic fiber, it is impossible to secure a route for drawing 0.9% physiological saline or artificial menstrual blood into the absorbent material. And menstrual blood absorption is expected to be slow.

(Comparative Example 2)
Although the comparative example 2 has secured the path | route for drawing 0.9% physiological saline and artificial menstrual blood into the inside of an absorptive material with a hydrophilic fiber, the surface of CMC hydrogel particle | grains is hydrophilic. As such, it is expected that it did not penetrate quickly into the interior of the CMC hydrogel particles. For this reason, the water absorption of 0.9% physiological saline and the absorption of menstrual blood of Comparative Example 2 are expected to be slow.

(Comparative Example 3)
In Comparative Example 3, by increasing the ratio of the hydrophilic fiber, it was possible to secure an extremely large number of routes for drawing 0.9% physiological saline and artificial menstrual blood into the absorbent material. For this reason, it is expected that the water absorption of 0.9% physiological saline of Comparative Example 3 and the absorption of menstrual blood were fast. However, since the surface of the CMC hydrogel particles is hydrophilic, it is expected that the CMC hydrogel particles did not penetrate quickly into the CMC hydrogel particles. For this reason, it is expected that the water absorption ratio and water retention ratio of 0.9% physiological saline of Comparative Example 2 were small.

(Comparative Example 4)
In Comparative Example 4, the effect of the nonionic surfactant on the water absorption capacity and the water retention capacity of 0.9% physiological saline did not appear. This is because of the increased pulp fiber, the hydrogen bond between the nonionic surfactant and the hydroxyl group or carboxyl group on the surface of the CMC hydrogel particles becomes weak, and the surface of the CMC hydrogel particles is sufficiently water repellent. It is expected that it was because it was not.

(Comparative Example 5)
In Comparative Example 5, the retention rate of artificial menstrual blood was small. This is presumably because the surface added to the CMC hydrogel particles became too strong due to an increase in the amount of surfactant added, and the penetration into the inside of the CMC hydrogel particles was less likely to occur. .

  In the examples and comparative examples of the second embodiment in which the absorbent material does not include hydrophilic fibers, the water absorption rate, the water absorption rate and the water retention rate in 0.9% physiological saline, and the absorption rate in artificial menstrual blood, the rewet amount and The test results of the blood retention magnification are shown in Table 2 below.

  Examples 9-11 are the absorption rate in 0.9% physiological saline of 41 seconds or less, the water absorption rate in 0.9% physiological saline of 25 times or more, and 0.9% physiological saline of 20 times or more. It had a water retention ratio. Examples 9 to 11 further had an absorption rate when 2 mL of artificial menstrual blood of 110 seconds or less was dropped and a blood retention rate in artificial menstrual blood of 14 times or more. In Example 12, although the absorption of artificial menstrual blood was slightly delayed, Example 12 was an absorption rate in 0.9% physiological saline of 41 seconds or less and water absorption in 0.9% physiological saline of 25 times or more. It had a magnification, a water retention magnification in 0.9% physiological saline of 20 times or more, and a blood retention magnification in artificial menstrual blood of 14 times or more. In Example 13, although the absorption of artificial menstrual blood was slow and the retention rate of artificial menstrual blood was small, Example 13 had an absorption rate in 0.9% physiological saline of 41 seconds or less and 25 times or more. It had a water absorption rate in 0.9% physiological saline and a water retention rate in 0.9% physiological saline of 20 times or more.

  In Comparative Examples 6 to 8, the absorption of 0.9% physiological saline and artificial menstrual blood was slow. In Comparative Example 6, the water absorption ratio and the water retention ratio of 0.9% physiological saline were further small. In Comparative Examples 7 and 8, the retention rate in artificial menstrual blood was further small.

  By comparing Examples 9 to 13 and Comparative Example 6, it was found that the surfactant accelerated the water absorption and / or absorption of menstrual blood of 0.9% physiological saline in the absorbent material.

  By comparing Example 10 and Comparative Example 6, the rate of absorption in 0.9% physiological saline equal to or greater than that of Comparative Example 6 and the water absorption by Example 10 in the amount of 80% by weight relative to Comparative Example 6 It was found that the magnification and the water retention ratio, the absorption rate and the blood retention ratio in artificial menstrual blood can be obtained. That is, it was found that by replacing the comparative example 6 with the example 10, an absorber having good characteristics can be produced with a small amount of the absorbent material. Thereby, an absorber can be made thin or the raw material cost of an absorber can be made cheap.

  By comparing Examples 9 to 12 and Comparative Example 7, it was found that when too much surfactant was added, the absorption of 0.9% physiological saline and / or artificial menstrual blood was delayed. .

  From Example 13, the surfactant capable of improving the absorption rate, the water absorption capacity, and the water retention capacity of the absorbent material in 0.9% physiological saline is not limited to a cationic surfactant, but a nonionic interface. It has been found that the above properties of the absorbent material can also be improved by an activator. However, it was found from Comparative Example 8 that in the case of a nonionic surfactant, the absorption of 0.9% physiological saline is delayed when the added amount of the surfactant is too large.

  From the above experimental results, Examples 9 to 13 and Comparative Examples 6 to 8 are further discussed below.

(Examples 9 to 12)
FIG. 6 shows an electron scanning microscope (SEM) photograph of the absorbent material in Example 9. As shown in the SEM photograph of FIG. 6, it can be seen that the surface of the CMC hydrogel particles is in a dry state by the surfactant.

  The surface of the CMC hydrogel particles can be negatively charged due to the hydroxyl groups and carboxyl groups on the surface of the CMC hydrogel particles. Dioleyldimethylammonium chloride is a cationic surfactant and is positively charged, so dioleyldimethylammonium chloride can be strongly adsorbed on the surface of CMC hydrogel particles. As a result, the surface of the CMC hydrogel particles is expected to be hydrophobic. Therefore, the surface of the CMC hydrogel particles can be in a water-repellent state, and the surface of the CMC hydrogel particles can be in a dry state. Thus, it is expected that the penetration of 0.9% physiological saline adhering to the surface of the CMC hydrogel particles or the inside of the CMC hydrogel particles in artificial menstrual blood was promoted.

(Example 13)
Sucrose fatty acid esters are nonionic surfactants. Since the nonionic surfactant is not positively or negatively charged, the sucrose fatty acid ester is adsorbed on the surface of the CMC hydrogel particles by hydrogen bonds between the hydroxyl groups and carboxyl groups on the surface of the CMC hydrogel particles. It is expected that Even when a nonionic surfactant is used, the inside of the CMC hydrogel particles in 0.9% physiological saline attached to the surface of the CMC hydrogel particles by making the surface of the CMC hydrogel particles water repellent. It is expected that penetration into

(Comparative Example 6)
Since the surface of the CMC hydrogel particles is hydrophilic, the 0.9% physiological saline and artificial menstrual blood held between the CMC hydrogel particles remain held between the CMC hydrogel particles. It is expected that it did not penetrate quickly into the interior of the CMC hydrogel particles.

(Comparative Example 7 and Comparative Example 8)
In Comparative Example 7 and Comparative Example 8, the effect of the cationic surfactant and the nonionic surfactant on the absorption in 0.9% physiological saline and artificial menstrual blood did not appear. This is presumably because the surface added to the CMC hydrogel particles became too strong due to an increase in the amount of surfactant added, and the penetration into the inside of the CMC hydrogel particles was less likely to occur. .

1 Absorbent article (Sanitary napkin)
DESCRIPTION OF SYMBOLS 2 Surface material 3 Leak-proof sheet 4 Absorber 5 Tissue 10 Crusher 11 Handle 12 Container lid 13 Crushing cutter 14 Set screw 15 Crush tank 16 Main body 21 Nylon mesh 22 Heat seal 23 Upper end 24 Nylon mesh bag

Claims (7)

Cellulose hydrogel particles of cellulose hydrogel prepared by crosslinking alkyl cellulose derivatives;
A surfactant seen including,
The surfactant is present on the surface and inside of the cellulose hydrogel particles,
The absorptive material, wherein the surfactant is a cationic surfactant or a nonionic surfactant .   The absorptive material according to claim 1, further comprising hydrophilic fibers reaching from the outside to the inside of the cellulose hydrogel particles.   The absorbent material according to claim 2, wherein a weight ratio between the cellulose hydrogel particles and the hydrophilic fibers is 1: 1 to 1: 2. The absorbent material according to claim 1, wherein the cationic surfactant is dioleyldimethylammonium chloride. The absorptive material according to any one of claims 1 to 4, comprising 0.5 to 2.0 parts by weight of the surfactant with respect to 100 parts by weight of the cellulose hydrogel particles. The absorbent material according to any one of claims 1 to 5, wherein the alkyl cellulose derivative is carboxyethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, a combination thereof, or a salt thereof. An absorbent material comprising the absorbent material according to any one of claims 1 to 6 for absorbing bodily fluids to be used;
A liquid-permeable sheet that covers one surface of the absorbent body and transmits the body fluid of what is used;
An absorbent article comprising: a liquid-impermeable sheet that covers the other surface of the absorbent body and that does not allow permeation of body fluids.