JP6255215B2 - Absorbent articles - Google Patents

Description

  The present invention relates to an absorbent article having a deodorizing and antibacterial function.

In recent years, there has been a great need for providing antibacterial and deodorizing functions to absorbent articles such as disposable diapers, light incontinence products, and pet sheets. The antibacterial function suppresses the propagation of bacteria such as ammonia-producing bacteria after urination. As such an absorbent article, a configuration is disclosed in which an absorbent core is wrapped with a carrier sheet (carrier sheet) coated with a deodorant and an antibacterial agent, and the whole is wrapped with a top sheet (Patent Document 1).
On the other hand, there is also a fiber used for the absorbent body with a deodorant and an antibacterial agent added. (Patent Document 2)

JP 2004-89322 A JP 05-161671 A

However, when a carrier sheet is produced by applying a chemical solution having a deodorizing and antibacterial function to the base paper, the binding between the pulp fibers is weakened, so that the carrier sheet is twisted or broken, and the use feeling of the absorbent article It may be inferior in durability. Furthermore, there is also a problem that the antibacterial and deodorizing effects are not sustained because the chemical solution is eluted from the carrier sheet by body fluids such as sweat and urine.
On the other hand, when the fiber used for the absorber uses a deodorant and an antibacterial agent, the shape retention of the absorber may be impaired during the use of the absorbent article. Further, in the manufacturing (stacking) process of the absorbent body, there is a problem that a lot of fine fibers are generated and the stacking machine is easily clogged.
In addition, when a powder or liquid deodorant or antibacterial agent is sprayed or sprayed at the time of production (stacking) of the absorber, there is a problem in fixing the drug.
Accordingly, an object of the present invention is to provide an absorbent article having an odor eliminating and antibacterial function, an excellent productivity, and an excellent shape retention after moisture absorption.

In order to solve the above problems, an absorbent article of the present invention is an absorbent article comprising a top sheet, a back sheet, and an absorbent body interposed between the top sheet and the back sheet. The absorber is a metal formed by supporting one or more metal particles selected from the group consisting of Ag, Au, Pt, Pd, Cu and Zn with respect to the oxidized cellulose fiber having a carboxyl group or a carboxylate group on the surface. It consists of a supported cellulose fiber , a superabsorbent resin, and pulp .

The metal loading cellulose fibers may be in the form of fluff pulp.

  According to the present invention, an absorbent article having a deodorizing and antibacterial function in the absorber itself, excellent productivity, and excellent shape retention after moisture absorption can be obtained.

It is a perspective view which shows the external appearance of the absorbent article which concerns on embodiment of this invention. It is sectional drawing which follows the AA line of FIG.

Hereinafter, the absorbent article which concerns on embodiment of this invention is demonstrated.
FIG. 1 is an external view of an absorbent article (pants-type paper diaper) 200 according to the first embodiment of the present invention. The absorbent article 200 includes a water absorbent article main body 20 having water absorption, and an exterior body 100 that holds the water absorbent article main body 20 inside and forms a pants shape.
The exterior body 100 can be made of a nonwoven fabric made of a thermoplastic resin such as polypropylene, polyester, or polyethylene and manufactured by a spunbond or air-through manufacturing method. The exterior body 100 is preferably configured by laminating two or more sheets having at least an exterior sheet and an interior sheet.
The water-absorbent article main body 20 is elongated, the width near the center in the longitudinal direction is slightly narrower, and is disposed between the crotch of the absorbent article 200.

FIG. 2 is a cross-sectional view of the water absorbent article main body 20 taken along the line AA of FIG. The water absorbent article main body 20 includes a liquid permeable hydrophilic surface sheet (top sheet) 2 that forms a body contact side surface (upper surface in FIG. 2), a liquid impermeable back sheet 6, and a surface sheet 2. And an absorbent core 4a, 4b having a highly water-absorbent resin and a fluff. The absorbent cores 4a and 4b are covered with carrier sheets 10a and 10b, respectively. Further, both side portions of the water absorbent article main body portion 20 stand up as a three-dimensional gather 30 composed of a water-repellent side sheet to prevent side leakage of urine and the like.
The absorbent cores 4a and 4b respectively covered with the carrier sheets 10a and 10b correspond to “absorbers” in the claims. In addition, as an absorber, the type which does not use a carrier sheet may be sufficient.
One absorbent body may be provided for each water-absorbent article main body 20 or a plurality of absorbent bodies may be provided.

Since the surface sheet 2 is made of a nonwoven fabric and comes into contact with the wearer's skin, the surface sheet 2 is preferably made of a material that is soft to the touch and does not irritate the skin. As the surface sheet 2, an air-through nonwoven fabric, a point bond nonwoven fabric, a spunbond nonwoven fabric, a spunlace nonwoven fabric, or the like made of synthetic fibers such as polypropylene, polyethylene, or polyester can be used. In particular, an air-through nonwoven fabric with a small liquid return amount is suitable.
The back sheet 6 only needs to be formed from a liquid-impermeable material having a waterproof property so that liquid or the like held in the water-absorbent article main body 20 does not leak into the underwear, such as a breathable polyethylene film. A thin plastic film. Moreover, a moisture-permeable film may be used as the back sheet 6 to reduce stuffiness.

The absorbent cores 4a and 4b are formed by mixing fluff pulp and super absorbent polymer (SAP) particles. Fluff pulp is a metal-supported cellulose formed by supporting one or more metal particles selected from the group consisting of Ag, Au, Pt, Pd, Cu and Zn against oxidized cellulose fibers having a carboxyl group or a carboxylate group on the surface. It is formed by fibrillating fibers. The absorbent cores 4a and 4b may further include a fluff pulp obtained by defibrating wood pulp other than the metal-supporting cellulose fibers, or may include hydrophilic synthetic fibers or polymer fibers that are different from the fluff pulp.
This metal-supporting cellulose fiber has a deodorizing and antibacterial function, and is defibrated and contained in the absorbent body (absorbing cores 4a and 4b) in the form of fluff pulp. Thereby, since metal carrying | support cellulose fiber becomes a bulky structure with many space | gap, a contact with an odor component increases more and a deodorizing and antibacterial effect improve.
The content ratio of the metal-supporting cellulose fibers in the absorber is preferably 5 wt% or more. When the content ratio of the metal-supporting cellulose fiber is less than 5 wt%, the amount of the metal-supporting cellulose fiber in the absorbent body is not sufficient, and the deodorizing and antibacterial functions may be inferior.
This metal-supporting cellulose fiber can be obtained by bringing a metal compound aqueous solution into contact with an oxidized cellulose fiber having a carboxyl group or a carboxylate group introduced on the surface of the cellulose fiber.

The oxidized cellulose fiber can be produced by oxidizing cellulose fiber such as wood pulp using an N-oxyl compound as a catalyst. By this oxidation reaction, the primary hydroxyl group at the C6 position of the glucopyranose ring on the cellulose surface is selectively oxidized, and an oxidized cellulose fiber having a carboxyl group or a carboxylate group on the surface is obtained. The raw material cellulose is preferably natural cellulose. The oxidation reaction is preferably performed in water. Although the density | concentration of the cellulose fiber in reaction is not specifically limited, 5 mass% or less is preferable. The amount of the N-oxyl compound may be about 0.1 to 4 mmol / L with respect to the reaction system. A known cooxidant may be used for the reaction. Examples of the co-oxidant include dihalous acid or a salt thereof. The amount of the co-oxidant is preferably 1 to 40 mol with respect to 1 mol of the N-oxyl compound.
The reaction temperature is preferably 4 to 40 ° C., more preferably room temperature. The pH of the reaction system is preferably 8-11. The degree of oxidation can be appropriately adjusted depending on the reaction time, the amount of the N-oxyl compound, and the like.
The oxidized cellulose fiber thus obtained has acid groups on the surface and almost no acid groups inside. This is presumably because the cellulose fiber is crystalline, so that the oxidant hardly diffuses into the fiber.

The carboxyl group refers to a group represented by —COOH, and the carboxylate group refers to a group represented by —COO—. The counter ion of the carboxylate group is not particularly limited. As will be described later, when metal nanoparticles are formed through ionic bonds with carboxylate groups, these metal ions serve as a counter. The carboxyl group or carboxylate group is also referred to as an “acid group”.
The content of acid groups can be measured by the method disclosed in paragraph 0021 of JP2008-001728A. That is, using a precisely weighed dry cellulose sample, 60 mL of a 0.5 to 1 mass% slurry is prepared, and the pH is adjusted to about 2.5 with a 0.1 mol / L hydrochloric acid aqueous solution. Then, 0.05 mol / L sodium hydroxide aqueous solution is dripped and electrical conductivity measurement is performed. The measurement is continued until the pH is about 11. From the amount (V) of sodium hydroxide consumed until the neutralization step of the weak acid, where the change in electrical conductivity shows a gradual change, the acid group amount X1 is determined using the following equation.
X1 (mmol / g) = V (mL) × 0.05 / mass of cellulose (g)

  The amount of acid groups of the cellulose fiber is preferably 0.2 to 2.2 mmol / g. When the amount of acid groups is less than 0.2 mmol / g, the amount of metal particles present on the surface of the cellulose fiber is not sufficient, and the deodorizing and antibacterial functions may be inferior. When the amount of the acid group exceeds 2.2 mmol / g, the metal particles may aggregate, resulting in poor deodorization and antibacterial functions.

Next, an aqueous solution containing the metal compound is brought into contact with the oxidized cellulose fiber to bond the carboxyl group or carboxylate group (acid group) of the oxidized cellulose fiber with the metal compound. The metal compound should just form the coordinate bond and the hydrogen bond with the carboxyl group. Moreover, the metal ion derived from a metal compound may form the ionic bond with the carboxylate group. In this step, since the metal compound is considered to be bonded to the acid group at the molecular level, metal nanoparticles are not formed.
The metal compound aqueous solution is an aqueous solution of a metal salt or an organometallic compound. Examples of metal salts include complexes (complex ions), halides, nitrates, sulfates, and acetates. The metal salt is preferably water-soluble.
With regard to the method of contacting the metal compound, a cellulose fiber dispersion prepared in advance and a metal compound aqueous solution may be mixed, and a dispersion containing cellulose fibers is applied onto a substrate to form a film, and the metal compound is applied to the film. An aqueous solution may be dropped and impregnated. At this time, the film may remain fixed on the substrate or may be peeled from the substrate.
Although the density | concentration of metal compound aqueous solution is not specifically limited, 10-80 mass parts is preferable with respect to 100 mass parts of cellulose fibers, and 30-60 mass parts is 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, 20-40 degreeC is preferable. In addition, the pH of the liquid at the time of contact is preferably 2.5 to 13.

Next, metal particles are formed by reducing the metal compound bound to the oxidized cellulose fiber obtained as described above. Although this mechanism is not clear, it is guessed as follows. The metal compound or the ion derived from the metal compound that has been bonded to the acid group by the reduction reaction is reduced to a metal. At this time, the produced metal is supported on the surface of the oxidized cellulose fiber. Similarly, the generated neighboring metals are integrated with each other, so that the particles grow to form nanoparticles. On the other hand, a metal compound or the like that exists in the vicinity of the cellulose fiber but does not bind to the acid group is also reduced to generate a metal. This metal quickly integrates with the metal on the surface of the cellulose fiber to form metal particles.
The reduction reaction may be performed by a known method, but it is preferable to perform the reduction reaction so as not to cleave the bond between the metal compound and the acid group while reducing the metal compound. Examples of such a reduction method include a gas phase reduction method using hydrogen and a liquid phase reduction method using a reducing agent such as an aqueous sodium borohydride solution. Conditions such as time and temperature in the gas phase reduction are appropriately adjusted. For example, the reaction may be performed at 50 to 60 ° C for about 1 to 3 hours. The gas phase reduction reaction is preferably performed in a state where the oxidized cellulose fiber does not contain water or a solvent. In the reduction reaction, the film may remain fixed on the substrate or may be peeled from the substrate. In the case of liquid phase reduction, a film can be obtained from the above dispersion and subjected to a reduction reaction with or without drying. Further, the dispersion can be subjected to a liquid phase reduction reaction without drying. The reaction temperature in the liquid phase reduction is preferably 4 to 40 ° C., more preferably room temperature.

The metal particles are supported on the surface of the cellulose fiber by using an acid group present on the surface of the cellulose fiber as a contact. That is, the metal particles are fixed to the cellulose fiber surface via acid groups present on the cellulose fiber surface. The chemical bond for immobilization is preferably a coordination bond, a hydrogen bond, or an ionic bond. The bonding state can be analyzed by X-ray photoelectron spectroscopy or infrared spectroscopy.
The average particle diameter of the metal particles is determined from a transmission electron microscope image or X-ray diffraction. In the present invention, the average particle diameter of the metal particles is preferably in the range of 1 to 50 nm when determined from a transmission electron microscope image. Specifically, the average particle diameter is obtained by preparing a transmission electron microscope image of cellulose fibers, obtaining the equivalent circle diameter of primary particles of a plurality of metal particles from the image, and averaging these values.
By using at least one selected from the group consisting of Ag and Cu as the metal particles, an antibacterial function is imparted. On the other hand, the metal particles do not bind to all of the acid groups of the cellulose fiber, and the remaining acid groups neutralize ammonia, which is a odorous component, thereby exhibiting a deodorizing function.

It goes without saying that the present invention is not limited to the above-described embodiments, and extends to various modifications and equivalents included in the spirit and scope of the present invention.
An absorptive article is not restricted to the above-mentioned underpants type paper diaper, for example, it is a long and slender piece like a sanitary napkin, and the type which hits a local part may be sufficient. In the above-described embodiment, the liquid-permeable surface sheet 2 covers only one surface (body contact side surface) of the absorbent core 4a. However, both surfaces of the absorbent core are covered with the liquid-permeable surface sheet, and the absorbent article. It may be possible to absorb urine and the like from both the front and back surfaces.
Moreover, the absorber should just contain the metal carrying | support cellulose fiber, and the structure of an absorber and the containing form of a metal carrying cellulose fiber are not limited above.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these examples of course.

16 g of pulp fibers (cellulose) made of NBKP were prepared and dispersed in 1600 g of water. To this dispersion, 0.2 g of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and 2 g of sodium hypochlorite as a co-oxidant were added, stirred at room temperature for 2 hours, and oxidized. Reaction was performed and the dispersion liquid of the oxidized cellulose fiber (TEMPO oxidized cellulose fiber) was obtained. This TEMPO oxidized cellulose fiber has a carboxyl group or a carboxylate group on its surface. The acid group amount of the TEMPO oxidized cellulose fiber before supporting the metal particles was 1.6 mmol / g.
The TEMPO oxidized cellulose fiber obtained by the above operation is paper-made with a round hand machine so that the basis weight is 18 g / m 2, dried with a cylinder dryer (105 ° C.), and round with a diameter of about 16 cm. A mold sheet was prepared.
Next, this sheet was impregnated with 200 ppm of an Ag compound aqueous solution, and filter paper was piled up to remove an excess aqueous solution, followed by drying for 15 minutes by a blow dryer at 50 ° C. Thereafter, the sheet impregnated and dried with the Ag compound aqueous solution is impregnated with 200 ppm of the reducing agent solution, the filter paper is overlaid to remove the excess aqueous solution, and dried with an air dryer at 50 ° C. for 15 minutes to form oxidized cellulose fibers in the sheet. Ag nanoparticles were supported. The amount of metal particles supported on the oxidized cellulose fiber was 5.75 mg / g. In Example 3, Cu was used instead of Ag.

Next, this sheet was defibrated by a defibrator to obtain fluff pulp made of TEMPO oxidized cellulose fibers. The fluff pulp, the superabsorbent resin (SAP), and fluff pulp formed by defibrating general pulp (NBKP) were blended at a blending ratio shown in Table 1 to prepare an absorbent body. As Comparative Example 1, an absorbent body was similarly prepared using fluff pulp obtained by defibrating a zeolite-supported cellulose fiber with 10 wt% Ag particles supported thereon. In addition, the carrier sheet (basis weight 20g / m < ² >) was laminated | stacked on the upper and lower sides of the absorber.

<Deodorizing effect>
Saturated gas of aqueous ammonia solution (ammonia water 2mL: water 2mL) was inserted into a gas bag with a cock containing a test piece of 5cm x 5cm absorber with a 1.2mL syringe, and 1.5L of air was filled with an air pump. . 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 the 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 less than 1/3 of the initial value ○: Normal Residual concentration is 1/2 to 3/1 of the initial value
×: Poor residual concentration is 1/2 or more of initial <antibacterial property>
It was evaluated by a halo test. An agar medium containing E. coli was prepared, and a small piece of the absorber was placed thereon. After culturing at 37 ° C. for 17 hours, the presence or absence of the “growth inhibition zone” of the test bacteria formed around the sample was confirmed.
○: Growth inhibition zone is recognized and has antibacterial properties.
X: No growth inhibition zone was observed and no antibacterial activity was observed.

<Operability>
The absorbent body was produced (operated) for 2 hours continuously with a fiber pile, and it was confirmed whether or not the wire in the rotating drum was clogged with fine fibers.
○: Occurrence of clogging is not recognized and there is no operational problem.
X: That was confirmed.
<Shape retention>
A 10 cm x 10 cm absorbent body is sandwiched between a top sheet (air-through nonwoven fabric 25 g / m ² ) and a back sheet, 150 ml of physiological saline is poured from the top of the top sheet, and a weight of 1,360 g (diameter 50 mmφ) is 1 minute later. The state of the absorber when the was placed in the center of the top sheet was observed. If the shape retention is ○, there is no practical problem.
◯: No fiber and superabsorbent polymer are removed from the side of the absorber. ×: Fiber and superabsorbent polymer are detached from the side of the absorber.
The obtained results are shown in Table 1.

As is apparent from Table 1, in each of the examples, the deodorizing and antibacterial functions were excellent, the operability was good, and the shape retention of the absorbent after moisture absorption was also good.
On the other hand, in the case of Comparative Example 1, the operability was inferior and the shape retention was also inferior.

2 Top sheet 4a, 4b Absorber (absorption core)
6 Back sheet 200 Water-absorbent article

Claims (2)

An absorbent article comprising a top sheet, a back sheet, and an absorbent body interposed between the top sheet and the back sheet,
The absorber is a metal-supported material in which one or more metal particles selected from the group consisting of Ag, Au, Pt, Pd, Cu and Zn are supported on an oxidized cellulose fiber having a carboxyl group or a carboxylate group on the surface. An absorbent article comprising cellulose fiber , a highly water-absorbent resin, and pulp . The metal loading cellulosic fibers absorbent article to claim 1 wherein such a form of fluff pulp.

Images