ABSORBENT ARTICLE

Abstract

The present invention provides an absorbent article that suppresses acetaldehyde odor. This absorbent article is obtained by layering at least a liquid-permeable sheet, an absorbent body containing a water-absorbing resin, and a liquid-impermeable sheet in this order, wherein at least some of a hydrazide compound is present on the liquid-permeable sheet side with respect to the absorbent body.

Claims

1. An absorbent article comprising at least: a liquid-permeable sheet; an absorber containing a water-absorbing resin; and a liquid-impermeable sheet, the absorbent article being obtained by laminating the liquid-permeable sheet, the absorber, and the liquid-impermeable sheet in this order, wherein at least some of a hydrazide compound is present on a side where the liquid-permeable sheet is present, the side being based on a position of the absorber.

2. The absorbent article according to claim 1, wherein the hydrazide compound is present on a surface of the liquid-permeable sheet and/or contained in the liquid-permeable sheet.

3. The absorbent article according to claim 1, wherein the hydrazide compound is present between the liquid-permeable sheet and the absorber.

4. The absorbent article according to claim 2, wherein the hydrazide compound is present between the liquid-permeable sheet and the absorber.

Description

EXAMPLES

[0084] Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. However, the present invention is not limited to the examples.

[0085] The absorbent articles obtained in the following examples and comparative examples were evaluated in the following various tests. Hereinafter, each evaluation test method will be described.

<Median Particle Diameter>

[0086] The measurement was performed in an environment at a temperature of 25±2° C. and a humidity of 50±10%. JIS standard sieves were combined in the following order from the top: a sieve with an opening of 850 μm, a sieve with an opening of 600 μm, a sieve with an opening of 500 μm, a sieve with an opening of 425 μm, a sieve with an opening of 300 μm, a sieve with an opening of 250 μm, a sieve with an opening of 150 μm, and a receptacle.

[0087] The water-absorbing resin, 50 g, was placed on the uppermost sieve of the combined sieves, and shaken for 10 minutes using a rotating and tapping shaker to perform classification. After classification, the mass of the water-absorbing resin retained on each sieve was calculated as a mass percentage with respect to the total amount, and the particle size distribution was determined. With respect to this particle size distribution, by cumulation of the mass percentages of the retained on the sieves in descending order of particle diameter, the relationship between the opening of the sieve and the cumulative value of the mass percentage of the water-absorbing resin retained on the sieve was plotted on a logarithmic probability paper. The plotted points on the probability paper were connected with a straight line, and a particle diameter corresponding to a cumulative mass percentage of 50 mass % was defined as a median particle diameter.

<Acetaldehyde Odor Suppression Test>

[0088] The acetaldehyde odor suppression test was performed in an environment of 25° C. ±2° C. A test absorbent article to be described later was placed in a plastic petri dish having an inner diameter of 10 cm and a height of 1.5 cm, 0.6 g of a 0.1% aqueous acetaldehyde solution was added to 29.4 g of ion-exchanged water, and the solution was stirred for 10 seconds. The entire amount of the solution was quickly put into the central portion of the absorbent article. The petri dish containing the absorbent article was placed in a 2L-Tedlar bag (with one port and a cap) equipped with a three-way cock with a silicone tube having an inner diameter of 5 mm interposed therebetween, and the bag was hermetically sealed by heat sealing. Then, the glass syringe (constant humidity glass syringe, 200 mL, manufactured by Tsuji Seisakusho Co., Ltd.) was connected to a three-way cock, and the entire amount of air in the Tedlar bag was withdrawn. Thereafter, 900 mL of air was enclosed using the glass syringe described above. After 60 minutes from the completion of enclosing of the acetaldehyde-containing gas, the three-way cock was removed from the Tedlar bag, a gas detection tube with the ends open (manufactured by GASTEC Corporation, detection tube: acetaldehyde 92L) was attached, and the acetaldehyde concentration in the Tedlar bag gas phase was measured. The measurement results are shown in Table 1.

<Production of Water-Absorbing Resin>

Production Example 1

[0089] A 2-L round-bottom cylindrical separable flask having an inner diameter of 11 cm and equipped with a reflux condenser, a dropping funnel, a nitrogen gas inlet tube, and a stirring blade having two stages of 4-inclined paddle blades having a blade diameter of 5 cm as a stirrer was prepared. To this flask, 293 g of n-heptane as a hydrocarbon dispersion medium and 0.736 g of a maleic anhydride-modified ethylene-propylene copolymer (Mitsui Chemicals, Inc., Hi-WAX 1105A) as a polymeric dispersant were added, the temperature was raised to 80° C. with stirring to dissolve the dispersant, and then the contents were cooled to 50° C.

[0090] On the other hand, in a beaker having an internal volume of 300 mL, 92.0 g (1.03 mol) of an 80.5 mass % aqueous acrylic acid solution as a water-soluble ethylenically unsaturated monomer was placed, 147.7 g of a 20.9 mass % aqueous sodium hydroxide solution was added dropwise while cooling with ice water to perform neutralization of 75 mol %, and then 0.092 g (Sumitomo Seika Chemicals Co., Ltd., HECAW-15F) of hydroxylethyl cellulose as a thickener, 0.0736 g (0.272 mmol) of potassium persulfate as a water-soluble radical polymerization agent, and 0.010 g (0.057 mmol) of ethylene glycol diglycidyl ether as an internal-crosslinking agent were added thereto and dissolved, thereby preparing a first-stage aqueous monomer solution.

[0091] Then, the aqueous monomer solution prepared above was added to the separable flask and stirred for 10 minutes, after which a surfactant solution obtained by heating and dissolving 0.736 g of a sucrose stearate having an HLB of 3 (Mitsubishi Chemical Foods Corporation, Ryoto Sugar Ester S-370) as a surfactant in 6.62 g of n-heptane in a 20 mL-vial was further added. While stirring at a stirrer rotational speed of 550 rpm, the inside of the system was sufficiently purged with nitrogen, and then the flask was immersed in a water bath at 70° C. for 60 minutes to obtain a first-stage polymerization slurry solution.

[0092] On the other hand, in another beaker having an internal volume of 500 mL, 128.8 g (1.43 mol) of an 80.5 mass % aqueous acrylic acid solution as a water-soluble ethylenically unsaturated monomer was placed, 159.0 g of a 27 mass % aqueous sodium hydroxide solution was added dropwise while cooling with ice water to perform neutralization of 75 mol %, and then 0.103 g (0.381 mmol) of potassium persulfate as a water-soluble radical polymerization initiator and 0.0116 g (0.067 mmol) of ethylene glycol diglycidyl ether as an internal-crosslinking agent were added thereto and dissolved, thereby preparing a second-stage aqueous monomer solution.

[0093] While stirring at a stirrer rotational speed of 1000 rpm, the inside of the separable flask system was cooled to 25° C. Then the whole amount of the second-stage aqueous monomer solution was added to the first-stage polymerization slurry. After the inside of the system was purged with nitrogen for 30 minutes, the flask was immersed again in a water bath at 70° C. for 60 minutes to obtain a second-stage hydrous gel polymer.

[0094] To the hydrous gel polymer after the second-stage polymerization, 0.589 g of a 45 mass % aqueous pentasodium diethylenetriaminepentaacetate solution was added under stirring. Thereafter, the flask was immersed in an oil bath set at 125° C., and 257.7 g of water was removed to the outside of the system while refluxing n-heptane by azeotropic distillation of n-heptane and water. Then, 4.42 g (0.507 mmol) of a 2 mass % aqueous solution of ethylene glycol diglycidyl ether as a post-crosslinking agent was added to the flask, and the contents were held at 83° C. for 2 hours.

[0095] Thereafter, the contents were dried by evaporation of n-heptane at 125° C. to obtain a particulate crosslinked polymer (dry product). This particulate crosslinked polymer was passed through a sieve with an opening of 850 μm, and 0.1 mass % of amorphous silica (Oriental Silicas Corporation, TOKUSIL NP-S) with respect to the mass of the particulate crosslinked polymer was mixed with the particulate crosslinked polymer to obtain 228.0 g of a particulate water-absorbing resin containing amorphous silica. The median particle diameter of the particulate water-absorbing resin was 352 μm.

<Production of Test Absorbent Article>

Example 1

[0096] An absorbent article was prepared so as to have the laminated configuration of Table 1. First, on a polyethylene film (6 cm×6 cm, 40 g/m.sup.2), a piece of tissue (22 g/m.sup.2) of the same size and 2 sheets of sheet-like molded pulp (disintegrated pulp, 139 g/m.sup.2) of the same size were placed, and 1.0 g (corresponding to 278 g/m.sup.2) of the water-absorbing resin produced in Production Example 1 was sprayed. Furthermore, two sheets of the sheet-like molded pulp described above and one piece of tissue of the same size were placed. Thereonto, 0.0007 g (corresponding to 0.194 g/m.sup.2) of malonic acid dihydrazide as a hydrazide compound was sprayed. One polyethylene-polypropylene air-through type porous liquid-permeable sheet (16.0 g/m.sup.2) of the same size, as a liquid-permeable sheet (top sheet) was placed thereon, and the resultant was compressed from the top with a weight of 5 kg (10 cm×10 cm) for 30 seconds to prepare a test absorbent article.

Example 2

[0097] An absorbent article was prepared so as to have the laminated configuration of Table 1. First, on a polyethylene film (6 cm×6 cm, 40 g/m.sup.2), a piece of tissue (6 cm×6 cm, 22 g/m.sup.2) of the same size was placed, and 2 sheets of sheet-like molded pulp (disintegrated pulp, 139 g/m.sup.2) of the same size were placed thereon, and 1.0 g (corresponding to 278 g/m.sup.2) of the water-absorbing resin produced in Production Example 1 was sprayed. Furthermore, two sheets of the sheet-like molded pulp described above were placed. Thereonto, 0.0007 g (corresponding to 0.194 g/m.sup.2) of malonic acid dihydrazide was sprayed. One piece of tissue of the same size and one polyethylene-polypropylene air-through type porous liquid-permeable sheet (16.0 g/m.sup.2) of the same size, as a liquid-permeable sheet (top sheet) were placed thereon, and the resultant was compressed from the top with a weight of 5 kg (10 cm×10 cm) for 30 seconds to prepare a test absorbent article.

Comparative Example 1

[0098] An absorbent article was prepared so as to have the laminated configuration of Table 1. First, on a polyethylene film (6 cm×6 cm, 40 g/m.sup.2), a piece of tissue (6 cm×6 cm, 22 g/m.sup.2) of the same size was placed, 0.0007 g (corresponding to 0.194 g/m.sup.2) of malonic acid dihydrazide was sprayed thereonto, 2 sheets of sheet-like molded pulp (disintegrated pulp, 139 g/m.sup.2) of the same size were placed thereon, and 1.0 g (corresponding to 278 g/m.sup.2) of the water-absorbing resin produced in Production Example 1 was sprayed. Furthermore, two sheets of the sheet-like molded pulp described above, one piece of tissue of the same size, and one polyethylene-polypropylene air-through type porous liquid-permeable sheet (16.0 g/m.sup.2) of the same size, as a liquid-permeable sheet (top sheet) were placed thereon, and then the resultant was compressed from the top with a weight of 5 kg (10 cm×10 cm) for 30 seconds to prepare a test absorbent article.

Example 3

[0099] A test absorbent article was prepared by performing the same operations as in Example 1 except that in Example 1, the amount of malonic dihydrazide to be sprayed was changed to 0.0004 g (corresponding to 0.111 g/m.sup.2).

Example 4

[0100] A test absorbent article was prepared by performing the same operations as in Example 2 except that in Example 2, the amount of malonic dihydrazide to be sprayed was changed to 0.0004 g (corresponding to 0.111 g/m.sup.2).

Comparative Example 2

[0101] A test absorbent article was prepared by performing the same operations as in Comparative Example 1 except that in Comparative Example 1, the amount of malonic dihydrazide to be sprayed was changed to 0.0004 g (corresponding to 0.111 g/m.sup.2).

Comparative Example 3

[0102] A test absorbent article was prepared by performing the same operations as in Example 1 except that in Example 1, the malonic dihydrazide was not added.

TABLE-US-00001 TABLE 1 Test absorbent article Present Acetaldehyde amount of concentration hydrazide after odor Laminated configuration compound suppression test (liquid fed side .fwdarw. outside) (g/m.sup.2) (ppm) Example 1 Liquid-permeable sheet/hydrazide 0.194 4 compound/tissue/absorber (pulp/water-absorbing resin/pulp)/tissue/liquid-impermeable sheet Example 2 Liquid-permeable sheet/tissue/hydrazide 0.194 12 compound/absorber (pulp/water-absorbing resin/pulp)/tissue/liquid-impermeable sheet Comparative Liquid-permeable sheet/tissue/absorber 0.194 14 example 1 (pulp/water-absorbing resin/pulp)/hydrazide compound/tissue/liquid-impermeable sheet Example 3 Liquid-permeable sheet/hydrazide 0.111 7 compound/tissue/absorber (pulp water-absorbing resin/pulp)/tissue/liquid-impermeable sheet Example 4 Liquid-permeable sheet/tissue/hydrazide 0.111 9 compound/absorber (pulp/water-absorbing resin/pulp)/tissue/liquid-impermeable sheet Comparative Liquid-permeable sheet/tissue/absorber 0.111 15 example 2 (pulp/water-absorbing resin/pulp)/hydrazide compound/tissue/liquid-impermeable sheet Comparative Liquid-permeable sheet/tissue/absorber 0 15 example 3 (pulp/water-absorbing resin/pulp)/tissue/liquid- impermeable sheet