JP6234046B2 - Absorbent articles - Google Patents

Description

  The present invention relates to an absorbent article.

  As absorbents for absorbent articles, hydrophilic fibers (for example, pulp) and synthetic resin fibers that have been crimped into a coil shape (for example, a latently crimped eccentric core-sheath composite fiber are crimped into a coil shape by heating. And an absorbent body further containing superabsorbent polymer particles as necessary (Patent Document 1), a liquid absorbent mixture comprising superabsorbent polymer particles and fluff pulp, and a thermoplastic resin. (For example, a core-sheath type composite fiber having a thermoplastic resin selected from polyethylene and an ethylene copolymer as a sheath and a thermoplastic resin having a melting point higher than that of the thermoplastic resin forming the sheath) There is known an absorbent body (Patent Document 2) containing a non-woven fabric.

  On the other hand, as a heat-adhesive conjugate fiber for airlaid nonwoven fabric, a modified polyolefin graft-polymerized with a vinyl monomer containing an unsaturated carboxylic acid or unsaturated carboxylic acid anhydride is used as a sheath component, and a resin having a higher melting point than the modified polyolefin is used as a core. A core-sheath type composite fiber as a component is known (Patent Documents 3 and 4).

  Further, the plurality of absorption parts are separated from each other and joined to the base sheet via a fixing part, and the fixing part is included in the area of the absorption part in plan view, and the plurality of absorption parts are in fluid communication with each other. An absorber arranged in a state that can be converted is known (Patent Document 5).

JP 2004-159786 A JP 2008-142424 A Japanese Patent No. 4221849 JP 2004-270041 A JP 2010-268919 A

  The absorbers described in Patent Documents 1 and 2 are intended to prevent loss of shape, improve cushioning, and the like, and have a novel absorber that has sufficient absorbency and retains sufficient strength even after absorption. It was sought after.

  On the other hand, the core-sheath type composite fibers described in Patent Documents 3 and 4 are known to have good adhesiveness with cellulosic fibers, but their useability as a constituent component of the absorber is known. There wasn't.

  In addition, the absorbent body described in Patent Document 5 has insufficient strength when wet, which may cause a decrease in absorbability, kinking of the absorbent body, and the like.

  An object of the present invention is to provide an absorbent article that follows the movement of the user and is excellent in absorbency both when dry and when wet.

  As a result of intensive studies to solve the above problems, the present inventors have found that the liquid permeable layer, the liquid impermeable layer, and the absorption provided between the liquid permeable layer and the liquid impermeable layer. An absorbent article comprising a body, wherein the absorbent includes an absorbent core composed of a plurality of absorbent core portions, and a base sheet for fixing the plurality of absorbent core portions, The core parts are fixed to the base sheet at a distance from each other, and the absorbent core includes a cellulosic water-absorbing fiber and an unsaturated carboxylic acid, an unsaturated carboxylic acid anhydride, or a mixture thereof as monomer components. An absorbent article comprising a thermoplastic resin fiber and characterized in that the thermoplastic resin fiber is connected to the water-absorbing fiber and / or another thermoplastic resin fiber has been found.

  The absorbent article of the present invention follows the movement of the user both when dry and when wet, and has excellent absorbency.

FIG. 1 is a partially broken plan view of a sanitary napkin according to a first embodiment of the present invention. FIG. 2 is an end view taken along line II-II in FIG. FIG. 3 is a plan view of a sanitary napkin according to a third embodiment of the present invention. FIG. 4 is a plan view of a sanitary napkin according to a fourth embodiment of the present invention. FIG. 5 is a plan view of a sanitary napkin according to a fifth embodiment of the present invention. FIG. 6 is an end view showing an example in which the absorbent core portion 9 has a plurality of flange portions 41 and groove portions 42 on the surface on the top sheet 2 side. FIG. 7 is an end view showing an example in which the absorbent core portion 9 has a plurality of flange portions 43 and groove portions 44 on the surface on the backsheet 3 side. FIG. 8 is a diagram illustrating a manufacturing process of the absorbent body and the absorbent article. FIG. 9 is a partial development view of the suction drum 151. FIG. 10 is a diagram showing an SJ belt press used in the embodiment.

Hereinafter, the absorbent article of the present invention will be described.
The absorbent article of the present invention includes an absorbent core composed of a plurality of absorbent core portions, and a base sheet for fixing the plurality of absorbent core portions, and the plurality of absorbent core portions are separated from each other. It is fixed to the base sheet.

  In the absorbent article of the present invention, the absorbent core is composed of a cellulosic water absorbent fiber (hereinafter sometimes abbreviated as “water absorbent fiber”), an unsaturated carboxylic acid, an unsaturated carboxylic acid anhydride, or a mixture thereof. It contains thermoplastic resin fibers contained as components (hereinafter may be abbreviated as “thermoplastic resin fibers”).

In the absorbent core of the absorbent article of the present invention, thermoplastic resin fibers are connected to water-absorbing fibers and / or other thermoplastic resin fibers.
The connection improves the strength of the absorbent core (particularly, the strength when wet after liquid absorption). Examples of connection include, for example, (i) thermal fusion between thermoplastic resin fibers, (ii) thermal fusion between thermoplastic resin fibers and water absorbent fibers, (iii) between thermoplastic resin fibers, and water absorbent fibers. And hydrogen bonds between thermoplastic resin fibers and water-absorbing fibers. In addition, when an absorption core contains other fibers other than a thermoplastic resin fiber and a water absorbing fiber, a thermoplastic resin fiber and / or a water absorbing fiber may be connected with the other fiber.

  In the absorbent core of the absorbent article of the present invention, the mass ratio of water absorbent fibers to thermoplastic resin fibers is preferably from about 1.0 to about 9.0, and from about 1.5 to about 4.0. It is more preferable that When the mass ratio exceeds about 9.0, the strength of the absorbent core (particularly, strength when wet after liquid absorption) tends to decrease. If the mass ratio is less than about 1.0, the liquid absorbability of the absorbent core tends to be reduced.

In the present invention, the absorbent core preferably has a density of about 0.06 to about 0.14 g / cm ³ . This is because, in the absorbent article of the present invention, the absorbent core achieves both absorbency and strength after absorption.

The density of the absorbent core is calculated based on the following formula.
D (g / cm ³ ) = B (g / m ² ) / T (mm) × 10 ⁻³
[In formula, D, B, and T represent the density, basic weight, and thickness of an absorption core, respectively. ]

The basis weight (g / m ² ) of the absorbent core is measured as follows.
When the absorbent core part has a size of 30 mm x 30 mm or more, three test pieces of 30 mm x 30 mm are cut out from the absorbent core part and tested in standard conditions (temperature 23 ± 2 ° C, relative humidity 50 ± 5%). The mass of the piece was measured with a direct balance (for example, electronic balance HF-300 manufactured by Kensei Kogyo Co., Ltd.), and the mass per unit area of the absorbent core calculated from the average of the three measured values (g / m ² ) Is the basis weight of the absorbent core.

When the absorbent core portion has a size of less than 30 mm × 30 mm, prepare a plurality of absorbent core portions so that the total area exceeds 900 mm ² , measure their total area and total mass, and measure the basis weight Is calculated.
Regarding the measurement of the basis weight of the absorbent core, the measurement conditions described in ISO 9073-1 or JIS L 1913 6.2 are adopted for the measurement conditions not particularly specified above.

The measurement of the thickness (mm) of an absorption core is implemented as follows.
In a standard state (temperature 23 ± 2 ° C., relative humidity 50 ± 5%) by a thickness gauge (for example, FS-60DS, manufactured by Daiei Scientific Instruments Co., Ltd., measurement surface 44 mm (diameter), measurement pressure 3 g / cm ² ). Five parts with different absorption cores (when using a thickness gauge FS-60DS, the diameter of each part is 44 mm) were pressurized at a constant pressure of 3 g / cm ² , and the thickness after 10 seconds of pressurization at each part was measured. The average value of the two measured values is taken as the thickness of the absorbent core.

  In the present invention, the density of the absorbent core can be adjusted to a desired range by, for example, increasing the density of the mixed material containing water-absorbing fibers and thermoplastic resin fibers. In order to maintain the density of the absorbent core within a certain range, it is necessary to suppress the elastic recovery of the fibers and maintain the bulk of the absorbent core within a certain range. In this regard, in the absorbent core in the absorbent article of the present invention, hydrogen bonds (for example, hydrogen bonds formed between water-absorbing fibers, between thermoplastic resin fibers, between water-absorbing fibers and thermoplastic resin fibers, etc.) are absorbed. Contributes to maintaining the bulk of the core. In addition, since hydrogen bonds are cut by the liquid absorbed by the absorbent core, the swelling of the absorbent material (absorbent fiber as an essential component, highly absorbent material as an optional component) contained in the absorbent core is inhibited. do not do.

  In the present invention, the absorbent core is preferably obtained by injecting high-pressure steam into a mixed material containing cellulosic water-absorbing fibers and thermoplastic resin fibers to increase the density. The density of the absorbent core is adjusted to a desired range by densification using high-pressure steam injection. When high-pressure water vapor is injected into the mixed material, the water vapor penetrates into the mixed material and forms hydrogen bonds (for example, between water-absorbing fibers, between thermoplastic resin fibers, between water-absorbing fibers and thermoplastic resin fibers, etc.). (Hydrogen bonds) are broken, and the mixed material is softened. Therefore, the pressure required for densification decreases, and the density of the softened mixed material can be easily adjusted. When the density-adjusted mixed material is dried and hydrogen bonds are reformed, elastic recovery (increase in bulk) of the fibers is suppressed, and the density of the absorbent core is maintained within a certain range.

  Densification using high-pressure steam injection is particularly suitable when an unsaturated carboxylic acid anhydride (for example, maleic anhydride or a derivative thereof) is contained as a monomer component in the thermoplastic resin fiber. When the unsaturated carboxylic acid anhydride group contained in the thermoplastic fiber reacts with water vapor to form an unsaturated carboxylic acid, the number of oxygen atoms capable of forming hydrogen bonds increases, so the elasticity of the densified fiber is increased. Recovery (increase in bulk) is effectively suppressed.

  In densification using high-pressure steam injection, the temperature of the high-pressure steam is preferably less than the melting point of the thermoplastic resin fiber. This is because the density of the absorbent core can be easily adjusted.

In the present invention, the absorbent core preferably has a basis weight of about 40 to about 900 g / m ^2. When the basis weight is less than about 40 g / m ² , the amount of fibers is small, and density adjustment by jetting high-pressure steam may be difficult, and when the basis weight exceeds about 900 g / m ² , the amount of fibers In many cases, internal penetration of water vapor may be difficult.
Further, if the basis weight is less than about 40 g / m ² , the strength of the absorbent core (particularly, strength when wet after liquid absorption) tends to be reduced, and the basis weight exceeds about 900 g / m ² . And the intensity | strength (especially strength at the time of drying) of an absorption core is high, and there exists a tendency for it to be inferior to a feeling of wear.

In the present invention, the base sheet preferably has a maximum load elongation of about 10 to about 100%, more preferably about 20 to about 90%, and even more preferably about 30 to about 80%. When the elongation rate at the maximum load is less than about 10%, it becomes difficult for the absorbent body to bend from the folding axis, and as a result, the absorbent body conforms to the three-dimensional shape of the user's body, walking, etc. It becomes difficult to follow the movement of the user during exercise. When the elongation rate at the maximum load exceeds about 100%, the base sheet is likely to be broken and the absorbent body may be called.
Hereinafter, the maximum load elongation rate may be simply referred to as the elongation rate.

The base sheet preferably has an elongation rate in the above range in the width direction of the absorbent article. This is because the absorbent article has a large degree of deformation in the width direction.
Moreover, a base material sheet may have the elongation rate of the said range in the longitudinal direction of an absorbent article.

The elongation at maximum load is measured as follows. In addition, the matter which is not described follows the description of "6.3 tensile strength and elongation rate" of JIS L 1913: 2010, a general nonwoven fabric test method.
(1) A tensile tester is prepared in a constant temperature and humidity chamber at 20 ° C. and 60% RH.
Note that AG-1kNI manufactured by Shimadzu Corporation is used as the tensile tester.
(2) The sample is cut into sample pieces having a size of 150 mm × 25 mm.
In addition, a long side (150 mm) direction is a direction which measures an elongation rate.

(3) The sample piece is attached to the chuck with an initial gripping interval L ₀ (mm), and tension (load) is applied at a pulling speed of 100 mm / min until the sample piece is cut or plastically deformed.
The grip interval L ₀ is 100 mm.
(4) The grip interval at the point with the maximum load: L ₁ (mm) is read, and the elongation percentage (%) is measured according to the following formula.
Elongation rate (%) = 100 × [L ₁ (mm) −L ₀ (mm)] / L ₀ (mm)
(5) Repeat the measurement a total of 5 times and adopt the average value.

  In this test, the plastic deformation means that after showing the maximum load, it continues to expand with a smaller load. When the described sheet is plastically deformed, the function as a base sheet is deteriorated. Therefore, in this test, the elongation rate at the maximum load is an object of evaluation.

In the measurement, if a foreign material such as an adhesive adheres to the base sheet, the base sheet is immersed in a solvent, the adhesive is dissolved, and the base sheet is dried with a dryer or the like. Measure after.
In addition, as said solvent, although a foreign material is melt | dissolved, if it does not melt | dissolve a base material sheet, it can use without a restriction | limiting in particular, For example, aromatic solvents, such as toluene, are mentioned.

In the present invention, the base sheet is not particularly limited as long as it can fix a plurality of absorbent core portions, and the liquid-impermeable layer side of the absorbent core, the liquid-permeable layer side of the absorbent core, or It can be arranged on both the liquid-impermeable layer side and the liquid-permeable layer side of the absorbent core.
In addition, the plurality of absorbent core portions may be a base sheet on the liquid-impermeable layer side of the absorbent core, the liquid-permeable layer side of the absorbent core, or both the liquid-impermeable layer side and the liquid-permeable layer side of the absorbent core. Fixed to.

  In the present invention, the absorbent article preferably has a Gurley stiffness (No. 10) of about 170 to about 400 mN, and more preferably about 200 to about 300 mN, when 10 sets of Gurley stiffness are measured under wet conditions. Set). When the Gurley bending resistance is less than about 170 mN, the absorbent article may depend on when wet, and when the Gurley bending resistance exceeds about 400 mN, the user tends to feel the absorbent article hard. .

  In the present invention, the absorbent article has a Gurley stiffness retention of preferably about 77 to about 100%, and more preferably about 77 to about 90% when ten sets of Gurley stiffness are measured under wet conditions. Have a rate. If the Gurley bending resistance retention is less than about 77%, there is a risk that the absorbent article will be swung when the absorbent article is used for a long time.

In the present invention, “Gurley stiffness” and “Gurley stiffness retention” are measured as follows. Note that matters not described are in accordance with JIS L 1096: 2010 “8.22.1 A Method Bending Softness (Gurley Method)”.
(1) No. manufactured by Yasuda Seiki Seisakusho Co., Ltd. A 311 Gurley type flexibility tester is prepared in a constant temperature and humidity chamber of 65% RH at 20 ° C.

(2) The absorbent article to be measured is cut into a size of 25 mm × 38 mm (longitudinal direction × width direction) with the center in the longitudinal direction and the center in the width direction as the center, and a measurement sample is prepared.
(3) The measurement sample is immersed in ion-exchanged water until it sinks under its own weight, or immersed in water for 1 hour or more.

(4) The measurement sample is set on a Gurley-type flexibility tester so that the back sheet touches the pendulum, and the bending resistance is measured (first set, first time). Next, the measurement sample is set on a Gurley-type flexibility tester so that the top sheet touches the pendulum, and the bending resistance is measured (first set, second time).
The average value of the two measurements of the bending resistance is adopted as the bending resistance of the first set.
(5) The procedure of the first set (two times in total) is repeated for a total of 10 sets with the same measurement sample, and the first set and the tenth set are calculated.

(6) As an index of the difficulty of the absorbent article, the Gurley stiffness retention (%) is expressed by the following formula:
Gurley bending resistance retention (%)
= 100 × 10th set bending resistance (mN) / 1st set bending resistance (mN)
Calculate according to
In addition, it means that the rigidity of an absorptive article does not fall easily when it gets wet, so that a Gurley bending resistance retention rate is near 100%.

In addition, the specific measurement procedure of bending resistance is as follows.
Attach the measurement sample to the chuck of the movable arm, rotate it to the left or right at a specified speed, read the scale when the lower end of the measurement sample is separated from the pendulum, and calculate the bending resistance S (mN) as follows: Calculate based on

S = R × (D ₁ W ₁ + D ₂ W ₂ + D ₃ W ₃ ) × (L−12.7) ² /b×3.375×10 ⁻⁵
[In the formula, R is a reading of the scale plate, and D ₁ , D ₂ , and D ₃ are distances from the pendulum fulcrum to the weight mounting position (25.4 mm (1 in.), 50.8 mm (2 in.), 101. 6 mm (4 in.)), W ₁ , W ₂ , W ₃ are the weights (g) of the weights attached to the holes D ₁ , D ₂ , D ₃ , and L is the length of the sample piece (mm) And b is the width (mm) of the sample piece. ]

  In the present invention, the absorbent core portion has a ratio of flexural rigidity under wet conditions to flexural rigidity under dry conditions, preferably about 20 to about 40%, and more preferably about 24 to about 30%. If the ratio is less than about 20%, the absorbent article may depend when wet, and if the ratio exceeds about 40%, the user tends to feel the absorbent article as hard.

“Bending stiffness under wet conditions” and “flexural stiffness under dry conditions” are measured as follows.
The measurement was carried out based on KES (Kawabata's Evaluation System for Fabrics). For conditions not described below, “Standardization and analysis of texture evaluation (2nd edition)” (by Katsuo Kawabata, The measurement conditions described in the Japan Textile Machinery Society, Total Wind and Standardization Research Committee (1980) are adopted.

(1) Prepare samples and test equipment as follows.
The absorbent core is cut into a size of 20 mm × 10 mm (MD direction × CD direction) to prepare a sample.
(2) KES-FB2-AUTO-A manufactured by Kato Tech Co., Ltd. is prepared as a test device.

(3) A sample for measuring bending stiffness under dry conditions is prepared by storing and adjusting the state of the sample at a temperature of 23 ± 2 ° C. and a relative humidity of 50 ± 5% for 24 hours or more.
(4) The sample for measuring the bending stiffness under wet conditions is adjusted by immersing the sample in ion-exchanged water until it sinks under its own weight or by immersing it in water for 1 hour or longer.
The measurement is performed in a room at a temperature of 23 ± 2 ° C. and a relative humidity of 50 ± 5%.

(5) “Bending stiffness under dry conditions” and “bending stiffness under wet conditions” are measured according to the following procedure.
The sample is attached to the test equipment so as to bend perpendicularly to the MD direction (clamp interval 1 cm), and the deformation rate is 0.5 cm ^-1 / sec in the range of curvature K = -2.5 to +2.5 cm ^-1. The bending moment M per unit length of the sample (gf · cm / cm) is measured, and an M-K curve is created. The average value of the inclination of the curvature K = 0.5 to 1.5 and the inclination of the curvature K = −0.5 to −1.5 in the M-K curve is the bending rigidity B ₁ (gf · cm in the longitudinal direction of the sample). ² / cm).

The sample is attached to the test equipment so as to bend perpendicularly to the CD direction (clamp interval 1 cm), and an M-K curve is prepared in the same manner as described above. The curvature K in the M-K curve is 0.5 to 1 The average value of the slope of .5 and the slope of curvature K = −0.5 to −1.5 is defined as the bending stiffness B ₂ (gf · cm ² / cm) in the transverse direction of the sample.
The average value of B ₁ and B ₂ is calculated and set as the bending rigidity B (N · m ² / m) of the sample.
In the present specification, the bending rigidity of the sample under the wet condition is expressed as B _W (N · m ² / m), and the bending rigidity under the dry condition is expressed as B _D (N · m ² / m). Is written.

The ratio of the bending stiffness under wet conditions to the bending stiffness under dry conditions (hereinafter sometimes simply referred to as “bending stiffness retention”) is expressed by the following formula:
Bending rigidity retention rate (%) = 100 × B _W / B _D
Calculate according to

  In the present invention, the plurality of absorbent core portions are arranged in a staggered manner in the planar direction of the absorbent article, or are arranged in parallel with the longitudinal direction and / or in the width direction of the absorbent article. Can do. By arranging a plurality of absorbent core portions in a staggered manner, the absorbent body can easily follow the three-dimensional shape of the user's body, and can easily follow the user's actions during exercise such as walking. However, since it has a local folding axis (not having a folding axis extending over the entire absorbent body), problems such as bending of the absorbent body, and hence the absorbent article, are unlikely to occur when worn.

  By arranging the plurality of absorbent core portions in parallel with the longitudinal direction and / or the width direction of the absorbent article, the absorbent body has a plurality of folding axes extending over the whole, and the three-dimensional shape of the user's body Especially, it becomes easy to fit the curved part.

  In the present invention, the thermoplastic resin fiber may be, for example, a modified polyolefin produced by graft polymerization of a vinyl monomer containing an unsaturated carboxylic acid, an unsaturated carboxylic acid anhydride, or a mixture thereof onto the polyolefin, or the modified polyolefin and others. It is preferably a core-sheath type composite fiber having a mixed polymer with a resin as a sheath component, and a resin having a melting point higher than that of the modified polyolefin as a core component, and an unsaturated carboxylic acid, an unsaturated carboxylic acid anhydride or their More preferably, the mixture is, for example, maleic acid or a derivative thereof, maleic anhydride or a derivative thereof, or a mixture thereof.

  In the present invention, the absorbent core preferably contains a highly water-absorbing material. When the absorbent core contains the superabsorbent material, the liquid absorbability of the absorbent core is improved. In addition, since a hydrogen bond is cut | disconnected by the liquid absorbed by the absorption core, it does not inhibit swelling of the highly water-absorbing material contained in the absorption core.

  In the present invention, the absorbent core may be colored. By coloring the absorbent core, it becomes easy to visually check whether the water-absorbing fibers and the thermoplastic resin fibers are uniformly dispersed. In addition, the color of the absorbed liquid can be masked. For example, when the liquid to be absorbed is urine, it is colored blue, and when it is menstrual blood, the user can feel cleanliness.

  In the absorbent article of the present invention, a groove structure may be formed on the surface of the absorbent core on the liquid-permeable layer side and / or on the surface of the liquid-impermeable layer side. Even when force is applied to the absorbent article and the heel portion is crushed, the space of the groove portion is maintained, so that the liquid absorbability and the retainability are maintained. In addition, since the area where the absorbent core comes into contact with the liquid permeable layer is reduced, even if force is applied to the absorbent article, the liquid absorbed by the absorbent core is difficult to reverse, and the liquid from the liquid permeable layer overflows. Protruding is prevented.

  In the present invention, the absorbent core is formed on the surface of the liquid-permeable layer and has a groove structure extending in the longitudinal direction of the absorbent article, and the absorbent article formed on the surface of the liquid-impermeable layer. You may have the groove structure extended in the width direction (short direction).

  In the present invention, the absorbent core may have a fiber density that increases from the surface on the liquid-permeable layer side toward the surface on the liquid-impermeable layer side. Since the spot property is high on the liquid-permeable layer side of the absorbent core and the diffusibility is high on the liquid-impermeable layer side of the absorbent core, the liquid permeability and retention of the absorbent core are improved, and the liquid overflows. This is because it is prevented.

The kind and application of the absorbent article of the present invention are not particularly limited. Examples of the absorbent article include sanitary products and sanitary products such as sanitary napkins, disposable diapers, panty liners, incontinence pads, sweat removing sheets, and the like, and these may be used for humans and other than humans such as pets. Animals may be targeted. The liquid which an absorptive article makes absorption object is not specifically limited, For example, a user's liquid excrement, body fluid, etc. are mentioned.
Hereinafter, an embodiment of the absorbent article of the present invention will be described using a sanitary napkin as an example.

<First Embodiment>
As shown in FIGS. 1 and 2, the sanitary napkin 1 according to the first embodiment includes a liquid-permeable top sheet 2, a liquid-impermeable back sheet 3, and between the top sheet 2 and the back sheet 3. The absorbent body 4 is provided with a pair of side sheets 5a and 5b. The absorbent body 4 includes an absorbent core 8 including a plurality of absorbent core portions 9 and a base sheet 10. The plurality of absorbent core portions 9 are fixed to the base sheet 10 via the fixing portion 15 while being separated from each other.

In FIG. 1, the X-axis direction is the width direction (short direction) of the sanitary napkin 1, the Y-axis direction is the longitudinal direction of the sanitary napkin 1, and the plane directions extending in the X-axis and Y-axis directions are physiological. This corresponds to the plane direction of the napkin 1 for use. The same applies to the other drawings.
In FIG. 1, the some absorption core part 9 is arrange | positioned at zigzag form. As shown in FIG. 2, the plurality of absorbent core portions 9 are fixed to the base sheet 10 disposed on the backsheet 3 side via fixing portions 15 on the backsheet 3 side.

  In the absorbent article of the present invention, each absorbent core portion has an absorbent article longitudinal length of about 5 to about 40 mm, preferably about 10 to about 30 mm, and more preferably about 15 to about 25 mm, and about 3 to about 3 mm. Preferably, the absorbent article has a length in the width direction of about 30 mm, preferably about 5 to about 20 mm, and more preferably about 7 to about 15 mm. This is from the viewpoint of both rigidity at the time of drying and rigidity at the time of wetness.

  In the absorbent article of the present invention, each absorbent core portion has a pitch of about 1 to about 10 mm, preferably about 1 to about 6 mm, and more preferably about 1 to about 4 mm. When the pitch is less than about 1 mm, the interval between the absorbent core portion and the adjacent absorbent core portion is narrowed, and there is a tendency that a folding axis is hardly formed between them, and the pitch is about 10 mm. If it exceeds, the absolute amount of the absorbent core decreases, and the user may feel stickiness due to the remaining liquid.

  As shown in FIGS. 1 and 2, the top sheet 2 and the back sheet 3 are joined at their longitudinal ends by seal portions 11 a and 11 b to form a main body portion 6. The shape of the main body 6 is not particularly limited as long as it fits a female body, underwear, etc. For example, it may be a substantially rectangular shape, a substantially elliptical shape, a substantially saddle shape, or the like. The total length in the longitudinal direction of the outer shape of the main body 6 is preferably about 100 to about 500 mm, more preferably about 150 to about 350 mm. Further, the total dimension in the width direction in the outer shape of the main body 6 is preferably about 30 to about 200 mm, more preferably about 40 to about 180 mm.

  As shown in FIGS. 1 and 2, the pair of side sheets 5a and 5b are provided on both sides of the top sheet 2 in the width direction, and the back sheet 3 and the side sheets 5a and 5b are end portions in the short direction. The parts are joined together by seal parts 12a and 12b to form substantially rectangular wing parts 7a and 7b extending from the main body part 6 in the width direction. The side sheets 5a and 5b preferably have hydrophobicity or water repellency so as to prevent liquid excrement from leaking to the outside in the width direction of the sanitary napkin 1. As a material which comprises the side sheets 5a and 5b, an air through nonwoven fabric etc., such as a spun bond nonwoven fabric and an SMS nonwoven fabric, are mentioned, for example.

  As shown in FIG. 2, adhesive portions 13 a and 13 b are provided on the clothing side of the backsheet 3 that forms the wing portions 7 a and 7 b, and on the clothing side of the backsheet 3 that forms the main body portion 6, An adhesive portion 14 is provided. The sanitary napkin 1 is obtained by attaching the adhesive part 14 to the crotch part of the underwear, bending the wing parts 7a and 7b to the outer surface side of the underwear, and attaching the adhesive parts 13a and 13b to the crotch part of the underwear. Stablely fixed to underwear.

Examples of the pressure-sensitive adhesive that can form the pressure-sensitive adhesive portions 13a, 13b, and 14 include styrene-ethylene-butylene-styrene block copolymer, styrene-butylene polymer, styrene-butylene-styrene block copolymer, and styrene-isobutylene- Styrene polymers such as styrene copolymers; tackifiers such as C5 petroleum resins, C9 petroleum resins, dicyclopentadiene petroleum resins, rosin petroleum resins, polyterpene resins, terpene phenol resins; tricresyl phosphate , phthalic acid Examples include monomer plasticizers such as dibutyl and dioctyl phthalate; polymer plasticizers such as vinyl polymer and polyester.
Moreover, the fixing | fixed part 15 is the same as that of the adhesion parts 13a, 13b, 14, and can be formed with the thing similar to the above-mentioned adhesive.

  The seal portions 11a, 11b, 12a, and 12b are provided at the peripheral portion of the sanitary napkin 1, and examples of the bonding mode by each seal portion include embossing, ultrasonic waves, and a hot-melt adhesive. In order to increase the bonding strength, two or more bonding modes may be combined (for example, embossing is performed after bonding with a hot-melt adhesive).

  As the embossing, for example, the top sheet 2 and the back sheet 3 are combined between the patterned embossing roll and the flat roll, or the top sheet 2, the back sheet 3, and the side sheets 5a and 5b are combined. For example, a method of embossing the peripheral portion of the absorbent body 4 by passing it through (a method called a so-called round seal) may be used.

  In the said method, since each sheet | seat softens by heating an embossing roll and / or a flat roll, a seal part tends to become clear. Examples of the emboss pattern include a lattice pattern, a staggered pattern, and a wavy pattern. The embossed pattern is preferably intermittently elongated so that the sanitary napkin 1 is not easily bent at the boundary of the seal portion.

  As the hot melt adhesive, for example, a rubber system such as styrene-ethylene-butadiene-styrene (SEBS), styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), or a straight chain is used. Pressure-sensitive adhesives or heat-sensitive adhesives mainly composed of olefins such as low-density polyethylene; water-soluble polymers (for example, polyvinyl alcohol, carboxymethyl cellulose, gelatin, etc.) or water-swellable polymers (for example, polyvinyl acetate, And water sensitive adhesives such as sodium polyacrylate). Specific examples of the method for applying the adhesive include spiral coating, coater coating, curtain coater coating, summit gun coating, and the like.

  The sanitary napkin 1 is worn by the user for the purpose of absorbing the user's liquid excretion (for example, menstrual blood, urine, descending product, etc.). At this time, the user wears the top sheet 2 on the user's skin side and the back sheet 3 on the user's clothes (underwear) side. The liquid excrement of the user penetrates into the absorbent body 4 through the top sheet 2 and is absorbed by the absorbent body 4. Leakage of liquid excreta absorbed by the absorber 4 is prevented by the back sheet 3.

  The top sheet 2 is a sheet through which the user's liquid excrement can permeate, and is provided on a surface that comes into contact with the user's skin for the purpose of improving the touch when the user wears the sanitary napkin 1. Yes.

  The top sheet 2 is not particularly limited as long as the user's liquid excrement can permeate. Examples of the top sheet 2 include a nonwoven fabric, a woven fabric, a synthetic resin film in which liquid permeation holes are formed, and a net-like sheet having a mesh. Among these, a nonwoven fabric is preferable.

  Examples of the fibers constituting the nonwoven fabric include natural fibers (wool, cotton, etc.), recycled fibers (rayon, acetate, etc.), inorganic fibers (glass fibers, carbon fibers, etc.), synthetic resin fibers (polyethylene, polypropylene, polybutylene, ethylene). -Polyolefin such as vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ionomer resin; polyester such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polylactic acid; And polyamides such as nylon). Nonwoven fabrics include core / sheath fibers, side-by-side fibers, island / sea fibers, etc .; hollow fibers; flat fibers, Y-shaped fibers, C-shaped fibers, etc .; latent crimps or manifestations Crimped three-dimensional crimped fibers; split fibers that are split by a physical load such as water flow, heat, and embossing may be mixed.

  Examples of the nonwoven fabric manufacturing method include a method of forming a web (fleece) and physically and chemically bonding fibers. Examples of the web forming method include a spunbond method and a dry method (card). Method, spunbond method, melt blown method, airlaid method, etc.), wet method, etc., and examples of the bonding method include thermal bond method, chemical bond method, needle punch method, stitch bond method, spunlace method, etc. It is done. In addition to the nonwoven fabric produced in this manner, a spunlace formed into a sheet shape by a hydroentanglement method may be used as the top sheet 2. Moreover, the nonwoven fabric which provided the unevenness | corrugation on the skin side surface (For example, the nonwoven fabric which formed the unevenness | corrugation in the upper layer side by shrink | contracting the lower layer side containing a heat shrink fiber etc., and the unevenness | corrugation was formed by applying air at the time of web formation Nonwoven fabric or the like) may be used as the top sheet 2. Thus, the contact area between the top sheet 2 and the skin can be reduced by forming irregularities on the skin side surface.

  The thickness, basis weight, density, and the like of the top sheet 2 can be appropriately adjusted as long as the user's liquid excrement can permeate. When using a non-woven fabric as the top sheet 2, the fineness, fiber length, density, basis weight, thickness, etc. of the non-woven fabric can be appropriately adjusted from the viewpoints of permeability of liquid excrement, touch, and the like. .

  From the viewpoint of improving the concealability of the top sheet 2, the nonwoven fabric used as the top sheet 2 may contain an inorganic filler such as titanium oxide, barium sulfate, or calcium carbonate. When the nonwoven fabric fiber is a core-sheath type composite fiber, an inorganic filler may be contained only in the core, or only in the sheath.

  The back sheet 3 is a sheet through which the user's liquid excrement cannot permeate, and on the surface that contacts the user's clothes (underwear) for the purpose of preventing leakage of the liquid excretion absorbed by the absorbent body 4. Is provided. The backsheet 3 preferably has moisture permeability in addition to liquid impermeability in order to reduce stuffiness when worn.

  The back sheet 3 is not particularly limited as long as it does not pass through the user's liquid excrement. Examples of the backsheet 3 include waterproof nonwoven fabric, synthetic resin (eg, polyethylene, polypropylene, polyethylene terephthalate, etc.) film, and composite sheet of nonwoven fabric and synthetic resin film (eg, nonwoven fabric such as spunbond and spunlace). And a composite film in which a breathable synthetic resin film is bonded), an SMS nonwoven fabric in which a melt-blown nonwoven fabric having high water resistance is sandwiched between strong spunbond nonwoven fabrics, and the like.

  In the absorbent body 4, the absorbent core 8 contains cellulosic water-absorbing fibers and thermoplastic resin fibers containing an unsaturated carboxylic acid, an unsaturated carboxylic acid anhydride or a mixture thereof as a monomer component. The fibers are mainly involved in the liquid absorbability and retention of the absorbent core 8, and the thermoplastic resin fibers are mainly involved in the strength of the absorbent core 8 (particularly, the wet strength after liquid absorption).

  The water absorbent fibers and the thermoplastic resin fibers are contained in the absorbent core 8 in a mixed state. Intersections between fibers (for example, intersections between thermoplastic resin fibers, intersections between thermoplastic resin fibers and water-absorbing fibers) are connected by thermal fusion of the thermoplastic resin fibers. This improves the strength of the absorbent core 8 (particularly, the strength when wet after liquid absorption). In addition, the fibers are mechanically entangled and connected by hydrogen bonds formed between the thermoplastic resin fibers, between the water absorbent fibers, or between the thermoplastic resin fibers and the water absorbent fibers. In addition, when the absorption core 8 contains another fiber, the thermoplastic resin fiber and / or the water absorbing fiber may be connected with the other fiber.

  The heat fusion is performed, for example, by heating a mixed material containing water-absorbing fibers and thermoplastic resin fibers at a temperature equal to or higher than the melting point of the thermoplastic resin fibers. The heating temperature can be appropriately adjusted according to the type of thermoplastic resin fiber. The temperature above the melting point of the thermoplastic resin fiber may be at or above the temperature at which a part of the thermoplastic resin fiber melts. For example, when the thermoplastic resin fiber is a core-sheath type composite fiber, the temperature at which the sheath component melts That is all you need.

  In the absorbent core 8, the mass ratio of the water-absorbing fibers to the thermoplastic resin fibers is about 1.0 to about 9.0, and can be appropriately changed within this range, but preferably about 1.5 to about 4 .0. If the mass ratio exceeds about 9.0, the strength of the absorbent core 8 (particularly, the strength when wet after liquid absorption) tends to decrease. If the mass ratio is less than about 1.0, the liquid absorbability of the absorbent core 8 tends to decrease.

The absorbent core 8 is preferably about 0.06 to about 0.14 g / cm ³ , more preferably about 0.07 to about 0.12 g / cm ³ , and even more preferably about 0.08 to about 0.1 g / cm ³ . It has a density of cm ³ . This is from the viewpoint of the liquid absorbability of the absorbent core and the strength after absorption.

  The density of the absorbent core 8 is adjusted to a desired range by increasing the density of the mixed material containing water-absorbing fibers and thermoplastic resin fibers. In order to maintain the density of the absorbent core 8 within a certain range, it is necessary to suppress the elastic recovery of the fibers and maintain the bulk of the absorbent core 8 within a certain range. In this respect, hydrogen bonds (for example, hydrogen bonds formed between water-absorbing fibers, between thermoplastic resin fibers, between water-absorbing fibers and thermoplastic resin fibers, etc.) contribute to maintaining the bulk of the absorbent core 8. The hydrogen bond is formed, for example, between an oxygen atom of a thermoplastic resin fiber (for example, an oxygen atom such as a carboxyl group, an acyl group, or an ether bond) and a hydrogen atom of cellulose (for example, a hydrogen atom of a hydroxyl group). . In addition, since hydrogen bonds are cut by the liquid absorbed in the absorption core 8, the swelling of the absorbent material (the water-absorbing fiber as an essential component, the highly water-absorbing material as an optional component) contained in the absorption core 8 Does not disturb.

  Cellulosic water-absorbing fibers include, for example, wood pulp obtained from softwood or hardwood (for example, mechanical pulp such as groundwood pulp, refiner ground pulp, thermomechanical pulp, chemithermomechanical pulp; kraft pulp, sulfide pulp, alkali Chemical pulp such as pulp; semi-chemical pulp); mercerized pulp or crosslinked pulp obtained by chemically treating wood pulp; non-wood pulp such as bagasse, kenaf, bamboo, hemp, cotton (for example, cotton linter); rayon Examples thereof include recycled fibers such as fibers.

  The thermoplastic resin fiber containing an unsaturated carboxylic acid, an unsaturated carboxylic acid anhydride or a mixture thereof as a monomer component can be appropriately selected from the viewpoints of strength, hydrogen bondability, heat-fusibility, etc., and is particularly limited. Is not to be done.

  Examples of the thermoplastic resin fiber include a modified polyolefin produced by graft polymerization of a vinyl monomer containing an unsaturated carboxylic acid, an unsaturated carboxylic acid anhydride, or a mixture thereof with a polyolefin, or the modified polyolefin and another resin. And a core-sheath type composite fiber having a core component made of a resin having a melting point higher than that of the modified polyolefin.

  Examples of the unsaturated carboxylic acid or unsaturated carboxylic acid anhydride include maleic acid or derivatives thereof, maleic anhydride or derivatives thereof, fumaric acid or derivatives thereof, unsaturated derivatives of malonic acid, and unsaturated derivatives of succinic acid. Examples of other vinyl monomers include general-purpose monomers having radical polymerizability, for example, styrenes such as styrene and α-methylstyrene; methyl (meth) acrylate, ethyl (meth) acrylate, ( And (meth) acrylic acid esters such as 2-hydroxyethyl (meth) acrylate and dimethylaminoethyl (meth) acrylate. Examples of maleic acid derivatives or maleic anhydride derivatives include citraconic acid, citraconic anhydride, pyrocynconic anhydride, and the like, and examples of fumaric acid derivatives or malonic acid unsaturated derivatives include 3-butene- Examples include 1,1-dicarboxylic acid, benzylidenemalonic acid, isopropylidenemalonic acid, and the like. Examples of unsaturated derivatives of succinic acid include itaconic acid and itaconic anhydride.

  As the backbone polymer of modified polyolefin, linear low density polyethylene (LLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), polypropylene, polybutylene, and copolymers based on these (For example, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), ethylene-acrylic acid copolymer (EAA), ionomer resin, etc.).

  For example, graft polymerization of vinyl monomer to the trunk polymer uses a radical initiator, mixes unsaturated carboxylic acid or unsaturated carboxylic acid anhydride and vinyl monomer into polyolefin, and introduces side chains made of random copolymer. And a conventional method such as a method of sequentially polymerizing different monomers and introducing a side chain comprising a block copolymer.

  The sheath component may be a modified polyolefin alone or a mixed polymer of the modified polyolefin and another resin. The other resin is preferably a polyolefin, and more preferably the same type of polyolefin as the backbone polymer of the modified polyolefin. For example, when the trunk polymer is polyethylene, the other resin is also preferably polyethylene.

  The resin used as the core component is not particularly limited as long as the resin has a higher melting point than the modified polyolefin. For example, polyamides such as 6-nylon and 6,6-nylon; polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polylactic acid, polyglycolic acid and other linear or branched polyesters having up to 20 carbon atoms such as polyhydroxyalkanoic acid and copolymers mainly composed of these Or a copolymerized polyester obtained by copolymerizing a small amount of other components with alkylene terephthalate as a main component. PET is preferable from the viewpoint of having high resilience and high cushioning properties, and from the economical viewpoint of being industrially inexpensive.

  Spinning is possible when the composite ratio of the sheath component and the core component is in the range of 10/90 to 90/10, but is preferably 30/70 to 70/30. If the sheath component ratio decreases too much, the heat-fusibility decreases, and if it increases too much, the spinnability decreases.

  Addition of antioxidants, light stabilizers, UV absorbers, neutralizers, nucleating agents, epoxy stabilizers, lubricants, antibacterial agents, flame retardants, antistatic agents, pigments, plasticizers, etc. to thermoplastic resin fibers You may add an agent as needed. The thermoplastic resin fiber is preferably hydrophilized with a surfactant, a hydrophilic agent or the like.

  The fiber length of the thermoplastic resin fiber is not particularly limited, but is preferably about 3 to about 70 mm, more preferably about 5 to about 20 mm when mixed with the pulp in an airlaid manner. Below this range, the number of joints with the water-absorbing fibers decreases, so that sufficient strength cannot be imparted to the absorbent core 8. On the other hand, if it exceeds this range, the defibrating property is remarkably lowered and a large number of undefibrated states are generated, so that uneven formation occurs and the uniformity of the absorbent core 8 is lowered. The fineness of the thermoplastic resin fiber is preferably about 0.5 to about 10 dtex, more preferably about 1.5 to about 5 dtex. When the fineness is less than about 0.5 dtex, the defibration property is lowered, and when it exceeds about 10 dtex, the number of fibers is reduced and the strength is lowered.

  A three-dimensional crimped shape may be imparted to the thermoplastic resin fiber. Thereby, even when the fiber orientation is in the plane direction, the buckling strength of the fiber works in the thickness direction, so that it is difficult to be crushed even if an external pressure is applied. Examples of the three-dimensional crimped shape include a zigzag shape, an Ω shape, and a spiral shape. Examples of the method for imparting the three-dimensional crimped shape include mechanical crimping and shape provision by heat shrinkage. Mechanical crimping can be controlled by the difference in peripheral speed of the line speed, heat, pressurization, etc. for continuous linear fibers after spinning, and the greater the number of crimps per unit length, the greater the resistance to external pressure. The buckling strength is increased. The number of crimps is usually about 5 to about 35 pieces / inch, preferably about 15 to about 30 pieces / inch. In shape imparting by heat shrinkage, for example, by applying heat to fibers made of two or more resins having different melting points, it is possible to perform three-dimensional crimping by utilizing the difference in heat shrinkage caused by the melting point difference. is there. Examples of the shape of the fiber cross section include an eccentric type and a side-by-side type of a core-sheath type composite fiber. The thermal shrinkage of such fibers is preferably about 5 to about 90%, more preferably about 10 to about 80%.

  The absorbent core 8 preferably contains a highly water-absorbing material (for example, a highly water-absorbing resin, a highly water-absorbing fiber, etc.) in addition to the water-absorbing fibers and the thermoplastic resin fibers. The content of the superabsorbent material is usually about 5 to about 80% by mass of the absorbent core 8, preferably about 10 to about 60% by mass, and more preferably about 20 to about 40% by mass.

  Examples of the superabsorbent material include starch-based, cellulose-based, and synthetic polymer-based superabsorbent materials. Examples of starch-based or cellulose-based superabsorbent materials include starch-acrylic acid (salt) graft copolymers, saponified starch-acrylonitrile copolymers, and crosslinked products of sodium carboxymethyl cellulose, and synthetic polymers. Examples of high water-absorbing materials include polyacrylates, polysulfonates, maleic anhydrides, polyacrylamides, polyvinyl alcohols, polyethylene oxides, polyaspartates, polyglutamates , Polyalginate-based, starch-based, and cellulose-based superabsorbent polymers (SAP) and the like. Among these, polyacrylate-based (particularly, sodium polyacrylate-based) superabsorbent Resins are preferred. Examples of the shape of the superabsorbent material include a particulate shape, a fibrous shape, a scale shape, and the like. In the case of the particulate shape, the particle size is preferably about 50 to about 1000 μm, and more preferably about 100 to 100 μm. About 600 μm.

  The absorbent core 8 may contain silver, copper, zinc, silica, activated carbon, an aluminosilicate compound, zeolite or the like in order to have a desired function. Thereby, it can have functions, such as a deodorizing property, antibacterial property, and an endothermic effect.

  The absorption core 8 may be colored with a pigment or the like. Thereby, it is easy to visually check whether the water-absorbing fibers and the thermoplastic resin fibers are uniformly dispersed. In addition, the color of the absorbed liquid can be masked. For example, when the liquid to be absorbed is urine, it is colored blue, and when it is menstrual blood, it is possible to make the user feel clean.

The thickness, basis weight, etc. of the absorbent core 8 can be appropriately adjusted according to the characteristics (for example, absorbency, strength, lightness, etc.) that the sanitary napkin 1 should have. The absorbent core 8 usually has a thickness of about 0.1 to about 15 mm, preferably about 1 to about 10 mm, and more preferably about 2 to about 5 mm, and usually about 20 to about 1000 g / m ² , preferably Has a basis weight of from about 50 to about 800 g / m ² , and more preferably from about 100 to about 500 g / m ² . In addition, the thickness, basic weight, etc. of the absorption core 8 may be constant over the whole, and may differ partially.

  The fiber density of the absorbent core 8 is preferably increased from the surface on the top sheet 2 side toward the surface on the back sheet 3 side. Due to such a fiber density gradient, the absorbent core 8 has a high spot property on the top sheet 2 side and a high diffusibility on the back sheet 3 side of the absorbent core 8, so that the absorbent core 8 has excellent liquid permeability and retainability. The liquid excretion from the top sheet 2 can be prevented from overflowing.

  The absorber 4 may be integrated with the top sheet 2. When the absorbent body 4 is integrated with the top sheet 2, the top sheet 2 and the absorbent body even if a force (for example, a force by a user's operation such as walking or standing) is applied to the sanitary napkin 1. 4. Specifically, since the separation from the absorbent core 8 is prevented, the liquid transferability from the top sheet 2 to the absorbent body 4 is maintained. Thereby, the surface dryness of the top sheet 2 is improved, and it is difficult for the user to have a sticky feeling or a wet feeling. Examples of the integration method include embossing, fusion with a heated fluid, ultrasonic waves, and a hot melt adhesive.

  A second sheet may be provided between the top sheet 2 and the absorbent body 4. The second sheet is not particularly limited as long as the user's liquid excrement can permeate, like the top sheet 2. Specific examples of the second sheet are the same as those of the top sheet 2.

The substrate sheet 10 is not particularly limited as long as it has liquid permeability and absorber retention, but from the viewpoint of low cost and absorber retention, it is molded by a wet method using pulverized pulp as a main material. Tissue is preferred. Moreover, it is preferable that the base material sheet 10 is the same nonwoven fabric as demonstrated regarding the top sheet 2 from a viewpoint of hold | maintaining a some absorption core part.
Moreover, the base material sheet 10 can have elasticity, and as a base material sheet which has elasticity, the elastic nonwoven fabric described in Unexamined-Japanese-Patent No. 2008-248460 is mentioned, for example.

Second Embodiment
In 2nd Embodiment, it replaces with the absorption core 8 between the top sheet 2 and the back sheet 3, and injects high pressure steam into the mixed material containing a water absorbing fiber and a thermoplastic resin fiber, and densifies it. The absorption core 8 ′ (not shown) obtained by the above is provided. The configuration of the absorption core 8 ′ is the same as the configuration of the absorption core 8 except that the density is adjusted by using high-pressure steam injection, and the description is omitted unless necessary.

  The density of the absorption core 8 'is adjusted to a desired range by increasing the density using high-pressure steam injection. When high-pressure water vapor is injected into the mixed material, the water vapor penetrates into the mixed material and forms hydrogen bonds (for example, between water-absorbing fibers, between thermoplastic resin fibers, between water-absorbing fibers and thermoplastic resin fibers, etc.). (Hydrogen bonds) are broken, and the mixed material is softened. Therefore, the pressure required for densification decreases, and the density of the softened mixed material can be easily adjusted. When the density-adjusted mixed material is dried and hydrogen bonds are re-formed, elastic recovery (increase in volume) of the fibers is suppressed, and the density of the absorbent core 8 ′ is maintained within a certain range.

  Densification by jetting high-pressure steam is particularly suitable when an unsaturated carboxylic acid anhydride (for example, maleic anhydride or a derivative thereof) is contained as a monomer component in the thermoplastic resin fiber. When the unsaturated carboxylic acid anhydride group contained in the thermoplastic resin fiber reacts with water vapor to form an unsaturated carboxylic acid, the number of oxygen atoms capable of forming hydrogen bonds increases, so the elastic recovery of the density-adjusted fiber (Increase in bulk) is effectively suppressed.

Densification by injection of high-pressure steam is performed, for example, after bonding thermoplastic resin fibers with water-absorbing fibers. The temperature, vapor pressure, etc. of the high-pressure steam are appropriately adjusted according to the required density range. The temperature of the high-pressure steam is preferably less than the melting point of the thermoplastic resin fiber (for example, when the thermoplastic resin fiber is a core-sheath type composite fiber, the melting point of the sheath component). High-pressure steam is preferably injected at approximately per unit surface area 0.03 kg / m ² ~ about 1.23 kg / m ^2. Steam pressure of the high pressure steam is usually about 0.1 to about 2.0 M P a, preferably from about 0.3 to about 0.8 M P a.

The absorbent core 8 ′ preferably has a basis weight of about 40 to about 900 g / m ² , and more preferably about 100 to about 400 g / m ² . When the basis weight is less than about 40 g / m ² , the amount of fibers is small, and it tends to be difficult to increase the density by jetting high-pressure steam, and when the basis weight exceeds about 900 g / m ² , the amount of fibers is increased. In many cases, the internal penetration of water vapor tends to be difficult.

  On the surface of the absorbent core 8 ', there may be a flange and a groove formed by jetting high-pressure steam. The number, interval, and the like of the flange portion and the groove portion vary depending on the number, pitch, and the like of the nozzles that inject high-pressure steam. In addition, the part into which high-pressure steam is injected becomes a groove part.

  The high-pressure steam may be injected over the entire mixed material or may be injected over a part thereof. Moreover, you may change the temperature of high-pressure steam, vapor pressure, etc. which are injected for every part of mixed material. The density distribution of the absorbent core 8 ′ can be changed by partially injecting high-pressure steam into the mixed material, or by changing the temperature, vapor pressure, etc. of the injected high-pressure steam for each part of the mixed material. .

  The high-pressure steam may be injected while pressing the mixed material, or may be injected without pressing. The density distribution of the absorbent core 8 ′ can be changed by injecting high-pressure steam while pressing a part of the mixed material and injecting high-pressure steam without pressing the other part. For example, when high-pressure steam is sprayed onto the mixed material while passing between mesh conveyor belts that are partially open, high-pressure steam is directly applied to the mesh conveyor belt without being pressed at the opening of the mesh conveyor belt, and the mesh conveyor belt is not open. Then, since high-pressure steam is applied while being pressed, the density distribution can be changed.

In the case of increasing the density by jetting high-pressure steam, it is advantageous in the following points as compared with other methods. When the mixed material is densified by press roll molding, high compression is required to provide a bonding force between fibers that exceeds the repulsive force of the fibers. Moreover, even if compressed once by high compression, a fiber will elastically recover and a bulk will return. On the other hand, when the density of the mixed material is increased by combining a press roll and water spray, if the basis weight is 100 g / m ² or less, moisture can penetrate into the mixed material, but the basis weight is 100 g / m ^2. If it exceeds m ² , it becomes difficult to permeate moisture into the mixed material, and hydrogen bonds cannot be formed inside the mixed material.

  Moreover, if excessive moisture is given, it becomes possible to allow moisture to penetrate into the mixed material. In this case, however, an excessive amount of heat and time are required to evaporate the moisture, resulting in a decrease in productivity. On the other hand, when the density is increased by jetting high-pressure steam, the steam penetrates into the mixed material, and hydrogen bonds (for example, between water-absorbing fibers, between thermoplastic resin fibers, and between water-absorbing fibers and thermoplastic resin fibers). The hydrogen bond formed between them is broken, and the mixed material is softened. Accordingly, the pressure required for densification is reduced, and the density of the softened mixed material can be easily adjusted. Further, the water vapor easily evaporates and the time required for drying is short, so that productivity is improved.

<Third Embodiment>
In the sanitary napkin according to the third embodiment, the plurality of absorbent core portions are arranged in parallel to the longitudinal direction (Y-axis direction) and in parallel to the width direction (X-axis direction).
Hereinafter, although the sanitary napkin which concerns on 3rd Embodiment is demonstrated, since the sanitary napkin which concerns on 3rd Embodiment is the same as the sanitary napkin 1 which concerns on 1st Embodiment except the arrangement | sequence of an absorption core part. The description of the same part is omitted.

  In the third embodiment, as shown in FIG. 3, the plurality of absorbent core portions 9 are arranged in parallel to the longitudinal direction (Y-axis direction) and in parallel to the width direction (X-axis direction). By arranging in this way, the sanitary napkin 1 has a plurality of folding axes LF parallel to the longitudinal direction and a plurality of folding axes WF parallel to the width direction. It becomes easy to conform to the three-dimensional shape of the user's body, and it is easy to bend in parallel with the longitudinal direction and parallel to the width direction following the user's movement during exercise such as walking, and menstrual blood is hard to leak Become.

  In FIG. 3, the top sheet and the side sheet are omitted for explanation. Further, in FIG. 3, only a part of the folding shaft is shown for convenience.

<Fourth embodiment>
In the sanitary napkin according to the fourth embodiment, the plurality of absorbent core portions include two types of absorbent core portions having different sizes.
Hereinafter, although the sanitary napkin which concerns on 4th Embodiment is demonstrated, since the sanitary napkin which concerns on 4th Embodiment is the same as the sanitary napkin 1 which concerns on 1st Embodiment except the size of an absorption core part. The description of the same part is omitted.

  In 4th Embodiment, as FIG. 4 shows, the several absorption core part 9 has the size of the planar direction of the sanitary napkin 1 rather than the several 1st absorption core part 9a and the 1st absorption core part 9a. The first absorbent core portion 9a is arranged in the longitudinal central region of the sanitary napkin 1, and the second absorbent core portion 9b is formed of the sanitary napkin 1. It is arrange | positioned at the longitudinal direction both ends area | region.

By arranging in this way, in the center region in the longitudinal direction of the sanitary napkin 1, that is, the excretory opening contact region, the absorbability and retention of menstrual blood and the form retention against external pressure such as body pressure are excellent. Moreover, by arranging in this way, it is easy to follow the three-dimensional shape of the user's body and to follow the movement such as walking in the longitudinal direction both end regions, and between the user and the sanitary napkin 1 The gap is not easily formed, and the fit is excellent.
In FIG. 4, the top sheet and the side sheet are omitted for explanation.

  The plurality of types of absorbent core portions used in the fourth embodiment can be manufactured by arranging two types of absorbent core portions having different sizes, which are manufactured in two or more times, in a desired arrangement. Or by forming the webs of different sizes by changing the shape of the recesses of the suction drum, specifically the length and width of the recesses, and then pressing them while injecting high-pressure steam, Can do. A detailed manufacturing method will be described later.

<Fifth Embodiment>
In the sanitary napkin according to the fifth embodiment, the plurality of absorbent core portions include two types of absorbent core portions having different densities.
Hereinafter, although the sanitary napkin which concerns on 5th Embodiment is demonstrated, since the sanitary napkin which concerns on 5th Embodiment is the same as the sanitary napkin 1 which concerns on 1st Embodiment except the density of an absorption core part. The description of the same part is omitted.

  In the fifth embodiment, as shown in FIG. 5, a plurality of absorbent core portions 9 are a plurality of low density absorbent core portions 9c and a plurality of high density absorbent cores having a higher density than the low density absorbent core portions 9c. The low-density absorbent core portion 9 c is arranged in the central region of the sanitary napkin 1, and the high-density absorbent core portion 9 d is arranged in the peripheral region of the sanitary napkin 1.

By arranging in this way, in the central region of the sanitary napkin 1, that is, in the excretory opening contact region, the menstrual blood absorbability and retention, and cushioning are excellent, and in the peripheral region of the sanitary napkin 1, It follows the three-dimensional shape of the user's body and movements such as walking, and a gap is not easily formed between the user and the sanitary napkin 1, and the fit is excellent.
In FIG. 4, the top sheet and the side sheet are omitted for explanation.

  A plurality of types of absorbent core parts used in the fifth embodiment can be manufactured by arranging two types of absorbent core parts having different densities, which are manufactured in two or more times, in a desired arrangement. Or, by changing the shape of the recess of the suction drum, specifically the depth of the recess, webs with different basis weights (heights) are formed, and then pressed to the same height while jetting high-pressure steam Thus, it can be manufactured collectively. A detailed manufacturing method will be described later.

  In the sanitary napkin of the first to fifth embodiments, the absorbent core portion has a rectangular shape in the planar direction of the sanitary napkin. However, in the absorbent article of the present invention, the shape of the absorbent core portion in the planar direction of the absorbent article is not limited to a rectangle. In the absorbent article of the present invention, the shape of the absorbent core portion in the planar direction of the absorbent article is, for example, approximately circular, approximately elliptical, approximately triangular, approximately rectangular, for example, approximately square and approximately rectangular, approximately rhombus, Examples include substantially polygons, such as substantially pentagons and hexagons, and polygons having one or more apex angles greater than 180 °.

  In the sanitary napkin of the first to fifth embodiments, the absorbent core portion has a rectangular cross-sectional shape in the width direction of the sanitary napkin. However, in the absorbent article of the present invention, the cross-sectional shape of the absorbent core portion in the width direction of the absorbent article is not limited to a rectangle. In the absorbent article of the present invention, examples of the cross-sectional shape of the absorbent core portion in the width direction and / or the longitudinal direction of the absorbent article include a substantially square shape, for example, a substantially square shape, a substantially rectangular shape, and a substantially trapezoidal shape.

In the sanitary napkin 1 according to the first to fifth embodiments, the surface of the absorbent core portion on the top sheet side is a flat surface. However, in the absorbent article of the present invention, the surface of the absorbent core portion on the liquid permeable layer side may have a structure other than a flat surface, for example, a grooved structure.
For example, as FIG. 6 shows, the absorption core part 9 can have the some collar part 41 and the groove part 42 in the surface at the top sheet 2 side.
6 corresponds to an end view taken along line II-II in FIG.

In the sanitary napkin 1 according to the first to fifth embodiments, the surface of the absorbent core portion on the liquid impermeable layer side is a flat surface. However, in the absorbent article of the present invention, the surface of the absorbent core portion on the liquid impermeable layer side may have a structure other than a flat surface, for example, a grooved structure.
For example, as FIG. 7 shows, the absorption core part 9 can have the some collar part 43 and the groove part 44 in the surface at the side of the back seat | sheet 3. As shown in FIG.
7 corresponds to an end view taken along line II-II in FIG.

The specific example of the manufacturing process of the sanitary napkin which concerns on 1st Embodiment-5th Embodiment is demonstrated based on FIG.
[First step (I)]
On the peripheral surface 151a of the suction drum 151 rotating in the machine direction MD, recesses 153 are formed at a required pitch in the circumferential direction as a mold for filling the absorbent core material. When the suction drum 151 rotates and the recess 153 enters the material supply unit 152, the suction unit 156 acts on the recess, and the absorbent core material supplied from the material supply unit 152 is vacuum sucked into the recess 153.

The hooded material supply unit 152 is formed so as to cover the suction drum 151, and the material supply unit 152 supplies the mixed material 21 of the cellulosic water absorbent fiber and the thermoplastic resin fiber to the recess 153 by air conveyance. Supply. The material supply unit 152 includes a particle supply unit 158 that supplies the highly water-absorbing polymer particles 22, and supplies the highly water-absorbing polymer particles 22 to the recesses 153. Cellulose-based water-absorbing fibers, thermoplastic resin fibers, and highly water-absorbing polymer particles are supplied to the recesses 153 in a mixed state, and a layered material 224 is formed in the recesses 153. The layered material 224 formed in the recess 153 proceeds in the machine direction MD and is transferred onto the carrier sheet 150 having the adhesive applied thereon from the coating machine 159.
The carrier sheet 150 will later form a base sheet for the absorbent core.

FIG. 9 is a partial development view of the suction drum 151. As shown in FIG. 8, the suction drum 151 has a recess 153 on its peripheral surface 151a, and the recess 153 has a plurality of recess portions 153a. Each recessed portion 153a is independent of the other recessed portions, and each recessed portion 153a corresponds to the absorbent core portion of the absorbent core.
By having such a configuration, a plurality of absorbent core portions can be easily manufactured without using a cutting means such as a cutter.

  Moreover, the density of the absorption core part formed can be changed by changing the depth of each recessed part. For example, as shown in FIG. 5, the absorbent core portion 9 composed of a plurality of low-density absorbent core portions 9 c and a plurality of high-density absorbent core portions 9 d has a depth of the concave portion in the central region of the concave portion 153. It can be formed by making it shallower than the depth of the recessed portion in the peripheral region. By reducing the depth of the recessed portion 153a, the height of the layered material 224 to be formed is reduced, that is, the basis weight is reduced. In the third step, the density is reduced by compressing with the mesh conveyor belts 171 and 172. A low low density absorbent core portion can be formed.

  Moreover, the size (size in the planar direction of the absorbent article) of the formed absorbent core portion can be changed by changing the size of each concave portion (size on the peripheral surface of the suction drum). For example, as shown in FIG. 4, the absorbent core portion 9 composed of a plurality of first absorbent core portions 9 a and a plurality of second absorbent core portions 9 b is the size of the recessed portion 153 a in the central region in the longitudinal direction of the recessed portion 153. It can be formed by increasing.

  Furthermore, the shape of the absorption core part formed can be changed by changing the shape of each recessed part. For example, by forming the shape of each concave portion into a frustum having a lower base on the peripheral surface of the suction drum and an upper base from the center of the suction drum, for example, a truncated cone, a square frustum, etc. The shape of the absorption core portion may be a frustum, for example, a truncated cone, a quadrangular frustum or the like.

[Second step (II)]
The layered material 224 transferred onto the carrier sheet 150 moves away from the peripheral surface 151a of the suction drum 151 in the machine direction MD. In the carrier sheet 150, the layered material 224 in an uncompressed state is intermittently arranged in the machine direction MD. The heating unit 103 blows air heated to 135 ° C. at a wind speed of 5 m / sec against the upper surface of the layered material 224 and the heating unit 104 against the lower surface of the layered material 224. As a result, the thermoplastic resin fibers contained in the layered material 224 are melted, and the thermoplastic resin fibers, thermoplastic resin fibers-pulp, thermoplastic resin fibers-superabsorbent polymer particles are bonded (heat-sealed). Material 225 is formed. The conditions (temperature, wind speed, heating time) of the heated air sprayed on the layered material 224 are appropriately controlled according to the production speed and the like.

[Third step (III)]
The breathable mesh conveyor belts 171 and 172 arranged vertically so as to form a pair are run in the machine direction MD while compressing the layered material 225 on the carrier sheet 150. The dimension in the vertical direction d (the distance between the mesh conveyor belts 171 and 172) in the parallel traveling unit 175 is the gap between the upstream upper roll 176 and the upstream lower roll 177 rotating in the machine direction MD, and the downstream upper roll 178. The layered material 225 is compressed to a required thickness by the mesh conveyor bare belts 171 and 172. In FIG. 7, a steam jetting part 173 and a steam suction part 174 are arranged on the parallel running part 175 extending horizontally so as to face each other with the mesh conveyor belts 171 and 172 interposed therebetween.

  For example, a nozzle (not shown) having a diameter of about 0.1 to about 2 mm is provided in the steam injection unit 173, for example, about 0.5 to about 10 mm, preferably about 0.5 to about 5 mm, and more preferably about 0.5. It is arranged in a cross direction CD (not shown) orthogonal to the machine direction MD and the vertical direction TD so as to cross the layered material 225 at a pitch of about 3 mm, and each nozzle is generated by a steam boiler 180 The water vapor having a temperature equal to or higher than the boiling point of the water is supplied through the pipe 182 as high-pressure water vapor adjusted to a vapor pressure of, for example, 0.1 to 2.0 MPa by the pressure control valve 181. From each nozzle, high-pressure steam is jetted through the mesh conveyor belt 171 to the layered material 225 that is compressed by the mesh conveyor belts 171 and 172.

The amount of high-pressure steam sprayed onto the layered material 225 is adjusted according to the traveling speed of the mesh conveyor belts 171 and 172, and when the mesh conveyor belts 171 and 172 are traveling at about 5 to about 500 m / min, it is preferably injected at a range of about 1.23 kg / m ² ~ about 0.03 kg / m ² of the surface area of the layered material 225 that faces the mesh conveyor belt 171. The steam passes through the mesh conveyor belt 171, the layered material 225, and the mesh conveyor belt 172 in order in the thickness direction of the layered material 225, and is collected by the suction action of the vacuum pressure by the steam suction unit 174. The layered material 225 injected with the high-pressure steam proceeds in the machine direction MD, is separated from the mesh conveyor belts 171 and 172, and proceeds to the fourth step.

  By adjusting the number of nozzles, the pitch, and the like of the steam injection unit 173, the flange portion and the groove portion can be formed on the surface of the layered material 225 on which the high-pressure steam is injected. Note that the portion where the high-pressure steam is jetted becomes a groove.

  In the third step, in order to prevent the layered material 225 from being locally compressed by the mesh conveyor belts 171 and 172, at least one of the mesh conveyor belts 171 and 172 can be easily deformed in the vertical direction TD. Those having a degree of flexibility are used. For the mesh conveyor belts 171 and 172, metal wire mesh belts made of stainless alloy, bronze, etc., plastic mesh belts made of polyester fiber, aramid fiber, etc. can be used. A metal belt formed of a plate may be used instead of the mesh belt.

  When the layered material 225 extremely dislikes the mixing of metal powder, it is preferable to use a plastic mesh belt. Further, when a plastic mesh belt is required to have high heat resistance, it is preferable to use a mesh belt made of polyphenylene sulfide resin. A 10-75 mesh plain weave mesh belt using polyphenylene sulfide resin is an example of a particularly preferable mesh belt which has flexibility and can be used for both the mesh conveyor belt 171 and the mesh conveyor belt 172. It is preferable that the steam injection unit 173 and the pipe 182 are provided with appropriate heat retention measures or provided with a drain discharge mechanism. By doing so, it is possible to prevent drain generated in the steam injection unit 173 and the like from being ejected from the nozzle and excessively containing moisture in the layered material 225.

  The water vapor sprayed toward the layered material 225 may be dry steam that does not include a liquid component that is moisture, may be saturated steam, or may be wet steam that includes a liquid component. If the water vapor is wet or saturated steam, the pulp can be easily wetted and deformed. Dry steam can vaporize moisture contained in the pulp, and the vaporized moisture can facilitate the deformation of the pulp. Moreover, if the pulp is a thermoplastic synthetic fiber, the thermoplastic synthetic fiber can be easily deformed by the heat of the dry steam.

  The steam injection unit 173 may be provided with a heating mechanism to change the steam into superheated steam and spray it. It is preferable that the steam suction unit 174 has a pipe that allows the sucked high-pressure steam to go to an exhaust blower (not shown) after passing through the steam separator. In addition, the position of the steam injection part 173 and the steam suction part 174 may be switched, that is, the steam injection part 173 may be on the lower side and the steam suction part 174 may be on the upper side. Further, when it is not necessary to recover the high-pressure steam, the steam suction 174 can be performed without being arranged.

[Fourth step (IV)]
The fourth step is an example of a step for producing a general sanitary napkin. The pair of rolls 300 and 301 is a step of cutting out the absorber 226 obtained in the third step into a predetermined shape. A top sheet is supplied from the roll 302 and sealed with heated embosses 303 and 304 having high-pressure parts and low-pressure parts, and the top sheet and the absorber 226 are integrated. After that, the back sheet 305 is supplied, and the product rim is passed through the steps 306 and 307 in which the peripheral portion of the product is sealed by hot embossing while the absorber 226 is sandwiched between the top sheet and the back sheet. Cut out.

In addition, the absorption core which is not divided into the some absorption core part can also be cut | disconnected to a some absorption core part between a 3rd process and a 4th process, and can also be arrange | positioned in a desired position.
For example, in the first step, the layered material 224 formed from a single recess is transferred to the carrier sheet 150 that is not coated with an adhesive, and after the second and third steps, the fourth step is performed. Previously, it can be cut into the desired absorbent core portion and fixed with an adhesive at the desired location on the carrier sheet.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, the scope of the present invention is not limited to an Example.

[Example 1]
(1) Absorption core material No. 1-No. Preparation of No. 5 Pulp (manufactured by Warehauser, NB416) and heat-fusible conjugate fiber A (hereinafter referred to as “composite fiber A”) were prepared in 5: 5 (No. 1), 6.5: 3.5 (No. .2), 8: 2 (No. 3), 9: 1 (No. 4), and 10: 0 (No. 5). 1-No. 5 (basis weight 200 g / m ² ) was prepared.

  The composite fiber A is a core-sheath type composite fiber having polyethylene terephthalate (PET) as a core component and high-density polyethylene (HDPE) graft-polymerized with a vinyl polymer containing maleic anhydride as a sheath component. The core-sheath ratio of the composite fiber A was 50:50 (mass ratio), the amount of titanium oxide in the core component was 0.7% by mass, the fineness was 2.2 dtex, and the fiber length was 6 mm.

  Absorption core material No. 1-No. 5 is bonded by a general through-air method, and the composite fiber A is heated and fused. 1-No. 5 was prepared. At this time, the heating temperature was set to 135 ° C., the air volume was set to 5 m / second, the heating time was set to 20 seconds, and the thickness was adjusted to 2.8 mm.

(2) Absorber No. 1-No. No. 10 Absorption core No. 10 1-No. 5 is cut into a size of 20 mm × 10 mm (longitudinal direction × width direction), and a stretchable nonwoven fabric coated with an adhesive, as shown in FIG. 2 mm and 2 mm are arranged in a zigzag pattern. 1-No. 5 was produced.

In addition, the said elastic nonwoven fabric was manufactured according to Example 1 of Unexamined-Japanese-Patent No. 2008-248460. The stretchable nonwoven fabric was composed of polypropylene (PP) fiber and polyurethane (TPU) fiber, the basis weight was 27 g / m ² , and the blending ratio of the polyurethane fiber (TPU) was 50% by mass.

  Moreover, the absorption core No. cut into the size of 20 mm x 10 mm (longitudinal direction x width direction). 1-No. As shown in FIG. 3, the absorbent body No. 5 was arranged in parallel with the longitudinal direction and parallel to the width direction, and the longitudinal pitch was changed to 2.2 mm. 1-No. In the same manner as in No. 5, Absorber No. 6-No. 10 was produced.

(3) Absorbent article No. 1-No. Production of No. 10 on the back sheet coated with the adhesive. 1-No. No. 10 is stacked, a second sheet is stacked thereon with an adhesive interposed therebetween, and a top sheet is stacked thereon with an adhesive interposed therebetween, whereby absorbent article no. 1-No. 10 was produced.

The top sheet is a nonwoven fabric having a two-layer structure of an upper layer and a lower layer, and the upper layer is a PET / HDPE core-sheath type composite fiber (fineness: 2.6 dtex, fiber length: 51 mm) and a PET / HDPE core-sheath type composite fiber. (Fineness: 2.8 dtex, fiber length: 51 mm) and a mass ratio of 6: 4, and the lower layer is a PET / HDPE core-sheath composite fiber (fineness: 3.3 dtex, fiber length: 38 mm) ) And the basis weight of the whole nonwoven fabric was 25 g / m ² .

The second sheet is an air-through nonwoven fabric formed from a core-sheath type composite fiber (fineness: 2.8 dtex, fiber length: 38 mm) having polyethylene terephthalate (PET) as a core component and high-density polyethylene (HDPE) as a sheath component. The basis weight was 25 g / m ² .
The back sheet was a film mainly composed of low density polyethylene (LDPE) having a basis weight of 25 g / m ² and linear low density polyethylene (LLDPE).

(4) Measurement of “Gurley Bending Softness” and “Gurley Bending Softness Retention” Absorbent article no. The Gurley stiffness and the Gurley stiffness retention of 1-10 were measured according to the methods specified herein. The results are also shown in Table 1.

The consideration based on Table 1 is as follows.
The absorbent article containing the composite fiber A is both a staggered arrangement of absorbent core parts (absorbent article No. 1 to 4) and a parallel arrangement (absorbent article No. 6 to 9). , Gurley stiffness (10th) and Gurley stiffness retention are high.

From the above, it is clear that the absorbent article of the present invention can retain its rigidity not only when it is dry but also when it is wet.
In addition, the reason why the absorbent article (absorbent article Nos. 1 to 4) including the absorbent core portions arranged in a staggered pattern has higher rigidity than those arranged in parallel (absorbent article Nos. 6 to 9). This is because the absorbent article including the absorbent core portions arranged in a staggered pattern does not have a folding axis extending in its entirety.

(5) Flexural rigidity Absorbent article no. The bending stiffness (B _W ) of the sample under wet conditions of 1-5, the bending stiffness (B _D ) under dry conditions, and the bending stiffness retention (100 × B _W / B _D ) are defined in this specification. Measured according to the method. The results are shown in Table 2 below.

The consideration based on Table 2 is as follows.
Absorbent article no. 1-4 have the bending rigidity (B _W ) of the sample under high wet conditions and the bending rigidity retention (100 × B _W / B _D ).
From the above, it is clear that the absorbent article of the present invention can retain its rigidity not only when it is dry but also when it is wet.
Hereinafter, although the absorption core is not an example including a plurality of absorption core portions, the following Examples 2 to 4 were performed in order to evaluate the performance of the absorption core itself.

[Example 2]
(1) Preparation of absorbent core material A (A1 to A7) Pulp (manufactured by Werehauser, NB416) and heat-fusible conjugate fiber A (hereinafter referred to as “composite fiber A”), 9: 1 (A1), 8: 2 (A2), 6.5: 3.5 (A3), 5: 5 (A4), 3.5: 6.5 (A5), 2: 8 (A6), 0:10 (A7) Absorbent core materials A1 to A7 (basis weight 200 g / m ² ) were prepared by blending at a mass ratio.

  The composite fiber A is a core-sheath type composite fiber having polyethylene terephthalate (PET) as a core component and high-density polyethylene (HDPE) graft-polymerized with a vinyl polymer containing maleic anhydride as a sheath component. The core-sheath ratio of the composite fiber A is 50:50 (mass ratio), the amount of titanium oxide in the core component is 0.7% by weight, the fineness is 2.2 dtex, and the fiber length is 6 mm.

(2) Preparation of absorbent core material B (B1-B9) Pulp (manufactured by Warehauser, NB416) and heat-fusible conjugate fiber B (hereinafter referred to as “composite fiber B”), 9: 1 (B1), 8.5: 1.5 (B2), 8: 2 (B3), 6.5: 3.5 (B4), 5: 5 (B5), 3.5: 6.5 (B6), 2: 8 Absorption core materials B1 to B9 (basis weight 200 g / m ² ) were prepared by blending at a mass ratio of (B7), 0:10 (B8), and 10: 0 (B9).

  The composite fiber B is a core-sheath type composite fiber having polyethylene terephthalate (PET) as a core component and general high-density polyethylene (HDPE) as a sheath component. The core-sheath ratio of the composite fiber B is 50:50 (mass ratio), the amount of titanium oxide in the core component is 0.7% by weight, the fineness is 2.2 dtex, and the fiber length is 6 mm.

(3) Production of absorption core samples A (A1 to A7) and B (B1 to B9) Absorption core materials A1 to A7 and B1 to B9 are bonded by a general through air method, and the composite fibers A and B are heated. Fusion core samples A1 to A7 and B1 to B9 were prepared by fusing. At this time, the heating temperature was set to 135 ° C., the air volume was set to 5 m / second, and the heating time was set to 20 seconds.

(4) Measurement of maximum tensile strength [maximum tensile strength during drying (N / 25 mm)]
Sample pieces (length 150 mm x width 25 mm, 5 pieces) at standard time (temperature 20 ° C, humidity 60%) are attached to a tensile tester (Shimadzu Corporation, AG-1kNI) at a grip interval of 100 mm, and a tensile speed of 100 mm / min. Then, a load (maximum point load) was applied until the sample piece was cut, and the maximum tensile strength per 25 mm width in the length direction (MD direction) of the sample piece was measured.

[Maximum tensile strength when wet (N / 25mm)]
After immersing a sample piece (length 150 mm x width 25 mm) in ion-exchanged water until it sinks under its own weight, or after submerging the sample piece in water for 1 hour or longer, the length direction of the sample piece is the same as above. The maximum tensile strength per 25 mm width in the (MD direction) was measured (ISO 9073-3, JIS L 1913 6.3).
In addition, the measurement of the maximum tensile strength at the time of drying and wetness in other examples was also performed in the same manner as described above.

(5) Measurement of basis weight, thickness and density of absorbent core sample The density of the absorbent core sample was calculated based on the following equation.
D (g / cm ³ ) = B (g / m ² ) / T (mm) × 10 ⁻³
[Wherein D, B, and T represent the density, basis weight, and thickness of the absorbent core sample, respectively. ]

The basis weight (g / m ² ) of the absorbent core sample was measured as follows.
Three test pieces of 100 mm × 100 mm are cut out from the absorption core sample, and the mass of each test piece in a standard state (temperature 23 ± 2 ° C., relative humidity 50 ± 5%) is directly indicated by a balance (Electric Balance manufactured by Kensei Kogyo Co., Ltd. HF-300) and the mass per unit area (g / m ² ) of the absorbent core sample calculated from the average value of the three measured values was taken as the basis weight of the absorbent core sample.
In addition, regarding the measurement of the basis weight of the absorbent core sample, the measurement conditions described in ISO 9073-1 or JIS L 1913 6.2 were adopted for the measurement conditions not particularly specified above.

Measurement of the thickness (mm) of the absorbent core sample was performed as follows.
Thickness gauge by (Ltd. Daiei Kagaku Seiki Seisakusho FS-60DS, measurement surface 44 mm (diameter), measuring pressure 3 g / cm ^2), the absorption core in the standard state (temperature 23 ± 2 ° C., a relative humidity of 50 ± 5%) Pressurize five different parts of the sample (the diameter of each part is 44 mm) with a constant pressure of 3 g / cm ² , measure the thickness after 10 seconds of pressure in each part, and calculate the average value of the five measurements as the absorbent core sample It was set as the thickness.
In addition, the measurement of the basic weight, thickness, and density of the absorption core sample in another Example was implemented similarly to the above.

(6) Results and discussion Table 3 shows the measurement results.

Considerations based on Table 3 are as follows.
In the absorbent core sample A, when the mixing ratio (mass ratio) of the composite fiber A to the pulp is less than 1/9, the maximum tensile strength when wet is expected to be less than 2 N / 25 mm. Therefore, considering the strength when wet, in the absorbent core sample A, it is preferable that the mixing ratio (mass ratio) of the composite fiber A to the pulp is 1/9 or more from the viewpoint of maintaining strength.

  In the absorbent core sample B, when the mixing ratio (mass ratio) of the composite fiber B to the pulp is 1.5 / 8.5 or less, the maximum tensile strength when wet is less than 2 N / 25 mm. Therefore, considering the strength when wet, in the absorbent core sample B, it is preferable that the mixing ratio (mass ratio) of the composite fiber B to the pulp exceeds 1.5 / 8.5.

  When absorption core samples (for example, absorption core sample A1 and absorption core sample B1) having the same mixing ratio (mass ratio) of pulp and composite fibers A and B are compared, the maximum tensile strength (when dry and wet) is In any mixing ratio (mass ratio), the absorbent core sample A is larger than the absorbent core sample B. Moreover, when the mixing ratio (mass ratio) of the pulp and the composite fibers A and B is in the range of 9: 1 to 3.5: 6.5 (absorbing core samples A1 to A5 and B1 to B6), The difference between the maximum tensile strength and the maximum tensile strength when wet (the maximum tensile strength when dry-the maximum tensile strength when wet) is greater in the absorbent core sample A than in the absorbent core sample B.

  In the absorption core sample A, such a difference in strength is caused by hydrogen bonds between the acyl groups of maleic anhydride and oxygen atoms of ether bonds and the OH groups of cellulose. It is considered that such a hydrogen bond does not occur.

  This is also supported by the maximum tensile strength of the web sample. That is, when the maximum tensile strength of the sample in the web state was measured, all samples were less than 0.4 N / 25 mm (see Table 3), and the difference in strength was not caused by the difference in the degree of entanglement. This suggests that it is caused by the presence or absence of hydrogen bond formation. The web sample is a sample that has not been subjected to any treatment after the absorbent core material is laminated on the base material, and is entangled with needle punch, etc., heated with hot air, embossing, energy wave, etc., bonded No treatment such as treatment with an agent is performed.

  In addition, as shown in Table 4 below, since the composite fiber A has a higher heat of fusion than the composite fiber B, the composite fiber A has a higher degree of crystallinity than the composite fiber B, and the difference in strength is as follows. , B is considered to be caused by a difference in crystallinity (bonding strength of the fiber itself).

  In JP-A-2004-270041, a modified polyolefin obtained by graft polymerization of maleic anhydride is bonded to a cellulose fiber because a carboxylic anhydride group of maleic anhydride is cleaved and covalently bonded to a hydroxyl group on the surface of the cellulose fiber. However, in this result, an increase in strength due to the formation of a covalent bond was not observed.

[Example 3]
(1) Production of absorbent core samples C (C1 to C7) and D (D1 to D9) Absorbent core materials A1 to A7 (see Example 2) on a carrier sheet (manufactured by UCKN, tissue basis weight: 14 g / m ² ). And bonded by a general through-air method, and the composite fiber A is heated and fused (heating temperature: 135 ° C., air volume: 5 m / second, heating time: 20 seconds), and then a steam jet (SJ) belt. adjust with press machine to a density of about ^{0.08g / cm 3 (0.0793~0.0817g / cm} 3), absorbent core samples C1~C7 (120mm × 120mm, the 3 sheets) were prepared.
Absorbent core samples D1 to D9 (120 mm × 120 mm, 3 sheets each) were similarly produced using the absorbent core materials B1 to B9 (see Example 2).

The configuration of the used SJ belt press is shown in FIG.
As shown in FIG. 10A, the SJ belt press machine 9 includes mesh conveyor belts 91a and 91b, a steam nozzle 92, and a suction box 93, and the steam nozzle 92 and the suction box 93 facing each other. In the middle, the absorbent core sandwiched between the pair of mesh conveyor belts 91a and 91b is transported, high-pressure steam is jetted from the steam nozzle 92 toward the absorbent core, and the absorbent core is compressed. The water vapor that has passed through the absorption core is sucked by the suction box 93 and exhausted. The thickness of the absorbent core can be adjusted by adjusting the distance between the pair of mesh conveyor belts 91a and 91b.

  The mesh conveyor belts 91a and 91b are polyphenylene sulfide plain weave mesh conveyors (manufactured by Nippon Filcon Co., Ltd.). The vertical and horizontal wire diameters are 0.37 mm, the vertical lines are 34 / inch, and the horizontal lines are 32 / inch. The distance between the mesh conveyor belts 91a and 91b is adjusted to 1 mm or 0.2 mm, and the line speed is 200 m / sec.

As shown in FIG. 10B, the steam nozzle 92 is formed with openings having a diameter of 0.5 mm with an opening pitch of 2 mm and 5 mm, and the steam pressure of water vapor ejected therefrom is 0.7 MPa. Yes, the steam throughput is 1.27 kg / m ² per unit area.

(2) Measurement of absorbency (penetration time, liquid brushing time) A surface sheet (uses a surface sheet of the product name Sophie Haodai) is placed on each absorbent core sample piece, and a perforated acrylic board (in the center) 40 mm × 10 mm holes, 200 mm (length) × 100 mm (width)) were stacked. Using autoburet (Shibata Chemical Instruments Co., Ltd., Multidojimat E725-1 type), artificial menstrual blood (80 g of glycerin, 1 liter of ion-exchanged water, sodium carboxymethylcellulose) toward the hole in the acrylic plate 8 g, sodium chloride 10 g, sodium hydrogen carbonate 4 g, red No. 102 8 g, red No. 2 2 g and yellow No. 5 2 g were used, and 3 ml was injected at 90 ml / min. The time from the start of injection until the artificial menstrual blood staying in the hole in the acrylic plate disappeared was the permeation time (seconds), and the time from the start of injection until the artificial menstrual blood disappeared from the surface sheet was taken as the brush time (seconds). .

(3) Measurement of the maximum tensile strength at the time of drying and wet The maximum tensile strength at the time of drying and wet of each absorbent core sample piece was measured in the same manner as in Example 2.

(4) Results and discussion Table 5 shows the measurement results.

  As shown in Table 5, when the mixing ratio (mass ratio) of pulp and composite fiber A is in the range of 9: 1 to 5: 5 (absorbing core samples C1 to C4), the absorbent core sample has high absorbency. It was. On the other hand, when the mixing ratio (mass ratio) of pulp and composite fiber A is in the range of 3.5: 6.5 to 0:10 (absorbing core samples C5 to C7), the absorbability of the absorbing core sample decreases. There was a trend.

  As shown in Table 5, in the absorbent core sample C, when the mixing ratio (mass ratio) of the composite fiber A to the pulp is less than 1/9, the maximum tensile strength when wet is expected to be less than 2 N / 25 mm. . Therefore, in consideration of strength when wet, in the absorbent core sample C, it is preferable that the mixing ratio (mass ratio) of the composite fiber A to the pulp is 1/9 or more from the viewpoint of maintaining strength.

  As shown in Table 5, in the absorbent core sample D, when the mixing ratio (mass ratio) of the composite fiber B to the pulp is 1.5 / 8.5 or less, the maximum tensile strength when wet is less than 2 N / 25 mm. Become. Therefore, in consideration of strength when wet, in the absorbent core sample D, it is preferable that the mixing ratio (mass ratio) of the composite fiber B to the pulp exceeds 1.5 / 8.5 from the viewpoint of maintaining strength.

From the results shown in Table 5, the density of the absorbent core is about 0.08 g / cm ³ (0.0793 to 0.0817 g / cm ³ ), and the mixing ratio (mass ratio) of the pulp and the composite fiber A is 9: When in the range of 1 to 5: 5, the absorbent core had particularly high strength and absorbency. This is because the composite fiber A can secure the strength of the absorbent core in a smaller amount than the composite fiber B (thus, without inhibiting the absorbability).

[Example 4]
In Example 3, the fixed system a density of about ^{0.08g / cm 3 (0.0793~0.0817g / cm} 3), the mixing ratio of the intensity and from the standpoint of the absorbent, pulp and composite fibers A (mass Ratio) was examined.
In this example, the optimum range of density was examined from the viewpoint of absorbability.

In the same manner as in Example 3, using a pulp (basis weight 200 g / m ² ) obtained by blending pulp (Warehauser, NB416) and composite fiber A with a mixing ratio (mass ratio) shown in Table 6, Absorbent core samples E1 to E9 of various densities (0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.12, 0.13, 0.14 g / cm ³ ) Was measured and absorbency (liquid brushing time) was measured.
Table 6 shows the measurement results.

The measurement results shown in Table 6 revealed the following.
Particularly high when the mixing ratio (mass ratio) of pulp and composite fiber A is in the range of 9: 1 to 5: 5 and the density of the absorbent core is in the range of 0.06 to 0.14 g / cm ^3. Liquid brush performance (specifically, a liquid brush time after dropping 3 cc of artificial menstrual blood within 90 seconds) was obtained.

The present invention relates to the following J1 to J16.
[J1]
An absorbent article comprising a liquid permeable layer, a liquid impermeable layer, and the absorbent provided between the liquid permeable layer and the liquid impermeable layer,
The absorbent body includes an absorbent core composed of a plurality of absorbent core portions, and a base sheet for fixing the plurality of absorbent core portions,
The plurality of absorbent core portions are fixed to the base sheet apart from each other,
The absorbent core contains a cellulosic water-absorbing fiber, and a thermoplastic resin fiber containing an unsaturated carboxylic acid, an unsaturated carboxylic acid anhydride or a mixture thereof as a monomer component, and the thermoplastic resin fiber is the above Connected to water absorbent fibers and / or other thermoplastic fibers,
The said absorbent article characterized by the above-mentioned.

[J2]
The absorbent article according to J1, wherein in the absorbent core, a mass ratio of the water-absorbing fiber to the thermoplastic resin fiber is 1.0 to 9.0.
[J3]
The absorbent article according to J1 or J2, wherein the absorbent core has a density of 0.06 to 0.14 g / cm ³ .

[J4]
It said absorbent core has a basis weight of 40~900g / m ^2, the absorbent article according to any one of J1 to J3.
[J5]
The absorbent article according to any one of J1 to J4, wherein the base sheet has a maximum load elongation rate of 10 to 100%.

[J6]
The absorbent article has a Gurley bending resistance of 170 to 400 mN (10th set) when measuring 10 sets of Gurley bending resistance under wet conditions, and 77 to 100% Gurley bending resistance. Where the Gurley stiffness retention is given by the following formula:
Gurley bending resistance retention (%)
= 100 x 10th set of Gurley stiffness / 1st set of Gurley stiffness,
The absorbent article as described in any one of J1-J5.

[J7]
The absorbent article according to any one of J1 to J6, wherein the absorbent core portion has a ratio of bending rigidity under wet conditions to bending rigidity under dry conditions of 20 to 40%.

[J8]
The plurality of absorbent core portions are arranged in a staggered manner in the planar direction of the absorbent article, or arranged in parallel to the longitudinal direction and / or the width direction of the absorbent article. The absorbent article as described in any one.
[J9]
The said absorption core was obtained by injecting high-pressure water vapor | steam to the mixed material containing the said cellulose water-absorbing fiber and the said thermoplastic resin fiber, and obtaining it as described in any one of J1-J8. Absorbent article.

[J10]
The absorbent article according to J9, wherein the temperature of the high-pressure steam is lower than the melting point of the thermoplastic resin fiber.
[J11]
The thermoplastic resin fiber is a modified polyolefin produced by graft polymerization of a vinyl monomer containing an unsaturated carboxylic acid, an unsaturated carboxylic acid anhydride or a mixture thereof onto a polyolefin, or the modified polyolefin and another resin. The absorbent article according to any one of J1 to J10, which is a core-sheath type composite fiber having a sheath polymer as a sheath component and a resin having a melting point higher than that of the modified polyolefin as a core component.

[J12]
Absorption according to any one of J1 to J11, wherein the unsaturated carboxylic acid, unsaturated carboxylic acid anhydride or mixture thereof is maleic acid or a derivative thereof, maleic anhydride or a derivative thereof, or a mixture thereof. Sex goods.
[J13]
The absorbent article as described in any one of J1-J12 containing a highly water-absorbing material.

[J14]
The absorbent article according to any one of J1 to J13, wherein a groove structure is formed on the surface of the absorbent core on the liquid-permeable layer side and / or on the surface of the liquid-impermeable layer side.
[J15]
A groove structure formed on the surface of the liquid-permeable layer side extends in the longitudinal direction of the absorbent article, and a groove structure formed on the surface of the liquid-impermeable layer side of the absorbent article. The absorbent article according to J14, which extends in the short direction.

[J16]
The absorbent article according to any one of J1 to J15, wherein the fiber density of the absorbent core is higher toward the liquid-permeable layer side surface and / or the liquid-impermeable layer side surface. .

1 Sanitary napkin (absorbent article)
2 Top sheet (liquid permeable sheet)
3 Back sheet (liquid impervious sheet)
4 Absorber 5a, 5b Side sheet 6 Body part 7a, 7b Wing part 8 Absorbing core 9 Absorbing core part 10 Base sheet 11a, 11b, 12a, 12b Seal part 13a, 13b, 14 Adhesive part 15 Fixing part 41, 43 畝Part 42, 44 groove part

Claims (14)

A liquid permeable layer; a liquid impermeable layer; and an absorber provided between the liquid permeable layer and the liquid impermeable layer, wherein the absorber comprises an absorption core portion. A method for producing an absorbent article comprising a core and a base sheet for fixing the plurality of absorbent core portions, wherein the production method comprises superabsorbent polymer particles, cellulosic water absorbent fibers, and a thermoplastic resin. The thermoplastic resin fibers contained in the layered material are melted by blowing heated air onto the uncompressed layered material containing the fibers to melt the thermoplastic resin fibers, the thermoplastic resin fibers and the cellulosic water absorbent fibers, heat After the plastic resin fibers and the superabsorbent polymer particles are heat- sealed, water vapor having a vapor pressure of 0.1 to 2.0 MPa is sprayed onto the layered material to a density of 0.06 to 0.14 g / cm ^3. By the absorption Includes the step of forming the A,
The plurality of absorbent core portions are fixed to the base sheet apart from each other,
The absorbent core contains superabsorbent polymer particles, cellulosic water-absorbent fibers, and thermoplastic resin fibers containing unsaturated carboxylic acid, unsaturated carboxylic acid anhydride or a mixture thereof as monomer components; and Thermoplastic resin fibers are connected to the water-absorbing fibers and / or other thermoplastic resin fibers,
The manufacturing method of the said absorbent article characterized by the above-mentioned. A liquid permeable layer; a liquid impermeable layer; and an absorber provided between the liquid permeable layer and the liquid impermeable layer, wherein the absorber comprises an absorption core portion. A method for manufacturing an absorbent article comprising a core and a base sheet for fixing the plurality of absorbent core portions, wherein the manufacturing method comprises:
(I) (Ia) Mixing highly water-absorbing polymer particles, cellulosic water-absorbing fibers and thermoplastic resin fibers into the plurality of recess portions of the suction drum having a plurality of recess portions corresponding to the plurality of absorption core portions. Forming a plurality of layered materials by supplying in a state,
(Ib) The plurality of layered materials are carrier sheets for forming a base sheet in the absorbent article, and for fixing the plurality of absorbent core portions to the base sheet in the absorbent article A process of transferring to a carrier sheet coated with an adhesive;
(Ic) The thermoplastic resin fibers contained in the layered material are melted by blowing heated air to the plurality of layered materials in the uncompressed state transferred to the carrier sheet, and the thermoplastic resin fibers are thermoplastic. After heat-sealing resin fibers and cellulose-based water-absorbing fibers, and thermoplastic resin fibers and highly water-absorbing polymer particles, 0.06 to 0.14 g of water vapor is sprayed at a steam pressure of 0.1 to 2.0 MPa. sandwiching process to form an absorbent core comprising a plurality of absorbent core, and (I-d) wherein the absorbent body between the liquid permeable layer and the liquid impermeable layer by the density of / cm ³ Process,
Or
(II) (II-a) supplying a superabsorbent polymer particle, a cellulosic water absorbent fiber and a thermoplastic resin fiber in a mixed state to the concave portion of the suction drum having the concave portion to form a layered material;
(II-b) A step of transferring the layered material formed in step (II-a) to a carrier sheet which forms a base sheet in the absorbent article and which is not coated with an adhesive. ,
(II-c) The thermoplastic resin fibers contained in the layered material are melted by blowing heated air onto the uncompressed layered material transferred to the carrier sheet in the step (II-b), and the thermoplastic resin fibers The thermoplastic resin fibers and the cellulose water-absorbing fibers, and the thermoplastic resin fibers and the highly water-absorbing polymer particles are thermally fused together, and then steam of 0.1 to 2.0 MPa is sprayed to 0.06. Forming an absorbent core by making it to a density of ˜0.14 g / cm ³ ,
(II-d) The absorbent core formed in step (II-c) is cut into a plurality of absorbent core portions, and the obtained plurality of absorbent core portions are fixed at desired positions on the carrier sheet using an adhesive. And (II-e) a step of sandwiching the absorber between the liquid-permeable layer and the liquid-impermeable layer,
Including
The plurality of absorbent core portions are fixed to the base sheet apart from each other,
The absorbent core contains superabsorbent polymer particles, cellulosic water-absorbent fibers, and thermoplastic resin fibers containing unsaturated carboxylic acid, unsaturated carboxylic acid anhydride or a mixture thereof as monomer components; and Thermoplastic resin fibers are connected to the water-absorbing fibers and / or other thermoplastic resin fibers,
The manufacturing method of the said absorbent article characterized by the above-mentioned. The method according to claim 1 or 2, wherein a temperature of the water vapor is lower than a melting point of the thermoplastic resin fiber.   The method according to any one of claims 1 to 3, wherein the absorbent core has a mass ratio of the water-absorbing fibers to the thermoplastic resin fibers of 1.0 to 9.0. The absorbent core is 40 to 900 g / m ² The method as described in any one of Claims 1-4 which has the basic weight of. The method as described in any one of Claims 1-5 in which the said base material sheet has the elongation rate at the time of the maximum load of 10 to 100%. The absorbent article has a Gurley stiffness of 170 to 400 mN (10th set) when measuring a total of 10 Gurley stiffness under wet conditions, and 77-100% Gurley stiffness Having a retention rate, wherein the Gurley stiffness retention is:
Gurley bending resistance retention (%)
= 100 x 10th set of Gurley stiffness / 1st set of Gurley stiffness
As defined by
The method according to any one of claims 1 to 6. 8. A method according to any one of the preceding claims, wherein the absorbent core portion has a ratio of bending stiffness under wet conditions to bending stiffness under dry conditions of 20-40%. The plurality of absorbent core portions are arranged in a staggered manner in the planar direction of the absorbent article, or are arranged in parallel with the longitudinal direction and / or the width direction of the absorbent article. 9. The method according to any one of items 8. The thermoplastic resin fiber is a modified polyolefin produced by graft polymerization of a vinyl monomer containing an unsaturated carboxylic acid, an unsaturated carboxylic acid anhydride or a mixture thereof onto a polyolefin, or the modified polyolefin and another resin. The method as described in any one of Claims 1-9 which is a core-sheath-type composite fiber which uses as a core component resin with a higher melting | fusing point than the said modified polyolefin as a sheath component. The unsaturated carboxylic acid, unsaturated carboxylic acid anhydride, or a mixture thereof is maleic acid or a derivative thereof, maleic anhydride or a derivative thereof, or a mixture thereof. the method of. The method according to any one of claims 1 to 11, wherein a groove structure is formed on the surface of the absorbent core on the liquid-permeable layer side and / or on the surface of the liquid-impermeable layer side. The groove structure formed on the surface of the liquid-permeable layer extends in the longitudinal direction of the absorbent article, and the groove structure formed on the surface of the liquid-impermeable layer side of the absorbent article. The method according to claim 12, wherein the method extends in a short direction. 14. The method according to claim 1, wherein a fiber density of the absorbent core is increased toward a surface on the liquid-permeable layer side and / or a surface on the liquid-impermeable layer side. .

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