JP6957106B2 - Absorbent core - Google Patents

Description

The present invention relates to an absorbent core that can be used in an absorbent article.

Conventionally, for example, an absorbent article known as a sanitary napkin or the like includes a liquid-permeable front surface sheet, a waterproof back surface sheet, and an absorbent body arranged between the two sheets. As such an absorbent article, the absorbent core is composed of a thermoplastic resin fiber (synthetic fiber), a cellulose-based water-absorbent fiber (pulp fiber), and a superabsorbent polymer (SAP), and the synthetic fiber is an elastic body. It is known that the structure is soft and hard to twist while having strength (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-43197

In the absorbent article disclosed in Patent Document 1, the first portion in which the synthetic fiber is exposed on the first surface of the absorbent core, the second portion exposed on the second surface, and the connecting portion connecting these portions. And have. And since this synthetic fiber functions as a skeletal role for supporting (holding) pulp, it has high shape stability. However, there is room for improvement in further improving the fit to the wearer's body shape by further increasing the flexibility and deformability while maintaining high shape stability.

The present invention has been made in view of the above circumstances, and relates to an absorbent core capable of achieving both shape stability and fit at a high level.

The absorbent core according to the present invention is a vertically long absorbent core made of a fiber composition containing synthetic fibers and cellulosic water-absorbent fibers, and has recesses recessed from one surface to the other. At least a part of the synthetic fiber in the fiber composition is an absorbent core having a first exposed portion exposed on the inner wall surface of the recess.

According to the present invention, shape stability and fit can be achieved at a high level.

It is a top view which shows schematicly by cutting out a part of the absorbent article which concerns on one Embodiment of this invention. FIG. 5 is an enlarged cross-sectional view schematically showing a cross-sectional shape along the line II-II of FIG. It is a perspective view which shows roughly the state which the absorbent core was seen from the non-skin facing surface side. FIG. 5 is an enlarged cross-sectional view schematically showing a cross-sectional shape along the IV-IV line of FIG. It is a partially enlarged sectional view of FIG. It is a schematic diagram which shows the deformed state of the absorbent core at the time of wearing an absorbent article. It is a figure which shows the part of the manufacturing process for demonstrating the method of manufacturing an absorbent core schematicly. It is an exploded perspective view which shows a part of the fiber stacking drum used for manufacturing an absorbent core. It is sectional drawing which shows roughly the part of the fiber stacking drum and the fiber composition.

Hereinafter, an absorbent article including an absorber having an absorbent core according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the following embodiments do not limit the invention according to each claim, and not all combinations of features described in the embodiments are essential for the means for solving the invention. ..

Hereinafter, in the present embodiment, the "skin facing surface" refers to the surface facing the wearer side when worn, and the "non-skin facing surface" refers to the surface opposite the skin facing surface, that is, the surface is attached to clothing when worn. It shall refer to the surface on the side of the skin. The front-rear direction (longitudinal direction (X direction in FIGS. 1 and 2)) refers to the direction along the long side of the absorbent article 1, and the width direction (short direction (Y direction in FIGS. 1 and 2)). )) Refers to the direction along the skin-facing surface or the non-skin-facing surface among the directions orthogonal to the longitudinal direction. In FIG. 1, the letter F indicates the front of the absorbent article 1, and the letter B indicates the rear of the absorbent article 1.

As shown in FIGS. 1 and 2, the absorbent article 1 according to the present embodiment is a sanitary napkin used by being attached to the skin contact surface (inner surface) of clothing such as shorts. The absorbent article 1 includes a liquid-permeable (water-permeable) front sheet 12 arranged on the skin-facing surface side and a liquid-proof (waterproof) back sheet 14 arranged on the non-skin-facing surface side. , The absorber 40 is provided between the two sheets 12 and 14.

The front surface sheet 12 and the back surface sheet 14 have a size larger than that of the absorber 40, are vertically elongated in the front-rear direction of the absorber 40, and have a shape wider in the width direction than the absorber 40. Both the sheets 12 and 14 extend from both ends in the front-rear direction and the width direction of the absorber 40, respectively, and surround the absorber 40 with the absorber 40 sandwiched between the sheets 12 and 14, respectively. As described above, the adhesive portion 17 is formed on the outer peripheral side by being adhered to each other by a heat seal or the like.

Specifically, when the front surface sheet 12 and the back surface sheet 14 are attached to the inner surface of the wearer's clothing, for example, the front surface sheet 12 and the back surface sheet 14 reach the buttocks from the wearer's lower abdomen through a liquid excretion site (vaginal opening or the like). It has a length and a predetermined width that covers the excretion site over the bases of both thighs. In addition, in FIG. 1, the front surface sheet 12 and the back surface sheet 14 are shown in a mode having the same outer shape when viewed in a plan view.

The surface sheet 12 can be formed of a liquid-permeable sheet material, for example, a single-layer (single sheet) woven fabric, a non-woven fabric, a porous sheet, or the like, or a structure in which a plurality of layers of these materials are stacked. The back surface sheet 14 can be formed of a sheet material having liquid-proof property, for example, polyethylene, a waterproof film, or a composite material such as a film and a woven fabric.

Side sheets 16 forming a wing portion to be wound around a crotch portion such as the shorts are laminated on both sides of the surface sheet 12 in the width direction. On the non-skin facing surface of the back sheet 14, an adhesive layer (not shown) for wrapping and fixing the wing portion around the non-skin contact surface of the crotch portion of the shorts or the like, and the absorbent article 1 are attached to the shorts or the like. An adhesive layer (not shown) for fixing to the inner surface is laminated. A release paper (not shown) is laminated on these pressure-sensitive adhesive layers when not in use. The pressure-sensitive adhesive layer laminated on the back surface sheet 14 may be laminated so as to form an adhesive region provided except for a position corresponding to the recess 33 of the absorbent core 30, which will be described later. In this way, in the absorbent article 1, it is possible to make it difficult to prevent the deformation operation in the thickness direction centering on the recess 33.

As shown in FIGS. 1 and 2, the surface sheet 12 has a plurality of convex portions 13 projecting toward the skin facing surface (front surface) and projecting toward the non-skin facing surface (back surface) side over almost the entire area thereof. The plurality of convex portions 15 are alternately formed in a staggered manner when viewed in a plan view. The surface sheet 12 is formed in a bulky manner by the plurality of convex portions 13 and 15. Although the convex portions 13 and 15 are formed in a hemispherical shape in the present embodiment, each of the convex portions 13 and 15 has various shapes such as a semi-elliptical shape and a conical shape in which the top of the convex side is gently or steeply bent. Can be adopted. The convex portions 13 and 15 of the surface sheet 12 can be formed by various known methods.

Further, a pair of leakage-proof surfaces extending along the front-rear direction of the surface sheet 12 and provided symmetrically with respect to the center line (not shown) in the width direction in a plan view. Grooves 20a and 20b are formed. The pair of leakage-proof grooves 20a and 20b have a streak-like concave shape from the skin-facing surface to the non-skin-facing surface of the surface sheet 12, and a liquid receiving region is formed in the inner region surrounded by these. .. In the description of the present embodiment, the "liquid receiving region" is included in the liquid excretion site facing region which is arranged to face the liquid excretion site (vaginal opening, etc.) of the wearer at the time of wearing, and the liquid excretion of the wearer. A region that receives a liquid such as menstrual blood excreted from a site (vaginal ostium, etc.). It shall refer to the area of the department. The leak-proof grooves 20a and 20b suppress the spread of liquids such as menstrual blood and body fluids discharged from the wearer's liquid excretion site, and integrate the surface sheet 12 and the absorber 40 having the absorbent core 30. It also plays a role of suppressing compression deformation when worn and stabilizing the shape. In addition, the leak-proof grooves 20a and 20b also play a role of raising and fitting the liquid receiving region toward the liquid excretion site of the wearer when the absorbent article 1 is sandwiched between both feet during wearing. These leakage-proof grooves 20a and 20b can be formed by various known methods.

The front surface sheet 12, the back surface sheet 14, and the side sheet 16 are not limited to the shapes shown and the above configurations, and known ones used in conventional absorbent articles can be used.

As shown in FIG. 2, the absorber 40 includes an absorbent core 30 having absorbency and a core wrap sheet 38 that covers at least a part of the absorbent core 30.

The absorbent core 30 is formed of a fiber composition containing synthetic fibers such as thermoplastic resin fibers and cellulosic water-absorbing fibers such as pulp fibers. As shown in FIG. 3, the absorbent core 30 has a vertically long shape having a substantially rounded rectangular appearance in a plan view.

As shown in FIGS. 1 to 3, the absorbent core 30 is composed of a fiber composition having the composition as described above, and the first surface 31 is directed toward the skin facing surface (surface) side so as to face the surface sheet 12. , And a second surface 32 that faces the non-skin facing surface (back surface) side so as to face the back surface sheet 14. Further, the absorbent core 30 is formed on the second surface 32 and has a recess 33 recessed in the direction toward the first surface 31.

In the present embodiment, the recesses 33 extend over the entire length of the absorbent core 30 along the front-rear direction, and a plurality of vertical groove portions 33a arranged side by side along the width direction and the width direction. It is composed of a plurality of lateral groove portions 33b extending along the entire width of the absorbent core 30 and arranged side by side in the front-rear direction. The plurality of flutes 33a and the plurality of lateral grooves 33b form a plurality of block-shaped absorption portions regularly arranged in a grid pattern on the second surface 32 of the absorbent core 30.

As shown in FIGS. 4 and 5, the absorbent core 30 has a portion in which the basis weight (mass per unit area) of the fiber composition at the bottom 34 of the recess 33 is a portion other than the recess 33, that is, in the present embodiment, a block shape. The absorption portion (hereinafter, the portion other than the recess 33 is referred to as a “block-shaped absorption portion”) 35 is formed so as to be smaller than the basis weight of the fiber composition. Therefore, the bottom portion 34 constitutes a low basis weight portion, and the block-shaped absorption portion 35 constitutes a high basis weight portion. In FIG. 4, the display of the core wrap sheet 38 is omitted, and the top and bottom of the absorbent core 30 are displayed upside down.

In addition, when there is no fiber composition in the recess 33 which forms a part or all of the absorbent core 30, that is, when the basis weight of the fiber composition in the bottom 34 of the recess 33 is 0 g / m ^2. Is also included. That is, a part of the vertical groove portion 33a and the horizontal groove portion 33b may reach from the first surface 31 to the second surface 32 of the absorbent core 30, and the plurality of vertical groove portions 33a and the horizontal groove portion 33b are all of the absorbent core 30. By reaching from the first surface 31 to the second surface 32, a plurality of block-shaped absorbing portions 35 may be arranged in a state of being independent of each other to form the absorbing core 30.

Regarding the basis weight, specifically, for example, the basis weight of the fiber composition constituting the bottom portion 34 is more preferably 0% or more in proportion to the basis weight of the fiber composition constituting the block-shaped absorbing portion 35. Is 5% or more, preferably 50% or less, more preferably 40% or less, preferably 0% or more and 80% or less, and more preferably 5% or more and 70% or less. ..

More specifically, the basis weight of the bottom 34 is preferably 0 g / m ² or more, more preferably 10 g / m ² or more, and preferably 400 g / m ² or less, more preferably 350 g / m ² or less. It is preferably 0 g / m ² or more and 400 g / m ² or less, and more preferably 10 g / m ² or more and 300 g / m ² or less.

The basis weight of the block-shaped absorbing portion 35 is preferably 100 g / m ² or more, more preferably 200 g / m ² or more, and preferably 800 g / m ² or less, more preferably 700 g / m ² or less. In addition, it is preferably 200 g / m ² or more and 800 g / m ² or less, and more preferably 300 g / m ² or more and 700 g / m ² or less.

The bottom portion 34 is not only smaller in basis weight than the block-shaped absorbing portion 35, but also has a smaller thickness. As shown in FIG. 5, the thickness t1 of the bottom 34 is preferably 0% or more, more preferably 5%, in proportion to the thickness t of the block-shaped absorbing portion 35 (that is, the thickness of the absorbing core 30) t. It is more preferably 50% or less, more preferably 40% or less, preferably 0% or more and 50% or less, and more preferably 5% or more and 40% or less.

More specifically, the thickness t1 of the bottom 34 is preferably 0 mm or more, more preferably 0.1 mm or more, preferably 5 mm or less, more preferably 4 mm or less, and 0 mm or more and 5 mm or less. It is preferably 0.1 mm or more and 4 mm or less.

The thickness t of the block-shaped absorbing portion 35 is preferably 1.5 mm or more, more preferably 2 mm or more, preferably 10 mm or less, more preferably 8 mm or less, and 1.5 mm or more and 10 mm. It is preferably 2 mm or more, and more preferably 8 mm or less.

In this case, the depth t2 of the recess 33 is preferably 1.4 mm or more, more preferably 1.8 mm or more.

The basis weight of the bottom 34 of the absorbent core 30 described above is determined by pressing a razor (feather shaving blade S single blade) manufactured by FEATHER to cut out the bottom 34, measuring the weight of the cut out portion, and measuring the measured weight. It was calculated by dividing by the area of the cut out part. Further, the basis weight of the block-shaped absorbing portion 35 was calculated by similarly cutting out the block-shaped absorbing portion 35, measuring the weight, and dividing the measured weight by the area of the cut out portion.
To measure the thickness t of the block-shaped absorption unit 35, an acrylic plate having a size of 37 mm × 37 mm and a thickness of 3 mm is placed on the absorbent core 30 including the block-shaped absorption unit 35, and a non-contact laser manufactured by KEYENCE is used. The measurement was performed using a displacement meter (laser head LK-G30, displacement meter LK-GD500). The thickness t1 of the bottom portion 34 and the depth t2 of the recess 33 were measured by using a microscope VHX-1000 manufactured by KEYENCE Co., Ltd. to measure a cross section of the absorbent core 30 corresponding to FIG.

The above-mentioned values of the block-shaped absorbing portion 35 and various values in relation to the bottom portion 34 or the recess 33 are obtained when the leakage-proof grooves 20a and 20b are provided as in the absorbent article 1 of the present embodiment. It suffices if it corresponds to the portion which does not include the leakage-proof grooves 20a and 20b.

As shown in FIG. 5, the absorbent core 30 has a first exposed portion 36a in which at least a part of the synthetic fibers 36 contained in the fiber composition is exposed on the inner wall surface 33c of the recess 33. Further, it is preferable that at least a part of the synthetic fiber 36 has a second exposed portion 36b exposed on at least one of the bottom wall surface 34a, the first surface 31 or the second surface 32 of the recess 33. Here, "exposed" means that the first exposed portion 36a of the synthetic fiber 36 is present on the inner wall surface 33c, or the second exposed portion 36b is present on the bottom wall surface 34a, the first surface 31 or the second surface 32. do.

The synthetic fiber 36 is formed so that its fiber length is longer than, for example, the distance W between the non-opposing inner wall surfaces 33c and 33c of the adjacent recesses 33 and 33. Specifically, as shown in FIG. 5, in the synthetic fiber 36, the fiber length L between the first and second exposed portions 36a and 36b is the distance W between the non-opposing inner wall surfaces 33c and 33c of the recesses 33 and 33. It is formed so as to be longer than (distance W <fiber length L). The synthetic fiber 36 may be configured not to have the second exposed portion 36b. When the synthetic fiber 36 has only the first exposed portion 36a, the length to the end opposite to the first exposed portion 36a may be interpreted as the fiber length L.

Here, the distance between the non-opposing inner wall surfaces 33c and 33c of the adjacent recesses 33 and 33 is a pair of recesses 33 arranged adjacent to each other in a cross section in a direction orthogonal to the extending direction of the recess 33. Of the pair of inner wall surfaces 33c and 33c each of 33, the distance between the inner wall surfaces 33c and 33c on the non-opposing sides (distance between the left inner wall surface 33c and the right inner wall surface 33c shown in FIG. 5). Means. In other words, the distance between the non-opposing inner wall surfaces 33c and 33c of the adjacent recesses 33 and 33 is the convex portion formed by the pair of recesses 33 and 33 arranged adjacent to each other (block in the present embodiment). It means the width of the shape absorbing portion 35). When the adjacent recesses 33 and 33 do not extend in parallel with each other (for example, when the block-shaped absorbing portion 35 is formed in a trapezoidal shape or the like in a plan view), the recesses 33 and 33 The distance W between the non-opposing inner wall surfaces 33c and 33c is not constant. In this case, the fiber length L of the synthetic fiber 36 may be formed to be longer than the minimum value of the distance W between the non-opposing inner wall surfaces 33c and 33c of the recesses 33 and 33.

The distance D between the facing inner wall surfaces 33c and 33c of the recess 33 (groove width of the recess 33) D is preferably 1 mm or more, more preferably 2 mm or more, and preferably 40 mm or less, more preferably 30 mm or less. Further, it is preferably 1 mm or more and 40 mm or less, and more preferably 2 mm or more and 30 mm or less. The distance D may be substantially the same in the vertical groove portion 33a and the horizontal groove portion 33b, or may be completely different. By arbitrarily setting the distance D in the vertical groove portion 33a and the horizontal groove portion 33b in this way, a plurality of block-shaped absorbing portions formed by the concave portions 33 can be formed in various forms.

On the other hand, the fiber length L of the synthetic fiber 36 is preferably 4 mm or more, more preferably 6 mm or more, preferably 70 mm or less, more preferably 60 mm or less, and further preferably 4 mm or more and 70 mm or less. , 6 mm or more and 60 mm or less is more preferable. The fiber length includes an average fiber length. For example, the average fiber length of a pulp fiber means a weight-weighted average fiber length, and Kayani Fiber Lab Fiber Properties manufactured by metso automation. (Offline) means the L (w) value measured by [kajaniFiberLab fiber developers (off-line)].

The distance W between the non-opposing inner wall surfaces 33c and 33c of the recesses 33 and 33 is preferably 5 mm or more, more preferably 7 mm or more, preferably 40 mm or less, more preferably 35 mm or less, and also. It is preferably 5 mm or more and 40 mm or less, and more preferably 7 mm or more and 35 mm or less.

As the cellulose-based water-absorbent fiber that can be adopted for the absorbent core 30, for example, wood pulp obtained from broadleaf tree or coniferous tree as a pulp fiber; non-wood pulp such as bamboo, hemp, cotton (for example, cotton linter) and the like. In addition, regenerated cellulose fibers such as biscous fiber and rayon fiber; semi-synthetic fibers such as acetate fiber, triacetate fiber and promix fiber can be mentioned. When pulp fiber is used as the cellulosic water-absorbent fiber, it is preferable to use kraft pulp which is highly safe and can be produced at low cost. Hereinafter, cellulosic water-absorbent fibers will be described as pulp fibers, but pulp fibers are not shown by reference numerals. Further, in FIGS. 4 and 5, for example, the synthetic fiber 36 is indicated by a thick and long line, but this does not reflect the actual thickness, length or size of the fiber.

The synthetic fiber that can be used in the fiber composition of the absorbable core 30 is preferably, for example, hydrophobic and non-absorbent, but may be hydrophilic. If it is non-water-absorbent, the synthetic fiber can maintain its properties even if the absorbent core 30 comes into contact with the body fluid, so that the shape stability of the absorbent core 30 is more likely to be realized. Examples of the hydrophobic and non-absorbable synthetic fibers (thermoplastic fibers) include polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate; polyamides such as nylon 6 and nylon 66; polyacrylic acid and alkyl methacrylate. Examples thereof include ester, polyvinyl chloride, and polyvinylidene chloride.

Whether the fiber is hydrophilic or hydrophobic can be determined based on the contact angle with water measured by the following method. If this is less than 90 degrees, it is hydrophilic, and if it is 90 degrees or more, it is hydrophilic. It is hydrophobic. The smaller the contact angle with water measured by the following method, the higher the hydrophilicity (lower hydrophobicity), and the larger the contact angle, the lower the hydrophilicity (higher hydrophobicity).

<Measurement method of contact angle>
The fiber is taken out from the measurement target (absorbent core), and the contact angle of water with respect to the fiber is measured. As a measuring device, an automatic contact angle meter MCA-J manufactured by Kyowa Interface Science Co., Ltd. is used. Deionized water is used to measure the contact angle. The amount of liquid discharged from the inkjet water droplet discharge unit (Pulse injector CTC-25 manufactured by Cluster Technology Co., Ltd., having a discharge unit hole diameter of 25 μm) is set to 20 picolitres, and the water droplet is dropped directly above the fiber. The state of dripping is recorded on a high-speed recording device connected to a horizontally installed camera. From the viewpoint of image analysis later, the recording device is preferably a personal computer incorporating a high-speed capture device. In this measurement, an image is recorded every 17 msec. In the recorded video, the first image of water droplets on the fibers is the attached software FAMAS (software version is 2.6.2, analysis method is droplet method, analysis method is θ / 2, image processing algorithm. Is non-reflective, image processing image mode is frame, threshold level is 200, curvature correction is not performed), the angle between the surface of the water droplet in contact with the air and the fiber is calculated, and the contact is made. Make a corner. The fiber taken out from the object to be measured is cut into a fiber length of 1 mm, and the fiber is placed on a sample table of a contact angle meter and maintained horizontally. Measure the contact angles at two different points for each fiber. The contact angle of N = 5 fibers is measured to one digit after the decimal point, and the value obtained by averaging the measured values at 10 points in total (rounded to the second digit after the decimal point) is defined as the contact angle of the fiber with water. The measurement environment is room temperature 22 ± 2 ° C. and humidity 65 ± 2% RH.

Also, as used herein, the term water absorption is understood in a general sense. However, the degree of water absorption of the fiber can be determined by the value of the water content measured by the following method. The water absorption fiber preferably has such a water content of 6.0% or more, and more preferably 10.0% or more. Further, the non-water-absorbent synthetic fiber preferably has a water content of less than 6.0%, more preferably less than 5.0%.

<Measurement method of moisture content>
The water content was calculated by applying the water content test method of JIS P8203 mutatis mutandis. That is, after the fiber sample was allowed to stand in a test room having a temperature of 40 ° C. and a relative humidity of 80% RH for 24 hours, the weight W (g) of the fiber sample before the absolute drying treatment was measured in the room. Then, the fiber sample was subjected to an absolute drying treatment by allowing it to stand for 1 hour in an electric dryer having a temperature of 105 ± 2 ° C. (for example, manufactured by Isuzu Seisakusho Co., Ltd.). After the absolute drying treatment, Si silica gel (for example, Si silica gel (for example,)) is used in a standard test room at a temperature of 20 ± 2 ° C. and a relative humidity of 65 ± 2% in a state where the fiber sample is covered with Saran Wrap (registered trademark) manufactured by Asahi Kasei Corporation. Toyoda Kako Co., Ltd. is placed in a glass desigator (for example, manufactured by Tech Jam Co., Ltd.) and allowed to stand until the temperature of the fiber sample reaches 20 ± 2 ° C. Then, the constant weight W'(g) of the fiber sample is weighed, and the water content of the fiber sample is obtained by the following formula.
Moisture content (%) = (W-W'/ W') x 100

The synthetic fiber contained in the fiber composition of the absorbent core 30 may be, for example, a single fiber made of one kind of synthetic fiber or a blended polymer in which two or more kinds of synthetic fibers are mixed, and other so-called so-called synthetic fibers. It may be a composite fiber. This composite fiber is, for example, a synthetic fiber obtained by combining two or more kinds of synthetic fibers having different components with a spinneret and spinning them at the same time, and a plurality of components are continuous in the length direction of the fiber. A structure that is mutually bonded within a single fiber. The form of the composite fiber includes the core-sheath type and the side-by-side type described above, but is not particularly limited.

On the other hand, examples of the hydrophilic synthetic fiber or the hydrophilized synthetic fiber include hydrophilic synthetic fiber such as polyvinyl alcohol fiber and polyacrylonitrile fiber; hydrophobicity such as polyethylene terephthalate fiber, polyethylene fiber, polypropylene fiber and polyester fiber. Examples thereof include fibers obtained by subjecting synthetic fibers to hydrophilization treatment. The method for hydrophilizing the fiber is, for example, kneading the hydrophilizing agent inside the synthetic fiber, adhering the hydrophilizing agent to the surface of the synthetic fiber, plasma treatment on the surface of the synthetic fiber, or the like. Can be mentioned.

The blending ratio of the pulp fiber and the synthetic fiber 36 in the forming material is such that when the blending ratio of the pulp fiber is 20% by mass or more and 80% by mass or less, the blending ratio of the synthetic fiber 36 is 80% by mass or more and 20% by mass or less. When the compounding ratio of the pulp fiber is 40% by mass or more and 60% by mass or less, the compounding ratio of the synthetic fiber 36 is more preferably 60% by mass or more and 40% by mass or less. In addition to the forming material, an additive such as a deodorant or an antibacterial agent may be added to the absorbent core 30 as needed.

Further, the absorbent core 30 may be composed of a super absorbent polymer (SAP) (not shown). Examples of the super absorbent polymer include cellulose-based, starch-based, and synthetic polymer-based polymers, such as acrylic acid-based superabsorbent polymers. Since the absorbent core 30 contains a super absorbent polymer, the liquid absorbency can be further improved.

When the absorbent core 30 contains a superabsorbent polymer, the absorbent core 30 contains a superabsorbent polymer, for example, 5% by mass or more and 50% by mass or less, preferably 10 by mass of the total mass of the absorbent core 30. It is preferable that the content is in the range of mass% or more and 40 mass% or less.

The core wrap sheet 38 is used to prevent leakage of the fiber composition (forming material) of the absorbent core 30 and to improve the position retention and shape stability (shape retention) of the absorbent core 30. Be done. The core wrap sheet 38 is formed by subjecting, for example, thin paper (thin leaf paper) such as hydrophilic tissue paper, crepe paper, non-woven fabric made of hydrophilic fibers such as cotton and rayon, and synthetic resin fibers to a hydrophilic treatment. Various hydrophilic sheets such as non-woven fabrics (for example, air-through non-woven fabrics, point-bonded non-woven fabrics, spunlaced non-woven fabrics, spunbonded non-woven fabrics, spunbond-melt blown-spunbond (SMS) non-woven fabrics, etc.) can be adopted.

As shown in FIG. 2, the absorber 40 having the above configuration is formed by covering at least a part of the absorbent core 30, in the present embodiment, with a core wrap sheet 38. In this state, the core wrap sheet 38 is fixed to either one of the first exposed portion 36a and the second exposed portion 36b of the synthetic fiber 36, preferably both the first exposed portion 36a and the second exposed portion 36b. .. Note that FIG. 5 illustrates a state in which the core wrap sheet 38 is fixed to the second exposed portion 36b of the synthetic fiber 36. The absorber 40 configured in this way is arranged at the center of the absorbent article 1 in the width direction so that the front-rear direction thereof coincides with the front-rear direction of the absorbent article 1. Further, the absorber 40 is arranged between the front surface sheet 12 and the back surface sheet 14 so that the opening of the recess 33 of the absorbent core 30 faces the back surface sheet 14.

According to the absorbent article 1 provided with the absorbent body 40 having the absorbent core 30 according to the present embodiment configured as described above, the absorbent core 30 is a fiber composition in which synthetic fibers 36 are mixed with pulp fibers. It has a vertically long shape, and is provided with a recess 33 that is recessed from one surface (second surface 32) toward the other surface (first surface 31).

Therefore, as compared with the case where the absorbent core 30 is made of only pulp fibers or is made of a super absorbent polymer, the flexibility is excellent even after liquid absorption, and the bottom 34 in the recess 33 is formed. As a starting point, it has a structure that easily bends or bends in the thickness direction of the absorbent core 30. Therefore, the absorbent core 30 has the characteristics that it is excellent in flexibility as a whole and has a very high fit to the wearer's body shape.

Further, the absorbent core 30 has a structure in which the first exposed portion 36a of the synthetic fiber 36 is exposed and fixed to the inner wall surface 33c of the recess 33 facing the bottom portion 34 which can be the starting point of bending. Therefore, the synthetic fiber 36 can act as an elastic body of the absorbent core 30 to some extent. Thereby, for example, even if the absorbent article 1 is deformed due to a large external force due to the movement of the wearer, the shape of the recess 33 of the absorbent core 30 can be maintained appropriately.

That is, the synthetic fiber 36 exhibits a restoring force that stretches when an external force is applied to the absorber 40 and deforms the absorbent core 30, and contracts when the external force is removed to quickly restore the shape of the absorbent core 30. This restoring force is so high that the first exposed portion 36a of the synthetic fiber 36 is exposed on the inner wall surface 33c, and the second exposed portion 36b is further exposed on the bottom wall surface 34a, the first surface 31 or the second surface 32. The higher it is, the higher it becomes.

Further, this restoring force becomes higher as the first exposed portion 36a and the second exposed portion 36b are fixed to the core wrap sheet 38. It is considered that this is because a part of the synthetic fiber 36 is fixed to the core wrap sheet 38, so that the synthetic fiber 36 can more easily function as the elastic body as described above. Then, when the absorbent core 30 and the core wrap sheet 38 are fixed in this way, the absorbent core 30 and the core wrap sheet 38 exhibit an integral motion followability to the wearer's motion, thereby providing a good fit. Can be done.

That is, according to such a structure, a part of the synthetic fiber 36 can function as a skeletal role for supporting the pulp fiber. As a result, the strength of the absorbent core 30 and the absorbent body 40 is improved, and the absorbent core 30 and the absorbent body 40 are less likely to be bent and lose their shape, and have extremely high shape stability. be able to.

In particular, in a part of the synthetic fiber 36, if the first exposed portion 36a is exposed on the inner wall surface 33c and the second exposed portion 36b is exposed on the bottom wall surface 34a, the first surface 31 or the second surface 32, Since the restoring force against deformation when an external force is applied to a portion (block-shaped absorbing portion 35) other than the bottom portion 34 of the recess 33 is increased, it is possible to realize an absorbent core 30 that is even more difficult to lose its shape.

The synthetic fiber 36 is formed so that the fiber length L between the first and second exposed portions 36a and 36b is longer than the distance W between the non-opposing inner wall surfaces 33c and 33c of the recesses 33 and 33. Therefore, the restoring force against deformation can be further enhanced, and the shape stability can be further improved.

Further, in the absorbent core 30, the bottom portion 34 of the recess 33 constitutes a low basis weight portion, the block-shaped absorption portion 35 constitutes a high basis weight portion, and the second surface 32 on which the recess 33 is formed is absorbent. Since it is arranged on the non-skin facing surface side of the article 1, it is highly deformable and has a structure in which the first surface 31 which is the skin contact surface is relatively easy to adhere to the body.

Therefore, as shown in FIG. 6, the absorbent core 30 is formed by the recess 33 on the second surface 32 side while keeping the first surface 31 side as close as possible to the liquid excretion site and the intergluteal cleft of the wearer 90. It becomes easy to deform the entire shape so as to follow the body shape of the wearer 90. Therefore, it has a characteristic that the fit to the wearer's body shape is very high and the flexibility is excellent, so that the follow-up deformability with respect to the wearer's movement is very excellent. This can provide a comfortable wearing feeling.

Further, since the recess 33 of the absorbent core 30 is composed of a plurality of vertical groove portions 33a and horizontal groove portions 33b having a predetermined length, it is possible to further improve the deformation followability of the wearer to the body shape. can. If the synthetic fiber 36 has hydrophobicity, when the absorbent core 30 absorbs a liquid such as menstrual blood or body fluid and becomes wet (swelling), it is absorbed as compared with the hydrophilic synthetic fiber. It is possible to further improve the shape retention of the sex core 30.

The absorbent article 1 is provided with an adhesive layer laminated on the back sheet 14 as an adhesive region for fixing the absorbent article 1 to the underwear. The adhesive region is configured to be provided except for at least a part of the recess 33 of the absorbent core 30 and the position corresponding to the thickness direction. With this configuration, the absorbent article 1 can be provided with more excellent flexibility and deformability because the adhesive region does not hinder the diameter-expanding or diameter-reducing operation of the recess 33. ..

Next, a method for manufacturing the absorbent core 30 according to the present embodiment will be described.
As a manufacturing method, it is composed of a fiber composition containing synthetic fibers and cellulosic water-absorbent fibers, and is formed on the first surface 31, the second surface 32 on the opposite side, and the second surface 32, and is the first surface. An absorbent core 30 having a recess 33 recessed in the direction toward the surface 31 and having a first exposed portion 36a in which at least a part of the synthetic fiber 36 in the fiber composition is exposed on the inner wall surface 33c of the recess 33 can be manufactured. The method is not particularly limited, and a known method in the art can be used.

As shown in FIG. 7, for example, a part of the outer peripheral surface of the stacking fiber drum 100 rotating in the mechanical direction M indicated by the arrow in the figure is covered with the hood 111. Inside the stacking fiber drum 100, a negative pressure due to vacuum acts on the central portion except for the lower portion. Further, the other part of the outer peripheral surface of the stacking fiber drum 100 may be provided with holding belts (not shown) arranged to face each other along the outer peripheral surface.

Synthetic fibers 36 and cellulosic water-absorbent fibers are supplied into the hood 111 from a material supply unit (not shown) connected via a duct 111a. In FIG. 7, the synthetic fiber 36 and the cellulosic water-absorbent fiber are not shown.

These fibers are supplied to the outer peripheral surface of the fiber stacking drum 100 via the duct 111a and the hood 111 in a defibrated and scattered state. For example, a polymer shooter 115 is provided on a part of the hood 111 on the duct 111a side, and when the fiber composition contains a superabsorbent polymer, the superabsorbent polymer particles pass through the polymer shooter 115. Is supplied.

As shown in FIG. 8, a stacking fiber plate 104 in which a plurality of stacking fiber pockets 101 are connected along the circumferential direction is attached to the outer peripheral surface of the stacking fiber drum 100. A plurality of stacking fiber pocket portions 101 are attached, for example, at regular intervals along the circumferential direction of the outer peripheral surface of the stacking fiber drum 100.

The fiber stacking plate 104 is formed with a convex portion 104a for forming a concave portion 33 of the absorbent core 30. Then, due to the negative pressure in the fiber stack 100, as shown in FIG. 9A, the fiber composition 105 composed of the synthetic fiber 36 which is the material for forming the absorbent core 30 and the cellulosic water-absorbing fiber is formed. It is deposited in a predetermined shape in the fiber stack 104. In addition, in FIG. 9, these fibers are not specified.

Then, by releasing the deposited fiber composition 105 from the fiber stacking plate 104, the fiber composition becomes an absorbent core 30 in which a portion corresponding to the recess 33 is formed as shown in FIG. 9B. The thing 105 can be obtained.

Further, in the portion of the released fiber composition 105 corresponding to the recess 33, at least a part of the first exposed portion 36a of the synthetic fiber 36 is exposed at the portion corresponding to the inner wall surface 33c. .. At the same time, at least a part of the second exposed portion 36b of the synthetic fiber 36 is exposed to a portion corresponding to the bottom wall surface 34a, the first surface 31 or the second surface 32 of the recess 33 of the fiber composition 105. It may be.

Then, as shown in FIG. 7, the fiber composition 105 thus obtained is suction-placed by the vacuum conveyor 100a with the opening of the portion corresponding to the recess 33 facing upward, and is placed in the mechanical direction M. Will be transported to.

Then, for example, the obtained absorbent core 30 is coated with the core wrap sheet 38 to form the absorbent body 40, and the absorbent body 40 is arranged at a predetermined position between the front surface sheet 12 and the back surface sheet 14 to form a side sheet. Laminate with 16. Further, if the leak-proof grooves 20a and 20b are formed by known embossing or the like, the front surface and the back surface sheets 12 and 14 are adhered by the adhesive portion 17, and the back surface sheet 14 is provided with an adhesive region, as shown in FIG. Absorbent article 1 can be obtained.

As described above, according to the absorbent core 30, the absorbent body 40 and the absorbent article 1 provided with the absorbent core 30 and the absorbent body 40 according to the present embodiment, it is possible to achieve both shape stability and fit at a higher level than before. It becomes. Although the embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

For example, in the above embodiment, a sanitary napkin has been described as an example of the absorbent article 1, but the absorbent core 30 and the absorber 40 of the present invention are not limited to such sanitary napkins, and paper diapers are used. It can be applied to various known absorbent articles such as incontinence pants and urine absorbing pads. Further, the recess 33 of the absorbent core 30 includes not only the groove-shaped one described above, but also a recessed shape having a square shape or a circular shape when viewed in a plan view. Then, at least one recess 33 may be formed in the absorbent core 30. Further, the recess 33 may be formed by, for example, at least one of the vertical groove portion 33a and the horizontal groove portion 33b, and in this case, at least one of the vertical groove portion 33a and the horizontal groove portion 33b may be formed. Further, the vertical groove portion 33a and the horizontal groove portion 33b do not necessarily have to be formed over the entire length or width of the absorbent core 30. Further, in the absorbent core 30, the recess 33 may be arranged on the side facing the skin.

1 Absorbent article 12 Front sheet 14 Back sheet 30 Absorbent core 31 First surface 32 Second surface 33 Recessed 33a Vertical groove 33b Horizontal groove 33c Inner wall surface 34 Bottom 34a Bottom wall surface 35 Block-shaped absorbing part 36 Synthetic fiber 36a First exposure Part 36b Second exposed part 38 Core wrap sheet 40 Absorber

Claims (10)

A vertically long absorbent core composed of a fiber composition containing synthetic fibers and cellulosic water-absorbent fibers.
It has a recess that dents from one side to the other
At least a part of the synthetic fiber in the fiber composition has a first exposed portion exposed on the inner wall surface of the recess and a second exposed portion exposed on the bottom wall surface of the recess, the one surface or the other surface. It has a door,
A plurality of the recesses are formed.
An absorbent core in which the fiber length between the first exposed portion and the second exposed portion is longer than the distance between the non-opposing inner wall surfaces of the recesses provided adjacent to the first exposed portion. The absorbent core according to claim 1, wherein the recess has a basis weight of the fiber composition at the bottom thereof, which is smaller than the basis weight of the fiber composition at a portion other than the recess. The absorbent core according to claim 1 or 2 , wherein the recess is a groove extending along at least one of the longitudinal direction and the lateral direction of the absorbent core. The absorbent core according to claim 3 , wherein the recess extends over the entire width in the lateral direction. The absorbent core according to any one of claims 1 to 4 , wherein the synthetic fiber has hydrophobicity. The absorbent core according to any one of claims 1 to 5.
A liquid permeable sheet covering at least a part of the surface of the absorbent core is provided.
The liquid permeable sheet is an absorber that is fixed to the first exposed portion of the synthetic fiber of the absorbent core. The absorbent core according to any one of claims 1 to 5.
A liquid permeable sheet covering at least a part of the surface of the absorbent core is provided.
The liquid permeable sheet is an absorber that is fixed to the second exposed portion of the synthetic fiber of the absorbent core. A liquid-permeable surface sheet placed on the side facing the skin,
A liquid-proof back sheet placed on the non-skin facing side,
An absorbent article comprising the absorbent core according to any one of claims 1 to 5 arranged between these sheets. The eighth aspect of the present invention, wherein the back surface sheet has an adhesive region provided on the surface of the non-skin facing surface side except for at least a part of a position corresponding to the concave portion of the absorbent core in the thickness direction. Absorbent article. The absorbent article according to claim 8 or 9 , wherein the absorbent core is arranged so that the opening of the concave portion faces the back surface sheet.

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