JP7846957B2 - Absorbent materials and absorbent articles - Google Patents

Description

This invention relates to an absorbent material and an absorbent article equipped therewith.

Generally, absorbent materials consist of a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent core placed between the top and back sheets. Bodily fluids such as urine are absorbed through the top sheet into the absorbent core. These absorbent materials come in various types depending on their intended use, regardless of whether they are for adults or infants, including tape-type diapers, pull-up diapers, urine pads, and light incontinence pads.

Furthermore, composite nonwoven fabrics are used as absorbents in such absorbent articles. For example, Patent Document 1 discloses a nonwoven composite fabric with a high pulp content, formed by entanglement under hydraulic pressure, characterized by containing approximately 30% by weight or less of nonwoven continuous filament support and approximately 70% by weight or more of pulp fibers.

Japanese Patent Application Publication No. 05-179545

On the other hand, recently, in the use of absorbent items such as disposable diapers, there is a preference for products that can repeatedly absorb bodily fluids such as urine, thereby reducing the frequency of changing the absorbent item. In light of this need, the conventional composite nonwoven fabric absorbent material described above has room for improvement in terms of bodily fluid absorption capacity, absorption rate during repeated absorption, fluid return, diffusion, and wearing comfort.

This invention has been made in view of these circumstances, and aims to provide an absorbent material that has high absorption capacity, can maintain the absorption rate during repeated absorption, has low backflow, has excellent diffusion of body fluids, and provides a good wearing comfort, as well as an absorbent article equipped therewith.

The inventors, after diligent research to achieve the above-mentioned objectives, have discovered that the absorbent material is a laminate comprising: a first absorbent material containing fluff pulp as an absorbent base material, positioned on the skin side of the wearer; and a second absorbent material not containing fluff pulp, positioned on the non-skin side of the wearer. The second absorbent material includes a highly absorbent sheet, the highly absorbent sheet comprising: a first composite nonwoven fabric layer in which a pulp fiber web is laminated on the surface of a spunbond nonwoven fabric; a second composite nonwoven fabric layer in which a pulp fiber web is laminated on the surface of a spunbond nonwoven fabric; and a highly absorbent polymer disposed between the first and second composite nonwoven fabric layers. Furthermore, the highly absorbent sheet is provided with openings extending in the longitudinal direction. Based on these findings, the inventors have completed the present invention.

In other words, the present invention is as follows:

(1)
An absorbent material used in an absorbent article, which absorbs and retains the bodily fluids of the wearer of the absorbent article, comprising a laminate including a first absorbent material containing fluff pulp as an absorbent base material, which is placed on the skin side of the wearer, and a second absorbent material not containing fluff pulp, wherein the second absorbent material includes a highly absorbent sheet, the highly absorbent sheet comprising a spunbond nonwoven fabric and a first composite nonwoven fabric layer including a pulp fiber web integrated on at least one surface of the spunbond nonwoven fabric, and a second composite nonwoven fabric layer including a spunbond nonwoven fabric and a pulp fiber web integrated on at least one surface of the spunbond nonwoven fabric , and the first The absorbent material comprises a composite nonwoven fabric layer and a superabsorbent polymer disposed between the second composite nonwoven fabric layer, wherein the first composite nonwoven fabric layer and/or the second composite nonwoven fabric layer have surfaces in contact with the superabsorbent polymer where the spunbond nonwoven fabric and the pulp fiber web are entangled by water flow, the entangled surfaces of the composite nonwoven fabric layer have irregularities formed on them, the irregularities hold the superabsorbent polymer, the superabsorbent sheet has two openings extending in the longitudinal direction in the width direction , the spacing between the openings in the width direction is 60 to 100 mm, and the width dimension of the openings in the superabsorbent sheet is 5 to 12 mm .
(2)
The second absorbent is the absorbent of (1), further comprising a hydrophilic sheet covering at least a portion of the surface of the highly absorbent sheet .
(3 )
The first composite nonwoven fabric layer and/or the second composite nonwoven fabric layer is an absorbent of either (1) or ( 2 ), wherein the material of the spunbond nonwoven fabric is at least one selected from the group consisting of nylon, vinylon, polyester, acrylic resin, polyethylene, polypropylene, and polystyrene.
( 4 )
The first composite nonwoven fabric layer and/or the second composite nonwoven fabric layer is an absorbent of any of (1) to (3), wherein the basis weight of the spunbond nonwoven fabric is 7 to 20 g/ ^m² , the basis weight of the pulp fiber web is 30 to 70 g/ ^m² , and the weight composition ratio of the spunbond nonwoven fabric to the pulp fiber web is 40/60 to 10/90 .
( 5 )
The absorbent is one of (1) to ( 4 ), wherein the longitudinal dimension of the opening of the superabsorbent sheet is 50 to 95% of the maximum longitudinal dimension of the superabsorbent sheet.
(6)
Using a jig with a base of 140 x 100 mm, an outer diameter of 40 mm, an inner diameter of 35 mm, and a weight of 1400 g, 150 mL of physiological saline solution is injected three times at 10-minute intervals under load, and the time required to absorb the third injection of 150 mL of saline solution is less than 50 seconds, and the absorbent is one of the (1) to (5) described above.
(7)
Using a jig with a base of 140 x 100 mm, an outer diameter of 40 mm, an inner diameter of 35 mm, and a weight of 1400 g, 150 mL of physiological saline solution is injected three times at 10-minute intervals under load, and the maximum length of the area that absorbed the physiological saline solution exceeds 280 mm, and the absorbent is one of the (1) to (6) described above.
( 8 )
An absorbent article comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, and one of the absorbents (1) to ( 7 ) disposed between the top sheet and the back sheet, wherein the absorbents are arranged such that the first absorbent is located on the top sheet side, which is on the skin side of the wearer, and the second absorbent is located on the back sheet side, which is on the non-skin side of the wearer.

According to the present invention, it is possible to provide an absorbent material that has high absorption capacity, maintains its absorption rate during repeated absorption, has low backflow, exhibits excellent diffusion of body fluids, and provides a good wearing comfort, as well as an absorbent article equipped therewith.

Figure 1 is a schematic plan view of an absorbent article according to the first embodiment. Figure 2 is a schematic cross-sectional view along the line X-X in Figure 1. Figure 3 is a schematic cross-sectional view showing the arrangement of the first composite nonwoven fabric layer, the second composite nonwoven fabric layer, and the superabsorbent polymer. Figure 4 is a schematic cross-sectional view of the absorbent article of Comparative Example 1. Figure 5 is a schematic cross-sectional view of the absorbent article of Comparative Example 2. Figure 6 is a schematic cross-sectional view of the absorbent article of Comparative Example 3.

The following describes in detail embodiments for carrying out the present invention (hereinafter simply referred to as "this embodiment"). This embodiment is illustrative for explaining the present invention and is not intended to limit the present invention to the following content. The present invention can be appropriately modified and implemented within the scope of its gist.

Furthermore, identical elements in the drawings will be given the same reference numeral, and redundant explanations will be omitted. Unless otherwise specified, positional relationships (up, down, left, right, etc.) are based on those shown in the drawings. Additionally, the dimensional ratios in the drawings are not limited to those shown.

Furthermore, in this specification, terms marked with "abbreviated" indicate the meaning of the term without the "abbreviated" designation, within the scope of common technical knowledge for those skilled in the art, and also include the meaning of the term without the "abbreviated" designation.

Figure 1 is a schematic plan view of an absorbent article according to the first embodiment; Figure 2 is a schematic cross-sectional view taken along the line X-X in Figure 1; and Figure 3 is a schematic cross-sectional view showing the arrangement of the first composite nonwoven fabric layer, the second composite nonwoven fabric layer, and the superabsorbent polymer.

The absorbent article 1 according to this embodiment comprises a liquid-permeable top sheet 20 positioned on the skin side when the absorbent article 1 is worn, a liquid-impermeable back sheet 30 positioned opposite the top sheet 20 and on the non-skin side when the absorbent article 1 is worn, an absorbent body 10 positioned between the top sheet 20 and the back sheet 30, and a pair of three-dimensional gathers 40 provided on the skin-side surface of the top sheet 20. The absorbent body 10 is sandwiched between the top sheet 20 and the back sheet 30, and bodily fluids such as urine are absorbed and retained by the absorbent body 10 through the top sheet 20. Depending on the application and type of the absorbent article 1, leg gathers, waist gathers, side flaps, etc., can be appropriately provided.

The absorbent body 10 absorbs and retains the bodily fluids of the wearer of the absorbent article 1. It is a laminate comprising a first absorbent body 11 containing fluff pulp as an absorbent base material, and a second absorbent body 12 that does not contain fluff pulp. The second absorbent body 12 includes a highly absorbent sheet 13, which is wrapped in a hydrophilic sheet 17. The absorbent body 10 is arranged such that the first absorbent body 11 is located on the top sheet 20 side, and the second absorbent body 12 is located on the back sheet 30 side.

The superabsorbent sheet 13 comprises a first composite nonwoven fabric layer 14 in which a pulp fiber web is laminated on the surface of a spunbond nonwoven fabric, a second composite nonwoven fabric layer 15 in which a pulp fiber web is laminated on the surface of a spunbond nonwoven fabric, and a superabsorbent polymer 16 disposed between the first composite nonwoven fabric layer 14 and the second composite nonwoven fabric layer 15. The superabsorbent sheet 13 is provided with an opening 18 extending in the longitudinal direction.

By incorporating such an absorbent material 10, the absorbent article 1 exhibits high absorption capacity, maintains a consistent absorption rate during repeated use, minimizes backflow, and provides excellent diffusion of bodily fluids, resulting in a comfortable wearing experience. Furthermore, when the absorbent article 1 is used in thin, disposable diapers, it is usually desirable to make the absorbent material 10, which typically constitutes the majority of the diaper, thinner. By using this absorbent material 10, it is possible to achieve both a thinner and lighter absorbent article 1.

Unless otherwise specified, "wearing absorbent article 1" refers to at least one of the periods during and after wearing absorbent article 1. "Wearing" refers to the state in which absorbent article 1 is attached to the body. Absorbent article 1 is usually worn on the body inside clothing, but it may also be worn on the body so that at least a portion of it is exposed to the outside.

Furthermore, the absorbent article 1 can be suitably used as a light incontinence product, urine pad, pant-type disposable diaper, tape-fastening disposable diaper, etc., whether for babies or adults, but is not limited to these, and can also be other absorbent articles. It is also possible to use various types of disposable diapers as outer layers and the absorbent article 1 as an inner layer in combination. Therefore, the absorbent article 1 may be provided with three-dimensional gathers 40 to prevent leakage of bodily fluids, depending on its intended use.

Furthermore, the longitudinal direction of the absorbent article 1 refers to the length direction of the absorbent article 1, and the width direction of the absorbent article 1 is the direction perpendicular to the longitudinal direction. The thickness direction of the absorbent article 1 refers to the lamination direction of each component, such as the top sheet 20, absorbent body 10, and back sheet 30. The skin-facing side refers to the side of each component of the absorbent article 1 that faces the wearer's skin when worn, and the non-skin-facing side refers to the side of each component that faces the wearer's clothing when worn. Body fluids refer to liquids expelled from the body, such as urine, blood, and water in loose stools.

The longitudinal dimension of the absorbent article 1 is not particularly limited, but for example, it is in the range of 100 to 800 mm. Similarly, the width dimension of the absorbent article 1 is not particularly limited, but for example, it is in the range of 50 to 500 mm. By adjusting the dimensions of the absorbent article 1 within these ranges, it is possible to create an absorbent article 1 suitable for light incontinence pads, urine absorption pads, pant-type disposable diapers, tape-fastened disposable diapers, etc.

The following provides a more detailed explanation of each component. Note that these components may have three-dimensional structures other than sheet-like and plate-like forms.

<Top Sheet>

The top sheet 20 is provided to cover the entire surface of the absorbent 10, but is not limited to this configuration. For example, a configuration in which a portion of the absorbent 10 is exposed (or, if a hydrophilic sheet is provided as described later, a portion of the hydrophilic sheet 17 is exposed) is also possible.

The top sheet 20 can be made of a liquid-permeable substrate that allows bodily fluids to move to the absorbent 10. Examples of liquid-permeable top sheets 20 include hydrophilic nonwoven fabrics such as air-through nonwoven fabrics, thermal-bonded nonwoven fabrics, and spunbond nonwoven fabrics; composite nonwoven fabrics formed by laminating the same or different types of nonwoven fabrics, such as thermal-bonded/spunbond; foamed films made of urethane foam, polyethylene foam, etc.; and composite sheets formed by laminating two or more of these. Among these, thermal-bonded nonwoven fabrics, spunbond nonwoven fabrics, and thermal-bonded/spunbond composite nonwoven fabrics are preferred from the viewpoint of the transfer of bodily fluids to the absorbent 10 (liquid permeability) and the diffusion of bodily fluids within the absorbent article 1.

The top sheet 20 may be embossed or perforated on its surface to improve liquid permeability. Embossing and perforation can be carried out by known methods. Furthermore, to reduce skin irritation, the top sheet 20 may contain lotion, antioxidants, anti-inflammatory components, pH adjusters, antibacterial agents, moisturizers, etc.

The basis weight of the top sheet 20 is not particularly limited, but from the viewpoint of strength, processability, and liquid return rate, it is preferably 18 g to 400 g/ ^m² . The shape of the top sheet 20 is not particularly limited, but it should be a shape that can guide bodily fluids to the absorbent 10 so that they do not leak out. From this viewpoint, it is preferable that the top sheet 20 is arranged to cover the absorbent 10.

<Three-dimensional gathers>

Furthermore, as shown in Figure 1, the absorbent article 1 is equipped with a pair of three-dimensional gathers 40 along the longitudinal direction of the absorbent article 1, on both ends of the skin-facing side of the top sheet 20, to prevent lateral leakage of bodily fluids excreted by the user. One end of the three-dimensional gather 40 in the width direction of the absorbent article 1 is fixed near both ends of the skin-facing side (or near both ends of the non-skin-facing side) of the back sheet 30. The three-dimensional gather 40 is also positioned such that its middle portion in the width direction is fixed near both ends of the skin-facing side of the top sheet 20, while its other end in the width direction is a free end 41 not fixed to the top sheet 20.

By providing an elastic stretchable member for three-dimensional gathering along the longitudinal direction near the free end 41, the free end 41 of the three-dimensional gather 40 can be given uprightness, allowing it to deform to conform to the wearer's body shape. Examples of fixing positions for one end of the three-dimensional gather 40 in the width direction include both ends in the width direction of the non-skin side of the back sheet 30, both ends in the width direction of the bag formed by partially or completely joining the top sheet 20 and the back sheet 30, and both ends in the width direction of the skin side of the top sheet 20. Note that this embodiment also includes configurations of the absorbent article 1 that do not include the three-dimensional gather 40.

For the elastic stretch material used for three-dimensional gathers, for example, polyurethane yarn, a strip of polyurethane film, or thread-like or strip-like natural rubber are used. For the three-dimensional gather sheet, a water-repellent or liquid-impermeable nonwoven fabric formed from hydrophobic fibers is used, such as spunbond nonwoven fabric, meltblown nonwoven fabric, or a composite nonwoven fabric which is a laminate of spunbond nonwoven fabric/meltblown nonwoven fabric/spunbond nonwoven fabric.

<Backseat>

The backsheet 30 can be made of a breathable or non-breathable liquid-impermeable base material to prevent the bodily fluids held by the absorbent 10 from wetting clothing or adhering to the skin surface. Examples of liquid-impermeable backsheets 30 include resin films and composite sheets, which are laminates of resin films and nonwoven fabrics. Examples of resin films include films made from synthetic resins such as polyester, polyvinyl alcohol, polyethylene, and polypropylene, and composite films of polyethylene and polypropylene. Examples of nonwoven fabrics used in composite sheets include spunbond nonwoven fabrics, meltblown nonwoven fabrics, composite nonwoven fabrics, which are laminates of spunbond nonwoven fabrics and meltblown nonwoven fabrics, and composite nonwoven fabrics, which are laminates of spunbond nonwoven fabrics and meltblown nonwoven fabrics.

The basis weight of the backsheet 30 is not particularly limited, but from the viewpoint of strength and processability, it is preferably 15 to 40 g/ ^m² . Furthermore, from the viewpoint of preventing stuffiness when worn, it is preferable that the backsheet 30 be breathable. The method for imparting breathability to the backsheet 30 is not particularly limited, and known methods can be used. For example, methods include making the resin film that serves as the base material of the backsheet 30 porous, or embossing the base material of the backsheet 30. An example of a method for making the resin film porous is to incorporate a filler into the resin to form a film, and then remove the filler from the resulting film. Examples of fillers include inorganic salts such as calcium carbonate.

<Absorbent material>

The absorbent 10 according to this embodiment is a laminate of a first absorbent 11 positioned relatively towards the top sheet 20 and a second absorbent 12 positioned relatively towards the back sheet 30.

(First absorber)

The first absorbent body 11 is an absorbent body containing fluff pulp (not shown) as an absorbent base material, and preferably an absorbent body containing fluff pulp as an absorbent base material and a superabsorbent polymer (not shown) as an absorbent component.

Examples of fluff pulp include wood pulp, synthetic fibers, polymer fibers, and non-wood pulp that have been defibrated into a cotton-like form. From the viewpoint of absorbency and feel, the basis weight of the fluff pulp is, for example, in the range of 50 to 800 g/ ^m² . In this embodiment, other absorbent base materials can be used together with the fluff pulp. Other absorbent base materials are not particularly limited as long as they are used in absorbent articles such as sanitary napkins, diapers, and incontinence pads, but examples include cotton, rayon, acetate, tissue, absorbent paper, and hydrophilic nonwoven fabrics.

The superabsorbent polymer (also called "SAP") used in the first absorbent body 11 is not particularly limited as long as it can absorb body fluids and prevent backflow of body fluids. Examples include polyacrylates, polyaspartates, (starch-acrylic acid) graft copolymers, (acrylic acid-vinyl alcohol) copolymers, (isobutylene-maleic anhydride) copolymers, and their saponified products. Among these, polyacrylates are preferred, and sodium polyacrylate is more preferred, from the viewpoint of absorption per unit weight. SAP may be used alone or in combination of two or more types.

As for the form of the SAP, for example, from the viewpoint of suppressing the occurrence of gel blocking, it is preferable that it be in particulate form, and more preferably in particulate form having a medium particle size. The medium particle size of the superabsorbent polymer is preferably in the range of 50 to 600 μm, and more preferably in the range of 50 to 550 μm. From the viewpoint of absorption performance and feel, the basis weight of the SAP in the first absorbent 11 is preferably in the range of 10 to 500 g/ ^m² . Furthermore, the SAP content in the absorbent 10 is preferably in the range of 15 to 50% by mass of the total amount of the first absorbent 11.

The first absorbent 11 can take the form of, for example, a laminated mat formed by mixing and dispersing SAP particles in an absorbent substrate. Furthermore, from the viewpoint of preventing the SAP particles from falling off and stabilizing the shape of the first absorbent 11, the first absorbent 11 may be wrapped in a carrier sheet. Examples of carrier sheets include tissue paper, absorbent paper, and hydrophilic nonwoven fabrics such as airlaid nonwoven fabric. The shape and dimensions of the first absorbent 11 are consistent with those of the absorbent 10.

(Second absorber)

The second absorbent body 12 is a laminate that does not contain fluff pulp as an absorbent base material and includes a highly absorbent sheet 13. The highly absorbent sheet 13 has a first composite nonwoven fabric layer 14 in which a pulp fiber web is laminated on the surface of a spunbond nonwoven fabric, and a second composite nonwoven fabric layer 15 in which a pulp fiber web is laminated on the surface of a spunbond nonwoven fabric, with a highly absorbent polymer 16 disposed between these layers.

Furthermore, the highly absorbent sheet 13 is provided with an opening 18 extending in the longitudinal direction. From the viewpoint of fluid diffusion, the width dimension of the opening 18 is preferably 1 to 15 mm. More preferably, the lower limit of this dimension is 5 mm or more. Furthermore, the upper limit of this dimension is more preferably 12 mm or less. The longitudinal dimension of the opening 18 is preferably 50 to 95% of the maximum longitudinal dimension of the highly absorbent sheet 13. More preferably, the lower limit of this ratio is 60% or more. Furthermore, the upper limit of this ratio is more preferably 80% or less. Additionally, multiple openings 18 may be provided in the width direction of the highly absorbent sheet 13. In this case, the spacing between the openings 18 in the width direction is preferably 30 to 120 mm. More preferably, the lower limit of this spacing is 60 mm or more. Furthermore, the upper limit of this spacing is more preferably 100 mm or less.

As shown in Figure 2, it is preferable that the second absorbent 12 further includes a hydrophilic sheet 17 that covers at least a portion of the surface of the highly absorbent sheet. Although not shown in the figure, the second absorbent 12 may also be a laminate of multiple layers of highly absorbent sheets 13, which are then wrapped in the hydrophilic sheet 17.

The first composite nonwoven fabric layer 14 and the second composite nonwoven fabric layer 15 (hereinafter, these may be collectively referred to as composite nonwoven fabric layers 14 and 15) include a spunbond nonwoven fabric and a pulp fiber web laminated on the surface of the spunbond nonwoven fabric. Preferably, the composite nonwoven fabric layers 14 and 15 include a spunbond nonwoven fabric and a pulp fiber web integrated onto at least one surface of the spunbond nonwoven fabric. Here, "integrated" means that the spunbond nonwoven fabric and the pulp fiber web are not partially separated, even before and after use of the absorbent article 1, so that their function is not significantly reduced.

The composite nonwoven fabric layers 14 and 15 can be manufactured, for example, by a manufacturing method that includes a step of laminating and integrating a spunbond nonwoven fabric and a pulp fiber web, and a step of pressurizing and/or heating the resulting laminate using a roll or the like as needed. Alternatively, the spunbond nonwoven fabric and the pulp fiber web may be integrated by bonding with an adhesive or by sewing. Furthermore, the composite nonwoven fabric layers 14 and 15 can also be obtained by a manufacturing method that includes a water jet entanglement step in which pulp fibers constituting the pulp fiber web are sprayed onto the spunbond nonwoven fabric along with a water jet. The composite nonwoven fabric layers 14 and 15 may be embossed.

Among these manufacturing methods, the method using the water jet entanglement method is preferred from the viewpoint of achieving both softness in appearance and feel, and strength. In the water jet entanglement process, from the viewpoint of balancing appearance, softness in feel, and efficiency, the hole diameter of the water jet nozzles that spray the water jet is preferably 0.06 to 0.15 mm, and the spacing between the water jet nozzles is preferably 0.4 to 1.0 mm.

In other words, a preferred embodiment of the composite nonwoven fabric layers 14 and 15 is one in which the materials are integrated by water entanglement. Specifically, it is preferable that the surface of the superabsorbent sheet 13 that contacts the superabsorbent polymer 16 is such that the spunbond nonwoven fabric and pulp fiber web are entangled by water. Such an integrated material by water entanglement can be obtained, for example, by entangling wood pulp fibers with a water jet on the surface of the spunbond nonwoven fabric without using a binder, thereby integrating them and creating a pulp-containing composite nonwoven fabric with a pulp fiber web.

When the composite nonwoven fabric layers 14 and 15 are such pulp-containing composite nonwoven fabrics, on one surface of the spunbond nonwoven fabric, the fibers constituting the spunbond nonwoven fabric and the wood pulp fibers become intertwined, integrating the pulp fiber web. Furthermore, some of the wood pulp fibers penetrate the spunbond nonwoven fabric in the thickness direction and are exposed on the other surface, allowing for a strong bond between the spunbond nonwoven fabric and the pulp fiber web.

Furthermore, since irregularities are formed on the water-entangled surfaces (water-entangled surfaces) of the composite nonwoven fabric layers 14 and 15, these irregularities can hold the superabsorbent polymer 16, as described later. This prevents uneven distribution due to displacement of the superabsorbent polymer 16 on the composite nonwoven fabric layers 14 and 15. For example, when using a conventional superabsorbent sheet (SAP sheet) filled with superabsorbent polymer as an absorbent, the superabsorbent polymer filled inside the absorbent can shift position due to the wearer's movements during wear, resulting in uneven distribution of the superabsorbent polymer, leading to problems such as reduced absorbency and poor wearing comfort. However, this embodiment prevents such problems.

Regarding the composite nonwoven fabric layers 14 and 15, in a tensile strength test using Tensilon, the force (tensile strength) required to stretch a 25 mm wide test specimen by 2 mm in the longitudinal direction is not particularly limited, but it is preferably 1.5 to 5.0 N/25 mm.

Regarding the composite nonwoven fabric layers 14 and 15, the weight composition ratio (nonwoven fabric/pulp fiber web; based on mass%) of the spunbond nonwoven fabric and the pulp fiber web is preferably in the range of 40/60 to 10/90. A weight composition ratio of 40/60 or higher allows for sufficient filling of the pulp fiber web, resulting in improved texture, sweat absorption, and reduced stuffiness. Furthermore, a weight composition ratio of 10/90 or lower prevents the composite nonwoven fabric layers 14 and 15 from becoming too hard, resulting in superior softness. From this perspective, a lower limit of this weight composition ratio is more preferably 35/65 or higher. A higher limit of this weight composition ratio is more preferably 25/75 or lower.

The following describes the spunbond nonwoven fabric and pulp fiber web that constitute the composite nonwoven layers 14 and 15.

By using spunbond nonwoven fabric, the support for the pulp fiber web, as well as the overall strength, softness, and texture of the composite nonwoven fabric layers 14 and 15, are improved. From this perspective, it is preferable to use spunbond nonwoven fabric made from at least one synthetic resin selected from the group consisting of nylon (trademark name), vinylon, polyester, acrylic resin, polyethylene, polypropylene, and polystyrene. For example, spunbond nonwoven fabric can be made from synthetic resin fibers of these materials, or it can be made from two or more types of synthetic resin fibers.

Furthermore, the manufacturing method of the spunbond nonwoven fabric is not particularly limited; for example, nonwoven fabrics produced by the spunbond method, melt-blown method, or flash spinning method can be used. In addition, the spunbond nonwoven fabric may be hydrophilically treated with a known hydrophilic agent such as a surfactant. Such hydrophilic treatment makes it easier for bodily fluids to pass through the spunbond nonwoven fabric and reach the pulp fiber web.

The basis weight of the spunbond nonwoven fabric is preferably in the range of 7 to 20 g/ ^m² . The lower limit is more preferably 10 g/ ^m² or more. The upper limit is more preferably 17 g/ ^m² or less. The basis weight of the pulp fiber web is preferably in the range of 30 to 50 g/ ^m² . The lower limit is more preferably 35 g/ ^m² or more. The upper limit is more preferably 45 g/ ^m² or less. By setting the basis weights of the spunbond nonwoven fabric and the pulp fiber web within these ranges, it becomes easy to adjust the basis weight of the composite nonwoven fabric layers 14 and 15 to an appropriate range.

Because the pulp fiber web has excellent bodily fluid absorbency, it can quickly diffuse bodily fluids that have locally passed through, for example, the spunbond nonwoven fabric, allowing them to easily spread throughout the entire surface of the absorbent 10. Therefore, it is preferable that the spunbond nonwoven fabric be located on the outside of the absorbent 10 and the pulp fiber web be located on the inside.

The pulp fiber web can be made of any nonwoven fabric primarily composed of pulp fibers without any particular limitations. While the pulp fibers are not particularly limited, bleached kraft pulp (NBKP) from coniferous trees such as radiata pine, slush pine, southern pine, lodgepole pine, spruce, and Douglas fir is preferred. NBKP may be used alone or in combination of two or more types. Furthermore, while the basis weight of the pulp fiber web is not particularly limited, it is preferably 30 to 70 g/ ^m² from the viewpoint of uniformity, feel, and absorbency.

The first composite nonwoven fabric layer 14 and the second composite nonwoven fabric layer 15 may have the same layer structure or different layer structures.

The superabsorbent polymer (SAP) 16, positioned between the first composite nonwoven fabric layer 14 and the second composite nonwoven fabric layer 15, only needs to be capable of absorbing bodily fluids and preventing their backflow; its material is not particularly limited. Examples of materials for the superabsorbent polymer 16 include polyacrylates, polyaspartates, (starch-acrylic acid) graft copolymers, (acrylic acid-vinyl alcohol) copolymers, (isobutylene-maleic anhydride) copolymers, and their saponified products. Among these, polyacrylates are preferred, and sodium polyacrylate is more preferred, from the viewpoint of absorption per unit weight.

Furthermore, by avoiding the use of finely powdered superabsorbent polymer 16, which has poor fluidity as a powder, the basic performance related to absorption is enhanced, and from the viewpoint of reducing the rough or gritty texture caused by the hardening of the second absorbent 12, the median particle size of the superabsorbent polymer 16 is preferably 50 to 600 μm, and more preferably 100 to 500 μm.

For example, by placing a superabsorbent polymer 16 at a predetermined basis weight on the surface of the pulp fiber web in the first composite nonwoven fabric layer 14, fixing the superabsorbent polymer 16 in the fixed area, then overlapping the pulp fiber web of the second composite nonwoven fabric layer 15, joining its surrounding edges, and further joining the boundary between the fixed and non-fixed areas, the superabsorbent polymer 16 can be positioned in the predetermined location.

Examples of joining methods include hot-melt adhesive bonding, heat fusion, and ultrasonic bonding. For example, when using a hot-melt adhesive to join the boundary between the bonded and non-bonded areas, the hot-melt adhesive is applied in advance to two predetermined areas extending in the width direction on the pulp fiber web surface of the first composite nonwoven fabric layer 14. Then, after overlapping the pulp fiber webs of the second composite nonwoven fabric layer 15, these two predetermined areas can be heated to bond them.

Furthermore, it is preferable that the second absorbent 12 covers the highly absorbent sheet 13 with a hydrophilic sheet 17. By including the hydrophilic sheet 17 in the second absorbent 12, further stabilization of the shape of the absorbent 10 and further prevention of the detachment of the highly absorbent polymer 16 can be achieved. While the hydrophilic sheet 17 only needs to cover at least a portion of the highly absorbent sheet 13, it is preferable that it covers the entire sheet from the viewpoint of stable arrangement and prevention of detachment of the highly absorbent polymer 16.

The material of the hydrophilic sheet 17 can be anything that is hydrophilic, such as tissue paper, absorbent paper, or hydrophilic nonwoven fabrics like airlaid nonwoven fabric. Multiple hydrophilic sheets 17 may be used; in this case, the base materials of the multiple hydrophilic sheets 17 may be the same or different.

As described above, the absorbent material 10 and the absorbent article 1 equipped therewith, according to this embodiment, are thin, yet possess high absorption capacity, maintain a consistent absorption rate during repeated absorption, have minimal backflow, exhibit excellent diffusion of bodily fluids, and provide a comfortable wearing experience.

As a preferred embodiment of the absorbent body 10 and the absorbent article 1 equipped therewith, regarding the repeated absorption rate, when 150 mL of physiological saline solution is poured three times at 10-minute intervals under load using a jig with a base of 140 × 100 mm , an outer diameter of 40 mm, an inner diameter of 35 mm, and a weight of 1400 g , the time required to absorb the third 150 mL of liquid is preferably less than 50 seconds, more preferably 45 seconds or less, and even more preferably 40 seconds or less. Furthermore, regarding the diffusivity of body fluids, when 150 mL of physiological saline solution is poured three times at 10-minute intervals under load using a jig with a base of 140 × 100 mm, an outer diameter of 40 mm, an inner diameter of 35 mm, and a weight of 1400 g , the maximum length of the area where the physiological saline solution has been absorbed is preferably greater than 280 mm, more preferably 300 mm or more, and even more preferably 320 mm or more.

<Method for Manufacturing Absorbent Articles>

The method for manufacturing the absorbent article 1 is not particularly limited, and conventionally known methods can be employed. For example, an absorbent article 1 can be manufactured by laminating a liquid-permeable top sheet 20, an absorbent 10, and a liquid-impermeable back sheet 30 in this order, and fixing part or all of the circumference of the top sheet 20 and back sheet 30 with a hot-melt adhesive, heat embossing, ultrasonic embossing, or high-frequency embossing. The absorbent article 1 thus obtained can then be individually packaged in a packaging body and folded into thirds along its length.

The present invention will be described in more detail by the following examples and comparative examples, but the present invention is not limited in any way by these examples.

Absorbent material 10 and absorbent article 1 shown in Figures 1 to 3 (Example 1), absorbent material 100 and absorbent article A shown in Figure 4 (Comparative Example 1), absorbent material 200 and absorbent article B shown in Figure 5 (Comparative Example 2), and absorbent material 300 and absorbent article C shown in Figure 6 (Comparative Example 3) were each prepared. For each absorbent material and absorbent article, the total absorption capacity, repeated absorption rate, return volume, diffusion length, and wearing comfort were evaluated using physiological saline solution.

(Example 1)
The top sheet 20, back sheet 30, first composite nonwoven fabric layer 14, and second composite nonwoven fabric layer 15 shown below were prepared to create an absorbent body 10 and an absorbent article 1 having the configuration shown in Figures 1 to 3.

First, a liquid-permeable air-through nonwoven fabric (basis weight 20 g/ ^m² ) was used as the top sheet 20, and a liquid-impermeable breathable polyethylene film (basis weight 35 g/ ^m² ) was used as the back sheet 30.

The second absorbent 12 was then prepared by the following method. First, a spunbond nonwoven fabric (made of polypropylene, basis weight 15 g/ ^m² per sheet) and a pulp fiber web (basis weight 40 g/ ^m² per sheet) were entangled and integrated using a water jet to obtain a pulp-containing composite nonwoven fabric sheet with a spunbond nonwoven fabric/pulp fiber web weight composition ratio (based on mass%) of 30/70. This pulp-containing composite nonwoven fabric sheet obtained by this water jet entanglement method was used as the first composite nonwoven fabric layer 14 and the second composite nonwoven fabric layer 15. In this pulp-containing composite nonwoven fabric sheet, the pulp fiber web was integrated onto the surface of the spunbond nonwoven fabric, and irregularities were formed on the water jet entanglement surface. Furthermore, in a tensile strength test using Tensilon, the force required to stretch a 25 mm wide test piece by 2 mm in the longitudinal direction was measured for this pulp-containing composite nonwoven fabric sheet, and it was confirmed that the required force was within the range of 1.5 to 5.0 N/25 mm.

Next, a superabsorbent polymer (SAP; made of sodium polyacrylate, basis weight 380 g/m²) was dispersed on a spunbond nonwoven fabric on which the pulp fiber webs of the first composite nonwoven fabric layer ¹⁴ and the second composite nonwoven fabric layer 15 were provided. Then, by overlapping and fixing these together, a superabsorbent sheet 13 was obtained.

Furthermore, an air-through nonwoven fabric (width 140 mm, length 300 mm, basis weight 50 g/ ^m² ), which is the hydrophilic sheet 17, was folded in three inwards, and the highly absorbent sheet 13 was placed on top of it. Then, the entire surface of the highly absorbent sheet 13 was covered by the hydrophilic sheet 17 to obtain a second absorbent body 12 (see "Composite Nonwoven Fabric + SAP" in Table 1, and Figure 3).

The first absorbent 11 ("fluff pulp + SAP") and the second absorbent 12 ("composite nonwoven fabric + SAP") shown in Table 1 were laminated and partially fixed with hot-melt adhesive to obtain an absorbent 10. Using the obtained absorbent 10, a top sheet 20, and a back sheet 30, an absorbent article 1 having the configuration shown in Figures 1 to 3 was obtained. Note that the SAP used in the first absorbent 11 is the same SAP used in the second absorbent 12.

(Comparative Example 1)
Except for changing the conditions shown in Table 1, an absorbent body 100 and absorbent article A having the configuration shown in Figure 4 were obtained in the same manner as in Example 1. The first absorbent body 110 of absorbent article A is the same as the second absorbent body 12 of absorbent article 1 in Example 1 (see Table 1). The second absorbent body 120 of absorbent article A is the same as the first absorbent body 11 of absorbent article 1 in Example 1 (see Table 1). In other words, the only difference from Example 1 is the vertical arrangement of the first absorbent body 11 and the second absorbent body 12.

(Comparative Example 2)
Except for changing the conditions shown in Table 1, an absorbent body 200 and absorbent article B having the configuration shown in Figure 5 were obtained in the same manner as in Example 1. The first absorbent body 210 of absorbent article B is the same as the first absorbent body 11 of absorbent article 1 in Example 1 (see Table 1). The second absorbent body 220 of absorbent article B is an absorbent body having the fluff pulp amount and SAP amount shown in Table 1.

(Comparative Example 3)
Except for changing the conditions shown in Table 1, an absorbent body 300 and an absorbent article C having the configuration shown in Figure 6 were obtained in the same manner as in Example 1. The first absorbent body 310 of absorbent article C is an absorbent body having the fluff pulp amount and SAP amount shown in Table 1. The second absorbent body 320 of absorbent article C is the same as the first absorbent body 11 of absorbent article 1 in Example 1 (see Table 1).

For each absorbent material and absorbent article obtained in Example 1 and Comparative Examples 1-3, the product thickness, total absorption capacity, repeated absorption rate, liquid return amount, diffusion length, and wearing comfort were evaluated according to the following method.

(Measurement of product thickness)
The thickness of each absorbent article in Example 1 and Comparative Examples 1 to 3 was measured under a load of 70 gf/ ^cm² .

(Measurement of total absorption)
Each absorbent material from Example 1 and Comparative Examples 1-3, whose weight had been measured beforehand, was immersed in physiological saline for 5 minutes so that it was completely submerged. After 5 minutes of immersion, the absorbent material was placed on a wire mesh to drain for 30 seconds, and the weight after absorption was measured. The total absorbed amount (g) was determined by measuring the weight difference before and after absorption.

(Measurement of repeated absorption rate)
Using a jig with a base of 140 x 100 mm , an outer diameter of 40 mm, an inner diameter of 35 mm , and a weight of 1400 g , 150 mL of physiological saline solution was injected under load three times at 10-minute intervals, and the time required to absorb the third injection of 150 mL was measured.

(Measurement of liquid return volume)
Ten minutes after the end of the third water injection measurement in the repeated absorption rate measurement test, the amount of water absorbed back into a circular qualitative filter paper (ADVANTEC No. 2, 55 mm in diameter, manufactured by Advantec Toyo Co., Ltd.) in one minute was measured under a load condition of ³⁵ gf/cm².

(Measurement of diffusion length)
In the repeated absorption rate measurement test, the maximum length of the region that absorbed physiological saline was measured after the third measurement of water injection.

(Comfort of wearing, from putting it on to replacing it)
A monitor test was conducted with 20 participants, and the wearing comfort was evaluated according to the following criteria.
○: Between 16 and 20 people said it felt comfortable to wear.
△: Between 11 and 15 people reported that the product felt comfortable to wear.
×: No one responded with "comfortable to wear," or there were between 1 and 10 respondents who responded with "good fit."

Table 1 shows the conditions for each absorbent article (product) and absorbent material in Example 1 and Comparative Examples 1-3, as well as their evaluation results.

As shown in Table 1, it was confirmed that the absorbent article 1 of Example 1, despite being thin, has a high absorption capacity, maintains its absorption rate during repeated absorption, has a low amount of backflow, and exhibits excellent diffusion of body fluids, resulting in a comfortable wearing experience.
<Note>
Furthermore, the following matters are disclosed as an addendum regarding this embodiment.
<Note 1>
An absorbent material used in an absorbent article, which absorbs and retains the bodily fluids of the wearer of the absorbent article, comprising a laminate containing a first absorbent material containing fluff pulp as an absorbent base material, which is disposed on the wearer's skin side, and a second absorbent material not containing fluff pulp, wherein the second absorbent material comprises a highly absorbent sheet, the highly absorbent sheet comprising a first composite nonwoven fabric layer in which a pulp fiber web is laminated on the surface of a spunbond nonwoven fabric, a second composite nonwoven fabric layer in which a pulp fiber web is laminated on the surface of a spunbond nonwoven fabric, and a highly absorbent polymer disposed between the first composite nonwoven fabric layer and the second composite nonwoven fabric layer, the highly absorbent sheet being provided with an opening extending in the longitudinal direction.
<Note 2>
The second absorbent is the absorbent described in <Note 1>, further comprising a hydrophilic sheet covering at least a portion of the surface of the highly absorbent sheet.
<Note 3>
The first composite nonwoven fabric layer and/or the second composite nonwoven fabric layer are absorbents as specified in <Note 1> or <Note 2>, wherein the force required to stretch a 25 mm wide test specimen by 2 mm in the longitudinal direction in a tensile strength test using Tensilon is 1.5 to 5.0 N/25 mm.
<Note 4>
The first composite nonwoven fabric layer and/or the second composite nonwoven fabric layer is an absorbent according to any of the <Appendix 1> to <Appendix 3>, wherein the material of the spunbond nonwoven fabric is at least one selected from the group consisting of nylon, vinylon, polyester, acrylic resin, polyethylene, polypropylene, and polystyrene.
<Note 5>
The first composite nonwoven fabric layer and/or the second composite nonwoven fabric layer is an absorbent as specified in any of the <Appendix 1> to <Appendix 4>, wherein the basis weight of the spunbond nonwoven fabric is 7 to 20 g/m² ^, the basis weight of the pulp fiber web is 30 to 70 g/m² ^, and the weight composition ratio of the spunbond nonwoven fabric to the pulp fiber web is 40/60 to 10/90.
<Note 6>
The first composite nonwoven fabric layer and/or the second composite nonwoven fabric layer is an absorbent according to any of the <Note 1> to <Note 5>, wherein the surface of the superabsorbent sheet in contact with the superabsorbent polymer is such that the spunbond nonwoven fabric and the pulp fiber web are entangled by water flow, and irregularities are formed on the water-entangled surface of the composite nonwoven fabric layer, and the irregularities hold the superabsorbent polymer.
<Note 7>
The absorbent material is one of the <Appendix 1> to <Appendix 6>, wherein the width dimension of the opening of the superabsorbent sheet is 1 to 15 mm.
<Note 8>
The absorbent material is one of the following, specified in Appendix 1 to Appendix 7, wherein the openings of the highly absorbent sheet are provided in multiple locations in the width direction, and the spacing between the openings in the width direction is 30 to 120 mm.
<Note 9>
The absorbent material is one of the <Appendix 1> to <Appendix 8>, wherein the longitudinal dimension of the opening of the superabsorbent sheet is 50 to 95% of the maximum longitudinal dimension of the superabsorbent sheet.
<Note 10>
An absorbent article comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, and one of the absorbents specified in <Appendix 1> to <Appendix 9> placed between the top sheet and the back sheet, wherein the absorbents are arranged such that the first absorbent is located on the top sheet side, which is on the skin side of the wearer, and the second absorbent is located on the back sheet side, which is on the non-skin side of the wearer.

1: Absorbent article, 10: Absorbent body, 11: First absorbent body, 12: Second absorbent body, 13: Superabsorbent sheet, 14: (First) composite nonwoven fabric layer, 15: (Second) composite nonwoven fabric layer, 16, 16a, 16b, 16c, 16d: Superabsorbent polymer, 17: Hydrophilic sheet, 18: Opening (of the second absorbent body), 20: Top sheet, 30: Back sheet, 40: Three-dimensional gather, 41: Free end (of the three-dimensional gather), A, B, C: Absorbent article, 100, 200, 300: Absorbent body, 110, 210, 310: First absorbent body, 120, 220, 320: Second absorbent body

Claims (5)

An absorbent material used in absorbent articles, which absorbs and retains the bodily fluids of the wearer of the absorbent article,
The first absorbent body, which contains fluff pulp as an absorbent base material, is placed on the skin side of the wearer,
The laminate includes a second absorbent material, which does not contain fluff pulp, and is positioned on the non-skin side of the wearer.
The second absorbent includes a highly absorbent sheet.
The superabsorbent sheet comprises a spunbond nonwoven fabric, a first composite nonwoven fabric layer including a pulp fiber web integrated on at least one surface of the spunbond nonwoven fabric, a second composite nonwoven fabric layer including a spunbond nonwoven fabric and a pulp fiber web integrated on at least one surface of the spunbond nonwoven fabric, and a superabsorbent polymer disposed between the first composite nonwoven fabric layer and the second composite nonwoven fabric layer.
The first composite nonwoven fabric layer and/or the second composite nonwoven fabric layer are
The surface of the superabsorbent sheet that is in contact with the superabsorbent polymer is such that the spunbond nonwoven fabric and the pulp fiber web are entangled by water flow.
The surface of the composite nonwoven fabric layer where water flow is intertwined has irregularities formed on it, and these irregularities hold the superabsorbent polymer.
The aforementioned highly absorbent sheet has two openings extending in the longitudinal direction in the width direction.
The spacing between the openings in the width direction is 60 to 100 mm.
The width dimension of the opening in the aforementioned highly absorbent sheet is 5 to 12 mm.
The longitudinal dimension of the opening in the superabsorbent sheet is 60 to 80% of the maximum longitudinal dimension of the superabsorbent sheet.
Absorbent material. The second absorbent further comprises a hydrophilic sheet covering at least a portion of the surface of the highly absorbent sheet.
The absorbent according to claim 1. The first composite nonwoven fabric layer and/or the second composite nonwoven fabric layer are
The material of the spunbond nonwoven fabric is at least one selected from the group consisting of nylon, vinylon, polyester, acrylic resin, polyethylene, polypropylene, and polystyrene.
The absorbent according to claim 1 or 2. The first composite nonwoven fabric layer and/or the second composite nonwoven fabric layer are
The basis weight of the aforementioned spunbond nonwoven fabric is 7 to 20 g/ ^m² .
The basis weight of the pulp fiber web is 30 to 70 g/ ^m² , and
The weight composition ratio of the spunbond nonwoven fabric to the pulp fiber web is 40/60 to 10/90.
The absorbent according to any one of claims 1 to 3. A liquid-permeable top sheet,
A liquid-impermeable backsheet,
An absorbent according to any one of claims 1 to 4 , disposed between the top sheet and the back sheet,
Equipped with,
The absorbents are arranged such that the first absorbent is located on the top sheet side, which is on the skin side of the wearer, and the second absorbent is located on the back sheet side, which is on the non-skin side of the wearer.
Absorbent material.