Nonwoven fabric

Abstract

To provide a nonwoven fabric having apertures capable of being controlled to open and close depending on a prescribed condition.SOLUTION: A nonwoven fabric according to an embodiment of the invention contains shape memory fibers and includes a nonwoven fabric body and a plurality of apertures. Each of the plurality of apertures has an aperture body opening in a thickness direction of the nonwoven fabric and a lid part constituted so as to be able to cover the aperture body. The lid part has a connection part connected to the nonwoven fabric body. Each of the plurality of apertures is constituted so as be changed from an open shape in which the aperture body is opened due to bending in a thickness direction of the connection part to a closed shape in which an aperture area in a plan view is smaller than that of the open shape when the nonwoven fabric is immersed in hot water at 40°C for 30 seconds.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a nonwoven fabric containing shape-memory fibers, an absorbent article including the same, and a method for producing the nonwoven fabric. [Background technology]

[0002] A technology for forming a nonwoven fabric using fibers having shape memory is known. Patent Document 1 discloses a fiber sheet having shape memory, characterized by having a natural fiber and / or synthetic fiber sheet and a coating layer of a powder made of a shape memory polymer. Patent Document 2 discloses a composite binder fiber capable of forming a nonwoven fabric, characterized by being composed of a copolyester having a shape memory ability with a glass transition point of 37°C or less and a melting point of 150°C or more and a polymer having a melting point 20°C or more lower than that of the copolyester. Patent Document 3 discloses an article including a nonwoven fiber web and a strip bonded to the nonwoven fiber web, the strip including a shape memory polymer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 02-118178 [Patent Document 2] Japanese Patent Application Publication No. 05-279922 [Patent Document 3] Patent No. 5774020 Summary of the Invention [Problem to be solved by the invention]

[0004] However, no nonwoven fabric having shape-memory ability and having openings that can be opened and closed by a stimulus such as warm water is known.

[0005] The present invention relates to a nonwoven fabric having apertures which can be controlled to be opened or closed under predetermined conditions. [Means for solving the problem]

[0006] A nonwoven fabric according to one embodiment of the present invention contains shape memory fibers, and has a nonwoven fabric main body and a plurality of openings. Each of the plurality of openings is An aperture body opening in the thickness direction of the nonwoven fabric; and a lid portion configured to be able to cover the aperture body. The lid portion has a connecting portion connected to the nonwoven fabric main body. Each of the plurality of openings is When immersed in 40°C warm water for 30 seconds, the connecting portion is bent in the thickness direction, switching between an open shape in which the opening body is opened, and a closed shape in which the opening area in a planar view is smaller than that of the open shape. Effect of the Invention

[0007] According to the nonwoven fabric of the present invention, the opening and closing of the apertures can be controlled under predetermined conditions. [Brief description of the drawings]

[0008] [Figure 1] 1A and 1B are cross-sectional views of a nonwoven fabric according to a first embodiment of the present invention, in which (A) shows an embodiment in which the pores are open, and (B) shows an embodiment in which the pores are closed. [Diagram 2] 3A and 3B are plan views (reverse views) of the nonwoven fabric as viewed from the second main surface, where (A) shows an embodiment in which the apertures are open, and (B) shows an embodiment in which the apertures are closed. [Diagram 3] 4 is a flowchart showing a method for producing the nonwoven fabric. [Figure 4] FIG. 2 is a diagram showing a schematic diagram of the manufacturing process of the nonwoven fabric, in which the vertical axis indicates the temperature in each process. [Diagram 5] FIG. 2 is a plan view of a first support used in producing the nonwoven fabric. [Figure 6] 5A and 5B are views showing a first protrusion of the first support, in which (A) is a plan view and (B) is a side view. [Figure 7] 5A to 5C are schematic cross-sectional views showing a process in which the original nonwoven fabric is cut open by first protrusions of the first support. [Figure 8] FIG. 2 is a schematic cross-sectional view illustrating the effect of using the nonwoven fabric in an absorbent article. [Figure 9] 1A and 1B are diagrams showing a first convex portion of a first support according to a modified example of the above embodiment, where (A) is a plan view, (B) is a side view, and (C) is a schematic cross-sectional view showing the process of the first convex portion cutting open the original nonwoven fabric. [Figure 10] 2A and 2B are plan views (reverse views) of a nonwoven fabric according to a second embodiment of the present invention, as viewed from the second main surface, where (A) shows an embodiment in which the openings are closed, and (B) shows an embodiment in which the openings are open. [Figure 11] 4 is a flowchart showing a method for producing the nonwoven fabric. [Figure 12] FIG. 2 is a diagram showing a schematic diagram of the manufacturing process of the nonwoven fabric, in which the vertical axis indicates the temperature in each process. [Figure 13] FIG. 2 is a schematic cross-sectional view illustrating the effect of using the nonwoven fabric in an absorbent article. [Figure 14] FIG. 11 is a plan view (reverse view) of a nonwoven fabric according to a third embodiment of the present invention, seen from the second main surface, showing the state before stimulation with warm water or the like. [Figure 15] FIG. 2 is a plan view (reverse view) of the nonwoven fabric as viewed from the second main surface, showing the state after stimulation with warm water or the like. [Figure 16] 4 is a flowchart showing a method for producing the nonwoven fabric. [Figure 17] FIG. 2 is a diagram showing a schematic diagram of the manufacturing process of the nonwoven fabric, in which the vertical axis indicates the temperature in each process. [Figure 18] FIG. 2 is a plan view of a first support used in producing the nonwoven fabric. [Figure 19] FIG. 2 is a schematic cross-sectional view illustrating the effect of using the nonwoven fabric in an absorbent article. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] [Summary of the Invention] The present invention relates to a nonwoven fabric 10 containing shape memory fibers. As illustrated in FIG. 1, the nonwoven fabric 10 has a nonwoven fabric main body 11 and a plurality of openings 20 formed in the nonwoven fabric main body 11. Each opening 20 is characterized in that it switches between an open shape and a closed shape when immersed in 40° C. hot water for 30 seconds. An example of the openings 20 in an open shape is shown in FIG. 1(A). An example of the openings 20 in a closed shape is shown in FIG. 1(B). The switching between the open shape and the closed shape is performed by the action of the shape memory fibers, which causes the nonwoven fabric 10 to return from a temporary shape to a memorized shape.

[0011] The use of the nonwoven fabric 10 is not particularly limited. For example, the nonwoven fabric 10 can be used for at least one type of article selected from absorbent articles, hygiene products such as masks, filters, and cleaning sheets. Furthermore, the nonwoven fabric 10 is preferably a nonwoven fabric 10 for absorbent articles among hygiene products. The absorbent article is, for example, an article configured to be capable of absorbing a user's excretory fluid or bodily fluid, and can be, for example, at least one type selected from disposable diapers, sanitary napkins, panty liners (discharge sheets), and urine pads.

[0012] Next, the properties of shape memory polymers will be described. Shape memory polymers generally have the property that their elastic modulus changes reversibly and largely at a certain deformation temperature such as the glass transition point Tg. For example, by heating a shape memory polymer that has been shaped into a certain shape to a deformation temperature or higher, the shape memory polymer becomes soft and can be easily deformed. When cooled below the deformation temperature in that state, the shape memory polymer can maintain the deformed shape and exhibit shape fixation. When heated again to a deformation temperature or higher, the shape memory polymer autonomously returns to the shape that was initially shaped. This shape returnability is thought to be exhibited, for example, by the formation of physical or chemical bond sites (crosslinking points) that do not change at the deformation temperature when the memorized shape is shaped.

[0013] In the present invention, such properties of the shape memory polymer are utilized to provide a nonwoven fabric 10 in which the openings 20 can be opened and closed by the stimulation of immersion in 40°C hot water for 30 seconds. "Immersing in 40°C hot water for 30 seconds" refers to preparing hot water at 40°C in a container having a sufficient depth, and immersing the entire thickness of the nonwoven fabric 10 in the hot water in this container for 30 seconds. When the nonwoven fabric 10 is large, for example, the nonwoven fabric 10 is cut into a rectangular shape of 10 cm x 10 cm to prepare a sample for measurement, and the entire sample is immersed in the hot water in the container. In the present invention, "immersing in 40°C hot water for 30 seconds" is a condition for clearly defining the switching between the open shape and the closed shape. In this specification, "immersing in 40°C hot water for 30 seconds" and the application of heat energy equivalent thereto are collectively referred to as "stimulus such as hot water".

[0014] As the shape memory polymer contained in the nonwoven fabric 10, a shape memory polymer having a deformation temperature in the vicinity of 40° C. can be selected. Specifically, the deformation temperature of the shape memory polymer contained in the shape memory fiber under conditions in which no moisture is present is preferably 35° C. to 47° C., more preferably 35° C. to 42° C., and even more preferably 36° C. to 41° C. The nonwoven fabric 10 may contain one type of shape memory polymer having a deformation temperature in the above range, or may contain two or more types of shape memory polymers adjusted to have a deformation temperature in the above range.

[0015] The shape memory polymer can be appropriately selected based on the deformation temperature in the above range, and preferably contains one or more polymers selected from, for example, polyester resins (see, for example, JP-A-5-279922), polyurethane resins (see, for example, JP-A-2-118178), transisoprene resins (see, for example, JP-A-55-93806), polynorbornene resins (see, for example, JP-A-59-53528), styrene-butadiene copolymer resins, and mixtures of vinyl resins and acrylic acid resins or synthetic rubbers (see, for example, JP-A-63-17952). In particular, the shape memory polymer is preferably at least one of polyurethane resins or polyester resins, since it is easy to adjust the deformation temperature to the above range. Furthermore, it is more preferable that the shape memory polymer contains a polyurethane resin, since it can exhibit high shape recovery.

[0016] From the viewpoint of fully exerting the shape-recovery effect, nonwoven fabric 10 preferably contains a shape-memory polymer as a main component, but may contain other polymers and / or additives, etc. From the viewpoint of reliably opening and closing apertures 20 by the warm water stimulation, the content of shape-memory polymer in nonwoven fabric 10 is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 100% by mass. In other words, it is more preferable that nonwoven fabric 10 is composed of a shape-memory polymer.

[0017] In addition, the nonwoven fabric 10 preferably contains shape-memory fibers as its constituent fibers, but may contain fibers made of other components. The content of shape-memory fibers in the nonwoven fabric 10 is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 100% by mass. In other words, it is more preferable that the nonwoven fabric 10 is composed of shape-memory fibers.

[0018] The nonwoven fabric 10 may be manufactured by a known nonwoven fabric manufacturing technique. For example, the nonwoven fabric 10 may be a nonwoven fabric selected from an air-through nonwoven fabric, a spunbond nonwoven fabric, a meltblown nonwoven fabric, a spunlace nonwoven fabric, an airlaid nonwoven fabric, a needle-punched nonwoven fabric, and the like.

[0019] The present inventors have considered the above-mentioned properties of the shape memory polymer and have studied specific processing methods for the openings 20. In the course of their investigation, the present inventors have found that when openings are formed in a nonwoven fabric containing shape memory fibers by inserting a pin or the like between the fibers, the area of ​​the openings hardly changes even when the fabric is immersed in 40°C warm water for 30 seconds.

[0020] On the other hand, in the nonwoven fabric containing shape memory fibers, the portion folded along the edge of the support returned to its original flat shape when immersed in warm water at 40° C. for 30 seconds. From this, the present inventors came up with the idea that it is possible to form an opening that can be opened and closed by processing the nonwoven fabric containing shape memory fibers so as to bend a portion of it.

[0021] Therefore, the multiple openings 20 in one embodiment of the present invention are configured as follows. As shown in Fig. 1(A), each of the multiple openings 20 has an opening body 21 that opens in the thickness direction Z of the nonwoven fabric 10, and a lid portion 22 configured to be able to cover each of the multiple openings 20. The lid portion 22 has a connecting portion 23 connected to the nonwoven fabric body 11. Each of the multiple openings 20 is configured so that when immersed in warm water at 40°C for 30 seconds, the connecting portion 23 bends in the thickness direction Z to switch between an open shape in which the opening body 21 is opened, and a closed shape in which the opening area in a plan view is smaller than that of the open shape. Note that Fig. 1(B) shows an example in which the lid portion 22 completely covers the opening body 21.

[0022] In this specification, "planar view" refers to a planar view from the thickness direction Z. "Planar shape" refers to the shape in a planar view. "Area" refers to the area in a planar shape. "Open hole area" refers to the area of ​​the portion of the open hole body 21 that is not covered by the lid portion 22 in a planar view. The "open hole area" is calculated by measuring the areas of any 10 open holes (the maximum number if there are fewer than 10) in the nonwoven fabric 10 and averaging these.

[0023] In each figure, the thickness direction Z indicates the thickness direction of the nonwoven fabric 10. The first planar direction X and the second planar direction Y are directions perpendicular to the thickness direction Z. The first planar direction X is, for example, the MD direction (fiber orientation direction) corresponding to the flow direction during the production of the nonwoven fabric 10. The second planar direction Y is a direction perpendicular to the first planar direction X, for example, the CD direction (direction perpendicular to the fiber orientation direction) perpendicular to the MD direction. The MD direction is, for example, the direction in which many fibers are oriented, and can be distinguished by the fact that the MD direction shows a higher strength than the CD direction in a tensile test. In this specification, the fiber orientation direction may be referred to as the MD direction, and the direction perpendicular to the fiber orientation direction may be referred to as the CD direction.

[0024] Each embodiment of the present invention will be described in detail below. In the first embodiment, an example will be described in which the openings 20 change from an open shape to a closed shape by a stimulus such as hot water. In the second embodiment, an example will be described in which the openings 20 change from a closed shape to an open shape by a stimulus such as hot water. In the third embodiment, an example will be described in which the openings 20 include first openings 20A that change from an open shape to a closed shape by a stimulus such as hot water, and second openings 20B that change from a closed shape to an open shape. The basic configuration of the nonwoven fabric 10 described above is common to each embodiment, so duplicated explanations will be omitted.

[0025] [First embodiment] 1 and 2, the openings 20 according to the first embodiment of the present invention are configured as first openings 20A that switch from an open shape to a closed shape when immersed in warm water at 40° C. for 30 seconds. This embodiment can provide a nonwoven fabric 10A whose opening area decreases in response to a stimulus such as warm water.

[0026] The first openings 20A are formed in the nonwoven fabric body 11. In this embodiment, the nonwoven fabric body 11 is configured as a portion of the nonwoven fabric 10A surrounding the first openings 20A. The nonwoven fabric body 11 has a first main surface 12 and a second main surface 13, each extending on a plane (XY plane) perpendicular to the thickness direction Z. The first main surface 12 is a surface located on the upper side in the thickness direction Z in Figs. 1(A) and (B). The second main surface 13 is a surface located on the lower side in the thickness direction Z in Figs. 1(A) and (B). The second main surface 13 is located, for example, on the side where the first lid portion 22A of the first openings 20A is bent. The first main surface 12 and the second main surface 13 may include a substantially flat portion, as exemplified in Figs. 1(A) and (B). The "substantially flat portion" refers to a portion where the undulations in the thickness direction Z are 25% or less of the entire thickness of nonwoven fabric body 11 when nonwoven fabric 10A is placed on a flat XY plane without the application of external force.

[0027] The first opening portion 20A has a first opening body 21A as the opening body 21 and a first lid portion 22A as the lid portion 22. In this embodiment, the first lid portion 22A is connected to the nonwoven fabric body 11 by a first connecting portion 23A and is configured to be able to cover at least a part of the first opening body 21A. The first connecting portion 23A is configured to be bendable with respect to the nonwoven fabric body 11. The first connecting portion 23A is a portion that serves as a base axis for bending the first lid portion 22A, and specifically, is a portion along a fold line formed when bending. In FIG. 2(B), the first connecting portion 23A is shown by a dashed line. The opening and closing of the first lid portion 22A is controlled by bending and flattening the first connecting portion 23A. The bent state of the first connecting portion 23A corresponds to, for example, an open shape, and the state of the first connecting portion 23A that is flatter than the open shape corresponds to, for example, a closed shape.

[0028] It is preferable that the first lid portion 22A is formed integrally with the nonwoven fabric body 11. "The first lid portion 22A is formed integrally with the nonwoven fabric body 11" means that the first lid portion 22A is not formed of a different nonwoven fabric from the nonwoven fabric body 11, but is formed of the same nonwoven fabric. This eliminates the need for a joint between the first lid portion 22A and the nonwoven fabric body 11, and the first connecting portion 23A is smoothly deformed by stimulation such as warm water. In this case, the first lid portion 22A is formed, for example, by cutting open the area where the first opening portion 20A is to be formed in the original nonwoven fabric before the formation of the first opening portion 20A. At this time, the first connecting portion 23A connected to the nonwoven fabric body 11 can be formed by leaving a part of the area where the first opening portion 20A is to be formed without cutting it off from the nonwoven fabric body 11, rather than cutting off the entire area where the first opening portion 20A is to be formed from the nonwoven fabric body 11.

[0029] In the example shown in Fig. 2(A) and (B), each of the first openings 20A has a pair of first lids 22A. The pair of first lids 22A are adjacent to each other in the closed shape, and face each other across the first opening body 21A in the open shape. Such a pair of first lids 22A is formed by, for example, an H-shaped cut, as will be described in detail later. By the first opening 20A having a pair of first lids 22A, the area of ​​each first lid 22A can be reduced, and the first lid 22A can be opened and closed smoothly. Note that the configuration of the first lid 22A of the first opening 20A is not limited to this. Other configuration examples of the first lid 22A will be described later.

[0030] As shown in FIG. 2(A), the first perforated body 21A is configured as a perforation in a plan view when the first connecting portion 23A is sufficiently bent so that the angle between the first lid portion 22A and the second main surface 13 is 130 degrees or less. The angle is determined by measuring any 10 pieces (the maximum number if less than 10 pieces) in the nonwoven fabric 10, and taking the average value of these (the same applies to the angles of the other lid portions). The planar shape of the first perforated body 21A is not particularly limited, and can be appropriately selected from, for example, a polygonal shape, a circular shape, an elliptical shape, shapes similar thereto, and other shapes. In the example shown in FIG. 2(A), the first perforated body 21A is configured in a rectangular shape. As a result, as shown in FIG. 2(B), the first lid portion 22A is also configured in a polygonal shape such as a rectangular shape, and the first lid portion 22A can be formed by a cut in a simple shape such as an H-shape.

[0031] In this embodiment, the open shape of the first hole 20A is a shape in which the first connecting portion 23A of the first lid portion 22A is bent before the nonwoven fabric 10A is immersed in hot water at 40° C. for 30 seconds, as shown in Figures 1(A) and 2(A). The closed shape of the first hole 20A is a shape in which the open area in a plan view is smaller than the open shape after the nonwoven fabric 10A is immersed in hot water at 40° C. for 30 seconds, as shown in Figures 1(B) and 2(B).

[0032] A method for determining the reduction in the open area of ​​the first hole portion 20A will be described. First, the open area before immersion in warm water is calculated. The open area can be calculated, for example, by placing the nonwoven fabric 10A on an arbitrary flat surface (XY plane) and analyzing an image of the nonwoven fabric 10A captured from above in the thickness direction Z. The open area is defined as the area of ​​the portion of the first hole body 21A that is not covered by the first lid portion 22A. The open area of ​​any 10 first hole portions 20A (the maximum number if less than 10) in the nonwoven fabric 10A is calculated, and the average value of these is measured. This average value is defined as the "open area before immersion in warm water." Next, the open hole area of ​​the nonwoven fabric 10A is calculated by the method described above after immersing it in 40°C hot water for 30 seconds. The open hole areas of any 10 holes (the maximum number if the number is less than 10) that are the same or similar in shape to the first open hole 20A for which the open hole area before immersion in hot water was calculated are calculated, and the average value is measured. This average value is the "open hole area after immersion in hot water." If the open area after immersion in hot water is smaller than the open area before immersion in hot water, it is determined that the open area has been reduced by contact with hot water.

[0033] In the present embodiment, nonwoven fabric 10A has stored therein, for example, a substantially flat shape corresponding to a closed shape. In nonwoven fabric 10A, a bent shape of first connecting portion 23A corresponding to an open shape is imparted by processing. Therefore, in nonwoven fabric 10A, the bent shape of first lid portion 22A is maintained before stimulation by hot water or the like, and returns to the stored flat shape by stimulation by hot water or the like.

[0034] (Manufacturing method) Next, a method for producing the nonwoven fabric 10A according to the present embodiment will be described with reference to Figures 3 and 4. As shown in the flow chart of Figure 3, the method for producing the nonwoven fabric 10A according to the present embodiment includes, for example, an original nonwoven fabric production step S11 and a first cutting step S12. Note that the original nonwoven fabric may be one that has been produced in advance. In this case, the production method may not include the original nonwoven fabric production step S11, and may include only the first cutting step S12.

[0035] In the manufacturing process S11 of the original nonwoven fabric 101, as shown in FIG. 4, the original nonwoven fabric 101 is manufactured using a raw material of shape memory fiber containing a shape memory polymer. The raw material of the original nonwoven fabric 101 may contain other resins and additives in addition to the shape memory polymer. In this process, the raw material is heated to a first temperature T1 higher than the melting temperature Ta of the shape memory polymer and formed into a nonwoven fabric. The method of forming the nonwoven fabric is not particularly limited, and for example, a spunbond method, a meltblown method, etc. can be applied. Alternatively, the forming method may be a method of forming a fiber web and then fusing the fibers by an air-through method, a needle punch method, a spunlace method, etc. The first temperature T1 is preferably 100° C. or higher, more preferably 150° C. or higher.

[0036] The flow direction of the original nonwoven fabric 101 during production is defined as the MD direction (first planar direction X), and the direction perpendicular thereto is defined as the CD direction (second planar direction Y). From the viewpoint of improving production efficiency, it is preferable that the original nonwoven fabric 101 is configured in a long shape extending in the MD direction.

[0037] The original nonwoven fabric 101 formed at the first temperature T1 is cooled to room temperature RT as shown in Fig. 4. The room temperature RT is, for example, 15°C or higher and 35°C or lower. This forms crosslinking points in the shape memory polymer, and the original nonwoven fabric 101 that has memorized the first memory shape before processing is formed. The original nonwoven fabric 101 in the first memory shape does not have any open holes, and is, for example, substantially flat overall.

[0038] Next, in the first cutting step S12, as shown in FIG. 4, the original nonwoven fabric 101 is pressed against the first support R1, and the original nonwoven fabric 101 is cut open by the first protrusions R10 of the first support R1. This produces a nonwoven fabric 10A in a first processed shape having first open holes 20A. In this embodiment, the first cutting step S12 is performed at a temperature lower than the deformation temperature Tb of the shape memory polymer, for example, at room temperature RT. Since the nonwoven fabric is made of fibers, it is relatively easy to process, and a temporary shape can be imparted even at room temperature RT.

[0039] From the viewpoint of increasing productivity, the first support R1 is preferably configured in a roll shape. In this case, by providing a flat roll Rf opposite the roll-shaped first support R1, it becomes possible to press the original nonwoven fabric 101 against the first support R1 while continuously feeding out the long original nonwoven fabric 101.

[0040] As shown in FIG. 5, the first support R1 has a plurality of first protrusions R10 for forming the first openings 20A. The first protrusions R10 protrude from the support surface R13 of the first support R1 in the thickness direction Z and include sharp tips E (first tip E1 and second tip E2). The sharp tips E are portions that cut open the raw nonwoven fabric 110 and have a shape corresponding to the cuts in the raw nonwoven fabric 110. Therefore, the tips E have a linear planar shape. The "linear planar shape" means a shape that extends linearly along the support surface R13 when the support surface R13 of the first support R1 is viewed from the thickness direction Z. This "linear" may be a straight line or a curved line, or may be a shape that is a combination of a plurality of lines. For example, the tip E shown in FIG. 5 has an H-shaped planar shape.

[0041] As shown in Figs. 6A and 6B, for example, the first protrusion R10 includes a pair of first cut portions R11 including a sharp first tip portion E1, and a second cut portion R12 including a sharp second tip portion E2 and connecting between the pair of first cut portions R11. The first cut portion R11 is a portion that cuts open the periphery of the first opening portion 20A, and the first tip portion E1 at the tip in the thickness direction Z extends, for example, in the first direction. The second cut portion R12 is a portion that cuts open between the pair of first lid portions 22A, and the second tip portion E2 at the tip in the thickness direction Z extends, for example, in a second direction intersecting with the first direction. In the example shown in Fig. 6, the "first direction" is the first planar direction X, and the "second direction" is the second planar direction Y. The shape of the first protrusion R10 is not limited to the example shown in Fig. 6, and can be appropriately set according to the shape of the first lid portion 22A.

[0042] The process of cutting open the original nonwoven fabric 101 by the first convex portions R10 will be described with reference to Fig. 7. In Fig. 7, the cross section of the original nonwoven fabric 101 is shown by a dot pattern. In addition, in the roll-shaped first support R1, the support surface R13 is curved, but in Fig. 7 it is depicted as being flat for illustrative purposes.

[0043] As shown in Fig. 7(A), when the original nonwoven fabric 101 is pressed against the first convex portion R10, the original nonwoven fabric 101 stretches / breaks along the second end portion E2 of the first convex portion R10. At the same time, the original nonwoven fabric 101 breaks at the first end portion E1. In this way, by pressing the original nonwoven fabric 101 further toward the support surface R13, the original nonwoven fabric 101 breaks along the first end portion E1 and the second end portion E2 as shown in Fig. 7(B). The broken portion forms the first lid portion 22A.

[0044] Here, in the embodiment shown in Fig. 7(A), tension (see arrows in Fig. 7(A)) is generated in the original nonwoven fabric 101 from the portions in contact with the first cut portion R11 and the second cut portion R12 toward the outside of the formation region of the first hole portion 20A. When the original nonwoven fabric 101 shown in Fig. 7(B) breaks, the pair of first lid portions 22A cut open by the second tip portion E2 are folded along the side surfaces of the second cut portion R12. As a result, in the first cutting step S12, the first hole portion 20A is formed as an open shape in which the first connecting portion 23A is bent, as shown in Fig. 7(B).

[0045] 6 and 7 show an example in which the angle α between the first lid portion 22A and the second main surface 13 is about 90 degrees. The angle α can be adjusted by the width dimension D of the base of the second cut portion R12 along the first direction (first planar direction X). A method for adjusting the angle α by changing the shape of the second cut portion R12 will be described later.

[0046] The above manufacturing method produces a nonwoven fabric 10A that has memorized a substantially flat shape as the first memorized shape and has first open holes 20A as the first processed shape. In the above method, the first connecting portions 23A are processed into a bent shape, so that the shape memory fibers in this portion are bent and sufficiently distorted.

[0047] (Effects of this embodiment) In the nonwoven fabric 10A of this embodiment, the elastic modulus of the first connecting portions 23A increases and the first connecting portions 23A autonomously return to a state close to the first memory shape by immersing the nonwoven fabric 10A having the first openings 20A in open shape in hot water at 40°C for 30 seconds. As a result, as shown in "After stimulation with hot water, etc." in Fig. 4, the first connecting portions 23A are flattened and the first openings 20A become closed. Then, when the nonwoven fabric 10A is cooled to about room temperature RT after stimulation with hot water, etc., the restored shape is maintained.

[0048] As a result, according to the nonwoven fabric 10A of this embodiment, for example, in the open shape, moisture and air can easily pass through the first openings 20A, and in the closed shape, moisture and air cannot easily pass through. Therefore, when the nonwoven fabric 10A is used in an absorbent article, for example, the first openings 20A become closed after excreted liquid passes through them, making it difficult for the excreted liquid to return to the skin. In addition, when the nonwoven fabric 10A is used in an article other than an absorbent article, the first openings 20A can become closed due to stimuli such as breath, body heat, sweat, and steam, and therefore can be used to distinguish before and after use, block moisture, and suppress ventilation after use.

[0049] An example in which the nonwoven fabric 10A is applied to an absorbent article 1A will be described below with reference to Fig. 8. As shown in Fig. 8(A), the absorbent article 1A has an absorbent body 30 and a nonwoven fabric 10A laminated on the absorbent body 30. Fig. 8 shows an example in which the nonwoven fabric 10A is disposed on the absorbent body 30 as a top sheet of the absorbent article 1A.

[0050] 8(A), the wearer's excreted liquid WL comes into contact with, for example, the excretory-facing region P of the nonwoven fabric 10A. As a result, the excreted liquid WL passes through the open first open holes 20A present in the excretory-facing region P. As a result, the excreted liquid WL is quickly absorbed into the absorber 30.

[0051] The first connecting portion 23A of the first opening portion 20A located in the excretory-facing region P is heated by contact with the excretion liquid WL. As a result, as shown in FIG. 8(B), the first connecting portion 23A is flattened so as to return to the first memory shape, and the first lid portion 22A covers at least a part of the first opening body 21A. Accordingly, the opening area of ​​the first opening portion 20A is also reduced. FIG. 8(B) shows an example in which the first lid portion 22A completely covers the first opening body 21A after the passage of the excretion liquid WL. After the passage of the excretion liquid WL, the first opening portion 20A in a closed shape cooled by the surrounding air is maintained in that shape.

[0052] As shown in Fig. 8(B), the excreted liquid WL held in the absorber 30 is less likely to return to the first main surface 12 due to the reduction in the open area. This makes it possible to suppress the liquid from returning onto the first main surface 12 even when an external force such as the wearer's body pressure is applied to the absorbent article 1A. Therefore, the nonwoven fabric 10A can suppress discomfort and skin troubles caused by the liquid returning. Furthermore, suppressing the liquid returning can also suppress leakage of liquid to the outside of the absorbent article 1A.

[0053] In addition, when the absorbent article 1A is worn for a long time, it may absorb the excreted liquid WL discharged multiple times. In the nonwoven fabric 10A of this embodiment, the first openings 20A in the area that contacts the excreted liquid WL are closed, so that the excreted liquid WL discharged from the second time onward is less likely to permeate through the closed first openings 20A. Therefore, the excreted liquid WL can be diffused along the closed first openings 20A to the open first openings 20A around the excretory-facing area P. As a result, the excreted liquid WL can be dispersed and absorbed in the unused area of ​​the absorber 30, and the absorption capacity of the absorber 30 can be increased. Therefore, the absorbent article 1A can be used for a long time while suppressing discomfort and skin troubles on the skin.

[0054] (Detailed configuration example of the first opening) A detailed configuration example of the first opening 20A will be described below. In order to obtain the effect of opening and closing the first openings 20A more effectively, it is preferable that the opening area of ​​the first openings 20A is sufficiently reduced by stimulation with warm water or the like. From this viewpoint, the ratio of the opening area of ​​the closed shape to the opening area of ​​the open shape of the first openings 20A is preferably 10% or more, more preferably 20% or more, even more preferably 30% or more, and preferably 80% or less, more preferably 70% or less, even more preferably 50% or less, even more preferably 45% or less, and even more preferably 40% or less. By using a nonwoven fabric 10A having such first openings 20A in an absorbent article, the effect of preventing liquid return can be improved, and skin troubles can be more effectively suppressed.

[0055] The ratio of the open area can be calculated as follows. First, the open area before immersion in warm water is calculated as the "open area of ​​the open shape". The open area can be calculated, for example, by placing the nonwoven fabric 10A on an arbitrary flat surface (XY plane) and analyzing an image of the nonwoven fabric 10A captured from above in the thickness direction Z. The open area is defined as the area of ​​the portion of the first open body 21A that is not covered by the first lid portion 22A. The open area of ​​any 10 first open portions 20A (the maximum number when the number is less than 10) in the nonwoven fabric 10A is calculated, and the average value of these is measured. This average value is defined as the "open area before immersion in warm water". Next, the open hole area after the nonwoven fabric 10A is immersed in 40°C hot water for 30 seconds is calculated using the method described above. The areas of 10 random open holes having the same or similar shape as the first open hole portion 20A for which the open hole area before immersion in hot water was calculated are calculated, and the average value is measured. This average value is the "closed open hole area." Using the calculated value, the ratio of the closed open hole area to the open open hole area ((closed open hole area) / (open open hole area)×100) is calculated.

[0056] In addition, the opening area of ​​the first opening 20A is preferably 10 mm2 or less in order to fully exert the effect in the open shape. 2 More than 12mm, preferably 2 More preferably, 15 mm 2 More than 30 mm, preferably 2 Less than or equal to 28mm, preferably 2 Less than 25mm, more preferably 2 The open first open hole portions 20A have such an area, so that when the nonwoven fabric 10A is used in an absorbent article, good liquid permeability can be obtained.

[0057] In addition, the proportion of the total open area of ​​the first open hole portions 20A in the nonwoven fabric 10A is, from the viewpoints of obtaining good liquid permeability and maintaining the shape of the nonwoven fabric 10A, preferably 10% or more, more preferably 13% or more, even more preferably 17% or more, and is preferably 35% or less, more preferably 33% or less, even more preferably 28% or less.

[0058] Furthermore, from the viewpoint of sufficiently reducing the opening area of ​​the first open hole portion 20A by the stimulation of warm water or the like, the first connecting portion 23A preferably intersects with the fiber orientation direction (MD direction: first planar direction X in FIG. 2), and more preferably intersects with the fiber orientation direction (MD direction). Since the first connecting portion 23A is a portion along the folding line formed during bending processing, the first connecting portion 23A can be bent along the fiber orientation direction (MD direction) by intersecting with the fiber orientation direction (MD direction). By intersecting with the fiber orientation direction (MD direction), the shape memory fiber of the first connecting portion 23A can be sufficiently bent, and the first connecting portion 23A can be effectively restored to its shape. The fiber orientation direction can be determined by the following method. First, a nonwoven fabric is placed on a scanning electron microscope JCM-5100 (trade name) manufactured by JEOL Ltd., and a planar image (adjusted to a magnification that can measure 10 or more fibers to be measured; 70 times or more and 300 times or less) is printed, and the fibers are traced on a transparent PET sheet. The image is imported into a personal computer, and the image is binarized using nexusNewQube (trade name) (standalone version) image processing software manufactured by Nexus Co., Ltd. Next, the binarized image is Fourier transformed using Fiber Orientation Analysis 8.13 Single software (trade name), which is a fiber orientation analysis program, to obtain a power spectrum, and the orientation angle is obtained from an elliptical approximation distribution diagram. The orientation angle indicates the angle at which the fibers are most oriented, and the angle direction is defined as the "fiber orientation direction."

[0059] In addition, from the viewpoint of sufficiently reducing the opening area of ​​the first opening portion 20A, it is also preferable to largely bend the first connecting portion 23A during processing. Therefore, the angle between the first lid portion 22A and the second main surface 13 in the open shape is preferably 120 degrees or less, more preferably 90 degrees or less. In addition, from the viewpoint of ease of processing, etc., the angle is preferably 40 degrees or more, more preferably 60 degrees or more. The angle between the first lid portion 22A and the second main surface 13 can be the average value of the angles of any 10 first lid portions 22A (the maximum number if less than 10).

[0060] The angle between the first lid portion 22A and the second main surface 13 can be adjusted by the width dimension D in the first direction (first planar direction X) of the base of the second cut portion R12 with reference to Figures 6, 7 and 9. 9(A) to 9(C) show an example of a first protrusion R10 in which the angle α between the first lid portion 22A and the second main surface 13 can be set to approximately 120 degrees. This first protrusion R10 has a first cut portion R11 (first tip portion E1) and a second cut portion R12 (second tip portion E2) arranged in a similar manner to the example shown in Figures 6 and 7, but the width dimension D of the base of the second cut portion R12 is narrower than in the example shown in Figures 6 and 7. Here, the width dimension D of the base of the second cut portion R12 means the dimension along the first direction (eg, first planar direction X) at the portion (base) of the second cut portion R12 that connects with the support surface R13. In the example shown in Fig. 9(C), compared to the example shown in Fig. 7(B), the width dimension D of the base of the second cut portion R12 is narrow, so that the bending angle α of the pair of first lid portions 22A cut open by the second tip portion E2 can be increased when the pair is bent along the side surface of the second cut portion R12. As an example, by adjusting the width dimension D of the base of the second cut portion R12 in this manner, the angle α between the first lid portion 22A and the second main surface 13 can be adjusted.

[0061] The arrangement of the first openings 20A can be set in consideration of the effect obtained in the open shape. In the example shown in FIG. 2(A), the first openings 20A are arranged in a first row L11 along a first arrangement direction and a second row L12 along a second arrangement direction intersecting the first arrangement direction. In the example shown in the figure, the "first arrangement direction" is the first planar direction X, and the "second arrangement direction" is the second planar direction Y. The "first row L11 is along the first arrangement direction" is not limited to a case where a line connecting the center points of the first openings 20A is linear, but may be any case where the first openings 20A are arranged at intervals along any one direction in the XY plane. Similarly, "the second row L12 is aligned along the second arrangement direction" is not limited to a state in which a line connecting the center points of the first openings 20A is straight, but rather it is sufficient that multiple first openings 20A are arranged at intervals along a direction intersecting with the first row L11 in the XY plane.

[0062] In this case, as shown in FIG. 2(A), the first openings 20A may be arranged at the positions where the first row L11 and the second row L12 intersect, and the first openings 20A may be arranged in a lattice pattern. Alternatively, referring to FIG. 10 of the second embodiment, the first openings 20A belonging to adjacent first rows L11 may be arranged shifted from each other in the first arrangement direction (first planar direction X). In this way, by regularly arranging the first openings 20A, it is possible to suppress the variation in the liquid permeability in the XY plane of the nonwoven fabric 10A. Therefore, even during repeated excretion, the excreted liquid can be diffused more effectively.

[0063] From the viewpoint of arranging the first openings 20A more regularly, it is preferable that the intervals between adjacent first openings 20A in the first row L11 are substantially constant. Similarly, it is preferable that the intervals between adjacent first openings 20A in the second row L12 are substantially constant. "Substantially constant intervals" means that, when the intervals between the first openings 20A at any three locations in each row are measured and the narrowest interval is taken as 100%, the difference between the widest interval and the narrowest interval is within 20%.

[0064] In addition, the first lid portion 22A is not limited to the above configuration. For example, in order to form a first lid portion 22A with a smaller area, each first opening 20A may have multiple pairs of first lid portions 22A. In this configuration, the pair of first lid portions 22A are adjacent to each other in the closed shape and face each other across the first opening body 21A in the open shape. Such multiple pairs of first lid portions 22A may be formed by, for example, two or more intersecting cuts in a cross shape, etc. Alternatively, each of the first openings 20A may have one first lid portion 22A. Such a first lid portion 22A may be formed, for example, by cutting along the periphery of the first opening 20A.

[0065] (Examples of thickness and basis weight of nonwoven fabric body) The thickness of the nonwoven fabric body 11 in the thickness direction Z is preferably 0.5 mm or more, more preferably 0.8 mm or more, and is preferably 2.0 mm or less, more preferably 1.5 mm or less, from the viewpoint of sufficiently obtaining the opening and closing action of the first opening portion 20A. The basis weight of the nonwoven fabric body 11 is preferably 20 g / m 2 More preferably, 30 g / m 2 or more, preferably 150 g / m 2 Less than 130 g / m 2 The following is the result. The above values ​​were measured at 25° C. using the nonwoven fabric body 11 before contact with hot water.

[0066] A method for measuring the thickness of the nonwoven fabric body 11 will be described. The nonwoven fabric 10A to be measured is cut into a 10 cm x 10 cm rectangle to obtain a sample for measurement. If a 10 cm x 10 cm rectangle cannot be obtained, cut it to an area as large as possible. With a load of 0.5 Pa applied to the measurement sample, a laser thickness meter (Omron Corporation ZSLD80) is used to measure the thickness at five points in the sample, and the average value is calculated.

[0067] The method for measuring the basis weight of the nonwoven fabric body 11 will be described. The nonwoven fabric 10A to be measured is cut to a predetermined size to obtain small pieces for measurement. The mass of each small piece is measured, and the basis weight of each small piece is calculated by dividing the mass by the area of ​​each small piece. The average basis weight of the five small pieces is defined as the basis weight of the nonwoven fabric 10A.

[0068] [Second embodiment] As shown in Figure 1 and Figures 10(A) and (B), the openings 20 according to the second embodiment of the present invention are configured as second openings 20B that switch from a closed state to an open state when immersed in warm water at 40°C for 30 seconds. This embodiment can provide a nonwoven fabric 10B that opens in response to a stimulus such as warm water. The nonwoven fabric body 11 in which the second openings 20B are formed is configured in the same way as in the first embodiment, and therefore description thereof will be omitted.

[0069] Similar to the first hole section 20A, the second hole section 20B has a second hole body 21B as the hole body 21 and a second lid section 22B as the lid section 22. In this embodiment, the second lid section 22B is connected to the nonwoven fabric body 11 by a second connecting section 23B and configured to be able to cover at least a part of the second hole body 21B. The second connecting section 23B is configured to be bendable relative to the nonwoven fabric body 11.

[0070] The second lid portion 22B is configured similarly to the first lid portion 22A. Specifically, each second opening portion 20B has a pair of second lid portions 22B. The pair of second lid portions 22B are adjacent to each other in the closed shape, and face each other across the second opening body 21B in the open shape. In the example shown in FIG. 10(A), the second lid portion 22B is formed by an H-shaped cut. As described in the first embodiment, the second lid portion 22B may have a plurality of pairs of second lid portions 22B, or may have one second lid portion 22B. The second opening body 21B is also configured similarly to the first opening body 21A. In the example shown in FIGS. 10(A) and (B), the second opening body 21B is configured in a rectangular shape.

[0071] In this embodiment, the closed shape of the second opening 20B is the shape in which the second connecting portion 23B is flattened before the nonwoven fabric 10B is immersed in 40° C. hot water for 30 seconds, as shown in Fig. 1(B) and Fig. 10(A). The open shape of the second opening 20B is the shape in which the second connecting portion 23B is bent after the nonwoven fabric 10B is immersed in 40° C. hot water for 30 seconds, as shown in Fig. 1(A) and Fig. 10(B), and the open shape of the second opening 20B is the shape in which the second connecting portion 23B is bent after the nonwoven fabric 10B is immersed in 40° C. hot water for 30 seconds, and the open area of ​​the second opening 20B is increased compared to the closed shape. The open area of ​​the second opening 20B before and after immersion in 40° C. hot water for 30 seconds can be compared in the same manner as in the first embodiment.

[0072] In the present embodiment, nonwoven fabric 10B has a bent shape of second connecting portion 23B of second lid portion 22B, which corresponds to the open shape, memorized as the second memory shape. Nonwoven fabric 10B is given a flattened shape (second processed shape) corresponding to the closed shape. Therefore, nonwoven fabric 10B maintains the second processed shape corresponding to the closed shape before stimulation with hot water or the like, and returns to a shape close to the second memory shape corresponding to the open shape when stimulated with hot water or the like.

[0073] (Manufacturing method) Next, a method for producing the nonwoven fabric 10B according to this embodiment will be described with reference to Figures 11 and 12. As shown in the flow chart of Figure 11, the method for producing the nonwoven fabric 10B according to this embodiment includes, for example, a step S11 of producing an original nonwoven fabric, a first cutting step S22 involving heating, and a flattening step S23. Note that this production method does not necessarily have to include the step S11 of producing an original nonwoven fabric, as in the first embodiment.

[0074] In the production step S11 of the original nonwoven fabric 101, the original nonwoven fabric 101 having no open holes is produced using a raw material of shape memory fiber containing a shape memory polymer, as shown in Fig. 12. The production step S11 of the original nonwoven fabric 101 is similar to that of the first embodiment, and therefore a detailed description thereof will be omitted.

[0075] 12, in the first cutting step S22, similar to the first cutting step S12 of the first embodiment, the original nonwoven fabric 101 is pressed against the first support R1, and the original nonwoven fabric 101 is cut open by the first protrusions R10 of the first support R1. This forms the second lid portion 22B having the bent second connecting portion 23B, and produces the intermediate nonwoven fabric 102 having the second memory shape and the open second openings 20B. The formation of the second openings 20B in this first cutting step S22 is performed as described with reference to FIG. 7, for example.

[0076] The first support R1 of this embodiment has a heating mechanism (not shown) and is configured to be able to be heated to a temperature T2 of 80°C or more and 200°C or less. In this embodiment, the first cutting step S22 is performed with the first support R1 heated to temperature T2. At this temperature T2, the shape memory polymer contained in the shape memory fiber is significantly softened, and the crosslinking points of the shape memory polymer are reformed. As a result, the second memory shape imparted at temperature T2 is memorized in the shape memory polymer of the intermediate nonwoven fabric 102. The intermediate nonwoven fabric 102 is then cooled to room temperature RT.

[0077] As shown in Fig. 12, the first support R1 has a plurality of first protrusions R10 having a linear planar shape, as in the first embodiment. The planar shape and arrangement of the first protrusions R10 are not limited to the examples shown in Fig. 5 and Fig. 6, and can be appropriately set in consideration of the shape and arrangement of the second openings 20B. In the example shown in Fig. 12, the first support R1 is configured, for example, in a roll shape, and is disposed opposite the flat roll Rf.

[0078] Next, in the flattening step S23, the open second apertures 20B of the intermediate nonwoven fabric 102 are flattened at 60° C. or less. This forms a nonwoven fabric 10B in a second processed shape having closed second apertures 20B. The flattening step S23 is preferably performed by a pair of flat rolls Rf each having a substantially flat peripheral surface maintained at room temperature RT. In this case, in the flattening step S23, by sandwiching the original nonwoven fabric 101 between the pair of flat rolls Rf, it becomes possible to press and flatten the intermediate nonwoven fabric 102 while continuously feeding out the long intermediate nonwoven fabric 102.

[0079] By the above manufacturing method, nonwoven fabric 10B is produced, which has memorized the second memory shape including open second openings 20B and has been given a second processed shape including closed second openings 20B.

[0080] (Effects of this embodiment) In the nonwoven fabric 10B of this embodiment, the nonwoven fabric 10B having the second openings 20B in a closed shape is immersed in 40°C hot water for 30 seconds, whereby the second connecting portions 23B are softened and restored to a state close to the second memory shape. As a result, the second openings 20B are switched to an open shape as shown in "After stimulation by hot water, etc." in Fig. 12. After contact with hot water, the nonwoven fabric 10B is cooled to about room temperature RT and maintains the restored shape.

[0081] In this embodiment, the second openings 20B are configured to switch from a closed state to an open state when immersed in 40°C hot water for 30 seconds, so that, for example, in the closed state, moisture and air can pass through the gaps between the fibers of the nonwoven fabric 10B, and in the open state, the second openings 20B promote the passage of moisture and ventilation. As a result, when the nonwoven fabric 10B is used in an absorbent article, the second openings 20B open after the passage of excreted liquid, promoting ventilation. In addition, when the nonwoven fabric 10B is used in an article other than an absorbent article, the second openings 20B can open due to stimuli such as breath, body heat, sweat, and steam, so that it can be used to distinguish before and after use, promote ventilation and liquid passage after use, and the like.

[0082] An example in which the nonwoven fabric 10B is applied to an absorbent article 1B will be described below with reference to Fig. 13. As shown in Fig. 13(A), the absorbent article 1B has an absorbent body 30 and a nonwoven fabric 10B laminated on the absorbent body 30. Fig. 13 shows an example in which the nonwoven fabric 10B is disposed on the absorbent body 30 as a top sheet of the absorbent article 1B.

[0083] As shown in Fig. 13(A), the wearer's excreted liquid WL excreted in the excretory-facing region P of the nonwoven fabric 10B can pass through gaps between the fibers of the nonwoven fabric 10B and permeate the nonwoven fabric 10B having the closed second openings 20B. This allows the excreted liquid WL to be absorbed into the absorber 30. Meanwhile, the second connecting parts 23B of the second openings 20B located in the excretory-facing region P are heated by contacting with the excretory liquid WL. This causes the connecting parts 23 to bend so as to return to the second memory shape, and the second openings 20B to switch to an open shape, as shown in Fig. 13(B).

[0084] As shown in Fig. 13(B), moisture is likely to evaporate from the excreted liquid WL held in the absorbent body 30 due to the body temperature of the wearer and the temperature of the excreted liquid WL itself. In the nonwoven fabric 10B of this embodiment, the second openings 20B are opened after the excreted liquid WL has permeated, and water vapor is released to the outside through the second openings 20B, as shown by the dashed lines in Fig. 13(B). In other words, the breathability of the absorbent article 1B is improved after the excretion of the excreted liquid WL. Therefore, the nonwoven fabric 10B of this embodiment can prevent a stuffy feeling while wearing the absorbent article 1B, and can prevent skin discomfort and skin troubles caused by stuffiness.

[0085] (Detailed configuration of second opening 20B) The detailed configuration of the second opening 20B will be described below, with the explanation of parts that overlap with the first embodiment (such as the definition of each component, the measurement method, etc.) being omitted.

[0086] In order to obtain the effect of opening and closing the second openings 20B more effectively, it is preferable that the second openings 20B are reliably opened by stimulation such as warm water. From this viewpoint, the ratio of the open opening area of ​​the second openings 20B to the closed opening area of ​​the second openings 20B is preferably 150% or more, more preferably 160% or more, even more preferably 200% or more, even more preferably 250% or more, even more preferably 260% or more, and is preferably 400% or less, more preferably 350% or less, and even more preferably 300% or less. By using a nonwoven fabric 10B having such second openings 20B in an absorbent article, good breathability can be obtained and stuffiness can be effectively suppressed.

[0087] The ratio of the area of ​​the openings in the open shape to the area of ​​the second openings 20B can be calculated as follows. First, the open area before immersion in hot water is calculated as the "open area in closed shape". The open area can be calculated, for example, by placing the nonwoven fabric 10B on an arbitrary flat surface (XY plane) and analyzing an image of the nonwoven fabric 10B captured from above in the thickness direction Z. The open area is defined as the area of ​​the portion of the second open body 21B that is not covered by the second lid portion 22B. The open area of ​​any 10 second open portions 20B in the nonwoven fabric 10B (the maximum number if less than 10) is calculated, and the average value of these is measured. This average value is defined as the "open area in closed shape (before immersion in hot water)". Next, the open hole area after the nonwoven fabric 10B is immersed in 40°C hot water for 30 seconds is calculated using the method described above. The open hole areas of any 10 holes (the maximum number if there are less than 10) having the same or similar shape as the second hole portion 20B for which the open hole area before immersion in hot water was calculated are calculated, and the average value is measured. This average value is the "open hole area in the open shape (after immersion in hot water)". Using the calculated value, the ratio of the open hole area to the closed hole area of ​​the second hole portion 20B ((open hole area) / (closed hole area)×100) is calculated.

[0088] In addition, the opening area of ​​the second opening 20B in the closed state is preferably 6 mm 2More than 6.5mm, preferably 6.5mm 2 More preferably, 8 mm 2 More than 30 mm, preferably 2 Less than or equal to 29.5mm, preferably 2 Less than 28mm, more preferably 2 The following is the result.

[0089] As in the first embodiment, in the open state, the second connecting portions 23B preferably intersect with the fiber orientation direction (MD direction: first planar direction X in FIG. 2), and more preferably intersect at right angles with the fiber orientation direction (MD direction). This allows the shape-memory fibers of the second connecting portions 23B to be sufficiently bent in the intermediate nonwoven fabric 102 in which the open second openings 20B are formed, and allows the second connecting portions 23B to effectively restore their shape.

[0090] In addition, the proportion of the total open area of ​​the open shape of the second open hole portion 20B in the nonwoven fabric 10B is preferably 5% or more, more preferably 6% or more, even more preferably 8% or more, and is preferably 68% or less, more preferably 60% or less, even more preferably 50% or less.

[0091] In the open shape, the angle between second lid portion 22B and second main surface 13 is preferably 120 degrees or less, and more preferably 90 degrees or less. From the viewpoint of ease of processing, the angle is preferably 40 degrees or more, and more preferably 60 degrees or more.

[0092] The second openings 20B can be arranged in consideration of the effect obtained in the open shape. In the example shown in Fig. 10(B), the second openings 20B are arranged in a first row L21 along a first arrangement direction (for example, a first planar direction X) and a second row L22 along a second arrangement direction (a second planar direction Y) intersecting the first arrangement direction.

[0093] In the second openings 20B shown in Fig. 10(B), the second openings 20B belonging to adjacent first rows L21 are arranged so as to be shifted from each other in the first arrangement direction (first planar direction X). However, this is not limited thereto, and as shown in Fig. 2(A), the second openings 20B may be arranged at positions where the first row L21 and the second row L22 intersect, and the second openings 20B may be arranged in a lattice pattern. As in the first embodiment, from the viewpoint of arranging the second openings 20B more regularly, it is preferable that the intervals between the adjacent second openings 20B in each row are substantially constant.

[0094] [Third embodiment] As shown in Fig. 1, Fig. 14 and Fig. 15, the opening 20 according to the third embodiment of the present invention includes a first opening 20A that switches from an open shape to a closed shape when immersed in 40°C hot water for 30 seconds, and a second opening 20B that switches from a closed shape to an open shape. Fig. 14 shows an example of a nonwoven fabric 10C before immersion in hot water, and Fig. 15 shows an example of a nonwoven fabric 10C after immersion in hot water. This embodiment can provide a nonwoven fabric 10C whose opening pattern changes depending on a stimulus such as hot water. The nonwoven fabric body 11 in which the first opening 20A and the second opening 20B are formed is configured in the same way as in the first embodiment, and therefore a description thereof will be omitted.

[0095] The first perforated portion 20A has a first perforated body 21A and a first lid portion 22A, similar to the first embodiment. In this embodiment, the first lid portion 22A is connected to the nonwoven fabric body 11 by a first connecting portion 23A and configured to be able to cover at least a part of the first perforated body 21A. The first connecting portion 23A is configured to be bendable relative to the nonwoven fabric body 11.

[0096] In the example shown in Fig. 14 and Fig. 15, each first opening 20A has a pair of first lid portions 22A. The pair of first lid portions 22A are adjacent to each other in the closed shape, and face each other across the first opening body 21A in the open shape. Furthermore, in the example shown in Fig. 14 and Fig. 15, the pair of first lid portions 22A face each other in the first planar direction X (fiber orientation direction), and the first connecting portion 23A is arranged to intersect with said direction. The pair of first lid portions 22A is formed by, for example, an H-shaped cut, similar to the first embodiment.

[0097] The second perforated portion 20B has a second perforated body 21B and a second lid portion 22B, similar to the second embodiment. In this embodiment, the second lid portion 22B is connected to the nonwoven fabric body 11 by a second connecting portion 23B and configured to be able to cover at least a part of the second perforated body 21B. The second connecting portion 23B is configured to be bendable relative to the nonwoven fabric body 11.

[0098] In the example shown in Figs. 14 and 15, each second opening 20B has a pair of second lids 22B. The pair of second lids 22B are adjacent to each other in the closed shape, and face each other across the second opening body 21B in the open shape. Furthermore, in the example shown in Figs. 14 and 15, the pair of second lids 22B face each other in the second planar direction Y (CD direction), and the second connecting portion 23B is arranged to cross this direction. The pair of second lids 22B is formed by an H-shaped cut as in the first embodiment, but has a shape that is elongated in the first planar direction X more than the first lid 22A. Such an elongated H-shaped cut is hereinafter referred to as an I-shaped cut.

[0099] In the nonwoven fabric 10C of this embodiment, for example, a shape having the first openings 20A in a closed shape and the second openings 20B in an open shape is stored as the third memory shape. In the nonwoven fabric 10C, a shape having the first openings 20A in an open shape and the second openings 20B in a closed shape (third processed shape) is imparted by processing. For this reason, the nonwoven fabric 10C is configured to maintain the third processed shape before stimulation such as hot water, and to approach the third memory shape by stimulation such as hot water.

[0100] (Manufacturing method) Next, a method for producing the nonwoven fabric 10 according to this embodiment will be described with reference to Figures 16 and 17. As shown in the flow chart of Figure 16, the method for producing the nonwoven fabric 10 according to this embodiment includes, for example, an original nonwoven fabric production step S11, a first cutting step S32, a flattening step S33, and a second cutting step S34. Note that, like the first embodiment, this production method does not necessarily have to include the original nonwoven fabric production step S11.

[0101] In the production step S11 of the original nonwoven fabric 101, the original nonwoven fabric 101 having no open holes is produced using a raw material of shape memory fiber containing a shape memory polymer, as shown in Fig. 17. The production step S11 of the original nonwoven fabric is similar to that of the first embodiment, and therefore a detailed description thereof will be omitted.

[0102] 17, in the first cutting step S32, similar to the first cutting step S22 of the second embodiment, the original nonwoven fabric 101 is pressed against the first support R1 heated to a temperature T2 of 80°C to 200°C, and the original nonwoven fabric 101 is cut open by the first protrusions R10 of the first support R1. This produces a first intermediate nonwoven fabric 102 in a third memory shape having second open hole portions 20B in an open shape. The processed first intermediate nonwoven fabric 102 is cooled to room temperature RT.

[0103] As shown in FIG. 18, the first support R1 in this embodiment has a first protrusion R10 including, for example, an I-shaped tip E (a first tip E1 and a second tip E2). Specifically, like the first protrusion R10 shown in FIG. 5 and FIG. 6, this first protrusion R10 includes a pair of first cut portions R11 including a sharp first tip E1, and a second cut portion R12 including a sharp second tip E2 and connecting between the pair of first cut portions R11. In this example, the first direction in which the pair of first tips E1 extend is the second planar direction Y, and the second direction in which the second tip E2 extends is the first planar direction X. In this embodiment, the length in the extension direction of the second tip E2 is configured to be greater than the length in the extension direction of the first tip E1. The first protrusion R10 forms a long and narrow I-shaped second opening 20B. Also, similarly to the first embodiment, the angle α between the second lid portion 22B and the second main surface 13 can be adjusted by the width dimension of the base of the second cut portion R12 in the first direction (second planar direction Y). Note that the shape and arrangement of the first convex portion R10 of the first support R1 are appropriately set according to the shape and arrangement of the second opening portion 20B.

[0104] 17, the open second apertures 20B of the first intermediate nonwoven fabric 102 are flattened at 60° C. or less, similar to the flattening step S33 of the second embodiment. In the example shown in the figure, the flattening step S33 uses a pair of flat rolls Rf, each having a substantially flat peripheral surface, preferably maintained at room temperature RT. This forms a second intermediate nonwoven fabric 103 having closed second apertures 20B.

[0105] Subsequently, in the second cutting step S34, as shown in FIG. 17, the second intermediate nonwoven fabric 103 is pressed against a second support R2 that has a plurality of second convex portions arranged in a pattern different from the first convex portions and is maintained at 60° C. or less, and the second intermediate nonwoven fabric 103 is cut open by the plurality of second convex portions R20 of the second support R2. In the second cutting step S34, a pair of flat rolls Rf, each having a substantially flat peripheral surface, preferably maintained at room temperature RT, is used. This produces a nonwoven fabric 10C having a third processed shape including the first open hole portion 20A and the second closed hole portion 20B. The shape and arrangement of the second convex portions R20 of the second support R2 are appropriately set according to the shape and arrangement of the first hole portion 20A.

[0106] By the above manufacturing method, a nonwoven fabric 10C is produced, which has a third memory shape having an open second opening 20B, and has a third processed shape having an open first opening 20A and a closed second opening 20B.

[0107] (Effects of this embodiment) In the nonwoven fabric 10 of this embodiment, by immersing a nonwoven fabric 10C having first apertures 20A in an open shape and second apertures 20B in a closed shape in 40°C warm water for 30 seconds, the nonwoven fabric 10 returns to the second memory shape having first apertures 20A in a closed shape and second apertures 20B in an open shape, as shown in "After stimulation with warm water, etc." in Fig. 17. Then, after stimulation with warm water, etc., the nonwoven fabric 10C is cooled to about room temperature RT and maintains the restored shape.

[0108] According to the nonwoven fabric 10C of this embodiment, the pore pattern can be changed at the location where a stimulus such as warm water is applied. As a result, when the nonwoven fabric 10C is used in an absorbent article, as described in detail below, the excreted liquid can be quickly absorbed and the absorbent body can be effectively utilized by diffusing the excreted liquid. Furthermore, when the nonwoven fabric 10C is used in an article other than an absorbent article, the pore pattern changes due to stimuli such as breath, body temperature, sweat, steam, etc., and therefore the nonwoven fabric 10C can be used to distinguish before and after use and to adjust ventilation and liquid passage after use.

[0109] An example in which the nonwoven fabric 10C is applied to an absorbent article 1C will be described below with reference to Fig. 19. As shown in Fig. 19(A), the absorbent article 1C has an absorbent body 30 and a nonwoven fabric 10C laminated on the absorbent body 30. Fig. 19 shows an example in which the nonwoven fabric 10C is disposed on the absorbent body 30 as a top sheet of the absorbent article 1C.

[0110] As shown in FIG. 19(A), the wearer's excretory liquid WL comes into contact with, for example, the excretory part-facing region P of the nonwoven fabric 10C. In the excretory part-facing region P, first openings 20A that are open and second openings 20B that are closed may be present. The excretory liquid WL on the excretory part-facing region P moves from the first openings 20A that are open and thus more easily permeable, toward the absorbent body 30. As the first openings 20A are open, the excretory liquid WL is quickly absorbed by the absorbent body 30.

[0111] 19(B), the first lid portion 22A is flattened by the stimulation of the excreted liquid WL so as to return to the third memory shape, and the opening area of ​​the first opening portion 20A is reduced. On the other hand, the second opening portion 20B is opened by contact with the excreted liquid WL, and the opening area of ​​the second opening portion 20B is increased.

[0112] After contact with the excretion liquid WL, the first openings 20A are switched to a closed shape, thereby preventing the liquid from returning from the first openings 20A to the first main surface 12 side. Furthermore, when the next excretion liquid WL is excreted, the opened second openings 20B can allow the excretion liquid WL to pass through. Alternatively, the excretion liquid WL can spread along the second openings 20B to the periphery of the excretion part facing region P. In this case, the second openings 20B that are switched to an open shape can function as a guide portion that guides the excretion liquid WL to the periphery of the excretion part facing region P. In other words, the second openings 20B can disperse the second and subsequent excretion liquid WL to a position different from the first excretion liquid WL.

[0113] In this way, the present embodiment can achieve both rapid liquid absorption and large amount of liquid absorption by dispersing or diffusing the liquid, which were previously contradictory technologies. The first openings 20A quickly absorb the excreted liquid WL and confine it to the absorbent body 30 side, thereby suppressing discomfort and skin troubles caused by liquid backflow and residual liquid. Furthermore, the second openings 20B, which have switched from a closed shape to an open shape, can effectively utilize the absorption area of ​​the absorbent body 30 and increase the absorption capacity of the absorbent body 30. Therefore, the absorbent article 1C can be used for a long time while suppressing discomfort and skin troubles.

[0114] (Example of detailed configuration of opening) Hereinafter, a detailed configuration example of the first opening 20A and the second opening 20B will be described. Note that a description of parts that overlap with the first embodiment (such as the definition of each component, the measurement method, etc.) will be omitted.

[0115] In this embodiment, the second perforation body 21B of the second perforation portion 20B is preferably configured in a groove shape. The groove shape refers to a shape in which the ratio of the width dimension to the length dimension is 80% or less when the maximum dimension in the longitudinal direction of the second perforation body 21B is the length dimension and the maximum dimension in the width direction perpendicular to the longitudinal direction is the width dimension. When the nonwoven fabric 10C having such second perforation portions 20B is used in the absorbent article 1C, the diffusion effect of the excreted liquid by the second perforation portions 20B can be effectively obtained. Specifically, when the excreted liquid comes into contact with the second perforation portions 20B, the second perforation portions 20B become open, and the groove-shaped second perforation portions 20B are generated. When the next excreted liquid is excreted, the excreted liquid is easily allowed to flow along the groove-shaped second perforation portions 20B, so that the excreted liquid can be diffused along the second perforation portions 20B. The excreted liquid is then guided to a region different from the region where the excreted liquid is excreted, and can be absorbed from the open first hole portion 20A located in the different region. In this manner, by forming the second hole body 21B in a groove shape, the excreted liquid can be diffused more effectively, which can contribute to improving the absorption capacity of the excreted liquid WL.

[0116] In order to effectively induce the excretory liquid, the ratio of the width to the length of the groove-shaped second perforated body 21B is preferably 60% or less, more preferably 40% or less. In order to form an openable and closable second lid portion 22B, the ratio of the width to the length is preferably 5% or more, more preferably 10% or more.

[0117] Furthermore, for example, from the viewpoint of effectively exerting the above-mentioned excretory liquid induction effect, the length dimension of the groove-shaped second opening portion 20B is preferably 5 mm or more, more preferably 10 mm or more, and is preferably 25 mm or less, more preferably 20 mm or less.

[0118] Furthermore, since the absorbent body 30 is generally configured to be elongated, in order to effectively utilize the absorbent body 30, it is preferable that the liquid can be guided along the longitudinal direction of the absorbent body 30. For this reason, it is preferable that the groove-shaped second openings 20B are formed along the longitudinal direction of the absorbent body 30, and specifically, it is preferable that the angle between the longitudinal direction of the second openings 20B and the longitudinal direction of the absorbent body 30 is 45 degrees or less. In the example shown in Fig. 14 and Fig. 15, the second openings 20B are arranged along the first planar direction X.

[0119] In order to effectively exert the above-mentioned effect, the area of ​​the second opening 20B is preferably 6 mm 2 More than 6.5mm, preferably 6.5mm 2 More preferably, 8 mm 2 More than 30 mm, preferably 2 Less than or equal to 29.5mm, preferably 2 Less than 28mm, more preferably 2 The following is the result.

[0120] For the second opening portion 20B, the ratio of the open opening area to the closed opening area is preferably 150% or more, more preferably 160% or more, even more preferably 200% or more, even more preferably 250% or more, and is preferably 400% or less, more preferably 350% or less, even more preferably 300% or less.

[0121] In addition, the proportion of the total open area of ​​the open shape of the second open hole portion 20B in the nonwoven fabric 10C is preferably 5% or more, more preferably 6% or more, even more preferably 8% or more, and is preferably 68% or less, more preferably 60% or less, even more preferably 50% or less. The preferred ranges for the area of ​​the first hole sections 20A, the ratio of the area of ​​the closed hole sections to the area of ​​the open hole sections, and the ratio of the total area of ​​the open hole sections 20A in the nonwoven fabric 10C are the same as in the first embodiment.

[0122] In the open shape, the angle formed between first lid portion 22A or second lid portion 22B and second main surface 13 is preferably 120 degrees or less, more preferably 100 degrees or less, and is preferably 40 degrees or more, more preferably 60 degrees or more.

[0123] The first openings 20A and the second openings 20B can be arranged in consideration of these effects. In the example shown in Fig. 14, the first openings 20A are arranged in a first row L31 along a first arrangement direction (e.g., first planar direction X) and a second row L32 along a second arrangement direction (second planar direction Y) intersecting with the first arrangement direction. Similarly, the second openings 20B are arranged in a third row L33 along the first arrangement direction (e.g., first planar direction X) and a fourth row L34 along a second arrangement direction (second planar direction Y) intersecting with the first arrangement direction.

[0124] In the example of FIG. 14, the first hole 20A in the first row L31 and the second hole 20B in the third row L33 are arranged next to each other. Similarly, in this example, the first hole 20A in the second row L32 and the second hole 20B in the fourth row L34 are arranged next to each other. With this arrangement, the first hole 20A and the second hole 20B can be arranged in a mixed state. This allows both the first hole 20A and the second hole 20B to be opened and closed by stimulation such as warm water. Therefore, when the nonwoven fabric 10C is used in the absorbent article 1C, the first hole 20A can be closed and the second hole 20B can be opened by contacting the excreted liquid once, and the second hole 20B can exhibit a dispersing or diffusing effect of the excreted liquid.

[0125] As in the first embodiment, in order to arrange the first openings 20A and the second openings 20B more regularly, it is preferable that the distance between adjacent first openings 20A and second openings 20B in each row is substantially constant.

[0126] [Other embodiments] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0127] The arrangement of the openings 20 is not limited to the above example, and may be, for example, another regular arrangement or a random arrangement. The planar shapes of the openings 20 and the lids 22 are also not limited to the above example.

[0128] Furthermore, the manufacturing method of the opening 20 is not limited to the above example. For example, the opening may be cut into the shape of the lid 22 with a cutter or the like, and then the connecting portion 23 of the lid 22 may be bent in a separate process.

[0129] The configuration of the support used to shape the nonwoven fabric 10 is not limited to the above-mentioned example. For example, the support is not limited to a roll shape, but may be a mold or may have another configuration capable of shaping.

[0130] In the above embodiment, the nonwoven fabric 10 is used as a top sheet in an absorbent article, but is not limited thereto. The nonwoven fabric 10 of the present invention may be used as an intermediate sheet disposed between a top sheet and an absorbent body of an absorbent article, for example.

[0131] Furthermore, the uses of the nonwoven fabric 10 are not limited to the above-mentioned examples, and the nonwoven fabric 10 can be applied to various articles other than absorbent articles. EXAMPLES

[0132] [Test Example 1 Test Example According to the First Embodiment] In Test Example 1, first openings were formed in a nonwoven fabric sample containing shape-memory fibers, and it was examined whether or not the sample would close when immersed in warm water.

[0133] (Example 1-1) As a sample of Example 1-1, a nonwoven fabric sample containing shape memory fibers was prepared. First, a commercially available polyurethane-based shape memory polymer ("NICS 3 DF-SMP300N", manufactured by NCI Sales Co., Ltd.) was prepared. This polymer was melt-spun, and the short fibers were carded into a web, which was then made into a nonwoven fabric by the air-through method to produce a flat sheet-like original nonwoven fabric. The molding temperature of the original nonwoven fabric was 180°C. Then, the original nonwoven fabric after molding was cooled to room temperature. The size of this original nonwoven fabric was 10 cm x 20 cm.

[0134] Next, a processing roll (first support) having a convex portion as shown in FIG. 4 and a flat flat roll were prepared. The two rolls were at room temperature. The planar shape of the convex portion of this processing roll was H-shaped, and the length dimension of the pair of first cut portions was 4 mm, the length dimension of the second cut portion was 4 mm, and the height dimension of the convex portion was 5 mm. Here, the width dimension of the base of the second cut portion of the processing roll was 3.5 mm. While rotating these two rolls, the original nonwoven fabric was pressed against the processing roll by the flat roll, thereby cutting open the original nonwoven fabric. As a result, the original nonwoven fabric was formed with a first opening portion having an open shape as shown in FIG. 2(A). The connecting portion of the cover portion of this first opening portion was bent along the fiber orientation direction (MD direction). The number of first opening portions in the sample was 220.

[0135] As shown in Table 1, the thickness of this sample was 0.9 mm. The basis weight of this sample was 100 g / m 2 In the open shape, the angle (bending angle) between the lid portion and the second main surface was 90 degrees.

[0136] (Example 1-2) A nonwoven fabric sample of Example 1-2 was produced in the same manner as in Example 1-1, except that the orientation of the original nonwoven fabric sandwiched between the processing rolls was rotated 90 degrees. The connecting portion of the lid portion of this first hole portion was bent along the CD direction. As shown in Table 1, the angle between the lid portion and the second main surface in the open shape was 90 degrees. The number of first holes in the sample was 220, the same as in Example 1-1.

[0137] (Examples 1-3) A nonwoven fabric sample of Example 1-3 was produced in the same manner as in Example 1-1, except that the width dimension of the base of the second cut portion of the processing roll was 1 mm. As shown in Table 1, the angle between the lid portion and the second main surface in the open shape was 120 degrees. The number of first openings in the sample was 220, the same as in Example 1-1.

[0138] (Comparative Example 1-1) As a nonwoven fabric sample of Comparative Example 1-1, a flat original nonwoven fabric similar to that of Example 1-1 was prepared, and openings were formed in this original nonwoven fabric by punching. Specifically, the position of the original nonwoven fabric was fixed by a fixture, and punching was performed using a punch at the same position as in Example 1-1. As a result, a plurality of rectangular openings were formed. The number of first openings in the nonwoven fabric sample was 220, the same as in Example 1-1. However, in the sample of Comparative Example 1-1, no lids were formed.

[0139] (Comparative Example 1-2) As a nonwoven fabric sample of Comparative Example 1-2, an original nonwoven fabric without any openings formed therein was prepared before processing.

[0140] (Evaluation of pore opening rate after immersion in hot water) A sheet-like sample of each Example and Comparative Example was cut to 10 cm x 10 cm. The cut sample was placed on a flat work table, and the sample was photographed from above in the thickness direction. The image was analyzed, and the area of ​​10 random holes in the sample was calculated, and the average value of these was measured. This average value was defined as the "open hole area in the open shape (before immersion in hot water)". Hot water at 40°C was added to a tray of a size that could accommodate the cut sample. The entire cut sample was immersed in the hot water in the tray for 30 seconds. After removing the sheet from the hot water, the average value of the area of ​​10 random holes was measured. This average value was defined as the "open hole area in the closed shape (after immersion in hot water)". The ratio of the open hole area in the closed shape to the open hole area ((open hole area in the closed shape) / (open hole area in the open shape) x 100) was calculated as the "open hole ratio after immersion in hot water". The results are shown in Table 1.

[0141] [Table 1]

[0142] As shown in Table 1, the sheet of Comparative Example 1-1 was softened somewhat by immersion in hot water, but the pore ratio after immersion in hot water was 90%, and there was almost no change in the open pore area. Moreover, in Comparative Example 1-2, in which no pores were formed, the pore ratio could not be defined in the first place.

[0143] On the other hand, the pore ratios of the samples of Examples 1-1 to 1-3 after immersion in hot water were all 80% or less, and it was found that the open area was reduced by immersion in hot water. In addition, the pore ratio of the sample of Example 1-1, in which the connecting portion is configured to bend along the MD direction, was smaller than that of the sample of Example 1-2, in which the connecting portion is configured to bend along the CD direction. From this, it was found that by forming an opening portion in which the connecting portion is bent along the MD direction, the open area is more reliably reduced by immersion in hot water. Furthermore, Example 1-1, in which the angle between the lid portion and the second main surface in the open shape is 90 degrees, had a smaller pore ratio after immersion in hot water than Example 1-3, in which the angle is 120 degrees. From this, it was found that by making the angle between the lid portion and the second main surface 90 degrees or less, the open area is more reliably reduced by immersion in hot water.

[0144] [Test Example 2 Test Example According to the Second Embodiment] In Test Example 2, closed second apertures were formed in a nonwoven fabric sample containing shape-memory fibers, and it was examined whether or not the second apertures would open when immersed in warm water.

[0145] (Example 2-1) As a sample of Example 2-1, a nonwoven fabric sample having a closed second opening was prepared. First, a flat original nonwoven fabric similar to that of Example 1-1 was prepared. Then, a processing roll (first support) having an I-shaped convex portion and a flat roll facing it were prepared. Here, the width dimension of the base of the second cut portion of the processing roll was set to 4.0 mm. The two rolls were heated to 80°C. The shape and arrangement of the convex portion of the processing roll were the same as those of Example 1-1.

[0146] While rotating these two rolls, the original nonwoven fabric was pressed against the processing roll by the flat roll, cutting the original nonwoven fabric open. This resulted in the formation of open second apertures in the original nonwoven fabric, producing an intermediate nonwoven fabric. The connecting parts of these second apertures were bent along the MD direction. The intermediate nonwoven fabric after the formation of the second apertures was cooled to room temperature.

[0147] As shown in Table 2, the thickness of the nonwoven fabric body of this sample was 1.1 mm. The basis weight of this sample was 124 g / m 2 The total number of second open holes in the entire sample was 112. In the open shape, the angle (bending angle) between the lid portion and the second main surface was 90 degrees.

[0148] Next, two opposing flat rolls maintained at room temperature were prepared. Then, while rotating these two rolls, the intermediate nonwoven fabric was sandwiched between the two rolls to flatten the intermediate nonwoven fabric. This formed a closed second aperture. After this flattening process and before immersion in hot water, the aperture body of the second aperture was covered with a lid.

[0149] (Example 2-2) A nonwoven fabric sample of Example 2-2 was produced in the same manner as in Example 2-1, except that the orientation of the original nonwoven fabric sandwiched between the processing rolls was rotated 90 degrees. The connecting portion of this second opening was bent along the CD direction. As shown in Table 2, the angle between the lid portion and the second main surface in the open shape was 90 degrees.

[0150] (Example 2-3) A nonwoven fabric sample of Example 2-3 was produced in the same manner as Example 2-1, except that the width dimension of the base of the second cut part of the processing roll was 1 mm. As shown in Table 2, the angle between the lid part and the second main surface in the open shape was 120 degrees. The open area after flattening and before immersion in hot water was 6.5 mm2. 2 It was.

[0151] (Comparative Example 2-1) As a nonwoven fabric sample of Comparative Example 2-1, a flat original nonwoven fabric similar to that of Example 2-1 was prepared, and holes were formed in this original nonwoven fabric by piercing a pin. Specifically, the position of the original nonwoven fabric was fixed with a fixture, and a pin was pierced in the same position as in Example 2-1. However, in the sample of Comparative Example 2-1, a lid portion was not formed. Therefore, the area of ​​the opening did not change before and after the flattening process.

[0152] (Comparative Example 2-2) As a nonwoven fabric sample of Comparative Example 2-2, a flat original nonwoven fabric without openings formed therein and before processing in Example 2-1 was prepared.

[0153] (Evaluation of pore opening rate after immersion in hot water) A sheet-like sample of each Example and Comparative Example was cut to 10 cm x 10 cm. The cut sample was placed on a flat work table, and the sample was photographed from above in the thickness direction. The image was analyzed, and the area of ​​10 random holes in the sample was calculated, and the average value of these was measured. This average value was defined as the "open hole area in closed shape (before immersion in hot water)". Hot water at 40°C was added to a tray of a size that could accommodate the cut sample. The entire cut portion was immersed in the hot water in this tray for 30 seconds. After removing the sheet from the hot water, the average value of the area of ​​10 random holes was measured. This average value was defined as the "open hole area in open shape (after immersion in hot water)". The ratio of the open hole area to the closed hole area ((open hole area in open shape) / (closed hole area) x 100) was calculated as the "open hole ratio after immersion in hot water" according to this test example. The results are shown in Table 2.

[0154] [Table 2]

[0155] As shown in Table 2, the sheet of Comparative Example 2-1 was softened somewhat by immersion in hot water, but the pore ratio after immersion in hot water was 90%, and there was almost no change in the open pore area. Moreover, in Comparative Example 2-2, where no pores were formed, the pore ratio could not be defined in the first place.

[0156] On the other hand, the pore ratios of the samples of Examples 2-1 to 2-3 after immersion in hot water were all 200% or more, and it was found that the pores were opened by immersion in hot water. In addition, the pore ratio of the sample of Example 2-1 in which the connecting portion was configured to bend along the MD direction was larger than that of the sample of Example 2-2 in which the connecting portion was configured to bend along the CD direction. From this, it was found that by forming an opening portion in which the connecting portion is bent along the MD direction, the opening was more reliably opened by immersion in hot water. Furthermore, from the results of Examples 2-1 and 2-3, it was found that by setting the angle between the lid portion and the second main surface at the time of forming the opening to 90 degrees or less, the opening was more reliably opened by immersion in hot water.

[0157] [Test Example 3 Test Example According to the Third Embodiment] In test example 3, a first opening portion with an open shape and a second opening portion with a closed shape were formed in a nonwoven fabric sample containing shape memory fibers, and it was examined whether these opened and closed when immersed in warm water.

[0158] (Example 3-1) As a sample of Example 3-1, a nonwoven fabric sample having a first open hole and a second closed hole was produced. First, a flat sheet-like original nonwoven fabric similar to that of Example 1-1 was produced. Then, a processing roll (first support) having an I-shaped convex portion and a flat roll facing it were prepared. The two rolls were heated to 80°C. The shape and arrangement of the convex portion of the processing roll were the same as those of Example 2-1.

[0159] While rotating these two rolls, the original nonwoven fabric was pressed against the processing roll by the flat roll, cutting the original nonwoven fabric open. Here, the width dimension of the base of the second cut part of the processing roll was set to 4.0 mm. This resulted in the formation of second open holes in the original nonwoven fabric, producing a first intermediate nonwoven fabric. The connecting part of the lid part of this second hole was provided so as to intersect with the MD direction. The original nonwoven fabric after the formation of the second holes was cooled to room temperature.

[0160] As shown in Table 3, the thickness of the nonwoven fabric body of this sample was 1.0 mm. The basis weight of this sample was 112 g / m 2 In the open shape, the angle between the lid portion and the second main surface was 90 degrees.

[0161] Next, two opposing flat rolls maintained at room temperature were prepared. Then, while rotating these two rolls, the first intermediate nonwoven fabric was sandwiched between the two rolls to flatten the first intermediate nonwoven fabric. This resulted in the formation of a second intermediate nonwoven fabric having a closed second aperture. After this flattening process, the aperture body of the second aperture was entirely covered with the lid.

[0162] Next, a processing roll (second support) having an H-shaped convex portion and a flat roll facing it were prepared. The two rolls were kept at room temperature. The shape and arrangement of the convex portion of the processing roll were the same as those in Example 1-1.

[0163] While rotating these two rolls, the second intermediate nonwoven fabric was pressed against the processing roll by the flat roll, cutting the second intermediate nonwoven fabric open. Here, the width dimension of the base of the second cut part of the processing roll was set to 3.5 mm. As a result, an open-shaped first opening part was formed in the second intermediate nonwoven fabric, and a nonwoven fabric sample was produced. The connecting part of this first opening part was bent along the MD direction. In the open shape, the angle between the lid part and the second main surface was 90 degrees.

[0164] (Example 3-3) A nonwoven fabric sample of Example 3-3 was produced in the same manner as Example 3-1, except that the width dimension of the base of the second cut portion of the first processing roll and the second processing roll was 1 mm. As shown in Table 3, the angle between the second lid portion and the second main surface in the open shape and the angle between the first lid portion and the second main surface in the open shape were both 120 degrees.

[0165] (Example 3-2) A nonwoven fabric sample of Example 3-2 was produced in the same manner as in Example 3-1, except that the orientation of the original nonwoven fabric sandwiched between the first processing roll and the second processing roll was rotated 90 degrees. The connecting portion of the lid portion of this second opening portion was bent along the CD direction. As shown in Table 3, the angle between the lid portion and the second main surface in the open shape was 90 degrees.

[0166] (Comparative Example 3-1) As a nonwoven fabric sample of Comparative Example 3-1, a flat original nonwoven fabric similar to that of Example 3-1 was prepared, and an opening was formed in this original nonwoven fabric by piercing a pin. Specifically, the position of the original nonwoven fabric was fixed by a fixture, and a pin was pierced in the same position as the opening in Example 3-1. In the sample of Comparative Example 3-1, a lid portion was not formed. Therefore, the opening area did not change before and after the flattening process. In addition, the pin piercing used in Comparative Example 3-1 did not allow the formation of a second opening portion having a closed shape.

[0167] (Comparative Example 3-2) As a nonwoven fabric sample of Comparative Example 3-2, a flat original nonwoven fabric without openings formed therein and before processing in Example 3-1 was prepared.

[0168] (Evaluation of pore opening rate after immersion in hot water) A sheet-like sample of each Example and Comparative Example was cut to 10 cm x 10 cm. The cut sample was placed on a flat work table, and the sample was imaged from above in the thickness direction. This image was analyzed, and the open area of ​​any 10 first open holes and second open holes in the cut sample was calculated, and the average value of these was measured. As shown in Table 3, this average value was designated as the "open area before immersion in hot water." Warm water at 40°C was added to a tray large enough to hold the cut sample. The cut sample was immersed in the warm water in the tray for 30 seconds. After removing the sample from the warm water, the average area of ​​10 randomly selected holes was measured for each of the first and second holes. These average values ​​were designated as the "open area after immersion in warm water." For the first open hole portion, the ratio of the open hole area after immersion in hot water (closed shape) to the open hole area before immersion in hot water (open shape) ((open hole area in closed shape) / (open hole area in open shape)×100) was calculated as the "open hole ratio after immersion in hot water". For the second open hole portion, the ratio of the open hole area after immersion in hot water (open shape) to the open hole area before immersion in hot water (closed shape) ((open hole area in open shape) / (open hole area in closed shape)×100) was calculated as the "open hole ratio after immersion in hot water" for this test example. The results are shown in Table 3.

[0169] [Table 3]

[0170] As shown in Table 3, the sheet of Comparative Example 3-1 was softened somewhat by immersion in hot water, but the pore ratio after immersion in hot water was 90%, and there was almost no change in the open pore area. Moreover, in Comparative Example 3-2, in which no pores were formed, the pore ratio could not be defined in the first place.

[0171] On the other hand, the aperture ratio of the first opening portion in the samples of Examples 3-1, 3-2, and 3-3 after immersion in hot water was 80% or less in all cases, and it was found that the opening area was reduced by immersion in hot water. Also, as in Test Example 1, the aperture ratio of the sample of Example 3-1 in which the connecting portion is configured to bend along the MD direction was smaller than that of the sample of Example 3-2 in which the connecting portion is configured to bend along the CD direction. From this, it was found that by forming an opening portion in which the connecting portion is bent along the MD direction, the opening area is more reliably reduced by immersion in hot water. Furthermore, from the results of Examples 3-1 and 3-3, it was found that the opening area is more reliably reduced by immersion in hot water by setting the angle between the first lid portion and the second main surface to 90 degrees or less.

[0172] In the samples of Examples 3-1, 3-2, and 3-3, the aperture ratio after the second hot water immersion was 200% or more, and it was found that the holes were opened by the immersion in hot water. In addition, the aperture ratio of the sample of Example 3-1 in which the connecting portion is configured to bend along the MD direction was larger than that of the sample of Example 3-2 in which the connecting portion is configured to bend along the CD direction. From this, it was found that the holes were opened more reliably by immersion in hot water by forming the openings in which the connecting portion is bent along the MD direction. Furthermore, from the results of Examples 3-1 and 3-3, it was found that the holes were opened more reliably by immersion in hot water by setting the angle between the second cover portion and the second main surface at the time of forming the openings to 90 degrees or less.

[0173] Thus, the results of this test example demonstrate that it is possible to produce a nonwoven fabric that includes both first openings that switch to a closed shape when stimulated by warm water, and second openings that switch to an open shape. [Explanation of symbols]

[0174] 10,10A,10B,10C Non-woven fabric 11 Nonwoven fabric body 20 Opening part 21 Hole body 22 Lid 23 Connecting part 20A 1st hole 20B 2nd hole 1A, 1B, 1C Absorbent articles

Claims

1. A nonwoven fabric containing shape memory fibers, The nonwoven fabric is A nonwoven fabric body, a plurality of openings formed in the nonwoven fabric body, Each of the plurality of openings is an aperture body opening in the thickness direction of the nonwoven fabric; a lid portion configured to be able to cover the hole body, the lid portion has a connecting portion connected to the nonwoven fabric main body, Each of the plurality of openings is When immersed in warm water at 40°C for 30 seconds, the connecting portion is bent in the thickness direction, so that the opening body is switched between an open shape and a closed shape in which the opening area in a plan view is smaller than that of the open shape. Nonwoven fabric.

2. The plurality of openings are The first opening portion switches from the open shape to the closed shape when immersed in hot water at 40°C for 30 seconds. The nonwoven fabric of claim 1.

3. The plurality of openings are The second opening portion is configured to switch from the closed state to the open state when immersed in hot water at 40°C for 30 seconds. The nonwoven fabric of claim 1.

4. The aperture body of the second aperture portion is configured in a groove shape. The nonwoven fabric according to claim 3.

5. The nonwoven fabric has a fiber orientation direction perpendicular to the thickness direction and a direction perpendicular to the fiber orientation direction, The connecting portion intersects with the fiber orientation direction. The nonwoven fabric of claim 1.

6. In the nonwoven fabric, the angle formed by the bent connecting portions in the open shape with respect to a main surface extending on a plane perpendicular to the thickness direction is 30 degrees or more and 130 degrees or less. The nonwoven fabric of claim 1.

7. The nonwoven fabric is a nonwoven fabric for absorbent articles. The nonwoven fabric according to any one of claims 1 to 6.

8. A device comprising the nonwoven fabric according to any one of claims 1 to 6. Absorbent articles.

9. A method for producing a nonwoven fabric containing shape memory fibers, comprising: The method includes a first cutting step of pressing an original nonwoven fabric containing shape memory fibers against a first support having a plurality of first protrusions, and cutting open the original nonwoven fabric with the plurality of first protrusions to form a plurality of second open apertures. Method for manufacturing nonwoven fabric.

10. In the first cutting step, the first support is heated to a temperature of 80° C. or higher and 200° C. or lower, The method further includes a flattening step, after the first cutting step, of flattening the plurality of open second apertures formed in the original nonwoven fabric at 60° C. or less to form the plurality of closed second apertures. A method for producing the nonwoven fabric according to claim 9.

11. a second cutting step of further forming the plurality of open first apertures in the intermediate nonwoven fabric in which the plurality of closed second apertures has been formed by the flattening step, a second cutting step of pressing the intermediate nonwoven fabric against a second support maintained at 60°C or less, the second support having a plurality of second convex portions arranged in a pattern different from the plurality of first convex portions, and cutting open the intermediate nonwoven fabric with the plurality of second convex portions, thereby forming a plurality of first aperture portions having an open shape; the first opening portion switches from the open shape to the closed shape when immersed in warm water at 40°C for 30 seconds; the second opening portion switches from the closed shape to the open shape when immersed in warm water at 40°C for 30 seconds; A method for producing the nonwoven fabric according to claim 10.

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