JP7527956B2 - Non-woven construction - Google Patents

Description

The present invention relates to a nonwoven structure.

In absorbent articles such as diapers and sanitary napkins, a rounded nonwoven fabric may be used in the portion that comes into contact with the skin. In some cases, the folded nonwoven fabric is provided with a thread-like elastic member to form a gather portion. For example, in a diaper, a waist gather portion that comes into contact with the skin around the wearer's waist is included. In a diaper or a sanitary napkin, a three-dimensional gather portion that comes into contact with the skin around the wearer's crotch is included.
For example, Patent Document 1 discloses a diaper having a pair of left and right standing gathers arranged on both left and right sides of an absorbent body. The standing gathers are formed by arranging an elastic member on the back surface side of a topsheet.
Patent Document 2 describes a diaper having a pair of standing gathers on the skin contact surface side of the topsheet. The pair of standing gathers has free ends in which the sidesheet is folded back along the longitudinal direction and an elastic body is sandwiched between the pair of standing gathers.
Patent Document 3 describes a sanitary napkin with standing gathers on both sides of the use surface side. The standing gathers are composed of a hollow loop-shaped cross section and free end portions standing on the outer sides of the loop-shaped portions in the width direction.

JP 2000-83999 A Special table 2017-118962 publication JP 2012-205638 A

The folded nonwoven fabric described above, even if it has gathers made of an elastic material, is prone to crushing the rounded parts of the folds, making it difficult to maintain its three-dimensional appearance, and there is room for improvement in this regard. In addition, crushing can reduce the breathability inside the folds and the good fit to the skin, leaving room for further improvement.

In view of the above, the present invention relates to a nonwoven fabric structure that is less prone to crushing during use and is more likely to maintain its three-dimensional shape.

The present invention provides a nonwoven fabric structure using a nonwoven fabric sheet, the nonwoven fabric sheet comprising outer surface fiber layers on the front and back surfaces of the nonwoven fabric sheet, and a plurality of connecting parts arranged between the outer surface fiber layers on the front and back surfaces, with the fibers oriented in the thickness direction of the nonwoven fabric sheet, and a concave-convex structure consisting of the connecting parts and the outer surface fiber layers on the front and back surfaces on one side of the front and back surfaces, the nonwoven fabric sheet being folded back so that the surface having the concave-convex structure is on the inside, the nonwoven fabric sheet has a palm-to-palm laminated part where the nonwoven fabric sheets are joined together, and a folded-back end where the nonwoven fabric sheets are not joined together, and the outer shape of the folded-back end includes a convex curved surface.

The nonwoven fabric structure of the present invention is less susceptible to crushing at the folded ends and is more likely to maintain its three-dimensional shape.

1A and 1B are drawings that typically show a preferred embodiment of a nonwoven fabric structure according to the present invention, in which FIG. 1A is an enlarged perspective cross-sectional view, and FIG. 1B is an enlarged cross-sectional view of part A in FIG. 1A. 1 is a perspective cross-sectional view that illustrates a preferred embodiment (Example 1) of a nonwoven fabric sheet that constitutes a nonwoven fabric structure according to the present invention. FIG. 1 is a perspective cross-sectional view that illustrates a preferred embodiment (Example 2) of a nonwoven fabric sheet that constitutes the nonwoven fabric structure according to the present invention. FIG. 1 is a perspective cross-sectional view that illustrates a preferred embodiment (Example 3) of a nonwoven fabric sheet that constitutes the nonwoven fabric structure according to the present invention. FIG. 1 is a perspective cross-sectional view that illustrates a preferred embodiment (Example 4) of a nonwoven fabric sheet that constitutes the nonwoven fabric structure according to the present invention. FIG. 1 is a perspective view showing a typical example of a diaper to which the nonwoven fabric structure of the present invention is applied. FIG. 1 is a partially cutaway perspective view showing a schematic diagram of a specific example of a diaper to which the nonwoven fabric structure of the present invention is applied.

A preferred embodiment of the nonwoven fabric structure according to the present invention will be described below with reference to Figs. 1(A) and (B). Note that in Fig. 1(A), the projections 4 and depressions 5 (see Fig. 1(B)) of the nonwoven fabric sheet 11 are omitted.

As shown in FIGS. 1(A) and 1(B), the nonwoven fabric structure 10 of this embodiment is composed of a nonwoven fabric sheet 11.
The nonwoven fabric sheet 11 comprises outer fiber layers 1, 2 constituting the front and back surfaces of the nonwoven fabric sheet 11, and a plurality of connecting portions 3 disposed between the outer fiber layers 1, 2 on the front and back surfaces and having fibers oriented in the thickness direction of the nonwoven fabric sheet 11. One of the front and back surfaces has an uneven structure 12 consisting of the connecting portions 3 and the outer fiber layers 1, 2 on the front and back surfaces. The uneven structure 12 has convex portions 4 and concave portions 5 arranged alternately in the surface direction of the sheet surface of the nonwoven fabric sheet 11.
The alternating arrangement of the convex portions 4 and the concave portions 5 is preferably in at least one direction in the plane of the sheet surface of the nonwoven fabric sheet 11, and more preferably in a plurality of different directions intersecting each other in the plane direction. For example, when the nonwoven fabric sheet 11 has a longitudinal direction and a transverse direction, it is preferable that the convex portions 4 and the concave portions 5 are alternately arranged in at least one of the longitudinal direction and the transverse direction, and it is more preferable that the convex portions 4 and the concave portions 5 are alternately arranged in both the longitudinal direction and the transverse direction.

The nonwoven fabric structure 10 is formed by folding back the nonwoven fabric sheet 11 with the side having the uneven structure 12 facing inward. By this folding back, the nonwoven fabric structure 10 has a palm-to-palm laminated section 15 where the nonwoven fabric sheets 11 are joined together, and a folded-back end section 13 where the nonwoven fabric sheets 11 are not joined together. Note that when the uneven structure 12 is on both sides of the nonwoven fabric sheet 11, either side may be on the inside.

The nonwoven fabric structure 10 has a direction W in which the folded end 13 and the palm-to-palm laminated portion 15 extend, a folding direction J of the folded end 13, a thickness direction T of the folded end 13, and a height direction H of the folded end 13. The folding direction J is also called the curvature direction J. Furthermore, the nonwoven fabric structure 10 has a direction S toward the inner center of the folded end 13.

The palm-to-palm laminated portion 15 is formed by overlapping the sheet ends of the folded nonwoven fabric sheet 11 and joining them by fusion or adhesion. This allows the nonwoven fabric structure 10 to be integrated in the folded state. The length of the palm-to-palm laminated portion 15 in the height direction H can be appropriately determined depending on the member to which it is applied.

The folded end 13 is made by bending the nonwoven fabric sheet 11 without creating any creases, leaving it in an unbonded state. "Bent" refers, for example, to bending the folded end so that its cross section is rounded. The folded end 13 can be divided into three equal parts based on its annular cross section: tip 131 (the part farthest from the folded laminated section 15), middle section 132, and base section 133 (the part connected to the folded laminated section 15).

The outer shape of the folded end 13 which is bent without creating a crease includes a convex curved surface.
This is due to the uneven structure 12 facing the inside of the folded end 13. That is, inside the folded end 13, with the nonwoven fabric sheet 11 in a non-bonded state, the convex portions 4 and concave portions 5 of the uneven structure 12 are arranged alternately and adjacently. Therefore, inside the folded end 13, a continuous row of adjacent convex portions 4 and concave portions 5, particularly adjacent convex portions 4, 4, act to support each other and maintain their shape, and the outer shape of the folded end 13 has a convex curved surface. As a result, the folded end 13 has a ring-shaped or cylindrical shape, which makes it easier to maintain its shape.

The "outer shape of the folded end 13" refers to the contour shape formed by connecting the outermost surfaces of the folded end 13. When the nonwoven fabric sheet 11 has an uneven structure on both sides, the "outer shape of the folded end 13" refers to the contour shape formed by connecting the apexes of the convex parts corresponding to the outermost surfaces in the uneven structure arranged on the outer surface of the folded end 13.
The term "convex curved surface" refers to a surface whose outer shape is curved outward in a convex manner. It is preferable that this convex curved surface does not have any corners that impair the continuity of the curved surface in the aforementioned outline shape. Examples of such corners include linear folds and point-like protrusions or depressions in the nonwoven fabric sheet 11.

The folded end 13 including such a convex curved surface has a rounded outer shape and has a soft feel that is gentle on the skin. As described above, inside the folded end 13, the convex portions 4, 4 of the uneven structure 12 act to support each other against an external force, and the concave portions 5 act to pull the convex portions 4, 4 apart, thereby acting as a resistance against the external force.
In particular, the protrusions 4, 4 are most likely to approach each other at the tip 131 and the base 133, and the resulting resistance is likely to act. Among them, the top 13P of the tip 13 and the bottom 13M of the base 133 are the parts where the protrusions 4, 4 are most likely to approach each other first, and the resistance is likely to act quickly against the external force. Therefore, the convex curved surfaces of the top 13P of the tip 13 and the bottom 13M of the base 133 are particularly likely to be maintained against the external force. In addition, the resistance at the tip 131 and the base 133 is likely to spread to the entire annular uneven structure 12 of the folded end 13, and can become a force supporting the arch of the intermediate portion 132.
As a result, the convex curved surface of the folded end 13 of the nonwoven fabric structure 10 of this embodiment is less likely to be crushed, and the annular three-dimensional shape is more likely to be maintained. As a result, the soft feel that is gentle on the skin due to the rounded outer shape of the folded end 13 is more likely to be maintained. In addition, the nonwoven fabric structure 10 has better conformability to the skin surface, improving the fit.

The outer shape of the folded end 13 is preferably configured as a continuous convex curved surface. In other words, it is preferable that the outer contour of the entire folded end 13 is a continuous convex curved surface without corners. This gives the entire folded end 13 a rounded outer shape, further enhancing the aforementioned soft, skin-friendly feel of the nonwoven fabric structure 11.

In addition, it is preferable that the nonwoven fabric structure 11 has a cylindrical space 14 inside the folded end 13, in which the opposing concave-convex structures 12 are separated from each other.
The cylindrical space 14 refers to a section that is arranged inside the folded end 13 and in a natural state where no external force is applied to the nonwoven fabric structure 11, and where opposing convex portions 4, 4 are spaced apart so as not to come into contact with each other. This cylindrical space 14 is easily maintained while being deformed by the action of the resistance against external forces by the uneven structure 12 described above.
Here, "being in an opposing position" means being in a position facing each other in the natural state described above in the annular concave-convex structure 12 forming the outer wall of the cylindrical space 14. This is not limited to a strict positional relationship, and for example, the positional relationship in which the tip portion 131, the intermediate portion 132, and the base portion 133 face each other in the thickness direction T is considered to be in an "opposite position". Also, the positional relationship in which the tip portion 131 and the base portion 133 face each other is considered to be in an "opposite position".
The projections 4, 4 may be spaced apart from each other over the entire annular shape shown in the cross section of the folded end 13, or may be spaced apart from each other over a part of the annular shape. It is preferable that the projections 4, 4 are spaced apart from each other at least in the intermediate portion 132 in the above-mentioned natural state.

In the above-mentioned natural state, the cylindrical space 14 is preferably continuous along the extending direction W of the folded end 13. This continuous state of the cylindrical space 14 is easily maintained even while being deformed by the action of the resistance against external force by the uneven structure 12 described above.
The term "continuous" means that the cylindrical space 14 is in communication with the flow of a fluid such as air. As long as the flow is obtained, the size of the cylindrical space 14 does not necessarily have to be the same along the extending direction W of the folded end 13. For example, the cylindrical space 14 may be partially changed due to the deformation of the uneven structure 12. In addition, as long as the flow is obtained, the cylindrical space 14 does not have to be linear along the extending direction W of the folded end 13, and may be meandering.

In the nonwoven fabric structure 10 of this embodiment, the presence of the cylindrical space 14 at the folded end 13 as described above makes it easier to ensure breathability at the folded end 13.

Next, a preferred embodiment of the nonwoven fabric sheet 11 will be described.
As shown in Fig. 1(B) above, the nonwoven fabric sheet 11 has outer fiber layers 1, 2 on a first side 1A and a second side 1B opposite to the first side 1A, with the fibers oriented in the plane direction of the sheet surface. The outer fiber layers 1, 2 form the outermost surfaces of the front and back surfaces of the nonwoven fabric sheet 11 on the first side 1A and the second side 1B, respectively, and have flat portions. In Fig. 1(B), the first side 1A is the inside of the nonwoven fabric structure 10 and the folded end 13. The plane direction of the sheet surface in which the fibers of the outer fiber layers 1, 2 on the first side 1A and the second side 1B are oriented corresponds to the folding direction J of the folded end 13 of the nonwoven fabric structure 10 shown in Fig. 1(A) .
In addition, the nonwoven fabric sheet 11 has a plurality of connecting parts 3 disposed between the outer fiber layer 1 on the first side 1A and the outer fiber layer 2 on the second side 1B, with the fibers oriented in the thickness direction of the nonwoven fabric sheet 11. The thickness direction in which the fibers are oriented in the connecting parts 3 corresponds to the direction S toward the inner center of the folded end 13 of the nonwoven fabric structure 10 shown in Figure 1 (B).
The nonwoven fabric sheet 11 has a thickness with a resilience in the thickness direction because the connecting parts 3 connect and support the outer fiber layers 1, 2 on the first side 1A and the second side 1B. This thickness means an apparent thickness, which will be described later, and does not mean the local thickness of only the outer fiber layers 1, 2 or the connecting parts 3, but means the thickness between the front and back surfaces of the entire nonwoven fabric sheet 11 in its shaped form.

The nonwoven fabric sheet 11 has an uneven structure 12 on the first side 1A, in which convex portions 4 and concave portions 5 between the convex portions 4, 4, which are formed by the outer fiber layer 1 and connecting portions 3 on the first side 1A, are alternately arranged. The outer fiber layer 2 on the second side 1B forms the bottom of the concave portions 5.
The protrusions 4 have a columnar protruding structure having a flat top formed by the outer fiber layer 1 on the first side 1A and wall surfaces formed by the connecting parts 3. That is, the connecting parts 3 in the nonwoven fabric sheet 11 connect the outer fiber layers 1 and 2 so as to be perpendicular to each other, so that the cross-sectional outline of the protrusions 4 is rectangular. The recesses 5 are box-shaped spaces with the outer fiber layer 2 as their bottom (recess bottom) and the connecting parts 3 as their wall surfaces, which are open to the first side 1A.

In such a nonwoven fabric sheet 11, the fibers of the connecting parts 3 are oriented in the thickness direction, so that the connecting parts 3 can support a load in the thickness direction. This nonwoven fabric sheet 11 has improved thickness retention (compression resistance) and is less likely to be crushed even when pressed, and the thickness of the uneven structure 12 is easily restored, resulting in improved cushioning properties.
In addition, in the nonwoven fabric structure 10 made of this nonwoven fabric sheet 11, the convex curved surface forming the outer shape of the folded end 13 is less likely to be crushed, and the annular three-dimensional shape is more likely to be maintained. As a result, the nonwoven fabric structure 10 maintains a soft feel against the skin, and has better conformability to the skin surface and improved fit. Furthermore, the cylindrical space 14 formed by the folded end 13 is more easily maintained, and breathability at the folded end 13 is more easily ensured.

As shown in Fig. 1(B), the nonwoven fabric sheet 11 preferably has an uneven structure on the first side 1B in addition to the uneven structure on the first side 1A. As shown in Fig. 1(B), the uneven structure on the second side 1B is preferably a structure in which convex portions 6 formed by the outer surface fiber layer 2 and the connecting portion 3 and concave portions 7 formed by the connecting portion 3 and the inner surface fiber layer 1 are alternately arranged. In this case, it is preferable that the uneven structure on the first side 1A and the uneven structure on the second side 1B are in a front-back relationship. Specifically, it is preferable that the convex portions 6 on the second side 1B become concave portions 5 on the first side 1A, and the concave portions 7 on the second side 1B become convex portions 4 on the first side 1A. In this case, the convex portions 4 on the first side 1A have hollow portions open to the second side 1B, which is preferable from the viewpoint of increasing breathability.
By providing the nonwoven fabric sheet 11 with the above-mentioned uneven structure on the front and back surfaces, the nonwoven fabric structure 10 formed from the nonwoven fabric sheet 11 has a higher resistance to the above-mentioned external force. This makes it difficult for the convex curved surface forming the outer shape of the folded end 13 to be crushed, and makes it easier to maintain the annular three-dimensional shape.

In the outer surface fiber layers 1 and 2 on the first surface side 1A and the second surface side 1B of the nonwoven fabric sheet 11, "fibers are oriented in a planar direction" means that the longitudinal orientation rate of the fibers is less than 45% as measured by the measurement method described below. By making the longitudinal orientation rate of the fibers less than 45%, the fibers are sufficiently aligned in the planar direction and a flat shape can be maintained. From the viewpoint of maintaining the shape and strength of the nonwoven fabric sheet 11, it is more preferable that the longitudinal orientation rate of the fibers of the outer surface fiber layers 1 and 2 oriented in the planar direction is 30% or more. In addition, it is preferable to make the longitudinal orientation rate of the fibers of the outer surface fiber layers 1 and 2 on the first surface side 1A and the second surface side 1B less than 40% because it is easy to contact with a flat surface like a normal flat nonwoven fabric, and it is more preferable to make it 38% or less, and even more preferable to make it 37% or less.

In the connecting portion 3, "the fibers are oriented in the thickness direction" means that the longitudinal orientation rate of the fibers is 60% or more, as determined by the measurement method described below. When the connecting portion 3 has a longitudinal orientation rate of the fibers in this range, it can be said that the connecting portion 3 is arranged perpendicular to the thickness direction of the nonwoven fabric sheet 11. The connecting portion has a longitudinal orientation rate of the fibers of 60% or more, and has some fusion between the fibers, so that the connecting portion stands up like a column. From the viewpoint of easily maintaining the three-dimensional shape, the longitudinal orientation rate of the fibers in the connecting portion 3 is preferably 63% or more, more preferably 65% or more, and even more preferably 67% or more. There is no particular upper limit, but from the viewpoint of forming fusion points by creating intersections between the fibers and forming columns between the fibers to create a structure that can withstand force, the longitudinal orientation rate is preferably 90% or less, more preferably 85% or less, and even more preferably 80% or less.

The outer fiber layers 1, 2 on the first side 1A and the second side 1B and the connecting portion 3 are each classified as a region in which the longitudinal orientation rate of the fibers is within the above range. The connecting portion 3 is seamlessly connected to the outer fiber layers 1, 2 on the first side 1A and the second side 1B at the end, so that the fibers oriented in the planar direction and the fibers oriented in the thickness direction are mixed in that portion. In addition, in the portion in which the fibers oriented in the planar direction and the fibers oriented in the thickness direction are mixed, it is preferable that the longitudinal orientation rate of the fibers shows an oblique orientation of 45% to 60%, and it is more preferable that the longitudinal orientation rate of the fibers gradually changes from 45% to a sufficient longitudinal orientation of 60% or less.

(Method of measuring the longitudinal orientation ratio of fibers in the outer fiber layers 1 and 2 on the first side 1A and the second side 1B and in the connecting portion 3)
The longitudinal orientation ratios of the fibers in the outer fiber layers 1 and 2 on the first surface side 1A and the second surface side 1B and in the connecting portion 3 can be measured based on the following (1) and (2).
(1) Preparation of a cross section of a nonwoven fabric sheet 11 A cross section (longitudinal cross section) of the nonwoven fabric sheet 11 passing through the outer fiber layers 1 and 2 of the first surface side 1A and the second surface side 1B is prepared, the cross section being perpendicular to the direction in which the connecting portion 3 extends in the planar direction and passing through the center of the extending length. Alternatively, a cross section (longitudinal cross section) of the nonwoven fabric sheet 11 passing through the outer fiber layers 1 and 2 of the first surface side 1A and the second surface side 1B is prepared, the cross section being in the thickness direction at a position passing through the center of the recess 5. The cross section is to be cut out of the nonwoven fabric sheet 11 to be measured, measuring 5 mm x 5 mm or more.
(2) Measurement of the longitudinal orientation rate of fibers in the outer fiber layers 1, 2 on the first side 1A and the second side 1B and in the connecting portion 3 In the cross section of the nonwoven fabric sheet 11, the cross sections of the outer fiber layers 1, 2 on the first side 1A and the second side 1B and the connecting portion 3 are observed at a magnification of 35 times using a SEM (JCM-6000Plus manufactured by JEOL Ltd.). A square line of 0.5 mm x 0.5 mm is drawn on the observed image as a reference line. Each side of the square (reference line) is perpendicular to the thickness direction and the planar direction in the cross section of the nonwoven fabric sheet 11.
The total number of fibers passing through the reference line formed by each side of the square is counted. The fibers passing through the reference line of the square perpendicular to the planar direction of the nonwoven fabric sheet 11 are defined as the "number of horizontal fibers", and the fibers passing through the reference line of the square perpendicular to the thickness direction of the nonwoven fabric sheet 11 are defined as the "number of vertical fibers". The vertical orientation rate is calculated as (number of vertical fibers)/(number of horizontal fibers+number of vertical fibers)×100=vertical orientation rate (%). These are measured at four points each, and the average is taken as the value of the vertical orientation rate. The outer surface fiber layers 1, 2 and the connecting portion 3 are each cut out and measured.

The basis weight of the nonwoven fabric sheet 11 is preferably 50 g/m ² or less, more preferably 45 g/m ² or less, and even more preferably 40 g/m ² or less. By setting the basis weight in this range, the cost of the nonwoven fabric is reduced, and the nonwoven fabric is easily used as a nonwoven fabric for absorbent articles.
The nonwoven fabric sheet 11 preferably has a basis weight of 10 g/m ² or more, more preferably 13 g/m ² or more, and even more preferably 15 g/m ² or more. By setting the basis weight in this range, the nonwoven fabric can maintain a sufficient shape.

(Method of measuring basis weight)
The nonwoven fabric sheet 11 to be measured is cut to a size of 10 cm x 10 cm. If a size of 10 cm x 10 cm cannot be obtained, it is preferable to cut the sheet to an area as large as possible. The mass is measured using a scale (e.g., a balance), and the measured value is divided by the area of the nonwoven fabric sheet 11 to be measured to obtain the basis weight.

The thickness between the front and back sides of the nonwoven fabric sheet 11 is preferably 2 mm or more from the viewpoint of increasing the magnitude of the undulations in the uneven structure on the first surface side 1A, i.e., the depth of the recesses 5.
From the viewpoint of providing excellent flexibility and cushioning when in contact with the skin of a wearer, the thickness of the nonwoven fabric sheet 11 is preferably 2.3 mm or more, more preferably 2.5 mm or more, and even more preferably 2.8 mm or more. The upper limit of the thickness of the nonwoven fabric sheet 11 is not particularly limited, but from the viewpoint of easily maintaining the three-dimensional shape, it is preferably 10 mm or less, more preferably 8 mm or less, and even more preferably 6 mm or less.

The above "thickness between the front and back surfaces" does not refer to the local thickness of only the outer fiber layers 1 and 2 or the connecting portion 3, but refers to the apparent thickness between the front and back surfaces in the shaped shape of the entire nonwoven fabric. More specifically, the "thickness between the front and back surfaces" refers to the vertical distance between the horizontal surface and a virtual plane (horizontal plate) that contacts the outermost part of the side opposite to one side of the nonwoven fabric sheet 11 that contacts the horizontal surface when the nonwoven fabric sheet 11 is unfolded and laid out and placed on a horizontal surface (hereinafter, the vertical direction to the horizontal surface may be simply referred to as the "vertical direction"). The "thickness between the front and back surfaces" is, for example, the vertical distance between the position of the top of the convex part on one side and the position of the top of the convex part on the other side when the nonwoven fabric sheet 11 has an uneven shape on both sides. This "thickness between the front and back surfaces" is also called the apparent thickness.
The "thickness between the front and back surfaces" refers to the thickness when a load of 0.05 kPa is applied from the first surface side 1A using a horizontal plate. Specifically, it can be measured by the following method. Here, the "load of 0.05 kPa" refers to a load that suppresses fuzzing on the surface of the nonwoven fabric sheet 11, and is a light load (a light load that is not a compressive force that would crush the thickness of the nonwoven fabric sheet 11) necessary to properly measure the apparent thickness of the nonwoven fabric sheet 11. The load of 0.05 kPa is applied to the nonwoven fabric sheet 11 by placing a horizontal plate, for example, a circular flat plate with a diameter of 2.5 cm and a mass of 2.45 g, on the first surface side 1A of the nonwoven fabric sheet 11.

(Method for measuring thickness between front and back surfaces of nonwoven fabric sheet 11 under a load of 0.05 kPa)
The nonwoven fabric sheet 11 to be measured is cut to a size of 10 cm x 10 cm to prepare a measurement sample. Using a laser thickness gauge (high-precision displacement sensor ZS-LD80 (product name) manufactured by Omron Corporation; all laser thickness gauges used in this specification are of this type), a load of 0.05 kPa is applied to the first surface side 1A of the measurement sample using a horizontal plate, and the thickness is measured in this state. Measurements are taken at three locations, and the average value is regarded as the apparent thickness of the nonwoven fabric sheet 11 to be measured.
If the nonwoven fabric sheet to be measured is incorporated into a product, the adhesive strength of the adhesive or the like is weakened using a cooling means such as a cold spray, and the nonwoven fabric sheet is removed from the product before the above measurements are performed.
If it is not possible to take out a nonwoven fabric sheet measuring 10 cm x 10 cm, it is preferable to take out a sheet as large as possible.

In the nonwoven fabric structure 10 of this embodiment, the nonwoven fabric sheet 11 may have various patterns for the uneven structure on the first surface 1A. In addition, in the uneven structure on the first surface 1A, the inside of the protrusions 4 may be hollow or solid. Furthermore, the second surface 1B may be a flat surface without unevenness or may be a surface having an uneven structure.
Examples of the uneven structure on the first surface 1A of the nonwoven fabric sheet 11 include the uneven structures on the first surface 1A of the nonwoven fabric sheet 60 (Example 1), nonwoven fabric sheet 70 (Example 2), nonwoven fabric sheet 80 (Example 3), and nonwoven fabric sheet 90 (Example 4) described below. The nonwoven fabric sheets 60, 70, 80, and 90 having these uneven structures can incorporate the above-mentioned requirements as appropriate.
Preferred examples of these concave-convex structures will now be described.

As shown in FIG. 2, the nonwoven fabric sheet 60 (embodiment 1) has a first outer fiber layer 61A extending in the Y direction on the first surface side 1A and arranged at intervals in the X direction intersecting the Y direction. It further has a second outer fiber layer 61B connecting the first outer fiber layers 61A, 61A and extending in the X direction. A first connecting portion 63A extending perpendicularly to the thickness direction is connected to the end of the first outer fiber layer 61A. This forms a first convex portion 64A that protrudes to the first surface side 1A and has a length in the Y direction. In the first convex portion 64A, the first connecting portion 63A extends in the Y direction and forms a wall surface facing the X direction. In addition, a second connecting portion 63B extending perpendicularly to the thickness direction is connected to the end of the second outer fiber layer 61B. This forms a second convex portion 64B that protrudes to the first surface side 1A and has a length in the X direction. In the second protrusion 64B, the second connecting portion 63B extends in the X direction and forms a wall surface facing the Y direction. The first protrusion 64A and the second protrusion 64B both have a rectangular cross section and have a columnar three-dimensional protrusion structure.
The X direction and the Y direction can be any direction on the plane of the nonwoven fabric sheet 60. In particular, it is preferable that the Y direction is the longitudinal direction of the nonwoven fabric sheet 60, and the X direction is the transverse direction perpendicular to the longitudinal direction of the nonwoven fabric sheet 60. The longitudinal direction and the transverse direction are preferably the machine direction (MD) and the cross direction (CD) perpendicular to the machine direction during the manufacture of the nonwoven fabric sheet 60. It is also preferable that the Y direction is the direction W in which the folded end 13 and the palm-laminated portion 15 in the nonwoven fabric structure 10 extend. The matters related to the X direction and the Y direction also apply to the following embodiment examples.

In a plan view from the first surface side 1A of the nonwoven fabric sheet 60, two types of convex portions having different extending directions are arranged in a lattice pattern, intersecting each other, as described above. The lattice pattern prevents not only crushing in the thickness direction but also collapse in the planar direction, making it easier to maintain the uneven shape.
The area surrounded by the two types of convex portions is a concave portion 65 on the first side 1A. A rectangular outer fiber layer 62 on the second side 1B is disposed at the bottom of the concave portion 65. Two first connecting portions 63A and two second connecting portions 63B are vertically connected to four ends of the outer fiber layer 62 on the second side 1B. The concave portion 65 forms a box-shaped space portion open to the first side 1A, and a plurality of them are scattered in the planar direction. In the concave portion 65, the box-shaped space portion is surrounded by four connecting portions, and the connecting portions are connected to each other at right angles, so that the concave portion 65 is not easily crushed by pressure.
The fibers are oriented in the planar direction in the first outer fiber layer 61A and the second outer fiber layer 61B on the first side 1A and the outer fiber layer 62 on the second side 1B. The fibers are oriented in the thickness direction in the first connecting portion 63A and the second connecting portion 63B, although the wall faces in different directions (facing directions) in each case. This adds the aforementioned lattice-like convex structure, making the thickness more difficult to collapse.
Furthermore, in the nonwoven fabric sheet 60, the first outer fiber layer 61A and the second outer fiber layer 61B, which have different extending directions on the first surface side 1A, preferably have different fiber orientation directions in the planar direction. More preferably, the fibers of the first outer fiber layer 61A are oriented in the extending direction (Y direction), and the fibers of the second outer fiber layer 61B are oriented in the extending direction (X direction). This makes it more difficult for the lattice-shaped convex portions and the concave portions surrounded by the convex portions to be crushed.

In addition, the second surface side 1B of the nonwoven fabric sheet 60 has an uneven structure corresponding to the uneven structure of the first surface side 1A. That is, the convex portion 66 corresponding to the concave portion 65 of the first surface side 1A is arranged on the outer surface side 1B, and the concave portion 67 (first concave portion 67A and second concave portion 67B) corresponding to the convex portion 64 (first convex portion 64A and second convex portion 64B) of the first surface side 1A is arranged on the second surface side 1B. Due to the presence of the concave portion 67 on the second surface side 1B, the convex portion 64 on the first surface side 1A becomes a hollow portion that is open to the second surface side 1B. As a result, in the nonwoven fabric structure 10 consisting of this nonwoven fabric sheet 60, the convex curved surface of the folded end portion 13 is less likely to be crushed, and the annular three-dimensional shape can be more easily maintained.

In the nonwoven fabric sheet 70 (Example 2), as shown in Fig. 3, four connecting portions (two first connecting portions 73A and two second connecting portions 73B) are connected perpendicularly to the thickness direction to four ends of the rectangular outer fiber layer 71 on the first surface side 1A. This forms columnar protrusions 74 protruding from the first surface side 1A. A plurality of columnar protrusions 74 are scattered in the planar direction.
Between the columnar protrusions 74, 74 is a recess 75 (a first recess 75A extending in the Y direction and a second recess 75B extending in the X direction) on the first surface side 1A. An outer surface fiber layer 72 (a first outer surface fiber layer 72A extending in the Y direction and a second outer surface fiber layer 72B extending in the X direction) on the second surface side 1B is disposed at the bottom of the recess 75. The aforementioned connecting portions (first connecting portion 73A and second connecting portion 73B) extending perpendicularly in the thickness direction are connected to the ends of the outer surface fiber male 72 on the second surface side 1B.
In the first outer fiber layer 71 on the first side 1A and the outer fiber layer 72 on the second side 1B (the first outer fiber layer 72A and the second outer fiber layer 72B), the fibers are oriented in the planar direction. In the first connecting portion 73A and the second connecting portion 73B, although the directions in which the wall faces (facing directions) are different, the fibers are oriented in the thickness direction in both cases. This makes the thickness less likely to be crushed.

In addition, the second surface side 1B of the nonwoven fabric sheet 70 has an uneven structure corresponding to the uneven structure of the first surface side 1A. That is, the convex portions 76 (first convex portions 76A and second convex portions 76B) corresponding to the concave portions 75 (first concave portions 75A and second concave portions 75B) of the first surface side 1A are arranged on the second surface side 1B, and the concave portions 77 corresponding to the convex portions 74 of the first surface side 1A are arranged on the second surface side 1B. Due to the presence of the concave portions 75 on the second surface side 1B, the convex portions 74 of the first surface side 1A become hollow portions that are open to the second surface side 1B. As a result, the nonwoven fabric sheet 70, like the nonwoven fabric sheet 60, makes it difficult for the convex curved surface of the folded end portion 13 to be crushed, and makes it easier to maintain the annular three-dimensional shape.

In the nonwoven fabric sheet 80 (Example 3), as shown in FIG. 4, on the first surface side 1A, a first convex portion 84A in the form of vertical ridges protruding from the first surface side 1A extends in the Y direction and is arranged at intervals in the X direction intersecting the Y direction. The first convex portion 84A in the form of vertical ridges is composed of a first outer surface fiber layer 81A extending in the Y direction of the first surface side 1A and a first connecting portion 83A connecting to an end of the first outer surface fiber layer 81A and extending in the thickness direction. The connecting portion between the first connecting portion 83A and the first outer surface fiber layer 81A is curved. In the first convex portion 84A in the form of vertical ridges, the first connecting portion 83A extends in the Y direction and forms a wall surface facing the X direction. In addition, the second convex portion 84B, which is a horizontal ridge that protrudes from the first surface side 1A and extends in the X direction, is arranged to connect the first convex portion 84A, which is a vertical ridge. The second convex portion 84B is lower in the thickness direction than the first convex portion 84A, and has a shape in which the top is curved toward the second surface side 1B. This second convex portion 84B is composed of a second outer surface fiber layer 81B that extends in the X direction of the first surface side 1A and a second connecting portion 83B that connects to the end of the second outer surface fiber layer 81B and extends in the thickness direction. The connecting portion between the second connecting portion 83B and the second outer surface fiber layer 81B is curved. In the second convex portion 84B, which is a horizontal ridge, the second connecting portion 83B extends in the X direction and forms a wall surface facing the Y direction.

In a plan view from the first surface side 1A of the nonwoven fabric sheet 80, the above-mentioned two types of ridge-like protrusions are arranged in a lattice pattern, similar to the above-mentioned nonwoven fabric sheet 60. The lattice pattern prevents not only crushing in the thickness direction but also collapse in the planar direction, making it easier to maintain the shape.
In the nonwoven fabric sheet 80, the portion surrounded by the two types of convex portions is a concave portion 85 on the first surface side 1A, similar to the nonwoven fabric sheet 60 described above. The outer surface fiber layer 82 on the second surface side 1B is disposed at the bottom of the concave portion 85. Two first connecting portions 83A and two second connecting portions 83B are connected in the thickness direction to four ends of the outer surface fiber layer 82 on the second surface side 1B. The connecting portions between the first connecting portions 83A and the second connecting portions 83B and the outer surface fiber layer 82 on the second surface side 1B are curved. The concave portions 85 are cone-shaped spaces open to the first surface side 1A, and are scattered in a plurality of locations in the planar direction. In the concave portions 85, the cone-shaped spaces are surrounded by four connecting portions, making them less likely to be crushed by pressure.
The fibers are oriented in the planar direction in the first outer fiber layer 81A and the second outer fiber layer 81B on the first side 1A and the outer fiber layer 82 on the second side 1B. The fibers are oriented in the thickness direction in the first connecting portion 83A and the second connecting portion 83B, although the wall faces in different directions (facing directions) in each case. This adds the aforementioned lattice-like convex structure, making the thickness more difficult to collapse.
Furthermore, in the nonwoven fabric sheet 80, the first outer fiber layer 81A and the second outer fiber layer 81B, which have different extending directions on the first surface side 1A, preferably have different orientation directions in the planar direction of the fibers. It is more preferable that the fibers in the first outer fiber layer 81A are oriented in the extending direction (Y direction) and the fibers in the second outer fiber layer 81B are oriented in the extending direction (X direction). This makes it more difficult for the projections arranged in a lattice pattern to be crushed.

In addition, the second surface side 1B of the nonwoven fabric sheet 80 has an uneven structure corresponding to the uneven structure of the first surface side 1A. That is, a convex portion 86 corresponding to the concave portion 85 of the first surface side 1A is arranged on the second surface side 1B, and a concave portion 87 (first concave portion 87A and second concave portion 87B) corresponding to the convex portion 84 (first convex portion 84A and second convex portion 84B) of the first surface side 1A is arranged on the second surface side 1B. Due to the presence of the concave portion 87 on the outer surface side 1B, the convex portion 84 on the inner surface side 1A becomes a hollow portion that is open to the outer surface side 1B. As a result, the nonwoven fabric sheet 80 makes the convex curved surface of the folded end portion 13 less likely to be crushed, as in the case of the nonwoven fabric sheet 60, and can more easily maintain the annular three-dimensional shape.

In the nonwoven fabric sheet 90 (Example 4), as shown in FIG. 5, a plurality of streak-like convex portions 94 are arranged on the first surface side 1A, extending in the Y direction of the first surface side 1A and spaced apart in the X direction perpendicular to the Y direction. The streak-like convex portions 94 are composed of an outer surface fiber layer 91 extending in the Y direction of the first surface side 1A and a connecting portion 93 connecting an end of the outer surface fiber layer 91 and extending in the thickness direction. The connecting portion between the connecting portion 93 and the outer surface fiber layer 91 is curved, and the streak-like convex portions 94 are ridge-like with rounded corners. The outer surface fiber layer 91 on the first surface side 1A has a shape in which the height in the thickness direction is gradually increased and decreased along the Y direction and is connected in a ridge-like shape. In addition, the streak-like convex portions 94 have a shape in which the width in the X direction is gradually wavy along the Y direction in a plan view (wide portions and narrow portions are alternately connected).
Furthermore, the nonwoven fabric sheet 90 has streak-like recesses 95 on the first surface side 1A between the streak-like protrusions 94, 94. An outer surface fiber layer 92 extending in the Y direction on the second surface side 1B is disposed at the bottom of the recesses 95. A connecting portion 93 forming a wall surface extending in the Y direction and facing the X direction is connected in the thickness direction to the outer surface fiber layer 92 on the second surface side 1B. The connecting portion between the connecting portion 93 and the outer surface fiber layer 92 on the second surface side 1B is curved with rounded corners.
In the outer fiber layer 91 on the first surface side 1A and the outer fiber layer 92 on the second surface side 1B, the fibers are oriented in the planar direction. In the connecting portion 93, the fibers are oriented in the thickness direction. This makes it more difficult for the thickness to be crushed.

In addition, the second surface side 1B of the nonwoven fabric sheet 90 has an uneven structure corresponding to the uneven structure of the first surface side 1A. That is, a convex portion 96 corresponding to the concave portion 95 of the first surface side 1A is arranged on the second surface side 1B, and a concave portion 97 corresponding to the convex portion 94 of the first surface side 1A is arranged on the second surface side 1B. Due to the presence of this concave portion 95 on the second surface side 1B, the convex portion 94 of the first surface side 1A becomes a hollow portion that is open to the second surface side 1B. As a result, the nonwoven fabric sheet 90, like the nonwoven fabric sheet 60, makes it difficult for the convex curved surface of the folded end portion 13 to be crushed, and makes it easier to maintain the annular three-dimensional shape.

The uneven structure of the nonwoven fabric sheets 60 and 70 can be manufactured by the method described in paragraphs [0049] to [0057] of JP 2019-44319 A.
The uneven structure of the nonwoven fabric sheets 80 and 90 can be manufactured by the method described in paragraphs [0059] to [0065] of JP 2019-44320 A.
Furthermore, based on the manufacturing method described in the above document, it is possible to satisfactorily form connection parts in which the fibers are oriented in the thickness direction, regardless of the uneven structure of the nonwoven fabric sheet 11. That is, by subjecting the fiber web before the process of forming a nonwoven fabric by fusing the fiber intersections to a mechanical pressing process using the male support material and the female support material, it is possible to satisfactorily form connection parts in which the fibers are oriented in the thickness direction.

In the nonwoven fabric structure 10 of this embodiment, various forms of nonwoven fabric sheets 11 can be used as long as the uneven structure is not impaired. Among them, nonwoven fabric sheets 11 preferably have thermoplastic fibers and have fusion points between the fibers at the fiber intersections. This makes it easier to maintain the column-like standing state in the above-mentioned connecting portion 3, and to recover after compression. The fusion points are the parts where the fibers are bonded to each other at the contact points between the intersecting fibers by fusion of the thermoplastic resin components of the fibers themselves. More specifically, the fusion points are formed by, for example, heat treatment melting the surfaces of the thermoplastic fibers during the manufacturing process of the nonwoven fabric sheet, and fusing the fibers together. Examples of such nonwoven fabric sheets include thermal bonded nonwoven fabrics, and more specifically, air-through nonwoven fabrics (nonwoven fabrics in which the fusion points are formed by hot air treatment. Short fibers of 60 mm or less are mainly used) and spunbonded nonwoven fabrics (nonwoven fabrics in which molten resin is spun into yarn and then embossed to form the fusion points. Long fibers of 100 mm or more are mainly used). Air-through nonwoven fabrics are particularly preferred from the viewpoint of ensuring a good texture and high unevenness.

The thermoplastic fibers may be any fibers that are commonly used as materials for nonwoven fabrics without any particular limitations. For example, the fibers may be fibers made of a single resin component, or composite fibers made of multiple resin components. The composite fibers may have, for example, a core-sheath structure or a side-by-side structure.
When using composite fibers containing a low melting point component and a high melting point component as the thermoplastic fiber (for example, composite fibers having a core-sheath structure in which the sheath is a low melting point component and the core is a high melting point component), the temperature of the hot air blown onto the fiber web in the manufacturing process is preferably equal to or higher than the melting point of the low melting point component and lower than the melting point of the high melting point component. More preferably, the temperature is equal to or higher than the melting point of the low melting point component and 10°C lower than the melting point of the high melting point component, and even more preferably, the temperature is 5°C or higher than the melting point of the low melting point component and 20°C or lower than the melting point of the high melting point component. In addition, from the viewpoint of elasticity, the more the core of the core-sheath structure composite fibers have, the higher the elasticity. Therefore, it is preferable that the core component is larger in terms of cross-sectional area ratio. Specific examples of composite fibers having a core-sheath structure in which the sheath is a low melting point component and the core is a high melting point component include composite fibers having a core-sheath structure in which the sheath is a polyethylene resin (hereinafter also referred to as PE) and the core is a polyethylene terephthalate resin (hereinafter also referred to as PET).
Furthermore, in composite fibers with a core-sheath structure, when the resin component of the sheath has a lower glass transition point than the resin component of the core (hereinafter referred to as low glass transition point resin) (for example, the resin component of the core is PET and the resin component of the sheath is PE), the thickness recovery of the nonwoven fabric can be further improved by reducing the mass ratio of the low glass transition point resin component.

The nonwoven fabric structure 10 of the present embodiment can be used as various components in absorbent articles, for example, as a three-dimensional gathered portion that comes into contact with the skin around the crotch of a wearer, a waist gathered portion that comes into contact with the skin around the waist of a wearer, and the like.
The above-mentioned absorbent articles include various articles that absorb and retain excretory fluids from a wearer, such as diapers, sanitary napkins, panty liners, urine absorption pads, etc. Absorbent articles typically have a liquid-permeable top sheet, a back sheet, and an absorbent body sandwiched between them.

Next, a preferred example of the nonwoven fabric structure 10 of the present embodiment used as a waist gather portion of a pants-type diaper 100 (hereinafter, simply referred to as the diaper 100) will be described below with reference to Fig. 6. The pants-type diaper 100 may also be provided with a three-dimensional gather portion, which will be described later.
In FIG. 6, the uneven structure arranged on the nonwoven fabric structure 10 is omitted, and the details of the uneven structure are as described above with reference to FIGS. 1 to 5 (the same applies to FIG. 7).

As shown in FIG. 6, the diaper 100 comprises an exterior body 101 and an absorbent body 102 placed on its skin side. The exterior body 101 forms the outer shape of the diaper 100. The exterior body 101 has a front exterior body 101F and a rear exterior body 101R.

When worn, the diaper 100 has a ventral portion F that is disposed on the ventral side of the wearer, a dorsal portion R that is disposed on the dorsal side of the wearer, and a crotch portion C that is located between the ventral portion F and the dorsal portion R. The ventral portion F and the dorsal portion R are faced to each other with the crotch portion C as a folding axis. The diaper 100 is joined at side seal portions 103, 103 on both sides to form a ring-shaped waist portion D. With this configuration, the diaper 100 has a waist opening 104 with the upper end of the waist portion D open, and a pair of leg openings 105, 105 with both sides of the crotch portion C below the waist portion D open. The side seal portions 103 are formed by a method such as heat sealing or ultrasonic sealing.

The nonwoven fabric structure 10 of this embodiment can be applied to the waist gather portion 110 surrounding the waist opening 104 at the end of the waist circumference portion D. In this case, the nonwoven fabric structure 10 can be arranged so that the direction W in which the folded end portion 13 extends faces the waist circumference direction of the diaper 100. The folded end portion 11 of the nonwoven fabric structure 10 can be the end portion that contacts the skin surface of the waist gather portion 110, and the palm-seam laminated portion 15 can be arranged to form the waist circumference portion D. In this case, multiple elastic members are arranged on the nonwoven fabric sheet 11 of the nonwoven fabric structure 10. It is preferable that the elastic member is sandwiched between the nonwoven fabric sheets 11 in the palm-seam laminated portion 15. The size of the palm-seam laminated portion 15 in the nonwoven fabric structure 10 can be appropriately set to match the waist circumference portion D of the outer body 101.

At this time, the convex curved surface of the outer shape of the folded end 13 of the nonwoven fabric structure 10 of the waist gather portion 110 is less likely to be crushed, and the annular three-dimensional shape is easily maintained. This makes it soft to the touch against the skin, and also improves the fit to the skin, improving the wearing comfort. Furthermore, if there is a cylindrical space 14 inside the folded end 13, this cylindrical space 14 can improve the breathability.

Next, referring to FIG. 7, a preferred example of the nonwoven fabric structure 10 of this embodiment used as a three-dimensional gather portion of a tape-type diaper 200 (hereinafter, simply referred to as diaper 200) will be described below. The tape-type diaper 200 shown in the figure is a diaper that is laid out flat and slightly bent to be viewed from the inside (skin contact side).

As shown in FIG. 7, the diaper 200 has a longitudinal direction Y and a transverse direction X perpendicular to the longitudinal direction Y. Here, the longitudinal direction Y of the diaper 200 corresponds to the direction connecting the abdominal portion F, the crotch portion C, and the dorsal portion R, which correspond to the parts of the wearer's body when the absorbent article is worn. The transverse direction X of the diaper 200 is a direction perpendicular to the longitudinal direction Y, and corresponds to the direction connecting the left and right legs under the crotch of the wearer. As terms indicating the relative positional relationship in the thickness direction of the diaper 200, the side that contacts the wearer's skin is called the skin side or skin contact side or front side, and the opposite side is called the non-skin side or non-skin contact side or back side.

The diaper 200 includes a liquid-permeable top sheet 201 arranged on the skin-contacting side, a liquid-impermeable back sheet 202 arranged on the non-skin-contacting side, and a liquid-retentive absorbent 203 interposed between the top sheet 201 and the back sheet 202. The diaper 200 has a pair of fastening tapes 207 on both sides of the back portion R for fastening around the waist of the wearer.

In the diaper 200, first three-dimensional gathers 206, 206 formed by side sheets 205 are arranged on both sides of the top sheet 1 in the longitudinal direction Y. Furthermore, second three-dimensional gathers 210, 210 are arranged at the leg openings 209, 209. The first three-dimensional gathers 206 are arranged to abut against the skin on both sides of the wearer's crotch. The second three-dimensional gathers 210 are arranged to abut against the skin near the groin area, which is the base of the legs on the outside of the wearer's crotch.

The nonwoven fabric structure 10 of this embodiment can be applied to the first three-dimensional gather section 206 and the second three-dimensional gather section 210. In this case, the nonwoven fabric structure 10 can be arranged so that the direction W in which the folded end 13 extends is directed toward the longitudinal direction Y of the diaper 200. The folded end 11 of the nonwoven fabric structure 10 can be arranged to be in contact with the skin surface as a free end, and the palm-seated laminated section 15 can be arranged to be a fixed end of the diaper 200. In this case, multiple elastic members are arranged on the nonwoven fabric sheet 11 of the nonwoven fabric structure 10. It is preferable that the elastic member is sandwiched between the nonwoven fabric sheets 11 in the palm-seated laminated section 15. The size of the palm-seated laminated section 15 in the nonwoven fabric structure 10 can be appropriately set according to the first three-dimensional gather section 206 and the second three-dimensional gather section 210.

At this time, the first three-dimensional gathered portion 206 and the second three-dimensional gathered portion 210 are designed so that the convex curved surface of the outer shape of the folded end portion 13 of the nonwoven fabric structure 10 is less likely to be crushed, and the annular three-dimensional shape is easily maintained. This makes the garment soft to the touch against the skin, and also improves the fit to the skin, improving the wearing comfort.

The present invention will be explained in more detail below based on examples, but the present invention should not be construed as being limited thereto. In the examples, "parts" and "%" are all based on mass unless otherwise specified. In Table 1 below, "-" means that the item does not have a corresponding value, etc.

Example 1
(1) Preparation of nonwoven fabric sheet sample A fiber web with a target basis weight of 30 g/m2 was prepared using thermoplastic fibers of a core-sheath type (polyethylene terephthalate (PET) (core): polyethylene (PE) (sheath) = 5:5 (mass ratio)) with a fiber diameter of 1.8 ^dtex . A press-in shaping process was performed using a male support member and a female support member based on the description in paragraphs [0059] to [0065] of JP-A-2019-44320 to the center of the short direction of the fiber web. The shape of the uneven shaping at this time was as shown in FIG. 4 above. Next, the entire fiber web was made into a nonwoven fabric by the air-through method using hot air as shown in paragraphs [0059] to [0065] of the same publication. The hot air blowing process at this time was performed under conditions of a temperature of 163 ° C., a wind speed of 6 m/s, and a blowing time of 2 s.
The obtained nonwoven fabric was cut into a size of 400 mm in the longitudinal direction and 200 mm in the lateral direction to prepare a nonwoven fabric sheet sample of Example 1 composed of one sheet of nonwoven fabric.

The nonwoven fabric sheet sample had a basis weight of 32.8 g/m ^2. The nonwoven fabric sheet sample had an apparent thickness of 5.2 mm.
The nonwoven fabric sheet sample had the uneven shape shown in Figure 4, and had an outer fibrous layer 1 on the first side 1A, an outer fibrous layer 2 on the second side, and connecting portions 3 disposed between the two fibrous layers. The fibers in the connecting portions 3 were oriented in the thickness direction of the nonwoven fabric sheet sample, and the longitudinal orientation rate was 63%.

Next, the nonwoven fabric sheet sample was folded back along the short direction to produce a nonwoven fabric structure sample S1 with a folded end including a cylindrical space and a palm-to-palm laminated portion. The palm-to-palm laminated portion was created 5 cm from the cylindrical end, and the nonwoven fabric sheets 11, 11 were joined together with hot melt.

(Comparative Example 1)
An SMS nonwoven fabric used in the three-dimensional gathers of the commercially available baby diaper "Meries Sarasa Air Through L Size" (manufactured by Kao Corporation in 2020) was taken out (there was no vertical orientation because there were no uneven parts), and a cylindrical space was created in the same manner as in Example 1 to obtain nonwoven fabric structure sample C1 of Comparative Example 1.

(Comparative Example 2)
Using the web of Example 1, a flat air-through nonwoven fabric sheet was obtained by only performing a normal air-through treatment (temperature 145°C, wind speed 2 m/s, blowing time 3 s) (no unevenness, no longitudinal orientation). A cylindrical space was made in the same manner as in Example 1, and this was used as nonwoven fabric structure sample C2 of Comparative Example 2.

(Comparative Example 3)
A nonwoven fabric sheet having a shape shown in FIG. 1 of JP 2012-136791 A was produced by an air-through production method including the production process described in paragraph [0031] of the specification of the same document, using the thermoplastic fiber having a fiber diameter of 1.8 dtex in Example 1. This was used as a nonwoven fabric sheet sample of Comparative Example 3. The blowing treatment with the first hot air W1 was performed under conditions of a temperature of 160°C, a wind speed of 54 m/s, and a blowing time of 3 s. The blowing treatment with the second hot air was performed under conditions of a temperature of 160°C, a wind speed of 6 m/s, and a blowing time of 3 s. In the nonwoven fabric sheet sample of Comparative Example 3, both the first protrusions on the first surface side and the second protrusions on the second surface side were in a truncated cone shape or a hemisphere shape with a rounded apex. The longitudinal orientation rate was 52% for the first protrusions on the first surface side and the second protrusions on the second surface side, and the annular wall portion interposed between the first protrusions and the second protrusions.
Thereafter, a cylindrical space was formed in the same manner as in Example 1, and this was used as nonwoven fabric structure sample C3 for Comparative Example 3.

The following tests were carried out on the diaper samples of each of the Examples and Comparative Examples.
(1) Measurement of the size of the annular shape of the folded end Each nonwoven fabric structure sample with a cylindrical space was observed from the cross section, and the length (length in the thickness direction T) from one inner surface of the nonwoven fabric constituting the cylindrical shape to the inner surface of the other nonwoven fabric was measured using a ruler at the middle (2.5 cm from the cylindrical end) between the cylindrical end and the palm-to-palm laminated portion. That is, the annular space portion consisting of two nonwoven fabrics was measured. In this case, if it becomes a perfect arc, it will theoretically be 3.2 cm. When the space is 1.0 cm or more, the three-dimensional shape is excellent in maintenance, and when it is 1.6 cm or more, it is even better.
(2) Texture test Each nonwoven fabric structure sample with a cylindrical space was placed on a flat surface, and the texture of the cylindrical portion was evaluated. The three-dimensional gathers of the Merry's tape-type diaper of Comparative Example 1 were given a score of 1, and a relative evaluation was performed on a 5-point scale. A score of 3 or more was considered to indicate a strong texture, and a score of 4 or more was considered to indicate an even stronger texture.

From Table 1, it can be seen that the size of the annular shape in Example 1 is larger than that of the Comparative Example, and the shape with open spaces is maintained. This greatly improves the texture, making it suitable for three-dimensional gathers and waist gathers. The large space also leads to breathability and fit, which also makes it suitable for three-dimensional gathers and waist gathers in absorbent articles.

10 Nonwoven fabric structure 11, 60, 70, 80, 90 Nonwoven fabric sheet 12 Concave-convex structure 13 Folded end 131 Tip of folded end 132 Middle of folded end 133 Root of folded end 13P Top of tip of folded end 13M Bottom of root of folded end 14 Cylindrical space 15 Joint-laminated portion 1, 2 Outer surface fiber layer 3 Connecting portion 4 Convex portion 5 Concave portion

Claims (9)

A nonwoven fabric structure using a nonwoven fabric sheet,
The nonwoven fabric sheet comprises outer surface fiber layers on the front and back surfaces of the nonwoven fabric sheet, and a plurality of connecting portions disposed between the outer surface fiber layers on the front and back surfaces, the fibers being oriented in the thickness direction of the nonwoven fabric sheet, and one of the front and back surfaces has an uneven structure formed of the connecting portions and the outer surface fiber layers on the front and back surfaces,
The nonwoven fabric sheet is folded back with the surface having the uneven structure on the inside, and has a palm-to-palm laminated portion where the nonwoven fabric sheets are joined together and a folded-back end portion where the nonwoven fabric sheets are not joined together,
The outer shape of the folded end portion includes a convex curved surface,
In a natural state in which no external force is applied to the nonwoven fabric structure, a cylindrical space is formed inside the folded end portion, in which the opposing uneven structures are spaced apart from each other throughout the entire annular shape shown in the cross section of the folded end portion,
A nonwoven fabric structure , in which, in the annular shape shown in the cross section of the folded end, the uneven structure has alternating concave and convex portions arranged in an annular shape as the outer wall of the cylindrical space . The nonwoven fabric structure of claim 1, wherein the outer shape of the folded end portion is a continuous convex curved surface. The nonwoven fabric structure according to claim 1 or 2 , wherein the cylindrical space is continuous along the extending direction of the folded end portion. The nonwoven structure according to any one of claims 1 to 3 , wherein the nonwoven sheet has a basis weight of 50 g/ ^m2 or less. The nonwoven structure according to any one of claims 1 to 4 , wherein the nonwoven sheet has a basis weight of 10 g/ ^m2 or more. The nonwoven structure of any one of claims 1 to 5 , wherein the nonwoven sheet is an air-through nonwoven. The nonwoven fabric structure according to any one of claims 1 to 6 , wherein the thickness between the front and back surfaces of the nonwoven fabric sheet is 2 mm or more. 10. An absorbent article comprising the nonwoven fabric structure according to claim 1 in a three- dimensional gather portion that contacts the skin of a wearer around the crotch area. 8. An absorbent article comprising the nonwoven fabric structure according to claim 1 in a waist gather portion that contacts the skin of a wearer's waist.

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