WO2023188404A1 - Nonwoven fabric and method for manufacturing said nonwoven fabric - Google Patents

Abstract

The purpose of the present disclosure is to provide a nonwoven fabric that has embossed parts evenly arranged therein and that has excellent strength and flexibility. A nonwoven fabric according to the present disclosure has the following configuration.　A nonwoven fabric (1) comprises an embossed region (3) including a plurality of embossed parts (5) arranged evenly in the planar direction, and is characterized in that the plurality of embossed parts (5) in the embossed region (3) satisfy formula (1): 0.94≤(SMAX-SMIN)/SAVE≤2.50, when SMAX represents the maximum value of areas of the plurality of embossed parts (5), SMIN represents the minimum value of the areas of the plurality of embossed parts (5), and SAVE represents the average value of the areas of the plurality of embossed parts (5).

Description

Nonwoven fabric and method for manufacturing the nonwoven fabric

The present disclosure relates to a nonwoven fabric and a method for manufacturing the nonwoven fabric.

BACKGROUND ART Nonwoven fabrics, such as spunbond nonwoven fabrics, formed by forming a plurality of embossed portions on a web are used as exterior sheets, liquid permeable sheets, etc. of absorbent articles.
Spunbond nonwoven fabric is a nonwoven fabric that has excellent productivity, strength, air permeability, and the like. On the other hand, since it is necessary to arrange a plurality of embossed portions at a narrow pitch from the viewpoint of ensuring strength, spunbond nonwoven fabrics tend to be thin and have poor flexibility.

In order to solve this problem, for example, Patent Document 1 discloses a non-woven fabric having a plurality of embossed portions embossed over the entire surface, in which four embossed portions adjacent to an arbitrary embossed portion are non-embossed. The shortest distance from the boundary with the non-embossed part to the boundary of the arbitrary embossed part with the non-embossed part is 1.8 mm or more and less than 4.5 mm, and the crimped part due to the embossment accounts for the total area of the nonwoven fabric. Disclosed is the nonwoven fabric (claim 1) in which the area ratio of is 8% or more and less than 14%.

JP2019-157306A

The nonwoven fabric according to Patent Document 1 attempts to improve the flexibility of the nonwoven fabric by setting the distance of the embossed portion and the area ratio of the compressed portion to a specific range. However, the nonwoven fabric according to Patent Document 1 has embossed portions having a uniform shape arranged regularly (for example, arranged in a staggered manner), and due to the shape and arrangement of such embossed portions, the nonwoven fabric was less flexible.
Therefore, an object of the present disclosure is to provide a nonwoven fabric in which embossed portions are regularly arranged, and which has excellent strength and flexibility.

The present disclosure discloses a nonwoven fabric having an embossed region including a plurality of embossed portions regularly arranged in a plane direction, where the maximum value of the area of each of the plurality of embossed portions is S _MAX , and the above-mentioned When the minimum value of the individual areas of the plurality of embossed parts is S _MIN and the average value of the individual areas of the plurality of embossed parts is S _AVE , the number of the plurality of embossed parts in the embossed area is determined by the following formula. We have found a nonwoven fabric that satisfies (1): 0.94≦(S _MAX - S _MIN )/S _AVE ≦2.50.

The nonwoven fabric according to the present disclosure has embossed portions arranged regularly and has excellent strength and flexibility.

FIG. 1 is a diagram for explaining a spunbond nonwoven fabric 1 according to a first embodiment. FIG. 2 is a diagram for explaining the method for manufacturing the spunbond nonwoven fabric 1. FIG. 3 is a diagram for explaining a method for manufacturing the spunbond nonwoven fabric 1. FIG. 4 is a diagram for explaining a method of manufacturing the spunbond nonwoven fabric 1. FIG. 5 is a diagram for explaining a method for manufacturing the spunbond nonwoven fabric 1. FIG. 6 is a diagram for explaining the embossing roll. FIG. 7 is a diagram for explaining the wire mesh 101 used in Manufacturing Example 5. FIG. 8 is an image for explaining the example. FIG. 9 is a graph for explaining the example. FIG. 10 is a graph for explaining the example. FIG. 11 is a graph for explaining the example.

Specifically, the present disclosure relates to the following aspects.
[Aspect 1]
A nonwoven fabric comprising an embossed area including a plurality of embossed parts regularly arranged in a plane direction,
The maximum value of the individual areas of the plurality of embossed parts is S _MAX , the minimum value of the individual areas of the plurality of embossed parts is S _MIN , and the average value of the individual areas of the plurality of embossed parts is S _AVE . In this case, the plurality of embossed portions in the embossed area satisfy the following formula (1):
0.94≦(S _MAX - S _MIN )/S _AVE ≦2.50 Formula (1)
satisfy,
The above-mentioned nonwoven fabric is characterized by the following.

In the nonwoven fabric, the plurality of embossed portions in the embossed region satisfy formula (1).
In formula (1), in the embossed part having an area of S _MIN and close to it (hereinafter sometimes referred to as "embossed part near S _MIN "), the embossed part and its peripheral part (hereinafter referred to as "embossed part peripheral part") The fibers constituting the nonwoven fabric (sometimes referred to as '') are relatively weakly bonded to the embossed portion, and the peripheral portion of the embossed portion is soft and tends to be easily deformed. In addition, in the embossed part having an area of S _MAX or close to it, the fibers constituting the nonwoven fabric at the periphery of the embossed part are relatively strongly bonded to the embossed part, and the strength of the periphery of the embossed part tends to be high. .

When (S _MAX - S _MIN )/S _AVE satisfies the formula (1), the nonwoven fabric has excellent strength and flexibility.
Note that when (S _MAX - S _MIN )/S _AVE is less than 0.94, the difference between the soft and easily deformable parts of the nonwoven fabric and the strong parts becomes small, and the nonwoven fabric tends to be less flexible. . Furthermore, if (S _MAX - S _MIN )/S _AVE exceeds 2.50, the difference between the soft and easily deformed part of the nonwoven fabric and the strong part becomes too large, and the embossed part of the embossed part near S _MIN becomes too large. The strength of the nonwoven fabric decreases in the peripheral portion, and the nonwoven fabric tends to have poor strength as a whole.
As described above, since the plurality of embossed portions in the embossed region satisfy formula (1), the nonwoven fabric has excellent strength and flexibility in the embossed region.

[Aspect 2]
The nonwoven fabric according to aspect 1, wherein the nonwoven fabric is used for an exterior sheet or a liquid permeable sheet of an absorbent article.

Since the above-mentioned nonwoven fabric is used for the exterior sheet or liquid-permeable sheet of absorbent articles, when used in absorbent articles, it can impart a certain level of strength to the absorbent article, and the user can feel the softness. I can remember what it is like.

[Aspect 3]
When the coefficient of variation of the area of each of the plurality of embossed portions is CV, the plurality of embossed portions in the embossed area are expressed by the following formula (2):
10≦CV≦70 Formula (2)
The nonwoven fabric according to aspect 1 or 2, which satisfies the following.

In the above-mentioned nonwoven fabric, since the plurality of embossed portions in the embossed region satisfy formula (2), the individual areas of the plurality of embossed portions have a certain variation, and the effect of Aspect 1 is further enhanced.

[Aspect 4]
The plurality of embossed parts in the embossed area are expressed by the following formula (3):
0.09≦S _MIN /S _AVE formula (3)
satisfy,
The nonwoven fabric according to any one of aspects 1 to 3.

In the nonwoven fabric, in the embossed region, the plurality of embossed portions in the embossed region satisfy formula (3).
By satisfying formula (3), the fibers constituting the nonwoven fabric will be bonded to the embossed part with a certain strength in the embossed part peripheral part of the embossed part near S _MIN , and the embossed part peripheral part will be soft. It tends to be easily deformed.

In addition, in formula (3), if S _MIN /S _AVE is less than 0.09, the fibers constituting the nonwoven fabric will be weakly bonded to the embossed part in the embossed part peripheral part of the embossed part near S _MIN . , tends to be inferior to nonwoven fabrics in strength.
As described above, since the plurality of embossed portions in the embossed region satisfy formula (3), the nonwoven fabric has excellent strength in the embossed region.

[Aspect 5]
If the number of the plurality of embossed parts is N, and the number of the embossed parts having an area of 80% or more and 120% or less of S _AVE is _N1 , then the number of the plurality of embossed parts in the embossed area is N1. The embossed part has the following formula (4):
0.26≦N ₁ /N≦0.90 Formula (4)
satisfy,
The nonwoven fabric according to any one of aspects 1 to 4.

In the nonwoven fabric, the plurality of embossed portions in the embossed region satisfy formula (3).
By satisfying formula (3), a plurality of embossed portions will have an area close to the average value (S _AVE ) within a certain range, and the nonwoven fabric will have good strength and flexibility in the embossed area. Excellent balance with.

[Aspect 6]
Aspect 1, wherein in the embossed area, the nonwoven fabric includes a high basis weight area having a basis weight higher than the average basis weight of the nonwoven fabric, and a low basis weight area having a basis weight lower than the average basis weight. 5. The nonwoven fabric according to any one of items 5 to 5.

Since the nonwoven fabric has a high basis weight area and a low basis weight area in the embossed area, the nonwoven fabric has excellent strength in the high basis weight area and flexibility in the low basis weight area in the embossed area. Excellent in

[Aspect 7]
When the average value of the individual areas of the plurality of embossed portions in the low basis weight region is defined as SL _AVE , the plurality of embossed portions in the embossed region are expressed by the following formula (5):
SL _AVE < S _AVE formula (5)
satisfy,
The nonwoven fabric according to aspect 6.

In the nonwoven fabric, the plurality of embossed portions in the embossed region satisfy formula (5).
By satisfying formula (5), the average value of the individual areas of the multiple embossed parts in the low basis weight region (SL _AVE ) is lower than the average value of the individual areas of the multiple embossed parts (S _AVE ). Become. As a result, the low basis weight region has (i) flexibility due to the low basis weight, and (ii) a certain strength of the fibers constituting the nonwoven fabric in the embossed portion peripheral portion of the plurality of embossed portions. The nonwoven fabric has excellent flexibility in the embossed area and the low basis weight area.

[Aspect 8]
When the average value of the individual areas of the plurality of embossed portions in the high basis weight region is defined as SH _AVE , the plurality of embossed portions in the embossed region are expressed by the following formula (6):
S _AVE < SH _AVE formula (6)
satisfy,
The nonwoven fabric according to aspect 6 or 7.

In the nonwoven fabric, the plurality of embossed portions in the embossed region satisfy formula (6).
By satisfying formula (6), the average value of the individual areas of the multiple embossed parts in the high basis weight region (SH _AVE ) exceeds the average value of the individual areas of the multiple embossed parts (S _AVE ). Therefore, the high basis weight region has (i) strength due to the high basis weight, and (ii) fibers constituting the nonwoven fabric are strongly bonded to the embossed portions in the embossed portion peripheral portions of the plurality of embossed portions. The nonwoven fabric has excellent strength in the embossed area and the high basis weight area.

[Aspect 9]
The nonwoven fabric according to any one of aspects 6 to 8, wherein the nonwoven fabric is composed of continuous fibers.
Since the nonwoven fabric is composed of continuous fibers, the high basis weight region and the low basis weight region are directly connected by the continuous fibers, and as a result, the nonwoven fabric has excellent strength.

[Aspect 10]
In the embossed region, the high basis weight region and the low basis weight region are each composed of a ridge portion projecting in one direction in the thickness direction of the nonwoven fabric and a groove portion recessed in the one direction,
The nonwoven fabric according to aspect 9, wherein the ridge further has a plurality of recesses recessed in one direction, and a base made of the continuous fiber is provided at the bottom of each of the plurality of recesses.

The above-mentioned nonwoven fabric has a plurality of concave portions depressed in the thickness direction in the ridges formed from the high basis weight region, so that the area in which the skin of the user comes into contact with the nonwoven fabric is less than that of a nonwoven fabric without concave portions. less than. Therefore, the nonwoven fabric can provide a smooth touch to the user.
When the nonwoven fabric is applied to an absorbent article, such as an outer sheet of a disposable diaper, the nonwoven fabric is arranged such that the surface provided with the plurality of ridges and the plurality of grooves faces the non-skin side. When the nonwoven fabric has the concave portion, the surface contact area is reduced by the amount of the concave portion, so that a smooth tactile sensation can be provided. Furthermore, since the nonwoven fabric has a complex cloth-like surface shape, it is possible to impart a cloth-like (woven fabric-like) texture to the disposable diaper.

Further, when the nonwoven fabric is applied to an outer sheet of an absorbent article, such as a disposable diaper, the nonwoven fabric is arranged such that the surface on which the plurality of ridges and the plurality of grooves are provided faces the skin side. When this occurs, the space formed between the liquid-impermeable sheet and the liquid-impermeable sheet further increases by the amount of the recess, making it difficult for moisture to be transmitted to clothing, sheets, etc.

For example, when the nonwoven fabric is applied to a liquid-permeable sheet of an absorbent article, the base absorbs excreted body fluids and suppresses the body fluids absorbed by the absorbent body from returning into the recesses. Cheap. Therefore, the above-mentioned nonwoven fabric is excellent in suppressing the feeling of wetness.

[Aspect 11]
The planar direction includes a first direction and a second direction intersecting the first direction,
In any one of aspects 1 to 10, the plurality of embossed portions are intermittently arranged at a first pitch in the first direction and intermittently arranged at a second pitch in the second direction. Nonwoven fabric as described.

The above-mentioned nonwoven fabric has a plurality of embossed portions arranged in a predetermined arrangement, so that the effect of Aspect 1 is high.

[Aspect 12]
The nonwoven fabric according to aspect 11, wherein the intersecting angle between the first direction and the second direction is 60 to 90°.

In the nonwoven fabric, since the intersection angle is within a predetermined range, the plurality of embossed portions tend to take a nearly rectangular lattice shape, and the nonwoven fabric tends to have a constant strength in any direction. On the other hand, in the nonwoven fabric, the plurality of embossed portions satisfy at least formula (1), so the nonwoven fabric has flexibility.
As described above, the nonwoven fabric has excellent strength in any direction and also has excellent flexibility.

[Aspect 13]
The nonwoven fabric according to aspect 11 or 12, wherein the first pitch and the second pitch are the same.

In the nonwoven fabric, since the first pitch and the second pitch are the same, the plurality of embossed portions easily take a grid shape close to a square, and the nonwoven fabric has a more constant strength in any direction. easy to have. On the other hand, in the nonwoven fabric, the plurality of embossed portions satisfy at least formula (1), so the nonwoven fabric has flexibility.
As described above, the nonwoven fabric has excellent strength in any direction and also has excellent flexibility.

[Aspect 14]
A method for producing a nonwoven fabric according to any one of aspects 6 to 10, comprising:
preparing a web comprising the high basis weight region and the low basis weight region;
forming the plurality of embossed portions on the web using a pair of embossing rolls including an embossing roll having a plurality of protrusions and an anvil roll to form the nonwoven fabric;
including;
Each of the plurality of projections has the same compression area,
The above method, characterized in that:

The above production method can produce the nonwoven fabric according to any one of aspects 6 to 10.
In addition, in the above manufacturing method, since each of the plurality of protrusions has the same pressing area, the pressure applied to the web from the plurality of protrusions tends to be uniform in the conveying direction and the transverse direction of the embossing roll. Therefore, a nonwoven fabric with excellent strength and flexibility can be formed with high precision.

The nonwoven fabric and the method for manufacturing the nonwoven fabric of the present disclosure will be described in detail below.
[Nonwoven fabric]
The nonwoven fabric according to the present disclosure includes an embossed region including a plurality of embossed portions regularly arranged in a plane direction.
The above-mentioned plane direction means the direction in which the above-mentioned nonwoven fabric spreads. Regular arrangement will be described later.

In the nonwoven fabric of the present disclosure, the maximum value of the individual areas of the plurality of embossed parts is set as S _MAX , the minimum value of the individual areas of the plurality of embossed parts is set as S _MIN , and the average value of the individual areas of the plurality of embossed parts is set as S MAX. S _AVE , the multiple embossed parts in the embossed area are expressed by the following formula (1):
0.94≦(S _MAX - S _MIN )/S _AVE ≦2.50 Formula (1)
satisfy.
As a result, the nonwoven fabric has excellent strength and flexibility.

(S _MAX −S _MIN )/S _AVE is preferably 0.94 or more, more preferably 0.96 or more, and still more preferably 0.97 or more. This makes it easier to maintain the difference between the soft and easily deformable portions of the nonwoven fabric and the strong portions.
(S _MAX −S _MIN )/S _AVE is preferably 2.20 or less, more preferably 2.00 or less, and even more preferably 1.80 or less. Thereby, the difference between the soft and deformable portion of the nonwoven fabric and the high strength portion can be kept within a certain range.

In addition, in this specification, the individual areas of the plurality of embossed parts, the maximum value of the individual areas of the plurality of embossed parts (S _MAX ), the minimum value of the individual areas of the plurality of embossed parts (S _MIN ), and the individual areas of the plurality of embossed parts The method for measuring the average value (S _AVE ) of the individual areas of the embossed portions (hereinafter sometimes referred to as “method for measuring the area of the embossed portions”) is as follows.
(1) A KEYENCE VHX-7000 (lens: E30) is prepared in a constant temperature and humidity room adjusted to a temperature of 20° C. and a humidity of 60% RH.
(2) Cut the nonwoven fabric into a size of 100 mm x 100 mm to prepare a sample, and leave the sample in the constant temperature and humidity room for 24 hours.
(3) Place the sample on the stage of VHX-7000.

(4) Images of a plurality of embossed areas are taken under the following conditions.
・Magnification: 30x ・Epi-illumination: Off (Ring illumination)
・Inclination angle: 0°
・Support plate: Glass support plate (5) Select "Measurement/Scale", "Plane measurement", "Area measurement" on the menu screen, and trace the part where multiple fibers are crushed using the "Free line" setting. , extract the shape of the embossed part.
(6) Measure the area of the extracted part of the embossed part using VHX-7000.
(7) Measure the area of 100 embossed parts in total and calculate S _MAX , S _MIN and S _AVE .

In the nonwoven fabric according to the present disclosure, when the coefficient of variation of the area of each of the plurality of embossed portions is CV, the plurality of embossed portions in the embossed region are expressed by the following formula (2):
10≦CV≦70 Formula (2)
It is preferable to satisfy the following.
As a result, the nonwoven fabric has excellent strength and flexibility.

CV is preferably 14 or more, more preferably 17 or more, and even more preferably 20 or more. Thereby, the CV is also preferably 60 or less, more preferably 55 or less, and still more preferably 50 or less. As a result, the nonwoven fabric has excellent strength and flexibility.
Note that CV is calculated by dividing the standard deviation of the individual areas of multiple embossed parts in the embossed area by the average value of the individual areas of multiple embossed parts (S _AVE ), and multiplying by 100 to convert it into a percentage. CV (%).

In the nonwoven fabric according to the present disclosure, the plurality of embossed portions in the embossed region are expressed by the following formula (3):
0.09≦S _MIN /S _AVE formula (3)
It is preferable to satisfy the following.
Thereby, the nonwoven fabric has excellent strength in the embossed area. Note that the strength of the nonwoven fabric decreases at the periphery of the embossed area near S _MIN , and the nonwoven fabric tends to have poor strength as a whole.

S _MIN /S _AVE is preferably 0.12 or more, more preferably 0.14 or more, and still more preferably 0.16 or more. Further, S _MIN /S _AVE is preferably 0.7 or less, more preferably 0.6 or less, and still more preferably 0.5 or less. Thereby, the nonwoven fabric has excellent strength in the embossed area.

In the nonwoven fabric according to the present disclosure, when the number of the plurality of embossed portions is N, and the number of the plurality of embossed portions having an area of 80% or more and 120% or less of S _AVE is _N1 , the embossed area The plurality of embossed parts in the following equation (4):
0.26≦N ₁ /N≦0.90 Formula (4)
It is preferable to satisfy the following.
Thereby, the nonwoven fabric has an excellent balance between strength and flexibility in the embossed area.

N ₁ /N is preferably 0.30 or more, more preferably 0.35 or more, and still more preferably 0.40 or more. Further, N ₁ /N is preferably 0.88 or less, more preferably 0.86 or less, and still more preferably 0.84 or less. Thereby, the nonwoven fabric has an excellent balance between strength and flexibility in the embossed area.
Note that N can be determined by measuring the number of embossed parts in the embossed area, and _N1 is the number of embossed parts having an area of 80% or more and 120% or less of S _AVE in the embossed area. It can be determined by measuring the

The nonwoven fabric according to the present disclosure preferably includes a high basis weight area having a basis weight higher than the average basis weight of the nonwoven fabric and a low basis weight area having a basis weight lower than the average basis weight in the embossed area. . As a result, the nonwoven fabric has excellent strength in the high basis weight region and excellent flexibility in the low basis weight region in the embossed region.
In addition, examples of the nonwoven fabric having the high basis weight region and the low basis weight region include those known in the art.

In the nonwoven fabric according to the present disclosure, when the average value of the individual areas of the plurality of embossed portions in the low basis weight region is SL _AVE , the plurality of embossed portions in the embossed region are expressed by the following formula (5):
SL _AVE < S _AVE formula (5)
It is preferable to satisfy the following.
Thereby, the nonwoven fabric has excellent flexibility in the embossed area and the low basis weight area.

Note that the magnitude of the average value of the individual areas of the plurality of embossed portions in the low basis weight region: SL _AVE and the average value of the individual areas of the plurality of embossed portions: S _AVE can be visually evaluated. In addition, the above-mentioned size is determined by measuring the average value (SL _AVE ) of the individual areas of a plurality of embossed parts in the low basis weight region using the above-mentioned "method for measuring the area of embossed parts". This can be determined by comparing it with the average value (S _AVE ) of each area.

In the nonwoven fabric according to the present disclosure, when the average value of the individual areas of the plurality of embossed portions in the high basis weight region is SH _AVE , the plurality of embossed portions in the embossed region are expressed by the following formula (6):
S _AVE < SH _AVE formula (6)
It is preferable to satisfy the following.
Thereby, the nonwoven fabric has excellent strength in the embossed area and the high basis weight area.

Note that the magnitude of the average value of the individual areas of the plurality of embossed portions in the high basis weight region: SH _AVE and the average value of the individual areas of the plurality of embossed portions: S _AVE can be visually evaluated. In addition, the above-mentioned size is determined by measuring the average value (SH _AVE ) of the individual areas of multiple embossed areas in the high basis weight area using the above-mentioned "method for measuring the area of embossed areas". This can be determined by comparing it with the average value (S _AVE ) of each area.

The nonwoven fabric according to the present disclosure is not particularly limited as long as it has a plurality of embossed parts, and examples thereof include spunbond nonwoven fabric, spunbond/meltblown/spunbond nonwoven fabric (SMS nonwoven fabric), point bonded nonwoven fabric, and the like.

The fibers constituting the nonwoven fabric according to the present disclosure include heat-fusible fibers. The heat-fusible fibers include polyolefin single fibers such as polyethylene, polypropylene, and polyvinyl alcohol, polyethylene terephthalate (core)/polyethylene (sheath), polyethylene terephthalate (core)/polypropylene (sheath), Examples include core-sheath type composite fibers containing an olefin resin such as polypropylene (core)/polyethylene (sheath). Furthermore, the heat-fusible fibers may be biodegradable fibers such as polylactic acid, polyglycol, polyhydroxybutyrate, polybutylene succinate, polybutylene succinate/adipate, polycaprolactone, and the like.

The composite fiber may be a hydrophobic fiber or may be one that has been subjected to a hydrophilic treatment using a hydrophilic oil agent or the like. The hydrophilic treatment can be carried out, for example, by kneading a hydrophilic agent into the resin constituting the fibers, or by applying the hydrophilic agent to the surface of the fibers. Further, the composite fiber may be a side-by-side type fiber containing an olefin resin as described above. These fibers may be used alone or in combination of two or more types.
Moreover, it is preferable that the said fiber is comprised from a continuous fiber. As a result, the nonwoven fabric has excellent strength.

When the nonwoven fabric according to the present disclosure includes a high basis weight area and a low basis weight area in the embossed area, the high basis weight area and the low basis weight area each protrude in one direction in the thickness direction of the nonwoven fabric. The ridge further has a plurality of recesses recessed in one direction, and the bottom of each of the plurality of recesses is provided with a base made of continuous fibers. It is preferable. As a result, it is possible to give the user a smooth touch, excellent in suppressing the feeling of wetness, and impart a cloth-like texture, making it difficult for moisture to be transmitted to clothing, sheets, etc.

In the nonwoven fabric according to the present disclosure, "regularly arranged in the plane direction" with respect to the plurality of embossed parts means that the plane direction has a first direction, and the plurality of embossed parts are arranged at least in the first direction. It means that they are arranged regularly.

Further, in the nonwoven fabric according to the present disclosure, the planar direction includes the first direction and the second direction intersecting the first direction, and the plurality of embossed portions are arranged regularly in the first direction and the second direction. It is preferable that they are arranged intermittently at a first pitch in the first direction, and more preferably intermittently at a second pitch in the second direction. As a result, the nonwoven fabric tends to have excellent strength.
In addition, the first direction means the direction in which the distance between the embossed parts is the shortest in a plurality of embossed parts, and the second direction is the direction in which the distance between the embossed parts is the shortest in a direction different from the first direction. means.

In the nonwoven fabric according to the present disclosure, when the plurality of embossed portions are regularly arranged in the first direction and the second direction, the intersection angle formed by the first direction and the second direction is The angle is greater than 0° and less than 90°. The crossing angle is preferably 30° or more, more preferably 45° or more, even more preferably 60° or more, and even more preferably 75° or more. Thereby, the nonwoven fabric tends to have a constant strength in any direction.

In the nonwoven fabric according to the present disclosure, when the plurality of embossed portions are intermittently arranged at a first pitch in the first direction and intermittently arranged at a second pitch in the second direction, The first pitch and the second pitch may be the same or different. Since the first pitch and the second pitch are the same, the plurality of embossed portions can easily take a grid shape close to a square, and the nonwoven fabric can easily have a constant strength in any direction.

The external shape, various dimensions, average basis weight, etc. of the nonwoven fabric according to the present disclosure vary depending on the use of the nonwoven fabric, but for example, when the nonwoven fabric is used for an absorbent article, the average basis weight of the nonwoven fabric is, for example, It is 8 to 80 g/m ² .

In this specification, the average basis weight: BW (g/m ² ) of a nonwoven fabric is measured by the following method.
(1) Five samples of a predetermined size (example: 100 mm x 100 mm) are cut out from the nonwoven fabric.
(2) The mass of the five cut out samples is measured using a direct reading balance (eg, electronic balance HF-300 manufactured by Kensei Kogyo Co., Ltd.).
(3) The mass per unit area of the nonwoven fabric is calculated from the average value of the masses of the five samples, and the average basis weight of the nonwoven fabric is defined as BW (g/m ² ).

The average thickness of the nonwoven fabric varies depending on the use of the nonwoven fabric, but for example, when the nonwoven fabric is used for an absorbent article, the average thickness of the nonwoven fabric is, for example, 0.1 mm to 3 mm.
The average thickness of ^the nonwoven fabric was measured under standard conditions (temperature 23 ±2°C, relative humidity 50±5%), pressurizes five different parts of the nonwoven fabric, and measures the thickness of each part after 10 seconds of pressure.It refers to the average value of five measured values.

The nonwoven fabric according to the present disclosure has an initial thickness: T ₀ (mm) and a compressed thickness: T _m ( Compressive properties per unit basis weight ^: _{(T 0 - T m} )/BW [mm/(g/m ² )] is preferably 0.010 or more, more preferably 0.011 or more, and still more preferably 0.012 or more. Further, the compression property per unit basis weight: (T ₀ - T _m )/BW [mm/(g/m ² )] is preferably 0.030 or less, more preferably 0.025 or less, More preferably, it is 0.020 or less. As a result, when a user touches the nonwoven fabric, the nonwoven fabric easily deforms in the thickness direction and has excellent flexibility.

The measurement conditions for the initial thickness: T ₀ (mm) and the compressed thickness: T _m (mm) using the automated compression tester KES-FB3-A manufactured by Kato Tech Co., Ltd. are as follows. be.
SENS:2
Speed: 0.02mm/sec Stroke: 5mm/10V
Pressure area: 2cm ²
Capture interval: 0.1 seconds Upper limit load: 50g/cm ₂
Number of repetitions: 1 time

In addition, the initial thickness: T ₀ (mm) represents the thickness of the nonwoven fabric when pressurized with a pressure of 0.05 kPa (0.5 gf/cm ² ), and the compressed thickness: T _m (mm) , represents the thickness of the nonwoven fabric when pressurized with a pressure of 4.9 kPa (50 gf/cm ² ).

The nonwoven fabric according to the present disclosure has a bending stiffness value: B (10 ⁻⁴ mN×m ² /m) measured using a pure bending tester KES-FB2-A manufactured by Kato Tech Co., Ltd., which is the average of the nonwoven fabric. Bending rigidity per unit basis weight and unit thickness, which is the value divided by basis weight: BW and initial thickness of nonwoven fabric: T ₀ (mm): B/BW/T ₀ [(10 ^-4 mN m ² /m)/(g/m ² )/mm] is preferably 0.5 or more, more preferably 1.0 or more, and even more preferably 1.2 or more. Further, the bending rigidity per unit basis weight and unit thickness: B/BW/T ₀ [(10 ⁻⁴ mN×m ² /m)/(g/m ² )/mm] is preferably less than 2.7. , more preferably 2.5 or less, and even more preferably 2.3 or less. As a result, the nonwoven fabric easily deforms when force is applied, and has excellent flexibility.

The conditions for measuring the bending rigidity value: B (10 ⁻⁴ mN×m ² /m) using a pure bending tester KES-FB2-A manufactured by Kato Tech Co., Ltd. are as follows.
SENS:20
Maximum curvature: ±2.5
Sample width: 100mm
Number of repetitions: 1 time

Note that the bending stiffness value: B is calculated at a curvature of 0.5 to 1.5.
Further, the bending direction is such that the sample is bent in the MD direction so that the crease is parallel to the CD direction of the sample.
For the bending stiffness value: B, the average value of n=5 is adopted.

Bending rigidity value: B means that the smaller the value, the easier it is to bend and deform. For example, when a nonwoven fabric with a low bending rigidity value B is used as an exterior sheet for an absorbent article, the nonwoven fabric easily deforms when the surface is touched, and the nonwoven fabric follows the movement of the fingertips, making it feel soft. .

In addition, the bending rigidity value: B is divided by the average basis weight of the nonwoven fabric: BW and the initial thickness of the nonwoven fabric: T ₀ (mm) to obtain the bending rigidity per unit basis weight and unit thickness: B/BW. /T ₀ [(10 ^-4 mN×m ² /m)/(g/m ² )/mm] The reason for the evaluation is that the bending stiffness value: B tends to increase as the average basis weight of the nonwoven fabric increases. This is because the thickness tends to increase as the thickness of the nonwoven fabric increases.

The nonwoven fabric according to the present disclosure has a breaking strength per unit basis weight: BR/ which is calculated by dividing the breaking strength: BR (N/50 mm) by the average basis weight of the nonwoven fabric: BW (g/m ² ). BW [(N/50 mm)/(g/m ² )] is preferably 0.70 or more, more preferably 0.75 or more, and even more preferably 0.80 or more. Moreover, the breaking strength per unit basis weight: BR/BW [(N/50mm)/(g/m ² )] is preferably 2.00 or less, more preferably 1.70 or less, and further Preferably it is 1.50 or less. Thereby, the nonwoven fabric has excellent strength.

Breaking strength: BR is measured as follows.
(1) Prepare Autograph AG-1 manufactured by Shimadzu Corporation.
(2) Prepare five samples each having a length of 150 mm in the transverse direction CD at the time of manufacture and a length of 50 mm in the transport direction MD at the time of manufacture.
(3) Measure the breaking strength in the transverse direction CD at a distance between chucks of 100 mm and a tensile speed of 100 mm/min.

(4) The average value of the breaking strengths of the five samples is adopted as breaking strength: BR (N/50 mm). Note that "N/50 mm" means the breaking strength (N) per width of 50 mm, and the breaking strength means the strength at the maximum point load.

The nonwoven fabric according to the present disclosure is not particularly limited and can be used for various purposes, such as absorbent articles such as disposable diapers, urine absorbing pads, animal urine sheets, sanitary napkins, panty liners, etc. can be used.
Moreover, the nonwoven fabric according to the present disclosure can be used for an exterior sheet of an absorbent article and a liquid permeable sheet.

FIG. 1 is a diagram for explaining a spunbond nonwoven fabric 1 according to one embodiment of the present disclosure (hereinafter referred to as "first embodiment"). The spunbond nonwoven fabric 1 according to the first embodiment _has a planar direction PD including a first direction D ₁ and a second direction D ₂ orthogonal to the first direction D 1 .
The spunbond nonwoven fabric 1 includes a plurality of high basis weight regions 11 extending in a predetermined direction D, a plurality of low basis weight regions 13 extending in a predetermined direction D, and a plurality of high basis weight regions 13. 11 and the plurality of low basis weight regions 13 are alternately arranged in a direction orthogonal to a predetermined direction D.

The spunbond nonwoven fabric 1 includes an embossed area 3 that includes a plurality of embossed portions 5 . The plurality of embossed portions 5 are intermittently arranged at a first pitch P ₁ in the first direction D ₁ and intermittently arranged at a second pitch P ₂ in the second direction D ₂ .

The plurality of embossed portions 5 are divided into a plurality of first embossed portions 7 arranged in the plurality of high basis weight regions 11 and a plurality of second embossed portions 9 arranged in the plurality of low basis weight regions 13. The area of each of the plurality of first embossed portions 7 tends to be larger than the area of each of the plurality of second embossed portions 9.

A plurality of first embossed portions 7 having a large area of the embossed portion and a large amount of fibers to be joined, and a plurality of second embossed portions 9 having a small area of the embossed portion and a small amount of fibers to be joined are arranged in a predetermined direction. By arranging the embossed portions alternately in the direction orthogonal to D, the embossed portions have a small area and easily deformable regions are arranged at regular intervals, resulting in a nonwoven fabric that is easy to deform and has excellent flexibility.

Furthermore, since the area of the embossed parts is large and the high-strength parts are arranged at regular intervals, when used as an exterior sheet for absorbent articles, it is possible to obtain a highly durable nonwoven fabric that is resistant to tearing when worn. Furthermore, because the area of the embossed part is large and the areas with a large amount of fiber are arranged continuously in a certain direction, it is difficult to cut into the width during the manufacture of absorbent articles, making it possible to create a nonwoven fabric with excellent manufacturing stability and strength. Obtainable.

The spunbond nonwoven fabric 1 can be applied to an absorbent article, for example, an outer sheet of a disposable diaper.
In the spunbond nonwoven fabric 1, the structure of the web 51 that constitutes the spunbond nonwoven fabric 1 remains in portions spaced apart from each of the plurality of embossed portions 5. When the structure of the web 51 remains in the spunbond nonwoven fabric 1, the following effects can be obtained.

In a portion spaced apart from each of the plurality of embossed portions 5, each of the plurality of high basis weight regions 11 has a ridge portion 53 (see FIG. 2), and each of the plurality of low basis weight regions 13 has a ridge portion 53 (see FIG. 2). The ridge portion (see FIG. 2) having the groove portion 55 (see FIG. 2) and formed by the plurality of high basis weight regions 11 has a plurality of recesses 57 (see FIG. 2). ing.
In the description of the spunbond nonwoven fabric 1, some of the reference numerals are those of the web 51 shown in FIG. 2. Further, the predetermined direction D in the spunbond nonwoven fabric 1 is parallel to the first direction x in FIG. 2 .

Since the ridges 53 of the plurality of high basis weight regions 11 have a larger basis weight than the grooves 55 of the plurality of low basis weight regions 13, when a load is applied in the thickness direction z (see FIG. 2), The thickness of the ridge portion 53 is difficult to change. In this case, the length of the ridge portion 53 in the second direction y (see FIG. 2) is also difficult to change, so the length of the groove portion 55 in the second direction y is difficult to change.

Therefore, when the spunbond nonwoven fabric 1 is used as an exterior sheet so that the surface provided with the plurality of ridges 53 and the plurality of grooves 55 is the non-skin side (outer surface side), when worn, the Even when subjected to a load, the plurality of ridges 53 are resistant to collapse and have the recesses 57, so the contact area of the surface of the spunbond nonwoven fabric 1 can be reduced, giving the user a dry and dry feeling. It can give a tactile sensation. Moreover, since the spunbond nonwoven fabric 1 has a cloth-like complex surface shape, it is possible to impart a cloth-like (woven fabric-like) texture to the disposable diaper.
Further, in this case, in the disposable diaper, the patterns provided on the indicator, the liquid-impermeable sheet, etc. can be clearly seen from the exterior sheet side through the plurality of grooves 55.

Furthermore, when the spunbond nonwoven fabric 1 is used as an exterior sheet so that the surface on which the plurality of ridges 53 and the plurality of grooves 55 are provided faces the skin side (inner surface side), the plurality of ridges 53 Since it is hard to collapse, spaces derived from the plurality of grooves 55 and recesses 57 are formed between the absorbent article and the liquid-impermeable sheet, making it difficult to transmit moisture contained in the absorbent article to clothing, sheets, etc.
Further, in this case, in the disposable diaper, the patterns provided on the indicator, the liquid-impermeable sheet, etc. can be clearly seen from the exterior sheet side through the plurality of grooves 55.

The spunbond nonwoven fabric 1 can be applied to absorbent articles, for example, liquid permeable sheets for disposable diapers.
In the spunbond nonwoven fabric 1, the structure of the web 51 that constitutes the spunbond nonwoven fabric 1 remains in portions spaced apart from each of the plurality of embossed portions 5. When the structure of the web 51 remains in the spunbond nonwoven fabric 1, the following effects can be obtained.

The spunbond nonwoven fabric 1 (liquid permeable sheet) has a plurality of ridges 53 and a plurality of grooves 55 alternately provided in the second direction y, so that in a wide range in the first direction x and the second direction y, It maintains the distance between the absorbent body and the user's skin and is excellent in suppressing the feeling of wetness, and also has excellent visibility of bodily fluids absorbed into the absorbent body through the plurality of grooves 55.

The spunbond nonwoven fabric 1 (liquid permeable sheet) has a plurality of grooves 55 and a plurality of recesses 57 (see FIG. 2) recessed in the thickness direction z in the plurality of ridges 53. The area that the skin touches the wet spunbond nonwoven fabric 1 is smaller than that of the spunbond nonwoven fabric 1 that does not have the recesses 57. In the spunbond nonwoven fabric 1 (liquid permeable sheet), the base 59 (see FIG. 2) absorbs excreted body fluids and more reliably suppresses the body fluids absorbed by the absorbent body from returning into the recesses 57. do.

In the spunbond nonwoven fabric 1 (liquid permeable sheet), each of the plurality of ridges 53 has continuous fibers arranged in one direction in the second direction y of at least some of the plurality of recesses 57 (see FIG. 2). ) (see FIG. 2). The bundled portion 61 has a small inter-fiber distance between continuous fibers, and is not easily deformed when subjected to a load. Therefore, the spunbond nonwoven fabric 1 (liquid permeable sheet) having the bundled portion 61 easily maintains the shape of the concave portion with little change in thickness when worn. As a result, the spunbond nonwoven fabric 1 (liquid permeable sheet) can easily maintain the distance between the absorbent body and the user's skin, and can also easily maintain the shape of the recess 57. (Liquid-permeable sheet) It is easy to maintain a state in which the area that comes in contact with the sheet is small.

In the spunbond nonwoven fabric 1, the thickness of each of the plurality of grooves 55 is thinner than the thickness of the base 59, so the plurality of grooves 55 have excellent visibility in the thickness direction z, and have almost no visibility in the thickness direction z. The difference from the plurality of ridges 53 that are not obtained is conspicuous. Therefore, the spunbond nonwoven fabric 1 (liquid permeable sheet) has excellent visibility.

In the spunbond nonwoven fabric 1 (liquid permeable sheet), each of the plurality of ridges 53 of the spunbond nonwoven fabric 1 protrudes toward each of the plurality of adjacent grooves 55, and is arranged at intervals along the first direction x. Since it has a plurality of protrusions 63 (see FIG. 2), the plurality of ridges 53 are unlikely to fall down when a load is applied in the thickness direction z. Therefore, in the liquid-permeable sheet, the plurality of ridges 53 can easily maintain their shape, and the plurality of ridges 53 are less likely to block the grooves 55, resulting in excellent visibility.

In the spunbond nonwoven fabric 1 (liquid permeable sheet), the fiber orientation along the first direction x of the plurality of ridges 53 of the spunbond nonwoven fabric 1 is the same as the fiber orientation along the first direction x of the plurality of grooves 55. , so the distance between the intersections of continuous fibers is short. Therefore, in the spunbond nonwoven fabric 1, the shape of the plurality of ridges 53 is easily maintained. Further, body fluid can be diffused in the first direction x along the plurality of ridges 53. Therefore, the liquid-permeable sheet suppresses the bodily fluid from staying in one place by diffusing the bodily fluid in the first direction Lx, and is therefore excellent in suppressing the feeling of wetness. In addition, the liquid permeable sheet has a higher fiber orientation along the first direction x of the plurality of ridges 53, so that the distance between the intersections of continuous fibers is short, and the distance between the plurality of joints is short. Therefore, the shape is easily maintained. Therefore, the liquid permeable sheet is difficult to deform in the thickness direction z.

When forming the web 51 of the spunbond nonwoven fabric 1, the continuous fibers move due to the airflow, but because the fiber length is long, they move over a certain length and also move along with the adjacent continuous fibers. , susceptible to airflow during the deposition process. Therefore, as each of the continuous fibers moves, a portion where the distance between fibers is small is likely to be formed. Continuous fibers have short distances between mutual intersection points and short distances between multiple joints. Therefore, in the spunbond nonwoven fabric 1 (liquid permeable sheet), the shape of the plurality of ridges 53 is easily maintained.

When the spunbond nonwoven fabric 1 is worn, when a load is applied in the thickness direction z, the plurality of ridges 53 do not easily collapse, and the length of the plurality of grooves 55 in the second direction y is small when the basis weight is small. maintained.

[Method for manufacturing nonwoven fabric]
A method for manufacturing a nonwoven fabric according to the present disclosure has the following configuration.
- Step of preparing a web having a high basis weight region and a low basis weight region (hereinafter sometimes referred to as "web preparation step")
A step of forming the nonwoven fabric by forming a plurality of embossing parts on the web using a pair of embossing rolls including an embossing roll having a plurality of protrusions and an anvil roll (hereinafter referred to as "nonwoven fabric"). (sometimes referred to as "formation step")
Hereinafter, description will be given along with specific embodiments.

The spunbond nonwoven fabric 1 according to the first embodiment can be manufactured as follows.
[Web preparation steps]
The resin composition is spun out from a spinning nozzle, the spun filaments are cooled with cooling fluid, etc., and tension is applied to the filaments with drawing air to form continuous fibers having a predetermined fineness. The obtained continuous fibers are deposited on the wire mesh 101 while being sucked from below the wire mesh 101 moving in the transport direction MD, thereby forming the web 51.

A perspective view of the formed web 51 is shown in FIG. 2, and a cross section in the y direction of FIG. 2 is shown in FIG. Further, a perspective view schematically showing the wire mesh 101 is shown in FIG. 4, and an end view of the wire mesh 101 in the transverse direction CD is shown in FIG.

As shown in FIG. 2, the web 51 has a first direction x, a second direction y, and a thickness direction z that are orthogonal to each other, and is composed of continuous fibers. This makes it difficult for the ends of continuous fibers to exist on the surface of the web 51 and, ultimately, the spunbond nonwoven fabric 1, resulting in excellent wearing comfort.

The web 51 includes a plurality of ridges 53 and a plurality of grooves 55. The plurality of ridges 53 and the plurality of grooves 55 are provided on one surface of the web 51 in the thickness direction z, which is the upper surface in the case of FIG. 2 . The plurality of ridges 53 protrude from one surface of the web 51 in the thickness direction z and extend along the first direction x. The plurality of grooves 55 extend along the first direction x, and have a lower basis weight than the plurality of ridges 53. Each of the plurality of ridges 53 and each of the plurality of grooves 55 are provided alternately in the second direction y. The plurality of ridges 53 are arranged at predetermined intervals in the second direction y.

Each of the plurality of ridges 53 has a larger amount of continuous fibers than each of the plurality of grooves 55, and is thicker than each of the plurality of grooves 55. That is, the thickness of each of the plurality of grooves 55 is thinner than the thickness of each of the plurality of ridges 53. The plurality of ridges 53 and the plurality of grooves 55 are connected by a gentle surface. As shown in FIG. 3, the plurality of ridges 53 and the plurality of grooves 55 have a boundary at a thickness T50 of 50% of the thickness Tn of the web 51 in an unloaded state, and have a boundary of 50 _% of the thickness Tn. The region having a thickness of Tn or more is defined as a ridge portion 53, and the region having a thickness of less than 50% of the thickness Tn is defined as a groove portion 55.

It is preferable that the fiber orientation of the plurality of ridges 53 along the first direction x is higher than the fiber orientation of the plurality of grooves 55 along the first direction x. Due to the higher fiber orientation along the first direction x of the plurality of ridges 53, the distance between the intersections of continuous fibers is short, and the distance between the plurality of joints is short, so that the web 51 and, by extension, the spunbond The shape of the nonwoven fabric 1 is easily maintained. Fiber orientation is a concept consisting of fiber orientation angle and orientation strength, and can be measured, for example, by the following method.

The web 51 or the nonwoven fabric 1 is left still so that the surface on which the plurality of ridges 53 and the plurality of grooves 55 are formed is located on the upper side. Using a microscope (for example, a scanning electron microscope such as JCM-5100 manufactured by JEOL Ltd.), an enlarged image is taken in a direction perpendicular to the measurement surface of the web 51 or nonwoven fabric 1 and printed. , trace the fibers onto a transparent PET sheet. The enlarged image is an image enlarged to a magnification that allows measurement of 10 or more fibers, and the enlargement magnification is, for example, 50 to 300 times. The image is imported into a personal computer and binarized using nexus NewQube (stand-alone version) image processing software manufactured by Nexus Corporation. Using Fiber Orientation Analysis 8.13 Single, which is a fiber orientation analysis program, the orientation angle and orientation intensity are obtained from the binarized image. The orientation angle is the angle at which the fibers are most oriented, and the orientation strength is the strength at that orientation angle. Repeat the measurement several times (for example, 3 to 5 times) and calculate the average value.

Each of the plurality of ridges 53 has a plurality of recesses 57. The recesses 57 have an elongated shape in which the length in the first direction x is longer than the length in the second direction y, and a plurality of recesses 57 are arranged at intervals in the first direction x. Each of the plurality of recesses 57 is recessed in the thickness direction z, and has a base 59 at the bottom thereof. The base portion 59 is made of continuous fibers. The base portion 59 has a smaller amount of continuous fibers than the portions of the plurality of ridges 53 excluding the base portion 59. The thickness Tb of the base portion 59 is thicker than the thickness Tc of each of the plurality of groove portions 55 . That is, the thickness Tc of each of the plurality of groove portions 55 is thinner than the thickness Tb of the base portion 59.

The plurality of ridges 53 have a bundle portion 61 on one side of at least a portion of the recess 57 in the second direction y. The bundle portion 61 has a plurality of continuous fibers in a state where the plurality of continuous fibers are oriented in the first direction x. In the bundled portion 61, the inter-fiber distance between the continuous fibers is smaller than when the continuous fibers are not oriented in a specific direction. That is, in the bundled portion 61, since the continuous fibers between the bonded portions are oriented in the first direction x, the distance between the continuous fibers between the bonded portions is smaller. Therefore, in the web 51 and, by extension, in the spunbond nonwoven fabric 1, when a load is applied in the thickness direction z, the bundled portion 61 is unlikely to deform in the thickness direction z because there is a high probability that the continuous fibers will come into line contact with each other. . The bundle portion 61 may be formed on both sides of the recess 57 in the second direction y.

On the other hand, in the case of continuous fibers that are not oriented in a specific direction, the continuous fibers between the joints are oriented in an unspecified direction, so when a load is applied in the thickness direction z, the fibers There is a high probability of point contact, and the fibers in the non-contact range are likely to deform.

The thickness of the web 51 and the spunbond nonwoven fabric 1 under no load, the thickness of the plurality of grooves 55, and the thickness of the base 59 are measured using a two-dimensional laser displacement meter. Examples of the two-dimensional laser displacement meter include the high-precision two-dimensional laser displacement meter LJ-G series (model: LJ-G030) manufactured by Keyence Corporation. The web 51 is placed on a horizontal measuring stand, and the displacement from the measuring stand is measured for five different target parts of the web 51 using a laser displacement meter, and the average value of the five measured values is calculated for each of the web 51. The thickness of the target location (mm).

Each of the plurality of ridges 53 may have a plurality of protrusions 63 that protrude toward each of the plurality of adjacent grooves 55. Each of the plurality of protrusions 63 protrudes in the second direction y, and is lined up at intervals along the first direction x. The spaces between the protrusions 63 of the plurality of ridges 53 are depressed in the second direction y. The plurality of protrusions 63 are provided on both sides of the plurality of ridges 53, and each of the protrusions 63 may be provided at a position overlapping in the second direction y. When the respective protrusions 63 are provided at positions overlapping in the second direction y, the plurality of ridges 53 and the plurality of grooves 55 each have a wide portion and a narrow portion. Furthermore, the respective protrusions 63 may be provided at positions that do not overlap in the second direction y. When the respective protrusions 63 are provided at positions that do not overlap in the second direction y, the plurality of ridges 53 and the plurality of grooves 55 each have a substantially constant width.

The thickness Tc of each of the plurality of grooves 55 has a small amount of continuous fibers, and is therefore thinner than the thickness Tb of the base 59, so there is little overlap between the continuous fibers in the thickness direction z. That is, in the plurality of grooves 55, the intervals between the continuous fibers are larger. Therefore, the web 51 can be seen from one side to the other side in the thickness direction z through the intervals between the continuous fibers in the plurality of grooves 55, that is, the visibility is excellent.

The visibility may be evaluated by the average transmittance obtained by the method shown below. First, five samples of 100 mm x 100 mm are prepared. Place the sample on black paper with the textured side facing up. The entire sample is photographed using a 12 million pixel digital camera from a position approximately 15 cm away from the sample so that the entire sample can be photographed. The obtained image is taken into VHX-7000 manufactured by KEYENCE, automatic area measurement is performed, the extraction method is set to brightness (standard), and the image is processed with the following settings to calculate the transmittance. Then, the average value of the transmittances of the five samples is taken as the average transmittance of the nonwoven fabric.

Measurement area 50mm x 50mm
Filter settings Texture removal 10
Brightness unevenness removal 1
Extraction settings Brightness settings 0-148
Fill in the blanks OFF
Small particle removal OFF
Shaping settings Fill in the blanks Auto

As shown in FIG. 4, the wire mesh 101 for forming the web 51 has a conveying direction MD, a transverse direction CD, and a height direction H that are perpendicular to each other, and is made up of a plurality of wires 103 arranged in a net shape. A main body 105 is provided. Each of the plurality of wires 103 has a predetermined outer diameter. In the mesh main body 105, a plurality of wires 103 are arranged as vertical lines and horizontal lines, and are crossed one by one at a constant interval.

The wire mesh 101 has a plurality of protrusions 107 that protrude from one surface of the mesh main body 105 in the height direction H and extend along the conveyance direction MD. The protrusions 107 are arranged at predetermined intervals in the transverse direction CD. The protrusions 107 partially close the gaps formed between the wires 103 in the mesh main body 105. Note that the plurality of protrusions 107 extending along the conveyance direction MD may be collectively referred to as the protrusions 107 arranged in a stripe shape.

As shown in FIG. 5, the height H _L of the protrusion 107 may be 1.0 mm or more. It is preferable that the height H _L of the protrusion 107 is larger than the outer diameter of the wire 103, that is, the outer diameter of the wire 103 is smaller than the height H _L of the protrusion 107. The width W _L of each of the plurality of protrusions 107, that is, the total length of the length in the transverse direction CD may be 50% or less of the length of the mesh main body 105 in the transverse direction CD. The width W _L of each protrusion 107 is not limited to being constant, and may be partially different. The width W _L of each protrusion 107 may be an average value of values measured at a plurality of locations (eg, 5 locations) at a predetermined interval (eg, 100 mm) in the transport direction MD. The width W _L of the protrusion 107 is the length in the transverse direction CD of the portion in contact with the mesh main body 105 .

When the wire mesh 101 is used, continuous fibers are deposited on the wire mesh 101 by suction from the underside of the wire mesh 101. Some of the continuous fibers preferentially gather between the protrusions 107 of the mesh main body 105 where the protrusions 107 are not formed. A portion of the continuous fibers gather preferentially between the protrusions 107, so that the continuous fibers become dense and a plurality of ridges 53 of the web 51 are formed. Moreover, on the protrusion 107, the continuous fibers become sparse, and a plurality of grooves 55 of the web 51 are formed.

When the height of the ridges 107 is 1.0 mm or more, continuous fibers are less likely to remain on the ridges 107, and the continuous fibers are accumulated between the ridges 107, so that a plurality of ridges having a predetermined thickness can be formed. It becomes easier to form the portion 53. Since the continuous fibers are accumulated between the protrusions 107 along the protrusions 107 so as to avoid the protrusions 107, the fiber orientation along the first direction x of the plurality of ridges 53 is different from the plurality of grooves 55 fiber orientation along the first direction x.

When the total length of each of the plurality of protrusions 107 in the transverse direction CD is 50% or less of the length of the mesh main body 105 in the transverse direction CD, a sufficient amount of gas can pass through the protrusions 107. It becomes easier to pass through the mesh body 105.

If the outer diameter of the wire 103 forming the wire mesh 101 is smaller than the height of the protrusion 107, even in the portion where the wires 103 of the wire mesh 101 overlap, if the protrusion 107 is higher than the wire 103, the plurality of grooves 55 is more likely to form. Further, since the portion where the wires 103 of the wire mesh 101 overlap are smaller than the protrusions 107, continuous fibers are less likely to be deposited in the portion where the wires 103 of the wire mesh 101 overlap, and by gathering in the mesh, the concave portions 57 This makes it easier to form the plurality of ridges 53 having the same shape.

In addition, when the continuous fibers are accumulated between the protrusions 107 on the wire mesh 101, they avoid the portions where the wires 103 overlap and are convex upward in the height direction, and collect in the mesh. , a plurality of continuous fibers are oriented in the first direction x. By forming a bonded portion in this state, a bundle portion in which a plurality of continuous fibers are oriented in the transport direction MD, that is, the first direction x is formed.

The continuous fibers are preferably deposited on the wire mesh 101 at a fiber speed of 1000 m/min or more and 4500 m/min or less. The continuous fibers are easily deposited on the wire mesh 101 and a plurality of ridges 53 are easily formed when the fiber speed is 1000 m/min or more. Further, by setting the continuous fibers at a fiber speed of 4500 m/min or less, it is possible to suppress the orientation of the continuous fibers from being disordered on the wire mesh 101, so that a plurality of ridges 53 are likely to be formed. Therefore, by having the continuous fibers within the above range, the web 51 having a plurality of ridges 53 and a plurality of grooves 55 can be efficiently manufactured.

Note that the "web preparation step" in the method for manufacturing a nonwoven fabric according to the present disclosure is not limited to the specific embodiments disclosed in FIGS. 2 to 5, and includes a high basis weight region and a low basis weight region. including methods known in the art that can form webs that contain

[Nonwoven fabric forming step]
FIG. 6 shows an example of the embossing roll among the pair of embossing rolls used in the nonwoven fabric forming step, specifically, the arrangement of the pressing portions at the tips of the plurality of protrusions 111 included in the embossing roll.
The embossing roll 109 shown in FIG. 6 includes a plurality of protrusions 111. The embossing roll 109 has a first projection direction D 1 ′ corresponding to the first direction D ₁ of the spunbond nonwoven fabric 1 and a second projection direction D _{2 ′ corresponding to the second direction D 2 of} the spunbond nonwoven fabric 1. It is equipped with
Note that the intersection angle at which the transport direction MD and the first protrusion direction D ₁ ' intersect is 15°, and the intersection angle at which the first protrusion direction D ₁ ' and the second protrusion direction D ₂ ' intersect. The intersection angle is 90°.

The plurality of protrusions 111 are intermittently arranged at a first protrusion pitch P ₁ ' in the first protrusion direction D ₁ ', and at a second protrusion pitch P ₂ in the second protrusion direction D ₂ '. ' are arranged intermittently. In other words, the plurality of protrusions 111 are arranged in a staggered manner.
Note that each compressed portion of the plurality of protrusions 111 has a diameter of 0.8 mm, and the compressed area of the compressed portion is approximately 0.50 mm ² . Further, each of the first protrusion pitch P ₁ ′ and the second protrusion pitch P _{2 ′} is 2.9 mm.

An embossing roll 109 provided with a plurality of protrusions 111 is placed on the wire mesh 101 side (that is, on the side of the web 51 where the plurality of ridges 53 and the plurality of grooves 55 are formed), and an anvil roll (not shown) ) may be arranged on the side opposite to the wire mesh 101 (that is, on the side opposite to the side on which the plurality of ridges 53 and the plurality of grooves 55 of the web 51 are formed). Thereby, the formed spunbond nonwoven fabric 1 can easily maintain its bulk, and the spunbond nonwoven fabric 1 has excellent flexibility.

Further, an anvil roll (not shown) is arranged on the wire mesh 101 side (that is, the surface side on which the plurality of ridges 53 and the plurality of grooves 55 of the web 51 are formed), and is provided with a plurality of protrusions 111. The embossing roll 109 may be placed on the side opposite to the wire mesh 101 (that is, on the side opposite to the side on which the plurality of ridges 53 and the plurality of grooves 55 of the web 51 are formed). As a result, heat is easily transferred from the plurality of protrusions 111 of the embossing roll 109 to the web 51, and the amount of heat-fusible fibers fused in the plurality of embossed parts 5 to be formed increases, and the spunbond nonwoven fabric 1 Excellent strength.
Note that the pair of embossing rolls shown in FIG. 6 is an example, and rolls known in the art can be used in the nonwoven fabric forming step.

In the method for manufacturing a nonwoven fabric according to the present disclosure, the plurality of protrusions constituting the pair of embossing rolls may have the same or different squeezing areas for squeezing the web.
When each of the plurality of protrusions has the same compressed area, the nonwoven fabric (web) has a high basis weight area in order for the plurality of embossed parts to satisfy the requirements of formulas (1) to (6). and a low basis weight region.
When each of the plurality of projections has a different compressed area, the nonwoven fabric (web) may have a high basis weight region and a low basis weight region, and the high basis weight region and the low basis weight region It does not have to have. Even if the nonwoven fabric (web) does not have a high basis weight region and a low basis weight region, it is possible for a plurality of embossed parts to satisfy the requirements of formulas (1) to (6). It's for a reason.

Hereinafter, the present disclosure will be explained by giving examples, but the present disclosure is not limited to these examples.
[Manufacture example 1]
Using the wire mesh 101 (W _L : 1.8 mm, pitch of the protrusions 107: 4.0 mm) shown in FIGS. 4 and 5 and having the protrusions 107 arranged in a stripe pattern, web No. 1 was formed. Web No. The average basis weight: BW of No. 1 was 13 g/m ² .
Web No. For spunbond nonwoven fabric No. 1, a plurality of embossed portions were formed using a pair of embossing rolls having a plurality of protrusions 111 arranged in a staggered manner as shown in FIG. 1 was formed. Note that the anvil roll was placed on the wire mesh 101 side, and the embossing roll 109 provided with a plurality of protrusions 111 was placed on the side opposite to the wire mesh 101. Spunbond nonwoven fabric No. The average basis weight: BW of No. 1 was 13 g/m ² .

[Production Example 2 and Production Example 3]
Average basis weight: Spunbond nonwoven fabric No. 2 and no. 3 was formed. Spunbond nonwoven fabric No. An image of No. 3 is shown in FIG.

[Manufacture example 4]
In the wire mesh 101, the spunbond nonwoven fabric was manufactured according to Production Example 1, except that the pitch of the protrusions 107 was changed from "4.0 mm" to "5.0 mm" and the average basis weight: BW was set as shown in Table 1. No. 4 was formed.

[Manufacture example 5]
Spunbond nonwoven fabric No. 1 was prepared in the same manner as in Production Example 1 except that the wire mesh 101 was changed to the wire mesh 101 shown in FIG. 5 was formed.
Note that FIG. 7 is a view of the wire mesh 101 viewed from the height direction H, and only the protrusions 107 are shown, and the wires are omitted.
In the wire mesh 101 shown in FIG. 7, each of the protrusions 107 has a dot shape (approximately circular) with a diameter of about 3.0 mm, and the pitch of the protrusions 107 in the transport direction MD is 8.0 mm. 0 mm, and the protrusions 107 are arranged in a staggered manner so that the pitch in the transverse direction CD is 6.0 mm.

[Production Example 6 and Production Example 7]
The protrusions 107 of the wire mesh 101 shown in FIG. 7 have a diameter of 5.0 mm, the pitch of the protrusions 107 in the transport direction MD is 10.0 mm, the pitch of the protrusions 107 in the transverse direction CD is 10.0 mm, and the average Basis weight: Spunbond nonwoven fabric No. 6 and no. 7 was formed.

[Comparative production example 1]
Spunbond nonwoven fabric No. 8 was formed.
[Comparative production examples 2 to 8]
A commercially available spunbond nonwoven fabric was purchased, and spunbond nonwoven fabric No. 9～No. It was set at 15.

[Examples 1 to 7 and Comparative Examples 1 to 8]
Spunbond nonwoven fabric No. 1~No. 15, S _AVE (mm ² ), S _MAX (mm 2 ₎ , S MIN (mm ² ), (S _MAX - S ^MIN )/S _AVE , _{S MAX /} S _AVE , according to the methods described herein. S _MIN /S _AVE and CV (%) were measured. Those values are shown in Table 1.
In addition, spunbond nonwoven fabric No. 1~No. Regarding No. 15, the following special values were measured.

[Compression characteristics per unit basis weight]
Table 1 shows initial thickness: T ₀ (mm), compressed thickness: T _m (mm), “T ₀ - T _m ” (mm), and unit tsubo measured according to the method described in this specification. Compression characteristics per quantity: (T ₀ - T _m )/BW [mm/(g/m ² )] are shown, and in FIG. 9, (S _MAX - S _MIN )/S _AVE and (T ₀ - T _m )/BW. In addition, "EX" in FIG. 9 indicates spunbond nonwoven fabric No. 1~No. 7 (Example), and "COM" means data regarding spunbond nonwoven fabric No. 7 (Example). 8 to 15 (comparative examples).

[Bending rigidity per unit basis weight and unit thickness]
Table 1 shows the bending stiffness value: B (10 ⁻⁴ mN×m ² /m) and the bending stiffness per unit basis weight and unit thickness: B/BW/T, measured according to the method described in this specification. ₀ [(10 ⁻⁴ mN×m ² /m)/(g/m ² )/mm] is shown in Table 1. Further, FIG. 10 shows the relationship between (S _MAX - S _MIN )/S _AVE and B/BW/T ₀ . In addition, "EX" in FIG. 10 indicates spunbond nonwoven fabric No. 1~No. 7 (Example), and "COM" means data regarding spunbond nonwoven fabric No. 7 (Example). 8 to 15 (comparative examples).

[Breaking strength per unit basis weight]
Table 1 shows the breaking strength: BR (N/50mm) and the breaking strength per unit basis weight: BR/BW [(N/50mm)/(g/m ² ), measured according to the method described in this specification. ], and Figure 11 shows the relationship between (S _MAX - S _MIN )/S _AVE and breaking strength per unit basis weight: BR/BW [(N/50 mm)/(g/m ² )]. show. In addition, "EX" in FIG. 11 indicates spunbond nonwoven fabric No. 1~No. 7 (Example), and "COM" means data regarding spunbond nonwoven fabric No. 7 (Example). 8 to 15 (comparative examples).

From the data on compression properties per unit basis weight (Table 1 and FIG. 9), spunbond nonwoven fabric No. 1~No. 7 is spunbond nonwoven fabric No. Compared to 8 to 15, the compression property per unit basis weight is large, that is, the difference between the initial thickness (T ₀ ) of the nonwoven fabric and the thickness upon compression (T _m ) is large per unit basis weight. This shows that when a user touches the nonwoven fabric, the nonwoven fabric easily deforms in the thickness direction and has excellent flexibility.

From the data of B/BW/T ₀ (Table 1 and FIG. 10), spunbond nonwoven fabric No. 1~No. 7 is spunbond nonwoven fabric No. It can be seen that the bending rigidity per unit basis weight and unit thickness is small compared to samples Nos. 8 to 15, the nonwoven fabric easily deforms when force is applied, and it has excellent flexibility.
From the data on breaking strength per unit basis weight (Table 1 and FIG. 11), spunbond nonwoven fabric No. 1~No. 7 is spunbond nonwoven fabric No. It can be seen that it has a breaking strength equal to or higher than that of 8 to 15.

1 Spunbond nonwoven fabric 3 Embossed area 5 Embossed part 7 First embossed part 9 Second embossed part 11 High basis weight area 13 Low basis weight area 51 Web 53 Ridge section 55 Groove section 57 Recessed section 59 Base section 61 Bundled section 63 Projection section PD Plane Direction D ₁ First direction D ₂ Second direction P ₁ First pitch P ₂ Second pitch

Claims (14)

A nonwoven fabric comprising an embossed area including a plurality of embossed parts regularly arranged in a plane direction,
The maximum value of the individual areas of the plurality of embossed parts is S _MAX , the minimum value of the individual areas of the plurality of embossed parts is S _MIN , and the average value of the individual areas of the plurality of embossed parts is S _AVE . In this case, the plurality of embossed portions in the embossed area satisfy the following formula (1):
0.94≦(S _MAX - S _MIN )/S _AVE ≦2.50 Formula (1)
satisfy,
The nonwoven fabric is characterized in that: The nonwoven fabric according to claim 1, wherein the nonwoven fabric is used for an exterior sheet or a liquid permeable sheet of an absorbent article. When the coefficient of variation of the area of each of the plurality of embossed portions is CV, the plurality of embossed portions in the embossed area are expressed by the following formula (2):
10≦CV≦70 Formula (2)
The nonwoven fabric according to claim 1 or 2, which satisfies the following. The plurality of embossed parts in the embossed area are expressed by the following formula (3):
0.09≦S _MIN /S _AVE formula (3)
satisfy,
The nonwoven fabric according to any one of claims 1 to 3. If the number of the plurality of embossed portions is N, and the number of the plurality of embossed portions having an area of 80% or more and 120% or less of S _AVE is _N1 , then the number of the plurality of embossed portions in the embossed area is N1. The embossed part has the following formula (4):
0.26≦N ₁ /N≦0.90 Formula (4)
satisfy,
The nonwoven fabric according to any one of claims 1 to 4. In the embossed area, the nonwoven fabric includes a high basis weight area having a basis weight higher than the average basis weight of the nonwoven fabric, and a low basis weight area having a basis weight lower than the average basis weight. 6. The nonwoven fabric according to any one of 1 to 5. When the average value of the individual areas of the plurality of embossed portions in the low basis weight region is SL _AVE , the plurality of embossed portions in the embossed region are expressed by the following formula (5):
SL _AVE < S _AVE formula (5)
satisfy,
The nonwoven fabric according to claim 6. When the average value of the individual areas of the plurality of embossed portions in the high basis weight region is SH _AVE , the plurality of embossed portions in the embossed region are expressed by the following formula (6):
S _AVE < SH _AVE formula (6)
satisfy,
The nonwoven fabric according to claim 6 or 7. The nonwoven fabric according to any one of claims 6 to 8, wherein the nonwoven fabric is composed of continuous fibers. In the embossed region, the high basis weight region and the low basis weight region are each composed of a ridge portion protruding in one direction in the thickness direction of the nonwoven fabric and a groove portion recessed in the one direction,
The nonwoven fabric according to claim 9, wherein the ridge further includes a plurality of recesses recessed in one direction, and a base made of the continuous fiber is provided at the bottom of each of the plurality of recesses. The planar direction includes a first direction and a second direction intersecting the first direction,
Any one of claims 1 to 10, wherein the plurality of embossed portions are intermittently arranged at a first pitch in a first direction and intermittently arranged at a second pitch in a second direction. The nonwoven fabric described in . The nonwoven fabric according to claim 11, wherein the intersecting angle between the first direction and the second direction is 60 to 90°. The nonwoven fabric according to claim 11 or 12, wherein the first pitch and the second pitch are the same. A method for producing a nonwoven fabric according to any one of claims 6 to 10, comprising:
providing a web comprising the high basis weight region and the low basis weight region;
forming the plurality of embossed portions on the web using a pair of embossing rolls including an embossing roll having a plurality of protrusions and an anvil roll to form the nonwoven fabric;
including;
Each of the plurality of protrusions has the same compression area,
The method as described above.

Images