Nonwoven fabric and method for manufacturing the same

Abstract

The present disclosure aims to provide a nonwoven fabric regularly provided with embossed portions and excellent in strength and softness. The nonwoven fabric according to the present disclosure has the following configuration. A nonwoven fabric (1) has an embossed region (3) including a plurality of embossed portions (5) regularly arranged in a planar direction, and is characterized in that a maximum value of areas of the plurality of embossed portions (5) is S MAX a minimum value of the areas of the plurality of embossed portions (5) is S MIN an average value of the areas of the plurality of embossed portions (5) is S AVE In this case, the plurality of embossed portions (5) in the embossed region (3) satisfy the following formula (1): 0.94 ≤ (S MAX -S MIN ) / S AVE ≤ 2.50.

Description

Technical Field

[0001] This disclosure relates to nonwoven fabrics and methods for manufacturing such nonwoven fabrics. Background Technology

[0002] Nonwoven fabrics, such as spunbond nonwoven fabrics, are used as outer sheets for absorbent materials, liquid-permeable sheets, etc., formed by creating multiple embossed sections on a fiber web.

[0003] Spunbond nonwoven fabric is a type of nonwoven fabric with excellent production performance, strength, and breathability. On the other hand, from the point of view of ensuring strength, it is necessary to arrange multiple embossed parts with a small spacing. Therefore, spunbond nonwoven fabric is thin and tends to have reduced softness.

[0004] To address this issue, for example, Patent Document 1 (claim 1) discloses a nonwoven fabric having multiple embossed portions that have undergone embossing processing over the entire surface, wherein the shortest distance from the boundary between the four closest embossed portions adjacent to any embossed portion and the non-embossed portion to the boundary between the arbitrary embossed portion and the non-embossed portion is 1.8 mm or more and less than 4.5 mm, and the area proportion of the embossed portion formed by the embossing process in the entire area of ​​the nonwoven fabric is 8% or more and less than 14%.

[0005] Prior art literature

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2019-157306 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] The nonwoven fabric described in Patent Document 1 improves the softness of the nonwoven fabric by setting the distance between the embossed portions and the area ratio of the compressed portions within a specific range. However, the nonwoven fabric described in Patent Document 1 has embossed portions with uniform shapes arranged regularly (e.g., in an alternating pattern), and the shape and arrangement of such embossed portions lead to a decrease in the softness of the nonwoven fabric.

[0010] Therefore, the purpose of this disclosure is to provide a nonwoven fabric with regularly arranged embossed portions that has excellent strength and softness.

[0011] Solution for solving the problem

[0012] The inventors of this disclosure have discovered a nonwoven fabric having an embossed area comprising a plurality of embossed portions regularly arranged in a planar direction, characterized in that the maximum value of the area of ​​each of the plurality of embossed portions is set as S. MAX Let the minimum area of ​​each of the above embossed parts be S.MIN Let S be the average area of ​​each of the above embossed parts. AVE In this case, the plurality of embossed portions in the embossed area satisfy the following equation (1): 0.94 ≤ (S MAX -S MIN ) / S AVE ≤2.50.

[0013] The effects of the invention

[0014] The nonwoven fabric disclosed herein has regularly arranged embossed sections and exhibits excellent strength and softness. Attached Figure Description

[0015] Figure 1 This is a diagram used to illustrate the spunbond nonwoven fabric 1 according to the first embodiment.

[0016] Figure 2 This is a diagram illustrating the manufacturing method of spunbond nonwoven fabric 1.

[0017] Figure 3 This is a diagram illustrating the manufacturing method of spunbond nonwoven fabric 1.

[0018] Figure 4 This is a diagram illustrating the manufacturing method of spunbond nonwoven fabric 1.

[0019] Figure 5 This is a diagram illustrating the manufacturing method of spunbond nonwoven fabric 1.

[0020] Figure 6 This is a diagram used to illustrate embossing rollers.

[0021] Figure 7 This is a diagram used to illustrate the wire mesh 101 used in manufacturing example 5.

[0022] Figure 8 These are images used to illustrate the embodiments.

[0023] Figure 9 This is a graph used to illustrate the embodiments.

[0024] Figure 10 This is a graph used to illustrate the embodiments.

[0025] Figure 11 This is a graph used to illustrate the embodiments. Detailed Implementation

[0026] Specifically, this disclosure involves the following methods.

[0027] [Method 1]

[0028] A nonwoven fabric comprising an embossed area including a plurality of embossed portions regularly arranged in a planar direction, characterized in that,

[0029] Let the maximum area of ​​each of the above embossed sections be S. MAX Let the minimum area of ​​each of the above embossed parts be S. MIN Let S be the average area of ​​each of the above embossed parts. AVE In this case, the plurality of embossed portions in the embossed area satisfy the following equation (1):

[0030] 0.94≤(S MAX -S MIN ) / S AVE ≤2.50 Equation (1).

[0031] In the above nonwoven fabric, multiple embossed portions in the embossed area satisfy equation (1).

[0032] In equation (1), when S MIN And the embossed area of ​​similar size (hereinafter sometimes referred to as "S") MIN The fibers constituting the nonwoven fabric in the embossed area (near the embossed portion), and its surrounding portion (hereinafter sometimes referred to as the "embossed portion periphery"), are relatively weakly bonded to the embossed portion. The embossed portion periphery is soft and tends to deform easily. Additionally, in areas with S... MAX And an embossed section of similar area, where the fibers constituting the nonwoven fabric at the periphery of the embossed section are relatively strongly bonded to the embossed section, and there is a tendency for the strength of the periphery of the embossed section to increase.

[0033] By making (S) MAX -S MIN ) / S AVE If equation (1) is satisfied, the above nonwoven fabric becomes superior in both strength and softness.

[0034] Additionally, if (S MAX -S MIN ) / S AVE Below 0.94, the difference between the soft and easily deformable parts of the nonwoven fabric and the high-strength parts becomes smaller, indicating a tendency for the nonwoven fabric to become less soft. Additionally, if (S... MAX -S MIN ) / S AVE If the value exceeds 2.50, the difference between the soft and easily deformable parts of the nonwoven fabric and the high-strength parts becomes too large, resulting in an imbalance in strength. MIN The strength of the nonwoven fabric decreases at the periphery of the embossed area, and there is a tendency for the overall strength of the nonwoven fabric to deteriorate.

[0035] Based on the above configuration, by making multiple embossed portions in the embossed area satisfy equation (1), the nonwoven fabric becomes superior in terms of strength and softness in the embossed area.

[0036] [Method 2]

[0037] The nonwoven fabric as described in method 1 is characterized in that,

[0038] The aforementioned nonwoven fabric is used as an outer packaging sheet or liquid-permeable sheet for absorbent articles.

[0039] Since the aforementioned nonwoven fabric is used as an outer sheet or liquid-permeable sheet for absorbent articles, it can impart a certain strength to the absorbent articles and make the user feel soft when used in absorbent articles.

[0040] [Method 3]

[0041] The nonwoven fabric as described in method 1 or 2 is characterized in that,

[0042] When the variation coefficient of the area of ​​each of the above-mentioned embossed parts is set to CV, the above-mentioned embossed parts in the above-mentioned embossed region satisfy the following equation (2):

[0043] 10≤CV≤70 (2)

[0044] In the above nonwoven fabric, since multiple embossed parts in the embossed area satisfy equation (2), the area of ​​each of the multiple embossed parts has a certain deviation, and the effect of method 1 is higher.

[0045] [Method 4]

[0046] The nonwoven fabric according to any one of methods 1 to 3 is characterized in that...

[0047] The aforementioned embossed portions in the embossed area satisfy the following equation (3):

[0048] 0.09≤S MIN / S AVE Equation (3).

[0049] In the above nonwoven fabric, in the embossed area, multiple embossed parts in the embossed area satisfy equation (3).

[0050] By satisfying equation (3), in S MIN Near the embossed area, the fibers of the nonwoven fabric are bonded to the embossed area with a certain strength. The periphery of the embossed area is soft and tends to be easily deformed.

[0051] In addition, in equation (3), if S MIN / S AVE If it is below 0.09, then in S MINNear the embossed area, the fibers of the nonwoven fabric are weakly bonded to the embossed area, which tends to weaken the strength of the nonwoven fabric.

[0052] Based on the above structure, the nonwoven fabric exhibits excellent strength in the embossed area by satisfying equation (3) through multiple embossed portions in the embossed area.

[0053] [Method 5]

[0054] The nonwoven fabric according to any one of methods 1 to 4 is characterized in that,

[0055] Let N be the number of the aforementioned embossed parts, and let S be one of the aforementioned embossed parts. AVE The number of embossed portions covering 80% to 120% of the area is set as N1. In this case, the plurality of embossed portions in the embossed area satisfy the following equation (4):

[0056] 0.26≤N1 / N≤0.90 Equation (4).

[0057] In the above nonwoven fabric, multiple embossed portions in the embossed area satisfy equation (3).

[0058] By satisfying equation (3), multiple embossed parts possess an average value (S) within a certain range. AVE The embossed area of ​​the above nonwoven fabric has an excellent balance of strength and softness in the embossed area.

[0059] [Method 6]

[0060] The nonwoven fabric according to any one of methods 1 to 5 is characterized in that,

[0061] In the aforementioned embossed area, the nonwoven fabric has a high-basis-weight region having a basis weight higher than the average basis weight of the nonwoven fabric and a low-basis-weight region having a basis weight lower than the average basis weight.

[0062] Because the aforementioned nonwoven fabric has high-basic-weight regions and low-basic-weight regions in the embossed area, the high-basic-weight regions of the nonwoven fabric exhibit excellent strength, while the low-basic-weight regions exhibit excellent softness.

[0063] [Method 7]

[0064] The nonwoven fabric as described in method 6 is characterized in that...

[0065] Let the average area of ​​each of the plurality of embossed portions in the aforementioned low basis weight region be SL. AVE In the case of embossing, the above-mentioned multiple embossed parts in the embossed area satisfy the following equation (5):

[0066] SL AVE <SAVE Equation (5).

[0067] In the above nonwoven fabric, multiple embossed portions in the embossed area satisfy equation (5).

[0068] By satisfying equation (5), the average area (SL) of each of the multiple embossed parts in the low basis weight region is obtained. AVE ) lower than the average area of ​​each of the multiple embossed sections (S) AVE As a result, the low basis weight region has (i) softness due to the low basis weight and (ii) softness at the periphery of the embossed portion of the multiple embossed portions due to the fibers constituting the nonwoven fabric bonding with the embossed portion with a certain strength. The nonwoven fabric has excellent softness in the embossed region and the low basis weight region.

[0069] [Method 8]

[0070] The nonwoven fabric as described in method 6 or 7 is characterized in that,

[0071] Let the average area of ​​each of the aforementioned embossed portions in the high-basicity region be SH. AVE In the case of embossing, the plurality of embossed portions in the embossed area satisfy the following equation (6):

[0072] S AVE <SH AVE Equation (6).

[0073] In the above nonwoven fabric, multiple embossed portions in the embossed area satisfy equation (6).

[0074] By satisfying equation (6), the average area of ​​each of the multiple embossed parts in the high base weight region (SH) AVE ) higher than the average area of ​​each of the multiple embossed sections (S) AVE The high basis weight region has (i) strength due to the high basis weight and (ii) strength in the peripheral part of the embossed part of the multiple embossed parts due to the strong bonding between the fibers constituting the nonwoven fabric and the embossed part. The nonwoven fabric has excellent strength in the embossed region and the high basis weight region.

[0075] [Method 9]

[0076] The nonwoven fabric as described in any one of methods 6 to 8 is characterized in that...

[0077] The aforementioned nonwoven fabric is composed of continuous fibers.

[0078] Because the nonwoven fabric is composed of continuous fibers, the high-basic-weight region and the low-basic-weight region are directly connected by the continuous fibers, resulting in the nonwoven fabric having excellent strength.

[0079] [Method 10]

[0080] The nonwoven fabric as described in method 9 is characterized in that...

[0081] In the aforementioned embossed area, the aforementioned high-basic-weight area and the aforementioned low-basic-weight area are respectively composed of a ridge protruding in one direction toward the thickness direction of the nonwoven fabric and a groove protruding in one direction.

[0082] The aforementioned ridge also has a plurality of recesses that are concave toward the aforementioned side, and each of the plurality of recesses has a base made of the aforementioned continuous fibers at its bottom.

[0083] Because the aforementioned nonwoven fabric has multiple recesses in the thickness direction within the ribbed region formed by the high basis weight, the area of ​​contact between the user's skin and the nonwoven fabric is smaller than that of nonwoven fabrics without these recesses. Therefore, the aforementioned nonwoven fabric provides the user with a dry and comfortable feel.

[0084] When the aforementioned nonwoven fabric is used, for example, as an outer layer of absorbent articles such as disposable diapers, and when the nonwoven fabric is arranged with the side having multiple ridges and grooves facing the non-skin side, the contact area of ​​the nonwoven fabric surface is reduced by a corresponding amount to the recesses, thus providing a dry feel. Furthermore, because the aforementioned nonwoven fabric has a complex fabric-like surface shape, it can impart a fabric-like (woven fabric-like) texture to disposable diapers.

[0085] Furthermore, when the aforementioned nonwoven fabric is used, for example, in the outer covering of absorbent articles such as disposable diapers, and when the nonwoven fabric is arranged with the side having multiple ridges and multiple grooves facing the skin, the space formed between it and the liquid-impermeable sheet further increases the amount corresponding to the recesses, thus making it more difficult to transfer moisture to clothing, sheets, etc.

[0086] In applications such as liquid-permeable sheets for absorbent articles, the aforementioned nonwoven fabric absorbs excreted bodily fluids at the base and effectively prevents the absorbed bodily fluids from returning to the recesses. Therefore, the aforementioned nonwoven fabric exhibits excellent performance in suppressing a feeling of wetness.

[0087] [Method 11]

[0088] The nonwoven fabric according to any one of methods 1 to 10 is characterized in that,

[0089] The aforementioned planar directions include the first direction and the second direction intersecting the first direction.

[0090] The aforementioned plurality of embossed portions are arranged intermittently at a first spacing in the first direction and intermittently at a second spacing in the second direction.

[0091] Because the nonwoven fabric described above is configured with multiple embossed sections according to the prescribed arrangement, method 1 is more effective.

[0092] [Method 12]

[0093] The nonwoven fabric as described in method 11 is characterized in that,

[0094] The intersection angle between the first and second directions is 60° to 90°.

[0095] In the aforementioned nonwoven fabric, since the intersection angle is within a specified range, the multiple embossed portions can easily achieve a grid shape close to a rectangle, and the aforementioned nonwoven fabric can easily have a certain strength relative to any direction. On the other hand, in the aforementioned nonwoven fabric, since the multiple embossed portions at least satisfy equation (1), the nonwoven fabric has softness.

[0096] Based on the above composition, the nonwoven fabric exhibits excellent strength in any direction and excellent softness.

[0097] [Method 13]

[0098] The nonwoven fabric as described in method 11 or 12 is characterized in that,

[0099] The first spacing is the same as the second spacing.

[0100] In the aforementioned nonwoven fabric, since the first and second spacings are the same, the multiple embossed portions can easily achieve a grid shape close to a square, and the aforementioned nonwoven fabric is more likely to have a certain strength relative to any direction. On the other hand, in the aforementioned nonwoven fabric, since the multiple embossed portions at least satisfy equation (1), the nonwoven fabric has softness.

[0101] Based on the above composition, the nonwoven fabric exhibits excellent strength in any direction and excellent softness.

[0102] [Method 14]

[0103] A method for manufacturing a nonwoven fabric, wherein the method manufactures the nonwoven fabric according to any one of methods 6 to 10, characterized in that,

[0104] The above-mentioned method for manufacturing nonwoven fabric includes:

[0105] The steps of preparing a fiber web having the aforementioned high basicity region and the aforementioned low basicity region; and

[0106] The step of forming the nonwoven fabric by using a pair of embossing rollers, each having multiple protrusions, to form the multiple embossed portions on the fiber web.

[0107] The aforementioned protrusions each have the same compression area.

[0108] The above manufacturing method can manufacture nonwoven fabrics involved in any of methods 6 to 10.

[0109] Furthermore, in the above manufacturing method, since each of the multiple protrusions has the same compression area, the pressure applied to the fiber web from the multiple protrusions is easily made uniform in the conveying direction and the transverse direction of the embossing roller. Therefore, a nonwoven fabric with excellent strength and softness can be formed with high precision.

[0110] The following provides a detailed description of the nonwoven fabric and its manufacturing method.

[0111] [Non-woven fabric]

[0112] The nonwoven fabric disclosed herein has an embossed area comprising a plurality of embossed portions regularly arranged in a planar direction.

[0113] The aforementioned planar direction refers to the direction in which the nonwoven fabric expands. The configuration of the rules will be described later.

[0114] In the nonwoven fabric disclosed herein, the maximum value of the area of ​​each of the multiple embossed portions is set as S. MAX Let S be the minimum area of ​​each of the multiple embossed parts. MIN Let S be the average area of ​​each of the multiple embossed parts. AVE In this case, the multiple embossed portions in the embossed area satisfy the following equation (1):

[0115] 0.94≤(S MAX -S MIN ) / S AVE ≤2.50 Equation (1).

[0116] As a result, the aforementioned nonwoven fabrics exhibit superior strength and softness.

[0117] (S MAX -S MIN ) / S AVE Preferably, the value is 0.94 or higher, more preferably 0.96 or higher, and even more preferably 0.97 or higher. This easily ensures the difference between the soft, easily deformable portion and the high-strength portion of the nonwoven fabric.

[0118] (S MAX -S MIN ) / S AVE Preferably, the value is 2.20 or less, more preferably 2.00 or less, and even more preferably 1.80 or less. This allows the difference between the soft, easily deformable portion and the high-strength portion of the nonwoven fabric to be set within a certain range.

[0119] In addition, in this specification, the area of ​​each of the multiple embossed parts and the maximum value of the area of ​​each of the multiple embossed parts (S) are specified. MAX The minimum area of ​​each of the multiple embossed parts (S) MIN) and the average area of ​​each of the multiple embossed parts (S) AVE The method for determining the area of ​​the embossed part (hereinafter sometimes referred to as the "method for determining the area of ​​the embossed part") is as follows.

[0120] (1) In a constant temperature and humidity chamber adjusted to a temperature of 20°C and a humidity of 60%RH, prepare a VHX-7000 (lens: E30) manufactured by KEYENCE.

[0121] (2) Cut the non-woven fabric into 100mm×100mm size, prepare the sample, and let the sample stand in the constant temperature and humidity room for 24 hours.

[0122] (3) Place the sample on the VHX-7000 stage.

[0123] (4) Take images of multiple embossed parts under the following conditions.

[0124] Multiplier: 30x

[0125] • Radiant lighting: Turn off

[0126] (Ring lighting)

[0127] • Tilt angle: 0°

[0128] • Support plate: Glass support plate

[0129] (5) Select “Measurement / Scale”, “Plane Measurement”, “Area Measurement” from the menu screen, and draw the broken parts of multiple fibers according to the “Free Line” setting to extract the shape of the embossed part.

[0130] (6) Use VHX-7000 to measure the area of ​​the extracted part of the embossed part.

[0131] (7) Measure the area of ​​a total of 100 embossed parts and calculate S. MAX S MIN and S AVE .

[0132] In the nonwoven fabrics disclosed herein, when the variation coefficient of the area of ​​each of the plurality of embossed portions is set as CV, the plurality of embossed portions in the embossed region satisfy the following equation (2):

[0133] 10≤CV≤70 (2)

[0134] As a result, the aforementioned nonwoven fabrics exhibit superior strength and softness.

[0135] The CV is preferably 14 or more, more preferably 17 or more, and even more preferably 20 or more. Furthermore, the CV is preferably 60 or less, more preferably 55 or less, and even more preferably 50 or less. Therefore, the aforementioned nonwoven fabric exhibits superior strength and softness.

[0136] Additionally, CV refers to the following CV (%): the standard deviation of the area of ​​each of the multiple embossed portions in the embossed area divided by the average area of ​​each of the multiple embossed portions (S). AVE Multiply by 100 to convert to a percentage, and then calculate.

[0137] In the nonwoven fabrics disclosed herein, the plurality of embossed portions in the embossed region satisfy the following equation (3):

[0138] 0.09≤S MIN / S AVE Equation (3).

[0139] Therefore, nonwoven fabrics exhibit excellent strength in the embossed areas. Additionally, in S... MIN The strength of the nonwoven fabric decreases in the periphery of the embossed area, indicating a tendency for the overall strength of the nonwoven fabric to deteriorate.

[0140] S MIN / S AVE Preferably, it is 0.12 or higher, more preferably 0.14 or higher, and even more preferably 0.16 or higher. Additionally, S MIN / S AVE Preferably, the strength is 0.7 or less, more preferably 0.6 or less, and even more preferably 0.5 or less. This results in excellent strength of the nonwoven fabric in the embossed area.

[0141] In the nonwoven fabrics disclosed herein, it is preferable to set the number of embossed portions to N, and to have S among the embossed portions. AVE The number of embossed portions covering 80% to 120% of the area is set as N1. In this case, the multiple embossed portions in the embossed area satisfy the following equation (4):

[0142] 0.26≤N1 / N≤0.90 Equation (4).

[0143] Therefore, the above-mentioned nonwoven fabric exhibits excellent balance between strength and softness in the embossed area.

[0144] The N1 / N ratio is preferably 0.30 or higher, more preferably 0.35 or higher, and even more preferably 0.40 or higher. Furthermore, the N1 / N ratio is preferably 0.88 or lower, more preferably 0.86 or lower, and even more preferably 0.84 or lower. Therefore, the aforementioned nonwoven fabric exhibits excellent balance between strength and softness in the embossed area.

[0145] Additionally, N can be determined by measuring the number of embossed portions in the embossed area, and N1 can be determined by measuring the number of embossed portions with S in the embossed area. AVE The number of embossed sections is determined by the area of ​​80% to 120% of the total area.

[0146] The nonwoven fabric disclosed herein preferably has a high-basis-weight region with a basis weight higher than the average basis weight of the nonwoven fabric and a low-basis-weight region with a basis weight lower than the average basis weight in the embossing region. Therefore, the aforementioned nonwoven fabric exhibits excellent strength in the high-basis-weight region and excellent softness in the low-basis-weight region of the embossing region.

[0147] In addition, nonwoven fabrics known in the art can be cited as examples of nonwoven fabrics that possess the aforementioned high basis weight region and low basis weight region.

[0148] In the nonwoven fabrics disclosed herein, the average area of ​​each of the plurality of embossed portions in the low basis weight region is set as SL. AVE In such cases, multiple embossed portions in the embossed area satisfy the following equation (5):

[0149] SL AVE <S AVE Equation (5).

[0150] Therefore, nonwoven fabrics exhibit superior softness in embossed and low-basic-weight areas.

[0151] Additionally, the average area of ​​each of the multiple embossed portions in the low basis weight region: SL AVE The average area of ​​each of the multiple embossed sections: S AVE The size can be evaluated visually. Alternatively, the aforementioned size can be determined using the "method for measuring the area of ​​embossed portions" described above, by measuring the average area (SL) of multiple embossed portions in the low basis weight region. AVE ), and the average area of ​​each of the multiple embossed parts (S) AVE The judgment is made by comparison.

[0152] In the nonwoven fabrics disclosed herein, the average area of ​​each of the multiple embossed portions in the high-basic-weight region is set as SH. AVE In such cases, multiple embossed portions in the embossed area satisfy the following equation (6):

[0153] S AVE <SH AVE Equation (6).

[0154] Therefore, nonwoven fabrics exhibit excellent strength in embossed and high-basic-weight areas.

[0155] In addition, the average area of ​​each of the multiple embossed portions in the high-basicity region: SH AVEThe average area of ​​each of the multiple embossed sections: S AVE The size can be evaluated visually. Alternatively, the aforementioned size can be determined using the "method for measuring the area of ​​embossed portions" described above, by measuring the average area (SH) of multiple embossed portions in the high-base-weight region. AVE ), and the average area of ​​each of the multiple embossed parts (S) AVE The judgment is made by comparison.

[0156] There are no particular limitations on the nonwoven fabrics involved in this disclosure if they have multiple embossed sections, such as spunbond nonwoven fabrics, spunbond / meltblown / spunbond nonwoven fabrics (SMS nonwoven fabrics), dot-bonded nonwoven fabrics, etc.

[0157] The fibers constituting the nonwoven fabrics disclosed herein include heat-melting fibers. Examples of such heat-melting fibers include single fibers of polyolefins such as polyethylene, polypropylene, and polyvinyl alcohol; core-sheath type composite fibers containing olefin resins, such as polyethylene terephthalate (core) / polyethylene (sheath), polyethylene terephthalate (core) / polypropylene (sheath), and polypropylene (core) / polyethylene (sheath). Furthermore, the aforementioned heat-melting fibers may also be biodegradable fibers such as polylactic acid, polyethylene glycol, polyhydroxybutyrate, polyhydroxybutyrate, polyhydroxybutyrate / adipate, and adipate.

[0158] The aforementioned composite fibers can be either hydrophobic fibers or fibers that have undergone hydrophilic treatment using hydrophilic oils or the like. Hydrophilic treatment can be performed, for example, by kneading a hydrophilic agent into the resin constituting the fiber or by coating the fiber surface with a hydrophilic agent. Furthermore, composite fibers can also be parallel-type fibers containing olefin-based resins as described above. These fibers can be used individually or in combination of two or more types of fibers.

[0159] Furthermore, the aforementioned fibers are preferably composed of continuous fibers. As a result, the aforementioned nonwoven fabric exhibits excellent strength.

[0160] In the case where the nonwoven fabric disclosed herein has a high-basicity region and a low-basicity region in the embossed area, it is preferable that the high-basicity region and the low-basicity region are respectively composed of a ridge protruding in one direction toward the thickness direction of the nonwoven fabric and a groove recessed in one direction. The ridge also has a plurality of recesses recessed in the aforementioned direction, and each of the plurality of recesses has a base composed of continuous fibers at its bottom. As a result, it can provide the user with a dry touch, has excellent dampness suppression, can give the fabric a texture, and makes it more difficult for moisture to be transferred to clothing, sheets, etc.

[0161] In the nonwoven fabrics disclosed herein, the term "regularly arranged in a planar direction" refers to a planar direction having a first direction, wherein the plurality of embossed portions are regularly arranged in at least the first direction.

[0162] Furthermore, in the nonwoven fabric disclosed herein, it is preferable that the planar direction has a first direction and a second direction intersecting the first direction, and that a plurality of embossed portions are regularly arranged in the first and second directions. More preferably, they are arranged intermittently at a first interval in the first direction and intermittently at a second interval in the second direction. As a result, the nonwoven fabric tends to have superior strength.

[0163] In addition, the first direction refers to the direction in which the embossed parts are the shortest distance from each other among the multiple embossed parts, and the second direction refers to the direction in which the embossed parts are the shortest distance from each other in a direction different from the first direction.

[0164] In the nonwoven fabric disclosed herein, when multiple embossed portions are regularly arranged in a first direction and a second direction, the angle between the first direction and the second direction exceeds 0° and is less than 90°. Preferably, the angle is 30° or more, more preferably 45° or more, further preferably 60° or more, and even more preferably 75° or more. Therefore, the nonwoven fabric readily possesses a certain strength relative to any direction.

[0165] In the nonwoven fabric disclosed herein, when multiple embossed portions are intermittently arranged at a first spacing in a first direction and at a second spacing in a second direction, the first spacing and the second spacing can be the same or different. By making the first spacing and the second spacing the same, the multiple embossed portions can easily achieve a grid shape close to a square, and the aforementioned nonwoven fabric is more likely to have a certain strength relative to any direction.

[0166] The shape, dimensions, and average basis weight of the nonwoven fabrics disclosed herein vary depending on their intended use. For example, when the aforementioned nonwoven fabrics are used in absorbent articles, their average basis weight is, for example, 8 to 80 g / m³. 2 .

[0167] In this specification, the average basis weight of the nonwoven fabric is: BW (g / m³). 2 The following method was used to determine it.

[0168] (1) Cut five samples of a specified size (e.g., 100mm × 100mm) from the nonwoven fabric.

[0169] (2) The mass of the five cut samples was determined by a balance (e.g., an electronic balance HF-300 manufactured by Kensei Kogyo Co., Ltd.).

[0170] (3) Calculate the mass per unit area of ​​the nonwoven fabric from the average mass of the 5 samples, and set it as the average basis weight of the nonwoven fabric: BW (g / m²). 2 ).

[0171] The average thickness of the nonwoven fabric varies depending on its intended use. For example, when the nonwoven fabric is used in absorbent articles, the average thickness of the nonwoven fabric is, for example, 0.1 mm to 3 mm.

[0172] The average thickness of the nonwoven fabric mentioned above refers to the average of five measurements obtained by means of: FS-60DS (measurement surface 50.5 mm (diameter), measurement pressure 3 gf / cm) manufactured by Daiei Scientific Instruments Co., Ltd. 2 [0.3kPa] Under standard conditions (temperature 23±2℃, relative humidity 50±5%), pressure was applied to five different parts of the nonwoven fabric, and the thickness of each part after 10 seconds of pressure was measured.

[0173] The nonwoven fabrics involved in this disclosure will have their initial thickness T0 (mm) and thickness during compression measured using an automated compression tester KES-FB3-A manufactured by KATO TECH (Co., Ltd.). m The difference (mm) is "T0-T m (mm) divided by the average basis weight of the nonwoven fabric: BW (g / m 2 The compressibility per unit weight is obtained as follows: (T0 - T) m ) / BW[mm / (g / m 2 The preferred value is 0.010 or higher, more preferably 0.011 or higher, and even more preferably 0.012 or higher. Additionally, the compression characteristic per unit basis weight is: (T0 - T...) m ) / BW[mm / (g / m 2 The preferred value is 0.030 or less, more preferably 0.025 or less, and even more preferably 0.020 or less. Therefore, when a user comes into contact with the nonwoven fabric, the nonwoven fabric easily deforms in the thickness direction, exhibiting excellent softness.

[0174] The initial thickness (T0) and thickness during compression (T) were measured using the KATO TECH KES-FB3-A automated compression tester manufactured by KATO TECH Co., Ltd. m The measurement conditions (mm) are as follows.

[0175] SENS: 2

[0176] Speed: 0.02 mm / s

[0177] Travel: 5mm / 10V

[0178] Pressurized area: 2cm 2

[0179] Retrieval interval: 0.1 seconds

[0180] Upper limit load: 50g / cm2

[0181] Number of repetitions: 1

[0182] Additionally, the initial thickness: T0 (mm) represents the thickness at 0.05 kPa (0.5 gf / cm). 2 The thickness of the nonwoven fabric under pressure, and the thickness under compression: T m (mm) represents 4.9 kPa (50 gf / cm). 2 The thickness of the nonwoven fabric when pressure is applied.

[0183] For the nonwoven fabrics involved in this disclosure, the bending stiffness value measured using a pure bending testing machine KES-FB2-A manufactured by KATO TECH (Co., Ltd.) is: B(10 -4 mN×m 2 The value obtained by dividing / m) by the average basis weight of the nonwoven fabric: BW and the initial thickness of the nonwoven fabric: T0 (mm) is the bending stiffness per unit basis weight and unit thickness: B / BW / T0[(10 -4 mN×m 2 / m) / (g / m 2 The value of ) / mm is preferably 0.5 or more, more preferably 1.0 or more, and even more preferably 1.2 or more. Additionally, the bending stiffness per unit basis weight and unit thickness is: B / BW / T0[(10 -4 mN×m 2 / m) / (g / m 2 The ratio [) / mm] is preferably less than 2.7, more preferably less than 2.5, and even more preferably less than 2.3. Therefore, the nonwoven fabric is easily deformed when force is applied, exhibiting excellent softness.

[0184] The bending stiffness value of the pure bending testing machine KES-FB2-A manufactured by KATO TECH (Co., Ltd.) was: B(10) -4 mN×m 2 The determination conditions for ( / m) are as follows.

[0185] SENS: 20

[0186] Maximum curvature: ±2.5

[0187] Sample width: 100mm

[0188] Number of repetitions: 1

[0189] In addition, the bending stiffness value B is calculated between 0.5 and 1.5.

[0190] In addition, the bending direction is implemented under the condition that the bending line is parallel to the CD direction of the sample and then folded back in the MD direction.

[0191] Bending stiffness value: B is the average value of n=5.

[0192] The bending stiffness value (B) indicates that the smaller the value, the easier it is to bend and deform. In the case of nonwoven fabrics with a small bending stiffness value (B), such as those used in the outer covering of absorbent items, the nonwoven fabric deforms easily upon contact with the surface and follows the movement of the fingertips, thus feeling soft.

[0193] Additionally, the bending stiffness value: B is divided by the average basis weight of the nonwoven fabric: BW and the initial thickness of the nonwoven fabric: T0 (mm) to obtain the bending stiffness per unit basis weight and unit thickness: B / BW / T0[(10 -4 mN×m 2 / m) / (g / m 2 The reason for evaluating the bending stiffness value B is that it tends to increase with the average basis weight of the nonwoven fabric and also tends to increase with the thickness of the nonwoven fabric.

[0194] For the nonwoven fabrics involved in this disclosure, the tensile strength: BR (N / 50mm) is divided by the average basis weight of the nonwoven fabric: BW (g / m³). 2 The calculated breaking strength per unit base weight is: BR / BW[(N / 50mm) / (g / m²)] 2 The preferred value is 0.70 or higher, more preferably 0.75 or higher, and even more preferably 0.80 or higher. Additionally, the breaking strength per unit basis weight is: BR / BW[(N / 50mm) / (g / m²)] 2 The strength is preferably 2.00 or less, more preferably 1.70 or less, and even more preferably 1.50 or less. As a result, the nonwoven fabric exhibits excellent strength.

[0195] Fracture strength: BR is determined as follows.

[0196] (1) Prepare the Autograph AG-1 manufactured by Shimadzu Corporation.

[0197] (2) Prepare five samples with a length of 150 mm in the transverse direction CD and a length of 50 mm in the transport direction MD during manufacturing.

[0198] (3) The fracture strength of CD in the transverse direction was measured with a clamping distance of 100 mm and a tensile speed of 100 mm / min.

[0199] (4) The average fracture strength of the five samples was used as the fracture strength: BR(N / 50mm). In addition, “N / 50mm” refers to the fracture strength (N) per 50mm width, and the fracture strength refers to the strength under the maximum point load.

[0200] The nonwoven fabrics disclosed herein are not particularly limited and can be used for various purposes, such as absorbent articles, such as disposable diapers, urine pads, animal urination pads, sanitary napkins, and panty liners.

[0201] In addition, the nonwoven fabrics disclosed herein can be used in the outer packaging sheets of absorbent articles and liquid-permeable sheets.

[0202] Figure 1 This is a diagram illustrating 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 D1 and a second direction D2 orthogonal to the first direction D1.

[0203] The spunbond nonwoven fabric 1 has a plurality of high-basic-weight regions 11 extending in a predetermined direction D and a plurality of low-basic-weight regions 13 extending in a predetermined direction D, wherein the plurality of high-basic-weight regions 11 and the plurality of low-basic-weight regions 13 are alternately arranged in a direction orthogonal to the predetermined direction D.

[0204] The spunbond nonwoven fabric 1 has an embossed area 3 including a plurality of embossed portions 5. The plurality of embossed portions 5 are arranged intermittently in a first direction D1 at a first interval P1, and intermittently in a second direction D2 at a second interval P2.

[0205] The plurality of embossed portions 5 can be divided into a plurality of first embossed portions 7 disposed in a plurality of high base weight regions 11 and a plurality of second embossed portions 9 disposed in a plurality of low base weight regions 13, and tends to have an area of ​​each of the plurality of first embossed portions 7 being larger than the area of ​​each of the plurality of second embossed portions 9.

[0206] By alternately arranging multiple first embossed portions 7 with large embossed areas and a large amount of bonded fibers and multiple second embossed portions 9 with small embossed areas and a small amount of bonded fibers in a direction orthogonal to the specified direction D, the small and easily deformable areas of the embossed portions are arranged at certain intervals, resulting in a nonwoven fabric that is easily deformable and has excellent softness.

[0207] Furthermore, since the embossed areas, which are large in area and have high strength, are arranged at regular intervals, the nonwoven fabric is less prone to tearing during wear when used in outer coverings of absorbent articles, resulting in a highly durable fabric. Moreover, because the embossed areas, which are large in area and have a high fiber content, are arranged continuously in a certain direction, fabric shrinkage is less likely to occur during the manufacture of absorbent articles, resulting in a strong nonwoven fabric with excellent manufacturing stability.

[0208] Spunbond nonwoven fabric 1 can be used in absorbent articles such as outer coverings for disposable diapers.

[0209] In the spunbond nonwoven fabric 1, a structure in which the fiber web 51 constituting the spunbond nonwoven fabric 1 remains in the portions that separate from the plurality of embossed portions 5. By retaining the fiber web 51 in the spunbond nonwoven fabric 1, the following effects can be obtained.

[0210] In the portions that separate from the multiple embossed portions 5, the multiple high-basicity regions 11 each have ridges 53 (see reference). Figure 2 Multiple low-basic-weight regions 13 each have a groove 55 (refer to...) Figure 2 ), and the ridges formed by multiple high-basic-weight regions 11 (refer to Figure 2 It has multiple recesses 57 (refer to) Figure 2 ).

[0211] Additionally, in the description of spunbond nonwoven fabric 1, some of the reference numerals are derived from... Figure 2 The reference numerals for the fiber web 51 are shown in the attached diagram. Additionally, the specified direction D of the spunbond nonwoven fabric 1 is... Figure 2 The first direction x is parallel.

[0212] Since the basis weight of the ridges 53 in the multiple high basis weight regions 11 is greater than that of the grooves 55 in the multiple low basis weight regions 13, the basis weight in the thickness direction z (refer to...) Figure 2 When a load is applied, the thickness of the ridge 53 is difficult to change. Thus, due to the second direction y of the ridge 53 (refer to...), Figure 2 The length of the groove 55 is also difficult to change, so the length of the groove in the second direction y is also difficult to change.

[0213] Therefore, when the spunbond nonwoven fabric 1 is used as an outer covering with the surface having multiple ridges 53 and multiple grooves 55 as the non-skin side (outer side), the multiple ridges 53 are unlikely to collapse even when subjected to prolonged load during wear. Furthermore, due to the recesses 57, the contact area of ​​the spunbond nonwoven fabric 1 is reduced, providing the user with a dry touch. In addition, since the spunbond nonwoven fabric 1 has a complex fabric-like surface shape, it can impart a fabric-like (woven fabric-like) texture to disposable diapers.

[0214] In addition, in this case, the pattern provided on the indicator section or the liquid-proof sheet can be clearly seen from the outer cover side of the disposable diaper through multiple grooves 55.

[0215] In addition, when the spunbond nonwoven fabric 1 is used as an outer sheet with the surface having multiple ridges 53 and multiple grooves 55 as the skin side (inner side), the multiple ridges 53 are difficult to collapse. Therefore, a space from the multiple grooves 55 and recesses 57 is formed between it and the liquid-impermeable sheet, so the moisture carried by the absorbent item is difficult to be transferred to clothes, sheets, etc.

[0216] In addition, in this case, the pattern provided on the indicator section or the liquid-proof sheet can be clearly seen from the outer cover side of the disposable diaper through multiple grooves 55.

[0217] Spunbond nonwoven fabric 1 can be used in absorbent articles such as liquid-permeable sheets for disposable diapers.

[0218] In the spunbond nonwoven fabric 1, in the portions that are separated from the plurality of embossed portions 5, a structure containing the fiber web 51 constituting the spunbond nonwoven fabric 1 remains. By retaining the fiber web 51 in the spunbond nonwoven fabric 1, the following effects can be obtained.

[0219] The spunbond nonwoven fabric 1 (liquid-permeable sheet) maintains the distance between the absorbent and the user's skin over a large range in the first direction x and the second direction y by alternately providing multiple ridges 53 and multiple grooves 55 in the second direction y, which is excellent in suppressing the feeling of wetness and in the visibility of the body fluid absorbed by the absorbent through the multiple grooves 55.

[0220] The spunbond nonwoven fabric 1 (liquid-permeable sheet) has multiple grooves 55 and multiple recesses 57 in the thickness direction z of multiple ridges 53 (see reference). Figure 2 Therefore, compared to spunbond nonwoven fabric 1 without recesses 57, the user's skin has less contact area with the moistened spunbond nonwoven fabric 1. In spunbond nonwoven fabric 1 (liquid-permeable sheet), the base 59 (refer to...) Figure 2 It absorbs the excreted body fluids and more reliably inhibits the return of the absorbed body fluids into the recess 57.

[0221] In the spunbond nonwoven fabric 1 (liquid-permeable sheet), the plurality of ridges 53 each have continuous fibers along the first direction x in at least a portion of the plurality of recesses 57 in the second direction y (refer to...). Figure 2 ) aligned bundle 61 (refer to Figure 2 The continuous fibers of the bundle portion 61 have small inter-fiber distances, making them difficult to deform under load. Therefore, the spunbond nonwoven fabric 1 (liquid-permeable sheet) with the bundle portion 61 easily maintains the shape of the recess with minimal thickness variation during wear. As a result, the spunbond nonwoven fabric 1 (liquid-permeable sheet) easily maintains the distance between the absorbent and the user's skin, and also easily maintains the shape of the recess 57, thus easily maintaining a small contact area with the spunbond nonwoven fabric 1 (liquid-permeable sheet).

[0222] In the spunbond nonwoven fabric 1, since the thickness of each of the multiple grooves 55 is thinner than that of the base 59, the multiple grooves 55 have excellent visibility in the thickness direction z, which is significantly different from the multiple ridges 53, which have almost no visibility in the thickness direction z. Therefore, the spunbond nonwoven fabric 1 (liquid-permeable sheet) has excellent visibility.

[0223] In the spunbond nonwoven fabric 1 (liquid-permeable sheet), the plurality of ridges 53 of the spunbond nonwoven fabric 1 each have a plurality of protrusions 63 that protrude toward a plurality of adjacent grooves 55 and are spaced apart along the first direction x (see reference). Figure 2 Therefore, when a load is applied in the thickness direction z, the multiple ridges 53 are unlikely to collapse. As a result, the liquid-permeable sheet easily maintains the shape of the multiple ridges 53, so the multiple ridges 53 are unlikely to clog the grooves 55, thus providing excellent visibility.

[0224] In the spunbond nonwoven fabric 1 (liquid-permeable sheet), the fiber orientation of the plurality of ridges 53 along the first direction x is higher than that of the plurality of grooves 55 along the first direction x, resulting in shorter distances between the intersections of continuous fibers. Therefore, the spunbond nonwoven fabric 1 easily maintains the shape of the plurality of ridges 53. Furthermore, body fluid can diffuse along the plurality of ridges 53 in the first direction x. Therefore, by allowing body fluid to diffuse in the first direction x, the liquid-permeable sheet can suppress body fluid retention in one place, thus exhibiting excellent performance in suppressing a feeling of wetness. Additionally, because the fiber orientation of the plurality of ridges 53 along the first direction x is higher, the distances between the intersections of continuous fibers and the distances between the plurality of joints are short, making it easy to maintain its shape. Therefore, the liquid-permeable sheet is difficult to deform in the thickness direction z.

[0225] When the fiber web 51 of the spunbond nonwoven fabric 1 is formed, the continuous fibers move due to the airflow. Because of their long fiber length, they move a certain distance, and adjacent continuous fibers also move accordingly. Therefore, they are easily affected by the airflow in the stacking process. As a result, by moving the continuous fibers individually, it is easy to form sections with small inter-fiber distances. The distance between the intersections of the continuous fibers is short, and the distance between multiple joints is also short. Therefore, the spunbond nonwoven fabric 1 (liquid-permeable sheet) easily maintains the shape of the multiple ridges 53.

[0226] When the spunbond nonwoven fabric 1 is subjected to a load in the thickness direction z during use, the multiple ribs 53 are difficult to collapse, and the length of the multiple grooves 55 in the second direction y is maintained with a low basis weight.

[0227] [Manufacturing methods for nonwoven fabrics]

[0228] The method for manufacturing nonwoven fabric disclosed herein has the following structure.

[0229] • The steps for preparing a fiber web with high-basicity areas and low-basicity areas (hereinafter sometimes referred to as the "fiber web preparation steps").

[0230] • The step of forming the nonwoven fabric by forming multiple embossed portions on the fiber web using a pair of embossing rollers, including an embossing roller and an anvil roller with multiple protrusions (hereinafter sometimes referred to as the "nonwoven fabric forming step").

[0231] The following is a description of a specific implementation method.

[0232] The spunbond nonwoven fabric 1 according to the first embodiment can be manufactured as follows.

[0233] [Fiber Web Preparation Steps]

[0234] The resin composition is spun from a spinning nozzle, and the spun long fibers are cooled by a cooling fluid or the like. Tension is applied to the long fibers by extending air to form continuous fibers with a specified fineness. The obtained continuous fibers are drawn from the underside of the wire mesh 101, which moves in the transport direction MD, and are piled on the wire mesh 101 to form a fiber web 51.

[0235] A three-dimensional illustration of the formed fiber web 51 is shown in Figure 2 , Figure 2 The cross-section in the y direction is shown in Figure 3 Additionally, a three-dimensional illustration of the screen 101 is schematically shown in [the image / description]. Figure 4 The end face of the screen 101 in the transverse direction CD is shown in the figure. Figure 5 .

[0236] like Figure 2 As shown, the fiber web 51 has mutually orthogonal first direction x, second direction y, and thickness direction z, and is composed of continuous fibers. Therefore, it is difficult for the ends of continuous fibers to exist on the surface of the fiber web 51, and consequently the spunbond nonwoven fabric 1, resulting in excellent wearability.

[0237] The fiber web 51 has multiple ridges 53 and multiple grooves 55. The multiple ridges 53 and multiple grooves 55 are disposed on one side of the fiber web 51 in the thickness direction z. Figure 2 The ridges 53 are located on the upper surface. Multiple ridges 53 protrude from one side of the fiber web 51 in the thickness direction z and extend along the first direction x. Multiple grooves 55 extend along the first direction x and have a lower basis weight than the multiple ridges 53. The multiple ridges 53 and the multiple grooves 55 are alternately arranged in the second direction y. The multiple ridges 53 are arranged at predetermined intervals in the second direction y.

[0238] Each of the multiple ridges 53 has a greater amount of continuous fibers than each of the multiple grooves 55, and is thicker than each of the multiple grooves 55. That is, each of the multiple grooves 55 is thinner than each of the multiple ridges 53. The multiple ridges 53 and the multiple grooves 55 are connected by a non-steep surface. Figure 3 As shown, the multiple ridges 53 and multiple grooves 55 are 50% of the thickness Tn of the fiber web 51 under no-load conditions. 50As boundaries, regions with a thickness of 50% or more of the thickness Tn are designated as ridges 53, and regions with a thickness of less than 50% of the thickness Tn are designated as grooves 55.

[0239] Preferably, the fiber orientation of the plurality of ridges 53 along the first direction x is higher than that of the plurality of grooves 55 along the first direction x. By making the fiber orientation of the plurality of ridges 53 along the first direction x higher, the distance between the intersection points of the continuous fibers is shorter, and the distance between the plurality of joints is shorter, thus making it easier to maintain the shape of the fiber web 51, and thus the spunbond nonwoven fabric 1. Fiber orientation is a concept composed of the fiber orientation angle and orientation strength, and can be determined, for example, by the following methods.

[0240] The fiber web 51 or nonwoven fabric 1 is placed statically with the surface having multiple ridges 53 and multiple grooves 55 on the upper side. Using a microscope (e.g., a scanning electron microscope such as the JCM-5100 manufactured by Nippon Electron Ltd.), a magnified image is taken from a direction perpendicular to the measurement surface of the fiber web 51 or nonwoven fabric 1, and then printed to trace the fibers onto a transparent PET sheet. The magnified image is an image magnified to a level that allows measurement of 10 or more fibers, for example, a magnification of 50 to 300 times. The image is input into a personal computer, and the image is binarized using Nexus New Qube (standalone version) image processing software manufactured by NEXUS Ltd. Using Fiber OrientationAnalysis 8.13 Single, a fiber orientation analysis program, the orientation angle and orientation intensity are obtained from the binarized image. The orientation angle is the angle with the most fiber orientation, and the orientation intensity is the intensity at that orientation angle. Measurements are repeated several times (e.g., 3 to 5 times), and the average value is calculated.

[0241] Each of the multiple ridges 53 has a multiple recesses 57. Each recess 57 is an elongated shape, longer in the first direction x than in the second direction y, and is arranged at intervals in the first direction x. Each of the multiple recesses 57 is recessed in the thickness direction z, and has a base 59 at its bottom. The base 59 is composed of continuous fibers. The base 59 has less continuous fiber content than the portion of the multiple ridges 53 excluding the base 59. The thickness Tb of the base 59 is thicker than the thickness Tc of each of the multiple grooves 55. That is, the thickness Tc of each of the multiple grooves 55 is thinner than the thickness Tb of the base 59.

[0242] Multiple ridges 53 have bundles 61 on one side of the second direction y in at least a portion of the recess 57. The bundles 61 have multiple continuous fibers aligned in the first direction x. Compared to the case where the continuous fibers are not aligned in a specific direction, the interfiber distance between the continuous fibers in the bundles 61 is small. That is, because the continuous fibers between the joints in the bundles 61 are aligned in the first direction x, the interfiber distance between the continuous fibers between the joints is small. Therefore, in the fiber web 51, and further in the spunbond nonwoven fabric 1, the probability of the continuous fibers in the bundles 61 making line contact with each other is high when a load in the thickness direction z is applied, thus making it difficult to deform in the thickness direction z. The bundles 61 may also be formed on both sides of the recess 57 in the second direction y.

[0243] On the other hand, in the case of continuous fibers that are not aligned in a specific direction, the continuous fibers between the joints are oriented in an unspecified direction. Therefore, when a load is applied in the thickness direction z, the fibers are likely to make point contact with each other, and the fibers in the non-contacting areas are prone to deformation.

[0244] The thickness of the fiber web 51 and the spunbond nonwoven fabric 1 under no-load conditions, the thickness of the multiple grooves 55, and the thickness of the base 59 can be measured using a two-dimensional laser displacement meter. For example, a high-precision two-dimensional laser displacement meter from the LJ-G series (model: LJ-G030) manufactured by KEYENCE Corporation can be used. The fiber web 51 is placed on a horizontal measuring stage, and the displacement from the measuring stage is measured at five different locations for each target part of the fiber web 51 using the laser displacement meter. The average of the five measurements is taken as the thickness (mm) of each target part of the fiber web 51.

[0245] Each of the multiple ridges 53 may also have multiple protrusions 63 protruding toward adjacent multiple grooves 55. The multiple protrusions 63 protrude in the second direction y and are arranged at intervals along the first direction x. The protrusions 63 of each of the multiple ridges 53 are recessed in the second direction y. The multiple protrusions 63 are respectively provided on both sides of the multiple ridges 53, and each protrusion 63 may also be provided in a position where they overlap along the second direction y. When the protrusions 63 are provided in a position where they overlap along the second direction y, the multiple ridges 53 and the multiple grooves 55 each have a wider portion and a narrower portion. Alternatively, the protrusions 63 may also be provided in a position where they do not overlap along the second direction y. When the protrusions 63 are provided in a position where they do not overlap along the second direction y, the multiple ridges 53 and the multiple grooves 55 each have a substantially constant width.

[0246] The thickness Tc of each of the multiple grooves 55 is thinner than the thickness Tb of the base 59 because the amount of continuous fibers is small. Therefore, there is less overlap between the continuous fibers in the thickness direction z. That is, the spacing between the continuous fibers of the multiple grooves 55 is larger. As a result, the fiber web 51 can be seen from one side to the other in the thickness direction z through the spacing between the continuous fibers at the multiple grooves 55, which means it has excellent visibility.

[0247] Visibility can also be evaluated based on the average transmittance obtained using the method described below. First, prepare five 100mm × 100mm samples. Arrange the samples on black paper with the textured side facing up. Use a 12-megapixel digital camera to photograph the entire sample from a height of approximately 15cm. Input the resulting image into a KEYENCE VHX-7000 camera, automatically measure the area, set the extraction method to brightness (standard), and perform image processing using the settings described below to calculate the transmittance. The average transmittance of the five samples is then taken as the average transmittance of the nonwoven fabric.

[0248] Measurement area 50mm×50mm

[0249] Filter settings: Texture removal 10

[0250] Uneven brightness removal 1

[0251] Extract and set brightness from 0 to 148.

[0252] Filling holes OFF

[0253] Small particles remove OFF

[0254] Automatic shaping and filling settings

[0255] like Figure 4 As shown, the wire mesh 101 used to form the fiber web 51 has mutually orthogonal transport direction MD, transverse direction CD, and height direction H, and includes a web body 105 composed of a plurality of wires 103 arranged in a mesh pattern. Each of the plurality of wires 103 has a predetermined outer diameter. The web body 105 arranges the plurality of wires 103 as longitudinal and transverse lines, so that they cross each other one by one at a certain interval.

[0256] The wire mesh 101 has a plurality of protrusions 107 that protrude from one side of the mesh body 105 in the height direction H and extend along the conveying direction MD. The protrusions 107 are arranged at predetermined intervals in the transverse direction CD. The protrusions 107 block part of the gaps formed between the wires 103 in the mesh body 105. In addition, the plurality of protrusions 107 extending along the conveying direction MD are sometimes collectively referred to as protrusions 107 arranged in a stripe pattern.

[0257] like Figure 5 As shown, the height H of the protrusion 107 L It can also be 1.0 mm or more. Preferably, the height H of the protrusion 107 is... L It is larger than the outer diameter of wire 103, that is, the outer diameter of wire 103 is larger than the height H of the protrusion 107. L Small. The width W of each of the multiple protrusions 107. L That is, the total length across the transverse direction CD can also be less than 50% of the transverse direction CD length of the main body 105. The width W of each protrusion 107... L It is not limited to a specific occasion, but also includes a number of different occasions. The width W of each protrusion 107 L Alternatively, the average value of multiple locations (e.g., 5 locations) can be measured at specified intervals (e.g., 100 mm) along the conveying direction MD. The width W of the protrusion 107... L Let CD be the length of the part that connects to the main body of the net in the transverse direction.

[0258] If a wire mesh 101 is used, continuous fibers are attracted from the underside of the wire mesh 101 and accumulate on it. A portion of the continuous fibers preferentially aggregates between the protrusions 107 of the web body 105 that do not form protrusions 107. By preferentially aggregating a portion of the continuous fibers between the protrusions 107, the continuous fibers become denser, forming a plurality of ridges 53 of the fiber web 51. Additionally, the continuous fibers become sparser on the protrusions 107, forming a plurality of grooves 55 of the fiber web 51.

[0259] If the height of the protrusion 107 is 1.0 mm or more, it is difficult for continuous fibers to remain on the protrusion 107. The continuous fibers aggregate between each other on the protrusion 107, thus easily forming multiple ridges 53 with a specified thickness. Since the continuous fibers aggregate between each other along the protrusion 107 in a manner that avoids the protrusion 107, the fiber orientation of the multiple ridges 53 along the first direction x is higher than that of the multiple grooves 55 along the first direction x.

[0260] If the total length of the transverse direction CD of each of the multiple protrusions 107 is less than 50% of the transverse direction CD of the net body 105, then sufficient air permeability allows gas to easily pass through the net body 105 except for the protrusions 107.

[0261] If the outer diameter of the wires 103 forming the mesh 101 is smaller than the height of the ribs 107, then the ribs 107 will also be higher than the wires 103 at the overlapping portions of the wires 103 in the mesh 101, making it easier to form multiple grooves 55. In addition, since the overlapping portions of the wires 103 in the mesh 101 are smaller than the ribs 107, continuous fibers are difficult to accumulate at the overlapping portions of the wires 103 in the mesh 101 and gather in the mesh, thereby easily forming multiple ridges 53 with recesses 57.

[0262] Furthermore, when the continuous fibers are stacked on the protrusions 107 on the wire mesh 101, they avoid the portions of the wires 103 that overlap and protrude upwards in the height direction, thus concentrating in the mesh and forming a state in which multiple continuous fibers are more aligned in the first direction x. By forming a joint in this state, a bundle-like portion of multiple continuous fibers aligned in the transport direction MD, i.e., the first direction x, is formed.

[0263] The continuous fibers are preferably deposited onto the wire mesh 101 at a fiber speed of 1000 m / min or more and 4500 m / min or less. Because the continuous fibers have a fiber speed of 1000 m / min or more, they are easily deposited onto the wire mesh 101, easily forming multiple ridges 53. Furthermore, because the continuous fibers have a fiber speed of 4500 m / min or less, the disorder of the continuous fiber orientation on the wire mesh 101 can be suppressed, thus easily forming multiple ridges 53. Therefore, by setting the continuous fibers within the above range, a fiber web 51 having multiple ridges 53 and multiple grooves 55 can be efficiently manufactured.

[0264] Furthermore, the "fiber web preparation step" in the nonwoven fabric manufacturing method disclosed herein is not limited to... Figures 2-5 The specific embodiments disclosed also include known methods for forming fiber webs having high basis weight regions and low basis weight regions.

[0265] [Nonwoven Fabric Formation Steps]

[0266] Figure 6 An example of an embossing roller among a pair of embossing rollers used in the nonwoven fabric forming step is shown, specifically the arrangement of compression portions at the ends of the plurality of protrusions 111 of the embossing roller.

[0267] Figure 6 The embossing roller 109 shown has a plurality of protrusions 111. The embossing roller 109 has a first protrusion direction D1' corresponding to the first direction D1 of the spunbond nonwoven fabric 1 and a second protrusion direction D2' corresponding to the second direction D2 of the spunbond nonwoven fabric 1.

[0268] In addition, the intersection angle between the conveying direction MD and the direction of the first protrusion D1' is 15°, and the intersection angle between the direction of the first protrusion D1' and the direction of the second protrusion D2' is 90°.

[0269] Multiple protrusions 111 are arranged intermittently in the first protrusion direction D1' with a first protrusion spacing P1', and in the second protrusion direction D2' with a second protrusion spacing P2'. In other words, the multiple protrusions 111 are arranged in an alternating manner.

[0270] In addition, the diameter of the compression portion of each of the multiple protrusions 111 is 0.8 mm, and the compression area of ​​the compression portion is approximately 0.50 mm². 2 In addition, the distance between the first protrusion P1' and the distance between the second protrusion P2' are both 2.9 mm.

[0271] Alternatively, an embossing roller 109 with multiple protrusions 111 can be positioned on the side of the web 101 (i.e., the side of the fiber web 51 with multiple ridges 53 and multiple grooves 55), and an anvil roller (not shown) can be positioned on the side opposite to the web 101 (i.e., the side of the fiber web 51 opposite to the side with multiple ridges 53 and multiple grooves 55). As a result, the spunbond nonwoven fabric 1 easily maintains its volume, and the spunbond nonwoven fabric 1 exhibits excellent softness.

[0272] Alternatively, the anvil roller (not shown) can be positioned on the side of the wire mesh 101 (i.e., the side of the fiber web 51 where multiple ridges 53 and multiple grooves 55 are formed), and the embossing roller 109, which has multiple protrusions 111, can be positioned on the side opposite to the wire mesh 101 (i.e., the side of the fiber web 51 opposite to the side where multiple ridges 53 and multiple grooves 55 are formed). This facilitates heat transfer from the multiple protrusions 111 of the embossing roller 109 to the fiber web 51, increases the fusion amount of the heat-fusible fibers at the multiple embossed portions 5, and results in excellent strength of the spunbond nonwoven fabric 1.

[0273] in addition, Figure 6 The pair of embossing rollers shown is an example, and structures known in the art can be used in the nonwoven fabric forming step.

[0274] In the nonwoven fabric manufacturing method disclosed herein, the compression area of ​​the compression fiber web constituting the plurality of protrusions of a pair of embossing rollers can be the same or different.

[0275] In cases where multiple protrusions have the same compression area, in order to satisfy the necessary conditions of equations (1) to (6) for multiple embossed parts, the nonwoven fabric (fiber web) preferably has a high basis weight region and a low basis weight region.

[0276] In cases where multiple protrusions have different compression areas, the nonwoven fabric (fiber web) can have both high-basic-weight regions and low-basic-weight regions, or it can not have both high-basic-weight regions and low-basic-weight regions. This is because, even when the nonwoven fabric (fiber web) does not have high-basic-weight regions and low-basic-weight regions, multiple embossed sections can still satisfy the necessary conditions of equations (1) to (6).

[0277] Example

[0278] The following examples illustrate this disclosure, but this disclosure is not limited to these examples.

[0279] [Manufacturing Example 1]

[0280] use Figure 4 as well as Figure 5 The wire mesh 101 shown has striped ribs 107 arranged in a striped pattern. L (1.8mm diameter, spacing of ribs 107: 4.0mm), forming fiber web No. 1. The average basis weight of fiber web No. 1 is 13g / m². 2 .

[0281] For fiber web No.1, use Figure 6 The pair of embossing rollers shown form multiple embossed portions 111 arranged in a staggered pattern, thus forming spunbond nonwoven fabric No. 1. Additionally, an anvil roller is positioned on the side of the web 101, and an embossing roller 109, also having multiple protrusions 111, is positioned on the side opposite to the web 101. The average basis weight (BW) of spunbond nonwoven fabric No. 1 is 13 g / m³. 2 .

[0282] [Manufacturing Examples 2 and 3]

[0283] Except for changing the average basis weight (BW) as shown in Table 1, spunbond nonwoven fabrics No. 2 and No. 3 are formed in the same manner as in Manufacturing Example 1. An image of spunbond nonwoven fabric No. 3 is shown in... Figure 8 As shown in the image.

[0284] [Manufacturing Example 4]

[0285] Except for changing the spacing of the protrusions 107 in the screen 101 from "4.0 mm" to "5.0 mm" and setting the average basis weight (BW) as shown in Table 1, spunbond nonwoven fabric No. 4 is formed according to manufacturing example 1.

[0286] [Manufacturing Example 5]

[0287] In addition to changing screen 101 to Figure 7 Apart from the screen 101 shown, spunbond nonwoven fabric No. 5 is formed in the same manner as in manufacturing example 1.

[0288] in addition, Figure 7 This is a view of the wire mesh 101 from the height direction H, showing only the protrusions 107 and omitting the wires.

[0289] exist Figure 7 In the screen 101 shown, the protrusions 107 each have a dot-shaped (approximately circular) shape with a diameter of about 3.0 mm. The protrusions 107 are arranged in an alternating manner with a spacing of 8.0 mm between the protrusions 107 in the conveying direction MD and a spacing of 6.0 mm between the protrusions 107 in the transverse direction CD.

[0290] [Manufacturing Examples 6 and 7]

[0291] Will Figure 7 The ribs 107 of the mesh 101 shown are set to a diameter of 5.0 mm. The spacing of the ribs 107 in the conveying direction MD is set to 10.0 mm. The spacing of the ribs 107 in the transverse direction CD is set to 10.0 mm. The average basis weight: BW is set as shown in Table 1. Except for the above configuration, the spunbond nonwoven fabrics No. 6 and No. 7 are formed in the same way as in manufacturing example 5.

[0292] [Comparative Manufacturing Example 1]

[0293] Except for the absence of protrusions 107 on the wire mesh 101, spunbond nonwoven fabric No. 8 is formed in the same manner as in manufacturing example 1.

[0294] [Comparative Manufacturing Examples 2-8]

[0295] These constitute commercially available spunbond nonwoven fabrics, forming spunbond nonwoven fabrics No. 9 to No. 15.

[0296] [Examples 1-7 and Comparative Examples 1-8]

[0297] Regarding spunbond nonwoven fabrics No. 1 to No. 15, the S content was measured according to the method described in this instruction manual. AVE (mm 2 ), S MAX (mm 2 ), S MIN (mm 2 ), (S MAX -S MIN ) / S AVE S MAX / S AVE S MIN / SAVE And CV (%). These values ​​are shown in Table 1.

[0298] In addition, the following characteristic values ​​were measured for spunbond nonwoven fabrics No.1 to No.15.

[0299] [Compression characteristics per unit weight]

[0300] Table 1 shows the initial thickness T0 (mm) and the thickness at compression T0 (mm) measured according to the method described in this specification. m (mm) and "T0-T" m (mm), and compressibility per unit weight: (T0-T) m ) / BW[mm / (g / m 2 ], and in Figure 9 In, it is shown that (S) MAX -S MIN ) / S AVE With (T0-T) m The relationship between ) / BW. Additionally, Figure 9 In this context, "EX" refers to data related to spunbond nonwoven fabrics No.1 to No.7 (Examples), and "COM" refers to data related to spunbond nonwoven fabrics No.8 to No.15 (Comparative Examples).

[0301] [Bending stiffness per unit weight and unit thickness]

[0302] Table 1 shows the bending stiffness values ​​measured according to the method described in this specification: B(10 -4 mN×m 2 / m) and bending stiffness per unit base weight and unit thickness: B / BW / T0[(10 -4 mN×m 2 / m) / (g / m 2 ) / mm]. Additionally, in Figure 10 In, it is shown that (S) MAX -S MIN ) / S AVE The relationship with B / BW / T0. Additionally... Figure 10 In this context, "EX" refers to data related to spunbond nonwoven fabrics No.1 to No.7 (Examples), and "COM" refers to data related to spunbond nonwoven fabrics No.8 to No.15 (Comparative Examples).

[0303] [Tear strength per unit weight]

[0304] Table 1 shows the breaking strength BR (N / 50mm) and breaking strength per unit basis weight, measured according to the method described in this specification: BR / BW [(N / 50mm) / (g / m²)]. 2 )],exist Figure 11 In, it is shown that (S) MAX -S MIN ) / S AVE Tensile strength per unit basis weight: BR / BW [(N / 50mm) / (g / m)] 2 The relationship between )] . Additionally, Figure 11In this context, "EX" refers to data related to spunbond nonwoven fabrics No.1 to No.7 (Examples), and "COM" refers to data related to spunbond nonwoven fabrics No.8 to No.15 (Comparative Examples).

[0305] Table 1

[0306]

[0307] Based on the data on compressibility per unit weight (Table 1 and...) Figure 9 It can be seen that, compared with spunbond nonwoven fabrics No. 8 to No. 15, spunbond nonwoven fabrics No. 1 to No. 7 have greater compression characteristics per unit weight. That is, for each unit weight, the initial thickness (T0) of the nonwoven fabric is greater than the thickness (T) during compression. m The difference in thickness is large, therefore, when users come into contact with nonwoven fabric, the nonwoven fabric is easy to deform in the thickness direction, and it is excellent in terms of softness.

[0308] According to data from B / BW / T0 (Table 1 and...) Figure 10 It can be seen that, compared with spunbond nonwoven fabrics No.8 to No.15, spunbond nonwoven fabrics No.1 to No.7 have lower bending stiffness per unit basis weight and per unit thickness, making them easier to deform when force is applied, and they are superior in terms of softness.

[0309] Based on the data on the breaking strength per unit weight (Table 1 and...) Figure 11 It can be seen that spunbond nonwoven fabrics No.1 to No.7 have a breaking strength of the same or higher than that of spunbond nonwoven fabrics No.8 to No.15.

[0310] Explanation of reference numerals in the attached figures

[0311] 1. Spunbond nonwoven fabric

[0312] 3 Embossed area

[0313] 5 Embossed section

[0314] 7. Embossing Part 1

[0315] 9. Second Embossed Section

[0316] 11 High-basic-weight areas

[0317] 13 Low basis weight regions

[0318] 51 Fiber Web

[0319] 53 ridge part

[0320] 55 Groove

[0321] 57 recess

[0322] 59 Base

[0323] 61. Bundle-shaped portion

[0324] 63. Protrusion

[0325] PD planar direction

[0326] D1 Direction 1

[0327] D2, direction 2

[0328] P1 First Spacing

[0329] P2 second spacing

Claims

1. A nonwoven fabric comprising an embossed area including a plurality of embossed portions regularly arranged in a planar direction, characterized in that, Let the maximum area of ​​each of the above embossed sections be S. MAX Let the minimum area of ​​each of the above embossed parts be S. MIN Let S be the average area of ​​each of the above embossed parts. AVE In this case, the plurality of embossed portions in the embossed area satisfy the following equation (1): 0.94≤(S MAX -S MIN ) / S AVE ≤2.00 Equation (1), In the aforementioned embossed area, the nonwoven fabric includes a high-basis-weight region having a basis weight higher than the average basis weight of the nonwoven fabric and a low-basis-weight region having a basis weight lower than the average basis weight. Let the average area of ​​each of the plurality of embossed portions in the aforementioned low basis weight region be SL. AVE In the case of embossing, the above-mentioned multiple embossed parts in the embossed area satisfy the following equation (5): SL AVE <S AVE Equation (5).

2. The nonwoven fabric as described in claim 1, characterized in that, The aforementioned nonwoven fabric is used as an outer packaging sheet or liquid-permeable sheet for absorbent articles.

3. The nonwoven fabric as described in claim 1 or 2, characterized in that, When the variation coefficient of the area of ​​each of the above-mentioned embossed parts is set to CV, the above-mentioned embossed parts in the above-mentioned embossed region satisfy the following equation (2): 10≤CV≤70 Equation (2).

4. The nonwoven fabric as described in claim 1 or 2, characterized in that, The aforementioned embossed portions in the embossed area satisfy the following equation (3): 0.09≤S MIN / S AVE Equation (3).

5. The nonwoven fabric as described in claim 1 or 2, characterized in that, Let N be the number of the aforementioned embossed parts, and let S be one of the aforementioned embossed parts. AVE The number of embossed portions covering 80% to 120% of the area is set as N1. In this case, the plurality of embossed portions in the embossed area satisfy the following equation (4): 0.26≤N1 / N≤0.90 Equation (4).

6. The nonwoven fabric as described in claim 1, characterized in that, Let the average area of ​​each of the aforementioned embossed portions in the high-basicity region be SH. AVE In the case of embossing, the above-mentioned multiple embossed parts in the above-mentioned embossed area satisfy the following equation (6): S AVE <SH AVE Equation (6).

7. The nonwoven fabric as described in claim 1, characterized in that, The aforementioned nonwoven fabric is composed of continuous fibers.

8. The nonwoven fabric as described in claim 7, characterized in that, In the aforementioned embossed area, the aforementioned high-basic-weight area and the aforementioned low-basic-weight area are respectively composed of a ridge protruding in one direction toward the thickness direction of the nonwoven fabric and a groove protruding in one direction. The aforementioned ridge also has a plurality of recesses that are concave toward the aforementioned side, and each of the plurality of recesses has a base made of the aforementioned continuous fibers at its bottom.

9. The nonwoven fabric as described in claim 1 or 2, characterized in that, The aforementioned planar directions include the first direction and the second direction intersecting the first direction. The aforementioned plurality of embossed portions are arranged intermittently at a first spacing in the first direction and intermittently at a second spacing in the second direction.

10. The nonwoven fabric as described in claim 9, characterized in that, The intersection angle between the first and second directions is 60° to 90°.

11. The nonwoven fabric as described in claim 9, characterized in that, The first spacing is the same as the second spacing.

12. A method for manufacturing a nonwoven fabric, wherein the method manufactures the nonwoven fabric according to any one of claims 1, 6 to 8, characterized in that, The above-mentioned method for manufacturing nonwoven fabric includes: The steps of preparing a fiber web having the aforementioned high basicity region and the aforementioned low basicity region; and The step of forming the nonwoven fabric by using a pair of embossing rollers, each having multiple protrusions, to form the multiple embossed portions on the fiber web. The aforementioned protrusions each have the same compression area.

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