Spunbonded nonwoven fabric and sanitary material

Abstract

The present invention provides a spunbond nonwoven fabric comprising a fiber composed of a resin composition containing a propylene-based polymer (A) and a polymer (B) selected from at least one of the group consisting of a polyolefin (excluding the propylene-based polymer (A)) and a polyester. The fiber has an island-in-sea structure. The fiber contains, in the island phase in a cross section orthogonal to the axial direction of the fiber, an island phase having a diameter of less than 0.32 μm at a ratio of 60% or more in number on a number basis. The spunbond nonwoven fabric has a tensile strength (S MD ) in the mechanical running direction (MD) of the fabric of 0.5 to 2.0 N / tex and a tensile strength (S CD ) in the direction (CD) orthogonal to the mechanical running direction (MD) of the fabric of 0.1 to 0.5 N / tex, and the ratio (S MD / S CD ) of the tensile strength (S MD ) in the mechanical running direction (MD) to the tensile strength (S CD ) in the direction (CD) is 2.0 to 5.1.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a spunbond nonwoven fabric and a sanitary material. BACKGROUND

[0002] In recent years, nonwoven fabrics have been widely used for various uses because of excellent air permeability and softness. As representative uses of nonwoven fabrics, for example, there can be mentioned absorbent articles such as paper diapers, sanitary napkins for physiological use, and the like, sanitary masks, medical gauze, and base fabrics for wet compress materials.

[0003] For such nonwoven fabrics, from the viewpoint of ease of secondary processing, it is required to have elongation and the like according to the site to be used.

[0004] Patent Literature 1 discloses a spunbond nonwoven fabric having excellent heat sealability at low temperatures and stretch processing adaptability. The spunbond nonwoven fabric disclosed in Patent Literature 1 is composed of a specific composition. The specific composition contains a propylene homopolymer having a melting point of 140°C or higher, polyethylene, and at least one selected from a first polymer and a second polymer. The first polymer is a random copolymer of propylene and at least one selected from ethylene and an a-olefin having a carbon number of 4 to 20. The second polymer is a specific propylene homopolymer having a melting point of less than 120°C. The total content of the first polymer and the second polymer in the composition is within a specific range.

[0005] Patent Literature 1: International Publication No. 2017 / 006972 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] The nonwoven fabric described in Patent Literature 1 has excellent heat sealability at low temperatures, but sometimes it is required to further improve the elongation. The elongated nonwoven fabric in which the elongation is required has softness in most cases when used as a nonwoven fabric or is subjected to a stretching process to perform desired shaping. However, with such a stretching process, depending on the properties of the nonwoven fabric to be stretched, sometimes a break occurs, and thus desired processing cannot be performed. That is, sometimes it cannot be said that the stretch processing adaptability of the nonwoven fabric as a stretching object is sufficient. In order to provide a spunbond nonwoven fabric having excellent quality and cost balance, it is required to further improve the spinnability of the nonwoven fabric described in Patent Literature 1.

[0008] In view of the above, an object of the present disclosure is to provide a spunbond nonwoven fabric and a sanitary material having excellent elongation and spinnability.

[0009] METHOD FOR SOLVING THE PROBLEMS

[0010] The method for solving the above problems includes the following embodiments.

[0011] A spun-bond nonwoven fabric comprising a fiber composed of a resin composition containing a propylene-based polymer (A) and a polymer (B) that is at least one selected from the group consisting of a polyolefin (excluding the propylene-based polymer (A)) and a polyester,

[0012] The fiber has an island-in-sea structure,

[0013] The fiber contains, in the island phase in a cross section orthogonal to the axial direction of the fiber, an island phase having a diameter of less than 0.32 μm at a ratio of 60% or more in number based on the number of fibers,

[0014] The ratio (S MD / S CD ) of the tensile strength (S MD ) in the machine direction (MD) to the tensile strength (S CD ) in the direction (CD) orthogonal to the machine direction (MD) is 2.0 to 5.1.

[0015] <2> The spun-bond nonwoven fabric according to <1> above, wherein the propylene-based polymer (A) comprises a propylene homopolymer.

[0016] <3> The spun-bond nonwoven fabric according to <1> or <2> above, wherein the polymer (B) comprises a homopolymer of an α-olefin having 2 to 8 carbon atoms (excluding the propylene-based polymer (A)).

[0017] <4> The spun-bond nonwoven fabric according to any one of <1> to <3> above, wherein the polymer (B) comprises a polyethylene.

[0018] <5> The spun-bond nonwoven fabric according to <4> above, wherein the polyethylene has a density of 0.94 g / cm 3 to 0.97 g / cm 3 .

[0019] <6> The spun-bond nonwoven fabric according to any one of <1> to <5> above, wherein the sea phase of the island-in-sea structure comprises the propylene-based polymer (A),

[0020] the island phase comprises the polymer (B).

[0021] <7> The spun-bond nonwoven fabric according to any one of <1> to <6> above, wherein the ratio (S MD / S CD ) is 2.5 to 5.1.

[0022] <8> The spun-bond nonwoven fabric according to any one of <1> to <7> above, wherein the content of the propylene-based polymer (A) is 85.0 mass% to 95.0 mass% relative to the total amount of the resin composition.

[0023] <9> The spunbonded nonwoven fabric according to any one of <1> to <8> above, wherein the content of the polymer (B) is 1.0% by mass to 10.0% by mass based on the total amount of the resin composition.

[0024] <10> The spunbonded nonwoven fabric according to any one of <1> to <9> above, wherein the resin composition contains a low molecular weight olefin polymer having a weight average molecular weight of 500 to 30,000,

[0025] The content of the low-molecular-weight olefin polymer is 0.1% by mass to 5.0% by mass relative to the total amount of the resin composition.

[0026] <11> The spunbonded nonwoven fabric according to any one of <1> to <10> above, comprising thermoplastic elastomer fibers and being a laminated nonwoven fabric or a mixed fiber nonwoven fabric.

[0027] The laminated nonwoven fabric is formed by combining a spunbond web containing the above-mentioned fibers and a resin layer containing the above-mentioned thermoplastic elastomer fibers laminated on at least one main surface of the spunbond web.

[0028] The blended fiber nonwoven fabric is formed by blending the above fibers and the above thermoplastic elastomer fibers.

[0029] <12> The spunbonded nonwoven fabric according to <11>, wherein the thermoplastic elastomer fiber is a polyurethane-based thermoplastic elastomer fiber or an olefin-based thermoplastic elastomer fiber.

[0030] <13> A sanitary material comprising the spunbonded nonwoven fabric according to any one of <1> to <12> above.

[0031] Effects of the Invention

[0032] According to the present invention, a spunbonded nonwoven fabric and a sanitary material having excellent extensibility and spinnability are provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] [ Figure 1 ] is a schematic diagram showing an example of a manufacturing apparatus for a closed spunbond method.

[0034] [ Figure 2 ] is a transmission electron microscope photograph (photographing magnification: 6000 times) obtained by photographing a cross section of the fibers in the spunbond nonwoven fabric of Example 1.

[0035] [ Figure 3 ] is a transmission electron microscope photograph (photographing magnification: 6000 times) obtained by photographing a cross section of the fibers in the spunbond nonwoven fabric of Comparative Example 1. DETAILED DESCRIPTION

[0036] Hereinafter, the contents of the present application will be described in detail. The description of the constitutional elements described below is sometimes based on representative embodiments of the present application, but the present disclosure is not limited to such embodiments.

[0037] In the present disclosure, the term "step" includes not only an independent step, but also a case where the step cannot be clearly distinguished from other steps, as long as the purpose of the step can be achieved.

[0038] In the present disclosure, regarding the content of each component in the thermoplastic resin composition, in the case where a plurality of substances corresponding to each component is present in the thermoplastic resin composition, the meaning is the total amount of the plurality of substances present in the thermoplastic resin composition, unless otherwise specified.

[0039] In the present disclosure, the meaning of the numerical range represented by "~" is the range including the numerical values recited before and after "~" as the lower limit value and the upper limit value.

[0040] In the present disclosure, in the numerical range recited in stages in the "DETAILED DESCRIPTION", the upper limit value or the lower limit value recited in one numerical range can be replaced with the upper limit value or the lower limit value of the other numerical range recited in stages. In the present disclosure, in the numerical range recited in the "DETAILED DESCRIPTION", the upper limit value or the lower limit value of the numerical range can be replaced with the value shown in the "EMBODIMENTS".

[0041] In the present disclosure, a combination of two or more preferred modes is a more preferred mode.

[0042] (1) Spun-bonded nonwoven fabric

[0043] The spun-bonded nonwoven fabric of the present disclosure contains a fiber composed of a resin composition containing a propylene-based polymer (A) and a polymer (B),

[0044] The above polymer (B) is at least one selected from the group consisting of a polyolefin (excluding the propylene-based polymer (A)) and a polyester,

[0045] The above fiber has an island-in-sea structure,

[0046] The above fiber contains a fiber in which the proportion of island phases having a diameter of less than 0.32 μm in the island phases in a cross section orthogonal to the axial direction of the above fiber is 60 or more in number on a number basis,

[0047] The ratio (S) of the tensile strength (S MD ) in the machine direction (MD) to the tensile strength (S CD ) in the cross machine direction (CD) orthogonal to the above machine direction (MD) is 0.8 or more.MD / S CD ) is 2.0 to 5.1.

[0048] In the present disclosure, "spunbond nonwoven fabric" means a nonwoven fabric produced by layering continuous fibers (filaments) spun from a spinneret on a moving capturing member (for example, a mesh conveyor) using melting or dissolution of a thermoplastic resin composition, and using one or two or more bonding methods.

[0049] In the present disclosure, "island-in-sea structure" means a phase separation structure in which a phase (island phase) containing one of at least two components exists (for example, is dispersed) in a continuous phase (sea phase) composed of the other component.

[0050] In the present disclosure, "the fiber has an island-in-sea structure" means that the cross section of the fiber cut in a direction orthogonal to the axial direction of the fiber is an island-in-sea structure.

[0051] In the present disclosure, "machine running direction (MD)" means a direction parallel to the advancing direction of the moving capturing member.

[0052] In the present disclosure, "direction orthogonal to the machine running direction (MD) (CD)" means a direction orthogonal to the advancing direction of the moving capturing member in the face direction of the moving capturing member.

[0053] Hereinafter, the "fiber having an island-in-sea structure" is sometimes referred to as "island-in-sea fiber".

[0054] Hereinafter, the "proportion of the island phase having a diameter of less than 0.32 μm in the island phase in the cross section orthogonal to the axial direction of the fiber" is sometimes referred to as "island phase proportion".

[0055] Hereinafter, the "machine running direction (MD)" is referred to as "running direction (MD)", and the "direction orthogonal to the machine running direction (MD) (CD)" is referred to as "cross direction (CD)".

[0056] Hereinafter, the "ratio of the tensile strength (S MD ) in the machine running direction (MD) to the tensile strength (S CD ) in the direction orthogonal to the machine running direction (MD) (CD)" is sometimes referred to as "tensile strength ratio (S MD / S CD )". MD CD

[0057] The spunbond nonwoven fabric of the present disclosure has the above-described configuration, and thus is excellent in elongation and spinnability.

[0058] ​​"excellent elongation" means that the spunbond nonwoven fabric has the first property and the second property. The "first property" means a property that the shape of the spunbond nonwoven fabric is elongated in one direction when an external force is applied to the spunbond nonwoven fabric. The "second property" means a property that the shape of the spunbond nonwoven fabric is not easily restored even if the external force applied to the spunbond nonwoven fabric is removed. The quantitative evaluation method of the elongation of the spunbond nonwoven fabric is the same as the evaluation method described in the examples.

[0059] "excellent spinnability" means that when the thermoplastic resin composition as a raw material of the spunbond nonwoven fabric is discharged from a spinneret and in the stretching of the continuous fiber group, a broken filament is not easily generated and the continuous fibers do not fuse with each other. The quantitative evaluation method of the spinnability of the spunbond nonwoven fabric is the same as the evaluation method described in the examples.

[0060] The reason why the elongation and the spinnability of the spunbond nonwoven fabric of the present disclosure are excellent is not clear, but can be inferred as follows.

[0061] If the island phase ratio of the fibers contained in the spunbond nonwoven fabric is within the above range, the oriented crystallization of the propylene-based polymer (A) is uniformly hindered in the interior of the island-in-the-sea fibers. Thereby, the elongation and the spinnability of the spunbond nonwoven fabric are improved.

[0062] Further, if the tensile strength ratio (S MD / S CD ) of the spunbond nonwoven fabric is within the above range, the dispersion direction of the fibers constituting the spunbond nonwoven fabric easily becomes a relationship parallel to the running direction (MD). Thereby, the elongation of the obtained spunbond nonwoven fabric is excellent.

[0063] It can be inferred that the main reason why the elongation and the spinnability of the spunbond nonwoven fabric of the present disclosure are excellent is based on the synergistic effect of these combinations.

[0064] (1.1) Tensile strength ratio (S MD / S CD )

[0065] The tensile strength ratio (S MD / S CD ) of the spunbond nonwoven fabric of the present disclosure is 2.0 to 5.1. Since the tensile strength ratio (S MD / S CD ) is 2.0 to 5.1, the fibers oriented in the direction parallel to the running direction (MD) are more than the cross direction (CD). Further, the elongation in the running direction (MD) of the spunbond nonwoven fabric is more excellent. Since the tensile strength ratio (S MD / S CD ) is 5.0 or less, the tensile strength of the spunbond nonwoven fabric does not excessively increase, and the generation of cracks in the fibers constituting the spunbond nonwoven fabric can be suppressed.

[0066] From the viewpoint of improving the elongation of the spunbond nonwoven fabric, the tensile strength ratio (S MD / S CD ) may, for example, be 2.0 to 5.0, preferably 2.5 to 5.1, more preferably 2.5 to 5.1, further preferably 3.0 to 5.0, and particularly preferably 3.5 to 5.0.

[0067] The tensile strength ratio (S MD / S CD ) of the spunbond nonwoven fabric can be measured in accordance with 6.12.1 [A method] of JIS L 1906 (converted to JIS L 1913:2010, corresponding to ISO 9073-3:1989), as described in detail in the Examples described later.

[0068] The running direction (MD) of the spunbond nonwoven fabric can be determined from the spunbond nonwoven fabric itself by measuring the tensile strength of the spunbond nonwoven fabric.

[0069] Generally, in the production of the spunbond nonwoven fabric, the moving speed of the moving capturing member is set in advance from the viewpoint of productivity. Therefore, the continuous fiber group is easily oriented in the direction parallel to the running direction (MD) when laminated on the moving capturing member. As a result, the tensile strength of the running direction (MD) of the spunbond nonwoven fabric is higher than the tensile strength of the transverse direction (CD) of the spunbond nonwoven fabric. Therefore, by measuring the tensile strength of the spunbond nonwoven fabric, the running direction (MD) of the spunbond nonwoven fabric can be determined from the spunbond nonwoven fabric itself.

[0070] (1.2) Fibers having an island-in-sea structure

[0071] The spunbond nonwoven fabric contains island-in-sea fibers.

[0072] The island-in-sea fibers are composed of a resin composition containing a propylene-based polymer (A) and a polymer (B) that is at least one selected from the group consisting of a polyolefin (excluding the propylene-based polymer (A)) and a polyester.

[0073] Hereinafter, the propylene-based polymer (A) is sometimes referred to as “specific polypropylene (A)”.

[0074] Hereinafter, the polymer (B) that is at least one selected from the group consisting of a polyolefin (excluding the propylene-based polymer (A)) and a polyester is sometimes referred to as “specific polymer (B)”.

[0075] The island-in-sea structure has a sea phase and a plurality of island phases. The plurality of island phases exist (for example, are dispersed) in the sea phase.

[0076] The sea phase preferably contains the specific polypropylene (A), and each of the plurality of island phases preferably contains the specific polymer (B). Thus, the oriented crystallization of the sea phase of the main component is hindered, and the spunbond nonwoven fabric exhibits elongation.

[0077] The fiber diameter of the island fiber is preferably 4.0 d (denier) or less, more preferably 3.5 d or less, and further preferably 3.0 d or less.

[0078] The island fiber can be a filament or a staple. Further, the cross-sectional shape of the island fiber is not particularly limited, and examples include a circular shape, an elliptical shape, a shaped cross-section, and the like.

[0079] (1.2.1) Island Phase Ratio

[0080] The island phase ratio of the island fiber is 60% or more on a number basis. Since the island phase ratio is 60% or more on a number basis, the oriented crystallization of the specific polypropylene (A) is not easily hindered unevenly within the fiber. Thus, the spunbond nonwoven fabric exhibits excellent elongation and spinnability.

[0081] From the viewpoint of improving the elongation of the spunbond nonwoven fabric, the island phase ratio is preferably 70% or more on a number basis, more preferably 80% or more on a number basis, and further preferably 90% or more on a number basis.

[0082] The method of making the island phase ratio of the island fiber 60% or more on a number basis is not particularly limited, and examples include a raw material adjustment method, a manufacturing equipment adjustment method, and the like.

[0083] In the raw material adjustment method, the raw material of the island fiber is adjusted. Specifically, by causing the island fiber to contain a low-molecular-weight olefin-based polymer described later, the island phase ratio can be made 60% or more on a number basis.

[0084] In the manufacturing equipment adjustment method, the manufacturing equipment of the spunbond nonwoven fabric is adjusted. Specifically, as the manufacturing equipment adjustment method, examples include a method of selecting a screw having a shape that improves the mixing property, a method of increasing the resin pressure of a die, a method of increasing the outlet temperature of a die, and the like. By these methods, the island phase ratio can be made 60% or more on a number basis.

[0085] The lower limit of the proportion of the island phase area (hereinafter referred to as "island phase area ratio") with respect to the total area of the cross section of the island fiber is preferably 1.0% or more. By the lower limit of the island phase area ratio being 1.0% or more, the oriented crystallization of the specific polypropylene (A) is easily hindered within the island fiber.

[0086] The upper limit of the island phase area ratio is preferably 20% or less. If the upper limit of the island phase area ratio is 20% or less, the oriented crystallization of the specific polypropylene (A) is not easily hindered unevenly in the interior of the island-in-the-sea fiber, and the spunbond nonwoven fabric is more excellent in elongation and spinnability.

[0087] The method for adjusting the island phase area ratio is not particularly limited, and examples include a raw material adjustment method.

[0088] (1.2.2) Material of the fiber having an island-in-the-sea structure

[0089] The island-in-the-sea fiber contained in the spunbond nonwoven fabric is composed of a resin composition. The case where the resin composition contains each of the above components can be appropriately confirmed by a publicly known method.

[0090] (1.2.2.1) Specific polypropylene (A)

[0091] The resin composition of the island-in-the-sea fiber contains the specific polypropylene (A). The specific polypropylene (A) can be only one kind, or two or more kinds that differ from each other in melting point, molecular weight, crystal structure, or the like.

[0092] The specific polypropylene (A) contains a constitutional unit derived from propylene.

[0093] The specific polypropylene (A) is a propylene homopolymer or a propylene copolymer. The propylene copolymer can be a copolymer of propylene and a small amount of one or two or more kinds of α-olefins.

[0094] The number of carbon atoms of the α-olefin in the propylene copolymer is 2 or more (excluding 3), and is preferably 2 to 8 (excluding 3). Specifically, as the α-olefin in the propylene copolymer, ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, and the like can be given.

[0095] Among them, the specific polypropylene (A) preferably contains a propylene homopolymer, and more preferably is a propylene homopolymer.

[0096] The melting point of the specific polypropylene (A) is preferably 140°C or higher, more preferably 150°C or higher, further preferably 155°C or higher, and particularly preferably 157°C or higher and 165°C or lower.

[0097] The melting point of the specific polypropylene (A) is defined as the peak top of the peak observed on the highest temperature side in the melting endotherm curve obtained by using a differential scanning calorimeter (DSC) under a nitrogen atmosphere, after keeping at -40°C for 5 minutes, and then raising the temperature at 10°C / minute.

[0098] Specifically, a differential scanning calorimeter (manufactured by Perkin Elmer, product name: DSC-7) can be used to obtain a melting endothermic curve by keeping a sample of 5 mg under a nitrogen atmosphere at -40°C for 5 minutes and then increasing the temperature at 10°C / minute, and the peak top of the peak observed on the highest temperature side in the melting endothermic curve is determined.

[0099] The melt flow rate (MFR) of the specific polypropylene (A) is not particularly limited as long as the thermoplastic resin composition used as a raw material for the spun-bonded nonwoven fabric can be melt-spun, and is preferably 1 g / 10 minutes to 1000 g / 10 minutes, more preferably 5 g / 10 minutes to 500 g / 10 minutes, and further preferably 10 g / 10 minutes to 100 g / 10 minutes.

[0100] The melt flow rate of the specific polypropylene (A) is measured by a method according to ASTM standard D-1238. The measurement conditions of the melt flow rate of the specific polypropylene (A) are 230°C and a load of 2.16 kg.

[0101] The content of the specific polypropylene (A) is preferably 55.0% by mass to 95.0% by mass, more preferably 65.0% by mass to 95.0% by mass, further preferably 75.0% by mass to 95.0% by mass, and particularly preferably 85.0% by mass to 95.0% by mass, with respect to the total amount of the resin composition.

[0102] By the content of the specific polypropylene (A) being in the above range, the elongation of the spun-bonded nonwoven fabric is improved, and the tensile strength of the spun-bonded nonwoven fabric is maintained in a good range, and the spun-bonded nonwoven fabric is low in the weight per unit area (grammage) and soft. In particular, if the content of the specific polypropylene (A) is 85.0% by mass to 95.0% by mass, the excessive coagulation of the island phase is suppressed, and the elongation and the spinnability of the spun-bonded nonwoven fabric are both satisfied.

[0103] By the content of the specific polypropylene (A) being in the above range, the specific polypropylene (A) is contained in the sea phase, and the specific polymer (B) is contained in the island phase.

[0104] As long as the above specific polypropylene (A) of the present disclosure is satisfied, a commercially available product can also be used.

[0105] (1.2.2.2) Specific Polymer (B)

[0106] The sea-island fiber contains the specific polymer (B). The specific polymer (B) can be only one kind, or two or more kinds that differ from each other in melting point, molecular weight, crystal structure, or the like.

[0107] The specific polymer (B) is at least one selected from the group consisting of a polyolefin (excluding the propylene-based polymer (A)) and a polyester.

[0108] The polyolefin (excluding the propylene-based polymer (A)) is a homopolymer or a copolymer of an α-olefin. The α-olefin is an α-olefin having 2 or more carbon atoms (excluding 3 carbon atoms), preferably a homopolymer of an α-olefin having 2 to 8 carbon atoms (excluding 3 carbon atoms), and more preferably a homopolymer of an α-olefin having 2 to 8 carbon atoms (excluding 3 carbon atoms). As specific examples of the α-olefin, for example, ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, and the like can be given. Among them, the α-olefin is preferably ethylene.

[0109] Specifically, the polyolefin (excluding the propylene-based polymer (A)) can be given polyethylene (ethylene homopolymer), ethylene-α-olefin copolymer, propylene-based polymer, 1-butene-based polymer, poly-4-methyl-1-pentene, and the like.

[0110] As the polyethylene, high-pressure low-density polyethylene, linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), and the like can be given.

[0111] As the ethylene-α-olefin copolymer, ethylene-propylene random copolymer, ethylene-1-butene random copolymer, and the like can be given.

[0112] As the propylene-based polymer, propylene-ethylene random copolymer, propylene-ethylene-1-butene random copolymer, propylene block copolymer, propylene-1-butene random copolymer, and the like can be given.

[0113] As the 1-butene-based polymer, 1-butene homopolymer, 1-butene-ethylene copolymer, 1-butene-propylene copolymer, and the like can be given.

[0114] As the polyester, for example, an aliphatic polyester or a polyester copolymer is given. As the polyester copolymer, for example, a substance in which an aliphatic dicarboxylic acid alone or a mixture of an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid is polymerized with one or two or more kinds of diols can be given.

[0115] Among them, the specific polymer (B) preferably contains polyethylene, and more preferably is polyethylene.

[0116] From the viewpoint of improving the tensile strength of the spun-bonded nonwoven fabric, and the viewpoint of the elongation and softness of the spun-bonded nonwoven fabric, the density of the polyethylene is preferably 0.94 g / cm 3 ~ 0.98 g / cm 3more preferably 0.94 g / cm3 3 ~0.97 g / cm3 3 .

[0117] The melting point of the specific polymer (B) is preferably 150°C or higher, more preferably 155°C or higher, and further preferably 155°C to 165°C.

[0118] The melt flow rate of the specific polymer (B) is not particularly limited as long as the melt of the thermoplastic resin composition used as a raw material of the spun-bonded nonwoven fabric can be spun, and is preferably 1 g / 10 minutes to 1000 g / 10 minutes, more preferably 2 g / 10 minutes to 500 g / 10 minutes, and further preferably 3 g / 10 minutes to 100 g / 10 minutes.

[0119] In the case where the specific polymer (B) is a polyethylene, the melt flow rate is measured by a method according to ASTM standard D-1238. The measurement conditions of the melt flow rate of the polyethylene are 190°C and a load of 2.16 kg.

[0120] The content of the specific polymer (B) is preferably 1.0 mass% to 10.0 mass%, more preferably 3.0 mass% to 8.0 mass%, and further preferably 5.0 mass% to 7.0 mass%, relative to the total amount of the resin composition. If the content of the specific polymer (B) is within the above range, the elongation of the spun-bonded nonwoven fabric is improved.

[0121] (1.2.2.3) Low molecular weight olefin-based polymer

[0122] The resin composition preferably contains a low molecular weight olefin-based polymer having a weight average molecular weight of 500 to 30,000, and the content of the low molecular weight olefin-based polymer is 0.1 mass% to 5.0 mass%, relative to the total amount of the resin composition. The low molecular weight olefin-based polymer can be only one kind, or two or more kinds that differ from each other in melting point, molecular weight, crystal structure, or the like.

[0123] If the island fiber contains the low molecular weight olefin-based polymer and the content of the low molecular weight olefin-based polymer is within the above range, the dispersibility of the specific polypropylene (A) and the specific polymer (B) is improved. As a result, the elongation and the spinnability of the spun-bonded nonwoven fabric are further improved.

[0124] In the case where the island fiber contains the low molecular weight olefin-based polymer, the content of the low molecular weight olefin-based polymer is preferably 0.1 mass% to 5.0 mass%, relative to the total amount of the resin composition.

[0125] From the viewpoint of improving the dispersibility of the specific polypropylene (A) and the specific polymer (B) by allowing an adequate amount of the low molecular weight olefin-based polymer to exist at the interface between the sea phase and the island phase, the lower limit of the content of the low molecular weight olefin-based polymer relative to the total amount of the resin composition is more preferably 0.2% by mass or more, further preferably 1.0% by mass or more, and particularly preferably 1.5% by mass or more.

[0126] From the viewpoint of not causing a significant decrease in the strength of the sea-island fibers, the upper limit of the content of the low molecular weight olefin-based polymer relative to the total amount of the resin composition is more preferably 4.0% by mass or less, further preferably 3.0% by mass or less, and particularly preferably 2.5% by mass or less.

[0127] The low molecular weight olefin-based polymer can contain one constitutional unit derived from an olefin or two or more constitutional units derived from an olefin.

[0128] The low molecular weight olefin-based polymer is a waxy polymer. In other words, the weight average molecular weight (Mw) of the low molecular weight olefin-based polymer is lower than that of the specific polypropylene (A) and the poly-alpha-olefin.

[0129] The weight average molecular weight (Mw) of the low molecular weight olefin-based polymer is 500 to 30,000.

[0130] If the weight average molecular weight (Mw) of the low molecular weight olefin-based polymer is within the above range, the dispersibility of the specific polypropylene (A) and the specific polymer (B) is further improved. As a result, the elongation and the spinnability of the spunbonded nonwoven fabric are further excellent.

[0131] The upper limit of the weight average molecular weight (Mw) of the low molecular weight olefin-based polymer is 30,000 or less, preferably less than 15,000, more preferably 10,000 or less, further preferably 6,000 or less, particularly preferably less than 6,000, more further preferably 5,000 or less, more further preferably 3,000 or less, more further preferably 2,000 or less, and more further preferably 1,500 or less.

[0132] The lower limit of the weight average molecular weight (Mw) of the low molecular weight olefin-based polymer is 500 or more, and preferably 700 or more, and more preferably 1,000 or more.

[0133] The weight average molecular weight (Mw) of the low molecular weight olefin-based polymer can be measured using a gel permeation chromatography (GPC). The measurement conditions of the GPC are preferably the following 1st measurement conditions. The weight average molecular weight (Mw) of the low molecular weight olefin-based polymer is measured, for example, using a standard curve prepared using a commercially available monodisperse standard polystyrene and based on the following conversion formula.

[0134] 〔1st measurement conditions〕

[0135] Apparatus: Gel Permeation Chromatography Alliance GPC 2000 (manufactured by Waters Corporation)

[0136] Solvent: o-dichlorobenzene

[0137] Column: TSKgel GMH6-HT x 2 (manufactured by Tosoh Corporation), TSKgel GMH6-HTL column x 2 (manufactured by Tosoh Corporation)

[0138] Flow rate: 1.0 ml / min

[0139] Sample: 0.15 mg / mL o-dichlorobenzene solution

[0140] Temperature: 140°C

[0141] Molecular weight conversion: Polystyrene (PS) conversion / universal calibration method

[0142] The calculation of the universal calibration used the coefficients of the Mark-Houwink viscosity equation shown below.

[0143] Coefficient of polystyrene (PS): KPS= 1.38 x 10 -4 , aPS= 0.70

[0144] Coefficient of polyethylene (PE): KPE= 5.06 x 10 -4 , aPE= 0.70

[0145] The softening point of the low molecular weight olefin-based polymer is preferably 90°C to 145°C, more preferably 90°C to 135°C, and further preferably 100°C to 125°C.

[0146] The softening point of the low molecular weight olefin-based polymer is measured according to JIS K2207.

[0147] The density of the low molecular weight olefin-based polymer is not particularly limited, and is preferably 0.890 g / cm 3 to 0.980 g / cm 3 .

[0148] If the density of the low molecular weight olefin-based polymer is within the above range, the elongation of the spunbond nonwoven fabric is more excellent.

[0149] The lower limit of the density of the low molecular weight olefin-based polymer is more preferably 0.910 g / cm 3 or more, and further preferably 0.920 g / cm 3 or more.

[0150] The upper limit of the density of the low molecular weight olefin-based polymer is more preferably 0.960 g / cm 3Further preferably, it is 0.940 g / cm3 3 Further.

[0151] The density of the low molecular weight olefin-based polymer is measured according to JIS K7112.

[0152] The difference between the density of the low molecular weight olefin-based polymer and the density of the specific polypropylene (A) is not particularly limited, and is preferably less than 0.35 g / cm3 3 More preferably, it is less than 0.20 g / cm3 3 Further preferably, it is less than 0.15 g / cm3 3 .

[0153] If the difference between the density of the low molecular weight olefin-based polymer and the density of the specific polypropylene (A) is within the above range, the elongation of the spunbonded nonwoven fabric is more excellent.

[0154] Although the reason is not clear, it can be considered as follows. If the density of the low molecular weight olefin-based polymer and the density of the specific polypropylene (A) are within the above range, it can be considered, for example, that the specific polymer (B) is easily dispersed in the specific polypropylene (A) with the aid of the low molecular weight olefin-based polymer. That is, the low molecular weight olefin-based polymer effectively functions as a compatibilizer for the specific polypropylene (A) and the specific polymer (B). Therefore, the dispersibility of the specific polypropylene (A) and the specific polymer (B) is improved. It is considered that as a result, the elongation of the spunbonded nonwoven fabric is improved.

[0155] The low molecular weight olefin-based polymer is a homopolymer of an olefin or an olefin-based copolymer composed of two or more kinds of olefins.

[0156] Among them, the low molecular weight olefin-based polymer can be a homopolymer of ethylene or a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms.

[0157] The number of carbon atoms of the α-olefin is preferably 3 to 8, more preferably 3 to 4.

[0158] If the number of carbon atoms of the α-olefin is within the above range, the elongation and the spinnability of the spunbonded nonwoven fabric are more improved. Although the reason is not clear, it can be considered as follows.

[0159] If the number of carbon atoms of the α-olefin is within the above range, it can be considered, for example, that the specific polymer (B) is easily dispersed in the specific polypropylene (A) with the aid of the low molecular weight olefin-based polymer. That is, the low molecular weight olefin-based polymer functions as a compatibilizer for the specific polypropylene (A) and the poly α-olefin. Therefore, the uniformity of the specific polypropylene (A) and the specific polymer (B) is improved. It is considered that as a result, the properties such as the elongation of the spunbonded nonwoven fabric are improved.

[0160] The low molecular weight olefin-based polymer can be a single low molecular weight olefin-based polymer or a mixture of two or more thereof.

[0161] The method for producing the low molecular weight olefin-based polymer is not particularly limited, and for example, a first production method, a second production method, and the like can be given. The first production method indicates a production method based on polymerization of a low molecular weight polymer that is generally used. The second production method indicates a method for reducing the molecular weight by thermally degrading a high molecular weight ethylene-based polymer.

[0162] The low molecular weight olefin-based polymer can be refined by a method such as solvent fractionation or distillation based on a difference in solubility in a solvent.

[0163] As the first production method, for example, a production method using a Ziegler-Natta catalyst or a metallocene-based catalyst, and the like can be given. As the production method using a metallocene-based catalyst, a production method described in Japanese Patent Application Publication No. 08-239414, International Publication No. 2007 / 114102, and the like can be given.

[0164] The low molecular weight olefin-based polymer can be a commercially available product. As the commercially available product of the low molecular weight olefin-based polymer, "HI-WAX (registered trademark) 320P", "Excerex (registered trademark) 30200B", "HI-WAX (registered trademark) 100P", "HI-WAX (registered trademark) 110P", and the like manufactured by Mitsui Chemicals, Inc. can be given.

[0165] (1.2.2.4) Fatty acid amide

[0166] The sea-island fiber preferably contains a fatty acid amide having 15 to 22 carbon atoms, and the content of the fatty acid amide is 0.1 to 5.0 mass% with respect to the total amount of the resin composition. The fatty acid amide can be only one kind, or two or more kinds.

[0167] Thus, the fatty acid amide having 15 to 22 carbon atoms is adsorbed to the fiber surface of the spunbond nonwoven fabric to modify the surface of the sea-island fiber. In other words, the softness, the tactile sensation, the blocking resistance, and the like of the spunbond nonwoven fabric are further improved. Therefore, it is considered that the nonwoven fabric fiber is more effectively inhibited from adhering to various rotating devices and the like members inside the device used in the embossing process and the like. As a result, the elongation and the softness of the spunbond nonwoven fabric are further improved.

[0168] In the present disclosure, the "carbon atom number of the fatty acid amide" means the number of carbon atoms contained in the molecule, and the carbon in -CONH constituting the amide is also included in the above carbon atom number.

[0169] The carbon atom number of the fatty acid amide is preferably 18 to 22.

[0170] As the fatty acid amide having 15 to 22 carbon atoms, a fatty acid monoamide compound, a fatty acid diamide compound, a saturated fatty acid monoamide compound, and an unsaturated fatty acid diamide compound can be mentioned, and among them, palmitamide (carbon atoms: 16), stearamide (carbon atoms: 18), oleamide (carbon atoms: 18), erucamide (carbon atoms: 22), and the like can be suitably mentioned.

[0171] The content of the fatty acid amide having 15 to 22 carbon atoms is preferably 0.1 to 5.0% by mass, more preferably 0.1 to 3.0% by mass, and further preferably 0.1 to 1.0% by mass, relative to the total amount of the resin composition.

[0172] (1.2.2.6) Additives

[0173] The island fiber can contain an additive as an arbitrary component within a range not impairing the object of the present disclosure. As the additive, an antioxidant, a heat-resistant stabilizer, a weather-resistant stabilizer, an antistatic agent, a slip agent, a hydrophilic agent, an antifog agent, a lubricant, a dye, a pigment, a natural oil, a synthetic oil, a wax, a fatty acid amide, and the like can be mentioned.

[0174] (1.3) Configuration of the Spunbond Nonwoven Fabric

[0175] The spunbond nonwoven fabric can be composed of only the island fiber, or can be composed of the island fiber and a fiber not having an island structure.

[0176] In the case where the spunbond nonwoven fabric is composed of the island fiber and the fiber not having an island structure, the content of the island fiber is preferably 5 to 95% by mass, more preferably 15 to 90% by mass, further preferably 30 to 85% by mass, and particularly preferably 40 to 70% by mass, relative to the total amount of the spunbond nonwoven fabric, from the viewpoint of exhibiting the above-described effects of the spunbond nonwoven fabric.

[0177] In the case where the spunbond nonwoven fabric is composed of only the island fiber, the grammage of the spunbond nonwoven fabric is preferably 30 g / m 2 or less, more preferably 28 g / m 2 or less, and further preferably 25 g / m 2 or less, from the viewpoint of balancing the softness and the tensile strength of the spunbond nonwoven fabric. 2 20 g / m 2 .

[0178] In the case where the spunbond nonwoven fabric is applied to a sanitary material or the like described later, the grammage of the spunbond nonwoven fabric is preferably in the range of 5 g / m 2 19 g / m 2 .

[0179] The spunbond nonwoven fabric can also have stretchable spunbond fibers.

[0180] The stretchable spunbond fibers are preferably fibers produced by extruding a resin containing a specific thermoplastic polyurethane elastomer and using a spunbond method. The specific thermoplastic polyurethane elastomer has a solidification onset temperature of at least 65°C in differential scanning calorimeter (DSC) measurement, and a number of particles of a polar solvent-insoluble component of 3 million / g or less as measured in a particle size distribution measuring device equipped with a small hole of 100 micrometers based on a pore resistance method.

[0181] The stretchable spunbond fibers having the above-described properties can be produced, for example, by the method described in International Publication No. 2004 / 065680 or International Publication No. 2011 / 129433.

[0182] In the case where the spunbond nonwoven fabric has stretchable spunbond fibers, the spunbond nonwoven fabric can be the layered nonwoven fabric described later, or can be the mixed fiber nonwoven fabric described later.

[0183] The spunbond nonwoven fabric can be the layered nonwoven fabric or the mixed fiber nonwoven fabric depending on the purpose.

[0184] (1.3.1) Layered Nonwoven Fabric

[0185] The layered nonwoven fabric is produced by combining a spunbond fiber web with a resin layer. The resin layer is layered on at least one face of the spunbond fiber web. The spunbond fiber web contains island-in-the-sea fibers. The method of combining the spunbond fiber web with the resin layer can be any publicly known combining method.

[0186] In the present disclosure, the "spunbond fiber web" refers to a fiber web produced by extruding a molten or dissolved thermoplastic resin composition from a spinneret and layering continuous fibers (filaments) on a moving capturing member (e.g., a mesh conveyor). In the spunbond fiber web, the fibers constituting the spunbond fiber web are not combined with each other, which is different from the spunbond nonwoven fabric in this respect.

[0187] In the layered nonwoven fabric, the spunbond fiber web and the resin layer can each be one layer without particular limitation. In the layered nonwoven fabric, the spunbond fiber web can be one layer, or two or more layers. In the layered nonwoven fabric, the resin layer can be one layer, or two or more layers.

[0188] From the viewpoint of balancing the softness and the tensile strength of the layered nonwoven fabric, the grammage of the layered nonwoven fabric is preferably 100 g / m 2 More preferably, the grammage of the layered nonwoven fabric is 90 g / m 2 Further preferably, the grammage of the layered nonwoven fabric is 80 g / m 2 Further preferably, the grammage of the layered nonwoven fabric is 70 g / m

[0189] In the case where the layered nonwoven fabric is applied to a sanitary material or the like described later, the grammage of the layered nonwoven fabric is preferably 20 g / m2 ~ 70 g / m 2 in the range of 0.1 to 10 g / m2 / 24 hours.

[0190] The raw material of the resin layer can be different from the raw material of the thermoplastic resin composition as the island fiber.

[0191] As the resin layer, for example, a knitted fabric, a woven fabric, a fiber web, a nonwoven fabric, a film, or the like can be given.

[0192] The nonwoven fabric as an example of the resin layer can include a spunbond nonwoven fabric, a meltblown nonwoven fabric, a wet type nonwoven fabric, a dry type nonwoven fabric, a dry type pulp nonwoven fabric, a flash spinning nonwoven fabric, a split nonwoven fabric, and the like.

[0193] These nonwoven fabrics can be either stretchable nonwoven fabrics or non-stretchable nonwoven fabrics. The stretchable nonwoven fabric has a third property and a fourth property. The "third property" indicates a property in which the outer shape of the nonwoven fabric is elongated in one direction when an external force is applied to the nonwoven fabric. The "fourth property" indicates a property in which the outer shape of the nonwoven fabric is restored when the external force applied to the nonwoven fabric is removed.

[0194] As the stretchable nonwoven fabric, an elastic nonwoven fabric using a low-crystalline polypropylene described in International Publication No. 2012 / 070518 can be given.

[0195] The fiber web as an example of the resin layer can include a spunbond fiber web, a meltblown fiber web, a wet type fiber web, a dry type fiber web, a dry type pulp fiber web, a flash spinning fiber web, a split fiber web, and the like.

[0196] These fiber webs can be either stretchable fiber webs or non-stretchable fiber webs.

[0197] The film as an example of the resin layer is preferably a gas permeable film or a moisture permeable film when the laminated nonwoven fabric requires gas permeability.

[0198] As the gas permeable film, a film composed of a thermoplastic elastomer, a porous film, or the like can be given. As the raw material of the film, a thermoplastic elastomer having moisture permeability, such as a polyurethane-based elastomer, a polyester-based elastomer, a polyamide-based elastomer, or the like can be given.

[0199] The porous film is formed by stretching a film composed of a thermoplastic resin containing inorganic or organic microparticles to be porous. As the raw material of the porous film, a polyolefin such as high-pressure low-density polyethylene, linear low-density polyethylene (so-called LLDPE), high-density polyethylene, polypropylene, a polypropylene random copolymer, a combination thereof, or the like is preferred.

[0200] In the case where the laminated nonwoven fabric does not require gas permeability, as the raw material of the film as an example of the resin layer, one or more thermoplastic resins selected from polyethylene, polypropylene, and the like can be used.

[0201] The laminated nonwoven fabric is preferably partially heat-sealed.

[0202] As the heat-sealing method when partially heat-sealing the laminated nonwoven fabric, a method using means such as ultrasonic waves, hot embossing using an embossing roll, hot air through, and the like can be given. Among these, from the viewpoint that the long fibers can be efficiently stretched when stretching the laminated nonwoven fabric, the heat-sealing method is preferably hot embossing.

[0203] In the case where a portion of the laminated nonwoven fabric is heat-sealed by hot embossing, generally, the embossing area ratio is preferably 5 to 30%, and more preferably 5 to 20%. As the engraved shape, a circular shape, an elliptical shape, an oblong shape, a square shape, a diamond shape, a rectangular shape, a square shape, a continuous shape based on these shapes, and the like can be given.

[0204] The embossing temperature in the hot embossing is appropriately adjusted depending on the line speed, the pressure bonding pressure, and the like at the time of embossing, and is preferably 85 to 150°C.

[0205] In the case where the resin layer is a knitted fabric, a woven fabric, a fiber web, or a nonwoven fabric, the resin layer preferably contains a thermoplastic elastomer fiber.

[0206] By the resin layer containing a thermoplastic elastomer fiber, it is possible to produce a stretchable nonwoven fabric that does not undergo blocking.

[0207] The material of the thermoplastic elastomer fiber is not particularly limited, and is only required to be a thermoplastic elastomer. The thermoplastic elastomer has a soft segment (soft phase) and a hard segment (hard phase). The soft segment (soft phase) has elasticity in the molecule. The hard segment (hard phase) has a property of preventing plastic deformation.

[0208] As the thermoplastic elastomer fiber, for example, a polyurethane-based thermoplastic elastomer fiber, an olefin-based thermoplastic elastomer fiber, a styrene-based thermoplastic elastomer fiber, a polyester-based thermoplastic elastomer fiber, a polyamide-based thermoplastic elastomer fiber, and the like can be given. Among these, from the viewpoint of the stretchability and the spinning stability of the laminated nonwoven fabric, the thermoplastic elastomer fiber is preferably a thermoplastic polyurethane fiber or an olefin-based thermoplastic elastomer fiber.

[0209] As the material of the polyurethane-based thermoplastic elastomer fiber, a polyurethane produced by a method such as:

[0210] (1) a method in which an isocyanate group terminal prepolymer obtained by preliminarily reacting a polyol with an isocyanate compound is reacted with a chain extender;

[0211] (2) a method in which a polyol is preliminarily mixed with a chain extender, and then the mixture is reacted with an isocyanate compound, and the like.

[0212] As the polyol which is one of the components constituting the above-mentioned polyurethane-based thermoplastic elastomer, polyoxyalkylene polyol, polytetramethylene ether glycol, polyester polyol, polycaprolactone polyol, polycarbonate diol, and the like can be given.

[0213] As the isocyanate compound, aromatic ring, aliphatic or alicyclic compound having two or more isocyanate groups in one molecule, and the like can be given.

[0214] As the chain extender, aliphatic, aromatic, heterocyclic or alicyclic low-molecular-weight polyol having two or more hydroxyl groups in one molecule, and the like can be given.

[0215] Specifically, as the polyurethane-based thermoplastic elastomer fiber, the thermoplastic polyurethane elastomer described in International Publication No. 2011 / 129433, which uses 1,4-bis(2-hydroxyethoxy)benzene as a chain extender, can be given.

[0216] As the material of the olefin-based thermoplastic elastomer fiber, a substance in which an ethylene-a-olefin random copolymer and a diene copolymer as a second component are combined, and the like can be given, and specifically, a substance in which an ethylene-propylene random copolymer, an ethylene-1-butene random copolymer, EPDM (ethylene-propylene-diene copolymer, dicyclopentadiene or ethylidene norbornene as a diene component) as a soft segment, and a polyolefin as a hard segment are combined, and the like can be given. As the trade name of the material of the olefin-based thermoplastic elastomer fiber, Tafmer (manufactured by Mitsui Chemicals, Inc.), Milastomer (manufactured by Mitsui Chemicals, Inc.), EVAFLEX-EEA (manufactured by Mitsui DuPont Polychemicals, Inc.), Vistamaxx (manufactured by Exxon Mobil Corporation), and the like can be given.

[0217] As the raw material of each of the styrene-based thermoplastic elastomer fiber, the polyester-based thermoplastic elastomer fiber, and the polyamide-based thermoplastic elastomer fiber, a substance described in Japanese Patent Application Publication No. 2001-179867 can be given.

[0218] The fiber diameter of the thermoplastic elastomer fiber is preferably 4.0 d (denier) or less, more preferably 3.5 d or less, and further preferably 3.0 d or less.

[0219] The thermoplastic elastomer fiber can be a filament or a staple. Further, the cross-sectional shape of the thermoplastic elastomer fiber is not particularly limited, and for example, a circular shape, an elliptical shape, a shaped cross-section, and the like can be given.

[0220] (1.3.2) Mixed fiber nonwoven fabric

[0221] The mixed fiber nonwoven fabric contains the thermoplastic elastomer fiber. The mixed fiber nonwoven fabric is a mixed fiber of the island fiber and the thermoplastic elastomer fiber.

[0222] The mixed fiber ratio of the island fiber is not particularly limited, and is preferably 5 to 95 mass%, more preferably 25 to 75 mass%, and further preferably 40 to 60 mass%.

[0223] The "mixed fiber ratio" means the proportion of a certain kind of fiber contained in a nonwoven fabric in which two or more kinds of fibers are mixed, or the mixing ratio of various fibers in the nonwoven fabric. That is, the "mixed fiber ratio of the island fiber" in a mixed fiber nonwoven fabric composed of island fibers and thermoplastic elastomer fibers means {mass of island fiber ÷ (mass of island fiber + mass of thermoplastic elastomer fiber)}. The "mixed fiber ratio of the thermoplastic elastomer fiber" means {mass of thermoplastic elastomer fiber ÷ (mass of island fiber + mass of thermoplastic elastomer fiber)}.

[0224] From the viewpoint of balancing the softness and tensile strength of the mixed fiber nonwoven fabric, the basis weight of the mixed fiber nonwoven fabric is preferably 100 g / m 2 or more, and more preferably 90 g / m 2 or more, and further preferably 80 g / m 2 or more.

[0225] In the case where the mixed fiber nonwoven fabric is applied to a sanitary material or the like described later, the basis weight of the mixed fiber nonwoven fabric is preferably in the range of 20 g / m 2 or more and 70 g / m 2 or less.

[0226] As the thermoplastic elastomer fiber, the same fiber as exemplified as the thermoplastic elastomer fiber that can be contained in the resin layer of the layered nonwoven fabric can be cited.

[0227] (2) Sanitary material

[0228] The sanitary material of the present disclosure contains the spunbond nonwoven fabric of the present disclosure.

[0229] The spunbond nonwoven fabric of the present disclosure is excellent in elongation. Therefore, the sanitary material of the present disclosure is excellent in elongation.

[0230] The sanitary material is suitable for various sanitary material uses that require elongation and softness. Specifically, the sanitary material is suitable for medical sanitary material uses such as paper diapers, sanitary napkins, and the like, absorbent articles, bandages, medical gauze, towels, and the like, and sanitary masks.

[0231] (3) Method for producing spunbond nonwoven fabric

[0232] The spunbond nonwoven fabric of the present disclosure is produced using a thermoplastic resin composition as a raw material and by a conventional method.

[0233] The spunbond nonwoven fabric of the present disclosure is produced, for example, as follows.

[0234] That is, the thermoplastic resin composition is introduced into an extruder and melted. The melt of the thermoplastic resin composition is spun using a spunbond nonwoven fabric forming machine having a plurality of spinnerets. The resulting continuous fiber assembly is stretched by controlling the air volume using a blower or the like. At this time, the continuous fiber assembly is cooled as necessary. Then, the continuous fiber assembly is accumulated on a catching surface of the spunbond nonwoven fabric forming machine to obtain a spunbond fiber web. The resulting spunbond fiber web is subjected to a heat-pressing treatment using an embossing roll. Thus, a spunbond nonwoven fabric is obtained.

[0235] The composition of the thermoplastic resin composition is the same as the composition exemplified above as the composition of the island fiber.

[0236] Hereinafter, an example of a method for producing a spunbond nonwoven fabric will be described in detail with reference to the drawings.

[0237] Figure 1 is a schematic view showing an example of a production apparatus for a closed-type spunbond method. In the closed-type spunbond method, a continuous fiber assembly formed by melt spinning a thermoplastic resin composition is stretched while being cooled in a closed space.

[0238] Figure 1 The production apparatus 100 for the closed-type spunbond method shown in the drawing includes a spinning section 10. The spinning section 10 has an extruder 11, a spinneret 12, a cooling chamber 13, a cooling air supply section 14, a cooling air supply section 15, and a stretching section 16. The extruder 11 extrudes a thermoplastic polymer. The spinneret 12 spins the melt of the thermoplastic polymer. The cooling chamber 13 cools a continuous fiber assembly 1 spun out by the spinneret 12. The cooling air supply section 14 and the cooling air supply section 15 supply cooling air A into the cooling chamber 13 and the stretching section 16. The stretching section 16 stretches the continuous fiber assembly 1.

[0239] First, a thermoplastic resin composition is introduced into the extruder 11. The thermoplastic resin composition introduced into the extruder 11 is melt-kneaded in the extruder 11. The melt of the thermoplastic resin composition is extruded from the extruder 11.

[0240] The melt of the thermoplastic resin composition extruded from the extruder 11 is introduced into the spinneret 12. The melt of the thermoplastic resin composition introduced into the spinneret 12 is extruded from the spinneret 12 to be spun. Thus, the continuous fiber assembly 1 is formed.

[0241] The continuous fiber assembly 1 is introduced into the cooling chamber 13. The continuous fiber assembly 1 introduced into the cooling chamber 13 is cooled by the cooling air A. The cooling air A is supplied into the cooling chamber 13 and the stretching section 16 by at least one of the cooling air supply section 14 and the cooling air supply section 15. The cooled continuous fiber assembly 1 is introduced into the stretching section 16 disposed on the downstream side of the cooling chamber 13.

[0242] The stretch section 16 has a neck section 16a and a cylinder section 16b. The cylinder section 16b is formed at the end of the lower side (i.e., the moving capturing member 21 side) in the vertical direction (i.e., the gravitational direction) of the neck section 16a. The neck section 16a is neck-shaped. The cylinder section 16b is a cylinder. The hollow portion of the cylinder section 16b is enlarged toward the lower side as shown. Figure 1 The continuous fiber group 1 introduced into the stretch section 16 is stretched at the neck section 16a due to the increase in the speed of the cooling air. The continuous fiber group 1 stretched and passed through the cylinder section 16b is dispersed and captured on the moving capturing member 21.

[0243] The dispersed continuous fiber group 1 is efficiently captured on the moving capturing member 21 by the suction unit 22. The suction unit 22 is disposed at the lower portion of the capturing surface of the moving capturing member 21. Thus, the spunbond fiber web 2 is formed.

[0244] Then, the fibers contained in the spunbond fiber web 2 are subjected to a heat and pressure treatment by, for example, an embossing roll (not shown) and are bonded. Thus, a spunbond nonwoven fabric is obtained.

[0245] The manufacturing method of the spunbond nonwoven fabric of the present disclosure has been described taking the closed spunbond method as an example, but the manufacturing method of the spunbond nonwoven fabric of the present disclosure is not limited to the closed spunbond method. The manufacturing method of the spunbond nonwoven fabric of the present disclosure can also be an open spunbond method. In the open spunbond method, the continuous fiber group formed by melt spinning the thermoplastic resin composition is cooled.

[0246] The melting temperature of the thermoplastic resin composition is not particularly limited as long as it is equal to or higher than the softening temperature or the melting temperature of the thermoplastic resin composition and is lower than the thermal decomposition temperature of the thermoplastic resin composition, and can be appropriately set according to the physical properties and the like of the thermoplastic resin composition.

[0247] The temperature of the spinneret 12 can be appropriately adjusted according to the physical properties and the like of the thermoplastic resin composition. In consideration of the physical properties of the specific polypropylene (A) contained in the thermoplastic resin composition, the temperature of the spinneret 12 is preferably 180°C to 240°C, more preferably 190°C to 230°C, and further preferably 200°C to 225°C.

[0248] The pore diameter of the spinneret 12 is not particularly limited, and is preferably 0.05 mm to 1.00 mm from the viewpoint of the elongation of the spunbond nonwoven fabric.

[0249] The single-hole discharge amount of the melt of the thermoplastic resin composition from the spinneret 12 is preferably 0.1 g / minute to 3.0 g / minute, and more preferably 0.3 g / minute to 1.0 g / minute, from the viewpoint of the elongation of the spunbond nonwoven fabric.

[0250] The temperature of the cooling air for cooling the continuous fiber assembly extruded from the spinneret is not particularly limited as long as it is the temperature at which the thermoplastic resin composition solidifies. The temperature of the cooling air is preferably 5°C to 50°C, more preferably 10°C to 40°C, and further preferably 15°C to 30°C.

[0251] In the production method of the spunbond nonwoven fabric of the present disclosure, the fibers contained in the spunbond nonwoven fabric can be heat-fused in part thereof. The fibers contained in the spunbond nonwoven fabric can also be pressed using a roll before heat-fusion.

[0252] Examples

[0253] Hereinafter, the embodiments of the present disclosure are more specifically described based on examples, but the present disclosure is not limited to these examples as an embodiment of the present disclosure.

[0254] The physical property values and the like of the spunbond nonwoven fabric in the examples and comparative examples can be measured by the following methods.

[0255] (1) Gram weight [g / m 2 ]

[0256] Ten test pieces of 300 mm in the running direction (MD) and 250 mm in the cross direction (CD) were collected from the spunbond nonwoven fabric. The collection position was any 10 positions of the spunbond nonwoven fabric. Then, the mass (g) of each of the collected test pieces was measured using a top pan electronic balance (manufactured by Kenz, Ltd.). The average value of the mass of each of the test pieces was calculated. The mass (g) per 1 m 2 of the spunbond nonwoven fabric was calculated from the calculated average value, rounded off to the first decimal place, and set as the gram weight [g / m 2 ] of the spunbond nonwoven fabric.

[0257] (2) Maximum elongation, tensile strength (maximum strength), and tensile strength ratio (S MD / S CD )

[0258] In accordance with 6.12.1 [A method] of JIS L 1906 (converted to JIS L 1913:2010, corresponding to ISO 9073-3:1989), five test pieces of 25 cm in the running direction (MD) and 5 cm in the cross direction (CD) were collected from the spunbond nonwoven fabric in a constant-temperature room at a temperature of 20 ± 2°C and a humidity of 65 ± 2% as specified in JIS Z 8703 (standard state of test site). For the obtained test pieces, a tensile test was performed using a tensile testing machine (manufactured by Instron Japan Co., Ltd., Instron 5564 type) under conditions of a temperature of 20 ± 2°C, a chuck distance of 100 mm, and a tensile speed of 300 mm / minute, and the tensile load was measured for the five test pieces, and the average value of the maximum values thereof was set as the tensile strength (maximum strength) in the running direction (MD) [N / 50 mm].

[0259] The elongation in the tensile strength (maximum strength) was set as the maximum elongation (%) as an index for evaluating the elongation. In measuring the tensile strength and the maximum elongation in the cross direction, five test pieces of 25 cm in the cross direction (CD) and 5 cm in the running direction (MD) were collected, and the tensile test was performed under the same conditions. Specifically, the maximum elongation (%) in the running direction was calculated from the following equation.

[0260] Equation: Maximum elongation (%) = {(maximum length - 25 cm) / 25 cm} x 100

[0261] In the equation, "maximum length" indicates the length (cm) of the test piece when the tensile strength is exhibited in the long side of the test piece.

[0262] The tensile strength ratio (S MD / S CD ) was calculated from the measured value of the tensile strength (S MD ) in the running direction (MD) and the measured value of the tensile strength (S CD ) in the cross direction (CD).

[0263] (3) Fiber diameter

[0264] Ten test pieces of 10 mm x 10 mm were collected from the spunbond nonwoven fabric, and the diameter of the fiber was read to the first decimal place in the unit of μm using an ECLIPSE E400 microscope manufactured by Nikon Corporation at a magnification of 20 times. The diameter of 20 arbitrary places was measured for each of the test pieces, and the average value was calculated.

[0265] (4) Confirmation of island-in-sea structure and proportion (%) of island phase

[0266] The fibers were taken out from the spunbond nonwoven fabric, embedded in paraffin, and a measurement sample was prepared. Then, the measurement sample was set in the direction orthogonal to the fiber axis and parallel to the blade in a microtome, and slicing was performed in the direction orthogonal to the fiber axis. After that, the carbon-reinforced fibers obtained by slicing were observed using a transmission electron microscope (TEM). The island-in-sea structure was observed for the cross section of the fibers. The continuous phase was regarded as the sea phase, and the dispersed phase was regarded as the island phase. The diameter of the island phase within the observation range (cross section) was measured. The number of island phases having a diameter of 0.32 μm or more and the number of island phases having a diameter of less than 0.32 μm were counted. The number of island phases in each range was divided by the number of island phases within the observation range (cross section), and the proportion (i.e., the proportion of island phases) was calculated.

[0267] Here, as the transmission electron microscope, a transmission electron microscope Model H-7650 manufactured by Hitachi High-Technologies Corporation was used. The observation magnification was set to 6000 times.

[0268] The diameter of the island phase was found by image analysis using Mac-View (Mountech Corporation). Specifically, the major axis and the minor axis of the island phase were measured, and the average of these was set as the diameter. The island phase area ratio was set as the value obtained by dividing the total area of the island phase by the total area of the cross section of the island-in-sea fiber.

[0269] (5) Evaluation of Spinning Property

[0270] In the spinning of the spun-bond nonwoven fabric shown in the examples, the number of times of breakage of the yarn occurring within 30 minutes (hereinafter, referred to as "breakage frequency") was measured. Based on the measurement result of the breakage frequency, the spinning property was evaluated according to the following criteria. The acceptable evaluation of the spinning property was "A".

[0271] A: The breakage frequency was 0 times.

[0272] B: The breakage frequency was 1 to 3 times.

[0273] C: The breakage frequency was 4 times or more.

[0274] (Example 1)

[0275] <Manufacture of Spun-Bond Nonwoven Fabric>

[0276] A mixture of 92.7 parts by mass of a propylene homopolymer (1) having an MFR (determined in accordance with ASTM D1238 at a temperature of 230°C under a load of 2.16 kg) of 60 g / 10 minutes, a density of 0.91 g / cm 3 , and a melting point of 160°C,

[0277] 6.0 parts by mass of a high-density polyethylene (hereinafter, referred to as "polyethylene") having an MFR (determined in accordance with ASTM D1238 at a temperature of 190°C under a load of 2.16 kg) of 5 g / 10 minutes, a density of 0.95 g / cm 3 , and a melting point of 134°C,

[0278] 1.0 part by mass of an ethylene-propylene copolymer wax (manufactured by Mitsui Chemicals, Inc., product name "HI-WAX (registered trademark) 320P", density: 0.93 g / cm 3 , weight average molecular weight: 3000), and

[0279] 0.3 parts by mass of erucic acid amide was used

[0280] ​Extruder, melt-spun using a spunbond nonwoven fabric forming machine having a spinneret with 1093 holes (length in the direction perpendicular to the mechanical running direction on the catching surface: 320 mm, refer to Figure 1 ), under conditions where the resin temperature and the mold temperature were both 200°C, the resin discharge amount was 32 kg / h, the cooling air temperature was 20°C, the air flow speed of the drawing air was 3529 m / min, and the melt-spun using the spunbond method was made to accumulate on the catching surface, and the heated and pressurized treatment using the embossing roll was performed (embossing area ratio (heat seal ratio) 18%, embossing temperature 90°C), to produce a spunbond nonwoven fabric with a total basis weight of 18.0 g / m 2 . The number of broken filaments in the test was 0.

[0281] An image when observing the cross section of the fiber in the spunbond nonwoven fabric obtained in Example 1 using a transmission electron microscope is shown in Figure 2 .

[0282] (Example 2)

[0283] The propylene homopolymer (1) having a melting point of 160°C was changed to 91.7 parts by mass, and the product name "HI-WAX (registered trademark) 320P" [density: 0.93 g / cm 3 , weight average molecular weight: 3000] was changed to 2.0 parts by mass, and otherwise, a spunbond nonwoven fabric was produced and evaluated by the same method as in Example 1. The number of broken filaments in the test was 0.

[0284] (Example 3)

[0285] The propylene homopolymer (1) having a melting point of 160°C was changed to 90.7 parts by mass, and the product name "HI-WAX (registered trademark) 320P" [density: 0.93 g / cm 3 , weight average molecular weight: 3000] was changed to 3.0 parts by mass, and otherwise, a spunbond nonwoven fabric was produced and evaluated by the same method as in Example 1. The number of broken filaments in the test was 0.

[0286] (Example 4)

[0287] The propylene homopolymer (1) having a melting point of 160°C was changed to 87.7 parts by mass, the polyethylene was changed to 10.0 parts by mass, and the product name "HI-WAX (registered trademark) 320P" [density: 0.93 g / cm 3 , weight average molecular weight: 3000] was changed to 2.0 parts by mass, and otherwise, a spunbond nonwoven fabric was produced and evaluated by the same method as in Example 1. The number of broken filaments in the test was 0.

[0288] (Example 5)

[0289] The propylene homopolymer (1) having a melting point of 160°C was changed to 86.7 parts by mass, and the product name "HI-WAX (registered trademark) 320P" [density: 0.93 g / cm 3 , weight average molecular weight: 3000] was changed to 3.0 parts by mass, and a spunbonded nonwoven fabric was produced and evaluated by the same method as in Example 4, except for this. The number of broken filaments in the test was 0.

[0290] (Example 6)

[0291] The product name "HI-WAX (registered trademark) 320P" [density: 0.93 g / cm 3 , weight average molecular weight: 3000] was changed to an ethylene-butene copolymer wax (manufactured by Mitsui Chemicals, Inc., product name "Excerex (registered trademark) 30200B", density: 0.92 g / cm 3 , weight average molecular weight: 2900], and a spunbonded nonwoven fabric was produced and evaluated by the same method as in Example 1, except for this. The number of broken filaments in the test was 0.

[0292] (Example 7)

[0293] The product name "HI-WAX (registered trademark) 320P" [density: 0.93 g / cm 3 , weight average molecular weight: 3000] was changed to an ethylene polymer wax (manufactured by Mitsui Chemicals, Inc., product name "HI-WAX (registered trademark) 100P", density: 0.95 g / cm 3 , weight average molecular weight: 900], and a spunbonded nonwoven fabric was produced and evaluated by the same method as in Example 1, except for this. The number of broken filaments in the test was 0.

[0294] (Example 8)

[0295] The product name "HI-WAX (registered trademark) 320P" [density: 0.93 g / cm 3 , weight average molecular weight: 3000] was changed to an ethylene-propylene copolymer wax (manufactured by Mitsui Chemicals, Inc., product name "HI-WAX (registered trademark) 110P", density: 0.92 g / cm 3 , weight average molecular weight: 1000], and a spunbonded nonwoven fabric was produced and evaluated by the same method as in Example 1, except for this. The number of broken filaments in the test was 0.

[0296] (Example 9)

[0297] The propylene homopolymer (1) having a melting point of 160°C was changed to 93.7 parts by mass, and the polyethylene was changed to 5.0 parts by mass, and a spunbonded nonwoven fabric was produced and evaluated by the same method as in Example 8, except for this. The number of broken filaments in the test was 0.

[0298] (Example 10)

[0299] The propylene homopolymer (1) having a melting point of 160°C was changed to 94.7 parts by mass, and the polyethylene was changed to 4.0 parts by mass, and otherwise, a spunbond nonwoven fabric was produced and evaluated by the same method as in Example 8. The number of broken filaments in the test was 0.

[0300] (Example 11)

[0301] The propylene homopolymer (1) having a melting point of 160°C was changed to 93.0 parts by mass, the polyethylene was changed to 6.0 parts by mass, and the erucamide was not used, and otherwise, a spunbond nonwoven fabric was produced and evaluated by the same method as in Example 10. The number of broken filaments in the test was 0.

[0302] (Comparative Example 1)

[0303] A mixture of 92.7 parts by mass of a propylene homopolymer (1) having an MFR (determined in accordance with ASTM D1238 at a temperature of 230°C under a load of 2.16 kg) of 60 g / 10 minutes, a density of 0.91 g / cm 3

[0304] 6 parts by mass of a high-density polyethylene (hereinafter, referred to as "polyethylene") having an MFR (determined in accordance with ASTM D1238 at a temperature of 190°C under a load of 2.16 kg) of 5 g / 10 minutes, a density of 0.95 g / cm 3

[0305] 0.3 parts by mass of erucamide

[0306] was melted using an extruder of , a spunbond nonwoven fabric forming machine having a number of holes of 1093 holes (length in the direction perpendicular to the mechanical running direction on the catching surface: 320 mm, refer to Figure 1 ) was used, and under conditions where the resin temperature and the die temperature were both 200°C, the resin discharge amount was 32 kg / h, the cooling air temperature was 20°C, and the stretching air flow wind speed was 3529 m / minute, melt spinning was performed using the spunbond method, it was accumulated on the catching surface, and heating and pressurizing treatment was performed using an embossing roll (embossing area ratio (heat press bonding ratio) 18%, embossing temperature 90°C), and a spunbond nonwoven fabric having a total grammage of 18.0 g / m 2 was produced. The number of broken filaments in the test was 1.

[0307] An image when the cross section of the fiber in the spunbond nonwoven fabric obtained in Comparative Example 1 was observed using a transmission electron microscope is shown in Figure 3 .

[0308] ​​(Comparative Example 2)

[0309] The shape of the stretch part was adjusted so that the fibers were dispersed in the transverse direction (CD) (in detail, the length L (refer to FIG. 2) of the upper and lower directions of the tube part 16b of the stretch part 16 was increased by 50 times), and otherwise, the spunbond nonwoven fabric was produced by the same method as in Example 8 and evaluated. The number of broken filaments in the test was 0. Figure 1 ) was increased by 50 times), and otherwise, the spunbond nonwoven fabric was produced by the same method as in Example 8 and evaluated. The number of broken filaments in the test was 0.

[0310] Note that the tube part 16b of Comparative Example 2 did not contact the moving capture member 21 and the spunbond fiber web 2 formed on the moving capture member 21.

[0311] (Comparative Example 3)

[0312] The product name "HI-WAX (registered trademark) 320P" was changed to a low-crystalline polypropylene homopolymer (manufactured by Shinyeixing Co., Ltd., product name "S400", density: 0.87 g / cm 3 , weight average molecular weight: 45000), and otherwise, the spunbond nonwoven fabric was produced by the same method as in Example 1 and evaluated. The number of broken filaments in the test was 0.

[0313] (Comparative Example 4)

[0314] The propylene homopolymer (1) having a melting point of 160°C was changed to 83.7 parts by mass, the polyethylene was changed to 14.0 parts by mass, and the product name "HI-WAX (registered trademark) 320P" was changed to 2.0 parts by mass, and otherwise, the spunbond nonwoven fabric was produced by the same method as in Example 1 and evaluated. The number of broken filaments in the test was 0.

[0315] [Table 1]

[0316]

[0317] Note that in Table 1, "low-crystalline PP homopolymer" means a low-crystalline polypropylene homopolymer.

[0318] As shown in Table 1, the spunbond nonwoven fabrics of Examples 1 to 11 contained island fibers composed of a resin composition containing a propylene homopolymer and a polyethylene. It was confirmed that the island fibers all had an island structure. The island fibers contained fibers having an island phase ratio of 60% or more on a number basis. The tensile strength ratio (S MD / S CD) was 2.0 to 5.0. Thus, the spunbond nonwoven fabric of Example 1 to Example 11 was evaluated as “A” in terms of the spinnability, and the maximum elongation in the running direction (MD) was greater than 197%. As a result, it was found that the spunbond nonwoven fabric of Example 1 to Example 11 was excellent in the elongation and the spinnability. According to these evaluation results, it was found that the spunbond nonwoven fabric of the present disclosure was excellent in the productivity and was suitable for various uses of the sanitary material requiring secondary processability.

[0319] In contrast, the spunbond nonwoven fabrics of Comparative Example 1 and Comparative Example 3 included island fibers composed of the resin composition containing the propylene homopolymer and the polyethylene. It was confirmed that the island fibers each had the island structure. The island fibers did not include the fiber having the island phase ratio of 60% or more on a number basis. Thus, the spunbond nonwoven fabric of Comparative Example 1 and Comparative Example 3 had the maximum elongation in the running direction (MD) of 197% or less. Furthermore, the spunbond nonwoven fabric of Comparative Example 1 was evaluated as “B” in terms of the spinnability. As a result, it was found that the spunbond nonwoven fabric of Comparative Example 1 and Comparative Example 3 was poor in the elongation and the spinnability.

[0320] The spunbond nonwoven fabrics of Comparative Example 2 and Comparative Example 4 included island fibers composed of the resin composition containing the propylene homopolymer and the polyethylene. The spunbond nonwoven fabric of Comparative Example 2 and Comparative Example 4 had the tensile strength ratio (S MD / S CD ) outside the range of 2.0 to 5.0. Thus, the spunbond nonwoven fabric of Comparative Example 2 and Comparative Example 4 had the maximum elongation in the running direction (MD) of less than 197%. As a result, it was found that the spunbond nonwoven fabric of Comparative Example 2 and Comparative Example 4 was poor in the elongation and the spinnability.

[0321] The entire contents of the disclosure of Japanese Patent Application No. 2021-058789 filed on March 30, 2021 are incorporated herein by reference.

[0322] All literature, patents, and technical standards cited in the present specification are incorporated herein by reference to the same extent as if each individual publication, patent, and technical standard were specifically and individually indicated to be incorporated by reference.

Claims

1. A spun-bonded nonwoven fabric comprising a fiber composed of a resin composition containing a propylene-based polymer (A) and a polymer (B) that is at least one selected from the group consisting of a polyolefin and a polyester, the polyolefin excluding the propylene-based polymer (A), the fiber having an island-in-the-sea structure, the fiber comprising, in an island phase in a cross section orthogonal to an axial direction of the fiber, an island phase having a diameter of less than 0.32 μm at a ratio of 60 or more in number on a number basis. Tensile strength S in the mechanical running direction MD MD Tensile strength S in the direction CD orthogonal to the mechanical running direction MD CD Ratio S MD / S CD is 2.0 to 5.

1.

2. The spun-bonded nonwoven fabric according to claim 1, the propylene-based polymer (A) comprising a propylene homopolymer.

3. The spunbond nonwoven fabric according to claim 1 or 2, the polymer (B) comprising a homopolymer of an α-olefin having 2 to 8 carbon atoms, wherein, the propylene-based polymer (A) is excluded.

4. The spun-bonded nonwoven fabric according to claim 1 or 2, the polymer (B) comprising a polyethylene.

5. The spunbond nonwoven of claim 4, the polyethylene having a density of 0.94 g / cm 3 ~ 0.97 g / cm 3 .

6. The spun-bonded nonwoven fabric according to claim 1 or 2, the island-in-the-sea structure containing a sea phase comprising the propylene-based polymer (A), the island phase comprising the polymer (B).

7. The spunbond nonwoven fabric according to claim 1 or 2, wherein the ratio S MD / S CD is 2.5 to 5.

1.

8. The spun-bonded nonwoven fabric according to claim 1 or 2, the propylene-based polymer (A) being contained at 85.0 to 95.0 mass% relative to the total amount of the resin composition.

9. The spun-bonded nonwoven fabric according to claim 1 or 2, the polymer (B) being contained at 1.0 to 10.0 mass% relative to the total amount of the resin composition.

10. The spun-bonded nonwoven fabric according to claim 1 or 2, the resin composition containing a low-molecular-weight olefin-based polymer having a weight average molecular weight of 500 to 30,000, the low-molecular-weight olefin-based polymer being contained at 0.1 to 5.0 mass% relative to the total amount of the resin composition.

11. The spun-bonded nonwoven fabric according to claim 1 or 2, comprising a thermoplastic elastomer fiber, and being a laminated nonwoven fabric or a mixed fiber nonwoven fabric, the laminated nonwoven fabric being a combination of a spun-bonded fiber web comprising the fiber and a resin layer comprising the thermoplastic elastomer fiber laminated on at least one principal surface of the spun-bonded fiber web, the mixed fiber nonwoven fabric being a combination of the fiber and the thermoplastic elastomer fiber.

12. The spun-bonded nonwoven fabric according to claim 11, the thermoplastic elastomer fiber being a polyurethane-based thermoplastic elastomer fiber or an olefin-based thermoplastic elastomer fiber.

13. A sanitary material comprising the spun-bonded nonwoven fabric according to any one of claims 1 to 12.

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