Spunbond nonwoven fabrics and sanitary materials

Abstract

This spun-bonded nonwoven fabric comprises fibers which are formed of a resin composition that contains a propylene polymer (A) and at least one polymer (B) that is selected from the group consisting of polyolefins (excluding the propylene polymer (A)) and polyesters. The fibers have a sea-island structure. The fibers include those fibers wherein, among the island phases in a cross-section of each fiber, the cross-section being perpendicular to the axial direction of the fiber, the ratio of the island phases having a diameter less than 0.32 μm is 60% or more on a number basis. With respect to this spun-bonded nonwoven fabric, the ratio of the tensile strength (SMD) in the machine direction (MD) to the tensile strength (SCD) in a direction (CD) that is perpendicular to the machine direction (MD), namely SMD / SCD is from 2.0 to 5.1.

Description

[Technical Field]

[0001] The present disclosure relates to spunbond nonwoven fabrics and hygiene materials. [Background technology]

[0002] In recent years, nonwoven fabrics have been widely used in various applications due to their excellent breathability and flexibility. Typical applications of nonwoven fabrics include absorbent articles such as disposable diapers and sanitary napkins, sanitary masks, medical gauze, and base fabrics for compresses. Such nonwoven fabrics are required to have extensibility and other properties from the viewpoint of ease of secondary processing depending on the location where they are used.

[0003] Patent Document 1 discloses a spunbond nonwoven fabric that has good heat-sealing properties and stretch-processability at low temperatures. The spunbond nonwoven fabric disclosed in Patent Document 1 is composed of a specific composition. The specific composition includes a propylene homopolymer having a melting point of 140°C or higher, polyethylene, and at least one polymer selected from a first polymer and a second polymer. The first polymer is a random copolymer of propylene and at least one polymer selected from ethylene and an α-olefin having 4 to 20 carbon atoms. 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.

[0004] Patent Document 1: International Publication No. 2017 / 006972 Summary of the Invention [Problem to be solved by the invention]

[0005] The nonwoven fabric described in Patent Document 1 has excellent heat-sealing properties at low temperatures, but there are cases where further improvement in extensibility is required. Stretchable nonwoven fabrics that require extensibility are often subjected to a stretching process to impart flexibility or to achieve the desired shaping treatment when used as a nonwoven fabric. However, depending on the properties of the nonwoven fabric to be stretched, such a stretching process may cause breakage, making it impossible to achieve the desired processing. In other words, the stretching suitability of the nonwoven fabric to be stretched may not necessarily be sufficient. To provide a spunbond nonwoven fabric that offers an excellent balance between quality and cost, there is a need to further improve the spinnability of the nonwoven fabric described in Patent Document 1.

[0006] In view of the above circumstances, an object of the present disclosure is to provide a spunbond nonwoven fabric and a sanitary material that are excellent in extensibility and spinnability. [Means for solving the problem]

[0007] The means for solving the above problems include the following embodiments.

[0008] <1> a propylene polymer (A); a polymer (B) which is at least one selected from the group consisting of polyolefins (excluding propylene-based polymers (A)) and polyesters; The fiber comprises a resin composition containing The fibers have an island-in-a-sea structure, The fibers include fibers in which, among island phases in a cross section perpendicular to the axial direction of the fibers, the proportion of island phases having a diameter of less than 0.32 μm is 60% or more by number, Tensile strength in the cross direction (CD) (S CD ) to the tensile strength in the machine direction (MD) (S MD ) ratio (S MD / S CD ) is 2.0 to 5.1. <2> The propylene polymer (A) contains a propylene homopolymer. <1> The spunbond nonwoven fabric according to claim 1. <3> The polymer (B) contains a homopolymer of an α-olefin having 2 to 8 carbon atoms (excluding the propylene-based polymer (A)). <1> or <2> The spunbond nonwoven fabric according to claim 1. <4> The polymer (B) includes polyethylene. <1> ~ <3> 10. The spunbond nonwoven fabric according to any one of the preceding items. <5> The density of the polyethylene is 0.94 g / cm 3 ~0.97g / cm 3 The above <4> The spunbond nonwoven fabric according to claim 1. <6> the sea phase contained in the sea-island structure contains the propylene polymer (A), The island phase contains the polymer (B). <1> ~ <5> 10. The spunbond nonwoven fabric according to any one of the preceding items. <7> The ratio (S MD / S CD ) is 2.5 to 5.1, <1> ~ <6> The spunbond nonwoven fabric according to any one of claims 1 to 10. <8> The content of the propylene polymer (A) is 85.0% by mass to 95.0% by mass based on the total amount of the resin composition. <1> ~ <7> 10. The spunbond nonwoven fabric according to any one of the preceding items. <9> The content of the polymer (B) is 1.0 mass % to 10.0 mass % with respect to the total amount of the resin composition. <1> ~ <8> 10. The spunbond nonwoven fabric according to any one of the preceding items. <10> The resin composition contains a low-molecular-weight olefin polymer having a weight-average molecular weight of 500 to 30,000, The content of the low-molecular-weight olefin polymer is 0.1% by mass to 5.0% by mass with respect to the total amount of the resin composition. <1> ~ <9> 10. The spunbond nonwoven fabric according to any one of the preceding items. <11> containing thermoplastic elastomer fibers, It is a laminated nonwoven fabric or a mixed fiber nonwoven fabric, The laminated nonwoven fabric is formed by bonding a spunbond web containing the fibers to a resin layer containing the thermoplastic elastomer fibers and laminated on at least one main surface of the spunbond web, The mixed fiber nonwoven fabric is formed by mixing the fibers and the thermoplastic elastomer fibers. <1> ~ <10> 10. The spunbond nonwoven fabric according to any one of the preceding items. <12> The thermoplastic elastomer fiber is a polyurethane-based thermoplastic elastomer fiber or an olefin-based thermoplastic elastomer fiber. <11> The spunbond nonwoven fabric according to claim 1. <13> The aforementioned <1> ~ <12> A hygiene material comprising the spunbond nonwoven fabric according to any one of the above. [Effects of the Invention]

[0009] According to the present invention, a spunbond nonwoven fabric and a sanitary material having excellent extensibility and spinnability are provided. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing an example of a manufacturing apparatus used in a closed spunbonding method. [Figure 2] 1 is a transmission electron microscope photograph (magnification: 6000 times) of the cross section of a fiber in the spunbond nonwoven fabric of Example 1. [Figure 3] 1 is a transmission electron microscope photograph (magnification: 6000 times) of a cross section of a fiber in the spunbond nonwoven fabric of Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below. The following description of the components may be based on representative embodiments of the present invention, but the present disclosure is not limited to such embodiments.

[0012] In the present disclosure, the term "step" includes not only an independent step, but also a step that cannot be clearly distinguished from other steps as long as the purpose of the step is achieved. In the present disclosure, the content of each component in a thermoplastic resin composition means, when multiple substances corresponding to each component are present in the thermoplastic resin composition, the total amount of the multiple substances present in the thermoplastic resin composition, unless otherwise specified.

[0013] In the present disclosure, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In the present disclosure, in the numerical ranges described stepwise in the "Form for Carrying Out the Invention," the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described stepwise. In the present disclosure, in the numerical ranges described in the "Form for Carrying Out the Invention," the upper or lower limit value of the numerical range may be replaced with the value shown in the "Examples."

[0014] In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.

[0015] (1) Spunbond nonwoven fabric The spunbond nonwoven fabric of the present disclosure comprises: The fiber comprises a resin composition containing a propylene polymer (A) and a polymer (B) which is at least one selected from the group consisting of polyolefins (excluding the propylene polymer (A)) and polyesters, The fibers have an island-in-a-sea structure, The fiber has a cross section perpendicular to the axial direction of the fiber, and the proportion of island phases with a diameter of less than 0.32 μm is Match Contains fibers that account for 60% or more by number, Tensile strength in the direction perpendicular to the machine direction (MD: Machine Direction) (CD: Cross machine direction) CD ) to the tensile strength in the machine direction (MD) (S MD ) ratio (S MD / S CD ) is 2.0 to 5.1.

[0016] In this disclosure, the term "spunbond nonwoven fabric" refers to a nonwoven fabric made by laminating a group of continuous fibers (filaments) spun from a spinneret by melting or dissolving a thermoplastic resin composition onto a moving collecting member (e.g., a net conveyor) using one or more bonding methods. In the present disclosure, the term "sea-island structure" refers to a phase-separated structure in which a phase (island phase) containing one of at least two components exists (e.g., is dispersed) in a continuous phase (sea phase) consisting of the other component. In the present disclosure, the phrase "fibers have an islands-in-a-sea structure" means that the cross section of the fibers cut in a direction perpendicular to the axial direction of the fibers has an islands-in-a-sea structure. In this disclosure, "machine direction (MD)" refers to the direction parallel to the direction of travel of the moving collection member. In the present disclosure, the "direction (CD) perpendicular to the machine direction (MD)" refers to the direction of the surface of the moving collection member that is perpendicular to the direction of travel of the moving collection member.

[0017] Hereinafter, the "fiber having an islands-in-sea structure" may be referred to as "island-in-sea fiber." Hereinafter, "the proportion of island phases with a diameter of less than 0.32 μm among the island phases in the cross section perpendicular to the axial direction of the fiber" may be simply referred to as "island phase proportion." Hereinafter, the "machine direction (MD)" will be referred to as the "machine direction (MD)", and the "direction (CD) perpendicular to the machine direction (MD)" will be referred to as the "cross direction (CD)". Hereafter, "tensile strength in the direction perpendicular to the machine direction (MD) (S CD ) to the tensile strength in the machine direction (MD) (S MD ) ratio (S MD / S CD )" to "Tensile strength ratio (S MD / S CD )" may be used.

[0018] The spunbond nonwoven fabric of the present disclosure has the above-described configuration and is therefore excellent in extensibility and spinnability. "Excellent extensibility" means that the spunbond nonwoven fabric has a first property and a second property. "First property" means that when an external force is applied to the spunbond nonwoven fabric, the outer shape of the spunbond nonwoven fabric stretches in one direction. "Second property" means that the outer shape of the spunbond nonwoven fabric does not easily return to its original shape even when the external force applied to the spunbond nonwoven fabric is released. The quantitative evaluation method for the extensibility of the spunbond nonwoven fabric is the same as the evaluation method described in the Examples. "Excellent spinnability" means that the thermoplastic resin composition, which is the raw material of the spunbonded nonwoven fabric, is less likely to break when it is discharged from the spinneret and during drawing of the continuous fibers, and that fusion of the continuous fibers does not occur. The method for quantitatively evaluating the spinnability of the spunbonded nonwoven fabric is the same as the evaluation method described in the examples.

[0019] The reason why the spunbonded nonwoven fabric of the present disclosure has excellent extensibility and spinnability is not clear, but is presumed to be as follows. When the island phase ratio of the fibers in the spunbonded nonwoven fabric is within the above range, the orientation and crystallization of the propylene polymer (A) is uniformly inhibited within the sea-island composite fibers, thereby improving the extensibility and spinnability of the spunbonded nonwoven fabric. Furthermore, the tensile strength ratio (S MD / S CD ) is within the above range, the dispersion direction of the fibers constituting the spunbonded nonwoven fabric tends to be parallel to the machine direction (MD), which results in excellent extensibility of the resulting spunbonded nonwoven fabric. It is presumed that the synergistic effect of the combination of these factors is the main reason why the spunbonded nonwoven fabric of the present disclosure has excellent extensibility and spinnability.

[0020] (1.1) Tensile strength ratio (S MD / S CD ) The tensile strength ratio (S MD / S CD The tensile strength ratio (S MD / S CDSince the tensile strength ratio (S) is 2.0 to 5.1, the number of fibers oriented parallel to the machine direction (MD) is greater than that in the cross direction (CD). Furthermore, the spunbonded nonwoven fabric has better elongation in the machine direction (MD). MD / S CD ) is 5.0 or less, the tensile strength of the spunbonded nonwoven fabric does not increase too much, and the occurrence of cracks in the fibers constituting the spunbonded nonwoven fabric is suppressed. Tensile strength ratio (S MD / S CD ) may be, for example, 2.0 to 5.0, preferably 2.5 to 5.1, more preferably 2.5 to 5.1, even more preferably 3.0 to 5.0, and particularly preferably 3.5 to 5.0, from the viewpoint of improving the extensibility of the spunbonded nonwoven fabric.

[0021] Tensile strength ratio of spunbond nonwoven fabric (S MD / S CD ) can be measured in accordance with JIS L 1906, 6.12.1 [Method A] (transitioned to JIS L 1913:2010, corresponding to ISO 9073-3:1989), as will be described in detail in the Examples below.

[0022] The machine direction (MD) of a spunbond nonwoven can be determined from the spunbond nonwoven itself by measuring the tensile strength of the spunbond nonwoven. Generally, in the production of spunbond nonwoven fabrics, the moving speed of the moving collection member is set to a high speed from the viewpoint of productivity. Therefore, the continuous fibers tend to be oriented parallel to the machine direction (MD) when they are layered on the moving collection member. As a result, the tensile strength of the spunbond nonwoven fabric in the machine direction (MD) is higher than the tensile strength in the cross direction (CD) of the spunbond nonwoven fabric. Therefore, by measuring the tensile strength of the spunbond nonwoven fabric, the machine direction (MD) of the spunbond nonwoven fabric can be determined from the spunbond nonwoven fabric itself.

[0023] (1.2) Fibers with an island-sea structure Spunbond nonwoven fabrics contain islands-in-the-sea fibers. The sea-island composite fiber is made of a resin composition containing a propylene polymer (A) and a polymer (B) which is at least one selected from the group consisting of polyolefins (excluding the propylene polymer (A)) and polyesters.

[0024] Hereinafter, the propylene polymer (A) may be referred to as "specific polypropylene (A)". Hereinafter, the polymer (B) which is at least one selected from the group consisting of polyolefins (excluding the propylene polymer (A)) and polyesters may be referred to as the "specific polymer (B)".

[0025] The sea-island structure has a sea phase and a plurality of island phases, which are present (for example, dispersed) in the sea phase. The sea phase preferably contains a specific polypropylene (A), and each of the island phases preferably contains a specific polymer (B), which inhibits the oriented crystallization of the main sea phase and allows the spunbonded nonwoven fabric to exhibit extensibility.

[0026] The fiber diameter of the sea-island composite fiber is preferably 4.0d (denier) or less, more preferably 3.5d or less, and even more preferably 3.0d or less.

[0027] Island-sea fiber is a long fiber ( filament ) or single fiber ( Staples The cross-sectional shape of the sea-island composite fiber is not particularly limited, and may be, for example, circular, elliptical, or irregular.

[0028] (1.2.1) Island phase ratio The island phase ratio of the sea-island composite fiber is 60% or more by number. Since the island phase ratio is 60% or more by number, the orientation and crystallization of the specific polypropylene (A) inside the fiber is not easily inhibited unevenly. This results in excellent extensibility and spinnability of the spunbonded nonwoven fabric. From the viewpoint of improving the extensibility of the spunbonded nonwoven fabric, the island phase ratio is preferably 70% by number or more, more preferably 80% by number or more, and even more preferably 90% by number or more, on a number basis.

[0029] There are no particular limitations on the method for making the island phase ratio of the sea-island composite fiber 60% or more by number, and examples thereof include a raw material adjustment method and a manufacturing equipment adjustment method. In the raw material preparation method, the raw material of the sea-island composite fiber is prepared. Specifically, by adding a low molecular weight olefin polymer to the sea-island composite fiber, the island phase ratio can be increased to 60% or more by number. The manufacturing equipment adjustment method involves adjusting the manufacturing equipment for the spunbond nonwoven fabric. Specific examples of manufacturing equipment adjustment methods include selecting a screw with a shape that improves kneading performance, increasing the resin pressure in the die, and increasing the die outlet temperature. These methods can increase the island phase ratio to 60% or more by number.

[0030] The ratio of the island phase area to the total cross-sectional area of ​​the sea-island composite fiber (hereinafter referred to as "island phase area ratio") is preferably 1.0% or more. When the island phase area ratio is 1.0% or more, the oriented crystallization of the specific polypropylene (A) inside the sea-island composite fiber is easily inhibited. The upper limit of the island phase area ratio is preferably 20% or less. When the upper limit of the island phase area ratio is 20% or less, the orientation and crystallization of the specific polypropylene (A) inside the sea-island composite fiber is less likely to be inhibited unevenly, and the spunbonded nonwoven fabric has better extensibility and spinnability. The method for adjusting the island phase area ratio is not particularly limited, and examples thereof include a raw material adjustment method.

[0031] (1.2.2) Fiber material with sea-island structure The sea-island composite fiber in the spunbonded nonwoven fabric is made of a resin composition. The presence of the above components in the resin composition can be confirmed by a known method.

[0032] (1.2.2.1) Specific polypropylene (A) The resin composition of the sea-island composite fiber contains a specific polypropylene (A). The specific polypropylene (A) may be one kind or two or more kinds that differ from each other in melting point, molecular weight, crystal structure, etc.

[0033] The specific polypropylene (A) contains structural units derived from propylene. The specific polypropylene (A) is a propylene homopolymer or a propylene copolymer. The propylene copolymer is preferably a copolymer of propylene and a small amount of one or more α-olefins. The carbon number of the α-olefin in the propylene copolymer is 2 or more (excluding 3 carbon atoms), preferably 2 to 8 (excluding 3 carbon atoms).Specific examples of the α-olefin in the propylene copolymer include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene. Among these, the specific polypropylene (A) preferably contains a propylene homopolymer, and more preferably is a propylene homopolymer.

[0034] The melting point of the specific polypropylene (A) is preferably 140°C or higher, more preferably 150°C or higher, even more preferably 155°C or higher, and particularly preferably 157°C or higher and 165°C or lower. The melting point of the specific polypropylene (A) is defined as the peak top of the peak observed on the highest temperature side of the melting endothermic curve obtained by holding the polypropylene at -40°C for 5 minutes under a nitrogen atmosphere and then heating it at a rate of 10°C / min using a differential scanning calorimeter (DSC). Specifically, a differential scanning calorimeter (manufactured by Perkin-Elmer, product name: DSC-7) is used to hold 5 mg of a sample at -40°C for 5 minutes under a nitrogen atmosphere, and then the temperature is raised at 10°C / min. The peak top of the peak observed on the highest temperature side of the melting endothermic curve obtained can be determined.

[0035] The melt flow rate (MFR) of the specific polypropylene (A) is not particularly limited as long as it can melt-spin the thermoplastic resin composition, which is the raw material of the spunbond nonwoven fabric, and is preferably 1 g / 10 min to 1000 g / 10 min, more preferably 5 g / 10 min to 500 g / 10 min, and even more preferably 10 g / 10 min to 100 g / 10 min. The melt flow rate of the specific polypropylene (A) is measured by a method in accordance with ASTM standard D-1238. The measurement conditions for the melt flow rate of the specific polypropylene (A) are 230°C and a load of 2.16 kg.

[0036] The content of the specific polypropylene (A) relative to the total amount of the resin composition is preferably 55.0 mass% to 95.0 mass%, more preferably 65.0 mass% to 95.0 mass%, even more preferably 75.0 mass% to 95.0 mass%, and particularly preferably 85.0 mass% to 95.0 mass%. When the content of the specific polypropylene (A) is within the above range, the extensibility of the spunbonded nonwoven fabric is improved, and the spunbonded nonwoven fabric has a low basis weight and is soft while maintaining the tensile strength of the spunbonded nonwoven fabric within a good range. In particular, when the content of the specific polypropylene (A) is 85.0 to 95.0 mass%, excessive aggregation of the island phases is suppressed, and the extensibility and spinnability of the spunbonded nonwoven fabric can be compatible. When the content of the specific polypropylene (A) is within the above range, the specific polypropylene (A) is contained in the sea phase, and the specific polymer (B) is contained in the island phase.

[0037] Commercially available products may be used as long as they satisfy the above-mentioned specific polypropylene (A) of the present disclosure.

[0038] (1.2.2.2) Specific polymer (B) The sea-island composite fiber contains a specific polymer (B). The specific polymer (B) may be one kind or two or more kinds that differ from each other in melting point, molecular weight, crystal structure, etc.

[0039] The specific polymer (B) is at least one selected from the group consisting of polyolefins (excluding the propylene polymer (A)) and polyesters.

[0040] The polyolefin (excluding the propylene polymer (A)) is a homopolymer or copolymer of an α-olefin. The α-olefin is an α-olefin having 2 or more carbon atoms (excluding 3 carbon atoms), and preferably includes 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). Specific examples of the α-olefin include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene. Of these, the α-olefin is preferably ethylene. Specific examples of polyolefins (excluding the propylene polymer (A)) include polyethylene (ethylene homopolymer), ethylene-α-olefin copolymer, propylene polymer, 1-butene polymer, and poly(4-methyl-1-pentene). Examples of polyethylene include high-pressure low-density polyethylene, linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE). Examples of ethylene-α-olefin copolymers include ethylene-propylene random copolymers and ethylene-1-butene random copolymers. Examples of the propylene polymer include propylene-ethylene random copolymer, propylene-ethylene-1-butene random copolymer, propylene block copolymer, and propylene-1-butene random copolymer. Examples of the 1-butene polymer include 1-butene homopolymer, 1-butene-ethylene copolymer, and 1-butene-propylene copolymer.

[0041] The polyester may be, for example, an aliphatic polyester or a polyester copolymer, such as a copolymer of an aliphatic dicarboxylic acid alone or a mixture of an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid, and one or more diols.

[0042] Among these, the specific polymer (B) preferably contains polyethylene, and more preferably is polyethylene.

[0043] The density of the polyethylene is preferably 0.94 g / cm from the viewpoint of improving the tensile strength of the spunbonded nonwoven fabric and from the viewpoint of the extensibility and flexibility of the spunbonded nonwoven fabric. 3 ~0.98g / cm 3 , more preferably 0.94 g / cm 3 ~0.97g / cm 3 is.

[0044] The melting point of the specific polymer (B) is preferably 150°C or higher, more preferably 155°C or higher, and even more preferably 155°C to 165°C.

[0045] The melt flow rate of the specific polymer (B) is not particularly limited as long as it can spin a melt of the thermoplastic resin composition, which is the raw material of the spunbonded nonwoven fabric, and is preferably 1 g / 10 min to 1000 g / 10 min. minutes, The range is more preferably 2 g / 10 minutes to 500 g / 10 minutes, and even more preferably 3 g / 10 minutes to 100 g / 10 minutes. When the specific polymer (B) is polyethylene, the melt flow rate is measured by a method in accordance with ASTM standard D-1238. The measurement conditions for the melt flow rate of polyethylene are 190°C and a load of 2.16 kg.

[0046] The content of the specific polymer (B) is preferably 1.0 to 10.0% by mass, more preferably 3.0 to 8.0% by mass, and even more preferably 5.0 to 7.0% by mass, based on the total amount of the resin composition. When the content of the specific polymer (B) is within the above range, the extensibility of the spunbonded nonwoven fabric is improved.

[0047] (1.2.2.3) Low molecular weight olefin polymers The resin composition preferably contains a low-molecular-weight olefin polymer having a weight-average molecular weight of 500 to 30,000, and 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. The low-molecular-weight olefin polymer may be one type, or two or more types different from each other in melting point, molecular weight, crystal structure, etc.

[0048] When the sea-island composite fiber contains a low molecular weight olefin polymer, and the content of the low molecular weight olefin polymer is within the above range, the dispersibility of the specific polypropylene (A) and the specific polymer (B) is improved, which results in improved extensibility and spinnability of the spunbonded nonwoven fabric.

[0049] When the sea-island composite fiber contains a low molecular weight olefin polymer, the content of the low molecular weight olefin polymer is preferably 0.1 to 5.0 mass% based on the total amount of the resin composition. The lower limit of the content of the low-molecular-weight olefin polymer is more preferably 0.2% by mass or more, even more preferably 1.0% by mass or more, and particularly preferably 1.5% by mass or more, based on the total amount of the resin composition, from the viewpoint of ensuring that a sufficient amount of the low-molecular-weight olefin polymer is present at the interface between the sea phase and the island phase in order to improve the dispersibility of the specific polypropylene (A) and the specific polymer (B). End is. The upper limit of the low molecular weight olefin polymer content is more preferably 4.0 mass% or less, even more preferably 3.0 mass% or less, and particularly preferably 2.5 mass% or less, based on the total amount of the resin composition, in order to prevent a significant decrease in strength of the sea-island composite fiber.

[0050] The low-molecular-weight olefin polymer may contain structural units derived from one type of olefin, or structural units derived from two or more types of olefins.

[0051] The low-molecular-weight olefin polymer is a wax-like polymer, in other words, the weight-average molecular weight (Mw) of the low-molecular-weight olefin polymer is lower than that of the specific polypropylene (A) and the poly-α-olefin.

[0052] The low-molecular-weight olefin polymer has a weight-average molecular weight (Mw) of 500 to 30,000. When the weight average molecular weight (Mw) of the low molecular weight olefin 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 extensibility and Bisou The threadability is better. The upper limit of the weight average molecular weight (Mw) of the low molecular weight olefin polymer is 30,000 or less, preferably less than 15,000, more preferably 10,000 or less, even more preferably 6,000 or less, particularly preferably less than 6,000, even more preferably 5,000 or less, even more preferably 3,000 or less, even more preferably 2,000 or less, and even more preferably 1,500 or less. The lower limit of the weight average molecular weight (Mw) of the low molecular weight olefin polymer is 500 or more, preferably 700 or more, and more preferably 1,000 or more.

[0053] The weight-average molecular weight (Mw) of the low-molecular-weight olefin polymer may be measured by gel permeation chromatography (GPC). The measurement conditions for GPC are preferably the first measurement conditions shown below. The weight-average molecular weight (Mw) of the low-molecular-weight olefin polymer is measured, for example, by preparing a calibration curve using commercially available monodisperse standard polystyrene and then using the following conversion method.

[0054] [First measurement condition] Apparatus: Gel permeation chromatograph Alliance GPC2000 (Waters) Solvent: o-dichlorobenzene Columns: TSKgel GMH6-HT x 2 (Tosoh Corporation), TSKgel GMH6-HTL columns x 2 (Tosoh Corporation) Flow rate: 1.0ml / min Sample: 0.15 mg / mL Lo-dichlorobenzene solution Temperature: 140℃ Molecular weight conversion: Polyethylene (PE) conversion / general calibration method

[0055] The universal calibration calculation used the coefficients of the Mark-Houwink viscosity equation shown below. Modulus of polystyrene (PS): KPS = 1.38 x 10 -4 , aPS=0.70 Coefficient of polyethylene (PE): KPE = 5.06 x 10 -4 , aPE=0.70

[0056] The softening point of the low molecular weight olefin polymer is preferably 90°C to 145°C, more preferably 90°C to 135°C, and even more preferably 100°C to 125°C. The softening point of the low-molecular-weight olefin polymer is measured in accordance with JIS K2207.

[0057] The density of the low molecular weight olefin polymer is not particularly limited, but is preferably 0.890 g / cm 3 ~0.980g / cm 3 is. If the density of the low-molecular-weight olefin polymer is within the above range, the extensibility of the spunbonded nonwoven fabric will be superior. The lower limit of the density of the low molecular weight olefin polymer is more preferably 0.910 g / cm 3 More preferably, 0.920 g / cm 3 That's all. The upper limit of the density of the low molecular weight olefin polymer is more preferably 0.960 g / cm 3 or less, more preferably 0.940 g / cm 3 The following is the result. The density of the low-molecular-weight olefin polymer is measured in accordance with JIS K7112.

[0058] The difference between the density of the low-molecular-weight olefin polymer and the density of the specific polypropylene (A) is not particularly limited, and is preferably 0.35 g / cm 3less than 0.20 g / cm 3 less than 0.15 g / cm 3 is less than. When the difference between the density of the low-molecular-weight olefin polymer and the density of the specific polypropylene (A) is within the above range, the extensibility of the spunbonded nonwoven fabric is superior. The reason for this is not clear, but is thought to be as follows. When the density of the low-molecular-weight olefin polymer and the density of the specific polypropylene (A) are within the above ranges, it is thought that, for example, the specific polymer (B) is easily dispersed in the specific polypropylene (A) via the low-molecular-weight olefin polymer. In other words, the low-molecular-weight olefin polymer effectively acts 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. As a result, it is thought that the extensibility of the spunbond nonwoven fabric is improved.

[0059] The low molecular weight olefin polymer is an olefin homopolymer or an olefin copolymer made of two or more kinds of olefins. Among these, the low-molecular-weight olefin polymer may be either a homopolymer of ethylene or a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. The α-olefin preferably has 3 to 8 carbon atoms, and more preferably 3 to 4 carbon atoms. When the carbon number of the α-olefin is within the above range, the extensibility and spinnability of the spunbonded nonwoven fabric are improved. The reason for this is not clear, but is thought to be as follows. When the carbon number of the α-olefin is within the above range, it is considered that, for example, the specific polymer (B) is easily dispersed in the specific polypropylene (A) via the low-molecular-weight olefin-based polymer. That is, the low-molecular-weight olefin-based polymer acts as a compatibilizer for the specific polypropylene (A) and the polyα-olefin. Therefore, the specific polypropylene (A) and the specific polymer (B) are easily dispersed in the specific polypropylene (A) via the low-molecular-weight olefin-based polymer. )of The uniformity is improved, which is thought to result in improved properties such as elongation of the spunbonded nonwoven fabric. The low molecular weight olefin polymer may be used alone or in a mixture of two or more kinds thereof.

[0060] The method for producing the low-molecular-weight olefin polymer is not particularly limited, and examples thereof include the first production method and the second production method. 。 The first production method is a commonly used production method using polymerization of a low molecular weight polymer, and the second production method is a method in which the molecular weight of a high molecular weight ethylene polymer is reduced by thermal degradation. The low-molecular-weight olefin polymer may be purified by solvent fractionation, which separates the polymers based on the difference in solubility in a solvent, or by distillation. The first production method includes, for example, a production method using a Ziegler-Natta catalyst or a metallocene catalyst, etc. Production methods using a metallocene catalyst, etc. include production methods described in JP-A-08-239414, WO 2007 / 114102, etc.

[0061] The low-molecular-weight olefin polymer may be a commercially available product. Examples of commercially available low-molecular-weight olefin polymers include "HIWAX (registered trademark) 320P," "EXCEREX (registered trademark) 30200B," "HIWAX (registered trademark) 100P," and "HIWAX (registered trademark) 110P," manufactured by Mitsui Chemicals, Inc.

[0062] (1.2.2.4) Fatty acid amides The sea-island composite fiber preferably contains a fatty acid amide having 15 to 22 carbon atoms, and the content of the fatty acid amide is preferably 0.1 to 5.0 mass% based on the total mass of the resin composition. The fatty acid amide may be one type or two or more types. This allows the fatty acid amide having 15 to 22 carbon atoms to be adsorbed onto the fiber surface of the spunbonded nonwoven fabric, modifying the surface of the sea-island composite fiber. In other words, the softness, touch, blocking resistance, etc. of the spunbonded nonwoven fabric are further improved. This is thought to more effectively prevent the nonwoven fabric fibers from adhering to various rotating devices and other components in the equipment used in the embossing process, etc. As a result, the extensibility and softness of the spunbonded nonwoven fabric are further improved.

[0063] In the present disclosure, the "number of carbon atoms in the fatty acid amide" means the number of carbon atoms contained in the molecule, and the carbon atom in -CONH constituting the amide is included in the above number of carbon atoms. The fatty acid amide preferably has 18 to 22 carbon atoms. Examples of fatty acid amides having 15 to 22 carbon atoms include fatty acid monoamide compounds, fatty acid diamide compounds, saturated fatty acid monoamide compounds, and unsaturated fatty acid diamide compounds. Among these, preferred examples include palmitic acid amide (number of carbon atoms: 16), stearic acid amide (number of carbon atoms: 18), oleic acid amide (number of carbon atoms: 18), and erucic acid amide (number of carbon atoms: 22).

[0064] The content of the fatty acid amide having 15 to 22 carbon atoms is preferably 0.1 to 5.0 mass%, more preferably 0.1 to 3.0 mass%, and even more preferably 0.1 to 1.0 mass%, relative to the total amount of the resin composition.

[0065] (1.2.2.6) Additives The sea-island composite fiber may optionally contain additives such as antioxidants, heat stabilizers, weather stabilizers, antistatic agents, slip agents, hydrophilic agents, anti-fogging agents, lubricants, dyes, pigments, natural oils, synthetic oils, waxes, and fatty acid amides, provided that the additives do not impair the objectives of the present disclosure.

[0066] (1.3) Composition of spunbond nonwoven fabric The spunbond nonwoven fabric may be composed of only sea-island fibers, or may be composed of sea-island fibers and fibers without a sea-island structure. When the spunbonded nonwoven fabric is composed of sea-island fibers and fibers without a sea-island structure, the content of the sea-island fibers is preferably 5 to 95 mass%, more preferably 15 to 90 mass%, even more preferably 30 to 85 mass%, and particularly preferably 40 to 70 mass%, based on the total amount of the spunbonded nonwoven fabric, in order to exhibit the above-mentioned effects of the spunbonded nonwoven fabric.

[0067] When the spunbonded nonwoven fabric is composed only of islands-in-the-sea fibers, the basis weight of the spunbonded nonwoven fabric is preferably 30 g / m2 in order to achieve both flexibility and tensile strength. 2 or less, more preferably 28 g / m 2 or less, more preferably 25 g / m 2 Below 5 g / m, particularly preferably 2 ~20g / m 2 is. When spunbond nonwoven fabric is used for sanitary materials, etc., as described below, the basis weight of the spunbond nonwoven fabric is 5 g / m 2 ~19g / m 2 It is preferable that the temperature is in the range of

[0068] Spunbond nonwoven fabrics are made of elastic spunbond fibers. attitude That's fine. The elastic spunbond fiber is preferably a fiber produced by the spunbonding method, in which a resin containing a specific thermoplastic polyurethane elastomer is extruded. The specific thermoplastic polyurethane elastomer has a solidification onset temperature of at least 65°C as measured by a differential scanning calorimeter (DSC), and has a polar solvent insoluble particle count of 3 million particles / g or less as measured using a particle size distribution analyzer based on the electrical capillary resistance method equipped with a 100-micron aperture. Stretchable spunbond fibers having the above properties can be produced, for example, by the methods described in WO 2004 / 065680 and WO 2011 / 129433. When the spunbond nonwoven fabric comprises elastic spunbond fibers, the spunbond nonwoven fabric may be a laminated nonwoven fabric as described below, or a mixed fiber nonwoven fabric as described below.

[0069] The spunbond nonwoven fabric may be a laminated nonwoven fabric or a mixed fiber nonwoven fabric depending on the purpose.

[0070] (1.3.1) Laminated nonwoven fabric The laminated nonwoven fabric is formed by bonding a spunbond web and a resin layer. The resin layer is laminated on at least one surface of the spunbond web. The spunbond web contains sea-island fibers. The method for bonding the spunbond web and the resin layer may be any known bonding method.

[0071] In this disclosure, the term "spunbond web" refers to a web made by extruding a molten or dissolved thermoplastic resin composition through a spinneret and layering the continuous fibers (filaments) on a moving collection member (e.g., a net conveyor). Spunbond webs differ from spunbond nonwoven fabrics in that the fibers that make up the spunbond web are not bonded to each other.

[0072] The layer structure of the laminated nonwoven fabric is not particularly limited as long as there is one spunbond web and one resin layer. In the laminated nonwoven fabric, the spunbond web may be one layer or two or more layers. In the laminated nonwoven fabric, the resin layer may be one layer or two or more layers.

[0073] The basis weight of the laminated nonwoven fabric is preferably 100 g / m from the viewpoint of achieving both flexibility and tensile strength of the laminated nonwoven fabric. 2 Less than 90 g / m 2 or less, more preferably 80 g / m 2 The following is the result. When the laminated nonwoven fabric is used for sanitary materials, etc., as described below, the basis weight of the laminated nonwoven fabric is 20 g / m 2 ~70g / m 2 It is preferable that the temperature is in the range of

[0074] The material of the resin layer may be different from the thermoplastic resin composition that is the material of the sea-island composite fiber. Examples of the resin layer include knitted fabric, woven fabric, web, nonwoven fabric, and film. Examples of nonwoven fabrics that are resin layers include spunbond nonwoven fabrics, meltblown nonwoven fabrics, wet nonwoven fabrics, dry nonwoven fabrics, dry pulp nonwoven fabrics, flash-spun nonwoven fabrics, and spread nonwoven fabrics. These nonwoven fabrics may be stretchable or non-stretchable. Stretchable nonwoven fabrics have a third property and a fourth property. "Third property" refers to the property that when an external force is applied to the nonwoven fabric, the outer shape of the nonwoven fabric stretches in one direction. "Fourth property" refers to the property that when the external force applied to the nonwoven fabric is released, the outer shape of the nonwoven fabric returns to its original shape. An example of the stretchable nonwoven fabric is the elastic nonwoven fabric made of low-crystalline polypropylene described in WO 2012 / 070518. Examples of webs that are resin layers include spunbond webs and meltblown webs. , damp Examples of such webs include dry-laid webs, dry-laid pulp webs, flash-spun webs, and spread webs. These webs may be elastic or non-elastic.

[0075] When breathability is required for the laminated nonwoven fabric, the film, which is an example of a resin layer, is preferably a breathable film or a moisture-permeable film. Examples of breathable films include films made of thermoplastic elastomers, porous films, etc. Examples of thermoplastic elastomers that are raw materials for films include moisture-permeable polyurethane elastomers, polyester elastomers, polyamide elastomers, etc. The porous film is made by stretching a film made of a thermoplastic resin containing inorganic or organic fine particles to make it porous. Preferred thermoplastic resins as raw materials for the porous film are polyolefins such as high-pressure low-density polyethylene, linear low-density polyethylene (so-called LLDPE), high-density polyethylene, polypropylene, polypropylene random copolymers, and combinations thereof. When breathability is not required for the laminated nonwoven fabric, one or more thermoplastic resins selected from polyethylene, polypropylene, etc. may be used as the raw material for the film, which is an example of the resin layer. Fat It can be used.

[0076] The laminated nonwoven fabric is preferably partially heat-sealed. Examples of heat-sealing methods for partially heat-sealing the laminated nonwoven fabric include a method using ultrasonic waves, a heat embossing process using an embossing roll, and a hot air through method. Laminated nonwoven fabric The heat embossing is preferred in that the long fibers are efficiently stretched when the sheet is stretched.

[0077] By heat embossing Laminated nonwoven fabric When only a portion of the surface is heat-sealed, the embossed area ratio is preferably 5% to 30%, and more preferably 5% to 20%. Examples of the stamped shape include a circle, ellipse, oval, square, diamond, rectangle, and rectangle, as well as continuous shapes based on these shapes. The embossing temperature in the hot embossing process is adjusted appropriately depending on the line speed, pressure during embossing, etc., and is preferably 85°C to 150°C.

[0078] When the resin layer is a knitted fabric, a woven fabric, a web, or a nonwoven fabric, the resin layer preferably contains thermoplastic elastomer fibers. By including thermoplastic elastomer fibers in the resin layer, it is possible to produce a stretchable nonwoven fabric that does not cause blocking.

[0079] The material of the thermoplastic elastomer fiber is not particularly limited as long as it is 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 the property of preventing plastic deformation. Examples of thermoplastic elastomer fibers include polyurethane-based thermoplastic elastomer fibers, olefin-based thermoplastic elastomer fibers, styrene-based thermoplastic elastomer fibers, polyester-based thermoplastic elastomer fibers, polyamide-based thermoplastic elastomer fibers, etc. Among these, from the viewpoints of the stretchability and spinning stability of the laminated nonwoven fabric, the thermoplastic elastomer fibers are preferably thermoplastic polyurethane fibers or olefin-based thermoplastic elastomer fibers.

[0080] Materials for polyurethane thermoplastic elastomer fibers include: (1) A method of reacting an isocyanate-terminated prepolymer, which is prepared by preliminarily reacting a polyol with an isocyanate compound, with a chain extender; (2) Polyurethanes produced by a method in which a polyol and a chain extender are mixed in advance and then the mixture is reacted with an isocyanate compound. Examples of polyols, which are one of the components constituting the polyurethane-based thermoplastic elastomer, include polyoxyalkylene polyols, polytetramethylene ether glycols, polyester polyols, polycaprolactone polyols, and polycarbonate diols. The isocyanate compound may be an aromatic, aliphatic or alicyclic compound having two or more isocyanate groups in one molecule. Examples of the chain extender include aliphatic, aromatic, heterocyclic or alicyclic low molecular weight polyols having two or more hydroxyl groups in one molecule. Specifically, examples of polyurethane-based thermoplastic elastomer fibers include thermoplastic polyurethane elastomers obtained by using 1,4-bis(2-hydroxyethoxy)benzene as a chain extender, as described in International Publication No. 2011 / 129433. Examples of materials for olefin-based thermoplastic elastomer fibers include ethylene-α-olefin random copolymers and copolymers with a diene as a second component. Specifically, ethylene-propylene random copolymers, ethylene-1-butene random copolymers, and EPDM (ethylene-propylene-diene copolymers, with a dicyclohexyl olefin as the diene component) are mentioned. P Examples of such olefin-based thermoplastic elastomer fibers include those in which the soft segment is polyethylene or ethylenediaminetetraacetic acid (Ethylenediaminetetraacetic acid) and the hard segment is polyolefin. Examples of such olefin-based thermoplastic elastomer fibers include TAFMER (manufactured by Mitsui Chemicals, Inc.), MILASTOMER (manufactured by Mitsui Chemicals, Inc.), EVAFLEX-EEA (manufactured by DuPont-Mitsui Polychemicals Co., Ltd.), and VISTAMAX (manufactured by ExxonMobil Corporation). Examples of the raw materials for the styrene-based thermoplastic elastomer fibers, polyester-based thermoplastic elastomer fibers, and polyamide-based thermoplastic elastomer fibers include those described in JP-A No. 2001-179867.

[0081] The fiber diameter of the thermoplastic elastomer fiber is preferably 4.0d (denier) or less, more preferably 3.5d or less, and even more preferably 3.0d or less.

[0082] Thermoplastic elastomer fibers are long fibers ( filament ) or single fiber ( Staples Furthermore, the cross-sectional shape of the thermoplastic elastomer fiber is not particularly limited, and examples thereof include a circular, elliptical, and irregular cross-section.

[0083] (1.3.2) Mixed fiber nonwoven fabric The mixed fiber nonwoven fabric contains thermoplastic elastomer fibers. The mixed fiber nonwoven fabric is made by mixing sea-island fibers and thermoplastic elastomer fibers.

[0084] The mixed fiber ratio of the sea-island composite fiber is not particularly limited, but is preferably 5 to 95% by mass, more preferably 25 to 75% by mass, and even more preferably 40 to 60% by mass.

[0085] "Bulk fiber ratio" refers to the proportion of a specific type of fiber in a nonwoven fabric made from a blend of two or more types of fibers, or the blend ratio of various fibers in the nonwoven fabric. That is, in a blended nonwoven fabric made from sea-island fiber and thermoplastic elastomer fiber, the "bulk fiber ratio of sea-island fiber" is {mass of sea-island fiber ÷ (mass of sea-island fiber + mass of thermoplastic elastomer fiber)}. The "bulk fiber ratio of thermoplastic elastomer fiber" is {mass of thermoplastic elastomer fiber ÷ (mass of sea-island fiber + mass of thermoplastic elastomer fiber)}.

[0086] The weight of the mixed fiber nonwoven fabric is preferably 100 g / m from the viewpoint of achieving both flexibility and tensile strength of the mixed fiber nonwoven fabric. 2 Less than 90 g / m 2 More preferably, 80 g / m or less 2 The following is the result. When the mixed fiber nonwoven fabric is used for sanitary materials, etc., as described later, the weight of the mixed fiber nonwoven fabric is 20 g / m 2 ~70g / m 2 It is preferable that the temperature is in the range of

[0087] Examples of the thermoplastic elastomer fibers include the same ones as those exemplified as the thermoplastic elastomer fibers that can be contained in the resin layer of the laminated nonwoven fabric.

[0088] (2) Hygiene materials The hygiene material of the present disclosure includes the spunbond nonwoven fabric of the present disclosure. The spunbond nonwoven fabric of the present disclosure has excellent extensibility, and therefore the hygienic material of the present disclosure has excellent extensibility.

[0089] The sanitary material is suitable for use in various sanitary material applications requiring extensibility and flexibility, specifically, for absorbent articles such as disposable diapers and sanitary napkins, medical sanitary materials such as bandages, medical gauze and towels, and sanitary masks.

[0090] (3) Manufacturing method of spunbond nonwoven fabric The spunbond nonwoven fabric of the present disclosure is produced by a conventional method using a thermoplastic resin composition as a raw material. The spunbond nonwoven fabric of the present disclosure is produced, for example, as follows. That is, the thermoplastic resin composition is introduced into an extruder and melted. The molten thermoplastic resin composition is spun using a spunbond nonwoven fabric molding machine having multiple spinnerets. The resulting continuous fibers are stretched by controlling the air volume with a blower or the like. During this process, the continuous fibers are cooled as necessary. The continuous fibers are then deposited on the collecting surface of the spunbond nonwoven fabric molding machine to obtain a spunbond web. The resulting spunbond web is then heated and pressurized using an embossing roll. This results in a spunbond nonwoven fabric.

[0091] The thermoplastic resin composition has the same composition as the above-mentioned example of the sea-island composite fiber.

[0092] An example of a method for producing a spunbonded nonwoven fabric will be described in detail below with reference to the drawings. Fig. 1 is a schematic diagram showing an example of a production apparatus used in the closed-type spunbonding method, in which continuous fibers formed by melt-spinning a thermoplastic resin composition are stretched while being cooled in a closed space.

[0093] The closed spunbond manufacturing apparatus 100 shown in FIG. 1 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 drawing section 16. The extruder 11 extrudes a thermoplastic polymer. The spinneret 12 spins a melt of the thermoplastic polymer. The cooling chamber 13 cools the continuous fiber group 1 spun from 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 drawing section 16. The drawing section 16 draws the continuous fiber group 1.

[0094] 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. 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 and spun. As a result, a group of continuous fibers 1 is formed. The continuous fiber group 1 is introduced into the cooling chamber 13. The continuous fiber group 1 introduced into the cooling chamber 13 is cooled by cooling air A. The cooling air A is supplied into the cooling chamber 13 and the stretching section 16 from at least one of a cooling air supply section 14 and a cooling air supply section 15. The cooled continuous fiber group 1 is introduced into the stretching section 16 located downstream of the cooling chamber 13. The stretching section 16 has a narrow passage section 16a and a cylindrical section 16b. The cylindrical section 16b is formed at the end of the narrow passage section 16a on the lower side (i.e., on the mobile collection member 21 side) in the vertical direction (i.e., in the direction of gravity) of the narrow passage section 16a. The narrow passage section 16a is narrow. The cylindrical section 16b is cylindrical. The hollow section of the cylindrical section 16b widens downward as shown in FIG. 1 . The continuous fiber group 1 introduced into the stretching section 16 is stretched by increasing the speed of the cooling air in the narrow passage section 16a. After being stretched, the continuous fiber group 1 passing through the cylindrical section 16b is dispersed and collected on the mobile collection member 21. The dispersed continuous fiber group 1 is efficiently suctioned onto the moving collection member 21 by the suction unit 22. Captivity The suction unit 22 is a part of the moving collection member 21. Captivity The spunbond web 2 is formed by the spunbonding process. Thereafter, the fibers contained in the spunbond web 2 are bonded by, for example, heat and pressure treatment using an embossing roll (not shown), thereby obtaining a spunbond nonwoven fabric.

[0095] Although the closed spunbonding method has been described as an example of the method for producing the spunbonded nonwoven fabric of the present disclosure, the method for producing the spunbonded nonwoven fabric of the present disclosure is not limited to the closed spunbonding method. The spunbonded nonwoven fabric of the present disclosure may also be produced by the open spunbonding method. In the open spunbonding method, continuous fibers melt-spun with a thermoplastic resin composition are cooled.

[0096] 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 melting temperature of the thermoplastic resin composition and lower than the thermal decomposition temperature of the thermoplastic resin composition, and is set appropriately depending on the physical properties of the thermoplastic resin composition, etc.

[0097] The temperature of the spinneret 12 is adjusted appropriately depending on the physical properties of the thermoplastic resin composition, etc. Taking into consideration 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 even more preferably 200°C to 225°C.

[0098] The hole diameter of the spinneret 12 is not particularly limited, but is preferably 0.05 mm to 1.00 mm from the viewpoint of the extensibility of the spunbonded nonwoven fabric.

[0099] The rate of melted thermoplastic resin composition discharged per hole from the spinneret 12 is preferably 0.1 g / min to 3.0 g / min, more preferably 0.3 g / min to 1.0 g / min, from the viewpoint of the extensibility of the spunbonded nonwoven fabric.

[0100] The temperature of the cooling air used to cool the continuous fibers extruded from the spinneret is not particularly limited as long as it is a temperature at which the thermoplastic resin composition solidifies, and is preferably 5°C to 50°C, more preferably 10°C to 40°C, and even more preferably 15°C to 30°C.

[0101] In the method for producing a spunbonded nonwoven fabric according to the present disclosure, the fibers contained in the spunbonded nonwoven fabric may be partially heat-fused. The fibers contained in the spunbonded nonwoven fabric may be compressed using nip rolls before being heat-fused. [Example]

[0102] Hereinafter, the embodiments of the present disclosure will be described in more detail based on examples, but the present invention is not limited to these examples, which are one embodiment of the present disclosure.

[0103] The physical properties of the spunbond nonwoven fabrics in the examples and comparative examples were measured by the following methods.

[0104] (1) Weight [g / m 2 〕 Ten test pieces measuring 300 mm in the machine direction (MD) and 250 mm in the cross direction (CD) were taken from the spunbond nonwoven fabric. The test pieces were taken from 10 randomly selected locations on the spunbond nonwoven fabric. The mass (g) of each test piece was then measured using a top-pan electronic balance (manufactured by Kensei Kogyo Co., Ltd.). The average mass of each test piece was calculated. A 1m difference was calculated from the calculated average mass. 2 The weight of the spunbond nonwoven fabric is calculated by converting it into the mass (g) per unit area and rounding off to the nearest whole number. 2 〕

[0105] (2) Maximum elongation, tensile strength (maximum strength), and tensile strength ratio (S MD / S CD ) Five test specimens measuring 25 cm in the machine direction (MD) and 5 cm in the cross direction (CD) were taken from the spunbond nonwoven fabric in accordance with JIS L 1906, 6.12.1 [Method A] (transitioned to JIS L 1913:2010, corresponding to ISO 9073-3:1989) in a constant temperature room at 20±2°C and 65±2% humidity, as specified in JIS Z 8703 (standard conditions for the test location). Tensile tests were performed on the obtained test specimens using a tensile testing machine (Instron Japan Co., Ltd., Instron Model 5564) at a temperature of 20±2°C, a chuck gap of 100 mm, and a tensile speed of 300 mm / min. The tensile loads of the five test specimens were measured, and the average of the maximum values ​​was taken as the tensile strength (maximum strength) in the machine direction (MD) [N / 50 mm]. The elongation at the tensile strength (maximum strength) was defined as the maximum elongation [%] and was used as an index to evaluate extensibility. When measuring the tensile strength and maximum elongation in the cross direction, five test pieces measuring 25 cm in the cross direction (CD) and 5 cm in the machine direction (MD) were taken and tensile tests were performed under the same conditions. Specifically, the maximum elongation [%] in the machine direction was calculated using the following formula: Formula: Maximum elongation [%] = {(maximum length - 25 cm) / 25 cm} x 100 In the formula, "maximum length" refers to the length (cm) of the test piece when the tensile strength is measured on the long side of the test piece. Tensile strength ratio (S MD / S CD ) is the obtained tensile strength in the machine direction (MD) (S MD ) and transverse direction (CD) tensile strength (S CD ) was calculated from the measured values.

[0106] (3) Fiber diameter Ten 10mm x 10mm test pieces were taken from the spunbond nonwoven fabric, and the fiber diameters were measured in μm units to the first decimal place using a Nikon ECLIPSE E400 microscope at 20x magnification. The diameters were measured at 20 random locations on each test piece, and the average value was calculated.

[0107] (4) Confirmation of sea-island structure and proportion of island phase (%) Fibers were extracted from the spunbond nonwoven fabric and embedded in paraffin to prepare a measurement sample. The measurement sample was then placed in a microtome with the blade parallel to the direction perpendicular to the fiber axis, and sliced ​​along the direction perpendicular to the fiber axis. The sliced ​​fibers were then reinforced with carbon, and the cross-sections of the sliced ​​fibers were observed using a transmission electron microscope (TEM). The sea-island structure was observed in the fiber cross-section. The continuous phase was defined as the sea phase, and the dispersed phase as the island phase. The diameters of the island phases within the observation range (cross-section) were measured. The number of island phases with a diameter of 0.32 μm or more and the number of island phases with a diameter of less than 0.32 μm were counted. The number of island phases falling within each range was divided by the number of island phases within the observation range (cross-section) to calculate the ratio (i.e., the island phase ratio). The transmission electron microscope used here was a transmission electron microscope model H-7650 manufactured by Hitachi High-Tech Corp. The observation magnification was 6000 times. The diameter of the island phase was determined by image analysis using Mac-View (Mountec Co., Ltd.). Specifically, the major and minor axes of the island phase were measured, and the average value was taken as the diameter. The island phase area ratio was calculated by dividing the total area of ​​the island phases by the total cross-sectional area of ​​the sea-island composite fiber.

[0108] (5) Evaluation of spinnability During the spinning of the spunbond nonwoven fabrics shown in the Examples, the number of thread breakages that occurred within 30 minutes (hereinafter referred to as "number of thread breakages") was measured. Based on the measurement results of the number of thread breakages, the spinnability was evaluated according to the following criteria. An acceptable evaluation of spinnability is "A." A: The number of thread breakages was 0. B: The number of thread breakages was 1 to 3. C: The thread broke four or more times.

[0109] Example 1 <Manufacturing of spunbond nonwoven fabrics> MFR (measured in accordance with ASTM D1238 at 230°C and 2.16 kg load) 60 g / 10 min, density 0.91 g / cm 3 92.7 parts by mass of propylene homopolymer (1) having a melting point of 160 ° C., MFR (measured in accordance with ASTM D1238 at 190°C and 2.16 kg load) 5 g / 10 min, density 0.95 g / cm 3 6.0 parts by mass of high-density polyethylene (hereinafter referred to as "polyethylene") having a melting point of 134°C, Ethylene-propylene copolymer wax (manufactured by Mitsui Chemicals, Inc., product name "Hiwax® 320P", density: 0.93 g / cm 3 1.0 parts by mass of 1,000 propylene glycol ether, weight average molecular weight: 3000; 0.3 parts by mass of erucic acid amide The mixture was melted using a 75 mm diameter extruder, and melt-spun by the spunbond method using a spunbond nonwoven fabric molding machine with a spinneret having 1,093 holes (length perpendicular to the machine flow direction on the collecting surface: 320 mm, see Figure 1) under the conditions of a resin temperature and die temperature of 200°C, a resin discharge rate of 32 kg / h, a cooling air temperature of 20°C, and a drawing air speed of 3,529 m / min. The mixture was deposited on the collecting surface and subjected to a heat and pressure treatment with an embossing roll (embossed area ratio (thermocompression ratio) of 18%, embossing temperature of 90°C) to produce a total basis weight of 18.0 g / m. 2 The number of times that yarn breakage occurred during the test was 0. FIG. 2 shows an image of the cross section of the fiber in the spunbonded nonwoven fabric obtained in Example 1 observed with a transmission electron microscope.

[0110] Example 2 91.7 parts by mass of propylene homopolymer (1) with a melting point of 160 ° C., product name "HIWAX (registered trademark) 320P" [density: 0.93 g / cm 3 A spunbond nonwoven fabric was produced and evaluated in the same manner as in Example 1, except that the amount of the polymerizable monomer (polymerizable monomer: 1,000, weight average molecular weight: 3,000) was changed to 2.0 parts by mass. The number of times that yarn breakage occurred during the test was 0.

[0111] Example 3 90.7 parts by mass of propylene homopolymer (1) with a melting point of 160 ° C., product name "HIWAX (registered trademark) 320P" [density: 0.93 g / cm 3 A spunbond nonwoven fabric was produced and evaluated in the same manner as in Example 1, except that the amount of the polymer (weight average molecular weight: 3000) was changed to 3.0 parts by mass. The number of times that yarn breakage occurred during the test was 0.

[0112] Example 4 The melting point of the propylene homopolymer (1) was 87.7 parts by mass, and the polyethylene was 10.0 parts by mass. The product name was "Hiwax (registered trademark) 320P" [density: 0.93 g / cm 3 A spunbond nonwoven fabric was produced and evaluated in the same manner as in Example 1, except that the amount of the polymerizable monomer (polymerizable monomer: 1,000, weight average molecular weight: 3,000) was changed to 2.0 parts by mass. The number of times that yarn breakage occurred during the test was 0.

[0113] Example 5 The melting point of the propylene homopolymer (1) was 86.7 parts by mass, and the product name was "HIWAX (registered trademark) 320P" [density: 0.93 g / cm 3 A spunbond nonwoven fabric was produced and evaluated in the same manner as in Example 4, except that the amount of the polymer (weight average molecular weight: 3000) was changed to 3.0 parts by mass. The number of times that yarn breakage occurred during the test was 0.

[0114] Example 6 Product name: "HIWAX (registered trademark) 320P" [Density: 0.93 g / cm 3 , weight-average molecular weight: 3000] was mixed with an ethylene-butene copolymer wax (Mitsui Chemicals, Inc., product name "Excelex® 30200B", density: 0.92 g / cm 3 A spunbond nonwoven fabric was produced and evaluated in the same manner as in Example 1, except that the weight average molecular weight was changed to 2900. The number of times that yarn breakage occurred during the test was 0.

[0115] Example 7 Product name: "HIWAX (registered trademark) 320P" [Density: 0.93 g / cm 3 , weight average molecular weight: 3000] was mixed with ethylene polymer wax (manufactured by Mitsui Chemicals, Inc., product name "HIWAX (registered trademark) 100P", density: 0.95 g / cm 3 A spunbond nonwoven fabric was produced and evaluated in the same manner as in Example 1, except that the weight average molecular weight was changed to 900. The number of times that yarn breakage occurred during the test was 0.

[0116] Example 8 Product name: "HIWAX (registered trademark) 320P" [Density: 0.93 g / cm 3 , weight-average molecular weight: 3000] was dissolved in ethylene-propylene copolymer wax (manufactured by Mitsui Chemicals, Inc., product name "HIWAX® 110P", density: 0.92 g / cm 3 A spunbond nonwoven fabric was produced and evaluated in the same manner as in Example 1, except that the weight average molecular weight was changed to 1000. The number of times that yarn breakage occurred during the test was 0.

[0117] Example 9 A spunbond nonwoven fabric was produced and evaluated in the same manner as in Example 8, except that the propylene homopolymer (1) having a melting point of 160°C was used in an amount of 93.7 parts by mass and the polyethylene was used in an amount of 5.0 parts by mass. The number of times that yarn breakage occurred during the test was 0.

[0118] Example 10 A spunbond nonwoven fabric was produced and evaluated in the same manner as in Example 8, except that the propylene homopolymer (1) having a melting point of 160°C was used in an amount of 94.7 parts by mass and the polyethylene was used in an amount of 4.0 parts by mass. The number of times that yarn breakage occurred during the test was 0.

[0119] Example 11 A spunbond nonwoven fabric was produced and evaluated in the same manner as in Example 10, except that 93.0 parts by mass of propylene homopolymer (1) having a melting point of 160°C, 6.0 parts by mass of polyethylene, and no erucic acid amide were used. The number of times that yarn breakage occurred during the test was 0.

[0120] (Comparative Example 1) MFR (measured in accordance with ASTM D1238 at 230°C and 2.16 kg load) 60 g / 10 min, density 0.91 g / cm 3 92.7 parts by mass of propylene homopolymer (1) having a melting point of 160 ° C., MFR (measured in accordance with ASTM D1238 at 190°C and 2.16 kg load) 5 g / 10 min, density 0.95 g / cm 3 High density polyethylene with a melting point of 134°C (Hereafter 6 parts by mass of polyethylene; 0.3 parts by mass of erucic acid amide The mixture was melted using a 75 mm diameter extruder, and melt-spun by the spunbond method using a spunbond nonwoven fabric molding machine with a spinneret having 1,093 holes (length perpendicular to the machine flow direction on the collecting surface: 320 mm, see Figure 1) under the conditions of a resin temperature and die temperature of 200°C, a resin discharge rate of 32 kg / h, a cooling air temperature of 20°C, and a drawing air speed of 3,529 m / min. The mixture was deposited on the collecting surface and subjected to a heat and pressure treatment with an embossing roll (embossed area ratio (thermocompression ratio) of 18%, embossing temperature of 90°C) to produce a total basis weight of 18.0 g / m. 2 The number of thread breakages during the test was one. FIG. 3 shows an image of the cross section of the fiber in the spunbonded nonwoven fabric obtained in Comparative Example 1 observed with a transmission electron microscope.

[0121] (Comparative Example 2) A spunbond nonwoven fabric was produced and evaluated in the same manner as in Example 8, except that the shape of the stretching section was adjusted so that the fibers were dispersed in the cross direction (CD) (specifically, the length L (see Figure 1) in the vertical direction of the tubular section 16b of the stretching section 16 was increased by 50 times). The number of times that yarn breakage occurred during the test was 0. The cylindrical portion 16b of Comparative Example 2 was not in contact with the moving collection member 21 and the spunbond web 2 formed on the moving collection member 21.

[0122] (Comparative Example 3) The product name "Hiwax (registered trademark) 320P" was mixed with a low-crystalline polypropylene homopolymer (manufactured by Idemitsu Kosan Co., Ltd., product name "S400", density: 0.87 g / cm 3 A spunbond nonwoven fabric was produced and evaluated in the same manner as in Example 1, except that the weight average molecular weight was changed to 45,000. The number of times that yarn breakage occurred during the test was 0.

[0123] Comparative Example 4 A spunbond nonwoven fabric was produced and evaluated in the same manner as in Example 1, except that the propylene homopolymer (1) having a melting point of 160 ° C. was used in an amount of 83.7 parts by mass, polyethylene in an amount of 14.0 parts by mass, and the product name "Hiwax (registered trademark) 320P" in an amount of 2.0 parts by mass. The number of times that yarn breakage occurred during the test was 0.

[0124] [Table 1]

[0125] In Table 1, "low crystalline PP homopolymer" refers to low crystalline polypropylene homopolymer.

[0126] As shown in Table 1, the spunbonded nonwoven fabrics of Examples 1 to 11 contain sea-island fibers made of a resin composition containing a propylene homopolymer and polyethylene. All of the sea-island fibers were confirmed to have a sea-island structure. The sea-island fibers contain fibers with an island phase ratio of 60% or more by number. The tensile strength ratios (S MD / SCD ) was 2.0 to 5.0. Therefore, the spinnability of the spunbonded nonwoven fabrics of Examples 1 to 11 was rated "A," and the maximum elongation in the machine direction (MD) exceeded 197%. As a result, it was found that the spunbonded nonwoven fabrics of Examples 1 to 11 were excellent in extensibility and spinnability. These evaluation results demonstrate that the spunbonded nonwoven fabrics of the present disclosure are excellent in productivity and suitable for use in sanitary materials that require various secondary processability.

[0127] In contrast, the spunbonded nonwoven fabrics of Comparative Examples 1 and 3 contain sea-island fibers made of a resin composition containing a propylene homopolymer and polyethylene. It was confirmed that all of the sea-island fibers had a sea-island structure. The sea-island fibers did not contain fibers with an island phase ratio of 60% or more by number. Therefore, the maximum elongation in the machine direction (MD) of the spunbonded nonwoven fabrics of Comparative Examples 1 and 3 was 197% or less. Furthermore, the spinnability of the spunbonded nonwoven fabric of Comparative Example 1 was rated "B." As a result, it was found that the spunbonded nonwoven fabrics of Comparative Examples 1 and 3 did not have excellent extensibility and spinnability.

[0128] The spunbonded nonwoven fabrics of Comparative Examples 2 and 4 contain islands-in-the-sea fibers made of a resin composition containing a propylene homopolymer and polyethylene. The tensile strength ratios (S MD / S CD ) was not within the range of 2.0 to 5.0. Therefore, the maximum elongation in the machine direction (MD) of the spunbonded nonwoven fabrics of Comparative Examples 2 and 4 was less than 197%. As a result, it was found that the spunbonded nonwoven fabrics of Comparative Examples 2 and 4 were not excellent in extensibility and spinnability.

[0129] The disclosure of Japanese Patent Application No. 2021-058789, filed on March 30, 2021, is incorporated herein by reference in its entirety. All publications, patent applications, and technical standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A propylene polymer (A), a polymer (B) which is a polyolefin (excluding the propylene-based polymer (A)); a low-molecular-weight olefin polymer having a weight-average molecular weight of 500 to 30,000; The fiber comprises a resin composition containing the content of the low-molecular-weight olefin polymer is 1.0% by mass to 5.0% by mass based on the total amount of the resin composition; The fibers have an island-in-a-sea structure, the fibers include fibers in which, among island phases in a cross section perpendicular to the axial direction of the fibers, a ratio of island phases having a diameter of less than 0.32 μm is 60% or more by number, Tensile strength in the direction crossing the machine direction (MD) (S ＣＤ ) to the tensile strength in the machine direction (MD) (S ＭＤ ) ratio (S ＭＤ / S ＣＤ ) is 2.0 to 5.1, the polyolefin is polyethylene having a density of 0.94 g / cm 3 to 0.97 g / cm 3 ; the content of the propylene polymer (A) is 85.0% by mass to 95.0% by mass based on the total amount of the resin composition, The content of the polymer (B) is 1.0% by mass to 10.0% by mass relative to the total amount of the resin composition.

2. The spunbond nonwoven fabric according to claim 1 , wherein the propylene-based polymer (A) comprises a propylene homopolymer.

3. the sea phase contained in the sea-island structure contains the propylene polymer (A), The spunbond nonwoven fabric according to claim 1 or 2, wherein the island phase contains the polymer (B).

4. The ratio (S ＭＤ / S ＣＤ 4. The spunbond nonwoven fabric according to claim 1, wherein the tensile strength (N) of the spunbond nonwoven fabric is 2.5 to 5.

1.

5. containing thermoplastic elastomer fibers, It is a laminated nonwoven fabric or a mixed fiber nonwoven fabric, The laminated nonwoven fabric is formed by bonding a spunbond web containing the fibers to a resin layer containing the thermoplastic elastomer fibers and laminated on at least one main surface of the spunbond web, The spunbond nonwoven fabric according to any one of claims 1 to 4, wherein the mixed fiber nonwoven fabric is formed by mixing the fiber and the thermoplastic elastomer fiber.

6. 6. The spunbond nonwoven fabric according to claim 5, wherein the thermoplastic elastomer fibers are polyurethane-based thermoplastic elastomer fibers or olefin-based thermoplastic elastomer fibers.

7. A hygiene material comprising the spunbond nonwoven fabric according to any one of claims 1 to 6.

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