KNITTED NON-WOVEN FABRICS

Abstract

In order to provide a spun-bonded nonwoven fabric having excellent strength even at a low basis weight and excellent flexibility and tactile feel, the spun-bonded nonwoven fabric of the present invention is a spun-bonded nonwoven fabric made of core-sheath composite fibers containing a polypropylene-based resin as the main component, wherein the spun-bonded nonwoven fabric has a bonded area and a non-bonded area, and the ratio (Os / Oc) of the orientation parameter Os of the sheath component of the core-sheath composite fiber in the non-bonded area to the orientation parameter Oc of the core component of the core-sheath composite fiber in the non-bonded area is 0.10 to 0.90.

Description

Description NON-WOVEN FABRIC Invention Engineering Field The present invention relates to a nonwoven fabric. Background of the Invention Many sanitary products, such as paper diapers and sanitary pads, are incinerated or landfilled after use due to hygiene concerns, causing a significant environmental burden due to resource consumption and increased waste. In response to this problem, thinning and weight-reducing products have been developed. Even in spun-bonded nonwoven fabrics used as the primary material of paper diapers, efforts have been made to reduce the basis weight from the former. For example, a spun-bonded / melt-blown laminated nonwoven fabric comprising a polypropylene spun-bonded nonwoven fabric having a fineness of 0.7 to 1.5 dtex and a polypropylene melt-blown nonwoven fabric having a fiber diameter of 1 to 3 μm and having a modulus index of 5% within a specific range has been proposed as a nonwoven fabric having excellent water resistance, high softness, and tensile strength even at a low basis weight (refer to Patent Document 1). Prior Invention Document Patent Documents Patent Document 1: Japanese Patent No. 4245970 Brief Description of the Invention Problems Solved by the Invention However, in the method disclosed in the Document Patent 1, the effect of increasing strength is limited, and it is difficult to achieve strength that can be used in practical use at the low basis weight levels required in recent years. Therefore, it is an object of the present invention to provide a spun-tie nonwoven fabric having excellent strength, excellent flexibility, and feel even at a low basis weight. Problem solving The spun-tie nonwoven fabric of the present invention has the following configuration. [1] A spun-bonded nonwoven fabric comprising a core-sheath composite fiber containing a polypropylene-based resin as the main component, wherein the spun-bonded nonwoven fabric has a bonded area and a non-bonded area, and the ratio (Os / Oc) of the orientation parameter Os of the sheath component of the core-sheath composite fiber in the non-bonded area to the orientation parameter Oc of the core component of the core-sheath composite fiber in the non-bonded area is 0.10 to 0.90. [2] Spun-bonded nonwoven fabric according to [1], wherein the orientation parameter Os of the sheath component of the core-sheath composite fiber in the non-bonded area is 1.0 or more and 8.0 or less. [3] Spun-tie nonwoven fabric according to [1] or [2], wherein the spun-tie nonwoven fabric has a single peak melting temperature (Tm) (°C) in the differential spun calorimetry method. [4] Spun-bonded nonwoven fabric according to any one of [1] to [3], wherein the tensile strength and elongation product per basis weight of the spun-bonded nonwoven fabric is 1.20 (N / 50 mm) / (g / m2) or more. [5] Spun-bonded nonwoven fabric according to any one of [1] to [4], wherein the melt flow rate of the polyolefin-based resin of the sheath component is greater than the melt flow rate of the polyolefin-based resin of the core component by 10 g / 10 min to 200 g / 10 min. Influence of Invention The present invention can provide a spun-tie nonwoven fabric having excellent strength, excellent flexibility, and a tactile feel even at a low basis weight. Based on these properties, the spun-tie nonwoven fabric of the present invention can be used particularly suitably for sanitary purposes. Complete Description of the Invention The spun-bonded nonwoven fabric of the present invention is a spun-bonded nonwoven fabric made of core-sheath composite fibers containing polypropylene-based resin as the main component, wherein the spun-bonded nonwoven fabric has a bonded area and a non-bonded area, and the ratio (Os / Oc) of the orientation parameter Os of the sheath component of the core-sheath composite fiber in the non-bonded area to the orientation parameter Oc of the core component of the core-sheath composite fiber in the non-bonded area is 0.10 to 0.90. This makes it possible to provide spun-bonded nonwoven fabrics that have excellent strength, excellent flexibility and feel even at low basis weights. Hereinafter, the constituent elements of the present invention will be described in detail, but the present invention is not limited to the scope described below in any way without deviating from the essence thereof. [Polypropylene based resin] The core-sheath composite fibers that constitute the spun-bonded nonwoven fabric of the present invention contain a polypropylene-based resin as a major component. The polypropylene-based resin is suitable because of its excellent spinnability and strength properties when compared to other polyolefin-based resins such as polyethylene-based resins. In the present invention, “polypropylene-based resin” refers to a resin in which the mole fraction of propylene units in the repeating unit is 60 mol % to 100 mol %. The same applies to “polyethylene-based resin”. Examples of polypropylene-based resins used in the present invention include homopolymers of propylene and copolymers of propylene and various α-olefins. Herein, “major component” means that it occupies 50 mass % or more relative to the entire core-sheath composite fiber. In the polypropylene-based resin used in the present invention, the homopolymer percentage of propylene is preferably 60% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more. Therefore, good spinnability can be maintained and strength can be increased. The material that constitutes the composite fiber used in the present invention (hereinafter, sometimes referred to as “thermoplastic resin”) may be a mixture of two or more types containing polypropylene-based resins and other resins may be used. As a mixture, a resin composition containing other olefin-based resins such as polyethylene and poly-4-methyl-1-pentene, thermoplastic elastomers, and the like may be used. To the polypropylene-based resin used in the present invention, additives such as antioxidants, weather-resistant stabilizers, light-resistant stabilizers, heat-resistant stabilizers, antistatic agents, loading aids, antifog agents, anti-barrier agents, lubricants containing polyethylene wax, crystal nucleating agents, and pigments, or other polymers, which are commonly used, may be added if necessary to further improve the effect of the present invention or to provide other properties without impairing the effect of the present invention. The melting point (Tmr) of the polypropylene-based resin used in the present invention is preferably 120 °C to 200 °C. Setting this melting point (Tmr) to preferably 120 °C or more, more preferably 130 °C or more, and still more preferably 140 °C or more can easily provide heat resistance that can be used in practical use. Furthermore, setting the melting temperature to preferably 200 °C or less, more preferably 180 °C or less, and still more preferably 170 °C or less can facilitate cooling of the yarns discharged from the spinning tool, suppress fiber bonding with each other, and facilitate stable spinning even with thin fiber diameters. Herein, the melting point (Tmr) of the polypropylene-based resin refers to the maximum (highest) melting peak temperature obtained by measuring the polypropylene-based resin by differential scanning calorimetry (DSC). The melt flow rate (hereinafter, sometimes abbreviated as MFR) of the polypropylene-based resin as the core component of the spun-bonded nonwoven fabric including the core-sheath composite fiber of the present invention is preferably 10 g / 10 min to 100 g / 10 min. Setting the MFR of the polypropylene-based resin to preferably 10 g / 10 min or more, more preferably 20 g / 10 min or more, and still more preferably 30 g / 10 min or more enables stable spinning even with thin fiber diameters, making it possible to provide a spun-bonded nonwoven fabric having excellent tactile feel and uniform texture. On the other hand, setting the MFR of the polypropylene-based resin of the core component to preferably 100 g / 10 min or less, more preferably 80 g / 10 min or less, and still more preferably 60 g / 10 min or less can suppress the decrease in single yarn strength, making it possible to provide a spun-bonded nonwoven fabric having excellent strength. The MFR of the polypropylene-based resin of the sheath component of the spun-bonded nonwoven fabric including core-sheath composite fibers of the present invention is preferably greater than the MFR of the polypropylene-based resin as the core component by 10 g / 10 min to 200 g / 10 min. Setting the MFR of the polypropylene-based resin of the sheath component to be greater than the MFR of the polypropylene-based resin of the core component by preferably 10 g / 10 min or more, more preferably 15 g / 10 min or more, and still more preferably 20 g / 10 min or more can concentrate the spinning stress on the core component during spinning, promote the orientation of the core component, and suppress the orientation of the sheath component.On the other hand, in the case where the MFR of the polypropylene-based resin of the sheath component is greater than the MFR of the polypropylene-based resin of the core component by more than 200 g / 10 min, the single yarn strength of the core-sheath composite fiber decreases, and operational problems such as excessive softening tendency and sticking to the hot roller during thermal adhesion occur, which are undesirable. The MFR of the polypropylene-based resin of the sheath component is preferably not higher than 150 g / 10 min than the MFR of the polypropylene-based resin of the core component, and is still preferably not higher than 100 g / 10 min than the MFR of the polypropylene-based resin of the core component. When measuring and interpreting the MFR of polypropylene-based resin of the core component or sheath component of sea-island composite fibers, measurements and the like are performed by replacing “sheath component” with “sea component” and “core component” with “island component”. For the MFR of the polypropylene-based resin according to the present invention, a value measured according to ASTM D1238 (method A) is used. According to the standard, it is stipulated that the polypropylene-based resin is measured at a load of 2.16 kg and a temperature of 230 °C. Of course, the MFR of the polypropylene-based resin used in the present invention can also be adjusted by blending two or more resins having different MFRs at desired percentages. In this case, the MFR of the resin blended with the main polypropylene-based resin (referring to the polypropylene-based resin that provides the largest mass % in the polypropylene-based resin) is preferably 10 g / 10 min to 1,000 g / 10 min, more preferably 20 g / 10 min to 800 g / 10 min, and still more preferably 30 g / 10 min to 600 g / 10 min. Therefore, the occurrence of partial viscosity unevenness can be prevented in the blended polypropylene-based resin, the single fiber diameter and the single fiber fineness can be made uniform, and stable spinning can be achieved even with thin fibers. In a preferred embodiment of the spunbond nonwoven fabric of the present invention, a fatty acid amide compound having 23 or more and 50 or less carbon atoms is contained throughout the core-sheath composite fiber containing a polypropylene-based resin as a main component or a sheath component to improve smoothness and flexibility. Setting the amount of carbon from the fatty acid amide compound mixed with the polypropylene-based resin to preferably 23 or more, and preferably 30 or more can suppress the excessive exposure of the fatty acid amide compound on the surface of the fiber, making the spinning power and processing stability very good, and maintaining high productivity. On the other hand, setting the amount of carbon from the fatty acid amide compound to preferably 50 or less, and preferably 42 or less can facilitate the movement of the fatty acid amide compound to the surface of the fiber, and provide smoothness and flexibility to the non-woven fabric. Examples of fatty acid amide compounds having a carbon number of 23 or more and 50 or less used in the present invention include saturated fatty acid monoamide compounds, saturated fatty acid diamide compounds, unsaturated fatty acid monoamide compounds, and unsaturated fatty acid diamide compounds. Specific examples of fatty acid amide compounds having 23 or more and 50 or fewer carbon atoms include tetracosanoic acid amide, hexacosanoic acid amide, octacosanoic acid amide, nervonic acid amide, tetracosopentaenoic acid amide, nisinic acid amide, ethylene bislauric acid amide, methylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, distearyl adipate amide, distearyl sebacic acid amide, ethylene bisoleic acid amide, ethylene biserucic acid amide, and hexamethylene bisoleic acid amide, and some of these may be used in combination. In the present invention, among the fatty acid amide compounds, ethylene bisstearic acid amide, which is a saturated fatty acid diamide compound, is particularly preferred. Ethylene bisstearic acid amide has excellent thermal stability and is thus melt-spunable, and fibers containing polypropylene-based resins containing ethylene bisstearic acid amide can provide spun-bonded nonwoven fabrics with excellent slipperiness and flexibility while maintaining high productivity. In the present invention, it is a preferred embodiment that the amount of fatty acid amide compound added is 0.01 mass % to 5.0 mass %. Determining the amount of addition of fatty acid amide compounds to preferably 0.01 mass % to 5.0 mass %, preferably 0.1 mass % to 3.0 mass %, and still more preferably 0.1 mass % to 1.0 mass % can provide appropriate smoothness and flexibility while maintaining spinnability. The added amount referred to herein refers to the mass percentage of the fatty acid amide compound added to the entire thermoplastic resin primarily composed of polypropylene-based resin that constitutes the spunbond nonwoven fabric of the present invention. For example, even in the case where the fatty acid amide compound is added only to the sheath component that constitutes the core-sheath composite fiber, a percentage addition to the total amount of the core component and the sheath component is calculated. Examples of methods for measuring the amount of fatty acid amide compounds added to fibers containing polypropylene-based resins include a method where the additive is extracted from the fiber with a solvent and subjected to quantitative analysis using, for example, liquid chromatography-mass spectrometry (LS / MS). Currently, the extractant is selected appropriately according to the type of fatty acid amide compound, but for example, in the case of ethylene bis-stearamide, a method using, for example, a mixed chloroform-methanol solution is exemplified. [Core-sheath composite fiber containing polypropylene-based resin as the main component] As a composite form of the core-sheath composite fibers that constitute the spun-bonded nonwoven fabric of the present invention, a composite form such as a concentric core-sheath, an eccentric core-sheath, and a sea-island can be used. Among them, it is preferred to form a core-sheath composite form, namely, the composite fiber is preferably a core-sheath composite fiber, and it is more preferred to form a concentric core-sheath composite form, namely, the composite fiber is preferably a core-sheath composite fiber of the concentric core-sheath type, because it has excellent spinnability and allows the fibers to bond to each other uniformly by thermal adhesion. The core-sheath composite fibers that constitute the spun-bonded nonwoven fabric of the present invention preferably have an average single fiber fineness of 0.5 dtex to 3.0 dtex. Setting the average single fiber fineness to preferably 0.5 dtex or more, more preferably 0.6 dtex or more, and still more preferably 0.7 dtex or more can create a spun-bonded nonwoven fabric that prevents a decrease in spinnability and has excellent production stability. On the other hand, setting the average single fiber fineness to preferably 3.0 dtex or less, more preferably 2.0 dtex or less, and still more preferably 1.5 dtex or less can create a spun-bonded nonwoven fabric that has excellent feel, uniform texture, and excellent strength. The average single fiber fineness can be controlled according to, for example, the spinning temperature, the number of single hole outputs, and the spinning speed as described later. The core-sheath composite fibers that constitute the spun-bonded nonwoven fabric of the present invention preferably have an average single fiber diameter of 8 μm to 20 μη. Setting the average single fiber diameter to preferably 8 μm or more, more preferably 9 μm or more, and still more preferably 10 μm or more can create a spun-bonded nonwoven fabric that prevents a decrease in spinnability and has excellent production stability. On the other hand, setting the average single fiber diameter to preferably 20 μm or less, more preferably 17 μm or less, and still more preferably 14 μm or less can create a spun-bonded nonwoven fabric that has excellent feel, uniform texture, and excellent strength. The average single fiber diameter can be controlled according to, for example, the spinning temperature, the number of single hole outputs, and the spinning speed as described later. In the present invention, for the average single fiber diameter (μη) of the core-sheath composite fibers composing the spun-bonded nonwoven fabric, a value calculated according to the procedures below is used. (1) Ten small cut samples (100 x 100 mm) were randomly collected from the spun-tie nonwoven fabric. (2) Surface photographs were taken with a microscope or scanning electron microscope at a magnification of 500 to 2,000, and the width (diameter) of each of the 100 core-sheath composite fibers in the non-bonded area of ​​the whole sample, 10 fibers, was measured. In cases where the cross-section of the core-sheath composite fiber was deformed, the cross-sectional area of ​​the cross-section was measured, and the diameter of a perfect circle having the same cross-sectional area was determined. (3) The average diameter value of the 100 measured fibers is rounded to one decimal place to obtain the average single fiber diameter (μη). In the core-sheath composite fibers that constitute the spun-bonded nonwoven fabric of the present invention, the mass ratio of the sheath component is preferably 20 mass % to 80 mass %. The mass ratio of the sheath component is preferably 20 mass % or more, more preferably 30 mass % or more, and still more preferably 40 mass % or more, so as to firmly bond the sheath components to each other during thermal adhesion, and make it possible to provide a spun-bonded nonwoven fabric having sufficient strength that can be used for practical use.On the other hand, since the ratio of the sheath component is preferably 80 mass % or less, more preferably 70 mass % or less, and still more preferably 60 mass % or less, it is possible to prepare a spun-bonded nonwoven fabric that increases the percentage of a highly oriented core component, increases the single yarn strength of the core-sheath composite fiber, and has sufficient strength for use in practical applications. As the cross-sectional shape of the core-sheath composite fibers composing the spun-tie nonwoven fabric of the present invention, a round cross-section, a flat cross-section, and a heteromorphic cross-section such as a Y-shape or a C-shape can be used. Among them, a round cross-section is a preferred aspect because the spun-tie nonwoven fabric has no difficulty in bending due to the structure such as a flat cross-section or a heteromorphic cross-section and the flexibility is excellent. Furthermore, a hollow cross-section can also be applied as the cross-sectional shape, but a solid cross-section is a preferred aspect, because the spinnability is excellent and stable spinning can be carried out even with a thin fiber diameter. [Spun tie-dye nonwoven fabric] The spun-bonded nonwoven fabric of the present invention is a spun-bonded nonwoven fabric made of core-sheath composite fibers containing polypropylene-based resin as the main component, wherein the spun-bonded nonwoven fabric has a bonded area and a non-bonded area, and the ratio (Os / Oc) of the orientation parameter Os of the sheath component of the core-sheath composite fiber in the non-bonded area to the orientation parameter Oc of the core component of the core-sheath composite fiber in the non-bonded area is 0.10 to 0.90. This makes it possible to provide a spun-bonded nonwoven fabric that has excellent strength, excellent flexibility, and tactile feel even at a low basis weight. The spun-bonded nonwoven fabric of the present invention firstly has a bonded area and a non-bonded area. This makes it possible to provide a spun-bonded nonwoven fabric that has sufficient strength for practical use while maintaining flexibility and tactile feel. The bonded area refers to a portion where the core-sheath composite fibers are bonded to each other, and the non-bonded area refers to a portion where the core-sheath composite fibers are not bonded to each other and the cross-sectional shape is maintained. In the spun-bonded nonwoven fabric of the present invention, the orientation ratio (Os / Oc) is 0.10 to 0.90. The orientation ratio (Os / Oc) is preferably 0.10 or more, more preferably 0.15 or more, and still more preferably 0.20 or more, so as to prevent excessive concentration of tensile stress in the inner layers of the fibers during spinning and deterioration of spinning stability. On the other hand, the orientation ratio (Os / Oc) is preferably 0.90 or less, more preferably 0.85 or less, and still more preferably 0.80 or less, so as to allow only the surface layers of the fibers to be softened upon thermal adhesion. Among these, 0.70 or less is preferred, and especially 0.50 or less is preferred. The orientation parameter can be determined from the intensity of the Raman bands at about 810 cm-1 and 840 cm-1 in the Raman spectrum obtained by Raman spectroscopy, for example, in the case of polypropylene.In the case of polypropylene, it is known that the Raman bands around 810 cm-1 and 840 cm-1 exhibit strong anisotropy with respect to the polarization of the incident light. These are assigned to the coupling modes of CH2 bending vibration and CC stretching vibration, and CH2 bending vibration mode, respectively. From this, for the 810 cm-1 Raman band, the principal axis of the Raman tensor of the oscillatory mode is parallel to the main chain direction of the molecule, while it is orthogonal for the 840 cm-1 Raman band. Therefore, the orientation of the molecular chain is obtained from the ratio of the band intensities in the polarization direction of the Raman band. The orientation parameter I referred to in the present invention is obtained as a value of I810 / I840 (I810: Raman band intensity of about 810 cm-1, I840: Raman band intensity of about 840 cm-1). In the present invention, fixing the orientation ratio as described above can thermally bond the fibers firmly to each other while the molecular orientation of the inner layer of the fibers remains, thereby making it possible to provide a spun-bonded nonwoven fabric having strength applicable to practical use. Reducing the orientation parameter Os of the sheath component of the core-sheath composite fiber in the nonbonded area can provide a spun-bonded nonwoven fabric having excellent flexibility. Herein, the orientation parameter of the core-sheath composite fiber of the present invention is an index (not a unit) indicating that the molecular chains are oriented in a specific direction as the numerical value increases, and indicating that the molecular chains of the polypropylene-based resin composing the core-sheath composite fiber are oriented randomly as the numerical value decreases. The orientation parameter is 1.0 when the molecular chains are oriented in a completely random manner. In the present invention, the orientation parameter Os for the sheath component and the orientation parameter Oc for the core component of the core-sheath composite fiber in the non-bonded area of ​​the spun-bonded nonwoven fabric are measured by the following method. In the present invention, the sea-island composite fiber is also included in the core-sheath composite fiber, and in the case of the sea-island composite fiber, as in the case of the core-sheath composite fiber, when the orientation parameters Os and Oc are measured and interpreted, the “sheath component” is replaced by the “sea component”, and the “core component” is replaced by the “island component”, and then the measurement or the like is performed. (1) The core-sheath composite fiber around the center of the non-bonded area (a portion substantially equidistant from the surrounding bonded area) is sampled, and the fiber cut sample is embedded in a bisphenol-based epoxy resin. (2) The resin was cut into pieces with a microtome after the resin was cured. The thickness of each piece was 2 μη. At this time, the resin was cut while tilting from the fiber axis to make the cutting surface in an elliptical shape, and after that, a section where the thickness of the short axis of the elliptical shape appeared constant was selected and measured. The cutting angle was set within 4°, the cutting surface could be considered parallel to the fiber axis within the film thickness of 2 μη. (3) Light polarized in the fiber axis direction (parallel direction) and the direction orthogonal to the fiber axis direction (perpendicular direction) enters from the fiber surface layer into the center of the cross-section of the core-sheath composite fiber in the non-bonded area, and Raman spectral line measurements are performed. (4) At each position of the core component and sheath component of the core-sheath composite fiber in the non-bonded area, the Raman band intensities of Is40 and Is40 near 810 cm1 and near 840 cm-1 were calculated for the parallel direction and the vertical direction, respectively, and the intensity ratio of I810 / I840 was calculated. (5) The orientation parameter is calculated based on the following formula (a). In cases where the core component is divided into several free regions, the orientation parameter is measured in all regions, and the highest value is used. Orientation parameter = (Is10 / I 840 )parallel / (I810 / I 840 )perpendicular...(a) (6) Similar measurements were made on three different sections in the fiber axis direction of the core-sheath composite fiber, and the average value of the orientation parameter was calculated and rounded to one decimal place. If it is difficult to sample the core-sheath composite fiber around the center of the non-bonded area (a portion substantially equidistant from the surrounding bonded area), measurements can also be made by the following procedure. (1) Samples of spun-bonded nonwoven fabrics were immersed in bis-phenol based epoxy resin. (2) After the resin is cured, it is cut into pieces with a microtome to create a cutting surface around the center of the non-bonded area of ​​the spun-bonded nonwoven fabric (a section substantially equidistant from the surrounding bonded area). The thickness of each piece is 2 μη. The section having a cutting angle within 4° of the fiber axis is selected, and is machined with subsequent measurements. (3) Light polarized in the fiber axis direction (parallel direction) and the direction orthogonal to the fiber axis direction (perpendicular direction) enters from the fiber surface layer into the center of the cross-section of the core-sheath composite fiber in the non-bonded area, and Raman spectral line measurements are performed. (4) At each position of the core component and sheath component of the core-sheath composite fiber in the non-bonded area, the Raman band intensities of Is40 and Is40 near 810 cm1 and near 840 cm-1 were calculated for the parallel direction and the vertical direction, respectively, and the intensity ratio of I810 / I840 was calculated. (5) The orientation parameter is calculated based on the following formula (a). In cases where the core component is divided into several free regions, the orientation parameter is measured in all regions, and the highest value is used. Orientation parameter = (Is10 / I 840 )parallel / (I810 / I 840 )perpendicular...(a) (6) Similar measurements were made on three sections at different non-bonded areas of the spun-bonded nonwoven fabric, and the average value of the orientation parameter was calculated and rounded to one decimal place. In the spun-bonded nonwoven fabric of the present invention, the orientation parameter Os of the sheath component in the core-sheath composite fiber of the non-bonded area is preferably 1.0 to 8.0. The orientation parameter Os of the sheath component of the core-sheath composite fiber in the non-bonded area is preferably 1.0 or more, more preferably 1.5 or more, and still more preferably 2.0 or more, so as to prevent the occurrence of operational problems such as excessive softening of the fiber surface layer during thermal adhesion and sticking to the hot roller.On the other hand, the orientation parameter Os of the sheath component of the core-sheath composite fiber in the non-bonded area is preferably 8.0 or less, more preferably 6.0 or less, and still more preferably 5.0 or less, so as to enable to increase the flexibility, easily soften the surface layer of the fiber upon thermal adhesion, and firmly thermally bond the fibers to each other, so that a spun-bonded nonwoven fabric having excellent strength can be obtained. The orientation parameter Os of the sheath component of the core-sheath composite fiber in the non-bonded area can be controlled by the MFR of the polypropylene-based resin, melting point, additives, mass ratio of the sheath component of the core-sheath composite fiber, and / or the spinning temperature, spinning speed, and the like described hereinafter. In the spun-bonded nonwoven fabric of the present invention, the orientation parameter Oc of the core component of the core-sheath composite fiber in the non-bonded area is preferably 4.0 or more, more preferably 5.0 or more, and still more preferably 6.0 or more. Among these, 8.0 to 20.0 is preferred. The orientation parameter Oc of the core component of the core-sheath composite fiber of the non-bonded area is typically 4.0 or more, preferably 5.0 or more, more preferably 6.0 or more, still more preferably 8.0 or more, especially preferably 9.0 or more, and most preferably 10.0 or more, thereby increasing the strength of the inner layer of the fiber to provide a spun-bonded nonwoven fabric having strength usable in practical use after thermal adhesion. Furthermore, it is possible to prevent the occurrence of operational problems such as adhesion of the surface layer of the fiber to the hot roller due to excessive softening during thermal adhesion.On the other hand, the orientation parameter Oc of the core component of the core-sheath composite fiber in the non-bonded area is preferably 20.0 or less, more preferably 19.0 or less, and still more preferably 18.0 or less, so as to enable to improve the flexibility, suppress excessive concentration of tensile stress in the inner layer of the fiber during spinning, and improve the spinning stability. The orientation parameter Oc of the core component of the core-sheath composite fiber in the non-bonded area can be controlled by the MFR of the polypropylene-based resin, melting point, additives, mass ratio of the sheath component of the core-sheath composite fiber, and / or the spinning temperature, spinning speed, and the like described hereinafter. The spun-bonded nonwoven fabric of the present invention preferably has a single melting peak temperature (Tm) (°C) in differential scanning calorimetry (DSC). In the present invention, “spun-bonded nonwoven fabric having a single melting peak temperature (Tm) (°C) in differential scanning calorimetry” means that substantially only one melting endothermic peak described in (3) of the measurement method below is observed. Therefore, the fibers can be worked with strong thermal adhesion to each other at a sufficient temperature without the occurrence of operational problems such as adhesion of low melting point components to the hot roller due to melting of the components during thermal adhesion, and thus, spun-bonded nonwoven fabric having strength applicable to practical use is easily obtained. Here, as the peak melting temperature (Tm) (°C) of the spun-bonded nonwoven fabric obtained by differential scanning calorimetry (DSC), a value calculated by the following procedure is used. (1) Fiber fragments from spun-tie nonwoven fabrics were sampled in sample amounts of 0.5 to 5 mg. (2) The temperature was increased from normal temperature to 200 °C at a rate of 20 °C / min to obtain a DSC curve using differential scattering calorimetry (DSC). (3) The highest peak temperature of the melting endothermic peak is read from the DSC curve and taken as the melting peak temperature (Tm) (°C) of the spun-bonded nonwoven fabric. In the spun-tie nonwoven fabric of the present invention, the surface roughness (SMD) of at least one side by the KES method is preferably 1 μm to 3 μm. Since the surface roughness (SMD) by the KES method is preferably 1.0 μm or more, more preferably 1.3 μm or more, and still more preferably 1.6 μm or more, it is possible to prevent the spun-tie nonwoven fabric from becoming excessively dense so as to deteriorate the texture or impair the flexibility. On the other hand, since the surface roughness (SMD) by the KES method is preferably 3.0 μm or less, more preferably 2.8 μm or less, and still more preferably 2.5 μm or less, it is possible to prepare the spun-tie nonwoven fabric having a smooth surface, a slightly rough feel, and an excellent tactile feel.Surface roughness (SMD) by the KES method can be controlled by precisely adjusting, for example, the average single fiber diameter of the core-sheath composite fiber, the texture of the spun-bonded nonwoven fabric, and / or the thermal adhesion conditions (e.g., shape, degree of compression bonding, temperature, and linear stress of the adhesion site) which will be explained later. In this invention, a measured value as follows is used as the surface roughness (SMD) by the KES method. (1) From the spun-tie nonwoven fabric, three test samples having a width of 200 mm x 200 mm are collected at equal intervals in the width direction of the spun-tie nonwoven fabric. (2) The test sample is fixed on the sample holder. (3) The surface of each test sample was scanned with a contactor (material: φ 0.5 mm piano wire, contact length: 5 mm) for surface roughness measurement to which a load of 10 gf (0.098 N) was applied, and the average deviation of the irregular shape of the surface was measured. (4) The measurements described above were carried out in the machine direction (longitudinal direction of the non-woven fabric) and transverse direction (width direction of the non-woven fabric) of all test samples, and the average deviation of all six points was averaged and rounded to one decimal place to obtain the surface roughness (SMD) (μη). The longitudinal direction (machine direction) of the spun-tie nonwoven fabric refers to a direction in which the spun-tie nonwoven fabric is taken up by a winding device in the spun-tie nonwoven fabric production process, and is also referred to as the machine direction. The transverse direction refers to the width direction of the spun-tie nonwoven fabric with respect to the longitudinal direction. The coefficient of friction (MIU) of the spunbond nonwoven fabric of the present invention by the KES method is preferably 0.01 to 0.30. The coefficient of friction (MIU) is preferably 0.30 or less, more preferably 0.20 or less, and still more preferably 0.15 or less, so that it is possible to provide a spunbond nonwoven fabric that improves the surface smoothness of the nonwoven fabric, and is excellent in tactile feel. On the other hand, the coefficient of friction (MIU) is preferably 0.01 or more, more preferably 0.03 or more, and still more preferably 0.05 or more, so that it is possible to prevent slippage between yarns and deterioration of texture uniformity when the spun yarns are collected on a collecting conveyor.The coefficient of friction (MIU) by the KES method can be controlled by appropriately adjusting, for example, the additives of the polypropylene-based resin, the average single fiber diameter of the core-sheath composite fiber, the texture of the spun-bonded nonwoven fabric, and / or the thermal adhesion conditions (e.g., shape, degree of compression bonding, temperature, and linear stress of the adhesion site) which will be explained later. In this invention, a measured value as follows is used as the coefficient of friction (MIU) by the KES method. (1) From the spun-tie nonwoven fabric, three test samples having a width of 200 mm x 200 mm are collected at equal intervals in the width direction of the spun-tie nonwoven fabric. (2) The test sample is fixed on the sample holder. (3) The surface of each test sample was scanned with a friction contactor (material: φ 0.5 mm piano wire (20 in parallel), contact area: 1 cm2) to which a load of 50 gf (0.49 N) was applied, and the friction coefficient was measured. (4) The measurements described above were carried out in the machine direction (longitudinal direction of the non-woven fabric) and transverse direction (width direction of the non-woven fabric) of all test samples, and the average deviation of the six points was averaged and rounded to three decimal places to obtain the coefficient of friction (MIU). The MFR of the spun-bonded nonwoven fabric of the present invention is preferably 10 g / 10 min to 300 g / 10 min. The MFR of the spun-bonded nonwoven fabric is preferably 10 g / 10 min or more, more preferably 15 g / 10 min or more, and still more preferably 20 g / 10 min or more, so that it is possible to provide a spun-bonded nonwoven fabric that can be stably spun even with a thin fiber diameter, excellent feel, uniform texture, and excellent strength. On the other hand, the MFR of the spun-bonded nonwoven fabric is preferably 300 g / 10 min or less, more preferably 200 g / 10 min or less, and still more preferably 100 g / 10 min or less, so that it is possible to prevent a decrease in compressive strength, and the occurrence of operational problems such as a tendency to over-softening and sticking to the hot roller during thermal adhesion. For the MFR of the spun-bonded nonwoven fabric according to the present invention, a value measured by ASTM D1238 (method A) is used. According to the standard, it is stipulated that the polypropylene-based resin is measured at a load of 2.16 kg and a temperature of 230 °C. The basis weight of the spun-tie nonwoven fabric of the present invention is preferably 10 g / m2 to 100 g / m2. The basis weight is preferably 10 g / m2 or more, more preferably 13 g / m2 or more, and still more preferably 15 g / m2 or more, so that it is possible to provide a spun-tie nonwoven fabric having sufficient strength that can be used in practical applications. On the other hand, the basis weight is preferably 100 g / m2 or less, more preferably 50 g / m2 or less, and still more preferably 30 g / m2 or less, so that it is possible to provide a spun-tie nonwoven fabric having flexibility suitable for use as a nonwoven fabric for sanitary materials. In the present invention, for the basis weight of the spun-bonded nonwoven fabric, a value is measured by the procedures below in accordance with “6.2 Mass per unit area” in “General Test Methods for Nonwoven Fabrics” of JIS L1913:2010. (1) Three test samples of 20 cm x 25 cm were collected per 1 m sample width. (2) The mass (g) of each of the test samples in standard conditions is measured. (3) The average value of the mass is expressed as mass per 1m2(g / m2). The thickness of the spun-tie nonwoven fabric of the present invention is preferably 0.05 mm to 1.5 mm. The thickness is preferably 0.05 mm to 1.5 mm, more preferably 0.08 mm to 1.0 mm, and still more preferably 0.10 mm to 0.8 mm, so that it is possible to provide a spun-tie nonwoven fabric having moderate flexibility and cushioning properties, and is suitable for use in particular in the use of paper diapers as a spun-tie nonwoven fabric for sanitary materials. In the present invention, for the thickness (mm) of the spun-bonded nonwoven fabric, a value measured by the procedures below in accordance with 5.1 of “General Test Methods for Long Fiber Nonwoven Fabrics of JIS L1906:2000” is used. (1) The thickness is measured at 10 points per 1 m at equal intervals in the width direction of the non-woven fabric at a load of 10 kPa in units of 0.01 mm using a press having a diameter of 10 mm. (2) The average value of the thickness at 10 points is rounded to two decimal places. Furthermore, the apparent density of the spun-tie nonwoven fabric of the present invention is preferably 0.05 g / cm3 to 0.30 g / cm3. The apparent density is preferably 0.30 g / cm3 or less, more preferably 0.25 g / cm3 or less, and still more preferably 0.20 g / cm3 or less, so as to make it possible to prevent the fibers from being tightly packed to the detriment of the flexibility of the spun-tie nonwoven fabric. On the other hand, the apparent density is preferably 0.05 g / cm3 or more, more preferably 0.08 g / cm3 or more, and still more preferably 0.10 g / cm3 or more, so as to make it possible to provide a spun-tie nonwoven fabric that suppresses the occurrence of fluffing and delamination, and has sufficient strength and handling that can be used in practical use.The apparent density can be controlled by appropriately adjusting, for example, the average single fiber diameter of the core-sheath composite fiber, and / or the thermal adhesion conditions (e.g., shape, degree of compression bonding, temperature, and linear stress of the adhesion region) as described later. In the present invention, the apparent density (g / cm3) is calculated based on the expression below from the basis weight and thickness before rounding as described above, and rounded to two decimal places. Apparent density (g / cm3) = [basis weight (g / m2)] / [thickness (mm)] x 10-3 The flexural strength of the spunbond nonwoven fabric of the present invention is preferably 65 mm or less. The flexural strength is preferably 65 mm or less, more preferably 60 mm or less, and still more preferably 55 mm or less, so that it is possible to provide excellent flexibility suitable for use in particular in the use of paper diapers as a spunbond nonwoven fabric for sanitary materials. Furthermore, the flexural strength is very low and the handling power is poor, and thus the flexural strength is preferably 10 mm or more.The flexural resistance can be controlled by appropriately adjusting, for example, the MFR of the polypropylene-based resin, additives, the average single fiber diameter of the core-sheath composite fiber, the basis weight of the spun-bonded nonwoven fabric, the ratio (Os / Oc) of the orientation parameter Os of the sheath component of the core-sheath composite fiber in the non-bonded area to the orientation parameter Oc of the core component of the core-sheath composite fiber in the non-bonded area, and / or the thermal adhesion conditions (for example, the shape, degree of compression bonding, temperature, and linear stress of the adhesion region) which will be described later. The tensile strength and elongation product per basis weight of the spun-tie nonwoven fabric of the present invention are preferably 1.20 (N / 50 mm) / (g / m2) or more, and more preferably 1.20 (N / 50 mm) / (g / m2) to 10.0 (N / 50 mm) / (g / m2). The tensile strength and elongation product per basis weight are preferably 1.20 (N / 50 mm) / (g / m2) or more, more preferably 1.3 (N / 50 mm) / (g / m2) or more, still more preferably 1.4 (N / 50 mm) / (g / m2) or more, making it possible to provide a spun-tie nonwoven fabric that is flexible, has good feel and texture, and has excellent strength even when the basis weight is low. On the other hand, the tensile strength and elongation product per basis weight are preferably 10.0 (N / 50 mm) / (g / m2) or less, so as to prevent the flexibility of the spun-bonded nonwoven fabric from deteriorating or the texture from being damaged.The tensile strength and elongation product per basis weight can be controlled by appropriately adjusting, for example, the MFR of the polypropylene-based resin, additives, the average single fiber diameter of the core-sheath composite fiber, the Os / Oc ratio of the orientation parameter Os of the sheath component of the core-sheath composite fiber in the non-bonded area of ​​the spun-bonded nonwoven fabric to the orientation parameter Oc of the core component of the core-sheath composite fiber in the non-bonded area, and / or the spinning speed and thermal adhesion conditions (for example, shape, compression bonding degree, temperature, and linear stress of the adhesion region) which will be described later. In the present invention, for the tensile strength and elongation product of the spun-bonded nonwoven fabric per basis weight, a value measured by the procedures below in accordance with “6.3 Tensile strength and elongation rate (ISO method)” in “General Test Methods for Nonwoven Fabrics of JIS L1913:2010” is used. (1) Three test samples each measuring 50 mm x 300 mm were taken per 1 m width of the non-woven fabric in each direction where one long side was in the machine direction (longitudinal direction of the non-woven fabric) and the transverse direction (width direction of the non-woven fabric) of the non-woven fabric. (2) Each test sample is fixed in the tensile tester at a grip interval of 200 mm. (3) The tensile test was carried out at a pulling rate of 100 mm / min, and the maximum strength and elongation at the maximum strength were measured. Here, the elongation was not converted to 100 fractions (%). (4) The average value of the maximum strength and elongation at the maximum strength measured for each test sample was obtained, and the tensile strength and elongation product per basis weight were calculated based on the following formula, and rounded to two decimal places. Tensile strength and elongation product per basis weight ((N / 50 mm) / (g / m2)) = [average value of maximum strength (N / 50 mm)] x [average value of elongation at maximum strength (-)] / basis weight (g / m2) The tensile strength of the spun-tie nonwoven fabric of the present invention in the transverse direction (width direction of the nonwoven fabric) per basis weight is preferably 0.40 (N / 25 mm) / (g / m2) or more, and more preferably 0.40 (N / 25 mm) / (g / m2) to 2.00 (N / 25 mm) / (g / m2). The tensile strength per basis weight is preferably 0.40 (N / 25 mm) / (g / m2) or more, more preferably 0.60 (N / 25 mm) / (g / m2) or more, and still more preferably 0.80 (N / 25 mm) / (g / m2) or more, making it possible to provide a spun-tie nonwoven fabric having a strength that can be used in practical use. On the other hand, the tensile strength in the transverse direction per basis weight is preferably 2.00 (N / 25 mm) / (g / m2) or less, so that it is possible to prevent the reduction of the flexibility of the spun-tie nonwoven fabric or the destruction of the texture.Although the tensile strength of spun-bonded nonwoven fabrics is in both the machine direction (longitudinal direction of the nonwoven fabric) and the transverse direction (width direction of the nonwoven fabric), generally, the tensile strength in the transverse direction is smaller than the tensile strength in the machine direction. Therefore, the tensile strength in the transverse direction per basis weight is 0.4 to 2.00 (N / 25 mm) / (g / m2), making it possible to provide spun-bonded nonwoven fabrics that have strength that can be used in practical use in the machine direction.The tensile strength in the transverse direction per basis weight can be controlled by appropriately adjusting, for example, the MFR of the polypropylene-based resin, additives, the average single fiber diameter of the core-sheath composite fiber, the Os / Oc ratio of the orientation parameter Os of the sheath component of the core-sheath composite fiber in the non-bonded area of ​​the spun-bonded nonwoven fabric to the orientation parameter Oc of the core component of the core-sheath composite fiber in the non-bonded area, and / or the spinning speed and the thermal adhesion conditions (for example, the shape, degree of compression bonding, temperature, and linear stress of the adhesion region) which will be described later. In the present invention, for the tensile strength of spun-bonded nonwoven fabric in the transverse direction per basis weight, a value measured by the procedures below in accordance with “6.3 Tensile strength and elongation rate (ISO method)” in “General Test Methods for Nonwoven Fabrics of JIS L1913:2010” is used. (1) Three test samples of 25 mm x 200 mm are collected per 1 m width of the non-woven fabric to make the long side in the transverse direction of the non-woven fabric (width direction of the non-woven fabric). (2) The test sample is fixed on the tensile testing machine at a grip interval of 100 mm. (3) Tensile testing is carried out at a tensile speed of 100 mm / min to measure maximum strength. (4) The average value of the maximum strength measured with each of the test samples is determined, and the tensile strength per basis weight is calculated based on the expression below and rounded to two decimal places. Tensile strength in the transverse direction per basis weight ((N / 25 mm) / (g / m2)) = [average value of maximum strength (N / 25 mm)] / basis weight (g / m2) The tension at 5% elongation of the spun-tie nonwoven fabric of the present invention in the machine direction per basis weight is preferably 0.40 (N / 25 mm) / (g / m2) or more, and more preferably 0.40 (N / 25 mm) / (g / m2) to 2.00 (N / 25 mm) / (g / m2). The tension at 5% elongation in the machine direction per basis weight is preferably 0.40 (N / 25 mm) / (g / m2) or more, more preferably 0.50 (N / 25 mm) / (g / m2) or more, and still more preferably 0.60 (N / 25 mm) / (g / m2) or more, so that it is possible to suppress the elongation due to tension during the production of the spun-tie nonwoven fabric or during processing for sanitary use, and stably produce the spun-tie nonwoven fabric with a high yield. Furthermore, the tension at 5% elongation in the machine direction per basis weight is preferably 2.00 (N / 25 mm) / (g / m2) or less, so as to prevent a decrease in the flexibility of the spun-tie nonwoven fabric or a deterioration in the texture.The stress at 5% elongation in the machine direction per basis weight can be controlled by appropriately adjusting, for example, the MFR of the polypropylene-based resin, additives, the average single fiber diameter of the core-sheath composite fiber, the ratio (Os / Oc) of the orientation parameter Os of the sheath component of the core-sheath composite fiber in the non-bonded area of ​​the spun-bonded nonwoven fabric to the orientation parameter Oc of the core component of the core-sheath composite fiber in the non-bonded area, and / or the spinning speed and thermal adhesion conditions (for example, shape, compression bonding degree, temperature, and linear stress of the adhesion region) which will be described later. In the present invention, for the stress at elongation of 5% of the spun-bonded nonwoven fabric in the machine direction per basis weight, a value measured by the procedures below in accordance with “6.3 Tensile strength and elongation rate (ISO method)” in “General Test Methods for Nonwoven Fabrics” of JIS L1913:2010 is used. (1) Three test samples of 25 mm x 200 mm are collected per 1 m width of non-woven fabric to make the long side in the machine direction of the non-woven fabric (longitudinal direction of the non-woven fabric). (2) The test sample is fixed on the tensile testing machine at a grip interval of 100 mm. (3) The tensile test was carried out at a tensile speed of 100 mm / min, and the stress during 5% elongation (stress at 5% elongation) was measured. (4) The average value of the stress at 5% elongation measured for each test sample is determined, the stress at 5% elongation in the machine direction per basis weight is calculated based on the expression below, and rounded to two decimal places. Stress at 5% elongation in the machine direction per basis weight ((N / 25 mm) / (g / m2)) = [average value of stress at 5% elongation (N / 25 mm)] / basis weight (g / m2) [Method for producing spun-tie nonwoven fabric] Next, a preferred aspect of the method for producing the spun-tie nonwoven fabric of the present invention will be specifically described. The spun-tie nonwoven fabric of the present invention is a long fiber nonwoven fabric produced by the spun-tie method. The spun-tie method is excellent in productivity and mechanical strength, and can suppress fluffing and fiber unraveling, which are likely to occur in short fiber nonwoven fabrics. In addition, the stacking of a plurality of layers of gathered spun-tie nonwoven fiber web or thermocompression-bonded spun-tie nonwoven fabric (both indicated as S) with SS, SSS, and SSSS improves productivity and texture uniformity, which are preferred aspects. In the spun-bond method, thermoplastic resin is first spun from a spinning reel as long fibers, the long fibers are sucked with compressed air by an ejector, and then the fibers are collected on a moving net to obtain a nonwoven fiber web. In addition, the obtained nonwoven fiber web is treated with thermal adhesion to obtain a spun-bond nonwoven fabric. The shape of the spinning anti-spinning device or ejector is not particularly limited, but for example, various shapes such as circular and rectangular shapes can be used. Among these shapes, a combination of a rectangular anti-spinning device and a rectangular ejector is preferred, because the amount of compressed air used is relatively small, the energy cost is low, yarn binding and abrasion do not occur, and yarn opening is easy. In the present invention, a thermoplastic resin is melted in an extruder, weighed, fed to a spinning device for core-sheath composite fibers to be produced, and spun as long fibers. The spinning temperature when the thermoplastic resin is melted and spun is preferably 180 °C to 250 °C, more preferably 200 °C to 240 °C, and still more preferably 220 °C to 230 °C. Setting the spinning temperature within the range described above can provide a stable melting state and excellent spinning stability. The spun long fiber yarns are then cooled. Examples of methods for cooling the spun yarns include methods where cold air is forced onto the yarn, methods where the yarns are cooled naturally to ambient room temperature around the yarn, and methods where the distance between the spinning deflector and the ejector is adjusted, or methods where a combination of these methods can be used. Furthermore, the cooling conditions can be adjusted and used accordingly considering, for example, the amount of output from the spinning deflector per single hole, the spinning temperature, and the ambient temperature. Next, the cooled and solidified threads are drawn with compressed air discharged from the ejector. The spinning speed is preferably 3,000 m / min to 6,000 m / min, more preferably 3,500 m / min to 5,500 m / min, and still more preferably 4,000 m / min to 5,000 m / min. Setting the spinning speed to 3,000 m / min to 6,000 m / min can provide high productivity, and in addition, orientation crystallization of the fiber occurs, making it possible to provide long fibers having high strength. As previously described, the core-sheath composite fiber containing the polypropylene-based resin of the present invention as the main component has excellent spinning stability and can be stably produced even at high spinning speeds. Next, the long fibers obtained are collected on a moving net to form a non-woven fiber net. In the present invention, it is also a preferred aspect that the hot flat roller is contacted with the nonwoven fiber web from one side thereof on the web and temporary adhesion. Therefore, it is possible to prevent the surface layer of the nonwoven fiber web from being turned over or detached during delivery on the web and deterioration of the texture, and improve the delivery ability from yarn collection to thermocompression bonding. Next, the obtained nonwoven fiber web is tied to form a bonding area, and the intended spun-tie nonwoven fabric can be obtained. Methods for bonding nonwoven fiber webs are not particularly limited, and examples thereof include methods wherein the nonwoven fiber web is thermally bonded with various rollers, such as hot-embossing rollers wherein the upper and lower roller surfaces in pairs are each etched (having an uneven portion), hot-embossing rollers formed by a combination of rollers wherein one of the roller surfaces is flat (smooth) and rollers wherein the other roller surface is etched (having an uneven portion), and hot-flattening rollers formed by a combination of upper and lower flat (smooth) rollers in pairs; methods wherein the nonwoven fiber web is thermally bonded by ultrasonic vibration of a funnel; and methods wherein the nonwoven fiber web is penetrated with hot air to soften or melt the surfaces of the core-sheath composite fibers, and the fiber intersections are thermally bonded to each other. Among the rollers, it is preferred to use a hot-embossing roller in which the upper and lower roller surfaces in pairs are each metered (being an uneven portion), or a hot-embossing roller that includes a combination of a roller in which one of the roller surfaces is flat (smooth) and a roller in which the other roller surface is engraved (being an uneven portion). Therefore, it is possible to provide a bonding area that is good in productivity and improves the strength of the spun-bonded nonwoven fabric, and a non-bonding area that improves the texture and feel. As a surface material of a hot embossing roller, it is a preferred aspect that a metal roller and another metal roller are made into pairs to obtain sufficient thermocompression bonding effect and prevent the engraving (uneven portion) of one of the embossing rollers from transferring to the surface of the other roller. The degree of adhesion area of ​​embossing with the hot embossing roller is preferably 5 to 30%. Setting the adhesion area to preferably 5% or more, more preferably 8% or more, and still more preferably 10% or more can provide strength that can be used in practical use as a spun-bonded nonwoven fabric. On the other hand, setting the adhesion area to preferably 30% or less, more preferably 25% or less, and still more preferably 20% or less can provide appropriate flexibility that is suitable for use in particular in the use of paper diapers as a spun-bonded nonwoven fabric for sanitary materials. The degree of adhesion area is preferably in a similar range even in the case of ultrasonic adhesion use. The adhesion area referred to herein refers to the percentage of the adhesion portion to the entire spun-bonded nonwoven fabric. Specifically, in the case of thermal adhesion with a pair of uneven rollers, the adhesion area refers to the percentage of the portion (adhesion portion) in which a convex portion of the upper roller and a convex portion of the lower roller overlap each other and make contact with the nonwoven fiber web to the entire spun-bonded nonwoven fabric. Furthermore, in the case of thermal adhesion with uneven rollers and flat rollers, the adhesion area refers to the percentage of the portion (adhesion portion) in which the convex portion of the uneven roller makes contact with the nonwoven fiber web to the entire spun-bonded nonwoven fabric. Furthermore, in the case of ultrasonic adhesion, the adhesion area refers to the percentage of the portion (adhesion portion) that is heat-sealed by ultrasonic processing to the entire spun-bonded nonwoven fabric.In the case where sufficient heat is applied to the adhesion region during thermal adhesion and all core-sheath composite fibers of the adhesion region are bonded, the area of ​​the adhesion region and the bonding area can be considered equal. Although the shape of the adhesion member by hot embossing roller and ultrasonic adhesion is not particularly limited, for example, a circular shape, an elliptical shape, a square shape, a rectangular shape, a parallelogram shape, a rhombus shape, a regular hexagon shape, and a regular octagon shape can be used. Furthermore, the adhesion members are preferably located in a uniform manner at regular intervals in each of the longitudinal direction (delivery direction) and the width direction of the spun-bonded nonwoven fabric. Therefore, it is possible to reduce the strength variation of the spun-bonded nonwoven fabric. It is a preferred aspect that the surface temperature of the thermal embossing roll during thermal adhesion is set to a temperature lower by 30 °C to higher by 10 °C than the melting point (hereinafter, may be described as Tms (°C)) of the thermoplastic resin composing the used sheath component (i.e., (Tms -30 °C) to (Tms +10 °C)). Setting the surface temperature of the hot roll to preferably -30 °C and or more (i.e., (Tms -30 °C) and so on) or more, more preferably -20 °C or more ((Tms 20 °C) or more), and still more preferably -10 °C or more ((Tms -10 °C) or more) relative to the melting point of the thermoplastic resin can provide a thermally bonded spun-bonded nonwoven fabric that is strong and has strength that is usable in practical use.In addition, setting the surface temperature of the thermal embossing roller to preferably +10 °C or less ((Tms +10 °C) or less), more preferably +5 °C or less ((Tms +5 °C) or less), and still more preferably +0 °C or less ((Tms +0 °C) or less) relative to the melting point of the thermoplastic resin suppresses excessive thermal adhesion and can provide moderate flexibility suitable for use in particular in paper diaper applications as a spun-bonded nonwoven fabric for sanitary materials. The linear pressure of the hot embossing roller during thermal adhesion is preferably 50 N / cm to 500 N / cm. Setting the linear pressure of the roller to preferably 50 N / cm or more, more preferably 100 N / cm or more, and still more preferably 150 N / cm or more provides strong thermal adhesion and can provide a spun-bonded nonwoven fabric having strength that is usable in practical use. On the other hand, setting the linear pressure of the hot embossing roller to preferably 500 N / cm or less, more preferably 400 N / cm or less, and still more preferably 300 N / cm or less can provide moderate flexibility that is suitable for use in particular in the use of paper diapers as a spun-bonded nonwoven fabric for sanitary materials. Furthermore, in the present invention, thermocompression bonding can be performed with a hot flattening roller comprising paired upper and lower flat rollers before and / or after thermal adhesion with the above-described hot embossing roller for the purpose of adjusting the thickness of the spunbond nonwoven fabric. The paired upper and lower flat rollers are metal rollers or elastic rollers without concave and convex portions on the roller surface, and one metal roller and another metal roller can be used in pairs, or one metal roller and another elastic roller can be used in pairs. Furthermore, here, elastic rollers refer to rollers made of elastic materials when compared to metal rollers. Examples of elastic rollers include so-called paper rollers such as paper, cotton, and aramid paper, and resin rollers made of urethane-based resins, epoxy-based resins, silicone-based resins, polyester-based resins, hard rubber, and mixtures thereof. The spun-bonded nonwoven fabric of the present invention has excellent flexibility and tactile feel, uniform texture, sufficient strength to be used in practical applications, and excellent productivity, and thus can be widely used for sanitary materials, medical materials, daily life materials, industrial materials, or the like. In particular, the fabric can be suitably used as, for example, the base cloth of paper diapers, physiological articles and poultice materials in the case of sanitary materials, and as, for example, protective clothing and surgical gowns in the case of medical materials. Examples Next, the spun-tie nonwoven fabric of the present invention will be specifically described based on examples. However, the present invention is not limited to these examples. Unless otherwise described, each physical property is measured based on the methods described above. [Measurement method] (1) Resin melt flow rate (MFR) (g / 10 min) The MFR of the resin was measured by the above method under the conditions of a load of 2.16 kg and a temperature of 230 °C. (2) Average single fiber diameter (μη) of core-sheath composite fibers that make up spun-bonded nonwoven fabrics The measurements were carried out by the method described previously using the electron microscope “VHX-D 500” manufactured by KEYENCE CORPORATION. (3) Spinning speed (m / min) The mass per 10,000 m length is calculated by rounding to one decimal place as the average single fiber fineness (dtex) of the average single fiber diameter described above and the solid density of the resin (0.91 g / cm3). The spinning speed is calculated as two significant figures based on the formula below from the average single fiber fineness and the output amount (hereinafter, abbreviated as the single hole output amount) (g / min) of the resin discharged from the single hole of the spinning antih tool, the output amount being determined under each condition. Spinning speed (m / min) = (10,000 x [number of single hole output (g / min)]) / [average single fiber fineness (dtex)] (4) Core-sheath composite fiber orientation parameters of the non-bonded area of ​​the spun-bonded nonwoven fabric The measurements were carried out by the method described previously using a triple Raman spectrometer T64000” manufactured by Atago Bussan Co., Ltd. The measurement conditions were as follows. □ Measurement mode: Raman microscopic (polarization measurement) □ Objective lens: x100 □ Beam diameter: 1 μm □ Light source: Ar+ / 514.5 nm laser □ Laser power: 60 mW □ Diffraction grating: Single 1800 g / mm □ Cross slit: 100 μm □ Detector: CCD / Jobin Yvon 1024 x256 (5) Melting peak temperature (Tm) (°C) of spun-tie nonwoven fabric The measurements were carried out using the method described previously using the DSC8500” manufactured by PerkinElmer, Inc. as the measuring equipment. The measurement conditions were as follows. □ Atmosphere in the apparatus: nitrogen (20 mL / min) □ Temperature / heat calibration: high purity indium (Tm = 156.61 °C, and AHm = 28.70 J / g) □ Temperature range: 20 °C to 200 °C □ Rise rate: 20 °C / min □ Sample amount: approximately 0.5 to 4 mg □ Sample container: standard container made of aluminum If a single melting peak temperature (Tm) (°C) is observed in the spun-tie nonwoven fabrics in the table, the value is explained, and if a number of melting peak temperatures (Tm) (°C) are observed, the value is explained. For the melting point of the polypropylene-based resin used in the Examples, the peak melting temperature was measured in the same manner as in the method for measuring the peak melting temperature except that the polypropylene-based resin used was sampled, and set to the maximum (highest) peak melting temperature obtained. (6) Flexural resistance (mm) of spun-bonded nonwoven fabric in machine direction The flexural strength of spunbonded nonwoven fabrics is measured in the machine direction (longitudinal direction) of the nonwoven fabric according to the method described in “6.7.4 Gurley Method” in “6.7 Flexural strength (JIS method and ISO method)” in “General Test Methods for Nonwoven Fabrics” of JIS L1913:2010. In any spunbonded nonwoven fabric, the flexural strength in the machine direction (longitudinal direction) is greater than the flexural strength in the transverse direction (width direction). Since the flexural strength is smaller in the machine direction, the flexibility is better, and 65 mm or less is considered acceptable. (7) Tensile strength per base weight of non-woven fabric (N / 25 mm / (g / m2)) The measurements were carried out by the method described previously using “RTG-1250” manufactured by A & D Company, Limited as the measuring equipment. The tensile strength in the machine direction is also higher because the tensile strength per basis weight in the transverse direction is higher, but 0.80 (N / 25 mm) / (g / m2) or more is considered acceptable. (8) Tensile strength and elongation product per basis weight of spun-bonded nonwoven fabric (N / 50 mm / (g / m2)) The measurement was carried out by the method described previously using “RTG-1250” manufactured by A & D Company, Limited as the measuring equipment. Because the tensile strength and elongation product per basis weight are greater, the spun-bonded nonwoven fabric is softer and has a much better balance among feel, texture, and strength, but 1.20 (N / 50 mm) / (g / m2) or more is considered acceptable. (Example 1) Using a polypropylene resin composed of a homopolymer having a melt flow rate (MFR) of 35 g / 10 min and a melting point of 163 °C as the core component and a polypropylene resin composed of a homopolymer having a MFR of 60 g / 10 min and a melting point of 163 °C as the sheath component, each of the resins was melted by an extruder, and a concentric core-sheath composite fiber having a sheath component ratio of 30% by mass was spun from a spinning de-icer having a hole diameter of φ 0.40 mm and a hole depth of 0.8 mm at a spinning temperature of 235 °C and a single hole output of 0.40 g / min. The spun yarns were cooled and compacted, then drawn with compressed air in an ejector, and collected on a moving web to form a spun-bonded nonwoven fiber web formed by polypropylene-based long fibers.The properties of the core-sheath composite fibers that make up the formed nonwoven fiber web are that the average single fiber diameter is 14.0 μm and the spinning speed converted from it is 2,900 m / min. The spinnability is good because no yarn breakage was observed in spinning for 1 hour. Next, the formed nonwoven fiber web is thermally bonded under the conditions of a linear pressure of 500 N / cm and a thermal adhesion temperature of 140 °C using a pair of upper and lower thermal embossing rollers including the following upper roller and lower roller to provide a spun-bonded nonwoven fabric having a basis weight of 15 g / m2 with a bonded area and a non-bonded area. (Upper roller): Embossing roller made of metal, engraved with a dot pattern, and has an adhesion area rate of 11% (Lower roller): metal flat roller The resulting spun-tie nonwoven fabric has a uniform texture and excellent tactile feel. The evaluation results are shown in Table 1. (Example 2) A spun-tie nonwoven fabric having bonded and nonbonded areas was obtained by the same method as in Example 1 except that the basis weight was 10 g / m2. The properties of the fibers composing the formed spun-tie nonwoven fiber web were that the average single fiber diameter was 14.0 μη, and the spinning speed converted from it was 2,900 m / min. The spinnability was good because no yarn breakage was observed in spinning for 1 hour. The obtained spun-tie nonwoven fabric was uniform in texture and had excellent tactile feel. The evaluation results are shown in Table 1. (Example 3) A spun-tie nonwoven fabric having bonded and nonbonded areas was obtained by the same method as in Example 1 except that the basis weight was 30 g / m2. The properties of the fibers composing the formed spun-tie nonwoven fiber web were that the average single fiber diameter was 14.0 μη, and the spinning speed converted from it was 2,900 m / min. The spinnability was good because no yarn breakage was observed in spinning for 1 hour. The obtained spun-tie nonwoven fabric was uniform in texture and had excellent tactile feel. The evaluation results are shown in Table 1. (Example 4) A spun-bonded nonwoven fabric having a bonded area and a non-bonded area was obtained by the same method as in Example 1 except that the ratio of the sheath component was 50% by mass and the thermal adhesion temperature was 145 °C. The properties of the fibers composing the formed spun-bonded nonwoven fiber web were that the average single fiber diameter was 14.0 μη, and the spinning speed converted from it was 2,900 m / min. The spinning power was good because no yarn breakage was observed during spinning for 1 hour. The resulting ikat spun-bonded nonwoven fabric had a uniform texture and excellent feel. The evaluation results are shown in Table 1. (Example 5) A spun-tie nonwoven fabric having bonded and nonbonded areas was obtained by the same method as in Example 1 except that the pressure of compressed air was regulated in the ejector. The properties of the fibers composing the formed spun-tie nonwoven fiber web were that the average single fiber diameter was 11.2 μη, and the spinning speed converted from it was 4,400 m / min. The spinnability was good because no yarn breakage was observed in spinning for 1 hour. The obtained spun-tie nonwoven fabric was uniform in texture and had excellent tactile feel. The evaluation results are shown in Table 1. (Example 6) A spun-tie nonwoven fabric having bonded and nonbonded areas was obtained by the same method as in Example 1 except that a polypropylene resin composed of a homopolymer having an MFR of 170 g / 10 min and a melting point of 161 °C was used as the sheath component. The properties of the fibers composing the formed spun-tie nonwoven fiber web were that the average single fiber diameter was 14.0 μη, and the spinning speed converted from it was 2,900 m / min. The spinnability was good as no yarn breakage was observed in spinning for 1 h. The obtained spun-tie nonwoven fabric was uniform in texture and had excellent tactile feel. The evaluation results are shown in Table 1. (Example 7) A spun-tie nonwoven fabric having a bonded area and a non-bonded area was obtained by the same method as in Example 1 except that a polypropylene resin composed of a homopolymer having an MFR of 30 g / 10 min and a melting point of 148 °C was used as the sheath component, and the thermal adhesion temperature by a pair of upper and lower thermal embossing rollers was 130 °C. The properties of the fibers composing the formed spun-tie nonwoven fiber web were that the average single fiber diameter was 14.0 μη, and the spinning speed converted from it was 2,900 m / min. The spinnability was good because no yarn breakage was observed in spinning for 1 h. The obtained spun-tie nonwoven fabric was uniform in texture and had excellent tactile feel. The evaluation results are shown in Table 1. (Example 8) A spun-tie nonwoven fabric having bonded and nonbonded areas was obtained by the same method as in Example 1 except that a polypropylene resin composed of a homopolymer having an MFR of 20 g / 10 min and a melting point of 163 °C was used as the core component. The properties of the fibers composing the formed spun-tie nonwoven fiber web were that the average single fiber diameter was 14.0 μη, and the spinning speed converted from it was 2,900 m / min. The spinnability was good because no yarn breakage was observed in spinning for 1 h. The obtained spun-tie nonwoven fabric was uniform in texture and had excellent tactile feel. The evaluation results are shown in Table 1. (Comparative Example 1) A spun-bonded nonwoven fabric having a bonded area and a non-bonded area was obtained by the same method as in Example 1 except that a single-component fiber using only a polypropylene resin composed of a homopolymer having a melt flow rate (MFR) of 35 g / 10 min and a melting point of 163 °C was used, and the thermal adhesion temperature was 150 °C. The properties of the fibers composing the formed spun-bonded nonwoven fiber web were that the average single fiber diameter was 14.0 μη, and the spinning speed converted from it was 2,900 m / min. For the spinnability, yarn breakage occurred twice in spinning for 1 h. The evaluation results of the obtained spun-bonded nonwoven fabric are shown in Table 1. The thermal adhesion temperature was set to 155 °C, which caused the problem that the edge of the sheet stuck to the hot roller, and the delivery was poor. (Comparative Example 2) A spun-tie nonwoven fabric having a bonded area and a nonbonded area was obtained by the same method as in Example 1 except that a polypropylene resin composed of a homopolymer having an MFR of 45 g / 10 min and a melting point of 163 °C was used as the sheath component, and the thermal adhesion temperature was 150 °C. The properties of the fibers composing the formed spun-tie nonwoven fiber web were that the average single fiber diameter was 14.0 μη, and the spinning speed converted from it was 2,900 m / min. The spinnability was good because no yarn breakage was observed in spinning for 1 h. The evaluation results of the obtained spun-tie nonwoven fabric are shown in Table 1. [Table 1-1] Unit Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 MFR of polypropylene based resin g / 10 min (Core) 35 (Sheath) 60 (Core) 35 (Sheath) 60 (Core) 35 (Sheath) 60 (Core) 35 (Sheath) 60 (Core) 35 (Sheath) 60 (Core) 35 (Sheath) 170 Sheath component ratio %mass 30 30 30 50 30 30 Average single fiber diameter pm 14.0 14.0 14.0 14.0 11.2 14.0 Spinning speed m / min 2 . 900 2 . 900 2 . 900 4,400 2 .900 Basis weight, 2 g / m 15 10 30 15 15 15 Fiber orientation parameters in the non-bonded area (Core: Oc, Sheath: Os) - (Core) 10.9 (Sheath) 4.1 (Core) 10.9 (Sheath) 4.1 (Core) 10.9 (Sheath) 4.1 (Core) 11.0 (Sheath) 5.7 (Core) 13.7 (Sheath) 3.6 (Core) 12.1 (Sheath) 5.0 Orientation ratio of sheath component to core component of fiber in the non-bonded area (Os / Oc) - 0.38 0.38 0.38 0.52 0.26 0.41 Peak melting temperature (Tm) by DSC °C 163 163 163 163 163 162 Bending resistance in machine direction mm 64 56 91 63 68 60 Tensile strength in transverse direction per basis weight N / 25 mm / (g / m2) 0.92 0.81 1.05 0.86 0.81 0.80 Tensile strength and elongation product per basis weight N / 50 mm / (g / m ) 1.84 1.23 3.00 1.75 2.21 1.53. [Table 1-2] Unit Example 7 Example 8 Comparative Example 1 Comparative Example 2 MFR of polypropylene-based resin g / 10 min (Core) 35 (Sheath) 30 (Core) 20 (Sheath) 60 35 (Core) 35 (Sheath) 45 Sheath component ratio %mass 30 30 - 30 Average single fiber diameter μη 14.0 14.0 14.0 14.0 Spinning speed m / min 2,900 2,900 2,900 2,900 Basis weight , 2 g / m 15 15 15 15 Fiber orientation parameters in the non-bonded area (Core: Oc, Sheath: Os) (Core) 11.6 (Sheath) 3.2 (Core) 6.2 (Sheath) 4.7 9.7 (Core) 9.8 (Sheath) 9.0 Orientation ratio of sheath component to core fiber component in non-bonded area (Os / Oc) 0.28 0.76 - 0.92 Peak melting temperature (Tm) by DSC °C 163, 148 163 163 163 Flexural strength in machine direction mm 64 62 66 65 Tensile strength in transverse direction per basis weight N / 25 mm / (g / m2) 0.83 0.94 0.76 0.78 Tensile strength and elongation product per basis weight N / 50 mm / (g / m2) 1.70 1.85 1.13 1.17 The spun-bonded nonwoven fabrics of Examples 1 to 8, of which 5 are composed of core-sheath composite fibers containing polypropylene-based resin as the main component, wherein the ratio (Os / Oc) of the orientation parameter Os of the sheath component of the core-sheath composite fiber in the non-bonded area to the orientation parameter Oc of the core component of the core-sheath composite fiber in the non-bonded area satisfies 0.10 to 0.90, have excellent strength even at a low basis weight, and excellent flexibility and feel. On the other hand, the spun-tie nonwoven fabric composed of a single polypropylene resin of Comparative Example 1 and the spun-tie nonwoven fabric of Comparative Example 2 having an Os / Oc greater than 0.90 are poor in strength and flexibility.

Claims

1. A spun-bonded nonwoven fabric comprising a core-sheath composite fiber containing a polypropylene-based resin as the main component, wherein the spun-bonded nonwoven fabric has a bonded area and a non-bonded area, and the ratio (Os / Oc) of the orientation parameter Os of the sheath component of the core-sheath composite fiber in the non-bonded area to the orientation parameter Oc of the core component of the core-sheath composite fiber in the non-bonded area is 0.10 to 0.

90.

2. The spun-bonded nonwoven fabric according to claim 1, wherein the orientation parameter Os of the sheath component of the core-sheath composite fiber in the non-bonded area is 1.0 or more and 8.0 or less.

3. A spun-tie nonwoven fabric according to claim 1 or 2, wherein said spun-tie nonwoven fabric has a single melting peak temperature (Tm) (°C) in differential radiation calorimetry.

4. A spun-bonded nonwoven fabric according to claim 1 or 2, wherein the tensile strength and elongation product per basis weight of the spun-bonded nonwoven fabric are 1.20 (N / 50 mm) / (g / m2) or more.

5. A spun-bonded nonwoven fabric according to claim 1 or 2, wherein the melt flow rate of the polypropylene-based resin of the sheath component is greater than the melt flow rate of the polypropylene-based resin of the core component by 10 g / 10 min to 200 g / 10 min.