Spunbond nonwoven fabric and method for manufacturing the same, laminated nonwoven fabric, and sanitary material, clothing using the same

Abstract

To provide a spunbond nonwoven fabric having not only softness but also excellent mechanical properties, and easy high-order processing such as pleat processing, joining with other members, etc., the spunbond nonwoven fabric of the present application is composed of fibers formed from a polypropylene-based resin, and satisfies the following conditions (1) to (3), and the average single fiber diameter of the fibers is 5.0 μm or more and 20.0 μm or less. (1) The amount of organic peroxide is 100 ppm or more and 1000 ppm or less; (2) The melt flow rate is 20 g / 10 minutes or more and 400 g / 10 minutes or less; and (3) The branching degree λ of the polypropylene-based resin per 1 molecule is 1.0 x 10 ‑7 or more and 1.0 x 10 ‑3 or less.

Description

Technical Field

[0001] This invention relates to spunbond nonwoven fabrics that are not only soft but also have excellent mechanical properties and high processability, as well as methods for manufacturing the same and sanitary materials and clothing made therefrom. Background Technology

[0002] Spunbond nonwoven fabrics made from polyolefins, especially polypropylene spunbond nonwoven fabrics, are widely used primarily for hygiene applications due to their low cost and excellent processability.

[0003] In recent years, there has been a demand for further improvements in the softness of polypropylene spunbond nonwoven fabrics used in hygiene products. Several solutions have been proposed to date for this purpose.

[0004] For example, Patent Document 1 proposes a nonwoven web of microfibers formed from reactive particles of a treated polymer, the polymer having a specific molecular weight distribution and a certain melt flow rate.

[0005] Furthermore, Patent Document 2 discloses a method for manufacturing nonwoven fabric, which involves feeding a propylene polymer and an organic peroxide into an extruder (the extruder is equipped with a screw having a cross-cutting saw and a Unimert), melting and blending the propylene polymer resin composition containing the propylene polymer and the organic peroxide in the extruder, and then spinning the melt-blended propylene polymer resin composition to manufacture nonwoven fabric. Moreover, it is described that according to this method, nonwoven fabric with excellent spinnability can be obtained while suppressing filament breakage.

[0006] Furthermore, Patent Document 3 discloses a polypropylene resin composition containing an organic peroxide, characterized in that it is a resin composition formed by combining a certain amount of organic peroxide with a propylene / α-olefin random copolymer having certain properties polymerized using a metallocene catalyst, wherein the ratio of the melt flow rate of the resin composition to the melt flow rate of the resin composition after vacuum isothermal drying is a certain value or less. Moreover, it describes that such a resin composition, by being used alone or in combination with other polypropylene resins in the form of masterbatch, can be used as a useful resin composition for adjusting melt viscosity during molding processing.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 7-119014

[0010] Patent Document 2: Japanese Patent No. 6599078

[0011] Patent Document 3: Japanese Patent Application Publication No. 2003-138075 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] Patent Document 1 describes the following: According to its technology, by narrowing the molecular weight distribution of the polymer and further reducing the molecular weight of the polymer (i.e., increasing the melt flow rate), the nonwoven web of the invention can be manufactured efficiently by meltblowing. However, by adjusting the melt flow rate to a lower level, the following problems exist when obtaining spunbond nonwoven fabric: fiber strength will decrease, the mechanical properties of the nonwoven fabric will be significantly reduced, it will be difficult to perform pleating, high-level processing such as joining with other components, and the mechanical properties of the final product itself will deteriorate.

[0014] Furthermore, in the technologies proposed in patent documents 2 and 3, while increasing the melt flow rate of the resin can improve spinnability to some extent, the strength of the fibers constituting the nonwoven fabric will decrease. Therefore, there are problems such as a significant reduction in the mechanical properties of the nonwoven fabric, difficulty in pleating, difficulty in high-level processing such as joining with other components, and deterioration of the mechanical properties of the final product itself.

[0015] Therefore, the object of the present invention is to provide a spunbond nonwoven fabric that is not only soft but also has excellent mechanical properties and is easy to pleat and join with other components for advanced processing.

[0016] Methods for solving problems

[0017] The inventors of this application conducted research and discovered that, in order to make spunbond nonwoven fabrics softer, it is possible to make the fiber diameter finer and to make the fiber itself stronger in terms of excellent mechanical properties.

[0018] To achieve finer fiber diameters, using raw materials with high melt flow rates to increase spinning speed (drawing speed) is effective. However, as mentioned above, using raw materials with high melt flow rates results in reduced fiber strength, thus exhibiting opposite tendencies.

[0019] Therefore, the inventors of this application conducted further research and, as a result, conceived the following scheme: in order to further improve the melt flow rate of the raw material, a certain amount of peroxide used as a free radical generator is left in the spunbond nonwoven fabric, thereby using it as a crystal nucleating agent, and the degree of branching λ is kept within a specific range.

[0020] Furthermore, based on the above insights, the inventors of this application conducted in-depth research to solve the aforementioned problems. As a result, they discovered that by setting the amount of organic peroxide and the degree of branching λ of the polypropylene resin constituting the spunbond nonwoven fabric to a specific range, and further setting the melt flow rate of the spunbond nonwoven fabric to a specific range, the softness is improved due to the finer fiber diameter. Moreover, by suppressing defects in the nonwoven fabric caused by fiber breakage, a high-quality spunbond nonwoven fabric is obtained. Furthermore, by suppressing the orientation relaxation of the obtained fibers, the molecular orientation (Δn) is improved. As a result, the strength of the fibers is improved, resulting in a spunbond nonwoven fabric with excellent mechanical properties and easy to perform advanced processing such as pleating and joining with other components. Thus, the present invention was completed.

[0021] The present invention aims to solve the above-mentioned problems, and the following solutions can be provided according to the present invention.

[0022] [1] Spunbond nonwoven fabric, which is a spunbond nonwoven fabric made of fibers formed from polypropylene resin, wherein the spunbond nonwoven fabric satisfies the following conditions (1) to (3), and the average single fiber diameter of the fibers is more than 5.0 μm and less than 20.0 μm.

[0023] (1) The amount of organic peroxide extracted by ultrasonic treatment of the spunbond nonwoven fabric impregnated in a chloroform / methanol solvent with a volume ratio of 1:1 at 15 minutes, 45 kHz and a solution temperature of 30 °C is more than 100 ppm and less than 1000 ppm.

[0024] (2) The melt flow rate of the polypropylene resin is more than 20g / 10min and less than 400g / 10min;

[0025] (3) The degree of branching λ per molecule of the polypropylene resin, calculated using the molecular weight and radius of gyration determined by gel permeation chromatography / multi-angle light scattering analyzer and the trifunctional random branching theory, is 1.0 × 10⁻⁶. -7 Above 1.0×10 -3 the following.

[0026] [2] According to the spunbond nonwoven fabric described in [1], wherein the polypropylene resin further satisfies the following conditions (4) and (5).

[0027] (4) 2.50≤Mw / Mn≤3.20;

[0028] (5) 1.82≤Mz / Mw≤2.20

[0029] Wherein, Mw, Mn, and Mz are the weight-average molecular weight, number-average molecular weight, and z-average molecular weight obtained by gel permeation chromatography, respectively.

[0030] [3] The method for manufacturing spunbond nonwoven fabric described in [1] or [2] comprises:

[0031] The process of adding an organic peroxide to a raw material resin to decompose the raw material resin, thereby obtaining a polypropylene resin prepared in a manner that satisfies the following conditions (1) to (3);

[0032] The process of spinning the polypropylene resin to obtain fibers with an average single fiber diameter of 5.0 μm to 20.0 μm; and

[0033] The process of capturing the fibers.

[0034] (1) The residual amount of organic peroxide extracted by ultrasonic treatment of the spunbond nonwoven fabric impregnated in a chloroform / methanol solvent with a volume ratio of 1:1 at 15 minutes, 45 kHz and a solution temperature of 30 °C is more than 100 ppm and less than 1000 ppm.

[0035] (2) The melt flow rate of the polypropylene resin is more than 20g / 10min and less than 400g / 10min;

[0036] (3) The degree of branching λ per molecule of the polypropylene resin, calculated using the molecular weight and radius of gyration determined by gel permeation chromatography / multi-angle light scattering analyzer and the trifunctional random branching theory, is 1.0 × 10⁻⁶. -7 Above 1.0×10 -3 the following.

[0037] [4] The manufacturing method of spunbond nonwoven fabric described in [3] wherein the raw material resin is a recycled resin.

[0038] [5] A laminated nonwoven fabric comprising the spunbond nonwoven fabric described in [1] or [2].

[0039] [6] A sanitary material made of spunbond nonwoven fabric described in [1] or [2] or laminated nonwoven fabric described in [5].

[0040] [7] Clothing made of spunbond nonwoven fabric described in [1] or [2] or laminated nonwoven fabric described in [5].

[0041] The effects of the invention

[0042] In addition to its high quality and softness, the spunbond nonwoven fabric of this invention promotes orientation crystallization due to the effect of residual organic peroxides as nucleating agents by a certain amount of organic peroxides in the nonwoven fabric. Furthermore, by setting the degree of branching λ per molecule within a specific range, it is possible to suppress the orientation relaxation of fibers after traction in the spunbonding process, exhibiting excellent mechanical properties. Moreover, it also demonstrates excellent ease of high-level processing, such as pleating and joining with other components. Detailed Implementation

[0043] The spunbond nonwoven fabric of the present invention is a spunbond nonwoven fabric composed of fibers formed from polypropylene resin, wherein the spunbond nonwoven fabric satisfies the following conditions (1) to (3), and the average single fiber diameter of the fibers is 5.0 μm or more and 20.0 μm or less.

[0044] (1) The amount of organic peroxide extracted by ultrasonic treatment of the spunbond nonwoven fabric impregnated in a chloroform / methanol solvent with a volume ratio of 1:1 at 15 minutes, 45 kHz and a solution temperature of 30 °C is more than 100 ppm and less than 1000 ppm.

[0045] (2) The melt flow rate is above 20g / 10min and below 400g / 10min;

[0046] (3) The degree of branching λ per molecule of the polypropylene resin, calculated using the molecular weight and radius of gyration determined by gel permeation chromatography / multi-angle light scattering analyzer and the trifunctional random branching theory, is 1.0 × 10⁻⁶. -7 Above 1.0×10 -3 the following.

[0047] The spunbond nonwoven fabric of the present invention will be described in detail below. However, the present invention is not limited to the scope of the following description as long as it does not depart from its spirit, and various modifications can be made without departing from the spirit of the present invention.

[0048] [Polypropylene Resin]

[0049] The spunbond nonwoven fabric of the present invention is composed of fibers (polypropylene fibers) made of a polypropylene-based resin. In this invention, the term "polypropylene-based resin" refers to a resin in which the molar fraction of propylene units in the repeating units is 80 mol% to 100 mol%. By using a polypropylene-based resin, a low-cost spunbond nonwoven fabric with excellent softness can be produced.

[0050] Examples of polypropylene-based resins used in this invention include homopolymers of propylene and copolymers of propylene with various α-olefins. When using copolymers of propylene with various α-olefins as the polypropylene-based resin, the copolymerization ratio of the various α-olefins is preferably 10 mol% or less, more preferably 5 mol% or less, and even more preferably 3 mol% or less, in order to further improve the tensile strength of the fibers.

[0051] In the polypropylene resin used in this invention, other component resins may be mixed in without impairing the effects of the invention. Examples of other component resins include polyolefin resins such as polyethylene and poly-4-methyl-1-pentene, which have melting points similar to polypropylene. Other examples include low-melting-point polyester resins and low-melting-point polyamide resins. From the viewpoint of imparting softness, low-crystallinity olefin resins are preferred. Examples of low-crystallinity olefin resins include ethylene-propylene copolymers. In this case, to fully exhibit the characteristics of the polypropylene resin, the mass ratio of other component resins is preferably 20% by mass or less when the total mass ratio of the polypropylene resin and other component resins is set to 100% by mass, more preferably 10% by mass or less.

[0052] In the polypropylene resin used in this invention, pigments for coloring, antioxidants, polyethylene wax, fatty acid amide compounds and other lubricants, as well as heat stabilizers, may be added to the resin without impairing the effects of this invention.

[0053] Furthermore, according to a preferred embodiment of the spunbond nonwoven fabric of the present invention, the polypropylene resin further satisfies the following conditions (4) and (5).

[0054] (4) 2.50≤Mw / Mn≤3.20

[0055] (5) 1.82≤Mz / Mw≤2.20

[0056] The inventors of this application have discovered that the smaller the Mw / Mn and Mz / Mw ratios, the higher the molecular orientation (Δn) of the obtained fibers, even at the same spinning speed, and consequently, the higher the fiber strength. From this perspective, Mw / Mn ≤ 2.95 and Mz / Mw ≤ 1.98 are more preferred. On the other hand, by preferably setting them to 2.50 ≤ Mw / Mn and 1.82 ≤ Mz / Mw, the molecular orientation of the fibers is moderate and fiber breakage is suppressed, thereby producing a high-quality spunbond nonwoven fabric with fewer sheet defects.

[0057] The polypropylene resin used in this invention has a molecular weight (Mw) of 120,000 to 350,000 as determined by gel permeation chromatography (GPC). Mw is related to MFR (Mean Fiber Friction Rate). By setting Mw to 350,000 or less, the flowability and spinnability of the polypropylene resin are increased, thus reducing fiber breakage defects. From this perspective, a lower Mw is preferred, more preferably 250,000 or less, further preferably 210,000 or less, and particularly preferably 180,000 or less. On the other hand, by setting Mw to 120,000 or more, more preferably 130,000 or more, further preferably 150,000 or more, and particularly preferably 200,000 or more, fiber strength can be improved and sheet defects caused by fiber breakage can be suppressed.

[0058] It should be noted that, in this invention, Mw, Mn, and Mz refer to values ​​that are measured and calculated using the following methods.

[0059] (1) Five test pieces of 5 mg each were randomly collected from five points on the spunbond nonwoven fabric, excluding the ends. It should be noted that the ends of the spunbond nonwoven fabric refer to the 10% area at both ends relative to the width of the spunbond nonwoven fabric.

[0060] (2) For the test piece obtained in (1), add 5 mL of 1,2,4-trichlorobenzene (e.g., manufactured by Fujifilm and Kojun Pharmaceutical Co., Ltd.). Depending on the properties of the sample, the solution can be easily dissolved by heating at 165°C for 20 minutes. Next, filter the solution using a PTFE filter (pore size: 0.45 μm) to prepare a sample solution. Here, a PTFE filter such as Advantec Toyo Co., Ltd.'s "T010A" can be used.

[0061] (3) For the sample solution obtained in (2), GPC is used and the following conditions are met. Using, for example, “Empower” manufactured by Wyatt Technology, the discharge curve in GPC is analyzed, and Mw, Mn and Mz can be determined.

[0062] • Devices: For example, the "PL-220" manufactured by Polymer Laboratories, etc.

[0063] • Detector: Differential Refractive Index Detector (RI)

[0064] • Chromatographic column: Shodex HT-G (guard column) + Shodex HT-806M × 2 (8.0mm × 30cm, e.g., manufactured by Showa Denko Co., Ltd.)

[0065] Solvent: 1,2,4-Trichlorobenzene (with 0.1% BHT added)

[0066] • Flow rate: 1.0 mL / min

[0067] • Column temperature: 145℃

[0068] Injection volume: 0.20 mL

[0069] • Standard samples: monodisperse polystyrene (e.g., products manufactured by Tosoh Corporation), bibenzyl (e.g., products manufactured by Tokyo Chemical Industry Co., Ltd.).

[0070] [fiber]

[0071] The spunbond nonwoven fabric of the present invention is composed of fibers formed from the aforementioned polypropylene resin. Furthermore, the average single fiber diameter of these fibers is 5.0 μm or more and 20.0 μm or less. Regarding the range of average single fiber diameter, by setting its upper limit to 20.0 μm or less, preferably 16.0 μm or less, the surface of the spunbond nonwoven fabric becomes smooth to the touch. In addition, due to the fine fiber diameter, a lower quadratic moment of cross-section is exhibited, resulting in a spunbond nonwoven fabric with excellent softness. On the other hand, regarding the range of average single fiber diameter, by setting its lower limit to 5.0 μm or more, preferably 8.0 μm or more, a spunbond nonwoven fabric with high tensile strength and few defects is obtained.

[0072] It should be noted that the average single fiber diameter (μm) of the fibers in this invention refers to a value obtained by the following method: Ten 5mm × 5mm test pieces were randomly collected from the spunbond nonwoven fabric, excluding the ends. For the portions of each test piece other than the embossed bonding area, the side surfaces of the fibers constituting the spunbond nonwoven fabric were observed using a digital microscope (e.g., a "VHX-2000" manufactured by KEYENCE Co., Ltd.), and the fiber diameter was determined. The arithmetic mean (μm) of the fiber diameters measured from each test piece was rounded to the second decimal place. It should be noted that the ends of the spunbond nonwoven fabric refer to the area representing 10% of the length from both ends relative to the width direction of the spunbond nonwoven fabric.

[0073] Δn, which is an indicator of the molecular orientation of the fibers constituting the spunbond nonwoven fabric of the present invention, is preferably 0.020 or higher. By making Δn 0.020 or higher, not only is the fiber orientation improved, but the fiber strength and sheet strength are also improved. Furthermore, the heat resistance is also improved, thus enabling thermal bonding such as embossing at high temperatures. This makes thermal bonding of the fibers easier, resulting in a spunbond nonwoven fabric with good mechanical properties and easy processing such as pleating and joining with other components.

[0074] It should be noted that the Δn of the fibers constituting the spunbond nonwoven fabric of the present invention refers to the value obtained by means of the following method: 10 test pieces are randomly collected by means of the same method as the method for determining the average single fiber diameter, 10 monofilaments are extracted from the part of the test piece other than the embossed bonding part, and the retardation is calculated by means of the compensation method under the sample impregnation with flowing paraffin using a polarizing microscope (e.g., "BH2" manufactured by Olympus Corporation). The arithmetic mean (unitless) of the calculated value is rounded to the fourth decimal place.

[0075] The tensile strength of the fibers constituting the spunbond nonwoven fabric of the present invention is preferably 2.0 cN / dtex or higher. By making the tensile strength of the fibers 2.0 cN / dtex or higher, the strength of the sheet is improved, thus resulting in a spunbond nonwoven fabric with good mechanical properties and easy to perform advanced processing such as pleating and joining with other components.

[0076] It should be noted that the tensile strength of the fibers constituting the spunbond nonwoven fabric of the present invention refers to the value measured and calculated by the following methods.

[0077] (1) Ten test pieces were randomly collected using the same method as the method for determining the average single fiber diameter, and ten single filaments were extracted from the part of the test piece other than the embossed adhesive part.

[0078] (2) According to JIS L1015:2010 "Test Methods for Short Fibers of Chemical Fibers" "8.7 Tensile Strength and Elongation", the monofilaments were set with a clamping interval of 20 mm in a tensile testing machine (e.g., "UTM-III-100" manufactured by ORIENTEC Co., Ltd.) and a tensile test was performed at a tensile speed of 20 mm / min to determine the maximum point load (cN).

[0079] (3) Next, the maximum point load is divided by the arithmetic mean (cN / dtex) of the value obtained by the monofilament fineness (dtex) calculated by the following formula, and the second decimal place is rounded.

[0080] Single filament fineness (dtex) = π × (average single fiber diameter (μm) / 2) 2 ×0.91(g / cm 3 )×100000(cm).

[0081] The cross-sectional shape of the fibers constituting the spunbond nonwoven fabric of the present invention is not particularly limited as long as it does not impair the effects of the present invention. A circular cross-section is self-evident, but it can also be a triangular, elliptical, hexagonal, hollow, or other irregularly shaped cross-section. From the perspective of high productivity and excellent softness, a circular cross-section is preferred. That is, when the cross-sectional shape of the polypropylene fibers constituting the spunbond nonwoven fabric of the present invention is irregular, there is a bending direction with a larger second moment of cross-section for the same cross-sectional area than a circular cross-section. Therefore, it may become highly rigid when made into a spunbond nonwoven fabric. A circular cross-section does not have such a bending direction, and therefore has particularly excellent softness.

[0082] The fibers constituting the spunbond nonwoven fabric of the present invention are preferably composite fibers made by combining two or more resins. The composite fibers can be appropriately selected from core-sheath type, island type, side-by-side type, eccentric core-sheath type, etc. Among them, core-sheath type is preferred because of its excellent spinnability and the ability to bond the fibers together uniformly by thermal bonding. In particular, composite forms with concentric core-sheath types are preferred.

[0083] [Spunbond Nonwoven Fabric]

[0084] The spunbond nonwoven fabric of the present invention is a spunbond nonwoven fabric composed of fibers formed from the polypropylene resin. Thus, as described above, it becomes a spunbond nonwoven fabric that not only possesses softness but also excellent mechanical properties, is easy to wrinkle, and can be easily processed into higher-order materials such as joining with other components.

[0085] The spunbond nonwoven fabric of the present invention satisfies the following conditions (1) to (3).

[0086] (1) The amount of organic peroxide extracted by ultrasonic treatment of the spunbond nonwoven fabric impregnated in a chloroform / methanol solvent with a volume ratio of 1:1 at 15 minutes, 45 kHz and a solution temperature of 30 °C is more than 100 ppm and less than 1000 ppm.

[0087] (2) The melt flow rate is above 20g / 10min and below 400g / 10min;

[0088] (3) The degree of branching λ per molecule of the polypropylene resin, calculated using the molecular weight and radius of gyration determined by gel permeation chromatography / multi-angle light scattering analyzer and the trifunctional random branching theory, is 1.0 × 10⁻⁶. -7 Above 1.0×10 -3 the following.

[0089] By satisfying all of the conditions (1) to (3), a spunbond nonwoven fabric is produced that not only has softness but also excellent mechanical properties, is easy to wrinkle, and can be easily joined with other components for advanced processing. This will be explained in further detail.

[0090] First, regarding the polypropylene resin constituting the spunbond nonwoven fabric of the present invention, the amount of organic peroxide extracted by ultrasonically treating the spunbond nonwoven fabric impregnated in a chloroform / methanol solvent with a volume ratio of 1:1 for 15 minutes at 45 kHz is 100 ppm to 1000 ppm or less. Regarding the range of the amount of organic peroxide, by setting its lower limit to 100 ppm or more, preferably 200 ppm or more, and more preferably 300 ppm or more, it acts as a crystallization nucleating agent during the cooling and solidification process in spinning, thereby promoting the orientation crystallization of molecules. This improves the molecular orientation (Δn) and fiber strength of the fibers constituting the spunbond nonwoven fabric, resulting in a spunbond nonwoven fabric with excellent mechanical properties. On the other hand, by setting its upper limit to 1000 ppm or less, preferably 800 ppm or less, when used in applications involving direct contact with the human body, such as hygiene materials and protective clothing, the risk of skin problems such as inflammation caused by organic peroxides can be minimized.

[0091] It should be noted that, in this invention, the amount of organic peroxide refers to the value determined and calculated by the following methods.

[0092] (1) Five test pieces of 25 mg each were randomly collected from five points on the spunbond nonwoven fabric, excluding the ends. It should be noted that the ends of the nonwoven fabric refer to the 10% area at both ends relative to the width of the nonwoven fabric.

[0093] (2) The test piece obtained in (1) is immersed in a chloroform / methanol solvent with a volume ratio of 1:1 and subjected to ultrasonic treatment at 45 kHz for 15 minutes and a solution temperature of 30°C. For example, an ultrasonic cleaner such as the ASONE VS-100III manufactured by ASONE Corporation can be used for this ultrasonic treatment. Furthermore, the amount of solvent relative to the mass of the test piece is 0.8 mL relative to 1 mg of the test piece, and the solution is cooled with a refrigerant or similar agent to maintain the solution temperature at 30°C while extraction is performed.

[0094] (3) The ultrasonically treated solution obtained in (2) is filtered using a filter made of polytetrafluoroethylene (PTFE) (hereinafter, sometimes simply referred to as "PTFE filter". Pore size: 0.45 μm) to obtain a sample solution. Here, for example, the "T010A" manufactured by Advantec Toyo Co., Ltd. can be used as a PTFE filter.

[0095] (4) Dissolve 0.1 g of the organic peroxide in 10 mL of a chloroform / methanol solution with a volume ratio of 1:1 to prepare a standard stock solution (10 μg / mL). Then, dilute the standard stock solution with the chloroform / methanol solution to prepare standard solutions of various concentrations (0.1 μg / mL, 0.2 μg / mL, 0.5 μg / mL, 1.0 μg / mL). The following substances can be used as examples of the organic peroxide, and standard solutions of each concentration can be prepared for them. Furthermore, if an organic peroxide other than the following organic peroxides is clearly present or presumed to be present using other methods (e.g., iodine titration, polarography, etc.), a standard solution of that organic peroxide is also prepared.

[0096] · Peroxide methyl ethyl ketone

[0097] Methyl isobutyl ketone peroxide

[0098] ·benzoyl peroxide

[0099] • Di-(3,5,5-trimethylhexanoyl) peroxide

[0100] · Dilauryl peroxide

[0101] Didecyl peroxide

[0102] • Di-(2,4-dichlorobenzoyl) peroxide

[0103] ·tert-butyl hydroperoxide

[0104] ·Cumene peroxide

[0105] • Hydrogen peroxide diisopropylbenzene

[0106] ·2,5-Dimethylhexane-2,5-dihydroperoxide

[0107] • Di-tert-butyl peroxide, dicumyl peroxide

[0108] ·2,5-Dimethyl-2,5-bis(tert-butylperoxide)hexane

[0109] ·2,5-Dimethyl-2,5-bis(tert-butylperoxide)hexyn-3,α,α'-bis(tert-butylperoxide)diisopropylbenzene

[0110] ·1,1-bis(tert-butylperoxide)-3,3,5-trimethylcyclohexane

[0111] ·2,2-bis(tert-butylperoxide)butane

[0112] · tert-butyl peroxyoctanoate

[0113] ·tert-butyl peroxypentanoate

[0114] ·tert-butyl peroxyneodecanate

[0115] · tert-butyl peroxide

[0116] · Di(2-ethylhexyl) peroxide dicarbonate

[0117] Diisopropyl peroxide

[0118] · Bis(4-tert-butylcyclohexyl) peroxide dicarbonate

[0119] · Di-sec-butyl peroxide

[0120] · tert-butyl peroxide

[0121] (5) Using the sample solution, the solution is subjected to liquid chromatography-mass spectrometry (LC / MS / MS) analysis under the following conditions.

[0122] • High-performance liquid chromatography (HPLC): For example, "LC-20A" manufactured by Shimadzu Corporation, etc.

[0123] Mass spectrometers (MS), such as the Sciex API 4000, etc.

[0124] • Chromatographic column: ODS series chromatographic column (e.g., "SUMIPAX ODS A series" manufactured by Sumitomo Chemical Analysis Center Co., Ltd., etc.)

[0125] • Mobile phase: 0.1% formic acid aqueous solution + methanol (gradient extraction conditions)

[0126] Injection volume: 5μL

[0127] • Ionization: Electrospray ionization (ESI)

[0128] (6) The organic peroxides were identified by mass spectrometry (MS) of each sample solution, and the organic peroxides (ppm) were quantified by peak area using a standard curve obtained from the standard solution of the organic peroxide.

[0129] (7) Round the first decimal place of the arithmetic mean (ppm) of the values ​​obtained from the measurements of each test piece to obtain the amount of organic peroxide (ppm).

[0130] Furthermore, the amount of organic peroxide in the polypropylene resin constituting the spunbond nonwoven fabric of the present invention can be controlled by the addition form of the organic peroxide in the raw material resin and the addition temperature.

[0131] Examples of organic peroxides used in this invention include ketone peroxides such as "methyl ethyl ketone peroxide" and "methyl isobutyl ketone peroxide"; diacyl peroxides such as "benzoyl peroxide," "di-(3,5,5-trimethylhexanoyl peroxide," "dilauryl peroxide," "didecyl peroxide," and "di-(2,4-dichlorobenzoyl peroxide)"; hydroperoxides such as "tert-butyl hydroperoxide," "cumene hydroperoxide," "diisopropylbenzene hydroperoxide," and "2,5-dimethylhexane-2,5-dihydroperoxide"; and "di-tert-butyl peroxide," "diisopropylbenzene peroxide," "2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane," "2,5-dimethyl-2,5-bis(tert-butylperoxide)hexyne-3," "α,α'-," etc. Dialkyl peroxides such as "bis(tert-butylperoxide)diisopropylbenzene", peroxide ketals such as "1,1-bis(tert-butylperoxide)-3,3,5-trimethylcyclohexane" and "2,2-bis(tert-butylperoxide)butane", alkyl peresters such as "tert-butyl peroxyoctanoate", "tert-butyl peroxypentanoate", "tert-butyl peroxyneodecanate", and "tert-butyl peroxybenzoate", and peroxide carbonates such as "di(2-ethylhexyl) peroxydicarbonate", "diisopropyl peroxydicarbonate", "bis(4-tert-butylcyclohexyl) peroxydicarbonate", "disec-butyl peroxydicarbonate", and "tert-butyl peroxyisopropyl carbonate", are preferred, especially those dialkyl peroxides that allow for easy control of melt flow rate and Mw / Mn and Mz / Mw with small amounts added.

[0132] Secondly, the melt flow rate (hereinafter, sometimes simply referred to as MFR) of the spunbond nonwoven fabric of the present invention is 20 g / 10 min or more and 400 g / 10 min or less. Regarding the range of the MFR, by setting its lower limit to 20 g / 10 min or more, preferably 60 g / 10 min or more, and more preferably 100 g / 10 min or more, a spunbond nonwoven fabric with excellent softness is obtained. On the other hand, regarding the range of the MFR, by setting its upper limit to 400 g / 10 min or less, preferably 300 g / 10 min or less, the mechanical strength of the embossed portion of the spunbond nonwoven fabric is improved, resulting in a spunbond nonwoven fabric with high tensile strength.

[0133] It should be noted that the MFR of the spunbond nonwoven fabric in this invention is determined as follows: Following JIS K7210-1:2014 "Method for determining melt mass flow rate (MFR) and melt volumetric flow rate (MVR) of plastics—Part 1: Standard Test Methods," Chapter 8A: Mass Determination Method, five 20g test pieces are randomly collected from the spunbond nonwoven fabric, excluding the ends. For each test piece, the arithmetic mean of the values ​​(g / 10 min) obtained under a load of 2160g and a temperature of 230°C is rounded to the first decimal place to calculate the MFR (g / 10 min). It should be noted that the ends of the nonwoven fabric refer to the 10% area at both ends relative to the width direction of the nonwoven fabric. Furthermore, a melt index meter such as the "F-F01" manufactured by Toyo Seiki Co., Ltd. can be used for the measurement.

[0134] Furthermore, the melt flow rate (MFR) of spunbond nonwoven fabrics can be controlled by the weight-average molecular weight (MAM) of the polypropylene resin. A higher MLM of the polypropylene resin results in a lower melt flow rate. The MLM can be controlled by the MLM of the raw resin and the amount of organic peroxide added.

[0135] Furthermore, the spunbond nonwoven fabric of the present invention utilizes the molecular weight and radius of rotation determined by gel permeation chromatography / multi-angle light scattering (hereinafter, sometimes simply referred to as GPC-MALS), and calculates the degree of branching λ per molecule of polypropylene resin (hereinafter, sometimes simply referred to as the degree of branching λ per molecule) as 1.0 × 10⁻⁶ using the trifunctional random branching theory. -7 Above 1.0×10 -3 The following is a range for the degree of branching λ per molecule, with its lower limit set at 1.0 × 10⁻⁶. -7 The above, preferably 1.0×10 -6 The above, and more preferably 5.0×10 -6 Therefore, the polypropylene resin molecules have a more branched structure, resulting in a spunbond nonwoven fabric with higher fiber strength and excellent mechanical properties. On the other hand, regarding the aforementioned range, its upper limit is set to 1.0 × 10⁻⁶. -3 The following, preferably 1.0×10 -4 The following, and more preferably, is 5.0 × 10 -5 This allows for the suppression of filament breakage during spinning caused by excessive branching, resulting in high-quality spunbond nonwoven fabrics with fewer defects.

[0136] It should be noted that, in this invention, the degree of branching λ per molecule refers to the value determined and calculated by the following method.

[0137] (1) Five test pieces of 5 mg each were randomly collected from five points on the spunbond nonwoven fabric, excluding the ends. It should be noted that the ends of the nonwoven fabric refer to the 10% area at both ends relative to the width of the nonwoven fabric.

[0138] (2) For the test piece obtained in (1), add 5 mL of 1,2,4-trichlorobenzene (e.g., manufactured by Fujifilm and Kojun Pharmaceutical Co., Ltd.). If the sample is difficult to dissolve, the solution can be heated at 165°C for 20 minutes to dissolve it. Then, filter the solution using a PTFE filter (pore size: 0.45 μm, e.g., Advantec Toyo Co., Ltd. "T010A") to prepare the sample solution.

[0139] (3) For the sample solution obtained in (2), the determination was performed using GPC-MALS under the following conditions.

[0140] • Gel permeation chromatography (GPC): For example, "HLC-8321GPC / HT" manufactured by Tosoh Corporation, etc.

[0141] • Differential refractive index detector: For example, the "HL-8321GPC / HT" manufactured by Tosoh Corporation, etc.

[0142] • Multi-angle light scattering detectors (MALS): For example, the "DAWNNEON" manufactured by Wyatt Technology.

[0143] • Chromatographic columns: For example, the "Shodex HT-806M" manufactured by Showa Denko Co., Ltd.

[0144] • Solvent: 1,2,4-Trichlorobenzene (with 0.1% BHT added, for example, manufactured by Fujifilm and Kojun Pharmaceutical Co., Ltd.)

[0145] • Column temperature / detector temperature: 145℃ / 145℃

[0146] • Sample solution injection volume: 0.300 mL

[0147] • Data Processing Department: GPC: e.g., "Empower" manufactured by Wyatt Technology, etc.; MALS: e.g., "ASTRA 8.0.1.21" manufactured by Wyatt Technology, etc.

[0148] (4) For each sample solution, the molecular weight and radius of gyration at each dissolution time are calculated using the data processing software based on the obtained GPC-MALS curves. Regarding the relationship between molecular weight and radius of gyration, it is known that compared to linear polypropylene resins without branching structures (e.g., "NOVATEC" (registered trademark) PP FY6 manufactured by Nippon Polypropylene Co., Ltd.), polypropylene resins with branching structures have a smaller radius of gyration at the same molecular weight. In the trifunctional random branching theory, the radius of gyration S is related to the number of branching points λ at each molecular weight. M The following equation holds true between them.

[0149] [Mathematical Expression 1]

[0150]

[0151] (Where, g = (radius of rotation S of the sample)) 2 / (Radius of gyration S of linear polypropylene) 2 。 )

[0152] (5) Using the above formula, calculate the number of branching points λ for each sample. M Next, the number of branching points λ M The number of branching points per molecule is calculated by rounding the second decimal place of the value obtained by dividing by the corresponding absolute molecular weight (unitless).

[0153] (6) Among the branching points calculated in (5), the maximum value in the range of absolute molecular weights above 100,000 is taken as the degree of branching λ per molecule. It should be noted that the degree of branching λ per molecule is 1.0 × 10⁻⁶. -8 The following cases are below the detection limit and are therefore considered as 0.

[0154] Furthermore, the degree of branching λ per molecule can be controlled by the degree of branching λ per molecule of the raw material resin used. For example, the greater the degree of branching λ per molecule of the raw material resin, the greater the degree of branching λ of the polypropylene resin becomes.

[0155] Furthermore, the preferred unit area weight of the spunbond nonwoven fabric of the present invention is 3 g / m². 2 Above 50g / m 2 The following per unit area weight range is preferably set to a lower limit of 3 g / m². 2 The above, and more preferably 5g / m 2 The above results in a spunbond nonwoven fabric with sufficient strength, reduced breakage in subsequent processes, and excellent processability. Furthermore, regarding the range of weight per unit area, its upper limit is preferably 50 g / m². 2 Below, 30g / m 2This allows the spunbond nonwoven fabric to exhibit appropriate softness.

[0156] The unit area weight of the spunbond nonwoven fabric in this invention is obtained as follows: Following JIS L1913:2010 "General Nonwoven Fabrics Test Methods" "6.2 Mass per Unit Area (ISO Method)", three 20cm × 25cm test pieces are randomly collected from every 1m width of the spunbond nonwoven fabric, excluding the ends. The mass (g) of each piece under standard conditions is weighed, and their arithmetic mean (g) is calculated and converted to a mass per 1m. 2 mass (g / m 2 Round the first decimal place. It should be noted that the ends of the nonwoven fabric refer to the 10% area at both ends relative to the length of the nonwoven fabric in the width direction.

[0157] The spunbond nonwoven fabric of the present invention preferably has a tensile strength of 0.30 (N / 25mm) / (g / m²) per unit area weight. 2 ) above 5.00 (N / 25mm) / (g / m 2 Below that. Regarding the range of tensile strength per unit area weight, the lower limit is preferably 0.3 (N / 25mm) / (g / m²). 2 ) or more, preferably 0.50 (N / 25mm) / (g / m 2 ) or higher, and more preferably 0.70 (N / 25mm) / (g / m 2 The range is above 5.00 (N / 25mm) / (g / m³), which allows it to withstand the process flow during the manufacture of diapers and other similar products, and to be used as a product. Regarding the range, the upper limit is preferably 5.00 (N / 25mm) / (g / m³). 2 Therefore, it also has softness.

[0158] It should be noted that, in this invention, the tensile strength per unit area weight of spunbond nonwoven fabric refers to the value obtained by measuring according to the following steps in "6.3 Tensile strength and elongation (ISO method)" of JIS L1913:2010 "General nonwoven fabrics test methods".

[0159] (1) Three 25mm × 30mm test pieces were randomly collected from the spunbond nonwoven fabric in both the length and width directions, excluding the ends. It should be noted that the ends of the nonwoven fabric refer to the 10% area at both ends relative to the length in the width direction of the nonwoven fabric.

[0160] (2) Place the test piece on the tensile testing machine with a clamping interval of 20 mm.

[0161] (3) Perform a tensile test at a tensile speed of 20 mm / min, measure the maximum point load (N / 25 mm), and calculate the arithmetic mean (N / 25 mm) of all the maximum point loads in the length and width directions measured by each test piece.

[0162] (4) Based on the unit area weight (g / m²) determined by the above method 2 The arithmetic mean of the maximum point load (N / 25mm) is used to calculate the tensile strength per unit area weight according to the following formula, rounding the third decimal place.

[0163] Tensile strength per unit area weight (N / 25mm) / (g / m²) 2 = Arithmetic mean of maximum point load (N / 25mm) / Weight per unit area (g / m²) 2 ).

[0164] The stiffness of the spunbond nonwoven fabric of the present invention is preferably 0.5 mN·cm or more and 3.0 mN·cm or less. Stiffness is an indicator of softness, and high softness can be obtained by having a stiffness of 3.0 mN·cm or less. The lower the stiffness, the better the softness; therefore, a stiffness of 2.0 mN·cm or less is more preferred. On the other hand, if the stiffness is too low, it is easily caught by rollers, making it difficult to perform advanced processing such as pleating and joining with other parts; therefore, a stiffness of 0.5 mN·cm or more is preferred, and 1.0 mN·cm or more is more preferred.

[0165] It should be noted that the stiffness of the spunbond nonwoven fabric of the present invention refers to the value obtained by measuring the stiffness according to the "6.7.3 41.5° cantilever method" of JIS L1913:2010 "General Nonwoven Fabrics Test Method" through the following steps.

[0166] (1) Three 25mm × 250mm test pieces were randomly collected from the spunbond nonwoven fabric in both the length and width directions, excluding the ends. It should be noted that the ends of the nonwoven fabric refer to the 10% area at both ends relative to the length in the width direction of the nonwoven fabric.

[0167] (2) Set the test piece on a 41.5° cantilever testing machine and slowly push the steel ruler and the test piece together along the inclined plane at a constant speed.

[0168] (3) Move the steel ruler until the test piece contacts the inclined plane, and read the protruding length of the test piece from the steel ruler in 1 mm. For one test piece, perform 4 measurements on the inside and outside and at both ends, and take half of their arithmetic mean as the bending length (cm).

[0169] (4) Then, for the length direction and the width direction, calculate the arithmetic mean (cm) of the bending length of all test pieces, and round the second decimal place to get the total average bending length (cm).

[0170] (5) Based on the unit area weight (g / m²) obtained by the above method 2 The stiffness (mN·cm) is calculated from the total average bending length (cm) using the following formula, rounding to the second decimal place.

[0171] • Stiffness (mN·cm) = Weight per unit area (g / m²) 2 ) × [Total average bending length (cm)] 3 ×10 -3 .

[0172] [Manufacturing method of spunbond nonwoven fabric]

[0173] The method for manufacturing spunbond nonwoven fabric of the present invention comprises: a step of adding an organic peroxide to a raw material resin, decomposing the raw material resin to obtain a polypropylene resin prepared in a manner satisfying the following conditions (1) to (3); a step of spinning the polypropylene resin to obtain fibers with an average single fiber diameter of 5.0 μm or more and 20.0 μm or less; and a step of collecting the fibers.

[0174] (1) The residual amount of organic peroxide extracted by ultrasonic treatment of the spunbond nonwoven fabric impregnated in a chloroform / methanol solvent with a volume ratio of 1:1 for 15 minutes and 45 kHz is more than 100 ppm and less than 1000 ppm.

[0175] (2) The melt flow rate of the polypropylene resin is more than 20g / 10min and less than 400g / 10min;

[0176] (3) The degree of branching λ per molecule of the polypropylene resin, calculated using the molecular weight and radius of gyration determined by gel permeation chromatography / multi-angle light scattering analyzer and the trifunctional random branching theory, is 1.0 × 10⁻⁶. -7 Above 1.0×10 -3 the following.

[0177] Specific examples will be provided to illustrate this.

[0178] (a) Process for obtaining polypropylene resin

[0179] In the method for manufacturing the spunbond nonwoven fabric of the present invention, firstly, an organic peroxide is added to a raw material resin to decompose the raw material resin. The raw material resin used here refers to a resin in which the molar fraction of propylene units in the repeating units is 80 mol% to 100 mol%. Therefore, specific examples of the raw material resin include homopolymers of propylene, or copolymers of propylene with various α-olefins. When using copolymers of propylene with various α-olefins as the raw material resin, in order to improve the tensile strength of the spunbond nonwoven fabric, the copolymerization ratio of various α-olefins is preferably 10 mol% or less, more preferably 5 mol% or less, and even more preferably 3 mol% or less.

[0180] Alternatively, using recycled resin as the raw material is also a preferred embodiment. In this invention, recycled resin refers to resin formed from process waste generated during product manufacturing or from used finished products, comprising 10% or more by mass. Examples of process waste generated during product manufacturing include end materials of films, fabric scraps, and offcuts of nonwoven fabrics. In this technology, the raw material resin is decomposed in a manner that meets specific conditions. As the raw material resin, resins with a wide range of MFRs can be used, making recycled resin suitable. As a result, the amount of raw petrochemical raw materials used can be reduced, and the environmental impact during the manufacture of spunbond nonwoven fabrics can be lowered.

[0181] In the raw material resin used in this invention, pigments for coloring, antioxidants, polyethylene wax, fatty acid amide compounds and other lubricants, as well as heat stabilizers, may be added to the resin without impairing the effect of this invention.

[0182] Examples of organic peroxides used in the manufacturing method of spunbond nonwoven fabric of the present invention include those described in [Spunbond Nonwoven Fabric].

[0183] As described above, the polypropylene resin obtained by adding the organic peroxide to the raw material resin and decomposing the raw material resin to satisfy the conditions (1) to (3) can also be directly supplied to the spinning process described later without special drying. It should be noted that before the organic peroxide is supplied to the spinning process described later, it can be compounded and granulated by an extruder to produce the polypropylene resin, or the organic peroxide and polypropylene resin can be compounded by using an extruder used in spinning, and the polypropylene resin can be obtained by melt spinning.

[0184] Here, regarding the method for adjusting the MFR of polypropylene resins, increasing the amount of organic peroxide added can improve the MFR of the obtained polypropylene resin. Furthermore, if the amount added is constant, the higher the MFR of the raw material resin, the higher the MFR of the obtained polypropylene resin will be. Regarding the determination of the MFR of the raw material resin, similar to the method for determining the MFR of spunbond nonwoven fabrics, five samples of raw material resin, each weighing 20g, are prepared according to Chapter 8A of JIS K 7210-1:2014 "Methods for determining melt mass flow rate (MFR) and melt volumetric flow rate (MVR) of plastics—Thermoplastics—Part 1: Standard Test Methods": Method for determining mass flow rate (MFR). For each sample, the MFR (g / 10min) is calculated by rounding the arithmetic mean of the values ​​(g / 10min) obtained under a load of 2160g and a temperature of 230°C to the first decimal place. In addition, for the measurement, a melt index meter such as the "F-F01" manufactured by Toyo Seiki Co., Ltd. can be used.

[0185] Furthermore, from the viewpoint of obtaining spunbond nonwoven fabrics with high tensile strength, a higher degree of branching λ per molecule of the raw material resin, calculated using the molecular weight and radius of rotation determined by gel permeation chromatography / multi-angle light scattering and the trifunctional random branching theory, is preferred; preferably, it is 1.0 × 10⁻⁶. -7 That's all. On the other hand, by making the degree of branching λ per molecule of the raw material resin preferably 1.0 × 10⁻⁶ -3 Therefore, it is possible to suppress filament breakage during spinning caused by the increased elongation viscosity of the obtained polypropylene resin.

[0186] It should be noted that the degree of branching λ per molecule of the raw material resin can be measured and calculated using the same method as the degree of branching λ per molecule of the polypropylene resin.

[0187] Furthermore, other component resins may be mixed into the raw material resins used in this invention, without impairing the effects of the invention. Besides polyolefin resins such as polyethylene and poly-4-methyl-1-pentene, which have melting points close to polypropylene, other component resins include low-melting-point polyester resins and low-melting-point polyamide resins. From the viewpoint of imparting softness, low-crystallinity olefin resins are preferred. For example, ethylene-propylene copolymers are preferred as low-crystallinity olefin resins. In this case, in order not to impair the properties of the polypropylene resin, especially the heat resistance of the spunbond nonwoven fabric, the mass ratio of other component resins is preferably 20% by mass or less, more preferably 10% by mass or less.

[0188] Moreover, the amount of residual organic peroxides in polypropylene resins can be controlled by the temperature at which organic peroxides are added to the raw material resin and by the form of the peroxides.

[0189] Firstly, when organic peroxides are added to the raw material resin in the extruder, increasing the extrusion temperature reduces the amount of residual organic peroxides. Conversely, decreasing the extrusion temperature increases the amount of residual organic peroxides. Given the melting point of the polypropylene resin used as the raw material, the extrusion temperature is preferably 180°C or higher, more preferably 200°C or higher. Furthermore, to prevent the risk of yellowing and fire caused by the oxidative decomposition of the polypropylene resin, the extrusion temperature is preferably 280°C or lower, more preferably 260°C or lower.

[0190] As a form of organic peroxide, adding organic peroxide to the masterbatch of polypropylene resin inhibits self-decomposition in the extruder under certain addition amounts and extrusion temperatures, thus allowing more organic peroxide to remain in the polypropylene resin.

[0191] (b) Processes for obtaining fibers

[0192] In this process, the polypropylene resin is spun out to obtain fibers with an average single fiber diameter of 5.0 μm to 20.0 μm.

[0193] In this spinning process, melt spinning methods using extruders such as single-screw or twin-screw extruders can be applied. Furthermore, the polypropylene resin extruded from the extruder is piped, metered by a gear pump or similar device, passes through a filter to remove impurities, and is then guided to the spinning spinneret. To improve flowability, the temperature from the resin piping to the spinning spinneret (spinning temperature) is preferably 180°C to 280°C.

[0194] For the spinning spinneret used for spinning, it is preferable to set the diameter D of the spinneret orifice to be 0.1 mm or more and 1.0 mm or less. In addition, it is preferable that the ratio L / D, defined as the quotient of the forming section length (land length) L (the length of the straight tube section with the same diameter as the spinneret orifice) divided by the diameter D, is 1 or more and 10 or less.

[0195] The yarn ejected from the spinneret can be cooled and solidified by blowing air. From the viewpoint of cooling efficiency, the temperature of the cooling air in this case can be determined by balancing with the cooling air velocity, and from the viewpoint of fineness uniformity, it is preferably 0°C to 20°C. By preferably keeping the temperature of the cooling air above 0°C, more preferably above 2°C, condensation and freezing of the air piping and cooling air outlet can be prevented, and a stable supply of cooling air can be achieved. In addition, by preferably keeping the temperature of the cooling air below 20°C, more preferably below 16°C, and even more preferably below 12°C, the cooling effect of the fibers is improved and the uniformity is increased, resulting in a spunbond nonwoven fabric with fewer broken yarn defects.

[0196] Cooling gas is used to cool the yarn by flowing in a direction approximately perpendicular to the yarn (parallel to the ground when the fibers are moving up and down). The speed of the cooling air is preferably between 10 m / min and 100 m / min. By preferably setting the cooling air speed to 10 m / min or higher, the cooling effect is improved, uniformity is increased, and a spunbond nonwoven fabric with fewer yarn breakage defects is produced. Furthermore, by preferably setting the cooling air speed to 100 m / min or lower, yarn wobbling caused by the cooling air can be suppressed, thus reducing yarn breakage during spinning.

[0197] The distance from the spinneret orifice to the point where cooling begins is preferably 20 mm to 800 mm. By preferably setting the lower limit of this distance to 20 mm or more, the surface temperature of the spinneret is prevented from dropping excessively, resulting in stable spinning and reduced filament breakage during spinning. Furthermore, by preferably setting the upper limit of this distance to 800 mm or less, the cooling effect is improved, uniformity is increased, and a spunbond nonwoven fabric with fewer filament breakage defects is produced.

[0198] Regarding the yarn ejected from the spinneret, regardless of whether cooling air is blown, air traction (through accelerated airflow) is preferably performed at a distance of 400 mm to 700 mm from the spinneret. Regarding the accelerated airflow, the airflow velocity can be increased by sealing the area where cooling air is blown and gradually decreasing the cross-sectional area of ​​the sealed area towards the downstream of the spinning thread; however, using an ejector is a preferred embodiment to obtain a higher airflow velocity. The yarn is accelerated by this airflow velocity, and the spinning speed, which is the fiber's travel speed, also reaches a speed close to the airflow velocity. It should be noted that in this invention, the gas used for air traction is not limited to ordinary air; nitrogen can also be used, and if the humidity is below 100% RH, water vapor can also be used.

[0199] To achieve a smaller average single fiber diameter, the spinning speed is preferably 3 km / min or higher, more preferably 4 km / min. Similarly, the airflow velocity is also preferably 3 km / min or higher. Furthermore, the upper limit of the spinning speed is approximately 12 km / min.

[0200] Spinning speed is the value calculated using the following formula.

[0201] Spinning speed (km / min) = Q·1000 / ((W / 2)) 2 ×π×ρ)

[0202] (In the formula, Q represents the single-hole ejection rate (g / min), W represents the average single fiber diameter (μm), and ρ represents the density (g / cm³). 3 Regarding the polypropylene resin used in this invention, the density value is 0.91. Furthermore, the average single fiber diameter is a value obtained by measuring and calculating using the method described above in [Fibers].

[0203] This results in fibers with an average single fiber diameter of 5.0 μm to 20.0 μm.

[0204] (c) The process of capturing fibers

[0205] The air-drawn yarn (fiber) can be captured by the following method: it is opened by passing through an opening section that reduces the surrounding airflow velocity, and then falls onto a mesh conveyor that draws air from the back, and is captured in the form of a fiber web.

[0206] (d) Post-processing steps

[0207] The captured fiber web can then be used directly as spunbond nonwoven fabric, but it is more preferable to obtain spunbond nonwoven fabric by conveying it at a speed of 10 m / min to 1000 m / min and performing thermal bonding processing on the fiber web. As a method for integrating the fibers constituting the above-mentioned fiber web by thermal bonding, the following methods can be cited: a pair of thermal embossing rollers on which the upper and lower roller surfaces are respectively engraved (convex and concave); a thermal embossing roller consisting of a combination of a roller with one roller surface being flat (smooth) and a roller with the other roller surface being engraved (convex and concave); and a thermal calendering roller consisting of a pair of flat (smooth) rollers on which the upper and lower roller surfaces are engraved (convex and concave); and so on.

[0208] The embossed bonding area ratio during thermal bonding is preferably 5% to 30%. By preferably having a bonding area ratio of 5% or more, the spunbond nonwoven fabric exhibits high tensile strength practically usable for use, and is easy to perform advanced processing such as pleating and joining with other components. On the other hand, by preferably having a bonding area ratio of 30% or less, sufficient softness can be obtained, especially in the case of spunbond nonwoven fabrics used as sanitary materials.

[0209] In this invention, the so-called bonding area, when thermally bonded using a pair of rollers with concave and convex surfaces, refers to the proportion of the portion in the nonwoven fabric in which the convex portions of the upper and lower rollers overlap and abut against the fiber web. Furthermore, when thermally bonded using a roller with concave and convex surfaces and a flat roller, it refers to the proportion of the portion in the nonwoven fabric in which the convex portions of the rollers abut against the fiber web.

[0210] The shapes that can be engraved on the hot embossing roller include circles, ovals, squares, rectangles, parallelograms, rhombuses, regular hexagons, and regular octagons.

[0211] In the manufacture of the spunbond nonwoven fabric of this invention, a key technological aspect is the ability to achieve a finer average single fiber diameter and stable production through high-speed spinning. While the mechanism is not yet fully understood, the spunbond nonwoven fabric of this invention uses a polypropylene resin with a high MFR as a raw material. Therefore, the deformation following property of the polypropylene resin during the refining process in the spinning step is improved, resulting in a significant reduction in fiber breakage defects.

[0212] On the other hand, considering only the above points, the obtained spunbond nonwoven fabric has problems such as low tensile strength, difficulty in pleating, and difficulty in joining with other components due to its high MFR. Therefore, another important aspect of the manufacturing process of the spunbond nonwoven fabric of the present invention is that the crystal nucleating agent effect brought about by the organic peroxide and the effect of inhibiting orientation relaxation by the branched structure can improve Δn, which is an indicator of the molecular orientation of the fiber, and thus improve the strength of the fiber.

[0213] The resulting spunbond nonwoven fabric not only possesses excellent softness but also sufficient tensile strength for use in spunbond nonwoven fabric applications, and is easy to process into pleats and join with other components, among other advanced processing methods.

[0214] [Layered nonwoven fabric]

[0215] The laminated nonwoven fabric of the present invention includes the spunbond nonwoven fabric. While the spunbond nonwoven fabric of the present invention exhibits excellent tensile strength on its own, it displays even better mechanical properties when laminated with a heat-bonding nonwoven fabric. Examples of heat-bonding nonwoven fabrics include meltblown nonwoven fabrics with low softening temperatures and excellent heat-bonding properties, and spunbond nonwoven fabrics formed from low-melting-point polypropylene resins polymerized using metallocene catalysts. Furthermore, as the laminated structure of the laminated nonwoven fabric, the spunbond nonwoven fabric is designated as S and the meltblown nonwoven fabric as M; examples include S / M, S / S, S / M / M, M / S / M, S / S / M, S / M / S, S / M / M / S, S / M / M / S, S / M / M / M / S, and S / M / M / M / S. In addition, as a preferred manufacturing method for the laminated nonwoven fabric, an example is to stack the nonwoven fabric layers ejected from multiple spinning spinnerets on a conveyor and use embossing rollers or the like to bond the resulting laminated web portions together.

[0216] [Sanitary supplies, clothing]

[0217] The sanitary materials and clothing of the present invention are made of at least a portion thereof comprising spunbond nonwoven fabric or said laminated nonwoven fabric. The spunbond nonwoven fabric and the laminated nonwoven fabric, due to their softness, excellent skin feel, uniform texture, and sufficient tensile strength for practical use, can thus provide sanitary materials and clothing with excellent wearing comfort.

[0218] It should be noted that the hygiene materials and clothing mentioned here mainly refer to disposable items used for medical, nursing, and other health-related purposes.

[0219] Examples of sanitary materials according to the present invention include diapers, sanitary napkins, gauze, bandages, masks, gloves, and adhesive bandages. Regarding their constituent components, for example, in a diaper, they also include a top sheet, a bottom sheet, and side pleats. The bottom sheet is particularly suitable for use in diapers requiring high tensile strength and softness.

[0220] Examples of clothing made according to the present invention include protective suits, examination gowns, surgical gowns, work clothes or dustproof suits used in medical settings, etc. Regarding their constituent components, for example, in protective suits, they also include an inner layer that comes into direct contact with the skin, a middle layer that requires a barrier function, and an outer layer. The inner layer is particularly suitable for protective suits requiring high tensile strength and flexibility.

[0221] Example

[0222] The spunbond nonwoven fabric of the present invention will be described in more detail below through examples.

[0223] [Measurement and Evaluation Methods]

[0224] The characteristic values ​​in the embodiments were obtained using the following methods. It should be noted that, unless otherwise specified, the measurement methods described above were used.

[0225] A. MFR of raw material resin and spunbond nonwoven fabric:

[0226] Regarding the MFR of spunbond nonwoven fabric, it was measured according to the above method using the melt index tester "F-F01" manufactured by Toyo Seiki Co., Ltd.

[0227] B. Quantitative analysis of organic peroxides in raw resins and spunbond nonwoven fabrics:

[0228] Regarding the amount of organic peroxides in spunbond nonwoven fabrics, the high-performance liquid chromatography (HPLC) was performed using the "LC-20A" manufactured by Shimadzu Corporation, the mass spectrometer (MS) was the "API4000" manufactured by Sciex, and the chromatographic column was the "SUMIPAX ODS A series" manufactured by Sumitomo Chemical Analysis Center Co., Ltd.

[0229] The detection limit in the above determination is 5 ppm, therefore, in the absence of detectable organic peroxides, it is recorded as <5 [ppm] in the table.

[0230] C. Branching degree λ of raw material resin and spunbond nonwoven fabric:

[0231] Regarding the branching degree λ of spunbond nonwoven fabric, a gel permeation chromatography (GPC) instrument manufactured by Tosoh Corporation was used, a differential refractive index detector manufactured by Tosoh Corporation was used, a multi-angle light scattering detector (MALS) manufactured by Wyatt Technology was used, and a chromatographic column manufactured by Showa Denko Corporation was used. The data analysis of the ejection curve was performed using an Empower instrument manufactured by Wyatt Technology and an ASTRA 8.0.1.21 instrument manufactured by Wyatt Technology. 'NOVATEC' (registered trademark) PP FY6 manufactured by Nippon Polypropylene Co., Ltd. was used as a linear polypropylene resin without branching structure. The results were determined and calculated using the above methods.

[0232] D. Mn, Mw, and Mz of raw material resins and spunbond nonwoven fabrics:

[0233] For the Mn, Mw, and Mz of polypropylene resins, Advantec Toyo Co., Ltd.'s "T010A" PTFE filter was used, Polymer Laboratories' "PL-220" was used as the apparatus, and Shodex HT-G (guard column) + two Shodex HT-806M (8.0mm × 30cm, manufactured by Showa Denko Co., Ltd.) columns were used as chromatographic columns. Monodisperse polystyrene manufactured by Tosoh Co., Ltd. and bibenzyl ether manufactured by Tokyo Chemical Industry Co., Ltd. were used as standard samples. The determination was carried out using the above method, and the data analysis of the ejection curves was performed using Wyatt Technology's "Empower".

[0234] E. Average single fiber diameter and spinning speed:

[0235] In determining the average single fiber diameter, a "VHX-2000" manufactured by KEYENCE Co., Ltd. was used. Furthermore, the spinning speed (km / min) was calculated from the obtained average single fiber diameter using the above formula.

[0236] F. Molecular orientation of the fiber Δn:

[0237] Regarding the molecular orientation Δn of the fiber, the above method was used to determine it using a polarizing microscope manufactured by Olympus Corporation, "BH2".

[0238] G. Tensile strength of the fiber:

[0239] Regarding the tensile strength (cN / dtex) of the fiber, the tensile tester was a "UTM-III-100" manufactured by ORIENTEC Co., Ltd., and the test was performed using the method described above.

[0240] H. Weight per unit area of ​​spunbond nonwoven fabric:

[0241] The weight per unit area of ​​spunbond nonwoven fabric was measured and calculated using the method described above.

[0242] I. Tensile strength per unit area weight of spunbond nonwoven fabric:

[0243] In the determination of the tensile strength per unit area weight of spunbond nonwoven fabric, the "UTM-III-100" manufactured by ORIENTEC Co., Ltd. was used as a tensile testing machine, and the tensile strength was determined and calculated using the method described above.

[0244] J. Stiffness of spunbond nonwoven fabric:

[0245] The stiffness of spunbond nonwoven fabric was measured using the method described above.

[0246] K. Number of defects in spunbond nonwoven fabric:

[0247] Visually inspect a 10cm square area excluding the ends of the spunbond nonwoven fabric using a magnifying glass. Defects are identified as areas where the fiber diameter is more than twice the average fiber diameter due to broken fibers, and areas where the fiber edges are rounded and appear more than twice the average fiber diameter. Count these defects. Repeat this observation five times along the length (MD) of the nonwoven fabric, and record the total number of defects as the total number of defects in the spunbond nonwoven fabric. Note that the ends of the nonwoven fabric refer to the 10% area at both ends relative to the width direction of the nonwoven fabric.

[0248] L. The high processability of spunbond nonwoven fabrics:

[0249] To assess the ease of advanced processing such as pleating and joining with other components, a sheet-like test piece of spunbond nonwoven fabric (100 mm wide, 300 m long, excluding the ends) was prepared and passed between a pair of silicone rubber (hardness 12°) rollers (rubber outer diameter: 15 cm, surface roughness Ra: 6.3 μm) at a linear pressure of 300 N / cm for 10 minutes. The adhesion of fibers to the rollers and the state of the spunbond nonwoven fabric were observed, and scores were assigned as processability (points) based on the following criteria. A score of 4 or higher was considered excellent processability. It should be noted that the ends of the nonwoven fabric refer to the 10% area at both ends relative to the width direction of the nonwoven fabric.

[0250] ·5 points: There are no fibers attached to the roller, and no lint or tears are visible on the nonwoven fabric.

[0251] ·4 points: There are fibers attached to the roller, but no nonwoven fabric fuzz or cracks are visible.

[0252] ·3 points: There are fibers attached to the roller and some non-woven fabric fluff, but no cracks are visible.

[0253] ·2 points: There are fibers attached to the roller, as well as non-woven fabric lint, and there are tears.

[0254] ·1 point: Due to the sheet tearing, the nonwoven fabric is wrapped around the roller.

[0255] M. Effects of spunbond nonwoven fabrics on the skin:

[0256] 10 cm square test pieces collected from the spunbond nonwoven fabric (excluding the ends) and "LabCyte EPI-MODEL 24well 6-day culture" (intended as a human epidermal model for sensitive skin) manufactured by Japan Tissue Engineering Co., Ltd. were cultured together in a culture medium at 37°C for 24 hours. After culture, based on ISO 10993-5:2009 "Biological evaluation of medical devices" Annex C, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide thiazolyl blue (MTT) reagent was added for pigment detection, and the absorbance at OD570 was measured. Cell viability (%) was calculated from this, and evaluated using the following criteria (0, Δ, ×).

[0257] • 0: Cell survival rate is over 99%.

[0258] • △: Cell viability is above 95% but less than 99%

[0259] ×: Cell viability is less than 95%

[0260] It should be noted that the ends of nonwoven fabric refer to the 10% area at both ends relative to the length of the nonwoven fabric in the width direction.

[0261] [Raw material resin, polypropylene masterbatch, organic peroxide]

[0262] The raw material resins, polypropylene masterbatches, and organic peroxides used in the examples and comparative examples are shown below.

[0263] (Raw material resin A)

[0264] Polypropylene, a homopolymer of propylene obtained using a Ziegler-Natta catalyst, has an MFR of 6 g / 10 min, a Mw of 458,000, an Mw / Mn ratio of 5.31, an Mz / Mw ratio of 2.79, and a degree of branching λ of 1.0 × 10⁻⁶. -6 .

[0265] (Raw material resin B)

[0266] Polypropylene, a homopolymer of propylene obtained using a Ziegler-Natta catalyst, has an MFR of 0.3 g / 10 min, Mw of 1,319,362, Mw / Mn of 6.31, Mz / Mw of 3.06, and a degree of branching λ of 1.0 × 10⁻⁶. -6 .

[0267] (Raw material resin C)

[0268] Polypropylene, a homopolymer of propylene obtained using a Ziegler-Natta catalyst, has an MFR of 0.05 g / 10 min, Mw of 2483427, Mw / Mn of 7.55, Mz / Mw of 4.79, and a degree of branching λ of 1.0 × 10⁻⁶. -6 .

[0269] (Raw material resin D)

[0270] Polypropylene, a homopolymer of propylene obtained using a Ziegler-Natta catalyst, has an MFR of 10 g / 10 min, Mw of 382638, Mw / Mn of 4.90, Mz / Mw of 2.54, and a degree of branching λ of 1.0 × 10⁻⁶. -6 .

[0271] (Raw material resin E)

[0272] Polypropylene, a homopolymer of propylene obtained using a Ziegler-Natta catalyst, has an MFR of 15 g / 10 min, Mw of 331610, Mw / Mn of 4.55, Mz / Mw of 2.45, and a degree of branching λ of 1.0 × 10⁻⁶. -6 .

[0273] (Raw material resin F)

[0274] Polypropylene, a homopolymer of propylene obtained using a Ziegler-Natta catalyst, has an MFR of 0.01 g / 10 min, Mw of 4383165, Mw / Mn ratio of 7.98, Mz / Mw ratio of 5.11, and a branching degree λ of 1.0 × 10⁻⁶. -6 .

[0275] (Raw material resin G)

[0276] Polypropylene, a homopolymer of propylene obtained using a Ziegler-Natta catalyst, has an MFR of 0.3 g / 10 min, Mw of 1,319,362, Mw / Mn of 6.31, Mz / Mw of 3.06, and a degree of branching λ of 1.0 × 10⁻⁶. -5 .

[0277] (Raw material resin H)

[0278] Polypropylene, a homopolymer of propylene obtained using a Ziegler-Natta catalyst, has an MFR of 0.3 g / 10 min, Mw of 1,319,362, Mw / Mn of 6.31, Mz / Mw of 3.06, and a degree of branching λ of 1.0 × 10⁻⁶. -7 .

[0279] (Raw material resin I)

[0280] Polypropylene, a homopolymer of propylene obtained using a Ziegler-Natta catalyst, has an MFR of 60 g / 10 min, Mw of 204987, Mw / Mn ratio of 7.98, Mz / Mw ratio of 5.11, a melting point of 160 °C, and a degree of branching λ of 1.0 × 10⁻⁶. -6 .

[0281] (Raw material resin J)

[0282] Polypropylene, which is a homopolymer of propylene obtained using Ziegler-Natta catalyst, has an MFR of 230 g / 10 min, Mw of 151000, Mw / Mn of 5.31, Mz / Mw of 2.70, and a degree of branching λ of 0.

[0283] (Raw material resin K)

[0284] Polypropylene, which is a homopolymer of propylene obtained using Ziegler-Natta catalyst, has an MFR of 3.3 g / 10 min, Mw of 575,000, Mw / Mn of 6.69, Mz / Mw of 3.20, and a degree of branching λ of 0.

[0285] (Polypropylene masterbatch α)

[0286] "VMPP10X" (polypropylene masterbatch: containing 10% by mass of 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane) manufactured by Polytechs.

[0287] (organic peroxide β)

[0288] "PERHEXA 25B" (organic peroxide: 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane) manufactured by Nichiyu Corporation.

[0289] [Example 1]

[0290] (a) Process for obtaining polypropylene resin

[0291] For 100 parts by weight of raw material resin A, 2.5 parts by weight of polypropylene masterbatch α were blended with the scrap. Then, the blended scrap was melt-extruded at 230°C using a single-screw extruder, with the molten resin being metered and fed to the spinning spinneret simultaneously using a gear pump. The obtained polypropylene resin had an MFR of 200 g / 10 min, Mw of 132899, Mw / Mn of 2.95, Mz / Mw of 1.85, and a branching degree λ of 1.0 × 10⁻⁶. -6 .

[0292] (b) Processes for obtaining fibers

[0293] Next, the spinning temperature (spinneret temperature) was set to 230°C, and polypropylene resin was ejected from a spinneret with a diameter D of 0.30 mm and a forming section length L of 0.75 mm at a single-hole ejection rate of 0.4 g / min. The following spinning spinneret was used, wherein the inlet hole directly above the spinneret is a straight hole, and the connection between the inlet hole and the spinneret is tapered.

[0294] In addition, the ejected fibrous resin is cooled and cured by blowing cooling air at a temperature of 12°C and a speed of 30 m / min from the outside. Then, fibers are obtained by drawing the resin with air using a rectangular ejector at a spinning speed of 4.0 km / min. At this time, the distance from the spinneret orifice of the spinning spinneret to the ejector inlet, which is the starting point of the cooling process, is set to 550 mm.

[0295] (c) The process of capturing fibers

[0296] Next, the fibers obtained above are opened by passing them through an opening section where the surrounding airflow velocity is reduced. Then, they are collected by falling onto a mesh conveyor from the back for air extraction, resulting in a fiber web. The fiber web is then conveyed at a speed of 11 m / min.

[0297] (d) Post-processing steps

[0298] Next, the fiber web obtained as described above is thermally bonded at 130°C using a pair of hot embossing rollers, consisting of an upper embossing roller made of metal with an engraved bonding area ratio of 16% and a lower flat metal roller, to obtain a unit area weight of 30 g / m². 2 spunbond nonwoven fabric.

[0299] The evaluation results of the obtained spunbond nonwoven fabric are shown in Table 1. Regarding the obtained spunbond nonwoven fabric, the average single fiber diameter is 12.0 μm, and the tensile strength per unit area weight is 0.89 (N / 25 mm) / (g / m²). 2 The stiffness is 1.6 mN·cm, and the number of defects is 2. The obtained nonwoven fabric not only has softness, but also excellent mechanical properties, with few defects and no problem with high-level processing.

[0300] [Example 2]

[0301] In step (a), raw material resin A was replaced with raw material resin B. In step (b), the spinning speed was changed from 4.0 km / min to 3.5 km / min. Otherwise, spunbond nonwoven fabric was obtained using the same method as in Example 1. It should be noted that the polypropylene resin obtained in step (a) had an MFR of 55 g / 10 min, Mw of 209623, Mw / Mn of 2.97, Mz / Mw of 1.91, and a branching degree λ of 1.0 × 10⁻⁶. -6 .

[0302] The evaluation results of the obtained spunbond nonwoven fabric are shown in Table 1. Regarding the obtained spunbond nonwoven fabric, the average single fiber diameter is 13.0 μm, and the tensile strength per unit area weight is 0.91 (N / 25 mm) / (g / m²). 2 The stiffness is 1.8 mN·cm, the number of defects is 3, and the obtained nonwoven fabric not only has softness, but also excellent mechanical properties, with few defects and no problem with high-level processing.

[0303] [Example 3]

[0304] In step (a), raw material resin A was replaced with raw material resin C. In step (b), the spinning speed was changed from 4.0 km / min to 2.5 km / min. Otherwise, spunbond nonwoven fabric was obtained using the same method as in Example 1. It should be noted that the polypropylene resin obtained in step (a) had an MFR of 20 g / 10 min, Mw of 299587, Mw / Mn of 2.98, Mz / Mw of 1.93, and a branching degree λ of 1.0 × 10⁻⁶. -6 .

[0305] The evaluation results of the obtained spunbond nonwoven fabric are shown in Table 1. Regarding the obtained spunbond nonwoven fabric, the average single fiber diameter is 15.0 μm, and the tensile strength per unit area weight is 0.89 (N / 25 mm) / (g / m²). 2 The stiffness is 2.0 mN·cm, and the number of defects is 5. The obtained nonwoven fabric not only has softness, but also excellent mechanical properties, with few defects and no problem with high-level processing.

[0306] [Example 4]

[0307] In step (a), raw material resin A was replaced with raw material resin D. In step (b), the spinning speed was changed from 4.0 km / min to 4.5 km / min. Otherwise, spunbond nonwoven fabric was obtained using the same method as in Example 1. It should be noted that the polypropylene resin obtained in step (a) had an MFR of 380 g / 10 min, Mw of 105955, Mw / Mn of 2.92, Mz / Mw of 1.83, and a branching degree λ of 1.0 × 10⁻⁶.-6 .

[0308] The evaluation results of the obtained spunbond nonwoven fabric are shown in Table 1. Regarding the obtained spunbond nonwoven fabric, the average single fiber diameter is 11.2 μm, and the tensile strength per unit area weight is 0.79 (N / 25 mm) / (g / m²). 2 The stiffness is 1.2 mN·cm, the number of defects is 1, and the obtained nonwoven fabric not only has softness, but also excellent mechanical properties, with few defects and no problem with high-level processing.

[0309] [Table 1]

[0310] Table 1

[0311]

[0312] [Comparative Example 1]

[0313] In step (a), raw material resin A was replaced with raw material resin E. In step (b), the spinning speed was changed from 4.0 km / min to 4.5 km / min. Otherwise, spunbond nonwoven fabric was obtained using the same method as in Example 1. It should be noted that the polypropylene resin obtained in step (a) had an MFR of 500 g / 10 min, Mw of 96173, Mw / Mn of 2.90, Mz / Mw of 1.81, and a branching degree λ of 1.0 × 10⁻⁶. -6 .

[0314] The evaluation results of the obtained spunbond nonwoven fabric are shown in Table 2. Regarding the obtained spunbond nonwoven fabric, the average single fiber diameter is 11.4 μm, and the tensile strength per unit area weight is 0.45 (N / 25 mm) / (g / m²). 2 The stiffness was 0.9 mN·cm, and the number of defects was 1. Although the obtained nonwoven fabric had excellent softness and few defects, its mechanical properties were worse than those of Example 1, and its high-level processing properties were also problematic.

[0315] [Comparative Example 2]

[0316] In step (a), raw material resin A was replaced with raw material resin F. In step (b), the spinning speed was changed from 4.0 km / min to 2.0 km / min. Otherwise, spunbond nonwoven fabric was obtained using the same method as in Example 1. It should be noted that the polypropylene resin obtained in step (a) had an MFR of 10 g / 10 min, Mw of 382637, Mw / Mn of 3.00, Mz / Mw of 1.95, and a branching degree λ of 1.0 × 10⁻⁶. -6 .

[0317] The evaluation results of the obtained spunbond nonwoven fabric are shown in Table 2. Regarding the obtained spunbond nonwoven fabric, the average single fiber diameter is 16.0 μm, and the tensile strength per unit area weight is 0.70 (N / 25 mm) / (g / m²). 2 The stiffness is 3.5 mN·cm, and the number of defects is more than 20. Although the obtained nonwoven fabric has excellent mechanical properties and no problem with high-level processing, it has poor softness and many defects.

[0318] [Example 5]

[0319] In step (a), regarding the blending of 2.5 parts by mass of polypropylene masterbatch α with 100 parts by mass of raw material resin A scrap, this is replaced by the blending of 0.25 parts by mass of organic peroxide β with 100 parts by mass of raw material resin B scrap. Furthermore, in step (b), the spinning speed is changed from 4.0 km / min to 3.5 km / min. Otherwise, spunbond nonwoven fabric is obtained using the same method as in Example 1. It should be noted that the polypropylene resin obtained in step (a) has an MFR of 55 g / 10 min, Mw of 209623, Mw / Mn of 2.97, Mz / Mw of 1.91, and a branching degree λ of 1.0 × 10⁻⁶. -6 .

[0320] The evaluation results of the obtained spunbond nonwoven fabric are shown in Table 2. Regarding the obtained spunbond nonwoven fabric, the average single fiber diameter is 13.0 μm, and the tensile strength per unit area weight is 0.87 (N / 25 mm) / (g / m²). 2 The stiffness is 1.8 mN·cm, the number of defects is 3, and the obtained nonwoven fabric not only has softness, but also excellent mechanical properties, with few defects and no problem with high-level processing.

[0321] [Example 6]

[0322] In step (a), the melt extrusion temperature was changed from 230°C to 200°C. Otherwise, the spunbond nonwoven fabric was obtained using the same method as in Example 2. It should be noted that the polypropylene resin obtained in step (a) had an MFR of 55 g / 10 min, Mw of 209623, Mw / Mn of 2.97, Mz / Mw of 1.96, and a branching degree λ of 1.0 × 10⁻⁶. -6 .

[0323] The evaluation results of the obtained spunbond nonwoven fabric are shown in Table 2. Regarding the obtained spunbond nonwoven fabric, the average single fiber diameter is 13.0 μm, and the tensile strength per unit area weight is 0.93 (N / 25 mm) / (g / m²). 2The stiffness is 1.8 mN·cm, and the number of defects is 2. The obtained nonwoven fabric not only has softness, but also excellent mechanical properties, with few defects and no problem with high-level processing.

[0324] [Table 2]

[0325] Table 2

[0326]

[0327] [Example 7]

[0328] In step (a), raw material resin A was replaced with raw material resin G. In step (b), the spinning speed was changed from 4.0 km / min to 1.5 km / min. Otherwise, spunbond nonwoven fabric was obtained using the same method as in Example 1. It should be noted that the polypropylene resin obtained in step (a) had an MFR of 55 g / 10 min, Mw of 209623, Mw / Mn of 2.97, Mz / Mw of 1.91, and a branching degree λ of 1.0 × 10⁻⁶. -5 .

[0329] The evaluation results of the obtained spunbond nonwoven fabric are shown in Table 3. Regarding the obtained spunbond nonwoven fabric, the average single fiber diameter is 16.4 μm, and the tensile strength per unit area weight is 0.71 (N / 25 mm) / (g / m²). 2 The stiffness is 1.8 mN·cm, and the number of defects is 8. The obtained nonwoven fabric not only has softness, but also excellent mechanical properties, with few defects and no problem with high-level processing.

[0330] [Example 8]

[0331] In step (a), raw material resin A was replaced with raw material resin H. In step (b), the spinning speed was changed from 4.0 km / min to 3.5 km / min. Otherwise, spunbond nonwoven fabric was obtained using the same method as in Example 1. It should be noted that the polypropylene resin obtained in step (a) had an MFR of 55 g / 10 min, Mw of 209623, Mw / Mn of 2.96, Mz / Mw of 1.91, and a branching degree λ of 1.0 × 10⁻⁶. -7 .

[0332] The evaluation results of the obtained spunbond nonwoven fabric are shown in Table 3. Regarding the obtained spunbond nonwoven fabric, the average single fiber diameter is 13.0 μm, and the tensile strength per unit area weight is 0.85 (N / 25 mm) / (g / m²). 2 The stiffness is 3.0 mN·cm, the number of defects is 3, and the obtained nonwoven fabric not only has softness, but also excellent mechanical properties, with few defects and no problem with high-level processing.

[0333] [Comparative Example 3]

[0334] In step (a), raw material resin A was replaced with raw material resin I, and polypropylene masterbatch α was not used (no organic peroxide was added). In step (b), the spinning speed was changed from 4.0 km / min to 3.5 km / min. Otherwise, spunbond nonwoven fabric was obtained using the same method as in Example 1. It should be noted that the polypropylene resin obtained in step (a) had an MFR of 55 g / 10 min, Mw of 209623, Mw / Mn of 3.22, Mz / Mw of 2.36, and a branching degree λ of 1.0 × 10⁻⁶. -6 .

[0335] The evaluation results of the obtained spunbond nonwoven fabric are shown in Table 3. Regarding the obtained spunbond nonwoven fabric, the average single fiber diameter is 13.0 μm, and the tensile strength per unit area weight is 0.52 (N / 25 mm) / (g / m²). 2 The stiffness was 1.8 mN·cm, and the number of defects was 3. Although the obtained nonwoven fabric had excellent softness and few defects, its mechanical properties were worse than those of Example 2, and its high-level processing properties were also problematic.

[0336] [Comparative Example 4]

[0337] In step (a), the melt extrusion temperature was changed from 230°C to 180°C. Otherwise, the spunbond nonwoven fabric was obtained using the same method as in Example 2. It should be noted that the polypropylene resin obtained in step (a) had an MFR of 55 g / 10 min, Mw of 209623, Mw / Mn of 2.97, Mz / Mw of 1.96, and a branching degree λ of 1.0 × 10⁻⁶. -6 .

[0338] The evaluation results of the obtained spunbond nonwoven fabric are shown in Table 3. Regarding the obtained spunbond nonwoven fabric, the average single fiber diameter is 13.0 μm, and the tensile strength per unit area weight is 0.89 (N / 25 mm) / (g / m²). 2 The stiffness was 1.6 mN·cm, and the number of defects was 3. Although the obtained nonwoven fabric not only has softness, but also excellent mechanical properties, few defects, and no problem with high-level processing, in terms of its impact on the skin, the survival rate of cultured cells was less than 95% in the evaluation using a human epidermal model conceived as sensitive skin.

[0339] [Table 3]

[0340] Table 3

[0341]

[0342] [Comparative Example 5]

[0343] In step (a), raw material resin A is replaced with raw material resin J, and polypropylene masterbatch α is not used (no organic peroxide is added). In step (b), the spinning speed is changed from 4.0 km / min to 4.2 km / min. Otherwise, spunbond nonwoven fabric is obtained by the same method as in Example 1. It should be noted that the polypropylene resin obtained in step (a) has an MFR of 230 g / 10 min, Mw of 151000, Mw / Mn of 5.31, Mz / Mw of 2.70, and a branching degree λ of 0.

[0344] The evaluation results of the obtained spunbond nonwoven fabric are shown in Table 4. Regarding the obtained spunbond nonwoven fabric, the average single fiber diameter is 11.7 μm, and the tensile strength per unit area weight is 0.90 (N / 25 mm) / (g / m²). 2 The stiffness was 0.8 mN·cm, and the number of defects was 1. Although the obtained nonwoven fabric had excellent mechanical properties and few defects, its high-level processing properties were problematic.

[0345] [Example 9]

[0346] In step (a), the amount of polypropylene masterbatch α blended with 2.5 parts by mass of raw material resin A100 parts by mass is instead set to 1.1 parts by mass. In step (b), the spinning speed is changed from 4.0 km / min to 3.5 km / min. Otherwise, spunbond nonwoven fabric is obtained by the same method as in Example 1. It should be noted that the polypropylene resin obtained in step (a) has an MFR of 55 g / 10 min, Mw of 209000, Mw / Mn of 3.71, Mz / Mw of 2.26, and a branching degree λ of 5.0 × 10⁻⁶. -7 .

[0347] The evaluation results of the obtained spunbond nonwoven fabric are shown in Table 4. Regarding the obtained spunbond nonwoven fabric, the average single fiber diameter is 12.8 μm, and the tensile strength per unit area weight is 0.90 (N / 25 mm) / (g / m²). 2 The stiffness is 2.0 mN·cm, the number of defects is 3, and the obtained nonwoven fabric not only has softness, but also excellent mechanical properties, few defects, and no problem with high-level processing.

[0348] [Example 10]

[0349] In step (a), regarding the blending of 2.5 parts by weight of polypropylene masterbatch α with 100 parts by weight of raw material resin A, this is instead set to 3.5 parts by weight of the blended material. Otherwise, spunbond nonwoven fabric is obtained using the same method as in Example 1. It should be noted that the polypropylene resin obtained in step (a) has an MFR of 380 g / 10 min, Mw of 105000, Mw / Mn of 2.80, Mz / Mw of 1.80, and a branching degree λ of 5.0 × 10⁻⁶. -5 .

[0350] The evaluation results of the obtained spunbond nonwoven fabric are shown in Table 4. Regarding the obtained spunbond nonwoven fabric, the average single fiber diameter is 12.0 μm, and the tensile strength per unit area weight is 0.85 (N / 25 mm) / (g / m²). 2 The stiffness is 1.5 mN·cm, and the number of defects is 2. The obtained nonwoven fabric not only has softness, but also excellent mechanical properties, with few defects and no problem with high-level processing.

[0351] [Comparative Example 6]

[0352] In step (a), raw material resin A was replaced with raw material resin K. In step (b), the spinning speed was changed from 4.0 km / min to 3.6 km / min. Otherwise, spunbond nonwoven fabric was obtained using the same method as in Example 1. It should be noted that the polypropylene resin obtained in step (a) had an MFR of 220 g / 10 min, Mw of 147,000, Mw / Mn of 2.96, Mz / Mw of 1.91, and a branching degree λ of 0.

[0353] The evaluation results of the obtained spunbond nonwoven fabric are shown in Table 4. Regarding the obtained spunbond nonwoven fabric, the average single fiber diameter is 12.5 μm, and the tensile strength per unit area weight is 0.90 (N / 25 mm) / (g / m²). 2 The stiffness was 0.7 mN·cm, and the number of defects was 1. Although the obtained nonwoven fabric had excellent mechanical properties and few defects, its high-level processing properties were problematic.

[0354] [Table 4]

[0355] Table 4

[0356]

[0357] [Example 11]

[0358] In step (c), the bonding temperature based on the hot embossing roller was changed from 130°C to 135°C; otherwise, the spunbond nonwoven fabric was obtained using the same method as in Example 1. It should be noted that the polypropylene resin obtained in step (a) had an MFR of 200 g / 10 min, Mw of 132899, Mw / Mn of 2.95, Mz / Mw of 1.85, and a branching degree λ of 1.0 × 10⁻⁶. -6 .

[0359] The evaluation results of the obtained spunbond nonwoven fabric are shown in Table 5. Regarding the obtained spunbond nonwoven fabric, the average single fiber diameter is 12.0 μm, and the tensile strength per unit area weight is 1.09 (N / 25 mm) / (g / m²). 2 The stiffness is 1.9 mN·cm, and the number of defects is 2. The obtained nonwoven fabric not only has softness, but also excellent mechanical properties, with few defects and no problem with high-level processing.

[0360] [Table 5]

[0361] Table 5

[0362]

Claims

1. Spunbond nonwoven fabric, which is a spunbond nonwoven fabric composed of fibers formed from polypropylene resin, wherein, The spunbond nonwoven fabric satisfies the following conditions (1) to (3), and the average single fiber diameter of the fibers is 5.0 μm or more and 20.0 μm or less. (1) The amount of organic peroxide extracted by ultrasonic treatment of the spunbond nonwoven fabric impregnated in a chloroform / methanol solvent with a volume ratio of 1:1 at 15 minutes, 45 kHz and a solution temperature of 30 °C is more than 100 ppm and less than 1000 ppm. (2) The melt flow rate is above 20g / 10min and below 400g / 10min; (3) The degree of branching λ per molecule of the polypropylene resin, calculated using the molecular weight and radius of gyration determined by gel permeation chromatography / multi-angle light scattering analyzer and the trifunctional random branching theory, is 1.0 × 10⁻⁶. -7 Above 1.0×10 -3 the following.

2. The spunbond nonwoven fabric according to claim 1, wherein, The polypropylene resin further satisfies the following conditions (4) and (5). (4) 2.50≤Mw / Mn≤3.20; (5) 1.82≤Mz / Mw≤2.20 Wherein, Mw, Mn, and Mz are the weight-average molecular weight, number-average molecular weight, and z-average molecular weight obtained by gel permeation chromatography, respectively.

3. The method for manufacturing the spunbond nonwoven fabric according to claim 1 or 2, comprising: The process of adding an organic peroxide to a raw material resin to decompose the raw material resin, thereby obtaining a polypropylene resin prepared in a manner that satisfies the following conditions (1) to (3); The process of spinning the polypropylene resin to obtain fibers with an average single fiber diameter of 5.0 μm to 20.0 μm; and The process of capturing the fibers. (1) The amount of organic peroxide extracted by ultrasonic treatment of the spunbond nonwoven fabric impregnated in a chloroform / methanol solvent with a volume ratio of 1:1 at 15 minutes, 45 kHz and a solution temperature of 30 °C is more than 100 ppm and less than 1000 ppm. (2) The melt flow rate is above 20g / 10min and below 400g / 10min; (3) The degree of branching λ per molecule of the polypropylene resin, calculated using the molecular weight and radius of gyration determined by gel permeation chromatography / multi-angle light scattering analyzer and the trifunctional random branching theory, is 1.0 × 10⁻⁶. -7 Above 1.0×10 -3 the following.

4. The method for manufacturing spunbond nonwoven fabric according to claim 3, wherein, The raw material resin is recycled resin.

5. A laminated nonwoven fabric comprising the spunbond nonwoven fabric of claim 1.

6. A sanitary material made using the spunbond nonwoven fabric of claim 1 or the laminated nonwoven fabric of claim 5.

7. Clothing made using the spunbond nonwoven fabric of claim 1 or the laminated nonwoven fabric of claim 5.

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