Title of invention: Spunbond nonwoven fabric, sanitary material, and method for producing spunbond nonwoven fabric
Technical field
[0001]
　The present disclosure relates to spunbond nonwovens, sanitary materials, and methods of making spunbond nonwovens.
Background technology
[0002]
　In recent years, nonwoven fabrics have been widely used for various purposes because of their excellent air permeability and flexibility. Typical uses of the non-woven fabric include, for example, absorbent articles such as paper diapers and sanitary napkins, hygiene masks, medical gauze, and base cloth for poultices.
　Such a non-woven fabric is required to have extensibility depending on the location where it is used.
[0003]
　For example, Japanese Unexamined Patent Publication No. 9-512313 proposes a technique relating to a contact type stretchable nonwoven fabric which contains polyethylene and propylene polymer and has good stretchability as a nonwoven fabric included in the composite nonwoven fabric.
　Further, International Publication No. 2014/050965 proposes, as a flexible nonwoven fabric, a spunbond nonwoven fabric composed of a composition containing two or more kinds of polypropylenes having different melting points from each other and a specific fatty acid amide.
　Further, in JP-A-2005-071854, a thermoplastic polyurethane elastomer containing ethylene bisoleic acid amide and/or crosslinked organic fine particles is used as a spunbonded non-woven fabric which is suitable for sanitary materials and has good stretchability and touch. , A spunbonded nonwoven fabric using a thermoplastic polyurethane elastomer having a hardness in the range of 75 to 85 has been proposed.
　In addition, in WO 2017/006972, in addition to propylene homopolymer having a relatively high melting point and polyethylene, as a spunbonded nonwoven fabric having good heat sealability at low temperature and suitability for stretching, polyethylene Includes a polymer selected from the group consisting of a random copolymer of α-olefin having a carbon number and propylene, and a propylene homopolymer having a relatively low melting point and a specific mesopentad fraction and racemic pentad fraction. Spunbond nonwovens have been proposed.
Summary of the invention
Problems to be Solved by the Invention
[0004]
　In the contact type stretchable non-woven fabric described in Japanese Patent Publication No. 9-512313, it is assumed that the composite non-woven fabric has a second stretchable layer. Improvement may be required.
　The spunbonded nonwoven fabric described in WO 2014/050965 may be required to have improved stretchability.
　Since the spunbonded nonwoven fabric described in JP-A-2005-071854 uses a thermoplastic polyurethane elastomer, the heat resistance is not sufficient, so that there is a case where improvement in processability is required.
　The spunbonded nonwoven fabric described in WO 2017/006972 may be required to have improved extensibility.
[0005]
　An object of one embodiment of the present invention is to provide a spunbonded nonwoven fabric excellent in extensibility and a sanitary material using the spunbonded nonwoven fabric without using a thermoplastic polyurethane elastomer.
　An object of another embodiment of the present invention is to provide a method for producing a spunbonded nonwoven fabric having excellent extensibility.
Means for solving the problem
[0006]
　Means for solving the above problems include the following embodiments.
<1>
　Propylene homopolymer having a melting point of 140° C. or higher, polyethylene, and at least one polymer selected from the group consisting of the following polymers (I) and (II) A
　spunbonded non-woven fabric , comprising a fiber made of a composition, wherein the fiber has a sea-island structure, and the average length of the island phase in a cross section along the long axis direction of the fiber is 1 μm or more and 500 μm or less.
　(I) Random copolymer of propylene and at least one selected from ethylene and α-olefins having 4 to 20 carbon atoms
　(II) Melting point less than 120° C. satisfying the following (a) to (f): Of propylene homopolymer
(a) [mmmm]=20 mol% or more and 60 mol% or less
(b) [rrrr]/(1-[mmmm])≦0.1
(c) [rmrm]>2.5 mol%
(D) [mm]×[rr]/[mr] 2 ≦2.0
(e) Weight average molecular weight (Mw)=10,000 or more and 200,000 or less
(f) Molecular weight distribution (Mw/Mn)<4
( In a) to (d), [mmmm] is a mesopentad fraction, [rrrr] is a racemic pentad fraction, [rmrm] is a racemic mesoracemic mesopentad fraction, and [mm], [mm], rr] and [mr] are triad fractions, respectively.
[0007]
<2>
　The spunbond nonwoven fabric according to <1>, wherein the content of the polyethylene is 1.0% by mass or more and 15.0% by mass or less with respect to the total amount of the composition.
[0008]
<3>
　The content of at least one polymer selected from the group consisting of the polymer shown in (I) and the polymer shown in (II) is 5.0% by mass or more based on the total amount of the composition. The spunbond nonwoven fabric according to <1> or <2>, which is 30.0 mass% or less.
[0009]
<4>
　Any of <1> to <3>, wherein the content of the propylene homopolymer having a melting point of 140° C. or higher is 55.0% by mass or more and 90.0% by mass or less based on the total amount of the composition. 1. The spunbonded nonwoven fabric according to item 1.
[0010]
<5>
　density of the polyethylene, 0.941 g / cm 3 or more 0.970 g / cm 3 in the following range, <1> to <4> spunbonded nonwoven fabric according to any one of the.
[0011]
<6> The
　composition contains a fatty acid amide having 15 or more and 22 or less carbon atoms, and the content of the fatty acid amide having 15 or more and 22 or less carbon atoms is 0.1% by mass or more based on the total amount of the composition. The spunbonded nonwoven fabric according to any one of <1> to <5>, which is 0 mass% or less.
[0012]
<7>
　The spunbonded nonwoven fabric according to any one of <1> to <6>, wherein the polymer shown in (I) is a random copolymer containing at least propylene and ethylene.
[0013]
<8>
　A sanitary material containing the spunbonded nonwoven fabric according to any one of <1> to <7>.
[0014]
<9>
　Polyethylene is melted at 180° C. or higher and 200° C. or lower, and the melted polyethylene is passed through a sieve having an opening of 65 μm or less, and a filtration step, and
　polyethylene passed through the sieve in the filtration step, and a melting point of 140° C. or higher. A propylene homopolymer of (1) and at least one polymer selected from the group consisting of the polymer shown in (I) and the polymer shown in (II) below to obtain a composition,
　A non-woven fabric forming step of obtaining a non-woven fabric from the composition obtained in the mixing step by a spunbond method, and
having a diameter of 0 included in the membrane formed of the polyethylene that has passed through the sieve in the filtration step. A method for producing a spunbonded nonwoven fabric, wherein the number of particles having a size of 2 mm or less is 25 particles/g or less.
　(I) Random copolymer of propylene and at least one selected from ethylene and α-olefins having 4 to 20 carbon atoms
　(II) Melting point less than 120° C. satisfying the following (a) to (f): Of propylene homopolymer
(a) [mmmm]=20 mol% or more and 60 mol% or less
(b) [rrrr]/(1-[mmmm])≦0.1
(c) [rmrm]>2.5 mol%
(D) [mm]×[rr]/[mr] 2 ≦2.0
(e) Weight average molecular weight (Mw)=10,000 or more and 200,000 or less
(f) Molecular weight distribution (Mw/Mn)<4
In (a) to (d), [mmmm] is a mesopentad fraction, [rrrr] is a racemic pentad fraction, [rmrm] is a racemic mesoracemic mesopentad fraction, and [mm] is [Rr] and [mr] are triad fractions, respectively.
[0015]
<10> The
　method for producing a spunbonded nonwoven fabric according to <9>, wherein the content of the polyethylene used in the mixing step is 1.0% by mass or more and 15.0% by mass or less with respect to the total amount of the composition. ..
[0016]
<11>
　The content of at least one polymer selected from the group consisting of the polymers (I) and (II) used in the mixing step is 5 with respect to the total amount of the composition. The method for producing a spunbonded nonwoven fabric according to <9> or <10>, which is from 30% by mass to 30% by mass.
[0017]
<12>
　The content of the propylene homopolymer having a melting point of 140° C. or higher used in the mixing step is 55.0% by mass or more and 90.0% by mass or less based on the total amount of the composition, <9> to <11> A method for producing a spunbonded nonwoven fabric according to any one of <11>.
[0018]
<13> The
　mixing step is a step of further mixing a fatty acid amide having 15 to 22 carbon atoms to obtain a composition, and the content of the fatty acid amide having 15 to 22 carbon atoms is the total amount of the composition. The method for producing a spunbonded nonwoven fabric according to any one of <9> to <12>, wherein the content is 0.1% by mass or more and 5.0% by mass or less.
Effect of the invention
[0019]
　According to one embodiment of the present invention, a spunbonded nonwoven fabric having excellent extensibility and a hygienic material using the spunbonded nonwoven fabric are provided.
　According to another embodiment of the present invention, a method for producing a spunbonded nonwoven fabric having excellent extensibility is provided.
Brief description of the drawings
[0020]
FIG. 1A is an image obtained by observing a cross section of a fiber in the spunbonded nonwoven fabric of Example 1 with a transmission electron microscope.
FIG. 1B is an image obtained by observing a cross section of a fiber in the spunbonded nonwoven fabric of Comparative Example 1 with a transmission electron microscope.
FIG. 2 is a schematic view of a closed spun bond method.
FIG. 3 is a schematic view of a gear stretching device.
MODE FOR CARRYING OUT THE INVENTION
[0021]
　Hereinafter, an embodiment of the present invention (hereinafter, also referred to as “the present embodiment”) will be described.
　However, the present invention is not limited to the following embodiments. In the following embodiments, the constituent elements (including element steps, etc.) are not essential unless otherwise specified, unless otherwise apparent in principle. The same applies to the numerical values ​​and the range thereof, and does not limit the present invention.
[0022]
　In the present specification, the term “step” is included in the term as long as the purpose of the step is achieved not only as an independent step but also when it cannot be clearly distinguished from other steps.
　In the present specification, the content of each component in the composition is the sum of the substances of the plurality of types present in the composition, unless a plurality of types of substances corresponding to the components are present in the composition. Means quantity.
　In the numerical ranges described stepwise in the present specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of another stepwise described numerical range. Further, in the numerical range described in the present specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the values ​​shown in the examples.
　In the present specification, a combination of two or more preferred embodiments is a more preferred embodiment.
[0023]

　The spunbonded nonwoven fabric of the present embodiment is selected from the group consisting of a propylene homopolymer having a melting point of 140° C. or higher, polyethylene, a polymer shown in (I) below and a polymer shown in (II) below. At least one polymer which is used, and the fiber has a sea-island structure, and the average length of the island phase in a cross section along the major axis direction of the fiber is 1 μm or more and 500 μm or less. , A spunbond nonwoven fabric.
　(I) Random copolymer of propylene and at least one selected from ethylene and α-olefins having 4 to 20 carbon atoms
　(II) Melting point less than 120° C. satisfying the following (a) to (f): Of propylene homopolymer
(a) [mmmm]=20 mol% or more and 60 mol% or less
(b) [rrrr]/(1-[mmmm])≦0.1
(c) [rmrm]>2.5 mol%
(D) [mm]×[rr]/[mr] 2 ≦2.0
(e) Weight average molecular weight (Mw)=10,000 or more and 200,000 or less
(f) Molecular weight distribution (Mw/Mn)<4
( In a) to (d), [mmmm] is a mesopentad fraction, [rrrr] is a racemic pentad fraction, [rmrm] is a racemic mesoracemic mesopentad fraction, and [mm], [mm] rr] and [mr] are triad fractions, respectively.
　The "at least one polymer selected from the group consisting of the polymer shown in (I) and the polymer shown in (II)" may be collectively referred to as "specific polymer".
　Moreover, since the fibers constituting the spunbonded nonwoven fabric of the present embodiment are composed of the composition containing the above-mentioned components, the content of each component in the fiber is the same as the content of each component in the composition.
[0024]
　The spunbond nonwoven fabric of the present embodiment is composed of a fiber having a composition having a relatively high melting point of propylene homopolymer, polyethylene, and a specific polymer, and the fiber has a sea-island structure, The average length of the island phase in the cross section along the major axis direction of the fiber is 1 μm or more and 500 μm or less.
　The present inventors have obtained a spunbonded nonwoven fabric containing fibers having the above-mentioned sea-island structure, and having an average island phase length of 1 μm or more and 500 μm or less in a cross section along the long axis direction of the fibers. We obtained new knowledge that the extensibility of the It is presumed that the fiber has a sea-island structure as described above, which inhibits the oriented crystallization of polypropylene and enhances the extensibility. However, when the average length of the island phase is within the above range, the extensibility is more improved. The reason for the rise is unclear.
[0025]
　The spunbonded nonwoven fabric of this embodiment is composed of fibers having a sea-island structure. The average length of the island phase in the sea-island structure of the fibers is 1 μm or more and 500 μm or less. The length of the island phase is preferably 1 μm or more and 100 μm or less, and more preferably 3 μm or more and 50 μm or less.
　When the length of the island phase is 1 μm or more and 500 μm or less, excellent extensibility is obtained as described above.
[0026]
　Here, the length of the island phase in the sea-island structure of the fiber is measured as follows.
　First, fibers are taken out from a spunbonded nonwoven fabric and embedded in paraffin to prepare a measurement sample. Then, the measurement sample is placed on a microtome so that the blade is parallel to the long axis direction of the fiber, and sliced ​​along the long axis direction of the fiber. Then, after slicing the obtained fiber and applying carbon reinforcement, the cross section is observed using a transmission electron microscope (TEM), and the length of any 100 island phases is measured. Then, find the average length.
　Here, as the transmission electron microscope, a transmission electron microscope model: H-7650 manufactured by Hitachi High-Tech Co., Ltd. is used. The observation magnification is not particularly limited as long as the length of the island phase can be measured, but is 8000 times, for example.
　If the end of the fiber cannot be observed due to embossing, the length of the island phase from the other end to the boundary of embossing may be measured. If both ends of the fiber cannot be observed due to embossing, the length of the island phase from one embossing boundary to the other embossing boundary may be measured.
　That is, in the present invention, "the length of the island phase in the sea-island structure of the fiber" is the length of the island phase from one end of the island phase to the embossing boundary, and also from the one embossing boundary. Including the case where the length of the island phase extends to the other embossing boundary.
[0027]
　FIG. 1 shows a cross-sectional image of a fiber observed with a transmission electron microscope. 1A is a cross-sectional image of fibers in the spunbonded nonwoven fabric of Example 1, and FIG. 1B is a cross-sectional image of fibers in the spunbonded nonwoven fabric of Comparative Example 1.
[0028]
　It can be appropriately confirmed by a known method that the composition or the fiber made of the composition of the spunbonded nonwoven fabric of the present embodiment contains each of the above components.
　The propylene homopolymer having a melting point of less than 120° C. in the polymer shown in (II) has a mesopentad fraction [mmmm], a racemic pentad fraction [rrrr], a racemic mesoracemic mesopentad fraction [rmrm], a triad. The fractions [mm], [rr], and [mr] are based on the method proposed in “Macromolecules, 6, 925 (1973)” by A. Zambelli, etc., as described in detail below. Can be calculated.
[0029]
　In the composition of the present embodiment, the content of polyethylene is preferably 1.0% by mass or more and 15.0% by mass or less, and 3.0% by mass or more and 12.0% by mass with respect to the total amount of the composition. % Or less, more preferably 6.0% by mass or more and 10.0% by mass or less.
　When the content of polyethylene is within the above range, the extensibility of the obtained spunbonded nonwoven fabric can be improved.
[0030]
　From the viewpoint of improving the strength of the spunbonded nonwoven fabric, polyethylene has a density in the range of 0941 g/cm 3 or more and 0.970 g/cm 3 or less so that the extensibility and flexibility of the obtained spunbonded nonwoven fabric are improved. It is preferable from the viewpoint of improvement.
　When the density of polyethylene is within the above range, the strength of the spunbonded nonwoven fabric obtained can be improved.
[0031]
　In the composition of the present embodiment, the content of the specific polymer is preferably 5.0% by mass or more and 30.0% by mass or less, and 10.0% by mass or more and 30.% or less, based on the total amount of the composition. It is more preferably 0% by mass or less, and further preferably 15.0% by mass or more and 25.0% by mass or less.
　When the content of the specific polymer is within the above range, the extensibility of the obtained spunbonded nonwoven fabric can be improved.
[0032]
　The specific polymer in the present embodiment is a random copolymer containing at least a structural unit derived from (I) propylene and a structural unit derived from ethylene, from the viewpoint of further improving the extensibility of the spunbonded nonwoven fabric obtained, or , A propylene homopolymer having a melting point of less than 120° C. that satisfies (II)(a) to (f) is preferable. From the same viewpoint, the specific polymer is more preferably a random copolymer containing at least a constitutional unit derived from propylene and a constitutional unit derived from ethylene, and only from a constitutional unit derived from propylene and a constitutional unit derived from ethylene. Is more preferable.
[0033]
　In the composition of the present embodiment, the content of the propylene homopolymer having a melting point of 140°C or higher is preferably 55.0% by mass or more and 90.0% by mass or less based on the total amount of the composition, and 60. It is more preferably 0% by mass or more and 85.0% by mass or less, and further preferably 65.0% by mass or more and 80.0% by mass or less.
　When the content of the propylene homopolymer having a melting point of 140° C. or higher is within the above range, it is possible to improve the extensibility of the spunbonded nonwoven fabric obtained, and at the same time, the strength and physical properties of the spunbonded nonwoven fabric are maintained in a good range, and the low basis weight is obtained. It is easy to obtain a flexible nonwoven fabric.
[0034]
　The composition in the present embodiment preferably contains a fatty acid amide having 15 or more and 22 or less carbon atoms. When the composition contains a fatty acid amide having 15 or more and 22 or less carbon atoms, the fatty acid amide having 15 or more and 22 or less carbon atoms is adsorbed on the fiber surface of the spunbond nonwoven fabric formed by the composition, and the fiber surface is modified. To be done. As a result, the extensibility and flexibility of the spunbond nonwoven fabric are further improved.
　The content of the fatty acid amide having 15 or more and 22 or less carbon atoms is preferably 0.1% by mass or more and 5.0% by mass or less, and 0.1% by mass or more and 3.0% by mass with respect to the total amount of the composition. % Or less, more preferably 0.1% by mass or more and 1.0% by mass or less.
[0035]
[Aspects and Physical Properties
　of Spunbonded Nonwoven Fabric] Preferred aspects and physical properties of the spunbonded nonwoven fabric of the present embodiment will be described below.
[0036]
(A value obtained by dividing 5% strength by the unit weight of the nonwoven fabric and an integrated value of stress integral values ​​at the time of 50% stretching) In
　the spunbonded nonwoven fabric of the present embodiment, a value obtained by dividing 5% strength by the unit weight of the nonwoven fabric is 0.2 N/ It is preferable that it is 25 mm/(g/m 2 ) or more, and the integrated value of the stress integral value at the time of 50% stretching is 70 N/(g/m 2 ) or less.
　The value obtained by dividing 5% strength by the basis weight of the nonwoven fabric means a tensile test in accordance with JIS L 1906 6.12.1 [Method A] in the flow direction (that is, MD direction) at the time of manufacturing the nonwoven fabric, A value obtained by dividing the MD5% strength, which is the tensile load in the state of being stretched 5% from the tensile test start state, by the basis weight, which is the weight per unit area of ​​the nonwoven fabric. In addition, the stress integral value at the time of 50% stretching refers to a stress integral from a tensile test start state to a 50% stretched state by performing a tensile test in accordance with JIS L 1906 6.12.1 [Method A]. It refers to the value obtained by dividing the integrated value by the unit weight, which is the weight per unit area of ​​the nonwoven fabric.
　The spunbonded nonwoven fabric having this preferable physical property can be obtained by using the open type spunbond method described later.
[0037]
　The basis weight of the spunbonded nonwoven fabric of this embodiment is not particularly limited.
　From the viewpoint of achieving both flexibility and strength, the spunbonded nonwoven fabric of the present embodiment usually has a basis weight of preferably 30 g/m 2 or less, more preferably 28 g/m 2 or less, and 25 g. /M 2 or less is more preferable, and the range of 5 g/m 2 or more and 20 g/m 2 or less is most preferable. When the spunbonded nonwoven fabric of the present embodiment is applied to a sanitary material or the like described later, the basis weight of the spunbonded nonwoven fabric is preferably in the range of 5 g/m 2 or more and 19 g/m 2 or less.
　The basis weight can be measured by the method used in Examples described later.
[0038]
(Fiber diameter)
　Generally, the fiber constituting the spunbonded nonwoven fabric of the present embodiment preferably has a fiber diameter of 50 μm or less, more preferably 40 μm or less, further preferably 30 μm or less, and most preferably Is 20 μm or less. The smaller the fiber diameter, the better the flexibility of the nonwoven fabric. The fiber diameter is preferably 10 μm or more from the viewpoints of handleability, production suitability, and suppression of fluffing of the obtained nonwoven fabric.
[0039]
(Heat Sealability)
　One of the physical properties of the spunbonded nonwoven fabric of this embodiment is heat sealability.
　As for the heat-sealing property of the spunbonded non-woven fabric, when two non-woven fabrics are superposed and heat-sealed by a heat-sealing tester, it is preferable that the non-woven fabric can be heat-sealed at a temperature of 180°C or lower, and heat-sealed at a temperature of 160°C or lower. Is more preferable.
　In addition, it is preferable to prevent burning when heat-sealed under the above conditions, that is, discoloration due to heating.
　The presence or absence of heat sealability may be evaluated by confirming the tensile peel strength (also referred to as heat seal strength) of the two heat-sealed spunbonded nonwoven fabrics. For example, the heat-sealing strength is appropriately determined depending on the purpose of use of the spunbonded nonwoven fabric, but in general, it is preferably 0.05 N/20 mm or more, more preferably 0.1 N/20 mm or more.
　The presence or absence of heat sealability is confirmed, for example, by the method used in Examples described later.
[0040]
(Embossing Residual Rate)
　One of the physical properties of the spunbonded nonwoven fabric of the present embodiment is the embossing residual rate.
　The embossing residual rate of the spunbonded nonwoven fabric after stretching is preferably 40% or more, more preferably 50% or more, still more preferably 70% or more.
　When the embossing residual rate after stretching is 40% or more, the feel of the spunbonded nonwoven fabric becomes better.
　The emboss residual rate can be measured by the method used in Examples described later.
[0041]
(Flexibility)
　One of the physical properties of the spunbonded nonwoven fabric of the present embodiment is flexibility .
　The flexibility of spunbonded nonwoven fabric has a great influence on the feeling of use of the nonwoven fabric. Examples of the flexibility include flexibility by sensory evaluation by touch (for example, flexibility in the method described in detail in Examples) and bending resistance. It can be measured in accordance with 8.21.1 [Method A (45° cantilever method)] of JIS L 1096:2010.
[0042]
(Maximum elongation and maximum strength)
　One of the preferable physical properties of the spunbonded nonwoven fabric of the present embodiment is maximum elongation and maximum strength.
　The spunbonded nonwoven fabric of the present embodiment preferably has a maximum elongation in at least one direction of 70% or more, more preferably 100% or more, and further preferably 140% or more.
　In the spunbonded nonwoven fabric of the present embodiment, the maximum strength in at least one direction is preferably 10N/50nn or more, more preferably 15N/50nn or more, and further preferably 20N/50nn or more.
　Further, a spunbonded nonwoven fabric having a property of almost no elastic recovery is preferable.
　The maximum elongation and the maximum strength of the spunbonded nonwoven fabric can be measured according to JIS L 1906 6.12.1 [Method A], as described in detail in Examples.
[0043]
　The spunbonded nonwoven fabric of the present embodiment can be produced by a conventional method using one or more of the compositions described in detail below.
[0044]
[Ingredients Included in Composition] As
　described above, the composition of the spunbonded nonwoven fabric of the present embodiment may have a propylene homopolymer having a melting point of 140° C. or higher (hereinafter, referred to as “specific polypropylene”). ), polyethylene, and at least one polymer (specific polymer) selected from the group consisting of the polymer represented by (I) and the polymer represented by (II).
　Hereinafter, each component contained in the composition will be described in detail.
[0045]
　From the viewpoint of effectively achieving the object of the present embodiment, the total content of the specific polypropylene and the specific polymer in the total mass of the composition is preferably 80% by mass or more, and 90% by mass or more. Is more preferable, and 92% by mass or more is further preferable.
[0046]
[Propylene homopolymer having a melting point of 140° C. or higher (specific polypropylene)]
　A propylene homopolymer having a melting point of 140° C. or higher contains only structural units derived from propylene and has a melting point of 140° C. or higher.
　The melting point of the propylene homopolymer is preferably 150° C. or higher. The upper limit of the melting point of the propylene homopolymer is, for example, 166°C.
[0047]
　The specific polypropylene is a crystalline resin manufactured or sold under the name of polypropylene, and any resin having a melting point (Tm) of 140° C. or higher can be used. Examples of commercially available products include propylene homopolymers having a melting point of 155° C. or higher, preferably 157° C. or higher and 166° C. or lower.
　The melting point of the specific polypropylene is defined by the same definition as the melting point of the polymer (I) described later, and can be measured by the same method as the melting point of the polymer (I) described below.
[0048]
　The melt flow rate (MFR: ASTM D 1238, measurement condition: temperature 230° C., load 2160 g) of the specific polypropylene is not particularly limited as long as it can be melt-spun. The melt flow rate of the specific polypropylene is usually 1 g/10 minutes or more and 1000 g/10 minutes or less, preferably 5 g/10 minutes or more and 500 g/10 minutes or less, and more preferably 10 g/10 minutes or more and 100 g/10 minutes or less. In range.
[0049]
　Only one type of specific polypropylene may be used in the composition, or two or more types having different melting points, molecular weights, crystal structures and the like may be used.
　The preferable content of the specific polypropylene with respect to the total amount of the composition is as described above.
[0050]
[Polyethylene]
　Polyethylene is not particularly limited as long as it is a polyethylene containing a structural unit derived from ethylene, and specifically, high-pressure low-density polyethylene, linear low-density polyethylene (so-called LLDPE), high-density polyethylene (so-called HDPE). ) And other ethylene homopolymers.
　Among them, the polyethylene, as described previously, density 0.941 g / cm 3 or more 0.970 g / cm 3 to be a high density polyethylene in the range of elongation, flexibility, and strength at break more It is preferable from the viewpoint of improvement.
[0051]
　The polyethylene is preferably polyethylene in which, when a film is formed from polyethylene, the number of particles having a diameter of 0.2 mm or less contained in the film is 25 particles/g or less.
　Further, polyethylene is preferably polyethylene in which, when a film is formed from polyethylene, the number of particles having a diameter of 2 mm or less contained in the film is 10 particles/g or less.
[0052]
　Only one kind of polyethylene may be used in the composition, or two or more kinds of polyethylene having different melting points, molecular weights, crystal structures and the like may be used.
　The preferable content of polyethylene based on the total amount of the composition is as described above.
[0053]
[Specific polymer] In the
　present embodiment, by using a composition containing the specific polymer, the spunbonded nonwoven fabric obtained, while maintaining good flexibility and extensibility, obtains extremely excellent stretchability. be able to.
[0054]
[Polymer represented by (I): Random copolymer of propylene and at least one selected from ethylene and α-olefins having 4 to 20 carbon atoms] Polymer
　represented by (I) (hereinafter, The polymer (I) may include a structural unit derived from propylene and a structural unit derived from at least one olefin selected from ethylene and α-olefins having 4 to 20 carbon atoms. It is a random copolymer.
　It is preferable that the polymer (I) is a random copolymer from the viewpoint that the obtained spunbonded nonwoven fabric does not have stickiness and the flexibility is improved.
　The polymer (I) is not particularly limited as long as it is a random copolymer containing the above structural unit.
[0055]
　The structural unit that can be copolymerized with propylene is a structural unit derived from ethylene; an α-olefin having 4 to 20 carbon atoms such as 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene. Examples of the constituent units include the constituent units.
　Of these, a structural unit derived from ethylene and a structural unit derived from an α-olefin having 4 to 8 carbon atoms are preferable.
　The constitutional unit derived from the α-olefin contained in the polymer (I) may be only one type, or may be two or more types.
　Specific preferred examples of the polymer (I) include a propylene/1-butene random copolymer, a propylene/ethylene random copolymer, and a propylene/ethylene/1-butene random copolymer.
[0056]
　From the viewpoint of effectively achieving the object of the present embodiment, the total of structural units derived from propylene and structural units derived from the olefin other than propylene such as ethylene in all the structural units contained in the polymer (I). The ratio is preferably 80 mol% or more, more preferably 85 mol% or more, still more preferably 90 mol% or more.
[0057]
　The melting point of the polymer (I) is preferably 100° C. or higher, more preferably 130° C. or higher, even more preferably 140° C. or higher.
　The melting point of the polymer (I) was measured by using a differential scanning calorimeter (DSC), which was obtained by holding at −40° C. for 5 minutes in a nitrogen atmosphere and then raising the temperature at 10° C./minute. It is defined as the peak top of the peak observed on the highest temperature side.
　Specifically, by using a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer Co., Ltd.), 5 mg of the sample was kept at −40° C. for 5 minutes in a nitrogen atmosphere, and then heated at 10° C./minute. It can be determined as the peak top of the peak observed on the highest temperature side of the obtained melting endothermic curve.
[0058]
　The crystallinity of the polymer (I) is preferably 15% or less, more preferably 10% or less, still more preferably 8% or less.
　The crystallinity of the polymer (I) was measured by using a differential scanning calorimeter (DSC), which was obtained by holding at −40° C. for 5 minutes in a nitrogen atmosphere and then raising the temperature at 10° C./minute. It is calculated from the heat of fusion curve derived from the melting of the main component in the curve.
　Specifically, by using a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer Co., Ltd.), 5 mg of the sample was kept at −40° C. for 5 minutes in a nitrogen atmosphere, and then heated at 10° C./minute. It can be calculated using the following formula from the melting heat curve derived from the melting of the main component in the obtained melting heat absorption curve.
　Crystallinity=ΔH/ΔH 0×100(%)
　where ΔH is the heat of fusion (J/g) obtained from the heat of fusion curve derived from the melting of the main component of the α-olefin copolymer containing ethylene and propylene. Yes, ΔH0 is the heat of fusion (J/g) of the complete crystal of the main component. That is, when the main component is ethylene, ΔH0 is 293 J/g, and when the main component is propylene, ΔH0 is 210 J/g.
[0059]
　The tensile modulus of the polymer (I) measured by the method according to JIS K 7161:2011 is preferably 100 MPa or less, more preferably 40 MPa or less, and further preferably 25 MPa or less. ..
[0060]
　The polymer (I) has a melt flow rate (MFR, measurement conditions: temperature of 230° C., load of 2160 g) measured by a method according to ASTM D 1238, from the viewpoint of obtaining good spinnability and excellent stretchability. Usually, it is preferably in the range of 1 g/10 minutes or more and 100 g/10 minutes or less, more preferably in the range of 5 g/10 minutes or more and 100 g/10 minutes or less, and 30 g/10 minutes or more and 70 g/10 minutes or less It is even more preferable that it is in the range.
[0061]
　The ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the polymer (I): Mw/Mn (molecular weight distribution) is usually 1.5 or more and 5.0 or less. The molecular weight distribution (Mw/Mn) of the polymer (I) is more preferably 1.5 or more and 3.0 or less from the viewpoint of obtaining a conjugated fiber having better spinnability and particularly excellent fiber strength.
　Good spinnability means that yarn breakage does not occur when the polymer (I) is discharged from the spinning nozzle and during drawing, and fusion of filaments does not occur.
　Mw and Mn of the polymer (I) can be measured by a known method by GPC (gel permeation chromatography).
　The Mw and Mn of the polymer (I) can be measured by the same method as the Mw and Mn of the polymer (II) described later.
[0062]
[Polymer represented by (II): Propylene homopolymer satisfying the following requirements (a) to (f)] The polymer
　represented by (II) (hereinafter sometimes referred to as polymer (II)) is as follows. It is a polymer that satisfies the requirements (a) to (f).
　First, the requirements (a) to (f) will be described.
[0063]
-(A) [mmmm] = 20 mol% or more and 60 mol% or less When
　the mesopentad fraction [mmmm] of the polymer (II) is 20 mol% or more, the occurrence of stickiness is suppressed and it is 60 mol% or less. Since the crystallinity does not become too high, the elastic recovery property becomes good.
　The mesopentad fraction [mmmm] is preferably 30 mol% or more and 50 mol% or less, and more preferably 40 mol% or more and 50 mol% or less.
[0064]
　The mesopentad fraction [mmmm], the racemic pentad fraction [rrrr] and the racemic mesoracemic mesopentad fraction [rmrm], which will be described later, are described in “Macromolecules, 6, 925 (1973)” by A. Zambelli and others. And a racemic fraction and a racemic meso-racemic meso fraction in a pentad unit in a polypropylene molecular chain measured by a signal of a methyl group in a 13 C-NMR spectrum. .. The stereoregularity increases as the mesopentad fraction [mmmm] increases. Further, triad fractions [mm], [rr] and [mr] described later are also calculated by the above method.
[0065]
　The 13 C-NMR spectrum can be measured by the following apparatus and conditions according to the attribution of peaks proposed in “Macromolecules, 8, 687 (1975)” by A. Zambelli and others. it can.
[0066]
Apparatus: JNM-EX400 type 13 C-NMR apparatus manufactured by JEOL Ltd.
Method: Proton complete decoupling method
concentration: 220 mg/ml
solvent: 1,2,4-trichlorobenzene and heavy benzene 90:10 (volume ratio) Mixed solvent
temperature: 130°C
pulse width: 45°
pulse repetition time: 4 seconds
integration: 10000 times
[0067]
[Calculation Formula]
M=m/S×100
R=γ/S×100
S=Pββ+Pαβ+Pαγ
S: Signal intensity of side chain methyl carbon atoms of all propylene units
Pββ: 19.8 ppm or more and 22.5 ppm or less
Pαβ: 18.0 ppm
Or more and 17.5 ppm or less Pαγ: 17.5 ppm or more and 17.1 ppm or less
γ: racemic
pentad chain: 20.7 ppm or more and 20.3 ppm or less m: mesopentad chain: 21.7 ppm or more and 22.5 ppm or less
[0068]
The value of (b) [rrrr]/(1-[mmmm])≦0.1
　[rrrr]/[1-mmmm] is obtained from the above-mentioned fraction of the pentad unit, and propylene in the polymer (II) is obtained. It is an index showing the uniformity of the regular distribution of the constituent units from which it is derived. When this value becomes large, it becomes a mixture of highly ordered polypropylene and atactic polypropylene like conventional polypropylene produced by using an existing catalyst system, which causes stickiness.
　In the polymer (II), when [rrrr]/(1-[mmmm]) is 0.1 or less, stickiness in the obtained spunbonded nonwoven fabric is suppressed. From such a viewpoint, [rrrr]/(1-[mmmm]) is preferably 0.05 or less, and more preferably 0.04 or less. The lower limit of [rrrr]/(1-[mmmm]) is 0.01.
[0069]
(C) [rmrm]>2.5 mol% When
　the racemic meso-racemic meso fraction [rmrm] of the polymer (II) is more than 2.5 mol%, the randomness of the polymer (II) And the elastic recovery of the spunbonded non-woven fabric is further improved. [Rmrm] is preferably 2.6 mol% or more, and more preferably 2.7 mol% or more. The upper limit of the racemic meso racemic meso fraction [rmrm] of the polymer (II) is usually about 10 mol %.
[0070]
-(D) [mm] x [rr]/[mr] 2 ≤ 2.0
　[mm] x [rr]/[mr] 2 indicates an index of randomness of the polymer (II), and this value is When it is 2.0 or less, the elastic nonwoven fabric has a sufficient elastic recovery property and the stickiness is suppressed. [Mm]×[rr]/[mr] 2 has a higher randomness as it approaches 0.25. From the viewpoint of obtaining the sufficient elastic recovery property, [mm]×[rr]/[mr] 2 is preferably more than 0.25 and 1.8 or less, more preferably 0.5 or more and 1.5 or less. Is.
[0071]
-(E) Weight average molecular weight (Mw) = 10,000 or more and 200,000 or less In
　the polymer (II) which is a propylene homopolymer, when the weight average molecular weight is 10,000 or more, the polymer (II) Since the viscosity is not too low and is moderate, yarn breakage during production of the spunbond nonwoven fabric obtained from the composition is suppressed. When the weight average molecular weight is 200,000 or less, the viscosity of the polymer (II) is not too high, and the spinnability is improved.
　This weight average molecular weight is preferably 10,000 or more and 150,000 or less.
　The method for measuring the weight average molecular weight of the polymer (II) will be described later.
[0072]
-(F) Molecular weight distribution (Mw/Mn)<4 In the
　polymer (II), when the molecular weight distribution (Mw/Mn) is less than 4, the occurrence of stickiness in the obtained spunbonded nonwoven fabric is suppressed. This molecular weight distribution is preferably 1.5 or more and 3 or less.
　The weight average molecular weight (Mw) is a polystyrene equivalent weight average molecular weight measured by the gel permeation chromatography (GPC) method using the following apparatus and conditions. The molecular weight distribution (Mw/Mn) is a value calculated from the number average molecular weight (Mn) and the weight average molecular weight (Mw) measured in the same manner as the weight average molecular weight (Mw).
[0073]
[GPC measurement device]
Column: TOSO GMHHR-H(S)HT
detector: RI detector for liquid chromatogram WATERS 150C
[Measurement conditions]
Solvent: 1,2,4-trichlorobenzene
Measurement temperature: 145°C
Flow rate: 1. 0
ml /min Sample concentration: 2.2 mg/ml
Injection amount: 160 μl
Calibration curve: Universal Calibration
analysis program: HT-GPC (Ver.1.0)
[0074]
　The polymer (II) preferably further satisfies the following requirement (g).
(G) Melting point (Tm-D)=0° C. or more and 120° C. or less
　The melting point (Tm-D) of the polymer (II) is (g) using a differential scanning calorimeter (DSC), under a nitrogen atmosphere of −10. It is the melting point (Tm-D) defined as the peak top of the peak observed on the highest temperature side of the melting endothermic curve obtained by holding at 5°C for 5 minutes and then raising the temperature at 10°C/minute.
　When the melting point (Tm-D) of the polymer (II) is 0°C or higher, the occurrence of stickiness in the spunbonded nonwoven fabric formed by the composition is suppressed, and when it is 120°C or lower, sufficient elastic recovery is achieved. can get. From such a viewpoint, the melting point (Tm-D) is more preferably 0° C. or higher and 100° C. or lower, and further preferably 30° C. or higher and 100° C. or lower.
[0075]
　The melting point (Tm-D) was measured by using a differential scanning calorimeter (DSC-7 manufactured by Perkin-Elmer Co., Ltd.) and holding 10 mg of the sample at −10° C. for 5 minutes in a nitrogen atmosphere, and then at 10° C./minute. It can be determined as the peak top of the peak observed on the highest temperature side of the melting endothermic curve obtained by raising the temperature at.
[0076]
　The polymer (II) has a melt flow rate (MFR, measurement condition: 230° C., load 2160 g) measured by a method according to ASTM D 1238, from the viewpoint of obtaining good spinnability and excellent stretchability, Usually, it is preferably in the range of 1 g/10 minutes or more and 100 g/10 minutes or less, more preferably in the range of 5 g/10 minutes or more and 100 g/10 minutes or less, and 30 g/10 minutes or more and 70 g/10 minutes or less It is more preferable that it is in the range.
[0077]
　The polymer (II) can be synthesized, for example, by using a homogeneous catalyst called a so-called metallocene catalyst as described in WO 2003/087172.
[0078]
[Additives] The
　composition is an optional component as long as the object of the present embodiment is not impaired. Various known additives such as pigments, natural oils, synthetic oils, waxes and fatty acid amides may be included.
[0079]
(Fatty acid amide) As
　described above, the composition preferably contains a fatty acid amide having 15 or more and 22 or less carbon atoms.
　When the composition contains a fatty acid amide, the fatty acid amide is adsorbed on the fiber surface of the spunbonded nonwoven fabric formed by the composition, and the fiber surface is modified to further improve flexibility, touch, blocking resistance and the like. .. As a result, it is considered that the non-woven fabric fibers are more effectively suppressed from adhering to members such as various rotating devices in the device used for embossing and the like.
[0080]
　Examples of the fatty acid amide having 15 to 22 carbon atoms include a fatty acid monoamide compound, a fatty acid diamide compound, a saturated fatty acid monoamide compound, and an unsaturated fatty acid diamide compound.
　The carbon number of the fatty acid amide in the present specification means the total number of carbon atoms contained in the molecule, and the carbon number in —CONH constituting the amide is also included in the carbon number. The carbon number of the fatty acid amide is more preferably 18 or more and 22 or less.
[0081]
　Specific examples of the fatty acid amide include palmitic acid amide (having 16 carbon atoms), stearic acid amide (having 18 carbon atoms), oleic acid amide (having 18 carbon atoms), and erucic acid amide (having 22 carbon atoms).
　Only one kind of fatty acid amide may be used in the composition, or two or more kinds thereof may be used in the composition.
　The preferable range of the content of the fatty acid amide with respect to the total amount of the composition is as described above.
[0082]

　The spunbonded nonwoven fabric of the present embodiment can be manufactured by an ordinary method using one kind or two or more kinds of the composition described above.
　Specifically, the spunbonded nonwoven fabric of this embodiment is preferably manufactured by the method for manufacturing a spunbonded nonwoven fabric of this embodiment described below.
　The method for producing the spunbonded nonwoven fabric of the present embodiment comprises a filtration step of melting polyethylene at 180° C. or higher and 200° C. or lower, and passing the melted polyethylene through a sieve having a mesh size of 65 μm or less heated to 180° C. or higher and 200° C. or lower. A mixing step of obtaining a composition by mixing polyethylene that has passed through a screen in the filtration step, a propylene homopolymer having a melting point of 140° C. or higher, and a specific polymer, and a span from the composition obtained in the mixing step. And a non-woven fabric forming step of obtaining a non-woven fabric by the bonding method, and the number of particles having a diameter of 0.2 mm or less contained in the membrane formed of polyethylene that has passed through the filtration step is 25 particles/g or less. A method for producing a spunbond nonwoven fabric.
　Hereinafter, each step will be described.
[0083]
[Filtration Step] In the
　filtration step, polyethylene is melted at 180° C. or higher and 200° C. or lower, and the melted polyethylene is passed through a sieve having an opening of 65 μm or less.
　When the melting temperature of polyethylene is 180° C. or higher, the clogging of the screen is unlikely to occur and the filtration process is stably performed. Moreover, when the melting temperature of polyethylene is 200° C. or lower, deterioration of polyethylene is suppressed, and a spunbonded nonwoven fabric having excellent stretchability can be obtained. For the same reason, the melting temperature of polyethylene is preferably 185° C. or higher and 195° C. or lower.
[0084]
　In this step, a sieve having an opening of 65 μm or less is used. From the viewpoint of obtaining a spunbonded nonwoven fabric having more excellent extensibility, the sieve is preferably 62 μm or less, more preferably 59 μm or less.
　Further, the sieve preferably has an opening of 30 μm or more, more preferably 40 μm or more, from the viewpoint of efficiency of the filtration step.
　By filtering the molten polyethylene with a sieve having an opening of 65 μm or less heated to the above temperature, the length of the island phase in the fibers constituting the spunbonded nonwoven fabric is shortened, and the average length of the island phase is 500 μm or less. To be achieved.
[0085]
　The sieve used in this step is preferably heated before coming into contact with the molten polyethylene.
　Specifically, the sieve is more preferably heated to 100° C. or higher and 300° C. or lower, and more preferably 150° C. or higher and 220° C. or lower.
　Heating the sieve tends to prevent clogging of the sieve.
[0086]
　The sieve used in this step is not limited as long as it has an opening of 65 μm or less, but is preferably made of metal (for example, stainless steel) so as to withstand heating.
[0087]
　The polyethylene that has passed through the screen in this step satisfies the following physical properties.
　That is, the number of particles having a diameter of 0.2 mm or less contained in a film formed of polyethylene that has passed through a sieve is 25 particles/g or less, preferably 20 particles/g or less, and 15 particles/g or less. Is more preferable.
　Hereinafter, "particles having a diameter of 0.2 mm or less" contained in the film formed of polyethylene will be referred to as "small particles".
　When the number of small particles is 25 particles/g or less, the length of the island phase in the fibers constituting the obtained spunbonded nonwoven fabric becomes short, and the extensibility can be improved.
[0088]
　Further, the number of particles having a diameter of more than 2 mm contained in the membrane formed of polyethylene that has passed through a sieve is preferably 10 particles/g or less, more preferably 5 particles/g or less, and 1 particle/g. It is even more preferably g or less.
　Hereinafter, “particles having a diameter of more than 2 mm” contained in the film formed of polyethylene are referred to as “large particles”.
　When the number of large particles is 10 particles/g or less, yarn breakage during spinning is easily suppressed, spinnability is excellent, and productivity can be improved.
[0089]
　The number of particles contained in the film made of polyethylene is determined as follows.
　That is, the polyethylene that has passed through the screen in this step is melt-kneaded at 280° C. for 30 minutes by an extruder and extrusion molded from a T die at 280° C. to obtain a film having a thickness of 55 μm.
　The obtained film is cut into 100 cm×25 cm, weighed and used as a measurement sample. Three pieces of measurement sample are collected.
　The surface of each of the three pieces of the obtained measurement sample is visually observed, the diameter of the found particle is observed and confirmed with an optical microscope, the diameter of the particle contained in the measurement sample is measured, and the large particle or the small particle is measured. Count the number of particles classified into particles. The total number of large particles or small particles obtained from 3 pieces of the measurement sample is divided by the total weight of the 3 pieces of the measurement sample to obtain the number of large particles or small particles per 1 g of the measurement sample.
[0090]
[Mixing Step] In the
　mixing step, a composition is obtained by mixing the polyethylene that has passed through the sieve in the filtering step, the propylene homopolymer having a melting point of 140° C. or higher, and the specific polymer.
　In addition, components other than polyethylene used in this step, that is, a propylene homopolymer having a melting point of 140° C. or higher, a specific polymer, and an additive (optional components such as fatty acid amide having 15 to 22 carbon atoms) are It may be in a molten state or a solid.
　This step may be performed in the extruder used in the nonwoven fabric forming step.
[0091]
　The content of polyethylene used in this step is preferably 1.0% by mass or more and 15.0% by mass or less with respect to the total amount of the composition.
　Further, the content of the specific polymer used in this step is preferably 5% by mass or more and 30% by mass or less with respect to the total amount of the composition.
　Further, the content of the propylene homopolymer having a melting point of 140° C. or higher used in this step is preferably 55.0% by mass or more and 90.0% by mass or less with respect to the total amount of the composition.
[0092]
　Furthermore, this step is preferably a step of further mixing a fatty acid amide having 15 to 22 carbon atoms to obtain a composition.
　That is, in this step, a composition obtained by mixing polyethylene that has passed through the screen in the filtration step, a propylene homopolymer having a melting point of 140° C. or higher, a specific polymer, and a fatty acid amide having 15 to 22 carbon atoms is prepared. Is preferably obtained.
　Then, the content of the fatty acid amide having 15 or more and 22 or less carbon atoms used in this step is preferably 0.1% by mass or more and 5.0% by mass or less with respect to the total amount of the composition.
[0093]
[Nonwoven fabric forming step] In the
　nonwoven fabric forming step, a nonwoven fabric is obtained from the composition obtained in the mixing step by a spunbond method.
　In this step, for example, a nonwoven fabric is obtained by the following method.
　That is, the composition obtained in the mixing step is melted by using an extruder, and the melted composition is melt-spun by using a spunbond nonwoven fabric molding machine having a plurality of spinnerets, and a long fiber formed by spinning. This is a method in which the fibers are cooled if necessary, then deposited on the collecting surface of a spunbond nonwoven fabric molding machine, and heated and pressed by an embossing roll.
[0094]
　The melting temperature of the composition is not particularly limited as long as it is equal to or higher than the softening temperature or melting temperature of the composition used for spinning and lower than the thermal decomposition temperature, and may be appropriately determined depending on the physical properties of the composition used and the like.
　The temperature of the spinneret depends on the composition used, but since the composition used in this step is a composition containing a large amount of the propylene-containing polymer, it is preferably 180° C. or higher and 240° C. or lower, and 190° C. The temperature is more preferably 230°C or lower and more preferably 200°C or higher and 225°C or lower.
[0095]
　When cooling the spun long fibers, it is preferable to use a method of applying cooling air to the long fibers so that the long fibers are drawn while being cooled.
　The temperature of the cooling air for cooling the spun long fibers is not particularly limited as long as it is the temperature at which the composition solidifies. Generally, the temperature of the cooling air is preferably 5°C or higher and 50°C or lower, more preferably 10°C or higher and 40°C or lower, and further preferably 15°C or higher and 30°C or lower.
　When the spun long fibers are stretched with cooling air, the air velocity of the cooling air is usually 100 m/min or more and 10,000 m/min or less, preferably 500 m/min or more and 10,000 m/min or less.
[0096]
　Hereinafter, the nonwoven fabric forming step will be described in detail with reference to the drawings.
　FIG. 2 is a schematic view of a closed-type spunbond method produced by drawing melt-spun long fibers while cooling in a closed space using a composition that is a raw material for a nonwoven fabric.
[0097]
　The spunbond method shown in FIG. 2 is performed by a closed-type spunbond nonwoven fabric manufacturing apparatus having a closed space (closed cooling chamber 13). Specifically, in the closed type spunbond method shown in FIG. 2, first, the composition discharged from the spinneret 11 passes through the throat 12 of the closed type spunbonded nonwoven fabric manufacturing apparatus, and enters the closed cooling chamber 13. And cooled to form long fibers 18. The spunbonded nonwoven fabric 21 is formed by the formed long fibers 18 reaching the collecting device 20 and accumulating.
　Cooling air is supplied into the cooling chamber 13 from a blower 15 having a looper 14 through a filter 17. The amount of cooling air supplied to the cooling chamber 13 is adjusted by opening and closing the blower 15, a switching valve 19 for adjusting the cooling air sent to the blower 15, and a damper 16.
[0098]
　This step has been described by taking the closed spun bond method as an example, but the present step is not limited to the closed spun bond method and may be, for example, an open spun bond method of cooling in an open space.
[0099]
　A part of the fibers of the spunbonded nonwoven fabric obtained in this step may be heat-sealed. Further, the fibers of the spunbonded nonwoven fabric obtained in this step may be pressed and solidified using a nip roll before heat-sealing.
[0100]
　As described above, the spunbonded nonwoven fabric of the present embodiment can be obtained through the filtration process, the mixing process, and the nonwoven fabric formation process.
[0101]
[Nonwoven fabric laminate]
　The spunbonded nonwoven fabric of the present embodiment may be used alone, or may be a nonwoven fabric laminate obtained by laminating the spunbonded nonwoven fabric of the present embodiment and other layers according to the purpose.
　When a nonwoven fabric laminate is formed using the spunbonded nonwoven fabric of the present embodiment, the layers other than the spunbonded nonwoven fabric of the present embodiment may be one layer or may have two or more layers. ..
[0102]
　Specific examples of layers other than the spunbonded nonwoven fabric of the present embodiment include knitted fabrics, woven fabrics, nonwoven fabrics other than the spunbonded nonwoven fabric of the present embodiment, films, and the like.
　The method of further laminating (bonding) another layer to the spunbonded nonwoven fabric of the present embodiment is not particularly limited, and a heat fusion method such as heat embossing or ultrasonic fusion, a machine such as needle punch or water jet. Various methods such as a mechanical entanglement method, a method using an adhesive such as a hot-melt adhesive, a urethane-based adhesive, and extrusion lamination can be adopted.
[0103]
　Other non-woven fabrics that can be laminated with the spun bond non-woven fabric of the present embodiment to form a non-woven fabric laminate, spun bond non-woven fabrics other than the spun bond non-woven fabric of the present embodiment, melt blown non-woven fabric, wet non-woven fabric, dry non-woven fabric, dry pulp non-woven fabric, Various known non-woven fabrics such as flash-spun non-woven fabrics and opened non-woven fabrics can be used.
　These nonwoven fabrics may be stretchable nonwoven fabrics or non-stretchable nonwoven fabrics.
　Here, the non-stretchable non-woven fabric is stretched in MD (that is, the flow direction of the non-woven fabric, the longitudinal direction) or CD (that is, the direction perpendicular to the flow direction of the non-woven fabric (or the MD direction, the transverse direction), and then the return stress is applied. What does not occur.
[0104]
　As a film that can be laminated with the spunbonded nonwoven fabric of the present embodiment to form a nonwoven fabric laminate, a breathable film, a moisture permeable film, or the like is preferable when the nonwoven fabric laminate requires air permeability.
　As the breathable film, a polyurethane elastomer having moisture permeability, a polyester elastomer, a film made of a thermoplastic elastomer such as a polyamide elastomer, a film made of a thermoplastic resin containing inorganic fine particles or organic fine particles is stretched to be porous. Various well-known breathable films such as a porous film made of
　The thermoplastic resin used for the porous film is preferably a polyolefin such as high-pressure low-density polyethylene, linear low-density polyethylene (so-called LLDPE), high-density polyethylene, polypropylene, polypropylene random copolymer, or a combination thereof.
　When the nonwoven fabric laminate does not require air permeability, a film made of one or more thermoplastic resins selected from polyethylene, polypropylene and the like can be used.
[0105]
　Examples of the heat-sealing method for heat-sealing a part of the nonwoven fabric laminate include various known methods, for example, a method using means such as ultrasonic waves, heat embossing using an embossing roll, or hot air through. Be done.
　Of these, hot embossing is preferable because the long fibers are efficiently stretched when the nonwoven fabric laminate is stretched.
[0106]
　When a part of the nonwoven fabric laminate is heat-sealed by hot embossing, the embossed area ratio is usually 5% or more and 30% or less, preferably 5% or more and 20% or less, and the non-embossed unit area is 0.5 mm 2 or more. , And preferably in the range of 4 mm 2 or more and 40 mm 2 or less.
　The non-embossing unit area is the maximum area of ​​a quadrangle inscribed in the embossing in the minimum unit non-embossing portion surrounded by embossing portions on all sides. The engraved shape of the embossed portion is exemplified by a circle, an ellipse, an ellipse, a square, a rhombus, a rectangle, a rectangle, or a continuous shape based on these shapes.
[0107]
　By stretching the obtained nonwoven fabric laminate, a stretchable nonwoven fabric laminate having elasticity can be obtained.
　The stretching method is not particularly limited, and a conventionally known method can be applied.
　The stretching method may be a partial stretching method or a total stretching method. Further, either a uniaxial stretching method or a biaxial stretching method may be used.
　Examples of the method of drawing in the machine direction (so-called MD direction) include a method of passing the partially fused mixed fibers through two or more nip rolls. At this time, the partially fused nonwoven fabric laminate can be stretched by increasing the rotation speed of the nip rolls in the order of the machine flow direction. Further, it is also possible to perform gear stretching processing using a gear stretching device.
[0108]
　The stretching ratio is preferably 50% or more, more preferably 100% or more, still more preferably 200% or more, and preferably 1000% or less, more preferably 400% or less.
[0109]
　In the case of uniaxial stretching, it is preferable that either the stretching ratio in the machine flow direction (so-called MD direction) or the direction perpendicular to this (so-called CD direction) satisfies the above stretching ratio. In the case of biaxial stretching, it is preferable that at least one of the machine direction (so-called MD direction) and the direction perpendicular to this (so-called CD direction) satisfies the above stretching ratio.
[0110]
　By performing the stretching process at such a draw ratio, the long fibers having elasticity in the spunbonded nonwoven fabric are drawn, and the long fibers having no drawability are plastically deformed and expanded according to the draw ratio.
　Similarly, in other laminated layers, the elastic layer is elastically deformed and the non-elastic layer is plastically deformed.
　When a non-woven fabric laminate is formed, a layer having elasticity and a layer having no elasticity are laminated and stretched, and when the stress is released, the layer having elasticity (long fibers constituting the layer) becomes elastic. The long fibers that have recovered and have no elasticity can be folded without elastic recovery, and the nonwoven fabric laminate can express a feeling of bulk. Since the plastically deformed long fibers become thin, the softness and feel are improved, and at the same time, the nonwoven fabric laminate can be imparted with a non-expansion function.
[0111]

　The sanitary material of the present embodiment includes the spunbonded nonwoven fabric of the present embodiment described above.
　The spunbonded nonwoven fabric of the present invention has excellent extensibility. Therefore, the spunbonded nonwoven fabric of this embodiment is suitably used as a sanitary material.
[0112]
　Examples of sanitary materials include absorbent articles such as paper diapers and sanitary napkins, bandages, medical gauze, medical sanitary materials such as towels, and sanitary masks.
　The sanitary material that can contain the spunbonded nonwoven fabric of the present embodiment is not limited thereto, and can be suitably used for any of various sanitary material applications that require extensibility and flexibility.
　The sanitary material may include the spunbonded nonwoven fabric of the present embodiment as a nonwoven fabric laminate including the spunbonded nonwoven fabric of the present embodiment and other layers.
Example
[0113]
　Hereinafter, the embodiments of the present invention will be described more specifically based on Examples, but the present invention is not limited to these Examples, which are one embodiment of the present invention.
　Physical property values ​​and the like in Examples and Comparative Examples were measured by the following methods.
[0114]
(1) Average length of island phase [μm]
　Fibers were taken out from a spunbonded nonwoven fabric and embedded in paraffin to prepare a measurement sample. Then, the measurement sample was placed on a microtome so that the blade was parallel to the long axis direction of the fiber, and sliced ​​along the long axis direction of the fiber. Then, after carbon reinforcement to the fiber obtained by slicing, about the cross section, about the cross section of the fiber obtained by slicing, it is observed using a transmission electron microscope (TEM: Transmission Electron Microscope), The length of 100 island phases was measured and the average length was calculated.
　Here, as the transmission electron microscope, a transmission electron microscope model: H-7650 manufactured by Hitachi High-Tech Co., Ltd. was used, and the observation magnification was 8000 times.
[0115]
(2) 　Ten test pieces having a unit weight [g/m 2 ]
spunbond nonwoven of 300 mm in the machine direction (MD) and 250 mm in the transverse direction (CD) were collected. It should be noted that the sampling points were arbitrarily set at 10 points. Next, the mass (g) of each of the collected test pieces was measured using a precision electronic balance (manufactured by Kensei Kogyo Co., Ltd.). The average value of the mass of each test piece was calculated. The obtained average value was converted into mass (g) per 1 m 2 , and the first decimal place was rounded off to obtain a basis weight [g/m 2 ] of the spunbond nonwoven fabric .
[0116]
(3) Maximum elongation [%] and maximum strength [N/50 mm] From
　spunbonded nonwoven fabric, in accordance with JIS L 1906, 6.12.1 [Method A], the maximum elongation and maximum are as follows. The strength was measured.
　A test of 25 cm in the flow direction (so-called MD direction) and 5 cm in the lateral direction (so-called CD direction) in a temperature-controlled room at a temperature of 20±2° C. and a humidity of 65±2% as specified in JIS Z 8703 (standard condition of test site). Five pieces were collected. The obtained test piece was subjected to a tensile test using a tensile tester (manufactured by Instron Japan Company Limited, Instron 5564 type) under conditions of a chuck distance of 100 mm and a pulling speed of 300 mm/min. The tensile load was measured, and the average value of the maximum values ​​was defined as the maximum strength [N/50 mm].
　In addition, the elongation at maximum strength was defined as the maximum elongation [%].
[0117]
(4) Evaluation of heat-sealing property
[Heat-sealing method]
　Ten test pieces having a flow direction (so-called MD direction) of 100 mm and a transverse direction (so-called CD direction) of 100 mm were sampled from a spunbonded nonwoven fabric. Then, two test pieces are superposed so that the MD direction is the same, and a heat seal tester (product name: heat seal tester) manufactured by Tester Sangyo Co., Ltd. is used, and heat sealed under the following conditions. went.
　Seal bar width: 10.0 mm
　Seal pressure: 2.0 kg/cm 2
　Seal time: 1.0 sec
　Seal temperature: Set upper bar and lower bar at the same temperature (145° C. or 155° C.)
　Seal direction: Vertical with MD direction
[0118]
[Confirmation of heat-sealing strength] Using a
　constant-speed tensile tester (manufactured by Toyo Seiki Co., Ltd., product name: Strograph), a tensile peel test of a test piece heat-sealed under the above conditions was conducted under the following conditions. 5 pieces each, and the presence or absence of peeling was confirmed, and when there was no peeling, it was evaluated as “having heat sealability”.
　Test piece shape: Width 20 mm, length 50 mm
　Tensile speed: 30 mm/min
　Atmosphere temperature during measurement: 23°C
[0119]
(5) Embossing residual rate [%] From the
　spunbonded nonwoven fabric, one test piece having a flow direction (so-called MD direction) of 250 mm and a transverse direction (so-called CD direction) of 200 mm was taken. The obtained test piece was inserted so that the roll rotation direction of the gear stretching device (that is, gear processing machine) as shown in FIG. 3 and the CD direction of the test piece were aligned, and the gear was moved in the MD direction (that is, the flow direction of the nonwoven fabric). A stretched spunbond nonwoven fabric was obtained. The gear rolls mounted on the gear processing machine each had a diameter of 200 mm and a gear pitch of 2.5 mm, and the engagement depth of both rolls was adjusted to be 5.5 mm.
　With respect to the spunbonded non-woven fabric gear-stretched as described above, the morphology was observed by SEM, and the residual rate of embossing after gear-stretching was evaluated. The higher the remaining rate of embossing, the better the feel. The emboss residual rate was calculated using the following formula.
　Remaining emboss rate = (number of unembossed embosses/number of observed embosses) x 100
　Note that, by observing the embossed portion of the gear-stretched spunbonded nonwoven fabric by SEM, perforation at the embossed portion, detachment of fibers, Also, the embossed portion in which neither the embossed portion nor the fiber breakage at the boundary thereof was confirmed was defined as "unbroken embossing".
　The remaining rate of the emboss formed by the stretching process using a gear processing machine is good, and the fiber breakage of the spunbonded nonwoven fabric at the embossed part and its boundary during the stretching process and the breaking of the nonwoven fabric due to the fiber breakage do not occur. Thus, it can be confirmed that the stretchability of the spunbonded nonwoven fabric is good.
[0120]
(6) Softness evaluation With
　respect to the spunbonded nonwoven fabric, a sensory evaluation of the feel (touch) when touched directly with a hand was performed, and evaluation was performed based on the following criteria. Sensory evaluation was performed by 10 monitors, and the evaluation result with the most answers was adopted.
　In addition, when there were multiple evaluation results with the most answers, the superior result was adopted. 　-Evaluation
Criteria-
A: The touch was very good and the flexibility was excellent.
　B: The touch was good, and the flexibility was excellent as compared with the following C evaluation.
　C: Hard to the touch and poor in flexibility.
[0121]
[Example 1]

-Filtration step-
　First, MFR (measured in accordance with ASTM D 1238 at a temperature of 190°C and a load of 2.16 kg) 5 g/10 minutes and a density of 0.95 g/cm. 3. High-density polyethylene having a melting point of 134°C was heated to 190°C and melted.
　Then, in the molten state, it was filtered through a metal sieve (opening 58 μm) heated to 190° C.
[0122]
　The number of small particles and large particles contained in the film formed of polyethylene that passed through the screen in the above filtration step was determined by the method described above.
　The results are shown in Table 1.
[0123]
- mixing step -
　in the filtration step, a polyethylene 7% by weight passing through a sieve, (in conformity with ASTM D 1238, the temperature 230 ° C., measured under a load 2.16kg) MFR 60g / 10 min, density 0.91g /Cm 3 , 72.7% by mass of a propylene homopolymer having a melting point of 160°C, MFR (measured in accordance with ASTM D 1238 at a temperature of 230°C and a load of 2.16 kg) 60 g/10 minutes, a density of 0.91 g/ cm 3 and a melting point of 142° C., a propylene random copolymer (copolymer of propylene and ethylene, polymerization molar ratio 97:3, polymer (I)) 20 mass %, and erucic acid amide 0.3 mass %. Were mixed to obtain a composition.
[0124]
- nonwoven forming step -
　a composition obtained in the mixing step was melted using an extruder of 75Mmfai, spunbonded nonwoven fabric manufacturing apparatus having a spinneret hole number 2557 holes (into sealable spunbond method shown in FIG. 2 Using the apparatus used, the length in the direction perpendicular to the machine flow direction on the collecting surface: 800 mm), the melting temperature of the composition and the die temperature are both 220° C., the cooling air temperature is 20° C., the drawing air air speed is 5233 m/ Melt spinning was performed by the closed spun bond method under the condition of minutes.
　The spun filaments are deposited on the collecting surface and subjected to a heat and pressure treatment with an embossing roll (embossing area ratio (thermo-compression ratio) 18%, embossing temperature 116° C.) to give a total basis weight of 18 g/m 2 . A spunbond nonwoven fabric was produced.
[0125]
　The obtained spunbonded nonwoven fabric of Example 1 was evaluated by the evaluation method described above.
　The results are shown in Table 1 below.
[0126]
[Example 2]
In
　the filtration step in the production of the spunbonded non-woven fabric of Example 1, except that a metal sieve having an opening of 64 μm was used instead of a metal sieve having an opening of 58 μm. In the same manner as in Example 1, polyethylene was filtered, and then the filtered polyethylene was used to obtain a composition, and subsequently a spunbond nonwoven fabric was produced.
[0127]
　The obtained spunbonded nonwoven fabric of Example 2 was evaluated by the evaluation method described above.
　The results are shown in Table 1 below.
[0128]
Example 3
A stainless steel reactor having
　an internal volume of 0.2 m 3 equipped with a stirrer was charged with 20 L/h of n-heptane, 15 mmol/h of triisobutylaluminum, and dimethyl. Anilinium tetrakispentafluorophenyl borate and (1,2′-dimethylsilylene)(2,1′-dimethylsilylene)-bis(3-trimethylsilylmethylindenyl)zirconium dichloride were previously contacted with triisobutylaluminum and propylene. The catalyst component thus obtained was continuously supplied at 6 μmol/h per zirconium.
　At a polymerization temperature of 70° C., propylene and hydrogen were continuously supplied while maintaining the gas phase hydrogen concentration at 8 mol% and the total pressure inside the reactor at 0.7 MPa·G.
　SUMILIZER GP (manufactured by Sumitomo Chemical Co., Ltd.) was added to the obtained polymerization solution to a concentration of 1000 ppm, and the solvent was removed to obtain a propylene polymer.
　The weight average molecular weight (Mw) of the obtained propylene polymer was 1.2×10 4 , and Mw/Mn=2. In addition, [mmmm] obtained from NMR measurement is 46 mol%, [rrrr]/(1-[mmmm]) is 0.038, [rmrm] is 2.7 mol%, and [mm]×[rr]/[ mr] 2 was 1.5.
　The low crystalline polypropylene (polymer (II)) obtained as described above is hereinafter referred to as “LMPP1”.
[0129]
In
　the mixing step in the production of the spunbonded nonwoven fabric of Example 1, MFR (measured according to ASTM D 1238 at a temperature of 230° C. and a load of 2.16 kg) 60 g/10 minutes and a density of 0. LMPP1 synthesized above instead of 20 mass% of propylene random copolymer (copolymer of propylene and ethylene, polymerization molar ratio 97:3, polymer (I)) having a melting point of 142° C. of 0.91 g/cm 3 . A composition was obtained in the same manner as in Example 1 except that 20% by mass was used, and then a spunbonded nonwoven fabric was produced.
[0130]
　The obtained spunbonded nonwoven fabric of Example 3 was evaluated by the evaluation method described above.
　The results are shown in Table 1 below.
[0131]
[Example 4]

　MFR (measured at a temperature of 230°C and a load of 2.16 kg according to ASTM D 1238) in the mixing step in the production of the spunbonded nonwoven fabric of Example 1 60 g/ Example except that the amount of propylene homopolymer having a density of 0.91 g/cm 3 and a melting point of 160° C. of 10 minutes was changed to 74.7% by mass, and the amount of polyethylene after filtration was changed to 5% by mass. A composition was obtained in the same manner as in 1, and subsequently a spunbonded nonwoven fabric was produced.
[0132]
　The obtained spunbonded nonwoven fabric of Example 4 was evaluated by the evaluation method described above.
　The results are shown in Table 1 below.
[0133]
[Comparative Example 1]
In
　the filtration step in the production of the spunbonded nonwoven fabric of Example 1, except that a metal sieve having an opening of 69 μm was used instead of the metal sieve having an opening of 58 μm. In the same manner as in Example 1, polyethylene was filtered, and then the filtered polyethylene was used to obtain a composition, and subsequently a spunbond nonwoven fabric was produced.
[0134]
　The obtained spunbonded nonwoven fabric of Comparative Example 1 was evaluated by the evaluation method described above.
　The results are shown in Table 1 below.
[0135]
[Comparative Example 2]
In
　the filtration step in the production of the spunbonded nonwoven fabric of Example 3, a metal sieve having an opening of 69 μm was used in place of the metal sieve having an opening of 58 μm. The polyethylene was filtered in the same manner as in Example 3, and then the filtered polyethylene was used to obtain a composition, and subsequently a spunbond nonwoven fabric was produced.
[0136]
　The obtained spunbonded nonwoven fabric of Comparative Example 2 was evaluated by the evaluation method described above.
　The results are shown in Table 1 below.
[0137]
[Comparative Example 3]
In
　the filtration step in the production of the spunbonded nonwoven fabric of Example 4, a metal sieve having an opening of 69 μm was used in place of the metal sieve having an opening of 58 μm. The polyethylene was filtered in the same manner as in Example 4, and then the composition was obtained using the filtered polyethylene, and subsequently, a spunbonded nonwoven fabric was produced.
[0138]
　The obtained spunbonded nonwoven fabric of Comparative Example 3 was evaluated by the evaluation method described above.
　The results are shown in Table 1 below.
[0139]
　Table 1 below shows the conditions in the filtration step, the numbers of small particles and large particles contained in the film formed of polyethylene that has passed through the filtration step, the amount of each component used in the mixing step, and the conditions in the non-woven fabric forming step. , And the measurement and evaluation results.
　In Table 1, "-" means that the corresponding component was not included.
[0140]
[table 1]

[0141]
　From the results in Table 1, it can be seen that the spunbonded nonwoven fabrics of this embodiment obtained in Examples 1 to 4 have excellent extensibility.
[0142]
　As shown in Table 1 above, the spunbonded nonwoven fabrics of Examples 1 to 4 all have excellent extensibility, good heat sealability, and good embossing residual rate. From this, it can be seen that the stretching suitability is excellent. Furthermore, it can be seen that the spunbonded nonwoven fabrics of Examples 1 to 4 are all excellent in flexibility.
　From these evaluation results, it can be seen that the spunbonded nonwoven fabric of the present embodiment is suitable for use in sanitary materials that require extensibility, flexibility, and processability.
[0143]
　The disclosure of Japanese Patent Application 2018-009762 filed January 24, 2018 is incorporated herein by reference in its entirety.
　All documents, patent applications, and technical standards mentioned herein are to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference. Incorporated herein by reference.
The scope of the claims
[Claim 1]
　From a composition containing a propylene homopolymer having a melting point of 140° C. or higher, polyethylene, and at least one polymer selected from the group consisting of the following polymers (I) and (II) consisting comprises fibers,
　the fibers have a sea-island structure, the average length of the island phase in a cross section along the longitudinal direction of the fibers is 1μm or more 500μm or less, spunbonded nonwoven fabric.
　(I) Random copolymer of propylene and at least one selected from ethylene and α-olefins having 4 to 20 carbon atoms
　(II) Melting point less than 120° C. satisfying the following (a) to (f): Of propylene homopolymer
(a) [mmmm]=20 mol% or more and 60 mol% or less
(b) [rrrr]/(1-[mmmm])≦0.1
(c) [rmrm]>2.5 mol%
(D) [mm]×[rr]/[mr] 2 ≦2.0
(e) Weight average molecular weight (Mw)=10,000 or more and 200,000 or less
(f) Molecular weight distribution (Mw/Mn)<4
( In a) to (d), [mmmm] is a mesopentad fraction, [rrrr] is a racemic pentad fraction, [rmrm] is a racemic mesoracemic mesopentad fraction, and [mm], [mm], rr] and [mr] are triad fractions, respectively.
[Claim 2]
　The spunbonded nonwoven fabric according to claim 1, wherein the content of the polyethylene is 1.0% by mass or more and 15.0% by mass or less with respect to the total amount of the composition.
[Claim 3]
　The content of at least one polymer selected from the group consisting of the polymer represented by (I) and the polymer represented by (II) is 5.0% by mass or more and 30.0% with respect to the total amount of the composition. The spunbonded non-woven fabric according to claim 1 or 2, which has a mass% or less.
[Claim 4]
　4. The content of the propylene homopolymer having a melting point of 140° C. or higher is 55.0% by mass or more and 90.0% by mass or less with respect to the total amount of the composition. The spunbonded non-woven fabric according to.
[Claim 5]
　Density of the polyethylene, 0.941 g / cm 3 or more 0.970 g / cm 3 in the following range, spunbonded nonwoven fabric according to any one of claims 1 to 4.
[Claim 6]
　The composition contains a fatty acid amide having 15 to 22 carbon atoms, and the content of the fatty acid amide having 15 to 22 carbon atoms is 0.1% by mass or more and 5.0% by mass or less with respect to the total amount of the composition. The spunbonded nonwoven fabric according to any one of claims 1 to 5, which is as follows.
[Claim 7]
　7. The span according to claim 1, wherein the polymer represented by (I) is a random copolymer containing at least a constitutional unit derived from propylene and a constitutional unit derived from ethylene. Bonded non-woven fabric.
[Claim 8]
　A sanitary material comprising the spunbonded nonwoven fabric according to any one of claims 1 to 7.
[Claim 9]
　Polyethylene was melted at 180 ° C. or higher 200 ° C. or less, molten passing the polyethylene mesh 65μm following sieve filtration step and,
　the polyethylene through the sieve at the filtration step, melting point 140 ° C. or more propylene homopolymer and polymer, a mixing step of obtaining at least one polymerization and body, are mixed with the composition is selected from the group consisting of polymers shown in the polymer and (II) below are shown below (I),
　the mixing step , a non-woven fabric formation step of obtaining a nonwoven fabric by spun bond method from the resulting the composition
comprises, included 0.2mm diameter is below the film formed by the polyethylene having passed through the sieve at the filtering step The method for producing a spunbonded nonwoven fabric, wherein the number of particles is 25/g or less.
　(I) Random copolymer of propylene and at least one selected from ethylene and α-olefins having 4 to 20 carbon atoms
　(II) Melting point less than 120° C. satisfying the following (a) to (f): Of propylene homopolymer
(a) [mmmm]=20 mol% or more and 60 mol% or less
(b) [rrrr]/(1-[mmmm])≦0.1
(c) [rmrm]>2.5 mol%
(D) [mm]×[rr]/[mr] 2 ≦2.0
(e) Weight average molecular weight (Mw)=10,000 or more and 200,000 or less
(f) Molecular weight distribution (Mw/Mn)<4
In (a) to (d), [mmmm] is a mesopentad fraction, [rrrr] is a racemic pentad fraction, [rmrm] is a racemic mesoracemic mesopentad fraction, and [mm] is [Rr] and [mr] are triad fractions, respectively.
[Claim 10]
　The method for producing a spunbonded nonwoven fabric according to claim 9, wherein the content of the polyethylene used in the mixing step is 1.0% by mass or more and 15.0% by mass or less with respect to the total amount of the composition.
[Claim 11]
　The content of at least one polymer selected from the group consisting of the polymer shown in (I) and the polymer shown in (II) used in the mixing step is 5% by mass or more based on the total amount of the composition. The method for producing a spunbonded nonwoven fabric according to claim 9 or 10, wherein the content is 30% by mass or less.
[Claim 12]
　The content of the propylene homopolymer having a melting point of 140° C. or higher used in the mixing step is 55.0% by mass or more and 90.0% by mass or less with respect to the total amount of the composition. The method for producing the spunbonded nonwoven fabric according to any one of 1.
[Claim 13]
　The mixing step is a step of further mixing a fatty acid amide having 15 to 22 carbon atoms to obtain a composition, and the content of the fatty acid amide having 15 to 22 carbon atoms relative to the total amount of the composition. The method for producing a spunbonded nonwoven fabric according to any one of claims 9 to 12, wherein the content is 0.1% by mass or more and 5.0% by mass or less.