JP2022154452A - Spun-bonded nonwoven fabric - Google Patents

Abstract

To provide a spun-bonded nonwoven fabric capable of achieving both strength and flexibility.SOLUTION: A spun-bonded nonwoven fabric contains composite fibers including an area A containing propylene/α-olefin random copolymers and an area B containing ethylene-based polymers. The composite fiber is of a side-by-side type or an eccentric core-sheath type. The ratio between the area A and the area B is 70:30 to 10:90 on a mass basis. The area B has a density of 0.900 kg/m3 to 0.945 kg/m3.SELECTED DRAWING: Figure 1

Description

The present invention relates to spunbond nonwoven fabrics.

In recent years, nonwoven fabrics have been used for various disposable articles including sanitary materials such as diapers and napkins.

As nonwoven fabrics, in addition to nonwoven fabrics made of fibers formed from a single component, nonwoven fabrics made of so-called conjugate fibers, which are fibers having a plurality of regions formed from different resins in one fiber, are known.

As a nonwoven fabric used for sanitary materials, for example, Patent Document 1 discloses a bulky composite length made of 1 polypropylene resin as the first component and 1 polyethylene resin or 2 polyethylene resin mixture as the second component. A fibrous nonwoven is described. This composite filament nonwoven fabric can be suitably used for sanitary materials, and is said to have cushioning softness, bending softness, and barrier properties.

JP 2018-145544 A

As a result of studies by the inventors, it has been found that the composite long fiber nonwoven fabric described in Patent Document 1 may not have sufficient strength and flexibility at the same time.

An object of the present disclosure is to provide a spunbond nonwoven fabric that can achieve both strength and flexibility.

The present disclosure relates to the following aspects.
<1> A spunbond nonwoven fabric containing composite fibers containing a region A containing a propylene/α-olefin random copolymer and a region B containing an ethylene polymer,
The composite fiber is a side-by-side type or an eccentric core-sheath type,
The ratio of the region A to the region B is 70:30 to 10:90 on a mass basis,
The spunbond nonwoven fabric, wherein the region B has a density of 0.900 kg/m ³ to 0.945 kg/m ³ .
<2> The spunbond nonwoven fabric according to <1>, wherein the composite fiber has the region A exposed.
<3> The spunbond nonwoven fabric according to <1> or <2>, wherein the propylene/α-olefin random copolymer has a melting point of 155° C. or lower.
<4> The spunbond nonwoven fabric according to any one of <1> to <3>, wherein the region A further contains a propylene homopolymer.
<5> The spunbond nonwoven fabric according to any one of <1> to <4>, wherein the ethylene polymer comprises an ethylene/α-olefin copolymer.
<6> The ethylene-based polymer contains at least one selected from the group consisting of ethylene/1-butene copolymer and ethylene/4-methyl-1-pentene copolymer, <1> to <5 The spunbond nonwoven fabric according to any one of >.
<7> Any one of <1> to <6>, wherein the ethylene polymer has an MFR (ASTM D-1238, 190°C, 2.16 kg load) of 10 g/10 min to 100 g/10 min The spunbond nonwoven fabric according to 1.
<8> The spunbond nonwoven fabric according to any one of <1> to <7>, wherein the composite fibers have an average fiber diameter of 10 μm to 40 μm.
<9> The spunbond nonwoven fabric according to any one of <1> to <8>, which has a basis weight of 8 g/m ² to 30 g/m ² .
<10> The spunbond nonwoven fabric according to any one of <1> to <9>, wherein the composite fiber contains a hydrophilic agent.

According to the present disclosure, it is possible to provide a spunbond nonwoven fabric that achieves both strength and flexibility.

FIG. 1 is a schematic diagram showing an example of a cross section of a side-by-side composite fiber included in the spunbond nonwoven fabric of the present disclosure. FIG. 2 is a schematic diagram showing an example of a cross section of an eccentric sheath-core composite fiber included in the spunbond nonwoven fabric of the present disclosure.

Embodiments of the present disclosure will be described below. These descriptions and examples are illustrative of embodiments and do not limit the scope of embodiments.

In the present disclosure, a numerical range represented using "to" means a range including the numerical values described before and after "to" as lower and upper limits.
In the present disclosure, when there are multiple substances corresponding to each component in the composition, the amount of each component in the composition is the total amount of the multiple substances present in the composition unless otherwise specified. means.
In the numerical ranges described step by step in the present disclosure, the upper limit value or lower limit value described in one numerical range may be replaced with the upper limit value or lower limit value of another numerical range described step by step. . Moreover, in the numerical ranges described in the present disclosure, the upper or lower limits of the numerical ranges may be replaced with the values shown in the examples.
In the present disclosure, each component may contain multiple types of applicable substances. When referring to the amount of each component in the composition in the present disclosure, when there are multiple types of substances corresponding to each component in the composition, unless otherwise specified, the multiple types of substances present in the composition It means the total amount of substance.
In the present disclosure, MD (Machine Direction) refers to the traveling direction of a nonwoven web in a nonwoven fabric manufacturing apparatus. The CD (Cross Direction) direction refers to a direction perpendicular to the MD direction and parallel to the main surface (surface perpendicular to the thickness direction of the nonwoven fabric).

<<Nonwoven fabric>>
An example of a preferred embodiment of the nonwoven fabric of the present disclosure will be described.
The spunbond nonwoven fabric in the present disclosure is a spunbond nonwoven fabric containing composite fibers containing a region A containing a propylene/α-olefin random copolymer and a region B containing an ethylene polymer, and the composite fibers are side-by-side type. Alternatively, it is an eccentric core-sheath type, the ratio of area A to area B is 70:30 to 10:90 based on mass, and the density of area B is 0.900 to 0.945 kg/m ³ .

The nonwoven fabric of the present disclosure preferably has a basis weight of 8 g/m ² to 30 g/m ² , more preferably 10 g/m ² to 25 g/m ² . When the basis weight is within the above range, the strength and flexibility tend to be well balanced. The nonwoven fabric of the present disclosure preferably has a thickness of 0.05 mm to 2.00 mm, more preferably 0.10 mm to 1.00 mm.

The nonwoven fabric of the present disclosure may be a single-layer nonwoven fabric or a multi-layer nonwoven fabric (nonwoven multilayer structure) in which a plurality of layers are laminated. The nonwoven multilayer structure may be a nonwoven multilayer structure in which many nonwoven fabrics of the present disclosure are laminated, or may be a nonwoven multilayer structure in which the nonwoven fabric of the present disclosure and another nonwoven fabric are laminated. Other nonwoven fabrics include, for example, other spunbond nonwoven fabrics and meltblown nonwoven fabrics.

<Composite fiber>
The conjugate fiber in the present disclosure includes a region A described later and a region B described later, and is a side-by-side type or eccentric core-sheath type conjugate fiber. FIG. 1 shows a cross section of a side-by-side type composite fiber. In FIG. 1, the area A and the area B form the left side and the right side, respectively, and the boundary between the area A and the area B is substantially linear. The cross section of the side-by-side type conjugate fiber is not limited to this, and for example, the boundary between the regions A and B may be formed on the left or right.

FIG. 1 shows a cross section of a side-by-side type composite fiber. In FIG. 1, the area A and the area B form the left side and the right side, respectively, and the boundary between the area A and the area B is substantially linear. The cross section of the side-by-side type conjugate fiber is not limited to this, and for example, the boundary between the regions A and B may be formed on the left or right. Moreover, the left and right sides of the area A and the area B may be reversed.

The cross section of the eccentric core-sheath type conjugate fiber is shown in FIGS. 2(a) and 2(b). The eccentric core-sheath type conjugate fiber shown in FIG. In the eccentric core-sheath type conjugate fiber of FIG. 2(b), the core 3 is further to the left than the eccentric core-sheath type conjugate fiber of FIG. It is a mode. The core portion may be the region A described later or the region B described later. The sheath portion may be the region A described later or the region B described later. In the eccentric core-sheath type conjugate fiber, it is preferable that the region A is the core portion and the region B is the sheath portion, and more preferably the region A is the core portion and the region B is the exposed sheath portion.

It is preferable that the region A of the composite fiber is exposed. More specifically, the conjugate fiber is preferably a side-by-side type or an eccentric core-sheath type conjugate fiber in which the region A is exposed. Due to the above-described aspect, embossing tends to be applied appropriately, and thus the strength tends to be excellent.

The ratio of area A to area B in the composite fiber is 70:30 to 10:90 (area A:area B) on a mass basis. More preferably, this ratio is between 60:40 and 20:80. When the ratio of the region A to the region B in the conjugate fiber is within the above range, the balance between strength and flexibility tends to be excellent.

The average fiber diameter of the conjugate fiber is preferably 10 μm to 40 μm, more preferably 10 μm to 25 μm, even more preferably 12 μm to 20 μm. When the average fiber diameter of the conjugate fiber is within the above range, there is a tendency that the balance between strength and flexibility is excellent.

(Area A)
Region A contains a propylene/α-olefin random copolymer.

The content of structural units derived from propylene in the propylene/α-olefin random copolymer is 50% by mass or more and less than 100% by mass, preferably 70% by mass to 99% by mass, more preferably 80% by mass to 98% by mass. preferable. The content of structural units derived from α-olefin in the propylene/α-olefin random copolymer is more than 0% by mass and 50% by mass or less, preferably 1% by mass to 30% by mass or less, and 2% by mass to 20 mass % or less is more preferable. When the content of the propylene-derived structural unit and/or the α-olefin-derived structural unit in the propylene/α-olefin random copolymer is within the above range, the balance between strength and flexibility tends to be excellent.

The α-olefin in the propylene/α-olefin random copolymer is not particularly limited as long as it is an α-olefin other than propylene. Examples of α-olefins include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene and the like. Among these, ethylene is preferable as the α-olefin from the viewpoint of further improving flexibility.

The propylene/α-olefin random copolymer preferably has an MFR (ASTM D-1238, 230° C./2.16 kg load) of 10 g/10 min to 100 g/10 min, more preferably 15 g/10 min to 80 g/10 min. More preferably 10 minutes. When the MFR of the propylene/α-olefin random copolymer is within the above range, the balance between strength and flexibility tends to be excellent.

The propylene/α-olefin random copolymer preferably has a melting point of 155° C. or lower. When the region A contains only the propylene/α-olefin random copolymer as the resin component, the melting point of the propylene/α-olefin random copolymer is preferably 125°C to 155°C. When the melting point is within the above range, the balance between strength and flexibility tends to be excellent.

The content of the propylene/α-olefin random copolymer in region A is preferably 10% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, even more preferably 90% by mass to 100% by mass, and 99 % to 100% by weight is particularly preferred. When the content of the propylene/α-olefin random copolymer in the region A is within the above range, the balance between strength and flexibility tends to be excellent.

From the viewpoint of further improving strength, region A preferably further contains a propylene homopolymer or a plurality of types of propylene/α-olefin random copolymers. When region A contains a propylene homopolymer, the strength tends to be excellent.

The content of the propylene homopolymer in region A is preferably 1% by mass to 90% by mass, more preferably 50% by mass to 80% by mass. When the content of the propylene homopolymer in the region A is within the above range, the strength tends to be excellent. When the region A contains the propylene homopolymer within the above range, the content of the propylene/α-olefin random copolymer may be such that the total of the propylene homopolymer is 100% by mass.

The content of structural units derived from propylene in all resin components contained in region A is preferably 90% by mass to 99.5% by mass, more preferably 93% by mass to 99% by mass, and 95% by mass to 98% by mass. More preferred. When the content of structural units derived from propylene is within the above range, the balance between strength and flexibility tends to be excellent.

(Area B)
Region B contains an ethylene-based polymer. Region B has a density between 0.900 kg/m ³ and 0.945 kg/m ³ . The density of area B is preferably between 910 kg/m ³ and 940 kg/m ³ . When the density is within the above range, the balance between strength and flexibility tends to be excellent.

The content of structural units derived from ethylene in the ethylene-based polymer is 50% by mass or more, preferably 70% by mass to 99.8% by mass, more preferably 90% by mass to 99% by mass. The content of other structural units in the ethylene polymer is 0% by mass to 50% by mass or less, preferably 0.2% by mass to 30% by mass or less, more preferably 1% by mass to 10% by mass or less. When the content of structural units derived from ethylene and/or other structural units in the ethylene-based polymer is within the above range, the balance between strength and flexibility tends to be excellent.

Examples of monomers constituting other structural units include α-olefins. α-Olefins are not particularly limited as long as they are other than ethylene. , 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene and the like. Among these, 1-butene and 4-methyl-1-pentene are preferred as the α-olefin from the viewpoint of further improving the balance between strength and flexibility.

The ethylene-based polymer preferably contains an ethylene/α-olefin copolymer. The ethylene/α-olefin copolymer is preferably at least one selected from the group consisting of an ethylene/1-butene copolymer and an ethylene/4-methyl-1-pentene copolymer. When the ethylene-based polymer has the above aspect, it tends to have an excellent balance between strength and flexibility.

The ethylene polymer preferably has an MFR (ASTM D-1238, 190° C./2.16 kg load) of 10 g/10 min to 100 g/10 min, more preferably 15 g/10 min to 60 g/10 min. is more preferred. When the MFR of the ethylene-based polymer is within the above range, the balance between strength and flexibility tends to be excellent.

The density of region B is 0.900 kg/m ³ to 0.945 kg/m ³ , preferably 910 kg/m ³ to 940 kg/m ³ , more preferably 915 kg/m ³ to 940 kg/m ³ . When the density of the region B is within the above range, the strength and flexibility tend to be well balanced. The density of region B can be adjusted by changing the density of the resin forming region B. FIG.

The content of the ethylene-based polymer in region B is preferably 10% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, even more preferably 90% by mass to 100% by mass, and 99% by mass to 100% by mass. % is particularly preferred. When the content of the ethylene-based polymer in region B is within the above range, there is a tendency for the balance between strength and flexibility to be excellent.

(hydrophilic agent)
The conjugate fiber in the present disclosure preferably contains a hydrophilic agent. When the conjugate fibers of the present disclosure contain a hydrophilic agent, they tend to have improved hydrophilicity. The hydrophilic agent may be contained inside the conjugate fiber, or may be attached to the surface of the conjugate fiber. Hydrophilic agents can be further classified into penetrants and wetting agents. Nonwovens of the present disclosure may contain both a penetrant and a wetting agent, or may contain no penetrating agent and a wetting agent. From the viewpoint of excellent hydrophilicity, the hydrophilic agent preferably contains both a penetrating agent and a wetting agent.

The hydrophilic agent preferably contains at least one of a sulfonate and a sulfate as a penetrant. Sulfonates include alkylbenzenesulfonates, alkylnaphthalenesulfonates, α-olefinsulfonates, and alkylsulfosuccinates. These sulfonates are preferably alkali metal salts. Sulfate salts include higher alcohol sulfates, alkyl sulfates, and the like. These sulfate ester salts are preferably alkali metal salts. Among these, the hydrophilic agent preferably contains a sulfonate, more preferably an alkali metal salt of a sulfonic acid, as a penetrating agent.

The sulfonate used as the penetrant is preferably an alkyl sulfosuccinate from the viewpoint of stability in the step of applying a hydrophilic agent and hydrophilicity of the product. The alkylsulfosuccinate is preferably an alkali metal salt of dialkylsulfosuccinic acid, more preferably an alkali metal salt of dialkylsulfosuccinic acid having two alkyl groups having 8 to 16 carbon atoms. Alkali metal salts of dialkylsulfosuccinic acid include lithium salts thereof, sodium salts thereof, potassium salts thereof, etc., and sodium salts thereof are preferred. Specific examples of the alkali metal salt of dialkylsulfosuccinic acid having two alkyl groups having 8 to 16 carbon atoms include sodium dioctylsulfosuccinate, sodium di(2-ethylhexyl)sulfosuccinate, and didecyl. Sulfosuccinic acid sodium salt, didodecylsulfosuccinic acid sodium salt, ditetradecylsulfosuccinic acid lithium (Li) salt, dihexadecylsulfosuccinic acid potassium (K) salt and the like. Among these, di(2-ethylhexyl)sulfosuccinic acid sodium salt is preferable from the viewpoint of suppressing migration of the hydrophilic agent when it comes into contact with other members.

When the hydrophilic agent contains a wetting agent, the wetting agent is not particularly limited. For example, the hydrophilic agent may contain any of cationic surfactants, anionic surfactants, amphoteric surfactants, and nonionic surfactants as wetting agents.

Examples of cationic surfactants include alkyl (or alkenyl) trimethylammonium halides, dialkyl (or alkenyl) quaternary ammonium salts represented by dimethylammonium halides, alkylamine salts, and alkylene oxide adducts thereof. . Examples of anionic surfactants include phosphate salts such as sodium lauryl phosphate and fatty acid salts such as sodium laurate. Examples of amphoteric surfactants include salts of these cationic surfactants and anionic surfactants.

The wetting agent is preferably a nonionic surfactant from the viewpoint of imparting excellent hydrophilicity to the nonwoven fabric. Nonionic surfactants that are wetting agents include, for example, polyhydric alcohol fatty acid esters, polyoxyalkylene fatty acid esters, alkylpolyoxyethylene alcohols, alkylene oxide adducts of polyhydric alcohol fatty acid esters, alkoxylated alkylphenols, fatty acid amides, Examples include nonionic surfactants such as alkyldiethanolamides and polyoxyalkylenes. Among these, from the viewpoint of imparting excellent hydrophilicity, the hydrophilic agent is selected as a wetting agent from the group consisting of polyhydric alcohol fatty acid esters, polyoxyalkylene fatty acid esters, and alkylene oxide adducts of polyhydric alcohol fatty acid esters. It is preferable to include at least one kind of The polyhydric alcohol fatty acid ester, the polyoxyalkylene fatty acid ester, and the alkylene oxide adduct of the polyhydric alcohol fatty acid ester may be monoesters, diesters, and triesters, respectively. Polyhydric alcohol fatty acid esters, polyoxyalkylene fatty acid esters, and alkylene oxide adducts of polyhydric alcohol fatty acid esters may each contain one of monoesters, diesters, and triesters alone; It may contain more than seeds.

Polyhydric alcohol fatty acid esters include glycerin fatty acid esters and sorbitan fatty acid esters. Both glycerin fatty acid esters and sorbitan fatty acid esters are preferably esters of glycerin or sorbitan with fatty acids having 10 to 20 carbon atoms. Specific examples include glycerin lauric acid monoester, glycerin oleic acid diester, glycerin oleic acid triester, sorbitan lauric acid monoester, sorbitan lauric acid diester, and sorbitan lauric acid triester.

Polyoxyalkylene fatty acid esters include polyoxyethylene fatty acid esters and polyoxypropylene fatty acid esters. Among these, polyoxyethylene fatty acid esters are preferred. The polyoxyethylene fatty acid ester preferably has 10 to 20 carbon atoms in the fatty acid and 5 to 20 moles of the ethylene oxide chain (also referred to as EO chain). Specific examples include polyoxyethylene stearate monoester, polyoxyethylene laurate monoester, polyoxyethylene laurate diester, polyoxyethylene oleate monoester, and polyoxyethylene oleate diester.

Examples of alkylene oxide adducts of polyhydric alcohol fatty acid esters include ethylene oxide adducts of polyhydric alcohol fatty acid esters and propylene oxide adducts of polyhydric alcohol fatty acid esters. Among these, the alkylene oxide adduct of a polyhydric alcohol fatty acid ester is preferably an ester of glycerin and a fatty acid having 10 to 20 carbon atoms and has 5 to 20 moles of ethylene oxide added. Specific examples include polyoxyethylene glycerol laurate monoester, polyoxyethylene glycerol laurate diester, and polyoxyethylene glycerol laurate triester.

The wetting agent preferably contains a combination of a polyhydric alcohol fatty acid ester, an alkylene oxide adduct of the polyhydric alcohol fatty acid ester, and a polyoxyalkylene fatty acid ester, from the viewpoint of imparting excellent hydrophilicity to the nonwoven fabric. It is also preferable that the wetting agent is a combination of a polyhydric alcohol fatty acid ester and a polyoxyalkylene fatty acid ester.

Combinations of polyhydric alcohol fatty acid esters, alkylene oxide adducts of polyhydric alcohol fatty acid esters, and polyoxyalkylene fatty acid esters include glycerin fatty acid esters, ethylene oxide adducts of polyhydric alcohol fatty acid esters, and polyoxyethylene fatty acids. A combination with an ester is more preferred. A combination of glycerin oleate diester, polyoxyethylene glycerin laurate diester and triester, and polyoxyethylene laurate diester is more preferred.

A combination of a polyhydric alcohol fatty acid ester and an alkylene oxide adduct of a polyhydric alcohol fatty acid ester is preferably a combination of a glycerin fatty acid ester and an alkylene oxide adduct of a polyhydric alcohol fatty acid ester, and glycerin oleic acid. Combinations of diesters and glycerin oleic acid triesters with polyoxyethylene oleic acid monoesters and polyoxyethylene oleic acid diesters are more preferred.
Further, the combination of polyhydric alcohol fatty acid ester and polyoxyalkylene fatty acid ester is preferably a combination of sorbitan lauric acid monoester, diester or triester and polyoxyethylene lauric acid monoester or diester. In addition to these sorbitan laurate and polyoxyethylene laurate, it is also preferable to combine polyoxyethylene sorbitan oleate monoester, polyoxyethylene sorbitan oleate diester and polyoxyethylene sorbitan oleate triester.

The weight ratio of penetrant to wetting agent (penetrant/wetting agent) is preferably 0/100 to 60/40, more preferably 5/95 to 50/50, and 10/90 to 40/ 60 is more preferred. When the mass ratio of the wetting agent/penetrating agent is within this range, the hydrophilicity is excellent.

The content of the hydrophilic agent is preferably 0.01% by mass to 2.0% by mass, more preferably 0.05% by mass to 1.0% by mass, and 0.1% by mass to 0.1% by mass. More preferably, it is 5% by mass.
The method of applying the hydrophilic agent is not particularly limited. Examples of the method of applying the hydrophilic agent include a method of kneading it into the raw material resin of the composite fiber, and a method of applying it to the surface after processing into a fiber shape.
The method for imparting the hydrophilic agent to the surface of the fiber is not particularly limited, and the fiber is applied by a known and publicly used method such as a method of immersing the fiber in a solution containing the hydrophilic agent or a method of applying a solution containing the hydrophilic agent to the fiber. It can be applied to the surface.
As a method of kneading into the raw material resin, for example, a method of adding the above-described hydrophilic agent to at least one of the above-described region A and the above-described region B resin, and then spinning to form a fiber. mentioned.

(other ingredients)
The conjugate fiber in the present disclosure may contain, as optional components, antioxidants, heat stabilizers, weather stabilizers, antistatic agents, slip agents, antifog agents, lubricants, dyes, pigments, Various known additives such as natural oils, synthetic oils and waxes may also be included.

The nonwoven fabric of the present disclosure may contain other components as needed. Other components include, for example, antioxidants, heat stabilizers, weather stabilizers, antistatic agents, slip agents, antifog agents, lubricants, dyes, pigments, light stabilizers, antiblocking agents, dispersants, and nucleating agents. , softeners, water repellents, fillers, natural oils, synthetic oils, waxes, antibacterial agents, preservatives, matting agents, antirust agents, fragrances, antifoaming agents, antifungal agents, insect repellents, etc. and additives. These other components may be contained inside the fibers constituting the nonwoven fabric, or may be attached to the surface of the fibers.

<Method for manufacturing nonwoven fabric>
The method for producing the nonwoven fabric of the present disclosure is not particularly limited as long as it is a spunbond method. The spunbond method includes, for example, a step of melt-spinning a propylene-based polymer to form continuous fibers (spinning step), and a step of depositing the continuous fibers on a moving collection member to form a nonwoven web ( forming a nonwoven web); and partially crimping the nonwoven web (crimping step).

The spinning process includes the well-known process of cooling and stretching prior to the nonwoven web forming step of depositing the first continuous fibers on the moving collection member. From the viewpoint of achieving both flexibility and strength of the spunbond nonwoven fabric, the compression bonding step is preferably performed by thermocompression bonding using an embossing roll. In thermocompression bonding, it is preferable to use an embossing roll having a convex area ratio of 7% to 20%. The surface temperature of the embossing roll can be, for example, within the range of 90.degree. C. to 160.degree.

<Application>
Since the nonwoven fabric of the present disclosure has both strength and flexibility, it can be suitably used for conventionally known nonwoven fabric applications. Nonwoven fabrics of the present disclosure include, for example, absorbent articles (disposable diapers, disposable pants, sanitary products, urine absorbing pads, pet sheets, etc.), cosmetic materials (face masks, etc.); sanitary materials (poultice materials, sheets, towels, industrial masks, sanitary masks, hair caps, etc.);

The nonwoven fabric of the present disclosure will be described below with reference to examples, but the nonwoven fabric of the present disclosure is not limited by the following examples. In addition, in the following examples, "%" represents mass %.

Physical properties and the like in Examples and Comparative Examples were measured by the following methods.

(1) basis weight [g/m ² ]
Ten test pieces of 100 mm (machine direction: MD) x 100 mm (direction perpendicular to machine direction: CD) were sampled from the obtained nonwoven fabric. Ten test pieces were collected in the CD direction. Then, the mass [g] was measured for each test piece taken under an environment of 23° C. and a relative humidity of 50% using a top-pan electronic balance (manufactured by Kensei Kogyo Co., Ltd.). An average value of the mass of each test piece was determined. The obtained average value was converted to mass [g] per 1 m ² , rounded off to the second decimal place, and determined as basis weight [g/m ² ] of each nonwoven fabric sample.

(2) Average fiber diameter [μm]
A test piece was taken from the obtained nonwoven fabric and imaged using a Nikon ECLIPSE E400 microscope at a magnification of 20 times. Among the fibers appearing in the obtained image, the diameters of all fibers whose diameter (width) can be measured were measured. The imaging and measurement were repeated until the number of measurement points exceeded 100. Fiber diameters were read in microns to one decimal place. An average value of the diameters thus obtained was obtained, and this value was defined as an average fiber diameter (μm).

[Evaluation of flexibility]
(3) B value (flexural rigidity) [gf cm ² /cm]
Two test pieces of 200 mm (MD)×200 mm (CD) were randomly sampled from the obtained nonwoven fabric. Then, using a KES-FB2 bending property tester manufactured by Kato Tech Co., Ltd., the sample was held on a chuck at intervals of 1 cm, and the curvature was 0.50 cm ⁻ in the range of −2.5 to +2.5 cm ⁻¹ . Pure bending tests were performed at a deformation rate of ¹ sec ⁻¹ . The measured values were averaged for each of the MD direction and the CD direction, and rounded off to the fifth decimal place to obtain the KES-bending stiffness B value (KES-B value).

[Evaluation of strength]
(4) Tensile strength and strength at 5% stretching [N/25mm]
The obtained nonwoven fabric was measured according to JIS L 1906. A test piece having a width of 25 mm and a length of 200 mm was taken from the nonwoven fabric, and the distance between chucks was 100 mm and the head speed was 100 mm/min using a tensile tester. was calculated, and the tensile strength in the MD direction (N/25 mm) and the tensile strength in the CD direction (N/25 mm) were obtained. Also, the intensity INDEX was calculated from the following formula.
[Formula] Strength INDEX = (((tensile strength in MD direction) 2 + (tensile strength in CD direction) 2)) / 2) 0.5

[Evaluation of thickness]
Ten test pieces of 100 mm (MD)×100 mm (CD) were taken from the obtained nonwoven fabric. The test piece was taken from the same place as the test piece for basis weight measurement. Then, using a load-type thickness gauge (manufactured by Ozaki Seisakusho Co., Ltd.) for each sampled test piece, the thickness [mm] is measured at a load of 0.3 kPa in accordance with the method described in JIS L 1096: 2010. did. The average value of the thickness of each test piece was obtained. The thickness [mm] of each nonwoven fabric sample was obtained by rounding off to the third decimal place.

The following materials were prepared as raw materials used in Examples and Comparative Examples.

-rPP1-
Propylene/ethylene random copolymer -rPP2- having an MFR of 60 g/10 min (ASTM D-1238, 230°C, 2.16 kg load), a melting point of 142°C, and an ethylene content of 4% by mass
Propylene/ethylene random copolymer -hPP1- having an MFR of 24 g/10 min (ASTM D-1238, 230°C, 2.16 kg load), a melting point of 105°C, and an ethylene content of 15% by mass
MFR 60 g/10 minutes (230°C, 2.16 kg load), melting point 162°C, propylene homopolymer -PE1-
Ethylene/ ¹ -butene random copolymer -PE2- with an MFR of 25 g/10 min (ASTM D-1238, 190°C, 2.16 kg load) and a density of 915 kg/m3
Ethylene/ ⁴ -methyl-1-pentene random copolymer -PE3- with an MFR of 50 g/10 min (190°C/2.16 kg load) and a density of 928 kg/m3
Ethylene/ ¹ -hexene random copolymer -PE4- with an MFR of 50 g/10 min (190°C/2.16 kg load) and a density of 948 kg/m3
Ethylene/propylene random copolymer ⁽ PE1) with an MFR of 18 g/10 min (190°C/2.16 kg load) and a density of 955 kg/m3

<Example 1>
A spunbonded nonwoven fabric was obtained by performing composite melt spinning by a spunbond method using a nozzle for forming an eccentric sheath-core composite fiber with an exposed core shown in FIG. 2(b). Specifically, rPP1 was used as a core and was led to a nozzle of the core. In addition, the PE1 was used as a sheath and led to the nozzle of the sheath. The melting temperature and extrusion temperature were 210° C. for both the core and the sheath. The mass ratio of the core part and the sheath part was 40:60. A nonwoven web was obtained by depositing the bicomponent fibers spun from the nozzle onto a moving conveyor net.
Then, the nonwoven fabric web was heat-pressed (embossed) at 125° C. with an embossing roll and a mirror surface roll to obtain a spunbond nonwoven fabric. The spunbond nonwoven fabric had a basis weight of 20 g/m ² , a thickness of 0.15 mm, an area ratio of the crimped portion of 18%, and an average fiber diameter of 17.6 μm. Table 1 shows the strength and bending stiffness B value of the obtained nonwoven fabric.

<Examples 2 to 6, Comparative Examples 1 to 9>
A nonwoven fabric web was obtained in the same manner as in Example 1, except that the raw materials for the core and the sheath and the ratio of the core and the sheath were changed as shown in Table 1.
Next, a spunbonded nonwoven fabric was obtained in the same manner as in Example 1, except that the thermocompression bonding temperature was changed as shown in Table 1.
Table 1 shows the average fiber diameter, basis weight, strength, and flexural rigidity B value of the obtained spunbond nonwoven fabric. The thickness of the spunbond nonwoven fabrics of Examples 2 to 6, Comparative Examples 1 to 6, Comparative Examples 8 and 9 was 0.15 mm. Moreover, the thickness of the spunbond nonwoven fabric of Comparative Example 7 was 0.18 mm.

For the core portion of Example 5, a resin composition in which 75% by mass of hPP1 and 25% by mass of rPP2 were mixed was used. For the sheath of Example 6, a resin composition in which 50% by mass of PE1 and 50% by mass of PE3 were mixed was used.

It can be seen that the spunbond nonwoven fabrics obtained in Examples 1 to 6 have an excellent balance between strength and flexibility. The fibers of Comparative Example 7 were crimped.

1 Area A
2 Area B
3 Core 4 Sheath

Claims (10)

A spunbonded nonwoven fabric containing composite fibers containing a region A containing a propylene/α-olefin random copolymer and a region B containing an ethylene polymer,
The composite fiber is a side-by-side type or an eccentric core-sheath type,
The ratio of the region A to the region B is 70:30 to 10:90 (region A: region B) on a mass basis;
The spunbond nonwoven fabric, wherein the region B has a density of 0.900 kg/m ³ to 0.945 kg/m ³ . 2. The spunbond nonwoven fabric according to claim 1, wherein said bicomponent fibers have said regions A exposed. 3. The spunbond nonwoven fabric according to claim 1, wherein the propylene/α-olefin random copolymer has a melting point of 155° C. or less. The spunbond nonwoven fabric according to any one of claims 1 to 3, wherein said region A further comprises a propylene homopolymer. The spunbond nonwoven fabric according to any one of claims 1 to 4, wherein the ethylene-based polymer comprises an ethylene/α-olefin copolymer. Any one of claims 1 to 5, wherein the ethylene polymer comprises at least one selected from the group consisting of ethylene/1-butene copolymer and ethylene/4-methyl-1-pentene copolymer. 1. The spunbond nonwoven fabric according to claim 1. The ethylene polymer according to any one of claims 1 to 6, wherein the MFR (ASTM D-1238, 190°C, 2.16 kg load) is 10 g/10 minutes to 100 g/10 minutes. of spunbond nonwovens. The spunbond nonwoven fabric according to any one of claims 1 to 7, wherein the composite fibers have an average fiber diameter of 10 µm to 40 µm. The spunbond nonwoven fabric according to any one of claims 1 to 8, which has a basis weight of 8 g/m ² to 30 g/m ² . The spunbond nonwoven fabric according to any one of claims 1 to 9, wherein said bicomponent fibers contain a hydrophilic agent.

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