JP2021161564A - Spunbonded nonwoven fabrics, sanitary materials, and method for drawing of spunbonded nonwoven fabric - Google Patents

Abstract

To provide a spunbonded nonwoven fabric excellent in elongation property, a method for drawing the same, and a sanitary material using a spunbonded nonwoven fabric.SOLUTION: There is provided a spunbonded nonwoven fabric which comprises 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 polymer shown in (I) and the polymer shown in (II). A ratio (MD/CD) of the strength in the flow direction (MD) to the strength in the lateral direction (CD) is 2.0 or more and 4.0 or less, and 5% strength in the flow direction (MD) is 5 to 9. The polymer shown in (I) is a random copolymer of propylene and an α-olefin having a specific carbon number, and the polymer shown in (II) is a propylene homopolymer having a melting point of less than 120°C and satisfies specific physical properties.SELECTED DRAWING: None

Description

The present disclosure relates to spunbonded non-woven fabrics, sanitary materials, and methods for stretching spunbonded non-woven fabrics.

In recent years, non-woven fabrics have been widely used in various applications because of their excellent breathability and flexibility. Typical uses of non-woven fabrics include, for example, absorbent articles such as disposable diapers and sanitary napkins, sanitary masks, medical gauze, and base cloths for compresses.
Such a non-woven fabric is required to have extensibility depending on the place where it is used.

As a spunbonded non-woven fabric having good heat sealability at low temperature and suitability for stretching, for example, Patent Document 1 describes a propylene homopolymer having a relatively high melting point, polyethylene, and an α having a specific carbon number. -Disclosure of spunbonded non-woven fabrics containing a polymer selected from the group consisting of a random copolymer of olefin and propylene and a propylene homopolymer having a relatively low melting point and a specific mesopentad fraction and a racemic pentad fraction. Has been done.

International Publication No. 2017/006972

The spunbonded nonwoven fabric described in Patent Document 1 may be required to have higher extensibility. Stretchable non-woven fabrics, which are required to have extensibility, are often subjected to a stretching step in order to give flexibility or perform a desired shaping treatment in the use as a non-woven fabric. However, such a stretching step may break depending on the properties of the non-woven fabric to be stretched, and the desired processing may not be possible. That is, the suitability for stretching the non-woven fabric to be stretched may not always be sufficient.

An object of an embodiment of the present invention is to provide a spunbonded nonwoven fabric having excellent extensibility and a sanitary material using the spunbonded nonwoven fabric.
An object of another embodiment of the present invention is to provide a method for stretching a spunbonded nonwoven fabric having excellent extensibility.

Means for solving the above problems include the following embodiments.
<1> With a propylene homopolymer having a melting point of 140 ° C. or higher,
With polyethylene
It contains a fiber composed of a composition containing at least one polymer selected from the group consisting of the polymer shown in (I) below and the polymer shown in (II) below.
The ratio (MD / CD) of the strength in the flow direction (MD) of the machine to the strength in the direction perpendicular to the flow of the machine (CD) is 2.0 or more and 4.0 or less.
The 5% intensity of the machine flow direction (MD) at 40 ° C. is 5N / 50mm-9N / 50mm.
Spun-bonded non-woven fabric.
(I) Random copolymer of propylene and at least one olefin selected from the group consisting of ethylene and α-olefin having 4 to 20 carbon atoms (II) Satisfying the following (a) to (f). Propylene copolymer having a melting point of less than 120 ° C. (a) [mmmm] = 20 mol% to 60 mol%
(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 to 200,000
(F) Molecular weight distribution (Mw / Mn) <4
In (a) to (d), [mm mm] is a racemic pentad fraction, [rrrr] is a racemic pentad fraction, and [rmrm] is a racemic mesolacemic mesopentad fraction, [mm], [Rr] and [mr] are triad fractions, respectively.

<2> density of the polyethylene ^is in the range of ^{0.941g / cm 3 ~0.970g / cm 3} , spunbonded nonwoven fabric according to <1>.
<3> The method according to <1> or <2>, wherein the composition contains a fatty acid amide having 15 or more and 22 or less carbon atoms in an amount of 0.1% by mass or more and 5.0% by mass or less based on the total amount of the composition. Spunbond non-woven fabric.
<4> Of <1> to <3>, wherein the composition contains 55.0% by mass or more and 90.0% by mass or less of the propylene homopolymer having a melting point of 140 ° C. or higher with respect to the total amount of the composition. The spunbonded nonwoven fabric according to any one.
<5> The span according to any one of <1> to <4>, wherein the composition contains the polyethylene in an amount of 1.0% by mass or more and 10.0% by mass or less based on the total amount of the composition. Bond non-woven fabric.
<6> The spunbonded nonwoven fabric according to any one of <1> to <5>, wherein the polymer shown in (I) is a random copolymer of propylene and ethylene.

<7> 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 based on the total amount of the composition. The spunbonded nonwoven fabric according to any one of <1> to <6>, which is 30.0% by mass or less.
<8> A sanitary material containing the spunbonded non-woven fabric according to any one of <1> to <7>.
<9> A method for stretching a spunbonded nonwoven fabric, which comprises a step of stretching the spunbonded nonwoven fabric according to any one of <1> to <7> with a stretching apparatus.
<10> The method for stretching a spunbonded nonwoven fabric according to <9>, which comprises a step of preheating the spunbonded nonwoven fabric according to any one of <1> to <7> before the stretching step.
<11> The method for stretching a spunbonded nonwoven fabric according to <9> or <10>, wherein the temperature of the spunbonded nonwoven fabric at the time of stretching is 30 ° C. to 50 ° C. in the stretching step.

According to one embodiment of the present invention, a spunbonded nonwoven fabric having excellent extensibility and a sanitary material using the spunbonded nonwoven fabric are provided.
According to another embodiment of the present invention, there is provided a method for producing a spunbonded nonwoven fabric having excellent extensibility.

FIG. 1 is a schematic view of a closed spunbonding method. FIG. 2 is a schematic side view showing an example of a preheating roll. FIG. 3 is a schematic perspective view of the gear stretching device. FIG. 4 is a photograph of the surface of the stretched nonwoven fabric of Example 1. FIG. 5 is a photograph of the surface of the stretched nonwoven fabric of Comparative Example 1.

Hereinafter, the contents of the present invention will be described in detail.
Although the description of the constituent elements described below may be based on typical embodiments of the present invention, the present disclosure is not limited to such embodiments.

In the present specification, the term "process" is included in this term not only as an independent process but also as long as the purpose of the process is achieved even if it cannot be clearly distinguished from other processes.
In the present specification, the content of each component in the composition is the sum of the plurality of substances present in the composition unless otherwise specified, when a plurality of substances corresponding to each component are present in the composition. Means quantity.

In addition, the numerical range represented by using "~" in the present specification means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.
In the numerical range described stepwise in the present specification, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerical range described stepwise. good. Further, in the numerical range described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

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

(Spanbond non-woven fabric)
The spunbonded nonwoven fabric according to the embodiment of the present invention includes a propylene homopolymer having a melting point of 140 ° C. or higher (hereinafter, also referred to as “specific propylene”), polyethylene, a polymer shown in (I) below, and (II) below. ), And a fiber composed of a composition containing at least one polymer selected from the group consisting of the polymers (hereinafter, also referred to as “specific polymer”), which is perpendicular to the flow of the machine. The ratio of the strength of the machine's flow direction (MD) (hereinafter, also simply referred to as "flow direction (MD)") to the strength of the direction (CD) (hereinafter, also simply referred to as "lateral direction (CD)") (MD). / CD) is 2.0 or more and 4.0 or less, and the 5% intensity of the flow direction (MD) at 40 ° C. is 5N / 50mm to 9N / 50mm.
(I) Random copolymer of propylene and at least one olefin selected from the group consisting of ethylene and α-olefin having 4 or more and 20 or less carbon atoms (II) The following (a) to (f). Satisfied propylene copolymer having a melting point of less than 120 ° C. (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), [mm mm] is a racemic pentad fraction, [rrrr] is a racemic pentad fraction, and [rmrm] is a racemic mesolacemic mesopentad fraction, [mm], [Rr] and [mr] are triad fractions, respectively.

The spunbonded nonwoven fabric according to the embodiment of the present invention has the above-mentioned structure and is excellent in the extensibility of the obtained nonwoven fabric.
The reason is not clear, but it is presumed as follows.
The spunbonded nonwoven fabric according to one embodiment of the present invention is composed of fibers made of a specific composition, and has a ratio (MD / CD) of strength in the flow direction (MD) to strength in the lateral direction (CD) of 2. By setting it from 0.0 to 4.0 and setting the 5% strength of the flow direction (MD) at 40 ° C to the range of 5N / 50mm to 9N / 50mm, the dispersion direction of the fibers is MD-oriented and is around 40 ° C. It is presumed that a change in strength suitable for processing appears at a temperature of (for example, 30 ° C. to 50 ° C.), and as a result, the obtained nonwoven fabric has excellent extensibility and excellent stretchability while maintaining extensibility. ..

The extensibility means that it has a property of extending in one direction when an external force is applied, but does not go back when the external force is released.

<< Strength ratio (MD / CD) >>
The spunbonded nonwoven fabric according to the embodiment of the present invention has a ratio (MD / CD) of strength in the flow direction (MD) to strength in the lateral direction (CD) of 2.0 or more and 4.0 or less. Since the strength ratio (MD / CD) of the spunbonded non-woven fabric is 2.0 or more and 4.0 or less, the spunbonded non-woven fabric has more molecular orientation in MD than CD and has a larger amount of grain, and extends to MD. It becomes better in sex. Further, when the strength ratio (MD / CD) is 4.0 or less, the strength of the spunbonded non-woven fabric does not increase too much, and the risk of cracking can be suppressed.
The strength ratio (MD / CD) is preferably 2.5 or more and 4.0 or less, and more preferably 2.5 or more and 3.8 or less, from the viewpoint of the extensibility of the obtained spunbonded non-woven fabric. ..

The MD / CD of the spunbonded non-woven fabric is described in 6.12.1 [A method] of JIS L 1906 (transition to JIS L 1913: 2010, ISO 9073-3: 1989), as will be described in detail in Examples described later. Correspondence) can be measured.

<< 5% strength of MD at 40 ° C >>
The spunbonded nonwoven fabric according to the embodiment of the present invention has a 5% strength of 5N / 50mm to 9N / 50mm in the flow direction (MD) at 40 ° C. When the MD of the spunbonded non-woven fabric has a 5% strength of 5N / 50mm to 9N / 50mm, it is excellent in stretchability while maintaining extensibility.
The 5% strength of MD means the strength when the spunbonded nonwoven fabric is stretched by 5%, and is an index of processability.

It is generally known that the rigidity of an olefin resin decreases when it is heated. Therefore, the olefin-based non-woven fabric using the olefin resin also has the same characteristics. The 5% strength in the flow direction (MD) in the present invention indicates the initial tensile strength, but when the non-woven fabric is heated, the 5% strength of the MD decreases. When the non-woven fabric is subjected to secondary processing, it is common to heat (preheat) the non-woven fabric in advance to reduce the rigidity before processing. The spunbonded nonwoven fabric according to the embodiment of the present invention utilizes a change in strength depending on the degree of heating during processing, and when preheating is performed at a temperature of 30 ° C. to 50 ° C. close to room temperature, the rigidity is relaxed. At the same time, it exhibits the property of increasing elongation. As a result, resistance to width shrinkage in the flow direction (MD) is ensured, and the suitability for stretching is excellent.

From the above viewpoint, the 5% strength of MD at 40 ° C. is preferably 5N / 50mm to 8N / 50mm, and more preferably 5N / 50mm to 7.5N / 50mm.
The 5% intensity in the MD direction at 40 ° C. is a value (N / 50 mm) obtained by the method used in the examples described later.

The 5% strength of MD / CD and MD in the above specific range is the blower amount (stretched air volume; unit) described later with respect to the discharge amount (R; unit kg / h) per single hole of the molten composition (resin) described later. It can be adjusted by the ratio (A / R) of Nm ^{3 / min) (A).}
From the viewpoint of enhancing the extensibility of the obtained non-woven fabric, the A / R is preferably 1.5 or more, more preferably 1.5 or more and 2.2 or less, and 1.8 or more and 2.2 or less. Is more preferable.

^{The blower amount (stretched air volume) indicates, for example, the air volume (unit: Nm 3} / min) of the cooling air supplied from the blower 15 to the fibers through the filter 17 in the cooling chamber, as shown in FIG.
The discharge amount (R) of the molten composition (resin) per single hole is, for example, as shown in FIG. 1, the discharge amount (R; unit) of the melted composition (resin) per single hole of the spinneret 11. kg / h) is shown.
The method for adjusting the blower amount (stretched air volume; A) and the discharge amount (R) per single hole of the melted composition (resin) will be described in the method for producing a spunbonded nonwoven fabric described later.

<Fiber>
The fibers contained in the spunbonded nonwoven fabric according to the embodiment of the present invention include a propylene homopolymer (specific polypropylene) having a melting point of 140 ° C. or higher, polyethylene, a polymer shown in (I) below, and (II) below. It is composed of at least one polymer (specific polymer) selected from the group consisting of polymers and a composition containing the polymer (hereinafter, also referred to as "composition constituting fibers" or simply "composition"). NS.
It can be appropriately confirmed by a known method that each of the above components is contained in the composition constituting the spunbonded nonwoven fabric according to the embodiment of the present invention or the fiber composed of the composition.

The mesopentad fraction [mmmm], racemic pentad fraction [rrrr], racemic mesolazemimesopentide fraction [rmrm], and triad of the propylene homopolymer having a melting point of less than 120 ° C. in the polymer shown in (II). The fractions [mm], [rr] and [mr] are based on the method proposed in "Macropolymers, 6,925 (1973)" by A. Zambelli et al., As detailed below. Can be calculated.

<< Specific polypropylene >>
A propylene homopolymer having a melting point of 140 ° C. or higher contains a structural unit 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 specific polypropylene is a crystalline resin manufactured or sold under the name of polypropylene, and can be used as long as it is a resin having a melting point (Tm) of 140 ° C. or higher.
Examples of commercially available products include homopolymers of propylene having a melting point in the range of 155 ° C. or higher, preferably 157 ° C. or higher and 165 ° C. or lower.

The melt flow rate (MFR: ASTMD-1238, 230 ° C., load 2160 g) of the specific polypropylene is not particularly limited as long as it can be melt-spun, but is usually preferably 1 g / 10 minutes or more and 1000 g / 10 minutes or less. It is more preferably 5 g / 10 minutes or more and 500 g / 10 minutes or less, and further preferably in the range of 10 g / 10 minutes or more and 100 g / 10 minutes or less.

The content of the polypropylene homopolymer having a melting point of 140 ° C. or higher in the total mass of the composition is preferably 55.0% by mass or more and 90.0% by mass or less, and 60.0% by mass or more and 85.0% by mass. % Or less, more 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 in the composition is within the above range, the extensibility of the obtained spunbonded nonwoven fabric can be improved, and the strength and physical properties of the spunbonded nonwoven fabric are maintained within a good range. , It is easy to obtain a flexible non-woven fabric with a low basis weight.
The specific polypropylene may be contained in only one kind in the composition constituting the fiber, or may contain two or more kinds having different melting points, molecular weights, crystal structures and the like.

<< Polyethylene >>
The fiber contained in the spunbonded nonwoven fabric according to the embodiment of the present invention contains polyethylene.
The polyethylene that can be used in this embodiment is not particularly limited as long as it is polyethylene containing a structural unit derived from ethylene. Specifically, high-pressure low-density polyethylene, linear low-density polyethylene (so-called LLDPE), and high-density polyethylene are used. Preferable examples include ethylene homopolymers such as polyethylene (so-called HDPE).

The density of polyethylene contained in the composition in the present embodiment is in the range of ^{0941 g / cm 3} or more and 0.970 g / cm ³ or less from the viewpoint of improving the strength, extensibility and flexibility of the spunbonded nonwoven fabric. It is preferable, and it is more preferable that it is in the range of ^{0.941 g / cm 3} or more and 0.960 g / cm ^{3 or less.}

The melting point of polyethylene is preferably 150 ° C. or higher, more preferably 155 ° C. or higher, and even more preferably 155 ° C. or higher and 165 ° C. or lower.

The melt flow rate of polyethylene (MFR: ASTMD-1238, 230 ° C., load 2160 g) is not particularly limited as long as it can be melt-spun, but is usually preferably 1 g / 10 minutes or more and 1000 g / 10 minutes or less. It is more preferably 5 g / 10 minutes or more and 500 g / 10 minutes or less, and further preferably in the range of 10 g / 10 minutes or more and 100 g / 10 minutes or less.

The content of polyethylene is preferably 1.0% by mass or more and 10.0% by mass or less, and 3.0% by mass or more and 8.0% by mass or less, based on the total mass of the composition constituting the fiber. Is more preferable, and 5.0% by mass or more and 7.0% by mass or less is further preferable.
When the polyethylene content is in the above range, the extensibility of the obtained spunbonded non-woven fabric can be improved.
Only one type of polyethylene may be contained in the composition constituting the fiber, or two or more types having different melting points, molecular weights, crystal structures and the like may be contained.

<< Specific Polymer >>
The fiber contained in the spunbonded nonwoven fabric according to the embodiment of the present invention is at least one polymer (specific) selected from the group consisting of polyethylene, the polymer shown in the following (I), and the polymer shown in the following (II). Polymer) is contained. By containing the specific polymer, the obtained spunbonded non-woven fabric has excellent stretchability while maintaining good flexibility and extensibility.

[Polymer (I)]
The fiber in the spunbonded non-woven fabric is a random copolymer of (I) propylene and at least one olefin selected from the group consisting of ethylene and an α-olefin having 4 to 20 carbon atoms (hereinafter, “polymer”). (I) ”) can be contained. In other words, the polymer (I) contains a structural unit derived from propylene and a structural unit derived from at least one olefin selected from the group consisting of ethylene and an α-olefin having 4 to 20 carbon atoms. It is a random copolymer.
It is preferable that the polymer (I) is a random copolymer because the obtained spunbonded non-woven fabric does not have a sticky feeling and the flexibility is improved.

The polymer (I) is not particularly limited as long as it is a random copolymer containing the above-mentioned structural unit.
"Constituent unit derived from propylene" means one unit of propylene in the polymer main chain formed by the polymerization reaction of propylene.
The "constituent unit derived from an olefin" means one unit of an α-olefin in a polymer main chain formed by a polymerization reaction of an α-olefin.

Examples of the α-olefin having 4 to 20 carbon atoms include 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 4-methyl-1-pentene and the like.

As the structural unit derived from at least one olefin selected from the group consisting of ethylene and α-olefin having 4 or more and 20 or less carbon atoms, a structural unit derived from 1-butene, a structural unit derived from 1-hexene, and 4 Examples thereof include a structural unit derived from methyl-1-pentene, a structural unit derived from 1-octene, a structural unit derived from 4-methyl-1-pentene, and the like.
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 structural unit derived from the α-olefin contained in the polymer (I) may be only one kind or two or more kinds.

Specific examples of the polymer (I) include a propylene / 1-butene random copolymer, a propylene / ethylene random copolymer, a propylene / ethylene / 1-butene random copolymer, and the like.

From the viewpoint of effectively achieving the object according to the embodiment of the present invention, at least one olefin selected from the group consisting of a constituent unit derived from propylene, ethylene and an α-olefin having 4 or more and 20 or less carbon atoms. The total ratio of the constituent units derived from the above is preferably 80 mol% or more, more preferably 85 mol% or more, and 90 mol% or more, based on all the constituent units contained in the polymer (I). It is more preferably mol% or more.

The melting point of the polymer (I) is preferably 100 ° C. or higher, more preferably 130 ° C. or higher, and even more preferably 150 ° C. or higher.

The melting point of the polymer (I) is determined by the melting endothermic curve obtained by holding the polymer (I) at −40 ° C. for 5 minutes under a nitrogen atmosphere and then raising the temperature at 10 ° C./min using a differential scanning calorimeter (DSC). It is defined as the peak top of the peak observed on the hottest side.
Specifically, using a differential scanning calorimeter (manufactured by PerkinElmer, product name: DSC-7), 5 mg of the sample was held at −40 ° C. for 5 minutes in a nitrogen atmosphere, and then the temperature was raised at 10 ° C./min. It can be obtained as the peak top of the peak observed on the highest temperature side of the melting endothermic curve obtained by the above-mentioned.

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 determined by melting heat absorption obtained by holding the polymer (I) at −40 ° C. for 5 minutes under a differential scanning calorimeter (DSC) and then raising the temperature at 10 ° C./min. It is calculated from the heat of fusion curve derived from the melting of the main component of the curve.
Specifically, using a differential scanning calorimeter (DSC-7, manufactured by PerkinElmer), 5 mg of the sample was held at −40 ° C. for 5 minutes in a nitrogen atmosphere, and then the temperature was raised at 10 ° C./min. Of the obtained heat absorption curves for melting, it can be calculated using the following formula from the heat of fusion curve derived from the melting of the main component.
Crystallinity (%) = ΔH / ΔH ₀ × 100
In the formula, ΔH is the amount of 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, and ΔH ₀ is the melting of the perfect crystal of the main component. The amount of heat (J / g). That is, when the main component is ethylene, ΔH0 is 293 J / g, and when the main component is propylene, ΔH ₀ is 210 J / g.

The tensile elastic modulus of the polymer (I) measured by a method conforming to JIS K 7161 (transitioned to JIS K 7161-1: 2014, corresponding to ISO 527-1: 2012) is preferably 100 MPa or less. , 40 MPa or less, more preferably 25 MPa or less.

As the melt flow rate (MFR) (measurement conditions: 230 ° C., load 2160 g) measured by a method conforming to ASTM standard D-1238 of the polymer (I), good spinnability and excellent drawability are obtained. From the point of view, it is usually 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. It is more preferably in the range of minutes or less.

The ratio of the weight average molecular weight (Mw) of the polymer (I) to the number average molecular weight (Mn): Mw / Mn (molecular weight distribution) is usually preferably 1.5 or more and 5.0 or less, and has spinnability. The molecular weight distribution (Mw / Mn) of the polymer (I) is more preferably 1.5 or more and 3.0 or less in that a composite fiber having a better quality and a particularly excellent fiber strength can be obtained.
The better spinnability means that the yarn does not break during the ejection and drawing of the polymer (I) from the spinning nozzle, and the filaments do not fuse.
Mw and Mn of the polymer (I) can be measured by a known method by GPC (gel permeation chromatography).
The details of the measurement method will be described later.

[Polymer (II)]
The fibers in the spunbonded nonwoven fabric contain (II) a propylene homopolymer having a melting point of less than 120 ° C. (hereinafter, may be referred to as polymer (II)) satisfying (a) to (f) shown below. Can be done.
Hereinafter, each of the requirements (a) to (f) will be described.

-(A) [mmmm] = 20 mol% or more and 60 mol% or less-
When the mesopentad fraction [mm mm] of the polymer (II) is 20 mol% or more, the occurrence of stickiness is likely to be suppressed, and when it is 60 mol% or less, the crystallinity does not become too high, so that it is elastic. Good recovery.
From the above viewpoint, the mesopentad fraction [mm mm] is preferably 30 mol% or more and 50 mol% or less, and more preferably 40 mol% or more and 50 mol% or less.

The mesopentad fraction [mmmm], the racemic pentad fraction [rrrr] described later, and the racemic mesolane semimesopentide fraction [rmrm] are defined by A. Zambeli and the like as "Macromolecules, 6,925." (1973) ”, the meso-parts, racemic-partsper, and racemic-meso-racemic-meso in pentad units in the polypropylene molecular chain measured by the signal of the methyl group ^{in the 13 C-NMR spectrum.} It is a fraction.
The larger the mesopentad fraction [mm mm], the higher the stereoregularity. Further, the triad fractions [mm], [rr], and [mr] described later are also calculated by the above method.

The measurement of the ¹³ C-NMR spectrum can be performed with the following equipment and conditions according to the peak attribution proposed in "Macromomolecules, 8, 687 (1975)" by A. Zambeli et al. can.

Equipment: JNM-EX400 type ¹³ C-NMR equipment manufactured by JEOL Ltd. Method: Proton complete decoupling method Concentration: 220 mg / ml
Solvent: 90:10 (volume ratio) mixture of 1,2,4-trichlorobenzene and heavy benzene Solvent temperature: 130 ° C
Pulse width: 45 °
Pulse repetition time: 4 seconds integration: 10000 times

[a formula]
M = m / S × 100
R = γ / S × 100
S = Pββ + Pαβ + Pαγ
S: Signal intensity of side chain methyl carbon atom of all propylene units Pββ: 19.8 ppm or more and 22.5 ppm or less Signal intensity Pαβ: 18.0 ppm or more and 17.5 ppm or less Signal intensity Pαγ: 17.5 ppm or more and 17.1 ppm or less Signal intensity γ: Lasemipentad chain: Signal intensity of 20.7 ppm or more and 20.3 ppm or less m: Mesopentad chain: Signal intensity of 21.7 ppm or more and 22.5 ppm or less In addition, M is the abundance rate of the mesopentad chain in propylene. Represents, and R represents the abundance of the racemic pentad chain in propylene.

-(B) [rrrr] / (1- [mmmm]) ≤ 0.1-
The value of [rrrr] / [1-mmmm] is obtained from the fractions of the racemic pentad unit and the mesopentad unit, and is an index showing the uniformity of the regularity distribution of the propylene-derived constituent units in the polymer (II). be. When this value becomes large, it becomes a mixture of highly regular polypropylene and atactic polypropylene like conventional polypropylene manufactured by using an existing catalyst system, which causes stickiness.
When [rrrr] / (1- [mmmm]) of the polymer (II) is 0.1 or less, the stickiness of the obtained spunbonded non-woven fabric is suppressed. From such a viewpoint, [rrrr] / (1- [mmmm]) is preferably 0.05 or less, more preferably 0.04 or less.

-(C) [rmrm]> 2.5 mol%-
When the racemic mesolasemimeso fraction [rmrm] of the polymer (II) exceeds 2.5 mol%, the randomness of the polymer (II) increases, and the elastic recovery of the spunbonded non-woven fabric is further improved. do. [Rmrm] is preferably 2.6 mol% or more, and more preferably 2.7 mol% or more. The upper limit of the racemic mixture of the polymer (II) [rmrm] is usually about 10 mol%.

-(D) [mm] x [rr] / [mr] ² ≤ 2.0-
[Mm] × [rr] / [mr] ² indicates an index of randomness of the polymer (II). When the value of [mm] × [rr] / [mr] ² is 2.0 or less, the elastic non-woven fabric can obtain sufficient elastic recovery and suppress stickiness, and the closer it is to 0.25, the more random it is. Will be higher. From the viewpoint of obtaining sufficient elastic recovery, [mm] × [rr] / [mr] ² is preferably more than 0.25 and 1.8 or less, and more preferably 0.5 or more and 1.5 or less. Is.

-(E) Weight average molecular weight (Mw) = 10,000 or more and 200,000 or less-
The weight average molecular weight of the polymer (II) is 10,000 or more and 200,000 or less by weight average molecular weight (Mw).
When the weight average molecular weight of the polymer (II) is 10,000 or more, the viscosity of the polymer (II) is not too low and becomes appropriate, so that the yarn at the time of producing the spunbonded nonwoven fabric obtained by the composition Cutting is suppressed. Further, 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.
From the above viewpoint, the weight average molecular weight of the polymer (II) is preferably 30,000 or more and 150,000 or less, and more preferably 50,000 or more and 150,000 or less.
The method for measuring the weight average molecular weight of the polymer (II) will be described later.

-(F) Molecular weight distribution (Mw / Mn) <4-
The molecular weight distribution (Mw / Mn) of the polymer (II) is less than 4.
When the molecular weight distribution (Mw / Mn) of the polymer (II) is less than 4, the occurrence of stickiness in the obtained spunbonded nonwoven fabric is suppressed. From the above viewpoint, the molecular weight distribution of the polymer (II) 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 a gel permeation chromatography (GPC) method under the following equipment and conditions. The molecular weight distribution (Mw / Mn) is a value calculated from the number average molecular weight (Mn) measured in the same manner as the weight average molecular weight (Mw) and the weight average molecular weight (Mw).

-GPC measuring 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 velocity: 1.0 ml / min Sample concentration: 2.2 mg / ml
Injection volume: 160 μl
Calibration curve: Universal Calibration
Analysis program: HT-GPC (Ver.1.0)

The melting point of the polymer (II) is less than 120 ° C.
It is preferable that the polymer (II) further satisfies the following requirement (g).
(G) Melting point (Tm-D) = 0 ° C. or higher and lower than 120 ° C. The melting point (Tm-D) of the polymer (II) is -10 under a nitrogen atmosphere using (g) differential scanning calorimeter (DSC). It is a 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 ° C. for 5 minutes and then raising the temperature at 10 ° C./min.
When the melting point (Tm-D) of the polymer (II) is 0 ° C. or higher, the occurrence of stickiness of the spunbonded nonwoven fabric formed by the composition is suppressed. Further, when the melting point (Tm-D) is less than 120 ° C., sufficient elastic recovery can be obtained. From this point of view, 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.

The melting point (Tm-D) was measured at 10 ° C./min after holding 10 mg of the sample in a nitrogen atmosphere at -10 ° C. for 5 minutes using a differential scanning calorimeter (DSC-7, manufactured by PerkinElmer). It can be obtained as the peak top of the peak observed on the highest temperature side of the melting endothermic curve obtained by raising the temperature.

As the melt flow rate (MFR) (measurement conditions: 230 ° C., load 2160 g) measured by a method conforming to ASTM standard D 1238 of the polymer (II), good spinnability and excellent drawability are obtained. Therefore, it is usually 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 preferably in the following range.

The polymer (II) can be synthesized, for example, by using a homogeneous catalyst such as a metallocene catalyst described in International Publication No. 2003/0871772.

The content of the specific polymer is preferably 5.0% by mass or more and 30.0% by mass or less, preferably 10.0% by mass or more and 30.0% by mass or less, based on the total mass of the composition. More preferably, it is more preferably 15.0% by mass or more and 25.0% by mass or less.
When the content of the specific polymer in the composition is within the above range, the extensibility of the obtained spunbonded non-woven fabric can be improved.

From the viewpoint of the extensibility of the obtained non-woven fabric, 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, more preferably 90% by mass or more. It is preferably 95% by mass or more, and more preferably 95% by mass or more.

The specific polymer is a random copolymer containing at least (I) a structural unit derived from propylene and a structural unit derived from ethylene, or (II) from the viewpoint of further improving the extensibility of the obtained spunbonded non-woven fabric. ) It is preferable that it is a propylene homopolymer having a melting point of less than 120 ° C. that satisfies (a) to (f), and (I) a random copolymer containing at least a structural unit derived from propylene and a structural unit derived from ethylene. It is more preferable that the polymer is a random copolymer consisting of only a structural unit derived from propylene and a structural unit derived from ethylene.

<Additives>
The composition constituting the fiber is, as an optional component, an antioxidant, a heat-resistant stabilizer, a weather-resistant stabilizer, an antistatic agent, a slip agent, an antifogging agent, a lubricant, a dye, and a pigment, as long as the object of the present invention is not impaired. , Natural oils, synthetic oils, waxes, fatty acid amides and other known additives may be included.

<Fatty acid amide>
The composition constituting the fiber 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 spunbonded nonwoven fabric formed by the composition, and the fiber surface is modified. Therefore, it is considered that the flexibility, tactile sensation, blocking resistance and the like are further improved, and the adhesion of the non-woven fabric fibers to the members of various rotating devices and the like in the apparatus used in the embossing process and the like is more effectively suppressed. As a result, the extensibility and flexibility of the non-woven fabric are further improved.

The carbon number of the fatty acid amide in the present specification means the carbon number contained in the molecule, and the carbon in -CONH constituting the amide is also included in the carbon number.
The number of carbon atoms of the fatty acid amide is preferably 18 or more and 22 or less.
Examples of fatty acid amides having 15 or more and 22 or less carbon atoms include fatty acid monoamide compounds, fatty acid diamide compounds, saturated fatty acid monoamide compounds, and unsaturated fatty acid diamide compounds. Among these, palmitate amide (16 carbon atoms) and stearer. Preferable examples include acid amide (18 carbon atoms), oleic acid amide (18 carbon atoms), and erucic acid amide (22 carbon atoms).

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 or less, based on the total amount of the composition. The following is more preferable, and 0.1% by mass or more and 1.0% by mass or less is further preferable.
Only one type of fatty acid amide may be contained in the composition constituting the fiber, or two or more types may be contained.

[Manufacturing method of spunbonded non-woven fabric]
The spunbonded nonwoven fabric according to one embodiment of the present invention can be produced by a conventional method using one or more of the above-mentioned compositions.
The following methods can be mentioned as a general method for producing a spunbonded nonwoven fabric using the composition constituting the above-mentioned fibers. That is,
The composition constituting the above-mentioned fiber is melted by using an extruder, and the melted composition is melt-spun by using a spunbonded non-woven fabric molding machine having a plurality of spinnerets. The fibers are stretched by controlling the air volume with a blower or the like, and the long fibers formed by spinning are cooled as necessary. Then, it is deposited on the collection surface of the spunbonded non-woven fabric molding machine and heat-pressurized with an embossed roll.

Hereinafter, the manufacturing process of the spunbonded nonwoven fabric will be described in detail with reference to the drawings.
FIG. 1 is a schematic view of a closed spunbonding method produced by stretching melt-spun long fibers while being cooled in a closed space using a composition which is a raw material of a non-woven fabric.

The spunbond method shown in FIG. 1 is performed by a closed spunbonded non-woven fabric manufacturing apparatus having a closed space (sealed cooling chamber 13). Specifically, in the closed-type spunbond method shown in FIG. 1, first, the molten composition discharged from the spinneret 11 passes through the throat portion 12 of the closed-type spunbonded non-woven fabric manufacturing apparatus, and is sealed in a cooling chamber. It is stretched at 13 and cooled if necessary to form long fibers 18. The formed long fibers 18 reach the collecting device 20 and are deposited to form the spunbonded non-woven fabric 21. After the deposition, a heat and pressure treatment using an embossed roll or the like can be performed.
The cooling air is supplied to the inside of the cooling chamber 13 from the looper 14 connected to the blower 15 and the damper 16 via the filter 17. The amount of cooling air supplied to the cooling chamber 13 is adjusted by opening and closing the blower 15, the switching valve 19 for adjusting the cooling air sent to the blower 15, and the damper 16.

The method for producing a spunbonded nonwoven fabric according to an embodiment of the present invention has been described by taking a closed spunbond method as an example, but the method for producing a spunbonded nonwoven fabric according to an embodiment of the present invention is limited to the closed spunbond method. However, for example, an open spunbond method for cooling in an open space may be used.

The melting temperature of the composition is not particularly limited as long as it is the softening temperature of the composition used for spinning or the melting temperature or higher and lower than the thermal decomposition temperature, and may be appropriately set depending on the physical characteristics of the composition to be used. can.

The temperature of the spinneret 11 depends on the composition used, but is preferably 180 ° C. to 240 ° C., preferably 190 ° C. to 230 ° C. in consideration of the physical properties of the propylene-containing polymer having a large content in the above composition. The temperature is more preferably set to 200 ° C to 225 ° C.

The pore diameter of the spinneret 11 is preferably 0.05 mm to 0.4 mm from the viewpoint of the extensibility of the obtained non-woven fabric.

The single-hole discharge amount (R) of the melted composition (resin) is preferably 1.0 g / min to 3.5 g / min, preferably 1.5 g / min to 1.5 g / min, from the viewpoint of the extensibility of the obtained non-woven fabric. More preferably, it is 2.5 g / min.

The temperature of the cooling air for cooling the spun long fibers is not particularly limited as long as the temperature at which the composition solidifies. Generally, the temperature of the cooling air is preferably 5 ° C. to 50 ° C., more preferably 10 ° C. to 40 ° C., and further preferably in the range of 15 ° C. to 30 ° C.

The velocity of the drawing air when stretching the spun fibers by air (air) (blower volume) (A), in view of the elongation of the resulting nonwoven fabric, usually it is 20 Nm ³ / min ~45Nm ³ / min preferably, and more preferably in the range of 30 Nm ³ / min ~36Nm ³ / min.

The basis weight of the spunbonded non-woven fabric is not particularly limited. From the viewpoint of achieving both flexibility and strength, the basis weight is usually ^{preferably 30 g / m 2} or less, more preferably 28 g / m ² or less, and further preferably 25 g / m ² or less. It is preferably in the range of ^{5 g / m 2} or more and 20 g / m ^{2 or less.}
When the spunbonded nonwoven fabric according to one embodiment of the present invention 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 fibers constituting the spunbonded non-woven fabric usually have a fiber diameter of 4.0 d (denier) or less, more preferably 3.0 d or less, further preferably 2.8 d or less, and 2 It is even more preferable that it is 0.7d or less.
The smaller the fiber diameter, the better the flexibility of the non-woven fabric, but from the viewpoint of handleability, manufacturing suitability, and suppression of fluffing of the obtained non-woven fabric, the fiber diameter is preferably 1.0 d or more.

The form of the fibers constituting the spunbonded nonwoven fabric is not particularly limited, and may be a single fiber or a composite fiber.
In the case of composite fibers, core-sheath type, sea-island type and the like can be appropriately used. Further, it may be a long fiber (staple) or a single fiber (filament). Further, the cross-sectional shape of the fiber is not particularly limited, and may be a shape such as a circular shape, an elliptical shape, or a deformed cross section.

In the production method according to the embodiment of the present invention, a part of the fibers of the obtained spunbonded nonwoven fabric may be heat-sealed. The fibers of the spunbonded non-woven fabric may be compacted using a nip roll before heat fusion.

[Physical characteristics of spunbonded non-woven fabric]
The preferred physical properties of the spunbonded nonwoven fabric according to the embodiment of the present invention are listed below.

-Heat sealability-
The spunbonded non-woven fabric according to the embodiment of the present invention is preferably heat-sealed at a temperature of 180 ° C. or lower, preferably 160 ° C. or lower, when two spunbonded non-woven fabrics are laminated and heat-sealed by a heat-sealing tester. More preferably, it can be heat-sealed at the temperature of.
In addition, it is preferable that burning when heat-sealed under the above conditions, that is, discoloration due to heating is suppressed.
The tensile peel strength of the two heat-sealed spunbonded non-woven fabrics is appropriately determined depending on the purpose of use of the spunbonded non-woven fabric, but is generally preferably 0.05 N / 20 mm or more, and 0.1 N / 20 mm or more. It is more preferably 20 mm or more.

-Embossing survival rate-
The residual embossing rate of the spunbonded non-woven fabric after the stretching process is preferably 40% or more, more preferably 50% or more, and further preferably 70% or more. When the residual embossing rate after the stretching process is 40% or more, the tactile sensation of the spunbonded non-woven fabric becomes better.
The embossing residual rate can be measured by the method used in the examples described later.

-Maximum elongation and tensile strength (maximum strength)-
The maximum elongation is an index for evaluating the extensibility.
The spunbonded non-woven fabric has a maximum elongation in the flow direction (MD) of preferably 180% or more, more preferably 190% or more, and further preferably 200% or more.
Further, the spunbonded nonwoven fabric according to the embodiment of the present invention preferably has a maximum elongation of 150% or more in the direction perpendicular to the flow (CD), more preferably more than 155%, and more preferably 170% or more. Is more preferable.

Further, the spunbonded non-woven fabric preferably has a tensile strength (maximum strength) of 10 N / 50 mm or more in at least one direction in the flow direction (MD) and the lateral direction (CD), and more preferably 15 N / 50 mm or more. , 20N / 50mm or more is more preferable.
Further, a spunbonded non-woven fabric having a property of having almost no elastic recovery is preferable.
The maximum elongation and tensile strength (maximum strength) of the spunbonded non-woven fabric are determined in 6.12.1 [Method A] of JIS L 1906 (JIS L 1913: 2010), ISO 9073, as described in detail in Examples. -3: Corresponds to 1989).

[Non-woven fabric laminate]
The spunbonded non-woven fabric according to the embodiment of the present invention may be used alone, or may be a non-woven fabric laminate obtained by laminating the spunbonded non-woven fabric according to the embodiment of the present invention and another layer, depending on the purpose. good. In the case of a non-woven fabric laminate using the spunbonded non-woven fabric according to the embodiment of the present invention, the other layers other than the spunbonded non-woven fabric according to the embodiment of the present invention may be one layer or 2 layers. It may have more than one layer.

Specific examples of the layers other than the spunbonded non-woven fabric according to the embodiment of the present invention include knitted fabrics, woven fabrics, and non-woven fabrics other than the spunbonded non-woven fabric according to the embodiment of the present invention (hereinafter, "other". Also referred to as non-woven fabric), films and the like.

The method of further laminating (bonding) another layer to the spunbonded nonwoven fabric according to the embodiment of the present invention is not particularly limited, and is a heat fusion method such as heat embossing or ultrasonic fusion, needle punching, water. Various methods such as a mechanical entanglement method such as a jet, a method using an adhesive such as a hot melt adhesive and a urethane adhesive, and an extrusion lamination can be adopted.

Examples of other non-woven fabrics that can be laminated with the spunbonded non-woven fabric according to the embodiment of the present invention to form a non-woven fabric laminate include spunbonded non-woven fabrics, melt-blown non-woven fabrics, and wet non-woven fabrics other than the spunbonded non-woven fabric according to the embodiment of the present invention. , Dry non-woven fabric, dry pulp non-woven fabric, flash-spun non-woven fabric, spread non-woven fabric, and various other known non-woven fabrics.
These non-woven fabrics may be stretchable non-woven fabrics or non-stretchable non-woven fabrics.
Here, the non-stretchable non-woven fabric means a non-woven fabric that does not generate a return stress after being stretched in MD (that is, the flow direction of the non-woven fabric, the vertical direction) or CD (that is, the direction perpendicular to the flow direction of the non-woven fabric, the lateral direction). ..

As the film capable of forming a nonwoven fabric laminate by laminating with the spunbonded nonwoven fabric according to the embodiment of the present invention, a breathable film or a moisture-permeable film is preferable when the nonwoven fabric laminate requires breathability.
As the breathable film, a film made of a thermoplastic elastomer such as a moisture-permeable polyurethane elastomer, a polyester elastomer, or a polyamide elastomer, or a film made of a thermoplastic resin containing inorganic fine particles or organic fine particles is stretched and made porous. Examples thereof include various known breathable films such as a porous film.
As the thermoplastic resin used for the porous film, polyolefins such as high-pressure low-density polyethylene, linear low-density polyethylene (so-called LLDPE), high-density polyethylene, polypropylene, polypropylene random copolymer, and a combination thereof are preferable.
When the nonwoven fabric laminate does not require breathability, a thermoplastic resin film made of one or more thermoplastic resins selected from polyethylene, polypropylene and the like can be used.

It is preferable that the non-woven fabric laminate is partially heat-sealed.
Examples of the heat fusion method for heat-sealing a part of the non-woven 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. Above all, heat embossing is preferable in that long fibers are efficiently stretched when the non-woven fabric laminate is stretched.

When a part of the non-woven fabric laminate is heat-sealed by heat embossing, the embossing area ratio is usually preferably 5% or more and 30% or less, and more preferably 5% or more and 20% or less. The non-embossed unit area is ^{preferably in the range of 0.5 mm 2} or more, more preferably in the range of 4 mm ² or more and 40 mm ² or less.
The non-embossed unit area is the maximum area of a quadrangle inscribed in embossing in the smallest unit non-embossed portion surrounded by embossed portions on all sides. Further, the engraved shape is exemplified by a circle, an ellipse, an oval, a square, a rhombus, a square, a square, or a continuous shape based on those shapes.

When heat embossing is performed, the embossing temperature is generally preferably in the range of 85 ° C. to 150 ° C., although it depends on the line speed, crimping pressure, etc. at the time of embossing.

(Method of stretching spunbonded non-woven fabric and non-woven fabric laminate, stretched non-woven fabric)
The spunbonded non-woven fabric and the non-woven fabric laminate are preferably further stretched. The spunbonded non-woven fabric and the non-woven fabric laminate can be made into a stretchable non-woven fabric and a non-woven fabric laminate having elasticity, respectively, by stretching.

The method for stretching the spunbonded non-woven fabric and the non-woven fabric laminate is not particularly limited, and conventionally known methods can be applied.
The stretching method may be a method of partially stretching or a method of totally stretching. Further, it may be a method of uniaxial stretching or a method of biaxial stretching.
Examples of the method of stretching in the flow direction (MD) include a method of passing mixed fibers partially fused to 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 roll in the order of the flow direction of the machine.

The method for stretching the spunbonded non-woven fabric preferably includes a step of stretching the spunbonded non-woven fabric with a stretching device from the viewpoint of the extensibility of the obtained non-woven fabric.

The steps of stretching the spunbonded non-woven fabric with the stretching device include a step of stretching the spunbonded nonwoven fabric using a gear stretching device that stretches with a gear, a step of stretching the spunbonded nonwoven fabric by applying pressure and heating by heat embossing, and heating. Examples thereof include a step of applying pressure and heating to stretch the spunbonded nonwoven fabric through a roll pair, a step of heating the spunbonded nonwoven fabric with hot air, and then applying pressure and stretching through the roll pair.

The temperature of the spunbonded non-woven fabric at the time of stretching is preferably 30 ° C. to 50 ° C. In order to adjust the temperature of the spunbonded non-woven fabric, the spunbonded non-woven fabric may be preheated to a temperature of 30 ° C. to 50 ° C.

From the viewpoint of the extensibility of the obtained non-woven fabric, the method for stretching the spunbonded non-woven fabric preferably includes a step of preheating the spunbonded non-woven fabric before the stretching step.
Examples of the method for preheating the spunbonded non-woven fabric include a method usually used as a method for preheating the non-woven fabric, and there is no particular limitation. Among them, as the preheating method, a method capable of raising the temperature of the spunbonded non-woven fabric to preferably 30 ° C. to 50 ° C. (more preferably 35 ° C. to 45 ° C.) is preferable. The preheating method is preferably a method of preheating the spunbonded non-woven fabric using a preheating roll from the viewpoint of the extensibility of the obtained non-woven fabric.

The preheating roll may be a single roll or a pinch roll (a pair of rolls) shown in FIG.
When the preheating roll is composed of a plurality of rolls, it is preferable that at least one of the plurality of rolls is a preheating roll, and it is more preferable that all the rolls are preheating rolls.
The preheating roll diameter is not particularly limited as long as it is a known roll diameter used for the non-woven fabric.

In the step of preheating the spunbonded non-woven fabric, the surface temperature of the preheating roll is preferably 30 ° C. to 100 ° C., more preferably 35 ° C. to 70 ° C.

Further, in the step of preheating the spunbonded nonwoven fabric, the temperature of the spunbonded nonwoven fabric and the surface temperature of the preheating roll can be measured by a conventional method using a contact type thermocouple thermometer, a non-contact type thermometer, or the like. ..
Specifically, according to the following procedures (1) and (2), measurements are made at arbitrary 5 points on the roll surface, and the arithmetic mean value of the measured values at the arbitrary 5 points is used as the surface temperature.
(1) The roll is heated, and at any point on the surface of the roll, a contact thermometer (model: HFT-51, manufactured by Anritsu Co., Ltd.) and a measuring probe (model: U-131E-00-D0, Anritsu Co., Ltd.) ) And) to measure the temperature.
(2) The temperature measurement time shall be 10 seconds, and the value obtained by rounding off the value with one decimal place shall be read and used as the measured value.

In the step of preheating the spunbonded non-woven fabric, from the viewpoint of the extensibility of the obtained non-woven fabric, the preheating time is preferably 1 second to 60 minutes, more preferably 1 second to 300 seconds, and 1 second to 1 second. It is more preferably 60 seconds.

The draw ratio in the flow direction (MD) is preferably 180% or more, more preferably 200% or more, and preferably 1000% or less, more preferably 400% or less.

The draw ratio in the direction perpendicular to the MD (CD) is preferably 140% or more, more preferably 150% or more, still more preferably 170% or more. The stretch ratio of the CD is preferably 1000% or less, more preferably 400% or less.

By stretching at such a draw ratio, the elastic long fibers in the spunbonded nonwoven fabric are stretched, and the non-stretchable long fibers are plastically deformed and stretched according to the draw ratio.
Similarly, in the other layers to be laminated, the elastic layer is elastically deformed, and the non-elastic layer is plastically deformed.
When forming a non-woven fabric laminate, an elastic layer and a non-elastic layer are laminated and stretched, and then when stress is released, the elastic layer (long fibers constituting the layer) becomes elastic. The recovered and non-elastic long fibers can bend without recovering the elasticity and give a feeling of bulkiness to the non-woven fabric laminate. Since the plastically deformed long fibers become thin, the flexibility and the tactile sensation are improved, and the non-woven fabric laminate can be provided with a non-stretching function.

(Sanitary material)
The sanitary material according to the embodiment of the present invention includes the spunbonded nonwoven fabric according to the embodiment of the present invention described above.
The spunbonded nonwoven fabric of the present invention has excellent extensibility. Therefore, the spunbonded nonwoven fabric according to the embodiment of the present invention is suitably used as a sanitary material.

Examples of sanitary materials include absorbent articles such as disposable diapers and sanitary napkins, medical sanitary materials such as bandages, medical gauze and towels, and sanitary masks.
The sanitary material that can include the spunbonded nonwoven fabric according to the embodiment of the present invention is not limited to these, and can be suitably used for any of various sanitary material applications that require extensibility and flexibility.
The sanitary material may include the spunbonded non-woven fabric according to the embodiment of the present invention as a non-woven fabric laminate containing the spunbonded non-woven fabric according to the embodiment of the present invention and other layers.

Hereinafter, embodiments of the present invention will be described in more detail based on examples, but the present invention is not limited to these examples, which are embodiments of the present invention.
Physical property values and the like in Examples and Comparative Examples were measured by the following methods.

(1) Metsuke [g / m ² ]
Ten test pieces having a flow direction (MD) of 300 mm and a lateral direction (CD) of 250 mm were collected from the spunbonded non-woven fabric. In addition, the collection place was arbitrary 10 places. 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 calculated average value ^{was converted into mass (g) per 1 m 2} , and the first decimal place was rounded off to obtain the basis weight of the spunbonded non-woven fabric [g / m ² ].

(2) Maximum elongation, tensile strength (maximum strength), and strength ratio (MD / CD)
From spunbonded non-woven fabric, in accordance with JIS L 1906 6.12.1 [A method] (transition to JIS L 1913: 2010, corresponding to ISO 9073-3: 1989), JIS Z 8703 (standard condition of test site) ), In a constant temperature room having a temperature of 20 ± 2 ° C. and a humidity of 65 ± 2%, five test pieces having a flow direction (MD) of 25 cm and a lateral direction (CD) of 5 cm were collected. The obtained test pieces were subjected to a tensile test using a tensile tester (Instron Japan Company Limited, Instron 5564 type) under the conditions of a chuck distance of 100 mm and a tensile speed of 300 mm / min, and the five test pieces were tensioned. The loads were measured, and the average value of their maximum values was taken as the tensile strength (maximum strength) [N / 50 mm].
Further, the elongation at the tensile strength (maximum strength) was defined as the maximum elongation [%], which was used as an index for evaluating the extensibility. The strength ratio (MD / CD) was determined from the obtained tensile strengths in the MD direction and the CD direction.

(3) 5% strength of MD at 40 ° C. A constant temperature layer containing a tensile tester was prepared. The constant temperature layer was set to 40 ° C. in advance, and it was confirmed that the temperature was stable for 1 hour or more. Five test pieces having a flow direction (MD) length of 25 cm and a lateral direction (CD) length of 5 cm were collected, placed in a constant temperature layer for 30 minutes, and left to stand. After leaving the test piece for 30 minutes, a tensile test is performed in a constant temperature layer using a tensile tester (Instron Japan Company Limited, Instron 5564 type) under the conditions of a chuck distance of 100 mm and a tensile speed of 300 mm / min. rice field. The tensile load of the five test pieces at the time of extending by 0.5 cm was measured, and the average value of the measured values was taken as 5% strength.

(4) Fiber diameter Ten 10 mm × 10 mm test pieces were sampled from a spunbonded non-woven fabric, and the fiber diameter was read to the first decimal place at a magnification of 20 times using an ECLIPSE E400 microscope manufactured by Nikon Corporation. .. The diameters of 20 arbitrary points were measured for each test piece, and the average value was calculated.

(Example 1)
<Manufacturing of spunbonded non-woven fabric>
MFR (measured at a temperature of 230 ° C. and a load of 2.16 kg according to ASTMD1238) 60 g / 10 minutes, a density of 0.91 g / cm ³ , and a propylene homopolymer (1) having a melting point of 160 ° C. (1) 73.7% by mass.
MFR (measured at a temperature of 230 ° C. and a load of 2.16 kg according to ASTMD1238) 60 g / 10 minutes, density 0.91 g / cm ³ , propylene random copolymer having a melting point of 142 ° C. (2: Polymer (I)) (Copolymer of propylene and ethylene, polymerization molar ratio 97: 3) 20% by mass,
MFR (measured at a temperature of 190 ° C. and a load of 2.16 kg according to ASTMD1238) 5 g / 10 minutes, density 0.95 g / cm ³ , high density polyethylene with a melting point of 134 ° C. (3: hereinafter referred to as "polyethylene"). .) 6% by mass,
A mixture of 0.3% by mass of erucic acid amide is melted using an extruder of 75 mmφ, and a spunbonded non-woven fabric molding machine having a spun cap with 257 holes (in the direction perpendicular to the flow direction of the machine on the collection surface). Length: 800 mm, 2 blowers, see Fig. 1), both resin temperature and die temperature are 220 ° C, resin discharge rate 34 kg / h, cooling air temperature 20 ° C, stretched air air speed 3973 m / min, blower amount ( Melt spinning is performed by the spunbond method under the condition of (drawing air volume of one blower) 33 Nm ³ / min, deposited on the collection surface, and heat-pressurized with an embossing roll (embossing area ratio (heat crimping ratio) 18%, A spunbonded non-woven fabric having a total grain size of 18.0 g / m ^{2 was produced by embossing temperature (116 ° C.).}

In Example 1, a spunbonded non-woven fabric was produced by the closed spunbonding method shown in FIG.

Using the spunbonded non-woven fabric obtained above, evaluation was performed by the evaluation method described above. The evaluation results are shown in Table 1 below.

Next, one test piece having a flow direction (MD) of 250 mm and a lateral direction (CD) of 200 mm was collected from the spunbonded non-woven fabric obtained above.
The collected test piece was inserted so that the CD direction coincided with the roll rotation direction of the pinch roll shown in FIG. 2, and preheated. The preheating was performed by adjusting the surface temperature of the pinch roll (preheating roll) to 50 ° C. to 60 ° C. so that the temperature of the test piece would be 40 ° C. at the time of stretching. A test piece preheated to 40 ° C. is inserted so that the roll rotation direction and the CD direction of the gear stretching machine shown in FIG. 3 coincide with each other, and the test piece is stretched in the MD direction (nonwoven fabric flow direction) with a stretching ratio of 124%. Processed.
The pair of gear rolls mounted on the gear stretching machine had a diameter of 200 mm and a gear pitch of 2.5 mm, respectively, and the meshing depth of the two gear rolls was adjusted to 5.5 mm.
As described above, a stretched non-woven fabric was obtained.

The surface temperature of the pinch roll during preheating is the contact thermometer (model: HFT-51, manufactured by Anritsu Co., Ltd.) and the measuring probe (model: U-131E-00-D0, Anritsu) for any five points on the roll surface. The temperature was measured using (manufactured by Co., Ltd.). At this time, the temperature measurement time was set to 10 seconds, and the value obtained by rounding off the value with one decimal point was read and used as the measured value. Then, the value obtained by arithmetically averaging the measured values at any five points was used as the surface temperature.
The surface temperature of the stretched non-woven fabric was continuously measured on the surface of the non-woven fabric using a non-contact thermometer (model: MT7, manufactured by Mother Tool Co., Ltd.). At this time, the value obtained by truncating the value with one decimal point was read and used as the measured value. This was taken as the surface temperature.

The surface of the above-mentioned stretched non-woven fabric was observed to confirm the state of the surface. The results are shown in FIG. FIG. 4 is a photograph (length 210 mm × width 260 mm) of the surface of the stretched non-woven fabric.

Next, the tactile sensation of the stretched nonwoven fabric subjected to the above stretching treatment was evaluated by the following method.
(5) Tactile sensation The feel (tactile sensation) of the stretched non-woven fabric when touched by hand was evaluated by 10 evaluators according to the following evaluation criteria.
<Evaluation criteria>
Of the 3:10 people, all 10 evaluated that there was no roughness.
Of the 2:10 people, 9 to 7 people evaluated that there was no roughness.
Of the 1:10 people, 6 to 3 people evaluated that there was no roughness.
Of the 0:10 people, 2 to 0 people evaluated that there was no roughness.

(Examples 2 to 4, Comparative Examples 1 and 2)
A spunbonded nonwoven fabric was produced and evaluated in the same manner as in Example 1 except that the conditions for producing the raw materials and the nonwoven fabric shown in Table 1 were changed.

Further, the test piece collected in the same manner as in Example 1 was preheated and stretched to obtain a stretched non-woven fabric. Then, in the same manner as in Example 1, the surface of the stretched nonwoven fabric was observed to confirm the state of the surface. Further, in the same manner as in Example 1, the tactile sensation of the obtained stretched nonwoven fabric was evaluated. The evaluation results are shown in Table 1 and FIG. FIG. 5 is a photograph (length 210 mm × width 260 mm) of the surface of the stretched nonwoven fabric of Comparative Example 1.

The fiber diameter "-" in Comparative Example 1 in Table 1 means that the fiber diameter could not be confirmed.

As can be seen from Table 1 and FIGS. 4 to 5, the spunbonded nonwoven fabrics of Examples 1 to 4 are superior in extensibility as compared with the spunbonded nonwoven fabrics produced in Comparative Examples 1 and 2. ..
The stretched nonwoven fabrics obtained by stretching the spunbonded nonwoven fabrics of Examples 1 to 4 had no roughness and had a good tactile sensation. When the surface condition of the stretched non-woven fabric after the stretching treatment in Example 1 was observed on behalf of the examples, as shown in FIG. 4, no failure such as streaks was observed, and it was confirmed that the surface condition was good. Was done.
On the other hand, the stretched nonwoven fabrics obtained by stretching the spunbonded nonwoven fabrics of Comparative Examples 1 and 2 all had a rough feeling and were inferior in tactile sensation. When the surface condition of the stretched nonwoven fabric after the stretching treatment in Comparative Example 1 was observed on behalf of the comparative example, it was confirmed that a large number of white streaks were contained as shown in FIG. 5, and the surface condition was significantly deteriorated. You can see that.

From the above results, the spunbonded nonwoven fabric according to the embodiment of the present invention is excellent in extensibility and processability, and is suitable for use in sanitary materials that require extensibility and processability.

11 ... Spinning cap 12 ... Throat 13 ... Cooling chamber 14 ... Looper 15 ... Blower 16 ... Damper 17 ... Filter 18 ... Long fiber 19 ... Switching valve 20 ... Collection device 21 ... Spun-bonded non-woven fabric 30 ... Preheating roll 40 ... Spun-bonded non-woven fabric or non-woven fabric laminate A ... Direction of rotation of preheating roll

Claims (11)

With a propylene homopolymer having a melting point of 140 ° C or higher,
With polyethylene
At least one polymer selected from the group consisting of the polymer shown in (I) below and the polymer shown in (II) below,
Containing fibers composed of a composition comprising
The ratio (MD / CD) of the intensity in the flow direction (MD) to the intensity in the lateral direction (CD) is 2.0 or more and 4.0 or less.
A spunbonded non-woven fabric having a 5% strength in the flow direction (MD) at 40 ° C. of 5N / 50mm to 9N / 50mm.
(I) Random copolymer of propylene and at least one olefin selected from the group consisting of ethylene and α-olefin having 4 to 20 carbon atoms (II) Satisfying the following (a) to (f). Propylene copolymer having a melting point of less than 120 ° C. (a) [mmmm] = 20 mol% to 60 mol%
(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 to 200,000
(F) Molecular weight distribution (Mw / Mn) <4
In (a) to (d), [mm mm] is a racemic pentad fraction, [rrrr] is a racemic pentad fraction, and [rmrm] is a racemic mesolacemic mesopentad fraction, [mm], [Rr] and [mr] are triad fractions, respectively. Density of the ^{polyethylene,} 0.941 g / cm 3 in the range of ~0.970g / cm ^3, spunbonded nonwoven fabric according to claim 1. The spunbond according to claim 1 or 2, wherein the composition contains a fatty acid amide having 15 or more and 22 or less carbon atoms in an amount of 0.1% by mass or more and 5.0% by mass or less based on the total amount of the composition. Non-woven fabric. Any one of claims 1 to 3, wherein the composition contains 55.0% by mass or more and 90.0% by mass or less of the propylene homopolymer having a melting point of 140 ° C. or higher with respect to the total amount of the composition. The spunbonded non-woven fabric according to the section. The spunbonded nonwoven fabric according to any one of claims 1 to 4, wherein the composition contains the polyethylene in an amount of 1.0% by mass or more and 10.0% by mass or less based on the total amount of the composition. The spunbonded nonwoven fabric according to any one of claims 1 to 5, wherein the polymer shown in (I) is a random copolymer of propylene and ethylene. 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 spunbonded nonwoven fabric according to any one of claims 1 to 6, which is 0% by mass or less. A sanitary material containing the spunbonded nonwoven fabric according to any one of claims 1 to 7. A method for stretching a spunbonded nonwoven fabric, which comprises a step of stretching the spunbonded nonwoven fabric according to any one of claims 1 to 7 with a stretching apparatus. The method for stretching a spunbonded nonwoven fabric according to claim 9, further comprising a step of preheating the spunbonded nonwoven fabric according to any one of claims 1 to 7 before the stretching step. The method for stretching a spunbonded nonwoven fabric according to claim 9 or 10, wherein in the stretching step, the temperature of the spunbonded nonwoven fabric at the time of stretching is 30 ° C. to 50 ° C.

Images