JP2020076178A - Nonwoven fabric and manufacturing method thereof - Google Patents

Abstract

To provide a sufficiently bulky nonwoven fabric.SOLUTION: A nonwoven fabric comprises 10 mass% or more and 99 mass% or less of a propylene homopolymer (A) having a melting point (Tm-D) of more than 120°C measured by differential scanning calorimeter (DSC), and 1 mass% or more and 90 mass% or less of a propylene resin (B) having a melting point (Tm-D) of 120°C or less measured by differential scanning calorimeter (DSC), having a thickness/basis weight of 25 cm/g or more and 100 cm/g or less, and a tensile strength in CD direction of 5 N/5 cm or more.SELECTED DRAWING: None

Description

  The present invention relates to a nonwoven fabric and a method for manufacturing the same.

  In recent years, higher spinnability has been demanded for resins for fibers, and for example, expansion of the temperature range in which spinning is possible is required. For example, Patent Document 1 contains a highly crystalline polyolefin that satisfies a specific condition and a low crystalline polyolefin for the purpose of thinning the fibers that form the nonwoven fabric while maintaining the spinning stability. A fibrous nonwoven fabric made of a resin composition is disclosed.

International Publication No. 2014/119687

However, the technique disclosed in Patent Document 1 may not be able to obtain a sufficiently bulky nonwoven fabric.
The problem to be solved by the present invention is to provide a sufficiently bulky nonwoven fabric.

That is, the present disclosure relates to the following.
<1> 10% by mass or more and 99% by mass or less of a propylene homopolymer (A) having a melting point (Tm-D) measured by a differential scanning calorimeter (DSC) of more than 120 ° C., a differential scanning calorimeter (DSC) ), The melting point (Tm-D) is 120 ° C or less, and the polypropylene resin (B) is 1% by mass or more and 90% by mass or less, and the thickness / unit weight is 25 cm ³ / g or more and 100 cm ³ / g or less. A nonwoven fabric having a tensile strength in the CD direction of 5 N / 5 cm or more.
<2> The nonwoven fabric according to <1>, wherein the fiber diameter of the fibers forming the nonwoven fabric is 1.8 denier or less.
<3> The nonwoven fabric according to <1> or <2>, wherein the propylene homopolymer (A) has a melt flow rate (MFR) at 230 ° C. of 5 g / 10 minutes or more and 100 g / 10 minutes or less.
<4> In any one of the above items <1> to <3>, wherein the polypropylene resin (B) has a melt flow rate (MFR) at 230 ° C. of 5 g / 10 minutes or more and 5,000 g / 10 minutes or less. The non-woven fabric described.
<5> The melting endotherm (ΔHD) of the polypropylene resin (B) measured by a differential scanning calorimeter (DSC) is 0 J / g or more and 80 J / g or less, and the above <1> to <4. > The non-woven fabric according to any one of
<6> The nonwoven fabric according to any one of <1> to <5>, in which the polypropylene resin (B) has a molecular weight distribution (Mw / Mn) of 1.5 or more and 3.5 or less.
<7> The nonwoven fabric according to any one of <1> to <6>, wherein the polypropylene resin (B) is a propylene homopolymer.
<8> The nonwoven fabric according to any one of <1> to <7>, further including a polyethylene resin (C).
<9> The nonwoven fabric according to <8>, wherein the polyethylene resin (C) has a melt flow rate (MFR) at 190 ° C. of 10 g / 10 minutes or more and 50 g / 10 minutes or less.
<10> 10 mass% or more and 99 mass% or less of a propylene homopolymer (A) having a melting point (Tm-D) measured by a differential scanning calorimeter (DSC) of more than 120 ° C., a differential scanning calorimeter (DSC). ), The melting point (Tm-D) measured by 120 ° C. or less of the polypropylene resin (B) 1 mass% or more 90 mass% or less fibers, including a step of fusing with a hot air knife. ..
<11> The method for producing a nonwoven fabric according to <10> above, which does not use a compression roll.

  According to the present invention, a sufficiently bulky nonwoven fabric can be provided.

  Hereinafter, the present invention will be described in detail. In the present specification, the term “A to B” regarding the description of numerical values means “A or more and B or less” (when A <B) or “A or less and B or more” (when A> B). . In addition, in the present invention, a combination of preferred embodiments is a more preferred embodiment.

[Nonwoven fabric]
The nonwoven fabric of the present embodiment has a propylene homopolymer (A) having a melting point (Tm-D) measured by a differential scanning calorimeter (DSC) of more than 120 ° C. of 10% by mass or more and 99% by mass or less, a differential scanning type. 1 mass% or more and 90 mass% or less of polypropylene-based resin (B) whose melting point (Tm-D) measured by a calorimeter (DSC) is 120 ° C. or less is included, and thickness / unit weight is 25 cm ³ / g or more 100 cm ³ / The tensile strength in the CD direction is 5 N / 5 cm or more.

(Propylene homopolymer (A))
The melting point (Tm-D) of the propylene homopolymer (A) exceeds 120 ° C. When the melting point (Tm-D) is 120 ° C or lower, the strength of the fiber may be insufficient. From this point of view, the melting point (Tm-D) of the propylene homopolymer (A) is preferably 125 ° C. or higher, more preferably 130 ° C. or higher, still more preferably 135 ° C. or higher. The upper limit is not particularly limited, but is preferably 180 ° C or lower.
The melting point (Tm-D) of the propylene homopolymer (A) is maintained at −10 ° C. for 5 minutes in a nitrogen atmosphere using a differential scanning calorimeter (DSC) and then raised at 10 ° C./minute. It is defined as the peak top of the peak observed on the highest temperature side of the melting endothermic curve obtained.

The melt flow rate (MFR) of the propylene homopolymer (A) is preferably 5 g / 10 minutes or more, more preferably 7 g / 10 minutes or more, further preferably 10 g / 10 minutes or more, particularly preferably 20 g / 10 minutes or more. And is preferably 100 g / 10 minutes or less, more preferably 75 g / 10 minutes or less, still more preferably 50 g / 10 minutes or less. If the MFR is 5 g / 10 minutes or more, the spinnability will be better, and if it is 100 g / 10 minutes or less, the strength of the fiber can be further improved.
The melt flow rate (MFR) of the propylene homopolymer (A) is measured by the measuring method specified in JIS K7210, and the temperature is 230 ° C and the load is 2.16 kg.

  The half-crystallization time of the propylene homopolymer (A) at 25 ° C is preferably more than 0.01 seconds, more preferably 0.02 seconds or more, still more preferably 0.03 seconds or more, still more preferably 0. It is 04 seconds or more, and preferably 0.06 seconds or less, more preferably 0.05 seconds or less. When the half-crystallization time of the propylene homopolymer (A) at 25 ° C. exceeds 0.01 seconds, a difference from the half-crystallization time of the polypropylene resin (B) at 25 ° C. occurs, and the side-by-side crimped fiber The crimpability can be improved.

In this embodiment, the half crystallization time was measured by the following method.
Using a FLASH DSC (manufactured by METTLER TOLEDO Co., Ltd.), the sample was heated at 230 ° C. for 2 minutes to be melted, then cooled to 25 ° C. at 2,000 ° C./sec, and subjected to an isothermal crystallization process at 25 ° C. , Measure the change in heat generation over time. When the integrated value of the calorific value from the start of the isothermal crystallization to the completion of the crystallization is 100%, the time from the start of the isothermal crystallization to the integrated value of the calorific value of 50% is the half crystallization time. ..

  The content of the propylene homopolymer (A) in the nonwoven fabric is preferably 10% by mass or more, more preferably 75% by mass or more, further preferably 80% by mass or more, from the viewpoint of fiber spinnability, and It is preferably 99% by mass or less, more preferably 97% by mass or less, and further preferably 95% by mass or less.

  Further, the content of the propylene homopolymer (A) in the total 100% by mass of the propylene homopolymer (A) and the polypropylene resin (B) in the nonwoven fabric is preferably 10 from the viewpoint of fiber spinnability. It is at least mass%, more preferably at least 60 mass%, further preferably at least 70 mass%, and preferably at most 99 mass%, more preferably at most 95 mass%.

(Polypropylene resin (B))
The polypropylene-based resin (B) has a melting point (Tm-D) of 120 ° C. or lower, preferably 100 ° C. or lower, more preferably 90 ° C. or lower, and preferably 0 ° C. or higher, from the viewpoint of improving the spinnability of the fiber. , More preferably 30 ° C. or higher, still more preferably 60 ° C. or higher.
The melting point (Tm-D) of the polypropylene resin (B) is measured in the same manner as the melting point (Tm-D) of the propylene homopolymer (A).

The polypropylene resin (B) was obtained by using a differential scanning calorimeter (DSC) and holding the sample in a nitrogen atmosphere at −10 ° C. for 5 minutes and then raising the temperature at 10 ° C./minute. It is preferable that the melting endotherm (ΔHD) obtained from the above is 0 J / g or more and 80 J / g or less. Within the range, the spinnability of the fiber can be improved. From such a viewpoint, the melting endotherm (ΔH-D) is preferably 20 J / g or more, more preferably 25 J / g or more, further preferably 27 J / g or more, particularly preferably 30 J / g or more, and It is preferably 50 J / g or less, more preferably 45 J / g or less, still more preferably 40 J / g or less. If the melting endotherm is 20 J / g or more, stickiness is further suppressed.
The melting endotherm (ΔH-D) is the highest temperature of the melting endotherm curve obtained by DSC measurement, with the line connecting the low temperature side point where the calorific value does not change and the high temperature side point where the calorific value does not change as the baseline. It is calculated by obtaining the area surrounded by the line portion including the peak observed on the side and the baseline.
The melting endotherm (ΔH-D) can be controlled by appropriately adjusting the monomer concentration and reaction pressure.

The melt flow rate (MFR) of the polypropylene resin (B) is preferably 5 g / 10 minutes or more, more preferably 30 g / 10 minutes or more, further preferably 100 g / 10 minutes or more, from the viewpoint of improving the spinnability of the fiber. It is particularly preferably 1,000 g / 10 minutes or more, and preferably 5,000 g / 10 minutes or less, more preferably 4,000 g / 10 minutes or less, and further preferably 3,000 g / 10 minutes or less. If the MFR is 5 g / 10 minutes or more, the spinnability will be better, and if it is 100 g / 10 minutes or less, the strength of the fiber can be further improved.
The melt flow rate (MFR) of the polypropylene resin (B) is measured by the measuring method specified in JIS K7210, and the temperature is 230 ° C. and the load is 2.16 kg.

  The weight average molecular weight (Mw) of the polypropylene resin (B) is preferably 30,000 or more, more preferably 35,000 or more, still more preferably 40,000 or more, from the viewpoint of improving the spinnability of the fiber. It is preferably 200,000 or less, more preferably 150,000 or less, still more preferably 100,000 or less.

  The molecular weight distribution (Mw / Mn) of the polypropylene resin (B) is preferably 1.5 or more, more preferably 1.8 or more, and preferably 3.5 or less, more preferably 3.0 or less, More preferably, it is 2.5 or less. When the molecular weight distribution of the polypropylene resin (B) is within the range, stickiness in the fiber obtained by spinning is suppressed.

The weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) are determined by gel permeation chromatography (GPC) measurement. The weight average molecular weight is a polystyrene-equivalent weight average molecular weight measured by the following apparatus and conditions, and the molecular weight distribution is a value calculated from the number average molecular weight (Mn) similarly measured and the above weight average molecular weight.
<GPC measuring device>
Column: "TOSO GMHHR-H (S) HT" manufactured by Tosoh Corporation
Detector: RI detection for liquid chromatogram "WATERS 150C" manufactured by Waters Corporation
<Measurement conditions>
Solvent: 1,2,4-trichlorobenzene Measurement temperature: 145 ° C
Flow rate: 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 polypropylene resin (B) is not particularly limited as long as the above melting point (Tm-D) is within the above range, and may be a propylene homopolymer or a copolymer. Among them, propylene homopolymer is preferable.
When the polypropylene resin (B) is a copolymer, the copolymerization ratio of propylene units exceeds 50 mol%, preferably 60 mol% or more, more preferably 70 mol% or more, further preferably 90 mol% or more. , And more preferably 95 mol% or more. The copolymerizable monomer is at least one selected from the group consisting of ethylene and α-olefins having 4 to 30 carbon atoms, and specific examples include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, etc. are mentioned. When the polypropylene resin (B) is a copolymer, the polypropylene resin (B) contains 0 mol% of at least one structural unit selected from the group consisting of ethylene and α-olefins having 4 to 30 carbon atoms. It is preferable that the content exceeds 20 mol% or less.

The half-crystallization time of the polypropylene resin (B) at 25 ° C is preferably longer than 0.06 seconds. When the half-crystallization time of the polypropylene resin (B) at 25 ° C. exceeds 0.06 seconds, a difference from the half-crystallization time of the propylene homopolymer (A) at 25 ° C. occurs, and the side-by-side crimped fiber is obtained. The crimpability of can be further improved.
The half crystallization time of the polypropylene resin (B) is measured in the same manner as the half crystallization time of the propylene homopolymer (A).

(Method for producing polypropylene resin (B))
The polypropylene resin (B) can be produced, for example, by using a metallocene catalyst as described in WO 2003/087172. In particular, it is preferable to use a transition metal compound in which the ligand forms a crosslinked structure through a crosslinking group, and above all, a transition metal compound in which a crosslinked structure is formed through two crosslinking groups A metallocene catalyst obtained by combining a cocatalyst is preferable.

To give a concrete example,
(I) General formula (I)

[In the formula, M represents a metal element of Group 3 to 10 of the periodic table or a lanthanoid series, E ¹ and E ² are a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group, and a heterocyclopentadienyl group, respectively. A ligand selected from the group consisting of a substituted heterocyclopentadienyl group, an amide group, a phosphide group, a hydrocarbon group and a silicon-containing group, which form a crosslinked structure via A ¹ and A ^2. Further, they may be the same or different from each other, X represents a σ-bonding ligand, and when there are a plurality of Xs, the plurality of Xs may be the same or different, and other X, E ¹ , It may be crosslinked with E ² or Y. Y represents a Lewis base, and when there are plural Y's, the plural Y's may be the same or different and may be crosslinked with other Y, E ¹ , E ² or X, and A ¹ and A ² are A divalent bridging group that binds two ligands, which is a hydrocarbon group having 1 to 20 carbon atoms, a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group, a germanium-containing group, a tin-containing group , -O -, - CO -, - S -, - SO 2 -, - Se -, - NR 1 -, - PR 1 -, - P (O) R 1 -, - BR 1 - or -AlR ¹ - R ¹ represents a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms or a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, which may be the same or different from each other. q is an integer of 1 to 5 and represents [(valence of M) -2], and r is an integer of 0 to 3. ]
And (ii) (ii-1) a compound capable of reacting with the transition metal compound of the component (i) or a derivative thereof to form an ionic complex, and (ii-2) aluminoxane. A polymerization catalyst containing at least one component selected from the group consisting of

  The transition metal compound of the component (i) is preferably a double-bridged transition metal compound having a ligand of (1,2 ′) (2,1 ′), such as (1,2′-dimethylsilylene) ( 2,1′-dimethylsilylene) -bis (3-trimethylsilylmethylindenyl) zirconium dichloride.

  Specific examples of the compound of the component (ii-1) include triethylammonium tetraphenylborate, tri-n-butylammonium tetraphenylborate, trimethylammonium tetraphenylborate, tetraethylammonium tetraphenylborate, methyl tetraphenylborate (tri- n-butyl) ammonium, benzyl (tri-n-butyl) ammonium tetraphenylborate, dimethyldiphenylammonium tetraphenylborate, triphenyl (methyl) ammonium tetraphenylborate, trimethylanilinium tetraphenylborate, methylpyridinium tetraphenylborate, tetra Benzylpyridinium phenylborate, methyl (2-cyanopyridinium) tetraphenylborate, triethylammonium tetrakis (pentafluorophenyl) borate, tri-n-butylammonium tetrakis (pentafluorophenyl) borate, triphenylammonium tetrakis (pentafluorophenyl) borate , Tetra-n-butylammonium tetrakis (pentafluorophenyl) borate, tetraethylammonium tetrakis (pentafluorophenyl) borate, benzyl (tri-n-butyl) ammonium tetrakis (pentafluorophenyl) borate, methyl tetrakis (pentafluorophenyl) borate Diphenylammonium, tetraphenyl (methyl) ammonium tetrakis (pentafluorophenyl) borate, methylanilinium tetrakis (pentafluorophenyl) borate, dimethylanilinium tetrakis (pentafluorophenyl) borate, trimethylanilinium tetrakis (pentafluorophenyl) borate, Methylpyridinium tetrakis (pentafluorophenyl) borate, Benzylpyridinium tetrakis (pentafluorophenyl) borate, Methyl tetrakis (pentafluorophenyl) borate (2-cyanopyridinium), Benzyl tetrakis (pentafluorophenyl) borate (2-cyanopyridinium), Methyl tetrakis (pentafluorophenyl) borate (4-cyanopyridinium), triphenylphosphonium tetrakis (pentafluorophenyl) borate, dimethylanilinium tetrakis [bis (3,5-ditrifluoromethyl) phenyl] borate, ferrocenium tetraphenylborate, Silver tetraphenylborate, trityl tetraphenylborate, tetraphenylporphyrin manganese tetraphenylborate Ferrocenium tetrakis (pentafluorophenyl) borate, Tetrakis (pentafluorophenyl) borate (1,1′-dimethylferrocenium), Decamethylferrocenium tetrakis (pentafluorophenyl) borate, Silver tetrakis (pentafluorophenyl) borate , Trikis (pentafluorophenyl) borate, lithium tetrakis (pentafluorophenyl) borate, sodium tetrakis (pentafluorophenyl) borate, tetrakis (pentafluorophenyl) borate tetraphenylporphyrin manganese, silver tetrafluoroborate, silver hexafluorophosphate, Examples thereof include silver hexafluoroarsenate, silver perchlorate, silver trifluoroacetate, and silver trifluoromethanesulfonate.

  Examples of the aluminoxane as the component (ii-2) include known chain aluminoxanes and cyclic aluminoxanes.

  Also, trimethyl aluminum, triethyl aluminum, triisopropyl aluminum, triisobutyl aluminum, dimethyl aluminum chloride, diethyl aluminum chloride, methyl aluminum dichloride, ethyl aluminum dichloride, dimethyl aluminum fluoride, diisobutyl aluminum hydride, diethyl aluminum hydride, ethyl aluminum sesquichloride, etc. The polypropylene-based resin (B) may be produced by using the organoaluminum compound (1).

  The content of the polypropylene resin (B) in the non-woven fabric is preferably 1% by mass or more, more preferably 3% by mass or more, further preferably 5% by mass or more, and preferably from the viewpoint of spinnability of the fibers. Is 90% by mass or less, more preferably 25% by mass or less, and further preferably 20% by mass or less.

  Further, the content of the polypropylene resin (B) in the total 100% by mass of the propylene homopolymer (A) and the polypropylene resin (B) in the nonwoven fabric is preferably 1 mass from the viewpoint of fiber spinnability. % Or more, more preferably 5% by mass or more, and preferably 90% by mass or less, more preferably 40% by mass or less, further preferably 30% by mass or less.

  The fibers constituting the nonwoven fabric of the present embodiment are not particularly limited, and include side-by-side fibers, core-sheath fibers, eccentric core-sheath fibers, etc., but side-by-side fibers are preferable. Further, it may be crimped fibers, and examples thereof include side-by-side crimped fibers, core-sheath crimped fibers, and eccentric core-sheathed crimped fibers.

In the present specification, “crimped fiber” is used to include a composite spun fiber made by a side-by-side nozzle, an eccentric core-sheath nozzle, a deformed nozzle, or a split nozzle in which different thermoplastic resins are combined. Further, the core-sheath type fiber refers to a fiber whose cross section has a "core" of the inner layer part and a "sheath" of the outer layer part, and the eccentric core-sheath type fiber is the center of gravity position of the inner layer part in its cross-sectional shape. Means a fiber different from the position of the center of gravity of the whole fiber.
Further, in the present specification, in the case of the side-by-side type fiber, one component constituting the side-by-side type fiber is referred to as "first component" and the other component is referred to as "second component". Further, in the case of the core-sheath type fiber, one of the component used for the core portion and the component used for the sheath portion of the core-sheath type fiber is the "first component" and the other is the "second component".

The nonwoven fabric of the present embodiment contains fibers made of a resin composition containing 50% by mass or more and 99% by mass or less of a propylene homopolymer (A) and 1% by mass or more and 50% by mass or less of a polypropylene resin (B). Preferably.
When the fibers constituting the nonwoven fabric of the present embodiment are at least one selected from the group consisting of side-by-side fibers, core-sheath fibers and eccentric core-sheath fibers, the first component of the fibers is a propylene homopolymer ( A fiber made of a resin composition containing 50% by mass or more and 99% by mass or less of A) and 1% by mass or more and 50% by mass or less of the polypropylene resin (B) is preferable.
The non-woven fabric of the present embodiment contains fibers other than the fiber made of a resin composition containing 50% by mass or more and 99% by mass or less of the propylene homopolymer (A) and 1% by mass or more and 50% by mass or less of the polypropylene resin (B). May be included.

(Polyethylene resin (C))
The nonwoven fabric of the present embodiment may further contain a polyethylene resin (C).
The polyethylene resin (C) is not particularly limited, but is preferably a polyethylene resin using a so-called metallocene catalyst having a narrow molecular weight distribution.
The polyethylene resin may be an ethylene homopolymer or a copolymer. When it is a copolymer, the copolymerization ratio of ethylene units exceeds 50 mol%, preferably 60 mol% or more, more preferably 70 mol% or more, further preferably 90 mol% or more, even more preferably 95 mol%. That is all. The copolymerizable monomer is, for example, an α-olefin having 3 to 30 carbon atoms, and specific examples thereof include 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene and the like.

  The half-crystallization time of the polyethylene resin (C) is preferably 0.01 seconds or less from the viewpoint of enhancing the crimpability of the fiber. When the half-crystallization time of the polyethylene resin (C) at 25 ° C. is 0.01 second or less, crimped fibers having higher crimpability can be obtained.

The melt flow rate (MFR) of the polyethylene resin (C) is preferably 10 g / 10 minutes or more, more preferably 15 g / 10 minutes or more, further preferably 20 g / 10 minutes or more, from the viewpoint of enhancing the crimpability of the fiber. And is preferably 50 g / 10 minutes or less, more preferably 45 g / 10 minutes or less, still more preferably 40 g / 10 minutes or less.
The melt flow rate (MFR) of the polyethylene-based resin (C) is measured by the measuring method specified in JIS K7210, and the temperature is 190 ° C. and the load is 2.16 kg.

The melting point of the polyethylene resin (C) is preferably 90 ° C. or higher, more preferably 100 ° C. or higher, further preferably 115 ° C. or higher, and preferably 140 ° C. or lower, from the viewpoint of enhancing the crimpability of the fiber. More preferably, it is 135 ° C. or lower.
The melting point (Tm-D) of the polyethylene resin (C) is measured in the same manner as the melting point (Tm-D) of the propylene homopolymer (A).

Examples of commercially available ethylene homopolymers include "ASPUN ^™ " series (for example, "ASPUN 6850" and "ASPUN 6834") (manufactured by Dow Chemical Co.). Further, commercially available copolymers of ethylene and octene include "Affinity GA1900", "Affinity GA1950", "Affinity EG8185", "Affinity EG8200", "Engage 8137" and "Engage 8180" manufactured by Dow Chemical Company. , “Engage 8400”, etc. (all are trade names).

When the fibers constituting the nonwoven fabric of the present embodiment are at least one selected from the group consisting of side-by-side fibers, core-sheath fibers and eccentric core-sheath fibers, the first component of the fibers is a propylene homopolymer ( The fiber is preferably a resin composition containing 50% by mass or more and 99% by mass or less of A) and 1% by mass or more and 50% by mass or less of the polypropylene resin (B), and the second component of the fiber is a polyethylene resin. A fiber containing (C) is preferable.
The content of the polyethylene resin (C) in the second component is preferably 80% by mass or more, more preferably 85% by mass or more, further preferably 90% by mass or more, when the second component is 100% by mass. The upper limit value is 100% by mass.

  When the fibers constituting the nonwoven fabric of the present embodiment are crimped fibers, the first component containing the propylene homopolymer (A) and the polypropylene resin (B) and the second component containing the polyethylene resin (C). The mass ratio with the components (first component / second component) is preferably 1/9 to 9/1, more preferably 3/7 to 7/3. When the mass ratio of the first component and the second component is within the above range, the crimped nonwoven fabric exhibits crimpability and extensibility.

The nonwoven fabric of the present embodiment may contain any additive as long as the effect of the present invention is not impaired. When the fiber constituting the nonwoven fabric of the present embodiment is at least one selected from the group consisting of side-by-side type fiber, core-sheath type fiber and eccentric core-sheath type fiber, at least the first component and the second component of the fiber One may contain an additive.
Specific examples of additives include foaming agents, crystal nucleating agents, weathering stabilizers, UV absorbers, light stabilizers, heat resistance stabilizers, antistatic agents, mold release agents, flame retardants, synthetic oils, waxes, and electrical properties. Improver, anti-slip agent, anti-blocking agent, viscosity modifier, anti-coloring agent, anti-fog agent, lubricant, pigment, dye, plasticizer, softening agent, anti-aging agent, hydrochloric acid absorbent, chlorine scavenger, antioxidant , An anti-adhesive agent and the like.

  The fiber diameter of the fibers constituting the nonwoven fabric of the present embodiment is preferably 1.8 denier or less, more preferably 1.6 denier or less, and further preferably 1.4 denier or less from the viewpoint of the feel of the nonwoven fabric. Although the lower limit of the fiber diameter is not particularly limited, it is preferably 0.5 denier or more, more preferably 0.6 denier or more, and further preferably 0.7 denier or more from the viewpoint of ease of production.

  The non-woven fabric of this embodiment may be a multi-layer non-woven fabric formed by laminating two or more layers. In that case, from the viewpoint of the smoothness of the surface, it is preferable that at least one layer of the nonwoven fabric constituting the outer layer of the multilayer nonwoven fabric is the above-mentioned fiber.

The bulkiness of the nonwoven fabric of the present embodiment is preferably 500 μm or more, more preferably 550 μm or more, still more preferably 600 μm or more, and the larger the value, the more preferable.
In the present invention, the bulkiness of the non-woven fabric is determined by stacking ten non-woven fabric test pieces each having a length of 50 mm and a width of 50 mm, placing a 1.9 g metal plate thereon, and measuring the thickness of the stacked test pieces. I asked for.

From the viewpoint of the bulkiness of the nonwoven fabric, the nonwoven fabric of the present embodiment has a thickness / unit weight of 25 cm ³ / g or more, preferably 30 cm ³ / g or more, and the larger the value, the more preferable. The upper limit value is 100 cm ³ / g or less from the viewpoint of ease of manufacturing.
The value of the thickness / area weight is obtained from the value of the bulkiness of the nonwoven fabric measured by the above method and the value of the area weight of the nonwoven fabric.

  Further, the nonwoven fabric of the present embodiment has a tensile strength in the direction perpendicular to the machine direction (MD) (CD) of 5 N / 5 cm or more, preferably 6 N / cm or more, more preferably 7 N / cm or more, and further preferably Is 10 N / cm or more, and the larger the value, the more preferable. The tensile strength in the CD direction is measured by the method described in Examples described later.

<Method of manufacturing non-woven fabric>
The manufacturing method of the nonwoven fabric of the present embodiment, the melting point (Tm-D) measured by a differential scanning calorimeter (DSC) is 50% by mass or more and 99% by mass or less of a propylene homopolymer (A) having a melting point of more than 120 ° C. A step of fusing a fiber containing a polypropylene resin (B) having a melting point (Tm-D) of 120 ° C. or less, measured by a differential scanning calorimeter (DSC), of 1% by mass or more and 50% by mass or less with a hot air knife. including. By fusing the fibers with a hot air knife, a sufficiently bulky nonwoven fabric can be obtained.

  Usually, in the spun bond method, the melt-kneaded resin composition is spun, stretched, to form continuous filaments by opening, and continuous filaments are deposited on the moving collection surface in a continuous process, A non-woven fabric is manufactured by entanglement. According to this method, a nonwoven fabric can be continuously manufactured, and since the fibers constituting the nonwoven fabric are continuous long fibers that have been stretched, the strength is high. In the spunbond method, fibers can be produced by extruding a molten polymer from a large nozzle having thousands of holes or a small nozzle group having holes of about 40, for example. After exiting the nozzle, the molten fiber is cooled by a cross-flow cold air system, then pulled away from the nozzle and drawn with high velocity air. There are usually two types of air damping methods, both of which use the Venturi effect. The first method is to draw the filaments using a suction slot (slot drawing), nozzle width or machine width. The second method draws the filament through a nozzle or a suction gun. The filaments formed in this way are collected on a screen (wire) or on a pore forming belt to form a web.

  In the method for manufacturing the nonwoven fabric of the present embodiment, hot air is applied to the obtained web using a hot air knife to fuse the fibers.

  Here, the hot air knife is a device that blows out hot air from a slit having a constant width. Immediately after collecting the fibers obtained above on the moving net surface, the hot air blown from the hot air knife is applied to the fibers to fuse them together. The temperature of the hot air is preferably 120 to 150 ° C., and the pressure (air pressure) of the hot air is preferably 1,000 to 2,500 Pa.

  Further, in this embodiment, in order to obtain a sufficiently bulky nonwoven fabric, it is preferable that the web obtained by collecting the fibers is not passed through a compression roll (compression roll). That is, in the method for manufacturing the nonwoven fabric of the present embodiment, it is preferable not to use the compression roll.

  After fusing the fibers, as in the conventional method, the fiber bundle is passed between heating calender rolls, and the raised portion on one roll is a portion including an area of 10% or more and 40% or less of the web. It is preferred that they are combined to form a nonwoven fabric.

The method for manufacturing a nonwoven fabric of this embodiment can be applied to the manufacture of a nonwoven fabric composed of crimped fibers.
An example of the method for producing the side-by-side crimped fiber is shown below. The side-by-side type crimped fiber is obtained by melt-extruding at least two resin components using separate extruders, and using a special spinneret as disclosed in, for example, US Pat. No. 3,671,379. It is produced by a melt spinning method in which molten resins extruded and melt-extruded from different extruders are combined and discharged to form a fiber, which is then cooled and solidified. Here, in the above step, the higher the spinning speed is, the more the crimpability of the obtained side-by-side crimped fiber can be enhanced, which is preferable.
In the method for producing the side-by-side crimped fiber in the present embodiment, a desired fiber can be produced without a post-treatment step such as heating and drawing after spinning, but if necessary, post-treatment A step may be adopted, and for example, the crimping rate of the fiber may be increased by heating at 100 to 150 ° C., stretching at 1.2 to 5 times, or a combination thereof.

(Fiber products)
The fiber product using the nonwoven fabric of the present embodiment is not particularly limited, but the following fiber products can be given as examples. That is, members for disposable diapers, elastic members for diaper covers, elastic members for sanitary products, elastic members for hygiene products, elastic tapes, bandages, elastic members for clothing, insulating materials for clothing, heat insulating materials for clothing, Protective clothing, hats, masks, gloves, supporters, elastic bandages, base fabrics for poultices, anti-slip fabrics, vibration absorbers, finger cots, air filters for clean rooms, electret filters with electret processing, separators, and heat insulating materials. , Coffee bags, food packaging materials, automobile ceiling skin materials, soundproofing materials, cushioning materials, speaker dustproof materials, air cleaner materials, insulator skins, backing materials, adhesive non-woven fabric sheets, door trim and other various automotive parts, and copying machine cleaning. Examples include various cleaning materials such as materials, front and back materials for carpets, agricultural cloth, wood drains, shoe members such as skins of sports shoes, bag members, industrial sealing materials, wiping materials, and sheets. ..

  Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

[Semi-crystallization time]
FLASH DSC (manufactured by METTLER TOLEDO Co., Ltd.) was used for measurement by the following method.
(1) The sample was heated at 230 ° C. for 2 minutes to be melted, then cooled to 25 ° C. at 2,000 ° C./sec, and the time change of the heat generation amount in the isothermal crystallization process at 25 ° C. was measured.
(2) When the integrated value of the calorific value from the start of the isothermal crystallization to the completion of the crystallization is 100%, the time from the start of the isothermal crystallization until the integrated value of the calorific value reaches 50% is half-crystallized. It was time.

[Melt flow rate (MFR)]
According to JIS K7210, the propylene homopolymer (A) and the polypropylene resin (B) have a temperature of 230 ° C. and a load of 2.16 kg, and the polyethylene resin (C) has a temperature of 190 ° C. and a load of 2. It was measured under the condition of 16 kg.

[DSC measurement]
Using a differential scanning calorimeter ("DSC-7" manufactured by Perkin-Elmer Co., Ltd.), 10 mg of the sample was kept under a nitrogen atmosphere at -10 ° C for 5 minutes and then heated at 10 ° C / minute. The melting endotherm (ΔH-D) was obtained from the melting endotherm curve. Further, the melting point (Tm-D) was determined from the peak top of the peak observed on the highest temperature side of the obtained melting endothermic curve.
The melting endotherm (ΔH-D) is a differential scanning calorimeter (manufactured by Perkin-Elmer Co., Ltd.) with a line connecting the low-temperature side without heat change and the high-temperature side with no heat change as a baseline. , "DSC-7"), and the area surrounded by the line portion including the peak of the melting endothermic curve obtained by the DSC measurement and the baseline is calculated.

[Measurement of weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn)]
The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by the gel permeation chromatography (GPC) method to determine the molecular weight distribution (Mw / Mn). For the measurement, the following equipment and conditions were used to obtain a polystyrene-equivalent weight average molecular weight and number average molecular weight. The molecular weight distribution (Mw / Mn) is a value calculated from these weight average molecular weight (Mw) and number average molecular weight (Mn).
<GPC measuring device>
Column: "TOSO GMHHR-H (S) HT" manufactured by Tosoh Corporation
Detector: RI detection for liquid chromatogram "WATERS 150C" manufactured by Waters Corporation
<Measurement conditions>
Solvent: 1,2,4-trichlorobenzene Measurement temperature: 145 ° C
Flow rate: 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)

(Production of Propylene Polymer (B1))
In a 20 L internal volume stainless reactor equipped with a stirrer, n-heptane 20 L / hr, triisobutylaluminum 15 mmol / hr, dimethylanilinium tetrakispentafluorophenylborate, (1,2′-dimethylsilylene) A catalyst component obtained by previously contacting (2,1′-dimethylsilylene) -bis (3-trimethylsilylmethylindenyl) zirconium dichloride and triisobutylaluminum with propylene at a mass ratio of 1: 2: 20 is converted to zirconium. At 6 μmol / hr.
At a polymerization temperature of 75 ° C., propylene and hydrogen were continuously supplied so that the gas phase hydrogen concentration was 24 mol% and the total pressure in the reactor was 1.0 MPa · G. A propylene-based polymer (B1) was obtained by adding an antioxidant to the obtained polymerization solution so that the content ratio was 1,000 mass ppm, and then removing n-heptane as a solvent. ..
The above measurement was performed on the obtained propylene polymer (B1). The results are shown in Table 1.

(Production of Propylene Polymer (B2))
In a 20 L internal volume stainless reactor equipped with a stirrer, n-heptane 20 L / hr, triisobutylaluminum 15 mmol / hr, dimethylanilinium tetrakispentafluorophenylborate, (1,2′-dimethylsilylene) A catalyst component obtained by previously contacting (2,1′-dimethylsilylene) -bis (3-trimethylsilylmethylindenyl) zirconium dichloride and triisobutylaluminum with propylene at a mass ratio of 1: 2: 20 is converted to zirconium. At 6 μmol / hr.
At a polymerization temperature of 65 ° C., propylene and hydrogen were continuously supplied so that the gas phase hydrogen concentration was 8 mol% and the total pressure in the reactor was 1.0 MPa · G. A propylene-based polymer (B2) was obtained by adding an antioxidant to the obtained polymerization solution so that the content ratio was 1,000 mass ppm, and then removing n-heptane as a solvent. ..
The above measurement was performed on the obtained propylene polymer (B2). The results are shown in Table 1.

Moreover, the following raw materials were used in the following examples.
<Propylene homopolymer (A)>
Propylene homopolymer (A1): "HG475FB" (manufactured by Borealis)
<Polyethylene resin (C)>
Polyethylene resin (C1): "ASPUN 6850" (manufactured by Dow Chemical Co.)
<Other ingredients>
Anti-slip agent: erucic acid amide, "EA-10" (manufactured by Dainichiseika Kogyo Co., Ltd.)

  Table 2 shows the half-crystallization time, MFR and melting point (Tm-D) of the propylene homopolymer (A1) and the polyethylene resin (C1) measured by the above method.

Example 1
(Preparation of the first component)
A thermoplastic resin composition was obtained by kneading 78 mass% of a propylene homopolymer (A1), 20 mass% of a propylene polymer (B1), and 2 mass% of erucic acid amide as an antislip agent.

(Preparation of the second component)
A thermoplastic resin composition was obtained by kneading 98 mass% of propylene homopolymer (A1) and 2 mass% of erucic acid amide as an antislip agent.

(Manufacture of side-by-side type fiber)
The molding of the side-by-side type fiber was carried out using a composite melt spinning machine bi-component spinning machine having two extruders. The first component and the second component are melt-extruded at a resin temperature of 240 ° C. by using separate single-screw extruders, and 265 kg / nozzle per nozzle from a side-by-side composite nozzle (hole number 6800 holes) having a nozzle diameter of 0.60 mm. The molten resin was discharged at a discharge amount of h so that the mass ratio of the first component: the second component was 70:30, and spun to obtain a side-by-side crimped fiber.

(Manufacture of spunbonded nonwoven fabric composed of side-by-side type fibers)
The obtained fiber is sucked with a cabin pressure of 6,500 Pa and collected on a moving net surface, and immediately after that, hot air of 140 ° C. is blown with a hot air knife (manufactured by Rycofil Co., Ltd.) of 1,900 Pa. The pressure applied to the fiber. The fiber bundle collected on the net surface was embossed with a heat roll having a calendering temperature of 143 ° C./135° C. at a linear pressure of 60 N / mm and a line speed of 205 m / min, and wound on a take-up roll.

Comparative Example 1
(Preparation of first component and second component)
A thermoplastic resin composition was obtained by kneading 93 mass% of a propylene homopolymer (A1), 5 mass% of a propylene polymer (B2), and 2 mass% of erucic acid amide as an antislip agent.

(Manufacture of side-by-side type fiber)
The first component and the second component are melt-extruded at a resin temperature of 240 ° C. by using separate single-screw extruders, and 265 kg / nozzle per nozzle from a side-by-side composite nozzle (hole number 6800 holes) having a nozzle diameter of 0.60 mm. The molten resin was discharged at a discharge amount of h so that the mass ratio of the first component: the second component was 50:50 and spun to obtain a side-by-side crimped fiber.

(Manufacture of spunbonded nonwoven fabric composed of side-by-side type fibers)
The obtained fiber was sucked with a cabin pressure of 5,500 Pa and collected on the moving net surface. The fiber bundle collected on the net surface was embossed with a heat roll having a calender temperature of 131 ° C / 126 ° C at a linear pressure of 60 N / mm and a line speed of 278 m / min, and wound on a take-up roll.

Example 2
(Preparation of the first component)
A thermoplastic resin composition was obtained by kneading 80% by mass of the propylene homopolymer (A1) and 20% by mass of the propylene polymer (B2).

(Preparation of the second component)
Only the polyethylene resin (C1) was used as the second component.

(Production of side-by-side crimped fiber)
The first component and the second component are melt-extruded using a separate single-screw extruder at a resin temperature of 240 ° C., and a side-by-side compound nozzle having a nozzle diameter of 0.60 mm (holes of 6800 holes) is used to discharge 220 kg / nozzle. The molten resin was discharged at a discharge amount of h so that the mass ratio of the first component: the second component was 20:80 and spun to obtain a side-by-side crimped fiber.

(Manufacture of spunbonded nonwoven fabric composed of side-by-side crimped fibers)
The obtained fiber was sucked with a cabin pressure of 6,000 Pa and collected on a moving net surface, and immediately after that, hot air of 135 ° C. was blown with 1,920 Pa of hot air using a hot air knife (manufactured by Lycofil). The pressure applied to the fiber. The fiber bundle collected on the net surface was embossed with a heat roll having a calendar temperature of 135 ° C./130° C. at a linear pressure of 60 N / mm and a line speed of 163 m / min, and wound on a take-up roll.

[Measurement of unit weight]
The mass of the obtained nonwoven fabric of 20 cm × 20 cm was measured, and the basis weight (gsm) was measured.

[Measurement of fineness (fiber diameter)]
The fibers in the nonwoven fabric are observed using a polarization microscope, the average value (d) of 100 randomly selected fiber diameters is measured, and the density of the resin (ρ = 900,000 g / m ³ ) is used to measure the nonwoven fabric. The fineness of the sample was calculated from the following formula.
Fineness (denier) = ρ × π × (d / 2) ² × 9000

[Tensile test]
From the obtained nonwoven fabric, a test piece having a length of 150 mm and a width of 50 mm was sampled in the machine direction (MD) and the direction perpendicular to the machine direction (CD). Using a tensile tester (manufactured by Shimadzu Corp., Autograph AG-I), the initial length L ₀ was set to 100 mm, the sample was stretched at a tensile rate of 300 mm / min, and the strain and load during the stretching process were measured. The maximum strength in the process of breaking the nonwoven fabric was defined as the strength of the nonwoven fabric.

[Measurement of bulkiness]
A test piece having a length of 50 mm and a width of 50 mm was sampled from the obtained nonwoven fabric. Ten of the test pieces were stacked, a 1.9 g metal plate was placed on the stacked test pieces, and the thickness of the stacked test pieces was measured. The higher the numerical value of the thickness, the more bulky the nonwoven fabric is.

[Measurement of the number of crimps]
According to the method for measuring the number of crimps defined in JIS L1015: 2010, the measurement was performed using an automatic crimp elastic modulus measuring device. One fiber was extracted from the cotton sample before embossing so that tension was not applied to the fiber, and the length when a 25 mm sample was loaded with an initial load of 0.18 mN / tex was measured. The number of crimps was counted and the number of crimps per 25 mm was obtained. The higher the number of crimps, the higher the crimpability of the fiber and the nonwoven fabric.

[Measurement of crimp ratio]
About 10 cm of the obtained side-by-side crimped fiber was collected from a take-up roll, one fiber was separated from the bundled yarn, and the number of windings per 1 mm was measured with a microscope. The number of measurement samples was 10, and the average value was the crimp rate. A higher value of the crimp rate indicates that the fibers are crimped, which means that bulky fibers and nonwoven fabrics can be obtained.

  As is clear from the comparison between Example 1 and Comparative Example 1, according to the present invention, a sufficiently bulky nonwoven fabric can be provided. Further, as is clear from Example 2, according to the present invention, a sufficiently bulky nonwoven fabric can be provided even with crimped fibers.

Claims (11)

10 mass% or more and 99 mass% or less of the propylene homopolymer (A) whose melting point (Tm-D) measured by a differential scanning calorimeter (DSC) exceeds 120 ° C., measured by a differential scanning calorimeter (DSC). The melting point (Tm-D) of the polypropylene resin (B) having a melting point (Tm-D) of 120 ° C. or less is 1% by mass or more and 90% by mass or less, and the thickness / unit weight is 25 cm ³ / g or more and 100 cm ³ / g or less and the CD direction A non-woven fabric having a tensile strength of 5 N / 5 cm or more.   The non-woven fabric according to claim 1, wherein the fibers constituting the non-woven fabric have a fiber diameter of 1.8 denier or less.   The nonwoven fabric according to claim 1 or 2, wherein the propylene homopolymer (A) has a melt flow rate (MFR) at 230 ° C of 5 g / 10 minutes or more and 100 g / 10 minutes or less.   The nonwoven fabric according to any one of claims 1 to 3, wherein the polypropylene resin (B) has a melt flow rate (MFR) at 230 ° C of 5 g / 10 minutes or more and 5,000 g / 10 minutes or less.   5. The melting endotherm (ΔH-D) of the polypropylene resin (B) measured by a differential scanning calorimeter (DSC) is 0 J / g or more and 80 J / g or less. The non-woven fabric described in.   The nonwoven fabric according to claim 1, wherein the polypropylene resin (B) has a molecular weight distribution (Mw / Mn) of 1.5 or more and 3.5 or less.   The nonwoven fabric according to any one of claims 1 to 6, wherein the polypropylene resin (B) is a propylene homopolymer.   The non-woven fabric according to any one of claims 1 to 7, further comprising a polyethylene resin (C).   The non-woven fabric according to claim 8, wherein the polyethylene resin (C) has a melt flow rate (MFR) at 190 ° C of 10 g / 10 minutes or more and 50 g / 10 minutes or less.   10 mass% or more and 99 mass% or less of the propylene homopolymer (A) whose melting point (Tm-D) measured by a differential scanning calorimeter (DSC) exceeds 120 ° C., measured by a differential scanning calorimeter (DSC). And a melting point (Tm-D) of 120 [deg.] C. or less of the polypropylene-based resin (B) in an amount of 1% by mass to 90% by mass.   The method for manufacturing a nonwoven fabric according to claim 10, wherein a compression roll is not used.