WO2019124408A1 - Meltblown non-woven fabric - Google Patents

Meltblown non-woven fabric Download PDF

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Publication number
WO2019124408A1
WO2019124408A1 PCT/JP2018/046653 JP2018046653W WO2019124408A1 WO 2019124408 A1 WO2019124408 A1 WO 2019124408A1 JP 2018046653 W JP2018046653 W JP 2018046653W WO 2019124408 A1 WO2019124408 A1 WO 2019124408A1
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WO
WIPO (PCT)
Prior art keywords
nonwoven fabric
fibers
melt
less
straightness
Prior art date
Application number
PCT/JP2018/046653
Other languages
French (fr)
Japanese (ja)
Inventor
竜規 伊藤
正和 佐瀬
太一 新津
Original Assignee
花王株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2018215397A external-priority patent/JP6771012B2/en
Application filed by 花王株式会社 filed Critical 花王株式会社
Priority to MYPI2020003174A priority Critical patent/MY188653A/en
Priority to RU2020123901A priority patent/RU2754413C1/en
Priority to KR1020207018580A priority patent/KR102233538B1/en
Priority to CN201880082713.3A priority patent/CN111527254B/en
Priority to EP18890630.9A priority patent/EP3730685A4/en
Publication of WO2019124408A1 publication Critical patent/WO2019124408A1/en

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/51—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the outer layers
    • A61F13/514—Backsheet, i.e. the impermeable cover or layer furthest from the skin
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
    • A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
    • A61L15/22—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons containing macromolecular materials
    • A61L15/24—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives thereof
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
    • D04H3/005—Synthetic yarns or filaments
    • D04H3/007—Addition polymers
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
    • D04H3/08—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating
    • D04H3/16—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating with bonds between thermoplastic filaments produced in association with filament formation, e.g. immediately following extrusion

Definitions

  • the present invention relates to a meltblown nonwoven fabric produced by a meltblowing method.
  • a meltblown nonwoven fabric is a nonwoven fabric produced by a meltblowing method, and it is known that the distance between the fibers is small because the thin fibers are closely overlapped with each other, and it has high water resistance (Patent Document 1).
  • the melt-blowing method is a spinning step of drawing a molten thermoplastic resin composition into a fibrous form by blowing out a molten thermoplastic resin composition from a die having a plurality of nozzles at a high speed and a high velocity, and the obtained fibers are deposited on a collecting surface And a depositing step for fusing, suitable for producing fine fibers.
  • Patent Document 1 International Publication No. 2012/102398
  • the present invention is a melt-blown nonwoven fabric having an average fiber diameter of 4 ⁇ m or less
  • a meltblown nonwoven fabric is provided, which has a first direction along the plane of the meltblown nonwoven fabric and in which the straightness of fibers is the highest, and a second direction orthogonal to the first direction.
  • the straightness of the fibers in the first direction and the second direction is 35% or more.
  • the meltblown nonwoven fabric satisfies one or more conditions selected from the following (I), (II) and (III).
  • the straightness of fibers in the first direction and the second direction is 35% or more.
  • the ratio of the straightness of fibers in the first direction to the straightness of fibers in the second direction is 1 or more. 5 or less.
  • the water pressure resistance of the melt-blown non-woven fabric is 100 mm H 2 O or more and 10000 mm H 2 O or less, and optionally, the water-pressure resistant retention when the melt-blown non-woven fabric is deformed in the second direction is 85% or more.
  • the melt-blown nonwoven fabric of (I) has a ratio of a linear movement ratio of fibers in the first direction to a linear movement ratio of fibers in the second direction (a linear movement ratio of fibers in the first direction / the second direction
  • the straightness of fibers is 1 or more and 2.5 or less.
  • the above-mentioned (I) or the (II) melt-blown nonwoven fabric has a water pressure resistance of 100 mm H 2 O or more and 10000 mm H 2 O or less.
  • the melt-blown nonwoven fabric of (I) or (II) has a water pressure resistance retention of 85% or more when the melt-blown nonwoven fabric is deformed in the second direction.
  • the meltblown non-woven fabric has a filling rate of 3% or more and / or 30% or less.
  • the heat of fusion of the fibers is greater than 5 mJ / mg and / or less than 94 mJ / mg.
  • the present invention is a melt-blown nonwoven fabric having an average fiber diameter of 0.1 ⁇ m to 4 ⁇ m,
  • the straightness of the fibers in the first direction along which the meltblown nonwoven fabric has the highest straightness of the fibers and in the second direction orthogonal to the first direction is 35% or more.
  • the ratio of the straightness of fibers in the first direction to the straightness of fibers in the second direction is 1 or more and 2.5 or less Yes,
  • the filling rate is 3% or more and 30% or less
  • the melt-blown nonwoven fabric is provided, wherein the heat of fusion of the fibers is more than 5 mJ / mg and less than 94 mJ / mg.
  • the melt-blown nonwoven fabric has a ratio of a straightness of fibers in the first direction to a straightness of fibers in the second direction (a straightness of fibers in the first direction / a straightness of fibers in the second direction ) Is 1 or more and 1.9 or less.
  • the first direction, the second direction, and the rectilinear rate are determined by the following procedures (a) to (g).
  • N (0), N (1) and N (2) respectively represent the following.
  • N (0) is the number of fibers continuously extending from one end to the other end of the SEM image
  • N (1) is the number of fibers crossing one end in the long side
  • N (2) is the length in the long side
  • the meltblown non-woven fabric has a filling factor of 6% or more and / or 15% or less.
  • the meltblown nonwoven has a formation index of at least 30, and / or at most 300, optionally at most 200.
  • the heat of fusion of the fiber is 20 mJ / mg or more and / or 80 mJ / mg or less.
  • this invention provides the leak-proof sheet which has the said melt-blown nonwoven fabric. Further, according to the present invention, there is provided a liquid-permeable top sheet disposed on the side facing the skin, Liquid-repellent back sheet disposed on the non-skin facing side, And an absorbent disposed between the sheets. The back sheet provides the absorbent article which is the leakproof sheet.
  • the present invention also provides a method for producing a melt-blown nonwoven fabric, including a spinning step of discharging a molten thermoplastic resin composition from a nozzle and forming it into a fibrous form by air flow.
  • the manufacturing method manufactures a meltblown nonwoven fabric having an average fiber diameter of 4 ⁇ m or less.
  • the temperature of the air flow is equal to or higher than the melting point of the thermoplastic resin composition.
  • the heat of fusion of the thermoplastic resin composition is more than 5 mJ / mg and / or less than 94 mJ / mg.
  • the temperature of the air flow is 260 ° C. or less, optionally 250 ° C. or less, optionally 240 ° C. or less.
  • the manufacturing method contains two or more kinds of polyolefins different in the heat of fusion in the thermoplastic resin composition.
  • the thermoplastic resin composition comprises a polyolefin comprising a first polyolefin having a heat of fusion of 94 mJ / mg or more and / or a second polyolefin having a heat of fusion of less than 94 mJ / mg. contains.
  • the second polyolefin is one or more selected from low crystalline polypropylene having MFR 400 g / 10 min or more, low crystalline polypropylene having MFR 400 g / 10 min or less, and polypropylene based elastomer having MFR 400 g / 10 min or less including.
  • the polyolefin comprises one or more selected from homopolymers of alpha-olefins and copolymers of two or more alpha-olefins.
  • the ⁇ -olefin homopolymer includes one or more selected from a high crystalline polyolefin and a low crystalline polyolefin.
  • the copolymer of two or more ⁇ -olefins includes one or more selected from low crystalline olefin elastomers and amorphous olefin elastomers.
  • the first polyolefin comprises a high crystalline polyolefin, and the high crystalline polyolefin has a melt flow rate of 100 g / 10 min or more and / or 2000 g / 10 min or less.
  • the first polyolefin comprises a high crystalline polyolefin, and the high crystalline polyolefin has a melt flow rate of 300 g / 10 min or more and / or 1800 g / 10 min or less.
  • the content of the second polyolefin relative to the total amount of the first polyolefin and the second polyolefin is When the second polyolefin is a low crystalline polypropylene having a MFR of 400 g / 10 min or more, the content is 50 mass% or more and / or 70 mass% or less, When the second polyolefin is a low crystalline polypropylene having a MFR of less than 400 g / 10 min or a polypropylene elastomer having a MFR of less than 400 g / 10 min, the content is 10% by mass or more and / or 15% by mass or less.
  • the manufacturing method further includes a depositing step of depositing the fibers obtained in the spinning step on the collecting surface.
  • the manufacturing method sets the distance between the nozzle and the collection surface to 400 mm or less, optionally 300 mm or less, optionally 150 mm or less, and / or 50 mm or more.
  • the manufacturing method includes a heating step of heating the fibers obtained in the spinning step before the fibers obtained in the spinning step are deposited on the collecting surface.
  • the present invention also provides a meltblown nonwoven fabric produced by the above production method.
  • FIG. 1 is a schematic view showing an example of a SEM image of a meltblown nonwoven fabric according to the present invention.
  • MD direction Machine Direction
  • CD direction CD direction
  • the inventors have found that the strength in the MD direction of the meltblown nonwoven fabric is sufficient but the strength in the CD direction is low. For this reason, in the melt-blown nonwoven fabric, for example, when a tensile load is applied in the CD direction to cause deformation, the distance between the fibers is likely to be extended, and a gap may be generated to significantly reduce the water resistance. In general, when using a meltblown nonwoven fabric at a location where there is a possibility that deformation may occur due to load, a high-strength spunbond nonwoven fabric or air through nonwoven fabric is used so as to cover the meltblown nonwoven fabric.
  • the present invention relates to a meltblown non-woven fabric in which a decrease in water pressure resistance due to deformation is suppressed.
  • the melt-blown nonwoven fabric according to the present invention can suppress a decrease in water pressure resistance due to deformation.
  • the average fiber diameter of the contained fibers is 4 ⁇ m or less.
  • the average fiber diameter is preferably 3.6 ⁇ m or less, more preferably 3.2 ⁇ m or less, still more preferably 3 ⁇ m or less, and particularly preferably 2.5 ⁇ m or less, and is 2 ⁇ m or less. Is particularly preferred.
  • the average fiber diameter is preferably 0.1 ⁇ m or more, more preferably 0.2 ⁇ m or more, and still more preferably 0.3 ⁇ m or more.
  • the average fiber diameter is preferably 0.1 ⁇ m to 4 ⁇ m, more preferably 0.2 ⁇ m to 3.6 ⁇ m, and still more preferably 0.3 ⁇ m to 3.2 ⁇ m.
  • the thickness is more preferably 0.3 ⁇ m or more and 3 ⁇ m or less, particularly preferably 0.3 ⁇ m or more and 2.5 ⁇ m or less, and particularly preferably 0.3 ⁇ m or more and 2 ⁇ m or less.
  • the average fiber diameter of the meltblown nonwoven fabric according to the present invention is calculated as follows. First, using a scanning electron microscope, an SEM image is taken in a field of view where 20 to 60 fibers appear. The fiber diameter is measured once for each of all the fibers in the field of view to obtain an average value. The 10 nm digit of the average value is rounded off to obtain an average fiber diameter. The unit of average fiber diameter is ⁇ m.
  • the melt-blown nonwoven fabric according to the present invention has a first direction along which the melt-blown nonwoven fabric has the highest straightness of fibers and a second direction orthogonal to the first direction.
  • the straightness of the fiber in the first direction and the straightness of the fiber in the second direction are each preferably 35% or more, more preferably 38% or more, and still more preferably 40% or more. Further, it is preferably 90% or less, more preferably 85% or less, and still more preferably 80% or less. Specifically, it is preferably 35% or more and 90% or less, more preferably 38% or more and 85% or less, and still more preferably 40% or more and 80% or less.
  • the first direction is preferably the MD direction at the time of manufacture.
  • the second direction is preferably the CD direction at the time of manufacture. Since the straightness of the fiber in the first direction and the straightness of the fiber in the second direction are both lower than or equal to the lower limit, a gap is formed between the fibers regardless of deformation in either the first direction or the second direction. It becomes difficult to suppress the decrease in water pressure resistance.
  • the direction in which the rectilinear rate of fibers is the highest is taken as the first direction, and the direction orthogonal to the first direction is taken as the second direction.
  • the ratio (A / B) of the rectilinear rate (A) of the fiber in the first direction to the rectilinear rate (B) of the fiber in the second direction is preferably 1 or more, and preferably 2.5 or less, It is more preferably 2.1 or less and still more preferably 1.9 or less.
  • the ratio (A / B) is preferably 1 or more and 2.5 or less, more preferably 1 or more and 2.1 or less, and still more preferably 1 or more and 1.9 or less.
  • the ratio (A / B) is less than or equal to the upper limit, it is difficult to form a gap between the fibers regardless of deformation in either the first direction or the second direction, and a decrease in water pressure resistance is suppressed.
  • the melt-blown nonwoven fabric according to the present invention preferably has a water pressure resistance of 100 mm H 2 O or more, and preferably 10,000 mm H 2 O or less. It is preferable that the water pressure resistance retention rate is 85% or more when the meltblown nonwoven fabric is deformed in a second direction orthogonal to the first direction along the plane of the meltblown nonwoven fabric and in which the rectilinear rate of fibers is the highest. The above is more preferable, 90% or more is more preferable, and 100% or less is realistic.
  • the water pressure resistance retention rate when deformed in the second direction is equal to or higher than this lower limit, so that a gap is formed between fibers regardless of deformation in either the first direction or the second direction. It is hard to be done. For this reason, even if it deform
  • the first direction in which the rectilinear rate of fibers of the melt-blown nonwoven fabric according to the present invention is the highest, the second direction orthogonal to the first direction, and the rectilinear rate (A) of fibers in the first direction and the rectilinear rate of fibers in the second direction (B) can be determined by the following procedures (a) to (g).
  • "the first direction in which the rectilinear rate of fibers is the highest” means the direction determined by the following procedures (a) to (g). It may be different from the high direction.
  • N (0), N (1) and N (2) respectively represent the following.
  • N (0) is the number of fibers continuously extending from one end to the other end of the SEM image
  • N (1) is the number of fibers crossing one end in the long side
  • N (2) is the length in the long side
  • the number of fibers crossing the end The fibers reaching one end in the long side direction of the SEM image are referred to as "fibers crossing at one end in the longitudinal direction". The same applies to the other end.
  • FIG. 1 is a schematic view showing an example of an SEM image in which the long side direction is parallel to the first direction.
  • the fiber is shown as a straight line for simplification of illustration, the actual fiber is not necessarily linear.
  • the number of fibers shown in the SEM image may differ from the actual one. In the case of the SEM image shown in FIG. 1, the number of fibers intersecting the left end in the long side direction is six at intersections a to f, and the number of fibers intersecting the right end in the long side direction is six at intersections g to l It is.
  • the angle ⁇ ° at the time of changing the visual field may be an arbitrary value, preferably 15 ° or less, more preferably 10 ° or less, and further preferably 5 ° or less preferable.
  • the “direction in which the rate of rectilinear movement is highest” may be different due to different conditions such as the observation position and the angle ⁇ . In that case, the direction in which the rate of rectilinear movement is the highest among the plurality of measurement results can be adopted as the first direction.
  • the melt-blown nonwoven fabric according to the present invention has a rectilinear rate of fibers of 35% or more in any of the first direction in which the rectilinear rate of fibers is the highest and the second direction orthogonal to it. Is less likely to occur, and a decrease in water pressure resistance can be suppressed. Furthermore, even if the melt-blown nonwoven fabric according to the present invention is deformed without being laminated with the spun bond nonwoven fabric or the air through nonwoven fabric, the decrease in water pressure resistance is suppressed.
  • the reduction in water pressure resistance due to the deformation of the meltblown nonwoven fabric according to the present invention can be evaluated by the ratio of water pressure resistance after deformation to the water pressure resistance before deformation (water pressure resistance retention rate).
  • the water pressure resistance and the water pressure resistance are measured by the method described later.
  • the meltblown nonwoven may be integrated with a base such as a spunbond nonwoven or an air through nonwoven by heat embossing. The integrated meltblown nonwoven is stretched in an integrated state and then the water pressure resistance is measured. When the melt-blown nonwoven fabric is integrated with the resin film by heat embossing, only the film in the non-embossed area is removed to make the measurement object.
  • the melt-blown nonwoven fabric according to the present invention comprises adjusting the heat of fusion of the thermoplastic resin composition constituting the fiber, adjusting the temperature of the air flow in the spinning step, or heating the fiber before the depositing step after the spinning step. It can be obtained by The temperature of the air flow in the spinning process and the heating of the fibers will be described later.
  • a thermoplastic resin composition is a mixture which contains 1 or more types of thermoplastic resin, and contains other components suitably as needed.
  • the heat of fusion of the thermoplastic resin composition is preferably greater than 5 mJ / mg, more preferably 10 mJ / mg or more, and particularly preferably 20 mJ / mg or more from the viewpoint of spinnability. Further, from the viewpoint of obtaining soft fibers and from the viewpoint of narrowing the fibers in a low temperature hot air temperature range, it is preferably less than 94 mJ / mg, more preferably 90 mJ / mg or less, and 80 mJ / mg or less Is more preferably 75 mJ / mg or less, particularly preferably 45 mJ / mg or less, and particularly preferably 35 mJ / mg or less.
  • the heat of fusion is preferably greater than 5 mJ / mg and less than 94 mJ / mg, more preferably 10 mJ / mg to 90 mJ / mg, and more preferably 20 mJ / mg to 80 mJ / mg. Is more preferably from 20 to 75 mJ / mg, particularly preferably from 20 to 45 mJ / mg, and particularly preferably from 20 to 35 mJ / mg.
  • the heat of fusion is an indicator of the degree of flexibility of the crystalline region of the thermoplastic resin composition.
  • the heat of fusion of the thermoplastic resin composition can be in the desired range by adjusting the thermoplastic resin to be used and the content thereof.
  • the heat of fusion of the thermoplastic resin composition can be obtained by collecting 1 mg of a measurement piece from the central portion of the melt-blown nonwoven fabric, and determining it by the method described later.
  • the heat of fusion is less than the above upper limit, the proportion of amorphous regions present in the fiber increases. As a result, the fibers become soft and the orientation that occurs during the spinning process is suppressed. The orientation of the fibers will be described later. If the heat of fusion is larger than the above lower limit, the fibers become soft and orientation is difficult to occur, while if it is less than the above upper limit, the number of crystal regions present in the fiber is sufficiently large and fusion between the fibers is suppressed And the distance between the fibers can be narrowed to improve the water pressure resistance.
  • the thermoplastic resin composition may contain only a thermoplastic resin whose heat of fusion is within a desired range. Moreover, two or more types of thermoplastic resins having different amounts of heat of fusion may be mixed so that the amount of heat of fusion falls within a desired range. When a plurality of thermoplastic resins are used, the heat of fusion is in the desired range by mixing the thermoplastic resin having the heat heat of fusion above the upper limit of the desired range and the thermoplastic resin of the heat heat of fusion below the lower limit of the desired range. Alternatively, a plurality of thermoplastic resins each having a desired range of heat of fusion may be mixed.
  • thermoplastic resin for example, polyolefin, polyester, polyetheretherketone, polyphenylene sulfide, polyamide and the like can be used. Among them, polyolefin or polyester is preferable, and polyolefin is particularly preferable. If the heat of fusion falls within the desired range, one of these thermoplastic resins may be used alone, or two or more thereof may be used in combination.
  • thermoplastic resin composition is a polyolefin.
  • polyolefin it is more preferable to occupy 80 mass% or more of a thermoplastic resin composition, and it is more preferable to occupy 90 mass% or more.
  • polystyrene resin a homopolymer of ⁇ -olefin or a copolymer of two or more ⁇ -olefins can be used. These may be used alone or in combination of two or more.
  • polyolefin those obtained by copolymerizing ⁇ -olefin with unsaturated carboxylic acid such as acrylic acid, methacrylic acid and maleic acid, ester of these unsaturated carboxylic acids, and acid anhydride can also be used. .
  • the ⁇ -olefin preferably has 2 to 20 carbon atoms, and more preferably 2 to 10 carbon atoms.
  • propylene, ethylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene and the like are preferable, propylene or ethylene is more preferable, and propylene is most preferable.
  • high crystalline polyolefin or low crystalline polyolefin can be used as a homopolymer of ⁇ -olefin.
  • the highly crystalline polyolefin is a polyolefin having high ⁇ -olefin stereoregularity.
  • Specific examples of the high crystalline polyolefin include high crystalline polypropylene such as isotactic polypropylene and syndiotactic polypropylene; high crystalline polyethylene such as high density polyethylene and medium density polyethylene.
  • the highly crystalline polypropylene generally used for the meltblown nonwoven fabric has a heat of fusion of over 94 mJ / mg, and is a resin having many crystalline regions and being hard.
  • shear flow occurs on the spinning line, and rigid fibers having many crystalline regions tend to be oriented in the direction of the air flow. Since the air stream is blown onto the collecting surface driven in the MD direction, it is considered that the fibers are deposited on the collecting surface while making the orientation direction the same as the MD direction. Therefore, by setting the heat of fusion of the thermoplastic resin composition constituting the fiber to less than 94 mJ / mg, a large number of soft noncrystalline regions exist in the fiber, and the orientation of the fiber according to the shear direction hardly occurs. As a result, it is considered that in the non-woven fabric deposited on the collecting surface, the fiber orientation in the MD direction decreases and the rectilinear rate in the CD direction increases.
  • the heat of fusion of the highly crystalline polyolefin is preferably greater than 94 mJ / mg, more preferably 96 mJ / mg or more, still more preferably 98 mJ / mg or more, and less than 120 mJ / mg. It is preferably 115 mJ / mg or less, more preferably 110 mJ / mg or less, and specifically more than 94 mJ / mg and less than 120 mJ / mg, and preferably 96 mJ / mg to 115 mJ / mg. It is more preferable that it is the following, and it is still more preferable that it is 98 to 110 mJ / mg.
  • the melt flow rate (MFR) (230 ° C.) of the highly crystalline polyolefin is preferably 100 g / 10 min or more, more preferably 300 g / 10 min or more, and 2000 g / 10 min or less Is more preferably 1800 g / 10 min or less, specifically 100 g / 10 min or more and 2000 g / 10 min or less and 300 g / 10 min or more and 1800 g / 10 min or less More preferable.
  • MFR is measured at a temperature of 230 ° C. under a load of 2.16 kg according to JIS K7210.
  • the MFR is less than this upper limit, the fluidity of the resin at the time of the spinning process is not too high, and yarn breakage is suppressed and thin fibers are easily realized.
  • the MFR is at least the lower limit, the resin has fluidity, and the fiber can be sufficiently drawn during the spinning process, and the fiber diameter can be reduced.
  • the high crystalline polyolefin preferably has a weight average molecular weight (Mw) of 5,000 or more, more preferably 10,000 or more, still more preferably 15,000 or more, and preferably 500,000 or less, and 200,000. It is more preferable that it is the following, it is more preferable that it is 150000 or less, and it is specifically preferable that it is 5000 or more and 500000 or less, it is more preferable that it is 10000 or more and 200000 or less, and it is that More preferable.
  • Mw weight average molecular weight
  • the weight average molecular weight is at least the lower limit, the polymer chains are strongly entangled in the spinning process, yarn breakage can be prevented, and thin fibers can be realized.
  • the weight average molecular weight is not more than this upper limit, the entanglement between polymer chains is not too strong, the fiber can be sufficiently drawn during the spinning process, and the fiber diameter can be reduced.
  • the high crystalline polyolefin preferably has a molecular weight distribution (average molecular weight (Mw) / number average molecular weight (Mn)) of 1.1 or more, more preferably 1.5 or more, and 2 or more. Is more preferably 5 or less, more preferably 4 or less, still more preferably 3.5 or less, specifically 1.1 or more and 5 or less, It is more preferably 1.5 or more and 4 or less, and still more preferably 2 or more and 3.5 or less.
  • Mw average molecular weight
  • Mn number average molecular weight
  • the low crystalline polyolefin is a polyolefin having low ⁇ -olefin stereoregularity.
  • Specific examples of the low crystalline polyolefin include low crystalline polypropylene such as atactic polypropylene and low stereoregular polypropylene; low crystalline polyethylene such as low density polyethylene and linear low density polyethylene.
  • the low stereoregular polypropylene is obtained by polymerizing propylene using a known methacone catalyst.
  • the heat of fusion of the low crystalline polyolefin is preferably greater than 0 mJ / mg, more preferably 3 mJ / mg or more, still more preferably 5 mJ / mg or more, and less than 94 mJ / mg. It is more preferably 85 mJ / mg or less, still more preferably 70 mJ / mg or less, specifically more than 0 mJ / mg and less than 94 mJ / mg, preferably 3 mJ / mg to 85 mJ / mg.
  • the content is more preferably 5 mJ / mg or more and 70 mJ / mg or less.
  • the low crystalline polyolefin preferably has MFR (230 ° C.) of 100 g / 10 min or more, more preferably 1000 g / 10 min or more, still more preferably 1800 g / 10 min or more, and 2500 g It is preferably 10 minutes or less, more preferably 2300 g / 10 minutes or less, still more preferably 2100 g / 10 minutes or less, and specifically 100 g / 10 minutes to 2500 g / 10 minutes Is preferably 1000 g / 10 minutes to 2300 g / 10 minutes, and more preferably 1800 g / 10 minutes to 2100 g / 10 minutes. MFR is measured at a temperature of 230 ° C. under a load of 2.16 kg according to JIS K7210.
  • the low crystalline polyolefin preferably has a weight average molecular weight (Mw) of 5,000 or more, more preferably 20,000 or more, still more preferably 30,000 or more, and preferably 150,000 or less, 70,000.
  • Mw weight average molecular weight
  • the following is more preferable, 50000 or less is more preferable, and specifically, 5000 or more and 150000 or less is preferable, 20000 or more and 70000 or less is more preferable, and 30000 or more and 50000 or less More preferable.
  • Copolymers of two or more ⁇ -olefins are low crystalline or amorphous olefin elastomers.
  • a copolymer of ⁇ -olefin a random copolymer, a block copolymer, a graft copolymer or an alternating copolymer can be used.
  • a block copolymer it is preferable that the ⁇ -olefin be bonded by an atactic structure.
  • a copolymer of two or more ⁇ -olefins is referred to as an olefin-based elastomer.
  • the olefin-based elastomer has a heat of fusion greater than 0 mJ / mg and less than 94 mJ / mg, preferably 3 mJ / mg or more, more preferably 5 mJ / mg or more, and 90 mJ / mg or less Is more preferable, and 85 mJ / mg or less is more preferable.
  • the olefin elastomer is at least one member selected from the group consisting of polyene compound units such as butadiene, isoprene, ethylidene norbornene and dicyclopentadiene, cyclic olefin units and vinyl aromatic compound units, as necessary, in addition to ⁇ -olefin May be contained as a monomer.
  • the olefin elastomer examples include, for example, propylene / ethylene copolymer, propylene / ethylene / 1-butene copolymer, propylene / 1-butene copolymer, propylene / ethylene / cyclic olefin copolymer, propylene / Examples thereof include ethylene / butadiene copolymer, propylene / 1-butene / styrene copolymer and the like.
  • a propylene / ethylene copolymer or a propylene / ethylene / 1-butene copolymer is most preferable. One of these may be used alone, or two or more may be used in combination.
  • the olefin elastomer preferably has an MFR (230 ° C.) of 10 g / 10 min or more, more preferably 300 g / 10 min or more, and preferably 2000 g / 10 min or less, 1800 g / 10 min. More preferably, it is less than a minute. MFR is measured at a temperature of 230 ° C. under a load of 2.16 kg according to JIS K7210.
  • the olefin elastomer preferably has a molecular weight distribution (weight-average molecular weight (Mw) / number-average molecular weight (Mn)) of 1.1 or more, more preferably 1.3 or more, and 1.5 or more. Some are more preferable, and 5 or less is preferable, 4 or less is more preferable, and 3.5 or less is more preferable.
  • Mw weight-average molecular weight
  • Mn number-average molecular weight
  • the olefin-based elastomer can be produced using a polymerization catalyst such as a known Ziegler-Natta type catalyst or a single site catalyst (for example, a metallocene type catalyst).
  • a polymerization catalyst such as a known Ziegler-Natta type catalyst or a single site catalyst (for example, a metallocene type catalyst).
  • the thermoplastic resin composition preferably contains a high crystalline polyolefin and a low crystalline polyolefin or a polyolefin-based elastomer.
  • the thermoplastic resin composition preferably contains a mixture of a first polyolefin whose heat of fusion is 94 mJ / mg or more and a second polyolefin whose heat of fusion is less than 94 mJ / mg.
  • the thermoplastic resin composition is generally a high crystalline polypropylene having a heat of fusion of 94 mJ / mg or more and a low crystalline polypropylene of a heat of fusion of less than 94 mJ / mg. It is particularly preferred to contain a mixture with a polypropylene-based elastomer.
  • the second polyolefin examples include high fluidity low crystalline polypropylene having MFR 400 g / 10 min or more, low fluidity low crystalline polypropylene having MFR 400 g / 10 min or less, and low fluidity MFR 400 g / 10 min Polypropylene-based elastomers can be mentioned.
  • the content of high fluidity low crystalline polypropylene having MFR of 400 g / 10 min or more is preferably 90% by mass or less, more preferably 80% by mass or less, of the entire thermoplastic resin composition, and 70% by mass It is more preferable that it is the following.
  • the content of the low crystalline polypropylene having high fluidity is preferably 3% by mass or more, more preferably 10% by mass or more, further preferably 20% by mass or more, and 50% by mass or more. In particular, it is preferably 3% by mass to 90% by mass, more preferably 10% by mass to 80% by mass, and particularly preferably 20% by mass to 70% by mass. Is more preferable, and 50 to 70% by mass is particularly preferable.
  • the content of the low crystalline polypropylene having high fluidity is not more than this upper limit, the number of amorphous regions in the fiber is not too large, the fusion between the fibers is suppressed, the distance between the fibers is narrowed, and the water pressure resistance Can be improved.
  • the content of the low crystalline polypropylene having high fluidity is not less than this lower limit, the amorphous region in the fiber is sufficiently present to be soft, and orientation becomes difficult to occur during the spinning process.
  • the content of the low crystalline polypropylene having an MFR of less than 400 g / 10 min or the polypropylene elastomer having an MFR of less than 400 g / 10 min is preferably 30% by mass or less of the entire thermoplastic resin composition, and is less than 30% by mass. More preferably, it is more preferably 20% by mass or less, and particularly preferably 15% by mass or less.
  • the content of the polypropylene-based elastomer is preferably 3% by mass or more, more preferably 5% by mass or more, particularly preferably 10% by mass or more, particularly preferably 20% by mass or more Specifically, it is preferably 3% by mass to 30% by mass, more preferably 3% by mass to less than 30% by mass, still more preferably 5% by mass to 20% by mass, and 10 It is particularly preferable that the content is not less than 20% by mass, particularly preferably not less than 20% by mass and not more than 15% by mass, and most preferably 10% by mass to 15% by mass.
  • low crystalline polypropylene having a MFR of less than 400 g / 10 min and polypropylene-based elastomer having a MFR of less than 400 g / 10 min have lower fluidity than a polypropylene resin for melt blowing.
  • the content is less than this upper limit, the flowability of the entire resin is increased, the fibers can be sufficiently drawn during the spinning process, and the fiber diameter becomes thin.
  • the content of the low crystalline polypropylene having a MFR of less than 400 g / 10 min and the polypropylene elastomer having a MFR of less than 400 g / 10 min is in the above range. It is preferably inside.
  • a high crystalline polypropylene is mentioned as a specific example of a 1st polyolefin.
  • the compounding ratio (first polypropylene / second polypropylene) of the first polypropylene and the second polypropylene on a mass basis is selected according to the type.
  • Mopren (registered trademark) HP 461Y (manufactured by Lyondellbasell) is used as the first polypropylene (high crystalline polypropylene), and an L-MODU of MFR 2600 g / 10 min as the second polypropylene (high flowability low crystalline polypropylene)
  • the blending ratio thereof is preferably 5/95 or more, more preferably 10/90 or more, and 20/80 or more. More preferably, it is particularly preferably 30/70 or more, and it is preferably 97/3 or less, more preferably 90/10 or less, still more preferably 80/20 or less, and 50/70.
  • the ratio is 50 or less, specifically, larger than 5/95 It is preferably 97/3 or less, more preferably 10/90 or more and 90/10 or less, still more preferably 20/80 or more and 80/20 or less, and 30/70 or more and 50/50 or less. Is particularly preferred.
  • low fluidity low crystalline polypropylene that can be used as the second polypropylene
  • a propylene-based elastomer which can be used as the second polypropylene for example, Tafresen (registered trademark) H5002 (manufactured by Sumitomo Chemical Co., Ltd.) can be mentioned.
  • the compounding ratio (first polypropylene / second polypropylene) is 70/30 or more. Is preferably 75/25 or more, more preferably 80/20 or more, particularly preferably 85/15 or more, and preferably 97/3 or less. 95/5 or less is more preferable, 90/10 or less is more preferable, and specifically 70/30 or more and 95/5 or less is preferable, and 75/25 or more and 95/5 or less Is more preferably 80/20 or more and 90/10 or less, and 8 / It is especially preferably 15 to 90/10.
  • polyester for example, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate and the like can be used. Among them, polyethylene terephthalate or polybutylene terephthalate is preferred. When plural types of polyesters are mixed and used, it is preferable that one of the polyesters is 50% by mass or more of the total polyester, more preferably 70% by mass or more, and further preferably 90% by mass or more. preferable.
  • polyamide 3 polyamide 4, polyamide 6, polyamide 66, polyamide 12 and the like can be used.
  • the thermoplastic resin composition is a nucleating agent, a matting agent, a pigment, a dye, an antifungal agent, an antibacterial agent, a flame retardant, a hydrophilic agent, a light stabilizer, an antioxidant, to the extent that the effects of the present invention are not impaired.
  • You may contain additives, such as an antiaging agent, a synthetic oil, a wax, a coloring inhibitor, and a viscosity modifier.
  • the filling ratio of the melt-blown nonwoven fabric according to the present invention is preferably 3% or more, more preferably 5% or more, and still more preferably 6% or more.
  • the filling rate is larger, the fibers are more densely present, and the water pressure resistance of the melt-blown nonwoven fabric becomes larger. The higher the filling rate, the harder the meltblown nonwoven, and the lower it is softer.
  • the filling rate is preferably 30% or less, more preferably 20% or less, and still more preferably 15% or less because softness is preferred.
  • the melt-blown nonwoven fabric according to the present invention preferably has a filling rate of 3% to 30%, more preferably 5% to 20%, and more preferably 6% to 15%. More preferable.
  • the packing ratio can be made to be more than the above-mentioned lower limit by compacting the fibers by the wind pressure of the air flow by setting the distance from the nozzle of the nonwoven fabric manufacturing device described later to the collecting surface to 400 mm or less. Moreover, a melt-blown nonwoven fabric can be compressed at the time of manufacture using a calender roll etc., and a filling rate can also be adjusted more than said lower limit.
  • a thickness is set in a state where a load of 4 kPa is applied to the melt-blown nonwoven fabric using a laser displacement meter made by OMRON Corporation with respect to the nonwoven fabric obtained by the method described later taking measurement. According to the method mentioned later, a filling rate is calculated
  • the melt-blown nonwoven fabric according to the present invention preferably has a formation index of 300 or less, more preferably 280 or less, still more preferably 260 or less, and particularly preferably 250 or less. Is particularly preferred.
  • the formation index can be made equal to or less than the above-described upper limit by setting the distance from the nozzle of the nonwoven fabric manufacturing apparatus described later to the collection surface to 400 mm or less and suppressing the occurrence of unevenness in fiber deposition.
  • the formation index is practically as small as about 30 when producing a non-woven fabric by the melt-blowing method. As the formation index is smaller, the fibers are uniformly present, and the water pressure resistance of the melt-blown nonwoven fabric becomes larger.
  • the measurement of the formation index is carried out using the method which will be described later, at any position in the longitudinal direction and at the center of the meltblown nonwoven fabric in the lateral direction.
  • melt-blown nonwoven fabric integrated by heat embossing with base materials may peel when peeling off and obtaining a sample.
  • the formation index is calculated using the standard deviation of the absorbance and the mean value after subtraction of the absorbance E derived from the holes.
  • the melt-blown nonwoven fabric according to the present invention preferably has a basis weight of 20 g / m 2 or less, more preferably 15 g / m 2 or less, and more preferably 10 g / m 2 from the viewpoint of setting the filling rate and the formation index to the above range. More preferably, it is m 2 or less.
  • the basis weight is not more than this upper limit, the volume of fibers to the air pressure of the air flow is reduced, so that consolidation becomes easy, and the filling rate becomes sufficient.
  • the basis weight is below the upper limit, uniform deposition is performed in the deposition step, and the formation index is sufficient.
  • Basis weight for meltblown nonwoven express water pressure 1 g / m 2 or more preferably, 2 g / m 2 or more is more preferable.
  • the basis weight of melt-blown nonwoven fabric according to the present invention is preferably 1 g / m 2 or more 20 g / m 2 or less, 1 g / m 2 or more 15 g / m 2 or less, 2 g / More preferably, it is m 2 10 g / m 2 or less.
  • the basis weight can be measured from the weight per area of 0.05 m.
  • a melt-blown nonwoven fabric is bonded to a resin film, paper, a base material such as a spunbond nonwoven fabric, or an air-through nonwoven fabric by a hot melt or the like to form a composite
  • the hot melt is first heated by cold spray or a dryer.
  • the adhesion is reduced and the meltblown nonwoven is peeled off from the substrate.
  • the hot melt adhered to the meltblown nonwoven is dissolved by soaking the meltblown nonwoven for 24 hours in a large excess of an organic solvent such as toluene in which the hot melt is soluble.
  • the meltblown nonwoven fabric removed from the organic solvent is dried, and the basis weight of the meltblown nonwoven fabric is measured by the above method.
  • the method of taking out the melt-blown nonwoven fabric from the composite is also applied to other measurements in the present specification.
  • the meltblown nonwoven fabric is integrated with a resin film, a spunbond nonwoven fabric, a base material such as an air through nonwoven fabric by heat embossing, the meltblown nonwoven fabric is first peeled off so as to remove the embossed portion.
  • the area of the melt-blown nonwoven fabric in a state in which the holes of the embossed portion are open may be obtained from image processing such as binarization, and the basis weight may be measured from the weight at that time.
  • melt-blown nonwoven fabric of 0.05 m square area to be subjected to measurement of basis weight be obtained from a continuous melt-blown nonwoven fabric.
  • the area of one melt-blown nonwoven fabric obtainable from a product is small, it can be the sum of the areas of a plurality of melt-blown nonwoven fabrics obtained from the same product.
  • meltblown non-woven fabric When the meltblown non-woven fabric is integrated with a resin film, a spunbond non-woven fabric, an air-through non-woven fabric, or the like by heat embossing, it does not include the embossed portion except for the measurement of water pressure and the measurement of water pressure after deformation as described later. As described above, the meltblown non-woven fabric is appropriately peeled off to make a measurement target.
  • the melt-blown nonwoven fabric according to the present invention has an average fiber diameter of 4 ⁇ m or less, and along a plane, in the first direction in which the rectilinear rate of fibers is the highest and in the second direction orthogonal to the first direction. Since the straightness rate of the fibers is 35% or more in any case, the water pressure resistance is excellent, and even if deformation occurs, it is difficult to form a gap between the fibers, and a decrease in water pressure resistance can be suppressed.
  • the water pressure resistance of the meltblown nonwoven fabric can be measured by obtaining the meltblown nonwoven fabric by the same means as described above. However, when the meltblown nonwoven fabric is integrated with a substrate such as a spunbond nonwoven fabric or an air through nonwoven fabric by heat embossing, the water pressure resistance is measured as it is, and the value is taken as the water pressure resistance of the meltblown nonwoven fabric.
  • the fine melt-blown non-woven fabric is a layer that determines the water pressure resistance, so the water pressure resistance of the entire laminated non-woven fabric can be regarded as the water pressure resistance of the melt-blown non-woven fabric.
  • melt-blown nonwoven fabric according to the present invention is not particularly limited, and can be used for various applications by taking advantage of its characteristics.
  • the melt-blown nonwoven fabric according to the present invention can be used as a single layer or as a laminate, and a plurality of melt-blown nonwoven fabrics according to the present invention may be laminated, together with other known nonwoven fabrics such as spunbonded nonwoven fabric and air through nonwoven fabric. It may be stacked.
  • the melt-blown nonwoven fabric according to the present invention may be embossed if necessary.
  • the spun bond layer and the meltblown layer may be laminated and integrated by heat embossing.
  • a spunbond nonwoven separately prepared meltblown nonwoven can be laminated and embossed.
  • the meltblown nonwoven and the spunbonded nonwoven may be separately manufactured and integrated by heat embossing.
  • the basis weight can be measured by appropriately peeling off the meltblown nonwoven fabric so as not to include the embossed portion in the same manner as described above.
  • the melt-blown nonwoven fabric according to the present invention can be used as a component of absorbent articles such as disposable diapers, sanitary napkins, and incontinence pads, for example, and a drop in water pressure resistance due to deformation is suppressed. Is suitable as a leak-proof sheet.
  • Such an absorbent article can be manufactured by laminating the leak-barrier sheet, the absorber and the top sheet, which are made of the melt-blown nonwoven fabric according to the present invention.
  • the melt-blown non-woven fabric according to the present invention can also be used for sanitary masks, liquid filters, air filters, battery separators, gloves and the like.
  • the melt-blown nonwoven fabric according to the present invention can be manufactured by a melt-blowing method using a known nonwoven fabric manufacturing apparatus conventionally used for manufacturing a melt-blown nonwoven fabric.
  • the nonwoven fabric manufacturing apparatus deposits, for example, an extruder provided with a barrel incorporating a screw and a raw material feeding part, a die connected directly to the extruder or via a gear pump and the like, and a fibrous melt And a collection surface.
  • a plurality of nozzles for discharging the melt are arranged in series in the die, and blowout ports are provided on both sides of each nozzle, and a high temperature / high pressure air stream (hot air) is jetted from the blowout port to melt the melt discharged from the nozzles
  • the product is stretched to form a fiber.
  • the plurality of nozzles are preferably arranged in series at regular intervals.
  • the bore diameter of the nozzle is preferably several hundred ⁇ m.
  • the high temperature and high pressure gas flow is preferably an air flow, but may be a gas flow of another gas.
  • As the collecting surface a known one such as a net conveyor or a collecting screen can be used.
  • the method for producing a melt-blown nonwoven fabric according to the present invention is a method for producing a melt-blown nonwoven fabric having an average fiber diameter of 4 ⁇ m or less, for example, supplying a thermoplastic resin composition in the form of pellets from an input portion into an extruder After heating and melting in the machine, the melt is supplied to a die and discharged from a nozzle, and the discharged melt is drawn by a stream (hot air) of high temperature and high pressure to form a fibrous form. The fibrous melt is deposited on the collecting surface in the deposition step, and the fibers are fused together to form a meltblown nonwoven fabric.
  • thermoplastic resin composition can be used as a thermoplastic resin composition used in the manufacturing method of the melt blow nonwoven fabric concerning the present invention.
  • the thermoplastic resin composition may be prepared by directly charging the thermoplastic resin and the component to be optionally blended into the extruder instead of the pellet.
  • the temperature (hot air temperature) of the air flow in the spinning step is 260 ° C. or less, preferably 250 ° C. or less, and more preferably 240 ° C. or less.
  • the temperature of the air flow becomes equal to or lower than this upper limit, the time for which the fibers have tackiness is shortened, entanglement of the fibers is less likely to occur, the air resistance of the fibers is suppressed, and it is difficult to orient in the MD direction in the spinning process, It is considered that the linear movement rate of the fiber in the CD direction is high.
  • the lower limit of the temperature of the air flow needs to be equal to or higher than the melting point of the thermoplastic resin composition.
  • the melting point is measured by differential scanning calorimetry (DSC), a DSC curve is obtained while raising the temperature from 30 ° C. to 20 ° C./min, and the temperature at the highest endothermic peak point appearing at 30 to 240 ° C. Let it be the melting point.
  • DSC differential scanning calorimetry
  • the thermoplastic resin composition preferably contains highly crystalline polypropylene.
  • the hot air temperature is preferably 160 ° C. or higher, which is the melting point of highly crystalline polypropylene, more preferably 180 ° C. or higher, and still more preferably 200 ° C. or higher.
  • the hot air temperature is preferably 160 ° C. or more and 260 ° C. or less, more preferably 180 ° C. or more and 250 ° C. or less, and still more preferably 200 ° C. or more and 240 ° C. or less.
  • the flow rate of the air flow and air flow width 1m per 500 Nm 3 / hr or more to be blown in the spinning process 700 Nm 3 / hr or more and It is more preferable to do.
  • it is preferable to set the flow rate of the air flow to 1700 Nm 3 / hr or less per 1 m width of the air flow, 1300 Nm 3 / hr It is more preferable to set it as the following.
  • the distance from the nozzle of the nonwoven fabric production apparatus to the collection surface is preferably 400 mm or less, more preferably 300 mm or less, and still more preferably 150 mm or less.
  • the distance from the nozzle to the collecting surface is equal to or less than the upper limit, it is considered that the fibers can be densely deposited and the water pressure resistance is improved.
  • the molten fibers can be cooled and deposited to prevent coalescence of the molten fibers and improve the water pressure resistance.
  • the fibers are cooled when the fibers are deposited, and the distance from the nozzle to the collection surface is preferably 50 mm or more, preferably 50 mm or more, more preferably 80 mm or more, and still more preferably 100 mm or more.
  • the method for producing a melt-blown nonwoven fabric according to the present invention preferably includes a heating step of heating the fibers after the spinning step and prior to the deposition step in which the fibers are deposited on the collecting surface.
  • a heating step it is preferable to use an IR heater instead of hot air from the viewpoint that it is preferable to apply heat only to the fibers without giving disturbance such as wind.
  • the position to heat the fibers is preferably 100 mm or more below the nozzle from the viewpoint of preventing the fibers discharged from the nozzle from cooling and solidifying in the spinning space, and preferably 200 mm or less .
  • the position to heat the fiber is preferably 80 mm or more, more preferably 100 mm or more, and preferably 200 mm or less, preferably 180 mm or less in the direction perpendicular to the spinning line. It is more preferable that
  • the temperature of air flow in the spinning step is 260 ° C. or less, and the heat of fusion of the thermoplastic resin composition constituting the fiber is more than 5 mJ / mg and less than 94 mJ / mg Because of this, it is possible to obtain a meltblown nonwoven fabric in which the straightness of the fibers in the CD direction is 35% or more.
  • Resins used as raw materials of the thermoplastic resin composition in Examples 1 to 11 and Comparative Examples 1 to 4 are as follows.
  • Resin 1 Polypropylene (Moplen (registered trademark) HP461Y manufactured by Lyondellbasell), heat of fusion 98 mJ / mg, MFR 1300 g / 10 min, melting point 160 ° C.
  • L-MODU Low crystalline polypropylene
  • melt-blown nonwoven fabric used in Comparative Examples 5 and 6 is as follows.
  • Non-woven fabric 1 Melt-blown non-woven fabric (PC 0009) manufactured by Kurare Kura Flex Co., Ltd.
  • Non-woven fabric 2 Made by Tapyrus Co., Ltd.
  • thermoplastic resin composition The heat of fusion of the thermoplastic resin composition was measured by differential scanning calorimetry (DSC). The DSC curve was obtained while raising the temperature from 30 ° C. to 20 ° C./min, and the heat quantity at the endothermic peak appearing at 100 to 200 ° C. was defined as the heat of fusion.
  • the basis weight of the melt-blown nonwoven fabric is obtained by cutting out three square measurement pieces 50 mm square from the central portion of the melt-blown nonwoven fabric, measuring the mass (g) of the measurement pieces, and measuring the area (m) of the measurement pieces 2 ) Divided by 3 and made the arithmetic average value of 3 sheets the basis weight.
  • the filling rate of the meltblown non-woven fabric can be calculated by the following equation (2).
  • the thickness of the melt-blown non-woven fabric was measured using a laser displacement meter made by OMRON Corporation in a state where a load was applied so that a pressure of 4 kPa was applied. The thickness was measured five times each, and the average value was calculated to determine the thickness of the meltblown nonwoven fabric.
  • the fiber density was measured by the method described in JIS K 7112, specifically, the pycnometer method.
  • the formation index of the meltblown non-woven fabric was calculated using a formation measuring machine (FMT-MIII) manufactured by Nomura Shoji Co., Ltd. Specifically, when a sample of melt-blown non-woven fabric is placed on a sample table, the height of the CCD camera is 26 cm, the effective size is 10 cm ⁇ 10 cm, and the moving average ⁇ pixel is 1, light is irradiated from one side of the sample Take a transmission image of the image with a CCD camera. The effective size of 10 cm ⁇ 10 cm was decomposed into 320 ⁇ 230 pixels, the light intensity received by each pixel was measured, and the transmittance T for each pixel was calculated by the following equation (3).
  • V T is the transmitted light amount when lit (with sample)
  • V R is the transmitted light amount when unlit (with sample)
  • V 100 is the transmitted light amount when lit (without sample)
  • V 0 is not lit (sample None) transmitted light amount.
  • the absorbance E was calculated by the following equation (4).
  • the formation index was calculated by the following formula (5). The measurement was performed on three test pieces, and the average value was taken as the sample formation index. If the size of the sample is small and the size of 10 cm ⁇ 10 cm can not be obtained as the effective size, place the sample at the center of the test stand and make the effective size smaller than the size of the sample and as wide as possible. By setting appropriately and performing measurement, the formation index of the sample can be determined.
  • Average fiber diameter For measurement of the average fiber diameter, first, five small-piece samples were randomly taken from the melt-blown nonwoven fabric. Next, using a tabletop scanning electron microscope (JCM-6000 Plus) manufactured by JEOL Ltd., an SEM photograph was taken, in which 20 to 60 fibers were visible in the field of view. The fiber diameter was measured once for each of all the fibers in the field of view to obtain an average value, and the value obtained by rounding off the 10 nm of the average value was taken as the fiber diameter of the small sample. The fiber diameter was similarly measured about five small pieces of samples, and the average value of five was made into the average fiber diameter of the melt-blown nonwoven fabric.
  • JCM-6000 Plus tabletop scanning electron microscope
  • the water resistance was measured in accordance with the water resistance test (hydrostatic pressure method) A (low water pressure method) of JIS L1092-1998. At the time of the water resistance test, measurement was performed by overlapping a nylon mesh sheet (pore size: 133 ⁇ m, thickness: 121 ⁇ m, manufactured by Kurashiki Spinning Co., Ltd., DO-ML-20) on the test piece. In addition, when the size of a test piece does not satisfy a regulation, the apparatus which reduced the measurement area so that water may contact the test piece of the area which can be extract
  • a melt-blown nonwoven fabric according to Example 1 was manufactured using the thermoplastic resin composition.
  • the production conditions of the meltblown nonwoven fabric according to Example 1 were as follows. The manufacturing conditions are shown in Table 1. Resin temperature (temperature when discharging from the nozzle): 270 ° C Single-hole discharge amount: 0.20 g / min / hole Hot air flow: 300 Nm 3 Hot air blowout width 400mm Hot air temperature (temperature of air flow in spinning process): 200 ° C.
  • Nozzle diameter 0.15 mm
  • nozzle length 3 mm
  • nozzle pitch 0.85 mm
  • Distance from nozzle to collection surface 300 mm
  • various physical properties of the meltblown nonwoven fabric according to Example 1 were measured by the methods (1) to (9) above, and the results are shown in Table 2.
  • Examples 2 to 11, Comparative Examples 1 to 4 Melt-blown non-woven fabrics according to Examples 2 to 11 and Comparative Examples 1 to 4 were produced in the same manner as in Example 1 except that the resin type, compounding ratio and production conditions were changed as shown in Table 1. The manufacturing conditions not described in Table 1 are the same as in Example 1. Further, in the same manner as in Example 1, various physical properties of melt-blown nonwoven fabrics according to Examples 2 to 11 and Comparative Examples 1 to 4 were measured, and the results are shown in Table 2.
  • Example 12 The center of the short wavelength infrared heater (model number IRMA 900/160) manufactured by Heraeus is located at a position of 150 mm below the nozzle and 120 mm away from the nozzle using Resin 1. The output is 100%. Heating was performed at a total output of 9000 W). The other manufacturing conditions were the same as in Example 1 to produce a meltblown nonwoven fabric according to Example 12. Further, in the same manner as Example 1, various physical properties of the obtained meltblown nonwoven fabric were measured, and the results are shown in Table 2.
  • the meltblown nonwoven fabrics according to Examples 1 to 12 have a mean fiber diameter of 4 ⁇ m or less, and a first direction in which the rectilinear rate of fibers is the highest and a second direction orthogonal to the first direction. Since the straightness of the fiber is 35% or more, or the average fiber diameter is 4 ⁇ m or less, the ratio of the straightness of the fiber in the first direction to the straightness of the fiber in the second direction in the plane of the meltblown nonwoven fabric is 2 Since it is less than or equal to .5, it can be seen that the water pressure resistance is high, and the decrease in water pressure resistance due to deformation is suppressed.

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Abstract

This meltblown non-woven fabric has an average fiber diameter of 4 μm or lower. In a first direction that is in the plane of the meltblown non-woven fabric and has the highest percentage of straight-running fibers and in a second direction that is orthogonal to the first direction, the percentage of straight-running fibers is at least 35%.

Description

メルトブロー不織布Melt blow nonwoven
　本発明は、メルトブロー法により製造されるメルトブロー不織布に関する。 The present invention relates to a meltblown nonwoven fabric produced by a meltblowing method.
　メルトブロー不織布は、メルトブロー法により製造される不織布であり、細い繊維同士が緻密に重なり合っているため繊維間の距離が小さく、高い耐水性を有することが知られている（特許文献１）。 A meltblown nonwoven fabric is a nonwoven fabric produced by a meltblowing method, and it is known that the distance between the fibers is small because the thin fibers are closely overlapped with each other, and it has high water resistance (Patent Document 1).
　メルトブロー法は、溶融した熱可塑性樹脂組成物を複数のノズルを有するダイから高温高速の気流で吹き出すことによって繊維状に延伸する紡糸工程と、得られた繊維を捕集面上に堆積させて互いに融着させる堆積工程とを備える方法であり、細い繊維を製造するのに適している。 The melt-blowing method is a spinning step of drawing a molten thermoplastic resin composition into a fibrous form by blowing out a molten thermoplastic resin composition from a die having a plurality of nozzles at a high speed and a high velocity, and the obtained fibers are deposited on a collecting surface And a depositing step for fusing, suitable for producing fine fibers.
　（特許文献１）国際公開第２０１２／１０２３９８号 (Patent Document 1) International Publication No. 2012/102398
　本発明は、平均繊維径が４μｍ以下であるメルトブロー不織布であって、
　前記メルトブロー不織布の平面に沿い、且つ繊維の直進率が最も高い第１方向及び前記第１方向に直交する第２方向を有するメルトブロー不織布を提供する。
　実施形態では、前記第１方向及び前記第２方向における繊維の直進率がいずれも３５％以上である。 The present invention is a melt-blown nonwoven fabric having an average fiber diameter of 4 μm or less,
A meltblown nonwoven fabric is provided, which has a first direction along the plane of the meltblown nonwoven fabric and in which the straightness of fibers is the highest, and a second direction orthogonal to the first direction.
In the embodiment, the straightness of the fibers in the first direction and the second direction is 35% or more.
　実施形態では、メルトブロー不織布は、下記（Ｉ），（II）及び（III）から選ばれる１又は複数の条件を満たす。
　（Ｉ）　前記第１方向及び前記第２方向における繊維の直進率がいずれも３５％以上である。
　（II）　前記第２方向における繊維の直進率に対する前記第１方向における繊維の直進率の比（前記第１方向における繊維の直進率／前記第２方向における繊維の直進率）が１以上２．５以下である。
　（III）　前記メルトブロー不織布の耐水圧が１００ｍｍＨ2Ｏ以上１００００ｍｍＨ2Ｏ以下であり、任意に、前記第２方向に前記メルトブロー不織布を変形させた場合の耐水圧保持率が８５％以上である。
　実施形態では、前記（Ｉ）のメルトブロー不織布は、前記第２方向における繊維の直進率に対する前記第１方向における繊維の直進率の比（前記第１方向における繊維の直進率／前記第２方向における繊維の直進率）が１以上２．５以下である。
　実施形態では、前記（Ｉ）又は前記（II）のメルトブロー不織布は、耐水圧が１００ｍｍＨ2Ｏ以上１００００ｍｍＨ2Ｏ以下である。
　実施形態では、前記（Ｉ）又は前記（II）のメルトブロー不織布は、前記第２方向に前記メルトブロー不織布を変形させた場合の耐水圧保持率が８５％以上である。
　実施形態では、前記メルトブロー不織布は、充填率が３％以上、及び／又は、３０％以下である。
　実施形態では、前記繊維の融解熱量が５ｍＪ／ｍｇより大きく、及び／又は、９４ｍＪ／ｍｇ未満である。 In an embodiment, the meltblown nonwoven fabric satisfies one or more conditions selected from the following (I), (II) and (III).
(I) The straightness of fibers in the first direction and the second direction is 35% or more.
(II) The ratio of the straightness of fibers in the first direction to the straightness of fibers in the second direction (the straightness of fibers in the first direction / the straightness of fibers in the second direction) is 1 or more. 5 or less.
(III) The water pressure resistance of the melt-blown non-woven fabric is 100 mm H 2 O or more and 10000 mm H 2 O or less, and optionally, the water-pressure resistant retention when the melt-blown non-woven fabric is deformed in the second direction is 85% or more.
In the embodiment, the melt-blown nonwoven fabric of (I) has a ratio of a linear movement ratio of fibers in the first direction to a linear movement ratio of fibers in the second direction (a linear movement ratio of fibers in the first direction / the second direction The straightness of fibers is 1 or more and 2.5 or less.
In an embodiment, the above-mentioned (I) or the (II) melt-blown nonwoven fabric has a water pressure resistance of 100 mm H 2 O or more and 10000 mm H 2 O or less.
In an embodiment, the melt-blown nonwoven fabric of (I) or (II) has a water pressure resistance retention of 85% or more when the melt-blown nonwoven fabric is deformed in the second direction.
In an embodiment, the meltblown non-woven fabric has a filling rate of 3% or more and / or 30% or less.
In embodiments, the heat of fusion of the fibers is greater than 5 mJ / mg and / or less than 94 mJ / mg.
　また、本発明は、平均繊維径が０．１μｍ以上４μｍ以下のメルトブロー不織布であって、
　前記メルトブロー不織布の平面に沿い、且つ繊維の直進率が最も高い第１方向及び前記第１方向に直交する第２方向における繊維の直進率がいずれも３５％以上であり、
　前記第２方向における繊維の直進率に対する前記第１方向における繊維の直進率の比（前記第１方向における繊維の直進率／前記第２方向における繊維の直進率）が１以上２．５以下であり、
　充填率が３％以上３０％以下であり、
　前記繊維の融解熱量が５ｍＪ／ｍｇより大きく９４ｍＪ／ｍｇ未満であるメルトブロー不織布を提供する。 Further, the present invention is a melt-blown nonwoven fabric having an average fiber diameter of 0.1 μm to 4 μm,
The straightness of the fibers in the first direction along which the meltblown nonwoven fabric has the highest straightness of the fibers and in the second direction orthogonal to the first direction is 35% or more.
The ratio of the straightness of fibers in the first direction to the straightness of fibers in the second direction (the straightness of fibers in the first direction / the straightness of fibers in the second direction) is 1 or more and 2.5 or less Yes,
The filling rate is 3% or more and 30% or less,
The melt-blown nonwoven fabric is provided, wherein the heat of fusion of the fibers is more than 5 mJ / mg and less than 94 mJ / mg.
　実施形態では、前記メルトブロー不織布は、前記第２方向における繊維の直進率に対する前記第１方向における繊維の直進率の比（前記第１方向における繊維の直進率／前記第２方向における繊維の直進率）が１以上１．９以下である。
　実施形態では、前記メルトブロー不織布は、前記第１方向及び前記第２方向、並びに前記直進率は、下記手順（ａ）～（ｇ）により決定される。
　（ａ）卓上走査電子顕微鏡（ＪＣＭ－６０００Ｐｌｕｓ、日本電子株式会社製）を用い、観察倍率＝３０００／平均繊維径（μｍ）で、メルトブロー不織布の中央部を観察位置としてＳＥＭ画像を取得して、該ＳＥＭ画像の長辺方向を０°とすること、ただし、測定対象の不織布が略長方形の形状である場合には、該不織布の長手方向を０°とし、ＳＥＭ画像の長辺方向が０°に平行となるようにＳＥＭ画像を取得する、
　（ｂ）視野をθ°回転させてＳＥＭ画像を取得し、さらに視野をθ°ずつ回転して０°～（１８０－θ）°のＸ枚のＳＥＭ画像を取得すること、ここで、枚数Ｘ＝（１８０°／θ°）－１である、
　（ｃ）上記手順（ａ）の観察位置とは異なる観察位置７点において、上記手順（ａ）及び（ｂ）の操作をそれぞれ行い、Ｘ枚×８点のＳＥＭ画像を取得すること、ただし、８点の観察位置は、メルトブロー不織布の中央部における４０ｍｍ×２０ｍｍの範囲内にあり、それぞれ１０ｍｍ以上離れている、
　（ｄ）上記手順（ａ）～（ｃ）で得られたＳＥＭ画像のそれぞれについて、０°～（１８０－θ）°の各角度における繊維の直進率を下記式（１）により算出し、小数点以下を四捨五入し、８点の平均値を求めて各角度における直進率とすること、
　（ｅ）上記手順（ｄ）で算出した各角度の直進率のうち、最も直進率の大きい角度を第１方向とし、該最も大きい値の直進率を第１方向における繊維の直進率とすること、
　（ｆ）前記第１方向と直交する方向を第２方向とすること、
　（ｇ）前記８点の観察位置において、ＳＥＭ画像の長辺方向が前記第２方向に平行となるＳＥＭ画像を取得し、それぞれ前記第２方向の繊維の直進率を下記式（１）により算出して８点の平均値を求め、小数点以下を四捨五入すること、
Figure JPOXMLDOC01-appb-M000002
 　　　　　　　　　　　　　　　　　 
ここで、N(0)、N(1)、N(2)は、それぞれ以下を表す。
　　N(0)は、ＳＥＭ画像の長辺方向一端から他端へ連続して延びる繊維の本数
　　N(1)は、長辺方向一端に交差する繊維の本数
　　N(2)は、長辺方向他端に交差する繊維の本数
　実施形態では、前記メルトブロー不織布は、充填率が６％以上、及び／又は、１５％以下である。
　実施形態では、前記メルトブロー不織布は、地合い指数が３０以上、及び／又は、３００以下であり、任意に、２００以下である。
　実施形態では、前記繊維の融解熱量が２０ｍＪ／ｍｇ以上、及び／又は、８０ｍＪ／ｍｇ以下である。 In an embodiment, the melt-blown nonwoven fabric has a ratio of a straightness of fibers in the first direction to a straightness of fibers in the second direction (a straightness of fibers in the first direction / a straightness of fibers in the second direction ) Is 1 or more and 1.9 or less.
In the embodiment, in the melt-blown nonwoven fabric, the first direction, the second direction, and the rectilinear rate are determined by the following procedures (a) to (g).
(A) Using a tabletop scanning electron microscope (JCM-6000 Plus, manufactured by Nippon Denshi Co., Ltd.), obtain an SEM image with the central part of the meltblown non-woven fabric as the observation position at an observation magnification of 3000 / average fiber diameter (μm) The long side direction of the SEM image is 0 °, provided that the longitudinal direction of the non-woven fabric is 0 ° and the long side direction of the SEM image is 0 ° when the nonwoven fabric to be measured has a substantially rectangular shape. Acquire SEM images parallel to
(B) Rotate the field of view by θ ° to acquire an SEM image, and further rotate the field of view by θ ° to acquire X SEM images of 0 ° to (180-θ) °, where = (180 ° / θ °) -1,
(C) performing the operations of the above procedures (a) and (b) at seven observation positions different from the observation position of the above procedure (a) to obtain X pieces of × 8 SEM images; The eight observation positions are within the range of 40 mm × 20 mm in the central part of the meltblown non-woven fabric, and are each separated by 10 mm or more.
(D) For each of the SEM images obtained in the above procedures (a) to (c), the straightness of fibers at each angle of 0 ° to (180-θ) ° is calculated by the following equation (1), Round off the following, find the average value of 8 points, and let it be the rate of going straight at each angle,
(E) Of the straight advance rates of each angle calculated in the step (d), the largest straight advance rate is taken as the first direction, and the largest straight advance rate is regarded as the straight advance rate of fibers in the first direction. ,
(F) setting a direction orthogonal to the first direction as a second direction;
(G) An SEM image in which the long side direction of the SEM image is parallel to the second direction is acquired at the eight observation positions, and the straightness of fibers in the second direction is calculated by the following equation (1) Calculate the average of 8 points and round off the decimal point,
Figure JPOXMLDOC01-appb-M000002
Here, N (0), N (1) and N (2) respectively represent the following.
N (0) is the number of fibers continuously extending from one end to the other end of the SEM image N (1) is the number of fibers crossing one end in the long side N (2) is the length in the long side In an embodiment, the meltblown non-woven fabric has a filling factor of 6% or more and / or 15% or less.
In an embodiment, the meltblown nonwoven has a formation index of at least 30, and / or at most 300, optionally at most 200.
In an embodiment, the heat of fusion of the fiber is 20 mJ / mg or more and / or 80 mJ / mg or less.
　また、本発明は、前記メルトブロー不織布を有する防漏シートを提供する。
　また、本発明は、肌対向面側に配置される液透過性の表面シートと、
　非肌対向面側に配置される液防漏性の裏面シートと、
　これらシートの間に配置された吸収体と、を備える吸収性物品であって、
　前記裏面シートは、前記防漏シートである吸収性物品を提供する。 Moreover, this invention provides the leak-proof sheet which has the said melt-blown nonwoven fabric.
Further, according to the present invention, there is provided a liquid-permeable top sheet disposed on the side facing the skin,
Liquid-repellent back sheet disposed on the non-skin facing side,
And an absorbent disposed between the sheets.
The back sheet provides the absorbent article which is the leakproof sheet.
　また、本発明は、溶融した熱可塑性樹脂組成物をノズルから吐出し、気流により繊維状とする紡糸工程を含む、メルトブロー不織布の製造方法を提供する。
　実施形態では、前記製造方法は、平均繊維径が４μｍ以下であるメルトブロー不織布を製造する。
　実施形態では、前記気流の温度を前記熱可塑性樹脂組成物の融点以上とする。
　実施形態では、前記熱可塑性樹脂組成物の融解熱量を５ｍＪ／ｍｇより大きく、及び／又は、９４ｍＪ／ｍｇ未満とする。 The present invention also provides a method for producing a melt-blown nonwoven fabric, including a spinning step of discharging a molten thermoplastic resin composition from a nozzle and forming it into a fibrous form by air flow.
In an embodiment, the manufacturing method manufactures a meltblown nonwoven fabric having an average fiber diameter of 4 μm or less.
In the embodiment, the temperature of the air flow is equal to or higher than the melting point of the thermoplastic resin composition.
In an embodiment, the heat of fusion of the thermoplastic resin composition is more than 5 mJ / mg and / or less than 94 mJ / mg.
　実施形態では、前記気流の温度を２６０℃以下、任意に、２５０℃以下、任意に、２４０℃以下とする。
　実施形態では、前記製造方法は、前記熱可塑性樹脂組成物に前記融解熱量の異なる２種以上のポリオレフィンを含有する。
　実施形態では、前記熱可塑性樹脂組成物は、前記融解熱量が９４ｍＪ／ｍｇ以上である第１のポリオレフィン、及び／又は、前記融解熱量が９４ｍＪ／ｍｇ未満である第２のポリオレフィンとからなるポリオレフィンを含有する。
　実施形態では、前記第２のポリオレフィンは、ＭＦＲ４００ｇ／１０分以上の低結晶性ポリプロピレン、ＭＦＲ４００ｇ／１０分未満の低結晶性ポリプロピレン、及び、ＭＦＲ４００ｇ／１０分未満のポリプロピレン系エラストマーから選ばれる１又は複数を含む。
　実施形態では、前記ポリオレフィンは、α－オレフィンの単独重合体及び２種以上のα－オレフィンの共重合体から選ばれる１又は複数を含む。
　実施形態では、前記α－オレフィンの単独重合体は、高結晶性ポリオレフィン及び低結晶性ポリオレフィンのから選ばれる１又は複数を含む。
　実施形態では、前記２種以上のα－オレフィンの共重合体は、低結晶性オレフィン系エラストマー及び非晶性オレフィン系エラストマーから選ばれる１又は複数を含む。
　実施形態では、前記第１のポリオレフィンが高結晶性ポリオレフィンを含み、該高結晶性ポリオレフィンのメルトフローレートが１００ｇ／１０分以上、及び／又は、２０００ｇ／１０分以下である。
　実施形態では、前記第１のポリオレフィンが高結晶性ポリオレフィンを含み、該高結晶性ポリオレフィンのメルトフローレートが３００ｇ／１０分以上、及び／又は、１８００ｇ／１０分以下である。
　実施形態では、前記第１のポリオレフィンと前記第２のポリオレフィンとの総量に対する前記第２のポリオレフィンの含有量は、
　前記第２のポリオレフィンがＭＦＲ４００ｇ／１０分以上の低結晶性ポリプロピレンである場合、５０質量％以上、及び／又は、７０質量％以下であり、
　前記第２のポリオレフィンがＭＦＲ４００ｇ／１０分未満の低結晶性ポリプロピレン又はＭＦＲ４００ｇ／１０分未満のポリプロピレン系エラストマーである場合、１０質量％以上、及び／又は、１５質量％以下である。
　実施形態では、前記製造方法は、前記紡糸工程で得られた繊維を捕集面に堆積する堆積工程をさらに備える。
　実施形態では、前記製造方法は、前記ノズルと前記捕集面との距離を４００ｍｍ以下、任意に、３００ｍｍ以下、任意に、１５０ｍｍ以下、及び／又は、５０ｍｍ以上とする。
　実施形態では、前記製造方法は、前記紡糸工程で得られた繊維が前記捕集面に堆積される前に、前記紡糸工程で得られた繊維を加熱する加熱工程を有する。 In an embodiment, the temperature of the air flow is 260 ° C. or less, optionally 250 ° C. or less, optionally 240 ° C. or less.
In an embodiment, the manufacturing method contains two or more kinds of polyolefins different in the heat of fusion in the thermoplastic resin composition.
In an embodiment, the thermoplastic resin composition comprises a polyolefin comprising a first polyolefin having a heat of fusion of 94 mJ / mg or more and / or a second polyolefin having a heat of fusion of less than 94 mJ / mg. contains.
In an embodiment, the second polyolefin is one or more selected from low crystalline polypropylene having MFR 400 g / 10 min or more, low crystalline polypropylene having MFR 400 g / 10 min or less, and polypropylene based elastomer having MFR 400 g / 10 min or less including.
In embodiments, the polyolefin comprises one or more selected from homopolymers of alpha-olefins and copolymers of two or more alpha-olefins.
In an embodiment, the α-olefin homopolymer includes one or more selected from a high crystalline polyolefin and a low crystalline polyolefin.
In an embodiment, the copolymer of two or more α-olefins includes one or more selected from low crystalline olefin elastomers and amorphous olefin elastomers.
In an embodiment, the first polyolefin comprises a high crystalline polyolefin, and the high crystalline polyolefin has a melt flow rate of 100 g / 10 min or more and / or 2000 g / 10 min or less.
In an embodiment, the first polyolefin comprises a high crystalline polyolefin, and the high crystalline polyolefin has a melt flow rate of 300 g / 10 min or more and / or 1800 g / 10 min or less.
In an embodiment, the content of the second polyolefin relative to the total amount of the first polyolefin and the second polyolefin is
When the second polyolefin is a low crystalline polypropylene having a MFR of 400 g / 10 min or more, the content is 50 mass% or more and / or 70 mass% or less,
When the second polyolefin is a low crystalline polypropylene having a MFR of less than 400 g / 10 min or a polypropylene elastomer having a MFR of less than 400 g / 10 min, the content is 10% by mass or more and / or 15% by mass or less.
In an embodiment, the manufacturing method further includes a depositing step of depositing the fibers obtained in the spinning step on the collecting surface.
In an embodiment, the manufacturing method sets the distance between the nozzle and the collection surface to 400 mm or less, optionally 300 mm or less, optionally 150 mm or less, and / or 50 mm or more.
In an embodiment, the manufacturing method includes a heating step of heating the fibers obtained in the spinning step before the fibers obtained in the spinning step are deposited on the collecting surface.
　また、本発明は、前記製造方法により製造されたメルトブロー不織布を提供する。 The present invention also provides a meltblown nonwoven fabric produced by the above production method.
図１は、本発明に係るメルトブロー不織布のＳＥＭ画像の一例を示す模式図である。FIG. 1 is a schematic view showing an example of a SEM image of a meltblown nonwoven fabric according to the present invention.
発明の詳細な説明Detailed Description of the Invention
　一般に、メルトブロー不織布の製造時における不織布の搬送方向をＭＤ方向（Ｍａｃｈｉｎｅ　Ｄｉｒｅｃｔｉｏｎ）、ＭＤ方向に直交する方向をＣＤ方向（Ｃｒｏｓｓ　Ｄｉｒｅｃｔｉｏｎ）という。 In general, the transport direction of the nonwoven fabric at the time of production of the meltblown nonwoven fabric is referred to as MD direction (Machine Direction), and the direction orthogonal to the MD direction is referred to as CD direction (Cross Direction).
　本発明者は、メルトブロー不織布のＭＤ方向における強度は十分であるが、ＣＤ方向における強度が低いことを見出した。このため、メルトブロー不織布は、例えばＣＤ方向に引張荷重が与えられて変形が生じた場合に繊維間の距離が広がりやすく、隙間が生じて耐水性が著しく低下してしまう虞があった。一般に、荷重によって変形が生じる虞のある箇所にメルトブロー不織布を使用する場合は、メルトブロー不織布を覆うように高強度のスパンボンド不織布やエアスルー不織布が積層される形態で用いられている。 The inventors have found that the strength in the MD direction of the meltblown nonwoven fabric is sufficient but the strength in the CD direction is low. For this reason, in the melt-blown nonwoven fabric, for example, when a tensile load is applied in the CD direction to cause deformation, the distance between the fibers is likely to be extended, and a gap may be generated to significantly reduce the water resistance. In general, when using a meltblown nonwoven fabric at a location where there is a possibility that deformation may occur due to load, a high-strength spunbond nonwoven fabric or air through nonwoven fabric is used so as to cover the meltblown nonwoven fabric.
　本発明は、変形による耐水圧の低下を抑制したメルトブロー不織布に関する。 The present invention relates to a meltblown non-woven fabric in which a decrease in water pressure resistance due to deformation is suppressed.
　本発明に係るメルトブロー不織布は、変形による耐水圧の低下を抑制することができる。 The melt-blown nonwoven fabric according to the present invention can suppress a decrease in water pressure resistance due to deformation.
　本発明に係るメルトブロー不織布は、含まれている繊維の平均繊維径が４μｍ以下である。平均繊維径が小さいほど、充填率が低い領域における耐水圧が向上する。平均繊維径は、３．６μｍ以下であることが好ましく、３．２μｍ以下であることがより好ましく、３μｍ以下であることが更に好ましく、２．５μｍ以下であることが殊更好ましく、２μｍ以下であることが特に好ましい。また、平均繊維径は、０．１μｍ以上であることが好ましく、０．２μｍ以上であることがより好ましく、０．３μｍ以上であることが更に好ましい。具体的には、平均繊維径は、０．１μｍ以上４μｍ以下であることが好ましく、０．２μｍ以上３．６μｍであることがより好ましく、０．３μｍ以上３．２μｍ以下であることが更に好ましく、０．３μｍ以上３μｍ以下であることが更に好ましく０．３μｍ以上２．５μｍ以下であることが殊更好ましく、０．３μｍ以上２μｍ以下であることが特に好ましい。 In the meltblown nonwoven fabric according to the present invention, the average fiber diameter of the contained fibers is 4 μm or less. The smaller the average fiber diameter, the better the water pressure resistance in the region where the filling rate is low. The average fiber diameter is preferably 3.6 μm or less, more preferably 3.2 μm or less, still more preferably 3 μm or less, and particularly preferably 2.5 μm or less, and is 2 μm or less. Is particularly preferred. The average fiber diameter is preferably 0.1 μm or more, more preferably 0.2 μm or more, and still more preferably 0.3 μm or more. Specifically, the average fiber diameter is preferably 0.1 μm to 4 μm, more preferably 0.2 μm to 3.6 μm, and still more preferably 0.3 μm to 3.2 μm. The thickness is more preferably 0.3 μm or more and 3 μm or less, particularly preferably 0.3 μm or more and 2.5 μm or less, and particularly preferably 0.3 μm or more and 2 μm or less.
　平均繊維径がこの下限以上であることで強度に優れ、この上限以下であることで、耐水圧に優れたメルトブロー不織布となると考えられる。本発明に係るメルトブロー不織布の平均繊維径は、次のようにして算出される。まず、走査型電子顕微鏡を用いて、視野に２０～６０本の繊維が映る視野にてＳＥＭ画像を撮影する。視野内の全ての繊維について、それぞれ１回ずつ繊維径を測定して平均値を求める。当該平均値の１０ｎｍの位を四捨五入して、平均繊維径とする。平均繊維径の単位はμｍである。 When the average fiber diameter is at least the lower limit, the strength is excellent. When the average fiber diameter is at the upper limit or less, it is considered that the melt-blown nonwoven fabric is excellent in water pressure resistance. The average fiber diameter of the meltblown nonwoven fabric according to the present invention is calculated as follows. First, using a scanning electron microscope, an SEM image is taken in a field of view where 20 to 60 fibers appear. The fiber diameter is measured once for each of all the fibers in the field of view to obtain an average value. The 10 nm digit of the average value is rounded off to obtain an average fiber diameter. The unit of average fiber diameter is μm.
　本発明に係るメルトブロー不織布は、前記メルトブロー不織布の平面に沿い、且つ繊維の直進率が最も高い第１方向及び前記第１方向に直交する第２方向を有する。第１方向における繊維の直進率及び第２方向における繊維の直進率は、いずれも３５％以上であることが好ましく、３８％以上であることがより好ましく、４０％以上であることがさらに好ましく、また、９０％以下であることが好ましく、８５％以下であることがより好ましく、８０％以下であることが更に好ましい。具体的には、３５％以上９０％以下であることが好ましく、３８％以上８５％以下であることがより好ましく、４０％以上８０％以下であることが更に好ましい。第１方向は、製造時のＭＤ方向であることが好ましい。第２方向は、製造時のＣＤ方向であることが好ましい。第１方向における繊維の直進率及び第２方向における繊維の直進率が、いずれもこの下限以上であることにより、第１方向及び第２方向のいずれに変形しても繊維間に隙間が形成されにくくなり、耐水圧の低下が抑制される。 The melt-blown nonwoven fabric according to the present invention has a first direction along which the melt-blown nonwoven fabric has the highest straightness of fibers and a second direction orthogonal to the first direction. The straightness of the fiber in the first direction and the straightness of the fiber in the second direction are each preferably 35% or more, more preferably 38% or more, and still more preferably 40% or more. Further, it is preferably 90% or less, more preferably 85% or less, and still more preferably 80% or less. Specifically, it is preferably 35% or more and 90% or less, more preferably 38% or more and 85% or less, and still more preferably 40% or more and 80% or less. The first direction is preferably the MD direction at the time of manufacture. The second direction is preferably the CD direction at the time of manufacture. Since the straightness of the fiber in the first direction and the straightness of the fiber in the second direction are both lower than or equal to the lower limit, a gap is formed between the fibers regardless of deformation in either the first direction or the second direction. It becomes difficult to suppress the decrease in water pressure resistance.
　本発明に係るメルトブロー不織布は、前記メルトブロー不織布の平面に沿い、且つ繊維の直進率が最も高い方向を第１方向とし、前記第１方向に直交する方向を第２方向とする。第２方向における繊維の直進率（Ｂ）に対する第１方向における繊維の直進率（Ａ）の比（Ａ／Ｂ）は、１以上であることが好ましく、２．５以下であることが好ましく、２．１以下であることがより好ましく、１．９以下であることが更に好ましい。具体的には、比（Ａ／Ｂ）は、１以上２．５以下であることが好ましく、１以上２．１以下であることがより好ましく、１以上１．９以下であることが更に好ましい。比（Ａ／Ｂ）がこの上限以下であることで、第１方向及び第２方向のいずれに変形しても繊維間に隙間が形成されにくくなり、耐水圧の低下が抑制される。 In the melt-blown nonwoven fabric according to the present invention, the direction in which the rectilinear rate of fibers is the highest is taken as the first direction, and the direction orthogonal to the first direction is taken as the second direction. The ratio (A / B) of the rectilinear rate (A) of the fiber in the first direction to the rectilinear rate (B) of the fiber in the second direction is preferably 1 or more, and preferably 2.5 or less, It is more preferably 2.1 or less and still more preferably 1.9 or less. Specifically, the ratio (A / B) is preferably 1 or more and 2.5 or less, more preferably 1 or more and 2.1 or less, and still more preferably 1 or more and 1.9 or less. . When the ratio (A / B) is less than or equal to the upper limit, it is difficult to form a gap between the fibers regardless of deformation in either the first direction or the second direction, and a decrease in water pressure resistance is suppressed.
　本発明に係るメルトブロー不織布は、好ましくは耐水圧が１００ｍｍＨ2Ｏ以上であり、また、好ましくは１００００ｍｍＨ2Ｏ以下である。前記メルトブロー不織布の平面に沿い、且つ繊維の直進率が最も高い第１方向に直交する第２方向へメルトブロー不織布を変形させた場合の耐水圧保持率が８５％以上であることが好ましく、８８％以上であることがより好ましく、９０％以上であることがさらに好ましく、また、１００％以下であることが現実的である。本発明に係るメルトブロー不織布は、第２方向へ変形させた場合の耐水圧保持率がこの下限以上であることで、第１方向及び第２方向のいずれに変形しても繊維間に隙間が形成され難い。このため、スパンボンド不織布やエアスルー不織布と積層せずに使用して変形が生じても、耐水圧の低下が抑制される。 The melt-blown nonwoven fabric according to the present invention preferably has a water pressure resistance of 100 mm H 2 O or more, and preferably 10,000 mm H 2 O or less. It is preferable that the water pressure resistance retention rate is 85% or more when the meltblown nonwoven fabric is deformed in a second direction orthogonal to the first direction along the plane of the meltblown nonwoven fabric and in which the rectilinear rate of fibers is the highest. The above is more preferable, 90% or more is more preferable, and 100% or less is realistic. In the melt-blown nonwoven fabric according to the present invention, the water pressure resistance retention rate when deformed in the second direction is equal to or higher than this lower limit, so that a gap is formed between fibers regardless of deformation in either the first direction or the second direction. It is hard to be done. For this reason, even if it deform | transforms and uses without laminating | stacking with a spun bond nonwoven fabric or an air through nonwoven fabric, the fall of water pressure resistance is suppressed.
　本発明に係るメルトブロー不織布の繊維の直進率が最も高い第１方向、該第１方向に直交する第２方向、並びに第１方向における繊維の直進率（Ａ）及び第２方向における繊維の直進率（Ｂ）は、下記手順（ａ）～（ｇ）により決定することができる。なお、本発明に係るメルトブロー不織布の「繊維の直進率が最も高い第１方向」とは、下記手順（ａ）～（ｇ）により決定される方向を意味し、現実に繊維の直進率が最も高い方向とは異なる場合がある。
　（ａ）卓上走査電子顕微鏡（ＪＣＭ－６０００Ｐｌｕｓ、日本電子株式会社製）を用いて、観察倍率＝３０００／平均繊維径（μｍ）とし、メルトブロー不織布の中央部を観察位置としてＳＥＭ画像を取得し、該ＳＥＭ画像の長辺方向を０°とする。測定対象の不織布が略長方形の形状である場合には、該不織布の長手方向を０°とし、ＳＥＭ画像の長辺方向が０°に平行となるようにＳＥＭ画像を取得する。
　（ｂ）視野をθ°回転させてＳＥＭ画像を取得する。同様に視野をθ°ずつ回転して、０°～（１８０－θ）°のＸ枚のＳＥＭ画像を取得する。枚数Ｘ＝（１８０°／θ°）－１である。
　（ｃ）上記手順（ａ）の観察位置とは異なる観察位置７点において、上記手順（ａ）及び（ｂ）の操作をそれぞれ行い、Ｘ枚×８点のＳＥＭ画像を取得する。８点の観察位置は、メルトブロー不織布の中央部における４０ｍｍ×２０ｍｍの範囲内にあり、それぞれ１０ｍｍ以上離す。
　（ｄ）上記手順（ａ）～（ｃ）で得られたＳＥＭ画像のそれぞれについて、０°～（１８０－θ）°の各角度における繊維の直進率を下記式（１）により算出し、小数点以下を四捨五入する。８点の平均値を求め、各角度における直進率とする。
　（ｅ）上記手順（ｄ）で算出した各角度の直進率のうち、最も直進率の大きい角度を第１方向とし、該最も大きい値の直進率を第１方向における繊維の直進率（Ａ）とする。
　（ｆ）前記第１方向と直交する方向を第２方向とする。
　（ｇ）前記８点の観察位置において、ＳＥＭ画像の長辺方向が前記第２方向に平行となるＳＥＭ画像を取得し、それぞれ前記第２方向の繊維の直進率（Ｂ）を下記式（１）により算出して８点の平均値を求め、小数点以下を四捨五入する。
Figure JPOXMLDOC01-appb-M000003
 　　　　　　　　　　　　　　　　　 
ここで、N(0)、N(1)、N(2)は、それぞれ以下を表す。
　　N(0)は、ＳＥＭ画像の長辺方向一端から他端へ連続して延びる繊維の本数
　　N(1)は、長辺方向一端に交差する繊維の本数
　　N(2)は、長辺方向他端に交差する繊維の本数
　ＳＥＭ画像の長辺方向一端に達している繊維を、「長手方向一端に交差する繊維」とする。他端においても同様である。 The first direction in which the rectilinear rate of fibers of the melt-blown nonwoven fabric according to the present invention is the highest, the second direction orthogonal to the first direction, and the rectilinear rate (A) of fibers in the first direction and the rectilinear rate of fibers in the second direction (B) can be determined by the following procedures (a) to (g). In the melt-blown nonwoven fabric according to the present invention, "the first direction in which the rectilinear rate of fibers is the highest" means the direction determined by the following procedures (a) to (g). It may be different from the high direction.
(A) Using a table-top scanning electron microscope (JCM-6000 Plus, manufactured by Nippon Denshi Co., Ltd.), an observation magnification is 3000 / average fiber diameter (μm), and a SEM image is acquired with the center of the meltblown nonwoven fabric as the observation position, The long side direction of the SEM image is set to 0 °. When the nonwoven fabric to be measured has a substantially rectangular shape, the longitudinal direction of the nonwoven fabric is 0 °, and the SEM image is acquired so that the long side direction of the SEM image is parallel to 0 °.
(B) The field of view is rotated by θ ° to acquire a SEM image. Similarly, the field of view is rotated by θ °, and X SEM images of 0 ° to (180-θ) ° are acquired. The number of sheets is X = (180 ° / θ °) −1.
(C) Perform the operations of the above procedures (a) and (b) at seven observation positions different from the observation position of the above procedure (a), and obtain X sheets × 8 points of SEM images. The eight observation positions are in the range of 40 mm × 20 mm in the central part of the meltblown nonwoven fabric, and are separated by 10 mm or more.
(D) For each of the SEM images obtained in the above procedures (a) to (c), the straightness of fibers at each angle of 0 ° to (180-θ) ° is calculated by the following equation (1), Round off the following. The average value of eight points is determined and taken as the rate of rectilinear movement at each angle.
(E) Of the straight advance rates of each angle calculated in the above step (d), the largest straight advance rate is taken as the first direction, and the largest straight advance rate is the straight advance rate of fibers in the first direction (A) I assume.
(F) A direction orthogonal to the first direction is taken as a second direction.
(G) An SEM image in which the long side direction of the SEM image is parallel to the second direction is acquired at the observation positions of the eight points, and the straightness rate (B) of fibers in the second direction is expressed by the following equation (1) Calculate the average value of 8 points, and round off after the decimal point.
Figure JPOXMLDOC01-appb-M000003
Here, N (0), N (1) and N (2) respectively represent the following.
N (0) is the number of fibers continuously extending from one end to the other end of the SEM image N (1) is the number of fibers crossing one end in the long side N (2) is the length in the long side The number of fibers crossing the end The fibers reaching one end in the long side direction of the SEM image are referred to as "fibers crossing at one end in the longitudinal direction". The same applies to the other end.
　上記手順（ｄ）における繊維の直進率の算出方法について、図１を参照して詳細に説明する。図１は、長辺方向が第１方向に平行となるＳＥＭ画像の一例を示す模式図である。なお、図１において、図示の簡略化のため繊維を直線で示しているが、実際の繊維は直線状であるとは限らない。また、ＳＥＭ画像に写る繊維の本数も実際のものとは異なる場合がある。
　図１に示すＳＥＭ画像の場合、長辺方向の左端に交差する繊維の本数は交点ａ～ｆの６本であり、長辺方向の右端に交差する繊維の本数は交点ｇ～ｌの６本である。また、長辺方向左端から右端へ連続して延びる繊維は、直線ａｈ、直線ｃｉ、直線ｄｇ、直線ｅｌ及び直線ｆｋの計５本である。従って、第１方向の直進率（Ａ）（％）＝［５×２／（６＋６）］×１００＝８３％となる。 The calculation method of the straightness rate of the fiber in the said procedure (d) is demonstrated in detail with reference to FIG. FIG. 1 is a schematic view showing an example of an SEM image in which the long side direction is parallel to the first direction. In addition, in FIG. 1, although the fiber is shown as a straight line for simplification of illustration, the actual fiber is not necessarily linear. Also, the number of fibers shown in the SEM image may differ from the actual one.
In the case of the SEM image shown in FIG. 1, the number of fibers intersecting the left end in the long side direction is six at intersections a to f, and the number of fibers intersecting the right end in the long side direction is six at intersections g to l It is. Further, fibers extending continuously from the left end to the right end in the long side direction are a total of five fibers: straight line ah, straight line ci, straight line dg, straight line el and straight line fk. Accordingly, the rate of rectilinear movement in the first direction (A) (%) = [5 × 2 / (6 + 6)] × 100 = 83%.
　上記手順（ｂ）において、視野を変更する際の角度θ°は任意の値でよく、１５°以下であることが好ましく、１０°以下であることがより好ましく、５°以下であることがさらに好ましい。また、上述の測定を複数回実施した場合、観察位置や角度θ等の条件が異なることにより、決定される「直進率が最も高い方向」が異なる結果となる可能性がある。その場合、複数の測定結果のうち、直進率が最も高い方向を第１方向として採用することができる。 In the above procedure (b), the angle θ ° at the time of changing the visual field may be an arbitrary value, preferably 15 ° or less, more preferably 10 ° or less, and further preferably 5 ° or less preferable. In addition, when the above-described measurement is performed a plurality of times, the “direction in which the rate of rectilinear movement is highest” may be different due to different conditions such as the observation position and the angle θ. In that case, the direction in which the rate of rectilinear movement is the highest among the plurality of measurement results can be adopted as the first direction.
　本発明に係るメルトブロー不織布は、繊維の直進率が最も高い第１方向及びそれに直交する第２方向のいずれにおいても繊維の直進率が３５％以上であることで、変形しても繊維間に隙間が生じにくく、耐水圧の低下を抑制することができる。さらに、本発明に係るメルトブロー不織布は、スパンボンド不織布やエアスルー不織布と積層せずに使用して変形が生じても、耐水圧の低下が抑制される。 The melt-blown nonwoven fabric according to the present invention has a rectilinear rate of fibers of 35% or more in any of the first direction in which the rectilinear rate of fibers is the highest and the second direction orthogonal to it. Is less likely to occur, and a decrease in water pressure resistance can be suppressed. Furthermore, even if the melt-blown nonwoven fabric according to the present invention is deformed without being laminated with the spun bond nonwoven fabric or the air through nonwoven fabric, the decrease in water pressure resistance is suppressed.
　本発明に係るメルトブロー不織布の変形による耐水圧の低下は、変形前の耐水圧に対する変形後の耐水圧の割合（耐水圧保持率）により評価することができる。耐水圧及び耐水圧保持率は、後述する方法により測定される。メルトブロー不織布は、スパンボンド不織布、エアスルー不織布などの基材と熱エンボスによって一体化されていてもよい。一体化されたメルトブロー不織布は、一体化された状態で延伸し、その後耐水圧の測定を行う。メルトブロー不織布が熱エンボスによって樹脂フィルムと一体化されている場合には、エンボス加工されていない領域のフィルムのみを取り除き、測定対象とする。 The reduction in water pressure resistance due to the deformation of the meltblown nonwoven fabric according to the present invention can be evaluated by the ratio of water pressure resistance after deformation to the water pressure resistance before deformation (water pressure resistance retention rate). The water pressure resistance and the water pressure resistance are measured by the method described later. The meltblown nonwoven may be integrated with a base such as a spunbond nonwoven or an air through nonwoven by heat embossing. The integrated meltblown nonwoven is stretched in an integrated state and then the water pressure resistance is measured. When the melt-blown nonwoven fabric is integrated with the resin film by heat embossing, only the film in the non-embossed area is removed to make the measurement object.
　本発明に係るメルトブロー不織布は、繊維を構成する熱可塑性樹脂組成物の融解熱量を調節すること、紡糸工程において気流の温度を調節すること、または紡糸工程後、堆積工程前の繊維を加熱することにより得ることができる。紡糸工程における気流の温度、繊維の加熱については後述する。なお、熱可塑性樹脂組成物とは、１種以上の熱可塑性樹脂を含有し、必要に応じて適宜他の成分を含有する混合物である。 The melt-blown nonwoven fabric according to the present invention comprises adjusting the heat of fusion of the thermoplastic resin composition constituting the fiber, adjusting the temperature of the air flow in the spinning step, or heating the fiber before the depositing step after the spinning step. It can be obtained by The temperature of the air flow in the spinning process and the heating of the fibers will be described later. In addition, a thermoplastic resin composition is a mixture which contains 1 or more types of thermoplastic resin, and contains other components suitably as needed.
　熱可塑性樹脂組成物の融解熱量は、紡糸性の観点から、５ｍＪ／ｍｇより大きいことが好ましく、１０ｍＪ／ｍｇ以上であることがより好ましく、２０ｍＪ／ｍｇ以上であることが特に好ましい。また、柔らかい繊維を得る観点、かつ低温の熱風温度領域にて繊維を細くする観点から、９４ｍＪ／ｍｇ未満であることが好ましく、９０ｍＪ／ｍｇ以下であることがより好ましく、８０ｍＪ／ｍｇ以下であることが更に好ましく、７５ｍＪ／ｍｇ以下であることが更に好ましく、４５ｍＪ／ｍｇ以下であることが殊更好ましく、３５ｍＪ／ｍｇ以下であることが特に好ましい。 The heat of fusion of the thermoplastic resin composition is preferably greater than 5 mJ / mg, more preferably 10 mJ / mg or more, and particularly preferably 20 mJ / mg or more from the viewpoint of spinnability. Further, from the viewpoint of obtaining soft fibers and from the viewpoint of narrowing the fibers in a low temperature hot air temperature range, it is preferably less than 94 mJ / mg, more preferably 90 mJ / mg or less, and 80 mJ / mg or less Is more preferably 75 mJ / mg or less, particularly preferably 45 mJ / mg or less, and particularly preferably 35 mJ / mg or less.
　具体的には、融解熱量は、５ｍＪ／ｍｇより大きく９４ｍＪ／ｍｇ未満であることが好ましく、１０ｍＪ／ｍｇ以上９０ｍＪ／ｍｇ以下であることがより好ましく、２０ｍＪ／ｍｇ以上８０ｍＪ／ｍｇ以下であることが更に好ましく、２０ｍＪ／ｍｇ以上７５ｍＪ／ｍｇ以下であることが更に好ましく、２０ｍＪ／ｍｇ以上４５ｍＪ／ｍｇ以下であることが殊更好ましく、２０ｍＪ／ｍｇ以上３５ｍＪ／ｍｇ以下であることが特に好ましい。 Specifically, the heat of fusion is preferably greater than 5 mJ / mg and less than 94 mJ / mg, more preferably 10 mJ / mg to 90 mJ / mg, and more preferably 20 mJ / mg to 80 mJ / mg. Is more preferably from 20 to 75 mJ / mg, particularly preferably from 20 to 45 mJ / mg, and particularly preferably from 20 to 35 mJ / mg.
　融解熱量は、熱可塑性樹脂組成物の結晶領域の多少、すなわち柔軟性を示す指標である。熱可塑性樹脂組成物の融解熱量は、用いる熱可塑性樹脂及びその含有量を調節することにより所望の範囲内とすることができる。熱可塑性樹脂組成物の融解熱量は、メルトブロー不織布の中央部より測定片を１ｍｇ採取し、後述する方法により求めることができる。 The heat of fusion is an indicator of the degree of flexibility of the crystalline region of the thermoplastic resin composition. The heat of fusion of the thermoplastic resin composition can be in the desired range by adjusting the thermoplastic resin to be used and the content thereof. The heat of fusion of the thermoplastic resin composition can be obtained by collecting 1 mg of a measurement piece from the central portion of the melt-blown nonwoven fabric, and determining it by the method described later.
　融解熱量が上記の上限未満であると、繊維中に存在する非晶領域が占める割合が多くなる。その結果、繊維が柔らかくなって紡糸工程時に起こる配向が抑制される。繊維の配向については後述する。融解熱量が上記の下限より大きいと、繊維が柔らかくなるために配向が生じにくくなり、一方、上記の上限未満であると、繊維中に存在する結晶領域が十分多く、繊維同士の融着が抑制され、繊維間の距離が狭まり耐水圧を向上できる。 If the heat of fusion is less than the above upper limit, the proportion of amorphous regions present in the fiber increases. As a result, the fibers become soft and the orientation that occurs during the spinning process is suppressed. The orientation of the fibers will be described later. If the heat of fusion is larger than the above lower limit, the fibers become soft and orientation is difficult to occur, while if it is less than the above upper limit, the number of crystal regions present in the fiber is sufficiently large and fusion between the fibers is suppressed And the distance between the fibers can be narrowed to improve the water pressure resistance.
　熱可塑性樹脂組成物には、融解熱量が所望の範囲内である熱可塑性樹脂が単独で含有されていてもよい。また、融解熱量が所望の範囲内となるように、融解熱量の異なる熱可塑性樹脂を２種以上混合することもできる。複数の熱可塑性樹脂を用いる場合、融解熱量が所望の範囲の上限以上の熱可塑性樹脂と、融解熱量が所望の範囲の下限以下の熱可塑性樹脂とを混合して、融解熱量が所望の範囲内となるようにしてもよいし、それぞれ融解熱量が所望の範囲である熱可塑性樹脂を複数混合してもよい。 The thermoplastic resin composition may contain only a thermoplastic resin whose heat of fusion is within a desired range. Moreover, two or more types of thermoplastic resins having different amounts of heat of fusion may be mixed so that the amount of heat of fusion falls within a desired range. When a plurality of thermoplastic resins are used, the heat of fusion is in the desired range by mixing the thermoplastic resin having the heat heat of fusion above the upper limit of the desired range and the thermoplastic resin of the heat heat of fusion below the lower limit of the desired range. Alternatively, a plurality of thermoplastic resins each having a desired range of heat of fusion may be mixed.
　熱可塑性樹脂としては、例えばポリオレフィン、ポリエステル、ポリエーテルエーテルケトン、ポリフェニレンサルファイド、ポリアミド等を用いることができる。中でもポリオレフィン又はポリエステルが好ましく、ポリオレフィンが特に好ましい。融解熱量が所望の範囲内となれば、これらの熱可塑性樹脂のうち、１種を単独で用いても、２種以上を併用してもよい。 As the thermoplastic resin, for example, polyolefin, polyester, polyetheretherketone, polyphenylene sulfide, polyamide and the like can be used. Among them, polyolefin or polyester is preferable, and polyolefin is particularly preferable. If the heat of fusion falls within the desired range, one of these thermoplastic resins may be used alone, or two or more thereof may be used in combination.
　熱可塑性樹脂組成物の７０質量％以上は、ポリオレフィンであることが好ましい。ポリオレフィンは、熱可塑性樹脂組成物の８０質量％以上を占めることがより好ましく、９０質量％以上を占めることがさらに好ましい。 It is preferable that 70% by mass or more of the thermoplastic resin composition is a polyolefin. As for polyolefin, it is more preferable to occupy 80 mass% or more of a thermoplastic resin composition, and it is more preferable to occupy 90 mass% or more.
　ポリオレフィンとして、α－オレフィンの単独重合体、又は２種以上のα－オレフィンの共重合体を用いることができる。これらはそれぞれ単独で用いても、２種以上を併用してもよい。ポリオレフィンとして、α－オレフィンと、アクリル酸、メタクリル酸、マレイン酸等の不飽和カルボン酸、これらの不飽和カルボン酸のエステル、及び酸無水物のいずれかとを共重合したもの等を用いることもできる。 As the polyolefin, a homopolymer of α-olefin or a copolymer of two or more α-olefins can be used. These may be used alone or in combination of two or more. As the polyolefin, those obtained by copolymerizing α-olefin with unsaturated carboxylic acid such as acrylic acid, methacrylic acid and maleic acid, ester of these unsaturated carboxylic acids, and acid anhydride can also be used. .
　α－オレフィンは、炭素数が２以上２０以下であることが好ましく、２以上１０以下であることがより好ましい。α－オレフィンとしては、プロピレン、エチレン、１－ブテン、１－ヘキセン、１－オクテン、４－メチル－１－ペンテン等が好ましく、プロピレン又はエチレンがより好ましく、プロピレンが最も好ましい。 The α-olefin preferably has 2 to 20 carbon atoms, and more preferably 2 to 10 carbon atoms. As the α-olefin, propylene, ethylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene and the like are preferable, propylene or ethylene is more preferable, and propylene is most preferable.
　α－オレフィンの単独重合体として、高結晶性ポリオレフィン又は低結晶性ポリオレフィンを用いることができる。高結晶性ポリオレフィンは、α－オレフィンの立体規則性が高いポリオレフィンである。高結晶性ポリオレフィンの具体例として、アイソタクチックポリプロピレン及びシンジオタクチックポリプロピレンなどの高結晶性ポリプロピレン；高密度ポリエチレン及び中密度ポリエチレンなどの高結晶性ポリエチレン等が挙げられる。 As a homopolymer of α-olefin, high crystalline polyolefin or low crystalline polyolefin can be used. The highly crystalline polyolefin is a polyolefin having high α-olefin stereoregularity. Specific examples of the high crystalline polyolefin include high crystalline polypropylene such as isotactic polypropylene and syndiotactic polypropylene; high crystalline polyethylene such as high density polyethylene and medium density polyethylene.
　メルトブロー不織布に一般に用いられる高結晶性ポリプロピレンは、融解熱量が９４ｍＪ／ｍｇ超であり、結晶領域が多く硬い樹脂である。紡糸工程時には紡糸線上にせん断流が生じており、結晶領域が多い剛直な繊維はその気流の向きに配向しやすい。その気流は、ＭＤ方向に駆動する捕集面上に吹き付けられるため、繊維はその配向方向をＭＤ方向と同じにしながら捕集面上に堆積すると考えられる。従って、繊維を構成する熱可塑性樹脂組成物の融解熱量を９４ｍＪ／ｍｇ未満とすることにより、繊維中に柔軟な非晶領域が多く存在し、せん断方向に応じた繊維の配向が生じにくくなる。その結果、捕集面上に堆積した不織布は、ＭＤ方向への繊維配向が小さくなり、ＣＤ方向の直進率が高くなると考えられる。 The highly crystalline polypropylene generally used for the meltblown nonwoven fabric has a heat of fusion of over 94 mJ / mg, and is a resin having many crystalline regions and being hard. During the spinning process, shear flow occurs on the spinning line, and rigid fibers having many crystalline regions tend to be oriented in the direction of the air flow. Since the air stream is blown onto the collecting surface driven in the MD direction, it is considered that the fibers are deposited on the collecting surface while making the orientation direction the same as the MD direction. Therefore, by setting the heat of fusion of the thermoplastic resin composition constituting the fiber to less than 94 mJ / mg, a large number of soft noncrystalline regions exist in the fiber, and the orientation of the fiber according to the shear direction hardly occurs. As a result, it is considered that in the non-woven fabric deposited on the collecting surface, the fiber orientation in the MD direction decreases and the rectilinear rate in the CD direction increases.
　高結晶性ポリオレフィンの融解熱量は、９４ｍＪ／ｍｇより大きいことが好ましく、９６ｍＪ／ｍｇ以上であることがより好ましく、９８ｍＪ／ｍｇ以上であることが更に好ましく、また、１２０ｍＪ／ｍｇ未満であることが好ましく、１１５ｍＪ／ｍｇ以下であることがより好ましく、１１０ｍＪ／ｍｇ以下であることが更に好ましく、具体的には９４ｍＪ／ｍｇより大きく１２０ｍＪ／ｍｇ未満であることが好ましく、９６ｍＪ／ｍｇ以上１１５ｍＪ／ｍｇ以下であることがより好ましく、９８ｍＪ／ｍｇ以上１１０ｍＪ／ｍｇ以下であることが更に好ましい。 The heat of fusion of the highly crystalline polyolefin is preferably greater than 94 mJ / mg, more preferably 96 mJ / mg or more, still more preferably 98 mJ / mg or more, and less than 120 mJ / mg. It is preferably 115 mJ / mg or less, more preferably 110 mJ / mg or less, and specifically more than 94 mJ / mg and less than 120 mJ / mg, and preferably 96 mJ / mg to 115 mJ / mg. It is more preferable that it is the following, and it is still more preferable that it is 98 to 110 mJ / mg.
　高結晶性ポリオレフィンは、メルトフローレート（ＭＦＲ）（２３０℃）が１００ｇ／１０分以上であることが好ましく、３００ｇ／１０分以上であることがより好ましく、また、２０００ｇ／１０分以下であることが好ましく、１８００ｇ／１０分以下であることがより好ましく、具体的には、１００ｇ／１０分以上２０００ｇ／１０分以下であることが好ましく、３００ｇ／１０分以上１８００ｇ／１０分以下であることがより好ましい。ＭＦＲは、ＪＩＳ　Ｋ７２１０に基づき荷重２．１６ｋｇ、温度２３０℃で測定する。ＭＦＲがこの上限以下であることで、紡糸工程時における樹脂の流動性が高すぎず、糸切れを抑制して、細い繊維が実現されやすい。一方、ＭＦＲがこの下限以上であることで、樹脂が流動性を有し、紡糸工程時に繊維を十分に延伸することができ、繊維径を細くすることができる。 The melt flow rate (MFR) (230 ° C.) of the highly crystalline polyolefin is preferably 100 g / 10 min or more, more preferably 300 g / 10 min or more, and 2000 g / 10 min or less Is more preferably 1800 g / 10 min or less, specifically 100 g / 10 min or more and 2000 g / 10 min or less and 300 g / 10 min or more and 1800 g / 10 min or less More preferable. MFR is measured at a temperature of 230 ° C. under a load of 2.16 kg according to JIS K7210. When the MFR is less than this upper limit, the fluidity of the resin at the time of the spinning process is not too high, and yarn breakage is suppressed and thin fibers are easily realized. On the other hand, when the MFR is at least the lower limit, the resin has fluidity, and the fiber can be sufficiently drawn during the spinning process, and the fiber diameter can be reduced.
　高結晶性ポリオレフィンは、重量平均分子量（Ｍｗ）が５０００以上であることが好ましく、１００００以上であることがより好ましく、１５０００以上であることがさらに好ましく、また、５０００００以下であることが好ましく、２０００００以下であることがより好ましく、１５００００以下であることがさらに好ましく、具体的には５０００以上５０００００以下であることが好ましく、１００００以上２０００００以下であることがより好ましく、１５０００以上１５００００以下であることがさらに好ましい。重量平均分子量がこの下限以上であることで、紡糸工程時に高分子鎖同士の絡まりが強く、糸切れを防止し、細い繊維が実現できる。一方、重量平均分子量がこの上限以下であることで、高分子鎖同士の絡まりが強過ぎず、紡糸工程時に繊維を十分に延伸でき、繊維径を細くすることができる。 The high crystalline polyolefin preferably has a weight average molecular weight (Mw) of 5,000 or more, more preferably 10,000 or more, still more preferably 15,000 or more, and preferably 500,000 or less, and 200,000. It is more preferable that it is the following, it is more preferable that it is 150000 or less, and it is specifically preferable that it is 5000 or more and 500000 or less, it is more preferable that it is 10000 or more and 200000 or less, and it is that More preferable. When the weight average molecular weight is at least the lower limit, the polymer chains are strongly entangled in the spinning process, yarn breakage can be prevented, and thin fibers can be realized. On the other hand, when the weight average molecular weight is not more than this upper limit, the entanglement between polymer chains is not too strong, the fiber can be sufficiently drawn during the spinning process, and the fiber diameter can be reduced.
　高結晶性ポリオレフィンは、分子量分布（平均分子量（Ｍｗ）／数平均分子量重量（Ｍｎ））が１．１以上であることが好ましく、１．５以上であることがより好ましく、２以上であることがさらに好ましく、また、５以下であることが好ましく、４以下であることがより好ましく、３．５以下であることがさらに好ましく、具体的には１．１以上５以下であることが好ましく、１．５以上４以下であることがより好ましく、２以上３．５以下であることがさらに好ましい。 The high crystalline polyolefin preferably has a molecular weight distribution (average molecular weight (Mw) / number average molecular weight (Mn)) of 1.1 or more, more preferably 1.5 or more, and 2 or more. Is more preferably 5 or less, more preferably 4 or less, still more preferably 3.5 or less, specifically 1.1 or more and 5 or less, It is more preferably 1.5 or more and 4 or less, and still more preferably 2 or more and 3.5 or less.
　低結晶性ポリオレフィンは、α－オレフィンの立体規則性が低いポリオレフィンである。低結晶性ポリオレフィンの具体例として、アタクチックポリプロピレン及び低立体規則性ポリプロピレンなどの低結晶性ポリプロピレン；低密度ポリエチレン及び直鎖状低密度ポリエチレンなどの低結晶性ポリエチレン等が挙げられる。低立体規則性ポリプロピレンは、公知のメタセロン触媒を用いてプロピレンを重合することにより得られる。 The low crystalline polyolefin is a polyolefin having low α-olefin stereoregularity. Specific examples of the low crystalline polyolefin include low crystalline polypropylene such as atactic polypropylene and low stereoregular polypropylene; low crystalline polyethylene such as low density polyethylene and linear low density polyethylene. The low stereoregular polypropylene is obtained by polymerizing propylene using a known methacone catalyst.
　低結晶性ポリオレフィンの融解熱量は、０ｍＪ／ｍｇより大きいことが好ましく、３ｍＪ／ｍｇ以上であることがより好ましく、５ｍＪ／ｍｇ以上であることがさらに好ましく、また、９４ｍＪ／ｍｇ未満であることが好ましく、８５ｍＪ／ｍｇ以下であることがより好ましく、７０ｍＪ／ｍｇ以下であることがさらに好ましく、具体的には０ｍＪ／ｍｇより大きく９４ｍＪ／ｍｇ未満であることが好ましく、３ｍＪ／ｍｇ以上８５ｍＪ／ｍｇ以下であることがより好ましく、５ｍＪ／ｍｇ以上７０ｍＪ／ｍｇ以下であることがさらに好ましい。 The heat of fusion of the low crystalline polyolefin is preferably greater than 0 mJ / mg, more preferably 3 mJ / mg or more, still more preferably 5 mJ / mg or more, and less than 94 mJ / mg. It is more preferably 85 mJ / mg or less, still more preferably 70 mJ / mg or less, specifically more than 0 mJ / mg and less than 94 mJ / mg, preferably 3 mJ / mg to 85 mJ / mg. The content is more preferably 5 mJ / mg or more and 70 mJ / mg or less.
　低結晶性ポリオレフィンは、ＭＦＲ（２３０℃）が１００ｇ／１０分以上であることが好ましく、１０００ｇ／１０分以上であることがより好ましく、１８００ｇ／１０分以上であることが更に好ましく、また、２５００ｇ／１０分以下であることが好ましく、２３００ｇ／１０分以下であることがより好ましく、２１００ｇ／１０分以下であることがさらに好ましく、具体的には１００ｇ／１０分以上２５００ｇ／１０分以下であることが好ましく、１０００ｇ／１０分以上２３００ｇ／１０分以下であることがより好ましく、１８００ｇ／１０分以上２１００ｇ／１０分以下であることがさらに好ましい。ＭＦＲは、ＪＩＳ　Ｋ７２１０に基づき荷重２．１６ｋｇ、温度２３０℃で測定する。 The low crystalline polyolefin preferably has MFR (230 ° C.) of 100 g / 10 min or more, more preferably 1000 g / 10 min or more, still more preferably 1800 g / 10 min or more, and 2500 g It is preferably 10 minutes or less, more preferably 2300 g / 10 minutes or less, still more preferably 2100 g / 10 minutes or less, and specifically 100 g / 10 minutes to 2500 g / 10 minutes Is preferably 1000 g / 10 minutes to 2300 g / 10 minutes, and more preferably 1800 g / 10 minutes to 2100 g / 10 minutes. MFR is measured at a temperature of 230 ° C. under a load of 2.16 kg according to JIS K7210.
　低結晶性ポリオレフィンは、重量平均分子量（Ｍｗ）が５０００以上であることが好ましく、２００００以上であることがより好ましく、３００００以上であることがさらに好ましく、また、１５００００以下であることが好ましく、７００００以下であることがより好ましく、５００００以下であることがさらに好ましく、具体的には５０００以上１５００００以下であることが好ましく、２００００以上７００００以下であることがより好ましく、３００００以上５００００以下であることがさらに好ましい。 The low crystalline polyolefin preferably has a weight average molecular weight (Mw) of 5,000 or more, more preferably 20,000 or more, still more preferably 30,000 or more, and preferably 150,000 or less, 70,000. The following is more preferable, 50000 or less is more preferable, and specifically, 5000 or more and 150000 or less is preferable, 20000 or more and 70000 or less is more preferable, and 30000 or more and 50000 or less More preferable.
　２種以上のα－オレフィンの共重合体は、低結晶性又は非晶性のオレフィン系エラストマーである。α－オレフィンの共重合体として、ランダム共重合体、ブロック共重合体、グラフト共重合体又は交互共重合体を用いることができる。ブロック共重合体である場合、α－オレフィンがアタクチック構造で結合していることが好ましい。以下、２種以上のα－オレフィンの共重合体をオレフィン系エラストマーという。 Copolymers of two or more α-olefins are low crystalline or amorphous olefin elastomers. As a copolymer of α-olefin, a random copolymer, a block copolymer, a graft copolymer or an alternating copolymer can be used. In the case of a block copolymer, it is preferable that the α-olefin be bonded by an atactic structure. Hereinafter, a copolymer of two or more α-olefins is referred to as an olefin-based elastomer.
　オレフィン系エラストマーは、融解熱量が０ｍＪ／ｍｇより大きく９４ｍＪ／ｍｇ未満であり、３ｍＪ／ｍｇ以上であることが好ましく、５ｍＪ／ｍｇ以上であることがより好ましく、また、９０ｍＪ／ｍｇ以下であることが好ましく、８５ｍＪ／ｍｇ以下であることがより好ましい。 The olefin-based elastomer has a heat of fusion greater than 0 mJ / mg and less than 94 mJ / mg, preferably 3 mJ / mg or more, more preferably 5 mJ / mg or more, and 90 mJ / mg or less Is more preferable, and 85 mJ / mg or less is more preferable.
　オレフィン系エラストマーは、α－オレフィン以外に、必要に応じて、ブタジエン、イソプレン、エチリデンノルボルネン、ジシクロペンタジエン等のポリエン化合物単位、環状オレフィン単位及びビニル芳香族化合物単位からなる群から選ばれる少なくとも１種を単量体として含んでいてもよい。 The olefin elastomer is at least one member selected from the group consisting of polyene compound units such as butadiene, isoprene, ethylidene norbornene and dicyclopentadiene, cyclic olefin units and vinyl aromatic compound units, as necessary, in addition to α-olefin May be contained as a monomer.
　オレフィン系エラストマーの具体例としては、例えば、プロピレン・エチレン共重合体、プロピレン・エチレン・１－ブテン共重合体、プロピレン・１－ブテン共重合体、プロピレン・エチレン・環状オレフィン共重合体、プロピレン・エチレン・ブタジエン共重合体、プロピレン・１－ブテン・スチレン共重合体等が挙げられる。これら共重合体の中でも、プロピレン・エチレン共重合体または、プロピレン・エチレン・１－ブテン共重合体が最も好ましい。これらのうち１種を単独で用いることも、２種以上を併用することもできる。 Specific examples of the olefin elastomer include, for example, propylene / ethylene copolymer, propylene / ethylene / 1-butene copolymer, propylene / 1-butene copolymer, propylene / ethylene / cyclic olefin copolymer, propylene / Examples thereof include ethylene / butadiene copolymer, propylene / 1-butene / styrene copolymer and the like. Among these copolymers, a propylene / ethylene copolymer or a propylene / ethylene / 1-butene copolymer is most preferable. One of these may be used alone, or two or more may be used in combination.
　オレフィン系エラストマーは、そのＭＦＲ（２３０℃）が、１０ｇ／１０分以上であることが好ましく、３００ｇ／１０分以上であることがより好ましく、２０００ｇ／１０分以下であることが好ましく、１８００ｇ／１０分以下であることがより好ましい。ＭＦＲは、ＪＩＳ　Ｋ７２１０に基づき荷重２．１６ｋｇ、温度２３０℃で測定する。 The olefin elastomer preferably has an MFR (230 ° C.) of 10 g / 10 min or more, more preferably 300 g / 10 min or more, and preferably 2000 g / 10 min or less, 1800 g / 10 min. More preferably, it is less than a minute. MFR is measured at a temperature of 230 ° C. under a load of 2.16 kg according to JIS K7210.
　オレフィン系エラストマーは、分子量分布（重量平均分子量（Ｍｗ）／数平均分子量重量（Ｍｎ））が１．１以上であることが好ましく、１．３以上であることがより好ましく、１．５以上であることがさらに好ましく、また、５以下であることが好ましく、４以下であることがより好ましく、３．５以下であることがさらに好ましい。 The olefin elastomer preferably has a molecular weight distribution (weight-average molecular weight (Mw) / number-average molecular weight (Mn)) of 1.1 or more, more preferably 1.3 or more, and 1.5 or more. Some are more preferable, and 5 or less is preferable, 4 or less is more preferable, and 3.5 or less is more preferable.
　オレフィン系エラストマーは、公知のチーグラー・ナッタ型触媒やシングルサイト触媒（例えばメタロセン系触媒）のような重合触媒を用いて製造することができる。 The olefin-based elastomer can be produced using a polymerization catalyst such as a known Ziegler-Natta type catalyst or a single site catalyst (for example, a metallocene type catalyst).
　熱可塑性樹脂組成物は、高結晶性ポリオレフィンと、低結晶性ポリオレフィン又はポリオレフィン系エラストマーとを含有することが好ましい。 The thermoplastic resin composition preferably contains a high crystalline polyolefin and a low crystalline polyolefin or a polyolefin-based elastomer.
　熱可塑性樹脂組成物は、融解熱量が９４ｍＪ／ｍｇ以上の第１のポリオレフィンと、融解熱量が９４ｍＪ／ｍｇ未満の第２のポリオレフィンとの混合物を含有することが好ましい。 The thermoplastic resin composition preferably contains a mixture of a first polyolefin whose heat of fusion is 94 mJ / mg or more and a second polyolefin whose heat of fusion is less than 94 mJ / mg.
　メルトブロー紡糸では、溶融樹脂が引き伸ばされることにより繊維が形成される。糸引き性や糸切れ抑制を考慮すると、熱可塑性樹脂組成物は、一般にメルトブローで用いられる融解熱量が９４ｍＪ／ｍｇ以上の高結晶性ポリプロピレンと、融解熱量が９４ｍＪ／ｍｇ未満の低結晶性ポリプロピレン又はポリプロピレン系エラストマーとの混合物を含有することが特に好ましい。 In melt blow spinning, fibers are formed by drawing a molten resin. In view of stringiness and yarn breakage suppression, the thermoplastic resin composition is generally a high crystalline polypropylene having a heat of fusion of 94 mJ / mg or more and a low crystalline polypropylene of a heat of fusion of less than 94 mJ / mg. It is particularly preferred to contain a mixture with a polypropylene-based elastomer.
　第２のポリオレフィンの好ましい具体例として、ＭＦＲ４００ｇ／１０分以上の流動性の高い低結晶性ポリプロピレン、ＭＦＲ４００ｇ／１０分未満の流動性の低い低結晶性ポリプロピレン、ＭＦＲ４００ｇ／１０分未満の流動性の低いポリプロピレン系エラストマーが挙げられる。 Preferred specific examples of the second polyolefin include high fluidity low crystalline polypropylene having MFR 400 g / 10 min or more, low fluidity low crystalline polypropylene having MFR 400 g / 10 min or less, and low fluidity MFR 400 g / 10 min Polypropylene-based elastomers can be mentioned.
　ＭＦＲ４００ｇ／１０分以上の流動性の高い低結晶性ポリプロピレンの含有量は、熱可塑性樹脂組成物全体の９０質量％以下であることが好ましく、８０質量％以下であることがより好ましく、７０質量％以下であることがさらに好ましい。流動性の高い低結晶性ポリプロピレンの含有量は、３質量％以上であることが好ましく、１０質量％以上であることがより好ましく、２０質量％以上であることがさらに好ましく、５０質量％以上であることが殊更好ましく、具体的には３質量％以上９０質量％以下であることが好ましく、１０質量％以上８０質量％以下であることがより好ましく、２０質量％以上７０質量％以下であることがさらに好ましく、５０質量％以上７０質量％以下であることが殊更好ましい。 The content of high fluidity low crystalline polypropylene having MFR of 400 g / 10 min or more is preferably 90% by mass or less, more preferably 80% by mass or less, of the entire thermoplastic resin composition, and 70% by mass It is more preferable that it is the following. The content of the low crystalline polypropylene having high fluidity is preferably 3% by mass or more, more preferably 10% by mass or more, further preferably 20% by mass or more, and 50% by mass or more. In particular, it is preferably 3% by mass to 90% by mass, more preferably 10% by mass to 80% by mass, and particularly preferably 20% by mass to 70% by mass. Is more preferable, and 50 to 70% by mass is particularly preferable.
　流動性の高い低結晶性ポリプロピレンの含有量がこの上限以下であることで、繊維中の非晶領域が多くなりすぎず、繊維同士の融着を抑制し、繊維間の距離が狭まり、耐水圧を向上できる。一方、流動性の高い低結晶性ポリプロピレンの含有量がこの下限以上であることで、繊維中の非晶領域が十分に存在して柔らかく、紡糸工程時に配向が起こりにくくなる。 When the content of the low crystalline polypropylene having high fluidity is not more than this upper limit, the number of amorphous regions in the fiber is not too large, the fusion between the fibers is suppressed, the distance between the fibers is narrowed, and the water pressure resistance Can be improved. On the other hand, when the content of the low crystalline polypropylene having high fluidity is not less than this lower limit, the amorphous region in the fiber is sufficiently present to be soft, and orientation becomes difficult to occur during the spinning process.
　ＭＦＲ４００ｇ／１０分未満の低結晶性ポリプロピレン又はＭＦＲ４００ｇ／１０分未満のポリプロピレン系エラストマーの含有量は、熱可塑性樹脂組成物全体の３０質量％以下であることが好ましく、３０質量％未満であることがより好ましく、２０質量％以下であることが更に好ましく、１５質量％以下であることが殊更好ましい。ポリプロピレン系エラストマーの含有量は、３質量％以上であることが好ましく、５質量％以上であることがより好ましく、１０質量％以上であることが殊更好ましく、２０質量％以上であることが特に好ましく、具体的には３質量％以上３０質量％以下であることが好ましく、３質量％以上３０質量％未満であることがより好ましく、５質量％以上２０質量％以下であることが更に好ましく、１０質量％以上２０質量％以下であることが殊更好ましく、２０質量％以上１５質量％以下であることが特に好ましく、１０質量％以上１５質量％以下であることが最も好ましい。 The content of the low crystalline polypropylene having an MFR of less than 400 g / 10 min or the polypropylene elastomer having an MFR of less than 400 g / 10 min is preferably 30% by mass or less of the entire thermoplastic resin composition, and is less than 30% by mass. More preferably, it is more preferably 20% by mass or less, and particularly preferably 15% by mass or less. The content of the polypropylene-based elastomer is preferably 3% by mass or more, more preferably 5% by mass or more, particularly preferably 10% by mass or more, particularly preferably 20% by mass or more Specifically, it is preferably 3% by mass to 30% by mass, more preferably 3% by mass to less than 30% by mass, still more preferably 5% by mass to 20% by mass, and 10 It is particularly preferable that the content is not less than 20% by mass, particularly preferably not less than 20% by mass and not more than 15% by mass, and most preferably 10% by mass to 15% by mass.
　一般に、ＭＦＲ４００ｇ／１０分未満の低結晶性ポリプロピレン及びＭＦＲ４００ｇ／１０分未満のポリプロピレン系エラストマーは、メルトブロー用のポリプロピレン樹脂と比べて流動性が低い。その含有量がこの上限以下であることにより、樹脂全体の流動性が上がり、紡糸工程時に十分に繊維を延伸でき、繊維径が細くなる。繊維中の非晶領域を大きくしつつ、紡糸工程にて細い繊維を実現するためには、ＭＦＲ４００ｇ／１０分未満の低結晶性ポリプロピレン、ＭＦＲ４００ｇ／１０分未満のポリプロピレン系エラストマーの含有量が上記範囲内であることが好ましい。 In general, low crystalline polypropylene having a MFR of less than 400 g / 10 min and polypropylene-based elastomer having a MFR of less than 400 g / 10 min have lower fluidity than a polypropylene resin for melt blowing. When the content is less than this upper limit, the flowability of the entire resin is increased, the fibers can be sufficiently drawn during the spinning process, and the fiber diameter becomes thin. In order to realize a thin fiber in the spinning process while enlarging the amorphous region in the fiber, the content of the low crystalline polypropylene having a MFR of less than 400 g / 10 min and the polypropylene elastomer having a MFR of less than 400 g / 10 min is in the above range. It is preferably inside.
　第１のポリオレフィンの具体例として、高結晶性ポリプロピレンが挙げられる。第１のポリプロピレンと第２のポリプロピレンとの質量基準での配合比（第１のポリプロピレン／第２のポリプロピレン）は、種類に応じて選択される。 A high crystalline polypropylene is mentioned as a specific example of a 1st polyolefin. The compounding ratio (first polypropylene / second polypropylene) of the first polypropylene and the second polypropylene on a mass basis is selected according to the type.
　例えば、第１のポリプロピレン（高結晶性ポリプロピレン）としてＭｏｐｌｅｎ（登録商標）　ＨＰ４６１Ｙ（Ｌｙｏｎｄｅｌｌｂａｓｅｌｌ社製）を用い、第２のポリプロピレン（流動性の高い低結晶性ポリプロピレン）としてＭＦＲ２６００ｇ／１０分のＬ－ＭＯＤＵ（登録商標）　Ｓ４００（出光興産株式会社製）を用いる場合、これらの配合比は、５／９５より大きいことが好ましく、１０／９０以上であることがより好ましく、２０／８０以上であることがさらに好ましく、３０／７０以上であることが殊更好ましく、また、９７／３以下であることが好ましく、９０／１０以下であることがより好ましく、８０／２０以下であることがさらに好ましく、５０／５０以下であることが殊更好ましく、具体的には５／９５より大きく９７／３以下であることが好ましく、１０／９０以上９０／１０以下であることがより好ましく、２０／８０以上８０／２０以下であることがさらに好ましく、３０／７０以上５０／５０以下であることが殊更好ましい。 For example, Mopren (registered trademark) HP 461Y (manufactured by Lyondellbasell) is used as the first polypropylene (high crystalline polypropylene), and an L-MODU of MFR 2600 g / 10 min as the second polypropylene (high flowability low crystalline polypropylene) When using (registered trademark) S400 (made by Idemitsu Kosan Co., Ltd.), the blending ratio thereof is preferably 5/95 or more, more preferably 10/90 or more, and 20/80 or more. More preferably, it is particularly preferably 30/70 or more, and it is preferably 97/3 or less, more preferably 90/10 or less, still more preferably 80/20 or less, and 50/70. It is particularly preferable that the ratio is 50 or less, specifically, larger than 5/95 It is preferably 97/3 or less, more preferably 10/90 or more and 90/10 or less, still more preferably 20/80 or more and 80/20 or less, and 30/70 or more and 50/50 or less. Is particularly preferred.
　第２のポリプロピレンとして用い得る流動性の低い低結晶性ポリプロピレンの具体例としては、例えばＭＦＲ３５０ｇ／１０分のＬ－ＭＯＤＵ（登録商標）　Ｓ６００及びＭＦＲ５０ｇ／１０分のＬ－ＭＯＤＵ（登録商標）　Ｓ９０１（いずれも出光興産株式会社製）が挙げられる。第２のポリプロピレンとして用い得るプロピレン系エラストマーとしては、例えば、ＭＦＲ１０ｇ／１０分のタフレセン（登録商標）　Ｈ５００２（住友化学工業株式会社製）が挙げられる。 Specific examples of low fluidity low crystalline polypropylene that can be used as the second polypropylene include, for example, L-MODU S600 of MFR 350 g / 10 min and L-MODU S 901 of MFR 50 g / 10 min. All are made by Idemitsu Kosan Co., Ltd.). As a propylene-based elastomer which can be used as the second polypropylene, for example, Tafresen (registered trademark) H5002 (manufactured by Sumitomo Chemical Co., Ltd.) can be mentioned.
　こうした第２のポリプロピレンを、第１のポリプロピレンとしてのＭｏｐｌｅｎ（登録商標）　ＨＰ４６１Ｙ（Ｌｙｏｎｄｅｌｌｂａｓｅｌｌ社製）とともに用いる場合、これらの配合比（第１のポリプロピレン／第２のポリプロピレン）は、７０／３０以上であることが好ましく、７５／２５以上であることがより好ましく、８０／２０以上であることがさらに好ましく、８５／１５以上であることが殊更好ましく、また、９７／３以下であることが好ましく、９５／５以下であることがより好ましく、９０／１０以下であることがさらに好ましく、具体的には７０／３０以上９５／５以下であることが好ましく、７５／２５以上９５／５以下であることがより好ましく、８０／２０以上９０／１０以下であることがさらに好ましく、８５／１５以上９０／１０以下であることが殊更好ましい。 When such second polypropylene is used together with Moplen (registered trademark) HP 461Y (manufactured by Lyondellbasell) as the first polypropylene, the compounding ratio (first polypropylene / second polypropylene) is 70/30 or more. Is preferably 75/25 or more, more preferably 80/20 or more, particularly preferably 85/15 or more, and preferably 97/3 or less. 95/5 or less is more preferable, 90/10 or less is more preferable, and specifically 70/30 or more and 95/5 or less is preferable, and 75/25 or more and 95/5 or less Is more preferably 80/20 or more and 90/10 or less, and 8 / It is especially preferably 15 to 90/10.
　ポリエステルとしては、例えばポリエチレンテレフタレート、ポリブチレンテレフタレート、ポリトリメチレンテレフタレート等を用いることができる。中でも、ポリエチレンテレフタレート又はポリブチレンテレフタレートが好ましい。複数種のポリエステルを混合して使用する場合、いずれかのポリエステルが全ポリエステルの５０質量％以上であることが好ましく、７０質量％以上であることがより好ましく、９０質量％以上であることがさらに好ましい。 As polyester, for example, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate and the like can be used. Among them, polyethylene terephthalate or polybutylene terephthalate is preferred. When plural types of polyesters are mixed and used, it is preferable that one of the polyesters is 50% by mass or more of the total polyester, more preferably 70% by mass or more, and further preferably 90% by mass or more. preferable.
　ポリアミドとしては、例えばポリアミド３、ポリアミド４、ポリアミド６、ポリアミド６６、ポリアミド１２等を用いることができる。 As the polyamide, for example, polyamide 3, polyamide 4, polyamide 6, polyamide 66, polyamide 12 and the like can be used.
　熱可塑性樹脂組成物は、本発明の効果を損なわない程度に、結晶核剤、艶消し剤、顔料、染料、防カビ剤、抗菌剤、難燃剤、親水剤、光安定剤、酸化防止剤、老化防止剤、合成油、ワックス、着色防止剤、粘度調整剤等の添加剤を含有していてもよい。 The thermoplastic resin composition is a nucleating agent, a matting agent, a pigment, a dye, an antifungal agent, an antibacterial agent, a flame retardant, a hydrophilic agent, a light stabilizer, an antioxidant, to the extent that the effects of the present invention are not impaired. You may contain additives, such as an antiaging agent, a synthetic oil, a wax, a coloring inhibitor, and a viscosity modifier.
　本発明に係るメルトブロー不織布は、充填率が３％以上であることが好ましく、５％以上であることがより好ましく、６％以上であることがさらに好ましい。充填率が大きいほど繊維が緻密に存在するため、メルトブロー不織布の耐水圧が大きくなる。充填率は高いほどメルトブロー不織布が硬くなり、低いほど柔らかくなる。メルトブロー不織布を着用物品として用いる際には柔らかい方が好まれることから、充填率が３０％以下であることが好ましく、２０％以下であることがより好ましく、１５％以下であることがさらに好ましい。本発明に係るメルトブロー不織布は、充填率が具体的には３％以上３０％以下であることが好ましく、５％以上２０％以下であることがより好ましく、６％以上１５％以下であることがさらに好ましい。 The filling ratio of the melt-blown nonwoven fabric according to the present invention is preferably 3% or more, more preferably 5% or more, and still more preferably 6% or more. As the filling rate is larger, the fibers are more densely present, and the water pressure resistance of the melt-blown nonwoven fabric becomes larger. The higher the filling rate, the harder the meltblown nonwoven, and the lower it is softer. When a melt-blown non-woven fabric is used as a wearing article, the filling rate is preferably 30% or less, more preferably 20% or less, and still more preferably 15% or less because softness is preferred. Specifically, the melt-blown nonwoven fabric according to the present invention preferably has a filling rate of 3% to 30%, more preferably 5% to 20%, and more preferably 6% to 15%. More preferable.
　充填率は、後述する不織布製造装置のノズルから捕集面までの距離を４００ｍｍ以下とすることで、気流の風圧により繊維を圧密化し、上記の下限以上とすることができる。また、製造時にカレンダーロールなどを用いてメルトブロー不織布を圧縮し、充填率を上記の下限以上に調節することもできる。 The packing ratio can be made to be more than the above-mentioned lower limit by compacting the fibers by the wind pressure of the air flow by setting the distance from the nozzle of the nonwoven fabric manufacturing device described later to the collecting surface to 400 mm or less. Moreover, a melt-blown nonwoven fabric can be compressed at the time of manufacture using a calender roll etc., and a filling rate can also be adjusted more than said lower limit.
　充填率を算出するには、まず、後述する方法で取得した不織布に対して、オムロン株式会社製レーザー変位計を用いて、メルトブロー不織布に４ｋＰａの圧力が掛かるように荷重を加えた状態で厚みを測定する。後述する方法に従い、後述の数式（２）により充填率を求める。 In order to calculate the filling rate, first, a thickness is set in a state where a load of 4 kPa is applied to the melt-blown nonwoven fabric using a laser displacement meter made by OMRON Corporation with respect to the nonwoven fabric obtained by the method described later taking measurement. According to the method mentioned later, a filling rate is calculated | required by numerical formula (2) mentioned later.
　本発明に係るメルトブロー不織布は、地合い指数が３００以下であることが好ましく、２８０以下であることがより好ましく、２６０以下であることがさらに好ましく、２５０以下であることが殊更好ましく、２００以下であることが特に好ましい。後述する不織布製造装置のノズルから捕集面までの距離を４００ｍｍ以下とし、繊維の堆積にムラが生じることを抑制することによって、地合い指数を上記の上限以下とすることができる。 The melt-blown nonwoven fabric according to the present invention preferably has a formation index of 300 or less, more preferably 280 or less, still more preferably 260 or less, and particularly preferably 250 or less. Is particularly preferred. The formation index can be made equal to or less than the above-described upper limit by setting the distance from the nozzle of the nonwoven fabric manufacturing apparatus described later to the collection surface to 400 mm or less and suppressing the occurrence of unevenness in fiber deposition.
　地合い指数は、メルトブロー法により不織布を製造する際には、現実的には小さくて３０程度である。地合い指数が小さいほど繊維が均一に存在するため、メルトブロー不織布の耐水圧が大きくなる。地合い指数の測定は、メルトブロー不織布の短手方向の中央部であり且つ長手方向の任意の位置に対して、後述する方法を用いて行う。 The formation index is practically as small as about 30 when producing a non-woven fabric by the melt-blowing method. As the formation index is smaller, the fibers are uniformly present, and the water pressure resistance of the melt-blown nonwoven fabric becomes larger. The measurement of the formation index is carried out using the method which will be described later, at any position in the longitudinal direction and at the center of the meltblown nonwoven fabric in the lateral direction.
　なお、スパンボンド不織布、エアスルー不織布などの基材と熱エンボスによって一体化されたメルトブロー不織布は、引き剥がしてサンプルを得る際に穴が開く場合がある。穴の開いたサンプルは、穴に由来する吸光度Ｅを差し引いた後の吸光度の標準偏差と平均値を用いて地合い指数を算出する。 In addition, the melt-blown nonwoven fabric integrated by heat embossing with base materials, such as a spun bond nonwoven fabric and an air through nonwoven fabric, may peel when peeling off and obtaining a sample. For the samples with holes, the formation index is calculated using the standard deviation of the absorbance and the mean value after subtraction of the absorbance E derived from the holes.
　本発明に係るメルトブロー不織布は、充填率及び地合い指数を上記範囲にするという観点から、坪量が２０ｇ／ｍ2以下であることが好ましく、１５ｇ／ｍ2以下であることがより好ましく、１０ｇ／ｍ2以下であることがさらに好ましい。坪量がこの上限以下であることにより、気流の風圧に対する繊維の体積が小さくなるため圧密化しやすくなり、充填率が十分なものとなる。また、坪量がこの上限以下であることにより、堆積工程において均一に堆積され、地合い指数が十分なものとなる。 The melt-blown nonwoven fabric according to the present invention preferably has a basis weight of 20 g / m 2 or less, more preferably 15 g / m 2 or less, and more preferably 10 g / m 2 from the viewpoint of setting the filling rate and the formation index to the above range. More preferably, it is m 2 or less. When the basis weight is not more than this upper limit, the volume of fibers to the air pressure of the air flow is reduced, so that consolidation becomes easy, and the filling rate becomes sufficient. In addition, when the basis weight is below the upper limit, uniform deposition is performed in the deposition step, and the formation index is sufficient.
　坪量は、メルトブロー不織布が耐水圧を発現するために、１ｇ／ｍ2以上が好ましく、２ｇ／ｍ2以上がより好ましい。本発明に係るメルトブロー不織布の坪量は、具体的には１ｇ／ｍ2以上２０ｇ／ｍ2以下であることが好ましく、１ｇ／ｍ2以上１５ｇ／ｍ2以下であることがより好ましく、２ｇ／ｍ2１０ｇ／ｍ2以下であることがさらに好ましい。 Basis weight for meltblown nonwoven express water pressure, 1 g / m 2 or more preferably, 2 g / m 2 or more is more preferable. The basis weight of melt-blown nonwoven fabric according to the present invention, more preferably specifically it is preferably 1 g / m 2 or more 20 g / m 2 or less, 1 g / m 2 or more 15 g / m 2 or less, 2 g / More preferably, it is m 2 10 g / m 2 or less.
　メルトブロー不織布単体の場合、坪量は、０．０５ｍ四方の面積当たりの重量から測定することができる。メルトブロー不織布が樹脂製フィルムや紙、スパンボンド不織布、エアスルー不織布などの基材とホットメルト等で接着されて複合体とされている場合は、まず、コールドスプレーもしくはドライヤー等で加熱してホットメルトの接着力を下げて基材からメルトブロー不織布を剥がす。メルトブロー不織布に付着したホットメルトは、ホットメルトが可溶なトルエン等の大過剰の有機溶媒中にメルトブロー不織布を２４時間浸することで溶解させる。有機溶媒から取り出したメルトブロー不織布を乾燥させ、該メルトブロー不織布の坪量を上記方法にて測定する。 In the case of the melt-blown nonwoven fabric alone, the basis weight can be measured from the weight per area of 0.05 m. When a melt-blown nonwoven fabric is bonded to a resin film, paper, a base material such as a spunbond nonwoven fabric, or an air-through nonwoven fabric by a hot melt or the like to form a composite, the hot melt is first heated by cold spray or a dryer. The adhesion is reduced and the meltblown nonwoven is peeled off from the substrate. The hot melt adhered to the meltblown nonwoven is dissolved by soaking the meltblown nonwoven for 24 hours in a large excess of an organic solvent such as toluene in which the hot melt is soluble. The meltblown nonwoven fabric removed from the organic solvent is dried, and the basis weight of the meltblown nonwoven fabric is measured by the above method.
　なお、このメルトブロー不織布を複合体から取り出す方法は、本願明細書の他の測定においても適用される。メルトブロー不織布が樹脂製フィルムやスパンボンド不織布、エアスルー不織布などの基材と熱エンボスによって一体化されている場合は、まず、エンボス部を取り除くようにメルトブロー不織布を引き剥がす。次いで、エンボス部箇所の穴が空いた状態のメルトブロー不織布の面積を二値化等の画像処理から求め、その時の重量から坪量を測定すればよい。 In addition, the method of taking out the melt-blown nonwoven fabric from the composite is also applied to other measurements in the present specification. When the meltblown nonwoven fabric is integrated with a resin film, a spunbond nonwoven fabric, a base material such as an air through nonwoven fabric by heat embossing, the meltblown nonwoven fabric is first peeled off so as to remove the embossed portion. Next, the area of the melt-blown nonwoven fabric in a state in which the holes of the embossed portion are open may be obtained from image processing such as binarization, and the basis weight may be measured from the weight at that time.
　坪量の測定に供する０．０５ｍ四方の面積のメルトブロー不織布は、連続したメルトブロー不織布から得ることが好ましい。製品から取得できる一枚のメルトブロー不織布の面積が小さい場合、同製品から取得した複数のメルトブロー不織布の面積の合計とすることができる。 It is preferable that the melt-blown nonwoven fabric of 0.05 m square area to be subjected to measurement of basis weight be obtained from a continuous melt-blown nonwoven fabric. When the area of one melt-blown nonwoven fabric obtainable from a product is small, it can be the sum of the areas of a plurality of melt-blown nonwoven fabrics obtained from the same product.
　メルトブロー不織布が樹脂製フィルム、スパンボンド不織布、エアスルー不織布などの基材と熱エンボスによって一体化されている場合は、後述する耐水圧の測定及び変形後耐水圧の測定以外において、エンボス部を含まないようにメルトブロー不織布を適宜引き剥がして、測定対象とする。 When the meltblown non-woven fabric is integrated with a resin film, a spunbond non-woven fabric, an air-through non-woven fabric, or the like by heat embossing, it does not include the embossed portion except for the measurement of water pressure and the measurement of water pressure after deformation as described later. As described above, the meltblown non-woven fabric is appropriately peeled off to make a measurement target.
　以上のように、本発明に係るメルトブロー不織布は、平均繊維径が４μｍ以下であり、且つ平面に沿い、且つ繊維の直進率が最も高い第１方向及び該第１方向に直交する第２方向における繊維の直進率がいずれも３５％以上であるため、耐水圧に優れ、変形が生じても繊維間に隙間を生じにくく、耐水圧の低下を抑制することができる。 As described above, the melt-blown nonwoven fabric according to the present invention has an average fiber diameter of 4 μm or less, and along a plane, in the first direction in which the rectilinear rate of fibers is the highest and in the second direction orthogonal to the first direction. Since the straightness rate of the fibers is 35% or more in any case, the water pressure resistance is excellent, and even if deformation occurs, it is difficult to form a gap between the fibers, and a decrease in water pressure resistance can be suppressed.
　メルトブロー不織布の耐水圧は、上述と同様の手段でメルトブロー不織布を取得して測定することができる。ただし、メルトブロー不織布がスパンボンド不織布、エアスルー不織布などの基材と熱エンボスによって一体化されている場合は、その形態のまま耐水圧を測定し、その値をメルトブロー不織布の耐水圧とする。このような積層不織布の場合、目の細かいメルトブロー不織布が耐水圧を決める層であるため、積層不織布全体としての耐水圧をメルトブロー不織布の耐水圧とみなすことができる。 The water pressure resistance of the meltblown nonwoven fabric can be measured by obtaining the meltblown nonwoven fabric by the same means as described above. However, when the meltblown nonwoven fabric is integrated with a substrate such as a spunbond nonwoven fabric or an air through nonwoven fabric by heat embossing, the water pressure resistance is measured as it is, and the value is taken as the water pressure resistance of the meltblown nonwoven fabric. In the case of such a laminated non-woven fabric, the fine melt-blown non-woven fabric is a layer that determines the water pressure resistance, so the water pressure resistance of the entire laminated non-woven fabric can be regarded as the water pressure resistance of the melt-blown non-woven fabric.
　本発明に係るメルトブロー不織布の用途は特に限定されず、その特性を生かして様々な用途に用いることができる。本発明に係るメルトブロー不織布は、単層で、あるいは積層して用いることができ、本発明に係るメルトブロー不織布を複数積層してもよいし、スパンボンド不織布やエアスルー不織布等の公知の他の不織布と共に積層してもよい。さらに、本発明に係るメルトブロー不織布は、必要に応じてエンボス加工が施されていてもよい。 The application of the melt-blown nonwoven fabric according to the present invention is not particularly limited, and can be used for various applications by taking advantage of its characteristics. The melt-blown nonwoven fabric according to the present invention can be used as a single layer or as a laminate, and a plurality of melt-blown nonwoven fabrics according to the present invention may be laminated, together with other known nonwoven fabrics such as spunbonded nonwoven fabric and air through nonwoven fabric. It may be stacked. Furthermore, the melt-blown nonwoven fabric according to the present invention may be embossed if necessary.
　具体的には、スパンボンド層とメルトブローン層とをそれぞれ紡糸した後、これらを積層して熱エンボスによって一体化してもよい。あるいは、スパンボンド不織布を紡糸した後、別途用意されたメルトブロー不織布を積層してエンボス加工することもできる。さらに、メルトブロー不織布とスパンボンド不織布とを別個に製造して、熱エンボスにより一体化してもよい。いずれの場合も、上述と同様にしてエンボス部を含まないようにメルトブロー不織布を適宜引き剥がして坪量を測定することができる。 Specifically, after spun and spun, respectively, the spun bond layer and the meltblown layer may be laminated and integrated by heat embossing. Alternatively, after spinning a spunbond nonwoven, separately prepared meltblown nonwoven can be laminated and embossed. Furthermore, the meltblown nonwoven and the spunbonded nonwoven may be separately manufactured and integrated by heat embossing. In any case, the basis weight can be measured by appropriately peeling off the meltblown nonwoven fabric so as not to include the embossed portion in the same manner as described above.
　本発明に係るメルトブロー不織布は、例えば、使い捨ておむつや生理用ナプキン、失禁パッドなどの吸収性物品の構成部材として用いることができ、変形による耐水圧の低下が抑制されるため、特に耐水性が要求される防漏シートとして好適である。このような吸収性物品は、本発明に係るメルトブロー不織布からなる防漏シート、吸収体及び表面シートを積層することにより製造することができる。また、本発明に係るメルトブロー不織布は、衛生マスク、液体フィルタ、エアフィルタ、電池セパレータ、手袋等に使用することもできる。 The melt-blown nonwoven fabric according to the present invention can be used as a component of absorbent articles such as disposable diapers, sanitary napkins, and incontinence pads, for example, and a drop in water pressure resistance due to deformation is suppressed. Is suitable as a leak-proof sheet. Such an absorbent article can be manufactured by laminating the leak-barrier sheet, the absorber and the top sheet, which are made of the melt-blown nonwoven fabric according to the present invention. The melt-blown non-woven fabric according to the present invention can also be used for sanitary masks, liquid filters, air filters, battery separators, gloves and the like.
　次に、本発明に係るメルトブロー不織布の製造方法を説明する。本発明に係るメルトブロー不織布は、メルトブロー不織布の製造に従来用いられる公知の不織布製造装置を用いて、メルトブロー法により製造することができる。 Next, the method for producing a meltblown nonwoven fabric according to the present invention will be described. The melt-blown nonwoven fabric according to the present invention can be manufactured by a melt-blowing method using a known nonwoven fabric manufacturing apparatus conventionally used for manufacturing a melt-blown nonwoven fabric.
　不織布製造装置は、例えば、スクリューを内蔵したバレル及び原料投入部を備えた押出機と、押出機に直接、又はギアポンプ等を介して接続されたダイと、繊維状となった溶融物を堆積するための捕集面とを備える。ダイには、溶融物を吐出させる複数のノズルが直列配置され、各ノズルの両側に吹き出し口を備えており、吹き出し口から高温高圧の気流（熱風）を噴射して、ノズルから吐出された溶融物を延伸して繊維状とする。複数のノズルは、好ましくは一定の間隔で直列配置される。ノズルの口径は数百μｍであることが好ましい。高温高圧の気流は、好ましくは空気流であるが、他のガスの気流であってもよい。捕集面としては、ネットコンベアや捕集スクリーンなど公知のものを用いることができる。 The nonwoven fabric manufacturing apparatus deposits, for example, an extruder provided with a barrel incorporating a screw and a raw material feeding part, a die connected directly to the extruder or via a gear pump and the like, and a fibrous melt And a collection surface. A plurality of nozzles for discharging the melt are arranged in series in the die, and blowout ports are provided on both sides of each nozzle, and a high temperature / high pressure air stream (hot air) is jetted from the blowout port to melt the melt discharged from the nozzles The product is stretched to form a fiber. The plurality of nozzles are preferably arranged in series at regular intervals. The bore diameter of the nozzle is preferably several hundred μm. The high temperature and high pressure gas flow is preferably an air flow, but may be a gas flow of another gas. As the collecting surface, a known one such as a net conveyor or a collecting screen can be used.
　本発明に係るメルトブロー不織布の製造方法は、平均繊維径が４μｍ以下であるメルトブロー不織布の製造方法であって、熱可塑性樹脂組成物を例えばペレットの形態で原料投入部から押出機内に供給し、押出機中において加熱溶融した後、溶融物をダイに供給してノズルから吐出させ、吐出した溶融物を高温高圧の気流（熱風）により延伸させて繊維状とする紡糸工程を備える。繊維状となった溶融物は、堆積工程において捕集面上に堆積され、繊維同士が互いに融着することによりメルトブロー不織布となる。 The method for producing a melt-blown nonwoven fabric according to the present invention is a method for producing a melt-blown nonwoven fabric having an average fiber diameter of 4 μm or less, for example, supplying a thermoplastic resin composition in the form of pellets from an input portion into an extruder After heating and melting in the machine, the melt is supplied to a die and discharged from a nozzle, and the discharged melt is drawn by a stream (hot air) of high temperature and high pressure to form a fibrous form. The fibrous melt is deposited on the collecting surface in the deposition step, and the fibers are fused together to form a meltblown nonwoven fabric.
　本発明に係るメルトブロー不織布の製造方法において用いられる熱可塑性樹脂組成物としては、上述の熱可塑性樹脂組成物を用いることができる。熱可塑性樹脂組成物は、ペレットの代わりに、熱可塑性樹脂及び必要に応じて配合される成分を押出機に直接投入することによって調製されてもよい。 The above-mentioned thermoplastic resin composition can be used as a thermoplastic resin composition used in the manufacturing method of the melt blow nonwoven fabric concerning the present invention. The thermoplastic resin composition may be prepared by directly charging the thermoplastic resin and the component to be optionally blended into the extruder instead of the pellet.
　本発明に係るメルトブロー不織布の製造方法は、紡糸工程における気流の温度（熱風温度）を２６０℃以下とし、２５０℃以下とすることが好ましく、２４０℃以下とすることがより好ましい。気流の温度がこの上限以下となることで、繊維が粘着性を有する時間が短くなることにより繊維同士の絡み合いが生じにくく、繊維の空気抵抗が抑えられ、紡糸工程においてＭＤ方向に配向しにくく、ＣＤ方向の繊維の直進率が高くなると考えられる。また、気流の温度の下限は、熱可塑性樹脂組成物の融点以上とする必要がある。融点は示差走査熱量測定（ＤＳＣ）にて測定を行い、３０℃から２０℃／分で昇温しながらＤＳＣ曲線を得て、３０～２４０℃に現れた最も高い温度の吸熱ピーク点における温度を融点とする。 In the method for producing a melt-blown nonwoven fabric according to the present invention, the temperature (hot air temperature) of the air flow in the spinning step is 260 ° C. or less, preferably 250 ° C. or less, and more preferably 240 ° C. or less. When the temperature of the air flow becomes equal to or lower than this upper limit, the time for which the fibers have tackiness is shortened, entanglement of the fibers is less likely to occur, the air resistance of the fibers is suppressed, and it is difficult to orient in the MD direction in the spinning process, It is considered that the linear movement rate of the fiber in the CD direction is high. Further, the lower limit of the temperature of the air flow needs to be equal to or higher than the melting point of the thermoplastic resin composition. The melting point is measured by differential scanning calorimetry (DSC), a DSC curve is obtained while raising the temperature from 30 ° C. to 20 ° C./min, and the temperature at the highest endothermic peak point appearing at 30 to 240 ° C. Let it be the melting point.
　熱可塑性樹脂組成物は、高結晶性ポリプロピレンを含むことが好ましい。熱風温度は、高結晶性ポリプロピレンの融点である１６０℃以上が好ましく、１８０℃以上がより好ましく、２００℃以上が更に好ましい。具体的には、熱風温度は１６０℃以上２６０℃以下が好ましく、１８０℃以上２５０℃以下がより好ましく、２００℃以上２４０℃以下が更に好ましい。 The thermoplastic resin composition preferably contains highly crystalline polypropylene. The hot air temperature is preferably 160 ° C. or higher, which is the melting point of highly crystalline polypropylene, more preferably 180 ° C. or higher, and still more preferably 200 ° C. or higher. Specifically, the hot air temperature is preferably 160 ° C. or more and 260 ° C. or less, more preferably 180 ° C. or more and 250 ° C. or less, and still more preferably 200 ° C. or more and 240 ° C. or less.
　本発明に係るメルトブロー不織布の平均繊維径を確実に４μｍ未満とする観点から、紡糸工程における気流の流量を気流が吹き出す幅１ｍ当たり５００Ｎｍ3／ｈｒ以上とすることが好ましく、７００Ｎｍ3／ｈｒ以上とすることがより好ましい。また、繊維が延伸される過程での糸切れを抑制し、結果として繊維径を細くするため、気流の流量を気流が吹き出す幅１ｍ当たり１７００Ｎｍ3／ｈｒ以下とすることが好ましく、１３００Ｎｍ3／ｈｒ以下とすることがさらに好ましい。 From the viewpoint of the average fiber diameter of meltblown nonwoven fabric according to the present invention ensures less than 4 [mu] m, it is preferable that the flow rate of the air flow and air flow width 1m per 500 Nm 3 / hr or more to be blown in the spinning process, 700 Nm 3 / hr or more and It is more preferable to do. In addition, in order to suppress yarn breakage in the process of drawing the fiber and to make the diameter of the fiber smaller as a result, it is preferable to set the flow rate of the air flow to 1700 Nm 3 / hr or less per 1 m width of the air flow, 1300 Nm 3 / hr It is more preferable to set it as the following.
　本発明に係るメルトブロー不織布の製造方法は、不織布製造装置のノズルから捕集面までの距離を４００ｍｍ以下とすることが好ましく、３００ｍｍ以下とすることがより好ましく、１５０ｍｍ以下とすることがさらに好ましい。ノズルから捕集面までの距離がこの上限以下となることで、繊維が緻密に堆積でき、耐水圧が向上すると考えられる。メルトブロー法では、溶融した繊維を冷却して堆積することで、溶融繊維同士の合一を防ぎ、耐水圧を向上することができる。そのため、繊維の堆積時に繊維が冷えていることが好ましく、ノズルから捕集面までの距離は５０ｍｍ以上であることが好ましく、５０ｍｍ以上が好ましく、８０ｍｍ以上がより好ましく、１００ｍｍ以上がさらに好ましい。 In the method for producing a meltblown nonwoven fabric according to the present invention, the distance from the nozzle of the nonwoven fabric production apparatus to the collection surface is preferably 400 mm or less, more preferably 300 mm or less, and still more preferably 150 mm or less. When the distance from the nozzle to the collecting surface is equal to or less than the upper limit, it is considered that the fibers can be densely deposited and the water pressure resistance is improved. In the melt-blowing method, the molten fibers can be cooled and deposited to prevent coalescence of the molten fibers and improve the water pressure resistance. Therefore, it is preferable that the fibers are cooled when the fibers are deposited, and the distance from the nozzle to the collection surface is preferably 50 mm or more, preferably 50 mm or more, more preferably 80 mm or more, and still more preferably 100 mm or more.
　本発明に係るメルトブロー不織布の製造方法は、紡糸工程後、繊維が捕集面に堆積される堆積工程の前に、繊維を加熱する加熱工程を備えることが好ましい。加熱工程において、繊維に風などの外乱は与えずに熱だけを与えることが好ましい観点から、熱風ではなくＩＲヒーターを用いることが好ましい。また、繊維を加熱する位置は、ノズルから吐出した繊維が紡糸空間で冷えて固まることを防ぐ観点から、ノズルから下方に１００ｍｍ以上であることが好ましく、また、２００ｍｍ以下の位置であることが好ましい。このように、特開２０１５－５９２９４号公報や国際公開第２０１２／０１４５０１号に記載のように紡糸直後の繊維に熱を加えるのではなく、紡糸空間を加熱することが好ましい。さらに、繊維を加熱する位置は、紡糸線に対して垂直な方向に８０ｍｍ以上であることが好ましく、１００ｍｍ以上であることがより好ましく、また、２００ｍｍ以下であることが好ましく、１８０ｍｍ以下の位置であることがより好ましい。 The method for producing a melt-blown nonwoven fabric according to the present invention preferably includes a heating step of heating the fibers after the spinning step and prior to the deposition step in which the fibers are deposited on the collecting surface. In the heating step, it is preferable to use an IR heater instead of hot air from the viewpoint that it is preferable to apply heat only to the fibers without giving disturbance such as wind. Further, the position to heat the fibers is preferably 100 mm or more below the nozzle from the viewpoint of preventing the fibers discharged from the nozzle from cooling and solidifying in the spinning space, and preferably 200 mm or less . As described above, it is preferable to heat the spinning space instead of applying heat to the fibers immediately after spinning as described in JP-A-2015-59294 and WO 2012/014501. Furthermore, the position to heat the fiber is preferably 80 mm or more, more preferably 100 mm or more, and preferably 200 mm or less, preferably 180 mm or less in the direction perpendicular to the spinning line. It is more preferable that
　以上のように、本発明に係るメルトブロー不織布の製造方法は、紡糸工程における気流の温度を２６０℃以下とし、繊維を構成する熱可塑性樹脂組成物の融解熱量を５ｍＪ／ｍｇより大きく９４ｍＪ／ｍｇ未満とするため、ＣＤ方向の繊維の直進率が３５％以上であるメルトブロー不織布を得ることができる。 As described above, in the method for producing a melt-blown nonwoven fabric according to the present invention, the temperature of air flow in the spinning step is 260 ° C. or less, and the heat of fusion of the thermoplastic resin composition constituting the fiber is more than 5 mJ / mg and less than 94 mJ / mg Because of this, it is possible to obtain a meltblown nonwoven fabric in which the straightness of the fibers in the CD direction is 35% or more.
　次に、本発明の実施例について説明するが、これにより本発明が限定されるものではない。 Next, examples of the present invention will be described, but the present invention is not limited thereby.
［熱可塑性樹脂組成物］
　実施例１～１１及び比較例１～４において、熱可塑性樹脂組成物の原料として使用した樹脂は以下の通りである。
　樹脂１：ポリプロピレン（Ｌｙｏｎｄｅｌｌｂａｓｅｌｌ社製　Ｍｏｐｌｅｎ（登録商標）　ＨＰ４６１Ｙ）、融解熱量９８ｍＪ／ｍｇ、ＭＦＲ１３００ｇ／１０分、融点１６０℃である。
　樹脂２：低結晶性ポリプロピレン（出光興産株式会社製　Ｌ－ＭＯＤＵ（登録商標）　Ｓ４００）、融解熱量０．３ｍＪ／ｍｇ、ＭＦＲ２６００ｇ／１０分、Ｍｗ＝４５０００、Ｍｗ／Ｍｎ＝２、低立体規則性ポリプロピレンである。
　樹脂３：ポリプロピレン系エラストマー（住友化学株式会社製　タフセレン（登録商標）Ｈ５００２）、融解熱量６ｍＪ／ｍｇ、ＭＦＲ１０ｇ／１０分、融点１３５℃、Ｍｗ＝２３００００、Ｍｗ／Ｍｎ＝１．８、非晶質プロピレン－（１－ブテン）共重合体である。 [Thermoplastic resin composition]
Resins used as raw materials of the thermoplastic resin composition in Examples 1 to 11 and Comparative Examples 1 to 4 are as follows.
Resin 1: Polypropylene (Moplen (registered trademark) HP461Y manufactured by Lyondellbasell), heat of fusion 98 mJ / mg, MFR 1300 g / 10 min, melting point 160 ° C.
Resin 2: Low crystalline polypropylene (L-MODU (registered trademark) S400 manufactured by Idemitsu Kosan Co., Ltd.), heat of fusion 0.3 mJ / mg, MFR 2600 g / 10 min, Mw = 45000, Mw / Mn = 2, low stereoregularity It is polypropylene.
Resin 3: Polypropylene-based elastomer (Tough selenium (registered trademark) H5002 manufactured by Sumitomo Chemical Co., Ltd.), heat of fusion 6 mJ / mg, MFR 10 g / 10 min, melting point 135 ° C., Mw = 230,000, Mw / Mn = 1.8, amorphous Propylene- (1-butene) copolymer.
　また、比較例５、６において用いたメルトブロー不織布はそれぞれ以下の通りである。
　不織布１：クラレクラフレックス株式会社製　メルトブロー不織布（ＰＣ０００９）
　不織布２：タピルス株式会社製　メルトブロー不織布（Ｐ０１０ＳＷ－００Ｘ） Moreover, the melt-blown nonwoven fabric used in Comparative Examples 5 and 6 is as follows.
Non-woven fabric 1: Melt-blown non-woven fabric (PC 0009) manufactured by Kurare Kura Flex Co., Ltd.
Non-woven fabric 2: Made by Tapyrus Co., Ltd. Melt-blown non-woven fabric (P010SW-00X)
［評価］
　次に、実施例及び比較例に係るメルトブロー不織布の各種物性の測定方法を以下に示す。各種物性の測定結果は表２に示した。 [Evaluation]
Next, methods of measuring various physical properties of the meltblown nonwoven fabric according to Examples and Comparative Examples will be shown below. The measurement results of various physical properties are shown in Table 2.
（１）熱可塑性樹脂組成物の融解熱量
　熱可塑性樹脂組成物の融解熱量は、示差走査熱量測定（ＤＳＣ）にて測定した。３０℃から２０℃／分で昇温しながらＤＳＣ曲線を得て、１００～２００℃に現れた吸熱ピークにおける熱量を融解熱量とした。 (1) Heat of Melting of Thermoplastic Resin Composition The heat of fusion of the thermoplastic resin composition was measured by differential scanning calorimetry (DSC). The DSC curve was obtained while raising the temperature from 30 ° C. to 20 ° C./min, and the heat quantity at the endothermic peak appearing at 100 to 200 ° C. was defined as the heat of fusion.
（２）坪量
　メルトブロー不織布の坪量は、メルトブロー不織布の中央部より５０ｍｍ四方の正方形の測定片を３枚切り出し、その測定片の質量（ｇ）を測定し、これを測定片の面積（ｍ2）で除し、３枚の相加平均値を坪量とした。 (2) Basis Weight The basis weight of the melt-blown nonwoven fabric is obtained by cutting out three square measurement pieces 50 mm square from the central portion of the melt-blown nonwoven fabric, measuring the mass (g) of the measurement pieces, and measuring the area (m) of the measurement pieces 2 ) Divided by 3 and made the arithmetic average value of 3 sheets the basis weight.
（３）充填率
　メルトブロー不織布の充填率は、下記式（２）にて算出することができる。メルトブロー不織布の厚みは、オムロン株式会社製レーザー変位計を用いて、４ｋＰａの圧力が掛かるように荷重を加えた状態で測定した。厚みの測定はそれぞれ５回行い、平均値を算出してメルトブロー不織布の厚みとした。なお、繊維密度はＪＩＳ　Ｋ　７１１２記載方法、具体的にはピクノメーター法により測定した。
Figure JPOXMLDOC01-appb-M000004
 (3) Filling rate The filling rate of the meltblown non-woven fabric can be calculated by the following equation (2). The thickness of the melt-blown non-woven fabric was measured using a laser displacement meter made by OMRON Corporation in a state where a load was applied so that a pressure of 4 kPa was applied. The thickness was measured five times each, and the average value was calculated to determine the thickness of the meltblown nonwoven fabric. The fiber density was measured by the method described in JIS K 7112, specifically, the pycnometer method.
Figure JPOXMLDOC01-appb-M000004
（４）地合い指数
　メルトブロー不織布の地合い指数は、野村商事株式会社製の地合い測定機（ＦＭＴ－ＭＩＩＩ）を用いて算出した。具体的には、メルトブロー不織布のサンプルを試料台の上に置き、ＣＣＤカメラの高さを２６ｃｍ、有効サイズを１０ｃｍ×１０ｃｍ、移動平均・画素を１として、サンプルの片面側から光を照射した際の透過像をＣＣＤカメラで撮影する。有効サイズ１０ｃｍ×１０ｃｍを３２０×２３０画素に分解し、それぞれの画素が受ける光の強さを測定し、画素それぞれに対する透過率Ｔを下記の式（３）で算出した。
Figure JPOXMLDOC01-appb-M000005
 　　　　　　　　　　　　　　　　　 
　ただし、ＶTは点灯時（サンプルあり）の透過光量、ＶRは消灯時（サンプルあり）の透過光量であり、Ｖ100は点灯時（サンプルなし）の透過光量、Ｖ0は消灯時（サンプルなし）の透過光量である。
　得られた透過率Ｔから、下記式（４）により吸光度Ｅを算出した。
Figure JPOXMLDOC01-appb-M000006
　得られた吸光度Ｅから、下記式（５）により地合い指数を算出した。
Figure JPOXMLDOC01-appb-M000007
  
　測定は３枚の試験片について行い、その平均値をサンプルの地合い指数とした。
　なお、サンプルのサイズが小さく、有効サイズとして１０ｃｍ×１０ｃｍの大きさが得られない場合は、該サンプルを試験台中央に置き、有効サイズを該サンプルの大きさ未満且つできるだけ広い面積となるように適宜設定して測定を行うことで、そのサンプルの地合い指数を求めることができる。 (4) Formation Index The formation index of the meltblown non-woven fabric was calculated using a formation measuring machine (FMT-MIII) manufactured by Nomura Shoji Co., Ltd. Specifically, when a sample of melt-blown non-woven fabric is placed on a sample table, the height of the CCD camera is 26 cm, the effective size is 10 cm × 10 cm, and the moving average · pixel is 1, light is irradiated from one side of the sample Take a transmission image of the image with a CCD camera. The effective size of 10 cm × 10 cm was decomposed into 320 × 230 pixels, the light intensity received by each pixel was measured, and the transmittance T for each pixel was calculated by the following equation (3).
Figure JPOXMLDOC01-appb-M000005
However, V T is the transmitted light amount when lit (with sample), V R is the transmitted light amount when unlit (with sample), V 100 is the transmitted light amount when lit (without sample), and V 0 is not lit (sample None) transmitted light amount.
From the obtained transmittance T, the absorbance E was calculated by the following equation (4).
Figure JPOXMLDOC01-appb-M000006
From the obtained absorbance E, the formation index was calculated by the following formula (5).
Figure JPOXMLDOC01-appb-M000007
The measurement was performed on three test pieces, and the average value was taken as the sample formation index.
If the size of the sample is small and the size of 10 cm × 10 cm can not be obtained as the effective size, place the sample at the center of the test stand and make the effective size smaller than the size of the sample and as wide as possible. By setting appropriately and performing measurement, the formation index of the sample can be determined.
（５）平均繊維径
　平均繊維径の測定のために、まず、メルトブロー不織布からランダムに小片サンプルを５枚採取した。次に、日本電子株式会社製の卓上走査電子顕微鏡（ＪＣＭ－６０００Ｐｌｕｓ）を用い、視野に２０～６０本の繊維が映るように拡大したＳＥＭ写真を撮影した。視野内の全ての繊維について、それぞれ１回ずつ繊維径を測定して平均値を求め、当該平均値の１０ｎｍの位を四捨五入した値を小片サンプルの繊維径とした。５枚の小片サンプルについて同様に繊維径を測定し、５枚の平均値をメルトブロー不織布の平均繊維径とした。 (5) Average fiber diameter For measurement of the average fiber diameter, first, five small-piece samples were randomly taken from the melt-blown nonwoven fabric. Next, using a tabletop scanning electron microscope (JCM-6000 Plus) manufactured by JEOL Ltd., an SEM photograph was taken, in which 20 to 60 fibers were visible in the field of view. The fiber diameter was measured once for each of all the fibers in the field of view to obtain an average value, and the value obtained by rounding off the 10 nm of the average value was taken as the fiber diameter of the small sample. The fiber diameter was similarly measured about five small pieces of samples, and the average value of five was made into the average fiber diameter of the melt-blown nonwoven fabric.
（６）繊維の直進率
　実施例及び比較例に係るメルトブロー不織布について、第１方向と第２方向における繊維の直進率を、上述の手段に従って算出した。ここで、実施例及び比較例の不織布はＭＤ方向及びＣＤ方向が既知のため、ＭＤ方向を第１方向、ＣＤ方向を第２方向とした。 (6) Straightness of Straightening of Fiber With respect to the meltblown nonwoven fabric according to the example and the comparative example, the straightness of straightening of the fiber in the first direction and the second direction was calculated according to the above-mentioned means. Here, since the nonwoven fabric of an Example and a comparative example has known MD direction and CD direction, MD direction was made into the 1st direction and CD direction was made into the 2nd direction.
（７）耐水圧
　耐水圧は、ＪＩＳ　Ｌ１０９２－１９９８の耐水度試験（静水圧法）Ａ法（低水圧法）に準拠して測定した。耐水度試験の際、試験片の上にナイロンメッシュシート（ポアサイズ：１３３μｍ、厚み：１２１μｍ、倉敷紡績株式会社製、ＤＯ－ＭＬ－２０）を重ねて測定を行った。なお、試験片の大きさが規定に満たない場合は、採取できる面積の試験片に水が当たるよう測定面積を縮小した装置を組み、同様の方法で耐水圧を測定することができる。
　測定は１０枚の試験片について行い、その平均値を算出して、実施例及び比較例に係るメルトブロー不織布の耐水圧とした。 (7) Water Resistance The water resistance was measured in accordance with the water resistance test (hydrostatic pressure method) A (low water pressure method) of JIS L1092-1998. At the time of the water resistance test, measurement was performed by overlapping a nylon mesh sheet (pore size: 133 μm, thickness: 121 μm, manufactured by Kurashiki Spinning Co., Ltd., DO-ML-20) on the test piece. In addition, when the size of a test piece does not satisfy a regulation, the apparatus which reduced the measurement area so that water may contact the test piece of the area which can be extract | collected can be built, and water pressure resistance can be measured by the same method.
The measurement was performed on ten test pieces, and the average value was calculated to determine the water pressure resistance of the melt-blown nonwoven fabric according to the example and the comparative example.
（８）変形後耐水圧
　まず、実施例及び比較例に係るメルトブロー不織布の製造時のＣＤ方向を長さ方向、ＭＤ方向を幅方向とし、長さ１３０ｍｍ以上×幅１５０ｍｍの大きさに切り出した。次に、長さ方向のチャック間の距離が１３０ｍｍになるようにチャック（株式会社島津製作所製引張試験器ＡＧ－ＩＳ）で固定した。次に、長さ方向のチャック間の距離が１５０ｍｍになるようにメルトブロー不織布を延伸して（引張速度１ｃｍ／５秒）、５秒間保持し、メルトブロー不織布をＣＤ方向に変形させた。その後チャックを解除し、変形したメルトブロー不織布の中央部に対し、上記（７）の耐水圧の測定と同様にして、変形後耐水圧を測定した。 (8) Water pressure resistance after deformation First, with the CD direction at the time of production of the melt-blown nonwoven fabric according to the example and the comparative example as the length direction and the MD direction as the width direction, it was cut into a size of at least 130 mm long × 150 mm wide. Next, the chucks were fixed by a chuck (tensile tester AG-IS manufactured by Shimadzu Corporation) so that the distance between the chucks in the lengthwise direction was 130 mm. Next, the meltblown non-woven fabric was stretched (tension speed 1 cm / 5 sec) so that the distance between chucks in the longitudinal direction was 150 mm, held for 5 seconds, and the meltblown non-woven fabric was deformed in the CD direction. Thereafter, the chuck was released, and the water pressure resistance after deformation was measured for the central part of the deformed melt-blown nonwoven fabric in the same manner as the measurement of water pressure resistance described in (7) above.
（９）耐水圧保持率
　耐水圧保持率は、下記式（６）により求めた。
Figure JPOXMLDOC01-appb-M000008
 (9) Water pressure resistance retention rate The water pressure resistance retention rate was determined by the following equation (6).
Figure JPOXMLDOC01-appb-M000008
［実施例１］
　樹脂１及び樹脂２の配合比が樹脂１／樹脂２＝９７／３となるように混合し、熱可塑性樹脂組成物を調製した。該熱可塑性樹脂組成物を用いて、実施例１に係るメルトブロー不織布を製造した。
　実施例１に係るメルトブロー不織布の製造条件は、下記の通りとした。製造条件を表１に示す。
　樹脂温度（ノズルから吐出させる際の温度）：２７０℃
　単孔吐出量：０．２０ｇ／ｍｉｎ／ｈｏｌｅ
　熱風流量：３００Ｎｍ3
　熱風吹き出し幅４００ｍｍ
　熱風温度（紡糸工程における気流の温度）：２００℃
　ノズル径：０．１５ｍｍ、ノズル長さ：３ｍｍ、ノズルピッチ：０．８５ｍｍ
　ノズルから捕集面までの距離：３００ｍｍ
　また、上記（１）～（９）の方法により、実施例１に係るメルトブロー不織布の各種物性を測定し、結果を表２に示した。 Example 1
The thermoplastic resin composition was prepared by mixing the resin 1 and the resin 2 so that the compounding ratio of the resin 1 and the resin 2 was resin 1 / resin 2 = 97/3. A melt-blown nonwoven fabric according to Example 1 was manufactured using the thermoplastic resin composition.
The production conditions of the meltblown nonwoven fabric according to Example 1 were as follows. The manufacturing conditions are shown in Table 1.
Resin temperature (temperature when discharging from the nozzle): 270 ° C
Single-hole discharge amount: 0.20 g / min / hole
Hot air flow: 300 Nm 3
Hot air blowout width 400mm
Hot air temperature (temperature of air flow in spinning process): 200 ° C.
Nozzle diameter: 0.15 mm, nozzle length: 3 mm, nozzle pitch: 0.85 mm
Distance from nozzle to collection surface: 300 mm
Further, various physical properties of the meltblown nonwoven fabric according to Example 1 were measured by the methods (1) to (9) above, and the results are shown in Table 2.
［実施例２～１１、比較例１～４］
　樹脂の種類や配合比、製造条件を表１に示すように変更したこと以外は実施例１と同様にして、実施例２～１１及び比較例１～４に係るメルトブロー不織布を作成した。なお、表１に記載していない製造条件は、実施例１と同様である。また、実施例１と同様にして、実施例２～１１及び比較例１～４に係るメルトブロー不織布の各種物性を測定し、結果を表２に示した。 [Examples 2 to 11, Comparative Examples 1 to 4]
Melt-blown non-woven fabrics according to Examples 2 to 11 and Comparative Examples 1 to 4 were produced in the same manner as in Example 1 except that the resin type, compounding ratio and production conditions were changed as shown in Table 1. The manufacturing conditions not described in Table 1 are the same as in Example 1. Further, in the same manner as in Example 1, various physical properties of melt-blown nonwoven fabrics according to Examples 2 to 11 and Comparative Examples 1 to 4 were measured, and the results are shown in Table 2.
［実施例１２］
　樹脂１を用いて、ノズルから１５０ｍｍ下、さらに紡糸線に対して垂直に１２０ｍｍ離れる位置にＨｅｒａｅｕｓ社製短波長赤外線ヒーター（型番ＩＲＭＡ９００／１６０）の中央が位置するように設置し、出力１００％（総出力９０００Ｗ）で加熱を行った。その他の製造条件は実施例１と同様にして、実施例１２に係るメルトブロー不織布を作製した。また、実施例１と同様にして、得られたメルトブロー不織布の各種物性を測定し、結果を表２に示した。 [Example 12]
The center of the short wavelength infrared heater (model number IRMA 900/160) manufactured by Heraeus is located at a position of 150 mm below the nozzle and 120 mm away from the nozzle using Resin 1. The output is 100%. Heating was performed at a total output of 9000 W). The other manufacturing conditions were the same as in Example 1 to produce a meltblown nonwoven fabric according to Example 12. Further, in the same manner as Example 1, various physical properties of the obtained meltblown nonwoven fabric were measured, and the results are shown in Table 2.
［比較例５及び６］
　比較例５及び６に係るメルトブロー不織布の各種物性を実施例１と同様に測定し、結果を表２に示した。 [Comparative Examples 5 and 6]
Various physical properties of the melt-blown nonwoven fabric according to Comparative Examples 5 and 6 were measured in the same manner as Example 1, and the results are shown in Table 2.
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000010
Figure JPOXMLDOC01-appb-T000010
　表２に示すように、実施例１～１２に係るメルトブロー不織布は、平均繊維径が４μｍ以下であり、且つ繊維の直進率が最も高い第１方向及び該第１方向に直交する第２方向の繊維の直進率が３５％以上であるため、又は、平均繊維径が４μｍ以下であり、且つメルトブロー不織布の平面における第２方向における繊維の直進率に対する第１方向における繊維の直進率の比が２．５以下であるため、耐水圧保持率が高く、変形による耐水圧の低下が抑制されたことがわかる。 As shown in Table 2, the meltblown nonwoven fabrics according to Examples 1 to 12 have a mean fiber diameter of 4 μm or less, and a first direction in which the rectilinear rate of fibers is the highest and a second direction orthogonal to the first direction. Since the straightness of the fiber is 35% or more, or the average fiber diameter is 4 μm or less, the ratio of the straightness of the fiber in the first direction to the straightness of the fiber in the second direction in the plane of the meltblown nonwoven fabric is 2 Since it is less than or equal to .5, it can be seen that the water pressure resistance is high, and the decrease in water pressure resistance due to deformation is suppressed.

Claims (36)

  1. 　平均繊維径が０．１μｍ以上４μｍ以下のメルトブロー不織布であって、
    　前記メルトブロー不織布の平面に沿い、且つ繊維の直進率が最も高い第１方向及び前記第１方向に直交する第２方向を有し、下記（Ｉ），（II）及び（III）から選ばれる１又は複数の条件を満たすメルトブロー不織布。
    　（Ｉ）　前記第１方向及び前記第２方向における繊維の直進率がいずれも３５％以上である。
    　（II）　前記第２方向における繊維の直進率に対する前記第１方向における繊維の直進率の比（前記第１方向における繊維の直進率／前記第２方向における繊維の直進率）が１以上２．５以下である。
    　（III）　前記メルトブロー不織布の耐水圧が１００ｍｍＨ2Ｏ以上１００００ｍｍＨ2Ｏ以下であり、前記第２方向に前記メルトブロー不織布を変形させた場合の耐水圧保持率が８５％以上である。     A melt-blown nonwoven fabric having an average fiber diameter of 0.1 μm to 4 μm,
    It has a first direction along the plane of the meltblown non-woven fabric and the highest straightness of fibers and a second direction orthogonal to the first direction, and is selected from the following (I), (II) and (III) Or the melt blow nonwoven fabric which meets a plurality of conditions.
    (I) The straightness of fibers in the first direction and the second direction is 35% or more.
    (II) The ratio of the straightness of fibers in the first direction to the straightness of fibers in the second direction (the straightness of fibers in the first direction / the straightness of fibers in the second direction) is 1 or more. 5 or less.
    (III) The water pressure resistance of the melt-blown nonwoven fabric is 100 mm H 2 O or more and 10000 mm H 2 O or less, and the water pressure resistance retention when the melt-blown nonwoven fabric is deformed in the second direction is 85% or more.
  2. 　平均繊維径が０．１μｍ以上４μｍ以下のメルトブロー不織布であって、
    　前記メルトブロー不織布の平面に沿い、且つ繊維の直進率が最も高い第１方向及び前記第１方向に直交する第２方向における繊維の直進率がいずれも３５％以上であるメルトブロー不織布。     A melt-blown nonwoven fabric having an average fiber diameter of 0.1 μm to 4 μm,
    The meltblown nonwoven fabric according to any one of the first and second directions, in which the straightness of the fibers is the highest and the second direction orthogonal to the first direction is 35% or more.
  3. 　前記第２方向における繊維の直進率に対する前記第１方向における繊維の直進率の比（前記第１方向における繊維の直進率／前記第２方向における繊維の直進率）が１以上２．５以下である請求項１又は２記載のメルトブロー不織布。 The ratio of the straightness of fibers in the first direction to the straightness of fibers in the second direction (the straightness of fibers in the first direction / the straightness of fibers in the second direction) is 1 or more and 2.5 or less The melt-blown nonwoven fabric according to claim 1 or 2.
  4. 　平均繊維径が０．１μｍ以上４μｍ以下のメルトブロー不織布であって、
    　前記メルトブロー不織布の平面に沿い、且つ繊維の直進率が最も高い方向を第１方向、前記第１方向に直交する方向を第２方向とし、前記第２方向における繊維の直進率に対する前記第１方向における繊維の直進率の比（前記第１方向における繊維の直進率／前記第２方向における繊維の直進率）が１以上２．５以下であるメルトブロー不織布。     A melt-blown nonwoven fabric having an average fiber diameter of 0.1 μm to 4 μm,
    The direction in which the straightness of fibers is highest along the plane of the meltblown nonwoven fabric is referred to as a first direction, and the direction orthogonal to the first direction is referred to as a second direction. The first direction with respect to the straightness of fibers in the second direction The melt-blown nonwoven fabric, wherein the ratio of the straightness of fibers in (the straightness of fibers in the first direction / the straightness of fibers in the second direction) is 1 or more and 2.5 or less.
  5. 　前記第２方向における繊維の直進率に対する前記第１方向における繊維の直進率の比（前記第１方向における繊維の直進率／前記第２方向における繊維の直進率）が１以上１．９以下である請求項１乃至４のいずれか１項記載のメルトブロー不織布。 The ratio of the straightness of fibers in the first direction to the straightness of fibers in the second direction (the straightness of fibers in the first direction / the straightness of fibers in the second direction) is 1 or more and 1.9 or less The melt-blown nonwoven fabric according to any one of claims 1 to 4.
  6. 　前記第１方向及び前記第２方向、並びに前記直進率は、下記手順（ａ）～（ｇ）により決定される請求項１１乃至１５のいずれか１項記載のメルトブロー不織布。
    　（ａ）卓上走査電子顕微鏡（ＪＣＭ－６０００Ｐｌｕｓ、日本電子株式会社製）を用い、観察倍率＝３０００／平均繊維径（μｍ）で、メルトブロー不織布の中央部を観察位置としてＳＥＭ画像を取得して、該ＳＥＭ画像の長辺方向を０°とすること、ただし、測定対象の不織布が略長方形の形状である場合には、該不織布の長手方向を０°とし、ＳＥＭ画像の長辺方向が０°に平行となるようにＳＥＭ画像を取得する、
    　（ｂ）視野をθ°回転させてＳＥＭ画像を取得し、さらに視野をθ°ずつ回転して０°～（１８０－θ）°のＸ枚のＳＥＭ画像を取得すること、ここで、枚数Ｘ＝（１８０°／θ°）－１である、
    　（ｃ）上記手順（ａ）の観察位置とは異なる観察位置７点において、上記手順（ａ）及び（ｂ）の操作をそれぞれ行い、Ｘ枚×８点のＳＥＭ画像を取得すること、ただし、８点の観察位置は、メルトブロー不織布の中央部における４０ｍｍ×２０ｍｍの範囲内にあり、それぞれ１０ｍｍ以上離れている、
    　（ｄ）上記手順（ａ）～（ｃ）で得られたＳＥＭ画像のそれぞれについて、０°～（１８０－θ）°の各角度における繊維の直進率を下記式（１）により算出し、小数点以下を四捨五入し、８点の平均値を求めて各角度における直進率とすること、
    　（ｅ）上記手順（ｄ）で算出した各角度の直進率のうち、最も直進率の大きい角度を第１方向とし、該最も大きい値の直進率を第１方向における繊維の直進率とすること、
    　（ｆ）前記第１方向と直交する方向を第２方向とすること、
    　（ｇ）前記８点の観察位置において、ＳＥＭ画像の長辺方向が前記第２方向に平行となるＳＥＭ画像を取得し、それぞれ前記第２方向の繊維の直進率を下記式（１）により算出して８点の平均値を求め、小数点以下を四捨五入すること、
    Figure JPOXMLDOC01-appb-M000001
     
    ここで、N(0)、N(1)、N(2)は、それぞれ以下を表す。
    　　N(0)は、ＳＥＭ画像の長辺方向一端から他端へ連続して延びる繊維の本数
    　　N(1)は、長辺方向一端に交差する繊維の本数
    　　N(2)は、長辺方向他端に交差する繊維の本数     The melt-blown nonwoven fabric according to any one of claims 11 to 15, wherein the first direction, the second direction, and the rectilinear rate are determined by the following procedures (a) to (g).
    (A) Using a tabletop scanning electron microscope (JCM-6000 Plus, manufactured by Nippon Denshi Co., Ltd.), obtain an SEM image with the central part of the meltblown non-woven fabric as the observation position at an observation magnification of 3000 / average fiber diameter (μm) The long side direction of the SEM image is 0 °, provided that the longitudinal direction of the non-woven fabric is 0 ° and the long side direction of the SEM image is 0 ° when the nonwoven fabric to be measured has a substantially rectangular shape. Acquire SEM images parallel to
    (B) Rotate the field of view by θ ° to acquire an SEM image, and further rotate the field of view by θ ° to acquire X SEM images of 0 ° to (180-θ) °, where = (180 ° / θ °) -1,
    (C) performing the operations of the above procedures (a) and (b) at seven observation positions different from the observation position of the above procedure (a) to obtain X pieces of × 8 SEM images; The eight observation positions are within the range of 40 mm × 20 mm in the central part of the meltblown non-woven fabric, and are each separated by 10 mm or more.
    (D) For each of the SEM images obtained in the above procedures (a) to (c), the straightness of fibers at each angle of 0 ° to (180-θ) ° is calculated by the following equation (1), Round off the following, find the average value of 8 points, and let it be the rate of going straight at each angle,
    (E) Of the straight advance rates of each angle calculated in the step (d), the largest straight advance rate is taken as the first direction, and the largest straight advance rate is regarded as the straight advance rate of fibers in the first direction. ,
    (F) setting a direction orthogonal to the first direction as a second direction;
    (G) An SEM image in which the long side direction of the SEM image is parallel to the second direction is acquired at the eight observation positions, and the straightness of fibers in the second direction is calculated by the following equation (1) Calculate the average of 8 points and round off the decimal point,
    Figure JPOXMLDOC01-appb-M000001

    Here, N (0), N (1) and N (2) respectively represent the following.
    N (0) is the number of fibers continuously extending from one end to the other end of the SEM image N (1) is the number of fibers crossing one end in the long side N (2) is the length in the long side Number of fibers crossing the end
  7. 　耐水圧が１００ｍｍＨ2Ｏ以上１００００ｍｍＨ2Ｏ以下である請求項１乃至６のいずれか１項記載のメルトブロー不織布。 Water pressure resistance 100 mm H 2 O or more 10000mmH 2 O or less is claims 1 to 6 set forth in any one meltblown nonwoven fabric.
  8. 　前記第２方向に前記メルトブロー不織布を変形させた場合の耐水圧保持率が８５％以上である請求項２乃至７のいずれか１項記載のメルトブロー不織布。 The melt-blown nonwoven fabric according to any one of claims 2 to 7, wherein the water pressure resistance retention rate when the melt-blown nonwoven fabric is deformed in the second direction is 85% or more.
  9. 　平均繊維径が０．１μｍ以上４μｍ以下のメルトブロー不織布であって、
    　耐水圧が１００ｍｍＨ2Ｏ以上１００００ｍｍＨ2Ｏ以下であり、
    　前記メルトブロー不織布の平面に沿い、且つ繊維の直進率が最も高い第１方向に直交する第２方向に前記メルトブロー不織布を変形させた場合の耐水圧保持率が８５％以上であるメルトブロー不織布。     A melt-blown nonwoven fabric having an average fiber diameter of 0.1 μm to 4 μm,
    Water pressure resistance is 100 mm H 2 O or more and 10000 mm H 2 O or less,
    The melt-blown nonwoven fabric having a water pressure resistance retention of 85% or more when the melt-blown nonwoven fabric is deformed in a second direction orthogonal to a first direction along the flat surface of the melt-blown nonwoven fabric and having the highest straightness of fibers.
  10. 　充填率が３％以上３０％以下である請求項１乃至９のいずれか１項記載のメルトブロー不織布。 The melt-blown nonwoven fabric according to any one of claims 1 to 9, wherein the filling rate is 3% or more and 30% or less.
  11. 　平均繊維径が０．１μｍ以上４μｍ以下のメルトブロー不織布であって、
    　前記メルトブロー不織布の平面に沿い、且つ繊維の直進率が最も高い第１方向及び前記第１方向に直交する第２方向における繊維の直進率がいずれも３５％以上であり、
    　前記第２方向における繊維の直進率に対する前記第１方向における繊維の直進率の比（前記第１方向における繊維の直進率／前記第２方向における繊維の直進率）が１以上２．５以下であり、
    　充填率が３％以上３０％以下であり、
    　前記繊維の融解熱量が５ｍＪ／ｍｇより大きく９４ｍＪ／ｍｇ未満であるメルトブロー不織布。     A melt-blown nonwoven fabric having an average fiber diameter of 0.1 μm to 4 μm,
    The straightness of the fibers in the first direction along which the meltblown nonwoven fabric has the highest straightness of the fibers and in the second direction orthogonal to the first direction is 35% or more.
    The ratio of the straightness of fibers in the first direction to the straightness of fibers in the second direction (the straightness of fibers in the first direction / the straightness of fibers in the second direction) is 1 or more and 2.5 or less Yes,
    The filling rate is 3% or more and 30% or less,
    The melt-blown nonwoven fabric wherein the heat of fusion of the fibers is greater than 5 mJ / mg and less than 94 mJ / mg.
  12. 　前記平均繊維径が０．３μｍ以上２μｍ以下である請求項１乃至１１のいずれか１項記載のメルトブロー不織布。 The melt-blown nonwoven fabric according to any one of claims 1 to 11, wherein the average fiber diameter is 0.3 μm or more and 2 μm or less.
  13. 　充填率が６％以上１５％以下である請求項１乃至１２のいずれか１項記載のメルトブロー不織布。 The melt-blown nonwoven fabric according to any one of claims 1 to 12, wherein the filling rate is 6% or more and 15% or less.
  14. 　地合い指数が３０以上３００以下である請求項１乃至１３のいずれか１項記載のメルトブロー不織布。 The melt-blown nonwoven fabric according to any one of claims 1 to 13, wherein the formation index is 30 or more and 300 or less.
  15. 　地合い指数が３０以上２００以下である請求項１乃至１４のいずれか１項記載のメルトブロー不織布。 The melt-blown nonwoven fabric according to any one of claims 1 to 14, wherein the formation index is 30 or more and 200 or less.
  16. 　前記繊維の融解熱量が５ｍＪ／ｍｇより大きく９４ｍＪ／ｍｇ未満である請求項１乃至１５のいずれか１項記載のメルトブロー不織布。 The melt-blown nonwoven fabric according to any one of claims 1 to 15, wherein the heat of fusion of the fibers is more than 5 mJ / mg and less than 94 mJ / mg.
  17. 　前記繊維の融解熱量が２０ｍＪ／ｍｇ以上８０ｍＪ／ｍｇ以下である請求項１乃至１６のいずれか１項記載のメルトブロー不織布。 The melt-blown nonwoven fabric according to any one of claims 1 to 16, wherein the heat of fusion of the fibers is from 20 mJ / mg to 80 mJ / mg.
  18. 　請求項１乃至１７のいずれか１項記載のメルトブロー不織布を有する防漏シート。 A leakproof sheet having the meltblown nonwoven fabric according to any one of claims 1 to 17.
  19. 　肌対向面側に配置される液透過性の表面シートと、
    　非肌対向面側に配置される液防漏性の裏面シートと、
    　これらシートの間に配置された吸収体と、を備える吸収性物品であって、
    　前記裏面シートは、請求項１８記載の防漏シートである吸収性物品。     A liquid-permeable top sheet disposed on the side facing the skin;
    Liquid-repellent back sheet disposed on the non-skin facing side,
    And an absorbent disposed between the sheets.
    The absorbent article according to claim 18, wherein the back sheet is a leakproof sheet according to claim 18.
  20. 　溶融した熱可塑性樹脂組成物をノズルから吐出し、気流により繊維状とする紡糸工程を含み、
    　平均繊維径が４μｍ以下であるメルトブロー不織布の製造方法であって、
    　前記気流の温度を前記熱可塑性樹脂組成物の融点以上とし、
    　前記熱可塑性樹脂組成物の融解熱量を５ｍＪ／ｍｇより大きく９４ｍＪ／ｍｇ未満とするメルトブロー不織布の製造方法。     Including a spinning step of discharging a molten thermoplastic resin composition from a nozzle and forming it into a fibrous form by air flow;
    A method for producing a meltblown nonwoven fabric having an average fiber diameter of 4 μm or less,
    Making the temperature of the air flow equal to or higher than the melting point of the thermoplastic resin composition,
    The manufacturing method of the melt-blown nonwoven fabric which makes the heat of fusion of the said thermoplastic resin composition more than 5 mJ / mg and less than 94 mJ / mg.
  21. 　前記気流の温度を２６０℃以下とする請求項２０記載のメルトブロー不織布の製造方法。 The method for producing a melt-blown nonwoven fabric according to claim 20, wherein the temperature of the air flow is set to 260 ° C or less.
  22. 　前記気流の温度を２５０℃以下とする請求項２１記載のメルトブロー不織布の製造方法。 The method for producing a melt-blown nonwoven fabric according to claim 21, wherein the temperature of the air flow is 250 ° C or less.
  23. 　前記気流の温度を２４０℃以下とする請求項２２記載のメルトブロー不織布の製造方法。 The method for producing a meltblown nonwoven fabric according to claim 22, wherein the temperature of the air flow is 240 ° C or less.
  24. 　前記熱可塑性樹脂組成物に前記融解熱量の異なる２種以上のポリオレフィンを含有する請求項２０乃至２３のいずれか１項記載のメルトブロー不織布の製造方法。 The method for producing a melt-blown nonwoven fabric according to any one of claims 20 to 23, wherein the thermoplastic resin composition contains two or more types of polyolefins different in the heat of fusion.
  25. 　前記熱可塑性樹脂組成物は、前記融解熱量が９４ｍＪ／ｍｇ以上である第１のポリオレフィンと、前記融解熱量が９４ｍＪ／ｍｇ未満である第２のポリオレフィンとからなるポリオレフィンを含有し、
    　前記第２のポリオレフィンは、ＭＦＲ４００ｇ／１０分以上の低結晶性ポリプロピレン、ＭＦＲ４００ｇ／１０分未満の低結晶性ポリプロピレン、及び、ＭＦＲ４００ｇ／１０分未満のポリプロピレン系エラストマーから選ばれる１又は複数を含む請求項２４記載のメルトブロー不織布の製造方法。     The thermoplastic resin composition contains a polyolefin comprising a first polyolefin having a heat of fusion of 94 mJ / mg or more and a second polyolefin having a heat of fusion of less than 94 mJ / mg,
    The second polyolefin comprises one or more selected from low crystalline polypropylene having MFR of 400 g / 10 min or more, low crystalline polypropylene having MFR of less than 400 g / 10 min, and polypropylene elastomer having MFR of less than 400 g / 10 min. 24. The method for producing a meltblown nonwoven fabric according to 24.
  26. 　前記ポリオレフィンは、α－オレフィンの単独重合体及び２種以上のα－オレフィンの共重合体のいずれか１以上を含む請求項２４又は２５記載のメルトブロー不織布の製造方法。 The method for producing a melt-blown nonwoven fabric according to claim 24 or 25, wherein the polyolefin comprises any one or more of an α-olefin homopolymer and a copolymer of two or more α-olefins.
  27. 　前記α－オレフィンの単独重合体は、高結晶性ポリオレフィン及び低結晶性ポリオレフィンのいずれか１以上を含む請求項２６記載のメルトブロー不織布の製造方法。 The method for producing a melt-blown nonwoven fabric according to claim 26, wherein the α-olefin homopolymer comprises at least one of a high crystalline polyolefin and a low crystalline polyolefin.
  28. 　前記２種以上のα－オレフィンの共重合体は、低結晶性オレフィン系エラストマー及び非晶性オレフィン系エラストマーのいずれか１以上を含む請求項２６に記載のメルトブロー不織布の製造方法。 The method for producing a melt-blown nonwoven fabric according to claim 26, wherein the copolymer of two or more α-olefins comprises any one or more of a low crystalline olefin elastomer and an amorphous olefin elastomer.
  29. 　前記第１のポリオレフィンが高結晶性ポリオレフィンを含み、該高結晶性ポリオレフィンのメルトフローレートが１００ｇ／１０分以上２０００ｇ／１０分以下である請求項２４乃至２８のいずれか１項記載のメルトブロー不織布の製造方法。 The melt-blown nonwoven fabric according to any one of claims 24 to 28, wherein the first polyolefin comprises a high crystalline polyolefin, and the melt flow rate of the high crystalline polyolefin is 100 g / 10 minutes or more and 2000 g / 10 minutes or less. Production method.
  30. 　前記第１のポリオレフィンが高結晶性ポリオレフィンを含み、該高結晶性ポリオレフィンのメルトフローレートが３００ｇ／１０分以上１８００ｇ／１０分以下である請求項２４乃至２９のいずれか１項記載のメルトブロー不織布の製造方法。 The melt-blown nonwoven fabric according to any one of claims 24 to 29, wherein the first polyolefin comprises a high crystalline polyolefin, and the melt flow rate of the high crystalline polyolefin is from 300 g / 10 minutes to 1800 g / 10 minutes. Production method.
  31. 　前記第１のポリオレフィンと前記第２のポリオレフィンとの総量に対する前記第２のポリオレフィンの含有量は、
    　前記第２のポリオレフィンがＭＦＲ４００ｇ／１０分以上の低結晶性ポリプロピレンである場合、５０質量％以上７０質量％以下であり、
    　前記第２のポリオレフィンがＭＦＲ４００ｇ／１０分未満の低結晶性ポリプロピレン又はＭＦＲ４００ｇ／１０分未満のポリプロピレン系エラストマーである場合、１０質量％以上１５質量％以下である請求項３０記載のメルトブロー不織布の製造方法。     The content of the second polyolefin relative to the total amount of the first polyolefin and the second polyolefin is
    When the second polyolefin is a low crystalline polypropylene having a MFR of 400 g / 10 min or more, it is 50% by mass or more and 70% by mass or less,
    The method for producing a melt-blown nonwoven fabric according to claim 30, wherein when the second polyolefin is a low crystalline polypropylene having MFR of less than 400 g / 10 min or a polypropylene elastomer having MFR of less than 400 g / 10 min, the content is 10% by mass to 15% by mass. .
  32. 　前記紡糸工程で得られた繊維を捕集面に堆積する堆積工程をさらに備え、
    　前記ノズルと前記捕集面との距離を４００ｍｍ以下とする請求項２０乃至３１のいずれか１項記載のメルトブロー不織布の製造方法。     The method further comprises a deposition step of depositing the fibers obtained in the spinning step on the collection surface,
    The method for producing a meltblown nonwoven fabric according to any one of claims 20 to 31, wherein the distance between the nozzle and the collection surface is 400 mm or less.
  33. 　前記紡糸工程で得られた繊維を捕集面に堆積する堆積工程をさらに備え、
    　前記ノズルと前記捕集面との距離を５０ｍｍ以上３００ｍｍ以下とする請求項２０乃至２２のいずれか１項記載のメルトブロー不織布の製造方法。     The method further comprises a deposition step of depositing the fibers obtained in the spinning step on the collection surface,
    The method for producing a meltblown nonwoven fabric according to any one of claims 20 to 22, wherein the distance between the nozzle and the collecting surface is 50 mm or more and 300 mm or less.
  34. 　前記紡糸工程で得られた繊維を捕集面に堆積する堆積工程をさらに備え、
    　前記ノズルと前記捕集面との距離を５０ｍｍ以上１５０ｍｍ以下とする請求項２０乃至３３のいずれか１項記載のメルトブロー不織布の製造方法。     The method further comprises a deposition step of depositing the fibers obtained in the spinning step on the collection surface,
    The method for producing a meltblown nonwoven fabric according to any one of claims 20 to 33, wherein the distance between the nozzle and the collecting surface is 50 mm or more and 150 mm or less.
  35. 　前記紡糸工程で得られた繊維を捕集面に堆積する堆積工程をさらに備え、
    　前記紡糸工程で得られた繊維が前記捕集面に堆積される前に、前記紡糸工程で得られた繊維を加熱する加熱工程を有する請求項２０乃至３４のいずれか１項記載のメルトブロー不織布の製造方法。     The method further comprises a deposition step of depositing the fibers obtained in the spinning step on the collection surface,
    The melt-blown nonwoven fabric according to any one of claims 20 to 34, further comprising a heating step of heating the fibers obtained in the spinning step before the fibers obtained in the spinning step are deposited on the collection surface. Production method.
  36. 　請求項２０乃至３５のいずれか１項に記載の製造方法により製造されたメルトブロー不織布。 The melt-blown nonwoven fabric manufactured by the manufacturing method of any one of Claims 20-35.
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