JP4675865B2 - Nonwoven fabric made of split composite fiber - Google Patents

Description

  The present invention relates to a split-type composite long fiber excellent in splitting property made of an olefin polymer suitable for sanitary materials, filters, wipers, battery separators and the like, and a nonwoven fabric made of split-type composite long fiber.

  Nonwoven fabrics made of ultrafine fibers are excellent in flexibility, texture and the like, and are widely used as materials for clothing, disposable diapers, sanitary goods, wiping cloths and the like.

  As one of the methods for obtaining ultrafine fibers, a multi-component polymer is spun into a split-type composite fiber, and the resulting split-type composite fiber is utilized by physical stress, differential shrinkage of resin to chemicals, etc. And the method of dividing | segmenting into many fibers and obtaining an ultrafine fiber is used. In general, polymers used for the split type composite fibers are easily peeled, that is, incompatible polyester and polyolefin, polyester and polyamide, polyamide and polyolefin, and the like.

Splitting composite fibers made of the same kind of polymer are inferior to the combination of polyester and polyolefin, so there are various methods for improving the splitting ability of splitting composite fibers made of a propylene polymer and an ethylene polymer. Proposed. For example, a method in which a polypropylene-based resin and a polyethylene-based resin having different MFR ratios are made into split-type composite fibers having a bent cross section (Patent Document 1; Japanese Patent Laid-Open No. 2000-328348), and a polypropylene-based resin having a molecular weight distribution of at least 5 A method of using a polyethylene-based resin, melt spinning using a split type composite nozzle having a hollow center in the cross section, and drawing into a split type composite fiber by multistage drawing 5 times or more (Patent Document 2; No. 220740) has been proposed.
JP 2000-328348 A JP, 2002-220740, A However, in order to improve splitting properties, a special nozzle is required or multi-stage drawing is required, and the spun composite long fiber is cooled to a long fiber with a fluid while cooling with a cooling fluid. A nonwoven fabric composed of split-type composite continuous fibers having excellent splitting properties has not been obtained by a method of applying tension to make the material finer, that is, a so-called spunbond method.

The present invention has been studied for the purpose of improving the splitting property of split-type composite fibers composed of a propylene-based polymer and an ethylene-based polymer, and as a result, the degree of a ^* axis orientation of the portion composed of the propylene-based polymer is increased. It has been found that the resolvability can be improved.

The present invention relates to a propylene-based polymer part having an a ^* axial orientation degree of at least 0.80, a split-type composite long fiber in which the ethylene-based polymer part is in contact with each other, a non-woven fabric comprising such a split-type composite long fiber, and the non-woven fabric A split fiber nonwoven fabric obtained by splitting is provided.

The present invention also provides a split-type composite long fiber in which a propylene polymer part and an ethylene polymer part having a molecular weight distribution (Q _PP ; weight average molecular weight / number average molecular weight) of at least 10 are in contact with each other; A nonwoven fabric made of fibers and a split fiber nonwoven fabric obtained by dividing the nonwoven fabric are provided.

In the present invention, a propylene polymer and an ethylene polymer having a molecular weight distribution (Q _PP ; weight average molecular weight / number average molecular weight) of at least 10 are discharged from a spinneret having a composite spinning nozzle and spun. The composite long fiber in which the propylene-based polymer part and the ethylene-based polymer part are in contact with each other is cooled by a cooling fluid, and the long fiber is tensioned with a fluid to be thinned, and then collected on a collecting belt. And a method for producing a non-woven fabric composed of split composite long fibers by a so-called spunbond method.

  The split-type long fibers of the present invention are excellent in splitting properties because the propylene-based polymer portion is greatly oriented, and the resulting nonwoven fabric is made of an olefin-based polymer, so that it is low in cost, light weight, water resistance, and flexibility. Excellent in properties.

Propylene Polymer The propylene polymer according to the split composite long fiber of the present invention preferably has a molecular weight distribution (Q _PP ; weight average molecular weight / number average molecular weight) of at least 10. When a propylene polymer having a Q _PP of less than 10 is used, the a ^* axial orientation degree of the propylene polymer is set to at least 0.80 in the spunbond method in which a long fiber is tensioned with a fluid and thinned. It can be difficult.

  The propylene-based polymer may be a propylene homopolymer or a propylene and a small amount of ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, etc. -Examples of copolymers with olefins. Such a propylene polymer is preferably a polymer having a melting point (Tm) of 155 ° C. or higher, more preferably 160 ° C. or higher.

  The melt flow rate (MFR; ASTM D-1238 load; 2160 gf, temperature; 230 ° C.) of the propylene-based polymer is not particularly limited as long as it can be melt-spun, but is usually 1 to 1000 g / 10 minutes, preferably 5 to 5 g. It is in the range of 500 g / 10 min, more preferably 10-100 g / 10 min.

The molecular weight distribution (Q _PP ; weight average molecular weight / number average molecular weight) of the propylene polymer according to the present invention was as follows: 30 mg of sample was completely dissolved in 20 mL of o-dichlorobenzene at 145 ° C. An analysis sample was filtered through a 45 μm sintered filter. Next, 500 μL of an analytical sample having a sample concentration of 30 mg / 20 mL was injected into the 140 ° C. column at a flow rate of 1 mL / min, and the curve fitting was performed by GPC (gel permeation chromatography).

  In the propylene polymer according to the present invention, the antioxidant, weathering stabilizer, light stabilizer, antistatic agent, antifogging agent, antiblocking agent, lubricant, which are usually used within the range not impairing the object of the present invention. Additives such as nucleating agents and pigments or other polymers can be blended as required.

Ethylene polymer The ethylene polymer according to the split composite long fiber of the present invention is an ethylene homopolymer or ethylene and propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, etc. These are high-pressure method low-density polyethylene, linear low-density polyethylene (so-called LLDPE), medium-density polyethylene, and high-density polyethylene, which are known as copolymers with one or more α-olefins.

Among these ethylene polymers, density of 0.950 g / cm ³ or more, more preferably 0.955 g / cm ³ or more and a melting point (Tm) of the 120 ° C. or higher, more preferably above 125 ° C. ethylene polymer, So-called high-density polyethylene can easily make the degree of a-axis orientation 0.70 or more, and can be superior to the splitting property of the resulting split-type composite continuous fiber.

  The melt flow rate (MFR; ASTM D-1238 load; 2160 gf, temperature; 190 ° C.) of the ethylene-based polymer is not particularly limited as long as it can be melt-spun, but is usually 1 to 1000 g / 10 minutes, preferably 5 to 5 g. It is in the range of 500 g / 10 min, more preferably 10-100 g / 10 min.

The molecular weight distribution (Q _PE ; weight average molecular weight / number average molecular weight) of the ethylene polymer according to the present invention is not particularly limited, but is usually in the range of 1.0 to 8.0.

The molecular weight distribution (Q _PE ; weight average molecular weight / number average molecular weight) of the ethylene polymer according to the present invention was as follows: 30 mg of a sample was completely dissolved in 20 mL of o-dichlorobenzene at 145 ° C. An analysis sample was filtered through a 45 μm sintered filter. Next, 500 μL of an analytical sample having a sample concentration of 30 mg / 20 mL was injected into the 140 ° C. column at a flow rate of 1 mL / min, and the curve fitting was performed by GPC (gel permeation chromatography).

  In the ethylene polymer according to the present invention, a generally used antioxidant, weathering stabilizer, light stabilizer, antistatic agent, antifogging agent, antiblocking agent, lubricant, as long as the object of the present invention is not impaired. Additives such as nucleating agents and pigments or other polymers can be blended as required.

Split-type composite long fiber The split-type composite long fiber of the present invention is a composite long fiber that is formed in contact with a propylene-based polymer portion and an ethylene-based polymer portion before being split.

The split-type composite long fiber of the present invention is a split-type composite long fiber having a ^* axial orientation degree of at least 0.80, preferably 0.82 or more, in which a propylene polymer part and an ethylene polymer part are in contact with each other. is there.

  The split-type composite long fiber of the present invention preferably has an a-axis orientation degree of the ethylene polymer of at least 0.70, more preferably 0.75 or more.

The split-type long fiber of the present invention is preferably in the range of 70% to 90% of the a ^* axis orientation contribution ratio of the propylene polymer part.

  In the split continuous fibers of the present invention, the a-axis orientation contribution ratio of the ethylene polymer portion is preferably in the range of 80% to 100%.

Further, the split-type composite long fiber of the present invention has a split-type composite length in which a propylene-based polymer portion and an ethylene-based polymer portion having a molecular weight distribution (Q _PP ; weight average molecular weight / number average molecular weight) of at least 10 are in contact with each other. Fiber.

The split type composite fiber of the present invention preferably has a ratio (Q _PP / Q _PE ) of the molecular weight distribution (Q _PP ) of the propylene polymer part to the molecular weight distribution (Q _PE ) of the ethylene polymer part of at least 1.5. More preferably, it is 1.7 or more.

The split-type composite fiber of the present invention preferably has a propylene polymer part having an a ^* axial orientation degree of at least 0.80 and a molecular weight distribution (Q _PP ; weight average molecular weight / number average molecular weight) of at least 10 and an ethylene system. It is a split-type composite long fiber in which polymer portions are in contact with each other.

  The shape (cross section) of the split-type composite long fiber is not particularly limited as long as the propylene polymer portion and the ethylene polymer portion are in contact with each other, and various types such as [FIG. 1 (a) to FIG. 1 (e)]. It has the shape of

The number of divisions of the propylene polymer part and the ethylene polymer part forming the split-type composite continuous fiber of the present invention is not particularly limited as long as it does not impair the splittability, but usually 4 to 48 splits, preferably 4 It is in the range of ~ 24 divisions. By setting the splitting of the composite fiber in such a range, the fineness of the split fiber obtained by splitting the nonwoven fabric made of the composite fiber is 1.0 × 10 ^{−3 to} 2.0 denier, preferably 1.0 × 10 ^−3. It can be in the range of -1.2 denier.

Nonwoven fabric made of splittable conjugated filaments of the nonwoven fabric present invention comprising a splittable conjugated filaments are made from the splittable conjugated filaments, typically having a basis weight 3~200g / ^{m 2,} preferably from 10 to 150 g / ^{m 2} Is in range. Moreover, the nonwoven fabric of this invention heat-seals a split-type composite long fiber group by methods, such as an embossing roll and ultrasonic fusion, as needed. The area (embossed area ratio) in the case of heat-sealing can be appropriately selected according to the use, but is preferably 5 to 30%.

Split fiber nonwoven fabric The split fiber nonwoven fabric of the present invention is a nonwoven fabric obtained by dividing a propylene polymer portion and an ethylene polymer portion forming a composite fiber by applying stress to the nonwoven fabric composed of the split composite long fibers. The basis weight is usually 3 to 200 g / m ² , preferably 10 to 150 g / m ² .

The fineness after splitting of the split fibers forming the split fiber nonwoven fabric of the present invention is usually in the range of 1.0 × 10 ^{−3 to} 2.0 denier, preferably 1.0 × 10 ^{−3 to} 1.2 denier. is there.

  Examples of the stress applied to the nonwoven fabric composed of split-type composite long fibers include various known methods, for example, a method of applying a liquid such as water at a high pressure, a so-called high-pressure water flow method (water jet method), and a gear drawing machine. Among these, a method using a gear drawing machine is preferable in that a non-woven fabric made of ultrafine fibers can be easily obtained by efficiently dividing a split composite fiber.

  The gear stretching machine uses a pair of gear rolls as shown in FIG. 2, stretches the nonwoven fabric sandwiched between the gear rolls, and shapes wavy irregularities on the nonwoven fabric. Usually, one pair of gear rolls is sufficient, but a plurality of pairs may be used. The formation direction of the gear teeth of the pair of gear rolls may be a direction substantially orthogonal to the rotation axis of the roll, or may be a direction substantially parallel to the rotation axis of the roll. Further, it may be a direction substantially perpendicular to the rotation axis of the roll, or a direction appropriately deviated from a parallel direction to an oblique direction. In the present invention, the gear tooth formation direction means the direction of the ridgeline of the apex portion of each gear tooth.

  When the gear teeth are arranged in a direction substantially perpendicular to the rotation axis of the roll, the nonwoven fabric is stretched in a direction perpendicular to the machine direction (hereinafter referred to as CD), toward the CD of the nonwoven fabric. Wavy irregularities are formed. Further, when the gear teeth are arranged in a direction substantially parallel to the rotation axis of the roll, the nonwoven fabric is stretched in the machine direction (hereinafter referred to as MD), and the wavy unevenness toward the MD of the nonwoven fabric. Is formed. In consideration of workability and the like, it is preferable to use the former method, that is, the gear teeth disposed substantially orthogonal to the roll rotation axis. In this case, the wavy irregularities are shaped so that the convex portions and the concave portions are continuously continuous with the CD of the nonwoven fabric.

  In the present invention, shaping the wavy irregularities means shaping the nonwoven fabric in a so-called bellows shape. Further, the height of the wavy unevenness means the distance between the convex vertex of the wavy unevenness and the apex of the concave portion (valley bottom), and the wavelength of the wavy unevenness means the distance between the convex vertex of the wavy unevenness and the adjacent convexity vertex. .

  The gear teeth of the gear rolls that face each other in a pair are arranged so that the crests and troughs of each tooth mesh. The nonwoven fabric is stretched when passing between a peak portion of one gear roll and a trough portion of the other gear roll forming a meshing pair, and wave-shaped irregularities are formed. The shape of the wavy irregularities formed on the nonwoven fabric is affected by the shape of the teeth of the pair of gear rolls, the interval between the teeth, the degree of meshing, and the like. By adjusting the distance between the peak and valley peak (bottom) of the gear teeth of the gear roll (hereinafter referred to as the gear pitch), the distance between the peak and peak of the next wavy unevenness formed on the nonwoven fabric (hereinafter referred to as the gear peak) The wavelength of the wavy irregularities).

  Specifically, when the gear pitch is large, the wavelength of the wavy unevenness formed on the nonwoven fabric becomes long. Conversely, when the gear pitch is small, the wavelength of the wavy irregularities formed on the nonwoven fabric is shortened. If the gear pitch is too small, the nonwoven fabric is easily broken. On the other hand, if the gear pitch is too large, the stretching distance becomes wide and uniform stretching becomes difficult, and it becomes difficult to form wavy irregularities having a uniform thickness. Considering this point and the flexibility and stretchability of the resulting nonwoven fabric sheet, the gear pitch of the gear roll is preferably about 1 to 50 mm. In that case, the wavelength of the wavy unevenness formed on the nonwoven fabric is shaped to about 2 to 100 mm.

  Also, by adjusting the degree of meshing of the gear rolls facing each other in pairs, the height of the wavy irregularities formed on the nonwoven fabric, that is, the distance between the convex vertices and the concave vertices (valley bottoms) of the wavy irregularities is adjusted. To do. When the meshing degree of the gears of the opposing gear rolls is small, the height of the wavy irregularities formed on the nonwoven fabric is reduced. When the meshing degree of the gears is large, the height of the wavy irregularities formed on the nonwoven fabric is increased. Moreover, when the meshing degree of a gear is too large, a nonwoven fabric will be easy to tear. Considering this viewpoint and the flexibility and stretchability of the resulting nonwoven fabric sheet, the gear meshing degree is preferably 2 to 100 mm. In that case, the height of the wavy unevenness formed on the nonwoven fabric is shaped to about 2 to 100 mm. Usually, it is preferable that the gear tooth depth (distance between the peak of the peak and the peak of the valley) is 2 to 100 mm. By adjusting the gear pitch and the degree of meshing of the gear to the above ranges, the wave-like unevenness formed on the nonwoven fabric has a wavelength of 2 to 100 mm, and the wave-like unevenness has a height of 2 to 100 mm. A nonwoven fabric sheet having irregularities is obtained.

  Other shapes of the gear roll will be described. There is no restriction | limiting in particular in the dimension of the gear roll used by this invention. Usually, those having a roll diameter of about 10 to 500 mm and a width (length in the direction of the rotation axis) of about 25 to 2000 mm are used. The shape of the peak portion of the gear teeth of the gear roll affects the shape of the wavy unevenness of the obtained nonwoven fabric sheet, the breaking of the nonwoven fabric, and the like. The peak portion of the gear teeth serves as a point for supporting the nonwoven fabric when the nonwoven fabric is gear-stretched to shape wavy irregularities. Therefore, if the contact portion with the nonwoven fabric is too narrow, excessive stress is applied to the nonwoven fabric during stretching, causing the nonwoven fabric to break. On the other hand, since the nonwoven fabric part which contacts the peak part of a gear tooth is hardly extended | stretched, about this point, it is preferable that the part which contacts the peak part of a gear tooth is as narrow as possible. Considering this point, the apex angle of the gear tooth crest is preferably about 5 to 53 degrees. More preferably, it is about 5 to 45 degrees. The vertex angle referred to here is an angle formed by a straight line drawn from the peak (peak) of the gear teeth adjacent to the peak of the gear teeth. Moreover, as for R process of the peak part of a gear tooth, a curvature radius is preferable about 0.015-0.55 mm. More preferably, it is about 0.025 to 0.5 mm. Moreover, although the stretched part and the unstretched part are formed in the extending direction in the stretched nonwoven fabric, the length of the unstretched part in the stretched direction is preferably about 0.005 to 0.5 mm.

Production method of split-type composite long fiber and non-woven fabric Non-woven fabric comprising the above-mentioned split-type composite long fiber and split-type composite long fiber of the present invention is a known melt spinning production method using the propylene-based polymer and ethylene-based polymer. However, the spunbond method is preferred in that a non-woven fabric having good productivity and excellent strength due to long fibers can be obtained.

  A spunbond method will be described as an example as a method for producing the split composite fiber nonwoven fabric of the present invention. The propylene-based polymer and the ethylene-based polymer are separately melted with an extruder or the like, and each melt is hollow, radial, or parallel as illustrated in FIGS. 1 (a) to 1 (e). Alternatively, it is discharged from a spinneret having a composite spinning nozzle configured to form a cross-sectional structure in parallel or in an arc shape, and a split type composite long fiber in which a propylene polymer portion and an ethylene polymer portion are in contact with each other is spun. . The spun split-type composite long fibers are cooled by a cooling fluid, and further, tension is applied to the long fibers by drawn air to obtain a predetermined fineness, which is then collected on a collecting belt and deposited to a predetermined thickness. . Next, heat embossing is performed as necessary by heat fusion using a heat embossing roll. In the case of heat fusion with a hot embossing roll, the embossing area ratio of the embossing roll is appropriately determined, but is usually preferably 5 to 30%.

  At this time, the propylene-based polymer part, preferably the propylene-based polymer part and the ethylene-based polymer part are oriented crystallized in the above-mentioned range by appropriately selecting the molding temperature, spinning speed, and cooling air temperature within the range where the spinnability is good. It is necessary to make it.

Method for Producing Split Fiber Nonwoven Fabric The method for producing a split fiber nonwoven fabric according to the present invention comprises splitting a non-woven fabric composed of the split-type composite continuous fiber into a propylene polymer portion and an ethylene polymer portion by the various known methods described above. .

EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.
In addition, the physical-property value in an Example and a comparative example was measured with the following method.

(1) Dividing ratio The obtained divided fiber nonwoven fabric is embedded in an epoxy resin, and then cut with a microtome to obtain a sample piece. When this is observed with an electron microscope (S-3500N scanning electron microscope manufactured by Hitachi, Ltd.) and the number of segments of the divided fiber cross section observed from the obtained cross-sectional image is 1, the division ratio is 100%. When the observed number of segments in the cross section of the split fibers was two or more, the split ratio was calculated by the following formula. This was observed for 50 fibers, and the average value was taken as the split ratio of the split fiber nonwoven fabric.
Dividing ratio [%] = (total number of segments−number of observed segments of divided fiber cross section) / total number of segments × 100
Here, the total number of segments refers to the total number of segments forming the filament cross section of the split composite fiber. For example, in the case of a split type composite fiber having a filament cross section as shown in FIGS.
For example, when a split fiber cross section as shown in FIG. 1 (e) is observed in a filament with a total number of segments of 8 as shown in FIG. 1 (a), the number of segments of the observed split fiber cross section is set to 3, Further, the division ratio is 62.5%.

(2) Fineness The obtained split fiber nonwoven fabric is embedded in an epoxy resin, and then cut with a microtome to obtain a sample piece. Next, the sample was observed with an electron microscope (S-3500N scanning electron microscope manufactured by Hitachi, Ltd.), 30 undivided filaments were selected from the obtained cross-sectional image, and the cross-sectional area was calculated. The fineness of the undivided filament was determined, and the fineness of the divided fiber was calculated by the following formula using the division ratio.
Fineness of split fibers = unsplit filament fineness / (total number of segments x split ratio / 100)

(3) Texture The touch is evaluated by 10 evaluators, and the evaluation results are shown according to the following criteria.
◎: When 10 people out of 10 feel that the touch is good,
○: If there are 9 to 7 people out of 10
Δ: When 6 to 3 out of 10 people feel that the touch is good,
X: When the number of people who feel that the touch is good is 2 or less out of 10 people.

(4) Flexibility (45 ° cantilever method)
In accordance with JIS L1096 (6.19.1 A method paragraph), a test with a width of 20 mm x 150 mm in a temperature-controlled room at a temperature of 20 ± 2 ° C and a humidity of 65 ± 2% as specified in JIS Z8703 (standard state of the test place) Five pieces are taken in each of the flow direction (MD) and the transverse direction (CD), and the short side of the test piece is placed on a smooth horizontal table with a 45 ° slope, with the short side of the test piece aligned with the scale baseline. Next, the test piece is manually slid gently in the direction of the slope, and when the central point of one end of the test piece comes into contact with the slope, the moving length of the other end is read on the scale. Bending / softening (bending / softening) is indicated by the length (mm) of the test piece moved, measured for each of the five front and back sides, and expressed as an average value in each of the flow direction (MD) and the transverse direction (CD).
It is judged that the lower the bending resistance is, the more flexible the nonwoven fabric is. Generally, when the value of the bending resistance is 60 mm or less in both the flow direction (MD) and the transverse direction (CD), it is determined that the flexibility is good. However, since the required flexibility varies depending on the purpose of use, it is not necessarily limited to this value.

(5) Tensile strength In accordance with JIS L1906 (6.12.1 A method), the flow direction in a temperature-controlled room with a temperature of 20 ± 2 ° C and a humidity of 65 ± 2% specified in JIS Z8703 (standard condition of test place) Three non-woven fabric test pieces of 25 cm in (MD) and 2.5 cm in the transverse direction (CD) were collected, and a tensile tester (Instron 5564 manufactured by Instron Japan Company Limited) under the conditions of 200 mm between chucks and a pulling speed of 200 mm / min. A tensile test was conducted using a mold, the tensile load was measured for three test pieces, and the average value of the maximum values was taken as the tensile strength.

(6) Analysis of fiber structure [Evaluation of orientation]
Using a wide-angle X-ray diffractometer (RINT2550, manufactured by Rigaku Corporation, attached device: fiber sample table, X-ray source: CuKα, output: 40 kV 370 mA, detector: scintillation counter), the sample is aligned in the fiber axis direction and fixed to the sample holder. In the azimuth distribution curve (X-ray interference diagram) obtained by measuring the azimuth distribution strength of the crystal plane peak [polypropylene polymer: (110) plane, polyethylene polymer: (200) plane] The degree of orientation in the fiber axis direction (a ^* -axis orientation degree for the propylene polymer part and a-axis orientation degree for the ethylene polymer part) was calculated and evaluated from the half width (α) of the above. In the orientation degree calculated | required by the following formula, when the orientation degree calculated | required by the following formula is less than 0.8, it was judged that orientation was very low and made it non-orientated.
Degree of orientation (F) = (180 ° −α) / 180 °
(Α is the peak half-value width in the azimuth distribution curve)

[Evaluation of orientation]
For the amount of orientation, samples were aligned in the fiber axis direction and fixed to the sample holder, and the azimuth distribution strength of the crystal plane peak [polypropylene polymer: (110) plane, polyethylene polymer: (200) plane] was measured. In the obtained azimuth distribution curve (X-ray interference diagram), 2θ = 0 ° and 360 ° are connected by a straight line to be a base line.

Next, the peaks that contribute to the a-axis or a ^* -axis (peaks near 2θ = 90 °, 270 °) and c-axis (peaks near 2θ = 0 °, 180 °, 360 °) are separated, and the respective areas are separated. From the following equation, the orientation contribution ratio is calculated.
a shaft and a ^★ axial orientation contribution of = (peak area of the a-axis and a ^★ axial contribution) / (a-axis or a peak area of peak area + c-axis contribution axial contribution ^★) × 100 [%]

Example 1
As propylene polymer, MFR: 13 g / 10 min, Q _PP : 11.0 and melting point (Tm); 165 ° C. propylene homopolymer as ethylene polymer, MFR: 13 g / 10 min, Q _PE : 5.7, melting point (Tm): 133 ° C. and density: 0.965 g / cm ³ high-density polyethylene, each melted at 240 ° C. in a separate extruder molding temperature, and cross section as shown in FIG. Using a split type composite fiber spinning base having a total number of segments of 16 in shape, a split type composite long fiber having a weight ratio of propylene homopolymer to high density polyethylene of 50/50 is cooled using a cooling fluid at 25 ° C. While spinning at a yarn speed of 500 m / min and depositing on a collecting belt, this was heated and pressurized with an embossing roll (embossing area ratio 18%, embossing temperature 100 ° C.). With the amount to prepare a nonwoven fabric made of splittable conjugated filaments 50 g / m ^2. In addition, the fiber structure of the obtained split composite long fibers was measured and evaluated. The results are shown in Table 1.
Next, the obtained non-woven fabric was passed through a gear drawing machine (gear pitch: 25 mm, gear depth: 50 mm) shown in FIG. 2 and subjected to a transverse drawing treatment to produce an ultrafine fiber non-woven fabric having a fineness of 0.4 denier. About the obtained nonwoven fabric, the division ratio, the fineness, the bending resistance, and the tensile strength were measured and evaluated. The results are shown in Table 1.

Comparative Example 1
As propylene polymer, MFR: 30 g / 10 min, Q _PP : 6.8 and melting point (Tm); 163 ° C. propylene homopolymer as ethylene polymer, MFR: 13 g / 10 min, Q _PE : 5.7, melting point (Tm): 133 ° C. and density: 0.965 g / cm ³ of high-density polyethylene, each melted at 240 ° C. in a separate extruder, and in a cross-sectional shape as shown in FIG. While using a split type composite fiber spinning base having a total number of segments of 16 while cooling split type composite long fibers having a weight ratio of propylene homopolymer and high density polyethylene of 50/50 using a cooling fluid at 25 ° C. The yarn is spun at a yarn speed of 500 m / min, deposited on a collecting belt, and then heated and pressurized with an embossing roll (embossing area ratio 18%, embossing temperature 100 ° C.), and the basis weight is 50. / A m ² of the split mold nonwoven fabric comprising composite long fibers was prepared. In addition, the fiber structure of the obtained split composite long fibers was measured and evaluated. The results are shown in Table 1.
Next, the obtained non-woven fabric was passed through a gear drawing machine (gear pitch: 25 mm, gear depth: 50 mm) shown in FIG. 2 and subjected to a transverse drawing treatment to produce an ultrafine fiber non-woven fabric having a fineness of 0.9 denier. About the obtained nonwoven fabric, the division ratio, the fineness, the bending resistance, and the tensile strength were measured and evaluated. The results are shown in Table 1.

As is apparent from Table 1, the composite long fiber nonwoven fabric using the propylene polymer and the ethylene polymer of the examples has high orientation in the a-axis direction (the propylene polymer is the a ^* axis) direction. The splitting property can be easily split to 80% or more, the fineness of the resulting split fiber is thin, and the flexibility and texture are extremely excellent.
On the other hand, the composite long fiber nonwoven fabric using the propylene-based polymer and the ethylene polymer of the comparative example was difficult to be divided, the fineness could not be reduced, and the flexibility and texture were inferior.

  The split fiber nonwoven fabric obtained from the split-type composite fiber nonwoven fabric of the present invention is extremely excellent in flexibility and texture, and includes various wiping cloths, surgical nonwoven fabrics, medical gowns, industrial gowns and other clothing nonwoven fabrics, packaging fabrics, and disposables. It can also be used widely for surface materials of sanitary materials such as diapers and napkins, bedding such as bed sheets and pillow covers, carpets and base fabrics for artificial leather.

  Other applications include VTR and compact disc cleaning cloth, disc polishing, filter cloth, general consumer materials such as glass, precious metal, high-quality items, window glass, OA equipment, automobile windows, musical instruments, mirrors, etc. Examples include dirt removal, oil film removal, flooring, and toilet cleaners.

FIG. 1 is a schematic view showing an example of a cross section of a composite long fiber according to the present invention. The five forms (a) to (d) were listed. (E) is an example of the cross-sectional form after a division | segmentation process. In the figure, white and black portions represent polymers to be combined. FIG. 2 is a schematic view of a gear drawing machine used in Examples and Comparative Examples. (A) is a schematic view when a non-woven fabric is processed, (b) is a front view when the non-woven fabric is processed, and (c) shows an enlarged part of the front view.

Claims (9)

a ^★ axis orientation degree of at least 0.80 and a molecular weight distribution; and (Q _PP weight average molecular weight / number average molecular weight) of at least 10 propylene polymer portion of the ethylene heavy a-axis orientation degree of at least 0.70 Split composite long fibers obtained by a spunbond method in which the combined parts are in contact with each other. 2. The split composite according to claim 1 , wherein the ratio (Q _PP / Q _PE ) of the molecular weight distribution (Q _PP ) of the propylene-based polymer part to the molecular weight distribution (Q _PE ) of the ethylene-based polymer part is at least 1.5. Long fiber. The split composite long fiber according to claim 1 , wherein the propylene-based polymer portion is a propylene-based polymer portion having an a ^* axial orientation degree of at least 0.82.   The nonwoven fabric which consists of a split-type composite continuous fiber of any one of Claims 1-3. A split fiber nonwoven fabric obtained by dividing a propylene polymer portion and an ethylene polymer portion of a split composite long fiber by applying stress to the nonwoven fabric according to claim 4 . The split fiber nonwoven fabric according to claim 5 , wherein the stress is applied by a gear drawing machine. A propylene polymer portion spun by discharging a propylene polymer and an ethylene polymer having a molecular weight distribution (Q _PP ; weight average molecular weight / number average molecular weight) of at least 10 from a spinneret having a composite spinning nozzle. The composite long fiber in which the ethylene polymer part and the ethylene polymer part are in contact with each other is cooled by the cooling fluid, and the long fiber is tensioned with the fluid to make it thin, and then collected and deposited on the collecting belt. The manufacturing method of the nonwoven fabric which consists of a split-type composite continuous fiber obtained by the spunbond method. The manufacturing method of the split fiber nonwoven fabric characterized by dividing the propylene-type polymer part and ethylene-type polymer part of a split-type composite long fiber by adding stress to the nonwoven fabric of Claim 7 . The method for producing a split fiber nonwoven fabric according to claim 8 , wherein the stress is applied by a gear drawing machine.

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