JP7035360B2 - Spunbond non-woven fabric - Google Patents

Description

The present invention relates to a spunbonded nonwoven fabric which is composed of composite fibers made of two or more different types of polyolefin resins and has excellent geological uniformity, and is particularly suitable for sanitary material applications.

In general, non-woven fabrics for sanitary materials such as disposable diapers and menstrual napkins are required to have touch, flexibility and high productivity. Polyolefin-based resins, which are low-cost and have excellent texture, are widely used as fibers composed of a single component or a composite component, and composite fibers composed of two or more different types of polyolefin resins, especially polypropylene-based resin, are arranged as core components. However, with regard to the core-sheath composite fiber in which a polyethylene-based resin is arranged as a sheath component, various uses have been studied by utilizing its excellent flexibility.

It is known that reducing the diameter is effective for increasing the flexibility of the core-sheath composite fiber in which polypropylene-based resin is used as the core component and polyethylene-based resin is placed in the sheath component, but the productivity is low. In addition, there is a problem that yarn breakage occurs due to stretching at a high spinning speed in order to increase productivity, and stable production cannot be achieved.

Various proposals have been made as a method for improving the spinnability of such core-sheath composite fibers. For example, the values obtained by dividing the weight average molecular weights of polypropylene, which is the core component of the core-sheath composite fiber, and polyethylene, which is the sheath component, by the number average molecular weight are 2.5 to 4.0 and 1.5 to 4.0. Therefore, it has been proposed to increase the strength of the yarn and improve the spinnability (see Patent Document 1). However, although the spinnability is certainly improved by increasing the strength in this proposal, since polypropylene and polyethylene having a relatively small melt flow rate are used as raw materials, yarn breakage is likely to occur and stable production cannot be performed. There was a problem.

Further, it has been proposed to improve the spinnability by using a linear low-density polyethylene which is a copolymer containing 1 to 10% by mass of octene-1 as a sheath component (see Patent Document 2). .. However, in this proposal, polypropylene and polyethylene having a melt flow rate of 5 to 45 g / 10 minutes are used as raw materials, and there is a problem that the uniformity of the formation is inferior because the spinnability is poor and the fiber diameter cannot be made fine.

Japanese Unexamined Patent Publication No. 11-140766 Special Fair 7-103507 Gazette

Therefore, in view of the above problems, an object of the present invention is to be composed of a composite fiber made of two or more different types of polyolefin resins, which have a small single fiber fiber diameter and excellent spinnability, and have excellent uniformity, particularly. It is an object of the present invention to provide a spunbonded nonwoven fabric suitable for sanitary material applications.

The spunbonded nonwoven fabric of the present invention contains a polypropylene-based resin having a melt flow rate of 155 to 850 g / 10 minutes as a core component, and a polyethylene-based resin having a melt flow rate of 50 to 200 g / 10 minutes as a sheath component. A spunbonded nonwoven fabric composed of a core-sheath type composite fiber in which the center of the core portion composed of the core component and the sheath portion composed of the sheath component are the same in the cross section, and is a single fiber fiber of the composite fiber. The diameter is 6.5 to 14.5 μm, the air permeability CV value of the spunbonded nonwoven fabric is 7% or less, the complex viscosity at 6.28 rad / sec at a temperature of 230 ° C. is 100 Pa · sec or less. It is a spunbonded non-woven fabric characterized by being present.

According to the present invention, although the single fiber has a small diameter, it has excellent spinning stability and high productivity, and is composed of a composite fiber made of two or more different types of polyolefin resins, and has an excellent flexible and smooth surface touch. A spunbonded nonwoven fabric having the above can be obtained. Further, according to the present invention, in addition to the above-mentioned characteristics, since it is excellent in uniformity, it is possible to improve the processing stability of ultrasonic bonding, which is often used especially in the manufacturing process of sanitary materials.

FIG. 1 is a schematic cross-sectional view illustrating a cross section of a composite fiber constituting the spunbonded nonwoven fabric of the present invention. FIG. 2 is a schematic cross-sectional view illustrating a cross section of another composite fiber constituting the spunbonded nonwoven fabric of the present invention. FIG. 3 is a schematic cross-sectional view illustrating a cross section of another composite fiber constituting the spunbonded nonwoven fabric of the present invention.

The spunbonded nonwoven fabric of the present invention contains a polypropylene-based resin having a melt flow rate of 155 to 850 g / 10 minutes as a core component, and a polyethylene-based resin having a melt flow rate of 50 to 200 g / 10 minutes as a sheath component. A spunbonded nonwoven fabric composed of a core-sheath type composite fiber in which the center of the core portion composed of the core component and the sheath portion composed of the sheath component are the same in the cross section, and is a single fiber fiber of the composite fiber. The diameter is 6.5 to 14.5 μm, the air permeability CV value of the spunbonded nonwoven fabric is 7% or less, the complex viscosity at 6.28 rad / sec at a temperature of 230 ° C. is 100 Pa · sec or less. It is a spunbonded non-woven fabric characterized by being present.

As the polyolefin-based resin used in the present invention, a polyolefin having 2 to 10 carbon atoms is preferably used. Specifically, ethylene, propylene, 1-butene, 1-pentene, 1-hexane, 4-methyl-1-pentene, 1-octene, and copolymers of these monomers and other α-olefins can be used. Can be mentioned. These can be used alone or in combination of two or more. Among them, polypropylene-based resin is preferable because it has high strength and excellent dimensional stability during production of sanitary materials. Further, it is preferable to use a polyethylene-based resin because it has high flexibility and excellent texture.

Examples of the polyethylene-based resin used in the present invention include a homopolymer of ethylene or a copolymer of ethylene and various α-olefins.

Examples of the polyethylene-based resin used in the present invention include medium-density, high-density and linear low-density polyethylene (hereinafter, may be referred to as LLDPE) and the like, and are excellent in spinnability. , LLDPE is preferably used.

The polyethylene-based resin used in the present invention may be a mixture of two or more kinds, and may be a branching component different from ethylene, for example, α-such as butene, hexene, 4-methylpentene, heptene, and octene. A polyethylene-based resin obtained by copolymerizing an olefin or a resin composition containing a thermoplastic elastomer or the like can also be used.

The polyethylene-based resin used in the present invention includes antioxidants, weathering stabilizers, light-resistant stabilizers, antistatic agents, antifoaming agents, blocking inhibitors, lubricants, which are usually used, as long as the effects of the present invention are not impaired. Additives such as nucleating agents and pigments, or other polymers can be added as needed.

The melting point of the polyethylene-based resin used in the present invention is preferably 80 to 160 ° C, more preferably 100 to 140 ° C. By setting the melting point to preferably 80 ° C. or higher, more preferably 100 ° C. or higher, it becomes easy to obtain heat resistance that can withstand practical use. Further, by setting the melting point to 160 ° C. or lower, more preferably 140 ° C. or lower, it becomes easy to firmly adhere to the polypropylene resin and it becomes easy to spin without yarn breakage.

The melt flow rate (MFR) of the polyethylene-based resin used in the present invention is 50 to 200 g / 10 minutes . By setting the MFR to 50 to 200 g / 10 minutes , preferably 60 to 180 g / 10 minutes, more preferably 70 to 150 g / 10 minutes, the spinning speed was increased in order to increase the productivity. However, since the viscosity is low, it can easily follow the deformation, and stable spinning becomes possible. Further, by drawing at a high spinning speed, the orientation and crystallization of the fiber can be promoted to obtain a fiber having high mechanical strength.

The MFR of the polyethylene resin is measured by ASTM D-1238 under the conditions of a load of 2160 g and a temperature of 190 ° C.

Further, as the polyolefin-based resin other than the polyethylene-based resin used as the resin of the composite fiber constituting the spunbonded nonwoven fabric of the present invention, a polypropylene-based resin is particularly preferable from the viewpoint of strength .

Examples of the polypropylene-based resin used in the present invention include homopolymers of propylene and copolymers of propylene and various α-olefins.

The polypropylene-based resin used in the present invention may be a mixture of two or more kinds, and may be a branching component different from propylene, such as ethylene, butene, hexene, 4-methylpentene, heptene, and octene. A resin composition containing a polypropylene-based resin copolymerized with α-olefin, a thermoplastic elastomer, or the like can also be used.

The polypropylene-based resin used in the present invention includes antioxidants, weathering stabilizers, light-resistant stabilizers, antistatic agents, antifoaming agents, blocking inhibitors, lubricants, which are usually used, as long as the effects of the present invention are not impaired. Additives such as nucleating agents and pigments, or other polymers can be added as needed.

The melting point of the polypropylene-based resin used in the present invention is preferably 80 to 200 ° C, more preferably 100 to 180 ° C. By setting the melting point to preferably 80 ° C. or higher, more preferably 100 ° C. or higher, it becomes easy to obtain heat resistance that can withstand practical use. Further, by setting the melting point to 200 ° C. or lower, more preferably 180 ° C. or lower, it becomes easier to cool the yarn discharged from the mouthpiece, and it becomes easier to suppress fusion between fibers and perform stable spinning.

The melt flow rate of the polypropylene-based resin of the present invention (hereinafter, may be referred to as MFR) is 155 to 850 g / 10 minutes . By setting the MFR to 150 to 850 g / 10 minutes , preferably 150 to 600 g / 10 minutes, more preferably 150 to 400 g / 10 minutes, even if it is stretched at a high spinning speed in order to increase productivity. Since the viscosity is low, it can easily follow the deformation, and stable spinning becomes possible. Further, by drawing at a high spinning speed, the orientation and crystallization of the fiber can be promoted to obtain a fiber having high mechanical strength.

The polypropylene resin MFR is measured by ASTM D-1238 under the conditions of a load of 2160 g and a temperature of 230 ° C.

It is important that the complex viscosity of the spunbonded nonwoven fabric of the present invention at a temperature of 230 ° C. and 6.28 rad / sec is 100 Pa · sec or less for the same reason as described above. The complex viscosity of the spunbonded non-woven fabric is determined by the type of polyolefin resin such as polyethylene resin or polypropylene resin, and when a plurality of types of resins having different complex viscosities are mixed and used, when a plurality of types of resins are mixed. It can be adjusted by the mass ratio.

The polyethylene-based resin constituting the spunbonded non-woven fabric of the present invention and the composite fiber of the fiber made of different types of polyolefin-based resin preferably have a polyethylene-based resin having a mass ratio of 20 to 50% by mass, and different types of fibers. It is a preferable embodiment that the mass ratio of the polyolefin resin is 50 to 80% by mass. By setting the mass ratio of polyethylene to preferably 20 to 50% by mass, more preferably 25 to 40% by mass, it is possible to obtain a flexible composite fiber having sufficient adhesive strength. Further, by setting the mass ratio of the different types of polyolefin resins to preferably 50 to 80% by mass, more preferably 60 to 75% by mass, it is possible to obtain a composite fiber having strength that can be put into practical use.

It is important that the composite fiber constituting the spunbonded nonwoven fabric of the present invention has a single fiber fiber diameter of 6.5 to 14.5 μm. By setting the diameter of the single fiber to 6.5 to 14.5 μm, preferably 7.5 to 14.5 μm, and more preferably 8.4 to 11.8 μm, the texture of the spunbonded non-woven fabric is uniform. A spunbonded nonwoven fabric having excellent properties can be obtained.

1 to 3 are schematic cross-sectional views illustrating a cross section of a composite fiber constituting the spunbonded nonwoven fabric of the present invention.

1 and 2 are schematic cross-sectional views showing a cross section of a core-sheath type composite fiber. In FIG. 1, the centers of the core portion (a) and the sheath portion (b) are the same, and in FIG. 2, the centers of the core portion (a) and the sheath portion (b) are different.

Specifically, the core-sheath type composite fiber is composed of a core portion (a) and a sheath portion (b), and the core portion (a) is at least a part of a polymer different from the core portion (a) in the cross section of the fiber. A portion that is arranged so as to be surrounded by fibers and extends in the length direction of the fiber. Further, the sheath portion (b) is a portion arranged so as to surround at least a part of the core portion (a) in the cross section of the fiber and extending in the length direction of the fiber. The eccentric core-sheath type composite fiber includes an exposed type in which the side surface of the core portion (a) is exposed and a non-exposed type in which the side surface of the core portion (a) is not exposed .

FIG. 3 is a schematic cross-sectional view showing a cross section of a side-by-side type composite fiber. The side-by-side type composite fiber has a structure in which the first component (c) and the second component (d) are bonded together. The joint surface of these two components may be either a straight line or a curved line, and differs depending on the viscosity characteristics of the two components and the discharge rate ratio. The cross section of the composite fiber may be circular, or may be a modified cross section such as an ellipse.

The basis weight of the spunbonded nonwoven fabric of the present invention is preferably 10 to 100 g / m ² . By setting the basis weight to preferably 10 g / m ² or more, more preferably 13 g / m ² or more, a spunbonded nonwoven fabric having mechanical strength that can be put into practical use can be obtained. On the other hand, when the nonwoven fabric is used for sanitary material applications, it is suitable for sanitary materials by setting the basis weight to preferably 100 g / m ² or less, more preferably 50 g / m ² or less, and further preferably 30 g / m ² or less. A spunbonded nonwoven fabric having moderate flexibility can be obtained.

It is important that the spunbonded nonwoven fabric of the present invention has an air permeability CV value of 7% or less. By setting the air permeability CV value to 7% or less , preferably 5% or less, a highly uniform spunbonded non-woven fabric can be obtained, which is stable and uniform in ultrasonic bonding, which is often used in the manufacturing process of disposable diapers and the like. Adhesion is possible. On the other hand, in the case of a non-woven fabric having a CV value of more than 7%, that is, a non-woven fabric having large unevenness in formation, insufficient adhesion due to unevenness or perforation due to overadhesion may occur. The above CV value can be adjusted by reducing the diameter of the single fiber fiber and increasing the spinning speed.

The spunbonded nonwoven fabric of the present invention preferably has a standard deviation MMD of friction coefficient of 0.0040 to 0.0070. By setting the standard deviation MMD of the friction coefficient to 0.0040 to 0.0070, more preferably 0.0055 to 0.0065, the surface of the non-woven fabric is less rough and the span is excellent in surface touch when used as a sanitary material. A bonded non-woven fabric is obtained.

Next, the method for producing the spunbonded nonwoven fabric of the present invention will be specifically described.

In the spunbond method for producing a spunbonded non-woven fabric, a resin is melted, spun from a spinneret, and then cooled and solidified. This is a manufacturing method that requires a step of heat-bonding after collecting and forming a non-woven fiber web.

As the shape of the spinneret or ejector used, various spinneret or ejector such as a round shape or a rectangle can be adopted. In particular, from the viewpoint that the amount of compressed air used is relatively small and the yarns are less likely to be fused or scratched, it is preferable to use a combination of a rectangular base and a rectangular ejector.

In the present invention, the spinning temperature at the time of melting and spinning a polyethylene-based resin and a different type of polyolefin-based resin is preferably 200 to 270 ° C, more preferably 210 to 260 ° C, and further preferably 220 to 220 ° C. It is 250 ° C. By setting the spinning temperature within the above range, a stable molten state can be obtained and excellent spinning stability can be obtained.

To exemplify a preferable method for producing a composite fiber used in the present invention, a polypropylene-based resin and a polyethylene-based resin are melted and weighed in different extruders to form a composite spinneret, preferably a fiber cross section as shown in FIG. It is supplied to the core-sheath fiber spinneret, which forms

The filaments of the spun long fibers are then cooled, but as a method of cooling the spun yarns, for example, a method of forcibly blowing cold air onto the yarns or an atmospheric temperature around the yarns is used. A method of natural cooling, a method of adjusting the distance between the spinneret and the ejector, and the like can be mentioned, or a method of combining these methods can be adopted. Further, the cooling conditions can be appropriately adjusted and adopted in consideration of the discharge amount per single hole of the spinneret, the spinning temperature, the atmospheric temperature and the like.

Next, the cooled and solidified yarn is pulled and stretched by the compressed air ejected from the ejector.

The spinning speed is preferably 3,500 to 6,500 m / min, more preferably 4,000 to 6,500 m / min, and even more preferably 4,500 to 6,500 m / min. By setting the spinning speed to 3,500 to 6,500 m / min, high productivity can be obtained, and the orientation and crystallization of the fibers can be advanced to obtain high-strength long fibers.

Further, as described above, normally, when the spinning speed is increased, the spinnability deteriorates and the filamentous shape cannot be stably produced. However, in the present invention, a specific range not previously found has been found. By using a polyethylene-based resin having an MFR and a different polyolefin-based resin, it is possible to stably spin the intended composite fiber such as a core-sheath type.

Subsequently, the obtained long fibers are collected on a moving net to form a non-woven fiber web. In the present invention, since the fibers are drawn at a high spinning speed, the fibers emitted from the ejector are collected by the net under the control of a high-speed air flow, and the spunbonded nonwoven fabric with less fiber entanglement and high uniformity. Can be obtained.

Subsequently, the obtained non-woven fiber web is integrated by thermal adhesion to obtain the intended spunbonded non-woven fabric.

As a method of integrating the above-mentioned non-woven fiber webs by heat bonding, a heat embossed roll in which the upper and lower roll surfaces are engraved (uneven portions), a roll having a flat (smooth) surface on one roll and the other on the other. There are various methods of heat bonding using various rolls such as a heat embossed roll consisting of a roll with engraving (unevenness) on the surface of the roll and a thermal calendar roll consisting of a pair of upper and lower flat (smooth) rolls. Be done.

The embossed bonding area ratio at the time of heat bonding is preferably 5 to 30%. By setting the bonding area to preferably 5% or more, more preferably 10% or more, it is possible to obtain strength that can be put into practical use as a spunbonded nonwoven fabric. On the other hand, by setting the adhesive area to preferably 30% or less, more preferably 20% or less, sufficient flexibility can be obtained particularly when used as a spunbonded nonwoven fabric for sanitary materials.

The bonding area referred to here occupies the entire non-woven fabric in the portion where the convex portion of the upper roll and the convex portion of the lower roll overlap and abut on the non-woven fiber web when heat-bonding is performed by a roll having a pair of irregularities. It refers to the ratio. Further, when heat-bonding to a roll having unevenness by a flat roll, it means the ratio of the convex portion of the roll having unevenness to the entire nonwoven fabric of the portion in contact with the non-woven fiber web.

As the shape of the sculpture applied to the thermal embossing roll, a circular shape, an elliptical shape, a square shape, a rectangle, a parallelogram, a rhombus, a regular hexagonal shape, a regular octagonal shape, or the like can be used.

The surface temperature of the heat roll is preferably −20 to −5 ° C. with respect to the melting point of the polyethylene resin used as the sheath component. By setting the surface temperature of the thermal roll to −20 ° C. or higher with respect to the melting point of the polyethylene-based resin, it is possible to appropriately heat-adhere and maintain the non-woven fabric morphology and improve the wear resistance. Further, by setting the surface temperature of the thermal roll to -5 ° C or lower with respect to the melting point of the polyethylene resin, excessive thermal adhesion is suppressed, and sufficient flexibility is obtained especially when used as a spunbonded nonwoven fabric for sanitary materials. Can be obtained.

Further, the linear pressure of the heat embossing roll at the time of heat bonding is preferably 5 to 50 N / cm. By setting the linear pressure of the roll to preferably 5 N / cm or more, more preferably 10 N / cm or more, still more preferably 15 N / cm or more, sufficient heat adhesion is obtained to obtain strength and wear resistance that can be put into practical use as a non-woven fabric. be able to. On the other hand, by setting the linear pressure of the roll to preferably 50 N / cm or less, more preferably 40 N / cm or less, still more preferably 30 N / cm or less, sufficient flexibility is provided especially when used as a non-woven fabric for sanitary materials. Obtainable.

Since the spunbonded nonwoven fabric of the present invention is flexible and has extremely high uniformity, it can be suitably used for sanitary material applications such as disposable disposable diapers and napkins. Among the sanitary materials, it can be particularly preferably used for the back sheet of disposable diapers.

Next, the spunbonded nonwoven fabric of the present invention will be specifically described based on Examples.

(1) Melt flow rate (MFR):
The melt flow rate of the polyethylene resin is measured by ASTM D-1238 under the conditions of a load of 2160 g and a temperature of 190 ° C. The melt flow rate of the polyolefin resin other than the polyethylene resin is also measured by ASTM D-1238 under the conditions of a load of 2160 g and a temperature of 230 ° C.

(2) Complex viscosity (Pa · sec):
Using the capillary leometer RHEOSOL-G3000, the complex viscosity (Pa / sec) of the nonwoven fabric sheet at 20 mm parallel plate, gap 0.5 mm, temperature 230 ° C., strain 34.9%, frequency 0.3 to 63 rad / sec was measured. did.

(2) Single fiber Fiber diameter (μm):
After being towed by an ejector and stretched, 10 small pieces were randomly collected from the non-woven web collected on the net, and a surface photograph of 500 to 1000 times was taken with a microscope, and 10 pieces were taken from each sample. The width of a total of 100 fibers was measured, and the single fiber fiber diameter (μm) was calculated from the average value.

(3) Spinning speed (m / min):
From the above single fiber diameter and the solid density of the resin used, the mass per 10,000 m in length was taken as the single fiber fineness, and the second decimal place was rounded off. From the single fiber fineness (dtex) and the discharge amount of the resin discharged from the single hole of the spinneret set under each condition (hereinafter, abbreviated as the single hole discharge amount) (g / min), based on the following formula. The spinning speed was calculated.
-Spinning speed = (10000 x single hole discharge amount) / single fiber fineness.

(4) Metsuke:
Based on JIS L1913 (2010) 6.2 "Mass per unit area", 3 test pieces of 20 cm x 25 cm were collected per 1 m of sample width, and each mass (g) in the standard state was weighed. The average value was expressed by the mass per 1 m ² (g / m ² ).

(5) Aeration amount CV value (%):
According to the JIS L1913 (2010) Frazier method, 10 fiber sheets cut into 15 cm squares were tested at a test pressure of 1 using the breathability tester FX3300 manufactured by Textest.
It was measured at 25 Pa. The air volume CV value (%) was taken from the percentage of the coefficient of variation of the obtained value.

(6) Standard deviation of friction coefficient MMD:
Using the automated surface tester KES-FB4 AUTO-A manufactured by Kato Tech Co., Ltd., a load of 50 gf / cm ² is applied to the terminal wound with the piano wire in a range of 100 mm x 100 mm of each sample, and 1.0 mm. It was slid at a speed of / sec and the standard deviation MMD of the coefficient of friction was measured.

(7) Melting peak:
The differential scanning calorimeter (DSCQ1000 manufactured by TA Instruments) was used to measure the differential scanning calorimetry under the condition of a heating rate of 10 ° C./min, and the number of endothermic melting peaks was measured.

(Example 1)
A polypropylene homopolymer resin having a melt flow rate (MFR) of 170 g / 10 min and a polyethylene homopolymer resin (LLDPE) having an MFR of 100 g / 10 min were melted by an extruder, and the spinning temperature was 235 ° C. From a rectangular core sheath mouthpiece with a hole diameter φ of 0.30 mm, with a single hole discharge rate of 0.43 g / min, a core-sheath type cross section in which polypropylene-based resin is placed in the core component and polyethylene-based resin is placed in the sheath component. After the spun threads are cooled and solidified, they are pulled and stretched by compressed air with an ejector pressure of 0.50 MPa using a rectangular ejector, and collected on a moving net to collect the long fibers of the core-sheath type composite fiber. Obtained a non-woven fiber web consisting of. The characteristics of the long fibers of the obtained core-sheath type composite fiber were that the single fiber fiber diameter was 10.9 μm, and the spinning speed converted from this was 5,049 m / min. As for the spinnability, the yarn breakage was as good as 0 times in 1 hour of spinning.

Subsequently, the obtained non-woven fiber web was used as an embossed roll with an adhesive area ratio of 16%, which was made of metal and engraved with a polka dot pattern on the upper roll, and a pair of upper and lower heats composed of a metal flat roll on the lower roll. Using an embossed roll, heat bonding was performed at a linear pressure of 30 N / cm and a heat bonding temperature of 120 ° C. to obtain a spunbonded nonwoven fabric having a grain size of 18 g / m ² . The obtained spunbonded nonwoven fabric was measured and evaluated for complex viscosity, aeration rate CV value, standard deviation MMD of friction coefficient and melting peak. The results are shown in Table 1.

(Example 2)
A spunbonded nonwoven fabric was obtained by the same method as in Example 1 except that the MFR of the polypropylene resin was 300 g / 10 minutes. The characteristics of the long fiber made of the obtained core-sheath type composite fiber were that the single fiber fiber diameter was 10.5 μm, and the spinning speed converted from this was 5,457 m / min. As for the spinnability, the yarn breakage was as good as 0 times in 1 hour of spinning. The obtained spunbonded nonwoven fabric was measured and evaluated for complex viscosity, aeration rate CV value, standard deviation MMD of friction coefficient and melting peak. The results are shown in Table 1.

(Example 3)
A spunbonded nonwoven fabric was obtained by the same method as in Example 1 except that the MFR of the polypropylene resin was 850 g / 10 minutes. The characteristic of the long fiber made of the obtained core-sheath type composite fiber was that the diameter of the single fiber fiber was 9.8 μm, and the spinning speed converted from this was 6,264 m / min. As for the spinnability, the yarn breakage was as good as 0 times in 1 hour of spinning. The obtained spunbonded nonwoven fabric was measured and evaluated for complex viscosity, aeration rate CV value, standard deviation MMD of friction coefficient and melting peak. The results are shown in Table 1.

(Comparative Example 1)
A spunbonded nonwoven fabric was obtained by the same method as in Example 1 except that the MFR of the polypropylene resin was 60 g / 10 minutes and the ejector pressure was 0.15 MPa. The characteristics of the core-sheath length fiber were that the single fiber fiber diameter was 18.0 μm, and the spinning speed converted from this was 1,857 m / min. Regarding the spinnability, the yarn breakage was poor at 10 times in 1 hour of spinning. The obtained spunbonded nonwoven fabric was measured and evaluated for complex viscosity, aeration rate CV value, standard deviation MMD of friction coefficient and melting peak. The results are shown in Table 1.

(Comparative Example 2)
A spunbonded nonwoven fabric was obtained by the same method as in Example 1 except that the MFR of the polyethylene resin was 20 g / 10 minutes and the ejector pressure was 0.15 MPa. The characteristics of the long fibers of the obtained core-sheath type composite fiber were that the single fiber fiber diameter was 17.4 μm, and the spinning speed converted from this was 1,899 m / min. Regarding the spinnability, the yarn breakage was poor at 8 times in 1 hour of spinning. The obtained spunbonded nonwoven fabric was measured and evaluated for complex viscosity, aeration rate CV value, standard deviation MMD of friction coefficient and melting peak. The results are shown in Table 1.

In Examples 1 to 3, the spinnability was good even at a high spinning speed, and the results showed high productivity and stability. Further, in Examples 1 to 3, since the diameter was reduced at a high spinning speed, the uniformity and the surface touch property were excellent.

On the other hand, as shown in Comparative Examples 1 and 2, when a polypropylene resin and / or a polyethylene resin having a relatively small MFR is used and the complex viscosity is high, yarn breakage occurs at a high spinning speed and stable production is performed. There was a problem that it couldn't be done. Further, as shown in Comparative Examples 2 and 3, in the case of a thick single fiber fiber diameter, the spinning speed was low, so that the fibers were entangled before landing on the net, resulting in poor uniformity.

(A): Core portion (b): Sheath portion (c): First component (d): Second component

Claims (1)

A polypropylene-based resin having a melt flow rate of 155 to 850 g / 10 minutes is used as a core component, a polyethylene-based resin having a melt flow rate of 50 to 200 g / 10 minutes is used as a sheath component, and the core component is used in a cross section. A spunbonded nonwoven fabric composed of a core-sheath type composite fiber in which the center of the core portion and the sheath portion composed of the sheath component are the same, and the single fiber fiber diameter of the composite fiber is 6.5 to 14. The spunbond having a thickness of 5 μm, the air permeability CV value of the spunbonded nonwoven fabric is 7% or less, and the complex viscosity at 6.28 rad / sec at a temperature of 230 ° C. is 100 Pa · sec or less. Non-woven fabric.

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