JP2020196962A - Spun-bonded nonwoven fabric - Google Patents

Abstract

To provide a spun-bonded nonwoven fabric that is composed of polyolefin fibers having good spinnability and high productivity while having a small single fiber diameter, and has high flexibility and excellent touch.SOLUTION: A spun-bonded nonwoven fabric is composed of fibers comprising a polyolefin-based resin. The spun-bonded nonwoven fabric has a fused part and a non-fused part. An average single fiber diameter of the fibers is 6.5 μm or more and 16.6 μm or less. The fibers of the non-fused part have a melting temperature (Tm1) of an original crystal obtained by measuring using DSC is 130°C or more and 150°C or less. In the fibers of the non-fused part, a difference (Tm2-Tm1) between the melting temperature (Tm1) of the original crystal and a main melting temperature (Tm2) of a recrystallized substance is 20°C or more and 30°C or less.SELECTED DRAWING: None

Description

The present invention relates to a spunbonded non-woven fabric made of a polyolefin fiber and particularly suitable for use as a sanitary material.

In general, non-woven fabrics for sanitary materials such as disposable diapers and sanitary napkins are required to have texture, touch, flexibility and high productivity. In particular, since the top sheet of disposable diapers is a material that comes into direct contact with the skin, it is one of the applications for which there is a high demand for touch and flexibility.

As described above, as a means for improving the texture, touch and flexibility, it has been conventionally known that a method of controlling the fiber diameter of the fibers constituting the non-woven fabric is effective. For example, by using a polypropylene resin having a relatively large melt flow rate as a raw material and setting the draft ratio to 1500 or more, the diameter of the single fiber fineness can be reduced to 1.5 denier or less, and both flexibility and strength can be achieved. It has been proposed (see Patent Document 1).

Further, it contains a propylene-based polymer having a melting point of 120 ° C. or higher, a propylene-based polymer having a melting point of less than 120 ° C., and a fatty acid amide having 15 or more and 21 or less carbon atoms, and has both a soft and fluffy feeling and a smooth feeling. A flexible spunbonded nonwoven fabric has been proposed (see Patent Document 2).

Japanese Patent No. 4943349 Japanese Patent No. 5931207

However, in the method disclosed in Patent Document 1, a polypropylene-based resin having a relatively large melt flow rate is used as a raw material, and the diameter is reduced by setting the draft ratio to 1500 or more. Therefore, a low-viscosity raw material has a large pore diameter. It is necessary to spin with the mouthpiece of. As a result, back pressure on the base is less likely to be applied, uniform spinning is not possible, thread breakage and uneven fiber diameter are likely to occur, and there is room for improvement in the feel of the non-woven fabric.

On the other hand, in the method disclosed in Patent Document 2, since a propylene-based polymer having a melting point of less than 120 ° C. is used, the spinnability is inferior, and as a result, the fiber diameter is large and the texture is not satisfactory.

Therefore, in view of the above problems, an object of the present invention is to provide a spunbonded nonwoven fabric which is made of a polyolefin fiber having a small single fiber diameter but good spinnability and high productivity, and has high flexibility and excellent touch. It is in.

As a result of diligent studies to achieve the above object, the present inventors have found that it is important to appropriately control the melting temperature of the original crystal of the fiber, and have found that the flexibility and the touch can be improved. Obtained.

The spunbonded nonwoven fabric of the present invention is a spunbonded nonwoven fabric composed of fibers made of a polyolefin-based resin, and the spunbonded nonwoven fabric has a fused portion and a non-fused portion, and the average single of the fibers is simple. The fiber diameter is 6.5 μm or more and 16.6 μm or less, and the fiber of the non-woven fabric has a melting temperature (T _m1 ) of the original crystal obtained by measuring with DSC of 130 ° C. or more and 150 ° C. or less. In addition, the difference (T _m2- T _m1 ) between the melting temperature (T _m1 ) of the original crystal and the main melting temperature (T _m2 ) of the recrystallized fabric of the fibers in the non-woven fabric is larger than 20 ° C. and 30 ° C. or less. It is a spunbonded non-woven fabric.

According to a preferred embodiment of the spunbonded nonwoven fabric of the present invention, the fibers in the non-fused portion have a main melting temperature of a recrystallized product obtained by measuring with DSC of 160 ° C. or higher and 180 ° C. or lower.

According to a preferred embodiment of the spunbonded nonwoven fabric of the present invention, it is a spunbonded nonwoven fabric in which a polyolefin resin contains a fatty acid amide compound having 23 to 50 carbon atoms.

According to a preferred embodiment of the spunbonded nonwoven fabric of the present invention, the amount of the fatty acid amide compound added is 0.01% by mass or more and 5.0% by mass or less.

According to a preferred embodiment of the spunbonded nonwoven fabric of the present invention, the fatty acid amide compound is ethylene bisstearic acid amide.

According to a preferred embodiment of the spunbonded nonwoven fabric of the present invention, it is a spunbonded nonwoven fabric composed of fibers made of a polypropylene resin.

According to a preferred embodiment of the spunbonded nonwoven fabric of the present invention, the melt flow rate is 155 g / 10 minutes or more and 850 g / 10 minutes.

According to a preferred embodiment of the spunbonded nonwoven fabric of the present invention, the average single fiber diameter of the fibers is 6.5 μm or more and 14.0 μm or less.

According to the present invention, it is possible to obtain a spunbonded nonwoven fabric which is made of a polyolefin fiber having a small single fiber diameter but good spinnability and high productivity, and has high flexibility and excellent touch. From these characteristics, the spunbonded nonwoven fabric of the present invention can be suitably used particularly for sanitary material applications.

The spunbonded nonwoven fabric of the present invention is a spunbonded nonwoven fabric composed of fibers made of a polyolefin-based resin, and the spunbonded nonwoven fabric has a fused portion and a non-fused portion, and the average single of the fibers is simple. The fiber diameter is 6.5 μm or more and 16.6 μm or less, and the fiber of the non-woven fabric has a melting temperature (T _m1 ) of the original crystal obtained by measuring with DSC of 130 ° C. or more and 150 ° C. or less. In addition, in the fibers of the non-woven fabric, the difference (T _m2- T _m1 ) between the melting temperature (T _m1 ) of the original crystal and the main melting temperature (T _m2 ) of the recrystallized fabric is larger than 20 ° C. and 30 ° C. or less. is there.

By doing so, it is possible to obtain a spunbonded non-woven fabric having high flexibility and excellent touch. The details of these will be described below.

[Polyolefin-based resin]
Examples of the polyolefin-based resin used in the spunbonded nonwoven fabric of the present invention include polyethylene-based resin, polypropylene-based resin, and a resin in which these are mixed. Examples of the polyethylene-based resin include a homopolymer of ethylene, a copolymer of ethylene and various α-olefins, and a resin obtained by mixing an homopolymer of ethylene and the above-mentioned copolymer. Examples of the polypropylene-based resin include a propylene homopolymer, a copolymer of propylene and various α-olefins, and a resin obtained by mixing a propylene homopolymer and the above-mentioned copolymer. Be done. Above all, when the polyolefin-based resin is a polypropylene-based resin, it is possible to improve the spinnability at the time of producing the spunbonded nonwoven fabric or the mechanical properties such as the strength of the obtained spunbonded nonwoven fabric, which is more preferable. The polyolefin-based resin of the present invention includes the above-mentioned resin, a fatty acid amide compound having 23 or more and 50 or less carbon atoms, which will be described later, an antioxidant which is usually used as long as the effect of the present invention is not impaired, and weather resistance. Additives such as stabilizers, light stabilizers, antistatic agents, antifoaming agents, antiblocking agents, lubricants, nucleating agents, and pigments, or thermoplastic elastomers and other polymers can be added as needed. ..

The polyolefin-based resin used in the present invention preferably contains at least a homopolymer of propylene, and more preferably the mixing ratio of the homopolymer of propylene in the polyolefin resin is 60% by mass or more. By setting the mixing ratio of the homopolymer of propylene in this polyolefin resin to 60% by mass or more, more preferably 70% by mass or more, and most preferably 80% by mass or more, the spinnability at the time of producing a spunbonded nonwoven fabric is improved. And the strength of the spunbonded non-woven fabric can be improved.

Further, regarding the polyolefin-based resin used in the present invention, when the polyolefin-based resin is a polypropylene-based resin, in order to improve the spinnability at the time of producing the spunbonded nonwoven fabric and to make the spunbonded nonwoven fabric more flexible. , Polyolefins of propylene and various α-olefins are preferably contained in the range of 0.1% by mass or more and 40% by mass or less. The flexibility of the spunbonded non-woven fabric can be improved by containing 0.1% by mass or more, more preferably 1% by mass or more, still more preferably 3% by mass or more. On the other hand, by containing 40% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less, the spinnability at the time of producing the spunbonded nonwoven fabric can be improved.

Further, the polyolefin-based resin used in the present invention preferably contains a fatty acid amide compound having 23 or more and 50 or less carbon atoms in order to improve slipperiness and flexibility.

By setting the number of carbon atoms of the fatty acid amide compound contained in the polyolefin resin to preferably 23 or more, more preferably 30 or more, the fatty acid amide compound is suppressed from being excessively exposed on the fiber surface, and the spinnability It has excellent processing stability and can maintain high productivity. On the other hand, by setting the number of carbon atoms of the fatty acid amide compound to 50 or less, more preferably 42 or less, the fatty acid amide compound can easily move to the fiber surface, and the spunbonded nonwoven fabric can be imparted with slipperiness and flexibility. Can be done.

Examples of the fatty acid amide compound having 23 or more and 50 or less carbon atoms used in the present invention include a saturated fatty acid monoamide compound, a saturated fatty acid diamide compound, an unsaturated fatty acid monoamide compound, and an unsaturated fatty acid diamide compound.

Specifically, as fatty acid amide compounds having 23 or more and 50 or less carbon atoms, tetradocosanoic acid amide, hexadokosanic acid amide, octadokosanic acid amide, nervonic acid amide, tetracosaentapenic acid amide, heric acid amide, ethylenebislauric acid amide, Methylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbechenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisstearic acid amide, hexamethylene hydroxystearic acid amide, distearyl adipic acid Examples thereof include amides, distearyl sebacic acid amides, ethylene bisoleic acid amides, ethylene biserucic acid amides, hexamethylene bisoleic acid amides, and the like, and these can be used in combination of two or more.

Among these fatty acid amide compounds, ethylene bisstearic acid amide, which is a saturated fatty acid diamide compound, is particularly preferably used in the present invention. Since ethylene bisstearic acid amide has excellent thermal stability, it can be melt-spun, and by using a polyolefin resin containing this ethylene bisstearic acid amide, slipperiness is maintained while maintaining high productivity. It is possible to obtain a spunbonded nonwoven fabric having excellent flexibility.

In the present invention, the amount of the fatty acid amide compound added to the polyolefin resin is preferably 0.01% by mass or more and 5.0% by mass or less. By setting the addition amount of the fatty acid amide compound to preferably 0.01% by mass or more, more preferably 0.1% by mass or more, the spunbonded nonwoven fabric can have excellent slipperiness and flexibility. .. On the other hand, by setting the content to 5.0% by mass or less, more preferably 3.0% by mass or less, still more preferably 1.0% by mass or less, the spinnability at the time of producing the spunbonded nonwoven fabric can be improved.

The amount added here means the mass percent of the fatty acid amide compound added to the entire polyolefin resin constituting the spunbonded nonwoven fabric of the present invention. For example, even when the fatty acid amide compound is added only to the sheath portion component constituting the core-sheath type composite fiber, the addition ratio to the total amount of the core-sheath component is calculated.

As a method for measuring the amount of the fatty acid amide compound added to the fiber made of a polyolefin resin, for example, the additive is extracted from the fiber by a solvent and quantitatively analyzed by liquid chromatography-mass spectrometry (LS / MS) or the like. The method can be mentioned. At this time, the extraction solvent is appropriately selected according to the type of fatty acid amide compound. For example, in the case of ethylene bisstearic acid amide, a method using a mixed solution of chloroform and methanol can be mentioned as an example.

The melting point of the polyolefin resin used in the present invention is preferably 100 ° C. or higher and 200 ° C. or lower. By setting the melting point to preferably 100 ° C. or higher, more preferably 120 ° C. or higher, and further preferably 160 ° C. or higher, heat resistance that can withstand practical use can be imparted. Further, by setting the melting point to preferably 200 ° C. or lower, more preferably 180 ° C. or lower, and further preferably 170 ° C. or lower, it becomes easier to cool the yarn discharged from the mouthpiece, and fusion of fibers is suppressed and stable. It becomes easier to spin the yarn. Here, the melting point of the polyolefin resin refers to the main melting peak temperature obtained by differential scanning calorimetry (DSC).

The melt flow rate (sometimes abbreviated as MFR) of the polyolefin resin of the present invention is preferably 155 g / 10 minutes or more and 850 g / 10 minutes or less. By setting the amount to 155 g / 10 minutes or more, the thinning behavior when the fiber is drawn is stable, and even if the fiber is drawn at a high spinning speed in order to increase productivity, stable spinning can be achieved. In addition, by stabilizing the thinning behavior, thread sway is suppressed, and unevenness when collecting in the form of a sheet is less likely to occur. Further, since it is possible to draw the fiber stably and at a high spinning speed, the orientation and crystallization of the fiber can be promoted to obtain a fiber having high mechanical strength. On the other hand, by setting the weight to 850 g / 10 minutes or less, more preferably 600 g / 10 minutes or less, still more preferably 400 g / 10 minutes or less, tension is less likely to be applied when the fibers are stretched, and yarn sway increases. It is possible to suppress a decrease in mechanical strength.

For the MFR of this polyolefin resin, a value measured by ASTM D1238 (method A) is adopted. According to this standard, for example, polypropylene is measured at a load of 2.16 kg and a temperature of 230 ° C., and polyethylene is measured at a load of 2.16 kg and a temperature of 190 ° C.

Of course, the MFR of the polyolefin-based resin can be adjusted by blending two or more kinds of resins having different MFRs at an arbitrary ratio. In this case, the MFR of the resin to be blended with the main polyolefin resin is preferably 10 g / 10 minutes or more and 1000 g / 10 minutes or less. By setting the MFR of the blended resin to 10 g / 10 minutes or more, more preferably 20 g / 10 minutes or more, still more preferably 30 g / 10 minutes or more, the blended polyolefin resin partially has viscosity spots and the fineness is poor. It is possible to prevent homogenization and deterioration of spinnability. On the other hand, when the content is 800 g / 10 minutes or less, more preferably 600 g / 10 minutes or less, the blended polyolefin resin partially has viscosity unevenness, the fineness becomes non-uniform, and the mechanical strength partially decreases. It is possible to prevent the spinnability from being deteriorated.

Further, when spinning the fiber described later, this resin is decomposed with respect to the resin used in order to prevent the occurrence of partial viscosity unevenness, make the fineness of the fiber uniform, and further reduce the fiber diameter as described later. It is also conceivable to adjust the MFR. However, for example, it is preferable not to add a peroxide, particularly a free radical agent such as a dialkyl peroxide. When this method is used, viscosity spots are partially generated and the fineness becomes non-uniform, making it difficult to sufficiently reduce the fiber diameter. In addition, when the spinnability deteriorates due to viscosity spots and bubbles caused by decomposition gas. There is also.

[Fiber made of polyolefin resin]
The spunbonded nonwoven fabric of the present invention is composed of fibers made of the above-mentioned polyolefin resin. It is important that the average single fiber diameter of this fiber is 6.5 μm or more and 16.6 μm. By setting the average single fiber diameter to 6.5 μm or more, preferably 7.5 μm or more, more preferably 8.4 μm or more, it is possible to prevent deterioration of spinnability and stably produce a high quality spunbonded non-woven fabric. it can. On the other hand, by setting the average single fiber diameter to 16.6 μm or less, preferably 14.0 μm or less, more preferably 11.9 μm or less, it is possible to improve the flexibility and obtain a highly uniform spunbonded nonwoven fabric. ..

In the present invention, the average single fiber diameter (μm) of the fibers constituting the spunbonded nonwoven fabric shall be a value calculated by the following procedure.
(1) A polyolefin-based resin is melt-spun, towed and stretched by an ejector, and then a non-woven fiber web is collected on a net.
(2) Randomly collect 10 small piece samples (100 x 100 mm).
(3) A surface photograph of 500 to 1000 times is taken with a microscope, and the width of 100 polyolefin fibers is measured, 10 from each sample.
(4) The average single fiber diameter (μm) is calculated from the average value of the measured 100 fibers.

Among the fibers constituting the spunbonded nonwoven fabric of the present invention, the fibers in the non-fused portion have a melting temperature (T _m1 ) of 130 ° C. or higher and 150, which is obtained by measuring using DSC. It is important that the temperature is below ° C. By setting the melting temperature (T _m1 ) of the original crystal of the fiber to 130 ° C. or higher and 150 ° C. or lower, preferably 135 ° C. or higher and 148 ° C. or lower, more preferably 140 ° C. or higher and 146 ° C. or lower, a non-woven fabric having excellent flexibility is obtained. be able to.

Among the fibers constituting the spunbonded nonwoven fabric of the present invention, the fibers in the non-fused portion have a recrystallized main melting temperature (T _m2 ) of 160 ° C. or higher and 180 ° C. or higher, which is obtained by measuring using DSC. The temperature is preferably 1 ° C. or lower, more preferably 160 ° C. or higher and 170 ° C. or lower. By setting the main melting temperature (T _m2 ) of the recrystallized product to preferably 160 ° C. or higher, heat resistance that can withstand practical use can be imparted. Further, by setting the main melting temperature (T _m2 ) of the recrystallized product to preferably 180 ° C. or lower, more preferably 170 ° C. or lower, it becomes easier to cool the threads discharged from the mouthpiece, and the fibers are fused to each other. Suppressed and stable spinning becomes easier. By doing so, it has heat resistance that can withstand practical use, suppresses fusion between fibers, and facilitates stable spinning.

Among the fibers constituting the spunbonded nonwoven fabric of the present invention, the fibers in the non-fused portion have the melting temperature of the original crystal of the fiber and the main melting temperature of the recrystallized product obtained by measuring with DSC. It is important that the difference (T _m2- T _m1 ) is greater than 20 ° C and less than 30 ° C. The difference between the melting temperature of the original crystal of the fiber and the main melting temperature of the recrystallized fabric (T _m2- T _m1 ) is greater than 20 ° C (that is, (T _m2- T _m1 )> 20 ° C), preferably 21 ° C or higher. A non-woven fabric having excellent flexibility is obtained by more preferably 22 ° C. or higher, further preferably 23 ° C. or higher, or 30 ° C. or lower, preferably 27 ° C. or lower, and more preferably 25 ° C. or lower. be able to.

In the present invention, the melting temperature difference (T _m1 ) of the original crystals of the fibers of the non-fused portion constituting the spunbonded non-woven fabric and the main melting temperature difference (T _m2 ) of the recrystallized fabric are calculated by the following procedure. The value to be used shall be adopted.
(1) The fiber pieces of the non-fused portion of the spunbonded non-woven fabric are sampled.
(2) Using the differential scanning calorimetry (DSC), DSC curves are obtained for four heating rates of 5 ° C / min, 20 ° C / min, 50 ° C / min, and 100 ° C / min.
(3) Read all the melting peak temperatures from the DSC curve to the smallest ones, and plot the horizontal axis as the square root of the heating rate ((° C / min) ^0.5 ) and the vertical axis as the melting peak temperature (° C).
(4) The melting peak derived from the original crystal of the fiber is the one whose melting peak temperature is rising as the temperature rising rate is increased, and the melting peak temperature is decreasing or leveling off as the temperature rising rate is increased. Classified as melting peaks derived from crystals. There may be a plurality of melting peaks derived from recrystallized products. In this case, the one having the largest peak area is used as the main melting peak. When there are a plurality of melting peaks derived from the original crystal of the fiber, the one having the largest peak area is used as the representative peak and used in the subsequent analysis.
(5) The temperature corresponding to the melting peak derived from the original crystal of the fiber is fitted with a straight line, and the Y intercept (square root of the heating rate = 0) is set to "the difference in melting temperature of the original crystal of the fiber (T _m1 ) (° C.)". And.
(6) The temperature corresponding to the main melting peak derived from the recrystallized product is fitted with a straight line, and the Y intercept (square root of the heating rate = 0) is defined as "the main melting temperature difference of the recrystallized product (T _m2 ) (° C.)". And.

Depending on the temperature rise rate, the melting peak derived from the original crystal of the fiber may overlap with the main melting peak derived from the recrystallized product and cannot be read. In such a case, only the result at a readable temperature rise rate is shown. The melting temperature (T _m1 ) of the original crystal of the fiber is calculated using. If there is only one readable rate of temperature rise or does not exist, the temperature may be measured at a rate of temperature rise other than the above to calculate the melting temperature (T _m1 ) of the original crystal of the fiber.

[Spanbond non-woven fabric]
The spunbonded nonwoven fabric of the present invention preferably has a surface roughness SMD of 1.0 μm or more and 2.6 μm or less by the KES method on at least one side. By setting the surface roughness SMD to 1.0 μm or more, preferably 1.3 μm or more, more preferably 1.6 μm or more, and further preferably 2.0 μm or more, the spunbonded non-woven fabric becomes excessively dense and the texture deteriorates. It is possible to prevent the flexibility from being impaired. On the other hand, by setting the surface roughness SMD by the KES method to 2.6 μm or less, preferably 2.5 μm or less, more preferably 2.4 μm or less, still more preferably 2.3 μm or less, the surface is smooth and the feeling of roughness is small. , It can be a spunbonded non-woven fabric having excellent touch. The surface roughness SMD by the KES method can be controlled by appropriately adjusting the average single fiber diameter, the CV value of the single fiber diameter, the fiber dispersion degree, and the like.

In the present invention, the surface roughness SMD by the KES method shall adopt the value measured as follows.
(1) Three test pieces having a width of 200 mm × 200 mm are collected from the spunbonded non-woven fabric at equal intervals in the width direction of the spunbonded non-woven fabric.
(2) Set the test piece on the sample table.
(3) Scan the surface of the test piece with a contact for surface roughness measurement (material: φ0.5 mm piano wire, contact length: 5 mm) to which a load of 10 gf is applied, and measure the average deviation of the uneven shape of the surface. To do.
(4) The above measurement was performed in the vertical direction (longitudinal direction of the non-woven fabric) and the horizontal direction (width direction of the non-woven fabric) of all the test pieces, and the average deviations of these 6 points in total were averaged to the second place after the decimal point. Is rounded to the surface roughness SMD (μm).

The coefficient of friction MIU of the spunbonded non-woven fabric of the present invention by the KES method on at least one side is preferably 0.1 or more and 0.5 or less. By setting the friction coefficient MIU to preferably 0.5 or less, more preferably 0.45 or less, and further preferably 0.4 or less, the slipperiness of the surface of the non-woven fabric is improved, and a spunbonded non-woven fabric having a better feel is obtained. be able to. On the other hand, by setting the friction coefficient MIU to preferably 0.1 or more, more preferably 0.15 or more, and further preferably 0.2 or more, excessive addition of a lubricant may deteriorate spinnability or make the yarn. It is possible to prevent the threads from slipping and the texture from deteriorating when collected on the net. The coefficient of friction MIU by the KES method can be controlled by adjusting the average single fiber diameter, fiber dispersity, etc., or by adding a lubricant to the polyolefin resin.

The variation MMD of the friction coefficient by the KES method on at least one side of the spunbonded nonwoven fabric of the present invention is preferably 0.002 or more and 0.008 or less. By setting the variation MMD of the friction coefficient to preferably 0.008 or less, more preferably 0.0077 or less, still more preferably 0.0075 or less, the roughness of the surface of the spunbonded non-woven fabric can be further reduced. On the other hand, by setting the fluctuation MMD of the friction coefficient to preferably 0.002 or more, more preferably 0.004 or more, and further preferably 0.005 or more, the production equipment is complicated or the productivity is extremely lowered. You can prevent it from happening. Fluctuations in the coefficient of friction by the KES method The MMD can be controlled by adjusting the average single fiber diameter, the CV value of the single fiber diameter, the fiber dispersion degree, and the like, or by adding a lubricant to the polyolefin resin.

In the present invention, the friction coefficient MIU and the fluctuation MMD of the friction coefficient by the KES method shall adopt the values measured as follows.
(1) Three test pieces having a width of 200 mm × 200 mm are collected from the spunbonded non-woven fabric at equal intervals in the width direction of the spunbonded non-woven fabric.
(2) Set the test piece on the sample table.
(3) The surface of the test piece is scanned with a contact friction element (material: φ0.5 mm piano wire (20 pieces in parallel), contact area: 1 cm ² ) to which a load of 50 gf is applied, and the friction coefficient is measured.
(4) The above measurement was performed in the vertical direction (longitudinal direction of the non-woven fabric) and the horizontal direction (width direction of the non-woven fabric) of all the test pieces, and the average deviations of these 6 points in total were averaged to the 4th place after the decimal point. Is rounded to the friction coefficient MIU. Further, the fluctuations of the friction coefficient at the above 6 points are further averaged and rounded to the fourth decimal place to obtain the fluctuation MMD of the friction coefficient.

Further, in the present invention, the feel of the spunbonded nonwoven fabric is evaluated by a sensory test.

The melt flow rate of the spunbonded nonwoven fabric of the present invention (hereinafter, may be referred to as MFR) is preferably 155 g / 10 minutes or more and 850 g / 10 minutes or less. The MFR is preferably 155 g / 10 minutes or more and 850 g / 10 minutes or less, more preferably 155 g / 10 minutes or more and 600 g / 10 minutes or less, and further preferably 155 g / 10 minutes or more and 400 g / 10 minutes or less. The thinning behavior at the time of drawing is stable, and stable spinning is possible even if the fibers are drawn at a high spinning speed in order to increase productivity. In addition, by stabilizing the thinning behavior, thread sway is suppressed, and unevenness when collecting in the form of a sheet is less likely to occur. Further, since it is possible to draw the fiber stably and at a high spinning speed, the orientation and crystallization of the fiber can be promoted to obtain a fiber having high mechanical strength.

As the melt flow rate (MFR) of the spunbonded nonwoven fabric according to the present invention, a value measured by ASTM D1238 (method A) is adopted.

According to this standard, for example, polypropylene is measured at a load of 2.16 kg and a temperature of 230 ° C., and polyethylene is measured at a load of 2.16 kg and a temperature of 190 ° C.

The basis weight of the spunbonded non-woven fabric of the present invention is preferably 10 g / m ² or more and 100 g / m ² or less. By setting the basis weight to preferably 10 g / m ² or more, more preferably 13 g / m ² or more, and further preferably 15 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, 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, appropriate flexibility suitable for use as a non-woven fabric for sanitary materials can be obtained. It can be a spunbonded non-woven fabric having.

In the present invention, the basis weight of the spunbonded non-woven fabric shall be a value measured by the following procedure in accordance with "6.2 Mass per unit area" of JIS L1913: 2010 "General non-woven fabric test method". To do.
(1) Collect three 20 cm × 25 cm test pieces per 1 m of sample width.
(2) Weigh each mass (g) in the standard state.
(3) The average value is expressed by the mass per 1 m ² (g / m ² ).

The thickness of the spunbonded nonwoven fabric of the present invention is preferably 0.05 mm or more and 1.50 mm or less. By setting the thickness to preferably 0.05 mm or more, more preferably 0.08 mm or more, and further preferably 0.10 mm or more, it has an appropriate cushioning property suitable for use as a sanitary material, especially for disposable diapers. It can be a spunbonded non-woven fabric. On the other hand, by setting the thickness to preferably 1.50 mm or less, more preferably 1.00 mm or less, still more preferably 0.80 mm or less, a non-woven fabric having appropriate flexibility can be obtained.

In the present invention, the thickness (mm) of the spunbonded non-woven fabric adopts a value measured by the following procedure in accordance with "5.1" of JIS L1906: 2000 "General long fiber non-woven fabric test method". And.
(1) Using a pressurizer having a diameter of 10 mm, the thickness of 10 points per 1 m is measured in units of 0.01 mm at equal intervals in the width direction of the nonwoven fabric under a load of 10 kPa.
(2) Round off the third decimal place of the average value of the above 10 points.

Further, the apparent density of the spunbonded nonwoven fabric of the present invention is preferably 0.05 g / cm ³ or more 0.30 g / cm ³ or less. By setting the apparent density to preferably 0.30 g / cm ³ or less, more preferably 0.25 g / cm ³ or less, and further preferably 0.20 g / cm ³ or less, the fibers are tightly packed and the spunbonded non-woven fabric is used. It is possible to prevent the flexibility of the On the other hand, preferably the apparent density 0.05 g / cm ³ or more, more preferably 0.08 g / cm ³ or more, more preferably by a 0.10 g / cm ³ or more, suppressing the generation of fuzz or delamination , A spunbonded non-woven fabric having strength and handleability that can withstand practical use can be obtained.

In the present invention, the apparent density (g / cm ³ ) is calculated based on the following formula from the basis weight and thickness before rounding, and is rounded to the third decimal place.
-Appearance density (g / cm ³ ) = [Metsuke (g / m ² )] / [Thickness (mm)] x 10 ^-3 .

The sum of the rigidity and softness in the longitudinal direction and the lateral direction of the spunbonded nonwoven fabric of the present invention is preferably 0.45 mN · cm or less. The sum of the rigidity and softness in the vertical direction and the horizontal direction is preferably 0.45 mN · cm or less, more preferably 0.35 mN · cm or less, still more preferably 0.25 mN · cm or less, and thus a span for sanitary materials. As a bonded non-woven fabric, it is possible to obtain appropriate flexibility particularly suitable for use in disposable diaper applications. Further, when the rigidity and softness are extremely low, the handleability may be poor. Therefore, the sum of the rigidity and softness in the vertical direction and the horizontal direction is preferably 0.01 mN · cm or more. The rigidity and softness can be adjusted by adjusting the raw material composition and basis weight of the polyolefin resin, the single fiber diameter, and the thermocompression bonding conditions (bonding rate, temperature, linear pressure and speed).

In the present invention, the rigidity and softness of the spunbonded non-woven fabric in the vertical direction and the horizontal direction are as follows according to "6.7.3 41.5 ° cantilever method" of JIS L1913: 2010 "General non-woven fabric test method". The value measured by the procedure shall be adopted.
(1) Three 25 mm × 250 mm test pieces are collected per 1 m in width in each of the vertical direction (longitudinal direction of the non-woven fabric) and the horizontal direction (width direction of the non-woven fabric) of the non-woven fabric.
(2) Set the test piece on a 41.5 ° cantilever type tester, and gently push out the steel ruler and the test piece together in the direction of the slope at a constant speed.
(3) Move the steel ruler until the test piece comes into contact with the slope, and read the protruding length of the test piece from the steel ruler up to 1 mm. One test piece is measured four times on the front and back and both ends, and half of the average value is taken as the bending length (cm).
(4) Further, the average value of the bending lengths of all the test pieces is obtained in each of the vertical direction and the horizontal direction, and the second decimal place is rounded off to obtain the total average bending length.
(5) From the basis weight and the total average bending length measured by the above method, the rigidity and softness are calculated according to the following formulas in each of the vertical and horizontal directions, and the third decimal place is rounded off.
・ Rigidity and softness (mN ・ cm) = basis weight (g / m ² ) × [overall average bending length (cm)] ³ × 10 ^-3
The average flexural rigidity B of the spunbonded non-woven fabric of the present invention by the KES method is preferably 0.001 gf · cm ² / cm or more and 0.02 gf · cm ² / cm or less. By setting the average flexural rigidity B by the KES method to preferably 0.02 gf · cm ² / cm or less, more preferably 0.017 gf · cm ² / cm or less, and further preferably 0.015 gf · cm ² / cm or less. In particular, when used as a spunbonded non-woven fabric for sanitary materials, sufficient flexibility can be obtained. Further, when the average bending rigidity B by the KES method is extremely low, the handleability may be inferior. Therefore, the average bending rigidity B is preferably 0.001 gf · cm ² / cm or more. The average flexural rigidity B according to the KES method can be adjusted by the basis weight, single fiber diameter, and thermocompression bonding conditions (crimping rate, temperature, and linear pressure).

The stress at 5% elongation per basis weight (hereinafter, may be referred to as 5% modulus per basis weight) of the spunbonded nonwoven fabric of the present invention is 0.06 (N / 25 mm) / (g / m ² ) or more. It is preferably 0.33 (N / 25 mm) / (g / m ² ) or less. The 5% modulus per basis weight is preferably 0.06 (N / 25 mm) / (g / m ² ) or more, more preferably 0.13 (N / 25 mm) / (g / m ² ) or more, and further preferably. By setting the value to 0.20 (N / 25 mm) / (g / m ² ) or more, a spunbonded non-woven fabric that is flexible and has an excellent tactile sensation can be obtained. Further, the 5% modulus per basis weight is preferably 0.33 (N / 25 mm) / (g / m ² ) or less, more preferably 0.30 (N / 25 mm) / (g / m ² ) or less, and further. Preferably, it is 0.27 (N / 25 mm) / (g / m ² ) or less so that the strength that can withstand the transport tension during use can be maintained.

In the present invention, the stress at 5% elongation per basis weight of the spunbonded nonwoven fabric is as follows according to "6.3 Tensile Strength and Elongation Rate (ISO Method)" of JIS L1913: 2010 "General Nonwoven Fabric Test Method". The value measured by the procedure of is adopted.
(1) Three 25 mm × 300 mm test pieces are collected per 1 m in width in each of the vertical direction (longitudinal direction of the non-woven fabric) and the horizontal direction (width direction of the non-woven fabric) of the non-woven fabric.
(2) Grasp the test piece and set it in the tensile tester at an interval of 200 mm.
(3) A tensile test is carried out at a tensile speed of 100 mm / min, and the stress at 5% elongation (5% modulus) is measured.
(4) Obtain the average value of the 5% modulus in the vertical and horizontal directions measured with each test piece, calculate the 5% modulus per basis weight based on the following formula, and round off to the third decimal place.
5% modulus per basis weight ((N / 25 mm) / (g / m ² )) = [average value of 5% modulus (N / 25 mm)] / basis weight (g / m ² ).

Since the spunbonded non-woven fabric of the present invention has high productivity, high flexibility and excellent touch, 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.

[Manufacturing method of spunbonded non-woven fabric]
Next, a preferred embodiment of the method for producing the spunbonded nonwoven fabric of the present invention will be specifically described.

The spunbonded non-woven fabric of the present invention is a long-fiber non-woven fabric produced by the spunbond method. Examples of the method for producing a non-woven fabric include a spunbond method, a flash spinning method, a wet method, a card method and an airlaid method. The spunbond method is excellent in productivity and mechanical strength, and is a short fiber non-woven fabric. It is possible to suppress fluffing and fiber shedding that are likely to occur in. In addition, productivity and formation uniformity are improved by laminating multiple layers of collected spunbond non-woven fiber web or thermocompression-bonded spunbond non-woven fabric (both are referred to as S) with SS, SSS and SSSS. This is a preferred embodiment.

In the spunbond method, first, the molten thermoplastic resin is spun from a spinneret as long fibers, which is suction-stretched with compressed air by an ejector, and then the fibers are collected on a moving net to obtain a non-woven fiber web. .. Further, the obtained non-woven fiber web is heat-bonded to obtain a spunbonded non-woven fabric.

As the shape of the spinneret and the ejector, various shapes such as a round shape and a rectangular shape can be adopted. Among them, the combination of the rectangular base and the rectangular ejector is suitable because the amount of compressed air used is relatively small and the energy cost is excellent, the threads are less likely to be fused or scratched, and the threads can be easily opened. It is preferably used.

In the present invention, the polyolefin-based resin is melted in an extruder, weighed and supplied to a spinneret, and spun as long fibers. The spinning temperature when the polyolefin resin is melted and spun is preferably 200 ° C. or higher and 270 ° C. or lower. By setting the spinning temperature to preferably 200 ° C. or higher, more preferably 210 ° C. or higher, and further preferably 220 ° C. or higher, a stable molten state can be obtained and excellent spinning stability can be obtained. Further, by setting the spinning temperature to preferably 270 ° C. or lower, more preferably 260 ° C. or lower, and further preferably 250 ° C. or lower, thermal deterioration of the polyolefin resin can be suppressed and excellent spinning stability can be obtained.

The back pressure of the spinneret is preferably 0.1 MPa or more and 10.0 MPa or less. By setting the back pressure to preferably 0.1 MPa or more, more preferably 0.3 MPa or more, and even more preferably 0.5 MPa or more, it is possible to prevent deterioration of discharge uniformity and occurrence of fiber diameter variation. Further, by setting the back pressure to preferably 10.0 MPa or less, more preferably 8.0 MPa or less, and further preferably 6.0 MPa or less, it is possible to prevent the base from becoming large in order to increase the pressure resistance. The back pressure of the spinneret can be adjusted by adjusting the discharge hole diameter, the discharge hole depth, the spinning temperature, etc. of the spinneret, and the discharge hole diameter contributes greatly.

The spun long fiber yarns are then cooled. Examples of the method of cooling the spun yarn include a method of forcibly blowing cold air on the yarn, a method of naturally cooling at the ambient temperature around the yarn, and a method of adjusting the distance between the spinneret and the ejector. Etc., 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 towed and stretched by the compressed air injected from the ejector.

The spinning speed is preferably 3500 m / min or more and 7000 m / min or less. By setting the spinning speed to preferably 3500 m / min or more, more preferably 4000 m / min or more, and further preferably 4500 m / min or more, not only high productivity but also orientation crystallization of fibers can be achieved. It is possible to proceed and obtain high-strength long fibers. Normally, when the spinning speed is increased, the spinnability deteriorates and the filamentous shape cannot be stably produced. However, as described above, by using a polyolefin resin having a specific range of MFR, the intended polyolefin fiber is used. Can be stably spun. On the other hand, by setting the spinning speed to preferably 7,000 m / min or less, more preferably 6500 m / min or less, still more preferably 6000 m / min or less, excellent spinning stability can be obtained.

Subsequently, the obtained long fibers are collected on a moving net to obtain a non-woven fiber web.

In the present invention, it is also a preferred embodiment that a thermal flat roll is brought into contact with the non-woven fiber web from one side on the net to temporarily bond the web. By doing so, it is possible to prevent the surface layer of the non-woven fiber web from being turned over or blown off during transportation on the net, and to prevent the formation from deteriorating, or from collecting the threads to thermocompression bonding. Transportability can be improved.

Subsequently, the obtained non-woven fiber web is heat-bonded to obtain the intended spunbonded non-woven fabric.

As a method of heat-bonding the non-woven fiber web, a heat embossed roll in which a pair of upper and lower roll surfaces are engraved (concavo-convex parts), a roll having a flat (smooth) one roll surface and an engraving on the other roll surface. Thermal bonding methods using various rolls, such as thermal embossing rolls consisting of rolls with (unevenness) and thermal calendar rolls consisting of a pair of upper and lower flat (smooth) rolls, and ultrasonic vibration of the horn. A method such as ultrasonic bonding for heat welding can be mentioned. Among them, it is highly productive, it can give strength with a partial heat-bonded part, and it can maintain the texture and feel unique to non-woven fabric with a non-bonded part, so it is engraved on each of the upper and lower roll surfaces (uneven parts). ) Is applied, or a heat embossed roll consisting of a roll having a flat (smooth) surface on one roll and a roll having an engraving (unevenness) on the surface of the other roll is preferably used. It is an aspect.

As the surface material of the heat embossed roll, a metal roll and a metal roll are used in order to obtain a sufficient thermocompression bonding effect and prevent the engraving (uneven part) of one embossed roll from being transferred to the surface of the other roll. A pair is a preferred embodiment.

The embossing adhesion area ratio by such a heat embossing roll is preferably 5% or more and 30% or less. By setting the bonding area to preferably 5% or more, more preferably 8% or more, still more preferably 10% or more, strength that can be put into practical use as a spunbonded non-woven fabric can be obtained. On the other hand, by setting the adhesive area to preferably 30% or less, more preferably 25% or less, still more preferably 20% or less, it is suitable as a spunbonded non-woven fabric for sanitary materials, particularly suitable for use in disposable diapers. You can get sex. Even when ultrasonic bonding is used, the bonding area ratio is preferably in the same range.

The adhesive area referred to here refers to the ratio of the adhesive portion to the entire spunbonded non-woven fabric. Specifically, when heat-bonding with a pair of uneven rolls, the spunbonded non-woven fabric of the portion (adhesive portion) where the convex portion of the upper roll and the convex portion of the lower roll overlap and abut against the non-woven fiber web. It refers to the ratio to the whole. Further, in the case of heat-bonding between a roll having irregularities and a flat roll, the ratio of the convex portion of the roll having irregularities to the entire spunbonded non-woven fabric of the portion (adhesive portion) in contact with the non-woven fiber web. Further, in the case of ultrasonic bonding, it refers to the ratio of the portion (bonded portion) to be heat-welded by ultrasonic processing to the entire spunbonded non-woven fabric.

As the shape of the bonded portion by thermal embossing roll or ultrasonic bonding, a circle, an ellipse, a square, a rectangle, a parallelogram, a rhombus, a regular hexagon, a regular octagon, or the like can be used. Further, it is preferable that the bonded portions are uniformly present at regular intervals in the longitudinal direction (conveying direction) and the width direction of the spunbonded nonwoven fabric. By doing so, it is possible to reduce variations in the strength of the spunbonded non-woven fabric.

The surface temperature of the heat embossed roll at the time of heat bonding is preferably −50 ° C. or higher and −15 ° C. or lower with respect to the melting point of the polyolefin resin used. By setting the surface temperature of the thermal roll to −50 ° C. or higher, more preferably −45 ° C. or higher with respect to the melting point of the polyolefin resin, it is possible to obtain a spunbonded non-woven fabric having appropriate heat adhesion and strength that can be put into practical use. it can. Further, by setting the surface temperature of the heat embossed roll to -15 ° C. or lower, more preferably -20 ° C. or lower with respect to the melting point of the polyolefin resin, excessive thermal adhesion is suppressed and the spunbonded non-woven fabric for sanitary materials is used. As a result, it is possible to obtain appropriate flexibility particularly suitable for use in paper diaper applications.

The linear pressure of the heat embossing roll at the time of heat bonding is preferably 50 N / cm or more and 500 N / cm or less. By setting the linear pressure of the roll to preferably 50 N / cm or more, more preferably 100 N / cm or more, and further preferably 150 N / cm or more, it is possible to obtain a spunbonded non-woven fabric having a strength that can be appropriately heat-bonded and put into practical use. it can. On the other hand, by setting the linear pressure of the heat embossed roll to preferably 500 N / cm or less, more preferably 400 N / cm or less, still more preferably 300 N / cm or less, it is used as a spunbonded non-woven fabric for sanitary materials, especially for disposable diapers. Appropriate flexibility suitable for use can be obtained.

Further, in the present invention, for the purpose of adjusting the thickness of the spunbonded nonwoven fabric, thermocompression bonding may be performed by a thermal calendar roll composed of a pair of upper and lower flat rolls before and / or after thermal bonding by the above thermal embossing roll. it can. A pair of upper and lower flat rolls is a metal roll or an elastic roll having no unevenness on the surface of the roll, and a metal roll and a metal roll are paired, or a metal roll and an elastic roll are paired. Can be used. Further, the elastic roll here is a roll made of a material having elasticity as compared with a metal roll. Examples of the elastic roll include so-called paper rolls such as paper, cotton and aramid paper, and resin rolls made of urethane-based resin, epoxy-based resin, silicon-based resin, polyester-based resin and hard rubber, and a mixture thereof. Be done.

Next, the spunbonded nonwoven fabric of the present invention will be specifically described based on Examples. However, the present invention is not limited to these examples. In addition, in the measurement of each physical property, if there is no particular description, the measurement is performed based on the above method.

(1) Melt flow rate (MFR) of polyolefin resin:
The MFR of the polyolefin resin was measured under the conditions of a load of 2.16 kg and a temperature of 230 ° C.

(2) Spinning speed (m / min):
From the above average single fiber diameter and the solid density of the polyolefin resin used, the mass (g) per 10,000 m in length was calculated as the average single fiber fineness (dtex) by rounding off to the second decimal place. Next, from the average single fiber fineness 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), the following formula is used. The spinning speed was calculated based on this, and the tens digit was rounded off.
-Spinning speed (m / min) = (10000 x [single hole discharge amount (g / min)]) / [average single fiber fineness (dtex)].
(3) Melting temperature (T _m1 ) of the original crystal of the non-fused part fiber and main melting temperature (T _m2 ) (° C.) of the recrystallized product:
As the measuring device, "DSC8500" manufactured by Perkin-Elmer Co., Ltd. was used. The measurement conditions were as follows.
・ Atmosphere in the device: Nitrogen (20 mL / min)
-Temperature / calorific value calibration: High-purity indium (Tm = 156.61 ° C., ΔHm = 28.70 J / g)
・ Temperature range: Approximately -50 to 250 ° C
・ Temperature rise rate: 5 ° C / min, 20 ° C / min, 50 ° C / min, 100 ° C / min ・ Sample amount: Approximately 0.5-4 mg
-Sample container: Standard aluminum container (4) Melt flow rate (MFR) of spunbonded non-woven fabric:
The melt flow rate of the spunbonded non-woven fabric was measured by ASTM D1238 under the conditions of a load of 2160 g and a temperature of 230 ° C.

(5) Sum of flexibility in the vertical and horizontal directions (mN · cm):
Based on the above method, the flexibility in each of the vertical direction and the horizontal direction was obtained, and the sum of them was calculated.

(6) Touch of spunbonded non-woven fabric:
A sample having a size of 100 mm × 100 mm was taken, and 20 panelists touched the non-woven fabric, and each evaluated the feel of the spunbonded non-woven fabric according to the following five criteria. Subsequently, the points judged by each panelist were totaled to give the feel of the spunbonded non-woven fabric, and 80 points or more were passed. The touch is preferably 85 points or more, and more preferably 90 points or more.
5 points: Very good (I feel comfortable with excellent smoothness and flexibility.)
4 points: Good (between 5 and 3 points)
3 points: Normal (I feel smoothness and flexibility)
2 points: Bad (between 3 points and 1 point)
1 point: Very bad (feels lacking at least one of smoothness and flexibility)
(Example 1)
Ethylene bisstearic acid amide as a fatty acid amide compound was added in an amount of 0.5% by mass as a fatty acid amide compound to a polypropylene resin composed of a homopolymer having a melt flow rate (MFR) of 200 g / 10 min and a melting point of 163 ° C., and melted by an extruder to obtain a pore size. From a rectangular base having a φ of 0.30 mm and a hole depth of 2 mm, spinning was performed at a spinning temperature of 235 ° C. and a single hole discharge rate of 0.32 g / min. After the spun yarn was cooled and solidified, it was towed and stretched by compressed air having an ejector pressure of 0.35 MPa in a rectangular ejector, and collected on a moving net. As a result, a non-woven fiber web made of polypropylene filaments was formed. The characteristics of the fibers constituting the formed spunbond non-woven fiber web were that the average single fiber diameter was 10.1 μm, and the spinning speed converted from this was 4400 m / min. As for spinnability, no yarn breakage was observed after spinning for 1 hour, which was good.

Subsequently, the formed spunbonded non-woven fiber web is heated under the conditions of linear pressure: 300 N / cm and heat bonding temperature: 150 ° C. using a pair of upper and lower thermal embossed rolls composed of the following upper roll and lower roll. Adhesion gave a spunbonded non-woven fabric of 18 g / m ² .
(Upper roll): Metal embossed roll with polka dot engraving and an adhesive area ratio of 16% (Lower roll): Metal flat roll The results of evaluation of the obtained spunbonded non-woven fabric are shown in Table 1.

(Example 2)
A spunbonded nonwoven fabric was obtained by the same method as in Example 1 except that the concentration of ethylene bisstearic acid amide was 1.5% by mass. The characteristics of the fibers constituting the formed spunbond non-woven fiber web were that the average single fiber diameter was 10.1 μm, and the spinning speed converted from this was 4400 m / min. As for spinnability, no yarn breakage was observed after spinning for 1 hour, which was good. Table 1 shows the evaluation results of the obtained spunbonded non-woven fabric.

(Example 3)
A spunbonded nonwoven fabric was obtained by the same method as in Example 1 except that the concentration of ethylene bisstearic acid amide was 5.0% by mass. The characteristics of the fibers constituting the formed spunbond non-woven fiber web were that the average single fiber diameter was 10.1 μm, and the spinning speed converted from this was 4400 m / min. As for spinnability, no yarn breakage was observed after spinning for 1 hour, which was good. Table 1 shows the evaluation results of the obtained spunbonded non-woven fabric.

(Example 4)
A spunbonded nonwoven fabric was obtained by the same method as in Example 2 except that the polypropylene resin made of a homopolymer had an MFR of 800 g / 10 min and a melting point of 163 ° C. The characteristics of the fibers constituting the spunbonded non-woven fiber web formed were that the average single fiber diameter was 8.4 μm, and the spinning speed converted from this was 6400 m / min. As for spinnability, no yarn breakage was observed after spinning for 1 hour, which was good. Table 1 shows the evaluation results of the obtained spunbonded non-woven fabric.

(Example 5)
A spunbonded nonwoven fabric was obtained by the same method as in Example 2 except that the single-hole discharge rate was 0.43 g / min and the ejector pressure was 0.30 MPa. The characteristics of the fibers constituting the formed spunbond non-woven fiber web were that the average single fiber diameter was 12.9 μm, and the spinning speed converted from this was 3600 m / min. As for spinnability, no yarn breakage was observed after spinning for 1 hour, which was good. Table 1 shows the evaluation results of the obtained spunbonded non-woven fabric.

(Comparative Example 1)
A spunbonded nonwoven fabric was obtained by the same method as in Example 1 except that ethylene bisstearic acid amide was not added. The characteristics of the fibers constituting the spunbonded non-woven fiber web formed were that the average single fiber diameter was 10.1 μm, and the spinning speed converted from this was 4400 m / min. As for spinnability, no yarn breakage was observed after spinning for 1 hour, which was good. Table 1 shows the evaluation results of the obtained spunbonded non-woven fabric.

The obtained spunbonded non-woven fabric had a small difference between the melting temperature of the original crystal of the fiber in the non-fused portion and the melting temperature of the recrystallized product, which was inferior in flexibility and touch.

(Comparative Example 2)
A spunbonded nonwoven fabric was obtained by the same method as in Example 1 except that ethylene bisstearic acid amide was not added and the heat bonding temperature was set to 130 ° C. The characteristics of the fibers constituting the spunbonded non-woven fiber web formed were that the average single fiber diameter was 10.1 μm, and the spinning speed converted from this was 4400 m / min. As for spinnability, no yarn breakage was observed after spinning for 1 hour, which was good. Table 1 shows the evaluation results of the obtained spunbonded non-woven fabric.

The obtained spunbonded non-woven fabric had a small difference between the melting temperature of the original crystal of the fiber in the non-fused portion and the melting temperature of the recrystallized product, which was inferior in flexibility and touch.

(Comparative Example 3)
As a raw material, 90% by weight of a polypropylene resin made of a homopolymer having an MFR of 200 g / 10 minutes and a melting point of 163 ° C., and 10% by weight of an ethylene-propylene random copolymer resin (ethylene copolymerization ratio of 15%) having an MFR of 20 g / 10 minutes. A spunbonded non-woven fabric was obtained by the same method as in Example 1 except that the resin composition blended at a ratio of% was used and ethylene bisstearic acid amide was not added. The characteristics of the fibers constituting the spunbonded non-woven fiber web formed were that the average single fiber diameter was 10.1 μm, and the spinning speed converted from this was 4400 m / min. As for spinnability, no yarn breakage was observed after spinning for 1 hour, which was good. Table 1 shows the evaluation results of the obtained spunbonded non-woven fabric.

The obtained spunbonded non-woven fabric had a small difference between the melting temperature of the original crystal of the fiber in the non-fused portion and the melting temperature of the recrystallized product, which was inferior to the touch.

The average single fiber diameter is 6.5 to 16.6 μm, and the melting temperature of the original crystal obtained by measuring the fibers in the non-fused portion using DSC is 130 to 150 ° C., and further, the original crystal The spunbonded non-woven fabrics of Examples 1 to 5 in which the difference between the melting temperature and the main melting temperature of the recrystallized product is larger than 20 ° C. and 30 ° C. or lower have high flexibility and excellent touch, and are used as sanitary materials. It was particularly suitable.

On the other hand, the spunbonded non-woven fabric having a small difference between the melting temperature of the original crystal and the main melting temperature of the recrystallized product shown in Comparative Examples 1 to 3 was inferior in flexibility and touch to the non-woven fabric of the present invention. ..

Claims (8)

A spunbonded nonwoven fabric composed of fibers made of a polyolefin resin, the spunbonded nonwoven fabric has a fused portion and a non-fused portion, and the average single fiber diameter of the fibers is 6.5 μm or more and 16.6 μm. The fibers in the non-woven fabric have a melting temperature (T _m1 ) of 130 ° C. or higher and 150 ° C. or lower in the original crystal obtained by measuring with DSC, and the fibers in the non-woven fabric have a melting temperature of 130 ° C. or higher and 150 ° C. or lower. , The difference (T _m2- T _m1 ) between the melting temperature (T _m1 ) of the original crystal and the main melting temperature (T _m2 ) of the recrystallized fabric is larger than 20 ° C. and 30 ° C. or less. .. The spunbonded non-woven fabric according to claim 1, wherein the fiber of the non-fused portion has a main melting temperature (T _m2 ) of a recrystallized product obtained by measurement using DSC of 160 ° C. or higher and 180 ° C. or lower. The spunbonded nonwoven fabric according to claim 1 or 2, wherein the polyolefin-based resin contains a fatty acid amide compound having 23 or more and 50 or less carbon atoms. The spunbonded nonwoven fabric according to claim 3, wherein the amount of the fatty acid amide compound added is 0.01% by mass or more and 5.0% by mass or less. The spunbonded nonwoven fabric according to claim 3 or 4, wherein the fatty acid amide compound is ethylene bisstearic acid amide. The spunbonded nonwoven fabric according to any one of claims 1 to 5, which is composed of fibers made of polypropylene-based resin. The spunbonded nonwoven fabric according to any one of claims 1 to 6, wherein the melt flow rate is 155 g / 10 minutes or more and 850 g / 10 minutes or less. The spunbonded nonwoven fabric according to any one of claims 1 to 7, wherein the average single fiber diameter of the fibers is 6.5 μm or more and 14.0 μm or less.