TWI770366B - Spunbond Nonwoven - Google Patents

Abstract

The present invention provides a spunbond nonwoven fabric comprising polyolefin-based fibers with good spinnability and high productivity despite a small average single fiber diameter, uniform texture, smooth surface, excellent hand and skin feel, and high softness sex. The present invention relates to a spunbond nonwoven fabric, which is a spunbond nonwoven fabric composed of fibers containing polyolefin resin, wherein the average single fiber diameter of the aforementioned fibers is 6.5-11.9 μm, and the fiber dispersion degree according to the reflected light brightness is 10 Hereinafter, the surface roughness SMD according to the KES method on at least one side is 1.0 to 2.6 μm.

Description

Spunbond Nonwoven

The present invention relates to a spunbond nonwoven fabric, which is composed of fibers containing polyolefin resin, and is particularly suitable for use as a sanitary material.

In general, nonwoven fabrics for sanitary materials such as disposable diapers and sanitary napkins are required to have a feel, feel, softness, and high productivity. In particular, since the top sheet of a disposable diaper is a material that directly contacts the skin, it is one of the applications requiring high skin touch and softness.

As described above, it has been known that the method of controlling the fiber diameter of the fibers constituting the nonwoven fabric is effective as a means for improving the texture, skin feel, and softness. For example, there is proposed a spunbond nonwoven fabric in which the flexural softness of the fiber itself is improved by setting the fineness and the adsorption force of the fiber in a specific range (see Patent Document 1).

In addition, there is a proposal to use a polypropylene-based resin with a relatively high melt flow rate as a raw material, set the draft ratio to 1500 or more, and reduce the single fiber fineness to 1.5 denier or less to achieve both flexibility and strength. method (refer to Patent Document 2).

[Prior Art Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2013-159884

Patent Document 2: Japanese Invention Patent No. 4943349

However, in the method disclosed in Patent Document 1, a polypropylene-based resin having a relatively low melt flow rate, that is, a high viscosity, is used as a raw material, and the spinning speed is increased to, for example, 5,000 m/min. As the diameter is reduced, wire breakage is likely to occur, making it difficult to produce stably.

Furthermore, in Patent Document 1, it is also shown that by containing an ester compound having a melting point of 70° C. or higher, a smooth feeling is imparted to a nonwoven fabric, and the skin feel is improved. However, although the friction coefficient is indeed reduced in this proposal, the smoothness of the non-woven fabric cannot be sufficiently satisfied when compared to the required level, and further improvement of the skin feel is required.

On the other hand, in the method disclosed in Patent Document 2, by using a polypropylene-based resin having a relatively large melt flow rate as a raw material, and making the draft ratio 1500 or more, the diameter is reduced, so it is necessary to use a large pore diameter The spinning nozzle spins low-viscosity raw materials. Therefore, it is difficult to apply the back pressure of the spinning nozzle, and the spinning cannot be uniform, and there are problems that thread breakage and uneven fiber diameter are likely to occur, and there is room for improvement in the uniformity of the texture.

Therefore, in view of the above-mentioned problems, an object of the present invention is to provide a spunbond nonwoven fabric comprising polyolefin-based fibers with good spinnability and high productivity although the average single fiber diameter is small, and which has a uniform texture, a smooth surface, and a feel, Excellent skin feel and high softness.

The spunbond nonwoven fabric of the present invention is a spunbond nonwoven fabric, which is a spunbond nonwoven fabric composed of fibers containing polyolefin resin, the average single fiber diameter of the aforementioned fibers is 6.5~11.9 μm, and the fiber dispersion degree according to the reflected light brightness It is 10 or less, and the surface roughness SMD by KES method of at least one side is 1.0-2.6 micrometers.

According to a preferred aspect of the spunbond nonwoven fabric of the present invention, the apparent density of the aforementioned spunbond nonwoven fabric is 0.05-0.3 g/cm ³ .

According to a preferred aspect of the spunbond nonwoven fabric according to the present invention, the average friction coefficient MIU of at least one side of the spunbond nonwoven fabric according to the KES method is 0.1 to 0.5.

According to a preferred aspect of the spunbond nonwoven fabric of the present invention, the variation MMD of the average friction coefficient of the spunbond nonwoven fabric according to the KES method is 0.008 or less.

According to a preferred aspect of the spunbond nonwoven fabric of the present invention, the melt flow rate of the aforementioned spunbond nonwoven fabric is 155-850 g/10 minutes.

According to a preferred aspect of the spunbond nonwoven fabric of the present invention, the polyolefin-based resin contains a fatty acid amide compound having 23 to 50 carbon atoms.

According to a preferred aspect of the spunbond nonwoven fabric of the present invention, the amount of the fatty acid amide compound added is 0.01 to 5.0% by mass.

According to a preferred aspect of the spunbond nonwoven fabric of the present invention, the aforementioned fatty acid amide compound is ethylene bisstearate.

According to a preferred aspect of the spunbond nonwoven fabric of the present invention, the aforementioned spunbond nonwoven fabric is formed of fibers containing polypropylene-based resin.

According to the present invention, it is possible to obtain a spunbond nonwoven fabric comprising polyolefin fibers having good spinnability and high productivity although the average single fiber diameter is small, having a uniform texture, a smooth surface, excellent hand and skin feel, and more Has high flexibility. Due to these characteristics, the spunbond nonwoven fabric of the present invention is particularly suitable for use as a sanitary material.

[Form of implementing the invention]

The spunbond nonwoven fabric of the present invention is a spunbond nonwoven fabric, which is a spunbond nonwoven fabric composed of fibers containing polyolefin resin, the average single fiber diameter of the aforementioned fibers is 6.5~11.9 μm, and the fiber dispersion degree according to the reflected light brightness It is 10 or less, and the surface roughness SMD according to KES method (Kawabata Evaluation System, Kawabata Evaluation System) of at least one side is 1.0~2.6 μm.

By doing so, a spunbond nonwoven fabric having a uniform texture, a smooth surface, little roughness, excellent hand and skin feel, and excellent softness can be produced. The details of these will be described below.

[Polyolefin resin]

As a polyolefin resin used for this invention, a polypropylene resin and a polyethylene resin are mentioned, for example.

Examples of polypropylene-based resins include homopolymers of propylene, copolymers of propylene and various α-olefins, and the like.

Moreover, as a polyethylene-type resin, the homopolymer of ethylene, the copolymer of ethylene and various alpha-olefin, etc. are mentioned, for example.

From the viewpoint of spinnability and strength characteristics, polypropylene-based resins are particularly preferably used.

Regarding the polyolefin-based resin used in the present invention, the ratio of the homopolymer of propylene is preferably 60% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more. By setting it as the said range, favorable spinnability can be maintained, and intensity|strength can be improved.

As the polyolefin-based resin used in the present invention, a mixture of two or more kinds may be used, and a resin composition containing other olefin-based resins, thermoplastic elastomers, and the like may also be used.

Moreover, it can also be used as a composite fiber in which the above-mentioned polyolefin resin is combined. Examples of the composite form of the composite fiber include a concentric core-sheath type, an eccentric core-sheath type, and a sea-island type. Among them, from the viewpoint of being excellent in spinnability and being able to uniformly bond fibers to each other by thermal bonding, a preferred aspect is a composite form of a concentric core-sheath type.

In the polyolefin resin used in the present invention, within the scope of not impairing the effect of the present invention, commonly used antioxidants, weather-resistant stabilizers, light-resistant stabilizers, antistatic agents, antifogging agents, anti-staining agents can be added as required. Additives such as antiblocking agents, slip agents, nucleating agents and pigments, or other polymers.

The melting point of the polyolefin resin used in the present invention is preferably 80 to 200°C, more preferably 100 to 180°C, and further preferably 120 to 180°C. By setting the melting point to preferably be 80°C or higher, more preferably 100°C or higher, and further preferably 120°C or higher, it becomes easy to obtain heat resistance that can withstand practical use. In addition, by making the melting point preferably 200° C. or lower, more preferably 180° C. or lower, it becomes easy to cool the yarn discharged from the spinning nozzle, suppresses fusion of fibers, and facilitates stable spinning. .

The melt flow rate (hereinafter, sometimes referred to as MFR) of the polyolefin resin as the raw material of the spunbond nonwoven fabric of the present invention is preferably 155 to 850 g/10 minutes, more preferably 155 to 600 g/10 minutes, still more preferably It is 155~400g/10 minutes.

The MFR of this polyolefin resin adopts the value measured by ASTM D1238 (A method).

In addition, according to this standard, for example, polypropylene type is prescribed under load: 2.16 kg, temperature: 230°C, and polyethylene type is prescribed under load: 2.16 kg, temperature: 190°C.

Of course, it is also possible to adjust the MFR of the polyolefin-based resin by blending two or more types of resins having different MFRs in an arbitrary ratio. At this time, the MFR of the resin blended with the main polyolefin-based resin is preferably 10 to 1000 g/10 minutes, more preferably 20 to 800 g/10 minutes, and still more preferably 30 to 600 g/10 minutes. By setting it as the said range, the nonuniformity of viscosity and the nonuniformity of fineness, or the deterioration of spinnability can be prevented from partially generating in the polyolefin resin to be blended.

In addition, in order to prevent the occurrence of partial viscosity unevenness during the spinning of fibers, the fineness of the fibers is made uniform, and the fiber diameter is further reduced as described later. The resin used is also considered to be decomposed to adjust the MFR. However, for example, it is preferable not to add a free radical agent such as a peroxide, especially a dialkyl peroxide or the like. When this method is used, in addition to the unevenness of the viscosity and the unevenness of the fineness, it becomes difficult to sufficiently thin the fiber diameter, and the spinnability is also deteriorated due to the unevenness of the viscosity or the bubbles caused by the decomposed gas. Happening.

In the spunbond nonwoven fabric of the present invention, in order to improve the sliding property and the softness, a preferable aspect is that the polyolefin-based fiber corresponding to the polyolefin-based resin constituting the fiber contains a fatty acid having a carbon number of 23 to 50. amide compounds.

By making the carbon number of the fatty acid amide compound mixed in the polyolefin resin preferably 23 or more, more preferably 30 or more, the fatty acid amide compound can be suppressed from being excessively exposed on the fiber surface, and the spinnability and processing can be achieved. Those with excellent stability maintain high productivity. On the other hand, by making the carbon number of the fatty acid amide compound preferably 50 or less, more preferably 42 or less, the fatty acid amide compound can easily move to the surface of the fiber, and the slidability and flexibility can be imparted to the spinning Sticky nonwoven.

Examples of fatty acid amide compounds having 23 to 50 carbon atoms used in the present invention include saturated fatty acid monoamide compounds, saturated fatty acid diamide compounds, unsaturated fatty acid monoamide compounds, and unsaturated fatty acid diamide compounds. compounds, etc.

Specifically, examples of the fatty acid amide compound having 23 to 50 carbon atoms include behenic acid amide, hexadecanoic acid amide, octacosanoic acid amide, tetracosenoic acid amide, Docosapentaenoic acid amide, docosahexaenoic acid amide, ethylene bis-laurate, methylene bis-laurate, ethylene bis-stearate, ethylene ethylene Ethyl bis-hydroxystearic acid amide, ethylene bis-docosamide, hexamethylene bis-docosamide, hexamethylene bis-docosamide, hexamethylene hydroxy stearate Amide, Amide Distearyl Adipate, Amide Distearyl Sebacate, Amide Ethylene Dioleate, Amide Ethylene Dioleate, Ammonium Ethylene Dioleate and Hexamethylene Dioleate Amines, etc., these can also be used in combination in plural.

In the present invention, among these fatty acid amide compounds, ethylene bisstearic acid amide, which is a saturated fatty acid diamide compound, is particularly preferably used. Ethyl ethylene bisstearate can be melt-spun due to its excellent thermal stability, and high productivity can be obtained by including a fiber containing a polyolefin-based resin blended with this ethyl bis-stearate. , and spunbond non-woven fabric with excellent sliding and softness.

In the present invention, a preferable aspect is that the addition amount of the fatty acid amide compound is 0.01 to 5.0 mass % with respect to the fiber containing the polyolefin-based resin. By setting the addition amount of the fatty acid amide compound to preferably 0.01 to 5.0 mass %, more preferably to 0.1 to 3.0 mass %, and further preferably to 0.1 to 1.0 mass %, spinnability can be maintained and moderate Sliding and softness.

The addition amount here means the mass percentage of the fatty acid amide compound added with respect to the whole polyolefin resin which comprises the spunbond nonwoven fabric of this invention. For example, even when the fatty acid amide compound is added only to the sheath component constituting the core-sheath type conjugate fiber, the addition ratio with respect to the total amount of the core-sheath component is calculated.

As a method of measuring the addition amount of the fatty acid amide compound with respect to the fiber containing the polyolefin resin, for example, solvent extraction of the additive from the fiber, liquid chromatography mass spectrometry (LS/MS), etc. can be mentioned. Methods of quantitative analysis. At this time, the extraction solvent is appropriately selected according to the type of the fatty acid amide compound, for example, in the case of ethylene bisstearic acid amide, a method of using a chloroform-methanol mixed solution can be mentioned as an example.

[Fiber Containing Polyolefin-Based Resin]

It is important that the fibers constituting the spunbond nonwoven fabric of the present invention have an average single fiber diameter of 6.5 to 11.9 μm. By setting the average single fiber diameter to be 6.5 μm or more, preferably 7.5 μm or more, and more preferably 8.4 μm or more, a decrease in spinnability can be prevented, and a good quality spunbond nonwoven fabric can be stably produced. On the other hand, by setting the average single fiber diameter to be 11.9 μm or less, preferably 11.2 μm or less, and more preferably 10.6 μm or less, flexibility can be improved and a spunbond nonwoven fabric with high uniformity can be obtained.

In addition, in this invention, the average single fiber diameter (micrometer) of the fiber which comprises the said spunbond nonwoven fabric uses the value calculated by the following procedure.

(1) Polyolefin-based resin is melt-spun, drawn and stretched by an ejector, and then a nonwoven web (web) is collected on a net.

(2) 10 small samples (100×100 mm) were randomly collected.

(3) A photograph of the surface at a magnification of 500 to 1000 is taken with a microscope, and the width of 10 polyolefin fibers in total from 10 of each sample is measured.

(4) From the average value of 100 measured values, the average single fiber diameter (μm) was calculated.

The CV value of the single fiber diameter of the fibers constituting the spunbond nonwoven fabric of the present invention is preferably 7% or less. By making the CV value of the single fiber diameter preferably 7% or less, more preferably 6% or less, and further preferably 5% or less, it is possible to prevent roughness on the surface and to produce a spunbond nonwoven fabric with high uniformity. . The CV value of the single fiber diameter is mainly affected by the back pressure of the spinneret, the yarn cooling conditions, and the uniformity of the stretching conditions, and can be controlled by appropriately adjusting these.

[Spunbond Nonwoven]

It is important that the spunbond nonwoven fabric of the present invention has a fiber dispersion of 10 or less in terms of reflected light brightness. According to the fiber dispersion degree of reflected light brightness, it is an index indicating the degree of fiber dispersion when the spunbond nonwoven fabric is divided into a 0.1 × 0.1 inch grid to identify the fiber dispersion degree. The smaller the fiber dispersion degree, the more uniform the fibers are. of non-woven fabrics. By setting the fiber dispersion according to the brightness of reflected light to 10 or less, preferably 9.5 or less, and more preferably 9 or less, the fibers can be sufficiently opened to make the texture uniform, and unevenness on the surface can be prevented, or Deviations from physical properties. In addition, even in the ultrasonic bonding generally used in the manufacturing process of disposable diapers and the like, partial bonding failure or excessive bonding does not occur, and stable and uniform bonding is possible. The degree of fiber dispersion can be controlled by appropriately adjusting the melt flow rate of the spunbond nonwoven fabric and the average single fiber diameter of the fibers.

In addition, the fiber dispersion degree according to the reflected light brightness of the spunbonded nonwoven fabric of the present invention, more specifically, is a value measured by the following procedure.

(1) Stick the non-woven fabric on the black backing paper (AC Card black #350).

(2) Scan at 200dpi in full color to make a color scanned image of spunbond non-woven fabric and save it in JPG format.

(3) Cut out a 6×6 inch (1200×1200 pixel) image from the scanned image.

(4) Divide into grid units of 0.1×0.1 inches (20×20 pixels).

(5) In each grid, the average value (average luminance) of luminance defined in the YUV color space is calculated for each pixel using the following formula, and the standard deviation of the average luminance is obtained.

‧(Brightness of each pixel)=0.29891×R+0.58661×G+0.11448×B

Here, R, G, and B each represent the luminance of red, green, and blue in the RGB color mode.

(6) Three points per 1 m are carried out at equal intervals in the width direction of the spunbond nonwoven fabric, the average value of the standard deviation of each point is obtained, and the second decimal place is rounded off to obtain the fiber dispersion degree.

It is important for the spunbonded nonwoven fabric of the present invention that the surface roughness SMD of at least one side according to the KES method is 1.0 to 2.6 μm. By setting the surface roughness SMD according to the KES method to 1.0 μm or more, preferably 1.3 μm or more, more preferably 1.6 μm or more, and still more preferably 2.0 μm or more, it is possible to prevent the spunbonded nonwoven from becoming excessively thick. Densification and poor hand feel, or softness is impaired. On the other hand, by setting the surface roughness SMD according to the KES method to 2.6 μm or less, preferably 2.5 μm or less, more preferably 2.4 μm or less, and still more preferably 2.3 μm or less, the surface can be made smooth. Spunbond non-woven fabric with less roughness and excellent skin touch. The surface roughness SMD according to the KES method can be controlled by appropriately adjusting the average single fiber diameter or the CV value of the single fiber diameter, the degree of fiber dispersion, and the like.

In addition, in the present invention, the surface roughness SMD according to the KES method adopts the value measured as follows.

(1) Three test pieces with a width of 200 mm × 200 mm were collected from the spunbond nonwoven fabric at equal intervals in the width direction of the spunbond nonwoven fabric.

(2) The test piece is set on the sample table.

0.5mm鋼琴線，接觸長度：5mm)，掃描試驗片之表面，測定表面的凹凸形狀之平均偏差。 (3) A contact tip for surface roughness measurement (material:

0.5mm piano wire, contact length: 5mm), scan the surface of the test piece, and measure the average deviation of the uneven shape of the surface.

(4) The above-mentioned measurement is carried out in the longitudinal direction (longitudinal direction of the non-woven fabric) and the transverse direction (the width direction of the non-woven fabric) of all the test pieces, the average deviation of the total of 6 points is averaged, and the second decimal place is calculated as It is rounded up as the surface roughness SMD (μm).

The average friction coefficient MIU according to the KES method of at least one side of the spunbond nonwoven fabric of the present invention is preferably 0.1 to 0.5. By making the average friction coefficient MIU preferably 0.5 or less, more preferably 0.45 or less, and further preferably 0.4 or less, the slidability of the surface of the nonwoven fabric can be improved, and a spunbond nonwoven fabric with better skin feel can be produced. On the other hand, by making the average friction coefficient MIU preferably 0.1 or more, more preferably 0.15 or more, and still more preferably 0.2 or more, it is possible to prevent the spinnability from being deteriorated due to excessive addition of the slip agent, or When the yarn is captured on the mesh, the yarn slips and the texture becomes poor. The average friction coefficient MIU according to the KES method can be controlled by adjusting the average single fiber diameter, fiber dispersion, etc., or by adding a slip agent to the polyolefin-based resin.

The variation MMD of the average friction coefficient according to the KES method of at least one side of the spunbond nonwoven fabric of the present invention is preferably 0.002 to 0.008. By making the variation MMD of the average friction coefficient preferably 0.008 or less, more preferably 0.0077 or less, and still more preferably 0.0075 or less, the surface roughness of the spunbond nonwoven fabric can be further reduced. On the other hand, by making the variation MMD of the average friction coefficient preferably 0.002 or more, more preferably 0.004 or more, and still more preferably 0.005 or more, it is possible to prevent the production facility from being complicated or the productivity from being extremely lowered. The variation MMD of the average friction coefficient according to the KES method can be controlled by adjusting the average single fiber diameter or the CV value of the single fiber diameter, fiber dispersion, etc., or by adding a slip agent to the polyolefin resin.

In the present invention, the average friction coefficient MIU and the variation MMD of the average friction coefficient according to the KES method are the values measured as follows.

(1) Three test pieces with a width of 200 mm×200 mm were collected from the spunbond nonwoven fabric at equal intervals in the width direction of the spunbond nonwoven fabric.

(2) The test piece is set on the sample table.

0.5mm鋼琴線(20條並列)，接觸面積：1cm²)，掃描試驗片之表面，測定平均摩擦係數。 (3) Contact the friction head with a load of 50gf (material:

0.5 mm piano wire (20 parallel), contact area: 1 cm ² ), scan the surface of the test piece, and measure the average friction coefficient.

(4) The above-mentioned measurement was carried out in the longitudinal direction (longitudinal direction of the non-woven fabric) and the transverse direction (the width direction of the non-woven fabric) of all the test pieces, the average deviation of the total of 6 points was averaged, and the fourth decimal place was calculated as Rounded to the nearest whole number and regarded as the average friction coefficient MIU. In addition, the fluctuation of the average friction coefficient of the above-mentioned 6 points in total was further averaged, and the fourth place below the decimal point was rounded to the nearest 5, and it was regarded as the fluctuation MMD of the average friction coefficient.

Moreover, in the present invention, the texture of the spunbond nonwoven fabric was evaluated by a sensory test.

The MFR of the spunbond nonwoven fabric of the present invention is preferably 155-850 g/10 minutes. By setting the MFR to preferably 155 to 850 g/10 minutes, more preferably to 155 to 600 g/10 minutes, and still more preferably to be 155 to 400 g/10 minutes, the thinning behavior during fiber extension is stabilized, even if In order to improve productivity, it can be spun at a fast spinning speed, and stable spinning is also possible. In addition, by stabilizing the thinning behavior, the yarn backlash is suppressed, and unevenness at the time of capturing into a sheet becomes less likely to occur. Furthermore, since the drawing can be performed stably at a fast spinning speed, the orientation and crystallization of the fibers can be performed, and fibers having high mechanical strength can be obtained.

The melt flow rate (MFR) of the spunbonded nonwoven fabric of the present invention is the value measured by ASTM D1238 (method A).

In addition, according to this standard, for example, polypropylene type is prescribed under load: 2.16 kg, temperature: 230°C, and polyethylene type is prescribed under load: 2.16 kg, temperature: 190°C.

The weight per unit area of the spunbond nonwoven fabric of the present invention is preferably 10 to 100 g/m ² . By making the basis weight preferably 10 g/m ² or more, more preferably 13 g/m ² or more, and still more preferably 15 g/m ² or more, a spunbond nonwoven fabric with practical mechanical strength can be obtained. On the other hand, by setting the weight per unit area to preferably 100 g/m ² or less, more preferably 50 g/m ² or less, and still more preferably 30 g/m ² or less, it is possible to make it suitable for use as a sanitary material. The non-woven fabric used is a moderately soft spunbond non-woven fabric.

In addition, in this invention, the basis weight of a spunbond nonwoven fabric is based on "6.2 mass per unit area" of JIS L1913 (2010), and the value measured by the following procedure is used.

(1) Collect 3 test pieces of 20cm×25cm for every 1m of the width of the sample.

(2) Weigh the respective mass (g) in the standard state.

(3) The average value is expressed in terms of mass per 1 m ² (g/m ² ).

The thickness of the spunbond nonwoven fabric of the present invention is preferably 0.05 to 1.5 mm. By setting the thickness to preferably 0.05~1.5mm, more preferably 0.08~1.0mm, and further preferably 0.10~0.8mm, it has softness and moderate cushioning, and can be used as a spunbond for sanitary materials Non-woven fabrics, especially spunbond non-woven fabrics suitable for use in disposable diapers.

In addition, in this invention, the thickness (mm) of a spunbond nonwoven fabric is based on "5.1" of JIS L1906 (2000), and the value measured by the following procedure is employ|adopted.

(1) Using a pressure head having a diameter of 10 mm, under a load of 10 kPa, the thickness was measured at ten points per 1 m at equal intervals in the width direction of the nonwoven fabric in units of 0.01 mm.

(2) Round off the average of the above ten points to the third place below the decimal point.

In addition, the apparent density of the spunbond nonwoven fabric of the present invention is preferably 0.05 to 0.3 g/cm ³ . By setting the apparent density to preferably 0.3 g/cm ³ or less, more preferably 0.25 g/cm ³ or less, and still more preferably 0.20 g/cm ³ or less, it is possible to prevent the fibers from being densely packed and impair the spunbond. The softness of non-woven fabrics.

On the other hand, by making the apparent density preferably 0.05 g/cm ³ or more, more preferably 0.08 g/cm ³ or more, and still more preferably 0.10 g/cm ³ or more, fuzzing and interlayer peeling can be suppressed When this happens, a spunbond nonwoven fabric with durable and practical strength and handleability is produced.

In addition, in the present invention, the apparent density (g/cm ³ ) is calculated based on the following formula from the above-mentioned basis weight and thickness before rounding, and rounds off the third decimal place.

• Apparent density (g/cm ³ )=[weight per unit area (g/m ² )]/[thickness (mm)]×10 ^-3 .

The stiffness of the spunbond nonwoven fabric of the present invention is preferably 70 mm or less. By setting the stiffness to preferably 70 mm or less, more preferably 67 mm or less, and further preferably 64 mm or less, as a spunbond nonwoven fabric for hygiene materials, it is possible to obtain moderate softness especially suitable for use in disposable diapers. . Further, when the stiffness is extremely low, the handleability may be poor, so the stiffness is preferably 10 mm or more. Stiffness can be adjusted by basis weight, single fiber diameter, and thermocompression bonding conditions (compression bonding ratio, temperature, linear pressure, etc.).

The average bending rigidity B according to the KES method of the spunbond nonwoven fabric of the present invention is preferably 0.001 to 0.02 gf·cm ² /cm. By setting the average bending rigidity B according to the KES method to preferably 0.02 gf·cm ² /cm or less, more preferably 0.017 gf·cm ² /cm or less, still more preferably 0.015 gf·cm ² /cm or less , especially when used as a spunbond non-woven fabric for sanitary materials, sufficient softness can be obtained. Further, when the average bending rigidity B according to the KES method is extremely low, the handleability may be poor, so the average bending rigidity B is preferably 0.001 gf·cm ² /cm or more. The average bending rigidity B according to the KES method can be adjusted by basis weight, single fiber diameter, and thermocompression bonding conditions (compression bonding ratio, temperature, linear pressure, etc.).

The stress at 5% elongation per unit area weight of the spunbond nonwoven fabric of the present invention (hereinafter, sometimes described as 5% modulus per unit area weight) is preferably 0.06 to 0.33 (N/25mm)/(g/m ² ), more preferably 0.13-0.30(N/25mm)/(g/m ² ), further preferably 0.20-0.27(N/25mm)/(g/m ² ). By setting it as the said range, the spunbond nonwoven fabric which maintains practical strength, and is soft and excellent in touch can be produced.

In addition, in the present invention, the stress at 5% elongation per unit area weight of the spunbond nonwoven fabric is based on "6.3 Tensile strength and elongation (ISO method)" of JIS L1913 (2010), and is adopted by the following The value determined by the program.

(1) For each of the longitudinal direction (the longitudinal direction of the non-woven fabric) and the transverse direction (the width direction of the non-woven fabric), three test pieces of 25 mm×300 mm were collected every 1 m in width.

(2) The test piece was installed in the tensile tester with a gap of 200 mm between the jigs.

(3) A tensile test was carried out at a tensile speed of 100 mm/min, and the stress (5% modulus) at 5% elongation was measured.

(4) Calculate the average value of the 5% modulus in the longitudinal and transverse directions measured for each test piece, calculate the 5% modulus per unit area based on the following formula, and round off to the third decimal place.

‧5% modulus of weight per unit area ((N/25mm)/(g/m ² ))=[average value of 5% modulus (N/25mm)]/weight per unit area (g/m ² ).

[Manufacturing method of spunbond nonwoven]

Next, a preferred aspect of the method for producing the spunbond nonwoven fabric of the present invention will be specifically described.

The spunbond nonwoven fabric of the present invention is a long fiber nonwoven fabric produced by the spunbond method. The method for producing the nonwoven fabric is not particularly limited, and examples thereof include a spunbond method, a flash spinning method, a wet method, a card method, an air-laid method, and the like. . In particular, in addition to being excellent in productivity and mechanical strength, the spunbond method can also suppress fuzzing and fiber shedding that are easily caused in short-fiber nonwoven fabrics. In addition, by laminating the captured spunbond nonwoven web or thermocompression bonded spunbond nonwoven fabric (all marked as S) with SS, SSS and SSSS, the productivity and texture uniformity are improved, Therefore, it is a better form.

In the spunbond method, the molten thermoplastic resin is first spun out from the spinning nozzle as long fibers, and after being sucked and stretched by an ejector with compressed air, the fibers are collected on a moving mesh. Nonwoven web. Further, heat-bonding treatment is applied to the obtained nonwoven fiber web to obtain a spunbond nonwoven fabric.

The shape of the spinneret or the injector is not particularly limited, and various shapes such as a circle or a rectangle can be used, for example. Among them, the use of compressed air is relatively small, the energy cost is excellent, the yarns are not easily welded and rubbed together, and the yarns are easy to open, and a combination of a rectangular spinning nozzle and a rectangular jet is preferred.

In the present invention, the polyolefin-based resin is melted and measured in an extruder, supplied to a spinning nozzle, and spun out as a long fiber. The spinning temperature at the time of melting and spinning the polyolefin resin is preferably 200 to 270°C, more preferably 210 to 260°C, and further preferably 220 to 250°C. By setting the spinning temperature within the above-mentioned range, a stable molten state can be obtained, and excellent spinning stability can be obtained.

The back pressure of the spinning nozzle is preferably set to 0.1-6.0 MPa. By making the back pressure preferably 0.1 to 6.0 MPa, more preferably 0.3 to 6.0 MPa, and still more preferably 0.5 to 6.0 MPa, it is possible to prevent the occurrence of fiber diameter deviation due to deterioration of discharge uniformity, or to increase the Pressure resistance and larger size of the spinning nozzle. The back pressure of the spinneret can be adjusted by the discharge aperture or depth of the spinneret, and the spinning temperature, among which the contribution of the discharge aperture is large.

The spun filament yarn is then cooled. As a method of cooling the spun yarn, for example, a method of forcibly blowing cold air to the yarn, a method of natural cooling at the ambient temperature of the yarn around the yarn, and adjustment of the spinning nozzle and jet The method of the distance between the devices, etc., or a method of combining these methods can be used. In addition, the cooling conditions can be appropriately adjusted and adopted in consideration of the discharge rate per single hole of the spinning nozzle, the spinning temperature, the gas ambient temperature, and the like.

Then, the cooled and solidified yarn is drawn and extended by 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, still more preferably 4,500 to 6,500 m/min. By setting the spinning speed to 3,500 to 6,500 m/min, high productivity is achieved, and the orientation and crystallization of the fibers are advanced, and high-strength long fibers can be obtained. Generally, if the spinning speed is increased, the spinnability deteriorates and the yarn cannot be stably produced. However, as described above, by using a polyolefin-based resin having an MFR in a specific range, the intended polyolefin fiber can be spun stably. Silk.

Next, the obtained long fibers are collected on a moving web to obtain a nonwoven web.

In the present invention, it is also preferable that the nonwoven web is temporarily attached to the web by abutting the hot flat roll from one side thereof. By doing so, it is possible to prevent the surface layer of the nonwoven web from curling or fluttering during conveyance on the web and to prevent the texture from deteriorating, and to improve the conveyability from the yarn replenishment to the thermocompression bonding.

Next, by thermally bonding the obtained nonwoven web, the intended spunbond nonwoven fabric can be obtained.

The method for thermally bonding the nonwoven web is not particularly limited. For example, a pair of upper and lower thermal embossing rolls having engravings (concavities and convexities) on the roll surface, including one roll with a flat surface ( Various types of rolls, such as a combination of a smooth) roll and another roll with engraving (concave and convex) on the surface of the roll, and a combination of a pair of upper and lower flat (smooth) rolls and a hot calender roll. A method of performing thermal bonding, or a method of ultrasonic bonding in which heat is welded by ultrasonic vibration of a horn.

Among them, from the viewpoint of being excellent in productivity, being able to impart strength to a part of the thermally bonded part, and to maintain the hand and skin feel of a non-woven fabric in the non-bonded part, it is preferable to use a pair of upper and lower pairs on the surface of the roll, respectively. A thermal embossing roll to which engravings (concavities and convexities) are applied, or a thermal embossing roll comprising a combination of a roll having a flat (smooth) roll surface and another roll having engravings (concavities and convexities) applied to the roll surface.

As the surface material of the thermal embossing roll, in order to obtain a sufficient thermal pressure bonding effect and prevent the engraving (concave and convex portion) of one embossing roll from being transferred to the surface of the other roll, a metal roll is preferably used. Pairs with metal rollers.

The area ratio of embossing using such a hot embossing roll is preferably 5 to 30%. By making the bonding area preferably 5% or more, more preferably 8% or more, and further preferably 10% or more, practical strength can be obtained as a spunbond nonwoven fabric. On the other hand, by making the bonding area preferably 30% or less, more preferably 25% or less, and still more preferably 20% or less, it is possible to obtain a spunbond nonwoven fabric for sanitary materials, which is particularly suitable for disposable diapers. Moderate softness for use. Even when ultrasonic bonding is used, the bonding area ratio is preferably within the same range.

The so-called bonding area here refers to the proportion of the bonding portion in the entire spunbond nonwoven fabric. Specifically, when thermal bonding is performed by a pair of rolls having concavo-convex, it means that the portion (bonded portion) where the convex portion of the upper roll and the convex portion of the lower roll overlap and abut against the nonwoven web is spunbonded. The proportion of non-woven fabric as a whole. In addition, when thermal bonding is performed by a roll having unevenness and a flat roll, it refers to the proportion of the portion (bonding portion) where the convex portion of the roll having unevenness abuts on the nonwoven web in the entire spunbond nonwoven fabric. In addition, when ultrasonic bonding is performed, it refers to the proportion of the portion (bonded portion) thermally welded by ultrasonic processing in the entire spunbond nonwoven fabric.

The shape of the bonding portion formed by hot embossing rolls or ultrasonic bonding is not particularly limited, for example, circle, ellipse, square, rectangle, parallelogram, rhombus, regular hexagon and regular octagon can be used. Moreover, it is preferable that the adhesive portion is uniformly present at predetermined intervals in each of the longitudinal direction (conveying direction) and the width direction of the spunbonded nonwoven fabric. By doing so, the variation in strength of the spunbond nonwoven fabric can be reduced.

The surface temperature of the heat embossing roll at the time of thermal bonding is preferably -50 to -15° C. with respect to the melting point of the polyolefin-based resin used. By setting the surface temperature of the heat roller to preferably -50°C or higher, more preferably -45°C or higher with respect to the melting point of the polyolefin resin, it is possible to moderately thermally bond and obtain practical strength. of spunbond nonwovens. Moreover, by setting the surface temperature of the thermal embossing roll to preferably -15°C or lower, more preferably -20°C or lower with respect to the melting point of the polyolefin-based resin, excessive thermal bonding can be suppressed, and as a hygienic The spunbond non-woven fabric used as the material can obtain moderate softness especially suitable for the use of disposable diapers.

The linear pressure of the hot embossing roll during thermal bonding is preferably 50 to 500 N/cm. By setting the linear pressure of the roller to be preferably 50 N/cm or more, more preferably 100 N/cm or more, and still more preferably 150 N/cm or more, it is possible to moderately thermally bond, and to obtain a spinning of practical strength. Sticky nonwoven. On the other hand, by setting the linear pressure of the hot embossing roll to preferably 500 N/cm or less, more preferably 400 N/cm or less, and further preferably 300 N/cm or less, it is used as a spunbond nonwoven fabric for sanitary materials. , can obtain moderate softness especially suitable for the use of disposable diapers.

In addition, in the present invention, for the purpose of adjusting the thickness of the spunbond nonwoven fabric, before and/or after the thermal bonding with the above-mentioned thermal embossing rolls, a thermal calendering roll including a pair of upper and lower flat rolls can be used. Apply thermocompression. The upper and lower pair of flat rolls are metal rolls or elastic rolls with no unevenness on the surface of the rolls. Metal rolls and metal rolls can be used in pairs, or metal rolls and elastic rolls can be used in pairs.

In addition, the elastic roll referred to here includes a roll made of a material more elastic than a metal roll. Examples of the elastic roll include so-called paper rolls such as paper, cotton, and polyaramide paper, and those containing urethane-based resins, epoxy-based resins, silicone-based resins, and polyester-based resins. And hard rubber, and resin rolls of these mixtures, etc.

[Example]

Next, the spunbond nonwoven fabric of the present invention will be specifically described based on examples. In addition, in the measurement of each physical property, there is no specific description that the measurement is based on the aforementioned method.

(1) Melt flow rate (MFR) of polyolefin resin (g/10 minutes):

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-mentioned average single fiber diameter and the solid density of the polyolefin-based resin used, the mass per 10,000 m of length was regarded as the average single fiber fineness (dtex), and the value was calculated by rounding off to the second decimal place. The spinning speed was calculated based on the following formula from the average single fiber fineness and the resin discharge rate (hereinafter referred to as single hole discharge rate) (g/min) from the spinning nozzle set under each condition.

‧Spinning speed (m/min)=(10000×[single hole output (g/min)])/[average single fiber fineness (dtex)].

(3) Fiber dispersion of spunbond nonwovens according to reflected light brightness:

In the measurement of the fiber dispersion degree according to the reflected light brightness of the spunbond nonwoven fabric, a color laminator "DocuCentre-VI C4471 PFS" (Fuji Xerox Co., Ltd.) was used for the image scanning.

(4) Surface roughness SMD (μm) of spunbond non-woven fabric according to KES method:

In the measurement, an automatic surface tester "KES-FB4-AUTO-A" manufactured by KATO TECH Co., Ltd. was used. The surface roughness SMD is measured on both sides of the spunbond nonwoven fabric, and Table 1 describes the smaller value among these.

(5) The average friction coefficient MIU of the spunbond non-woven fabric according to the KES method, and the change of the average friction coefficient of the spunbond non-woven fabric according to the KES method MMD:

In the measurement, an automatic surface tester "KES-FB4-AUTO-A" manufactured by KATO TECH Co., Ltd. was used. The average friction coefficient MIU is measured on both sides of the spunbond nonwoven fabric, and Table 1 describes the smaller value among these.

(6) Melt flow rate (MFR) of spunbond non-woven fabric (g/10min):

The melt flow rate of the spunbond nonwoven fabric was determined according to ASTM D1238 under the conditions of a load of 2160 g and a temperature of 230°C.

(7) The feel of spunbond nonwovens

A sample with a size of 100 mm×100 mm was collected, and 20 panellists touched the nonwoven fabric, and each evaluated the hand of the spunbond nonwoven fabric according to the following 5-level criteria. Next, the judgment points of each sensory inspector were totaled, and the spunbonded nonwoven fabric was regarded as the hand feeling, and 80 points or more were regarded as pass. The feel is preferably 85 points or more, more preferably 90 points or more.

5 points: very good (feeling of comfort with excellent cushioning and softness)

4 points: good (between 5 points and 3 points)

3 points: Normal (feel cushioning, softness)

2 points: difference (between 3 points and 1 point)

1 point: very poor (at least one of cushioning and softness is felt to be lacking)

(Example 1)

為0.30mm、孔深度為2mm之矩形紡嘴，在紡絲溫度為235℃、單孔吐出量為0.32g/分鐘下紡出。將所紡出的紗線冷卻固化後，將其在矩形噴射器中，藉由將噴射器壓力設為0.35MPa的壓縮空氣而進行牽引、延伸，捕集在移動的網狀物上。藉此，形成由聚丙烯長纖維所構成之不織纖維網。另外，構成所形成的紡黏不織纖維網之纖維的特性，係平均單纖維直徑為10.1μm，由此所換算的紡絲速度為4,411m/分鐘。關於紡絲性，在1小時的紡絲中未看見斷線而為良好。 A polypropylene resin composed of a homopolymer having a melt flow rate (MFR) of 200 g/10 minutes and a melting point of 163° C. was melted in an extruder, and the diameter of the

A rectangular spinning nozzle with a hole depth of 0.30 mm and a hole depth of 2 mm was spun 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 drawn and stretched in a rectangular jet with compressed air whose jet pressure was 0.35 MPa, and was collected on a moving web. Thereby, a nonwoven web composed of polypropylene long fibers was formed. In addition, the characteristics of the fibers constituting the formed spunbond nonwoven web were that the average single fiber diameter was 10.1 μm, and the spinning speed converted from this was 4,411 m/min. With regard to spinnability, no thread breakage was observed during 1 hour of spinning, and it was good.

Next, the formed spunbond nonwoven web was subjected to the following conditions of a pair of upper and lower thermal embossing rolls consisting of the following upper and lower rolls, under the conditions of linear pressure: 300 N/cm, and thermal bonding temperature: 130°C After heating, a spunbond nonwoven fabric with a weight per unit area of 18 g/m ² was obtained.

(Top roller): Embossing roller made of metal and engraved with a water drop pattern with an area ratio of 16%

(Lower roll): Metal flat roll

Table 1 shows the results of the evaluation of the obtained spunbond nonwoven fabrics.

(Example 2)

A spunbond nonwoven fabric was obtained by the same method as in Example 1, except that the polypropylene resin composed of homopolymer was made into one with MFR of 155g/10min and melting point of 163°C, and the pressure of the ejector was set to 0.20MPa. . In addition, the characteristics of the fibers constituting the formed spunbond nonwoven web were that the average single fiber diameter was 11.8 μm, and the spinning speed converted from this was 3,216 m/min. With regard to spinnability, no thread breakage was observed during 1 hour of spinning, and it was good. Table 1 shows the results of the evaluation of the obtained spunbond nonwoven fabrics.

(Example 3)

A spunbond nonwoven fabric was obtained by the same method as in Example 1, except that the polypropylene resin composed of the homopolymer was made into one having an MFR of 800 g/10 minutes and a melting point of 163°C. In addition, the characteristics of the fibers constituting the formed spunbond nonwoven web were that the average single fiber diameter was 8.4 μm, and the spinning speed converted from this was 6,422 m/min. With regard to spinnability, no thread breakage was observed during 1 hour of spinning, and it was good. Table 1 shows the results of the evaluation of the obtained spunbond nonwoven fabrics.

(Example 4)

Spinning was obtained in the same manner as in Example 1, except that the polypropylene resin composed of a homopolymer had an MFR of 800 g/10 min, a melting point of 163° C., and a single-hole discharge rate of 0.21 g/min. Sticky nonwoven. In addition, the characteristics of the fibers constituting the formed spunbond nonwoven web were that the average single fiber diameter was 7.2 μm, and the spinning speed converted from this was 5,668 m/min. With regard to spinnability, no thread breakage was observed during 1 hour of spinning, and it was good. Table 1 shows the results of evaluation for the obtained spunbond nonwoven fabric.

(Example 5)

A spunbond nonwoven fabric was obtained by the same method as in Example 1, except that the polypropylene resin composed of the homopolymer had an MFR of 155 g/10 minutes and the pressure of the ejector was set to 0.38 MPa. In addition, the characteristics of the fibers constituting the formed spunbond nonwoven web were that the average single fiber diameter was 10.1 μm, and the spinning speed converted from this was 4,393 m/min. With regard to spinnability, no thread breakage was observed during 1 hour of spinning, and it was good. Table 1 shows the results of the evaluation of the obtained spunbond nonwoven fabrics.

(Example 6)

A spunbond was obtained in the same manner as in Example 1, except that 1.0% by mass of ethylidene bisstearate amide was used as the fatty acid amide compound in the polypropylene resin composed of the homopolymer Not woven. In addition, the characteristics of the fibers constituting the formed spunbond nonwoven web were that the average single fiber diameter was 10.1 μm, and the spinning speed converted from this was 4,352 m/min. With regard to spinnability, no thread breakage was observed during 1 hour of spinning, and it was good. Table 1 shows the results of the evaluation of the obtained spunbond nonwoven fabrics.

(Comparative Example 1)

Except that the polypropylene resin composed of the homopolymer was made into a MFR of 60 g/10 min and a melting point of 163° C., the discharge rate per hole was set to 0.43 g/min, and the pressure of the ejector was set to 0.15 MPa. In the same manner as in Example 1, a spunbond nonwoven fabric was obtained. The characteristics of the fibers constituting the formed spunbond nonwoven web were that the average single fiber diameter was 14.0 μm, and the spinning speed converted from this was 3,070 m/min. With regard to spinnability, no thread breakage was observed during 1 hour of spinning, and it was good. In addition, when the ejector pressure was set to 0.35 MPa under the same conditions, thread breakage frequently occurred, and spinning was not possible. Table 1 shows the results of the evaluation of the obtained spunbond nonwoven fabrics. The obtained spunbond nonwoven has large average single fiber diameter and fiber dispersion, so the surface roughness SMD is also large.

(Comparative Example 2)

A spunbonded nonwoven fabric was obtained by the same method as in Example 1, except that the discharge rate per hole was set to 0.43 g/min and the pressure of the ejector was set to 0.30 MPa. The characteristics of the fibers constituting the formed spunbond nonwoven web were that the average single fiber diameter was 12.9 μm, and the spinning speed converted from this was 3,617 m/min. With regard to spinnability, no thread breakage was observed during 1 hour of spinning, and it was good. Table 1 shows the results of the evaluation of the obtained spunbond nonwoven fabrics. Although the obtained spunbond nonwoven fabric has a small fiber dispersion, the average single fiber diameter is large, so the surface roughness SMD is also large.

(Comparative Example 3)

為0.35mm、孔深度為7mm之矩形紡嘴，在紡絲溫度為255℃、單孔吐出量為0.56g/分鐘下紡出。將所紡出的紗 線冷卻固化後，將其在矩形噴射器中，藉由將噴射器壓力設為0.35MPa的壓縮空氣而進行牽引、延伸，捕集在移動的網狀物上。藉此，形成由聚丙烯長纖維所構成之不織纖維網。另外，構成所形成的紡黏不織纖維網之纖維的特性，係平均單纖維直徑為12.5μm，由此所換算的紡絲速度為5,015m/分鐘。關於紡絲性，在1小時的紡絲中斷線頻繁發生而為不良。 Referring to Example 1 of Japanese Patent Application Laid-Open No. 2013-159884, an attempt was made to obtain the spunbond nonwoven fabric of the present invention. A polypropylene resin with a melt flow rate (MFR) of 35 g/10 minutes was melted in an extruder, from the hole diameter

A rectangular spinning nozzle with a hole depth of 0.35 mm and a hole depth of 7 mm was spun at a spinning temperature of 255°C and a single hole discharge rate of 0.56 g/min. After the spun yarn was cooled and solidified, it was drawn and stretched in a rectangular jet with compressed air whose jet pressure was 0.35 MPa, and was collected on a moving web. Thereby, a nonwoven web composed of polypropylene long fibers was formed. In addition, the characteristics of the fibers constituting the formed spunbond nonwoven web were that the average single fiber diameter was 12.5 μm, and the spinning speed converted from this was 5,015 m/min. With regard to spinnability, yarn breakage occurred frequently within 1 hour of spinning, and it was unfavorable.

Next, the formed spunbond nonwoven web was subjected to the following conditions of a pair of upper and lower thermal embossing rolls consisting of the following upper and lower rolls, under the conditions of linear pressure: 300 N/cm, and thermal bonding temperature: 130°C After heating, a spunbond nonwoven fabric with a weight per unit area of 17 g/m ² was obtained.

(Top roller): Embossing roller made of metal and engraved with a water drop pattern with an area ratio of 6%

(Lower roll): Metal flat roll

About the obtained spunbond nonwoven fabric, the part which did not mix|blend a broken thread was selected and evaluated. The results are shown in Table 1. The obtained spunbond nonwoven has large average single fiber diameter and fiber dispersion, so the surface roughness SMD is also large.

(Comparative Example 4)

為0.60mm、孔深度為1.2mm之矩形紡嘴，在紡絲溫度為245℃、單孔吐出量為0.35g/分鐘下紡出。將所紡出的紗 線冷卻固化後，將其在密閉型的矩形噴射器中，藉由將噴射器壓力設為0.35MPa的壓縮空氣而進行牽引、延伸，捕集在移動的網狀物上。藉此，形成由聚丙烯長纖維所構成之不織纖維網。另外，構成所形成的紡黏不織纖維網之纖維的特性，係平均單纖維直徑為8.4μm，由此所換算的紡絲速度為6,980m/分鐘。關於紡絲性，在1小時的紡絲中斷線頻繁發生而為不良。 Referring to Example 5 of Japanese Patent Application Laid-Open No. 8-3853, an attempt was made to obtain the spunbond nonwoven fabric of the present invention. A polypropylene resin with a melt flow rate (MFR) of 70 g/10 min was melted in an extruder, from the hole diameter

A rectangular spinning nozzle with a diameter of 0.60 mm and a hole depth of 1.2 mm was spun at a spinning temperature of 245° C. and a single hole discharge rate of 0.35 g/min. After cooling and solidifying the spun yarn, it is drawn and stretched in a closed rectangular ejector with compressed air with an ejector pressure of 0.35 MPa, and collected on a moving web . Thereby, a nonwoven web composed of polypropylene long fibers was formed. In addition, the characteristics of the fibers constituting the formed spunbond nonwoven web were that the average single fiber diameter was 8.4 μm, and the spinning speed converted from this was 6,980 m/min. With regard to spinnability, yarn breakage occurred frequently within 1 hour of spinning, and it was unfavorable.

Next, the formed spunbond nonwoven web was subjected to the following conditions of a pair of upper and lower thermal embossing rolls consisting of the following upper and lower rolls, under the conditions of linear pressure: 300 N/cm, and thermal bonding temperature: 130°C After heating, a spunbond nonwoven fabric with a weight per unit area of 17 g/m ² was obtained.

(Upper roll): Embossing roll made of metal and engraved with a water drop pattern with an area ratio of 21%

(Lower roll): Metal flat roll

About the obtained spunbond nonwoven fabric, the part which did not mix|blend a broken thread was selected and evaluated. The results are shown in Table 1. Although the average single fiber diameter of the obtained spunbond nonwoven fabric is small, the fiber dispersion is large, so the surface roughness SMD is also large.

The average single fiber diameter of Examples 1 to 6 is 6.5 to 11.9 μm, the fiber dispersion according to the reflected light brightness is 10 or less, and the surface roughness SMD of the KES method is 1.0 to 2.6 μm. Spinning of Examples 1 to 6 Sticky non-woven fabric with uniform texture, smooth surface, excellent hand and skin feel, and high softness. In addition, as the average single fiber diameter becomes smaller, the average friction coefficient tends to increase, but the spunbond nonwoven fabric of Example 6 to which ethylene bisstearate is added has a lower average friction coefficient and a dry feeling. , Increased flexibility, especially suitable for use as sanitary materials.

On the other hand, spunbond nonwoven fabrics with large average single fiber diameter and fiber dispersion degree shown in Comparative Example 1 and Comparative Example 3 and large surface roughness SMD according to the KES method, and the average single fiber diameter shown in Comparative Example 2 The spunbond nonwoven fabric with large surface roughness SMD according to the KES method, and the spunbond nonwoven fabric with large fiber dispersion according to the reflected light brightness and large surface roughness SMD according to the KES method shown in Comparative Example 4, compared In the non-woven fabric of the present invention, the roughness is large, and the hand and skin feel are poor. In addition, the spunbond nonwoven fabrics using polypropylene resin having a relatively small MFR shown in Comparative Example 3 and Comparative Example 4 had poor spinnability at high spinning speeds and could not be stably produced.

Although the present invention has been described in detail using specific aspects, it is clear for those skilled in the art that various changes and modifications are possible without departing from the intent and scope of the present invention. In addition, this application is based on the Japanese Patent Application for Invention (Japanese Patent Application No. 2018-034867) filed on February 28, 2018 and the Japanese Patent Application for Invention (Japanese Patent Application No. 2018-141046) filed on July 27, 2018 , the entirety of which is cited by reference.

[Industrial Availability]

The spunbond nonwoven fabric of the present invention has high productivity, uniform texture, smooth surface, excellent hand and skin feel, and high softness, so it can be suitably used for sanitary materials such as disposable diapers or sanitary napkins. Among sanitary materials, it is especially suitable for the back sheet of paper diapers.

Claims (10)

A spunbond nonwoven fabric, which is a spunbond nonwoven fabric composed of fibers containing polyolefin resin, the average single fiber diameter of the fibers is 6.5~11.9 μm, and the fiber dispersion degree according to the reflected light brightness is 10 or less, at least one side The surface roughness SMD according to the KES method is 1.0-2.6 μm, and the apparent density is 0.05-0.3 g/cm ³ . For the spunbond nonwoven fabric of claim 1, the average friction coefficient MIU of at least one side according to the KES method is 0.1~0.5. For the spunbond nonwoven fabric of claim 1, the variation MMD of the average friction coefficient according to the KES method of at least one side is 0.008 or less. For the spunbond nonwoven fabric of claim 2, the variation MMD of the average friction coefficient according to the KES method of at least one side is 0.008 or less. The spunbond non-woven fabric according to any one of claims 1 to 4 has a melt flow rate of 155 to 850 g/10 minutes. The spunbonded nonwoven fabric according to any one of Claims 1 to 4, which is obtained by containing a fatty acid amide compound having a carbon number of 23 or more and 50 or less in a polyolefin-based resin. The spunbond nonwoven fabric according to claim 5 is obtained by adding a fatty acid amide compound having 23 to 50 carbon atoms in a polyolefin-based resin. The spunbond nonwoven fabric of claim 6, wherein the addition amount of the fatty acid amide compound is 0.01 to 5.0% by mass. The spunbond nonwoven fabric of claim 6, wherein the fatty acid amide compound is ethylene bisstearate. The spunbond nonwoven fabric according to any one of claims 1 to 4, which is formed of fibers containing polypropylene-based resin.