Spun-bonded nonwoven fabric, production method thereof, and holding tape and cable

Abstract

To provide a spun-bonded nonwoven fabric used for a holding tape, having a specific strength, being easily subjected to surface treatment, with use of which a cable having excellent transmission characteristics can be obtained.SOLUTION: A spun-bonded nonwoven fabric comprises fibers containing a polyester-based resin as main component. The spun-bonded nonwoven fabric includes fibers having a fiber orientation degree of 0 degrees or more and 20 degrees or less in a number proportion of 40% or more and 70% or less among the fibers. The cross section of the spun-bonded nonwoven fabric has a roughness ratio of 1.1 or more and 2.0 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a spunbond nonwoven fabric that is particularly suitable for use in pressure winding tapes and cables. [Background technology]

[0002] Pressure winding tapes, which bundle multiple conductors together, are used for a variety of purposes, primarily for industrial cables, household cables, LAN cables, etc. These pressure winding tapes must not impair the transmission characteristics of the conductors, and must also be easy to surface treat, easy to wind, and heat-resistant.In recent years, from an environmental perspective, there has been a demand from various quarters for tapes to use less plastic and be easy to recycle.

[0003] Such a pressure winding tape is made of a film or a spunbond nonwoven fabric.

[0004] For example, Patent Document 1 proposes a spunbond nonwoven fabric that is made of fibers with a circular cross section of a certain single yarn fineness or less, the fibers being bonded together only by heat and pressure bonding, and has an apparent porosity within a specific range. It describes that the resulting nonwoven fabric is appropriately thin, has high strength, and is resistant to deformation, and further has a smooth surface, a good resin coating, and can be impregnated with liquid or resin.

[0005] Patent Document 2 proposes a spunbond nonwoven fabric in which continuous fibers primarily composed of polyethylene terephthalate are opened and then bonded together by thermocompression, the spunbond nonwoven fabric having a certain level or higher intrinsic viscosity of the constituent fibers, the ratio of the flatness of the cross-section of the fibers in the outermost layer to that of the fibers in the inner layer, the longitudinal tensile strength per unit area, and the longitudinal tensile strength per thickness. According to this document, the spunbond nonwoven fabric is binderless, has improved surface smoothness, retains the strength of the fibers, and has excellent strength in a specific direction, and therefore can be used as an inexpensive base fabric for applications requiring higher strength, such as electrical wire pressure tape, printing substrate, and house wrap.

[0006] Furthermore, Patent Document 3 proposes a binderless long-fiber nonwoven fabric in which the cross section of the fibers constituting the long-fiber nonwoven fabric is approximately circular, and intrinsic viscosity, aspect ratio in the fiber direction, and tensile strength per unit area in the longitudinal direction are at least certain levels. According to this document, it is described that the long-fiber nonwoven fabric has excellent tensile strength without using a special binder, and can be produced inexpensively by continuing to use a general-purpose spinneret that uses round cross-section fibers. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-16370 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-197891 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-162186 Summary of the Invention [Problem to be solved by the invention]

[0008] It is believed that spunbond nonwoven fabrics such as those disclosed in Patent Documents 1 and 2 can produce nonwoven fabrics with a certain level of strength. However, because the surface of spunbond nonwoven fabrics is uneven, when used as a pressure winding tape, sufficient adhesion cannot be achieved with the tape (shielding tape) wrapped around it to shield electromagnetic waves generated from internal conductors, resulting in the formation of voids and poor transmission characteristics. Furthermore, the long-fiber nonwoven fabric disclosed in Patent Document 3 has higher strength in the longitudinal direction and is resistant to shrinkage in the width direction. However, the transmission characteristics required for today's high-speed lines are insufficient.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a spunbond nonwoven fabric which, when used as a pressure winding tape, has a certain strength, is easy to surface-treat, and can provide a cable with excellent transmission characteristics. [Means for solving the problem]

[0010] As a result of extensive research conducted by the inventors in order to achieve the above-mentioned object, it was discovered that by setting the degree of fiber orientation of a spunbond nonwoven fabric and the unevenness ratio of the cross section of the spunbond nonwoven fabric within certain ranges, it is possible to obtain a spunbond nonwoven fabric that has a certain level of strength, is easy to surface-treat, and can be used to obtain a cable with excellent transmission characteristics.

[0011] The present invention has been completed based on these findings, and provides the following inventions.

[0012] [1] A spunbond nonwoven fabric composed of fibers whose main component is polyester resin, wherein the ratio of fibers having a fiber orientation degree of 0° or more and 20° or less is 40% or more and 70% or less, and the cross-sectional irregularity ratio of the spunbond nonwoven fabric is 1.1 or more and 2.0 or less.

[0013] [2] The spunbond nonwoven fabric according to [1], wherein the CV value of the spunbond nonwoven fabric is 1.0% or more and 7.0% or less.

[0014] [3] The spunbond nonwoven fabric according to [1] or [2], wherein the fibers are monocomponent fibers.

[0015] [4] The spunbond nonwoven fabric according to any one of [1] to [3], wherein the average single fiber diameter of the fibers is 5.0 μm or more and 12.0 μm or less.

[0016] [5] Weight is 30g / m 2 More than 140g / m 2 The spunbond nonwoven fabric according to any one of the above [1] to [4], which is:

[0017] [6] A pressure winding tape made from the nonwoven fabric according to any one of [1] to [5] above.

[0018] [7] A cable having a core wire and a coating layer, The core wire is a plurality of conductor wires and / or optical fibers that are bound by the pressure winding tape described in [6], The covering layer is composed of a first layer which is a shielding tape layer and / or an insulator, and a second layer which is composed of a resin and is disposed on the outer surface of the first layer. cable.

[0019] [8] A step of spinning a polyester resin through an outlet hole of a spinneret and further drawing the polyester resin by suction to obtain fibers; a step of making the fibers align with a spread fiber board having an average inclination angle θ of 0° or more and 40° or less, and then collecting the fibers on a moving net conveyor to obtain a nonwoven web; a step of fusing the nonwoven web with a pair of upper and lower flat rolls or an embossing roll, either of which has concaves and convexes; A method for producing a spunbond nonwoven fabric, comprising: A method for producing a spunbonded nonwoven fabric, wherein the ratio of fibers having a fiber orientation degree of 0° or more and 20° or less among the fibers of the spunbonded nonwoven fabric is 40% or more and 70% or less, and the unevenness ratio of the cross section of the spunbonded nonwoven fabric is 1.1 or more and 2.0 or less. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide a spunbond nonwoven fabric that has a certain strength, is easy to surface-treat, and can be used to obtain a cable with excellent transmission characteristics. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic surface diagram illustrating a method for measuring the degree of fiber orientation in the spunbonded nonwoven fabric of the present invention. [Figure 2] FIG. 2 is a cross-sectional conceptual diagram illustrating a method for measuring the unevenness ratio of the cross section of the spunbonded nonwoven fabric of the present invention. [Figure 3] FIG. 3 is a schematic cross-sectional view of a (part of) production device for spunbonded nonwoven fabric, illustrating and explaining the configuration of the spreading plate in the production method for the spunbonded nonwoven fabric of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] The spunbond nonwoven fabric of the present invention is a spunbond nonwoven fabric composed of fibers whose main component is a polyester-based resin, in which the number ratio of fibers having a fiber orientation degree of 0° or more and 20° or less is 40% or more and 70% or less, and the unevenness ratio of the cross section of the spunbond nonwoven fabric is 1.1 or more and 2.0 or less.

[0023] In the present invention, the MD direction refers to the sheet conveying direction during the production of a spunbonded nonwoven fabric, i.e., the winding direction of the nonwoven fabric roll, and the CD direction refers to the direction perpendicular to the sheet conveying direction, i.e., the winding direction of the nonwoven fabric roll. If the spunbonded nonwoven fabric is not in a rolled state, for example, because it is cut, the MD direction and CD direction are determined according to the procedures shown in (i-1) to (i-4) below. (i-1) One arbitrary direction is determined within the plane of the spunbond nonwoven fabric, and a test piece 20 cm long and 3.0 cm wide is taken along that direction. (i-2) Similarly, collect test pieces 20 cm long and 3.0 cm wide in directions rotated 30°, 60°, and 90° from the direction in which the sample was taken. (i-3) Test specimens in each direction shall be measured in accordance with "6.5 Tensile strength and elongation" of JIS L1908:2000 "Geotextile testing methods." (i-4) The direction in which the measured value is highest is the MD direction of the spunbond nonwoven fabric, and the direction perpendicular to this is the CD direction. If there are two or more directions in which the tensile strength is highest, the direction perpendicular to these directions in which the tensile strength is lower is the CD direction of the spunbond nonwoven fabric, and the direction perpendicular to this is the MD direction.

[0024] The components will be described in detail below, but the present invention is not limited to the scope described below as long as it does not go beyond the gist of the present invention, and various modifications are possible within the scope of the present invention.

[0025] [Fibers made primarily of polyester resin] First, the spunbond nonwoven fabric of the present invention is composed of fibers whose main component is a polyester-based resin. Here, in the present invention, "mainly composed of a polyester-based resin" means that the mass of the polyester-based resin is greater than 50 mass% relative to the mass of the entire fiber. By using a polyester-based resin as the main component, the spunbond nonwoven fabric has excellent mechanical strength and heat resistance durability.

[0026] The polyester resin is a thermoplastic resin containing an acid component and a diol component as monomers. In the present invention, the acid component may be an aromatic carboxylic acid such as terephthalic acid (ortho-isomer), isophthalic acid, or terephthalic acid, an aliphatic dicarboxylic acid such as adipic acid or sebacic acid, or an alicyclic dicarboxylic acid such as cyclohexanecarboxylic acid. The diol component may be ethylene glycol, diethylene glycol, or the like.

[0027] Specific examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate, polylactic acid, polybutylene succinate, etc., as well as copolymers and mixed resins thereof. Among these, polyethylene terephthalate (PET) is most preferably used because it has a higher melting point, excellent heat resistance, and excellent rigidity.

[0028] These polyester-based resins can contain additives such as crystal nucleating agents, matting agents, lubricants, pigments, mildew inhibitors, antibacterial agents, flame retardants, metal oxides, aliphatic bisamides and / or alkyl-substituted aliphatic monoamides, and hydrophilic agents, provided that the effects of the present invention are not impaired. Metal oxides such as titanium oxide, among others, improve spinnability by reducing surface friction of the fibers and preventing fusion between the fibers. They also improve the fusion properties of the spunbonded nonwoven fabric by increasing thermal conductivity during fusion molding with a heated roll. Furthermore, aliphatic bisamides and / or alkyl-substituted aliphatic monoamides, such as ethylene bisstearamide, improve the releasability between the heated roll and the nonwoven web, thereby improving transportability.

[0029] The fibers according to the present invention are preferably monocomponent fibers. Compared to composite fibers such as core-sheath composite fibers, the monocomponent fibers result in spunbond nonwoven fabrics with superior heat resistance. Furthermore, when used as a pressure winding tape for industrial electric wires, for example, it is possible to suppress the shrinkage of the pressure winding tape wound around the industrial electric wire, thereby reducing the amount of overlap.

[0030] In the present invention, the melting point of the polyester resin is preferably 160°C or higher and 320°C or lower. By setting the lower limit of the melting point range to preferably 160°C or higher, more preferably 170°C or higher, and even more preferably 180°C or higher, it is possible to minimize shrinkage of the pressure winding tape due to heat generation caused by the electrical resistance of the conductor, thereby reducing the amount of overlap during pressure winding. On the other hand, by setting the upper limit of the melting point range to preferably 320°C or lower, more preferably 300°C or lower, and even more preferably 280°C or lower, it is possible to obtain a spunbond nonwoven fabric that is excellent in flexibility and easily conforms to the shape of the conductor when used as a pressure winding tape.

[0031] In the present invention, the melting point of a polyester resin is measured using a differential scanning calorimeter (for example, a "DSC-2" model manufactured by PerkinElmer) at a heating rate of 20°C / min over a temperature range of 30°C to 350°C, and the temperature at which the obtained melting endothermic curve gives an extreme value is taken as the melting point of the thermoplastic resin. For resins whose melting endothermic curve does not give an extreme value in the differential scanning calorimeter, the resin is heated on a hot plate, and the temperature at which the resin melts under microscope observation is taken as the melting point.

[0032] The average single fiber diameter of the fibers according to the present invention is preferably in the range of 5.0 μm to 12.0 μm. By setting the lower limit of the average single fiber diameter range to preferably 5.0 μm or more, more preferably 7.0 μm or more, and even more preferably 9.0 μm or more, a nonwoven fabric with excellent mechanical strength can be obtained. On the other hand, by setting the upper limit of the above range to preferably 12.0 μm or less, more preferably 11.0 μm or less, the uniformity of the spunbond nonwoven fabric can be improved, resulting in a spunbond nonwoven fabric with a dense surface. For example, when used as a LAN cable clamp, the quality variation of the cable can be reduced.

[0033] In the present invention, the average single fiber diameter (μm) of the fibers is a value measured and calculated by the following method. (i) Ten small samples are randomly taken from the spunbond nonwoven fabric. (ii) The surface of the collected small sample is photographed using a scanning electron microscope (SEM, such as the VHX-D500 manufactured by Keyence Corporation) at a magnification range of 500 to 2000 times, allowing the fiber diameters of 10 or more fibers to be clearly measured. (iii) From the photographs of each small sample, 10 fibers (100 in total) are randomly selected and their thickness is measured. Assuming that the cross section of the fiber is circular, the thickness is expressed as the single fiber diameter (μm). (iv) The arithmetic mean value is rounded to one decimal place to obtain the average single fiber diameter (μm).

[0034] [Spunbond nonwoven fabric] The spunbond nonwoven fabric of the present invention is a spunbond nonwoven fabric composed of the above-described fibers. Among the fibers constituting this spunbond nonwoven fabric, the number percentage of fibers having a fiber orientation degree of 0° or more and 20° or less is 40% or more and 70% or less. The "number percentage" here refers to the percentage by number, as described in the measurement and calculation methods below. By satisfying this requirement, the spunbond nonwoven fabric exhibits excellent uniformity of basis weight in the longitudinal direction, and is excellent in quality and mechanical strength in the longitudinal direction when used as a tape substrate, primarily for use in narrow widths.

[0035] With respect to the range of the number proportion of fibers having a fiber orientation degree of 0% to 20%, if the lower limit is 40% or more, preferably 45% or more, and more preferably 50% or more, the spunbond nonwoven fabric will have excellent mechanical strength in the longitudinal direction and uniformity of basis weight, specifically, excellent mechanical strength and uniformity of basis weight in a 3 cm width, which is the product width for general cable winding applications. On the other hand, with respect to the range of the number proportion of fibers having a fiber orientation degree of 0% to 20%, if the upper limit is 70% or less, preferably 65% ​​or less, and more preferably 60% or less, the degree of fiber orientation will not be extreme and overlapping of webs will be suppressed, resulting in a spunbond nonwoven fabric with a more uniform density.

[0036] In the present invention, the percentage of fibers in a spunbond nonwoven fabric having a fiber orientation degree of 0° or more and 20° or less refers to a value measured and calculated by the following method. (i) Randomly collect 15 small samples (8 mm in MD x 10 mm in CD) from the specimen. (ii) Set the MD direction perpendicular to the observation screen using a scanning electron microscope (SEM, for example, Keyence Corporation's VHX-D500) and take a 1000x photograph. (iii) A 0-degree reference line (13) parallel to the MD direction (the direction of the arrow 14 in FIG. 1) of the photograph (a conceptual diagram of the surface is shown in FIG. 1) is set, and the fiber orientation angle relative to it (θ 11 ~θ 14The fiber orientation angle in the present invention is a value measured for fibers in the range of 0° to 90° with respect to the 0° reference line (13), and is determined so that the angle does not indicate a negative value or exceed 90°. Furthermore, the fibers to be measured are only those with a continuous single fiber length of 150 μm or more exposed on the surface, and the θ in FIG. 1 is used. 13 When the fiber (11) cannot be approximated to a straight line, as in the calculation of (a), two points on the bent convex part of the fiber (11) within the measurement range frame (12) are connected by a straight line, and the angle between this line and the 0-degree reference line (13) is calculated as the fiber orientation angle. (iv) The number of fibers with a fiber orientation angle between 0° and 20° (N 0-20 ) to the total number (N A ) and calculate the fiber orientation degree (F) using the following formula. F(%)=N 0-20 / N A ×100...(formula).

[0037] The degree of fiber orientation of the spunbonded nonwoven fabric can be adjusted by changing the average inclination angle θ of the fiber-spreading plate in the process of forming the nonwoven web.

[0038] The spunbond nonwoven fabric of the present invention has a cross-sectional unevenness ratio of 1.1 to 2.0. By satisfying this requirement, the adsorption of drugs and water-absorbent polymers can be improved when post-processing is performed to impart properties such as electrical conductivity and water absorbency required for the pressure wrapping tape.

[0039] When the lower limit of the range of the cross-sectional unevenness ratio of the spunbond nonwoven fabric is 1.1 or more, preferably 1.2 or more, and more preferably 1.3 or more, the spunbond nonwoven fabric does not have a completely smooth surface, but exhibits a moderate anchoring effect, and provides sufficient adhesion when a functional resin is coated on the surface. On the other hand, when the upper limit of the range of the cross-sectional unevenness ratio of the spunbond nonwoven fabric is 2.0 or less, preferably 1.9 or less, and more preferably 1.8 or less, the spunbond nonwoven fabric has little coating unevenness at the uneven portions when coated with a functional material or the like. Furthermore, when a film or the like is attached, the spunbond nonwoven fabric has good adhesion to the functional material. In the present invention, the cross-sectional unevenness ratio of the spunbond nonwoven fabric refers to a value measured or calculated by the following method. (i) Take 25 small sample pieces from the spunbond nonwoven fabric so that their cross sections can be observed. (ii) A cross section of the collected small sample is photographed at 1000x magnification using a scanning electron microscope (SEM, for example, "VHX-D500" manufactured by Keyence Corporation). (iii) In the photograph of each small sample, the distance H1 (μm) at the position where the cross-sectional thickness is maximum and the distance H2 (μm) at the position where the cross-sectional thickness is minimum are measured, as shown in the cross-sectional conceptual diagram of Figure 2, and the unevenness ratio of the cross-section of the spunbond nonwoven fabric is obtained by dividing H1 by H2. (iv) (iii) is repeated for 25 small sample pieces, and the arithmetic mean value (unitless) of the results for all small sample pieces is rounded to the nearest tenth.

[0040] The unevenness ratio of the cross section of the spunbonded nonwoven fabric can be adjusted by the shape of the rolls used in the step of fusing the nonwoven web, the roll temperature, and the roll linear pressure.

[0041] Furthermore, the CV value of the spunbond nonwoven fabric of the present invention is preferably 1.0% or more and 7.0% or less. By setting the upper limit of the CV value of the spunbond nonwoven fabric to 7.0% or less, more preferably 6.0% or less, and even more preferably 5.0% or less, the spunbond nonwoven fabric can have little variation in the width direction, even if the product size when used as a pressure winding tape is narrow, and can achieve excellent product yield. On the other hand, by setting the CV value of the spunbond nonwoven fabric to a range of preferably 1.0% or more, the spunbond nonwoven fabric can have an appropriate amount of voids, which will exhibit an anchor effect during post-processing and provide sufficient strength against peeling of functional thin films, etc.

[0042] In the present invention, the basis weight CV value (%) of the spunbond nonwoven fabric is determined as follows. (i) Take 100 small pieces of 3 cm x 10 cm from the spunbond nonwoven fabric. (ii) Measure the mass (g) of each piece and calculate the unit area (1 m 2 ) per (iii) The average value of the conversion of (ii) (W ave ), standard deviation (W sdv ) are calculated respectively. (iv) Calculate the basis weight CV value (%) using the following formula and round off to the nearest tenth. Weight CV value (%) = W ave / W sdv ×100...(formula).

[0043] The spunbond nonwoven fabric of the present invention has a basis weight of 30 g / m 2 More than 140g / m 2 It is preferable that the following condition is satisfied: By using such a spunbonded nonwoven fabric, the spunbonded nonwoven fabric has excellent breathability and strength.

[0044] The lower limit of the weight of the spunbond nonwoven fabric is preferably 30 g / m 2 More preferably, 40 g / m 2 More preferably, 50 g / m2 By setting the weight per unit area to 140 g / m or more, a spunbonded nonwoven fabric having excellent mechanical strength can be obtained. On the other hand, the upper limit of the weight per unit area range of the spunbonded nonwoven fabric is preferably 140 g / m or more. 2 or less, more preferably 130 g / m 2 or less, more preferably 120 g / m 2 By satisfying the above condition, it is possible to suppress the formation of a film of the fibers, to provide a spunbond nonwoven fabric that has a minimum level of breathability, is capable of dissipating heat, and is suitable for cable presser winding.

[0045] In the present invention, the basis weight of the spunbond nonwoven fabric is a value measured and calculated by the following procedure in accordance with "6.2 Mass per unit area" of JIS L1913:2010 "Testing methods for general nonwoven fabrics." (i) Take three 25cm x 25cm test pieces per meter of sample width. (ii) Weigh the mass (g) of each at standard conditions. (iii) The average value is 1 m 2 Mass per unit (g / m 2 ) and rounded to the first decimal place.

[0046] The apparent density of the spunbond nonwoven fabric of the present invention is 0.30 g / cm 3 More than 0.80g / cm 3 The lower limit of the apparent density range of the spunbond nonwoven fabric is preferably 0.30 g / cm or less. 3 More preferably, 0.35 g / cm 3 When the tensile strength is 0.80 g / cm or more, the spunbond nonwoven fabric has higher mechanical strength. On the other hand, the upper limit of the above range is preferably 0.80 g / cm. 3 or less, more preferably 0.70 g / cm 3 By satisfying the above condition, the spunbond nonwoven fabric will have the ability to adsorb chemicals and water-absorbent polymers when post-processing is carried out to impart properties such as conductivity and water-absorbency required for the pressure winding tape.

[0047] In the present invention, the apparent density of the spunbond nonwoven fabric is determined by the following method. (i) The thickness (mm) of the spunbond nonwoven fabric is measured according to the following procedures (i-1) to (i-2). (i-1) Using a thickness meter (for example, TECLOCK (registered trademark) SM-114 manufactured by TECLOCK Corporation), measure the thickness of the spunbond nonwoven fabric at 10 points at 10 cm intervals in the CD direction. If the distance in the CD direction is 100 cm or less, divide the distance in the CD direction into 10 parts and measure at 10 points at those intervals. (i-2) Calculate the arithmetic mean value (mm) of the above measurement results and round off to two decimal places. (ii) The basis weight (g / m) of the spunbond nonwoven fabric 2 ) and thickness (mm), the value calculated by the following formula will be used as the apparent density. Apparent density (g / cm 3 ) = basis weight (g / m 2 ) / Thickness (mm) / 1000 ···(Formula).

[0048] [Manufacturing method of spunbond nonwoven fabric] The spunbond nonwoven fabric of the present invention is preferably produced by: a step of spinning a polyester resin through an outlet hole of a spinneret and then drawing the polyester resin by suction to obtain fibers; a step of making the fibers align with a spread fiber board having an average inclination angle θ of 0° or more and 40° or less, and then collecting the fibers on a moving net conveyor to obtain a nonwoven web; a step of fusing the nonwoven web with a pair of upper and lower flat rolls or an embossing roll, either of which has concaves and convexes; A method for producing a spunbond nonwoven fabric, comprising: Preferably, the method for producing a spunbonded nonwoven fabric is such that the ratio of fibers having a fiber orientation degree of 0° or more and 20° or less among the fibers of the spunbonded nonwoven fabric is 40% or more and 70% or less, and the unevenness ratio of the cross section of the spunbonded nonwoven fabric is 1.1 or more and 2.0 or less. Each step of the above-mentioned preferred embodiment will be explained in more detail below, but the present invention is not limited thereto.

[0049] (a) Fiber Obtaining Process In this process, polyester resin is spun out from the outlet holes of the spinneret and then drawn by suction to obtain fibers.

[0050] First, the polyester resin is spun out from the nozzle holes of the spinneret. In particular, when polyethylene terephthalate is used as the polyester resin, it is preferable to melt the polyethylene terephthalate at a temperature equal to or higher than its melting point, and then raise the nozzle temperature of the spinneret to a temperature equal to or higher than the melting point (up to 70°C above the melting point), and then spin the polyester resin out from the nozzle holes of the spinneret.

[0051] The shape of the nozzle holes of the spinneret can be circular, elliptical, polygonal, multilobal, or a combination thereof, depending on the cross-sectional shape of the fibers. Of these, circular and elliptical cross-sectional shapes are more preferable. For example, when a circular cross-sectional shape is used, bonding points between fibers can be efficiently obtained, and the fibers can be firmly bonded to each other by fusion, as described below. Furthermore, when a elliptical cross-sectional shape is used, the apparent density can be further improved, and the porosity of the spunbonded nonwoven fabric can be reduced, thereby improving cable properties.

[0052] The polyester resin spun as described above is then drawn by suction using an ejector or the like to form a fiber. In this case, the spinning speed is preferably 3000 m / min or more and 6000 m / min or less. Setting the spinning speed to preferably 3000 m / min or more, more preferably 3300 m / min or more, and even more preferably 3600 m / min or more promotes the orientation and crystallization of the fiber, resulting in a high-strength fiber. On the other hand, setting the spinning speed to preferably 6000 m / min or less, more preferably 5500 m / min or less, and even more preferably 5000 m / min or less can suppress spinning defects such as thread breakage, resulting in manufacturing conditions with excellent production stability.

[0053] (b) Obtaining a nonwoven web In this step, the fibers are made to run along a fiber-spreading plate having an average tilt angle θ of 0° or more and 40° or less, and then collected on a moving net conveyor to obtain a fiber web.

[0054] First, the fibers obtained in the step (a) are aligned with a spread plate having an average inclination angle θ of 0° or more and 40° or less. This regulates the arrangement of the fibers. Specifically, it is preferable that the fibers sucked by an ejector are ejected from a spread plate having a slit provided below the ejector.

[0055] Here, the spread plate is, for example, provided directly below an ejector 31 used in suction drawing, as exemplified in Fig. 3, and the spread plate 32 is provided at an average inclination angle θ, which will be described later, with respect to a normal line 34 from the ground surface 33. Here, when this average inclination angle θ is parallel to the normal line 34 from the ground surface 33, θ=0°, and as shown in Fig. 3, the angle in the opposite direction with respect to the transport direction (direction indicated by arrow 35) of the nonwoven web transported by a moving net conveyor 36 is positive (θ>0°).

[0056] The average inclination angle θ is preferably 0° or more and 40° or less. By setting the average inclination angle θ to preferably 0° or more, more preferably 5° or more, even more preferably 10° or more, and particularly preferably 15° or more, the fibers ejected from the ejector are regularly aligned in the direction of travel of the net conveyor, making it possible to control the degree of fiber orientation in the resulting spunbond nonwoven fabric. On the other hand, by setting the average inclination angle θ to preferably 40° or less, more preferably 35° or less, even more preferably 30° or less, and particularly preferably 25° or less, the fibers ejected from the ejector do not become entangled with each other, making it possible to produce a spunbond nonwoven fabric with excellent basis weight uniformity.

[0057] In this process, the fibers are collected on a moving net conveyor to obtain a nonwoven web. In the present invention, "collecting the fibers on a moving net conveyor" refers to sequentially depositing the fibers on a rotating net conveyor. Furthermore, this net conveyor refers to a belt conveyor in which the belt portion is a punched plate, a mesh, or a porous body. However, to prevent the collected fibers from falling into the net conveyor through the perforations of the mesh, the punched plate, or the holes in the porous body (hereinafter abbreviated as "holes, etc."), or from clogging the holes, it is preferable to appropriately set the size of the holes, etc., taking into account the resin constituting the fibers and the fiber diameter, etc., or to use a material with high grip strength depending on the resin constituting the fibers. The belt portion may be made of metal or synthetic resin.

[0058] (c) Fusing the nonwoven web In this process, the nonwoven web is fused using a pair of upper and lower flat rolls or an embossing roll, either of which has concaves and convexes on the upper or lower side.

[0059] The term "flat roll" as used herein refers to a metal roll or elastic roll having no irregularities on the surface of the roll, and a pair of upper and lower flat rolls refers to a pair of such metal rolls or elastic rolls, such as a pair of metal rolls or a pair of metal rolls and an elastic roll.

[0060] An elastic roll is a roll made of a material that has greater elasticity than a metal roll, and examples of the elastic roll include so-called paper rolls made of paper, cotton, aramid paper, etc., and resin rolls made of urethane resin, epoxy resin, silicon resin, polyester resin, hard rubber, etc., or mixtures of these.

[0061] Furthermore, the embossing roll having irregularities referred to here is a roll in which the convex portions form fused portions and the concave portions form non-fused portions, and the shape of the irregularities is not limited, but polka dots, oval patterns, woven patterns, etc. are preferably used.

[0062] The surface temperature of the flat roll or embossing roll for fusion bonding is preferably 5°C to 60°C lower than the melting point of the polyester resin. This temperature can prevent excessive fusion between fibers, which could result in the spunbonded nonwoven fabric partially becoming a film-like sheet. It can also prevent the low-melting-point polymer component from fusing to the roll used for fusion bonding, which could result in a decrease in productivity.

[0063] The linear pressure of the roll during fusion is preferably 98 N / cm or more and 1960 N / cm or less. By setting the linear pressure to 98 N / cm or more, a spunbond nonwoven fabric with excellent mechanical strength can be obtained. By setting the linear pressure to 1960 N / cm or less, excessive fusion between the fibers can be prevented.

[0064] (d) Other post-processing processes However, in the method for producing the spunbond nonwoven fabric of the present invention, it is preferable to further carry out various post-processing steps, as in the case of general spunbond nonwoven fabrics. Of course, in the present invention, the spunbond nonwoven fabric obtained by carrying out these post-processing steps is also considered to be the spunbond nonwoven fabric of the present invention.

[0065] Examples of post-processing steps referred to here include processing to improve the electrical conductivity, water absorbency, flame retardancy, water and oil repellency, and slip resistance of the spunbond nonwoven fabric; lamination processing to form a laminate with a denser layer such as a melt-blown nonwoven fabric, a nanofiber fiber sheet, or a PTFE membrane; and super calendaring and paper calendaring to make the surface smoother.

[0066] [Pressing tape, cable] As described above, the spunbond nonwoven fabric according to the present invention provides a cable that has a certain strength, is easy to surface-treat, and has excellent transmission characteristics. Therefore, the pressure winding tape according to the present invention is preferably made from the nonwoven fabric. Here, in the present invention, the pressure winding tape is used to restrain a plurality of conductor wires and / or optical fibers, as described below, to form a core wire. Furthermore, by using the nonwoven fabric, the pressure winding tape can also function as an electromagnetic wave shield, blocking electromagnetic waves generated from the conductor wires.

[0067] Furthermore, the cable of the present invention is a cable having a core wire and a coating layer, wherein the core wire is composed of a plurality of conductors and / or optical fibers restrained by the pressure winding tape, and the coating layer is preferably composed of a first layer which is a shielding tape layer and / or an insulator, and a second layer which is composed of a resin and is disposed on the outer surface of the first layer.

[0068] Examples of the shielding tape layer in this first layer include copper foil, aluminum foil, conductive polyester woven fabric, etc. Examples of the insulator include cross-linked polyethylene, polyethylene, ethylene propylene rubber, vinyl chloride, etc.

[0069] Examples of the resin in the second layer include various resins such as vinyl chloride, polyethylene, natural rubber, synthetic rubber, and urethane.

[0070] The cable of the present invention is not particularly limited in its use, and can be used as a LAN cable for home use, a utility pole cable, an industrial cable, or an undersea cable. [Example]

[0071] Next, the spunbond nonwoven fabric of the present invention will be specifically described based on examples, although the present invention is not limited to these examples.

[0072] [Measurement method] The evaluation methods and measurement conditions used in the examples are explained below. Unless otherwise specified, the measurements of each physical property were carried out according to the above-mentioned methods.

[0073] (1) Melting point of polyester resin (℃) Measurement was carried out using a differential scanning calorimeter "DSC-2" manufactured by PerkinElmer Co., Ltd., at a temperature rise rate of 20°C / min, and the temperature at which the extreme value was obtained in the obtained melting endothermic curve was taken as the melting point.

[0074] (2) Intrinsic viscosity (IV) of polyester resin The intrinsic viscosity (IV) of polyester resin was measured by dissolving 8 g of sample in 100 mL of orthochlorophenol and measuring the relative viscosity η using an Ostwald viscometer at 25°C. r was calculated using the following formula: η r =η / η0=(t×d) / (t0×d0) ···(Formula). (where η is the viscosity of the polymer solution, η0 is the viscosity of orthochlorophenol, t is the solution drop time (seconds), and d is the solution density (g / cm 3 ), t0 is the fall time of orthochlorophenol (seconds), and d0 is the density of orthochlorophenol (g / cm 3 ) respectively. Next, the relative viscosity η r The intrinsic viscosity (IV) was calculated using the following formula: Intrinsic viscosity (IV)=0.0242η r +0.2634...(expression).

[0075] (3) Melt flow rate (MFR) of polyester resin The melt flow rate (MFR) of the polyester resin was measured according to ASTM D1238 under the conditions of a load of 2160 g and a temperature of 210°C.

[0076] (4) Average single fiber diameter (μm) The average single fiber diameter of the fibers was measured and calculated by the above-mentioned method using a scanning electron microscope "VHX-D500" manufactured by Keyence Corporation.

[0077] (5) Fiber orientation degree (°), percentage of fibers with a fiber orientation degree of 0% to 20% (%) The degree of fiber orientation and the number ratio of fibers having a degree of fiber orientation of 0% or more and 20% or less were measured and calculated by the above-mentioned method.

[0078] (6) Concave-convex ratio of the cross section of spunbond nonwoven fabric The unevenness ratio of the spunbond nonwoven fabric was calculated by the method described above. When the unevenness ratio of the cross section of the spunbond nonwoven fabric was 1.1 or more and 2.0 or less, the spunbond nonwoven fabric was deemed to be easy to surface process.

[0079] (7) Basis weight of spunbond nonwoven fabric (g / m 2 ) The basis weight of the spunbond nonwoven fabric was calculated by the method described above.

[0080] (8) CV value (%) of spunbond nonwoven fabric The CV value of the basis weight of the spunbond nonwoven fabric was calculated by the method described above.

[0081] (9) Thickness of spunbond nonwoven fabric (mm) The thickness of the spunbond nonwoven fabric was measured and calculated using a thickness meter "Teclock" (registered trademark) SM-114 manufactured by Teclock Corporation, according to the method described above.

[0082] (10) Apparent density of spunbond nonwoven fabric (g / cm 3 ) The apparent density of the spunbond nonwoven fabric was calculated by the method described above.

[0083] (11) Vertical tensile strength of spunbond nonwoven fabric (N / 3cm) The warp tensile strength (N / 3 cm) of the spunbond nonwoven fabric was measured and calculated using Baldwin's RTG-1250 by the following method. (i) Three 30 cm x 3.0 cm wide samples are taken from the spunbond nonwoven fabric at equal intervals in the MD direction. (ii) Apply a load until the sample breaks, with a grip distance of 20 cm and a tensile speed of 100±10 mm / min. (iii) The strength of the sample at the maximum load is taken as the tensile strength (N / 3cm), and the average value (N / 3cm) of three points in the MD direction is calculated and rounded to the first decimal place.

[0084] (12) Dielectric constant of spunbond nonwoven fabric The relative permittivity of spunbond nonwoven fabric was measured using the LCR meter IM3536 manufactured by Hioki E.E. Measurements were made in accordance with the measurement method of ASTM D 150. The sample size was a flat plate of 60 mm x 60 mm, and measurements were made at five points, with the average value being taken as the relative permittivity of the spunbond nonwoven fabric.

[0085] [Polyester resin used] Next, the resins used in the examples and comparative examples will be described in detail. Polyester resin A: Polyethylene terephthalate (referred to as PET in Tables 1 to 4) dried to a moisture content of 50 mass ppm or less, with an intrinsic viscosity (IV) of 0.65 and a melting point of 260°C. Polyester resin B: Copolymerized polyethylene terephthalate (referred to as Co-PET in Tables 1 to 4) dried to a moisture content of 50 mass ppm or less, with an intrinsic viscosity (IV) of 0.64, an isophthalic acid copolymerization rate of 11 mol%, and a melting point of 230°C. Polyester resin C: Polylactic acid, dried to a fraction of 50 mass ppm or less, with a melt flow rate (MFR) of 22 g / 10 min and a melting point of 180°C (referred to as PLA in Tables 1 to 4).

[0086] [Example 1] (Process for obtaining fibers) The polyester resin A was melted at a temperature of 295° C. Then, the resin was spun out from a circular nozzle at a nozzle temperature of 295° C.

[0087] The spun polyester resin A was then pulled and stretched by an ejector at a spinning speed of 4500 m / min to form fibers.

[0088] (Step of obtaining a nonwoven web) The obtained fibers were sucked by an ejector and were then placed along a slit-shaped opening plate provided at the bottom of the ejector with an average inclination angle of 20°, and the weight of the obtained nonwoven fabric was 100 g / m 2 The nonwoven web was obtained by collecting the particles on a net conveyor (a belt portion of which is made of a mesh) whose moving speed was adjusted so that the nonwoven web was obtained.

[0089] (Step of fusing nonwoven web) The obtained nonwoven web was fusion-bonded using a pair of upper and lower heated rolls having the following configuration to obtain a spunbonded nonwoven fabric. Upper roll: Metal embossing roll (EMB) with a surface temperature of 240°C Bottom roll: Metallic flat roll (FLT) with a surface temperature of 240°C (In the table above, the roll composition is written as EMB / FLT.) Roller line pressure: 686N / cm The physical properties of the resulting spunbond nonwoven fabric are shown in Table 1.

[0090] [Example 2] The weight of the nonwoven fabric obtained in (the step of obtaining a nonwoven web) is 100 g / m 2 It was originally adjusted to 30g / m 2 A spunbonded nonwoven fabric was obtained under the same conditions as in claim 1, except that the temperature was adjusted so that the following was true: The physical properties of the obtained spunbonded nonwoven fabric are shown in Table 1.

[0091] [Example 3] The weight of the nonwoven fabric obtained in (the step of obtaining a nonwoven web) is 100 g / m 2 It was originally adjusted to 140g / m 2A spunbonded nonwoven fabric was obtained under the same conditions as in claim 1, except that the temperature was adjusted so that the following was true: The physical properties of the obtained spunbonded nonwoven fabric are shown in Table 1.

[0092] [Example 4] A spunbond nonwoven fabric was obtained under the same conditions as in Example 1, except that in the (step of obtaining fibers), the spun polyester resin A was pulled and stretched by an ejector at a spinning speed of 4,500 m / min, but the spinning speed was changed to 3,500 m / min to adjust the average single fiber diameter. The physical properties of the obtained spunbond nonwoven fabric are shown in Table 1.

[0093] [Example 5] A spunbond nonwoven fabric was obtained under the same conditions as in Example 1, except that in the (step of obtaining fibers), the spun polyester resin A was pulled and stretched by an ejector at a spinning speed of 4,500 m / min, but the spinning speed was changed to 5,500 m / min to adjust the average single fiber diameter. The physical properties of the obtained spunbond nonwoven fabric are shown in Table 1.

[0094] [Table 1]

[0095] [Example 6] A spunbonded nonwoven fabric was obtained under the same conditions as in Example 1, except that in the (step of fusing the nonwoven web), the roll configuration was changed to the following. Upper roll: Metal flat roll with a surface temperature of 240°C Bottom roll: Metal flat roll with a surface temperature of 240°C Roller line pressure: 686N / cm The physical properties of the obtained spunbond nonwoven fabric are shown in Table 2.

[0096] [Example 7] A spunbonded nonwoven fabric was obtained under the same conditions as in Example 1, except that in (the process of obtaining fibers), polyester-based resin A was changed to polyester-based resin B, the resin was melted at a temperature of 260°C, and spun from a circular discharge hole at a nozzle temperature of 260°C, and in (the process of fusing the nonwoven web), the roll configuration was changed to the following. Upper roll: Metal embossing roll with a surface temperature of 190°C Lower roll: Metal flat roll with a surface temperature of 190°C Roller line pressure: 686N / cm The physical properties of the obtained spunbond nonwoven fabric are shown in Table 2.

[0097] [Example 8] A spunbonded nonwoven fabric was obtained under the same conditions as in Example 7, except that in the (step of fusing the nonwoven web), the roll configuration was changed to the following. Upper roll: Metallic flat roll with a surface temperature of 190°C Lower roll: Metal flat roll with a surface temperature of 190°C Metal roll line pressure: 686N / cm The physical properties of the obtained spunbond nonwoven fabric are shown in Table 2.

[0098] [Example 9] A spunbond nonwoven fabric was obtained under the same conditions as in Example 1, except that in (the process of obtaining fibers), polyester resin A was changed to polyester resin C, the resin was melted at a temperature of 220°C, and spun from a circular discharge hole at a nozzle temperature of 220°C, and in (the process of fusing the nonwoven web), the roll configuration was changed to the following. Upper roll: Metal embossing roll with a surface temperature of 150°C Lower roll: Metal flat roll with a surface temperature of 150°C Roller line pressure: 686N / cm The physical properties of the obtained spunbond nonwoven fabric are shown in Table 2.

[0099] [Example 10] A spunbonded nonwoven fabric was obtained under the same conditions as in Example 9, except that the roll configuration was changed to the following in (the step of fusing the nonwoven web). Upper roll: Metal flat roll with a surface temperature of 150°C Lower roll: Metal flat roll with a surface temperature of 150°C Roller line pressure: 686N / cm The physical properties of the obtained spunbond nonwoven fabric are shown in Table 2.

[0100] [Table 2]

[0101] [Example 11] A spunbonded nonwoven fabric was obtained under the same conditions as in Example 6, except that the average inclination angle θ of the spreader plate was changed to 5° in (the step of obtaining a nonwoven web). The physical properties of the obtained spunbonded nonwoven fabric are shown in Table 3.

[0102] [Example 12] A spunbonded nonwoven fabric was obtained under the same conditions as in Example 6, except that the average inclination angle θ of the spreader plate was changed to 15° in (the step of obtaining a nonwoven web). The physical properties of the obtained spunbonded nonwoven fabric are shown in Table 3.

[0103] [Example 13] A spunbonded nonwoven fabric was obtained under the same conditions as in Example 6, except that the average inclination angle θ of the spreader plate was changed to 35° in (the step of obtaining a nonwoven web). The physical properties of the obtained spunbonded nonwoven fabric are shown in Table 3.

[0104] [Example 14] A spunbonded nonwoven fabric was obtained under the same conditions as in Example 6, except that the average inclination angle θ of the spreader plate was changed to 25° in (the step of obtaining a nonwoven web). The physical properties of the obtained spunbonded nonwoven fabric are shown in Table 3.

[0105] [Table 3]

[0106] [Comparative Example 1] A spunbonded nonwoven fabric was obtained under the same conditions as in Example 1, except that in (step of obtaining a nonwoven web), the average inclination angle θ of the spread plate was changed from 20° to 0°. The physical properties of the obtained spunbonded nonwoven fabric are shown in Table 4.

[0107] Comparative Example 2 A spunbonded nonwoven fabric was obtained under the same conditions as in Example 7, except that in (step of obtaining a nonwoven web), the average inclination angle θ of the spread plate was changed from 20° to 0°. The physical properties of the obtained spunbonded nonwoven fabric are shown in Table 4.

[0108] Comparative Example 3 A spunbonded nonwoven fabric was obtained under the same conditions as in Example 9, except that in (step of obtaining a nonwoven web), the average inclination angle θ of the spread plate was changed from 20° to 0°. The physical properties of the obtained spunbonded nonwoven fabric are shown in Table 4.

[0109] Comparative Example 4 An attempt was made to obtain a spunbonded nonwoven fabric under the same conditions as in Example 1, except that in (the step of obtaining a nonwoven web), the average inclination angle θ of the spread plate was changed from 20° to 40°; however, in (the step of obtaining a nonwoven web), the web was blown away to the rear of the net conveyor, and therefore a nonwoven web could not be obtained, and therefore a spunbonded nonwoven fabric could not be obtained.

[0110] Comparative Example 5 In the (step of fusing the nonwoven web), the obtained nonwoven web was fused using a pair of heated upper and lower rolls having the following configuration to form a fused sheet, thereby obtaining a spunbonded nonwoven fabric under the same conditions as in Example 1. Upper roll: Metal embossing roll with a surface temperature of 240°C Lower roll: Metal embossing roll with a surface temperature of 240°C Roller line pressure: 686N / cm. The physical properties of the obtained spunbond nonwoven fabric are shown in Table 4.

[0111] [Table 4]

[0112] The properties of the obtained spunbond nonwoven fabrics are as shown in Tables 1 to 4. The spunbond nonwoven fabrics of Examples 1 to 14 had excellent basis weight uniformity, a small unevenness ratio in the cross section of the spunbond nonwoven fabric, and an excellent dielectric constant, and showed good properties when made into a pressure winding tape. In particular, Example 6 had high basis weight uniformity and a small unevenness ratio in the cross section of the nonwoven fabric, making it a spunbond nonwoven fabric suitable for a pressure winding tape.

[0113] On the other hand, the spunbond nonwoven fabrics of Comparative Examples 1 to 5 did not have excellent uniformity of basis weight (Comparative Examples 1 to 3), did not have excellent relative dielectric constants of the spunbond nonwoven fabrics (Comparative Examples 1 to 3, 5), or did not produce spunbond nonwoven fabrics (Comparative Example 4). [Explanation of symbols]

[0114] 11: Fiber 12: Measurement range frame 13:0 degree reference line 14: MD direction arrow 15: CD direction arrow 21: Spunbond nonwoven fabric 31: Ejector 32: Spreading board 33: Ground 34: Normal from the ground 35: Arrow indicating the direction of transport of the nonwoven web 36: Moving net conveyor H1: The distance at which the cross section is at its maximum thickness H2: The distance at which the cross-section thickness is minimum θ 11 ~θ 14 : Fiber orientation angle relative to the 0 degree reference line θ: average tilt angle

Claims

1. A spunbond nonwoven fabric made of fibers containing a polyester resin as a main component, wherein the ratio of fibers having a fiber orientation degree of 0° or more and 20° or less is 40% or more and 70% or less, and the unevenness ratio of the cross section of the spunbond nonwoven fabric is 1.1 or more and 2.0 or less.

2. 2. The spunbond nonwoven fabric according to claim 1, wherein the basis weight CV value of the spunbond nonwoven fabric is 1.0% or more and 7.0% or less.

3. 3. The spunbond nonwoven fabric of claim 1 or 2, wherein the fibers are monocomponent fibers.

4. 3. The spunbond nonwoven fabric according to claim 1, wherein the fibers have an average single fiber diameter of 5.0 μm or more and 12.0 μm or less.

5. Weight per unit area: 30g / m 2 140g / m or more 2 3. The spunbond nonwoven fabric of claim 1, wherein:

6. A pressure winding tape comprising the nonwoven fabric according to claim 1 or 2.

7. A cable having a core wire and a coating layer, The core wire is a plurality of conductive wires and / or optical fibers, and is bound by the pressure winding tape according to claim 6, The covering layer is composed of a first layer which is a shielding tape layer and / or an insulator, and a second layer which is an outer layer of the first layer and is composed of a resin. cable.

8. a step of spinning a polyester resin through an outlet hole of a spinneret and then drawing the polyester resin by suction to obtain fibers; a step of making the fibers align with a spread fiber plate having an average inclination angle θ of 0° or more and 40° or less, and then collecting the fibers on a moving net conveyor to obtain a nonwoven web; a step of fusing the nonwoven web with a pair of upper and lower flat rolls or an embossing roll, either of which has concaves and convexes; A method for producing a spunbond nonwoven fabric, comprising: A method for producing a spunbonded nonwoven fabric, wherein the ratio of fibers having a fiber orientation degree of 0° or more and 20° or less is 40% or more and 70% or less, among the fibers of the spunbonded nonwoven fabric, and the unevenness ratio of the cross section of the spunbonded nonwoven fabric is 1.1 or more and 2.0 or less.

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