Spunbond nonwoven fabric, method for manufacturing the same, and packaging material

Abstract

An object of the present invention is to provide a spunbonded nonwoven fabric excellent in tear strength, fuzzing resistance, and printability, and a packaging material formed using the same. [Solution] The spunbonded nonwoven fabric includes fibers composed of a thermoplastic resin A containing a polyester-based resin as a main component, wherein at least a part of the periphery of the fibers is coated with a thermoplastic resin B containing a polyolefin-based resin as a main component, the spunbonded nonwoven fabric, wherein the difference between the melting point (T m,A ) °C of the thermoplastic resin A and the melting point (T m,B ) °C of the thermoplastic resin B is 50°C or more and 180°C or less, the apparent density of the spunbonded nonwoven fabric is 0.30 g / cm 3 or more and 1.40 g / cm 3 or less, the average arithmetic mean roughness Ra of the surface of the spunbonded nonwoven fabric is 1.0 μm or more and 15.0 μm or less, and the tensile elongation in the longitudinal direction of the spunbonded nonwoven fabric is 35% or more, the spunbonded nonwoven fabric.

Description

[Technical Field]

[0001] This invention relates to spunbond nonwoven fabric, a method for producing the same, and packaging materials. [Background technology]

[0002] In recent years, nonwoven fabrics have been used in a variety of applications, including industrial materials, civil engineering materials, construction materials, consumer goods, agricultural materials, packaging materials, sanitary materials, and medical materials. Among these, nonwoven fabrics used in packaging materials require tensile strength and tear strength to prevent tearing when the contents are enclosed, resistance to fuzzing to prevent fiber shedding during use, and surface smoothness to achieve good printability.

[0003] For example, Patent Document 1 proposes a spunbond nonwoven fabric that exhibits excellent mechanical strength and surface smoothness by setting the crystallization peak and melting peak in differential scanning calorimetry for spunbond nonwoven fabrics within a specific temperature range. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2024 / 204334 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, the mechanical strength study of the spunbond nonwoven fabric described in Patent Document 1 only examined tensile strength, and improvements in tear strength and fuzz resistance, which are equally important for the performance of a packaging material, have not yet been considered.

[0006] Therefore, the object of the present invention is to provide a spunbond nonwoven fabric with excellent tear strength, fuzz resistance, and printability, and a packaging material made using the same. [Means for solving the problem]

[0007] As the present invention and preferred embodiments thereof, the following configurations are presented. [1] A spunbond nonwoven fabric comprising fibers composed of thermoplastic resin A containing a polyester-based resin as a main component, wherein at least part of the periphery of at least some of the fibers is coated with thermoplastic resin B containing a polyolefin-based resin as a main component, the spunbond nonwoven fabric having a melting point (T m,A ) °C of the thermoplastic resin A and a melting point (T m,B ) °C of the thermoplastic resin B that differ by 50°C or more and 180°C or less, the spunbond nonwoven fabric having an apparent density of 0.30 g / cm 3 or more and 1.40 g / cm 3 or less, an average arithmetic mean roughness Ra of the surface of the spunbond nonwoven fabric of 1 μm or more and 15 μm or less, and a tensile elongation in the longitudinal direction of the spunbond nonwoven fabric of 35% or more. [2] The spunbond nonwoven fabric according to [1], wherein the average number density of the fibers coated with the thermoplastic resin B, observed in a cross section in the thickness direction of the spunbond nonwoven fabric, is 100 fibers / mm 2 or more and 8000 fibers / mm 2 or less. [3] The spunbond nonwoven fabric according to [1] or [2], wherein the ratio of the number of the fibers coated with the thermoplastic resin B per unit area to the number of the fibers observed in a cross section in the thickness direction of the spunbond nonwoven fabric is 70% or more and 100% or less. [4] The spunbond nonwoven fabric according to any one of [1] to [3], wherein the product of tensile strength and elongation per basis weight of the spunbond nonwoven fabric is 1.0 (N / 50mm) / (g / m 2 ) or more and 8.0 (N / 50mm) / (g / m 2 ) or less. [5] The spunbond nonwoven fabric according to any one of [1] to [4], wherein the thermoplastic resin A is a polyethylene terephthalate-based resin, and the thermoplastic resin B is a polyethylene-based resin. [6] The spunbond nonwoven fabric according to any one of [1] to [5], which satisfies either of the following Formula 1 or Formula 2 R1<R2···(Formula 1) 0.50≦R1 / R2≦0.95 ···(Equation 2). Here, R1 (μm) is the fiber diameter of the fiber composed of thermoplastic resin A in the portion on one surface side of the spunbond nonwoven fabric, and R2 (μm) is the fiber diameter of the fiber composed of thermoplastic resin A in the portion on the other surface side of the spunbond nonwoven fabric. [7] A method for producing the spunbond nonwoven fabric according to any one of [1] to [6], comprising: a step of forming a fiber web composed of core-sheath type composite fibers, wherein the core component is a thermoplastic resin containing a polyester-based resin as a main component, and the sheath component is a thermoplastic resin containing a polyolefin-based resin as a main component; a step of bringing only one surface of the web into contact with a heating surface of a heating device for preheating to obtain a preheated web; and a step of thermally fusing the preheated web using a thermal calender roll composed of a pair of upper and lower flat rolls, wherein the preheating temperature in the step of obtaining the preheated web is 30°C or higher and 90°C or lower. [8] A method for producing the spunbond nonwoven fabric according to any one of [1] to [6], comprising: a step of forming a first fiber web composed of first core-sheath type composite fibers, wherein the core component is thermoplastic resin A containing a polyester-based resin as a main component, and the sheath component is thermoplastic resin B containing a polyolefin-based resin as a main component; a step of forming a second fiber web composed of second core-sheath type composite fibers on the first fiber web, wherein the core component is a thermoplastic resin containing polyester-based resin A as a main component, and the sheath component is thermoplastic resin B containing a polyolefin-based resin as a main component, to form a laminated web; a step of bringing only one surface of the laminated web into contact with a heating surface of a heating device for preheating to obtain a preheated web; and a step of thermally fusing the laminated web using a thermal calender roll composed of a pair of upper and lower flat rolls, wherein the preheating temperature in the step of obtaining the preheated web is 30°C or higher and 90°C or lower, and the first fiber web and the second fiber web satisfy the following Equations 3 and 4. 0.10≦P C1 ≦0.70 ···(Equation 3) 0.10≦PC2 -P C1 ≦0.55 (Equation 4). Here, P C1 P is the area ratio (unitless) of the core component in the cross-section of the first core-sheath type composite fiber, and P C2 This is the area ratio (unitless) of the core component in the cross-section of the second core-sheath type composite fiber. A method for producing a spunbond nonwoven fabric as described in any of [9] [1] to [6], comprising the steps of: forming a second fiber web composed of a second core-sheath composite fiber having a core component of thermoplastic resin A mainly composed of polyester resin and a sheath component of thermoplastic resin B mainly composed of polyolefin resin; forming a first fiber web on the second fiber web, composed of a first core-sheath composite fiber having a core component of thermoplastic resin A mainly composed of polyester resin and a sheath component of thermoplastic resin B mainly composed of polyolefin resin, to form a laminated web; preheating the laminated web by bringing the heating surface of a heating device into contact with only one surface of the laminated web to obtain a preheated web; and heat-sealing the laminated web using a thermal calender roll consisting of a pair of upper and lower flat rolls, wherein the preheating temperature in the step of obtaining the preheated web is 30°C or more and 90°C or less, and the first fiber web and the second fiber web satisfy the following formulas 3 and 4. 0.10≦P C1 ≦0.70 (Equation 3) 0.10≦P C2 -P C1 ≦0.55 (Equation 4). Here, P C1 This is the area ratio (unitless) of the core component in the cross-section of the first core-sheath type composite fiber, P C2 This is the area ratio (unitless) of the core component in the cross-section of the second core-sheath type composite fiber.

[10] The thermoplastic resin B is a polyethylene resin, and the solid density of the polyethylene resin is 0.935 g / cm³ 3 More than 0.970g / cm 3A method for producing a spunbond nonwoven fabric as described in any of the following [7] to [9].

[11] Packaging material comprising a spunbond nonwoven fabric as described in any of [1] to [6]. [Effects of the Invention]

[0008] According to the present invention, a spunbond nonwoven fabric with excellent tear strength, fuzz resistance, and printability, and a packaging material made using the same can be obtained. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a cross-sectional photograph in the thickness direction of the resin-embedded spunbond nonwoven fabric of the present invention. [Figure 2] Figure 2 illustrates the fibers coated with the countable thermoplastic resin B in Figure 1, and the smallest rectangle that can cover all of the countable fibers. [Figure 3] Figure 3 is a magnified photograph of a portion of Figure 1, illustrating the measurement section used when measuring the cross-sectional area of ​​a fiber made of thermoplastic resin A. [Modes for carrying out the invention]

[0010] The spunbond nonwoven fabric of the present invention is a spunbond nonwoven fabric comprising fibers composed of a thermoplastic resin A mainly composed of a polyester resin, wherein at least some of the fibers are coated with a thermoplastic resin B mainly composed of a polyolefin resin.

[0011] The components of the present invention will be described in detail below, but the present invention is not limited in any way to the scope described below, as long as it does not exceed the gist of the invention.

[0012] [Thermoplastic resin A] The fibers constituting the spunbond nonwoven fabric of the present invention contain a thermoplastic resin A, mainly composed of a polyester resin, as a constituent component. This allows for the production of a spunbond nonwoven fabric with sufficient strength and rigidity for practical use. In this invention, "polyester resin" refers to various polyester resins such as polyethylene terephthalate (described later), mixtures thereof, copolymers, and resins to which additives have been added. Hereafter, unless otherwise specified, the same applies to any mention of "...-type resin."

[0013] Polyester resins primarily consist of high-molecular polymers composed of acid and alcohol components as monomers. In this invention, "primarily consisting of..." means that the mass ratio of the said component to the total mass is greater than 50% by mass. Hereafter, unless otherwise specified, the same applies to any description of "primarily consisting of...".

[0014] As acidic components, aromatic carboxylic acids such as phthalic acid (ortho form), isophthalic acid, and terephthalic acid, aliphatic dicarboxylic acids such as adipic acid and sebacic acid, and alicyclic dicarboxylic acids such as cyclohexanecarboxylic acid can be used. As alcoholic components, ethylene glycol, diethylene glycol, and polyethylene glycol can be used.

[0015] Examples of polyester resins include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polylactic acid (PLA), and polybutylene succinate (PBS). Among these, PET is preferred because it has a high melting point, excellent heat resistance, and also possesses excellent strength and rigidity.

[0016] The thermoplastic resin A used in the present invention preferably contains 70% by mass or more of the above-mentioned polyester resin. Preferably, by containing 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more of the polyester resin, a spunbond nonwoven fabric with excellent strength and rigidity can be obtained. The upper limit is preferably 100% by mass, as this allows for a spunbond nonwoven fabric with excellent strength and rigidity.

[0017] Furthermore, the polyester resin used in the present invention may be a mixture of two or more types. In addition to the main polyester resin (referring to the polyester that accounts for the largest mass% in the polyester resin), a resin composition containing polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polytrimethylene terephthalate (PTT), polyolefin resins, thermoplastic elastomers, and thermoplastic resins such as low-melting-point polyamides may also be used. However, in order to fully express the properties of the main polyester resin, the ratio of the other thermoplastic resins mixed is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less.

[0018] Furthermore, thermoplastic resin A may contain, as necessary, commonly used additives such as antioxidants, weather stabilizers, light stabilizers, heat stabilizers, antistatic agents, antistatic additives, anti-fogging agents, anti-blocking agents, matting agents, antifungal agents, antibacterial agents, antiviral agents, flame retardants, metal oxides, hydrophilic agents, nucleating agents, pigments, lubricants including polyethylene wax, aliphatic bisamides and / or aliphatic monoamides, or other polymers, provided that the effects of the present invention are not impaired.

[0019] The melting point of thermoplastic resin A is preferably 200°C or higher and 320°C or lower. A spunbond nonwoven fabric with excellent heat resistance can be obtained when the melting point of thermoplastic resin A is preferably 200°C or higher, more preferably 220°C or higher, and even more preferably 240°C or higher. On the other hand, when the melting point of thermoplastic resin A is preferably 320°C or lower, more preferably 300°C or lower, and even more preferably 280°C or lower, it is possible to suppress thermal degradation of thermoplastic resin B, which has a lower melting point than thermoplastic resin A (described later), during the production of the spunbond nonwoven fabric, resulting in a spunbond nonwoven fabric with excellent quality. In addition, the yarn discharged from the spinneret is easier to cool, excessive fusion between fibers is suppressed, and a spunbond nonwoven fabric with excellent uniformity of form is obtained.

[0020] Here, the melting point of thermoplastic resin A refers to the maximum melting peak temperature obtained by measuring thermoplastic resin A using differential scanning calorimetry (DSC). When measuring the melting point of thermoplastic resin A from spunbond nonwoven fabric or the fibers constituting it, the value calculated by the following procedure shall be adopted. (1) Take one random small piece from the spunbond nonwoven fabric weighing between 0.5 mg and 5 mg as a sample. When measuring from the raw fibers, cut the fibers or otherwise obtain a fiber piece weighing between 0.5 mg and 5 mg as a sample. (2) For the sample from (1), differential scanning calorimeter (DSC, e.g., PerKin-Elmer's "DSC 8500", TA Instruments' "Q2000", etc.) is used to perform differential scanning calorimeter measurements twice under conditions of heating and cooling rates of 20°C / min, from room temperature to 350°C, and a DSC curve is obtained. (3) Read the peak top temperature (melting peak temperature) of the melting endothermic peak from the DSC curve during the second heating, and set the highest melting peak temperature as the melting point of thermoplastic resin A.

[0021] Furthermore, since the small piece being measured also contains thermoplastic resin B, it is possible to measure this simultaneously. If there is concern that the thermoplastic resin B being measured will deteriorate due to the temperature increase up to the upper limit of the temperature range described in (2) above, it is also possible to lower the upper limit of the temperature range to about 290°C, as long as the melting endothermic peaks of thermoplastic resins A and B can be obtained.

[0022] Furthermore, when measuring from the raw material polymer, thermoplastic resin A, take a sample of 0.5 mg to 5 mg, perform the procedure in (2), read the peak top temperature (melting peak temperature) of the melting endothermic peak from the DSC curve during the second heating, and set the obtained melting peak temperature as the melting point of thermoplastic resin A.

[0023] The intrinsic viscosity (IV) of thermoplastic resin A is preferably 0.55 or more and 0.75 or less. When the intrinsic viscosity (IV) is preferably 0.55 or more, more preferably 0.60 or less, and even more preferably 0.62 or more, the single filament strength is increased. On the other hand, when the intrinsic viscosity (IV) is preferably 0.75 or less, more preferably 0.70 or less, and even more preferably 0.68 or less, the spindle properties when manufacturing the spunbond nonwoven fabric can be improved, and a spunbond nonwoven fabric of superior quality can be obtained.

[0024] In this invention, the intrinsic viscosity (IV) of thermoplastic resin A shall be the value obtained by the following method. (1) Dissolve 8 g of the sample in 100 mL of orthochlorophenol, and measure the relative viscosity η at a temperature of 25°C using an Ostwald viscometer according to the following formula. r To seek η r =η / η0=(t×d) / (t0×d0) ···(Formula). Here, η is the viscosity of the polymer solution, η0 is the viscosity of orthochlorophenol, t is the fall time of the solution (seconds), and d is the density of the solution (g / cm³). 3 ), t0 is the fall time of orthochlorophenol (seconds), and d0 is the density of orthochlorophenol (g / cm³). 3 ) represents. (2) Relative viscosity η r Therefore, calculate the intrinsic viscosity (IV) using the following formula and round it to the third decimal place. Intrinsic viscosity (IV)=0.0242ηr+0.2634 (formula).

[0025] [Thermoplastic resin B] The spunbond nonwoven fabric of the present invention further contains a thermoplastic resin B, which is mainly composed of a polyolefin resin, as a constituent component.

[0026] The melting point of thermoplastic resin B is lower than that of thermoplastic resin A, and the melting point of thermoplastic resin B is (T m,B )℃ and the melting point (T) of thermoplastic resin A m,A The difference from )℃ is between 50℃ and 180℃. (T m,B )℃ is (T m,A By having a melting point that is 50°C or more, preferably 70°C or more, and more preferably 80°C or more lower than )°C, adhesion to thermal calender rolls and the like in the manufacturing process described later is suppressed, resulting in a spunbond nonwoven fabric with excellent strength. m,B )℃ and the melting point (T) of thermoplastic resin A m,A By keeping the temperature difference from 180°C or less, more preferably 150°C or less, polymer degradation during spinning is suppressed, resulting in a spunbond nonwoven fabric with excellent productivity and quality.

[0027] Here, the melting point of thermoplastic resin B refers to the maximum melting peak temperature obtained by measuring thermoplastic resin B using differential scanning calorimetry (DSC). When measuring the melting point of thermoplastic resin B from spunbond nonwoven fabric, the value calculated by the following procedure shall be adopted. (1) Take one random small piece of spunbond nonwoven fabric weighing between 0.5 mg and 5 mg as a sample. If measuring from raw fibers, cut the fibers to obtain a fiber piece weighing between 0.5 mg and 5 mg as a sample. (2) For the sample from (1), differential scanning calorimeter (DSC, e.g., PerKin-Elmer's "DSC 8500", TA Instruments' "Q2000", etc.) is used to perform differential scanning calorimeter measurements twice under nitrogen conditions, heating and cooling rates of 20°C / min, and conditions from room temperature to 350°C, and a DSC curve is obtained. (3) Read the peak top temperature (melting peak temperature) of the melting endothermic peak from the DSC curve during the second heating, and set the lowest melting peak temperature as the melting point of thermoplastic resin B.

[0028] Furthermore, if there are concerns about the degradation of the thermoplastic resin B being measured by raising the temperature to the upper limit of the temperature range described in (2) above, it is also possible to lower the upper limit of the temperature range to approximately 280°C, as long as the melting endothermic peak of thermoplastic resin B can be measured.

[0029] Furthermore, when measuring from the raw material polymer, thermoplastic resin B, take a sample of 0.5 mg to 5 mg, perform the procedure in (2), read the peak top temperature (melting peak temperature) of the melting endothermic peak from the DSC curve during the second heating, and define the obtained melting peak temperature as the melting point of thermoplastic resin B.

[0030] Furthermore, the melting point of thermoplastic resin B is preferably 100°C or higher and 240°C or lower. When the melting point of thermoplastic resin B is preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher, a spunbond nonwoven fabric with heat resistance suitable for practical use is obtained. On the other hand, when the melting point of thermoplastic resin B is preferably 240°C or lower, more preferably 210°C or lower, and even more preferably 180°C or lower, it prevents the sheet from sticking to the heating roll during heat bonding, preventing distortion and wrinkles from occurring in the sheet and reducing its quality, while also improving heat adhesion and resulting in a spunbond nonwoven fabric with excellent strength and rigidity.

[0031] Examples of thermoplastic resin B include polyethylene resins, polypropylene resins, polybutene resins, and polymethylpentene resins. Polyolefin resins are suitable for applications requiring heat adhesion, and among them, polyethylene resins and polypropylene resins are preferred due to their excellent spinnability. Furthermore, polyethylene resins are more preferably used because they can be heat-bonded at lower temperatures.

[0032] Polyethylene resins refer to resins having ethylene units as repeating units, and include ethylene homopolymers or copolymers of ethylene and various α-olefins. Among these, ethylene homopolymers are preferred in order to prevent a decrease in spinning stability and strength. As copolymers of ethylene and various α-olefins, copolymers of ethylene and α-olefins having 3 to 5 carbon atoms are preferred. Examples of α-olefins having 3 to 5 carbon atoms include propylene, 1-butene, and 1-pentene, with 1-butene being more preferred. By doing so, entanglement of molecular chains during melting is suppressed, preventing yarn breakage, and the increase in amorphous components prevents the sheet from sticking to the heating roll during heat bonding, which can cause distortion and wrinkles and reduce quality.

[0033] When using copolymers of ethylene and various α-olefins, the copolymerization ratio of the α-olefin is preferably 0.1 mol% to 10 mol% relative to the polymerization component of the polyethylene resin. A copolymerization ratio of α-olefin of preferably 0.1 mol% to 10 mol%, more preferably 0.1 mol% to 7 mol%, and even more preferably 0.1 mol% to 5 mol%, suppresses yarn breakage during spinning and adhesion to heat calender rolls during the manufacturing process described later, resulting in a spunbond nonwoven fabric with fewer defects such as distortion and wrinkles.

[0034] The α-olefin species and α-olefin copolymerization ratio in the polymerization components of polyethylene resins can be calculated, for example, from the detected peak positions and peak area ratios obtained by nuclear magnetic resonance (NMR) spectroscopy.

[0035] Examples of polyethylene resins include medium-density polyethylene, high-density polyethylene (hereinafter sometimes abbreviated as HDPE), or linear low-density polyethylene (hereinafter sometimes abbreviated as LLDPE). Among these, HDPE or LLDPE are preferred because they suppress yarn breakage during spinning in the manufacturing process described later, resulting in a spunbond nonwoven fabric with fewer surface defects.

[0036] The melting point of the polyethylene resin is preferably 100°C or higher and 150°C or lower. A melting point of 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher makes it easier to obtain heat resistance that is suitable for practical use. Furthermore, a melting point of 150°C or lower, more preferably 140°C or lower, and even more preferably 135°C or lower makes it easier to cool the yarn extruded from the spinneret in the manufacturing process described later, suppressing the fusion of fibers, resulting in a spunbond nonwoven fabric with excellent uniformity of texture.

[0037] The solid density of polyethylene resin is 0.935 g / cm³. 3 More than 0.970g / cm 3 Preferably, the following conditions apply: The solid density of the polyethylene resin is preferably 0.935 g / cm³. 3 More preferably 0.940 g / cm³ 3 More preferably 0.945 g / cm³ 3 As a result of the above, adhesion to the thermal calender roll and other components in the manufacturing process described later is suppressed, resulting in a spunbond nonwoven fabric with fewer defects such as distortion and wrinkles. Furthermore, the solid density of the polyethylene resin is preferably 0.970 g / cm³. 3 More preferably, 0.965 g / cm³ 3 More preferably, 0.960 g / cm³ 3 As a result of the following, yarn breakage during spinning in the manufacturing process described later is suppressed, resulting in a spunbond nonwoven fabric with fewer surface defects.

[0038] In this invention, the solid density (g / cm³) of the polyethylene resin is specified. 3 The value to be used shall be the value calculated by the following procedure. (1) Soak the polyethylene resin in ethanol to wash it, and then dry it in the open air. (2) The density of the dried resin is determined by the buoyancy method using a water-ethanol mixture. (3) Perform the same measurement five times using different resin pieces and obtain the measured density value (g / cm³). 3 ) are averaged and rounded to the fourth decimal place to obtain the solid density of polyethylene resin (g / cm³). 3 )

[0039] On the other hand, examples of polypropylene resins include propylene homopolymers or copolymers of propylene with one or more olefins selected from ethylene and / or various α-olefins other than propylene (hereinafter collectively referred to as "α-olefins, etc."). Among these, propylene homopolymers are preferred in order to prevent a decrease in spinning stability and strength.

[0040] When using a copolymer of propylene and α-olefins, etc., ethylene and 1-butene are preferred as copolymer components due to their excellent spinning stability, with ethylene being more preferred. Furthermore, the copolymerization ratio is preferably 15 mol% or less, more preferably 10 mol% or less, and even more preferably 5 mol% or less, in order to prevent a decrease in spinning stability and strength.

[0041] The types of α-olefins and other compounds in the polymerization components of polypropylene resins, as well as the copolymerization ratio of α-olefins and other compounds, can be calculated, for example, from the detected peak positions and peak area ratios obtained by nuclear magnetic resonance (NMR) spectroscopy.

[0042] The melting point of the polypropylene resin is preferably 120°C or higher and 180°C or lower. A melting point of 120°C or higher, more preferably 130°C or higher, and even more preferably 140°C or higher makes it easier to obtain heat resistance that is suitable for practical use. Furthermore, a melting point of 180°C or lower, more preferably 170°C or lower, and even more preferably 160°C or lower makes it easier to cool the yarn extruded from the spinneret, suppressing fusion between fibers and resulting in a spunbond nonwoven fabric with excellent uniformity of texture.

[0043] Furthermore, the polyolefin resin according to the present invention may be a mixture of two or more types. In addition to the main polyolefin resin (referring to the polyolefin that accounts for the largest mass% in the polyolefin resin), a resin composition containing polyolefin resins such as polyethylene, polypropylene, and poly-4-methyl-1-pentene, thermoplastic elastomers, low-melting-point polyesters, and low-melting-point polyamides may also be used. However, in order to fully express the properties of the main polyolefin resin, the ratio of the other thermoplastic resins mixed is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less.

[0044] Furthermore, the thermoplastic resin B may, as necessary, contain additives such as commonly used antioxidants, weather stabilizers, light stabilizers, heat stabilizers, antistatic agents, antistatic additives, fogging agents, antiblocking agents, matting agents, antibacterial agents, antifungal agents, antiallergens, antiviral agents, vitamins, flame retardants, metal oxides, hydrophilic agents, nucleating agents, pigments, lubricants including polyethylene wax, aliphatic bisamides and / or aliphatic monoamides, or other polymers, within the limits that do not impair the effects of the present invention.

[0045] The melt flow rate (hereinafter sometimes abbreviated as MFR) of thermoplastic resin B is preferably 1 g / 10 min or more and 100 g / 10 min or less. When the MFR of thermoplastic resin B is preferably 1 g / 10 min or more, more preferably 10 g / 10 min or more, and even more preferably 20 g / 10 min or more, yarn breakage during spinning in the manufacturing process described later is suppressed, resulting in a spunbond nonwoven fabric with fewer surface defects. On the other hand, when the MFR of thermoplastic resin B is preferably 100 g / 10 min or less, more preferably 80 g / 10 min or less, and even more preferably 60 g / 10 min or less, the single yarn strength is increased, resulting in a spunbond nonwoven fabric with excellent strength and rigidity. Of course, the MFR of the polyolefin resin used in the present invention can also be adjusted by blending two or more resins with different MFRs in any proportion.

[0046] The MFR of this thermoplastic resin B will be the value measured by ASTM D1238-10 "Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer" (Method A). According to this standard, polyethylene is measured at a load of 2.16 kg and a temperature of 190°C, and polypropylene is measured at a load of 2.16 kg and a temperature of 230°C.

[0047] Furthermore, while resins containing petroleum-derived components or biomass-derived components can be used as polyolefin resins, resins containing biomass-derived components are preferred. It is also preferable that the biomass-derived carbon accounts for 20% or more of the total carbon content of the polyolefin resin, more preferably 50% or more, and even more preferably 90% or more. This results in a spunbond nonwoven fabric with a low environmental impact.

[0048] Furthermore, the polyolefin resin of the present invention includes not only newly obtained polyolefin resins obtained by polymerizing biomass-derived components, but also recycled polyolefin resins that contain biomass-derived polyolefin resins.

[0049] The proportion of carbon atoms derived from biomass is measured by the carbon-14 concentration measurement method using accelerator mass spectrometry (Method B) described in ASTM D6866-22, "Standard Test Methods for Determining the Biobased Content of Solid, Liquid, and Gaseous Samples Using Radiocarbon Analysis." This method allows us to determine whether a component is derived from biomass or petroleum based on the amount of radioactive isotopes of the carbon atoms. If all carbon atoms are derived from biomass, the proportion of biomass-derived carbon atoms will be 100%.

[0050] [fiber] The spunbond nonwoven fabric of the present invention contains fibers made of the thermoplastic resin A.

[0051] Furthermore, the fibers made of the thermoplastic resin A are coated with a thermoplastic resin B, which is mainly composed of polyolefin resin, on the periphery of at least a portion of the fibers.

[0052] By coating at least a portion of the periphery of the fibers, which are composed of the aforementioned thermoplastic resin A, with a thermoplastic resin B mainly composed of polyolefin resin, the fibers are bonded by the thermoplastic resin B while maintaining their strength, resulting in a spunbond nonwoven fabric with high tear strength.

[0053] Here, "at least a portion of the fiber's periphery is coated with thermoplastic resin B" means that at least a portion of the fiber's periphery is in contact with the thermoplastic resin.

[0054] Then, as the cross-sectional shape of the fiber, in addition to a round cross-section, a flat cross-section, and irregular cross-sections such as Y-type and C-type are also acceptable. Among these, a round cross-section is a more preferred embodiment, as it exhibits excellent spinnability and allows production of composite fibers with excellent single-yarn strength by spinning at a high spinning speed. A hollow cross-section may also be applied as the cross-sectional shape, but a solid cross-section is a preferred embodiment, as it suppresses yarn breakage during spinning in the manufacturing process described later and results in a spunbond nonwoven fabric with few surface defects.

[0055] Further, the fibers composed of thermoplastic resin A that constitute the spunbond nonwoven fabric of the present invention preferably have an average single fiber diameter of 3.5 μm or more and 25.0 μm or less. Regarding this range of the average single fiber diameter, when the lower limit is preferably 3.5 μm or more, more preferably 3.8 μm or more, and even more preferably 4.1 μm or more, a spunbond nonwoven fabric with excellent air permeability can be obtained. On the other hand, when the upper limit of the aforementioned range is preferably 25.0 μm or less, more preferably 20.0 μm or less, even more preferably 18.0 μm or less, and particularly preferably 15.0 μm or less, the texture of the spunbond nonwoven fabric becomes good, and the spunbond nonwoven fabric with small variations in strength and rigidity can be obtained.

[0056] Further, for the fibers composed of thermoplastic resin A that constitute the spunbond nonwoven fabric of the present invention, when the fiber diameter of the fibers made of thermoplastic resin A in the portion on one surface side is defined as R1 (μm), and the fiber diameter of the fibers made of thermoplastic resin A in the portion on the other surface side is defined as R2 (μm), it is preferable that R1 / R2 satisfies either of the following Formula 1 or Formula 2 R1<R2···(Formula 1) 0.50≦R1 / R2≦0.95 ···(Formula 2). Here, R1 (μm) is the fiber diameter of the fibers made of thermoplastic resin A in the portion on one surface side of the spunbond nonwoven fabric, R2 (μm) is the fiber diameter of the fibers made of thermoplastic resin A in the portion on the other surface side of the spunbond nonwoven fabric.

[0057] When R1 / R2 is preferably 0.50 or higher, more preferably 0.60 or higher, and even more preferably 0.70 or higher, the thermoplastic resin B is uniformly distributed between the fibers, resulting in a spunbond nonwoven fabric with excellent tear strength. On the other hand, when R1 / R2 is preferably 0.95 or lower, more preferably 0.90 or lower, and even more preferably 0.85 or lower, a difference in the amount of thermoplastic resin B is created between the front and back surfaces, resulting in a nonwoven fabric with excellent heat-sealability.

[0058] To satisfy equations 1 and 2 above, it is sufficient to satisfy equations 3 and 4, which will be described later.

[0059] Furthermore, the fiber diameter of the thermoplastic resin A fibers constituting the spunbond nonwoven fabric, and the fiber diameter R1 of the thermoplastic resin A fibers on one surface side and the fiber diameter R2 of the thermoplastic resin A fibers on the other surface side shall be the values ​​calculated by the following procedure. (1) Take 10 small samples randomly from the spunbond nonwoven fabric. (2) The spunbond nonwoven fabric sample is embedded in bisphenol epoxy resin. (3) After the resin has hardened, sections are cut out using a freeze microtome so that the thickness direction of the spunbond nonwoven fabric becomes the cut surface. (4) For each small sample, cross-sectional photographs are taken at a magnification of 500x to 2000x using a microscope (e.g., Keyence Corporation's "VW-9000") or a scanning electron microscope (e.g., Keyence Corporation's "VHX-D500"). The cross-sectional photographs should be taken in the thickness direction of the spunbond nonwoven fabric (from one surface to the other). An example is shown in Figure 1. Figure 1 is a cross-sectional photograph of the resin-embedded spunbond nonwoven fabric of the present invention. Within the resin embedding (3), it can be observed that the outside of the fibers (1) made of thermoplastic resin A is covered by thermoplastic resin B (2). Ten cross-sectional photographs are taken from each sample, for a total of 100 cross-sectional photographs. (5) In the cross-sectional photograph, the cross-sectional area of ​​all fibers made of thermoplastic resin A is measured, and the diameter of a perfect circle with the same cross-sectional area is determined. An example of measuring the cross-sectional area of ​​the fibers is shown in Figure 3. Figure 3 is a magnified photograph of a part of Figure 1, and is a diagram to explain the measurement part when measuring the cross-sectional area of ​​fibers made of thermoplastic resin A. Specifically, Figure 3 is a magnified photograph of the part enclosed by the dashed line in Figure 1, and in Figure 3, the black line (5) is an example of the measurement part when measuring the cross-sectional area of ​​the fibers. (6) Average the diameter values ​​of all measured fibers and round to two decimal places to obtain the average single fiber diameter (μm).

[0060] Here, in the cross-sectional photograph described above, R1 (μm) is defined as the fiber diameter calculated from only the fibers in the 20% range from one surface side in the thickness direction of the spunbond nonwoven fabric, and R2 (μm) is defined as the fiber diameter calculated from only the fibers in the 20% range from the other surface side.

[0061] [Spunbond nonwoven fabric] The spunbond nonwoven fabric of the present invention includes fibers composed of the thermoplastic resin A. At least a portion of the fibers are coated with a thermoplastic resin B mainly composed of a polyolefin resin. Here, "at least a portion of the fibers are coated with thermoplastic resin B" means that at least a portion of the fibers are in contact with the thermoplastic resin B. In particular, it is preferable that the thermoplastic resin B, which is the sheath component of the core-sheath composite fiber, is heat-fused and coats the surrounding fibers composed of the remaining core component, thermoplastic resin A, while being fused and integrated with adjacent fibers (similarly, the thermoplastic resin B, which is the sheath component of the sheath-sheath composite fiber, coats the surrounding fibers composed of the remaining core component, thermoplastic resin A, during heat fusion).

[0062] In the present invention, the spunbond nonwoven fabric is preferable in that the thermoplastic resin A is a polyethylene terephthalate-based resin and the thermoplastic resin B is a polyethylene-based resin, as this allows for heat bonding at lower temperatures and provides superior strength and rigidity.

[0063] The basis weight of the spunbond nonwoven fabric of the present invention is 10 g / m². 2 More than 100g / m 2 The following is preferable: The basis weight is 10 g / m². 2 Preferably 15 g / m² 2 More than 20g / m 2 By doing so, a spunbond nonwoven fabric with mechanical strength suitable for practical use can be obtained. On the other hand, if the basis weight is 100 g / m² 2 Preferably 90 g / m 2 More preferably 80 g / m² 2 By doing the following, a spunbond nonwoven fabric with excellent processability and breathability for packaging materials can be produced.

[0064] In the present invention, the basis weight of the spunbond nonwoven fabric is measured according to the following procedure, in accordance with "6.2 Mass per unit area" of JIS L1913:2010 "General Test Methods for Nonwoven Fabrics". (1) Take three 20cm x 25cm test pieces for every 1m of width of the sample. (2) Weigh the mass (g) of each under standard conditions. (3) The average value is 1m 2 Mass per unit (g / m³) 2 It is represented as ).

[0065] The apparent density of the aforementioned spunbond nonwoven fabric is 0.30 g / cm³. 3 More than 1.40g / cm 3 Preferably, the apparent density is 0.30 g / cm³. 3 More preferably 0.35 g / cm³ 3 More preferably 0.40 g / cm³ 3 As a result of the above, the adhesion between fibers becomes strong, suppressing the occurrence of fuzzing and delamination, and making it possible to produce the spunbond nonwoven fabric with excellent tear strength. On the other hand, the apparent density is 1.40 g / cm³. 3 More preferably, 1.00 g / cm³ 3 More preferably, 0.70 g / cm³ 3The following conditions prevent the flexibility of the spunbond nonwoven fabric, which is suitable for packaging materials, from being compromised. The apparent density can be controlled by appropriately adjusting the average single fiber diameter and / or the heat bonding conditions described later (shape of the bonding area, heat fusion rate, temperature, and linear pressure, etc.).

[0066] Apparent density of spunbond nonwoven fabric (g / cm³) 3 ) is calculated by the following procedure. (1) The thickness (mm) of the spunbond nonwoven fabric is measured according to the following procedure in accordance with JIS L1913:2010 "General Test Methods for Nonwoven Fabrics" 6.1.1 "Method A". (A) Using a pressure probe with a diameter of 10 mm, measure the thickness of the spunbond nonwoven fabric at 10 points per meter at equal intervals in the width direction, to the nearest 0.01 mm, under a load of 10 kPa. (B) Round the average of the above 10 points to the third decimal place. (2) From the above weight and thickness before rounding, calculate the apparent density based on the following formula and round to the third decimal place. Apparent density (g / cm³) 3 )=[Balance (g / m 2 )] / [Thickness (mm)]×10 -3 ···(formula).

[0067] The spunbond nonwoven fabric of the present invention has an arithmetic mean roughness Ra of 1.0 μm or more and 15.0 μm or less on its surface. By setting Ra to 1.0 μm or more, more preferably 2.0 μm or more, and even more preferably 3.0 μm or more, a spunbond nonwoven fabric with excellent breathability can be obtained. On the other hand, by setting Ra to 15.0 μm or less, more preferably 10.0 μm or less, and even more preferably 7.5 μm or less, a spunbond nonwoven fabric with a smooth surface and excellent resistance to fluffing and printability can be obtained. The arithmetic mean roughness can be controlled by appropriately adjusting the preheating conditions (temperature, linear pressure, etc.) and heat bonding conditions (shape of the bonding area, heat fusion rate, temperature, and linear pressure, etc.) as described later.

[0068] In the present invention, the arithmetic mean roughness Ra of the surface of the spunbond nonwoven fabric shall be the value measured as follows, in accordance with "4.2.1 Arithmetic mean height of the contour curve" of JIS B0601:2013 "Geometric product specifications (GPS) - Surface texture: Contour curve method - Terms, definitions and surface texture parameters". (1) Take 100mm x 100mm test pieces from the spunbond nonwoven fabric, at equal intervals in the width direction of the spunbond nonwoven fabric, with 10 pieces per meter. (2) The test specimen is placed on the sample stage, and the contour curves in the longitudinal direction (longitudinal direction of the spunbond nonwoven fabric, i.e., MD direction) and transverse direction (width direction of the spunbond nonwoven fabric, i.e., CD direction) are measured on both sides of the spunbond nonwoven fabric, respectively, using a surface roughness measuring instrument (for example, the "SURFTEST SJ-210" compact surface roughness measuring instrument manufactured by Mitutoyo Corporation), and the arithmetic mean roughness Ra (μm) is calculated. (3) The arithmetic mean roughness Ra (μm) is calculated by averaging the measured values ​​of all test specimens on each side and rounding to the second decimal place.

[0069] This arithmetic mean roughness can be controlled by appropriately adjusting the average single fiber diameter of the fibers constituting the spunbond nonwoven fabric, the preheating temperature, or the heat fusion using a thermal calender roll before and after heat bonding.

[0070] The longitudinal tensile elongation of the spunbond nonwoven fabric of the present invention is 35% or more, preferably 35% to 90%. A longitudinal tensile elongation of 35% or more, preferably 40% or more, and more preferably 45% or more, results in a spunbond nonwoven fabric that possesses appropriate density and flexibility, and exhibits excellent tear strength. Furthermore, a longitudinal tensile elongation of preferably 90% or less, more preferably 80% or less, and even more preferably 70% or less, prevents excessive deformation of the spunbond nonwoven fabric, resulting in a spunbond nonwoven fabric excellent for use as a packaging material. In the spunbond nonwoven fabric of the present invention, at least a portion of the periphery of the fibers composed of the thermoplastic resin A is coated with a thermoplastic resin B mainly composed of a polyolefin resin. Therefore, the fibers are bonded via the thermoplastic resin B while maintaining their strength, resulting in a spunbond nonwoven fabric with appropriate tensile elongation.

[0071] The longitudinal tensile elongation can be controlled by appropriately adjusting the average single fiber diameter of the fibers, the MFR of thermoplastic resin A and thermoplastic resin B, the ratio of thermoplastic resin A to thermoplastic resin B, additives, the spinning rate described later, and the heat bonding conditions described later (shape of the bonded part, heat fusion rate, temperature, and linear pressure, etc.).

[0072] In the present invention, the longitudinal tensile elongation of the spunbond nonwoven fabric shall be determined in accordance with JIS L1913:2010 "General Test Methods for Nonwoven Fabrics," "6.3 Tensile Strength and Elongation (ISO Method)," and the value obtained by the following procedure shall be adopted. (1) Take three 50mm x 300mm test pieces for every 1m of spunbond nonwoven fabric width, with the longer side facing the longitudinal direction of the spunbond nonwoven fabric. (2) Grasp the test specimens and set them in the tensile testing machine at intervals of 200 mm. (3) A tensile test is conducted at a tensile speed of 100 mm / min, and the elongation at maximum strength is measured. The elongation is converted to a percentage (%).

[0073] The longitudinal direction of the spunbond nonwoven fabric in this invention is determined by the following method. If the longitudinal direction can be determined from the appearance of the spunbond nonwoven fabric, that is, if the winding direction on the nonwoven fabric roll can be uniquely determined, this direction shall be considered the longitudinal direction. On the other hand, if the longitudinal direction cannot be determined from the appearance, such as when the spunbond nonwoven fabric is cut or not in a roll, the longitudinal direction shall be determined by the following procedure. (1) Within the plane of the spunbond nonwoven fabric, one arbitrary direction is determined, and a test piece measuring 300 mm in length and 50 mm in width is taken along that direction. (2) Similarly, take test specimens measuring 300 mm in length and 50 mm in width from directions rotated 30, 60, and 90 degrees from the direction in which the specimen was taken. (3) For each test specimen in each direction, the maximum strength of each specimen is measured based on the above-mentioned method for measuring the tensile strength product per basis weight of the spunbond nonwoven fabric (2) to (3), the average value of the three points is calculated, and the value rounded to the first decimal place is taken as the tensile strength of the spunbond nonwoven fabric in each direction. (4) The direction in which the measured value is highest shall be considered the longitudinal direction of the spunbond nonwoven fabric. If there are two or more directions with the highest value, the direction in which the tensile strength in the direction perpendicular to those directions is lower shall be considered the longitudinal direction of the spunbond nonwoven fabric. If there are two or more directions with the highest value, and the tensile strength in the direction perpendicular to those directions is also equal, for example, if the tensile strength in all four directions is equal, then one of those four directions shall be considered the longitudinal direction.

[0074] The tensile strength product per basis weight of the aforementioned spunbond nonwoven fabric is 1.0 (N / 50mm) / (g / m 2 ) or more 8.0(N / 50mm) / (g / m 2 Preferably, the tensile strength-to-elongation product per basis weight is 1.0 (N / 50mm) / (g / m). 2 ) or more, more preferably 1.2 (N / 50mm) / (g / m 2 ) or more, more preferably 1.4 (N / 50mm) / (g / m 2By having a tensile strength product of 8.0 (N / 50mm) / (g / m²), a spunbond nonwoven fabric with excellent tear strength can be produced even at low basis weight. On the other hand, the tensile strength product per basis weight is preferably 8.0 (N / 50mm) / (g / m²). 2 ) or less, more preferably 7.0 (N / 50mm) / (g / m 2 ) More preferably 6.0 (N / 50mm) / (g / m 2 By keeping the following conditions in place, it is possible to prevent a decrease in the flexibility or deterioration of the texture of the spunbond nonwoven fabric.

[0075] The tensile strength product of the spunbond nonwoven fabric is determined by the MFR of the thermoplastic resins A and B, additives, average single fiber diameter of the fibers, the spinning rate described later, and the heat bonding conditions (shape of the bonded area, heat fusion). It can be controlled by appropriately adjusting factors such as the rate, temperature, and linear pressure.

[0076] In the present invention, the tensile strength-to-elongation product per basis weight of the spunbond nonwoven fabric shall be the value obtained by the following procedure, in accordance with "6.3 Tensile strength and elongation (ISO method)" of JIS L1913:2010 "General nonwoven fabric testing methods". (1) Take three 50mm x 300mm test pieces for every 1m of spunbond nonwoven fabric width, with the longer side facing the longitudinal direction of the spunbond nonwoven fabric. (2) Grasp the test specimens and set them in the tensile testing machine at intervals of 200 mm. (3) A tensile test is conducted at a tensile speed of 100 mm / min, and the maximum strength and elongation at maximum strength are measured. Here, the elongation is expressed as the ratio of the elongation to the initial gripping distance, not as a percentage (%). (4) Determine the average of the maximum strength and elongation at maximum strength measured for each test specimen, calculate the tensile strength-to-elongation product per unit weight based on the following formula, and round to two decimal places. Tensile strength product per unit weight ((N / 50mm) / (g / m) 2 )) = [Average value of maximum strength (N / 50mm)] × [Average value of elongation at maximum strength (-)] / Basis weight (g / m 2 )...(expression).

[0077] In the present invention, it is preferable that the fibers constituting the spunbond nonwoven fabric are bonded together by heat fusion via a thermoplastic resin B. In this way, the fibers composed of the thermoplastic resin A are firmly bonded via the thermoplastic resin B while maintaining their strength, resulting in a spunbond nonwoven fabric with excellent tear strength.

[0078] In the present invention, the average number density of fibers coated with the thermoplastic resin B, as observed in a cross-section in the thickness direction of the spunbond nonwoven fabric, is 100 fibers / mm². 2 Over 8000 threads / mm 2 Preferably, the average number density of the fibers coated with the thermoplastic resin B, as observed in a cross-section in the thickness direction of the spunbond nonwoven fabric, is preferably 100 fibers / mm². 2 More preferably 500 lines / mm 2 More preferably 1000 strands / mm 2 In particular, 1500 threads / mm 2 As a result, the fibers composed of thermoplastic resin A are bonded with thermoplastic resin B while maintaining their strength, making it possible to produce a spunbond nonwoven fabric with excellent tear strength. On the other hand, the average number density of the fibers is preferably 8000 fibers / mm². 2 More preferably, 7000 threads / mm 2 More preferably, 6000 threads / mm 2 As a result of the following, thermoplastic resin B can be sufficiently inserted between the fibers, improving adhesive strength, and thus enabling the production of a spunbond nonwoven fabric with excellent tear strength.

[0079] Furthermore, the average number density of fibers coated with the thermoplastic resin B, as observed in a cross-section in the thickness direction of the spunbond nonwoven fabric, shall be the value calculated by the following procedure. (1) Take 10 small samples randomly from the spunbond nonwoven fabric. (2) The spunbond nonwoven fabric sample is embedded in bisphenol epoxy resin. (3) After the resin has hardened, sections are cut out using a freeze microtome so that the thickness direction of the spunbond nonwoven fabric becomes the cut surface. (4) For each small sample, take cross-sectional images at magnifications of 500x to 2000x using a microscope (e.g., Keyence Corporation's "VW-9000") or a scanning electron microscope (e.g., Keyence Corporation's "VHX-D500"). Take 10 cross-sectional images from each sample, for a total of 100 images. An example is shown in Figure 1. (5) Count the number N of all fiber cross-sections observable in the cross-sectional photograph, where at least a portion of the fiber's periphery is covered with the thermoplastic resin B. Here, a fiber where at least a portion of the fiber's periphery is covered with the thermoplastic resin B means a state where at least a portion of the fiber's periphery is in contact with the thermoplastic resin B. In this case, if a fiber is located at the edge of the photograph and part of the fiber is cut off, that fiber shall not be counted. An example is shown in Figure 2. Figure 2 is an example diagram illustrating the countable fibers covered with thermoplastic resin B and the smallest rectangle that can cover all the fibers to be counted in Figure 1. To illustrate a countable fiber covered with thermoplastic resin B, an "x" mark is shown in the center of the fiber. This fiber is fiber (1) made of thermoplastic resin A. (6) The smallest rectangular area S that can cover all the fibers to be counted in the cross-sectional photograph. R (mm 2 ) is measured. An example is shown in Figure 2. This is an example of the smallest rectangle that can cover all of the countable fibers coated with thermoplastic resin B. The rectangle (4) is to cover the countable fibers coated with thermoplastic resin B scattered in the field of view, including the thermoplastic resin B (2) that covers the fibers (1) made of thermoplastic resin A. (7) For all photographs taken, the value calculated using the following formula, rounded to the first decimal place, is the average number density of fibers coated with the thermoplastic resin B, as observed in the cross-section in the thickness direction of the spunbond nonwoven fabric in each photograph. Average number density (number of threads / mm²) 2 )=N / SR ···(formula). The average of the average number density across all photographs taken will be used as the average number density of the spunbond nonwoven fabric.

[0080] In the present invention, it is preferable that the ratio of the number of fibers per unit area coated with the thermoplastic resin B to the number of fibers composed of the thermoplastic resin A, which mainly consists of the polyester resin, as observed in a cross-section in the thickness direction of the spunbond nonwoven fabric, is 70% or more and 100% or less. When the ratio of the number of fibers is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more, the fibers composed of the thermoplastic resin A are firmly bonded to the thermoplastic resin B while maintaining their fiber structure, resulting in a spunbond nonwoven fabric with excellent tear strength and resistance to fuzzing.

[0081] [Method for manufacturing spunbond nonwoven fabric] Next, preferred embodiments of the method for producing the spunbond nonwoven fabric of the present invention will be described in detail. The spunbond nonwoven fabric of the present invention is a long-fiber nonwoven fabric produced by the spunbond method. The spunbond method is excellent in terms of productivity and mechanical strength, and can suppress fluffing and fiber shedding that are common in short-fiber nonwoven fabrics. Furthermore, laminating multiple layers of collected spunbond nonwoven fiber webs or heat-fused spunbond nonwoven fabrics (both denoted as S) in layers such as SS, SSS, and SSSS is also a preferred embodiment because it improves productivity and uniformity of the fabric.

[0082] The present invention provides a method for producing a spunbond nonwoven fabric, comprising the steps of forming a fiber web composed of core-sheath type composite fibers, wherein the core component is a thermoplastic resin mainly composed of a polyester resin, and the sheath component is a thermoplastic resin mainly composed of a polyolefin resin; The process of obtaining a preheated web by bringing the heating surface of a heating device into contact with only one surface of the web and preheating it, The process involves heat-sealing the preheated web using a thermal calender roll consisting of a pair of upper and lower flat rolls, Includes, The preheating temperature in the process of obtaining the preheated web is set to be between 30°C and 90°C.

[0083] In the spunbond method, molten thermoplastic resin is first spun out as long fibers from a spinneret, which are then cooled and stretched, and finally collected on a moving net to form the material. Stretching may also be performed by suction using compressed air via an ejector or similar device.

[0084] The shape of the spinneret and ejector is not particularly limited, but various shapes such as round or rectangular can be used. Among these, a combination of a rectangular spinneret and a rectangular ejector is preferred because it uses relatively little compressed air, is energy-efficient, is less prone to fusing or friction between yarns, and facilitates yarn opening.

[0085] In this invention, thermoplastic resin A and thermoplastic resin B are melted in separate extruders, weighed, and supplied to a single spinneret to be spun out as a core-sheath type composite fiber.

[0086] The spinning temperature when spinning core-sheath type composite fibers is preferably 200°C to 320°C, more preferably 240°C to 300°C, and even more preferably 270°C to 290°C. By setting the spinning temperature within the above range, energy consumption during manufacturing is reduced, and a stable molten state is achieved while suppressing thermal degradation of thermoplastic resin A and thermoplastic resin B, resulting in excellent spinnability.

[0087] The spun filament yarn is then cooled. Methods for cooling the spun yarn include, for example, forcibly blowing cold air onto the yarn, allowing it to cool naturally with the ambient temperature around the yarn, and adjusting the distance between the spinneret and the ejector, or a combination of these methods can be employed. The cooling conditions can be appropriately adjusted considering the discharge rate per single hole of the spinneret, the spinning temperature, and the ambient temperature.

[0088] Next, the cooled and solidified yarn is pulled and drawn by compressed air jetted from an ejector.

[0089] The spinning speed is preferably 3000 m / min or more and 6500 m / min or less, more preferably 3500 m / min or more and 6000 m / min or less, and still more preferably 4000 m / min or more and 6500 m / min or less. By setting the spinning speed to 3000 m / min or more and 6500 m / min or less, not only high productivity is achieved, but also oriented crystallization of the fibers can be promoted, so high-strength long fibers can be obtained. The spinning speed can be controlled by appropriately adjusting the spinning temperature, the discharge rate per single hole of the spinneret, the distance between the spinneret and the ejector, the conditions for cooling the spun yarn (temperature of cooling air, air volume, etc.), and the like.

[0090] Subsequently, the obtained long fibers are collected on a moving net to obtain a fiber web.

[0091] In the present invention, when obtaining the above fiber web, a preferred embodiment also includes a step of forming a first fiber web composed of first core-sheath type composite fibers, and a step of forming a second fiber web composed of second core-sheath type composite fibers on the first fiber web to form a laminated web. At this time, the second fiber web may be formed directly on the first fiber web, or one or more other fiber webs may be formed on the first fiber web, and the second fiber web may be formed thereon.

[0092] Here, in the first fiber web and the second fiber web, the core component is a thermoplastic resin A containing a polyester-based resin as a main component, and the sheath component is a thermoplastic resin B containing a polyolefin-based resin as a main component. It is preferable that the first fiber web and the second fiber web satisfy the following Formulae 3 and 4 0.10≦P C1 ≦0.70 ···(Formula 3) 0.10≦P C2 -P C1 ≦0.55 ···(Formula 4). Here, P C1is the area ratio (unitless) of the core component in the cross section of the first core-sheath composite fiber, and P C2 is the area ratio (unitless) of the core component in the cross section of the second core-sheath composite fiber. By this means, sticking to hot embossing rolls and the like in the heat sealing step is particularly suppressed, and a spunbonded nonwoven fabric with particularly excellent heat seal processability is obtained.

[0093] In the present invention, when obtaining the above fiber web, a preferred embodiment also includes a step of forming a second fiber web composed of the second core-sheath composite fiber, and a step of forming a first fiber web composed of the first core-sheath composite fiber on the second fiber web to form a laminated web. At this time, the first fiber web may be directly formed on the second fiber web, or one or more other fiber webs may be formed on the second fiber web, and the first fiber web may be formed thereon.

[0094] Here, in the first fiber web and the second fiber web, the core component is a thermoplastic resin A containing a polyester-based resin as the main component, and the sheath component is a thermoplastic resin B containing a polyolefin-based resin as the main component. It is preferable that the first fiber web and the second fiber web satisfy the following Formulas 3 and 4 0.10≦P C1 ≦0.70 ···(Formula 3) 0.10≦P C2 -P C1 ≦0.55 ···(Formula 4). Here, P C1 is the area ratio (unitless) of the core component in the cross section of the first core-sheath composite fiber, and P C2 is the area ratio (unitless) of the core component in the cross section of the second core-sheath composite fiber.

[0095] To achieve the above range, spinning may be performed by adjusting the area ratio of the core component of the first core-sheath composite fiber so as to satisfy the above Formula 3, and spinning may be performed so that the area ratio of the core component of the second core-sheath composite fiber satisfies Formula 4.

[0096] The spunbond nonwoven fabric produced in the manner described above has a different area ratio of the sheath component of the core-sheath composite fiber between one surface and the other surface. When the surface with a smaller area ratio of the core component is used as the bonding side for heat sealing, good adhesive strength is obtained, while fusion to the heat sealing machine is suppressed on the other surface, resulting in particularly good processability. Furthermore, because the area ratio of the core component is relatively high on the other surface, it exhibits a particularly desirable effect in that the strength of the heat-sealed product is also excellent.

[0097] In this invention, it is also preferable to preheat the obtained fiber web by contacting it with a heated flat roll. This prevents the surface layer of the fiber web from peeling or being blown away during transport, which can worsen the fabrication, and improves transportability from the collection of the yarn to heat fusion. In the preheating process, it is preferable to preheat by contacting only one surface of the laminated web with the heating surface of the heating device. Preferred preheating methods include fusing the collected fiber web with an upper and lower pair of flat rolls, or installing a flat roll or heating plate above a net conveyor and fusing the web between the net conveyor and the flat roll or heating plate. In this way, a spunbond nonwoven fabric with excellent surface smoothness and virus barrier properties can be obtained while maintaining breathability. The "flat rolls" used in these methods refer to metal rolls or elastic rolls with no irregularities on the surface of the roll, and further, an upper and lower pair of flat rolls refers to a pair of metal rolls, or a pair of metal rolls and an elastic roll. Here, an elastic roll is a roll made of a material that has elasticity compared to a metal roll. Examples of elastic rolls include so-called paper rolls made of paper, cotton, or aramid paper, as well as resin rolls made of urethane resin, epoxy resin, silicone resin, polyester resin, hard rubber, or mixtures thereof.

[0098] In this preheating process, when fusion is performed using a pair of upper and lower flat rolls, only one of the flat rolls should be the heating surface. To illustrate one embodiment, one flat roll has a heating mechanism such as a heater and is heated to a temperature described later (a heated roll), while the other flat roll either does not have such a heating mechanism or, even if it has a heating mechanism, the heater switch is turned off. In this embodiment, the "heated surface" refers to the surface of the heated roll.

[0099] In this preheating process, a flat roll is installed above the net conveyor, and preheating is carried out between the net conveyor and the flat roll. Preferably, the flat roll is made of metal, and a heating mechanism such as a heater is provided only on this flat roll, and it is heated to the temperature described later. This flat roll is the heated roll, and the surface of this heated roll is the "heated surface" mentioned above.

[0100] Furthermore, in this preheating process, if a heating plate is installed above the net conveyor and preheating occurs between the net conveyor and the heating plate, the heating plate is preferably made of metal, and a heating mechanism such as a heater is provided only on this heating plate, and it is heated to the temperature described later. The surface of this heating plate that is in contact with the fiber web is the "heating surface".

[0101] In the present invention, it is preferable that the temperature of the heating surface during preheating is 30°C or higher and 90°C or lower. By setting the temperature of the heating surface to 30°C or higher, more preferably 35°C or higher, and even more preferably 40°C or higher, the thermal crystallization of the fibers can be promoted before heat fusion, preventing the air permeability of the spunbond nonwoven fabric from being impaired after heat fusion. Furthermore, it is possible to prevent the surface layer of the nonwoven fabric from peeling or being blown away during transport on the net, thereby preventing deterioration of the fabric's structure and improving transportability from yarn collection to heat fusion. On the other hand, by setting the surface temperature to 90°C or lower, more preferably 80°C or lower, and even more preferably 75°C or lower, the thermal crystallization of the fibers before heat fusion can be suppressed, resulting in a spunbond nonwoven fabric with higher surface smoothness, better resistance to fluffing, and superior printability. In addition, when a flat roll is used in the preheating process, it is preferable that the linear pressure of the heating surface is 1 N / cm or higher and 100 N / cm or lower. By setting the lower limit of the aforementioned linear pressure range to 1 N / cm or more, preferably 5 N / cm or more, the fiber web on the heating surface can be sufficiently preheated. On the other hand, by setting the upper limit of the aforementioned range to 100 N / cm or less, preferably 50 N / cm or less, heat can be transferred to the interior of the fiber web on the heating surface, suppressing thermal crystallization and enabling sufficient fusion during thermal bonding.

[0102] Next, the obtained fiber web is heat-fused. The method for heat-fusing the fiber web is not particularly limited as long as it satisfies the arithmetic mean roughness Ra specified in the present invention, but it is preferable to use a thermal calender roll consisting of a combination of an upper and lower pair of flat (smooth) rolls. In this way, a spunbond nonwoven fabric with high surface smoothness, excellent fuzz resistance and printability can be obtained.

[0103] The surface temperature of the thermal calender roll in the heat fusion process is determined by the melting point (T) of the thermoplastic resin B being used. m,B ) vs (T m,B -30)℃ or higher (T m,B It is preferable that the surface temperature of the thermocalender roll be (T) or lower. m,B -30°C or higher, more preferably (T m,BBy setting the temperature to -25°C or higher, a spunbond nonwoven fabric with sufficient strength for practical use can be obtained through appropriate fusion. m,B (T)℃ or lower, more preferably (T m,B (T)℃ or lower, more preferably (T m,B By keeping the temperature below +4°C, excessive fusion is suppressed, and the spunbond nonwoven fabric can be obtained with appropriate breathability and processability suitable for use as a packaging material.

[0104] The linear pressure of the thermal calender roll during heat bonding is preferably 50 N / cm or more and 500 N / cm or less. By setting the linear pressure of the roll to preferably 50 N / cm or more, more preferably 100 N / cm or more, and even more preferably 150 N / cm or more, strong heat bonding can be achieved, and a spunbond nonwoven fabric with strength suitable for practical use can be obtained. On the other hand, by setting the linear pressure of the thermal calender roll to preferably 500 N / cm or less, more preferably 400 N / cm or less, and even more preferably 300 N / cm or less, it is possible to suppress a decrease in tear strength due to excessive heat bonding.

[0105] Furthermore, in this invention, in order to adjust the thickness and surface roughness of the spunbond nonwoven fabric, thermal fusion can be performed using a thermal calender roll consisting of a pair of upper and lower flat rolls before and / or after thermal bonding with the thermal calender roll described above. The pair of upper and lower flat rolls are metal rolls or elastic rolls with no irregularities on the surface of the rolls, and can be used in pairs of metal rolls or metal rolls and elastic rolls.

[0106] Furthermore, an elastic roll, in this context, refers to a roll made of a material that has elasticity compared to a metal roll. Examples of elastic rolls include so-called paper rolls such as paper, cotton, and aramid paper, as well as resin rolls made of urethane resin, epoxy resin, silicone resin, polyester resin, hard rubber, and mixtures thereof.

[0107] Furthermore, the spunbond nonwoven fabric of the present invention may be post-processed to have functional agents such as antibacterial agents, antifungal agents, anti-allergen agents, antiviral agents, vitamins, and flame retardants attached to the fiber surface. In particular, when the spunbond nonwoven fabric of the present invention is used as a filter, the effect of imparting these functionalities can be significantly enhanced compared to conventional filters.

[0108] Methods for applying functional agents to the fiber surface include coating methods using gravure rolls, kiss rolls, impregnation methods, and spraying methods. Furthermore, because of their excellent safety and low environmental impact, the solvent used to dilute the functional agent is preferably water-based. Here, water-based solvents include water alone, or aqueous solutions containing water-soluble organic solvents such as lower alcohols like methanol and ethanol, lower ketones like acetone and methyl ethyl ketone, lower carboxylic acids like acetic acid, and glycols like ethylene glycol, propylene glycol, and diethylene glycol, which can be selected according to the purpose.

[0109] [Packaging material] The spunbond nonwoven fabric of the present invention has appropriate tensile elongation, excellent tear strength, fuzz resistance, and printability, making it suitable for various packaging materials such as desiccant packaging materials, food packaging materials, and wrapping packaging materials. In other words, the packaging material of the present invention includes the spunbond nonwoven fabric of the present invention. [Examples]

[0110] Next, the spunbond nonwoven fabric of the present invention will be described in detail based on the examples. However, the present invention is not limited to these examples.

[0111] [Measurement method] The evaluation methods and measurement conditions used in the examples are described below. Unless otherwise specified, the measurements of each physical property were performed based on the methods described above.

[0112] [1] Fiber diameter of the thermoplastic resin A fibers in the spunbond nonwoven fabric: Based on the method described above, the fiber diameter of the thermoplastic resin A fibers in the spunbond nonwoven fabric was measured.

[0113] [2] Basis weight of spunbond nonwoven fabric: Based on the method described above, the basis weight of the spunbond nonwoven fabric was measured.

[0114] [3] Heat fusion rate of spunbond nonwoven fabrics by embossing: The heat fusion rate of the spunbond nonwoven fabric in Comparative Example 2 due to embossing was calculated using the following method. (1) Ten small samples were randomly taken from the spunbond nonwoven fabric. (2) Using a scanning electron microscope, a "VHX-D500" manufactured by Keyence Corporation, a total of 10 images were taken from each sample at a magnification of 60x. At this time, the magnification was set so that the repeating units of the fusion zone were included in each image. (3) From each photograph, the area of ​​the fused portion and the area of ​​the smallest unit of the repeating embossing pattern were determined and averaged. Then, the thermal fusion rate was calculated using the following formula and rounded to the first decimal place. • Thermal fusion rate = (Area of ​​fused area) × (Number of fused areas in the smallest unit of the repeating pattern) / (Area of ​​the smallest unit of the repeating pattern) ... (Formula).

[0115] [4] Average number density of fibers coated with thermoplastic resin B: The average number density of fibers coated with thermoplastic resin B, which is the number of fibers coated with thermoplastic resin B per unit cross-sectional area in the thickness direction of the spunbond nonwoven fabric, was measured using a scanning electron microscope, the "VHX-D500" manufactured by Keyence Corporation, by the method described above.

[0116] However, for the spunbond nonwoven fabric of Comparative Example 2, that is, the spunbond nonwoven fabric having fused and unfused portions due to the heat embossing roll, the calculation was performed using the following method.

[0117] In taking cross-sectional photographs using the method described above, 10 photographs were taken from each sample, from the fused portion and the non-fused portion, for a total of 200 cross-sectional photographs. At this time, the entire thickness of the spunbond nonwoven fabric was captured in the photographs.

[0118] Average number density D of fused parts 融着部 and the average number density D of the non-fused section 非融着部 Each of these values ​​is calculated based on the method described above, and the value calculated by the following formula is rounded to the first decimal place to obtain the average number density. However, the thermal fusion rate by the thermal embossing roll is the one calculated using the method described above (without converting to a percentage). Average number density (number of threads / mm²) 2 )=D 融着部 (books / mm) 2 )×thermal fusion rate +D 非融着部 (books / mm) 2 )×(1-thermal fusion rate) ···(formula).

[0119] [5] The ratio of the number of fibers per unit area coated with thermoplastic resin B to the number of fibers composed of thermoplastic resin A, as observed in a cross-section in the thickness direction of the spunbond nonwoven fabric: A scanning electron microscope, the "VHX-D500" manufactured by Keyence Corporation, was used, and measurements were taken using the method described above.

[0120] [6] Arithmetic mean surface roughness Ra (μm): As a surface roughness measuring instrument, a compact surface roughness measuring instrument "SURFTEST SJ-210" manufactured by Mitutoyo Corporation was used, and measurements were taken using the method described above.

[0121] [7] Apparent density of spunbond nonwoven fabric (g / cm³) 3 ) Based on the method described above, the apparent density of the spunbond nonwoven fabric was calculated.

[0122] [8] Longitudinal tensile elongation (%) of spunbond nonwoven fabric Based on the method described above, the tensile elongation of the spunbond nonwoven fabric was calculated.

[0123] [9] Tear strength (N) of spunbond nonwoven fabric in the longitudinal and widthwise directions. The longitudinal tear strength of the spunbond nonwoven fabric was measured using an A&D Company, Limited "RTG-1250" constant-speed elongation tensile testing machine, in accordance with JIS L1913:2010 "General Test Methods for Nonwoven Fabrics" 6.4 "Tear Strength" a) trapezoid method, using the following method. (1) Three pieces of spunbond nonwoven fabric are taken at equal intervals in the width direction: one measuring 25 cm in the width direction and 5 cm in the length direction for measuring the tear strength in the longitudinal direction, and another measuring 25 cm in the length direction and 5 cm in the width direction for measuring the tear strength in the width direction. (2) Mark the specimen with an isosceles trapezoid shape, and make a 1.0 cm cut perpendicular to the shorter side in the center of the shorter side of the mark. (3) The test specimen is attached to the grips along the marks on a constant-speed elongation tensile testing machine with a gripping distance of 10 cm, the shorter side of the trapezoid being taut and the longer side being loosened. (4) Under the condition of a tensile speed of 100 ± 10 mm / min, the maximum load at which the fabric is torn is defined as the tear strength (N), and the average value of three points is calculated to determine the tear strength (N) of the spunbond nonwoven fabric. (5) The material has sufficient tear strength, with a longitudinal tear strength of 20 N or more and a widthwise tear strength of 30 N or more.

[0124]

[10] Printability of spunbond nonwoven fabrics: The following methods were used for evaluation. (1) Text was printed on spunbond nonwoven fabric in a size of 16pt using flexographic printing. (2) The tendency to fray was evaluated as ○ or × according to the following criteria. ◎: The text is clear and easy to read, without any blurring. ○: The letters are slightly blurred, but all letters are legible. ×: Some characters are blurred or illegible.

[0125]

[11] Fuzz resistance of spunbond nonwoven fabrics: The following methods were used for evaluation. (1) Cut out 10 pieces of spunbond nonwoven fabric, each measuring 15 cm in length and 15 cm in width, at five points at equal intervals in the width direction, one piece from each side of the spunbond nonwoven fabric. (2) Using the JSPS-type dye abrasion fastness tester "G-2" manufactured by Orihara Seisakusho, the abrasion test was performed with a load of 1.96N and 200 cycles of abrasion. (3) The pilling resistance was evaluated from A to C according to the following criteria. A rating of B or higher was judged as "sufficient pilling resistance". A: It doesn't fray. B: Multiple lint balls are visible. C: The thinner the test specimen, the more fibers are being stripped away.

[0126]

[12] Spunbond nonwoven fabrics, strong heat seal: Three samples measuring 130 mm in the longitudinal direction and 50 mm in the width direction were cut from the spunbond nonwoven fabric at three points per meter in the width direction, with two samples at each point. Two samples were placed on top of each other with the same faces touching, and the edges were heat-sealed 30 mm from the edge using a Fuji Impulse heat sealing machine (OPL-200) to create heat-sealed samples. The bonding temperature was set to be between 100°C and 160°C, and the bonding temperature of the sample was defined as the temperature at which the average value of the heat-seal strength measured by the method described below reached its maximum. The bonding time was set to 1 second. The heat-sealed samples were mounted on a constant-speed elongation tensile testing machine with a gripping distance of 100 mm, and a load was applied at a tensile speed of 100 mm / min until the test piece peeled or broke. The maximum strength at that time was defined as the heat-seal strength. Measurements were performed on both sides of the spunbond nonwoven fabric, and if there was a difference in heat-seal strength between the two sides, the larger value was adopted as the heat-seal strength of the spunbond nonwoven fabric. Furthermore, if the adhesive portion of the sample did not peel off but other parts broke, the strength value at the time of breakage was used.

[0127]

[13] Heat sealability When performing heat sealing of spunbond nonwoven fabric using the method described above, the processability of the surface where the heat sealing strength is greatest was evaluated as follows. ◎: The heat seal strength was 70N / 50mm or higher, and there was no fusion of the sample piece to the heat sealing machine during the heat sealing process, indicating good processability. ○: The heat seal strength was 50N / 50mm or higher, and there was no fusion of the sample piece to the heat sealing machine during the heat sealing process, indicating good processability. ×: Regardless of the heat seal strength, the sample piece fused to the heat sealing machine during the heat sealing process.

[0128] [Resin used] Next, we will describe in detail the resins used in the examples and comparative examples. • Polyester resin A: Dry with a moisture content of 50 ppm by mass or less, with an intrinsic viscosity (IV) of 0.65, a melting point of 260°C, and a solid density of 1.38 g / cm³. 3 Polyethylene terephthalate resin (labeled "PET" in Table 1) Polyethylene resin B: Melt flow rate (MFR) of 30 g / 10 min, melting point of 130°C, solid density of 0.955 g / cm³ 3 high-density polyethylene resin (referred to as "HDPE" in Tables 1-3) • Polyester resin C: Copolymerized polyethylene terephthalate, dried to a moisture content of 50 ppm by mass 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. (Denoted as "co-PET" in Table 1).

[0129] (Example 1) The aforementioned polyester resin A and polyethylene resin B were melted at temperatures of 295°C and 220°C, respectively. Then, using polyester resin A as the core component and polyethylene resin B as the sheath component, the fibers were spun from the pores of a concentric core-sheath composite spinneret at a spinneret temperature (corresponding to the spinning temperature) of 295°C, a core-to-sheath mass ratio of 60:40, and an extrusion rate of 0.55 g / min per pore. After the spun yarn was cooled and solidified, it was pulled and stretched in a rectangular ejector using compressed air at an ejector pressure of 0.30 MPa. The fibers were then piled up on a moving net conveyor, with the fiber arrangement restricted by a fiber-opening plate, and the fiber web was collected. The basis weight of the fiber web was 65 g / m². 2 The collected fiber web was preheated at 60°C and a linear pressure of 30 N / cm using a pair of upper and lower flat rolls. Then, it was heat-fused using a thermal calender roll consisting of a pair of upper and lower flat (smooth) rolls at a linear pressure of 300 N / cm and a heat bonding temperature of 130°C, resulting in a basis weight of 65 g / m². 2 A spunbond nonwoven fabric was obtained. The evaluation results are shown in Table 1.

[0130] (Example 2) A spunbond nonwoven fabric was obtained using the same method as in Example 1, except that the mass ratio of core component to sheath component was changed from 60:40 to 80:20. The evaluation results are shown in Table 1.

[0131] (Example 3) Except for increasing the discharge rate per single hole from 0.55 g / min to 2.90 g / min and changing the ejector pressure from 0.30 MPa to 0.50 MPa, a spunbond nonwoven fabric was obtained using the same method as in Example 1. The evaluation results are shown in Table 1.

[0132] (Example 4) A spunbond nonwoven fabric was obtained using the same method as in Example 1. The obtained spunbond nonwoven fabric was again heat-fused using a thermal calender roll consisting of a pair of upper and lower flat (smooth) rolls, under conditions of a linear pressure of 300 N / cm and a heat bonding temperature of 130°C, resulting in a basis weight of 65 g / m². 2 A spunbond nonwoven fabric was obtained.

[0133] (Example 5) Weight: 65g / m 2 However, the basis weight was 40g / m 2 A spunbond nonwoven fabric was obtained using the same method as in Example 1, except for the difference mentioned above. The evaluation results are shown in Table 1.

[0134] (Example 6) The first fiber web was formed in the same manner as in Example 1, except that the mass ratio of the core component to the sheath component was set to core component:sheath component = 50:50. The basis weight of the first fiber web was 33 g / m². 2 The average single fiber diameter was 14.9 μm.

[0135] A second fiber web was formed on the first fiber web described above using the same method as in Example 1, except that the mass ratio of the core component to the sheath component was set to core component:sheath component = 70:30, thereby obtaining a laminated fiber web. The basis weight of the laminated fiber web was 65 g / m². 2 The average single fiber diameter of the second fiber web was 15.0 μm.

[0136] The laminated fiber web described above was preheated and heat-fused in the same manner as in Example 1 to obtain a spunbond nonwoven fabric. Area ratio P of the core component in the cross-section of the first core-sheath type composite fiber. C1 P is 0.40, the area ratio of the core component in the cross-section of the second core-sheath type composite fiber. C2 is 0.62, P C2 -P C1 The value was 0.22. The ratio of the fiber diameter R1 of the thermoplastic resin A fibers on one surface to the fiber diameter R2 of the thermoplastic resin A fibers on the other surface, R1 / R2, was 0.89. The evaluation results are shown in Table 1.

[0137] (Comparative Example 1) In this experiment, the fiber web was collected in the same manner as in Example 1, except that the polyethylene resin B used as the sheath component was changed to polyester resin C, and the melting temperature was set to 295°C. The basis weight of the fiber web was 65 g / m². 2The collected fiber web was preheated at 60°C and a linear pressure of 30 N / cm using a pair of upper and lower flat rolls. Then, it was heat-fused using a thermal calender roll consisting of a pair of upper and lower flat (smooth) rolls at a linear pressure of 300 N / cm and a heat bonding temperature of 180°C, resulting in a basis weight of 65 g / m². 2 A spunbond nonwoven fabric was obtained. The evaluation results are shown in Table 1.

[0138] (Comparative Example 2) The fiber web was collected using the same method as in Example 1. The collected fiber web was preheated using a pair of upper and lower flat rolls at a temperature of 60°C and a linear pressure of 30 N / cm. Then, it was heat-bonded using a pair of upper and lower heat embossing rolls, consisting of the upper and lower rolls shown below, under the conditions of a linear pressure of 300 N / cm and a heat bonding temperature of 130°C, resulting in a basis weight of 65 g / m². 2 A spunbond nonwoven fabric was obtained. Top roll: A metal embossed roll with a polka dot pattern, with an adhesive surface area ratio of 11%. Lower roll: Metal flat roll The evaluation results are shown in Table 1.

[0139] [Table 1]

[0140] As shown in Table 1, the spunbond nonwoven fabrics of Examples 1 to 6 exhibited sufficient tear strength, printability, and fuzz resistance. On the other hand, the spunbond nonwoven fabric of Comparative Example 1 had insufficient tear strength and was unsuitable for packaging material applications. Furthermore, the spunbond nonwoven fabric of Comparative Example 2 had insufficient printability and fuzz resistance and was unsuitable for packaging material applications.

[0141] [Table 2]

[0142] As shown in Table 2, the spunbond nonwoven fabric of Example 1 exhibited sufficient heat-sealability. On the other hand, the spunbond nonwoven fabric of Example 6 exhibited even better heat-sealability than that of Example 1. [Explanation of Symbols]

[0143] 1. Fibers made of thermoplastic resin A 2.Thermoplastic resin B 3.Resin embedding 4. Rectangle 5. Black line

Claims

1. It contains fibers made of thermoplastic resin A, which is mainly composed of polyester resin. At least some of the aforementioned fibers are coated with a thermoplastic resin B mainly composed of a polyolefin resin, It is a spunbond nonwoven fabric, The melting point (T) of the thermoplastic resin A. ｍ，Ａ )°C and the melting point (T) of the thermoplastic resin B ｍ，Ｂ The difference from )°C is 50°C or more and 180°C or less. The apparent density of the spunbond nonwoven fabric is 0.30 g / cm³. ３ 1.40g / cm or more ３ The following: The average arithmetic mean roughness Ra of the surface of the spunbond nonwoven fabric is 1.0 μm or more and 15.0 μm or less. The tensile elongation in the longitudinal direction of the spunbond nonwoven fabric is 35% or more. Spunbond nonwoven fabric.

2. The average number density of fibers coated with the thermoplastic resin B, as observed in a cross-section in the thickness direction of the spunbond nonwoven fabric, is 100 fibers / mm². ２ Over 8000 pieces / mm ２ The spunbond nonwoven fabric according to claim 1, which is as follows:

3. Observed in a cross-section in the thickness direction of the spunbond nonwoven fabric, the ratio of the number of fibers per unit area coated with the thermoplastic resin B to the total number of fibers is 70% or more and 100% or less. The spunbond nonwoven fabric according to claim 1 or 2.

4. The tensile strength product per basis weight of the spunbond nonwoven fabric is 1.0 (N / 50 mm) / (g / m). ２ ) or more 8.0 (N / 50mm) / (g / m ２ The spunbond nonwoven fabric according to claim 1 or 2, wherein the fabric is as follows:

5. The thermoplastic resin A is a polyethylene terephthalate-based resin, The thermoplastic resin B is a polyethylene-based resin. The spunbond nonwoven fabric according to claim 1 or 2.

6. A spunbond nonwoven fabric according to claim 1 or claim 2, satisfying either formula 1 or formula 2 below. R １ <R ２ ...(Form 1) 0.50≦R １ / R ２ ≦0.95 ・・・(Equation 2) Here, R １ (μm) is the fiber diameter of the thermoplastic resin A fibers in one surface portion of the spunbond nonwoven fabric, R ２ (μm) is the fiber diameter of the thermoplastic resin A fibers in the other surface portion of the spunbond nonwoven fabric.

7. A method for producing the spunbond nonwoven fabric described in claim 1, A step of forming a fiber web composed of core-sheath type composite fibers, wherein the core component is a thermoplastic resin mainly composed of polyester resin, and the sheath component is a thermoplastic resin mainly composed of polyolefin resin, The process of obtaining a preheated web by bringing the heating surface of a heating device into contact with only one surface of the web and preheating it, The process of heat-sealing the preheated web using a thermal calender roll consisting of a pair of upper and lower flat rolls, Includes, The preheating temperature in the process of obtaining the preheated web is 30°C or higher and 90°C or lower. A method for manufacturing spunbond nonwoven fabric.

8. A method for producing the spunbond nonwoven fabric described in claim 1, A step of forming a first fiber web composed of a first core-sheath type composite fiber, wherein the core component is a thermoplastic resin A mainly composed of polyester resin, and the sheath component is a thermoplastic resin B mainly composed of polyolefin resin; A step of forming a laminated web by forming a second fiber web on the first fiber web, the second fiber web being composed of a second core-sheath type composite fiber, the second core-sheath type composite fiber having a core component mainly composed of a thermoplastic resin A and a sheath component mainly composed of a thermoplastic resin B. The process of obtaining a preheated web involves preheating the laminated web by bringing the heating surface of a heating device into contact with only one surface of the laminated web, The process of heat-sealing the laminated web using a thermal calender roll consisting of a pair of upper and lower flat rolls, Includes, The preheating temperature in the process of obtaining the preheated web is 30°C or higher and 90°C or lower. A method for producing a spunbond nonwoven fabric, wherein the first fiber web and the second fiber web satisfy the following formulas 3 and 4. 0.10≦P Ｃ１ ≦0.70 ・・・(Equation 3) 0.10≦P Ｃ２ -P Ｃ１ ≦0.55 ・・・(Equation 4) Here, P Ｃ１ This is the area ratio (unitless) of the core component in the cross-section of the first core-sheath type composite fiber, P Ｃ２ This is the area ratio (unitless) of the core component in the cross-section of the second core-sheath type composite fiber.

9. A method for producing the spunbond nonwoven fabric described in claim 1, A step of forming a second fiber web composed of a second core-sheath type composite fiber, wherein the core component is a thermoplastic resin A mainly composed of polyester resin, and the sheath component is a thermoplastic resin B mainly composed of polyolefin resin; A step of forming a laminated web by forming a first fiber web on the second fiber web, the first fiber web being composed of a first core-sheath type composite fiber in which the core component is a thermoplastic resin mainly composed of polyester resin A and the sheath component is a thermoplastic resin mainly composed of polyolefin resin B, The process of obtaining a preheated web involves preheating the laminated web by bringing the heating surface of a heating device into contact with only one surface of the laminated web, The process of heat-sealing the laminated web using a thermal calender roll consisting of a pair of upper and lower flat rolls, Includes, The preheating temperature in the process of obtaining the preheated web is 30°C or higher and 90°C or lower. A method for producing a spunbond nonwoven fabric, wherein the first fiber web and the second fiber web satisfy the following formulas 3 and 4. 0.10≦P Ｃ１ ≦0.70 ・・・(Equation 3) 0.10≦P Ｃ２ -P Ｃ１ ≦0.55 ・・・(Equation 4) Here, P Ｃ１ This is the area ratio (unitless) of the core component in the cross-section of the first core-sheath type composite fiber, P Ｃ２ This is the area ratio (unitless) of the core component in the cross-section of the second core-sheath type composite fiber.

10. The thermoplastic resin B is a polyethylene-based resin, The solid density of the polyethylene resin is 0.935 g / cm³. ３ 0.970g / cm or more ３ The following is: A method for producing a spunbond nonwoven fabric according to any one of claims 7 to 9.

11. A packaging material comprising the spunbond nonwoven fabric according to claim 1 or 2.

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