Laminated nonwoven fabric, method for manufacturing the same, and protective garment

Abstract

To provide a laminated nonwoven fabric excellent in air permeability, collection efficiency, and surface smoothness.SOLUTION: A laminated nonwoven fabric is formed by laminating at least one spun-bonded nonwoven fabric layer and at least one melt-blown nonwoven fabric layer. The at least one spun-bonded nonwoven fabric layer and the at least one melt-blown nonwoven fabric layer are both composed of fibers comprising a polypropylene-based resin. The laminated nonwoven fabric contains 0.01 mass% or more and 5.00 mass% or less of a hindered amine-based compound and / or a triazine-based compound based on the entire laminated nonwoven fabric. The laminated nonwoven fabric has a basis weight of 30 g / m2 or more and 90 g / m2 or less. When y (the number of yarns / mm2) represents the number of yarns having a flatness ratio of 0.80 or more and 1.25 or less per unit cross-sectional area of the laminated nonwoven fabric, and x (g / m2) represents the basis weight of the laminated nonwoven fabric, the laminated nonwoven fabric satisfies the following relational expression: -600≤a≤600 and y≥0, where a=y-10.7x.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminated nonwoven fabric, and more particularly to a laminated nonwoven fabric applicable to protective clothing. [Background technology]

[0002] In recent years, there has been an increasing demand for disposable protective clothing to protect workers in medical settings against infectious diseases and in workplaces where dust and chemicals are handled. Furthermore, when working in clean rooms, such as in pharmaceutical manufacturing, sterilized protective clothing is also required to protect the target formulation itself from bacteria emanating from the wearer's body (hereinafter referred to as "sterile clothing").

[0003] Conventionally, a laminate of a nonwoven fabric and a porous film has been used as a material for such protective clothing, but this has the problem of poor breathability, causing the inside of the clothing to become stuffy when worn, making it difficult to work for long periods of time. In response to this problem, Patent Document 1 proposes a protective clothing having a sewn section, in this order from the inside of the protective clothing: an inner nonwoven fabric with a water contact angle of a certain level or less, an electret melt-blown nonwoven fabric, and an outer nonwoven fabric with a water contact angle of a certain level or more. It is described that this protective clothing has excellent resistance to the intrusion of contaminated water, excellent dust resistance, and excellent breathability, and furthermore, it can prevent sweat generated from the human body from leaking out of the protective clothing and has excellent performance in absorbing sweat generated from the human body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-61600 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional protective clothing materials, such as laminates of nonwoven fabrics and porous films, can be made water-resistant by the film, but protective clothing using such laminates has the problem of poor breathability, causing the inside of the clothing to become stuffy when worn, making it difficult to work for long periods of time. In contrast, protective clothing such as that described in Patent Document 1 can be made to have a certain degree of water resistance without using a film, and as a result, can be made breathable, thereby improving the stuffiness inside the clothing when worn. However, there is still room for improvement in surface smoothness, which leads to easier dust removal. Therefore, the object of the present invention, made in consideration of the above circumstances, is to provide a laminated nonwoven fabric that combines high breathability and high collection efficiency and has excellent surface smoothness, a manufacturing method therefor, and protective clothing made using the same. [Means for solving the problem]

[0006] The present invention and its preferred embodiments include the following configurations. [1] A laminated nonwoven fabric comprising at least one spunbond nonwoven fabric layer and at least one meltblown nonwoven fabric layer, the at least one spunbonded nonwoven fabric layer and the at least one meltblown nonwoven fabric layer are both composed of fibers made of a polypropylene-based resin composition mainly containing a polypropylene-based resin, the laminated nonwoven fabric contains a hindered amine compound and / or a triazine compound in a total amount of 0.01% by mass or more and 5.00% by mass or less based on the entire laminated nonwoven fabric, The basis weight of the laminated nonwoven fabric is 30 g / m 2 More than 90g / m 2 The number of yarns per unit cross-sectional area of ​​the laminated nonwoven fabric is y (y / mm 2 ), the basis weight of the laminated nonwoven fabric is x (g / m 2 ) A laminated nonwoven fabric that satisfies the following relational expression. -600≦a≦600 y≧0 Here, a=y-10.7x+a [2] The laminated nonwoven fabric according to [1], wherein the arithmetic mean roughness Ra of at least one surface of the laminated nonwoven fabric is 1.0 μm or more and 10.0 μm or less. [3] The apparent density of the laminated nonwoven fabric is 0.20 g / cm 3 More than 0.80g / cm 3 The laminated nonwoven fabric according to [1] or [2], which is: [4] The tensile strength and elongation product per unit area of ​​the laminated nonwoven fabric, calculated by the following formula, is 0.05 (N / 50 mm) / (g / m 2 ) or more 1.50(N / 50mm) / (g / m 2 The laminated nonwoven fabric according to any one of [1] to [3], wherein: Tensile strength and elongation product per unit weight ((N / 50mm) / (g / m 2 )) = [Average value of maximum strength (N / 50mm)] x [Average value of elongation at maximum strength (-)] / basis weight (g / m 2 ). [5] The laminated nonwoven fabric according to any one of [1] to [4], wherein the polypropylene resin composition contains a low-crystalline polyolefin resin. [6] The laminated nonwoven fabric according to [5], wherein the content of the low-crystalline polyolefin resin in the polypropylene resin composition is 1% by mass or more and 20% by mass or less. [7] The laminated nonwoven fabric according to [5] or [6], wherein the low-crystalline polyolefin resin is an ethylene-propylene copolymer. [8] A method for producing the laminated nonwoven fabric according to any one of [1] to [7], comprising the steps of: forming a first spunbonded nonwoven fabric web; forming at least one layer of meltblown nonwoven fabric web on the first spunbonded nonwoven fabric web; and forming a second spunbonded nonwoven fabric web on the at least one layer of meltblown nonwoven fabric web to form a laminated web. and fusing the laminated web with a heat calendar roll consisting of a pair of upper and lower flat rolls to form a laminated nonwoven fabric. [9] Protective clothing in which the laminated nonwoven fabric according to any one of [1] to [7] is used at least in the front body. [Effects of the Invention]

[0007] According to the present invention, it is possible to obtain a laminated nonwoven fabric having high breathability, excellent collection efficiency, and excellent surface smoothness, and a protective suit made using the same. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of an apparatus used to measure the collection efficiency of a laminated nonwoven fabric. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described in detail below. However, the present invention is not limited to the embodiments described below as long as the gist of the present invention is not exceeded.

[0010] The laminated nonwoven fabric of the present invention is formed by laminating at least one spunbonded nonwoven fabric layer and at least one meltblown nonwoven fabric layer.

[0011] [Polypropylene resin] The at least one spunbonded nonwoven fabric layer and the at least one meltblown nonwoven fabric layer are both composed of fibers made of a polypropylene-based resin composition mainly containing a polypropylene-based resin. Herein, "polypropylene-based resin" in the present invention refers to a resin whose main repeating unit is a propylene unit. Hereinafter, the at least one spunbonded nonwoven fabric layer will be simply referred to as "the spunbonded nonwoven fabric layer," and the at least one meltblown nonwoven fabric layer will be simply referred to as "the meltblown nonwoven fabric layer." In addition, in the present invention, the polypropylene-based resin composition used for the fibers constituting the spunbonded nonwoven fabric layer will be referred to as polypropylene-based resin composition P S The polypropylene resin composition used for the fibers constituting the melt-blown nonwoven fabric layer is referred to as polypropylene resin composition P M It is sometimes referred to as.

[0012] Examples of the polypropylene resin include a homopolymer of propylene and a copolymer of propylene with various α-olefins.

[0013] For example, the proportion of propylene units in the polypropylene-based resin is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, the polypropylene-based resin can maintain good spinnability and improve the strength of the laminated nonwoven fabric.

[0014] The polypropylene-based resin composition may contain, in addition to polypropylene, other polyolefin-based resins, thermoplastic elastomers, and the like.

[0015] Among the other polyolefin resins, low-crystalline polyolefin resins are preferred from the viewpoint of imparting flexibility. The low-crystalline polyolefin resin is a polyolefin resin in which a copolymerization monomer such as ethylene or 1-butene is incorporated into a regular polypropylene chain. For example, an ethylene-propylene copolymer or a low stereoregular polypropylene is preferably used. An ethylene-propylene copolymer is more preferred. The ethylene content in the ethylene-propylene copolymer is preferably 1% by mass or more and 50% by mass or less. By having the ethylene content in the ethylene-propylene copolymer be 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, flexibility can be achieved with a low addition amount. By having the ethylene content in the ethylene-propylene copolymer be 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, the occurrence of partial viscosity unevenness during fiber spinning can be prevented, and good spinnability can be maintained.

[0016] The content of the low-crystalline polyolefin resin in the polypropylene resin composition is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 8% by mass or more, in order to fully exert the effect of imparting flexibility. On the other hand, the content of other resins in the polypropylene resin composition is preferably 20% by mass or less, more preferably 15% by mass or less, in order to fully exert the properties of the polypropylene resin.

[0017] The content of the other resin in the polypropylene resin can be calculated by subjecting the laminated nonwoven fabric to infrared spectroscopic analysis and differential scanning calorimetry.

[0018] The polypropylene resin composition preferably contains at least one hindered amine additive and / or triazine additive from the viewpoint of improving electret performance when an electret is provided to the laminated nonwoven fabric. That is, the laminated nonwoven fabric contains a hindered amine compound and / or a triazine compound.

[0019] Examples of the hindered amine compound include poly[(6-(1,1,3,3-tetramethylbutyl)imino-1,3,5-triazine-2,4-diyl)((2,2,6,6-tetramethyl-4-piperidyl)imino)hexamethylene((2,2,6,6-tetramethyl-4-piperidyl)imino)] (manufactured by BASF Japan Ltd., "Chimassorb" (registered trademark) 944LD), dimethyl succinate-1-(2 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonate bis(1,2,2,6,6-pentamethyl-4-piperidyl) (manufactured by BASF Japan Ltd., "Tinuvin" (registered trademark) 144).

[0020] Examples of the triazine additive include poly[(6-(1,1,3,3-tetramethylbutyl)imino-1,3,5-triazine-2,4-diyl)((2,2,6,6-tetramethyl-4-piperidyl)imino)hexamethylene((2,2,6,6-tetramethyl-4-piperidyl)imino)] (manufactured by BASF Japan Ltd., "Chimassorb" (registered trademark) 944LD), and 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-((hexyl)oxy)-phenol (manufactured by BASF Japan Ltd., "Tinuvin" (registered trademark) 1577FF).

[0021] The total amount of the hindered amine additive and / or the triazine additive added to the laminated nonwoven fabric is 0.01% by mass to 5.00% by mass, more preferably 0.02% by mass to 4.00% by mass, and even more preferably 0.03% by mass to 3.00% by mass. By setting the amount added within this range, a nonwoven fabric with excellent collection efficiency can be easily obtained.

[0022] The contents of the hindered amine additive and the triazine additive can be determined, for example, as follows: After the electret-added nonwoven fabric is subjected to Soxhlet extraction with a methanol / chloroform mixed solution, the extract is repeatedly fractionated by HPLC, and each fraction is subjected to IR measurement, GC measurement, GC / MS measurement, MALDI-MS measurement, and the like. 1 H-NMR measurement, and 13 The structure is confirmed by C-NMR measurement. The masses of the fractions containing hindered amine additives and / or triazine additives are added together, and the percentage relative to the total nonwoven fabric is calculated, which is the content of hindered amine additives and triazine additives.

[0023] Additives such as antioxidants, weathering agents, light stabilizers, anti-fogging agents, blocking agents, lubricants, nucleating agents, and pigments such as titanium oxide may be added to the polypropylene resin composition as needed, provided that the effects of the present invention are not impaired.

[0024] In particular, the polypropylene resin composition P M It is preferable that the polypropylene resin composition contains a nucleating agent. By containing the nucleating agent, the crystallization temperature of the polypropylene resin composition increases, and the solidification of the spun fibers proceeds more quickly, thereby reducing fusion between fibers and improving the breathability of the melt-blown nonwoven fabric layer. Examples of the nucleating agent include sorbitol-based nucleating agents, nonitol-based nucleating agents, xylitol-based nucleating agents, phosphoric acid-based nucleating agents, triaminobenzene derivative nucleating agents, and metal carboxylate nucleating agents.

[0025] The polypropylene resin composition P S The polypropylene resin composition P preferably has a melt flow rate (sometimes abbreviated as MFR) of 75 g / 10 min or more and 850 g / 10 min or less. S By setting the MFR to 75 g / 10 min or more, more preferably 120 g / 10 min or more, and even more preferably 155 g / 10 min or more, the stress during drawing can be reduced, and stable spinning is possible even when drawn at a high spinning speed. This reduces the fiber diameter of the spunbonded nonwoven fabric layer, making the surface smooth and allowing for a laminated nonwoven fabric with excellent dust removability. On the other hand, S By making the MFR of the polypropylene resin (P S ) has a larger molecular weight and the strength per fiber is higher, making it possible to obtain a laminated nonwoven fabric strong enough to be used, for example, as a material for protective clothing.

[0026] The polypropylene resin composition P M The polypropylene resin composition P preferably has an MFR of 200 g / 10 min or more and 2500 g / 10 min or less. MBy setting the MFR to 200 g / 10 min or more, more preferably 400 g / 10 min or more, and even more preferably 600 g / 10 min or more, the stress during stretching is reduced, so that a melt-blown nonwoven fabric layer having a small fiber diameter can be obtained while maintaining production capacity, and it is possible to achieve both productivity and high collection efficiency. M By setting the MFR to 2500 g / 10 min or less, more preferably 2000 g / 10 min or less, and even more preferably 1500 g / 10 min or less, the spinneret back pressure increases and fluctuations in the resin discharge rate can be suppressed, resulting in a uniform fiber diameter in the melt-blown nonwoven fabric layer and a laminated nonwoven fabric with uniform texture.

[0027] In the present invention, the MFR of the polypropylene resin composition is measured by ASTM D1238 (Method A), which specifies that the MFR of polypropylene is measured under a load of 2.16 kg and at a temperature of 230°C.

[0028] The polypropylene resin P S and the polypropylene resin composition P M The MFR can also be adjusted by blending two or more resins with different MFRs. In this case, the MFR of the resin blended with the main polypropylene resin (referring to the polypropylene resin that accounts for the largest mass % in the polypropylene resin composition) is preferably 10 g / 10 min or more and 1000 g / 10 min or less, more preferably 20 g / 10 min or more and 800 g / 10 min or less, and even more preferably 30 g / 10 min or more and 600 g / 10 min or less. This can prevent the blended polypropylene resin composition from having uneven viscosity, which can lead to non-uniform fineness or poor spinnability.

[0029] Furthermore, when spinning fibers as described below, the molecular weight of the resin used may be reduced to increase the MFR in order to prevent local viscosity variations, uniform the fiber fineness, and further reduce the fiber diameter as described below. Possible methods for increasing the MFR include, for example, heating the resin before use to pyrolyze it, or adding a peroxide to perform a heat treatment.

[0030] The melting point of the polypropylene resin composition is preferably 120°C or higher and 200°C or lower. By setting the melting point to preferably 120°C or higher, more preferably 130°C or higher, and even more preferably 140°C or higher, heat resistance sufficient for practical use is more likely to be obtained. Furthermore, by setting the melting point to preferably 200°C or lower, more preferably 180°C or lower, it becomes easier to cool the yarn discharged from the spinneret, suppressing fusion between fibers and facilitating stable spinning. Here, the melting point (Tmr) of the polypropylene resin composition refers to the maximum melting peak temperature obtained by measuring the polypropylene resin composition by differential scanning calorimetry (DSC).

[0031] [fiber] The fibers constituting the spunbonded nonwoven fabric layer may be either single-component fibers or bicomponent fibers.

[0032] When composite fibers are used as the fibers constituting the spunbonded nonwoven fabric layer, the composite fiber configuration may be, for example, a concentric sheath-core type, an eccentric sheath-core type, an islands-in-sea type, etc. Among these, concentric sheath-core type composite fibers are preferred because they have excellent spinnability and can be uniformly bonded to each other by thermal bonding.

[0033] The cross-sectional shape of the conjugate fiber may be circular, flat, polygonal, multi-lobal, hollow, etc. Of these, the circular cross-sectional shape is preferred as the cross-sectional shape of the conjugate fiber.

[0034] In the sheath-core composite fiber, the ratio (Os / Oc) of the orientation parameter Os of the sheath component to the orientation parameter Oc of the core component is preferably 0.10 to 0.90. This allows for a laminated nonwoven fabric with less fuzz, excellent strength, and excellent softness. By setting Os / Oc to preferably 0.10 or more, more preferably 0.15 or more, and even more preferably 0.20 or more, it is possible to prevent excessive concentration of drawing stress on the inner fiber layer during spinning, which would reduce spinning stability. On the other hand, by setting Os / Oc to preferably 0.90 or less, more preferably 0.70 or less, and even more preferably 0.50 or less, it is possible to soften only the fiber surface layer during thermal bonding. This allows for strong thermal bonding between the fibers while maintaining the molecular orientation of the inner fiber layer, thereby allowing for a laminated nonwoven fabric with practical strength. Furthermore, by setting the orientation parameter Os of the sheath component of the sheath-core composite fiber to a small value, it is possible to obtain a laminated nonwoven fabric with excellent softness.

[0035] The orientation parameter Os of the sheath component and the orientation parameter Oc of the core component of the sheath-core composite fiber are measured by the following method. In the present invention, islands-in-sea composite fibers are also included in the sheath-core composite fiber, and in the case of islands-in-sea composite fibers, as in the case of the sheath-core composite fiber, when measuring and interpreting the orientation parameters Os and Oc, the "sheath component" is read as the "sea component" and the "core component" as the "island component," and measurements are carried out after reading them as the "sea component" and the "core component," respectively. (1) A sample of laminated nonwoven fabric is embedded in bisphenol-based epoxy resin. (2) After the resin has hardened, a section is cut using a microtome so that the cross section of the spunbond nonwoven fabric layer containing the core-sheath composite fiber is the cutting surface. The section thickness is 2 μm. A point where the cutting angle is within 4° from the fiber axis is selected and the subsequent measurements are performed. (3) Polarized light is incident on a section of the target sheath-core composite fiber from the surface to the center in the fiber axis direction (parallel direction) and in the direction perpendicular to the fiber axis direction (vertical direction), and the Raman spectrum line measurement is performed using a triple Raman spectrometer. For example, the "T-64000" manufactured by Atago Bussan Co., Ltd. can be used as the triple Raman spectrometer. (4) At the positions of the core and sheath components of the core-sheath composite fiber, 810 cm in both the parallel and perpendicular directions -1 Around 840cm -1 Raman band intensity near I 810 and I 840 Calculate the intensity ratio I 810 / I 840 Calculate. (5) Calculate the orientation parameter based on the following formula (a). If the core component is divided into multiple independent regions, measure the orientation parameter in all regions and use the highest value. Orientation parameter = (I 810 / I 840 ) 平行 / (I 810 / I 840 ) 垂直 (a) Here, (I 810 / I 840 ) 平行 : Parallel direction intensity ratio (I 810 / I 840 ) 垂直 : Vertical strength ratio (6) Similar measurements are made at three different non-fused portions of the spunbond nonwoven fabric, the average orientation parameter is calculated, and the result is rounded to one decimal place.

[0036] The cross-sectional shape of the fibers constituting the spunbonded nonwoven fabric layer may be a round cross section, a flat cross section, or an irregular cross section such as a Y-shape or a C-shape. Of these, a round cross section is more preferred because it has excellent spinnability and can be spun at a high spinning speed to produce fibers with excellent single yarn strength.

[0037] The fibers constituting the spunbonded nonwoven fabric layer preferably have an average single fiber diameter of 6.5 μm or more and 16.8 μm or less. By setting the average single fiber diameter to preferably 6.5 μm or more, more preferably 7.5 μm or more, and even more preferably 8.4 μm or more, a decrease in spinnability can be prevented and a nonwoven fabric layer with a stable average single fiber diameter can be formed. On the other hand, by setting the average single fiber diameter to preferably 16.8 μm or less, more preferably 11.9 μm or less, and even more preferably 11.2 μm or less, a laminated nonwoven fabric with high flexibility and uniformity and excellent texture uniformity sufficient for practical use can be obtained, even if the content of the meltblown nonwoven fabric layer in the laminated nonwoven fabric is low.

[0038] The average single fiber diameter (μm) of the fibers constituting the spunbonded nonwoven fabric layer is calculated by the following procedure. (1) Ten small sample pieces are randomly taken from the laminated nonwoven fabric. (2) Surface photographs are taken at a magnification of 500 to 1000 times using a scanning electron microscope (SEM) (for example, Keyence Corporation's "VHX-D500"), and the widths of 100 polypropylene fibers (10 from each sample) are measured. If the cross section of the fiber is irregular, the cross-sectional area is measured, and the diameter of a perfect circle with the same cross-sectional area is determined. (3) Calculate the average single fiber diameter (μm) from the average of the 100 measured values.

[0039] The fibers constituting the melt-blown nonwoven fabric layer preferably have an average single fiber diameter of 0.1 μm or more and 8.0 μm or less. By setting the average single fiber diameter to preferably 0.1 μm or more, more preferably 0.4 μm or more, fibers can be easily collected when forming the melt-blown nonwoven fabric layer, preventing scattering to the surrounding area and resulting in a more uniform laminated nonwoven fabric. On the other hand, by setting the average fiber diameter to preferably 8.0 μm or less, more preferably 7.0 μm or less, the barrier properties of the melt-blown nonwoven fabric layer can be improved, and the collection efficiency of the laminated nonwoven fabric can be improved. The average single fiber diameter can be controlled by the spinning temperature, single-hole output, spinning speed, etc., as described below.

[0040] The polypropylene-based resin (P B The average single fiber diameter (μm) of fibers made of the above-mentioned cellulose acetate sheet is calculated by the following procedure. (1) Ten small sample pieces are randomly taken from the laminated nonwoven fabric. (2) The collected test specimen is cut using a freezing microtome, the obtained cross section is subjected to a conductive treatment, and the cross section is photographed at a magnification of 4000 to 10000 times using an SEM (for example, "VHX-D500" manufactured by Keyence Corporation). (3) Measure the width of 100 fibers in total, 10 fibers from each meltblown nonwoven fabric layer of each sample. (4) The average single fiber diameter (μm) is calculated from the average value of the 100 measured values.

[0041] [Laminated nonwoven fabric] Specific lamination structures of the laminated nonwoven fabric include, for example, an SMS nonwoven fabric formed by laminating (spunbond nonwoven fabric layer) / (meltblown nonwoven fabric layer) / (spunbond nonwoven fabric layer) in this order from the surface of the spunbond nonwoven fabric layer side, an SM nonwoven fabric formed by laminating (spunbond nonwoven fabric layer) / (meltblown nonwoven fabric layer), and an SM nonwoven fabric formed by laminating (spunbond nonwoven fabric layer) / (meltblown nonwoven fabric layer) / (meltblown nonwoven fabric layer). Examples of such a nonwoven fabric include an SMMS nonwoven fabric laminated with a (spunbond nonwoven fabric layer) / (spunbond nonwoven fabric layer) / (meltblown nonwoven fabric layer) / (meltblown nonwoven fabric layer) / (spunbond nonwoven fabric layer), and an SSMMS nonwoven fabric laminated with a (spunbond nonwoven fabric layer) / (spunbond nonwoven fabric layer) / (meltblown nonwoven fabric layer) / (spunbond nonwoven fabric layer), or a (spunbond nonwoven fabric layer) / (meltblown nonwoven fabric layer) / (meltblown nonwoven fabric layer) / (spunbond nonwoven fabric layer). When there are multiple spunbond nonwoven fabric layers or meltblown nonwoven fabric layers, the respective spunbond nonwoven fabric layers or meltblown nonwoven fabric layers may be different from one another. For example, the first and second spunbond nonwoven fabric layers may be made of different types of fibers, may have different melting points, may be made of a single component or a composite component, may have different cross-sectional shapes, may have different thicknesses, strengths, or pressure losses, or may have combinations of these, as long as the object of the present invention is achieved. Any difference may be selected and used depending on the object.

[0042] The laminated nonwoven fabric of the present invention has a number of yarns per unit cross-sectional area of ​​the laminated nonwoven fabric having an aspect ratio of 0.80 to 1.25 (y yarns / mm 2 ), the basis weight of the laminated nonwoven fabric is x (g / m 2 ), the following relation is satisfied: -600≦a≦600 y≧0 Here, a=y-10.7x+a By setting the above a to -600 or more, preferably -300 or more, more preferably -200 or more, a laminated nonwoven fabric with excellent softness can be obtained. On the other hand, by setting the a to 600 or less, preferably 500 or less, more preferably 300 or less, a laminated nonwoven fabric with excellent surface smoothness can be obtained.

[0043] In the present invention, the number y of yarns per unit cross-sectional area in the laminated nonwoven fabric is 0.80 or more and 1.25 or less (yarns / mm 2 ) is measured as follows: (1) Randomly take 20 test pieces measuring 20 mm x 20 mm from the laminated nonwoven fabric. (2) The collected specimen is cut using a freezing microtome, the resulting cross section is subjected to a conductive treatment, and the cross section is photographed using a scanning electron microscope (SEM) (e.g., VHX-D500 manufactured by Keyence Corporation) at a magnification of 1000 to 1800. If the SEM photograph of the cross section contains fused areas due to embossing or the like, the observation field is shifted and the photograph is taken again. (3) The thickness of the laminated nonwoven fabric is measured at five points on the SEM photograph of the cross section, and the average value is taken as the thickness (t) (mm) of the laminated nonwoven fabric. (4) The length (l) (mm) of the laminated nonwoven fabric included in the cross-sectional SEM photograph is measured. (5) Among the fibers included in the cross-sectional SEM photograph, the cross-sectional area is 30 μm 2 The flattening ratio of the above fibers is measured. The flattening ratio is the ratio (A / B or B / A) of the longest line segment (A) to the shortest line segment (B) of any line segments that pass through the center of the fiber cross section and have both end points on the circumference. Note that the flattening ratio is not measured for fibers at the edge of the cross-sectional SEM photograph, where the fiber cross section cannot be completely observed, or for fibers where the interface is unclear due to fusion between fibers. (6) Among the fibers contained in the cross-sectional SEM photograph, the number h (of fibers) with an aspect ratio of 0.80 or more and 1.25 or less is calculated. (7) Divide h by t and l to obtain the number of yarns with an aspect ratio of 0.80 or more and 1.25 or less per unit cross-sectional area (h / (t×l)) (number / mm 2 ) is calculated. (8) For 20 test pieces, the steps (2) to (7) are carried out, and the average value of (h / (t×l)) for the 20 test pieces is rounded to the nearest whole number, and the result is used as the number of yarns with an aspect ratio of 0.80 or more and 1.25 or less per unit cross-sectional area (h / (t×l)) (pieces / mm 2 )

[0044] The ratio h / (t×l) can be adjusted by adjusting the average single fiber diameter of the spunbonded nonwoven fabric layer, as well as by adjusting the bonding temperature, linear pressure, and clearance in the fusion process.

[0045] The basis weight of the laminated nonwoven fabric is 30 g / m 2 More than 90g / m 2 It is preferable that the basis weight is 30 g / m or less. 2 More preferably, 35 g / m 2 More preferably, 40 g / m 2 By adjusting the weight to 90 g / m or more, a laminated nonwoven fabric having a mechanical strength sufficient for practical use can be obtained. 2 Less than 70 g / m 2 By satisfying the following conditions, it is possible to obtain a laminated nonwoven fabric that does not impede the wearer's workability when used as protective clothing. Furthermore, it is possible to reduce the thickness of the protective clothing when folded, thereby reducing the storage space required for the protective clothing as a stockpile.

[0046] In the present invention, the basis weight of the laminated nonwoven fabric is measured by the following procedure in accordance with "6.2 Mass per unit area" of JIS L1913:2010 "Testing methods for general nonwoven fabrics." (1) Take three 20cm x 25cm test pieces per meter of sample width. (2) Weigh the mass (g) of each at standard conditions. (3) The average value is 1m 2 Mass per unit (g / m 2 )

[0047] The apparent density of the laminated nonwoven fabric is 0.20 g / cm 3 More than 0.80g / cm3 The apparent density is preferably 0.20 g / cm or less. 3 More preferably, 0.25 g / cm 3 More preferably, 0.30 g / cm 2 By satisfying the above conditions, the occurrence of fluffing and delamination can be suppressed, and the laminated nonwoven fabric can have strength and handleability. On the other hand, the apparent density is preferably 0.80 g / cm. 3 or less, more preferably 0.70 g / m 2 or less, more preferably 0.55 g / cm 3 or less, it is possible to prevent the voids inside the laminated nonwoven fabric from decreasing, which would result in a loss of flexibility of the laminated nonwoven fabric. The apparent density of the laminated nonwoven fabric can be controlled by appropriately adjusting the average single fiber diameter of the fibers and / or the thermal bonding conditions (shape of the bonded parts, compression rate, temperature, linear pressure, etc.) described below.

[0048] Apparent density of nonwoven fabric (g / cm 3 ) is calculated by the following procedure. (1) The thickness (mm) of the nonwoven fabric is measured according to the following procedure in accordance with "6.1.1 Method A" of JIS L1913:2010 "General nonwoven fabric testing methods." (A) Using a pressure probe with a diameter of 10 mm, measure the thickness of the nonwoven fabric at 10 equally spaced points per meter across the width with an accuracy of 0.01 mm under a load of 10 kPa. (B) Round the average of the above 10 points to the nearest hundredth. (2) From the above unrounded basis weight and thickness, calculate the apparent density using the following formula, and round off to the third decimal place. Apparent density (g / cm 3 ) = [weight (g / m 2 )] / [Thickness (mm)]×10 -3 .

[0049] The laminated nonwoven fabric preferably has an arithmetic mean roughness Ra of at least one surface of 1.0 μm or more and 10.0 μm or less. By setting the arithmetic mean roughness to 1.0 μm or more, more preferably 2.0 μm or more, and even more preferably 3.0 μm or more, the laminated nonwoven fabric can have excellent breathability. On the other hand, by setting the arithmetic mean roughness to 10.0 μm or less, more preferably 9.0 μm or less, and even more preferably 8.0 μm or less, the laminated nonwoven fabric can have excellent surface smoothness.

[0050] In the present invention, the arithmetic mean roughness Ra of the surface of the laminated nonwoven fabric is determined in accordance with "4.2.1 Arithmetic mean height of profile curve" in JIS B0601:2013 "Geometric product specifications (GPS) - Surface texture: Profile curve method - Terms, definitions and surface texture parameters," and is measured as follows: (1) Test pieces measuring 100 mm x 100 mm are taken from the laminated nonwoven fabric at equal intervals across the width of the laminated nonwoven fabric, 10 pieces per meter. (2) The test piece is set on the sample stage, and a surface roughness measuring instrument (for example, a small surface roughness measuring instrument "SURFTEST SJ-210" manufactured by Mitutoyo Corporation) is used to measure the contour curves in the warp direction (the longitudinal direction of the laminated nonwoven fabric, i.e., MD direction) and the weft direction (the width direction of the laminated nonwoven fabric, i.e., CD direction) for both sides of the laminated nonwoven fabric, and the arithmetic mean roughness Ra (μm) is calculated. (3) For each of both sides, the measured values ​​of all test pieces are averaged and rounded to the nearest tenth to obtain the arithmetic mean roughness Ra (μm).

[0051] The arithmetic mean roughness Ra can be controlled by appropriately adjusting the average single fiber diameter of the fibers and / or the preheating conditions (temperature, linear pressure, etc.) and thermal bonding conditions (shape of the bonded part, bonding rate, temperature, linear pressure, etc.) described below.

[0052] The air permeability per unit area of ​​the laminated nonwoven fabric of the present invention is 0.01 (cm 3 / (cm 2 ·sec)) / (g / m 2 ) or more 5.0(cm 3 / (cm2 ·sec)) / (g / m 2 The air permeability per unit area is preferably 5.0 (cm 3 / (cm 2 ·sec)) / (g / m 2 ) or less, more preferably 2 (cm 3 / (cm 2 ·sec)) / (g / m 2 ) or less, more preferably 1.0 (cm 3 / (cm 2 ·sec)) / (g / m 2 ) or less, more preferably 0.5 (cm 3 / (cm 2 ·sec)) / (g / m 2 ) or less, it is possible to maintain the water resistance required for protective clothing applications. On the other hand, the air permeability per unit area is 0.01 (cm 3 / (cm 2 ·sec)) / (g / m 2 ) or more, more preferably 0.02 (cm 3 / (cm 2 ·sec)) / (g / m 2 ) or more, more preferably 0.04 (cm 3 / (cm 2 ·sec)) / (g / m 2 ) or more, more preferably 0.06 (cm 3 / (cm 2 ·sec)) / (g / m 2 ) or more, stuffiness when worn in protective clothing applications can be reduced.

[0053] The air permeability can be adjusted by the basis weight, average single fiber diameter, basis weight of the melt-blown nonwoven fabric layer B, and thermocompression bonding conditions (bonding rate, temperature, and linear pressure), etc.

[0054] In the present invention, the air permeability per unit area weight of the laminated nonwoven fabric is measured by the following procedure in accordance with "6.8.1 Frazier type method" of JIS L1913:2010 "General nonwoven fabric testing methods." (1) Cut a test piece measuring 80 cm x 100 cm from the laminated nonwoven fabric. (2) At a barometer pressure of 125 Pa, measurements are taken at any 20 points on the test piece. (3) The average of the 20 points is calculated as the basis weight (g / m 2 ) and round to the third decimal place.

[0055] The tensile strength and elongation product per unit area of ​​the laminated nonwoven fabric is 0.05 (N / 50 mm) / (g / m 2 ) or more 1.5(N / 50mm) / (g / m 2 ) or less. The tensile strength and elongation product per unit area is preferably 0.05 (N / 50 mm) / (g / m 2 ) or more, more preferably 0.08 (N / 50mm) / (g / m 2 ) or more, more preferably 0.10 (N / 50mm) / (g / m 2 ) or more, it is possible to obtain a laminated nonwoven fabric that is soft, has a good feel and texture, and has excellent strength even at a low basis weight. On the other hand, when the tensile strength / elongation product per basis weight is 1.5 (N / 50 mm) / (g / m 2 ) or less, more preferably 1.2 (N / 50mm) / (g / m 2 ) or less, more preferably 0.8 (N / 50mm) / (g / m 2 ) or less, it is possible to prevent the flexibility of the spunbonded nonwoven fabric from decreasing and the texture from being damaged.

[0056] The tensile strength and elongation product per unit area weight can be controlled by appropriately adjusting the MFR of the polypropylene resin, additives, the average single fiber diameter of the sheath-core composite fiber, the ratio (Os / Oc) of the orientation parameter Os of the sheath component of the sheath-core composite fiber to the orientation parameter Oc of the core component of the sheath-core composite fiber of the spunbonded nonwoven fabric, the spinning speed described below, the preheating conditions (temperature, linear pressure, etc.), the thermal bonding conditions (shape of the bonded part, bonding rate, temperature, linear pressure, etc.), etc.

[0057] In the present invention, the tensile strength / elongation product per unit area of ​​the laminated nonwoven fabric is a value measured by the following procedure in accordance with "6.3 Tensile strength and elongation (ISO method)" of JIS L1913:2010 "Testing methods for general nonwoven fabrics." (1) Take three 50mm x 300mm test pieces per meter of nonwoven fabric width, with the long side facing the warp direction (longitudinal direction of the nonwoven fabric) of the nonwoven fabric. (2) Set the test piece in the tensile testing machine with a gripping distance of 200 mm. (3) A tensile test is carried out at a tensile speed of 100 mm / min, and the maximum strength and the elongation at the maximum strength are measured. Here, the elongation is not converted into a percentage (%), but is expressed as the ratio of elongation to the initial grip distance. (4) Obtain the average value of the maximum strength and elongation at maximum strength measured for each test piece, and calculate the tensile strength-elongation product per unit area based on the following formula, and round off to one decimal place. Tensile strength and elongation product per unit weight ((N / 50mm) / (g / m 2 )) = [Average value of maximum strength (N / 50mm)] x [Average value of elongation at maximum strength (-)] / basis weight (g / m 2 ).

[0058] The laminated nonwoven fabric of the present invention is preferably one in which at least one layer, including the meltblown nonwoven fabric layer, is electretized. Electret processing can trap dust and dirt, making the laminated nonwoven fabric highly dust-proof.

[0059] [Manufacturing method of laminated nonwoven fabric] Next, a preferred embodiment of the method for producing the laminated nonwoven fabric of the present invention will be specifically described.

[0060] The method for producing the laminated nonwoven fabric of the present invention preferably includes the steps of forming at least one layer of a first spunbond nonwoven web, forming at least one layer of a meltblown nonwoven web on the at least one layer of the first spunbond nonwoven web, forming at least one layer of a second spunbond nonwoven web on the at least one layer of the meltblown nonwoven web to form a laminated web (the process up to this point will be referred to as "Step 1"), and heat-fusing the laminated web with a thermal calendar roll consisting of a pair of upper and lower flat rolls to form a laminated nonwoven fabric (the process will be referred to as the "fusing process").

[0061] Alternatively, the nonwoven fabric of the present invention can be produced by superposing a spunbonded nonwoven fabric layer and a meltblown nonwoven fabric layer that have been formed separately, and fusing these nonwoven fabric layers together by applying heat and pressure, or by bonding them with an adhesive such as a hot melt adhesive or a solvent-based adhesive, to form a laminate.

[0062] The method for producing the laminated nonwoven fabric of the present invention preferably further comprises a step of subjecting the melt-blown nonwoven fabric layer or the entire obtained laminated nonwoven fabric to electret processing (referred to as an "electretization step").

[0063] (Process 1) In step 1, the spunbond nonwoven fabric layer and the meltblown nonwoven fabric layer can be formed by the spunbonding method and the meltblown nonwoven fabric layer, respectively. As a method for laminating these to form a laminate, a method can be preferably employed in which fibers formed by the meltblown method are deposited directly on the spunbond nonwoven fabric layer formed first to form a meltblown nonwoven fabric layer, and then fibers formed by the spunbonding method are deposited to form a spunbond nonwoven fabric layer, thereby forming a laminate by sequentially depositing additional fibers on the obtained nonwoven fabric layers.

[0064] The spunbond nonwoven web can be formed by spinning a molten polypropylene resin composition into long fibers from a spinneret, cooling and stretching the fibers, and then collecting the fibers on a moving net. The stretching may be performed by suction with compressed air using an ejector or the like.

[0065] The spinneret and ejector may have various shapes such as a round shape, a rectangular shape, etc. Among them, a combination of a rectangular spinneret and a rectangular ejector is preferably used because it uses a relatively small amount of compressed air, is excellent in energy cost, is less likely to cause fusion or friction between the yarns, and facilitates opening of the yarns.

[0066] In the present invention, a polypropylene resin composition is melted in an extruder, metered, and fed to a spinneret to be spun into continuous fibers. The spinning temperature when the polypropylene resin composition is melted and spun is preferably 200°C or higher and 270°C or lower, more preferably 210°C or higher and 260°C or lower, and even more preferably 220°C or higher and 250°C or lower. By setting the spinning temperature within the above range, a stable molten state can be achieved, and excellent spinning stability can be obtained.

[0067] The spun continuous fiber yarn is cooled by, for example, forcibly blowing cold air onto the yarn, naturally cooling at the ambient temperature around the yarn, or adjusting the distance between the spinneret and the ejector, or a combination of these methods can be used. The cooling conditions can be appropriately adjusted in consideration of the output per hole of the spinneret, the spinning temperature, the ambient temperature, etc.

[0068] Next, the cooled and solidified yarn may be drawn by compressed air injected from an ejector. The spinning speed is preferably 3000 m / min to 6500 m / min, more preferably 3500 m / min to 6500 m / min, and even more preferably 4000 m / min to 6500 m / min. A spinning speed of 3000 m / min to 6500 m / min results in high productivity, promotes fiber orientation and crystallization, and enables the production of high-strength long fibers.

[0069] The meltblown nonwoven fabric layer can be formed using a known manufacturing method. A polypropylene resin composition is melted in an extruder and fed to a nozzle. Hot air is blown onto the extruded filaments to thin them. The meltblown nonwoven fabric layer is then formed on a previously formed spunbonded or meltblown nonwoven fabric layer placed on a collection net or a moving net. The meltblowing method does not require complex processes, can easily produce fine fibers of several micrometers, and can exhibit high water resistance.

[0070] The long fibers can be collected on a moving net or on an already formed spunbond or meltblown nonwoven web that is placed on the moving net to further form a nonwoven web.

[0071] It is also preferable to preheat one surface of the laminated web before the fusion step. Preheating is preferably performed by fusing the collected fiber web using a pair of upper and lower flat rolls, or by placing a flat roll or a heating plate above a net conveyor and fusing the web between the net conveyor and the flat roll or heating plate. This method allows for a laminated nonwoven fabric with excellent surface smoothness while maintaining the gap. The "flat roll" used in these methods refers to a metal roll or elastic roll with a smooth surface. Furthermore, the upper and lower pair of flat rolls refers to a pair of metal rolls or a pair of metal rolls and elastic rolls. Here, an elastic roll refers to a roll made of a material that is more elastic than a metal roll. Examples of elastic rolls include so-called paper rolls made of paper, cotton, aramid paper, etc., as well as resin rolls made of urethane resins, epoxy resins, silicone resins, polyester resins, hard rubber, etc., or mixtures of these.

[0072] In this preheating, when a pair of upper and lower flat rolls are used for fusion bonding, only one of the flat rolls serves as a heated surface. To give an example of an embodiment, only one of the flat rolls has a heating mechanism such as a heater and is a roll (heated roll) heated to a temperature described below, while the other flat roll does not have such a heating mechanism, or has a heating mechanism but the heater is switched off. In this embodiment, the "heated surface" refers to the surface of the heated roll.

[0073] In this preheating, when a flat roll is placed above a net conveyor and preheating is performed between the net conveyor and the flat roll, the flat roll is preferably made of metal, and a heating mechanism such as a heater is provided only on this flat roll, which is heated to a temperature described below. This flat roll is the heated roll, and the surface of this heated roll is the "heated surface" mentioned above.

[0074] In this preheating, when a heating plate is placed above the net conveyor and preheating is performed 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 the surface of this heating plate that comes into contact with the fiber web is the "heating surface."

[0075] In the preheating step, the temperature of the heated surface is preferably 40°C or higher and 100°C or lower. By setting the temperature of the heated surface to 40°C or higher, more preferably 45°C or higher, and even more preferably 50°C or higher, thermal crystallization of the fibers before thermocompression bonding can be promoted, preventing a loss of flexibility in the nonwoven fabric after thermocompression bonding. Furthermore, deterioration of the texture due to the surface layer of the nonwoven fabric being turned up or blown away during transport on the net can be prevented, improving transportability from the time the yarn is collected to the time it is thermocompressed. On the other hand, by setting the surface temperature to 100°C or lower, more preferably 75°C or lower, and even more preferably 70°C or lower, thermal crystallization of the fibers before thermocompression bonding can be suppressed, resulting in a nonwoven fabric with even better surface smoothness.

[0076] Furthermore, when a flat roll is used in the preheating step, the linear pressure of the heating surface is preferably 1 N / cm or more and 100 N / cm or less. By setting the lower limit of the 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 range to 100 N / cm or less, preferably 50 N / cm or less, heat is transferred to the interior of the fiber web on the heating surface, thermal crystallization is suppressed, and sufficient pressure bonding can be achieved during thermal bonding.

[0077] (fusion process) In the fusion step, a method for fusion bonding the laminated web is preferably used, which uses a heat calendar roll consisting of a pair of upper and lower flat rolls, which allows the thickness of the spunbonded nonwoven fabric to be adjusted to a constant value.

[0078] As the surface material of the heat calender roll, it is preferable to use a pair of metal rolls in order to obtain a sufficient heat-pressure bonding effect.

[0079] The surface temperature of the thermal calendar roll in the fusion step is preferably Tm-50°C or higher and Tm-15°C or lower, where Tm is the melting point of the polypropylene resin composition used. By setting the surface temperature of the thermal calendar roll to Tm-50°C or higher, more preferably Tm-45°C or higher, it is possible to obtain a laminated nonwoven fabric with adequate fusion strength for practical use. Furthermore, by setting the surface temperature of the thermal calendar roll to Tm-15°C or lower, more preferably Tm-20°C or lower, excessive fusion is suppressed, and the laminated nonwoven fabric can be obtained with adequate flexibility and processability, particularly suitable for use in protective clothing.

[0080] The linear pressure of the thermal calendar roll is preferably 50 N / cm or more and 500 N / cm or less. By setting the linear pressure of the thermal calendar roll to 50 N / cm or more, more preferably 100 N / cm or more, and even more preferably 150 N / cm or more, it is possible to obtain a laminated nonwoven fabric with adequate fusion and practical strength. On the other hand, by setting the linear pressure of the thermal calendar roll to 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 obtain a laminated nonwoven fabric with adequate flexibility and processability, particularly suitable for use in protective clothing.

[0081] In the present invention, in order to adjust the thickness of the laminated nonwoven fabric, thermocompression bonding can be performed using a pair of upper and lower flat rolls before and / or after the fusion bonding using the above-mentioned thermal calendar rolls. The pair of upper and lower flat rolls refers to metal rolls or elastic rolls with smooth surfaces, and a pair of metal rolls or a pair of metal rolls and elastic rolls can be used.

[0082] The term "elastic roll" used herein refers to a roll made of a material that has greater elasticity than a metal roll. Examples of elastic rolls include so-called paper rolls made of paper, cotton, aramid paper, etc., and rolls made of resins such as urethane resin, epoxy resin, silicone resin, polyester resin, hard rubber, and mixtures of these.

[0083] (Electret formation process) As a method for electretizing the melt-blown nonwoven fabric layer in the electretization step, a method of spraying liquid droplets onto the yarns during the period from when hot air is sprayed onto the yarns to when the yarns are deposited in a collection section, which can be preferably used to perform electret treatment, can be employed.

[0084] The droplet spraying device may be a single-hole spray nozzle that sprays water droplets in a conical or fan shape from a single hole, a slit-type spray nozzle that sprays water droplets in a band shape from a slit-shaped outlet, etc. Among these, in terms of being able to apply even a small amount of water uniformly in the width direction, it is more preferable to use a spray nozzle that has a plurality of water outlets arranged in the width direction and a pair of air outlets that open continuously or intermittently across the width direction and are arranged opposite to each other so as to sandwich the plurality of water outlets, and that causes air discharged from the air outlet to collide with water discharged from the plurality of water outlets.

[0085] Methods for electretizing a laminated nonwoven fabric include, for example, a method in which a fiber sheet is placed in contact with an earth electrode, and while moving both the earth electrode and the laminated nonwoven fabric, high voltage is applied using a non-contact voltage application electrode to continuously electretize the fabric; a method in which a jet or a stream of water droplets is sprayed onto the laminated nonwoven fabric at a pressure sufficient to allow the water to penetrate into the fiber sheet, thereby electretizing the fabric and creating a uniform mixture of positive and negative charges; and a method in which the laminated nonwoven fabric is passed over a slit-shaped nozzle and the water is sucked into the nozzle, thereby allowing the water to penetrate into the laminated nonwoven fabric and creating a uniform mixture of positive and negative charges (hydrocharging method).

[0086] [Protective clothing] The protective clothing of the present invention uses the laminated nonwoven fabric at least on the front body, and is suitable for use in, for example, work carried out in clean rooms, work involving the removal or handling of dust and chemical substances (hereinafter referred to as pollutants), and in regenerative medicine culture facilities and pharmaceutical manufacturing sites.

[0087] Therefore, it is also preferable that the protective clothing has been subjected to a sterilization treatment. [Example]

[0088] The laminated nonwoven fabric of the present invention will be specifically described based on examples. However, the present invention is not limited to these examples. In measuring each physical property, unless otherwise specified, the measurement was performed according to the above-mentioned method.

[0089] (1) MFR of polypropylene resin (g / 10 min) The MFR of polypropylene resin was measured under the conditions of a load of 2.16 kg and a temperature of 230°C.

[0090] (2) Basis weight (g / m) of spunbond nonwoven fabric web, meltblown nonwoven fabric web, and laminated nonwoven fabric 2 ) The basis weights of the spunbond nonwoven fabric web and the meltblown nonwoven fabric web were measured by the method described above using webs separately collected on a collection net under the same conditions as in each Example and Comparative Example. The basis weight of the laminated nonwoven fabric was measured by the method described above.

[0091] (3) Number of threads y (threads / mm 2 ) Based on the above method, the number y of yarns having an aspect ratio of 0.80 or more and 1.25 or less per unit cross-sectional area was measured.

[0092] (4) Average single fiber diameter (μm) of spunbond nonwoven fabric layer and meltblown nonwoven fabric layer The scanning electron microscope used was a VHX-D500 manufactured by Keyence Corporation, and measurements were carried out according to the method described above.

[0093] (5) Orientation parameters of core-sheath composite fibers in laminated nonwoven fabrics The triple Raman spectrometer, "T-64000" manufactured by Atago Bussan Co., Ltd., was used and measurements were carried out according to the above-mentioned method. The measurement conditions were as follows: Measurement mode: Microscopic Raman (polarization measurement) Objective lens: x100 Beam diameter: 1 μm ·Light source: Ar + Laser / 514.5nm Laser power: 60mW Diffraction grating: Single 1800 gr / mm Cross slit: 100μm Detector resolution: 1024x256.

[0094] (6) Arithmetic mean roughness Ra (μm) of the surface, surface smoothness The surface roughness was measured using a small surface roughness measuring instrument "SURFTEST SJ-210" manufactured by Mitutoyo Corporation, using the method described above.

[0095] The surface smoothness was evaluated according to the following criteria, from A to C. A grade of B or higher was judged to have "sufficient surface smoothness" and was considered to be acceptable. A: Surface roughness is 6.0 μm or less. B: The surface roughness is greater than 6.0 μm and equal to or less than 10.0 μm. C: Surface roughness is greater than 10.0 μm.

[0096] (7) Apparent density of the laminated nonwoven fabric (g / cm 3 ) The apparent density of the laminated nonwoven fabric was calculated based on the above-mentioned method.

[0097] (8) Tensile strength and elongation product of laminated nonwoven fabric ((N / 50mm) / (g / m 2 )) The tensile strength-elongation product of the laminated nonwoven fabric was calculated based on the above-mentioned method.

[0098] (9) Air permeability per unit area of ​​laminated nonwoven fabric ((cm 3 / (cm 2 ·sec)) / (g / m 2 )) The airflow rate was measured based on the above-mentioned method. The calculated airflow rate (cm 3 / (cm 2 ·sec)) is calculated based on the above method. 2 ) and the air permeability per unit area was calculated by rounding off to two decimal places using the following formula. Air permeability per unit area = Air permeability (cm 3 / (cm 2 sec) / weight (g / m 2 ). The air permeability per unit area of ​​the laminated nonwoven fabric is 0.05 cm 3 / (cm 2 ·s) or above was considered a pass.

[0099] (10) Collection efficiency of laminated nonwoven fabric (%) Three measurement samples measuring 15 cm x 15 cm were taken widthwise from the spunbond nonwoven fabric, and the collection efficiency of each measurement sample was measured using the collection efficiency measurement device shown in Figure 1. The collection efficiency measurement device in Figure 1 has a dust collection box 2 connected upstream of sample holder 1, in which measurement sample M is set, and a flow meter 3, flow control valve 4, and blower 5 connected downstream. A particle counter 6 is also attached to sample holder 1, and the number of dust particles on the upstream and downstream sides of measurement sample M can be measured via a selector cock 7. The sample holder 1 is also equipped with a pressure gauge 8, which allows the static pressure difference between the upstream and downstream sides of measurement sample M to be read.

[0100] To measure the collection efficiency, a 10% solution of polystyrene 0.309U (manufacturer: Nacalai Tesque, Inc.) was diluted 200 times with distilled water and filled into a dust collection box 2. Next, a measurement sample M was set in a sample holder 1, and the air flow rate was adjusted with a flow control valve 4 so that the filter passing speed was 3.2 m / min, and the dust concentration was adjusted to 10,000 to 40,000 particles / 2.83 × 10 -4 m 3 (0.01ft 3 ), and the number of dust particles D upstream and d downstream of the measurement sample M were measured three times per measurement sample using a particle counter 6 (KC-01D, manufactured by Rion Co., Ltd.). The collection efficiency (%) for particles between 0.3 μm and 0.5 μm was calculated using the following formula based on JIS K0901:1991 "Test methods for the shape, dimensions and performance of filter media for collecting dust samples in gas." The average value for the five measurement samples was calculated and rounded to one decimal place to obtain the final collection efficiency (%). Collection efficiency (%) = [1-(d / D)] x 100 Here, d: Total number of downstream dust particles measured three times D: Total number of dust particles measured three times upstream The higher the collection efficiency of the nonwoven fabric, the fewer the downstream dust particles, and therefore the higher the collection efficiency value. A laminated nonwoven fabric with a collection efficiency of 85% or more was considered to be acceptable.

[0101] (11) Bending resistance of laminated nonwoven fabric (mm) Five 25mm wide x 250mm wide test pieces were prepared in accordance with JIS L1913:2010 "General Nonwoven Fabric Testing Methods," section 6.7.3, "41.5° Cantilever Method." The short side of each test piece was placed on a horizontal table with a 45° inclined surface, with the base line of the scale aligned. The test piece was manually slid along the inclined surface until the center of one end of the test piece contacted the inclined surface. The travel distance of the other end was read on the scale. Measurements were taken on both sides of the five test pieces, and the average value was calculated. A bending resistance of 150mm or less was considered a pass.

[0102] [Example 1] (First spunbond nonwoven web) A polypropylene resin consisting of a homopolymer with an MFR of 200 g / 10 min and a melting point of 163°C was mixed with a low-crystalline polyolefin resin, an ethylene-propylene copolymer with an MFR of 20 g / 10 min and an ethylene copolymerization rate of 15 wt% so that the ethylene-propylene copolymer blend ratio was 10 mass%. The mixed resin composition was melted in an extruder and spun from a rectangular spinneret with a hole diameter of φ0.30 mm and a hole depth of 2 mm at a spinning temperature of 235°C and a single-hole throughput rate of 0.40 g / min. The spun yarn was cooled and solidified, and then pulled and stretched in a rectangular ejector with compressed air at an ejector pressure of 0.35 MPa. The yarn was collected on a moving net and spun into a polypropylene long fiber fiber with a basis weight of 16.5 g / m. 2 A first spunbond nonwoven fabric web was formed. The average single fiber diameter of the fibers constituting the first spunbond nonwoven fabric web was 11.2 μm.

[0103] (meltblown nonwoven web) A polypropylene resin consisting of a homopolymer with an MFR of 1100 g / min, to which 2.0% by mass of a hindered amine compound was added, was melted in an extruder and spun from a die with a hole diameter of φ0.25 mm at a spinning temperature of 260°C and a single-hole throughput of 0.10 g / min. Air was then sprayed onto the yarn at an air temperature of 290°C and an air pressure of 0.10 MPa, and the yarn was collected on the first spunbond nonwoven fabric web to form a meltblown nonwoven fabric web. The basis weight of the meltblown nonwoven fabric web was 7 g / m. 2 The average single fiber diameter was 1.1 μm.

[0104] (Second spunbond nonwoven web) A second spunbond nonwoven web was formed on the meltblown nonwoven web under the same conditions as for the first spunbond nonwoven web, and the total basis weight was 40 g / m. 2 A laminated web of 1000 .mu.m was obtained.

[0105] (Laminated nonwoven fabric) The laminated web was preheated on one side by contacting it with a heated flat roll heated to 60°C on a net. Next, the laminated web was heat-sealed using a heated 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 thermal bonding temperature of 155°C, to obtain a laminated nonwoven fabric.

[0106] Next, the laminated nonwoven fabric was run along the water surface of a water tank supplied with pure water, and a slit-shaped suction nozzle was placed on the surface to suck the water, so that the water penetrated the entire surface of the laminated nonwoven fabric. After draining the water, the fabric was allowed to dry naturally, thereby carrying out an electret treatment. The evaluation results are shown in Table 1.

[0107] [Example 2] (First spunbond nonwoven web) The fibers to be spun were sheath-core composite fibers, with a core component made of a polypropylene homopolymer having an MFR of 120 g / 10 min and a melting point of 163°C, and the sheath component made of a polypropylene homopolymer having an MFR of 150 g / 10 min and a melting point of 163°C. The extrusion mass ratio of the core component to the sheath component was 7:3, and the same procedure as in Example 1 was used to spun a sheath-core composite fiber with a basis weight of 16.5 g / m2 made of polypropylene long fibers having an average single fiber diameter of 11.2 μm. 2 A first spunbond nonwoven web was formed.

[0108] (meltblown nonwoven web) A meltblown nonwoven web was formed in the same manner as in Example 1 on the first spunbond nonwoven web.

[0109] (Second spunbond nonwoven web) A second spunbond nonwoven web was formed on the meltblown nonwoven web under the same conditions as for the first spunbond nonwoven web, to obtain a laminated fiber web.

[0110] (Laminated nonwoven fabric) The laminated fiber web was subjected to preheating, heat fusion and electret treatment in the same manner as in Example 1 to obtain a laminated nonwoven fabric. The evaluation results are shown in Table 1.

[0111] [Example 3] (First spunbond nonwoven web) A 16.5 g / m2 woven fabric was prepared in the same manner as in Example 1, except that the resin composition fed to the extruder was a polypropylene resin consisting of a homopolymer with an MFR of 200 g / 10 min and a melting point of 163°C, and the fabric was made of polypropylene long fibers having an average single fiber diameter of 11.2 μm. 2 A first spunbond nonwoven web was formed.

[0112] (meltblown nonwoven web) A meltblown nonwoven web was formed in the same manner as in Example 1 on the first spunbond nonwoven web.

[0113] (Second spunbond nonwoven web) A second spunbond nonwoven web was formed on the meltblown nonwoven web under the same conditions as for the first spunbond nonwoven web, to obtain a laminated fiber web.

[0114] (Laminated nonwoven fabric) The laminated fiber web was subjected to preheating, heat fusion and electret treatment in the same manner as in Example 1 to obtain a laminated nonwoven fabric. The evaluation results are shown in Table 1.

[0115] [Example 4] (First spunbond nonwoven web) The resin composition fed to the extruder was a polypropylene resin consisting of a homopolymer with an MFR of 200 g / 10 min and a melting point of 163°C, the single-hole discharge rate was 0.30 g / min, and the ejector pressure was 0.50 MPa. The same procedure as in Example 1 was repeated to produce a 15.6 g / m2 polypropylene long fiber extrusion sheet having an average single fiber diameter of 8.0 μm and a basis weight of 15.6 g / m2. 2 A first spunbond nonwoven web was formed.

[0116] (meltblown nonwoven web) A meltblown nonwoven fabric web was formed on the first spunbond nonwoven fabric web in the same manner as in Example 1. The basis weight of the meltblown nonwoven fabric web was 8.8 g / m 2 The average single fiber diameter was 1.1 μm.

[0117] (Second spunbond nonwoven web) A second spunbond nonwoven web was formed on the meltblown nonwoven web under the same conditions as for the first spunbond nonwoven web, to obtain a laminated fiber web.

[0118] (Laminated nonwoven fabric) The laminated fiber web was subjected to preheating, heat fusion and electret treatment in the same manner as in Example 1 to obtain a laminated nonwoven fabric. The evaluation results are shown in Table 1.

[0119] [Example 5] (First spunbond nonwoven web) A first spunbond nonwoven web composed of polypropylene long fibers having an average single fiber diameter of 16.8 μm was formed in the same manner as in Example 1, except that the resin composition supplied to the extruder was a polypropylene resin consisting of a homopolymer having an MFR of 35 g / 10 min and a melting point of 163°C, and the single-hole discharge rate was 0.75 g / min.

[0120] (meltblown nonwoven web) A meltblown nonwoven web was formed in the same manner as in Example 1 on the first spunbond nonwoven web.

[0121] (Second spunbond nonwoven web) A second spunbond nonwoven web was formed on the meltblown nonwoven web under the same conditions as for the first spunbond nonwoven web, to obtain a laminated fiber web.

[0122] (Laminated nonwoven fabric) The laminated fiber web was subjected to preheating, heat fusion and electret treatment in the same manner as in Example 1 to obtain a laminated nonwoven fabric. The evaluation results are shown in Table 1.

[0123] [Example 6] (First spunbond nonwoven web) A 16.5 g / m2 woven fabric was prepared in the same manner as in Example 1, except that the resin composition fed to the extruder was a polypropylene resin consisting of a homopolymer with an MFR of 200 g / 10 min and a melting point of 163°C, and the fabric was made of polypropylene long fibers having an average single fiber diameter of 11.2 µm. 2 A first spunbond nonwoven web was formed.

[0124] (meltblown nonwoven web) A meltblown nonwoven web was formed in the same manner as in Example 1 on the first spunbond nonwoven web.

[0125] (Second spunbond nonwoven web) A second spunbond nonwoven web was formed on the meltblown nonwoven web under the same conditions as for the first spunbond nonwoven web, to obtain a laminated fiber web.

[0126] (Laminated nonwoven fabric) The laminated fiber web was subjected to preheating, heat fusion, and electret treatment in the same manner as in Example 1, except that the preheating temperature was 95°C and the heat fusion temperature was 135°C, to obtain a laminated nonwoven fabric. The evaluation results are shown in Table 1.

[0127] [Comparative Example 1] (First spunbond nonwoven web layer) In the same manner as in Example 1, a woven fabric consisting of polypropylene long fibers having an average single fiber diameter of 11.2 μm and a basis weight of 16.5 g / m 2 A first spunbond nonwoven web was formed.

[0128] (meltblown nonwoven web) A melt-blown nonwoven web was formed in the same manner as in Example 1, except that no hindered amine compound was added to the resin fed to the extruder.

[0129] (Second spunbond nonwoven web) A second spunbond nonwoven web was formed on the meltblown nonwoven web under the same conditions as for the first spunbond nonwoven web, to obtain a laminated fiber web.

[0130] (Laminated nonwoven fabric) The laminated fiber web was subjected to preheating, heat fusion and electret treatment in the same manner as in Example 1 to obtain a laminated nonwoven fabric. The evaluation results are shown in Table 1.

[0131] Comparative Example 2 (First spunbond nonwoven web layer) In the same manner as in Example 1, a woven fabric consisting of polypropylene long fibers having an average single fiber diameter of 11.2 μm and a basis weight of 16.5 g / m 2 A first spunbond nonwoven web was formed.

[0132] (meltblown nonwoven web) A meltblown nonwoven web was formed in the same manner as in Example 1 on the first spunbond nonwoven web.

[0133] (Second spunbond nonwoven web) A second spunbond nonwoven web was formed on the meltblown nonwoven web under the same conditions as for the first spunbond nonwoven web, to obtain a laminated fiber web.

[0134] (Laminated nonwoven fabric) For the heat fusion, a pair of upper and lower heat embossing rolls was used, consisting of an upper roll made of metal with an engraved (concave and concave) embossing roll with an adhesion area ratio of 11%, and a lower roll made of metal with a flat roll. Except for this, the laminated fiber web was preheated, heat fused, and electret-treated in the same manner as in Example 1 to obtain a laminated nonwoven fabric. The evaluation results are shown in Table 1.

[0135] Comparative Example 3 (First spunbond nonwoven web) The resin composition fed to the extruder was a polypropylene resin consisting of a homopolymer with an MFR of 200 g / 10 min and a melting point of 163°C, and a basis weight of 41 g / m 2 A first spunbond nonwoven web made of polypropylene long fibers having an average single fiber diameter of 11.2 μm was formed in the same manner as in Example 1, except that the above conditions were met.

[0136] (Melt-blown nonwoven fabric layer) Weight 18g / m 2 A meltblown nonwoven fabric web was formed on the first spunbonded nonwoven fabric web in the same manner as in Example 1, except that the following conditions were met:

[0137] (Second spunbond nonwoven web) A second spunbond nonwoven web was formed on the meltblown nonwoven web under the same conditions as for the first spunbond nonwoven web, to obtain a laminated fiber web.

[0138] (Laminated nonwoven fabric) The laminated fiber web was subjected to preheating, heat fusion and electret treatment in the same manner as in Example 1 to obtain a laminated nonwoven fabric. The evaluation results are shown in Table 1.

[0139] [Table 1]

[0140] The laminated nonwoven fabrics of the present invention in Examples 1 to 6 were nonwoven fabrics excellent in surface smoothness, breathability, and collection efficiency. On the other hand, the laminated nonwoven fabric containing no hindered amine compound in Comparative Example 1 was inferior in collection efficiency. Furthermore, the nonwoven fabric in Comparative Example 2, in which the value of a was greater than 600, was inferior in surface smoothness. Furthermore, the nonwoven fabric in Comparative Example 3, in which the basis weight was 90 g / m 2 Nonwoven fabrics with a larger diameter than this were found to have poor breathability. [Explanation of symbols]

[0141] M: Measurement sample 1: Sample holder 2: Dust storage box 3:Flow meter 4: Flow control valve 5: Blower 6: Particle Counter 7: Switch cock 8: Pressure gauge

Claims

1. A laminated nonwoven fabric comprising at least one spunbonded nonwoven fabric layer and at least one meltblown nonwoven fabric layer, the at least one spunbonded nonwoven fabric layer and the at least one meltblown nonwoven fabric layer are both composed of fibers made of a polypropylene-based resin composition mainly containing a polypropylene-based resin, the laminated nonwoven fabric contains a hindered amine compound and / or a triazine compound in a total amount of 0.01% by mass or more and 5.00% by mass or less based on the entire laminated nonwoven fabric, The basis weight of the laminated nonwoven fabric is 30 g / m ２ 90g / m or more ２ The number of yarns per unit cross-sectional area of ​​the laminated nonwoven fabric is y (yarns / mm ２ ), the basis weight of the laminated nonwoven fabric is x (g / m ２ ) a laminated nonwoven fabric that satisfies the following relational expression: −600≦a≦600 y≧0 Here, a = y - 10.7x

2. 2. The laminated nonwoven fabric according to claim 1, wherein the arithmetic mean roughness Ra of at least one surface of the laminated nonwoven fabric is 1.0 μm or more and 10.0 μm or less.

3. The apparent density of the laminated nonwoven fabric is 0.20 g / cm ３ 0.80g / cm or more ３ The laminated nonwoven fabric according to claim 1 or 2, wherein:

4. The tensile strength and elongation product per unit area of ​​the laminated nonwoven fabric, calculated by the following formula, is 0.05 (N / 50 mm) / (g / m ２ ) or more 1.50 (N / 50mm) / (g / m ２ 3. The laminated nonwoven fabric according to claim 1 or 2, wherein the thickness is 1 / 2 mm or less. Tensile strength and elongation product per unit area ((N / 50 mm) / (g / m ２ )) = [average value of maximum strength (N / 50mm)] x [average value of elongation at maximum strength (-)] / basis weight (g / m ２ ).

5. The laminated nonwoven fabric according to claim 1 or 2, wherein the polypropylene-based resin contains a low-crystalline polyolefin-based resin.

6. The laminated nonwoven fabric according to claim 5 , wherein the content of the low-crystalline polyolefin resin in the polypropylene resin is 1% by mass or more and 20% by mass or less.

7. 6. The laminated nonwoven fabric according to claim 5, wherein the low-crystalline polyolefin resin is an ethylene-propylene copolymer.

8. 3. A method for producing the laminated nonwoven fabric according to claim 1 or 2, comprising the steps of: forming at least one layer of a first spunbonded nonwoven web; forming at least one layer of a meltblown nonwoven web on the at least one layer of the first spunbonded nonwoven web; and forming at least one layer of a second spunbonded nonwoven web on the at least one layer of the meltblown nonwoven web to form a laminated web. and heat-sealing the laminated web with a heat calender roll consisting of a pair of upper and lower flat rolls to form a laminated nonwoven fabric.

9. 3. A protective suit, comprising the laminated nonwoven fabric according to claim 1 or 2 at least in the front body portion.

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