Nonwoven fabric laminate and method for producing nonwoven fabric laminate

Abstract

This nonwoven fabric laminate is embossed and comprises: a melt-blown nonwoven fabric layer that includes a melt-blown nonwoven fabric; and spunbond nonwoven fabric layers that include a spunbond nonwoven fabric and that are provided on both surfaces of the melt-blown nonwoven fabric layer. The nonwoven fabric laminate has an embossed pattern formed of an embossed portion and a non-embossed portion other than the embossed portion. In the nonwoven fabric laminate, the welded area percentage is at least 16.0%, and the emboss boundary length per unit area is at most 1.50 mm / mm2. This method is for producing the nonwoven fabric laminate.

Description

Nonwoven fabric laminate and method for manufacturing the same

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to nonwoven laminates and methods for making nonwoven laminates.

[0002] In recent years, nonwoven fabrics made of thermoplastic resin fibers have been widely used for various applications due to their excellent breathability, flexibility, light weight, etc. Therefore, nonwoven fabrics are required to have various properties according to the applications, and there is a demand for improvements in these properties.

[0003] For example, nonwoven fabrics made of thermoplastic resin fibers have been proposed for use in adhesive sheet substrates used in adhesive bandages, surgical tapes, and other medical patches, as well as in sanitary goods.

[0004] Patent Document 1 discloses a laminated nonwoven fabric consisting of at least one surface layer, intermediate layer, and back layer, which are integrated by thermocompression bonding, in which the nonwoven fabric of the surface layer is made of thermoplastic synthetic long fibers obtained by a spunbonding method with a fiber diameter of 30 μm or less, the nonwoven fabric of the intermediate layer is made of melt-blown fibers with a fiber diameter of 10 μm or less, and the nonwoven fabric of the back layer is made of thermoplastic synthetic long fibers with a fiber diameter of 10 μm or more and 30 μm or less, and has a basis weight of 3 g / m ２ A medical adhesive tape substrate characterized by having the above has been proposed.

[0005] Patent Document 2 proposes a loop-side nonwoven fabric material as a mechanical fastener, which is used in disposable hygiene products such as diapers, belt-type diapers, incontinence treatment products, and incontinence treatment pads, and which is characterized in that a first upper surface of the nonwoven fabric material includes first relatively large unbonded areas, which are arranged in island-like shapes and spaced apart from each other, and the first relatively large unbonded areas are bounded by a bonded outline and, outside the boundary, are surrounded by second relatively small unbonded areas and are spaced apart from each other by the second relatively small unbonded areas.

[0006] Patent Document 1: Japanese Patent No. 4799097 Patent Document 2: Japanese Patent Publication No. 2008-518649

[0007] Nonwoven fabric laminates comprising a meltblown nonwoven fabric layer and a spunbond nonwoven fabric layer are widely used in applications requiring filtering performance and mechanical strength, such as sanitary materials and medical materials. Nonwoven fabric laminates comprising a meltblown nonwoven fabric layer and a spunbond nonwoven fabric layer are generally fused together by embossing to improve mechanical strength, etc. An embossed nonwoven fabric laminate has an embossed pattern.

[0008] In this disclosure, the term "embossed pattern" refers to a concave-convex pattern formed on a nonwoven fabric laminate by an embossing roll when the nonwoven fabric laminate is embossed. In this disclosure, the term "embossed portion" refers to a recessed portion in the embossed pattern formed by thermocompression bonding of nonwoven fabrics together. The embossed portion includes a portion where a part of the spunbond nonwoven fabric layer and a part of the meltblown nonwoven fabric layer are welded together. In this disclosure, the term "non-embossed portion" refers to a convex portion other than the embossed portion in the embossed pattern.

[0009] In nonwoven fabric laminates having embossed patterns, increasing the weld area ratio improves the tensile strength of the nonwoven fabric laminate. However, increasing the weld area ratio increases the resistance to fluid (e.g., water) passage. Therefore, when the nonwoven fabric laminate is used for filtration and water is passed through, breaks (holes) may occur at the boundary between the embossed and non-embossed areas, resulting in poor water pressure resistance. For this reason, it has not been easy for conventional embossed nonwoven fabric laminates to achieve both high tensile strength and high water pressure resistance.

[0010] The present disclosure has been made in consideration of the above circumstances. An object of one embodiment of the present disclosure is to provide a nonwoven fabric laminate having excellent tensile strength and water pressure resistance. An object of another embodiment of the present disclosure is to provide a method for manufacturing a nonwoven fabric laminate that can produce a nonwoven fabric laminate having excellent tensile strength and water pressure resistance.

[0011] The present disclosure includes the following embodiments: <1> An embossed nonwoven fabric laminate comprising a meltblown nonwoven fabric layer containing a meltblown nonwoven fabric and a spunbond nonwoven fabric layer containing a spunbond nonwoven fabric on both sides of the meltblown nonwoven fabric layer, the laminate having an embossed pattern consisting of embossed portions and non-embossed portions other than the embossed portions, the fused area ratio being 16.0% or more, and the embossed boundary length per unit area being 1.50 mm / mm ２ <2> The nonwoven fabric laminate according to <1>, wherein the average fiber diameter of the fibers contained in the meltblown nonwoven fabric is 1.0 μm or less. <3> The nonwoven fabric laminate according to <1> or <2>, wherein the embossed pattern is composed of a plurality of embossed sections arranged at a distance from one another and the non-embossed sections surrounding the plurality of embossed sections, and wherein the radius of the maximum inscribed circle inscribed in the area surrounded by the plurality of embossed sections is 0.40 mm to 2.50 mm. <4> The nonwoven fabric laminate according to any one of <1> to <3>, wherein the shape of the embossed sections is circular or polygonal in top view. <5> The nonwoven fabric laminate according to <4>, wherein the shape of the embossed sections is elliptical in top view. <6> The nonwoven fabric laminate according to <4>, wherein the water pressure resistance measured in accordance with Method A specified in JIS L 1096:2010 is 1300 mmw. <7> The nonwoven fabric laminate according to any one of <1> to <5>, wherein the air permeability measured by a measuring method using a Frazier air permeability measuring device in accordance with JIS L 1096:2010 is 1.5 cm ３ / cm ２The nonwoven fabric laminate according to any one of <1> to <6>, having a tensile strength of 12 mm / 25 mm or more. <8> The nonwoven fabric laminate according to any one of <1> to <7>, having a tensile strength of 12 mm / 25 mm or more, measured by the following measurement method. (Measurement method) The nonwoven fabric laminate is cut in the MD direction to a length of 150 mm and a width of 25 mm to prepare five test pieces. The 5% strength of the test pieces is measured using a tensile tester. The chuck distance is 100 mm, the test speed is 100 mm / min, and the test is repeated five times (n=5), and the average of the five measured values ​​is used as the evaluation value. <9> The nonwoven fabric laminate according to any one of <1> to <8>, used for filtration. <10> A process of melt-spinning a first thermoplastic resin or a first resin composition containing the first thermoplastic resin by a spunbonding method, and depositing the fibers obtained by melt-spinning on a moving collecting surface to obtain a first spunbond nonwoven fabric layer containing a spunbond nonwoven fabric; a process of using a second thermoplastic resin or a second resin composition containing the second thermoplastic resin by a meltblown method, and depositing the fibers obtained by melt-spinning on a moving collecting surface to obtain a meltblown nonwoven fabric layer; a process of melt-spinning a third thermoplastic resin or a third resin composition containing the third thermoplastic resin by a spunbonding method, and depositing the fibers obtained by melt-spinning on a moving collecting surface to obtain a second spunbond nonwoven fabric layer containing a spunbond nonwoven fabric; and a process of heat-sealing the first spunbond nonwoven fabric layer, the meltblown nonwoven fabric layer, and the second spunbond nonwoven fabric layer in this order by embossing; <11> In the embossing process in the heat-sealing step, a fused area ratio is 16.0% or more, and an embossed boundary length per unit area is 1.50 mm / mm ２ The method for producing a nonwoven fabric laminate according to <10>, wherein an embossed pattern is formed that is composed of an embossed portion and a non-embossed portion other than the embossed portion, as follows:

[0012] According to one embodiment of the present disclosure, a nonwoven fabric laminate having excellent tensile strength and water pressure resistance can be provided. According to another embodiment of the present disclosure, a method for manufacturing a nonwoven fabric laminate capable of manufacturing a nonwoven fabric laminate having excellent tensile strength and water pressure resistance can be provided.

[0013] FIG. 1 is a diagram for explaining the maximum inscribed circle radius. FIG. 2 is a diagram illustrating an example of a manufacturing method for a spunbonded nonwoven fabric. FIG. 3 is a diagram illustrating an example of a manufacturing method for a meltblown nonwoven fabric. FIG. 4 is a diagram illustrating an embossed pattern on the nonwoven fabric laminate of Example 1. FIG. 5 is a diagram illustrating an embossed pattern on the nonwoven fabric laminate of Example 2. FIG. 6 is a diagram illustrating an embossed pattern on the nonwoven fabric laminate of Example 3. FIG. 7 is a diagram illustrating an embossed pattern on the nonwoven fabric laminate of Comparative Example 1. FIG. 8 is a diagram illustrating an embossed pattern on the nonwoven fabric laminate of Comparative Example 2. FIG. 9 is a diagram illustrating an embossed pattern on the nonwoven fabric laminate of Comparative Example 3. FIG. 10 is a diagram illustrating an embossed pattern on the nonwoven fabric laminate of Comparative Example 4. FIG. 11 is a diagram illustrating an embossed pattern on the nonwoven fabric laminate of Example 4.

[0014]

[0023] The following is a detailed description of an example of an embodiment of a nonwoven fabric laminate and a method for producing the same according to the present disclosure. The following description of the requirements may be based on a representative embodiment of the present disclosure, but the present disclosure is not limited to such an embodiment and can be implemented with appropriate modifications within the scope of the present disclosure.

[0015] In the present disclosure, numerical ranges indicated using "to" indicate ranges that include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in numerical ranges described in this specification, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in an example.

[0016] In the present disclosure, when a composition contains multiple substances corresponding to each component, the amount of each component in the composition refers to the total amount of the multiple substances present in the composition, unless otherwise specified. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In the present disclosure, "mass %" and "wt %" are synonymous. In the present disclosure, the term "process" includes not only an independent process, but also a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved.

[0017] <Nonwoven Fabric Laminate> The nonwoven fabric laminate according to the present disclosure (hereinafter also simply referred to as "nonwoven fabric laminate") is an embossed nonwoven fabric laminate comprising a meltblown nonwoven fabric layer and spunbond nonwoven fabric layers on both sides of the meltblown nonwoven fabric layer, the nonwoven fabric laminate having an embossed pattern composed of embossed portions and non-embossed portions other than the embossed portions, the embossed pattern having a fused area ratio of 16.0% or more and an embossed boundary length per unit area of ​​1.50 mm / mm ２ The following is the result.

[0018] The nonwoven fabric laminate according to the present disclosure is preferably used for filtration. The nonwoven fabric laminate can be used, for example, to remove solids from liquids, gases, etc. In one aspect, the nonwoven fabric laminate according to the present disclosure may be a filtration filter that removes solids from liquids, gases, etc. The filtration filter may include the nonwoven fabric laminate and a frame that holds the nonwoven fabric laminate.

[0019] The nonwoven fabric laminate according to the present disclosure has excellent tensile strength and water pressure resistance. Furthermore, the nonwoven fabric laminate according to the present disclosure also has excellent breathability.

[0020] The reason why the nonwoven fabric laminate according to the present disclosure has excellent tensile strength and water pressure resistance is not clear, but it is believed that the tensile strength is improved by having a welded area ratio of 16.0% or more (preferably 19.0% or more), and the embossed boundary length per unit area is 1.50 mm / mm ２ It is presumed that by satisfying the above condition, the resistance to fluid passage is reduced and deterioration of the fibers that make up the nonwoven fabric is suppressed at the boundary between the embossed and non-embossed areas, thereby improving water pressure resistance.

[0021] On the other hand, the prior art including the above-mentioned Patent Documents 1 and 2 does not focus on achieving both tensile strength and water pressure resistance.

[0022] The nonwoven fabric laminate according to the present disclosure is an embossed nonwoven fabric laminate, and has an embossed pattern composed of embossed portions and non-embossed portions other than the embossed portions. In the nonwoven fabric laminate according to the present disclosure, the shape and arrangement of the embossed portions reflect the shape and arrangement of the protrusions formed on the embossing roll.

[0023] The embossed pattern possessed by the nonwoven fabric laminate according to the present disclosure may be in a form consisting of a plurality of embossed portions arranged at a distance from one another and a non-embossed portion surrounding the plurality of embossed portions, or may be in a form consisting of a plurality of non-embossed portions arranged at a distance from one another and an embossed portion surrounding the plurality of embossed portions.

[0024] Since this is advantageous for achieving both tensile strength and water pressure resistance, it is preferable that the embossed pattern be composed of a plurality of embossed portions arranged at a distance from each other and a non-embossed portion surrounding the plurality of embossed portions.

[0025] An embodiment will be described in which the surface is configured with a plurality of embossed portions spaced apart from one another and a non-embossed portion surrounding the plurality of embossed portions.

[0026] The plurality of embossed portions may be arranged regularly or randomly, but are preferably arranged regularly.

[0027] The shape of the embossed portion is preferably circular or polygonal when viewed from above. The circle may be elliptical or perfect circular. Examples of polygonal shapes include quadrilaterals (e.g., diamonds), hexagons, and octagons. When the shape of the embossed portion is quadrilateral, examples include squares, rectangles, and diamonds. In one embodiment, the shape of the embossed portion is preferably elliptical when viewed from above. When the shape of the embossed portion is elliptical, the area ratio in the major axis direction is larger, which tends to increase the tensile strength compared to a perfect circle with the same welding rate, and is advantageous from the viewpoint of the durability of the nonwoven fabric laminate. It is presumed that an increase in the area ratio in the major axis direction facilitates entanglement of the fibers in the CD direction (i.e., the direction perpendicular to the fiber flow direction) of the nonwoven fabric, resulting in increased strength.

[0028] In this disclosure, the "welded area ratio" refers to the ratio of the area of ​​the thermocompression-bonded portion to the area of ​​the nonwoven fabric laminate. The welded area ratio of the nonwoven fabric laminate corresponds to the area ratio of the protrusions of the embossing roll (also referred to as the embossed area ratio). The method for calculating the welded area ratio will be described later.

[0029] The nonwoven fabric laminate according to the present disclosure has a welded area ratio of 16.0% or more, and from the viewpoint of superior tensile strength, the welded area ratio is preferably 19.0% or more. From the viewpoint of fluid permeation rate, the upper limit of the welded area ratio is preferably 30.0% or less, and more preferably 26.0% or less. In one embodiment, the welded area ratio is preferably 8.0% to 30.0%, and more preferably 8.0% to 26.0%.

[0030] In the present disclosure, the "embossed boundary length" refers to the length (mm) of the boundary between the embossed and non-embossed portions of the nonwoven fabric laminate. ２ The method for calculating the embossed boundary length (mm) per square inch will be described later.

[0031] The nonwoven fabric laminate according to the present disclosure has a surface area per unit area (mm ２ The embossed boundary length (mm) per ２ less than 0.50 mm / mm ２ ~1.50mm / mm ２ It is preferable that the thickness is 0.50 mm / mm ２ ~1.00mm / mm ２ It is more preferable that:

[0032] In the nonwoven fabric laminate according to the present disclosure, the embossed pattern is composed of a plurality of embossed sections arranged at a distance from one another and a non-embossed section surrounding the plurality of embossed sections, and the maximum inscribed circle radius inscribed in the area surrounded by the plurality of embossed sections (hereinafter also simply referred to as the "maximum inscribed circle radius") is preferably 0.40 mm to 2.50 mm. The maximum inscribed circle radius is more preferably 0.40 mm to 1.50 mm, as this is advantageous for achieving both tensile strength and water pressure resistance.

[0033] In the present disclosure, the "maximum inscribed circle radius" refers to the radius of the largest circle (virtual circle) that is tangent to the embossed portion in the non-embossed portion when the embossed pattern is viewed from above. A method for calculating the maximum inscribed circle radius will be described later.

[0034] The maximum inscribed circle radius will be explained using the embossed pattern shown in Figure 1 as an example, but it goes without saying that the embossed pattern in the nonwoven fabric laminate according to the present disclosure is not limited to this embossed pattern. In Figure 1, the areas filled in black correspond to the embossed areas, but the embossed and non-embossed areas may have a reversed uneven pattern as long as the above-mentioned welding area ratio and embossed boundary length are satisfied.

[0035] Fig. 1 shows a schematic example of an embossed pattern in which a plurality of square embossed portions 12 are arranged at regular intervals in a non-embossed portion 10. In Fig. 1, the imaginary circle designated by the reference numeral 14 is the largest inscribed circle, and the double-headed arrow X indicates the maximum inscribed circle radius.

[0036] In the present disclosure, the welding area ratio (%), the embossed boundary length per unit area (mm / mm ２ ), and the maximum inscribed circle radius (mm) shall be calculated using the following method.

[0037] First, the following processes (a1) and (a2) are performed on a sample of the nonwoven fabric laminate to be measured. (a1): Prepare a sample of the nonwoven fabric laminate to be measured. Scan the prepared sample using a scanner at a resolution of 6,400 dpi (3 x 4 inches). A 2D image scanner (manufactured by Epson Corporation) can be used as the scanner. (a2): From the scanned image obtained in (a1), an image of 16,000 pixels square is cut out, and the image is binarized by representing embossed areas as black pixels and non-embossed areas as white pixels. The binarization threshold may be set manually or automatically using Otsu's binarization method or the like.

[0038] Next, the image was processed using image analysis software, and the welding area ratio (%) and embossed boundary length per unit area (mm / mm ２ ) and the maximum inscribed circle radius [mm].

[0039] Welding Area Ratio (%) In the obtained binarized image, the ratio (%) of black pixels to the total number of black pixels and white pixels is calculated.

[0040] Embossed boundary length per unit area (mm / mm ２In the obtained binarized image, the contour portion surrounding the black pixels is extracted by image analysis. The sum of the lengths (mm) of the contours of the embossed portion in the analysis region is calculated as the area (mm) of the analysis region. ２ ) and the value obtained by dividing by (mm / mm ２ ) is calculated.

[0041] Maximum inscribed circle radius [mm] Calculate the distance from a white pixel located on the black-white boundary to the nearest black pixel for all white pixels. The white pixel position with the maximum value is set as the center of the virtual inscribed circle, and the maximum inscribed circle radius is calculated as the distance from the white pixel to the nearest black pixel.

[0042] The tensile strength (5% strength) of the nonwoven fabric laminate according to the present disclosure is preferably 12.0 [mm / 25 mm] or more, more preferably 13.0 [mm / 25 mm] or more, and even more preferably 14.0 [mm / 25 mm] or more. The upper limit of the tensile strength of the nonwoven fabric laminate is not particularly limited, and may be 13.0 [mm / 25 mm] or less. In the present disclosure, the tensile strength (5% strength) of the nonwoven fabric laminate is measured using a tensile tester. For example, a tensile tester (product name: E3-L) manufactured by Toyo Seiki Seisakusho, Ltd. can be used as the tensile tester. Specifically, the tensile strength of the nonwoven fabric laminate is measured using the measurement method and conditions described in the Examples below.

[0043] The nonwoven fabric laminate according to the present disclosure has an air permeability of 0.1 cm ３ / cm ２ s or more, and 1.0 cm ３ / cm ２ More preferably, it is 1.5 cm or more. ３ / cm ２ The upper limit of the breathability of the nonwoven fabric laminate is not particularly limited, and is preferably 20.0 cm ３ / cm ２In the present disclosure, the air permeability of the nonwoven fabric laminate is measured by a measurement method using a Frazier air permeability tester in accordance with JIS L 1096:2010. Specifically, the air permeability of the nonwoven fabric laminate is measured by the measurement method and measurement conditions described in the Examples below.

[0044] The water pressure resistance of the nonwoven fabric laminate according to the present disclosure is preferably 1300 mmw.c or more, and more preferably 1600 mmw.c or more. The upper limit of the water pressure resistance of the nonwoven fabric laminate is not particularly limited, and is up to 3000 cmw. ３ / cm ２ In the present disclosure, the water pressure resistance of the nonwoven fabric laminate is measured in accordance with Method A (low water pressure method) specified in JIS L 1096:2010. Specifically, the air permeability of the nonwoven fabric laminate is measured using the measurement method and conditions described in the Examples below.

[0045] In one aspect, the nonwoven fabric laminate according to the present disclosure preferably has a tensile strength (5% strength) of 12.0 mm / 25 mm or more and a water pressure resistance of 1300 mmw.c or more. In another aspect, the nonwoven fabric laminate according to the present disclosure preferably has a tensile strength (5% strength) of 12.0 mm / 25 mm or more, a water pressure resistance of 1300 mmw.c or more, and an air permeability of 0.1 cm ３ / cm ２ The more preferable ranges and even more preferable ranges for the tensile strength, water pressure resistance, and air permeability are as described above.

[0046] The nonwoven fabric laminate according to the present disclosure has an embossed pattern composed of embossed portions and non-embossed portions other than the embossed portions, and has a fused area ratio of 16.0% or more and an embossed boundary length per unit area of ​​1.50 mm / mm ２ By satisfying the following conditions, the above-mentioned tensile strength, breathability, and water pressure resistance can be exhibited.

[0047] The total basis weight of the nonwoven fabric laminate according to the present disclosure is 30 g / m ２ ~100g / m ２ It is preferable that the thickness is 36 g / m ２ ~95g / m２ More preferably, it is 40 g / m ２ ~80g / m ２ It is more preferable that:

[0048] The embossing rate of the nonwoven fabric laminate may be less than 100%, 60% to 90%, or 60% to less than 90%. The embossing rate can be determined as follows. First, a piece of black construction paper and the nonwoven fabric laminate are placed on a desk in this order. Next, an arbitrary portion of the nonwoven fabric laminate is selected, and a photograph is taken from directly above using a digital camera, showing 15 or more embossed fused portions without any cut-off. The above-described photographing operation is repeated while changing the position of the arbitrary portion to be photographed until 100 or more embossed fused portions are shown without any cut-off. Using the photograph of the embossed fused portions thus photographed, the numbers E1 and E2 of the embossed fused portions are counted as follows. E1: Total number of embossed fused areas that are visible without being cut off E2: Of the embossed fused areas that are visible without being cut off, the number of areas where the black drawing paper is hidden by unfused fibers Round off the value obtained using the following formula to find the embossed fusion rate (%): Embossed fusion rate (%) = [1 - (E2 / E1)] x 100

[0049] Depending on the purpose, the nonwoven fabric laminate according to the present disclosure may be laminated with a material such as a nonwoven fabric other than a knitted fabric, a woven fabric, a spunbonded nonwoven fabric, or a meltblown nonwoven fabric (also referred to as "other nonwoven fabrics"). The other nonwoven fabrics are not particularly limited and include, but are not limited to, wetlaid nonwoven fabrics, spunlaced nonwoven fabrics, drylaid nonwoven fabrics, dry pulp nonwoven fabrics, airlaid nonwoven fabrics, waterjet nonwoven fabrics, flash-spun nonwoven fabrics, spread-fiber nonwoven fabrics, needle-punched nonwoven fabrics, and various known short-fiber nonwoven fabrics and long-fiber nonwoven fabrics (for example, long-fiber cellulose nonwoven fabrics).

[0050] The nonwoven fabric laminate according to the present disclosure may contain commonly used additives such as antioxidants, weather stabilizers, light stabilizers, antistatic agents, hydrophilic agents, antifogging agents, antiblocking agents, lubricants, nucleating agents, and pigments, provided that the object of the present disclosure is not impaired. For example, the spunbond nonwoven fabric layer and the meltblown nonwoven fabric layer may or may not independently contain additives. These additives may be blended, as needed, into the thermoplastic resin that can be used to produce the spunbond nonwoven fabric or the meltblown nonwoven fabric.

[0051] The spunbond nonwoven fabric and meltblown nonwoven fabric included in the nonwoven fabric laminate according to the present disclosure will be described in detail below.

[0052] [Spunbond Nonwoven Fabric Layer] The nonwoven fabric laminate according to the present disclosure includes a spunbond nonwoven fabric layer (hereinafter also simply referred to as "spunbond nonwoven fabric layer") containing a spunbond nonwoven fabric on both sides of a meltblown nonwoven fabric layer (hereinafter also simply referred to as "meltblown nonwoven fabric layer") containing a meltblown nonwoven fabric. The nonwoven fabric laminate according to the present disclosure may include one or more spunbond nonwoven fabric layers on each side of the meltblown nonwoven fabric layer.

[0053] By providing spunbond nonwoven fabric layers on both sides of the meltblown nonwoven fabric layer, the spunbond nonwoven fabric layers can protect the meltblown nonwoven fabric. Specifically, this prevents the embossing roll from directly contacting the meltblown nonwoven fabric layer during the embossing process described below. This prevents holes caused by thermal damage to the meltblown fibers and increases water pressure resistance. The spunbond nonwoven fabric layer also prevents damage to the meltblown nonwoven fabric due to friction when handling the nonwoven fabric laminate. Furthermore, the spunbond nonwoven fabric layer prevents clogging of the meltblown nonwoven fabric layer in the non-embossed areas described below and ensures a high liquid permeability rate during filtration. The spunbond nonwoven fabric layer also improves the suppression of fuzzing on the surface of the nonwoven fabric laminate. Furthermore, providing a spunbond nonwoven fabric layer downstream of the meltblown nonwoven fabric layer in the filtration direction is preferable because it prevents deformation of the meltblown nonwoven fabric layer due to pressure and increases water pressure resistance.

[0054] Furthermore, when a nonwoven fabric laminate is manufactured using the method for manufacturing a nonwoven fabric laminate according to the present disclosure described below, in which a spunbond nonwoven fabric layer and a meltblown nonwoven fabric layer are collected on separate moving collecting members, and then these nonwoven fabric webs are laminated and thermally fused, the spunbond nonwoven fabric constituting the spunbond nonwoven fabric layer is preferably subjected to preliminary fiber entanglement using a calendar roll or an embossing roll, from the viewpoint of preventing fiber shedding in the spunbond nonwoven fabric layer and maintaining the integrity of the fabric. When an embossing roll is used for preliminary fiber entanglement, the embossed area ratio of the spunbond nonwoven fabric is preferably 5% to 40% from the viewpoint of improving strength and water pressure resistance.

[0055] The fibers contained in the spunbond nonwoven fabric preferably contain a thermoplastic resin. Examples of the thermoplastic resin include, but are not limited to, olefin polymers, such as homopolymers or copolymers of olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, and 4-methyl-1-hexene; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyamides such as nylon-6, nylon-66, and polymetaxylene adipamide; polyvinyl chloride; polyimide; ethylene-vinyl acetate copolymer; polyacrylonitrile; polycarbonate; polystyrene; and ionomers. The thermoplastic resin may consist of one type or a mixture of two or more types.

[0056] The spunbond nonwoven fabric preferably contains an olefin-based polymer. Examples of the olefin-based polymer include ethylene-based polymers such as ethylene random copolymers such as ethylene-propylene random copolymers, high-pressure low-density polyethylene, linear low-density polyethylene (LLDPE), high-density polyethylene, and ethylene-1-butene random copolymers; propylene-based polymers such as polypropylene (propylene homopolymer), propylene-ethylene random copolymers, and propylene-1-butene random copolymers; poly-1-butene; and poly-4-methyl-1-pentene. The thermoplastic resin preferably contains a propylene-based polymer from the viewpoint of excellent spinnability, stretchability, etc.

[0057] Examples of propylene-based polymers include propylene homopolymers and propylene random copolymers, which are copolymers of propylene as a main component and one or more olefins as secondary components. Among these, propylene homopolymers are preferred from the viewpoints of tensile strength and water pressure resistance. In the propylene random copolymer, the content of olefin-derived structural units is preferably 1 mol% to 10 mol% of the total, more preferably 1 mol% to 6 mol% of the total.

[0058] The olefin used for copolymerization of the propylene random copolymer is preferably ethylene or an α-olefin having 4 or more carbon atoms, more preferably ethylene or an α-olefin having 4 to 8 carbon atoms. Specific preferred α-olefins include 1-butene, 1-pentene, 1-hexene, 1-octene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, and 4-methyl-1-hexene.

[0059] The melting point (Tm) of the propylene polymer is not particularly limited, and may be, for example, 125°C or higher, or may be 125°C to 170°C.

[0060] In the present disclosure, the melting point can be measured using differential scanning calorimetry (DSC) as follows. Using a PerkinElmer DSC Pyris1 or SII NanoTechnology DSC7020 as a differential scanning calorimeter (DSC), a sample (approximately 5 mg) is heated to a target temperature set for each thermoplastic resin (230°C for propylene-based polymers) under a nitrogen atmosphere (20 mL / min), held at that temperature for 3 minutes, then cooled to 30°C at 10°C / min, held at 30°C for 1 minute, and heated to the target temperature at 10°C / min. The melting point (Tm) is calculated from the peak apex of the crystalline melting peak during the heating process. When multiple crystalline melting peaks are observed, the peak on the higher temperature side is taken as the melting point (Tm).

[0061] When a propylene-olefin random copolymer is used as the propylene polymer, the melting point (Tm) thereof is preferably 153° C. or lower, more preferably 125° C. to 150° C. When a propylene homopolymer is used as the propylene polymer, the melting point (Tm) thereof is preferably 155° C. or higher, more preferably 157° C. to 165° C.

[0062] The melt flow rate (MFR) (ASTM D-1238, 230°C, load 2160 g) of the propylene polymer is not particularly limited as long as a nonwoven fabric can be produced, and is, for example, preferably 10 g / 10 min to 100 g / 10 min, more preferably 20 g / 10 min to 70 g / 10 min. When a propylene polymer having an MFR of 10 g / 10 min or more is used, the melt viscosity tends to be low and the spinnability tends to be improved, while when a propylene polymer having an MFR of 100 g / 10 min or less is used, the tensile strength and other properties of the resulting nonwoven fabric tend to be improved.

[0063] Propylene-based polymers are usually obtained by homopolymerizing propylene or copolymerizing propylene with a small amount of an α-olefin through slurry polymerization, gas phase polymerization, or bulk polymerization using a Ziegler-Natta catalyst in which a so-called titanium-containing solid transition metal component is combined with an organometallic component, or a metallocene catalyst in which a transition metal compound of Groups 4 to 6 of the periodic table having at least one cyclopentadienyl skeleton and a cocatalyst component is used.

[0064] The content of the thermoplastic resin (preferably an olefin polymer, more preferably a propylene homopolymer) contained in the spunbond nonwoven fabric may be 50% by mass or more, 70% by mass or more, 90% by mass or more, or 95% by mass or more, based on the total amount of the spunbond nonwoven fabric. The content of the thermoplastic resin (preferably an olefin polymer, more preferably a propylene homopolymer) contained in the spunbond nonwoven fabric may be 100% by mass or less, or 99% by mass or less, based on the total amount of the spunbond nonwoven fabric.

[0065] The average fiber diameter of the fibers contained in the spunbonded nonwoven fabric is not particularly limited, and from the viewpoints of lightness and tensile strength, it is preferably 15 μm to 40 μm, more preferably 15 μm to 30 μm, and even more preferably 15 μm to 20 μm. A fiber diameter of 30 μm or less results in a dense structure of the spunbonded nonwoven fabric, which is advantageous from the viewpoint of water pressure resistance. A fiber diameter of 15 μm or more reduces liquid passage resistance, which is advantageous from the viewpoint of filtration rate.

[0066] In the present disclosure, the average fiber diameter of fibers can be determined as follows: A nonwoven fabric to be measured is observed under an optical microscope (for example, ECLIPSE E-400 manufactured by Nikon Corporation), 100 fibers are selected from the fibers forming the nonwoven fabric on the screen, and the fiber diameters are measured, and the average value is taken as the average fiber diameter of the fibers.

[0067] The basis weight of the spunbond nonwoven fabric layer is 10 g / m ２ ~40g / m ２ From the viewpoint of tensile strength, the basis weight of the spunbond nonwoven fabric layer is preferably 12 g / m ２It is preferable that the content is 15 g / m or more. ２ From the viewpoint of weight reduction, the basis weight of the spunbond nonwoven fabric layer is preferably 30 g / m or more. ２ It is preferable that the weight is 20 g / m or less. ２ It is more preferable that the weight per unit area of ​​the nonwoven fabric layer is equal to or less than the following: In the present disclosure, the weight per unit area of ​​the nonwoven fabric layer refers to the weight per unit area of ​​a single layer.

[0068] [Meltblown Nonwoven Fabric Layer] The nonwoven fabric laminate according to the present disclosure comprises a meltblown nonwoven fabric layer containing a meltblown nonwoven fabric. The nonwoven fabric laminate may comprise one meltblown nonwoven fabric layer, or two or more meltblown nonwoven fabric layers. When comprising two or more meltblown nonwoven fabric layers, the two or more meltblown nonwoven fabric layers may be directly laminated together, or another layer (e.g., a spunbond nonwoven fabric layer) may be interposed between the meltblown nonwoven fabric layers.

[0069] The average fiber diameter of the fibers contained in the meltblown nonwoven fabric is preferably 1.0 μm or less. The nonwoven fabric laminate according to the present disclosure may include a meltblown nonwoven fabric layer having an average fiber diameter of more than 1.0 μm, as well as a meltblown nonwoven fabric layer having an average fiber diameter of 1.0 μm or less. Alternatively, the nonwoven fabric laminate according to the present disclosure may not include a meltblown nonwoven fabric layer having an average fiber diameter of more than 1.0 μm. Hereinafter, meltblown nonwoven fabric layers having an average fiber diameter of 1.0 μm or less and meltblown nonwoven fabric layers having an average fiber diameter of more than 1.0 μm are collectively referred to as meltblown nonwoven fabric layers. A meltblown nonwoven fabric layer having an average fiber diameter of 1.0 μm or less is referred to as a specific meltblown nonwoven fabric layer.

[0070] In the nonwoven fabric laminate, it is preferable that spunbond nonwoven fabric layers are laminated on both sides of a meltblown nonwoven fabric layer, and it is more preferable that the nonwoven fabric laminate has an SMS three-layer structure in which a spunbond nonwoven fabric layer, a meltblown nonwoven fabric layer, and a spunbond nonwoven fabric layer are laminated in this order.

[0071] The fibers contained in the meltblown nonwoven fabric preferably contain a thermoplastic resin. The thermoplastic resin is not particularly limited, and may be the same as the examples given in the section on the spunbond nonwoven fabric layer.

[0072] The meltblown nonwoven fabric preferably contains an olefin-based polymer. Examples of the olefin-based polymer include ethylene-based polymers such as ethylene random copolymers such as ethylene-propylene random copolymers, high-pressure low-density polyethylene, linear low-density polyethylene (LLDPE), high-density polyethylene, and ethylene-1-butene random copolymers; propylene-based polymers such as polypropylene (propylene homopolymer), propylene-ethylene random copolymers, and propylene-1-butene random copolymers; poly-1-butene; and poly-4-methyl-1-pentene. The thermoplastic resin preferably contains a propylene-based polymer from the viewpoint of excellent spinnability, stretchability, and the like.

[0073] Examples of propylene-based polymers include propylene homopolymers and propylene random copolymers, which are copolymers of propylene as a main component and one or more olefins as secondary components. Among these, propylene homopolymers are preferred from the viewpoint of water pressure resistance. In the propylene random copolymer, the content of olefin-derived structural units is preferably 1 mol% to 10 mol% of the total, more preferably 1 mol% to 6 mol% of the total.

[0074] The olefin used for copolymerization of the propylene random copolymer is preferably ethylene or an α-olefin having 4 or more carbon atoms, more preferably ethylene or an α-olefin having 4 to 8 carbon atoms. Specific preferred α-olefins include 1-butene, 1-pentene, 1-hexene, 1-octene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, and 4-methyl-1-hexene.

[0075] When the meltblown nonwoven fabric contains a propylene-based polymer, the preferred conditions such as the melting point of the propylene-based polymer are the same as those described above in the section on the spunbond nonwoven fabric layer.

[0076] The melt flow rate (MFR) (ASTM D-1238, 230°C, load 2160 g) of the propylene polymer contained in the meltblown nonwoven fabric is not particularly limited as long as the nonwoven fabric can be produced, and is, for example, preferably 100 g / 10 min to 3000 g / 10 min, more preferably 500 g / 10 min to 2000 g / 10 min. When a propylene polymer with an MFR of 100 g / 10 min or more is used, the melt viscosity tends to be low and the fiber diameter tends to be thin, while when a propylene polymer with an MFR of 3000 g / 10 min or less is used, molding defects due to fusion of fibers during spinning tend to be suppressed.

[0077] The content of the thermoplastic resin (preferably an olefin polymer, more preferably a propylene homopolymer) contained in the meltblown nonwoven fabric may be 50% by mass or more, 70% by mass or more, 90% by mass or more, or 95% by mass or more, based on the total amount of the meltblown nonwoven fabric. The content of the thermoplastic resin (preferably an olefin polymer, more preferably a propylene homopolymer) contained in the meltblown nonwoven fabric may be 100% by mass or less, or 99% by mass or less, based on the total amount of the meltblown nonwoven fabric.

[0078] In a specific meltblown nonwoven fabric layer, the average fiber diameter of the fibers contained in the meltblown nonwoven fabric is preferably 0.1 μm to 1.0 μm, more preferably 0.2 μm to 0.9 μm, and even more preferably 0.4 μm to 0.8 μm, from the viewpoints of tensile strength and filter efficiency. When the fiber diameter is 1.0 μm or less, the structure of the meltblown nonwoven fabric becomes dense and it is possible to capture finer solid particles. When the fiber diameter is 0.1 μm or more, the liquid passage resistance is reduced, which is advantageous in terms of filtration speed.

[0079] The basis weight of the meltblown nonwoven fabric layer is 10 g / m ２ ~20g / m ２ From the viewpoint of tensile strength, the basis weight of the meltblown nonwoven fabric is preferably 12 g / m ２ It is preferable that the content is 15 g / m or more. ２From the viewpoint of weight reduction, the basis weight of the meltblown nonwoven fabric is preferably 30 g / m or more. ２ It is preferable that the weight is 20 g / m or less. ２ More preferably, it is:

[0080] The nonwoven fabric laminate according to the present disclosure can be produced by the method for producing a nonwoven fabric laminate according to the present disclosure. The method for producing a nonwoven fabric laminate according to the present disclosure will be described below.

[0081] <Method for manufacturing nonwoven fabric laminate> A method for manufacturing a nonwoven fabric laminate according to the present disclosure includes the steps of melt-spinning a first thermoplastic resin or a first resin composition containing the first thermoplastic resin by a spunbonding method, and depositing the fibers obtained by melt-spinning on a moving collecting surface to obtain a spunbonded nonwoven fabric layer containing a first spunbonded nonwoven fabric; using a second thermoplastic resin or a second resin composition containing the second thermoplastic resin by a meltblown method, and depositing the fibers obtained by melt-spinning on a moving collecting surface to obtain a meltblown nonwoven fabric layer containing a meltblown nonwoven fabric; heat-sealing the first spunbonded nonwoven fabric and the meltblown nonwoven fabric by embossing; melt-spinning a third thermoplastic resin or a third resin composition containing the third thermoplastic resin by a spunbonding method, and depositing the fibers obtained by melt-spinning on a moving collecting surface to obtain a second spunbonded nonwoven fabric layer containing a spunbonded nonwoven fabric; and a step of heat-sealing the first spunbond nonwoven fabric layer, the meltblown nonwoven fabric layer, and the second spunbond nonwoven fabric layer in this order by embossing.

[0082] Preferred examples of the first thermoplastic resin are the same as those described above in the section on spunbond nonwoven fabrics. Preferred examples of the first resin composition include resin compositions containing the thermoplastic resin described above in the section on spunbond nonwoven fabrics and the additives described above.

[0083] Preferred examples of the second thermoplastic resin are the same as those described above in the section on meltblown nonwoven fabrics. Preferred examples of the second resin composition include resin compositions containing the thermoplastic resins described above in the section on meltblown nonwoven fabrics and the additives described above.

[0084] The first spunbond nonwoven fabric layer and the second spunbond nonwoven fabric layer described below (hereinafter collectively referred to as "spunbond nonwoven fabric layers") can be produced by a closed spunbond process as disclosed in JP-A-60-155765, Japanese Patent No. 3,442,896, Japanese Patent No. 3,883,818, etc.

[0085] An example of a method for producing a spunbonded nonwoven fabric will be described with reference to Figure 2. In the method for producing a spunbonded nonwoven fabric, for example, a production apparatus equipped with a spinning section 110 having a cooling chamber with a closed structure as shown in Figure 2 can be used. In some embodiments, the cooling chamber may be an open type.

[0086] The nonwoven fabric manufacturing apparatus includes a spinning section 110 that melt-spins a molten first thermoplastic resin or a first resin composition and cools and stretches the melt-spun continuous fiber groups 22, a movable collection member 51 that collects the stretched continuous fiber groups 22, and a suction unit 39 that efficiently collects the continuous fiber groups 22 on the movable collection member 51.

[0087] The spinning section 110 has an extruder 32 that extrudes the first thermoplastic resin or the first resin composition, a spinneret 34 that discharges the molten first thermoplastic resin or the first resin composition from a spinning nozzle, a cooling chamber 38C that cools the continuous fiber groups 22 discharged from the spinning nozzle of the spinneret 34, cooling air supply sections 38A and 38B that supply cooling air 36, and a stretching section 38D that stretches the continuous fiber groups 22.

[0088] In the spinning section 110, the first thermoplastic resin or the first resin composition is extruded and introduced into the spinneret 34. Next, the molten first thermoplastic resin or the first resin composition is discharged from the spinning nozzle of the spinneret 34 and melt-spun. The melting temperature of the first thermoplastic resin or the like is not particularly limited as long as it is possible to melt the first thermoplastic resin or the like.

[0089] The melt-spun continuous fibers 22 are introduced into a cooling chamber 38C. The continuous fibers 22 are cooled by cooling air 36 supplied from either or both of a cooling air supply unit 38A and a cooling air supply unit 38B. The cooled continuous fibers 22 are introduced into a drawing unit 38D provided downstream of the cooling chamber 38C. The drawing unit 38D is provided in the shape of a narrow passage. The speed of the cooling air increases in the narrow passage, thereby drawing the continuous fibers 22 introduced into the drawing unit 38D.

[0090] The drawn continuous fibers 22 are collected by the moving collecting member 51, and the nonwoven web 43 made of the collected continuous fibers 22 corresponds to the spunbond nonwoven fabric layer before heat fusion.

[0091] The meltblown nonwoven fabric layer can be produced by a meltblowing process using an ultrafine fiber nonwoven fabric production apparatus as disclosed in Japanese Patent No. 6,339,124 and the like.

[0092] An example of a method for producing a meltblown nonwoven fabric will be described with reference to FIG.

[0093] 3 is a schematic diagram showing an example of the configuration of a meltblown nonwoven fabric manufacturing apparatus 100. As shown in FIG. 3, the nonwoven fabric manufacturing apparatus 100 includes an extruder 20, a die (spinneret) 23, and a moving collection member 51.

[0094] The extruder 20 has a hopper 21 and a compression section 22. The extruder 20 melts the solid second thermoplastic resin or the solid second resin composition introduced into the hopper 21 in the compression section 22. The extruder 20 may be a single-screw extruder or a multi-screw extruder.

[0095] The die (spinning nozzle) 23 is disposed connected to the tip of the extruder 20. The die 23 has a plurality of spinning nozzles 24 and two gas nozzles 25.

[0096] The spinning nozzles 24 are typically arranged in a row. The molten second thermoplastic resin or second resin composition P conveyed from the extruder 20 is introduced into the spinning nozzle 24, and the second thermoplastic resin or the like is extruded in a fibrous form from the nozzle opening. The diameter of the spinning nozzle can be, for example, 0.05 mm to 0.80 mm. The melting temperature of the second thermoplastic resin or the like can be adjusted by the set temperature of the die 23.

[0097] The two gas nozzles (air nozzles) 25 are arranged near the nozzle openings of the spinning nozzles 24, specifically, on both sides of the row of multiple spinning nozzles 24. The gas nozzles 25 inject heated gas (heated compressed gas) near the openings of the spinning nozzles 24. As shown in Figure 2, the gas nozzles 25 inject heated gas onto the second thermoplastic resin, etc. immediately after it has been discharged from the openings of the spinning nozzles 24.

[0098] The heating gas supplied to the gas nozzle 25 is supplied from a gas heating device 50. The temperature of the heating gas can be adjusted by a heating temperature adjusting means (not shown) attached to the gas heating device 50.

[0099] The second thermoplastic resin or the like discharged from the opening of the spinning nozzle 24 is stretched and thinned by heated gas, and the resulting fibrous material is collected on a moving collection member 51. An air suction unit 44 is arranged on the back side of the collection surface of the moving collection member 51, and rollers (not shown) are arranged to support and transport the moving collection member 51. The air suction unit 44 is connected to a blower (not shown). A nonwoven web 41 made of fibrous material is collected on the moving collection member 51. The nonwoven web 41 corresponds to the meltblown nonwoven fabric layer before heat fusion.

[0100] In the manufacturing method according to the present disclosure, the first spunbond nonwoven fabric layer and the meltblown nonwoven fabric layer obtained as described above are heat-sealed by embossing. The nonwoven web corresponding to the first spunbond nonwoven fabric layer and the nonwoven web corresponding to the meltblown nonwoven fabric may be collected on separate moving collecting members, and then these nonwoven webs may be stacked and then heat-sealed. Alternatively, the nonwoven web corresponding to the first spunbond nonwoven fabric layer and the nonwoven web corresponding to the meltblown nonwoven fabric may be stacked in order on the same moving collecting member, and then these nonwoven webs may be heat-sealed.

[0101] In the manufacturing method according to the present disclosure, a third thermoplastic resin or a third resin composition containing the third thermoplastic resin is melt-spun by a spunbonding method, and the fibers obtained by melt spinning are deposited on a moving collecting surface to form a second spunbond nonwoven fabric layer containing a spunbond nonwoven fabric.

[0102] The second spunbond nonwoven fabric layer may be prepared separately from the first spunbond nonwoven fabric layer and the meltblown nonwoven fabric layer, and then these layers may be laminated together. Alternatively, nonwoven webs corresponding to each nonwoven fabric layer may be prepared in order on the same moving collection member, and then the nonwoven fabric layers may be laminated together. This results in a pre-heat-sealed laminate in which the first spunbond nonwoven fabric layer, the meltblown nonwoven fabric layer, and the second spunbond nonwoven fabric layer are laminated in this order. This laminate may be heat-sealed by embossing.

[0103] From the viewpoint of freely designing the basis weight and fiber diameter of each of the spunbonded nonwoven fabric layer and the meltblown nonwoven fabric layer, it is preferable that the first spunbonded nonwoven fabric layer, the meltblown nonwoven fabric layer, and the second spunbonded nonwoven fabric layer are collected on separate moving collecting members, and then these nonwoven fabric webs are laminated and then heat-sealed.

[0104] This allows for the production of a nonwoven fabric laminate in which spunbonded nonwoven fabric layers are laminated on both sides of a meltblown nonwoven fabric layer. The method for melt-spinning the third thermoplastic resin or the third resin composition by the spunbonding method is the same as the method for melt-spinning the first thermoplastic resin or the first resin composition by the spunbonding method.

[0105] In the heat-sealing step, the embossing method is not particularly limited.

[0106] In the embossing process in the heat fusion step, the fusion area ratio is 16.0% or more, and the embossed boundary length per unit area is 1.50 mm / mm ２ It is preferable to form an embossed pattern consisting of an embossed portion and a non-embossed portion other than the embossed portion, as follows: In other words, the nonwoven fabric laminate according to the present disclosure can be manufactured by the method for manufacturing a nonwoven fabric laminate according to the present disclosure.

[0107] In the heat-sealing step, optimizing the embossing temperature, line pressure, and other conditions can prevent excessive heat transfer to the meltblown nonwoven fabric layer and, ultimately, hole breakage due to thermal damage to the meltblown fibers, thereby increasing water pressure resistance. If the embossing is too weak, the nonwoven fabric laminate will not be able to withstand the pressure when a load is applied, i.e., when measuring water pressure resistance, and will tend to be unable to achieve sufficient water pressure resistance. On the other hand, if the embossing is too strong, the edges of the embossed markings will be excessively damaged, making them more susceptible to hole breakage.

[0108] The optimum temperature and linear pressure vary depending on the characteristics and speed of the manufacturing equipment, so the specific conditions for temperature and linear pressure may be determined appropriately. The temperature is preferably approximately 105° C. or higher and 180° C. or lower. The linear pressure is preferably approximately 20 N / mm or higher and 150 N / mm or lower.

[0109] In some embodiments, the embossing temperature may be 105° C. to 125° C., and from the viewpoint of improving the tensile strength and water pressure resistance, it may be 115° C. The embossing temperature may be 115° C. from the viewpoint of increasing the water pressure resistance by ensuring the embossing strength.

[0110] In some embodiments, the embossing line pressure can be 150 N / mm or less, and from the viewpoint of improving the tensile strength and water pressure resistance, it may be 20 N / mm or more.

[0111] The embossing rate of the nonwoven fabric laminate can be adjusted by adjusting the embossing conditions in the heat-sealing step. For example, increasing the embossing temperature, embossing line pressure, etc. tends to increase the embossing rate, while increasing the embossing speed tends to decrease the embossing rate.

[0112] Whether the embossing is adequate can be confirmed by the state of breakage when measuring the tensile strength of an embossed sample. If the embossing is too weak, sufficient strength is not obtained and the fibers stretch while fraying, resulting in a large difference between the elongation when the maximum stress is detected and the elongation at break. If the embossing is too strong, the embossed pattern breaks at the edge of the embossed mark, resulting in a small difference between the elongation when the maximum stress is detected and the elongation at break, or the elongation at maximum strength detection and the elongation at break will be the same.

[0113] Hereinafter, embodiments of the nonwoven fabric laminate and the method for producing the same according to the present disclosure will be described in more detail based on examples. However, the nonwoven fabric laminate and the method for producing the same according to the present disclosure are not limited to the following examples as long as they do not deviate from the gist of the disclosure.

[0114] Physical properties in the examples and comparative examples were measured by the following methods. In Table 1, "-" means that the physical property was not measured, the process was not carried out, no resin was used, etc.

[0115] (1) Weight [g / m ２ Ten test pieces measuring 100 mm (machine direction: MD) x 100 mm (direction perpendicular to the machine direction: CD) were taken from the nonwoven fabric laminate to be measured. The test pieces were taken from 10 locations in the CD direction. Next, the mass [g] of each test piece was measured using a top-pan electronic balance (manufactured by Kensei Kogyo Co., Ltd.) in an environment of 20°C and a relative humidity of 50% RH. The average mass of each test piece was calculated. A 1m ２ The weight per unit area [g] of each test piece was calculated by rounding off to the nearest whole number. ２ 〕

[0116] (2) Tensile Strength The tensile strength of the nonwoven fabric laminate was evaluated as follows. The nonwoven fabric laminate was cut in the MD direction to a length of 150 mm and a width of 25 mm to prepare five test pieces. The 5% strength of the test pieces was measured using a tensile tester (product name: E3-L, manufactured by Toyo Seiki Seisakusho Co., Ltd.). However, the distance between chucks was 100 mm and the speed was 100 mm / min. The test was repeated five times (n=5), and the average value of the five measured values ​​obtained was used as the evaluation value. The evaluation criteria were as follows. Evaluation A: 13.0 N / mm ２ Rating B: 12.0 N / mm ２ Above, 13.0N / mm ２ Less than Rating C: 12.0 N / mm ２ less than

[0117] (3) Air Permeability The air permeability of the nonwoven fabric laminate was evaluated as follows by a measurement method using a Frazier air permeability tester in accordance with JIS L 1096:2010. The nonwoven fabric laminate was cut into a length of 150 mm and a width of 150 mm in the MD direction to prepare three test pieces. The air permeability was measured using an air permeability tester (product name: FX 3300, manufactured by TEXTEST Co., Ltd.). The air permeability direction was from the embossed surface to the non-embossed surface. The test was repeated three times (n = 3), and the average value of the three measured values ​​was used as the evaluation value. The evaluation result "A" in Table 1 indicates that the air permeability was "1.50 cm ３ / cm ２ ・ Indicates that it is "s or more".

[0118] (4) Water Pressure Resistance The water pressure resistance of the nonwoven fabric laminate was measured in accordance with Method A (low water pressure method) specified in JIS L 1096:2010, and evaluated as follows. The nonwoven fabric laminate was cut into a vertical width of 150 mm and a horizontal width of 150 mm in the MD direction to prepare three test pieces. The pressure at which water droplets leaked from the test piece was measured using a water pressure resistance tester (product name: FX 3000-IV, manufactured by TEXTEST Co., Ltd.). The pressure at the first three points at which water droplets leaked was measured, and the pressure at the third point was used as the evaluation value. The air permeability direction was from the embossed side to the non-embossed side. The test was repeated three times (n = 3), and the average of the three measured values ​​obtained was used as the evaluation value. The evaluation criteria were as follows: Evaluation A: 1600 mmw.c or more Evaluation B: 1300 mmw.c or more, less than 1600 mmw.c Evaluation C: 1300 mmw.c or more Less than c

[0119] (5) Welding area ratio (%), embossed boundary length per unit area (mm / mm ２ ), and maximum inscribed circle radius (mm). The nonwoven fabric laminate sample to be measured was subjected to the following (a1) and (a2) processes: (a1): A nonwoven fabric laminate sample to be measured was prepared. The prepared sample was scanned using a scanner at a resolution of 6,400 dpi (3 x 4 inches). A 2D image scanner (manufactured by EPSON) was used as the scanner. (a2): From the scanned image obtained in (a1), an image of 16,000 square pixels was cut out, and the image was binarized by assigning black pixels to embossed areas and white pixels to non-embossed areas. The binarization threshold was automatically set using Otsu's binarization method.

[0120] Next, the image was processed using image analysis software, and the welding area ratio (%) and embossed boundary length per unit area (mm / mm ２ ) and the maximum inscribed circle radius [mm] were calculated.

[0121] <5-1: Welded Area Ratio (%)> In the obtained binarized image, the ratio (%) of black pixels to the total number of black pixels and white pixels was calculated.

[0122] <5-2: Embossed boundary length per unit area (mm / mm ２)> In the obtained binarized image, the contour portion is extracted by image analysis so as to surround the black pixels. The sum of the lengths (mm) of the contours of the embossed portion in the analysis region is calculated as the area (mm) of the analysis region. ２ ) and the value obtained by dividing by (mm / mm ２ ) was calculated.

[0123] <5-3: Maximum inscribed circle radius [mm]> The distance from a white pixel located on the black-white boundary to the nearest black pixel was calculated for all white pixels. The position of the white pixel with the maximum value was set as the center of the virtual inscribed circle, and the maximum inscribed circle radius was calculated as the distance from the white pixel to the nearest black pixel.

[0124] [Example 1] A nonwoven fabric laminate having a laminate structure (shown as "SMS" in Table 1) consisting of a spunbond nonwoven fabric layer, a meltblown nonwoven fabric layer, and a spunbond nonwoven fabric layer in this order was produced as follows. The configuration of the obtained nonwoven fabric laminate is as shown in Table 1.

[0125] (First Layer: Spunbond Nonwoven Fabric Layer) The first layer was produced by melt-spinning the following Component I by a spunbond method, and depositing a nonwoven web formed from the fibers on a moving collecting surface. Component I: propylene homopolymer (hPP) with a melting point of 162°C and an MFR of 60 g / 10 min (measured in accordance with ASTM D1238 at a temperature of 230°C and a load of 2160 g; the same applies hereinafter unless otherwise specified).

[0126] (Second Layer: Meltblown Nonwoven Fabric Layer) The following component II was supplied to a die of a meltblown nonwoven fabric manufacturing apparatus, and extruded from the heated die using a meltblowing nozzle together with high-temperature, high-velocity air blown from both sides of the nozzle, to deposit a nonwoven web formed from fibers on the first layer, thereby producing a second layer. Component II: propylene homopolymer (hPP) with a melting point of 159°C and an MFR of 850 g / 10 min

[0127] (Third Layer: Spunbond Nonwoven Fabric Layer) Using the above-mentioned component I, melt spinning was carried out by the spunbond method, and a nonwoven web formed from the fibers was deposited on the second layer to form a third layer, thereby producing a nonwoven web with a laminated structure.

[0128] Next, the laminated nonwoven web was heat-fused using the following embossing roll under the following embossing conditions to produce a nonwoven fabric laminate. The produced nonwoven fabric laminate was used to carry out the evaluations shown in Table 1. The results are shown in Table 1. -Embossing roll- Embossed area ratio: 20.2% Embossed pattern: Embossed pattern shown in Figure 1A -Embossing conditions- Embossing temperature: 115°C Embossing line pressure: 1.0 kgf / cm Embossing speed: 5.0 m / min

[0129] [Experimental Examples 2 to 4, Comparative Examples 1 to 4] Nonwoven fabric laminates were produced in the same manner as in Example 1, except that the embossing roll used in Example 1 was replaced with one of the embossing rolls having embossed patterns shown in Figures 4B to 4H. The produced nonwoven fabric laminates were used to carry out the various evaluations shown in Table 1. The results are shown in Table 1.

[0130] The nonwoven fabric laminates produced in Examples 1 to 4 and Comparative Examples 1 to 4 each had a continuous embossed pattern corresponding to the embossed patterns shown in Figures 1A to 4H. In Figures 1A to 4H, the areas filled in black correspond to the embossed portions of the nonwoven fabric laminate.

[0131]

[0132] As shown in Table 1, the nonwoven fabric laminates of Examples 1 to 4 all had excellent tensile strength and water pressure resistance. The nonwoven fabric laminates of Examples 1 to 4 also had excellent breathability.

[0133] <Fluffing test> A fluffing test was conducted using the nonwoven fabric laminates of Examples 2 and 3. The fluffing test was conducted by rubbing the surface (embossed surface) of the nonwoven fabric laminate a predetermined number of times with a friction probe, and then visually observing whether fluffing had occurred. Details of the test conditions and the test results are shown in Table 2.

[0134]

[0135] As shown in Table 2, the nonwoven fabric laminate of Example 2 showed good results in the fluffing test.

[0136] X: Maximum inscribed circle radius 10: Non-embossed section 12: Embossed section 14: Virtual circle 100: Meltblown nonwoven fabric manufacturing apparatus 110: Spinning section

[0137] The disclosure of Japanese Patent Application No. 2023-223051, filed on December 28, 2023, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A nonwoven fabric laminate comprising a meltblown nonwoven fabric layer containing a meltblown nonwoven fabric and a spunbond nonwoven fabric layer containing a spunbond nonwoven fabric on both sides of the meltblown nonwoven fabric layer, the nonwoven fabric laminate being embossed, having an embossed pattern composed of an embossed portion and a non-embossed portion other than the embossed portion, having a welding area ratio of 16.0% or more, and having an embossed boundary length per unit area of 1.50 mm / mm ２ as follows: a nonwoven fabric laminate.

2. The nonwoven fabric laminate according to claim 1, wherein the average fiber diameter of the fibers contained in the meltblown nonwoven fabric is 1.0 µm or less.

3. The nonwoven fabric laminate according to claim 1, wherein the embossed pattern is composed of a plurality of embossed portions arranged apart from each other and the non-embossed portions surrounding the plurality of embossed portions, and the maximum inscribed circle radius inscribed in the region surrounded by the plurality of embossed portions is 0.40 mm to 2.50 mm.

4. The nonwoven fabric laminate according to claim 1, wherein the shape of the embossed portion is circular or polygonal in top view.

5. The nonwoven fabric laminate according to claim 4, wherein the shape of the embossed portion is elliptical in top view.

6. The nonwoven fabric laminate according to claim 1, wherein the water pressure resistance measured in accordance with Method A specified in JIS L 1096:2010 is 1300 mmw.c or more.

7. The air permeability measured by the measurement method using a frazil air permeability measuring instrument in accordance with JIS L 1096:2010 is 1.5 cm ３ / cm ２ ·s or more, the nonwoven fabric laminate according to claim 1 or claim 2.

8. The nonwoven fabric laminate according to claim 1, wherein the tensile strength measured by the following measurement method is 12 [mm / 25 mm] or more. (Measurement method) Cut the nonwoven fabric laminate in the MD direction into a longitudinal width of 150 mm and a transverse width of 25 mm, and prepare 5 test pieces. Use a tensile tester to measure the 5% strength of the test pieces. However, the chuck distance is 100 mm, the speed is 100 mm / min, the test is repeated 5 times (n = 5), and the average value of the 5 measured values obtained is taken as the evaluation value.

9. The nonwoven fabric laminate according to claim 1, which is used for filtration.

10. A step of melt-spinning a first thermoplastic resin or a first resin composition containing the first thermoplastic resin by the spunbond method, depositing the fibers obtained by the melt-spinning on a moving collection surface to obtain a first spunbond nonwoven fabric layer containing a spunbond nonwoven fabric; a step of using a second thermoplastic resin or a second resin composition containing the second thermoplastic resin, depositing the fibers obtained by the meltblown method on a moving collection surface to obtain a meltblown nonwoven fabric layer containing a meltblown nonwoven fabric; a step of melt-spinning a third thermoplastic resin or a third resin composition containing the third thermoplastic resin by the spunbond method, depositing the fibers obtained by the melt-spinning on a moving collection surface to obtain a second spunbond nonwoven fabric layer containing a spunbond nonwoven fabric; and a step of thermally fusing the first spunbond nonwoven fabric layer, the meltblown nonwoven fabric layer, and the second spunbond nonwoven fabric layer in this order by embossing. A method for manufacturing a nonwoven fabric laminate.

11. In the embossing process in the heat welding step, the welding area ratio is 16.0% or more, and the embossing boundary length per unit area is 1.50 mm / mm ２ The method for manufacturing a nonwoven fabric laminate according to claim 10, wherein an embossed pattern composed of an embossed portion and a non-embossed portion other than the embossed portion is formed, and the embossed pattern is 1.50 mm / mm or less.

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