Air permeable nonwoven fabric laminate and manufacturing method thereof

Abstract

To provide an air permeable nonwoven fabric that has sufficient heat adhesiveness on a whole surface of a heat seal surface, hardly causes fluffing when a heat seal part is peeled off, and has high tear strength.SOLUTION: An air permeable nonwoven fabric comprises: a thermoplastic resin fiber nonwoven fabric layer A in which one or more layers of a layer selected from a spunbonded nonwoven fabric and a melt-blown nonwoven fabric are laminated; and a thermoplastic resin fiber nonwoven fabric layer B of one layer or two or more layers. The thermoplastic resin fiber nonwoven fabric layer B contains low-melting polyester resin, polyester fibers, and polyethylene resin. The air permeable nonwoven fabric has 1000 mN or more of tear strength measured according to JIS P 8116:2000.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a breathable nonwoven fabric laminate which has sufficient thermal adhesion over the entire heat-sealed surface, is less likely to fray when the heat-sealed portion is peeled off, and has high tear strength, and a method for producing the same. [Background technology]

[0002] Breathable nonwoven fabrics have a wide range of applications, including as heat generating elements such as disposable heating pads and medical heating elements, as desiccants, oxygen absorbers, various stabilizers such as freshness preserving agents, as well as packaging materials for insect repellents and fragrances. They are also used as wrapping materials for clothing, miscellaneous goods, toys, etc. Furthermore, breathable nonwoven fabrics are also used as filter media for liquids such as water and gases. Breathable nonwoven fabrics are required to have breathability (barrier properties) suited to their applications, and these are adjusted by adjusting the properties and thickness of the materials used, laminating them with porous films, etc. For example, Patent Document 1 discloses a breathable and moisture-permeable laminate in which a reinforcing material is laminated on one side of a uniaxially stretched porous film. Patent Document 2 discloses a bag made of two layers of porous film, layer A and layer B, which have different melting points, and Patent Document 3 discloses a laminate in which a nonwoven fabric and a porous film are partially bonded with an adhesive, and the breathability and moisture permeability can be easily controlled by using a porous film having a specific median diameter, pore volume, and stress at 10% elongation. When used as wrapping material for clothing, miscellaneous goods, toys, etc., the sealed area may be required to be easy to open. Also, if fuzz occurs at the opening, the nonwoven fabric material may fall off and adhere to the surface of the contents, so this must be prevented. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 6-22959 [Patent Document 2] JP 2011-104993 A [Patent Document 3] JP 2014-83806 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a breathable nonwoven fabric which has sufficient thermal adhesion over the entire heat-sealed surface, is less likely to fray when the heat-sealed portion is peeled off, and has high tear strength. [Means for solving the problem]

[0005] The present invention has the following aspects. <1> A breathable nonwoven fabric laminate comprising a thermoplastic resin fiber nonwoven fabric layer A in which one or more layers selected from a spunbonded nonwoven fabric mainly composed of polyester resin fibers and a meltblown nonwoven fabric mainly composed of polyester resin fibers are laminated, and one or more thermoplastic resin fiber nonwoven fabric layers B, wherein the thermoplastic resin fiber nonwoven fabric layer B contains a low melting point polyester resin, polyester fibers and a polyethylene resin, and the breathable nonwoven fabric laminate has a tear strength of 1000 mN or more as measured in accordance with JIS P 8116:2000.

[0006] <2> The melting point of the low melting point polyester resin is 90 to 150°C, and the melting point of the polyethylene resin is 90 to 140°C. <1> The breathable nonwoven fabric laminate according to claim 1.

[0007] <3> The content of the low melting point polyester resin in the thermoplastic resin fiber nonwoven fabric layer B is 11 to 41 mass %, the content of the polyester fiber is 9 to 34 mass %, and the content of the polyethylene resin is 25 to 80 mass %. <1> or <2> The breathable nonwoven fabric laminate according to claim 1.

[0008] <4> The thermoplastic resin fiber nonwoven fabric layer A has a portion in which a spunbond nonwoven fabric, a meltblown nonwoven fabric, and a spunbond nonwoven fabric are laminated in this order at least. <1> ~ <3> 13. The breathable nonwoven fabric laminate according to any one of claims 1 to 12.

[0009] <5> When the surfaces of the breathable nonwoven fabric used for heat sealing are overlapped and heat sealed, the adhesive strength when peeled at 180° at a peel speed of 300 mm / min according to JIS K 6854-3:1999 is 0.5 N / 15 mm or more. <1> ~ <4> 13. The breathable nonwoven fabric laminate according to any one of claims 1 to 12.

[0010] <6> The breathable nonwoven fabric has a basis weight of 30 g / m 2 More than 150g / m 2 Is less than or equal to <1> ~ <5> 13. The breathable nonwoven fabric laminate according to any one of claims 1 to 12.

[0011] <7> <1> ~ <6> 2. A method for producing the breathable nonwoven fabric laminate according to any one of the above, comprising the following steps 1 to 3 in this order: Step 1: preparing a thermoplastic resin fiber nonwoven fabric a as a thermoplastic resin fiber nonwoven fabric layer A and a thermoplastic resin fiber nonwoven fabric b as a thermoplastic resin fiber nonwoven fabric layer B. Step 2: A step of laminating a thermoplastic resin fiber nonwoven fabric a having a three or more layer configuration and one or two or more layers of a thermoplastic resin fiber nonwoven fabric b. Step 3: A step of thermally fusing the thermoplastic resin fiber nonwoven fabric a and the thermoplastic resin fiber nonwoven fabric b laminated in step 2 to obtain a breathable nonwoven fabric laminate. Effect of the Invention

[0012] The breathable nonwoven fabric of the present invention has sufficient thermal adhesion over the entire heat-sealed surface, is less likely to fray when the heat-sealed portion is peeled off, and has high tear strength, making it excellent for use as various breathable packaging materials and filter media. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view of one embodiment of a breathable nonwoven fabric. [Diagram 2] FIG. 1 is a cross-sectional view of one embodiment of a breathable nonwoven fabric. [Diagram 3] FIG. 2 is a cross-sectional view of another embodiment of a breathable nonwoven fabric. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] In the present invention, the term "sheet" is a general term for thin sheets such as sheets, films, nonwoven fabrics, and laminates thereof. "Oken air permeability" is a value measured in accordance with JIS P 8117:2009. "Basis weight" is a value measured in accordance with JIS P 8124:2011. The "melting point" is the melting peak temperature measured in accordance with JIS K 7121:1987. "Tear strength" is a measurement of the sheet measured in accordance with JIS P 8116:2000.

[0015] Hereinafter, one embodiment of the breathable nonwoven fabric will be described with reference to FIG. [Breathable nonwoven laminate] The breathable packaging body (11) is a packaging body in which breathable nonwoven fabric laminates (21) are bonded to each other, or to a breathable nonwoven fabric laminate and a different sheet, molded body, etc., or the breathable nonwoven fabric laminate (21) and an adherend (31) are included. The breathable nonwoven fabric laminate (21) comprises a thermoplastic resin fiber nonwoven fabric layer A (22) in which one or more layers selected from a spunbond nonwoven fabric and a meltblown nonwoven fabric are laminated, and one or more thermoplastic resin fiber nonwoven fabric layers B (23). As described later, the breathable nonwoven fabric laminate (21) is preferably obtained by laminating a thermoplastic resin fiber nonwoven fabric layer A (22) and a thermoplastic resin fiber nonwoven fabric layer B (23) and heat fusing them together.

[0016] (tear strength) The breathable nonwoven fabric laminate (21) of the present invention has a tear strength of 1000 mN or more as measured in accordance with JIS P 8116:2012. The tear strength is measured in any direction along the surface of the breathable nonwoven fabric laminate, but it is preferably 1000 mN or more when measured in any direction along the surface of the breathable nonwoven fabric laminate. By setting the tear strength to 1000 mN or more, accidental breakage during use can be prevented when the material is used as various breathable packaging materials or filter media. The tear strength is more preferably 1500 mN or more, even more preferably 2000 mN or more, and even more preferably 3000 mN or more.

[0017] (Ouken style air permeability) The Oken air permeability of the breathable nonwoven fabric laminate (21), measured in accordance with JIS P 8121-2:2012, can be adjusted according to the required breathability by changing the conditions (temperature and pressure) for heat-sealing the thermoplastic resin fiber nonwoven fabric layer A (22) and the thermoplastic resin fiber layer B (23). The adjustable range is generally 0 to 100,000 seconds.

[0018] (Basic weight) The basis weight of the breathable nonwoven fabric laminate (21) of the present invention is preferably 30 g / m from the viewpoints of ease of production, appropriate heat seal strength and tear strength. 2 More preferably, 50 g / m 2 More preferably, 70 g / m 2 That's all. The basis weight of the breathable nonwoven fabric laminate of the present invention is preferably 150 g / m from the viewpoint of flexibility as a packaging material. 2 Less than 120 g / m 2 More preferably, 100 g / m or less 2 The following is the result.

[0019] <Thermoplastic resin fiber nonwoven fabric layer A> The thermoplastic resin fiber nonwoven fabric layer A (22) of this embodiment includes a spunbond nonwoven fabric layer and a meltblown nonwoven fabric layer each composed of continuous long fibers, and preferably further has a portion in which at least a spunbond nonwoven fabric layer, a meltblown nonwoven fabric layer, and a spunbond nonwoven fabric layer are laminated in this order. The continuous long fibers constituting the thermoplastic resin fiber nonwoven fabric layer A (22) are preferably polyester fibers.

[0020] The thermoplastic resin fiber nonwoven fabric A (22) may contain an airlaid nonwoven fabric layer, a wet-laid nonwoven fabric layer, or an electrospun nonwoven fabric layer in addition to a spunbond nonwoven fabric layer and a meltblown nonwoven fabric layer. The average fiber diameter of the polyester resin fibers in the spunbond nonwoven fabric constituting the thermoplastic resin fiber nonwoven fabric layer A (22) is preferably adjusted to within the range of 5 to 30 μm. The average fiber diameter of the polyester resin fibers in the melt-blown nonwoven fabric constituting the thermoplastic resin fiber nonwoven fabric layer A (22) is preferably adjusted to within the range of 0.5 to 10 μm. The thermoplastic resin fibers constituting the thermoplastic resin fiber nonwoven fabric a do not completely melt during the heat fusion process described below, and the fiber shape remains in the thermoplastic resin fiber nonwoven fabric layer A in the breathable nonwoven fabric laminate (21).

[0021] Furthermore, within the scope of the present invention, it is possible to use in combination in the thermoplastic resin fiber nonwoven fabric layer A natural pulp fibers, regenerated fibers, and other chemical fibers.

[0022] The basis weight of the thermoplastic resin fiber nonwoven fabric layer A (22) is not particularly limited, but is, for example, 5 g / m 2 More than 100g / m 2 From the viewpoint of obtaining sufficient thermal adhesiveness, breathability, and tear strength, it is preferable to adjust the thickness within a range of about 10 g / m 2 More than 80g / m 2 Less than 20 g / m 2 More than 50g / m 2 The following is the result. When the breathable nonwoven fabric has two or more thermoplastic resin fiber nonwoven fabric layers A (22), the above-mentioned preferable range of the basis weight is the preferable range of the basis weight of each layer. As the thermoplastic resin fiber nonwoven fabric layer A, for example, the Precise (registered trademark) series manufactured by Asahi Kasei Corporation (a three-layer structure of a polyester resin spunbond fiber layer / a polyester resin meltblown fiber layer / a polyester spunbond fiber layer) is available.

[0023] <Thermoplastic resin fiber nonwoven fabric layer B> The thermoplastic resin fiber nonwoven fabric layer B (23) is formed into a sheet by any of various known methods from one or more types of thermoplastic resin fibers. The thermoplastic resin fiber nonwoven fabric layer B contains a low melting point polyester resin, polyester fibers, and a polyethylene resin.

[0024] The content ratio of the low melting point polyester resin to the total mass of the thermoplastic resin fiber nonwoven fabric layer B (23) is preferably 11 to 41 mass %. By making the content ratio of the low melting point polyester resin in the thermoplastic resin fiber nonwoven fabric layer (23) B 11 mass % or more, fluffing of the heat sealed portion peeled off when the package is opened can be further suppressed. The melting point of the low-melting point polyester resin is appropriately selected from the range of 90 to 150°C depending on the polyester fibers to be combined and the heating conditions when the thermoplastic resin fiber nonwoven fabric layer A (22) and the thermoplastic resin fiber nonwoven fabric layer B are heat-fused, and is preferably 100 to 120°C.

[0025] The content ratio of the polyester fiber to the total mass of the thermoplastic resin fiber nonwoven fabric layer B (23) is preferably 9 to 34% by mass. By making the content ratio of the polyester fiber in the thermoplastic resin fiber nonwoven fabric layer B (23) 9% by mass or more, it becomes easy to adjust the air permeability in the process of heat-sealing the thermoplastic resin fiber nonwoven fabric layer A (22) and the thermoplastic resin fiber nonwoven fabric layer B (23). In addition, the melting point of the polyester fiber is preferably 150°C or more, more preferably 180°C or more, even more preferably 200°C or more, and even more preferably 240°C or more. By providing a difference between the melting point of the low melting point polyester fiber and the melting point of the polyester fiber, it becomes easy to adjust the air permeability. The polyester fiber component is, for example, polyethylene terephthalate.

[0026] The content of the polyethylene resin is preferably 25% by mass or more and 80% by mass or less, more preferably 30% by mass or more, and further preferably 40% by mass or more, based on the total mass of the thermoplastic resin fiber nonwoven fabric layer B (23). By making the content of the polyethylene resin in the thermoplastic resin fiber nonwoven fabric layer B (23) 25% by mass or more, good heat seal peel strength can be obtained. The melting point of the polyethylene resin is appropriately selected from the range of 90 to 140°C depending on other materials used in the breathable nonwoven fabric laminate and the heating conditions when the thermoplastic resin fiber nonwoven fabric layer A and the thermoplastic resin fiber nonwoven fabric layer B are heat-fused, and is preferably 125 to 145°C.

[0027] In the thermoplastic resin fiber nonwoven fabric layer B (23), the polyester fibers are referred to as "polyester fibers" since it is preferable that they are in a fibrous form, while the low-melting point polyester and polyethylene that constitute the thermoplastic resin fibers are at least partially melted, and therefore are referred to as "low-melting point polyester resin" and "polyethylene resin", respectively.

[0028] In addition, in the thermoplastic resin fiber nonwoven fabric layer B (23), natural pulp may be used in combination, although it is not thermoplastic, from the viewpoint of reducing the environmental load and improving the strength. Examples of natural pulp include wood pulp (softwood pulp, hardwood pulp, etc.) and non-wood pulp (hemp pulp, cotton pulp, straw pulp, etc.).

[0029] The fiber diameter of the fibers used in the thermoplastic resin fiber nonwoven fabric layer B (23) is not particularly limited, but is, for example, from 1 μm to 60 μm, and preferably from 1 μm to 40 μm.

[0030] The basis weight of the thermoplastic resin fiber nonwoven fabric layer B (23) is not particularly limited, but is, for example, 5 g / m 2 More than 100g / m2 From the viewpoint of obtaining sufficient thermal adhesiveness, breathability, and tear strength, it is preferably 10 g / m 2 More than 80g / m 2 Less than 15g / m 2 More than 60g / m 2 The following is the result. When the breathable nonwoven fabric has two or more thermoplastic resin fiber nonwoven fabric layers B (23), the above-mentioned preferable range of the basis weight is the preferable range of the basis weight of each layer.

[0031] The thermoplastic resin fiber nonwoven fabric layer B (23) may be a single layer or a multi-layer structure of two or more layers. The thermoplastic resin fiber nonwoven fabric layer B (23) and the thermoplastic resin fiber nonwoven fabric layer A (22) may be laminated in any order.

[0032] The thermoplastic resin fiber nonwoven fabric layer B (23) can be produced by mixing a low melting point polyester resin, polyester fiber, and polyethylene resin, using various known nonwoven fabric production methods. Among them, the wet papermaking method is preferred because it is easy to obtain good texture even at low basis weights and pinholes are less likely to occur in breathable nonwoven fabrics.

[0033] Examples of the wet papermaking method include methods using a Fourdrinier paper machine, a short wire paper machine, a cylinder paper machine, an inclined paper machine, etc. Among them, the cylinder paper machine and the inclined paper machine are preferred because they can use materials with relatively long fiber lengths, and the inclined paper machine is more preferred.

[0034] To the raw material slurry, various dispersants, surfactants, thickeners and other internal additives may be added for the purpose of adjusting the formation.

[0035] The method for drying the thermoplastic resin fiber nonwoven fabric after wet papermaking is not particularly limited, and a multi-cylinder dryer, Yankee dryer, hot air dryer, infrared dryer, etc. can be used. When a multi-cylinder dryer or Yankee dryer is used, it is preferable to set the drying temperature below the melting point of the thermoplastic resin fiber, or to coat the surface of the multi-cylinder dryer or Yankee dryer with a fluororesin in order to prevent surface contamination due to adhesion of the thermoplastic resin.

[0036] The polyethylene resin is mixed with other materials in the form of particles or fibers. When preparing a slurry for a wet papermaking process, the polyethylene resin is preferably used in the form of fibers, and more preferably in the form of hyperbranched fibers. When using a slurry using a polyethylene resin in the form of hyperbranched fibers, a breathable nonwoven fabric laminate that is uniform and has better heat sealability can be obtained. Examples of the hyperbranched fibers include the SWP (registered trademark) series manufactured by Mitsui Chemicals, Inc.

[0037] The low melting point polyester resin may be mixed with other materials in the form of particles, but is preferably mixed in the form of fibers. It is preferable to use a composite fiber of the polyester fiber and the low melting point polyester resin as a manufacturing material for the thermoplastic resin fiber nonwoven fabric layer B, since it is highly effective in suppressing fluffing at the heat seal portion peeled off when the package is opened. Examples of the composite fiber include a side-by-side composite fiber of a fiber made of the low melting point polyester resin and the polyester fiber, and a fiber in which the polyester fiber is coated with the low melting point polyester resin.

[0038] In the composite fiber, the ratio of the low melting point polyester resin component / polyester fiber is preferably 20 / 80 or more and 80 / 20 or less, more preferably 30 / 70 or more and 70 / 30 or less, and further preferably 40 / 60 or more and 60 / 40 or less. Examples of the composite fiber include Tepyrus (registered trademark) series manufactured by Teijin Frontier Co., Ltd., and PET-based binder fiber manufactured by Kuraray Co., Ltd.

[0039] The fibrous polyethylene resin, the fibrous low-melting point polyester resin, and the low-melting point polyester resin in the composite fiber are at least partially melted in the process of heat-sealing the thermoplastic resin fiber nonwoven fabric layer A and the thermoplastic resin fiber nonwoven fabric layer B, and contribute to improving the heat seal peel strength of the breathable nonwoven fabric laminate and suppressing pilling when the package is opened.

[0040] [Method of manufacturing breathable nonwoven fabric laminate] The method for producing the breathable nonwoven fabric laminate of the present embodiment preferably includes the following steps 1 to 3 in this order. Step 1: preparing a thermoplastic resin fiber nonwoven fabric a and a thermoplastic resin fiber nonwoven fabric b. Step 2: A step of laminating a thermoplastic resin fiber nonwoven fabric a and a thermoplastic resin fiber nonwoven fabric b. Step 3: A step of thermally fusing the thermoplastic resin fiber nonwoven fabric a and the thermoplastic resin fiber nonwoven fabric b.

[0041] <Process 1> Step 1 is a step of preparing a thermoplastic resin fiber nonwoven fabric a as the thermoplastic resin fiber nonwoven fabric layer A and a thermoplastic resin fiber nonwoven fabric b as the thermoplastic resin fiber nonwoven fabric layer B. Thermoplastic resin fiber nonwoven fabric a will become thermoplastic resin fiber nonwoven fabric layer A of the completed breathable nonwoven fabric laminate, and thermoplastic resin fiber nonwoven fabric b will become thermoplastic resin fiber nonwoven fabric layer B of the completed breathable nonwoven fabric laminate. The thermoplastic resin fiber nonwoven fabric a can be produced by the spunbonding method or the meltblowing method. When the thermoplastic resin fiber nonwoven fabric a is made of two or more layers, two or more nonwoven fabrics may be overlapped and heat-sealed. The thermoplastic resin fiber nonwoven fabric layer b can be produced by the method exemplified in the description of the thermoplastic resin fiber nonwoven fabric layer B above.

[0042] <Process 2> Step 2 is a step of laminating one or more layers of a thermoplastic resin fiber nonwoven fabric a and one or more layers of a thermoplastic resin fiber nonwoven fabric b. The method of laminating the thermoplastic resin fiber nonwoven fabric a and the thermoplastic resin fiber nonwoven fabric b is not limited to a specific order, except that the outermost surface of either the front or back surface is the thermoplastic resin fiber nonwoven fabric b from the viewpoint of heat sealability as a packaging material, and each layer may be a single layer or may be a multilayer of two or more layers.

[0043] Among these, in order to reduce curling after thermal lamination, it is preferable that the front and back layers are symmetrical or in a similar order from the center layer. Therefore, a three-layer structure is formed by laminating thermoplastic resin fiber nonwoven fabric b / thermoplastic resin fiber nonwoven fabric a / thermoplastic resin fiber nonwoven fabric b in this order, and a five-layer structure is formed by laminating b / a / b / a / b in this order, and b / (a / b) n It is preferable that the laminated structure be a / a / b (n is an integer of 0 or more). Of these, it is preferable that the laminated structure be a three-layer structure of b / a / b or a five-layer structure of b / a / b / a / b, and from the viewpoint of ease of production, it is more preferable that the laminated structure be a three-layer structure of b / a / b.

[0044] The multiple thermoplastic resin fiber nonwoven fabrics a that make up the breathable nonwoven fabric laminate may all be the same or different, and the same applies to the multiple thermoplastic resin fiber nonwoven fabrics b that make up the breathable nonwoven fabric laminate.

[0045] <Process 3> Step 3 is a step of heat-sealing the laminate obtained in step 2. In step 3, the thermoplastic resin fiber nonwoven fabric a and the thermoplastic resin fiber nonwoven fabric b constituting the laminate are heat-sealed (heat laminated). The heat fusion step is carried out, for example, by passing the laminate obtained in step 2 between two heated rolls.

[0046] The temperature of the heating roll is adjusted within a range of not less than the melting point of the thermoplastic resin fiber with the lowest melting point used in the thermoplastic resin fiber nonwoven fabric b, and not more than the melting point of the thermoplastic resin fiber with the lowest melting point used in the thermoplastic resin fiber nonwoven fabric a +30°C.

[0047] By setting the temperature of the heating roll to not lower than the melting point of the thermoplastic resin fiber with the lowest melting point among the thermoplastic resin fibers used in the thermoplastic resin fiber nonwoven fabric b, the effect of suppressing nap formation on the surface of the thermoplastic resin fiber nonwoven fabric b can be sufficiently obtained, and heat seal strength can also be obtained. In addition, by setting the temperature of the heating roll to not more than the melting point of the thermoplastic resin fiber with the lowest melting point among the thermoplastic resin fibers used in the thermoplastic resin fiber nonwoven fabric a +30°C, the fiber shape is maintained in the thermoplastic resin fiber nonwoven fabric layer a even after heat fusion, and sufficient tear strength can be obtained, which is preferable.

[0048] It is also preferable to coat the surface of the heating roll with a fluororesin in order to prevent surface contamination due to adhesion of a thermoplastic resin. Alternatively, a silicone rubber roll can be used.

[0049] The surface temperatures of the upper and lower heating rolls may be the same or different. Also, heat fusion may be performed with one nip or with two or more nips. In the case of two or more nips, the process may be performed in one pass or in two or more passes. When the laminate obtained in step 2 has three or more layers, all layers may be heat-sealed simultaneously, or a portion of the layers may be heat-sealed first, and then another layer may be added and heat-sealed. During heat fusion, a step of providing residual heat, such as by heating using a preheater, to the thermoplastic resin fiber nonwoven fabric a and / or the thermoplastic resin fiber nonwoven fabric b before contacting them with a heating roll can be added before pressing. Other known techniques can also be applied.

[0050] [Effects] The breathable nonwoven fabric laminate (21) of the present invention is obtained by heat fusing (thermal laminating) a thermoplastic resin fiber nonwoven fabric layer A and a thermoplastic resin fiber nonwoven fabric layer B, and has sufficient heat adhesion over the entire heat-sealed surface, is less likely to fray when the heat-sealed portion is peeled off, and has high tear strength, making it excellent as a breathable packaging material or filter medium.

[0051] [Application] The breathable nonwoven fabric laminate (21) of the present invention is used as a packaging material for, for example, heat generating elements such as disposable warmers and medical heating elements, various stabilizers such as desiccants, oxygen absorbers, and freshness preserving agents, insect repellents, and aromatics. It is also used as a wrapping material for clothing, miscellaneous goods, toys, and the like. It can also be applied to filter media. A breathable package in which the breathable nonwoven fabric (21) and the adherend are heat-pressed together can be formed by overlapping and heat-pressing parts of the breathable nonwoven fabric laminate (21) with each other or parts of the breathable nonwoven fabric laminate (21) and parts of the adherend such as wrapping paper, laminated paper, film, and molded containers so that a space is formed inside.

[0052] Examples of the film include films or perforated films made of polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polyvinyl chloride, polyvinylidene chloride, polystyrene, ethylene-vinyl acetate copolymer resins, ethylene-acrylic copolymer resins, or laminates thereof. The breathable nonwoven fabric laminate (21) of the present invention can be fixed to a housing in which a sheet-like filter is to be placed by thermal bonding to the housing at a part such as an end portion, and the air permeability can be adjusted to a desired value in the manufacturing process of the breathable nonwoven fabric laminate, making it also useful as a filter medium.

[0053] The breathable nonwoven fabric laminate (21) may be printed on either the front or back surface, or on the outermost surface of both surfaces.

[0054] In a package containing breathable nonwoven fabric laminates (21) together or with other adherends, the peel strength when heat-sealed portions of the breathable nonwoven fabric laminates (21) or other adherends are peeled at 180° at a peel speed of 300 mm / min is not particularly limited, but is preferably 0.5 N / 15 mm or more, more preferably 3.0 N / 15 mm or more, even more preferably 6.0 N / 15 mm or more, and particularly preferably 10 N / 15 mm or more. A peel strength within the above range is preferable because it can prevent breakage accidents. When opening the heat-sealed portion of the breathable packaging material using the breathable nonwoven fabric of the present invention, it is preferable that fuzzing does not easily occur. The heat seal peel strength and the degree of fuzzing are measured and evaluated by the methods described in the examples.

[0055] The heat seal peel strength can be adjusted within a desired range by setting the basis weight of the thermoplastic resin fiber nonwoven fabric layer B (23) constituting the heat seal surface, the polyethylene resin content in the thermoplastic resin fiber nonwoven fabric layer B (23), the heat fusion conditions in the heat fusion step of the laminate during the production of the breathable nonwoven fabric, and the heat fusion conditions with the adherend, all within appropriate ranges. EXAMPLES

[0056] The present invention will be specifically described below with reference to examples. Note that the present invention is not limited to these examples. Note that, unless otherwise specified, % is mass % and parts is mass parts.

[0057] [Example 1] <Production of thermoplastic resin fiber nonwoven fabric b> A raw material slurry was obtained by mixing and stirring 70 parts by mass of polyethylene hyperbranched fiber (product name: SWP (registered trademark) E400, melting point 135°C, average fiber length 0.9 mm, fiber diameter approximately 1 to 30 μm, manufactured by Mitsui Chemicals, Inc.) and 30 parts by mass of core-sheath structure polyester fiber (product name: Tepyrus (registered trademark) TJ04CN, fineness 1.1 dtex, fiber length 5 mm, fiber diameter approximately 10 μm, sheath melting point 110°C, core (polyethylene terephthalate) melting point 260°C, sheath / core mass ratio = 55 / 45, manufactured by Teijin Frontier Co., Ltd.). The raw material slurry was made into paper using a wet inclined papermaking machine, and dried in a Yankee dryer with a surface temperature of 105°C to produce a paper with a basis weight of 35 g / m 2 Thus, a thermoplastic resin fiber nonwoven fabric layer B was obtained.

[0058] <Production of breathable nonwoven fabric laminate> The thermoplastic resin fiber nonwoven fabric b obtained above and the polyester resin thermoplastic resin fiber nonwoven fabric a (three-layer structure of spunbond / meltblown / spunbond, basis weight 20 g / m 2 A thermal lamination process was carried out using a thermal laminator having a heating roll with a fluorine-coated surface, with the roll temperatures of the upper and lower rolls set to 170°C and the line speed set to 4.7 m / min, to obtain a sheet with a basis weight of 90 g / m. 2 Thus, the breathable nonwoven fabric laminate of Example 1 was obtained.

[0059] [Example 2] The breathable nonwoven fabric laminate of Example 2 was obtained in the same manner as in Example 1, except that in the production of the breathable nonwoven fabric laminate of Example 1, the heat lamination treatment conditions were a roll temperature of 150°C.

[0060] [Example 3] In the production of the breathable nonwoven fabric of Example 1, the polyester resin thermoplastic resin fiber nonwoven fabric a was prepared as a three-layer structure of spunbond nonwoven fabric / meltblown nonwoven fabric / spunbond nonwoven fabric, with a basis weight of 30 g / m 2 A breathable nonwoven fabric laminate of Example 3 was obtained in the same manner as in Example 1, except that the product name: Precise (registered trademark) AAS030, manufactured by Asahi Kasei Corporation, was used instead.

[0061] [Example 4] The breathable nonwoven fabric laminate of Example 4 was obtained in the same manner as in Example 3, except that in the production of the breathable nonwoven fabric of Example 3, the heat lamination conditions were a roll temperature of 150°C.

[0062] [Comparative Example 1] In the production of the breathable nonwoven fabric of Example 1, a wet-laid polyester nonwoven fabric (basis weight 20 g / m) was used as the polyester resin thermoplastic resin fiber nonwoven fabric a. 2 A breathable nonwoven fabric laminate was obtained in the same manner as in Example 1, except that a polyurethane foam was used instead of the polyurethane foam.

[0063] [Comparative Example 2] A breathable nonwoven fabric laminate was obtained in the same manner as in Example 1, except that in the production of the thermoplastic resin fiber nonwoven fabric b of Example 1, 30 parts by mass of a single cross section polyester fiber (trade name: Tepyrus (registered trademark) TK08PN, fiber diameter approximately 10 μm, fiber length approximately 3 mm, melting point 247° C., manufactured by Teijin Frontier Co., Ltd.) was used instead of 30 parts by mass of the core-sheath polyester fiber (trade name: Tepyrus (registered trademark) TJ04CN).

[0064] [Comparative Example 3] In producing the thermoplastic resin fiber nonwoven fabric b of Example 1, a breathable nonwoven fabric laminate was obtained in the same manner as in Example 1, except that no polyethylene hyperbranched fiber was used, and 100 parts by mass of a core-sheath structure polyester fiber (product name: Tepyrus (registered trademark) TJ04CN, fineness 1.1 dtex, fiber length 5 mm, fiber diameter approximately 10 μm, sheath melting point 110° C., core (polyethylene terephthalate) melting point 260° C., sheath / core mass ratio = 55 / 45, manufactured by Teijin Frontier Co., Ltd.) was used instead.

[0065] [Comparative Example 4] <Preparation of paper substrate> Hardwood bleached kraft pulp (LBKP) was beaten with a double disc refiner (DDR) to a Canadian standard freeness (freeness) of 390 mL as described in JIS P 8121-2:2012 to obtain a pulp slurry. The pulp slurry was added with 0.5 parts by mass of aluminum sulfate on an absolute dry basis, 0.05 parts by mass of an alkenyl succinic anhydride sizing agent dispersion previously dispersed in cationic starch as the solid content of the alkenyl succinic anhydride sizing agent, 0.7 parts by mass of an amphoteric polyacrylamide resin paper strength enhancer (PAM) (trade name: Polystron OFT-3, manufactured by Arakawa Chemical Industries Co., Ltd., weight average molecular weight 3 million), and 0.4 parts by mass of an epichloro resin wet paper strength enhancer (trade name: WS4024, manufactured by Seiko PMC Co., Ltd.) as internal chemicals per 100 parts by mass of pulp to obtain a papermaking raw material. The papermaking raw material was made into paper on a fourdrinier paper machine to obtain a breathable base material. The resulting breathable substrate had a basis weight of 60 g / m 2 It was. The "alkenyl succinic anhydride sizing agent dispersion previously dispersed in cationic starch" was prepared as follows: A 2% by mass aqueous solution of cationic starch (Pillar 3YK, manufactured by Pillar Starch Co., Ltd.) was prepared, and an alkenyl succinic anhydride sizing agent (Fibran 81K, manufactured by Arakawa Chemical Industries Co., Ltd.) was added thereto so that the solid content concentration was 4 / 1 (cationic starch (Pillar 3YK, manufactured by Pillar Starch Co., Ltd.) / alkenyl succinic anhydride sizing agent). The aqueous solution prepared as described above was added in an amount of 0.05 parts by mass as the solid content of alkenyl succinic anhydride.

[0066] <Preparation of paint for thermal adhesive layer> 138 parts by mass of EVA dispersion (Chemipearl V200, manufactured by Mitsui Chemicals, Inc., EVA particle average particle size 7 μm, minimum film formation temperature 85°C, solid content concentration 40%), PE dispersion (Chemipearl W400, manufactured by Mitsui Chemicals, Inc., PE particle average particle size 4 μm, solid content concentration 40%, PE density 920 kg / m 3 A coating material for thermal adhesive layers with a solids concentration of 25% was obtained by mixing and stirring 90 parts by mass of a polyurethane foam (softening point 110°C), 18 parts by mass of a reinforced rosin emulsion (Sizepine N775, manufactured by Arakawa Chemical Industries, Ltd., softening point less than 100°C, solids concentration 50%), and 154 parts by mass of dilution water.

[0067] <Production of heat seal paper> The above-mentioned coating material for thermal adhesive layer was applied to one surface of the above-obtained breathable substrate using a bar coater, and then dried in a blower dryer at 100°C for 1 minute to form a thermal adhesive layer. Here, the coating amount of the coating material for thermal adhesive layer after drying was 2.5 g / m 2 In this way, a heat seal paper of Comparative Example 4 was obtained.

[0068] [Measurement and Evaluation] The breathable nonwoven fabrics obtained in Examples 1 to 4 and Comparative Examples 1 to 3 and the heat seal paper obtained in Comparative Example 4 were evaluated as follows.

[0069] <Oken air permeability measurement> The Oken air permeability was measured in accordance with JIS P 8117:2009.

[0070] <Measurement of tear strength> According to JIS P 8116:2000, tear strength was measured in the direction parallel to the flow of the web during production and in the direction perpendicular to the flow, and the smaller of the measured values ​​was regarded as the tear strength.

[0071] <Measurement of heat seal adhesive strength (HS adhesive strength) between breathable nonwoven fabrics> Two pieces of each breathable nonwoven fabric obtained in the Examples and Comparative Examples were stacked and heat-pressed using a heat press tester under heat-pressing conditions of 170°C, 0.2 MPa, and 1.0 second to prepare HS adhesive strength test pieces. The obtained HS adhesive strength test piece was cut to a width of 15 mm to prepare a sample for adhesive strength measurement. The adhesive strength (N / 15 mm) of the obtained adhesive strength measurement sample was measured in accordance with JIS K 6854-3:1999 by chucking the ends of the upper and lower breathable nonwoven fabric and peeling them at a peeling speed of 300 mm / min using a tensile tester (model: Tensilon RTC-1250A, manufactured by Orientec Co., Ltd.).

[0072] <Peeling fluff at heat seal adhesive area> In the above measurement of heat seal adhesive strength between breathable nonwoven fabrics, the temperature of the heat press tester was changed to 150°C to measure the seal strength, and the seal portion was visually observed to evaluate the surface fuzziness. (Evaluation Criteria) ○: No fluffing is observed on the surface. ×: A lot of fuzzing is observed on the surface.

[0073] The breathable nonwoven fabrics of Examples 1 to 4 and Comparative Examples 1 to 3 and the heat seal paper of Comparative Example 4 were evaluated for Oken air permeability, tear strength, adhesive strength of the heat seal portion, and fuzzing. The results are shown in Table 1.

[0074] [Table 1]

[0075] The breathable nonwoven fabric laminates of Examples 1 to 4 have a tear strength of 1000 mN or more, and are considered to have a strength that is unlikely to cause breakage accidents when used in various breathable packaging materials. In addition, the HS strength at a sealing temperature of 170°C also exceeds 10 N / 15 mm, and it is considered that the heat-sealed portion is unlikely to open accidentally even if it is used as a packaging material with three-sided seal or pillow packaging form, for example. The breathable nonwoven fabrics of all Examples have a seal strength of 3.5 N / 15 mm or more when sealed at a sealing temperature of 150°C, which is sufficient seal strength, and no fraying was observed when the sealed portion was peeled off. The air permeability could be adjusted from one digit to five digits by changing the temperature of the heat lamination roll. This shows that the breathable nonwoven fabrics of the Examples can easily produce packaging materials suited to the contents. From the above results, the breathable nonwoven fabric laminates of Examples 1 to 4 were highly reliable and could be used in a wide range of applications as breathable packaging materials. On the other hand, when a wet polyester nonwoven fabric is used for the thermoplastic resin fiber nonwoven fabric A in Comparative Example 1, sufficient tear strength is not obtained, and depending on the usage environment, there is a risk of causing a breakdown of the packaging material. Also, when a single cross-section polyester resin fiber is used for the material of the thermoplastic resin fiber nonwoven fabric B in Comparative Example 2, when the heat-sealed portion at 150°C is peeled off, there is a risk of contamination of the contents and the opening environment. When a polyethylene resin is not used for the thermoplastic resin fiber nonwoven fabric B in Comparative Example 3, a satisfactory heat seal strength is not obtained. The heat seal paper of Comparative Example 4 has low tear strength and low heat seal strength, so its applications are limited. [Industrial Applicability]

[0076] The breathable nonwoven fabric of the present invention has sufficient thermal adhesion over the entire heat-sealed surface, does not fuzz when the heat-sealed portion is peeled off, and its breathability can be adjusted by a relatively simple method. Furthermore, it has high tear strength, making it excellent as a variety of breathable packaging materials and potentially applicable to filter media. [Explanation of symbols]

[0077] 11...breathable packaging body 11, 21...breathable nonwoven fabric laminate, 22...thermoplastic resin fiber nonwoven fabric layer A, 23...thermoplastic resin fiber nonwoven fabric layer B, 31...breathable nonwoven fabric or adherend

Claims

1. A breathable nonwoven fabric comprising a thermoplastic resin fiber nonwoven fabric layer A in which one or more layers selected from a spunbonded nonwoven fabric mainly composed of polyester resin fibers and a meltblown nonwoven fabric mainly composed of polyester resin fibers are laminated, and one or more thermoplastic resin fiber nonwoven fabric layers B, wherein the thermoplastic resin fiber nonwoven fabric layer B contains a low melting point polyester resin, polyester fibers and a polyethylene resin, and the breathable nonwoven fabric has a tear strength of 1000 mN or more as measured in accordance with JIS P 8116:2000.

2. 2. The breathable nonwoven fabric according to claim 1, wherein the melting point of the low melting point polyester resin is 90 to 150°C, and the melting point of the polyethylene resin is 90 to 140°C.

3. 3. The breathable nonwoven fabric according to claim 1, wherein the thermoplastic resin fiber nonwoven fabric layer B has a low melting point polyester resin content of 11 to 41% by mass, a polyester fiber content of 9 to 34% by mass, and a polyethylene resin content of 25 to 80% by mass.

4. The breathable nonwoven fabric according to any one of claims 1 to 3, wherein the thermoplastic resin fiber nonwoven fabric layer A has a portion in which a spunbond nonwoven fabric, a meltblown nonwoven fabric, and a spunbond nonwoven fabric are laminated in this order at least.

5. The breathable nonwoven fabric according to any one of claims 1 to 4, wherein the breathable nonwoven fabric has an adhesive strength of 0.5 N / 15 mm or more when the surfaces to be used for heat sealing of the breathable nonwoven fabric are overlapped and heat sealed, in accordance with JIS K 6854-3:1999, at a 180° peel speed of 300 mm / min.

6. The breathable nonwoven fabric has a basis weight of 30 g / m ２ 150g / m or more ２ The breathable nonwoven fabric according to any one of claims 1 to 5, wherein:

7. A method for producing the breathable nonwoven fabric according to any one of claims 1 to 6, comprising the steps of: Step 1: preparing a thermoplastic resin fiber nonwoven fabric a as a thermoplastic resin fiber nonwoven fabric layer A and a thermoplastic resin fiber nonwoven fabric b as a thermoplastic resin fiber nonwoven fabric layer B. Step 2: A step of laminating a thermoplastic resin fiber nonwoven fabric a having a three or more layer configuration and one or two or more layers of a thermoplastic resin fiber nonwoven fabric b. Step 3: A step of heat-sealing the thermoplastic resin fiber nonwoven fabric a and the thermoplastic resin fiber nonwoven fabric b laminated in step 2 to obtain an air-permeable nonwoven fabric laminate.

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