Heat seal sheet and method for producing the same, and package

Abstract

To provide a heat seal sheet which has sufficient heat adhesion and appropriate air permeability in the whole heat seal surface, and is excellent in strength and a method for producing the same, and a package using the heat seal sheet.SOLUTION: A heat seal sheet has one or two or more thermoplastic resin fiber non-woven fabric layers A, and one or two or more thermoplastic resin fiber non-woven fabric layers B, wherein the thermoplastic resin fiber non-woven fabric layer B contains a low melting point polyester resin, a polyester resin fiber and a polyethylene resin, and Oken type air permeability measured according to JIS P 8121-2:2012 of the heat seal sheet is 1,000 seconds or more and 50,000 seconds or less, and elongation at break measured according to JIS P 8113:2006 thereof is 8% or more.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a heat seal sheet, a method for producing the same, and a package using the heat seal sheet. [Background technology]

[0002] 2. Description of the Related Art As a component for a storage bag for enclosing a heat generating element such as a disposable warmer or a medical heating element, a breathable material obtained by bonding a porous film to a breathable base material such as a nonwoven fabric is used. 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 porous film layers, A and 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. [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] The present invention aims to provide a heat seal sheet which has sufficient thermal adhesion and appropriate breathability over the entire heat seal surface and which has excellent strength, a method for producing the same, and a package using the heat seal sheet. [Means for solving the problem]

[0005] The present invention has the following aspects. <1> A heat seal sheet having one or more thermoplastic resin fiber nonwoven fabric layers A and one or more thermoplastic resin fiber nonwoven fabric layers B, The thermoplastic resin fiber nonwoven fabric layer B contains a low melting point polyester resin, a polyester resin fiber, and a polyethylene resin, The heat seal sheet has an Oken air permeability of 1000 seconds or more and 50000 seconds or less as measured in accordance with JIS P 8121-2:2012, and a breaking elongation of 8% or more as measured in accordance with JIS P 8113:2006. Heat seal sheet. <2> The thermoplastic resin fiber nonwoven fabric layer A is a nonwoven fabric layer derived from at least one selected from the group consisting of a wet-laid nonwoven fabric, a spunbonded nonwoven fabric, a thermal-bonded nonwoven fabric, a chemical-bonded nonwoven fabric, a needle-punched nonwoven fabric, a spunlace nonwoven fabric, a melt-blown nonwoven fabric, and an SMS nonwoven fabric. <1> The heat seal sheet according to claim 1. <3> The thermoplastic resin fiber nonwoven fabric layer A contains at least one fiber selected from the group consisting of polypropylene resin fibers, polyester resin fibers, and polyamide resin fibers. <1> or <2> The heat seal sheet according to claim 1. <4> The thermoplastic resin fiber nonwoven fabric layer B is a nonwoven fabric layer derived from a wet-laid nonwoven fabric. <1> ~ <3> 13. A heat seal sheet according to any one of claims 1 to 12. <5> When the heat seal sheets are sealed together, the adhesive strength when peeled at 180° at a peel speed of 300 mm / min according to JIS K 6854-3:1999 is 6.0 N / 15 mm or more. <1> ~ <4> 13. A heat seal sheet according to any one of claims 1 to 12. <6> The heat seal sheet has a basis weight of 30 g / m 2 More than 150g / m 2 Below is the <1> ~ <5> 13. A heat seal sheet according to any one of claims 1 to 12. <7> <1> ~ <6> 1. A method for producing a heat seal sheet 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 and a thermoplastic resin fiber nonwoven fabric b Step 2: 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 to obtain a laminate. Step 3: A step of heat-sealing the laminate obtained in step 2 <8> <1> ~ <6> A package using the heat seal sheet described in any one of the above. <9> The contents are powder-like items; <8> The packaging body described in <10> The powdered article is a powdered heat generating agent, and the package is for a disposable hand warmer. <9> The packaging body described in Effect of the Invention

[0006] According to the present invention, there are provided a heat seal sheet which has sufficient thermal adhesion and appropriate breathability over the entire heat seal surface and excellent strength, a method for producing the same, and a package using the heat seal sheet. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a cross-sectional view of one embodiment of a package. [Diagram 2] FIG. 2 is a cross-sectional view of one embodiment of a heat seal sheet. [Diagram 3] FIG. 2 is a cross-sectional view of another embodiment of a heat seal sheet. [Figure 4] FIG. 2 is a cross-sectional view of another embodiment of a heat seal sheet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] 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. The "breaking elongation" is the geometric mean value of the measured values ​​in the machine direction and the cross direction of the sheet measured in accordance with JIS P 8113:2006.

[0009] Hereinafter, one embodiment of the heat seal sheet and packaging body will be described with reference to Figs. 1 to 4. [Heat seal sheets and packaging materials] The package (11) is a package in which heat seal sheets (21) are bonded together, or a heat seal sheet is bonded to a sheet of nonwoven fabric or the like different from the heat seal sheet (FIG. 1). That is, it comprises a heat seal sheet (21) and an adherend (31), and the adherend (31) may be the heat seal sheet of this embodiment, another nonwoven fabric, or a thermoplastic resin film, and is not particularly limited as long as it can be heat sealed to the heat seal sheet (21). The package (11) may be a three-side sealed package or a pillow package formed from a single heat seal sheet (21).

[0010] The heat seal sheet (21) comprises one or more thermoplastic resin fiber nonwoven fabric layers A (22) and one or more thermoplastic resin fiber nonwoven fabric layers B (23) (FIGS. 2 and 3). As long as the heat seal sheet (21) comprises one or more thermoplastic resin fiber nonwoven fabric layers A (22) and one or more thermoplastic resin fiber nonwoven fabric layers B (23), it may also comprise a thermoplastic resin fiber nonwoven fabric layer C (41) different from the thermoplastic resin fiber nonwoven fabric layer A (22) and the thermoplastic resin fiber nonwoven fabric layer B (23) (FIG. 4). As described later, the heat seal sheet (21) is preferably obtained by laminating one or more layers of thermoplastic resin fiber nonwoven fabric a and one or more layers of thermoplastic resin fiber nonwoven fabric b, followed by heat fusing. The thermoplastic resin fiber nonwoven fabric layer A is a layer derived from the thermoplastic resin fiber nonwoven fabric a, and the thermoplastic resin fiber nonwoven fabric layer B is a layer derived from the thermoplastic resin fiber nonwoven fabric b. The heat seal sheet (21) has an Oken air permeability of 1000 seconds or more and 50000 seconds or less, measured in accordance with JIS P 8121-2:2012, and a breaking elongation of 8% or more, measured in accordance with JIS P 8113:2006. Furthermore, the thermoplastic resin fiber nonwoven fabric layer B contains a low melting point polyester resin, polyester resin fibers, and a polyethylene resin.

[0011] (Ouken style air permeability) The heat seal sheet (21) has an Oken air permeability of 1000 seconds or more and 50000 seconds or less, measured in accordance with JIS P 8121-2: 2012. When the Oken air permeability is 1000 seconds or more, a sufficient heat generation duration can be obtained when the sheet is used, for example, as a package for a disposable warmer, and when the Oken air permeability is 50000 seconds or less, a sufficient heat generation temperature can be obtained, which is preferable. The heat seal sheet (21) has an Oken air permeability of preferably 5,000 seconds or more and 40,000 seconds or less, and more preferably 8,000 seconds or more and 30,000 seconds or less. The Oken air permeability of the heat seal sheet (21) can be adjusted to a desired range by adjusting the heat fusion conditions when the thermoplastic resin fiber nonwoven fabric a and the thermoplastic resin fiber nonwoven fabric b are heat fused together. Also, the desired range can be achieved by adjusting the type, fiber diameter, basis weight, and thickness of the fibers constituting the thermoplastic resin fiber nonwoven fabric a and the thermoplastic resin fiber nonwoven fabric b used. Specifically, the Oken air permeability can be increased by increasing the pressure and temperature during heat fusion or by lengthening the processing time.

[0012] (Elongation at break) The heat seal sheet (21) has a breaking elongation of 8% or more as measured in accordance with JIS P 8113:2006. By making the breaking elongation 8% or more, when the sheet is used as a package for disposable warmers, the package can be prevented from breaking during use. This is also preferable because it improves the conformability to the adherend during use. The breaking elongation of the heat seal sheet (21) is more preferably 10% or more. The upper limit of the breaking elongation of the heat seal sheet (21) is not particularly limited, but from the viewpoint of ease of production of the heat seal sheet, it is preferably 40% or less, more preferably 30% or less, and even more preferably 25% or less. By laminating thermoplastic resin fiber nonwoven fabric a and thermoplastic resin fiber nonwoven fabric b and heat fusing them to produce a heat seal sheet, the fiber structure is maintained in the heat seal sheet (21), and the breaking elongation can be made high. In addition, the desired range can be achieved by adjusting the heat fusing conditions when heat fusing the thermoplastic resin fiber nonwoven fabric a and the thermoplastic resin fiber nonwoven fabric b, and the type, fiber diameter, fiber length, nonwoven fabric manufacturing method, basis weight, and thickness of the fibers constituting the thermoplastic resin fiber nonwoven fabric a and the thermoplastic resin fiber nonwoven fabric b used.

[0013] (Basic weight) The basis weight of the heat seal sheet of the present embodiment is preferably 30 g / m from the viewpoints of ease of production, appropriate heat seal strength, air permeability and breaking elongation. 2 More preferably, 50 g / m 2 More preferably, 70 g / m 2 and preferably 200 g / m 2 Less than 150 g / m 2 More preferably, 120 g / m 2 The following is the result. The basis weight of the heat seal sheet can be adjusted to a desired range by adjusting the basis weights of the thermoplastic resin fiber nonwoven fabric a and the thermoplastic resin fiber nonwoven fabric b to appropriate ranges.

[0014] <Thermoplastic resin fiber nonwoven fabric layer A> The heat seal sheet (21) of this embodiment has one or more thermoplastic resin fiber nonwoven fabric layers A. The thermoplastic resin fiber nonwoven fabric layer A (22) is a layer derived from a thermoplastic resin fiber nonwoven fabric a obtained by forming one or more types of thermoplastic resin fibers a group into a sheet by any of various known methods. Examples of sheet-making methods include wet papermaking, spunbonding, thermal bonding, chemical bonding, needle punching, spunlace, meltblowing, and SMS (laminated spunbond / meltblown / spunbond) methods, among which the spunbonding and SMS methods are preferred because they are made of continuous fibers, have high strength, and are less susceptible to fiber detachment. The wet papermaking method is also preferred from the viewpoint of uniformity of the resulting nonwoven fabric.

[0015] (Thermoplastic resin fiber nonwoven fabric a) As the thermoplastic resin fibers a group constituting the thermoplastic resin fiber nonwoven fabric a, various known materials can be used, but those having a melting point higher than the melting point (not particularly limited, for example, 150°C or lower) of the fibers constituting the thermoplastic resin fibers b group used in the thermoplastic resin fiber nonwoven fabric layer B (23) are preferred because they retain their fiber shape even after thermal lamination and are likely to provide appropriate air permeability and high breaking elongation.

[0016] The thermoplastic resin fiber nonwoven fabric a is preferably at least one selected from the group consisting of wet-laid nonwoven fabric, spunbonded nonwoven fabric, thermal-bonded nonwoven fabric, chemical-bonded nonwoven fabric, needle-punched nonwoven fabric, spunlace nonwoven fabric, melt-blown nonwoven fabric, and SMS nonwoven fabric. That is, the thermoplastic resin fiber nonwoven fabric layer A is preferably a nonwoven fabric layer derived from at least one selected from the group consisting of wet-laid nonwoven fabric, spunbonded nonwoven fabric, thermal-bonded nonwoven fabric, chemical-bonded nonwoven fabric, needle-punched nonwoven fabric, spunlace nonwoven fabric, melt-blown nonwoven fabric, and SMS nonwoven fabric. Among these, the thermoplastic resin fiber nonwoven fabric a is preferably at least one selected from the group consisting of wetlaid nonwoven fabrics, spunbonded nonwoven fabrics, and SMS nonwoven fabrics. As described above, wetlaid nonwoven fabrics are preferred because they are uniform nonwoven fabrics, and spunbonded nonwoven fabrics and SMS nonwoven fabrics are preferred because they are made of continuous fibers, have high strength, and are less susceptible to fiber detachment.

[0017] Examples of the fibers constituting the group a of thermoplastic resin fibers include, but are not limited to, polypropylene resin fibers, polyester resin fibers, and polyamide resin fibers. That is, the thermoplastic resin fiber nonwoven fabric a and the thermoplastic resin fiber nonwoven fabric layer A preferably contain at least one selected from the group consisting of polypropylene resin fibers, polyester resin fibers, and polyamide resin fibers, more preferably contain at least one selected from the group consisting of polypropylene resin fibers and polyester resin fibers, even more preferably contain polypropylene resin fibers or polyester resin fibers, and even more preferably consist of polypropylene resin fibers or polyester resin fibers. It is preferable that the thermoplastic resin fibers constituting the thermoplastic resin fiber nonwoven fabric a do not melt completely in the heat fusion process described below, and that the fibrous shape remains partially in the thermoplastic resin fiber nonwoven fabric layer A even in the heat seal sheet (21).

[0018] Furthermore, it is possible to use natural pulp fibers, regenerated fibers, and other chemical fibers in combination, provided that the object of the present invention is not impaired.

[0019] The average fiber diameter of the thermoplastic resin fibers (a) is not particularly limited, but is, for example, preferably 0.1 μm or more and 50 μm or less, more preferably 0.5 μm or more and 30 μm or less, and further preferably 0.5 μm or more and 20 μm or less.

[0020] The basis weight of the thermoplastic resin fiber nonwoven fabric a and the thermoplastic resin fiber nonwoven fabric layer A (22) 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 breaking elongation, 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 heat seal sheet 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.

[0021] The thermoplastic resin fiber nonwoven fabric layer A (22) 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.

[0022] <Thermoplastic resin fiber nonwoven fabric layer B> The thermoplastic resin fiber nonwoven fabric layer B (23) is a layer derived from a thermoplastic resin fiber nonwoven fabric b obtained by forming one or more kinds of thermoplastic resin fibers b into a sheet by any of various known methods. The thermoplastic resin fiber nonwoven fabric layer B contains a low melting point polyester resin, polyester resin fibers, and polyethylene resin. The mass ratio of the low melting point polyester resin, polyester resin fibers, and polyethylene resin (low melting point polyester resin:polyester resin fibers:polyethylene resin) is not particularly limited, but is preferably 5:5:90 to 41.25:33.75:25.

[0023] (Thermoplastic resin fiber nonwoven fabric b) One or more types of thermoplastic resin fibers can be used as the thermoplastic resin fiber group b constituting the thermoplastic resin fiber nonwoven fabric b. In order to bond with the thermoplastic resin fiber nonwoven fabric layer A (22) after thermal lamination and to exhibit the heat sealability of the heat seal sheet, it is preferable that the fibers constituting the thermoplastic resin fiber group b contain fibers having a melting point of less than 150°C. The fibers constituting the thermoplastic resin fiber group b may have a single structure or a core-sheath structure of two or more layers. In the case of a core-sheath structure, the melting point of the sheath resin is preferably less than 150°C, and the melting point of the core resin may be 150°C or higher.

[0024] Examples of thermoplastic resin fibers group b include various polyethylene resin fibers, polyethylene-vinyl acetate ester resin fibers, low melting point polyester resin fibers, composite fibers having a core-sheath structure in which the core is a normal polyester resin and the sheath is the various polyethylene resin fibers described above, polyethylene-vinyl acetate ester resin, composite resins having a core-sheath structure in which the core is a normal polyester resin and the sheath is a low melting point polyester resin. These resin fibers may also have a multi-branched structure.

[0025] Among these, polyester resin fibers and polyethylene resin fibers having a core-sheath structure in which a low melting point polyester resin is used for the sheath and a normal polyester resin is used for the core are preferably used because they have excellent thermal lamination properties and heat sealability with thermoplastic resin fiber nonwoven fabric a. Here, the low melting point polyester resin used in the sheath has a melting point less than 150° C., preferably 140° C. or less, more preferably 130° C. or less, and even more preferably 120° C. or less. On the other hand, the polyester used in the core has a melting point of 150° C. or more, preferably 180° C. or more, more preferably 200° C. or more, and even more preferably 240° C. or more. An example of the polyester used in the core is polyethylene terephthalate. In addition, it is preferable that the polyethylene fiber is a polyethylene hyperbranched fiber obtained by quasi-pulping polyethylene, because this allows the thermoplastic resin fiber nonwoven fabric b to be produced by wet papermaking. By producing the thermoplastic resin fiber nonwoven fabric b by wet papermaking, it is preferable that a nonwoven fabric having excellent uniformity and density can be obtained. When the thermoplastic resin fiber nonwoven fabric b is a nonwoven fabric obtained using a core-sheath structure polyester fiber in which a low melting point polyester is used as the sheath and a normal polyester is used as the core, and polyethylene fiber, the low melting point polyester resin and the polyethylene fiber in the sheath of the core-sheath structure polyester fiber melt in the thermoplastic resin fiber nonwoven fabric layer B after heat fusion, and therefore the fiber shape is not necessarily maintained. Note that it is not limited to the case where all of the low melting point polyester resin and the polyethylene fiber are melted, and it is sufficient that at least a portion of them are melted.

[0026] The thermoplastic resin fiber nonwoven fabric b is preferably a nonwoven fabric obtained by a wet papermaking method, and is preferably obtained by wet papermaking of a core-sheath polyester fiber in which the low melting point polyester is used for the sheath and a normal polyester is used for the core, and a polyethylene hyperbranched fiber. The thermoplastic resin fiber nonwoven fabric b preferably contains 10% by mass or more and 75% by mass or less of core-sheath polyester fibers, in which a low-melting point polyester is used for the sheath and a normal polyester is used for the core, more preferably 20% by mass or more and 70% by mass or less, and even more preferably 30% by mass or more and 60% by mass or less. The mass ratio of the sheath to the core (sheath / core) 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 polyester fibers with a core-sheath structure in which a low melting point polyester is used for the sheath and a normal polyester is used for the core include the Tepyrus (registered trademark) series manufactured by Teijin Frontier Co., Ltd. and PET-based binder fibers manufactured by Kuraray Co., Ltd.

[0027] The thermoplastic resin fiber nonwoven fabric b contains polyethylene hyperbranched fibers in an amount of preferably 25% by mass to 90% by mass, more preferably 30% by mass to 80% by mass, and even more preferably 40% by mass to 75% by mass. Examples of polyethylene hyperbranched fibers obtained by quasi-pulping polyethylene include the SWP (registered trademark) series manufactured by Mitsui Chemicals, Inc.

[0028] In the thermoplastic resin fiber nonwoven fabric layer B derived from the thermoplastic resin fiber nonwoven fabric b obtained using these thermoplastic resin fibers b group, 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 constituting the thermoplastic resin fibers are at least partially melted, and therefore are referred to as "low-melting point polyester resin" and "polyethylene resin", respectively.

[0029] In the thermoplastic resin fiber nonwoven fabric layer B, the total content of the low melting point polyester resin, polyester fiber, and polyethylene resin is 50 mass% or more, more preferably 70 mass% or more, even more preferably 80 mass% or more, and even more preferably 85 mass% or more, and the upper limit is 100 mass% or less.

[0030] In addition, the thermoplastic resin fiber nonwoven fabric b may be used in combination with natural pulp, which is not thermoplastic but is environmentally friendly and has high strength. Examples of natural pulp include wood pulp (softwood pulp, hardwood pulp, etc.) and non-wood pulp (hemp pulp, cotton pulp, straw pulp, etc.).

[0031] The fiber diameter of the fibers used in the thermoplastic resin fiber nonwoven fabric b is not particularly limited, but is, for example, from 1 μm to 60 μm, and preferably from 1 μm to 40 μm.

[0032] The basis weight of the thermoplastic resin fiber nonwoven fabric b and the thermoplastic resin fiber nonwoven fabric layer B (23) is not particularly limited, but is, for example, 5 g / m 2 More than 100g / m 2 In order to obtain sufficient thermal adhesiveness, breathability, and elongation at break, the thickness is preferably adjusted to within a range of 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 heat seal sheet 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.

[0033] The thermoplastic resin fiber nonwoven fabric layer B (23) may be a single layer or a multi-layer structure of two or more layers. As described above, 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.

[0034] As the manufacturing method of the thermoplastic resin fiber nonwoven fabric b, various known methods can be applied, among which the wet papermaking method is preferred because it is easy to obtain a good texture even at a low basis weight and pinholes in the heat seal sheet are unlikely to occur.

[0035] 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.

[0036] To the raw material slurry, various dispersants, surfactants, thickeners and other internal additives may be added for the purpose of adjusting the formation.

[0037] The method for drying the thermoplastic resin fiber nonwoven fabric b after wet papermaking is not particularly limited, and a multi-cylinder dryer, Yankee dryer, hot air dryer, infrared dryer, etc. can be used. When using a multi-cylinder dryer or Yankee dryer, 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.

[0038] <Thermoplastic resin fiber nonwoven fabric layer C> The thermoplastic resin fiber nonwoven fabric layer C (41) is a layer derived from a thermoplastic resin fiber nonwoven fabric c obtained by forming one or more kinds of thermoplastic resin fibers c into a sheet by any of various known methods. The thermoplastic resin fiber nonwoven fabric layer C is a layer provided on the side of the heat seal sheet of this embodiment that is not to be heat sealed.

[0039] (Thermoplastic resin fiber nonwoven fabric c) One or more types of fibers may be used as the thermoplastic resin fiber group c constituting the thermoplastic resin fiber nonwoven fabric c. For adhesion to the thermoplastic resin fiber nonwoven fabric layer A (22) after thermal lamination, it is preferable that the fibers constituting the thermoplastic resin fiber group c contain thermoplastic resin fibers having a melting point of less than 150°C.

[0040] Examples of thermoplastic resin fibers in group c include various polyethylene resin fibers, polyethylene-vinyl acetate ester resin fibers, low-melting point polyester resin fibers, composite fibers with a core-sheath structure in which the core is a normal polyester resin and the sheath is the various polyethylene resin fibers described above, polyethylene-vinyl acetate ester resin, and composite resins with a core-sheath structure in which the core is a normal polyester resin and the sheath is a low-melting point polyester resin. These resin fibers may also have a multi-branched structure. Natural pulp fibers, regenerated fibers, and other chemical fibers may also be used in combination. Examples of natural pulp include wood pulp (softwood pulp, hardwood pulp, etc.) and non-wood pulp (hemp pulp, cotton pulp, straw pulp, etc.).

[0041] Among these, it is preferable that the thermoplastic resin fiber nonwoven fabric c contains natural pulp as a fiber group constituting the thermoplastic resin fiber nonwoven fabric c. When tension is applied in a heated state during thermal fusion (thermal lamination) in step 3 described below, the openings in the thermoplastic resin fiber nonwoven fabric layer A and the thermoplastic resin fiber nonwoven fabric layer B may open, causing a decrease in air permeability. It is preferable that the thermoplastic resin fiber nonwoven fabric c contains natural pulp, since this suppresses the openings and the decrease in air permeability. Furthermore, the thermoplastic resin fiber nonwoven fabric b may shrink during heat fusion, causing the heat seal sheet to curl, but by using the thermoplastic resin fiber nonwoven fabric c containing pulp, curling is suppressed, which is preferable. The content of natural pulp in the thermoplastic resin fiber nonwoven fabric c is preferably 5% by mass or more, and more preferably 10% by mass or more.

[0042] The basis weight of the thermoplastic resin fiber nonwoven fabric C and the thermoplastic resin fiber nonwoven fabric layer C (41) is not particularly limited, but is, for example, 10 g / m 2 More than 100g / m 2 In order to obtain sufficient thermal adhesiveness, breathability, and elongation at break, the thickness is preferably adjusted to within a range of 15 g / m 2 More than 80g / m 2 Less than 20 g / m 2 More than 60g / m 2 The following is the result. As described later, in the case of a laminated structure of b / a / c, the basis weight of the thermoplastic resin fiber nonwoven fabric c and the thermoplastic resin fiber nonwoven fabric layer C (41) is preferably greater than the basis weight of the thermoplastic resin fiber nonwoven fabric b and the thermoplastic resin fiber nonwoven fabric layer B (23), and is preferably 5 g / m 2 The above-mentioned configuration is preferable because curling of the heat seal paper due to curling of the thermoplastic resin fiber nonwoven fabric b and the thermoplastic resin fiber nonwoven fabric layer B (23) is suppressed.

[0043] [Method of manufacturing heat seal sheet] The method for producing the heat seal sheet 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 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 to obtain a laminate. Step 3: A step of heat-sealing the laminate obtained in step 2

[0044] <Process 1> Step 1 is a step of preparing a thermoplastic resin fiber nonwoven fabric a and a thermoplastic resin fiber nonwoven fabric b. The thermoplastic resin fiber nonwoven fabric a and the thermoplastic resin fiber nonwoven fabric b may be prepared by the method described above.

[0045] <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 to obtain a laminate. 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. 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. In addition, a three-layer structure of b / a / c may be used. When the above three-layer structure is used, it is preferable to reduce the basis weight of the nonwoven fabric layer B, which has a higher thermal shrinkage rate among the thermoplastic resin fiber nonwoven fabrics b and c, because curling after thermal lamination can be reduced. The thermoplastic resin fiber nonwoven fabrics a may all be the same or different, and the same applies to the thermoplastic resin fiber nonwoven fabrics b.

[0046] <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 by passing the laminate obtained in step 2 between two heated rolls.

[0047] 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. 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 used in the thermoplastic resin fiber nonwoven fabric b, it is possible to obtain a sufficient effect of suppressing the raising of the surface of the thermoplastic resin fiber nonwoven fabric b and also obtain heat seal strength. In addition, by setting the temperature of the heating roll to not higher 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, it is preferable that the fiber shape is maintained in the thermoplastic resin fiber nonwoven fabric layer A (22) even after heat fusion and sufficient breaking elongation is obtained.

[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 heat seal sheet (21) of this embodiment is obtained by heat fusing (thermal laminating) a thermoplastic resin fiber nonwoven fabric a and a thermoplastic resin fiber nonwoven fabric b, and has sufficient thermal adhesion and breathability over the entire heat seal surface, and also has the necessary breaking elongation, making it excellent as a package. The heat seal sheet (21) of this embodiment is suitable as a package for a powdery product, the contents of which are a powdery product, for example, a packaging bag for a powdery product. An example of a powdery product is a powdered heat generating agent, and an example of a package for a powdery product is a package for a disposable warmer.

[0051] [Application] The heat seal sheet (21) is used, for example, as a package for disposable hand warmers. By overlapping and thermocompressing parts of the heat seal sheet (21) with each other or parts of the heat seal sheet (21) with parts of an adherend such as wrapping paper, laminated paper, film, or molded container so as to form a space inside, a package for powdery goods can be formed in which the heat seal sheet (21) and the adherend are thermocompressed with each other. 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.

[0052] The use of the heat seal sheet (21) is not limited to packaging for powdery products, but can also be used for packaging food, various freshness-preserving agents such as desiccants and oxygen absorbers, general industrial products, etc. It is also possible to perform printing on either the front or back surface, or on the outermost surface of both surfaces.

[0053] When the heat seal sheets are heat sealed together, the adhesive strength at 180° peeling at a peeling speed of 300 mm / min according to JIS K 6854-3:1999 is not particularly limited, but is preferably 6.0 N / 15 mm or more, more preferably 9.0 N / 15 mm or more, even more preferably 12.0 N / 15 mm or more, and particularly preferably 15.0 N / 15 mm or more. If the adhesive strength is within the above range, package breakage accidents can be prevented, which is preferable. Furthermore, when a packaging body is produced by bonding the heat seal sheet of this embodiment to another adherend, the above-mentioned adhesive strength when the heat seal sheet of this embodiment is heat sealed to the adherend is preferably 6.0 N / 15 mm or more, more preferably 9.0 N / 15 mm or more, even more preferably 12.0 N / 15 mm or more, and particularly preferably 15.0 N / 15 mm or more. The adhesive strength is measured by the method described in the Examples. The adhesive strength can be adjusted within a desired range by adjusting, within appropriate ranges, 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 production of the heat seal sheet, and the heat fusion conditions between the heat seal sheets or between the heat seal sheets and the adherend. EXAMPLES

[0054] 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.

[0055] [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 at a surface temperature of 105°C to obtain a paper having a basis weight of 35 g / m 2 Thus, a thermoplastic resin fiber nonwoven fabric b was obtained.

[0056] <Production of heat seal sheets> The thermoplastic resin fiber nonwoven fabric b obtained above and the polypropylene resin spunbond nonwoven fabric a (fiber diameter about 15 μm, continuous fiber, basis weight 30 g / m 2 ), thermoplastic resin fiber nonwoven fabric b, and thermoplastic resin fiber nonwoven fabric c were laminated in this order, and the laminate was thermally laminated at a line speed of 4.7 m / min with a thermal laminator having a heating roll with a fluorine-coated surface at a roll temperature of 170°C for the upper and lower rolls. 2 Thus, the heat seal sheet of Example 1 was obtained. <Creating the packaging> Two of the heat seal sheets obtained above were stacked on top of each other, and the peripheral portions were heat-pressed using a heat press tester under heat-pressing conditions of 170° C., 0.2 MPa, and 1.0 second to produce a package (packaging bag).

[0057] [Example 2] In Example 1, a wet-laid polyester nonwoven fabric (polyethylene terephthalate nonwoven fabric, fiber diameter 14 μm, fiber length 5 mm, basis weight 30 g / m) was used in place of the polypropylene resin spunbond nonwoven fabric a. 2 The same procedure as in Example 1 was repeated except that a 100 g / m2 sheet was used. 2 Thus, a heat seal sheet and a package were obtained.

[0058] [Example 3] In the production of the heat seal sheet of Example 1, a wet-laid polyester nonwoven fabric (polyethylene terephthalate nonwoven fabric, fiber diameter 14 μm, fiber length 5 mm, basis weight 40 g / m) was used in place of the polypropylene resin spunbond nonwoven fabric A. 2 ) and the basis weight of the thermoplastic resin fiber nonwoven fabric b is 30 g / m 2 The same procedure as in Example 1 was repeated except that the basis weight was 100 g / m 2 Thus, a heat seal sheet and a package were obtained.

[0059] [Example 4] In the production of the heat seal sheet of Example 1, a polypropylene resin spunbonded nonwoven fabric (SMS method, basis weight 30 g / m) was used in place of the polypropylene resin spunbonded nonwoven fabric a. 2 The same procedure as in Example 1 was repeated except that a 100 g / m2 sheet was used. 2 Thus, a heat seal sheet and a package were obtained. The polypropylene resin nonwoven fabric (SMS method) used is made of polypropylene resin fibers and is a spunbond nonwoven fabric (fiber diameter 15 μm, continuous fiber, basis weight 14 g / m 2 ) / Meltblown nonwoven fabric (fiber diameter 1.5μm, continuous fiber, basis weight 2g / m 2 ) / Spunbond nonwoven fabric (fiber diameter 15 μm, continuous fiber, basis weight 14 g / m 2 ) is an SMS nonwoven fabric having the following structure.

[0060] [Example 5] In producing the package of Example 1, the heat seal sheet obtained in Example 1 was overlapped with the CPP side of a polypropylene film (PET#12 / sealant / CPP#30) so that the heat seal sheet was in contact with the heat seal sheet, and the peripheral portion was heat-pressed using a heat press tester under heat-pressing conditions of 190°C, 0.2 MPa, and 1.0 second to produce a package.

[0061] [Comparative Example 1] <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.

[0062] <Preparation of paint for thermal adhesive layer> 138 parts by mass of EVA (ethylene-vinyl acetate copolymer) 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 (polyethylene) dispersion (Chemipearl W400, manufactured by Mitsui Chemicals, Inc., PE particle average particle size 4 μm, solid content concentration 40%, PE density 920 kg / m 3A 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 (ring and ball method) 110°C), 18 parts by mass of a reinforced rosin-based 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.

[0063] <Production of heat seal sheets> The coating material for the thermal adhesive layer was applied to one side of the breathable substrate obtained above 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 the thermal adhesive layer after drying was 2.5 g / m 2 In this way, a heat seal sheet of Comparative Example 4 was obtained. <Creating packaging> Two of the obtained heat seal sheets were overlapped so that the thermal adhesive layers were in contact with each other, and the peripheral portions were heat-pressed using a heat press tester under heat-pressing conditions of 170° C., 0.2 MPa, and 1.0 second to produce a package.

[0064] [Measurement method] The heat sealable sheets and nonwoven fabrics obtained in the Examples and Comparative Examples were evaluated as follows. <Oken air permeability measurement> The Oken air permeability of the heat seal sheet was measured in accordance with JIS P 8117:2009.

[0065] <Measurement of breaking elongation> The breaking elongation of the heat seal sheet was measured in the longitudinal and transverse directions of the sheet in accordance with JIS P 8113:2006, and the geometric mean value of these values ​​was calculated.

[0066] <Measurement of heat seal adhesive strength (HS adhesive strength) of heat sealed parts of packaging> The heat-sealed portion of each package obtained in the Examples and Comparative Examples was cut to a width of 15 mm to prepare a sample for measuring adhesive strength. The adhesive strength (N / 15 mm) of the obtained sample for measuring adhesive strength was measured in accordance with JIS K 6854-3:1999 using a tensile tester (model: Tensilon RTC-1250A, manufactured by Orientec Co., Ltd.) by chucking the ends of the composite film and heat-sealed sheet of the sample and peeling them off at a peeling speed of 300 mm / min using a 180-degree peel method.

[0067] The Oken air permeability, breaking elongation, and adhesive strength of the heat-sealed portion were evaluated for each of the heat-sealed sheets and packages of Examples 1 to 5 and Comparative Example 1. The results are shown in Table 1.

[0068] [Table 1]

[0069] The heat seal sheets of Examples 1 to 5 have an air permeability (seconds) of 9,500 to 26,000 seconds. For example, if a heat generating composition for disposable hand warmers (a heat generating composition containing iron, activated carbon, vermiculite, water, and salts) is enclosed in a package using these sheets, and the maximum temperature when heated and the duration from 40°C to the maximum temperature to 40°C are measured in accordance with JIS S 4100:2007, it is believed that all of these will fall within the useful range for a disposable hand warmer. In addition, the heat seal sheets of Examples 1 to 5 have a breaking elongation of more than 10%, and are therefore unlikely to break even when used as a stick-on type package, not limited to disposable hand warmers. Furthermore, the adhesive strength of the heat seal portion exceeds 6.0 N / 15 mm, so the package is unlikely to break. On the other hand, in the case of a paper-based heat seal sheet as in Comparative Example 1, the air permeability is 20 seconds, so if it is used as a packaging material for disposable warmers, the maximum temperature reached will be high (65°C or higher), which is not within the practical range. Also, since the breaking elongation is low, there is a risk of the package breaking when used for pasting purposes, not limited to disposable warmers, and since the adhesive strength of the heat seal part is also low, there is a risk of the package breaking during use and the contents leaking out, so it is not preferable as a package. [Industrial Applicability]

[0070] The heat sealable sheet of the present invention has appropriate air permeability, high breaking elongation, and sufficient thermal adhesion over the entire heat-sealed surface, making it excellent for use as a package, particularly as a package for powdery goods. [Explanation of symbols]

[0071] 11...package, 21...heat seal sheet, 22...thermoplastic resin fiber nonwoven fabric layer A, 23...thermoplastic resin fiber nonwoven fabric layer B, 31...heat seal sheet or adherend, 41...thermoplastic resin fiber nonwoven fabric layer C

Claims

1. A heat seal sheet having one or more thermoplastic resin fiber nonwoven fabric layers A and one or more thermoplastic resin fiber nonwoven fabric layers B, The thermoplastic resin fiber nonwoven fabric layer B contains a low melting point polyester resin, a polyester resin fiber, and a polyethylene resin, The heat seal sheet has an Oken air permeability of 1000 seconds or more and 50000 seconds or less as measured in accordance with JIS P 8121-2:2012, and a breaking elongation of 8% or more as measured in accordance with JIS P 8113:2006. Heat seal sheet.

2. 2. The heat seal sheet according to claim 1, wherein the thermoplastic resin fiber nonwoven fabric layer A is a nonwoven fabric layer derived from at least one selected from the group consisting of a wet-laid nonwoven fabric, a spunbonded nonwoven fabric, a thermal-bonded nonwoven fabric, a chemical-bonded nonwoven fabric, a needle-punched nonwoven fabric, a spunlace nonwoven fabric, a melt-blown nonwoven fabric, and an SMS nonwoven fabric.

3. The heat sealable sheet according to claim 1 , wherein the thermoplastic resin fiber nonwoven fabric layer A contains at least one fiber selected from the group consisting of polypropylene resin fibers, polyester resin fibers and polyamide resin fibers.

4. The heat sealable sheet according to claim 1 , wherein the thermoplastic resin fiber nonwoven fabric layer B is a nonwoven fabric layer derived from a wet-laid nonwoven fabric.

5. The heat seal sheet according to claim 1, wherein the adhesive strength when the heat seal sheets are heat sealed together and peeled at 180° at a peel speed of 300 mm / min in accordance with JIS K 6854-3:1999 is 6.0 N / 15 mm or more.

6. The heat seal sheet has a basis weight of 30 g / m ２ 150g / m or more ２ 2. The heat seal sheet according to claim 1, wherein:

7. A method for producing the heat seal sheet according to any one of claims 1 to 6, comprising the following steps 1 to 3 in this order: Step 1: Preparing thermoplastic resin fiber nonwoven fabric a and thermoplastic resin fiber nonwoven fabric b Step 2: 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 to obtain a laminate. Step 3: A step of heat-sealing the laminate obtained in step 2

8. A package using the heat seal sheet according to any one of claims 1 to 6.

9. 9. The package of claim 8, wherein the contents are a powder-like product.

10. The package according to claim 9, wherein the powdered product is a powdered heat generating agent and the package is for a disposable hand warmer.

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