Extraction sheet material

Abstract

To provide a sheet material for extraction that prevents molten resin from striking through during heat-seal treatment.SOLUTION: A sheet material for extraction 1 is formed by laminating in this order: a spun bonded nonwoven fabric layer 5; a first melt-blown nonwoven fabric layer 10; and a second melt-blown nonwoven fabric layer 20. The melt point of resin forming the second melt-blown nonwoven fabric layer 20 is set to be lower than the melt point of resin forming the spun bonded nonwoven fabric layer 5 and the melting point of resin forming the first melt-blown nonwoven fabric layer 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an extraction sheet material in which a spunbonded nonwoven fabric layer, a first meltblown nonwoven fabric layer, and a second meltblown nonwoven fabric layer are laminated. [Background technology]

[0002] Nonwoven fabric sheets consisting of two layers, a spunbond nonwoven fabric layer and a meltblown nonwoven fabric layer, are generally relatively strong and have excellent extractability, and are therefore used as extraction sheet materials for extracting coffee, tea, soup stock, etc. (see, for example, Patent Documents 1 and 2).

[0003] The extraction sheet material described in Patent Document 1 has a spunbond nonwoven fabric layer and a meltblown nonwoven fabric layer made of polyester fibers, and by adjusting the fiber gaps and 3% modulus of the extraction sheet material, it is possible to achieve both improved transparency and component extractability and reduced powder leakage, thereby preventing the occurrence of defective products during manufacturing or processing.

[0004] The extraction sheet material described in Patent Document 2 is composed of a spunbond nonwoven fabric layer with improved heat resistance of the fibers and a meltblown nonwoven fabric layer that quickly softens and fluidizes when heated, and is capable of achieving high sealing strength even when sealed in a short time. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2018 / 216047 [Patent Document 2] International Publication No. 2015 / 147119 Summary of the Invention [Problem to be solved by the invention]

[0006] The extraction sheet materials in Patent Documents 1 and 2 are both made by laminating a spunbond nonwoven fabric layer and a meltblown nonwoven fabric layer. Since the spunbond nonwoven fabric layer has large gaps between its constituent fibers, there is a risk that the molten resin will leak out of the spunbond nonwoven fabric layer when heat-sealed (hereinafter referred to as "bleed-through") and contaminate the seal bar.

[0007] The present invention has been made in view of the above problems, and has as its object to provide an extraction sheet material that can prevent molten resin from seeping through to the back during heat sealing. [Means for solving the problem]

[0008] The characteristic configuration of the extraction sheet material according to the present invention to solve the above problem is as follows: An extraction sheet material comprising a spunbond nonwoven fabric layer, a first meltblown nonwoven fabric layer, and a second meltblown nonwoven fabric layer laminated in this order, The melting point of the resin constituting the second meltblown nonwoven fabric layer is set to be lower than the melting point of the resin constituting the spunbonded nonwoven fabric layer and the melting point of the resin constituting the first meltblown nonwoven fabric layer.

[0009] The extraction sheet material of this configuration is constructed by laminating a spunbonded nonwoven fabric layer, a first meltblown nonwoven fabric layer, and a second meltblown nonwoven fabric layer in this order. The resin fibers of the spunbonded nonwoven fabric layer are partially thermocompressed together, resulting in relatively large gaps between the resin fibers. Meanwhile, the resin fibers of the first meltblown nonwoven fabric layer are stretched with hot air during manufacturing, resulting in self-fusion and also fusion with some of the resin fibers of the spunbonded nonwoven fabric layer, maintaining a small three-dimensional gap between the resin fibers. Furthermore, the extraction sheet material of this configuration is designed so that the melting point of the resin of the second meltblown nonwoven fabric layer is lower than the melting point of the resin of the spunbonded nonwoven fabric layer and the melting point of the resin of the first meltblown nonwoven fabric layer. Therefore, even if the resin of the second meltblown nonwoven fabric layer melts during the heat-sealing process, the resin of the first meltblown nonwoven fabric layer does not melt, maintaining a small three-dimensional gap between the resin fibers. As a result, even if the resin of the second melt-blown nonwoven fabric layer that has melted during the heat sealing process attempts to leak out onto the surface of the spunbond nonwoven fabric layer, it is blocked by the first melt-blown nonwoven fabric layer, thereby preventing the molten resin from seeping through to the back during the heat sealing process.

[0010] In the extraction sheet material according to the present invention, A welded portion is formed by a heat sealing process in which a predetermined portion where the second meltblown nonwoven fabric layer is folded so that the second meltblown nonwoven fabric layer is on the inside and overlapped with the second meltblown nonwoven fabric layer is heated and pressed from the spunbonded nonwoven fabric layer side, It is preferable that the resin derived from the second meltblown nonwoven fabric layer penetrates into the thickness of the first meltblown nonwoven fabric layer without reaching the spunbonded nonwoven fabric layer.

[0011] In the extraction sheet material of this configuration, at the welded portion formed by the heat sealing process, the resin derived from the second meltblown nonwoven fabric layer penetrates into the thickness of the first meltblown nonwoven fabric layer without reaching the spunbonded nonwoven fabric layer, thereby preventing the resin derived from the second meltblown nonwoven fabric layer from striking through to the surface of the spunbonded nonwoven fabric layer.

[0012] In the extraction sheet material according to the present invention, It is preferable that the difference between the melting point of the resin constituting the first melt-blown nonwoven fabric layer and the melting point of the resin constituting the second melt-blown nonwoven fabric layer is set to 30° C. or more.

[0013] With this extraction sheet material, the difference in melting point between the resin constituting the first melt-blown nonwoven fabric layer and the resin constituting the second melt-blown nonwoven fabric layer is set to a sufficient value (30°C or higher), so that even if the resin constituting the second melt-blown nonwoven fabric layer melts during heat sealing, the resin constituting the first melt-blown nonwoven fabric layer does not melt, and the three-dimensional gaps between the resin fibers are reliably maintained. This reliably prevents the molten resin from striking through during heat sealing.

[0014] In the extraction sheet material according to the present invention, The first melt-blown nonwoven fabric layer preferably has an average fiber diameter of 0.4 to 30 μm.

[0015] According to the extraction sheet material of this configuration, the average fiber diameter of the first melt-blown nonwoven fabric layer is 0.4 to 30 μm, so that the fibers constituting the first melt-blown nonwoven fabric layer can be made extremely fine while ensuring a certain level of production efficiency and filter function, making it difficult for the molten resin of the fibers constituting the second melt-blown nonwoven fabric layer to penetrate into the gaps between the fibers constituting the first melt-blown nonwoven fabric layer during heat sealing, thereby further improving the effect of preventing the molten resin from striking through during heat sealing.

[0016] In the extraction sheet material according to the present invention, The basis weight of the first melt-blown nonwoven fabric layer is 1 to 10 g / m 2 It is preferable that:

[0017] According to the extraction sheet material of this configuration, the basis weight of the first melt-blown nonwoven fabric layer is 1 to 10 g / m 2 This allows the thickness of the first melt-blown nonwoven fabric layer and the gaps between the fibers to be appropriate, further improving the effect of preventing the molten resin from striking through to the back during heat sealing.

[0018] In the extraction sheet material according to the present invention, It is preferable that the first melt-blown nonwoven fabric layer has an average fiber diameter of 16.5 μm or less, and the second melt-blown nonwoven fabric layer has an average fiber diameter of 13.6 μm or less.

[0019] According to the extraction sheet material of this configuration, the average fiber diameter of the first melt-blown nonwoven fabric layer is 16.5 μm or less, and the average fiber diameter of the second melt-blown nonwoven fabric layer is 13.6 μm or less, so that the effect of preventing the molten resin from striking through to the back during the heat sealing process is particularly remarkable. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic diagram of an extraction sheet material according to the present invention, in which (a) is a cross-sectional view, (b) is a diagram showing the entanglement state of fibers constituting a spunbonded nonwoven fabric layer, (c) is a diagram showing the entanglement state of fibers constituting a first meltblown nonwoven fabric layer, (d) is a diagram showing the entanglement state of fibers constituting a second meltblown nonwoven fabric layer, and (e) is a diagram showing the entanglement state of fibers in a laminated state of the spunbonded nonwoven fabric layer, the first meltblown nonwoven fabric layer, and the second meltblown nonwoven fabric layer. [Figure 2] FIG. 2 shows the steps of the method for producing an extraction sheet material according to the present invention, where (a) is an explanatory diagram of the first step, (b) is an explanatory diagram of the second step, and (c) is an explanatory diagram of the third step. [Figure 3]FIG. 3 shows an extraction bag made from an extraction sheet material, where (a) is a plan view and (b) is a cross-sectional view taken along line XX' in (a). [Figure 4] FIG. 4 shows a cross section of the portion of the extraction sheet material that is to be heat-sealed, where (a) is a diagram showing the state before heat-sealing, and (b) is a cross section taken along line YY′ in FIG. 3(b) after heat-sealing. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, an embodiment of the extraction sheet material of the present invention will be described in detail with reference to the drawings. Note that the size relationships of the layer structures of the extraction sheet material shown in each drawing are appropriately exaggerated to facilitate understanding of the invention and do not necessarily reflect the actual size relationships. Furthermore, the present invention is not intended to be limited to the configurations described below.

[0022] <Layer structure of extraction sheet material> 1 is a schematic diagram of an extraction sheet material 1 according to the present invention, where (a) is a cross-sectional view, (b) is a diagram of the entanglement of fibers constituting a spunbonded nonwoven fabric layer 5, (c) is a diagram of the entanglement of fibers constituting a first meltblown nonwoven fabric layer 10, (d) is a diagram of the entanglement of fibers constituting a second meltblown nonwoven fabric layer 20, and (e) is a diagram of the entanglement of fibers in a laminated state of the spunbonded nonwoven fabric layer 5, the first meltblown nonwoven fabric layer 10, and the second meltblown nonwoven fabric layer 20. The extraction sheet material 1 shown in FIG. 1(a) is a sheet material used as a material for extraction bags for teas such as black tea and green tea, and broths made from bonito, kelp, etc., and has a structure in which a spunbonded nonwoven fabric layer 5, a first meltblown nonwoven fabric layer 10, and a second meltblown nonwoven fabric layer 20 are laminated.

[0023] <Spunbond nonwoven fabric layer> The spunbond nonwoven fabric layer 5, which primarily affects ingredient extraction, is made of a spunbond web produced by the spunbonding method. The spunbonding method is a nonwoven fabric manufacturing method in which molten resin extruded from a spinning nozzle is drawn and stretched by blowing a high-speed gas stream onto the resin, which is then cooled and solidified to form fibers. These fibers are then collected on a collector to form a web. In the spunbonding method, the thickness of the web may be adjusted using a flat roll or a partial thermal bonding process may be performed using a heat embossing roll, as needed. Spunbond webs produced by the spunbonding method generally have higher strength than meltblown webs produced by the meltblown method. Therefore, by placing the spunbond nonwoven fabric layer 5 on the outside when processed into extraction bags, it is possible to prevent fiber unraveling due to contact between extraction bags during transportation, etc. In order for the extraction sheet material 1 to have high ingredient extraction properties suitable for extracting tea and broth, it is necessary to use a spunbond web with large fiber gaps as the spunbond nonwoven fabric layer 5. The size of the gaps between fibers in a spunbond web can be controlled to some extent by adjusting the fiber length per unit area when producing the spunbond web. Here, "fiber length per unit area" is defined as the total length of all fibers contained in a unit area of ​​nonwoven fabric.

[0024] <First and second meltblown nonwoven fabric layers> The first meltblown nonwoven fabric layer 10 is a layer that prevents the resin of the fibers that make up the second meltblown nonwoven fabric layer 20 from leaking into the spunbond nonwoven fabric layer 5 when a heat-sealing process is performed. On the other hand, the second meltblown nonwoven fabric layer 20 is a layer that welds the extraction sheet materials 1 together when a heat-sealing process is performed. Both the first meltblown nonwoven fabric layer 10 and the second meltblown nonwoven fabric layer 20 are made of meltblown webs produced by the meltblowing method. The meltblowing method is a method of producing nonwoven fabrics in which a high-temperature, high-velocity gas flow is blown onto molten resin extruded from a spinning nozzle, stretching the molten resin and scattering it as it turns into fibers, which are then collected on a collector and solidified into a sheet.

[0025] FIG. 1(e) is a diagram showing the entanglement of fibers in the laminated state of the spunbonded nonwoven fabric layer 5, the first meltblown nonwoven fabric layer 10, and the second meltblown nonwoven fabric layer 20. In FIG. 1(e), the fibers constituting the spunbonded nonwoven fabric layer 5 are partially thermocompression-bonded to each other, resulting in relatively large gaps between the fibers. On the other hand, the fibers constituting the first meltblown nonwoven fabric layer 10 are stretched with hot air during production, resulting in self-fusion bonding between the fibers and also fusion bonding to some of the fibers constituting the spunbonded nonwoven fabric layer 5, thereby maintaining small gaps between the fibers in three dimensions. In addition, the melting point of the resin constituting the second meltblown nonwoven fabric layer 20 is set to be lower than the melting points of the resins constituting the spunbonded nonwoven fabric layer 5 and the first meltblown nonwoven fabric layer 10. When a heat sealing process is performed on an extraction sheet material 1 having such a configuration, even if the resin fibers constituting the second melt-blown nonwoven fabric layer 20 melt, the resin fibers constituting the first melt-blown nonwoven fabric layer 10 do not melt, and the three-dimensional fiber gaps are maintained small.

[0026] [Ventilation volume of extraction sheet material] The extraction sheet material 1 is suitable for use in extracting teas such as black tea and green tea, and broths made from bonito, kelp, etc., and has an air permeability of 150 cc / cm, which is an index of component extractability. 2 sec or more. The ventilation rate is preferably 150cc / cm 2 If the time is less than 1.5 seconds, the extractability of the components to be extracted may be poor.

[0027] [Weight of extraction sheet material] The basis weight of the extraction sheet material 1 is 10 to 30 g / m 2 It is preferable that the basis weight of the extraction sheet material 1 is 10 g / m 2 If the weight of the extraction sheet material 1 is less than 30 g / m, the strength of the extraction sheet material 1 may be insufficient. 2If the weight of the extraction sheet material 1 is in the above range, it will have excellent extractability of the components to be extracted and good strength.

[0028] [Fiber materials constituting each nonwoven fabric layer] Examples of fiber materials constituting the spunbond nonwoven fabric layer 5, the first meltblown nonwoven fabric layer 10, and the second meltblown nonwoven fabric layer 20 include thermoplastic resins such as polyester resins, nylon resins, polyethylene resins, polypropylene resins, and vinylon resins, among which polyester resins are preferred. Examples of polyester resins include polyester resins such as linear polyesters and copolymer polyesters, and suitable examples include polyethylene terephthalate / polyethylene isophthalate copolymers and polylactic acid (PLA). Suitable polyethylene terephthalate / polyethylene isophthalate copolymers include those in which the polymerization ratio of the acid components terephthalic acid / isophthalic acid is adjusted within an appropriate range, and those obtained by polymerizing terephthalic acid as the main component with dicarboxylic acids other than isophthalic acid, such as 5-sodium sulfoisophthalic acid, 4-hydroxybenzoic acid, adipic acid, naphthalenedicarboxylic acid, and phthalic acid, and diol components, such as ethylene glycol, 1,4-butanediol, diethylene glycol, propylene glycol, and pentaerythritol, in appropriate ratios. Furthermore, polyester resins may contain, as appropriate, additives such as impact modifiers, crystal nucleating agents, color inhibitors, delustering agents, antioxidants, heat resistance agents, plasticizers, lubricants, weather resistance agents, colorants, and pigments, such as various elastomers.

[0029] [Form of each nonwoven fabric layer] Examples of the form of the fibers constituting each of the nonwoven fabric layers of the spunbond nonwoven fabric layer 5, the first meltblown nonwoven fabric layer 10, and the second meltblown nonwoven fabric layer 20 include monofilaments, multifilaments, and composite fibers with a core-sheath structure that combine two types of resins. The cross-sectional shape of the fibers is not particularly limited, and may be a typical round shape, as well as irregular shapes such as flat, elliptical, triangular, hollow, Y-shaped, T-shaped, and U-shaped.

[0030] [Average fiber diameter of spunbond nonwoven fabric layer] The average fiber diameter of the fibers constituting the spunbonded nonwoven fabric layer 5 is preferably 10 to 30 μm, more preferably 13 to 26 μm. If the average fiber diameter is less than 10 μm, the component extractability of the extraction sheet material 1 may be poor. If the average fiber diameter is more than 30 μm, the strength of the spunbonded nonwoven fabric layer 5 may be insufficient. The term "average fiber diameter" refers to the average thickness of the fibers constituting the nonwoven fabric sheet. For example, if the cross-sectional shape of the fibers is round, the average fiber diameter is the average diameter of the fibers. If the cross-sectional shape of the fibers is irregular, such as flat, elliptical, or polygonal, the average fiber diameter is the average diameter of circles having the same cross-sectional area as the cross-sectional area of ​​the fibers. The average fiber diameter can be determined, for example, by observing the cross-section of the nonwoven fabric sheet using a microscope, selecting multiple fibers, measuring the fiber diameters of each, and calculating the average value.

[0031] [Basis weight of spunbond nonwoven fabric layer] The basis weight of the spunbond nonwoven fabric layer 5 is 8 to 25 g / m 2 is preferable, and more preferably 15 g / m 2 The weight is 8g / m or less. 2 If the weight is less than 25 g / m, the strength of the spunbonded nonwoven fabric layer 5 may be insufficient. 2 If the concentration exceeds this range, the problems of strength and strike-through will not occur, but there is a risk that the extractability of the components to be extracted will be poor.

[0032] [Average fiber diameter of first melt-blown nonwoven fabric layer] The average fiber diameter d1 of the fibers constituting the first meltblown nonwoven fabric layer 10 is preferably 0.4 to 30 μm, more preferably 0.5 to 21 μm, and even more preferably 0.5 to 16.5 μm. Generally, the advantage of the meltblowing method is that the fibers constituting the meltblown web can be made extremely fine. In the extraction sheet material 1 of the present invention, the fibers constituting the first meltblown nonwoven fabric layer 10 are made extremely fine, and the average fiber diameter d1 is set to the above range. This makes it difficult for the resin of the fibers constituting the second meltblown nonwoven fabric layer 20 to penetrate between the fibers constituting the first meltblown nonwoven fabric layer 10 during heat sealing, thereby further improving the effect of preventing the resin of the fibers constituting the second meltblown nonwoven fabric layer 20 from striking through to the surface on the spunbond nonwoven fabric layer 5 side. If the average fiber diameter d1 is less than 0.4 μm, the effect of preventing bleed-through is excellent, but production efficiency is low and the gaps between the fibers constituting the first melt-blown nonwoven fabric layer 10 become too narrow, causing clogging and potentially impairing the filtering function.If the average fiber diameter d1 exceeds 30 μm, the resin of the fibers constituting the second melt-blown nonwoven fabric layer 20 is likely to penetrate into the gaps between the fibers constituting the first melt-blown nonwoven fabric layer 10 during heat sealing, and there is a risk that the effect of preventing bleed-through of the resin of the fibers constituting the second melt-blown nonwoven fabric layer 20 cannot be sufficiently achieved.

[0033] [Basis weight of first meltblown nonwoven fabric layer] The basis weight of the first meltblown nonwoven fabric layer 10 is 1 to 10 g / m 2 is preferable, and more preferably 8 g / m 2 The basis weight is 1g / m or less. 2 If the weight is less than 10 g / m, there is a risk that the effect of preventing the resin of the fibers constituting the second melt-blown nonwoven fabric layer 20 from striking through to the back during heat sealing may not be sufficient, and there is a risk that the strength of the first melt-blown nonwoven fabric layer 10 may be insufficient. 2If the weight is greater than this, the amount of air permeability of the entire extraction sheet material 1 will decrease, which may result in poor extractability of the components to be extracted. If the weight is within the above range, the effect of preventing the resin of the fibers constituting the second melt-blown nonwoven fabric layer 20 from striking through to the back during heat sealing can be further improved.

[0034] [Average fiber diameter of second melt-blown nonwoven fabric layer] The average fiber diameter d2 of the fibers constituting the second melt-blown nonwoven fabric layer 20 depends on the basis weight of the spunbonded nonwoven fabric layer 5 and the first melt-blown nonwoven fabric layer 10, but is preferably not too thin compared to the first melt-blown nonwoven fabric layer 10, and is preferably 0.4 to 30 μm, more preferably 0.5 to 13.6 μm. If the average fiber diameter d2 is less than 0.4 μm, there is a risk that the effect of fusing the extraction sheet materials 1 together during the heat-sealing process will not be sufficiently achieved. If the average fiber diameter d2 exceeds 30 μm, the processing time required to melt the fibers constituting the second melt-blown nonwoven fabric layer 20 during the heat-sealing process will be long, and there is a risk that the manufacturing efficiency of the extraction bag 100 described below will decrease.

[0035] [Basis weight of second melt-blown nonwoven fabric layer] The basis weight of the second melt-blown nonwoven fabric layer 20 is 1 to 10 g / m 2 is preferably 4 to 7 g / m 2 The basis weight is 1g / m 2 If the weight is less than 10 g / m, the amount of resin melted in the second melt-blown nonwoven fabric layer 20 during the heat sealing process may be insufficient, and appropriate seal strength may not be obtained. 2 If the weight of the second melt-blown nonwoven fabric layer 20 is in the above range, the amount of resin melted in the second melt-blown nonwoven fabric layer 20 during the heat-sealing process is appropriate, and the extraction sheet material 1 has excellent component extractability.

[0036] [Melt flow rate of second melt-blown nonwoven fabric layer] The fibers constituting the second melt-blown nonwoven fabric layer 20 preferably have a melt flow rate of 150 to 270 g / 10 min at a temperature 70 to 120° C. higher than the melting point of the resin constituting the fibers.

[0037] A portion of the molten resin that will become second meltblown nonwoven fabric layer 20 solidifies while entering the gaps between the fibers of first meltblown nonwoven fabric layer 10. This prevents the resin from second meltblown nonwoven fabric layer 20 from striking through to the surface of spunbonded nonwoven fabric layer 5.

[0038] The difference in melting point between the fibers constituting the first meltblown nonwoven fabric layer 10 and the fibers constituting the second meltblown nonwoven fabric layer 20 is preferably 30° C. or more, and more preferably 42 to 106° C. If the difference in melting point between the two nonwoven fabric layers 10, 20 is 30° C. or more, by setting the processing temperature in the heat sealing treatment sufficiently higher than the melting point of the fibers constituting the second meltblown nonwoven fabric layer 20, it is possible to melt the fibers constituting the second meltblown nonwoven fabric layer 20 in a short time without melting the fibers constituting the spunbond nonwoven fabric layer 5 or the first meltblown nonwoven fabric layer 10.

[0039] <Method of manufacturing the extraction sheet material> 2 shows the steps of the manufacturing method of the extraction sheet material 1 according to the present invention, where (a) is an explanatory diagram of the first step, (b) is an explanatory diagram of the second step, and (c) is an explanatory diagram of the third step. The manufacturing method of the extraction sheet material 1 according to the present invention will be described below with reference to FIG. 2.

[0040] [First step (spunbond nonwoven fabric layer formation step)] As shown in FIG. 2(a), molten thermoplastic resin is pressure-fed from extruder 51 to spinneret 52, and the spun yarn is cooled and stretched via ejector 53, and then spread and deposited on conveyor net 54a of conveyor 54 to form spunbond web 35 that constitutes web-like spunbond nonwoven fabric layer 5.

[0041] [Second step (first melt-blown nonwoven fabric layer formation step)] Next, as shown in FIG. 2(b), molten thermoplastic resin is pressure-fed from an extruder 57 to a spinneret 58 onto the surface of the web-like spunbond nonwoven fabric layer 5 formed in the first step, which is being transported by a conveyor net 59a of a conveyor 59, and is stretch-spun with high-temperature compressed air. The resin is then accumulated before solidifying, thereby forming a sheet laminated with a first melt-blown web 41 that constitutes the web-like first melt-blown nonwoven fabric layer 10.

[0042] [Third step (second melt-blown nonwoven fabric layer forming step)] 2(c), a thermoplastic resin with a lower melting point than that used in the first and second steps is melted from an extruder 62 onto the surface of the laminated sheet 40 formed in the first and second steps and conveyed by a conveyor net 64a of a conveyor 64. The resin is then pressure-spun into a spinneret 63 and stretched with high-temperature compressed air. The resulting web is then accumulated before solidification to form a second melt-blown web 42 that constitutes the web-like second melt-blown nonwoven fabric layer 20. A flat roll or an embossing roll can then be used to adjust the thickness of the web-like nonwoven fabric layer or to partially heat-bond the nonwoven fabric, thereby obtaining an extraction sheet material 1 having a laminated structure of a spunbond nonwoven fabric layer 5, a first melt-blown nonwoven fabric layer 10, and a second melt-blown nonwoven fabric layer 20.

[0043] In the above manufacturing method, one extruder and one spinneret are shown for each manufacturing process, but this is not limited to this, and two or more extruders and spinnerets may be used in each process to laminate a web using multiple types of resins.

[0044] An example of forming a web-like nonwoven fabric layer using a manufacturing method including steps 1 to 3 described above has been shown, but the extraction sheet material 1 can also be manufactured by appropriately adopting the method described below to laminate each layer or the entire product together.

[0045] (Lamination integration method example 1) In this method, a first meltblown web-like nonwoven fabric layer 10 is formed on the surface of a spunbonded web-like nonwoven fabric layer 5 formed in a first step, and the resulting laminate is then subjected to a partial heat bonding process. Subsequently, a second meltblown web-like nonwoven fabric layer 20 is formed in a third step. The partial heat bonding process is carried out, for example, by passing a web formed by spreading and depositing a fibrous resin on a net between a heated embossing roll having an uneven surface structure and a smooth flat roll. The area ratio of the thermocompression-bonded portion (partial thermocompression bonding rate) is preferably 5.0 to 30.0% of the total area of ​​the nonwoven fabric surface.

[0046] According to lamination integration method example 1, a web-like first meltblown nonwoven fabric layer 10 formed in the second step is laminated on the web-like spunbond nonwoven fabric layer 5 formed in the first step, and then integrated by partial thermal bonding, thereby forming a laminate of the spunbond nonwoven fabric layer 5 and the first meltblown nonwoven fabric layer 10, in which the web-like first meltblown nonwoven fabric layer 10 is embedded in the web-like spunbond nonwoven fabric layer 5 and the first meltblown nonwoven fabric layer 10 are firmly integrated. Then, a web-like second meltblown nonwoven fabric layer 20 is accumulated, thereby preventing the web-like second meltblown nonwoven fabric layer 20 from reaching the spunbond nonwoven fabric layer 5 beyond the first meltblown nonwoven fabric layer 10 during sheet formation, and improving the effect of preventing bleed-through of the molten resin when the extraction sheet material 1 is heat-sealed.

[0047] (Lamination integration method example 2) In this method, a web-like spunbonded nonwoven fabric layer 5 is formed in a first step, followed by a partial heat bonding process, and then in a second step, a web-like first meltblown nonwoven fabric layer 10 is accumulated before solidification to form a laminated sheet of the spunbonded nonwoven fabric layer 5 and the web-like first meltblown nonwoven fabric layer 10, and then in a third step, a web-like second meltblown nonwoven fabric layer 20 is laminated before solidification to form a sheet.

[0048] According to the laminated integration method example 2, by forming the spunbonded nonwoven fabric layer 5 that has been subjected to a partial thermal bonding treatment in advance, it is less likely that the web-like first meltblown nonwoven fabric layer 10 will penetrate into the spunbonded nonwoven fabric layer 5 than in the laminated integration method example 1. However, by integrating the web-like first meltblown nonwoven fabric layer 10 onto the spunbonded nonwoven fabric layer 5, a network of the web-like first meltblown nonwoven fabric layer 10 is formed, which prevents the web-like second meltblown nonwoven fabric layer 20 from passing over the web-like first meltblown nonwoven fabric layer 10 and reaching the spunbonded nonwoven fabric layer 5, and the effect of preventing the molten resin from striking through to the back when the extraction sheet material 1 is heat-sealed can be improved to some extent.

[0049] (Lamination Integration Method Example 3) This method involves sequentially performing a spunbond nonwoven fabric layer formation step of forming a web-like spunbond nonwoven fabric layer 5, a first meltblown nonwoven fabric layer formation step of forming a web-like first meltblown nonwoven fabric layer 10 on the surface of the web-like spunbond nonwoven fabric layer 5, and a second meltblown nonwoven fabric layer formation step of forming a web-like second meltblown nonwoven fabric layer 20 on the surface of the web-like first meltblown nonwoven fabric layer 10, followed by a partial heat bonding treatment step to obtain a laminate of the spunbond nonwoven fabric layer 5, the first meltblown nonwoven fabric layer 10, and the second meltblown nonwoven fabric layer 20.

[0050] According to Example 3 of the lamination and integration method, after forming a web-like nonwoven fabric layer in the first, second, and third steps, they are integrated by a partial heat-bonding treatment step. Therefore, the web-like second melt-blown nonwoven fabric layer 20 formed in the third step is somewhat prone to penetrating into the web-like spunbond nonwoven fabric layer 5, and the effect of preventing the molten resin from penetrating to the back when the extraction sheet material 1 is heat-sealed is somewhat inferior, but the effect of preventing penetrating to the back is obtained compared to when the first melt-blown nonwoven fabric layer 10 is not used.

[0051] The lamination and integration method can be not only the above-mentioned methods 1 to 3, but also various other methods, such as combining a partial thermal bonding treatment after each step, or a method of applying pressure to the entire surface by passing through flat rolls without losing the shape of the fibers to integrate them.

[0052] <Extraction bag> 3A and 3B show an infusion bag 100 made from the infusion sheet material 1, with (a) being a plan view and (b) being a cross-sectional view taken along line XX' in (a). As shown in Figs. 3A and 3B, the infusion bag 100 is a tea bag containing an infusion material 103 such as tea leaf powder, and has welded portions 102 formed on three sides of a bag portion 101.

[0053] The bag portion 101 is a portion that maintains the structure of the extraction sheet material 1 as it is, and has high component extractability suitable for extracting tea and soup stock.

[0054] 4(a) shows a cross section of the portion of the extraction sheet material 1 to be heat-sealed, illustrating the state before the heat-sealing process. The welded portion 102 is a portion where the edge portion of the overlapping portion where the extraction sheet material 1 is folded in half with the second melt-blown nonwoven fabric layer 20 on the inside is welded by heat-sealing, and is formed by placing the second melt-blown nonwoven fabric layers 20 opposite each other and applying heat and pressure from the spunbond nonwoven fabric layer 5 side with a seal bar H, as shown in FIG.

[0055] FIG. 4(b) is a partial cross-sectional view of the welded portion 102 taken along line YY' in FIG. 3(b). At the welded portion 102, the fibers constituting the second meltblown nonwoven fabric layer 20 melt and resolidify to form a resin welded layer 25, thereby integrating the overlapping extraction sheet materials 1. During the heat-sealing process, some of the resin melted in the second meltblown nonwoven fabric layer 20 penetrates into the gaps between the fibers constituting the first meltblown nonwoven fabric layer 10 due to the clamping pressure of the seal bar H. Therefore, at the welded portion 102 of the extraction bag 100, some of the resin welded layer 25 derived from the second meltblown nonwoven fabric layer 20 penetrates into the gaps between the fibers constituting the first meltblown nonwoven fabric layer 10 within the thickness of the first meltblown nonwoven fabric layer 10 without reaching the spunbonded nonwoven fabric layer 5. Meanwhile, at the welded portion 102, the resin does not penetrate into the spunbonded nonwoven fabric layer 5, maintaining the original shape of the spunbonded nonwoven fabric layer 5.

[0056] In the extraction sheet material 1 of this embodiment, the resin fibers constituting the spunbonded nonwoven fabric layer 5 are partially thermocompressed together, resulting in relatively large gaps between the resin fibers. Meanwhile, the resin fibers constituting the first meltblown nonwoven fabric layer 10 are stretched with hot air during production, causing the fibers to self-bond and also to partially fuse with the resin fibers constituting the spunbonded nonwoven fabric layer 5, maintaining a small three-dimensional gap between the resin fibers. Furthermore, in the extraction sheet material 1 of this configuration, the melting point of the resin constituting the second meltblown nonwoven fabric layer 20 is set lower than the melting point of the resin constituting the spunbonded nonwoven fabric layer 5 and the melting point of the resin constituting the first meltblown nonwoven fabric layer 10. Therefore, even if the resin constituting the second meltblown nonwoven fabric layer 20 melts during the heat-sealing process, the resin constituting the first meltblown nonwoven fabric layer 10 does not melt, maintaining a small three-dimensional gap between the resin fibers. As a result, even if the resin of the second melt-blown nonwoven fabric layer 20 that melts during the heat sealing process tries to leak out onto the surface on the spunbond nonwoven fabric layer 5 side, it is blocked by the first melt-blown nonwoven fabric layer 10, and the molten resin can be prevented from seeping through to the back during the heat sealing process.

[0057] The above describes the extraction sheet material of the present invention based on one embodiment, but the present invention is not limited to the configuration described in the above embodiment, and the configuration can be changed as appropriate within the scope of the spirit of the present invention. [Example]

[0058] Hereinafter, examples of the extraction sheet material of the present invention will be described, but the present invention is not limited to the following examples.

[0059] Extraction sheet materials having the characteristic features of the present invention (Examples 1 to 8) and extraction sheet materials not having the characteristic features of the present invention (Comparative Examples 1 and 2) were produced, and an evaluation of strike-through was carried out.

[0060] Example 1 In the first step (spunbond nonwoven fabric layer formation step) described above, a web-like spunbond nonwoven fabric layer made of polyethylene terephthalate (PET (melting point: 252-256°C)) resin fibers was formed. Then, in the second step (first meltblown nonwoven fabric layer formation step) described above, a web-like first meltblown nonwoven fabric layer made of polyethylene terephthalate (PET (melting point: 252-256°C)) resin fibers was formed on the surface of the web-like spunbond nonwoven fabric layer formed in the first step. The laminate of the web-like spunbond nonwoven fabric layer and the web-like first meltblown nonwoven fabric layer was then subjected to a partial heat bonding treatment at a partial heat compression bonding rate of 15%. Furthermore, in the third step (second meltblown nonwoven fabric layer formation step) described above, a web-like second meltblown nonwoven fabric layer made of resin fibers of polyethylene terephthalate copolymer (co-PET (melting point: 200-210°C)), a low-melting-point polyester, was formed on the surface of the first meltblown nonwoven fabric layer. Thereafter, the sheet was passed through flat rolls to obtain the extraction sheet material of Example 1. The basis weight of the entire extraction sheet material of Example 1 was 18 g / m 2 The basis weight of the spunbond nonwoven fabric layer is 10 g / m 2 The basis weight of the first meltblown nonwoven fabric layer is 2 g / m 2 The basis weight of the second meltblown nonwoven fabric layer is 6 g / m 2In an image of the cross section of the extraction sheet material of Example 1 taken with an electron microscope (SEM), the diameters of the fibers constituting the spunbond nonwoven fabric layer were measured at 10 points, and the average fiber diameter calculated as the average value was 13.6 μm. The first meltblown nonwoven fabric layer and the second meltblown nonwoven fabric layer in the extraction sheet material of Example 1 were also measured using the same measurement method. As a result, the average fiber diameter of the first meltblown nonwoven fabric layer was 13.6 μm, and the average fiber diameter of the second meltblown nonwoven fabric layer was 10.3 μm.

[0061] Examples 2 to 8 In the first to third steps, the sheet movement speed, the heating temperature for melting the resin, the temperature of the airflow hitting the molten resin, the spray distance of the molten resin, etc. were appropriately adjusted. In the extraction sheet material of Example 7, a low-melting-point polyester (co-PET) with a melting point of 150 to 160°C was used as the resin fiber constituting the second melt-blown nonwoven fabric layer. In the extraction sheet material of Example 8, a polylactic acid (PLA) with a melting point of approximately 162°C was used as the resin fiber constituting the second melt-blown nonwoven fabric layer. Otherwise, the extraction sheet materials of Examples 2 to 8 were obtained using procedures similar to those of Example 1.

[0062] (Comparative Examples 1 and 2) The extraction sheet materials of Comparative Examples 1 and 2 were obtained by forming a spunbond nonwoven fabric layer (outer layer) made of PET (melting point: 252 to 256°C) resin fiber and a meltblown nonwoven fabric layer (inner layer) made of co-PET (melting point: 200 to 210°C) resin fiber in the same manner as in Example 1, except that the first meltblown nonwoven fabric layer in the extraction sheet material of Example 1 was not formed.

[0063] (Evaluation of bleed-through) A long extraction sheet material was set in a rotary automatic filling and packaging machine (manufactured by Topac Co., Ltd.), and a predetermined portion was clamped and surface-welded with a seal bar to form a rectangular bag body measuring 80 mm x 100 mm with 8 mm-wide surface-welded portions formed on the edges of three of the four sides. 7 g of barley tea extract material was sealed in the bag, and an extraction bag was produced. The temperature of the seal bar at this time was 150°C for the top seal portion and 170°C for the side seal portion. The rotary automatic filling and packaging machine was operated for 10 minutes, and the peelability of the extraction sheet material from the seal bar was observed, and the degree of fiber bleed-through was evaluated. The evaluation criteria are as follows. (Evaluation criteria) ⊚: Extraction bags can be manufactured without the extraction sheet material adhering to the seal bar. ◯: The extraction sheet material adheres slightly to the seal bar, but the extraction bag can be manufactured without any problems. ×: The extraction sheet material adheres to the seal bar, causing problems when manufacturing the extraction bag.

[0064] For the extraction sheet materials of Examples 1 to 8 and Comparative Examples 1 and 2, the basis weight of each layer and the entire sheet, the average fiber diameter of each layer, the melting point of each layer, and the results of the strike-through evaluation are shown in Table 1.

[0065] [Table 1]

[0066] In the bleed-through evaluation, the extraction sheet materials of Examples 1 to 8 were able to continuously produce extraction bags using a rotary automatic filling and packaging machine without any problems. In the extraction sheet materials of Examples 1 to 8, even if the resin constituting the second meltblown nonwoven fabric layer melted during the heat-sealing process, the resin constituting the first meltblown nonwoven fabric layer did not melt, maintaining a small three-dimensional gap between the resin fibers. Thus, it was confirmed that, even if the resin of the second meltblown nonwoven fabric layer melted during the heat-sealing process tried to leak onto the surface of the spunbonded nonwoven fabric layer, it was blocked by the first meltblown nonwoven fabric layer, preventing bleed-through. In particular, the extraction sheet materials of Examples 1 to 3, 5, and 7 to 8 had a first meltblown nonwoven fabric layer with an average fiber diameter of 16.5 μm or less and a second meltblown nonwoven fabric layer with an average fiber diameter of 13.6 μm or less, resulting in a particularly remarkable bleed-through prevention effect.

[0067] On the other hand, in the extraction sheet materials of Comparative Examples 1 and 2, in the bleed-through evaluation, the extraction sheet material adhered to the seal bar, causing problems when producing extraction bags using a rotary automatic filling and packaging machine. The extraction sheet materials of Comparative Examples 1 and 2 do not have the first melt-blown nonwoven fabric layer of the extraction sheet materials of Examples 1 to 8. For this reason, it is thought that in the extraction sheet materials of Comparative Examples 1 and 2, the co-PET constituting the inner layer melts during the heat-sealing process, and the molten co-PET leaks out onto the surface of the spunbond nonwoven fabric layer constituting the outer layer, causing bleed-through. [Industrial Applicability]

[0068] The extraction sheet material of the present invention can be used for extraction bags used for extracting teas such as black tea and green tea, and broth from bonito, kelp, and the like. [Explanation of symbols]

[0069] 1 Extraction sheet material 5. Spunbond nonwoven layer 10 First meltblown nonwoven fabric layer 20 Second meltblown nonwoven fabric layer 102 Dissolution Part

Claims

1. An extraction sheet material comprising a spunbond nonwoven fabric layer, a first meltblown nonwoven fabric layer, and a second meltblown nonwoven fabric layer laminated in this order, The melting point of the resin constituting the second meltblown nonwoven fabric layer is set to be lower than the melting point of the resin constituting the spunbonded nonwoven fabric layer and the melting point of the resin constituting the first meltblown nonwoven fabric layer, The spunbonded nonwoven fabric layer and the first meltblown nonwoven fabric layer are integrated into the extraction sheet material in such a manner that the web-like first meltblown nonwoven fabric layer is embedded in the web-like spunbonded nonwoven fabric layer.

2. A welded portion is formed by a heat sealing process in which a predetermined portion where the second meltblown nonwoven fabric layer is folded so that the second meltblown nonwoven fabric layer is on the inside and overlapped with the second meltblown nonwoven fabric layer is heated and pressed from the spunbonded nonwoven fabric layer side, The extraction sheet material according to claim 1, wherein the resin derived from the second meltblown nonwoven fabric layer penetrates into the thickness of the first meltblown nonwoven fabric layer without reaching the spunbonded nonwoven fabric layer.

3. The difference between the melting point of the resin constituting the first melt-blown nonwoven fabric layer and the melting point of the resin constituting the second melt-blown nonwoven fabric layer is set to 30 ° C. or more. The extraction sheet material according to claim 1 or 2.

4. The extraction sheet material according to any one of claims 1 to 3, wherein the average fiber diameter of the first melt-blown nonwoven fabric layer is 0.4 to 30 μm.

5. The basis weight of the first meltblown nonwoven fabric layer is 1 to 10 g / m ２ The extraction sheet material according to any one of claims 1 to 4,

6. The extraction sheet material according to any one of claims 1 to 5, wherein the average fiber diameter of the first melt-blown nonwoven fabric layer is 16.5 μm or less, and the average fiber diameter of the second melt-blown nonwoven fabric layer is 13.6 μm or less.

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