Filter bag

Abstract

To provide a filter bag which has excellent filterability and heat sealability using an environmentally friendly material.SOLUTION: A filter bag comprises a non-woven fabric including core-sheath polylactic acid fibers, polylactic acid fibers and pulp fibers. The content of the pulp fibers is 10 mass% or more and 30 mass% or less relative to the total content of the content of the core-sheath polylactic acid fibers, the content of the polylactic acid fibers and the content of the pulp fibers.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a filter bag.

Background Art

[0002] Conventionally, filter bags for decocting coffee, black tea, green tea, barley tea, dashi, etc., or for extracting them by pouring hot water or water are known. As filter bags, bags made of a non-woven fabric of synthetic fibers that are inexpensive and excellent in functionality, or bags incorporating binder fibers such as polyester-based or polyolefin-based binder fibers into pulp are used. Such conventional filter bags are generally discarded as household waste after being used up, and are disposed of by incineration or landfill.

[0003] Most of the powder after extracting coffee, black tea, green tea, barley tea, dashi, etc. is of natural origin and can be used as fertilizer. Therefore, it is desired to reduce the environmental load by using biodegradable fibers for filter bags as well. Representative biodegradable fibers include polylactic acid fibers. For example, Patent Document 1 discloses a coffee extraction sheet material made of polylactic acid, having an average fiber diameter of 20 μm or less, an air permeability of 10 to 250 cm 3 / cm 2 ·second, and having a water absorption rate of 5 seconds or less in water at a temperature of 60 °C or higher, which can moderately filter coffee fine particles, moderately adsorb oil and fat components, obtain a high-quality coffee extract, gradually decompose in the natural environment, and not lead to environmental destruction during disposal after use.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] However, as also shown in Patent Document 1, when polylactic acid fibers are used alone, the aperture tends to become large, and it is difficult to adjust the filtration performance to a predetermined value. Furthermore, it has been found that when a nonwoven fabric made of polylactic acid fibers is mixed with other plant fibers to adjust physical properties such as air permeability, the heat sealability particularly tends to decrease.

[0006] Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a filter bag that uses a material with a low environmental load, is excellent in filtration performance, and is excellent in heat sealability. [Means for Solving the Problems]

[0007] As a result of intensive studies to achieve the above object, the present inventors have found that, in particular, by using a nonwoven fabric in which core-sheath polylactic acid fibers and a predetermined amount of pulp fibers are mixed with polylactic acid fibers, the above problems can be solved, and the present invention has been completed.

[0008] That is, the present invention is as follows. [1] A filter bag comprising a nonwoven fabric containing polylactic acid fibers, core-sheath polylactic acid fibers, and pulp fibers, wherein the content of the pulp fibers is 10% by mass or more and 30% by mass or less with respect to the total amount of the content of the polylactic acid fibers, the content of the core-sheath polylactic acid fibers, and the content of the pulp fibers. Filter bag. [2] The air permeability of the nonwoven fabric is 50 cc / cm 2 ·sec or more and 130 cc / cm 2 ·sec or less, and the surface roughness (Sq) of at least one surface A of the nonwoven fabric is 10 μm or less. The filter bag according to [1]. [3] The density of the non-woven fabric is 0.36 g / cm 3 or more, The filter bag according to [1] or [2]. [4] Step 1 of producing a non-woven fabric containing polylactic acid fibers, core-sheath polylactic acid fibers, and pulp fibers by a wet method, Step 2 of forming the non-woven fabric into a bag shape by heat sealing, which has, A method for manufacturing a filter bag. [5] Before step 2, it further has step 3 of subjecting the non-woven fabric to calendering treatment, The method for manufacturing a filter bag according to [4]. [6] The temperature of the calendering treatment is 110 °C or higher, The method for manufacturing a filter bag according to [5].

Effect of the Invention

[0009] According to the present invention, it is possible to provide a filter bag that uses a material with a low environmental load, has excellent filtration performance, and excellent heat-sealing performance.

Brief Description of the Drawings

[0010]

Figure 1

Modes for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described (hereinafter, also referred to as "this embodiment"). Note that this embodiment is an exemplification for explaining the present invention, and the present invention is not limited only to this embodiment.

[0012] 1. Filter Bag The filter bag of the present embodiment includes a nonwoven fabric containing polylactic acid fibers, core-sheath polylactic acid fibers, and pulp fibers, and the content of the pulp fibers is 10% by mass or more and 30% by mass or less with respect to the total amount of the content of the polylactic acid fibers, the content of the core-sheath polylactic acid fibers, and the content of the pulp fibers. The nonwoven fabric contains polylactic acid fibers, core-sheath polylactic acid fibers, and pulp fibers, and may contain other components as necessary. Hereinafter, the specific configuration of the filter bag will be described, but the present invention is not particularly limited thereby.

[0013] 1.1. Polylactic acid fibers The polylactic acid fibers are fibers made of polylactic acid. The polylactic acid is not particularly limited, and for example, conventionally known ones can be used, commercially available products can be used, or it can be produced by a conventionally known synthesis method such as by ring-opening polymerization of lactide. In the present embodiment, unless otherwise specified, polylactic acid means poly-L-lactic acid which is a polymer of L-lactic acid.

[0014] When synthesizing polylactic acid, it is possible to adjust the physical properties by changing the degree of polymerization and the ratio of lactic acid monomers which are optical isomers. Although not particularly limited, for example, the melting point can be adjusted by changing the copolymerization ratio of D-form and L-form. Specifically, for example, when 1 mol% of D-form is copolymerized with L-form polylactic acid, the melting point is 170 ° C, when 3 mol% of D-form is copolymerized, the melting point is 150 ° C, when 7 mol% of D-form is copolymerized, the melting point is 130 ° C, and when 12 mol% of D-form is copolymerized, the melting point can be adjusted to 110 ° C, respectively. Hereinafter, the copolymer of L-lactic acid and D-lactic acid is also referred to as poly D,L-lactic acid.

[0015] The average fiber diameter of the polylactic acid fibers can generally be applied as long as the fibers have a fiber diameter that can be papermade from the viewpoints of dispersibility and operability when manufacturing a wet nonwoven fabric. Specifically, it is preferably 10 μm or more and 50 μm or less, more preferably 10 μm or more and 30 μm or less, and even more preferably 10 μm or more and 25 μm or less. Thereby, the effects according to the present invention can be achieved more effectively and surely.

[0016] Generally, the average fiber length of the polylactic acid fiber can be applied as long as it is a fiber with a fiber length that can be papermade from the viewpoints of dispersibility and operability when manufacturing a wet nonwoven fabric. Specifically, it is preferably 5 mm or more and 10 mm or less, and more preferably 5 mm or more and 8 mm or less. Thereby, the effects according to the present invention can be achieved more effectively and surely.

[0017] From the viewpoint of improving the balance between the filterability and the heat sealability, the content of the polylactic acid fiber is preferably 35% by mass or more and 65% by mass or less, more preferably 40% by mass or more and 60% by mass or less, and even more preferably 45% by mass or more and 60% by mass or less with respect to the total amount of the content of the polylactic acid fiber, the content of the core-sheath polylactic acid fiber, and the content of the pulp fiber.

[0018] 1.2. Core-sheath polylactic acid fiber The core-sheath polylactic acid fiber means a fiber in which one fiber has a structure composed of a core part made of polylactic acid and a sheath part. The core-sheath polylactic acid fiber of the present embodiment can improve the mixing property of polylactic acid and pulp fiber while maintaining the strength of the filter bag by using a resin that can be softened and melted at a temperature lower than that of the polylactic acid in the core part for the sheath part.

[0019] The resin used for the sheath part is not particularly limited as long as it is a resin having a softening point and a melting point lower than those of poly-L-lactic acid. For example, polybutylene succinate and poly-D,L-lactic acid having a melting point of 130 to 160°C can be used.

[0020] As the core-sheath polylactic acid fiber, conventionally known ones can be used, and commercially available products can be used, or it can be manufactured by synthesis.

[0021] The average fiber diameter of the core-sheath polylactic acid fiber can generally be applied as long as it is a fiber with a fiber diameter that can be papermade from the viewpoints of dispersibility and operability when manufacturing a wet nonwoven fabric. Specifically, it is preferably 10 μm or more and 50 μm or less, more preferably 20 μm or more and 50 μm or less, and even more preferably 25 μm or more and 50 μm or less. Thereby, the effects according to the present invention can be achieved more effectively and reliably.

[0022] The average fiber diameter of the polylactic acid fiber and the core-sheath polylactic acid fiber refers to the number average fiber diameter when the flat cross-sectional shape is converted into a perfect circle with the same area. The average fiber length refers to the number average fiber length. The average fiber diameter and the average fiber length are values calculated by an image analyzer from an image observed with an optical microscope. The same applies hereinafter.

[0023] The average fiber length of the core-sheath polylactic acid fiber can generally be applied as long as it is a fiber with a fiber length that can be papermade from the viewpoints of dispersibility and operability when manufacturing a wet nonwoven fabric. It is preferably 5 mm or more and 10 mm or less, and more preferably 5 mm or more and 8 mm or less. Thereby, the effects according to the present invention can be achieved more effectively and reliably.

[0024] From the viewpoint of improving the balance between filterability and heat sealability, the content of the core-sheath polylactic acid fiber is preferably 25% by mass or more and 40% by mass or less, more preferably 30% by mass or more and 40% by mass or less, and even more preferably 30% by mass or more and 35% by mass or less with respect to the total amount of the content of the polylactic acid fiber, the content of the core-sheath polylactic acid fiber, and the content of the pulp fiber.

[0025] 1.3. Pulp Fiber The pulp fiber is not particularly limited, and examples thereof include fibers derived from wood pulp and non-wood pulp. The pulp fiber derived from wood pulp is not particularly limited, and examples thereof include pulp fibers derived from coniferous trees such as the Pinaceae family and the Pine family, and pulp fibers derived from broad-leaved trees such as the Fagaceae family, the Betulaceae family, the Aceraceae family, the Salicaceae family, and the Eucalyptus of the Myrtaceae family. Although not particularly limited, examples of those derived from non-wood pulp include pulp fibers derived from rice straw, sugarcane, and reeds.

[0026] Also, the average fiber length of the pulp fibers is preferably 0.70 mm or more and 2.50 mm or less, more preferably 0.80 mm or more and 2.50 mm or less, and even more preferably 1.30 mm or more and 2.10 mm or less. Thereby, the effects of the present invention can be achieved more effectively and surely. The average fiber length of the pulp fibers can be measured as the length-weighted average fiber length, for example, in accordance with JIS P 8226-2:2011. The average fiber length of the pulp fibers can be adjusted according to the selection of the pulp type and the degree of beating treatment during raw material preparation.

[0027] The content of the pulp fibers is 10% by mass or more and 30% by mass or less, preferably 12.5% by mass or more and 20% by mass or less, and more preferably 15% by mass or more and 20% by mass or less, based on the total amount of the content of the polylactic acid fibers, the content of the core-sheath polylactic acid fibers, and the content of the pulp fibers. Being 10% by mass or more provides excellent strength and filterability, and being 30% by mass or less provides excellent heat sealability.

[0028] 1.4. Air permeability The non-woven fabric of the present embodiment preferably has an air permeability of 50 cc / cm 2 ·sec or more and 130 cc / cm 2 ·sec or less, more preferably 50 cc / (cm 2 ·sec) or more and 120 cc / (cm 2 ·sec) or less, and even more preferably 50 cc / (cm 2 ·sec) or more and 110 cc / (cm 2 ·sec) or less. When the air permeability is 50 cc / cm 2 ·sec or more and 130 cc / cm 2·By using a non-woven fabric of less than 1 sec, coffee with excellent flavor can be provided. As a method for adjusting the air permeability, there is no particular limitation, but for example, it can be adjusted by changing the pulp fiber content, beating degree, basis weight of the non-woven fabric, and density.

[0029] 1.5. Surface roughness For the non-woven fabric of this embodiment, the surface roughness (Sq) of at least one surface A of the non-woven fabric is preferably 10 μm or less, more preferably 8.5 μm or less, and even more preferably 7.5 μm or less. When the surface roughness is 10 μm or less, it tends to have excellent heat sealability. As a method for adjusting the surface roughness, there is no particular limitation, but for example, the surface roughness can be reduced by increasing the temperature of the heat roll and the calendar line pressure during the heat calendar treatment.

[0030] The surface roughness of the non-woven fabric of this embodiment was measured according to the following procedure. <Measuring device> Digital microscope "VHX6000" manufactured by Keyence Corporation <Observation of sample> When the non-woven fabric of this embodiment is heat-sealed, the surfaces where the non-woven fabrics come into contact and are heat-sealed were observed. The observation area was observed at a magnification such that it would be 9 mm 2 / 1 measurement. <Measurement of surface roughness> For the observed image, the surface roughness was determined according to the following procedure. (1) Create a 3D composite image in the "Depth composite & 3D" mode. (2) Measure the surface roughness of the obtained 3D composite image. (3) When measuring the surface roughness, the root mean square height Sq was determined under the conditions of "Gaussian" as the filter and 1 mm as the L-filter.

[0031] 1.6. Density The non-woven fabric of this embodiment preferably has a density of 0.30 g / cm 3 or more, and 0.36 g / cm 3It is more preferable that it is as described above. When the density is adjusted to 0.30 g / cm 3 or higher, when heat-sealing is performed, the heat and ultrasonic waves applied to the non-woven fabric are more effectively transmitted throughout the non-woven fabric, enabling good heat-sealing processing. The method for adjusting the density is not particularly limited. For example, by increasing the temperature of the heat roll and the calendar line pressure during heat calendar treatment, the density can be improved.

[0032] The non-woven fabric of this embodiment preferably has a basis weight of 15 g / m 2 or more and 40 g / m 2 or less, more preferably 20 g / m 2 or more and 37.5 g / m 2 or less, and most preferably 25 g / m 2 or more and 35 g / m 2 or less. This allows the effects of the present invention to be achieved more effectively and reliably. The basis weight can be adjusted by known methods applied during the production of the non-woven fabric in wet papermaking.

[0033] 2. Method for manufacturing a filter bag The method for manufacturing the filter bag of this embodiment includes Step 1 of producing a non-woven fabric containing polylactic acid fibers, core-sheath polylactic acid fibers, and pulp fibers by a wet method, and Step 2 of forming the non-woven fabric into a bag shape by heat-sealing. Additionally, other steps may be included as needed.

[0034] Step 1 is a step of producing a non-woven fabric containing polylactic acid fibers, core-sheath polylactic acid fibers, and pulp fibers by a wet method. Such Step 1 is not particularly limited, and for example, a conventionally known method can be used. Specifically, it can be produced by mixing polylactic acid fibers, core-sheath polylactic acid fibers, and pulp fibers in water, then draining them into a sheet shape, and further drying.

[0035] Step 2 is a step of forming the nonwoven fabric obtained in Step 1 into a bag shape by heat sealing. Such Step 2 is not particularly limited, and for example, a conventionally known method can be used. Specifically, heat sealing can be performed using a commercially available vertical pillow packaging machine. The temperature for heat sealing is not particularly limited, and for example, a temperature at which core-sheath polylactic acid fibers and the like can be melted may be used. Further, using an ultrasonic welder, polylactic acid fibers and core-sheath polylactic acid fibers, which are thermoplastic resins, can be melted by frictional heat generated by ultrasonic waves and subjected to a sealing process.

[0036] The method for manufacturing the filter bag of the present embodiment preferably further includes Step 3 of subjecting the nonwoven fabric to a calendar treatment before Step 2. Thereby, the strength and heat sealability tend to be improved. Further, the temperature of the calendar treatment is preferably 110°C or higher, and more preferably 110°C or higher and 120°C or lower. Thereby, the strength and heat sealability tend to be further improved.

Examples

[0037] Hereinafter, the molded interior material according to the present embodiment will be described more specifically using examples and comparative examples. However, the present invention is not limited by the following examples.

[0038] 1. Production of nonwoven fabric (Examples 1 to 12, Comparative Examples 1 to 2) <Example 1> First, a nonwoven fabric was produced by the wet method. Specifically, “Terramac PL01 1.7 dtx × 5 mm” manufactured by Unitika Ltd. as polylactic acid fibers, “Terramac 80 2.2 dtx × 5 mm” manufactured by Unitika Ltd. as core-sheath polylactic acid fibers, and commercially available NBKP (softwood bleached kraft pulp) were mixed so that the mass ratio was 50:30:20, and the fiber raw material was dispersed in water at a concentration of 0.1% by mass in water, and then wet papermaking was performed using an inclined wire type paper machine, dried at a dryer temperature of 140°C, and the basis weight was 35 g / m 2 of the nonwoven fabric for the reinforcing material was produced.

[0039] The nonwoven fabrics for filter bags of each example and each comparative example were produced under the same conditions as in Example 1, except that the content of polylactic acid fiber, the content of core-sheath polylactic acid fiber, the content of pulp fiber, and other conditions were changed as shown in Table 1.

[0040]

Table 1

[0041] In Table 1, "basis weight", "density", "surface roughness", and "air permeability" respectively mean the basis weight, density, surface roughness, and air permeability of the nonwoven fabric.

[0042] The details of each component shown in Table 1 are as follows. · Polylactic acid fiber: Manufactured by Unitika Ltd., "Terramac PL01 1.7 dtx", average fiber length 5 mm, average fiber diameter 15 μm · Core-sheath polylactic acid fiber: Manufactured by Unitika Ltd., "Terramac 80 2.2 dtx", average fiber length 5 mm, average fiber diameter 33 μm · Pulp fiber: NBKP (needle leaf tree-derived pulp fiber), average fiber length 2.0 mm, average fiber diameter 27 μm Also, the basis weight, density, air permeability, strength, surface roughness, and peel strength were measured by the following methods. <Basis weight> The basis weights of the nonwoven fabrics of the examples and comparative examples were measured according to JIS P8124:2011. <Density> The densities of the nonwoven fabrics of the examples and comparative examples were measured according to JIS P8118:2014. <Air permeability> The Frazier air permeability of the nonwoven fabrics of the examples and comparative examples was measured using an air permeability tester "KES-8" (manufactured by Kato Tech Co., Ltd.) according to JIS L1913:2010. <Strength> The specific tensile strengths in the longitudinal and transverse directions of the nonwoven fabrics of the examples and comparative examples were measured using a universal testing machine "Strograph E3-S" manufactured by Toyo Seiki Seisakusho Co., Ltd. according to JIS P8113:2006, and the geometric mean was obtained.

[0043] 2. Production and Evaluation of Filter Bags (1) Production of Filter Bags The non-woven fabrics of each example and each comparative example were subjected to bag-making processing using a packaging machine (ultrasonic sealing method) manufactured by Fushuang Industry Co., Ltd. (2) Evaluation of Filter Bags [Heat Sealability] Regarding the heat sealability, as shown in Fig. 1, for the three heat-sealed portions of the filter bag that were triple-sealed so that the width of the seal portion was 10 mm each, while ensuring the length required for the gripping margin, they were cut out on a strip with a width of 15 mm, and using a tensile testing machine, the load at the time when the heat-sealed portion broke was measured. The load measured at the time of breakage was divided by the width of the test piece of 15 mm to obtain the breaking strength, and the evaluation was carried out according to the following evaluation criteria. The results are shown in Table 1. Practically, those with "△" or above are usable. [Evaluation Criteria] ◎: The peel strength of the filter bag is 8.0 N / 15 mm or more. 〇: The peel strength of the filter bag is 6.0 N / 15 mm or more and less than 8.0 N / 15 mm. △: The peel strength of the filter bag is 5.5 N / 15 mm or more and less than 6.0 N / 15 mm. ×: The peel strength of the filter bag is less than 5.5 N / 15 mm. [Filtration Performance] 12 g of coffee powder (medium-ground regular coffee powder) was filled into the triple-sealed bag shown in Fig. 1, 200 cc of water at 90 °C was poured from the open part, and the time (filtration time) during which the coffee extracted from the bottom continued to flow continuously was measured. The filtration performance was evaluated according to the following evaluation criteria. The results are shown in Table 1. In the range where the flavor of the coffee is not impaired, it is "△" or above. [Evaluation Criteria] 〇: The filtration time is in the range of 55 seconds or more and 70 seconds or less. The flavor of the coffee is good. △: The filtration time is in the range of 50 seconds or more and 55 seconds or less. The extraction time is slightly early. ×: The filtration time is less than 50 seconds or exceeds 70 seconds. The coffee concentration is either too weak or too strong.

[0044] According to the comparison between Example 1 or 2 and Comparative Example 2, by including pulp fibers, the air permeability of the non-woven fabric can be adjusted to 50 cc / cm 2 ·sec or more and 130 cc / cm 2 ·sec, thereby providing a filter bag having appropriate filterability during coffee extraction. According to the comparison between Examples 1 to 3 and Comparative Examples 1 and 2, it can be seen that by containing 10% by mass or more and 30% by mass or less of pulp fibers, the heat sealability is improved. According to the comparison between Example 1 and Examples 5 to 7, as the density of the non-woven fabric increases, the surface roughness of the non-woven fabric decreases and the smoothness progresses. As a result, the adhesion between the heat-sealed surfaces is improved and the heat sealability is improved. At the same time, it was found that the strength of the entire non-woven fabric was improved. The mechanism by which the strength is improved is not particularly limited, but it is considered to be due to the improved binding property between the polylactic acid fibers of the non-woven fabric. According to the comparison between Example 1 and Examples 8 to 12, it was found that by increasing the temperature during the heat calendar treatment, a filter bag excellent in strength and heat sealability can be obtained.

Industrial Applicability

[0045] The present invention can be used as a filter bag for decocting coffee, black tea, green tea, barley tea, dashi, etc., or for extracting by pouring hot water or water, and thus has industrial applicability in that regard.

Claims

1. A nonwoven fabric including polylactic acid fibers, core-sheath polylactic acid fibers, and pulp fibers, The content of the pulp fibers is 10% by mass or more and 30% by mass or less based on the total amount of the content of the core-sheath polylactic acid fibers, the content of the polylactic acid fibers, and the content of the pulp fibers. Filter bag.

2. The nonwoven fabric has a breathability of 50 cc / cm ２ ・sec or more 130cc / cm ２ sec or less, The surface roughness (Sq) of at least one surface A of the nonwoven fabric is 10 μm or less.

2. The filter bag of claim 1.

3. The density of the nonwoven fabric is 0.36 g / cm ３ That's all.

2. The filter bag of claim 1.

4. A step 1 of producing a nonwoven fabric containing polylactic acid fibers, core-sheath polylactic acid fibers, and pulp fibers by a wet method; Step 2 of forming the nonwoven fabric into a bag shape by heat sealing. A method for manufacturing a filter bag.

5. The method further includes a step 3 of subjecting the nonwoven fabric to a calendar treatment before the step 2. A method for producing the filter bag according to claim 4.

6. The calendering temperature is 110° C. or higher. A method for producing the filter bag according to claim 5.

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