Filter material, method for manufacturing same, filter container, and enclosure

Abstract

An aspect of this filter material includes a stack composed of a first nonwoven fabric layer and a second nonwoven fabric layer. Fibers constituting the first nonwoven fabric layer have an average fiber diameter smaller than fibers constituting the second nonwoven fabric layer. The first nonwoven fabric layer and / or the second nonwoven fabric layer is composed of biodegradable fibers, and the density of the first nonwoven fabric layer is 0.85 g / cm3 or more.

Description

Filter material and method for manufacturing the same, as well as filter container and sealing body. Related applications

[0001] This application claims priority to Japanese Patent Application No. 2025-049442, filed on 25 March 2025, which is incorporated herein by reference as forming part of this application.

[0002] The present invention relates to a filter material having at least a portion of biodegradable fibers and composed of a specific nonwoven fabric layer, a method for producing the same, and a filter container and a encapsulated body using the same.

[0003] When extracting coffee, broth, or other liquids, there has been a growing preference in recent years for the use of filter media consisting of nonwoven fabric sheets containing the extracting material, such as coffee or dried bonito flakes. In recent years, from an environmental perspective, there has been a demand for the use of biodegradable materials, at least partially, in the nonwoven fabric sheets used in such filters.

[0004] For example, Patent Document 1 (Japanese Patent Publication No. 2016-168569) describes a polylactic acid resin fiber with a crystallinity of 9.0% or less and a fiber diameter of 15.0 μm or less, with a basis weight of 2.0 to 30.0 g / m². ２ A layer (M layer) formed from a melt-blown nonwoven fabric sheet, and fibers of polylactic acid resin with a crystallinity of 30.0 to 60.0% and a fiber diameter of 35.0 μm or less, with a basis weight of 5.0 to 30.0 g / m². ２ A multilayer extraction sheet is disclosed, having a layer (S layer) formed of spunbond nonwoven fabric.

[0005] Furthermore, Patent Document 2 (Japanese Unexamined Patent Publication No. 2011-157118) describes a food filter made of a biodegradable laminated nonwoven fabric sheet composed of long fibers and ultrafine fibers of a polylactic acid polymer, wherein the laminated nonwoven fabric sheet has a fiber diameter of 10 to 20 μm and a basis weight of 10 to 40 g / m². ２ A long-fiber nonwoven fabric sheet with a fiber diameter of 1 to 10 μm and a basis weight of 1 to 10 g / m². ２ At least two types of nonwoven fabric sheets made of ultrafine fibers are integrated by heat-sealing, the thickness of the laminated nonwoven fabric sheet is 0.02 to 0.50 mm, and the air permeability is 100 to 300 cc / cm². ２A food filter is disclosed, characterized in that it has a sec and a heat seal strength of 4N / 25mm or more.

[0006] Furthermore, Patent Document 3 (Japanese Patent Publication No. 2000-336570) describes a material made of a biodegradable thermoplastic polymer, having an average fiber diameter of 20 μm or less, and with an air permeability of 10 to 250 cm. ３ / cm ２ A coffee extraction sheet material is disclosed, characterized by being made of a melt-blown ultrafine fiber nonwoven fabric sheet having a water absorption rate of 5 seconds or less in water at a temperature of 60°C or higher.

[0007] Japanese Patent Publication No. 2016-168569, Japanese Patent Publication No. 2011-157118, Japanese Patent Publication No. 2000-336570

[0008] However, the sheets and filters described in Patent Documents 1 to 3 use biodegradable fibers formed from polylactic acid polymers as filter materials, and these biodegradable fibers are generally highly hydrophilic. Therefore, for example, when extracting a hydrophilic liquid from a encapsulated substance such as coffee grounds, the fiber diameter of the biodegradable fibers and the basis weight of the nonwoven fabric sheet are adjusted to control the extraction rate from the filter, so that the extraction rate of the hydrophilic liquid does not become too fast.

[0009] On the other hand, when distributing encapsulated products containing substances such as coffee grounds in such filter materials to the market, it has become clear that a problem exists where the physical properties of the filter material change during storage due to the encapsulated substance, possibly because biodegradable fibers are highly hydrophilic, making it impossible to maintain the extraction rate designed at the time of encapsulation. Therefore, there is a need for a filter material that can maintain the extraction rate designed at the time of encapsulation, even after being stored for a predetermined period.

[0010] Therefore, the object of the present invention is to provide a filter material that can maintain the filter properties designed at the time of sealing, even when the substance to be encapsulated is stored for a predetermined period of time after encapsulation.

[0011] That is, the present invention can be configured in the following aspects. [Aspect 1] A laminate composed of a first nonwoven fabric layer and a second nonwoven fabric layer is included, wherein fibers constituting the first nonwoven fabric layer have a smaller average fiber diameter than fibers constituting the second nonwoven fabric layer, at least one of the first nonwoven fabric layer and the second nonwoven fabric layer is composed of biodegradable fibers, and the density of the first nonwoven fabric layer is 0.85 g / cm ３ or more (for example, 0.85 to 2.00 g / cm ３ , preferably 0.90 to 1.50 g / cm ３ , more preferably 0.95 to 1.20 g / cm ３ ), which is a filter material. [Aspect 2] A laminate composed of a first nonwoven fabric layer and a second nonwoven fabric layer is included, wherein fibers constituting the first nonwoven fabric layer have a smaller average fiber diameter than fibers constituting the second nonwoven fabric layer, at least one of the first nonwoven fabric layer and the second nonwoven fabric layer is composed of biodegradable fibers, and a fiber occupied area on at least one surface of the first nonwoven fabric layer is 70.0% or more (for example, 70.0 to 95.0%, preferably 73.0 to 93.0%, more preferably 75.0 to 90.0%), which is a filter material. [Aspect 3] The filter material according to Aspect 1, wherein a fiber occupied area on at least one surface of the first nonwoven fabric layer is 70.0% or more (for example, 70.0 to 95.0%, preferably 73.0 to 93.0%, more preferably 75.0 to 90.0%), which is a filter material. [Aspect 4] The filter material according to any one of Aspects 1 to 3, wherein the crystallinity of fibers constituting the first nonwoven fabric layer is 30% or more (for example, 30 to 80%, preferably 32 to 70%, more preferably 35 to 60%), which is a filter material. [Aspect 5] The filter material according to any one of Aspects 1 to 4, wherein the thickness of the first nonwoven fabric layer is 0.1 to 12.0 μm (preferably 1.0 to 11.0 μm, more preferably 2.0 to 10.5 μm), which is a filter material. [Aspect 6] The filter material according to any one of Aspects 1 to 5, wherein the basis weight of the first nonwoven fabric layer is 1 to 14 g / m ２ (preferably 3 to 13 g / m ２ , more preferably 5 to 12 g / m２) A filter material. [Aspect 7] A filter material according to any one aspect of aspects 1 to 6, wherein the ratio of the thickness of the first nonwoven fabric layer to the thickness of the laminate is 2 to 15% (preferably 3 to 13%, more preferably 5 to 11%). [Aspect 8] A filter material according to any one aspect of aspects 1 to 7, wherein the first nonwoven fabric layer is made of meltblown nonwoven fabric. [Aspect 9] A filter material according to any one aspect of aspects 1 to 8, wherein the second nonwoven fabric layer is made of spunbond nonwoven fabric. [Aspect 10] A filter material according to any one aspect of aspects 1 to 9, for filtering oil-containing solids. [Aspect 11] A filter material according to any one aspect of aspects 1 to 10, wherein both the first nonwoven fabric layer and the second nonwoven fabric layer contain biodegradable fibers. [Aspect 12] A filter material according to aspect 11, wherein the biodegradable fibers contain polylactic acid fibers. [Aspect 13] A filter container comprising the filter material described in any one of aspects 1 to 12, wherein the first nonwoven fabric layer is arranged on the inside. [Aspect 14] An enclosure comprising the filter material described in any one of aspects 1 to 12 and a substance to be enclosed, wherein the substance to be enclosed is in contact with the first nonwoven fabric layer. [Aspect 15] A method for manufacturing a filter material including a laminate composed of a first nonwoven fabric layer and a second nonwoven fabric layer, comprising at least the steps of: preparing a first nonwoven fabric sheet and a second nonwoven fabric sheet; and integrating the first nonwoven fabric sheet and the second nonwoven fabric sheet to obtain a laminate composed of a first nonwoven fabric layer and a second nonwoven fabric layer, wherein the fibers constituting the first nonwoven fabric sheet have a smaller average fiber diameter than the fibers constituting the second nonwoven fabric sheet, at least one of the first nonwoven fabric sheet and the second nonwoven fabric sheet is composed of biodegradable fibers, and the first nonwoven fabric sheet is in a pressed state.[Aspect 16] A method for manufacturing a filter material according to the method described in Aspect 15, wherein the step of preparing the first nonwoven fabric sheet includes a step of obtaining the first nonwoven fabric sheet by press treatment. [Aspect 17] A method for manufacturing a filter material according to the method described in Aspect 15 or 16, wherein the first nonwoven fabric sheet is a press-treated meltblown nonwoven fabric.

[0012] Furthermore, any combination of at least two components disclosed in the claims and / or the specification and / or drawings is included in the present invention. In particular, any combination of two or more claims described in the claims is included in the present invention.

[0013] According to the present invention, even when the filter material is stored for a predetermined period after the substance to be encapsulated is sealed inside, it can maintain the filter properties designed at the time of encapsulation.

[0014] This invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustrative and explanatory purposes only and should not be used to define the scope of this invention. The scope of this invention is defined by the appended claims. This is an electron microscope image (500x magnification) of the surface (non-embossed portion) of the first nonwoven fabric layer in Example 1 of the present invention. This is an image processed from the electron microscope image of Figure 1A to calculate the fiber-occupied portion. This is an electron microscope image (500x magnification) of the surface of the first nonwoven fabric layer in Comparative Example 1. This is an image processed from the electron microscope image of Figure 2A to calculate the fiber-occupied portion. This is an electron microscope image (500x magnification) of the surface (non-embossed portion) of the first nonwoven fabric layer in Comparative Example 5. This is an image processed from the electron microscope image of Figure 3A to calculate the fiber-occupied portion.

[0015] [Method for Manufacturing Filter Material] One embodiment of the method for manufacturing a filter material of the present invention is a method for manufacturing a filter material including a laminate composed of a first nonwoven fabric layer and a second nonwoven fabric layer, comprising at least the steps of: preparing a first nonwoven fabric sheet and a second nonwoven fabric sheet; and integrating the first nonwoven fabric sheet and the second nonwoven fabric sheet to obtain a laminate composed of a first nonwoven fabric layer and a second nonwoven fabric layer. Furthermore, at least one of the first nonwoven fabric sheet and the second nonwoven fabric sheet is composed of biodegradable fibers. Preferably, at least the first nonwoven fabric sheet may be composed of biodegradable fibers, and more preferably, both the first nonwoven fabric sheet and the second nonwoven fabric sheet may be composed of biodegradable fibers.

[0016] (Biodegradable Fibers) Biodegradable fibers are not particularly limited as long as they are biodegradable, but preferred biodegradable fibers include cellulose fibers, polyvinyl alcohol fibers, and aliphatic polyester fibers. Cellulose fibers include natural fibers (e.g., cotton, hemp, various pulps, etc.), regenerated fibers (e.g., rayon, polynosic, cupro, lyocell, etc.), and semi-synthetic fibers (e.g., cellulose acetate, etc.). Polyvinyl alcohol fibers include fibers formed from polyvinyl alcohol, ethylene-vinyl alcohol copolymers, etc. Furthermore, examples of aliphatic polyester fibers include fibers formed from polylactic acid, polyhydroxyalkanoates, polyglycolic acid, polyethylene succinate, polybutylene succinate, polyethylene terephthalate succinate copolymer, polyethylene terephthalate adipate copolymer, polybutylene succinate adipate copolymer, polybutylene terephthalate adipate copolymer, poly-3-hydroxybutyrate-3-hydroxyvalate copolymer, polycaprolactone, modified forms thereof, or blends thereof. These biodegradable fibers may be used individually or in combination of two or more types. Among these biodegradable fibers, polylactic acid fibers and polybutylene succinate fibers are preferred.

[0017] As long as the biodegradable fiber is biodegradable, there are no particular limitations on its physical properties. For example, the viscosity of the resin constituting the fiber may be 5 to 600 g / 10 min as the melt flow rate (MFR) under conditions of a temperature of 190°C and a load of 2.16 kgf, and more preferably 25 to 300 g / 10 min. In this specification, the MFR can be measured by referring to JIS K 7210-1:2014 and is the value measured by the method described in the examples below.

[0018] Furthermore, the first nonwoven fabric layer and the second nonwoven fabric layer may contain non-biodegradable fibers, and such fibers include synthetic fibers spun from fiber-forming resins using known techniques. The fiber-forming resin is a polyolefin resin (polyethylene, polypropylene, etc.). ２－４ Examples of fiber-forming resins include olefin resins, polyvinyl chloride resins (polyvinyl chloride, polyvinylidene chloride, etc.), general-purpose polyester resins (polyalkylene arylate resins such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), polyamide resins (aliphatic polyamide resins such as polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 610, polyamide 612, etc.), polyurethane resins (urethane polymers obtained by the reaction of polyol components such as polyether polyol and polyester polyol with polyisocyanate components), and acrylic resins (polyacrylic acid, polymethacrylic acid, polyacrylic acid ester, polymethacrylic acid ester, etc.). These fiber-forming resins can be used individually or in combination of two or more. Of these, from the viewpoint of forming a spin-bonded nonwoven fabric sheet, polyolefin resins, polyester resins, polyamide resins, and polyurethane resins are preferred as fiber-forming resins, and polypropylene resins are particularly preferred.

[0019] These fibers may contain other conventional additives within a range that does not impair the object of the present invention, for example, stabilizers (heat stabilizers such as copper compounds, ultraviolet absorbers, light stabilizers, antioxidants, etc.), antibacterial agents, deodorants, fragrances, colorants (dyes and pigments, etc.), fillers, flame retardants, chargeability improvers (hindered amines, etc.), antistatic agents, conductive agents, plasticizers, lubricants, crystallization rate retarders, and the like. These additives can be used alone or in combination of two or more. The content of these additives can be selected according to their types, for example, it is 0.01 to 30 parts by mass, preferably 0.1 to 20 parts by mass, more preferably 0.3 to 10 parts by mass (particularly 0.5 to 5 parts by mass) per 100 parts by mass of the polymer component forming the fibers.

[0020] (Step of Preparing First and Second Nonwoven Fabric Sheets) The structures of the first nonwoven fabric sheet and the second nonwoven fabric sheet are not particularly limited as long as the object of the present invention can be achieved. They may be wet-laid nonwoven fabrics or dry-laid nonwoven fabrics, but directly spun-bonded nonwoven fabrics are preferred from the viewpoint of reducing fiber falling off. Examples of directly spun-bonded nonwoven fabrics include spunbonded nonwoven fabrics and meltblown nonwoven fabrics.

[0021] A meltblown nonwoven fabric is formed such that a polymer discharged from nozzles of a spinneret is blown off by a jet stream of high-temperature gas, is fined into fibers, and is deposited on a support such as a collection net. The polymer discharged from the spinneret may have a discharge amount per single hole of, for example, 0.05 to 1.0 g / hole·min, preferably 0.1 to 0.8 g / hole·min, more preferably about 0.2 to 0.6 g / hole·min. In addition, the diameter of a single hole may be, for example, 100 to 800 µm, preferably 150 to 700 µm, more preferably 200 to 600 µm.

[0022] A spunbonded nonwoven fabric is formed as follows: a polymer discharged from nozzles of a spinneret is cooled in a cold air chamber, and is drawn at a high speed by an air jet or drawn by a roll, then collected as a fiber web on a net conveyor, and thereafter fibers are pressed against each other by a heat roll to form the nonwoven fabric.

[0023] Since the first nonwoven fabric sheet is formed of fibers having an average fiber diameter smaller than that of the fibers forming the second nonwoven fabric sheet, it may preferably be a melt-blown nonwoven fabric. Further, since the second nonwoven fabric sheet is formed of fibers having an average fiber diameter larger than that of the fibers forming the first nonwoven fabric sheet, it may preferably be a spunbonded nonwoven fabric.

[0024] The step of preparing the first nonwoven fabric sheet may be a step of preparing an already pressed nonwoven fabric sheet as the first nonwoven fabric sheet. Alternatively, the step of preparing the first nonwoven fabric sheet may be a step of pressing an unpressed nonwoven fabric to obtain the first nonwoven fabric sheet.

[0025] The method and conditions of the pressing treatment can be appropriately set according to the structure of the nonwoven fabric sheet before pressing, and for example, the pressing treatment is performed by calendering or the like.

[0026] When calendering is performed, the pressure can be appropriately set according to the type of the nonwoven fabric sheet. For example, the linear pressure between the rubber roll and the metal roll may be 30 to 60 kg / cm, preferably 30 to 50 kg / cm, more preferably 35 to 50 kg / cm.

[0027] The temperature during calendering can be appropriately set according to the type of the nonwoven fabric sheet. For example, when T is defined as the lowest melting point or glass transition temperature of the fibers constituting the nonwoven fabric sheet, the temperature may be T-90°C to T-20°C, and preferably T-80°C to T-30°C. Here, when the resin forming the fibers is a crystalline resin, T can be based on the melting point, and when the resin is an amorphous resin, T can be based on the glass transition temperature. In the present specification, the melting point and the glass transition temperature are values measured by differential scanning calorimetry (DSC) in accordance with JIS K 7121:2012.

[0028] (Integration Process) In the process of integrating the first nonwoven fabric sheet and the second nonwoven fabric sheet, the first nonwoven fabric sheet and the second nonwoven fabric sheet are overlapped and integrated. For example, when the first nonwoven fabric sheet and the second nonwoven fabric sheet are integrated, it is preferable that the first nonwoven fabric sheet and the second nonwoven fabric sheet are integrated in such a state that at least a portion of them are not directly fused together.

[0029] The process of integrating the first nonwoven fabric sheet and the second nonwoven fabric sheet can be carried out by known methods, but from the viewpoint of adhesive-free lamination and integration, it is preferable to fuse and integrate the two by embossing, ultrasonic treatment, or the like.

[0030] In the embossing process, a laminate can be obtained by sandwiching a stack of sheets between a pair of embossing rolls, or a combination of embossing rolls and flat rolls, and then heat-pressing the embossed protrusions to fuse the first nonwoven fabric sheet and the second nonwoven fabric sheet together.

[0031] Furthermore, in ultrasonic processing, the overlapping sheets are sandwiched between an ultrasonic oscillator and an embossing roll, and the embossed protrusions are pressed together to fuse the first nonwoven fabric sheet and the second nonwoven fabric sheet together and obtain a laminate.

[0032] From the viewpoint of maintaining the high-density structure of the first nonwoven fabric layer, it is preferable that the crimping surfaces of the embossed protrusions are appropriately separated. For example, the average separation distance between the embossed crimping surfaces may be, for example, 0.5 to 4.0 mm, preferably 0.8 to 3.5 mm, and more preferably 1.0 to 3.0 mm. Here, the separation distance refers to the distance between the crimping surfaces of the highest parts of the embossed roll surface for each pattern of the embossed roll that is located on a straight line arbitrarily selected in the machine direction (MD) of the first nonwoven fabric sheet, and the average separation distance refers to the average separation distance between the embossed crimping surfaces in a continuous pattern of embossed rolls.

[0033] In filter materials, from the viewpoint of ensuring voids, it is preferable that voids and bonded portions (especially fused portions when embossing or ultrasonic treatment is performed) alternate in the laminate of the first nonwoven fabric layer and the second nonwoven fabric layer. The ratio of the embossed and bonded surface to the entire surface of the filter material may be, for example, 3 to 30%, preferably 5 to 25%, and more preferably 10 to 20%.

[0034] [Filter Material] One embodiment of the filter material of the present invention includes a laminate composed of a first nonwoven fabric layer and a second nonwoven fabric layer, wherein the fibers constituting the first nonwoven fabric layer have a smaller average fiber diameter than the fibers constituting the second nonwoven fabric layer, at least one of the first nonwoven fabric layer and the second nonwoven fabric layer is composed of biodegradable fibers, and the density of the first nonwoven fabric layer is 0.85 g / cm³. ３ That concludes the description of the filter material.

[0035] The density of the first nonwoven fabric layer is preferably 0.90 g / cm³. ３ More preferably 0.95 g / cm³ ３ The above is also acceptable. By increasing the density of the first nonwoven fabric layer, it is possible to suppress changes in the extraction rate from the encapsulated substance caused by changes in the physical properties of the filter material after encapsulation. The upper limit of the density of the first nonwoven fabric layer is not particularly limited as long as it does not hinder release, but for example, 2.00 g / cm³ ３ It may be less than 1.50 g / cm³, preferably 1.50 g / cm³. ３ More preferably, 1.20 g / cm³ ３ The following may also apply. Here, the density is the value measured by the method described in the examples below.

[0036] Another embodiment of the filter material of the present invention includes a laminate composed of a first nonwoven fabric layer and a second nonwoven fabric layer, wherein the fibers constituting the first nonwoven fabric layer have a smaller average fiber diameter than the fibers constituting the second nonwoven fabric layer, at least one of the first nonwoven fabric layer and the second nonwoven fabric layer is composed of biodegradable fibers, and the fiber area on at least one surface of the first nonwoven fabric layer is 70.0% or more.

[0037] The fiber occupancy area on at least one surface of the first nonwoven fabric layer is preferably 73.0% or more, more preferably 75.0% or more. The upper limit of the fiber occupancy area of ​​the first nonwoven fabric layer is not particularly limited as long as it does not impede release, but may be, for example, 95.0% or less, preferably 93.0% or less, and more preferably 90.0% or less. Here, the fiber occupancy area is a value measured by the method described in the examples later.

[0038] The size of the fiber-occupied area indicates the proportion of fibers present on the surface of the first nonwoven fabric layer; the larger the fiber-occupied area, the denser the fibers are. When fibers are densely packed, the accumulated fibers can obstruct the passage of liquid through the first nonwoven fabric layer, thereby slowing down the liquid extraction rate.

[0039] When fibers are densely packed together and there is little fusion between the fibers, the number of entry points through which the liquid passes through the first nonwoven fabric layer can be increased, which can improve the controllability of the liquid extraction rate.

[0040] In the filter material of the above embodiment, the density of the first nonwoven fabric layer is within a specific range, and, similar to the filter material of the other embodiment, the fiber occupied area on at least one surface of the first nonwoven fabric layer is within a specific range.

[0041] The degree of crystallinity of the fibers constituting the first nonwoven fabric layer may be, for example, 30% or more, preferably 32% or more, and more preferably 35% or more. Increasing the degree of crystallinity of the fibers constituting the first nonwoven fabric layer makes it less likely to shrink when heated and less likely to wrinkle. For example, the shape of the filter material can be maintained during the pressing process for forming the first nonwoven fabric sheet, the lamination and integration process with the second nonwoven fabric sheet, and the heat sealing process when forming it into a drip bag shape, thereby improving the handling of the filter material. The upper limit of the degree of crystallinity of the fibers constituting the first nonwoven fabric layer is not particularly limited, but may be, for example, 80% or less, preferably 70% or less, and more preferably 60% or less. The degree of crystallinity of the fibers can be adjusted according to the manufacturing conditions of the nonwoven fabric, the type of resin and melt viscosity, etc. Here, the degree of crystallinity can be calculated as the ratio of the heat of fusion ΔHm at the crystal melting endothermic peak measured by differential scanning calorimetry (DSC) to the heat of fusion of the resin constituting the fiber, and is a value measured by the method described in the examples below.

[0042] The average fiber diameter of the fibers constituting the first nonwoven fabric layer may be, for example, 10 μm or less, preferably 8 μm or less, and more preferably 7 μm or less, from the standpoint of controlling the extraction rate and the like. The lower limit of the average fiber diameter of the fibers constituting the first nonwoven fabric layer is not particularly limited, but may be, for example, 1 μm or more. Here, the average fiber diameter is a value measured by the method described in the examples later.

[0043] The thickness of the first nonwoven fabric layer may be, for example, 0.1 to 12.0 μm, preferably 1.0 to 11.0 μm, and more preferably 2.0 to 10.5 μm, from the standpoint of controlling the extraction rate and the like. Here, the thickness is a value measured by the method described in the examples below.

[0044] The basis weight of the first nonwoven fabric layer is, for example, 1 to 14 g / m², in order to control the extraction rate and other factors. ２ It may be, preferably 3 to 13 g / m² ２ More preferably 5 to 12 g / m ２This may also be the case. Here, the basis value is the value measured by the method described in the embodiment below.

[0045] The porosity of the first nonwoven fabric layer may be, for example, 5 to 35%, preferably 10 to 30%, and more preferably 13 to 28%, from the standpoint of controlling the extraction rate and the like. Here, the porosity is a value measured by the method described in the examples later.

[0046] The average fiber diameter of the fibers constituting the second nonwoven layer is not particularly limited as long as it is larger than the average fiber diameter of the fibers constituting the first nonwoven layer. For example, it may be 1.5 to 10 times, more preferably 3 to 9 times, and even more preferably 4 to 8 times, the average fiber diameter of the fibers constituting the first nonwoven layer. For example, the average fiber diameter of the fibers constituting the second nonwoven layer may be, for example, 10 to 30 μm, preferably 12 to 28 μm, and more preferably 15 to 25 μm.

[0047] The degree of crystallinity of the fibers constituting the second nonwoven layer is not particularly limited and may be, for example, 30% to 80%. It is more preferable that the absolute value of the numerical difference between the degree of crystallinity of the fibers constituting the second nonwoven layer and the degree of crystallinity of the fibers constituting the first nonwoven layer is small, as this reduces the difference in shrinkage during the lamination and integration process. For example, the absolute value of the numerical difference between the degree of crystallinity of the fibers constituting the second nonwoven layer and the degree of crystallinity of the fibers constituting the first nonwoven layer is preferably 0.1 to 20%, more preferably 1.0 to 15%, and even more preferably 1.0 to 10%.

[0048] The thickness of the second nonwoven fabric layer may be set in relation to the first nonwoven fabric layer, and from the viewpoint of achieving both ease of handling and extraction of the filter material, it may be, for example, 5 to 20 times, more preferably 6 to 18 times, and even more preferably 7 to 15 times, the thickness of the first nonwoven fabric layer.

[0049] The basis weight of the second nonwoven fabric layer is, for example, 5 to 25 g / m², from the standpoint of ease of handling. ２ It may be, preferably 7 to 23 g / m² ２ More preferably 10 to 20 g / m ２ That's fine.

[0050] The density of the second nonwoven fabric layer is set at 0.20 g / cm³ from the viewpoint of suppressing clogging by the nonwoven fabric sheet. ３ It may be less than 0.18 g / cm³, preferably 0.18 g / cm³. ３ More preferably, 0.15 g / cm³ ３ The following is also acceptable. The lower limit of the density of the second nonwoven fabric layer is not particularly limited as long as it does not excessively suppress release properties, but for example, 0.05 g / cm³ ３ That's fine too.

[0051] The air permeability of the laminate composed of the first nonwoven fabric layer and the second nonwoven fabric layer is, for example, 5 to 50 cc / cm². ２ It may be per second, preferably 7 to 40 cc / cm³. ２ / second, more preferably 10-35 cc / cm² ２ / second, more preferably 13 to 32 cc / cm³ ２ It may be per second. Here, the air permeability is a value measured by the method described in the examples below.

[0052] The thickness of the laminate composed of the first nonwoven fabric layer and the second nonwoven fabric layer may be, for example, 50 to 200 μm, preferably 90 to 180 μm, and more preferably 110 to 170 μm, from the viewpoint of handling.

[0053] Furthermore, the ratio of the thickness of the first nonwoven fabric layer to the thickness of the laminate may be, for example, 2 to 15%, preferably 3 to 13%, and more preferably 5 to 11%.

[0054] (Filter containers and enclosed bodies) Filter material can be used in filter containers. For example, filter material of a desired size can be formed into a bag or the like by known or conventional methods and used as a filter container.

[0055] Furthermore, it is also possible to contain the substance to be encapsulated in a filter container, seal it, and use it as an encapsulated body containing the substance inside the filter container.

[0056] The arrangement of the nonwoven fabric layers in the filter container can be appropriately selected depending on the application. For example, the filter material may be arranged so that hydrophilic liquid flows from the first nonwoven fabric layer towards the second nonwoven fabric layer, or so that hydrophilic liquid flows from the second nonwoven fabric layer towards the first nonwoven fabric layer. From the viewpoint of controlling the outflow of hydrophilic liquid, it is preferable to arrange the filter material so that hydrophilic liquid flows from the first nonwoven fabric layer towards the second nonwoven fabric layer. In this case, for example, when the substance to be sealed is sealed inside the filter container, it is preferable that the filter container has the first nonwoven fabric layer inside the second nonwoven fabric layer.

[0057] Furthermore, the first nonwoven fabric layer may be in contact with the encapsulated substance, or the second nonwoven fabric layer may be in contact with it. From the viewpoint of controlling the outflow of hydrophilic liquids, it is preferable that the first nonwoven fabric layer is in contact with the encapsulated substance. In this case, the extraction rate of the extracted substance from the encapsulated substance can be slowed down by the first nonwoven fabric layer.

[0058] When manufacturing filter containers and encapsulated bodies, the filter material may be bonded using adhesives, but from the viewpoint of being adhesive-free, it may also be bonded by sewing, heat fusion, high-frequency bonding, or ultrasonic bonding.

[0059] The filter container and the enclosed body may consist of a filter material and, if necessary, other components. These other components may include a frame for supporting the filter container and the enclosed body, and a gripping portion for the filter container and the enclosed body.

[0060] The encapsulated substance may be a variety of solids depending on its intended use. Examples include food products such as coffee grounds, tea leaves, and broth powders (dried bonito flakes powder, dried sardine powder), as well as pharmaceuticals such as herbal medicines and sustained-release drugs. For example, the encapsulated substance may also be an oil-containing solid (e.g., coffee grounds, broth powders, etc.).

[0061] In an encapsulated body, it is preferable from the viewpoint of controlling release if the first nonwoven fabric layer is in contact with the encapsulated substance. In particular, when the encapsulated substance is an oil-containing solid, the encapsulated body containing the oil-containing solid generally accumulates oil from the oil-containing solid on the filter fiber surface during storage, resulting in the fiber surface being coated with oil. When an oil film is present on the fiber surface, if an extract is released from the encapsulated body using a water-soluble medium, the liquid containing the extract flows quickly along the oil film, making it difficult to slow down the extraction rate of the oil-containing solid in the encapsulated body.

[0062] On the other hand, if the density of the first nonwoven fabric layer is controlled, even if an oil film is formed on the surface of the first nonwoven fabric layer, the high-density structure can slow down the extraction rate of the liquid containing the extract, and as a result, the release concentration of the extract can be increased.

[0063] For example, if the enclosed substance is coffee grounds, the coffee extraction rate can be slowed down, allowing for a higher concentration of coffee extract, resulting in a richer, more flavorful coffee.

[0064] Furthermore, since the filter material is composed of a biodegradable polymer, it can be implanted in the body with a drug encapsulated inside. In this case, the encapsulated substance can be slowly released within the body using bodily fluids. Moreover, if the bioabsorbable biodegradable polymer is used, the filter material can be broken down and absorbed within the body after the encapsulated substance has been released, without the need for surgical removal.

[0065] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by these examples. In the following examples and comparative examples, various physical properties were measured by the methods described below.

[0066] [Average Fiber Diameter] The surface of the test specimen was photographed with a scanning electron microscope (SEM) (magnification 1000x), and the diameter of 100 arbitrary fibers in the photograph was measured for each of the first and second nonwoven fabric layers. The average value of these measurements was defined as the average fiber diameter. In cases where there was a bias in the fiber diameter of a single fiber, the fiber diameter of that fiber was defined as the average of the diameter at the point with the largest diameter and the diameter at the point with the smallest diameter.

[0067] [Resin Viscosity] Using a melt flow rate (MFR) measuring device (L244, manufactured by Takara Kogyo Co., Ltd.), dried resin with a water content of less than 200 ppm was filled into a cylinder heated to 190°C and melted. A shaft with a load of 2.16 kgf was inserted into the cylinder to extrude the molten resin. The time required for the shaft to drop 25 mm was measured, and the MFR (g / 10 min) was calculated.

[0068] [Crystallization] The first and second nonwoven fabric layers were peeled from the laminate, and the crystallinity of the fibers constituting each layer was measured using the following procedure. In accordance with JIS K 7121:2012, a Mettler differential scanning calorimetry system (DSC-20) was used to measure the highest melting peak when 10 mg of fiber samples taken from each nonwoven fabric layer were heated at a rate of 20°C / min under nitrogen. The endothermic peak of crystallization was measured. The heat of fusion ΔHm (J / g) at the above endothermic peak was measured, and the degree of crystallinity (%) was calculated from the ratio to the heat of fusion of polylactic acid at perfect crystallization, which is 91.0 J / g, using the following formula: Crystallinity (%) = ΔHm (J / g) / 91.0 (J / g) × 100 Note that the heat of fusion of resins other than polylactic acid at perfect crystallization can also be used for calculation.

[0069] [Thickness of the First and Second Nonwoven Fabric Layers] The test specimen was cut with a sharp razor in a direction perpendicular to the fiber flow direction (or MD) of the test specimen, and the cross-section was observed with a scanning electron microscope (SEM) to measure the distance between the front and back surfaces of the first nonwoven fabric layer. Measurements were taken at 10 equally spaced points, and the average value of the 10 points was taken as the thickness of the first nonwoven fabric layer. If there were parts in the filter material where the shape of the first nonwoven fabric layer was clearly deformed due to post-processing such as thermal embossing, such deformed parts were avoided during measurement. The second nonwoven fabric layer was calculated in the same manner.

[0070] [Basis weight of the first and second nonwoven fabric layers] Measure the area and weight of the first nonwoven fabric sheet, and calculate the weight per square meter. ２ Convert to weight per unit, the basis weight (g / m²) of the first nonwoven fabric layer. ２ The calculation was performed as follows. The same calculation was performed for the second nonwoven fabric layer. When measuring using a laminate, the first nonwoven fabric layer and the second nonwoven fabric layer can be separated and measured.

[0071] [Density of the first and second nonwoven fabric layers] The density (g / cm³) of the first nonwoven fabric layer measured above is obtained by dividing its basis weight by its thickness. ３ The following was calculated: The same calculation was performed for the second nonwoven fabric layer.

[0072] [Void Ratio of the First Nonwoven Layer] The void ratio (%) was calculated from the density (bulk density) (ρ1) of the first nonwoven layer and the density (ρr) of the fibers (resin) constituting the first nonwoven layer using the following formula. Note that the density of the fibers can be measured in accordance with the density gradient tube method of JIS L 1015:2010 8.14.2. Void ratio (%) = (1 - ρ1 / ρr) × 100

[0073] [Fiber Occupied Area] The surface of the first nonwoven fabric layer of the test specimen, in areas without heat bonding due to embossing, was photographed at 500x magnification using a scanning electron microscope (SEM). The images were imported into a digital microscope DSX1000 (OLYMPUS), and binarized using the basic application software DSX10-BSW with a threshold of 128. The image was then quantified for each pixel. In terms of brightness value, pixels with a brightness value of 0 were determined to be non-fiber occupied areas, and pixels with a brightness value of 1 were determined to be fiber occupied areas. The percentage of fiber occupied area was calculated using the following formula. Measurements were taken at 10 locations, and the average value was used. Percentage of fiber occupied area (%) = (Number of pixels in fiber occupied area / Total number of pixels) × 100

[0074] [Basis weight of laminate] Measure the area and weight of a sheet-like test specimen, and use the weight as the basis for the area per square meter. ２ Convert to weight per unit area, basis weight (g / m²) ２ ) was calculated as follows.

[0075] [Thickness of the laminate] The thickness was measured by clamping a test specimen with a load of 20 gf applied to a pressure bar with a diameter of 16 mmΦ.

[0076] [Density of the laminate] The density (g / cm³) can be calculated by dividing the basis weight of the test specimen measured above by its thickness. ３ ) was calculated.

[0077] [Air permeability of laminate (cc / cm²)] ２ ( / second) In accordance with JIS L 1096:2010, 8.26.1 (Method A: Fragile method), three sample pieces were used, and for each sample piece, an air permeability meter (TEXTEST (Switzerland): FX3300) was used, with a measurement area of ​​38 cm². ２ The air permeability was measured under a measurement pressure of 125 Pa, and the average value of the air permeability obtained for each of the three layers was taken as the air permeability of the laminate.

[0078] [Extraction Speed] <Extraction Speed ​​Before Storage> Two cylinders with an inner diameter of 5 cm were prepared. A 10 cm diameter disc with a 6 cm diameter opening in the center was attached to one end of each cylinder. These cylinders were placed one above the other, with the discs facing each other, and a 10 cm square test piece was placed between the discs, and both sides were secured with two clips. Then, 5 g of ground coffee beans (coffee powder) was placed into the upper cylinder. Boiling water was poured in, and the time it took for 200 cc to pass through the top of the cylinder was measured. The time it took for 200 cc to pass through was defined as the extraction speed before storage.

[0079] <Extraction rate after storage> 5g of coffee grounds was wrapped around a 10cm square test piece so that the first nonwoven fabric layer of the test piece was in direct contact with it. This was then placed in a polyethylene bag, sealed with tape, and left to stand for 5 days under conditions of 70°C and 50% humidity. After that, the test piece was removed from the bag, the coffee grounds were brushed off, and the extraction rate was measured in the same manner as before storage.

[0080] [Wrinkle Evaluation] The appearance of the laminate after laminating the first nonwoven fabric layer and the second nonwoven fabric layer was evaluated according to the following criteria: A: Almost no wrinkles B: Slight wrinkles at the edges C: Wrinkles also present in the center of the sheet When a filter for extracting beverages is manufactured using a laminate with evaluations A and B, it is possible to achieve excellent quality with superior dimensional stability and no opening misalignment or fabric distortion.

[0081] [Example 1] Using a meltblown nonwoven fabric manufacturing apparatus, polylactic acid resin (Luminy® L130; MFR = 8.1 g / 10 min) was spun at a spinning temperature of 280°C with a single-hole discharge rate of 0.2 g / min and a single-hole diameter of 300 μm. The resulting material was then scattered onto a conveyor located at a collection distance of 13 cm by applying hot air at a temperature of 290°C and collected as an ultrafine fiber web (basis weight: approximately 10 g / m²). ２A fiber with an average fiber diameter of 2.49 μm was obtained. This ultrafine fiber web was calendered using a rubber roll and a metal flat roll, with the metal flat roll heated to 100°C and subjected to a linear pressure of 40 kg / cm to obtain a first nonwoven fabric sheet. The obtained first nonwoven fabric sheet and a spunbond nonwoven fabric mainly composed of polylactic acid (Asahi Kasei EcoRise S05015; average fiber diameter 16.1 μm) were layered and heat-pressed by thermal embossing using an embossing roll and a flat roll (average separation distance in MD: 2.7 mm; pressing area: 15%) to obtain a laminated composite filter material.

[0082] Figures 1A and 1B show an electron microscope image of the surface (non-embossed surface) of the first nonwoven fabric layer (Figure 1A) and a processed image for calculating its fiber area (Figure 1B). As shown in Figures 1A and 1B, the fiber area was 80.9% because the fibers constituting the first nonwoven fabric layer were densely packed together.

[0083] [Example 2] In the production of the first nonwoven sheet, a laminated composite filter material was obtained in the same manner as in Example 1, except that the collection distance during melt-blown spinning was set to 20 cm.

[0084] [Example 3] A laminated composite filter material was obtained in the same manner as in Example 1, except that the resin used in the production of the first nonwoven fabric sheet was changed to polylactic acid resin (Luminy® L-105; MFR = 23.7 g / 10 min).

[0085] [Example 4] A laminated composite filter material was obtained in the same manner as in Example 3, except that the spinning temperature during melt-blown spinning was changed to 300°C and the hot air temperature was changed to 310°C in the production of the first nonwoven sheet.

[0086] [Example 5] A laminated composite filter material was obtained in the same manner as in Example 3, except that the metal flat roll was calendered at 115°C in the production of the first nonwoven sheet.

[0087] [Comparative Example 1] The ultrafine fiber web obtained in Example 1 and a spunbond nonwoven fabric mainly composed of polylactic acid (Asahi Kasei EcoRise S05015; average fiber diameter 16.1 μm) were simply layered together, and the two were heat-pressed together by thermal embossing while sandwiched between an embossing roll and a flat roll. Furthermore, a laminated composite filter material was obtained by calendering using a rubber roll and a metal flat roll, with the metal flat roll heated to 100°C and sandwiched under a linear pressure of 40 kg / cm.

[0088] Figures 2A and 2B show electron microscope images of the surface of the first nonwoven fabric layer (Figure 2A) and processed images for calculating the fiber area (Figure 2B). As shown in Figures 2A and 2B, the fibers constituting the first nonwoven fabric layer were not sufficiently accumulated, and the fiber area was 58.9%.

[0089] [Comparative Example 2] Using a meltblown nonwoven fabric manufacturing apparatus, polylactic acid resin (Luminy® L130; MFR = 8.1 g / 10 min) was spun at a spinning temperature of 280°C with a single-hole discharge rate of 0.2 g / min / hole (single-hole diameter: 300 μm). Hot air at 290°C was applied, and the spun resin was scattered onto a conveyor lined with polylactic acid-based spunbond nonwoven fabric (Asahi Kasei EcoRise S05015; average fiber diameter 16.1 μm) at a collection distance of 13 cm to collect the material and obtain a laminated sheet (average fiber diameter of ultrafine fibers is 2.60 μm). The obtained laminated sheet was then calendered using a rubber roll and a metal flat roll, with the metal flat roll heated to 100°C and clamped under a linear pressure of 40 kg / cm to obtain a laminated composite filter material.

[0090] [Comparative Example 3] The composite filter material obtained in Comparative Example 2 was further sandwiched between an embossing roll and a flat roll and heat-pressed by thermal embossing.

[0091] [Comparative Example 4] Using a meltblown nonwoven fabric manufacturing apparatus, polylactic acid resin (Luminy® L130; MFR = 8.1 g / 10 min) was spun at a spinning temperature of 280°C, and hot air at a temperature of 290°C was applied to scatter the material onto a conveyor lined with spunbond nonwoven fabric (Asahi Kasei EcoRise S05015; average fiber diameter 16.1 μm) mainly composed of polylactic acid, and collect it to obtain a laminated sheet. The obtained sheet was then calendered using a rubber roll and a metal flat roll, with the metal flat roll heated to 100°C and clamped at a linear pressure of 40 kg / cm, and the clearance between the rubber roll and the metal flat roll was adjusted so that the sheet thickness was approximately 100 μm, to obtain a laminated composite filter material.

[0092] [Comparative Example 5] The ultrafine fiber web obtained in Example 1 and a spunbond nonwoven fabric (Asahi Kasei EcoRise S05015; average fiber diameter 16.1 μm) were simply layered together, sandwiched between an embossing roll and a flat roll, and heat-pressed together by thermal embossing to obtain a laminated composite filter material.

[0093] Figures 3A and 3B show an electron microscope image of the surface (non-embossed surface) of the first nonwoven fabric layer (Figure 3A) and a processed image for calculating the fiber-occupied area (Figure 3B). As shown in Figures 3A and 3B, the fibers constituting the first nonwoven fabric layer were not sufficiently accumulated, and the fiber-occupied area was 64.1%.

[0094] [Comparative Example 6] The ultrafine fiber web obtained in Example 3 and a spunbond nonwoven fabric (Asahi Kasei EcoRise S05015; average fiber diameter 16.1 μm) were simply layered together, sandwiched between an embossing roll and a flat roll, and heat-pressed together by thermal embossing to obtain a laminated composite filter material.

[0095]

[0096] As shown in Table 1, in Examples 1 to 5, despite using biodegradable fibers, the extraction rate remained almost unchanged before and after the encapsulated substance was stored. Furthermore, in Examples 1 to 5, the extraction rate from the encapsulated substance was slow both before and after storage. It is expected that using such a filter material to encapsulate coffee grounds will allow for a slow extraction of coffee components, resulting in a coffee with a rich flavor and superior aroma.

[0097] Furthermore, in Examples 1 and 3-5, the high degree of crystallinity of the polylactic acid fibers constituting the first nonwoven fabric layer reduces shrinkage when heated, resulting in less wrinkle formation. In particular, in Examples 1 and 3, the absolute value of the numerical difference between the degree of crystallinity of the fibers constituting the second nonwoven fabric layer and the degree of crystallinity of the fibers constituting the first nonwoven fabric layer was adjusted, resulting in almost no wrinkles.

[0098] On the other hand, in Comparative Examples 1 to 6, the extraction rate nearly doubled after storage, making it impossible to reproduce the extraction rate designed at the time of sealing. Furthermore, in Comparative Examples 1, 4, 5, and 6, the extraction rate was fast even at the time of sealing, so it was not possible to extract the coffee extract slowly in the first place, and the extracted coffee is expected to have a weak taste and inferior flavor.

[0099] Since the filter material of the present invention has biodegradable fibers in at least a portion of it, it can exhibit biodegradability and can be used, for example, as an encapsulated body in which various substances to be encapsulated are sealed with the filter material.

[0100] As described above, preferred embodiments of the present invention have been explained, but various additions, modifications, or deletions are possible without departing from the spirit of the present invention, and such are also included within the scope of the present invention.

Claims

1. The laminate comprises a first nonwoven fabric layer and a second nonwoven fabric layer, wherein the fibers constituting the first nonwoven fabric layer have a smaller average fiber diameter than the fibers constituting the second nonwoven fabric layer, at least one of the first and second nonwoven fabric layers is composed of biodegradable fibers, and the density of the first nonwoven fabric layer is 0.85 g / cm³. ３ That's all for the filter material.

2. A filter material comprising a laminate composed of a first nonwoven fabric layer and a second nonwoven fabric layer, wherein the fibers constituting the first nonwoven fabric layer have a smaller average fiber diameter than the fibers constituting the second nonwoven fabric layer, at least one of the first nonwoven fabric layer and the second nonwoven fabric layer is composed of biodegradable fibers, and the fiber area occupied on at least one surface of the first nonwoven fabric layer is 70.0% or more.

3. A filter material according to claim 1, wherein the fiber area occupied on at least one surface of the first nonwoven fabric layer is 70.0% or more.

4. A filter material according to any one of claims 1 to 3, wherein the crystallinity of the fibers constituting the first nonwoven fabric layer is 30% or more.

5. A filter material according to any one of claims 1 to 3, wherein the thickness of the first nonwoven fabric layer is 0.1 to 12.0 μm.

6. A filter material according to any one of claims 1 to 3, wherein the basis weight of the first nonwoven fabric layer is 1 to 14 g / m². ２ It is a filter material.

7. A filter material according to any one of claims 1 to 3, wherein the ratio of the thickness of the first nonwoven fabric layer to the thickness of the laminate is 2 to 15%.

8. A filter material according to any one of claims 1 to 3, wherein the first nonwoven fabric layer is made of a meltblown nonwoven fabric.

9. A filter material according to any one of claims 1 to 3, wherein the second nonwoven fabric layer is made of spunbond nonwoven fabric.

10. A filter material according to any one of claims 1 to 3, for filtering oil-containing solids.

11. A filter material according to any one of claims 1 to 3, wherein both the first nonwoven fabric layer and the second nonwoven fabric layer contain biodegradable fibers.

12. A filter material according to claim 11, wherein the biodegradable fiber includes polylactic acid fiber.

13. A filter container comprising the filter material according to any one of claims 1 to 3, wherein the first nonwoven fabric layer is arranged on the inside.

14. An encapsulation body comprising a filter material according to any one of claims 1 to 3 and a substance to be encapsulated, wherein the substance to be encapsulated is in contact with a first nonwoven fabric layer.

15. A method for manufacturing a filter material comprising a laminate composed of a first nonwoven fabric layer and a second nonwoven fabric layer, comprising at least the steps of: preparing a first nonwoven fabric sheet and a second nonwoven fabric sheet; and integrating the first nonwoven fabric sheet and the second nonwoven fabric sheet to obtain a laminate composed of a first nonwoven fabric layer and a second nonwoven fabric layer, wherein the fibers constituting the first nonwoven fabric sheet have a smaller average fiber diameter than the fibers constituting the second nonwoven fabric sheet, at least one of the first nonwoven fabric sheet and the second nonwoven fabric sheet is composed of biodegradable fibers, and the first nonwoven fabric sheet is in a pressed state.

16. A method for manufacturing a filter material according to claim 15, wherein the step of preparing the first nonwoven fabric sheet includes a step of obtaining the first nonwoven fabric sheet by a press treatment.

17. A method for manufacturing a filter material according to claim 15 or 16, wherein the first nonwoven fabric sheet is a press-treated meltblown nonwoven fabric.

Images