WO2015138556A1

WO2015138556A1 - Filter and method of producing the same and filtration system

Info

Publication number: WO2015138556A1
Application number: PCT/US2015/019875
Authority: WO
Inventors: Hironobu Satoh; Aaron S. NG; Erwin P. ONA; Jyoti Shailesh RASANE
Original assignee: 3M Innovative Properties Company
Priority date: 2014-03-11
Filing date: 2015-03-11
Publication date: 2015-09-17
Also published as: JP6385084B2; JP2015171670A

Abstract

A filter comprising: an acid clay or an activated clay or a combination thereof, a cellulose fiber, and a polyamine-epichlorohydrin resin; a method of producing the same; and a filtration system, a decaffeination system, and a decaffeination method using the filter.

Description

FILTER AND METHOD OF PRODUCING THE SAME AND FILTRATION

SYSTEM

FIELD

[0001] A filter and a method of producing the same and a filtration system.

A specific aspect of the present invention relates to a decaffeination system and a decaffeination method.

BACKGROUND

[0002] Conventionally, various filter media for removing an intended component from a fluid to be filtered have been proposed.

[0003] Patent Document 1 discloses a filter medium sheet comprising an adhesive matrix of a fine granular substance and a cellulose fiber, wherein a surface of at least one of the fine granular substance and the cellulose fiber is adjusted by a cationic resin of polyamide polyamine-epichlorohydrin, and the matrix is formed from cellulose fiber that is beaten in a manner such that a Canadian standard freeness of 600 mL or less is achieved. The Patent Document 1 discloses diatomaceous earth and pearlite as the granular substances.

[0004] Patent Document 2 discloses a method of producing a filter medium for cationic ultrafine contaminants having anionic electrokinetic capture potential, the method comprising the steps of: treating cellulose pulp and particulate filter elements using an inorganic cationic surface charge modifier to render the surface of the filter elements receptive to the subsequent deposition of an inorganic anionic charge modifier, thereafter, charge modifying the heat treated filter elements with an inorganic anionic charge modifier, and forming the filter elements into a sheet having a negative zeta potential and a wet strength of at least 2.5 kg/2.54 cm.

[0005] Patent Document 3 discloses filter media comprising filter elements of a cellulose fiber and silica based particulate or fiber and a charge modifying amount of a cationic charge modifying system bonded to surfaces of the elements.

[0006] Patent Document 4 discloses a filter sheet comprising a self- supporting fibrous matrix having immobilized therein particulate filter aid and particulate ion exchange resin particles, wherein the particulate filter aid and particulate ion exchange resin particles are distributed substantially uniformly throughout a cross-section of the matrix. Patent Document 4 also discloses that the filter sheet is used for removing ionic impurities from a photoresist solution.

[0007] In addition, various methods for removing caffeine from caffeine- containing beverages such as coffee and tea have been proposed so far. [0008] Patent Document 5 discloses a process for selectively removing caffeine from a caffeine-containing solution, the process comprising a step of bringing the solution into contact with activated clay or acid clay.

[0009] Patent Document 6 discloses a packaged beverage containing from

0.03 to 1.0 wt.% of non-polymer catechins, wherein the packaged beverage comprises a low-caffeine green tea extract obtained by a method of dissolving a green tea extract into an ethanol and water mixture having a weight ratio of 91/9 to 97/3, and bringing the mixture into contact with activated carbon, and acid clay or activated clay.

[0010] Patent Document 7 discloses a filter having a filter matrix containing activated clay powder or acid clay powder with an average particle diameter of 0.1 μιη to 100 μιη in a range of 20 mass% to 80 mass% based on the mass of the filter matrix, and ultra high molecular weight polyethylene powder or high molecular weight polyethylene powder (as a binding agent) in a range of 80 mass% to 20 mass% based on the mass of the filter matrix.

PATENT DOCUMENTS

[0011] Patent Document 1 : Japanese Unexamined Patent Application

Publication No. S55-129124A

Patent Document 2: Japanese Unexamined Patent Application Publication No. S56-124415A

Patent Document 3: Japanese Unexamined Patent Application Publication No. H04-504379A

Patent Document 4: Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2000-516133A

Patent Document 5: Japanese Unexamined Patent Application Publication No. H06-142405A

Patent Document 6: Japanese Unexamined Patent Application Publication No. 2005-176760A

Patent Document 7: Japanese Unexamined Patent Application Publication No. 2013-123662A

SUMMARY

[0012] Problem: To provide a filter that is capable of suitably achieving both the clarification and the decaffeination of the fluid to be filtered, and that is flexible and capable of being processed into various forms; a method of producing the same; and a filtration system, a decaffeination system, and a decaffeination method using the filter.

[0013] It has been known that the activated clay powder and acid clay powder have strong adsorption abilities and catalytic activities, and suitably adsorb caffeine. However, in a method where a filter medium in powder form is used, such as the methods described in Patent Documents 5 and 6, for example, there has been a problem of the process being complex because an additional solid-liquid separation treatment is required for removing the filter medium from the filtrate after removing the target component such as caffeine. Furthermore, since activated clay powders and acid clay powders are typically fine particles (particle diameter from several ten nm to several μιη), it has been difficult to separate the activated clay powders and the acid clay powder from the filtrate after use. On the other hand, for example, because the filter medium described in the Patent Document 7 has poor flexibility, there has been a problem that the formation of a filter having a large surface area (therefore, having a better filtration efficiency) is difficult.

[0014] Furthermore, for example, in a caffeine-containing fluid such as a caffeine-containing beverage, there are cases where a turbid appearance can be disadvantageous. Therefore, in a case where such a turbid appearance is not desired, a treatment for removing turbidity and a precursor of the turbidity, such as components contained in the tea extract (e.g. catechin, amino acid, saccharides, various polymer compounds, and the like) is required in addition to the removal of caffeine. However, a filter such that clarification and decaffeination of a caffeine-containing fluid can be achieved simultaneously by using the same filter has not been provided so far.

[0015] In light of the foregoing problems, an object is to provide a filter that is capable of suitably achieving both the clarification and the decaffeination of the fluid to be filtered, and that is flexible and capable of being processed into various forms; a method of producing the same; and a filtration system, a decaffeination system, and a decaffeination method using the filter.

[0016] One aspect provides a filter comprising: an acid clay or an activated clay or a combination thereof, a cellulose fiber, and a polyamine-epichlorohydrin resin.

[0017] Another aspect provides a filtration system comprising the filter described above.

[0018] Yet another aspect provides a decaffeination system comprising: a container having an introduction port for introducing a caffeine-containing fluid; and the filter described above arranged in the container.

[0019] Yet another aspect provides a method of removing caffeine from a caffeine-containing fluid comprising a step of filtering the caffeine-containing fluid using the filter described above.

[0020] Yet another aspect provides a method of producing a filter, the method comprising the steps of: preparing a dispersion containing: 30 parts by mass or greater and 79 parts by mass or less of an acid clay or an activated clay or a combination thereof, 20 parts by mass or greater and 69 parts by mass or less of a cellulose fiber, 1 part by mass or greater and 3 parts by mass or less of a polyamine- epichlorohydrin resin, and a dispersing medium; forming a filter on a support by placing the dispersion on the support, then removing the dispersing medium; and removing the support from the filter; wherein the acid clay or the activated clay or the combination thereof is in a particulate form having a particle diameter of 0.1 μιη or greater and 100 μιη or less; and a Canadian standard freeness of the cellulose fiber is 800 mL or less.

[0021] A filter that is capable of suitably achieving both the clarification and the decaffeination of the fluid to be filtered, and that is flexible and capable of being processed into various forms; a method of producing the same; and a filtration system, a decaffeination system, and a decaffeination method using the filter are provided.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a diagram illustrating an example of a decaffeination system according to an aspect.

[0023] FIG. 2 is a diagram illustrating an example of a container and a filter in the decaffeination system according to an aspect.

DETAILED DESCRIPTION

[0024] A typical embodiment is described in detail below, but the present is not limited to the embodiment below.

[0025] Filter. One aspect provides a filter comprising: an acid clay and/or an activated clay, a cellulose fiber, and a polyamine-epichlorohydrin resin. The acid clay and activated clay have high decaffeination capabilities, and thus the filter of the present disclosure has a high decaffeination capability.

[0026] Since the filter of the present disclosure comprises an acid clay and/or an activated clay, and a cellulose fiber, the acid clay and/or the activated clay can be suitably retained by a network of the cellulose fiber. Therefore, according to the filter of the present disclosure, because, due to the contribution of the cellulose fiber, the acid clay and/or the activated clay are hardly shed from the filter even when a relatively large amount of the acid clay and/or the activated clay is used, it is possible to maintain a favorable decaffeination capability for a long period of time. In addition, although it is thought that the liquid permeabilities of the acid clay and the activated clay themselves are not always satisfactory, in the filter of the present disclosure, favorable liquid permeability is achieved due to the acid clay and/or the activated clay being distributed among the cellulose fiber. Therefore, in the filter of the present disclosure, due to the favorable decaffeination capability (i.e. amount of decaffeination per unit amount of passed liquid) and favorable liquid permeability, excellent decaffeination treatment efficiency is achieved. Furthermore, the filter of the present disclosure is also effective for clarification of the fluid to be filtered. In other words, the filter of the present disclosure has a unique advantage that decaffeination and clarification of the fluid to be filtered can be achieved simultaneously.

[0027] The polyamine-epichlorohydrin resin imparts a positive zeta potential to the cellulose fiber, and is effective as a binding agent among the cellulose fiber. Because of this, a filter matrix containing the cellulose fiber is formed with a favorable mechanical strength. In addition, due to the use of the cellulose fiber, the filter of the present disclosure has extremely superior flexibility compared to conventional filters such as a filter, for example the filter disclosed in the Patent Document 7 described above, containing a combination of ultra high molecular weight polyethylene powder or high molecular weight polyethylene powder and activated clay powder or acid clay powder. Flexible filters can be processed into various forms, and thus various desired apparatus designs (e.g. filtration area) are made possible. Therefore, with such a flexible filter, favorable filtration efficiency can be easily achieved. In particular, the filter of the present disclosure can be made into a relatively thin sheet form (e.g. from about 2 mm to about 9 mm) while having a relatively large amount of the acid clay and/or the activated clay. Such a sheet-like filter has advantages in that the clarification capability and decaffeination capability can be enhanced compared to, for example, a block-like filter.

[0028] Each component of the filter will be further described hereinafter.

[0029] Acid clay and activated clay. The filter of the present disclosure comprises an acid clay or an activated clay or a combination thereof.

[0030] In the present disclosure, the "acid clay" refers to a clay that contains, as the main component, montmorillonite, and that emits H⁺ when suspended in water. The acid clay can be a naturally occurring montmorillonite-based clay. In a typical aspect, the acid clay includes a small amount of cristobalite. In the present disclosure, the "activated clay" refers to a product obtained by a thermal oxidization treatment of the acid clay described above. Each of the acid clay and the activated clay can contain, as a general chemical component, S1O2, AI2O3, Fe₂03, CaO, MgO, and the like. In an aspect, the acid clay and the activated clay can each have a S1O2/AI2O3 ratio of about 3 or greater and about 12 or less, or about 4 or greater and about 10 or less. In an aspect, the acid clay and the activated clay can each contain about 1.0 mass% or greater and about 5 mass% or less of Fe₂03, about 0 mass% or greater and about 1.5 mass% or less of CaO, and about 1 mass% or greater and about 7 mass% or less of MgO. In an aspect, the acid clay contains, as a major chemical composition, about 70% to about 75% of S1O2, and about 13% to about 15% of AI2O3, and in addition, can further contain H2O, OH^", and the like. In addition, in an aspect, the activated clay can contain, as a major chemical composition, about 70% to about 80% of S1O2 and about 8% to about 15% of AI2O3. In an aspect, the filter contains the acid clay.

[0031] In an aspect, the acid clay and the activated clay are each in a particulate form. In an aspect, each of the particulate acid clay and activated clay has a particle diameter of about 0.1 um or greater and about 100 μιη or less, or about 10 μιη or greater and about 50 μιη or less. In the present disclosure, the particle diameter is a median diameter measured in terms of volume measured by the laser diffraction/scattering method. In the case where the particle diameter is about 0.1 μιη or greater, it is advantageous from the perspective of ease of filter production due to the favorable handleability of the acid clay and/or the activated clay. In the case where the particle diameter is about 100 μιη or less, it is advantageous from the perspectives of the decaffeination capability of the filter being favorable as well as the acid clay and/or the activated clay being hardly shed from the filter.

[0032] In an aspect, the specific surface area of the acid clay and the activated clay are each about 1 m²/g or greater and about 500 m²/g or less, or about 50 m²/g or greater and about 350 m²/g or less. In addition, in an aspect of the acid clay, the specific surface area is about 50 m²/g or greater and about 150 m²/g or less. In the present disclosure, the specific surface area is a value measured by the BET method. In the case where the specific surface area described above is about 1 m²/g or greater, the decaffeination capability of the filter is favorable. In the case where the specific surface area is about 500 m²/g or less, the production of the filter is easy due to the favorable handleability of the acid clay and/or the activated clay.

[0033] Each of the acid clay and the activated clay can be a commercial product. Examples of the commercially available acid clay include Mizuka Ace #600 (commercially available from Mizusawa Industrial Chemicals, Ltd. (Chuo-ku, Tokyo, Japan)) and the like. Examples of the commercially available activated clay include Galleon Earth V2 (trade name; manufactured by Mizusawa Industrial Chemicals, Ltd. (Chuo-ku, Tokyo, Japan)), and activated clay SA35 (trade name; manufactured by Toshin Chemicals Co., Ltd. (Chuo-ku, Tokyo, Japan)).

[0034] In an aspect, the total amount of the acid clay and/or the activated clay is, in terms of the total mass of the filter, about 30 mass% or greater and about 79 mass% or less, or about 60 mass% or greater and about 79 mass% or less. In the case where the amount of the acid clay and/or the activated clay is about 30 mass% or greater, the decaffeination capability of the filter is favorable. In the case where the amount of the acid clay and/or the activated clay is about 79 mass% or less, an advantage due to the use of a preferable amount of the cellulose fiber described in the present disclosure can be favorably obtained.

[0035] In an aspect, the total amount of the acid clay and/or the activated clay is, in terms of 100 parts by mass of a cellulose fiber, about 50 parts by mass or greater and about 500 parts by mass or less, or about 100 parts by mass or greater and about 400 parts by mass or less. In the case where the amount of the acid clay and/or the activated clay relative to the 100 parts by mass of the cellulose fiber is about 50 parts by mass or greater, the decaffeination capability is favorable. In the case where the amount of the acid clay and/or the activated clay relative to the 100 parts by mass of the cellulose fiber is about 500 parts by mass or less, the formability, shape maintaining property, and flexibility of the filter are favorable, and the shedding of the acid clay and/or the activated clay can be favorably avoided.

[0036] Cellulose fiber. The cellulose fiber can be obtained from any of various cellulose sources such as wood pulp and cotton, and more typically from wood pulp. The cellulose fiber may be a natural cellulose fiber or a recycled cellulose fiber. In an aspect, the cellulose fiber is a natural cellulose fiber.

[0037] In an aspect, the Canadian standard freeness of the cellulose fiber is about 800 mL or less. In the present disclosure, the "Canadian standard freeness" refers to a value measured in accordance with the Canadian standard freeness method (in accordance with JIS P 8121 (2012 edition) or ISO 5267), and refers to a value measured with the entirety of the cellulose fiber contained in the filter of the present disclosure. In the case where the Canadian standard freeness of the cellulose fiber is about 800 mL or less, the clarification and decaffeination capabilities of the filter are favorable. The Canadian standard freeness of the cellulose fiber can be controlled to a desired range by adjusting the beating conditions for production of the cellulose fiber in which raw materials are beaten.

[0038] In an aspect, the cellulose fiber contained in the filter of the present disclosure can be a blended product of a cellulose pulp refined in a manner such that the Canadian standard freeness is from about +100 mL to about -600 mL (hereinafter, also called "highly refined pulp") and a cellulose pulp having a typical dimension (e.g. the Canadian standard freeness is from +400 mL to +800 mL; hereinafter, also called "standard cellulose pulp"). The standard cellulose pulp and the highly refined pulp described above can be obtained by, for example, the method described in Japanese Unexamined Patent Application Publication No. 2000-516133A. In a preferred aspect of the blended product described above, the mass ratio of the standard cellulose pulp the highly refined pulp can be from about 0.6: 1 to about 30: 1. From the perspective of favorably retaining the acid clay and/or the activated clay, such a blended product of the standard cellulose pulp and the highly refined pulp is more advantageous than a cellulose fiber, for example, consisting of standard cellulose pulp only.

[0039] In the exemplified aspect, the Canadian standard freeness of the raw material (e.g. wood pulp) of the cellulose fiber can be in a range of about 400 mL or greater and about 800 mL or less, for example.

[0040] In an aspect, the amount of the cellulose fiber is, in terms of the total mass of the filter, about 20 mass% or greater and about 69 mass% or less, or about 20 mass% or greater and about 50 mass% or less, or about 20 mass% or greater and about 30 mass% or less. In the case where the amount of the cellulose fiber is about 20 mass% or greater, the formability, shape maintaining property, and flexibility of the filter are favorable, and the acid clay and/or the activated clay can be favorably retained by the cellulose fiber. In the case where the amount of the cellulose fiber is about 69 mass% or less, an advantage due to the use of a preferable amount of the acid clay and/or the activated clay described in the present disclosure can be favorably obtained.

[0041] Polyamine-epichlorohydrin resin. The filter of the present disclosure contains a polyamine-epichlorohydrin resin. The polyamine-epichlorohydrin resin stably imparts a positive zeta potential, and favorably exhibits an effect as a binding agent among the cellulose fiber in the filter.

[0042] The polyamine-epichlorohydrin resin can be a reaction product of polyamide polyamine and epichlorohydrin for example, or the like. Polyamide polyamine can be obtained by, for example, reacting dicarboxylic acid and polyalkylene amine.

[0043] Dicarboxylic acid is exemplified by aromatic dicarboxylic acids and aliphatic dicarboxylic acids. Examples thereof include adipic acid, azelaic acid, diglycolic acid, oxalic acid, malonic acid, and the like.

[0044] Polyalkylene polyamine is exemplified by polyalkylene polyamine containing at least two primary amine groups and at least one secondary amine group. Examples thereof include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and the like.

[0045] In particular, polyamine-epichlorohydrin resin may be the polyamine-epichlorohydrin resin described in, for example, US Patent No. 2,926,116, US Patent No. 2,926,154, US Patent No. 3,224,986, US Patent No. 3,332,901 and US Patent No. 3,382,096, and may be a commercial product. Examples of the commercial product include POLYCUP, CUSCAMID, NOPCOBOND, and the like.

[0046] In an aspect, the amount of the polyamine-epichlorohydrin resin is, in terms of the total mass of the filter, about 1 mass% or greater and about 3 mass% or less, or about 1 mass% or greater and about 2 mass% or less. In the case where the amount of the polyamine-epichlorohydrin resin is about 1 mass% or greater, the mechanical strength of the filter is favorable and, in addition, the shedding of the acid clay and/or the activated clay can be favorably avoided. On the other hand, although an excessive amount of polyamine-epichlorohydrin resin tends to cause a decrease in flexibility, in the case where the amount of the polyamine-epichlorohydrin resin is about 3 mass% or less, such a demerit can be favorably avoided.

[0047] Shape and property of the filter. The shape of the filter can be a variety of shapes, and examples thereof include sheet, block, and the like. From the perspective of favorable filtration efficiency, the filter is preferably a sheet. In a preferred aspect, the thickness of the sheet is about 2 mm or greater and about 9 mm or less, or about 3 mm or greater and about 8 mm or less. In the case where the thickness of the sheet is about 2 mm or greater, the mechanical strength and the filtration performance of the filter is favorable. In the case where the thickness of the sheet is about 9 mm or less, excellent formability can be obtained due to the favorable flexibility of the filter, and thus a desired design, in a manner such that the design imparts favorable filtration efficiency, is facilitated.

[0048] In an aspect, when a caffeine aqueous solution having a caffeine concentration of 0.2 mg/mL is flowed using a 47 mm disk at a rate of 30 mL/min, the initial pressure drop is about 0 MPa or greater and about 0.1 MPa or less, or about 0 MPa or greater and about 0.05 MPa or less. In the case where the initial pressure drop is in the range described above, the filtration performance and liquid permeability of the filter are favorable.

[0049] In addition, from the perspective of liquid permeability, the air- flow resistance of the filter measured by using a device having a manometer and a flowmeter is preferably about 1.0 inH₂0 or greater and about 50 inH₂0 or less, or about 5 inH₂0 or greater and about 45 inH₂0 or less.

[0050] Production method of the filter. Another aspect provides a method of producing the filter. In an aspect, the method of producing the filter comprises the steps of:

preparing a dispersion containing: about 30 parts by mass or greater and about 79 parts by mass or less of an acid clay or an activated clay or a combination thereof,

about 20 parts by mass or greater and about 69 parts by mass or less of a cellulose fiber,

about 1 part by mass or greater and about 3 parts by mass or less of a polyamine-epichlorohydrin resin, and

a dispersing medium;

forming a filter on a support by placing the dispersion on the support, then removing the dispersing medium; and removing the support from the filter; wherein,

the acid clay or the activated clay or the combination thereof is in a particulate form having a particle diameter of about 0.1 μιη or greater and about 100 μιη or less; and

a Canadian standard freeness of the cellulose fiber is about 800 mL or less.

[0051] In an aspect, each of the acid clay and the activated clay described above is in a particulate form and has a particle diameter of about 0.1 um or greater and about 100 μιη or less. The details of the acid clay and the activated clay are as described above for the filter.

[0052] In an aspect, the Canadian standard freeness of the cellulose fiber is about 800 mL or less. The details of the cellulose fiber are as described above for the filter.

[0053] Hereinafter, a more specific example of the above described method will be explained.

[0054] A first dispersion is prepared in advance by adding an acid clay and/or an activated clay to a dispersing medium (typically water) and dispersing therein while stirring. Separately, a second dispersion is prepared by dispersing a cellulose fiber and a polyamine-epichlorohydrin resin in a dispersing medium (typically water). The first dispersion is added into the second dispersion. Thereby, a dispersion can be obtained, for example.

[0055] Next, this dispersion is placed on a support. The support can be a mesh or the like. A publicly known paper making apparatus or the like can be used. Then, the dispersing medium is removed by, for example, suction or the like. Thereby, a filter can be formed, as a fine porous structure with a high porosity, on the support. Finally, the support is removed from the obtained filter.

[0056] Use of the filter. Another aspect provides a filtration system, particularly a decaffeination system, comprising the filter according to one aspect of the present invention described above. In an aspect, a filtration system such as a decaffeination system comprises a container having an introduction port for introducing a fluid to be filtered such as a caffeine-containing fluid; and the filter according to one aspect of the present invention described above arranged in the container. The filtration system of the present disclosure is advantageous from the perspectives of having no need for additional treatments such as separating the acid clay and/or the activated clay from the treated fluid as well as causing no aggravation of work environment due to the scattering of the acid clay and/or the activated clay since the acid clay and/or the activated clay is favorably retained among the cellulose fiber in the filter.

[0057] In an aspect of the filtration system such as a decaffeination system, the filter is in a sheet form. The details of the filter in the filtration system are as described above for the filter.

[0058] The filter of the present disclosure has excellent capabilities of both cleaning and decaffemation, and the filtration system of the present disclosure is particularly advantageously a decaffemation system. However, for example, the filter of the present disclosure can be used in applications where the purpose is to clean but the purpose is not to remove caffeine.

[0059] Hereinafter, examples of the decaffemation system will be described in further detail. FIG. 1 is a diagram illustrating an example of a decaffemation system according to an aspect. FIG. 2 is a diagram illustrating an example of a container and a filter in the decaffemation system according to an aspect. Referring to FIGS. 1 and 2, as long as the decaffemation system 1 of the present disclosure comprises a container 11 having an introduction port for introducing a caffeine- containing fluid; and a filter 12 arranged in the container, any structure is possible.

[0060] In the exemplified aspect, referring to FIG. 1, the decaffemation system 1 can be configured to have a fluid supply part 10 and a decaffemation part 20. The decaffemation part 20 can have the container 11 and a filter 12 that is arranged in the container 11. In this configuration, the caffeine-containing fluid is supplied from the fluid supply part 10 to the decaffemation part 20 via a flow passage LI, and then the treated fluid from which caffeine is removed in the decaffemation part 20 is sent out via a flow passage L2.

[0061] Further referring to FIG. 2, the decaffemation system 1 comprises a container 11 having an introduction port 111 for introducing a caffeine-containing fluid, and a filter 12 arranged in the container 11. As illustrated in FIG. 2, the decaffemation system according to a more typical aspect comprises a container 11 having an introduction port 111 and an outlet port 112, and a filter 12. The introduction port 111 is connected to, for example, a fluid supply part via a flow passage LI, and the decaffemation system is configured to be such that the treated fluid, from which caffeine is removed by the filter 12 in the container 11, is sent out from the container through the outlet port 112 and a flow passage L2.

[0062] The decaffemation system can be configured, by those skilled in the art, in a manner such that a treated fluid with a desired caffeine concentration can be obtained. For example, the decaffemation system is configured in a manner such that the liquid hourly space velocity SV, the liquid temperature, or the like can be varied.

[0063] Examples of the caffeine-containing fluid include beverages such as tea (e.g. green tea, black tea, Oolong tea, and the like), coffee, cola, and the like; extracts such as tea, coffee, and other caffeine-containing plant extracts and the like.

[0064] Various materials and sizes can be used for the container 11; however, examples thereof include a stainless steel container such as 12ZPN filter housing (manufactured by 3M (Minnesota, USA)), and the like.

[0065] The fluid supply part 10 can be a storage tank or the like of the caffeine-containing fluid (e.g. caffeine-containing beverage such as coffee or tea).

[0066] As described above, various shapes are possible for the filter 12; however, in an aspect, the filter 12 is a sheet. Although various arrangements of the sheet within the container are possible, from the perspective of having a favorable filtration efficiency, typically, a larger filtration area is more preferable. As a means to enlarge the filtration area of the filter, conventionally known means can be suitably employed. For example, the filter cartridge configured by a plurality of disk-like filters illustrated in FIGS. 5 and 6 of the Patent Document 3 described above (Japanese Unexamined Patent Application Publication No. H04-504379A) can be employed in the decaffeination system of the present disclosure.

[0067] For example, referring to FIG. 2, an example of a batch type decaffeination system in the case where 90% of caffeine is removed from a caffeine- containing fluid with a caffeine concentration of 0.2 mg/mL has a configuration where about 10 cartridges, in which a plurality of cells 121 (e.g. 16 cells) formed by sealing the peripheral edge of two sheets 121a and 121b (thickness: from about 5 mm to about 7 mm; diameter: about 12 in) using a seal member 121c are layered, are arranged in a container 11 having a capacity of from about 4000 L to about 20000L (here, for example, an approximately 10000 L container 11).

[0068] The decaffeination system described above can be suitably modified.

For example, in place of the fluid supply part 10 described above, the flow passage LI can be connected to another decaffeination system, and caffeine can be further removed from the treated fluid supplied from the system.

[0069] In addition, in place of the above, a caffeine-containing fluid having undergone at least one of the means (a) to (c) described below can be supplied to the decaffeination part 20:

(a) centrifugal separation means;

(b) membrane filtration means such as ultrafiltration, fine filtration, precise filtration, reverse osmotic membrane filtration, electrodialysis, or filtration by a membrane such as a biofunctional membrane; and

(c) filtration means having a column, a filter press, or a Sparkler filter packed with an adsorbent such as an ion exchange resin, an activated carbon, or zeolite.

[0070] For example, in the case where the caffeine-containing fluid is obtained by centrifugal separation, the caffeine-containing fluid can be supplied as is to the decaffeination part 20.

[0071] Furthermore, at least one of the means (a) to (c) described above can be further performed in the subsequent stage of the decaff eination part 20.

[0072] Another aspect provides a method of removing caffeine from a caffeine-containing fluid comprising a step of filtering the caffeine-containing fluid using the filter according to an aspect of the present invention described above. In this method, by using the filter of the present disclosure, it is possible to favorably achieve clarification in addition to decaffeination.

[0073] As described above with examples, the present disclosure includes the following aspects.

[1] A filter comprising: an acid clay or an activated clay or a combination thereof; a cellulose fiber; and a polyamine-epichlorohydrin resin.

[2] The filter according to [1], wherein the filter comprises: 30 mass% or greater and 79 mass% or less of the acid clay or the activated clay or the combination thereof;

20 mass% or greater and 69 mass% or less of the cellulose fiber; and

1 mass% or greater and 3 mass% or less of the polyamine-epichlorohydrin resin;

the acid clay or the activated clay or the combination thereof is in a particulate form having a particle diameter of 0.1 μιη or greater and 100 μιη or less; and

a Canadian standard freeness of the cellulose fiber is 800 mL or less.

[3] The filter according to [1] or [2], wherein the filter is a sheet having a thickness of 2 mm or greater and 9 mm or less.

[4] A method of producing a filter, the method comprising the steps of:

preparing a dispersion containing:

30 parts by mass or greater and 79 parts by mass or less of an acid clay or an activated clay or a combination thereof;

20 parts by mass or greater and 69 parts by mass or less of a cellulose fiber;

1 part by mass or greater and 3 parts by mass or less of a polyamine- epichlorohydrin resin; and

a dispersing medium;

forming a filter on a support by placing the dispersion on the support, then removing the dispersing medium; and

removing the support from the filter; wherein

a Canadian standard freeness of the cellulose fiber is 800 mL or less.

[5] A filtration system comprising the filter described in any one of [1] to [3]. [6] A decaffeination system comprising: a container having an introduction port for introducing a caffeine-containing fluid; and the filter described in any one of [1] to [3] arranged in the container.

[7] A method of removing caffeine from a caffeine-containing fluid comprising a step of filtering the caffeine-containing fluid using the filter described in any one of [1] to [3].

EXAMPLES

[0074] Working Examples 1 through 5. Production of filters. An acid clay powder (trade name: Mizuka ace 600; manufactured by Mizusawa Industrial Chemicals, Ltd. (Chuo-ku, Tokyo, Japan)) having a median diameter of 17 μιη measured in terms of volume measured by the laser diffraction/scattering method; a cellulose fiber (a blended product of a cellulose fiber having a Canadian standard freeness of +400 to +800 mL and a cellulose fiber having a Canadian standard freeness of -250 mL; available from Carter Holt Harvey (Head office: New Zealand)) containing a beaten cellulose having a Canadian standard freeness of 800 mL or less; and a polyamine-epichlorohydrin resin (trade name: NOPCOBOND 1213; available from NOPCO (Head office: Norway)) are suspended in water at a compounding ratio shown in Table 1 , and then mixed using a stirrer.

[0075] The suspension obtained above is placed in hand paper-making equipment (box-shaped; 345 mm length, 240 mm width, and 77 mm height) equipped with a mesh and a suction mechanism, and suction was performed. The produced wet sheet was removed and placed in an oven to dry at a temperature of 180°C for 20 minutes. The obtained dried sheet was cut to a diameter of 47 mm and sheet-like filters for Working Examples 1 to 5 were obtained. The filtration areas of these filters are shown in Table 1.

[0076] Evaluation of the filters. The decaffeination capability, clarity of tea, and Shore hardness of the obtained filters are evaluated in accordance with the methods below.

[0077] 1. Decaffeination capability. A caffeine-containing fluid (hereinafter, called a "stock solution") was prepared by dissolving anhydrous caffeine reagent (manufactured by Wako Pure Chemical Industries, Ltd. (Osaka, Japan)) in ultrapure water in a manner such that the caffeine concentration thereof was 0.2 mg/mL. Then, the stock solution was passed through each of the filters of Working Examples 1 to 5 by using a Masterflex tubing pump and an L/S17 tube, and by setting the feed amount of the liquid at 30 mL/min.

[0078] 1000 mL of the stock solution was treated and the filtrate was sampled every 100 mL.

[0079] Note that, the caffeine concentration of the stock solution and the filtrate were determined by measuring the absorbance at a wavelength of 273 nm of a 20-fold diluted solution (diluted with ultrapure water) of each of the stock solution and the filtrate using a DR500 spectrophotometer (manufactured by Hach (Colorado, USA)), and performing calculations based on a calibration curve that was made in advance.

[0080] From the obtained caffeine concentration of the stock solution and the caffeine concentration of the filtrate, the decaffeination rate (%) of the filtrate from the stock solution was determined, and the relationship between the decaffeination rate (%) and the throughput (i.e. total amount of the filtrate) was plotted. To this, a fitted curve (polynomial approximation) of the least squares method was applied, and the throughput at 90% decaffeination rate was determined. The results are shown in Table 1.

[0081] 2. Clarity. As the caffeine-containing fluid, "Ajiwai ryoku-cha (trade name)" manufactured by Asahi Soft Drinks Co., Ltd. was prepared. Then, the caffeine-containing fluid was passed through each of the filters of Working Examples 1 to 5 by using a Masterflex tubing pump and an L/S17 tube, and by setting the feed amount of the liquid at 30 mL/min. Total throughput of the caffeine-containing fluid was set at 400 mL. The kaolin turbidity was measured as the clarity of the caffeine- containing fluid and the filtrate using a Water Analyzer 2000N manufactured by Nippon Denshoku Industries Co., Ltd. (Japan). The results are shown in Table 1.

[0082] 3. Shore hardness. The Shore A hardness of the filters was measured by a digital Rubber Hardness Tester, model DD2-A (ASKER (Kobunshi Keiki Co., Ltd.)). Per sample, five points were measured and a number average value was calculated. The results are shown in Table 1.

[0083] Comparative Example 1. 50 parts by mass of an acid clay powder

(trade name: Mizuka ace 600; manufactured by Mizusawa Industrial Chemicals, Ltd. (Chuo-ku, Tokyo, Japan)) having a median diameter of 13 μιη measured in terms of volume measured by the laser diffraction/scattering method; and 50 parts by mass of ultra high molecular weight polyethylene powder PE-1 (trade name: GUR2126; manufactured by Ticona (Kentucky, USA)) having a bulk density of 0.23 g/cm³, weight average molecular weight of 4.5x 10⁶ g/mol, and an average particle size of 35 μιη were mixed using a blade mixer, and mixed powder was obtained. The mixed powder was filled in a mold, and then baked in an oven at a temperature of 155°C for 10 minutes. The obtained baked product was cut to obtain a disk- like filter having a diameter of 47 mm and an average thickness of about 5 mm.

[0084] The filter was evaluated by the same procedure as for the Working

Examples except for using the disk-like filter in place of the sheet-like filter. The results are shown in Table 1. [0085]

Table 1: The compositions and properties of the filters

(1) Filter thickness was an average value measured at 5 points using vernier calipers

(2) Filtration area was an effective filtration area of the SUS Inline Holder 47 mm (manufactured by 3M) that was used

(3) Measured using a device having a manometer and a flowmeter

(4) Pressure drop when a caffeine aqueous solution having a caffeine concentration of 0.2 mg/mL was passed through

(5) The turbidity of the caffeine-containing fluid that was used was 9.051

[0086] The filter is advantageously used for filtration purposes such as decaffeination.

Claims

What is Claimed is:

1. A filter comprising: an acid clay or an activated clay or a combination thereof; a cellulose fiber; and a polyamine-epichlorohydrin resin.

2. The filter according to claim 1, wherein the filter comprises: 30 mass% or greater and 79 mass% or less of the acid clay or the activated clay or the combination thereof;

20 mass% or greater and 69 mass% or less of the cellulose fiber; and

1 mass% or greater and 3 mass% or less of the polyamine-epichlorohydrin resin;

a Canadian standard freeness of the cellulose fiber is 800 mL or less.

3. The filter according to claim 1 or 2, wherein the filter is a sheet having a thickness of 2 mm or greater and 9 mm or less.

4. A method of producing a filter, the method comprising the steps of:

preparing a dispersion containing:

20 parts by mass or greater and 69 parts by mass or less of a cellulose fiber;

a dispersing medium;

removing the support from the filter; wherein

a Canadian standard freeness of the cellulose fiber is 800 mL or less.

5. A filtration system comprising the filter described in any one of claims 1 to 3.

6. A decaff eination system comprising: a container having an introduction port for introducing a caffeine-containing fluid; and

the filter described in any one of claims 1 to 3 arranged in the container.

7. A method of removing caffeine from a caffeine-containing fluid comprising a step of filtering the caffeine-containing fluid using the filter described in any one of claims 1 to 3.