JP5933771B2 - Activated carbon sheet for water purification and water purification filter - Google Patents

Description

  The present invention relates to a water purification filter that has a small pressure loss, is not easily clogged, and is excellent in water purification performance per unit volume, and an activated carbon sheet for water purification that constitutes the water purification filter.

From the viewpoint of health and public health, the water supply law stipulates that tap water used for beverages is added with chlorine for the purpose of sterilization and contains a certain concentration or more of residual chlorine.
However, chlorine added for the purpose of sterilization has an oxidative action on inorganic substances and an oxidative decomposition action on organic substances in addition to the sterilizing action. When humic substances that are a kind of natural organic substances are oxidatively decomposed, It is known to produce trihalomethane, a carcinogen.
Therefore, in order to remove organic halogen compounds typified by trihalomethane contained in tap water, tap water purification treatment has been performed using activated carbon having an adsorption action.

Conventionally, as activated carbon for water treatment, activated carbon having a high surface area that is excellent in iodine adsorption performance, methylene blue adsorption performance, and the like has been used in order to increase the amount of the object to be removed per unit volume of activated carbon.
For example, Patent Document 1 discloses that the specific surface area is 1300 m ² / g or more, the cumulative pore volume occupied by pores having a pore radius of 9 to 16 Å is 0.25 cc / g or more, and the pore radius is 9 to 16 Å. There is disclosed a water purifier filler comprising fibrous activated carbon having a cumulative pore volume occupied by pores of 50% or more of a cumulative pore volume occupied by pores having a pore radius of 100 mm or less.
Patent Document 2 discloses that the cumulative surface volume occupied by pores having a specific surface area of 800 m ² / g or more and a pore radius of 9 mm or less is 0.20 cc / g or more and a pore radius of 9 mm or less. There is disclosed a water purifier filler comprising fibrous activated carbon having a cumulative pore volume occupied by pores of 50% or more of a cumulative pore volume occupied by pores having a pore radius of 100 mm or less.
However, in both cases, the ability to remove the organic halogen compounds is low, which is not satisfactory.

  In addition, with regard to the removal of trihalomethane, conventionally, there has been a water purification filter in which granular, powdered, fibrous activated carbon or ion exchangers are molded by a wet molding method (slurry suction method) or a compression molding method with a fibrous binder or a powdery binder. well known.

For example, Patent Document 3 discloses an integrally formed hollow cylindrical shaped adsorbent including 10 to 100 parts by weight of fibers composed of reinforcing fibers and a fibrous binder with respect to 100 parts by weight of granular activated carbon having a particle diameter of 150 μm to 5 mm. And the shaping | molding adsorption body whose ratio of a fibrous binder is 2-10 weight part with respect to 100 weight part of granular activated carbon is disclosed.
In Patent Document 4, 100 parts by weight of fibrous activated carbon having a specific surface area of 1000 to 1800 m ² / g and a powdery insulator having a center particle diameter of 10 to 70 microns and a benzene adsorption capacity of 25 to 40% by weight A water purifier is disclosed in which an activated carbon molded body obtained by integrally molding a mixture of 10 to 300 parts by weight of a phenol resin-based activated carbon and 3 to 30 parts by weight of a fibrous binder by a slurry suction method is filled as a cartridge. However, since it is molded by the slurry suction method, it is difficult to increase the molding density of the filter while suppressing the pressure loss of the filter, and there is a problem that clogging easily occurs.

  Patent Document 5 discloses a composite adsorbent in which plastic and fine particle powder are attached to the surface of at least one kind of adsorbent selected from powder, granule, and fiber, and Patent Document 6 includes An activated carbon molded body composed of granular or powdered activated carbon and a thermoplastic polymer binder, having an apparent density of 0.65 g / cc or less and a volume resistivity of 300 Ω · cm or less is disclosed. A water treatment filter is disclosed in which at least two types of activated carbons and short fibers having different diameters are solidified with a binder composed of a high molecular weight porous polymer. However, in the technique of Patent Document 5, it is necessary to screen the fine powder part, and since all of the techniques of Patent Documents 5 to 7 are obtained by the pressure molding method, the water purification performance is excellent. It was still not satisfactory enough.

  Furthermore, in Patent Document 8, the inner peripheral layer and the outer peripheral layer of the cylindrical body are each made of a nonwoven fabric, and the layer between the inner peripheral layer and the outer peripheral layer is constituted by a mixed paper made of activated carbon fibers and heat-meltable fibers, A filter for water purification in which both ends of a cylindrical body are fixed by a thermoplastic resin is disclosed, and Patent Document 9 discloses a composite fiber obtained by mixing fibrous activated carbon and a heat-fusible composite fiber by a dry papermaking method. There is disclosed a water purifier using a filter medium in which fibrous activated carbon sheets obtained by fusing are bonded. Although these techniques have low pressure loss and are not easily clogged, they cannot be said to be sufficiently satisfactory with respect to water purification performance, and further enhancement of performance has been demanded. Further, since many expensive fibrous activated carbons are used, there is a problem that the cost performance is particularly low at a low SV.

JP-A-6-99064 JP-A-6-99065 Japanese Patent No. 3537149 Japanese Patent No. 4064309 International Publication No. 2006/082898 JP 2006-182582 A JP 2002-355515 A Japanese Patent No. 3143860 JP 2008-149267 A

  An object of the present invention is to solve the above-mentioned problems, and to provide a water purification filter having a small pressure loss, being not easily clogged, and excellent in water purification performance per filter volume, and a water purification activated carbon sheet constituting the water purification filter.

As a result of intensive studies to solve the above-mentioned problems, the present inventors used an activated carbon sheet for water purification obtained by a wet papermaking method, comprising a mixture of powdered activated carbon, fibrous activated carbon, heat-fusible fiber, and pulp. The water purification filter obtained by molding this sheet has been found to have excellent water purification performance and low pressure loss, and has reached the present invention.
That is, the gist of the present invention is as follows.
(1) Powdered activated carbon (A) 50 to 80% by mass, fibrous activated carbon (B) 2 to 30% by mass, and heat-fusible fiber (C) 5 to 15% by mass with a fiber diameter of 10 to 25 μm And a wet papermaking sheet comprising a mixture of cellulose or acrylic pulp (D) having a fiber diameter of 5 to 30 μm and a total of 100% by mass of these, and said powder The activated carbon (A) has a median diameter of 30 to 120 μm, a basis weight of the sheet of 80 to 170 g / m ² , and a peel strength of a laminated sheet obtained by thermally bonding two sheets is 10 g / 20 mm or more. An activated carbon sheet for water purification.
(2) The activated carbon sheet for water purification according to (1), wherein the specific surface area of the sheet is 550 m ² / g or more.
(3) The mixture further contains 3 to 20% by mass of weak acid type polyacrylate ion exchange fiber (E), and the total is 100% by mass, for water purification according to (1) or (2) Activated carbon sheet.
(4) A water purification filter formed by molding the activated carbon sheet according to any one of (1) to (3) above, and having an apparent density of 0.35 to 0.55 g / cm ³ .
(5) The water purification filter according to (4), wherein the total trihalomethane removal performance at a space velocity (SV) of 500 / h is 15 L / cm ³ or more and the pressure loss is 0.10 MPa or less.

  The activated carbon sheet for water purification and the water purification filter of the present invention are excellent in removal performance for heavy metals such as organic halogen compounds represented by total trihalomethane and soluble lead, in addition to the free chlorine removal performance required for water purifiers, In addition, since the pressure loss is small and clogging is difficult, the service life can be extended and the cost performance is excellent.

Hereinafter, the present invention will be described in detail.
The activated carbon sheet for water purification of the present invention is powdered activated carbon (A) 40-80% by mass, fibrous activated carbon (B) 2-30% by mass, heat-fusible fiber (C) 5-15% by mass, It is a wet papermaking sheet comprising a mixture of 5 to 15% by mass of pulp (D) and the total of which is 100% by mass.

The powdered activated carbon (A) used in the activated carbon sheet for water purification of the present invention is preferably one having a specific surface area of 550 m ² / g or more when formed into a sheet, as long as the total trihalomethane removal performance does not decrease. It does not specifically limit, Commercially available eggplant type | system | group, coal type | system | group, a phenol resin type activated carbon can be used.

  The median diameter of the powdered activated carbon (A) is required to be 30 to 120 μm, and preferably 50 to 100 μm. When the median diameter of the powdered activated carbon (A) is less than 30 μm, most of the powdered activated carbon does not remain on the sheet when a sheet is obtained by the wet papermaking method, the material yield is significantly reduced, and a good sheet cannot be obtained. Not only that, even if it can be filtered, clogging is likely to occur. On the other hand, if the median diameter exceeds 120 μm, the contact efficiency is lowered, so not only the water purification performance may be lowered, but also problems such as falling off of activated carbon may occur during sheet processing or filter processing. It is not preferable. Examples of a method for measuring the median diameter of the powdered activated carbon (A) include a laser diffraction particle size distribution measuring device.

  The powdered activated carbon (A) mixing ratio needs to be 40 to 80% by mass, and preferably 50 to 70% by mass. When the mixing ratio of the powdered activated carbon (A) is less than 40% by mass, it is necessary to increase the ratio of the relatively expensive fibrous activated carbon (B) in order to maintain the water purification performance, which is not preferable because the raw material cost increases. On the other hand, when the mixing ratio of powdered activated carbon (A) exceeds 80% by mass, the strength of the sheet itself is lowered, and it becomes difficult not only to process and filter the sheet, but also to cause coal dust leakage and clogging. Therefore, it is not preferable.

  Powdered activated carbon (A) can be manufactured by pulverizing inexpensive granular activated carbon to a predetermined particle size by a known technique such as using a crusher such as Zegomir, ball mill, jet mill, etc., without classification. It can be used as it is.

The fibrous activated carbon (B) used for the activated carbon sheet for water purification of the present invention is activated carbon having a fibrous form and having a predetermined amount of micropores and mesopores inside the activated carbon surface and inside. The fibrous activated carbon (B) is preferably one having a specific surface area of 550 m ² / g or more when formed into a sheet, and is not particularly limited as long as the water purification performance does not deteriorate. System, resin system, cellulosic fibrous activated carbon can be used.

Preferably the specific surface area of the activated carbon fiber (B) is a 600~2500m ² / g, more preferably 650~2000m ² / g, more preferably from 700~1500m ² / g. When the specific surface area is less than 600 m ² / g, it is difficult to sufficiently adsorb and remove low molecular weight compounds represented by trihalomethane, which is the subject of the present invention. On the other hand, when it exceeds 2500 m ² / g This is not preferable because not only the strength of the activated carbon itself may be lowered but also the cost may be increased.

  The fiber diameter of the fibrous activated carbon (B) is preferably 5 to 30 μm, and more preferably 10 to 25 μm. If the fiber diameter is less than 5 μm, the pressure loss of the filter may increase or the filter may become clogged. When the fiber diameter exceeds 30 μm, the contact efficiency is lowered, and as a result, the water purification performance is lowered.

  The fibrous activated carbon (B) mixing ratio needs to be 2 to 30% by mass, and preferably 5 to 20% by mass. When the fibrous activated carbon (B) mixing ratio is less than 2% by mass, the sheet heat shrinks during drying during papermaking, resulting in tearing and tearing due to perforations in the sheet, not only significantly reducing production efficiency, Filtering becomes difficult because the strength of the sheet itself is also reduced. Moreover, since it becomes easy to clog when it is set as a water purification filter other than that, it is not preferable. On the other hand, when the fibrous activated carbon (B) mixing ratio exceeds 30% by mass, it is difficult to consolidate the sheet, and it may not be possible to increase the density of the filter. As a result, the water purification performance per filter volume decreases. Furthermore, it leads to an increase in raw material cost, which is not preferable.

  The heat-fusible fiber (C) used for the activated carbon sheet for water purification of the present invention is preferably a heat-fusible fiber formed of two or more polymers having different melting points or softening points, and a high melting point polymer is used as a core component. A fiber having a core-sheath structure having a low melting point polymer as a sheath component is particularly preferable from the viewpoint of easy heat treatment when forming a sheet or a filter medium. Examples of the fiber having a core-sheath structure include, for example, a polyolefin-based fiber having a core part made of polypropylene and a sheath part made of modified polyethylene, a core part made of polyethylene terephthalate and a sheath part made of polyolefin, and a core part made of polyethylene terephthalate and a sheath part made of polyethylene. Examples thereof include composite fibers such as polyester fibers made of low melting point (low softening point) polyester.

The fiber diameter of the heat-fusible fiber (C) is preferably 1 to 30 μm, and more preferably 10 to 25 μm. If the fiber diameter is less than 1 μm, the pressure loss of the filter may be increased or clogged, and if the fiber diameter exceeds 30 μm, the adhesion point as a binder with other constituent members decreases, As a result, the peel strength of the sheet may be reduced, and it may not be possible to filter.
The fiber length of the heat-fusible fiber (C) is preferably 1 to 20 mm, and more preferably 2 to 10 mm. If the fiber length is less than 1 mm, the other constituent members may not be entangled well and the meaning of the binder may be lost. If the fiber length exceeds 20 mm, dispersion may be difficult during slurry preparation.

  The mixing ratio of the heat-fusible fiber (C) needs to be 5 to 15% by mass. When the mixing ratio of the heat-fusible fiber (C) is less than 5% by mass, it leads to a decrease in the peel strength of the sheet, and the resultant activated carbon sheet is wound and the heat-bonded roll is cut to a predetermined length It is not desirable because it may become a bowl-like shape and a cylindrical filter with smooth both ends may not be obtained. On the other hand, when the mixing ratio of the heat-fusible fiber (C) exceeds 15% by mass, the ratio of the activated carbon in the activated carbon sheet is lowered, and as a result, the water purification performance per filter volume is lowered, which is not desirable.

  The pulp (D) used in the activated carbon sheet for water purification of the present invention is not particularly limited as long as it can physically entangle and capture the powdered activated carbon (A), and is not limited to cellulose, acrylic, Examples include polyethylene-based pulp.

  The fiber diameter of the pulp (D) is preferably 5 to 30 μm, and more preferably 10 to 25 μm. When the fiber diameter is less than 5 μm, the pressure loss of the filter may increase or clogging may occur. When the fiber diameter exceeds 30 μm, the powdered activated carbon (A) may be physically entangled and captured. It becomes difficult and it is necessary to increase the ratio of the pulp. As a result, the amount of activated carbon in the sheet decreases, and the water purification performance per filter volume may decrease.

  The mixing ratio of the pulp (D) needs to be 5 to 15% by mass. When the mixing ratio of the pulp (D) is less than 5% by mass, the powdery activated carbon is not captured when the wet papermaking sheet is formed, which is not desirable. On the other hand, when the mixing ratio of the pulp (D) exceeds 15% by mass, not only the water permeability deteriorates and the possibility of clogging increases, but also the ratio of the activated carbon in the activated carbon sheet decreases, and as a result, per filter volume. This is not preferable because the water purification performance decreases.

The basis weight of the water purification activated carbon sheet of the present invention is required to be 80~170g / ^{m 2,} it is preferably 100 to 150 g / ^{m 2.} When the basis weight is less than 80 g / m ² , the powdered activated carbon tends to fall off from the sheet when the activated carbon sheet is obtained by the wet papermaking method, or the texture is deteriorated. On the other hand, when the basis weight exceeds 170 g / m ² , the sheet flexibility is lost, which may make it difficult to wind the sheet during filter processing.

The peel strength of the activated carbon sheet for water purification of the present invention is required to be 10 g / 20 mm or more, and preferably 20 g / 20 mm or more. When the peel strength of the sheet is less than 10 g / 20 mm, since the adhesive force between the sheets is weak, there is a possibility that when the sheet is cut to a predetermined length, a cylindrical filter with smooth both ends cannot be obtained. Therefore, it is not preferable.
The above peel strength is obtained by superposing two activated carbon sheets, applying a pressure of 4.5 kgf / cm ² for 40 seconds at a pressing temperature of 85 ° C. using a hot press machine, and making the obtained laminated activated carbon sheet 20 mm wide × 50 mm long It is obtained by cutting and measuring the peel strength (g / 20 mm) at a peel speed of 300 mm / min and a peel angle of 165 ° with a peel strength tester.

The specific surface area of the activated carbon sheet for water purification of the present invention is preferably 550 m ² / g or more, and more preferably 650 m ² / g or more. When the specific surface area of the sheet is less than 550 m ² / g, not only the total trihalomethane removal performance but also other basic performance such as removal of free chlorine and mold odor (2-MIB) may be remarkably deteriorated. In order to set the specific surface area of the activated carbon sheet for water purification to 550 m ² / g or more, powdered activated carbon having a specific surface area of 800 m ² / g or more may be used.

As described above, the activated carbon sheet for water purification of the present invention is powdered activated carbon (A) 40-80% by mass, fibrous activated carbon (B) 2-30% by mass, and heat-fusible fiber (C) 5-5. 15% by mass and pulp (D) 5 to 15% by mass, and the total of these is a wet papermaking sheet consisting of 100% by mass. For reasons of removing soluble lead, the mixture is: Furthermore, it is preferable that 3-20 mass% of weak acid type polyacrylate type | system | group ion exchange fibers (E) are contained, and the sum total is 100 mass%. In the weak acid type polyacrylate ion exchange fiber (E), the terminal functional group is preferably substituted with Ca or Na.
The fiber diameter of the ion exchange fiber (E) is preferably 5 to 30 μm, and more preferably 10 to 25 μm. If the fiber diameter is less than 5 μm, it may be difficult to disperse at the time of slurry preparation. If the fiber diameter exceeds 30 μm, the contact efficiency is lowered, so that the soluble lead removal performance may be lowered.
Moreover, it is preferable that the fiber length of an ion exchange fiber (E) is 1-20 mm, and it is more preferable that it is 2-10 mm. If the fiber length is less than 1 mm, there is a possibility of dropping off from the sheet during papermaking. If the fiber length exceeds 20 mm, the ion-exchange fibers are not uniformly dispersed in the sheet, resulting in damaging, and the layer thickness of the SV or filter. However, it is not preferable because soluble lead may leak from the beginning.
The mixing ratio of ion exchange fibers (E) is preferably 3 to 20% by mass, and more preferably 4 to 10% by mass. When the ion exchange fiber (E) mixing ratio is less than 3% by mass, although it depends on the SV and the layer thickness of the filter, it is not preferable because soluble lead may leak from the beginning. On the other hand, when the ion exchange fiber (E) mixing ratio exceeds 20% by mass, the ion exchange fiber swells during paper making and retains a lot of moisture, so that the drying efficiency of the sheet deteriorates and the sheet cannot be dried. This is not preferable because paper breaks frequently occur and a good sheet cannot be obtained, resulting in a decrease in productivity and an increase in cost.

  The activated carbon sheet for water purification of the present invention comprises powdered activated carbon (A), fibrous activated carbon (B), heat-fusible fiber (C), pulp (D), and, if necessary, ion-exchange fiber (E). However, as long as the effect of the present invention is not impaired, it can be used in combination with other filter media. Examples of other filter media include ion exchange resins, natural stones, ceramics, calcium sulfite, hollow fibers, and nonwoven fabrics. When using other filter media, only one type may be used, or two or more types may be used. Further, in order to impart antibacterial properties to the activated carbon sheet for water purification and the water purification filter, fibrous activated carbon, powdered activated carbon, zeolite and the like containing silver or a silver compound may be used in combination. Further, a paper strength enhancer or the like may be added to improve the strength of the sheet.

  The activated carbon sheet for water purification of the present invention can be produced by wet papermaking a mixture of powdered activated carbon (A), fibrous activated carbon (B), heat-fusible fiber (C), and pulp (D). For example, powdered activated carbon (A), fibrous activated carbon (B), heat-fusible fiber (C), and pulp (D) were mixed, sheared, and uniformly dispersed using a device such as a pulper, beater, or refiner. What is necessary is just to adjust to arbitrary basis weights by producing a slurry and pouring the obtained slurry on a wire at a predetermined flow rate, and dehydrating. Thereafter, the sheet may be produced by a known technique such as drying the sheet with a dryer part through a press part, smoothing the surface of the sheet with a calendar part, and winding it with a reel. The thickness of the sheet may be adjusted to an arbitrary thickness with a hot press roller or the like.

The water purification filter of the present invention is a filter formed by molding the above-mentioned activated carbon sheet for water purification. Apparent density of the water purification filter is preferably ^{0.35~0.55g / cm 3, 0.40~0.50g / cm} 3 is more preferable. An apparent density of less than 0.35 g / cm ³ is not preferable because the removal performance per filter volume may be reduced. On the other hand, when the apparent density exceeds 0.55 g / cm ³ , although it depends on the size (layer thickness) of the filter, it is not preferable because the pressure loss of the filter may increase or the filter may become clogged.

The water purification filter of the present invention preferably has a total trihalomethane removal performance of 15 L / cm ³ or more at a space velocity (SV) of 500 / h. Depending on the size and type of the water purifier, if the removal performance is less than 15 L / cm ³ , for example, the filter life will be extremely short when used in a small, large flow water purifier, and the frequency of filter replacement Increases, which is not preferable.
Furthermore, in the water purification filter of the present invention, the pressure loss at a space velocity (SV) of 500 / h is preferably 0.10 MPa or less, and more preferably 0.05 MPa or less. If the pressure loss exceeds 0.10 MPa, for example, when used as a water purifier, the flow rate may not be secured, which is not preferable.

As a molding method for obtaining a water purification filter, the activated carbon sheet for water purification of the present invention is wound and heat treated to form a columnar or cylindrical filter, or the sheets are laminated and punched into an arbitrary shape and a filter. However, it is not limited to these.
The heat treatment conditions for the sheet at the time of molding differ depending on the melting point of the heat-fusible fiber (C) to be used, but it is generally preferable to fuse at 110 to 160 ° C. If the temperature is too high, the thermoplastic fiber (C) melts and flows, and there arises a problem that the powdered activated carbon (A) and the fibrous activated carbon (B) are coated to lower the water purification performance. Moreover, when the temperature is too low, heat fusion does not occur, and there is a problem that molding cannot be performed.

  The use of the activated carbon sheet for water purification and the water purification filter of the present invention includes, for example, commercial uses such as water purifiers, alkali ion water conditioners, pure water production apparatuses, water softeners, etc. It becomes possible.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these. The characteristics of the activated carbon sheet for water purification and the water purification filter were measured by the following methods.

<Peel strength (g / 20mm)>
The peel strength of the activated carbon sheet for water purification is such that two activated carbon sheets are superposed, a pressure of 4.5 kgf / cm ² is applied for 40 seconds at a press temperature of 85 ° C. using a hot press machine, and the resulting laminated activated carbon sheet is 20 mm wide. The film was cut to a length of 50 mm, and the peel strength (g / 20 mm) at a peel speed of 300 mm / min and a peel angle of 165 ° was measured with a peel strength tester.

<Specific surface area (m ² / g)>
The specific surface area of the activated carbon sheet for water purification was calculated based on the nitrogen adsorption isotherm at 77.4K. Specifically, a nitrogen adsorption isotherm was created as follows. The activated carbon sheet was cooled to 77.4K (the boiling point of nitrogen), nitrogen gas was introduced, and the nitrogen gas adsorption amount V [cc / g] was measured by the volumetric method. At this time, the pressure P [hPa] of the nitrogen gas to be introduced is gradually increased, and the value obtained by dividing by the saturated vapor pressure P ₀ [hPa] of the nitrogen gas is set as the relative pressure P / P ₀ , and the adsorption amount with respect to each relative pressure is plotted. Thus, a nitrogen adsorption isotherm was created. The adsorption amount of nitrogen gas was carried out using a commercially available automatic gas adsorption amount measuring device (trade name “AUTOSORB-6” (manufactured by QUANTCHROME)). In the present invention, the specific surface area was determined according to the BET method based on the nitrogen adsorption isotherm. This analysis used the analysis program attached to the said apparatus.

<Apparent density (g / cm ³ )>
The apparent density of the water purification filter was determined by drying the filter with the inner layer and outer layer nonwoven fabric removed at 80 ° C. for 3 hours in a hot air dryer, cooling to room temperature in a desiccator, and weighing the mass with an electronic balance. It is a value (g / cm ³ ) obtained by dividing (g) by the filter volume (cm ³ ).

<Pressure loss>
After sealing both ends of the water purification filter with a silicone sealant (made by Cemedine), ion exchange water loaded in a stainless steel housing and purified by a 0.1 μm filter is passed from outside to inside at a predetermined flow rate. After maintaining the flow rate for a minute, the pressure loss (MPa) was measured with a Bourdon tube pressure gauge.

<Total trihalomethane removal performance>
After sealing both ends of the water purification filter with silicone sealant (Cemedine), the total trihalomethane concentration in ion-exchanged water loaded in a stainless steel housing and purified by a filter with a filtration accuracy of 0.1 μm is applied according to JIS S 3201. The adjusted raw water is added with trihalomethanes so that becomes 100 ± 20 ppb, and is passed from the outside to the inside at a predetermined flow rate. The total trihalomethane concentration is quantitatively measured by headspace gas chromatography before and after the inflow of the filter. did. At this time, before and after passing through the activated carbon layer, the point where the total trihalomethane concentration in the effluent with respect to the influent becomes 20% or more is defined as the breakthrough point, and the total filtered water amount (L) up to the breakthrough point is defined as the filter volume (cm ^The value divided by ³ ) was defined as the total trihalomethane removal performance (L / cm ³ ).

The raw materials used in Examples, Reference Examples and Comparative Examples are as follows.
<Powdered activated carbon (A)>
A1: Eggplant granular activated carbon (manufactured by Kuraray Chemical Co., Ltd .: GW60 / 150THM, specific area 1000 m ² / g) was pulverized with Zegomyle so that the median diameter was 80 μm to obtain powdered activated carbon (A1).
A2: In the same manner as A1, the granular activated carbon was crushed so that the median diameter was 20 μm to obtain powdered activated carbon (A2).
A3: In the same manner as in A1, granular activated carbon was crushed so that the median diameter became 150 μm to obtain powdered activated carbon (A3).

<Fibrous activated carbon (B)>
Made by Adore; W-10, specific surface area 1000 m ² / g
<Heat-bonding fiber (C)>
Core-sheath type heat-fusible polyester fiber (manufactured by Unitika; Melty 4080, fiber diameter 12 μm, fiber length 5 mm)
<Pulp (D)>
Acrylic pulp (Nippon Exlan; Bi-PUL)
<Weak acid type polyacrylate ion exchange fiber (E)>
Ca-substituted polyacrylate ion exchange fiber (manufactured by Unitika; A-02CA)

Example 1
Powdered activated carbon (A1) 77% by mass, fibrous activated carbon (B) 5% by mass, heat-fusible fiber (C) 11% by mass, pulp (D) 7% by mass / M ² , sheet thickness 0.33 mm). The obtained activated carbon sheet had a specific surface area of 820 m ² / g and a peel strength of 53 g / 20 mm.
An inner-layer nonwoven fabric (manufactured by Unitika; Elves S0303) is first wound on a stainless steel pipe having a diameter of 30 mm, and then the obtained activated carbon sheet is wound until a predetermined outer diameter is reached, and heat treatment is performed at 150 ° C. for 3 hours in a heat treatment furnace. Then, after cooling to room temperature, the outer layer nonwoven fabric (manufactured by Unitika; Elves S0303) was spirally wound, placed again in a heat treatment furnace, heated at 150 ° C. for 10 minutes, allowed to cool and then extracted from the stainless steel pipe, using a cutting machine The obtained roll was cut to a predetermined length to obtain a cylindrical filter having an outer diameter of 65 mm / an inner diameter of 30 mm × a length of 125 mm. The apparent density of the obtained filter was 0.43 g / cm ³ .

Examples 2-8, Reference Example 1, Comparative Examples 1-3, 5-12
Table 1 shows the types and contents of powdered activated carbon (A), fibrous activated carbon (B), heat-fusible fiber (C), pulp (D), and weak acid polyacrylate ion-exchange fiber (E). A wet papermaking sheet and then a cylindrical filter were prepared in the same manner as in Example 1 except for the above changes.

Comparative Example 4
A cylindrical filter of φ65 / 30 × 125 L was obtained from a mixture of 80% by mass of powdered activated carbon (A1), 10% by mass of fibrous activated carbon (B) and 10% by mass of pulp (D) by a wet molding method. The apparent density of the obtained filter was 0.35 g / cm ³ .

  Table 1 shows the characteristics of the activated carbon sheet for water purification comprising the wet papermaking sheets obtained in Examples, Reference Examples and Comparative Examples, and the water purification filter comprising a cylindrical filter.

As shown in Table 1, each of the water purification filters of Examples 1 to 8 and Reference Example 1 of the present invention has a very excellent total trihalomethane removal performance of 17 to 24 L / cm ³ and a small pressure loss. It was a thing. In Example 3, even when the SV was increased from 500 / h to 1000 / h, the performance was hardly deteriorated.
Furthermore, when the soluble lead removal performance of the water purification filters of Examples 2 to 8 and Reference Example 1 containing ion exchange fibers was confirmed according to JIS S 3201, Example 2 was also found at the breakthrough point of total trihalomethanes. -6, Example 8 and Reference Example 1 had a sufficient removal rate of 96% or more, and Example 7 also had a sufficient removal rate of 84%.

On the other hand, in Comparative Example 1, an attempt was made to obtain a wet papermaking sheet from a mixture having a high mixing ratio of powdered activated carbon (A1). However, the activated carbon was largely removed from the sheet, and a good sheet was not obtained.
In Comparative Example 2, paper was made in the same manner as in Example 2 except that the fibrous activated carbon (B) was not used, but the sheet was frequently perforated and torn. The produced filter had a pressure loss of 0.05 MPa, which is at least twice as high, and the total trihalomethane removal performance was as low as 13 L / cm ³ . It is estimated that the filter was only partially used, such as uneven density in the filter due to the poor texture of the sheet, and drifting when water passed. The filter of Comparative Example 3 had a high mixing ratio of bulky fibrous activated carbon (B), so the density was difficult to increase. As a result, the total trihalomethane removal performance was as low as 13 L / cm ³ .
The filter of Comparative Example 4 is a filter having an apparent density of 0.35 g / cm ³ produced by a wet molding method, and the pressure loss is 4 times or more despite the density being lower than that of Examples 1 to 3. It was expensive.
In Comparative Example 5, an attempt was made to cut the roll obtained in the same manner as in Example 1 to a predetermined length using a cutting machine, but the mixing ratio of the heat-fusible fiber (C) was low, and the adhesive strength between the activated carbon sheets was low. Since it was not sufficient, it became bowl-shaped and a cylindrical filter with a smooth end face could not be obtained. The filter of Comparative Example 6 had a high mixing ratio of the heat-fusible fiber (C), so that the mixing ratio of the activated carbon decreased and the water purification performance per filter volume decreased.
In Comparative Example 7, an attempt was made to obtain a wet papermaking sheet from a mixture having a low mixing ratio of pulp (D). However, the powdered activated carbon often dropped from the sheet, and a good sheet could not be obtained. The filter of Comparative Example 8 had a high mixing ratio of pulp (D), resulting in a decrease in water permeability and a high pressure loss.
In Comparative Example 9, an attempt was made to obtain a wet papermaking sheet from a mixture having the same structure as Example 1 except that powdered activated carbon (A2) having a median diameter of 20 μm was used. There were too many, and a favorable sheet was not obtained. In Comparative Example 10, an attempt was made to obtain a wet papermaking sheet from a mixture of powdered activated carbon (A3) having a median diameter of 150 μm, but the particle diameter was large during the papermaking process and hot pressing for adjusting the thickness of the sheet. The activated carbon dropped out and a good sheet could not be obtained.
In Comparative Example 11, a wet papermaking sheet having a basis weight of 70 g / m ² was obtained, but holes and tears were partially generated, and the variation in sheet thickness was large. In Comparative Example 12, a wet papermaking sheet having a basis weight of 180 g / m ² and a sheet thickness of 0.50 mm was obtained. As in Example 1, the inner layer nonwoven fabric was previously wound around a stainless pipe having a diameter of 30 mm, and then an attempt was made to wind the obtained sheet. However, the sheet could not be wound around the pipe, and was filtered. I couldn't.

  From the above, the activated carbon sheet for water purification and the water purification filter of the present invention are excellent in removal performance against heavy metals such as organic halogen compounds represented by total trihalomethane and soluble lead, and have a small pressure loss. It can be suitably used for an ion water conditioner, a pure water production apparatus, a water softener and the like.

Claims (5)

Powdered activated carbon (A) 50-80% by mass, fibrous activated carbon (B) 2-30% by mass, heat-fusible fiber (C) 5-15% by mass with a fiber diameter of 10-25 μm, fiber A wet papermaking sheet comprising a cellulose or acrylic pulp (D) having a diameter of 5 to 30 μm and a total of 100% by mass of these, and the powdery activated carbon ( The median diameter of A) is 30 to 120 μm, the basis weight of the sheet is 80 to 170 g / m ² , and the peel strength of the laminated sheet obtained by thermally bonding two sheets is 10 g / 20 mm or more. Activated carbon sheet for water purification. The activated carbon sheet for water purification according to claim 1, wherein the sheet has a specific surface area of 550 m ² / g or more. The activated carbon sheet for water purification according to claim 1 or 2, wherein the mixture further contains 3 to 20% by mass of a weak acid type polyacrylate ion exchange fiber (E), and the total is 100% by mass. A water purification filter formed by molding the activated carbon sheet according to any one of claims 1 to 3, and having an apparent density of 0.35 to 0.55 g / cm ³ . 5. The water purification filter according to claim 4, wherein the total trihalomethane removal performance at a space velocity (SV) of 500 / h is 15 L / cm ³ or more and the pressure loss is 0.10 MPa or less.