JP7318115B2 - Filter for water purification and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a water purification filter and its manufacturing method, and more particularly to a water purification filter using an activated carbon fiber sheet and its manufacturing method.

A water purification filter is used to purify water such as tap water. Water purification filters are used in a variety of applications. For drinking water, for example, they are sometimes used to remove residual chlorine, components with unpleasant odors, and the like.

As a filter for water purification, it is known to use powdery activated carbon or activated carbon fiber having adsorption action. Since activated carbon fibers can be prepared with excellent adsorption and desorption performance, they are suitable as filter materials for water purification with high purification performance. However, in general, activated carbon fiber itself tends to be more brittle and more likely to collapse than other synthetic fibers, and it may be difficult to maintain its shape against water flow, so it has been processed and used in various forms. .

As a filter using activated carbon fiber, for example, (1) an activated carbon fiber layer is wound so as to constitute a thick wall portion of a hollow cylindrical body, and a water-permeable nonwoven fabric is wound around the inner and outer peripheral surfaces, respectively. (2) The inner and outer layers of the cylindrical body are made of nonwoven fabric, and the layer between the inner and outer layers is activated carbon. A filter for water purification, which is composed of a mixed paper made of fibers and heat-fusible fibers, and in which both ends of a cylindrical body are fixed with a thermoplastic resin (for example, Patent Document 2), (3) Fibrous activated carbon and heat-fusible A wet papermaking sheet containing fibers and the like, which is a heat-processed activated carbon sheet for water purification (for example, Patent Document 3), and the like have been proposed.

Japanese Utility Model Laid-Open No. 6-72619 JP-A-9-239214 JP-A-2015-110228

As described above, activated carbon fibers have been used in water purification filters in various forms. However, in order to maintain a high purification performance, it is desired to increase the amount of activated carbon fiber filled, but the activated carbon fiber sheet has a low tensile strength and cannot be tightly wound, so it has to be wound loosely. As a result, it becomes difficult to increase the filling amount of the activated carbon fiber sheet, and moreover, water accumulates over time between the loosely wound activated carbon fiber sheets, which can easily cause breakage such as rupture due to water pressure. rice field. One of the causes of such damage is thought to be that the pressure loss increases during the use of the water purification filter.

In view of the above situation, one of the problems to be solved by the present invention is that a water purification filter using activated carbon fiber can continuously exhibit high purification performance and low pressure loss performance. It is to develop things.

The present invention can be grasped from various aspects, and means for solving the problems include, for example, the following.
[1] A cylindrical body having a roll structure in which multiple sheets including at least two types of sheets, an activated carbon fiber sheet and a water-permeable substrate sheet, are wound together,
The tensile strength (MD) of the water-permeable base sheet is higher than the tensile strength (MD) of the activated carbon fiber sheet.
Filter for water purification.
[2] The water purification filter according to [1] above, wherein the inner peripheral portion and the outer peripheral portion of the tubular body are covered with the water-permeable substrate sheet.
[3] The water purification filter according to [1] or [2] above, wherein the water-permeable base sheet is a nonwoven fabric sheet having a tensile strength (MD) of 0.30 to 2.00 kN/m.
[4] The water purification filter according to any one of [1] to [3] above, wherein the activated carbon fiber sheet has a specific surface area of 1200 to 2400 m ² /g.
[5] The water purification filter according to any one of [1] to [4] above, wherein the packing density of the activated carbon fiber sheet in the tubular body is 0.05 to 0.09 g/cm ³ . .
[6] preparing at least two sheets, an activated carbon fiber sheet and a water-permeable substrate sheet having a higher tensile strength (MD) than the activated carbon fiber sheet;
forming a cylindrical body by winding a multiple sheet including the activated carbon fiber sheet and the water-permeable base sheet;
A method for manufacturing a filter for water purification.
[7] After winding the water-permeable base sheet in a single layer to form an inner peripheral portion, a multiple sheet containing the activated carbon fiber sheet and the water-permeable base sheet is formed so that the water-permeable base sheet is forming a cylindrical body by winding it so that it appears on the outer peripheral surface;
A method for producing a water purification filter according to [6] above.
[8] The water-permeable base sheet is a nonwoven fabric sheet,
The nonwoven fabric sheet before winding has a tensile strength (MD) of 0.30 to 2.00 kN/m, a sheet density of 0.07 to 0.16 g/cm ³ , and a sheet thickness of The method for producing a water purification filter according to the above [6] or [7], which is 0.10 to 0.70 mm.

According to one embodiment of the present invention, it is possible to provide a water purifying filter that is less likely to deteriorate in its ability to remove residual chlorine and the like and less likely to increase in pressure loss even when used continuously.
Moreover, according to one embodiment of the present invention, such a water purification filter can be easily produced.

FIG. 1 is a perspective view of an example of the water purification filter of the present invention. FIG. 2 is a vertical cross-sectional view of an example of the water purification filter of the present invention. FIG. 2 is a diagram showing an end face perpendicular to the long axis direction (winding axis direction) according to an example of the water purification filter of the present invention.

Embodiments of the present invention will be described below. The embodiments shown below provide specific descriptions for easy understanding of the present invention, but the present invention is not limited to the embodiments shown below, and each component is the gist of the present invention. can be changed as appropriate within a range that does not deviate from. Moreover, the embodiments of the present invention may be described below with reference to the drawings. In each drawing, the shape, size, arrangement, etc. of the constituent elements are schematically shown to facilitate understanding of the present invention, and can be changed as appropriate without departing from the gist of the present invention. In each figure, the same components are denoted by the same reference numerals, and redundant description may be omitted.

Unless otherwise specified, the description "AA to BB" with respect to the numerical range means "AA or more and BB or less" (here, "AA" and "BB" indicate arbitrary numerical values). In addition, the units for the lower and upper limits are the same as the units immediately following the latter (that is, "BB" here) unless otherwise specified.

In the description of the present invention, the term "pore size" refers to the diameter or width of the pore, not the radius of the pore, unless otherwise specified.

1. Water Purification Filter The water purification filter of the present invention is a cylindrical body having a roll structure in which multiple sheets including at least two types of sheets, an activated carbon fiber sheet and a water-permeable substrate sheet, are rolled up.
The tensile strength of a sheet is classified into MD (Machine Direction) and CD (Cross Direction) depending on the tensile direction. One embodiment of the water purification filter of the present invention includes a mode in which at least one of tensile strength (MD) and tensile strength (CD) is higher in the water-permeable substrate sheet than in the activated carbon fiber sheet. , preferably the water-permeable substrate sheet has higher tensile strength (MD) than the activated carbon fiber sheet, or the water-permeable substrate sheet has higher tensile strength (MD) and tensile strength (CD) than the activated carbon fiber sheet. Embodiments include those in which the sheet of material is taller.
In another embodiment of the present invention, the water-permeable base sheet may have a tensile strength (MD) greater than a tensile strength (CD).
Moreover, in another embodiment of the present invention, the inner peripheral portion and the outer peripheral portion of the cylindrical body may be covered with the water-permeable base sheet.

1.1. First Embodiment of Water Purification Filter of the Present Invention A first embodiment of the present invention will be described with reference to FIGS. 1 and 2 are diagrams showing a water purification filter that is one embodiment of the present invention. FIG. 3 is a diagram showing one end surface of the water purification filter of the first embodiment of the present invention.

The water purification filter 1 shown in FIG. 1 is provided with end caps 12 at both ends of a cylindrical body 11 formed by winding an activated carbon fiber sheet and a water-permeable substrate sheet. By providing end caps at both end portions of the cylindrical body 11, it is possible to prevent loosening of the winding of the sheet constituting the cylindrical body, which facilitates handling as a water purification filter. The water purification filter 1 can be used as a cartridge that can be easily replaced as one unit.

2 is a longitudinal sectional view of the water purification filter shown in FIG. 1. FIG. The cylindrical body 11 has a hollow portion whose center line is the axis indicated by the X-X' line. The inner peripheral portion 11 a and the outer peripheral portion 11 b are each covered with a water-permeable base sheet 111 .

FIG. 3 shows one end face of the water purification filter, showing a state in which a double sheet in which the water-permeable substrate sheet 111 and the activated carbon fiber sheet 112 are superimposed is wound. The tubular body 11, which is the main body of the water purification filter, has a double-sheet winding structure of a water-permeable substrate sheet 111 and an activated carbon fiber sheet 112, as shown in FIG. In the first embodiment, the water-permeable base sheet 111 covers the inner periphery, is wound with a double sheet from the middle, and finally the water-permeable base sheet 111 again covers the outer periphery. In FIG. 3, the edge of the water-permeable base sheet 111 closer to the outer periphery is depicted slightly away from the cylindrical body, but as a product, the edge is wrapped around the cylindrical body and fixed.

1.2. Another embodiment (modification) of the water purification filter
In the first embodiment shown in FIGS. 1 to 3 described above, a continuous water-permeable base sheet is used to cover both the inner peripheral portion and the outer peripheral portion of the cylindrical body with the water-permeable base sheet. there is However, the present invention is not limited to this, and as another embodiment, for example, the inner periphery is covered with a separate water-permeable base sheet, and then the activated carbon fiber sheet and the water-permeable base sheet are stacked. The double sheet may be rolled up, and finally the outer peripheral portion may be covered with the water-permeable base sheet again. Therefore, the number of water-permeable base sheets is not necessarily one, and different types of water-permeable base sheets may be used for each of the inner peripheral portion, the double-sheet portion, and the outer peripheral portion. For example, a water-permeable base sheet suitable for forming the inner periphery may be used. In addition, a water-permeable base sheet suitable for exterior use may be used for the outer peripheral portion. Further, instead of the sheet, a cylindrical core material through which liquid such as water can pass may be used to form the inner peripheral portion of the water purification filter (not shown). The core material may be made of plastic, for example.

In addition, in the first embodiment shown in FIGS. 1 to 3, two sheets, the activated carbon fiber sheet and the water-permeable substrate sheet, are used to form the cylindrical body. However, as another embodiment of the present invention, further sheets may be piled up and rolled up to form a tubular body. That is, the number of sheets to be wound may be three or more. As the third and subsequent sheets, sheets other than the activated carbon fiber sheet and the water-permeable sheet may be used. For example, other adsorptive sheets such as hollow fiber sheets may be used as the third and subsequent sheets.

As another embodiment of the present invention, in place of the end caps shown in FIG. 1, resin or the like may be applied to both ends of the tubular body and solidified to fix the both ends.

1.3. Uses of Water Purification Filter The water purification filter of the present invention can be used for various purposes for the purpose of purifying water, for example, purification of drinking water, purification of high-purity water, purification of polluted water, and the like. mentioned.

1.4. Activated Carbon Fiber Sheet The activated carbon fiber sheet that can be used in the present invention is not particularly limited as long as it is in the form of an activated carbon fiber sheet. The activated carbon fiber sheet can be obtained from a known material or produced by a known method, and examples of the activated carbon fiber sheet that can be used in the present invention include the following embodiments.

<Specific surface area of activated carbon fiber sheet>
The lower limit of the specific surface area of the activated carbon fiber sheet used in the present invention is preferably 1000 m ² /g or more, more preferably 1100 m ² /g or more, still more preferably 1200, 1300 or 1400 m ² /g or more. can be
Generally, a larger specific surface area of the activated carbon fiber sheet used in the present invention is preferable from the viewpoint of adsorption performance. , 2000, 1900, or 1800 m ² /g or less.

By setting the specific surface area within the range described above, it is possible to obtain a water purification filter having excellent ability to remove residual chlorine and the like.

<Total pore volume of activated carbon fiber sheet>
The lower limit of the total pore volume of the activated carbon fiber sheet used in the present invention is preferably 0.45 cm ³ /g or more, more preferably 0.50 cm ³ /g or more, still more preferably 0.55 cm ^{3 .} / g or more.
The upper limit of the total pore volume of the activated carbon fiber sheet used in the present invention is preferably 1.20 cm ³ /g or less, more preferably 1.10, 1.00, 0.95, 0.90, 0. 0.85 cm ³ /g or less, more preferably 0.80 cm ³ /g or less.

By setting the total pore volume within the above range, it is possible to obtain a water purification filter with superior adsorption/desorption performance.

<Average pore diameter (average pore diameter)>
In the context of the present invention, the term "pore size" refers to the diameter or width of the pore, not the radius of the pore, unless otherwise specified.

The lower limit of the average pore diameter of the activated carbon fiber sheet used in the present invention is preferably 1.50 nm or more, more preferably 1.55 nm or more, and still more preferably 1.60, 1.65, or 1.65 nm. 70 nm or more.
The upper limit of the average pore diameter of the activated carbon fiber sheet used in the present invention may be arbitrary, but is preferably 4.00 nm or less, more preferably 3.50, 3.00, 2.50, or 2.00 nm or less. and more preferably 1.80 nm or less.

By setting the average pore diameter within the above range, the sheet can be made more excellent in terms of adsorption and desorption performance.

<Basic weight of activated carbon fiber sheet (weight per unit area)>
The lower limit of the basis weight of the activated carbon fiber sheet used in the present invention is preferably 50.0 g/m ² or more, more preferably 60.0 g/m ² or more, still more preferably 70.0, 80.0 g/m 2 or more. It can be 0, or 90.0 g/m ² or more.
The upper limit of the basis weight of the activated carbon fiber sheet used in the present invention is preferably 200.0 g/m ² or less, more preferably 190.0 g/m ² or less, still more preferably 180.0, 170.0 g/m 2 or less. It can be 0, 160.0, or 150.0 g/m ² or less.
By setting the basis weight within the above range, it is possible to obtain a water purifying filter having excellent ability to remove residual chlorine and the like.

<Filling amount of activated carbon fiber sheet>
The filling amount of the activated carbon fiber sheet used in the water purification filter of the present invention is preferably large from the viewpoint of increasing the ability to remove residual chlorine and the like. On the other hand, if it is too large, it may easily cause breakage depending on various conditions such as the thickness of the sheet and the strength of the tension when winding. In addition, although the packing density of the activated carbon fiber sheet may be increased to increase the packing amount, the pressure loss may increase if the packing density is too high.
A preferred amount of the activated carbon fiber sheet to be filled depends on other conditions as described above, but as an example, the following is the case for one cylindrical body having a length of 250 mm.

The lower limit of the filling amount of the activated carbon fiber sheet is preferably 36 g or more, more preferably 37 g or more, and still more preferably 38 g or more, for one cylindrical body having a length of 250 mm, for example.
The upper limit of the filling amount of the activated carbon fiber sheet is preferably 70 g or less, more preferably 65 g, 60 g or less, and even more preferably 55 g or less per cylinder having a length of 250 mm, for example.

<Filling density of activated carbon fiber sheet>
The packing density (g/cm ³ ) of the activated carbon fiber sheet used in the water purification filter of the present invention is desirably high from the viewpoint of increasing the ability to remove residual chlorine and the like. Increasing the packing density of the fiber sheet may increase the pressure loss. From this point of view, it is preferable to balance the lower limit and the upper limit of the packing density of the activated carbon fiber sheet, specifically as follows.

The lower limit of the packing density of the activated carbon fiber sheet is preferably 0.050 g/cm ³ or higher, more preferably 0.055 g/cm ³ or higher, and even more preferably 0.060 g/cm ³ or higher.
The upper limit of the packing density of the activated carbon fiber sheet is preferably 0.090 g/cm ³ or less, more preferably 0.085 g/cm ³ or less, and even more preferably 0.080 g/cm ³ or less.

<Tensile strength of activated carbon fiber sheet (MD: Machine Direction) (before winding)>
Preferred lower and upper limits of the tensile strength (MD) before winding up of the activated carbon fiber sheet used in the present invention are as follows. The tensile strength before seaming means the tensile strength in the state of the raw material sheet before forming into a cylindrical body.

The lower limit of the tensile strength (MD) of the activated carbon fiber sheet is preferably 0.005 kN/m or more, more preferably 0.010, 0.050 kN/m or more, and more preferably 0.100 kN/m or more. can be
In the present invention, a higher tensile strength (MD) of the activated carbon fiber sheet generally tends to be preferable. It can be small, typically 1.200, 1.000, 0.800, 0.500, 0.400, 0.300, or 0.250 kN/m or less.

By setting the tensile strength (MD) to the above range, it is possible to make an activated carbon fiber sheet having flexibility, and therefore, it is excellent in workability and is difficult to break, and the winding operation for producing a water purification filter. It can be an absorbent material that is easy to handle in such as.

The tensile strength of the activated carbon fiber sheet can be adjusted by adjusting the material of the raw material sheet before carbonizing and activating the activated carbon fiber sheet, the sheet basis weight, the sheet density, the sheet thickness, and the carbonization/activation conditions. can be adjusted.

<Tensile strength (CD: Cross Direction) (before winding)>
Preferred lower and upper limits of the tensile strength (CD) of the activated carbon fiber sheet used in the present invention before winding are as follows.

The lower limit of the tensile strength (CD) of the activated carbon fiber sheet is preferably 0.005 kN/m or more, more preferably 0.010, 0.050 kN/m or more, and more preferably 0.100 kN/m or more. can be
In the present invention, a higher tensile strength (CD) of the activated carbon fiber sheet generally tends to be preferable. It can be small, typically 1.200, 1.000, 0.800, 0.500, 0.400, 0.300, or 0.250 kN/m or less.

By setting the tensile strength (CD) within the range described above, it is possible to obtain a flexible sheet, which is excellent in workability, is resistant to breakage, and can be handled in a seaming operation for producing a water purification filter. can be an absorbent material that is easy to absorb.

<Sheet thickness of activated carbon fiber sheet (before winding)>
Preferred lower and upper limits of the thickness of the activated carbon fiber sheet used in the present invention before winding are as follows. The thickness before winding means the thickness of the raw material sheet before being formed into a cylindrical body. However, in order to measure the thickness of the activated carbon fiber sheet so that the measured value is stable, it is preferable to measure the thickness with a slight load applied. In the description of the present invention, the measured value of the thickness of the activated carbon fiber sheet is indicated using the value when a load of 0.3 kPa is applied, as in the measurement method shown in the section of Examples below.

The lower limit of the thickness of the activated carbon fiber sheet before winding is preferably 0.10 mm or more, more preferably 0.50 mm or more, and still more preferably 1.00, 1.50, 1.80, or 2.00 mm. It can be more than that.
The upper limit of the thickness of the activated carbon fiber sheet before winding is preferably 5.00 mm or less, more preferably 4.50 mm or less, and still more preferably 4.00, 3.50, or 3.00 mm or less. .

By using an activated carbon fiber sheet having a sheet density within the range described above as the activated carbon fiber sheet before crimping, it is possible to obtain a water purification filter having excellent ability to remove residual chlorine and the like and having little pressure loss.

The thickness of the activated carbon fiber sheet can be adjusted by adjusting the type of fiber of the precursor, the thickness and density of the raw material sheet, or by pressing the activated carbon fiber sheet.

<Sheet density of activated carbon fiber sheet (before winding)>
Preferred lower and upper limits of the sheet density before winding up of the activated carbon fiber sheet used in the present invention are as follows. The sheet density before winding means the sheet density in the state of the raw material sheet before forming into a cylindrical body.

The lower limit of the density of the activated carbon fiber sheet before winding is preferably 0.010 g/cm ³ or more, more preferably 0.020, 0.030, 0.040 g/cm ³ or more, and still more preferably It can be 0.050 g/cm ³ or more.
The upper limit of the density of the activated carbon fiber sheet of the present invention is preferably 0.200 g/cm ³ or less, more preferably 0.150 g/cm ³ or less, still more preferably 0.100, 0.080, or 0.080. .070, or 0.060 g/cm ³ or less.

By using an activated carbon fiber sheet having a sheet density within the above range as the activated carbon fiber sheet before seaming, it is possible to obtain a water purification filter that has excellent ability to remove residual chlorine and the like and has little pressure loss.

The density of the activated carbon fiber sheet can be adjusted by adjusting the type of precursor fiber, the thickness and density of the raw material sheet, or by pressing the activated carbon fiber sheet.

<Water content>
The activated carbon fiber sheet used in the present invention preferably has a predetermined moisture content. For example, the lower limit of the moisture content under conditions of 23°C and 50% relative humidity is preferably 1% or more, more preferably 2, 4, 6, or 8% or more, and still more preferably 10% or more. .
Also, the upper limit of the water content under the conditions of 23° C. and 50% relative humidity is preferably 40% or less, more preferably 35% or less, and still more preferably 32, 30 or 28%. By setting the water content in the above range under the above conditions, a water purification filter having excellent adsorptivity can be obtained.

<Methylene blue adsorption performance of activated carbon fiber sheet>
For the activated carbon fiber sheet used in the present invention, methylene blue adsorption performance may be used as an indicator of performance as an adsorbent. The methylene blue absorption performance can be expressed as the methylene blue adsorption amount per activated carbon fiber sheet weight.

The methylene blue adsorption performance of the activated carbon fiber sheet used in the present invention is preferably 100 ml/g or more, more preferably 120 ml/g or more, still more preferably 140, 150 or 160 ml/g or more.
By using such an activated carbon fiber sheet having methylene blue adsorption performance, a water purification filter having excellent adsorption properties can be obtained.

1.5. Water-Permeable Base Sheet The water-permeable base sheet that can be used in the present invention includes the following various embodiments.

<Types of water-permeable base sheet>
The water-permeable base sheet that can be used in the present invention may be a sheet having water-permeability, and may be in the form of woven fabric, knitted fabric, non-woven fabric, or the like. Such a water-permeable base sheet can be obtained from a known product or produced by a known method, and examples of the water-permeable sheet that can be used in the present invention include the following embodiments.

Raw materials for the water-permeable base sheet include, for example, synthetic fibers such as polypropylene, polyethylene, and polyethylene terephthalate. Moreover, not only a single fiber but also a composite fiber containing two or more kinds of materials may be used. As the composite fiber consisting of two or more types, for example, a core-sheath type or side-by-side composite fiber consisting of two types having different melting points may be used, and the adhesiveness to the carbon fiber sheet is further improved by heat fusion. is also possible.
A preferable embodiment of the water-permeable base sheet is, for example, a spunbonded nonwoven fabric composed of synthetic fibers such as polypropylene, polyethylene, polyethylene terephthalate, or the like.

<Tensile strength of water-permeable base sheet (before winding)>
As a preferred embodiment of the present invention, the water-permeable base sheet may have a higher tensile strength than the activated carbon fiber sheet.
For water purification, the shape is highly durable against water flow and is hard to be damaged by using such a water-permeable base sheet overlaid rather than forming a cylindrical body by winding only the activated carbon fiber sheet. Can be a filter.

Tensile strength has MD (Machine Direction) and CD (Cross Direction) depending on the tensile direction.
A preferred embodiment includes, for example, a form in which the tensile strength (MD) of the water-permeable base sheet is higher than the tensile strength (MD) of the activated carbon fiber sheet.
In another preferred embodiment, for example, the tensile strength (MD) of the water-permeable base sheet is higher than the tensile strength (MD) of the activated carbon fiber sheet, and the tensile strength (CD ) is higher than the tensile strength (CD) of the activated carbon fiber sheet.

Regarding the relationship between the tensile strength (MD) and tensile strength (CD) of the water-permeable base sheet, as a preferred embodiment, for example, the tensile strength (MD) of the water-permeable base sheet is Forms higher than (CD) are included.

As described above, the tensile strength of the water-permeable substrate sheet is preferably determined in comparison with the tensile strength of the activated carbon fiber sheet.
The lower limit of the tensile strength (MD) of the water-permeable base sheet is preferably 0.30 kN/m or more, more preferably 0.35 kN/m or more, and more preferably 0.40, 0.45 or 0. .50 kN/m or more.
The upper limit of the tensile strength (MD) of the water-permeable base sheet is not particularly limited and may be arbitrary, but is preferably 2.00 kN/m or less, more preferably 1.90 kN/m or less, and still more preferably. can be 1.80, or 1.70 kN/m or less.

The lower limit of the tensile strength (CD) of the water-permeable base sheet is preferably 0.10 kN/m or more, more preferably 0.20 kN/m or more, and more preferably 0.30 kN/m or more. .
The upper limit of the tensile strength (MD) of the water-permeable base sheet is not particularly limited and may be arbitrary, but is preferably 1.70 kN/m or less, more preferably 1.60 kN/m or less, and still more preferably. can be less than or equal to 1.50 kN/m.

By setting one or both of the tensile strength (MD) and the tensile strength (CD) as in the preferred embodiment described above, a water purification filter that is less likely to be damaged by water pressure or the like can be obtained.

In addition, by setting at least the tensile strength (MD) as in the above-described preferred embodiment, workability can be excellent and handling can be facilitated in seaming work for producing a water purification filter. In addition, since the sheet can be tightly wound, it is possible to manufacture a water purification filter that is less likely to be damaged by water pressure or the like and that suppresses pressure loss.

<Sheet thickness of water-permeable base sheet (before winding)>
Preferred lower and upper limits of the thickness of the water-permeable base sheet used in the present invention before winding are as follows. The thickness before winding means the thickness of the raw material sheet before being formed into a cylindrical body. However, in order to measure the thickness of the water-permeable base sheet so that the measured value is stable, there are cases where it is preferable to measure the thickness with a slight load applied (for example, in the case of a nonwoven fabric). In the description of the present invention, the measured value of the thickness of the water-permeable base sheet is indicated using the value when a load of 0.3 kPa is applied, as in the measurement method shown in the section of Examples below.

The lower limit of the thickness of the water-permeable base sheet before winding is preferably 0.10 mm or more, more preferably 0.13 mm or more, and even more preferably 0.15 or 0.20 mm or more.
The upper limit of the thickness of the water-permeable base sheet before crimping is preferably 0.70 mm or less, more preferably 0.60 mm or less, and even more preferably 0.50 mm or less.

By using a water-permeable base sheet having a sheet density within the range described above as the water-permeable base sheet before crimping, it is possible to obtain a water purification filter that is less likely to be damaged while suppressing the volume of the water-permeable base sheet. . Reducing the volume of the water-permeable base sheet can contribute to relatively increasing the filling amount of the activated carbon fiber sheet.

The thickness of the water-permeable base sheet can be adjusted by adjusting the type of fiber of the precursor, the thickness and density of the raw material sheet, or by pressing the water-permeable base sheet. can.

<Sheet density of water-permeable base sheet (before winding)>
Preferred lower and upper limits of the density of the water-permeable substrate sheet used in the present invention before winding are as follows. The sheet density before winding means the sheet density in the state of the raw material sheet before forming into a cylindrical body.

The lower limit of the density of the water-permeable base sheet before winding is preferably 0.07 g/cm ³ or more, more preferably 0.08 g/cm ³ or more, and still more preferably 0.09 g/cm ³ or more. can be
The upper limit of the density of the water-permeable base sheet of the present invention is preferably 0.50 g/cm ³ or less, more preferably 0.30 g/cm ³ or less, and still more preferably 0.25 or 0.20 g/cm 3 . cm ³ or less.

Although it depends on the material of the water-permeable base sheet, by using a sheet density within the above range as the water-permeable base sheet before winding, it is possible to increase the filling rate of the activated carbon fiber sheet and prevent breakage. It is possible to obtain a water purification filter that does not easily cause

The density of the water-permeable base sheet can be adjusted by adjusting the type of fibers of the precursor, the thickness and density of the raw material sheet, or by pressing the water-permeable base sheet.

2. Method for producing water purification filter In the method for producing a water purification filter of the present invention, an activated carbon fiber sheet and a water-permeable substrate sheet are prepared, and a multiple sheet containing the prepared activated carbon fiber sheet and water-permeable substrate sheet is wound. , forming a cylinder.

The activated carbon fiber sheet and the water-permeable substrate sheet may be rolled up so as to form a roll structure in which they are alternately overlapped. In one embodiment of the present invention, the activated carbon fiber sheet and the water-permeable substrate sheet may be separately prepared and fed and overlapped when they are wound around the shaft core. Further, as another embodiment of the present invention, a double sheet in which an activated carbon fiber sheet and a water-permeable substrate sheet are laminated in advance is prepared, and this is fed and wound around the shaft core. good too.

In one embodiment of the present invention, the water-permeable base sheet used has a higher tensile strength than the activated carbon fiber sheet.

As the sheets to be wound, at least two types of sheets, ie, the activated carbon fiber sheet and the water-permeable substrate sheet, may be used, and other sheets may be prepared and stacked.

In the present invention, "winding up" the sheet means winding the sheet around its axis while applying tension to the sheet. The tension applied to the sheet can be appropriately adjusted to such an extent that the rolled structure of the tubular body to be produced is not loosened and the sheet is not broken.

As another embodiment of the present invention, a water-permeable base sheet is wound in a single layer to form an inner peripheral portion, and then a multi-layered sheet including an activated carbon fiber sheet and the water-permeable base sheet is wrapped into the water-permeable base sheet. A cylindrical body may be formed by winding the elastic base sheet so that it appears on the outer peripheral surface.
In this way, both the inner peripheral portion and the outer peripheral portion can be easily covered with the water-permeable base sheet.

The water-permeable substrate sheet, the activated carbon fiber sheet, and the like that can be used in the production method of the present invention are as described in the section "1. Filter for water purification" above.
As another embodiment of the production method of the present invention, the water-permeable base sheet is a nonwoven fabric sheet, and the nonwoven fabric sheet as a raw material has a tensile strength (MD) of 0.30 to 2 before winding. 00 kN/m, the sheet density can be 0.07-0.16 g/cm ³ and the sheet thickness can be 0.10-0.70 mm.

As described above, tensile strength has MD (Machine Direction) and CD (Cross Direction) depending on the tensile direction. By setting either one or both of the tensile strength (MD) and the tensile strength (CD) as in the preferred embodiment described above, in terms of the manufacturing method, processing such as winding work for producing a water purification filter It has excellent properties and can be easily handled. A preferred embodiment of the manufacturing method includes a form using a water-permeable base sheet having a tensile strength (MD) greater than the tensile strength (CD).

By using such a water-permeable substrate sheet, it is possible to increase the filling amount of the activated carbon fiber sheet in a cylindrical body having a scroll structure, and to tightly wind the scroll structure so that it is difficult to loosen due to water flow or the like. can.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the technical scope of the present invention is not limited to the following examples.

<Example 1>
(1) Activated carbon fiber sheet A needle-punched non-woven fabric made of rayon fiber (3.3 dtex, fiber length 76 mm) with a basis weight of 300 g/m ² is impregnated with a 6-10% aqueous solution of diammonium hydrogen phosphate, squeezed out, and dried. to deposit 8 to 10% by weight. The obtained pretreated nonwoven fabric was heated to 900° C. in 38 minutes in a nitrogen atmosphere. Subsequently, activation treatment was performed for 13.6 minutes in a stream of nitrogen containing water vapor with a dew point of 60° C. at that temperature (ACF-1).

(2) Nonwoven fabric sheet A polypropylene spunbond nonwoven fabric having a basis weight of 20 g/m ² was used as the water-permeable base sheet.

(3) Filter for Water Purification A non-woven fabric sheet was first wound around the shaft core to form the inner periphery. Subsequently, the activated carbon fiber sheet was superimposed on the nonwoven fabric sheet and fed so that the nonwoven fabric sheet was on the outside, and the sheet was further wound. When the diameter of the surface perpendicular to the long axis direction (winding axis direction) of the formed roll exceeds 6.5 cm, the supply of the activated carbon fiber sheet is stopped, and the nonwoven fabric sheet is wound again to form a cylindrical shape. The entire outer perimeter of the body was covered with a nonwoven sheet. The outer peripheral edge of the nonwoven fabric sheet was fixed so that the wound sheet would not loosen, and a water purification filter was obtained.

<Example 2>
(1) Activated carbon fiber sheet Same as Example 1 (ACF-1).

(2) Nonwoven fabric sheet A polypropylene spunbond nonwoven fabric having a basis weight of 60 g/m ² was used as the water-permeable base sheet.

(3) Filter for water purification A filter for water purification was obtained in the same manner as in Example 1.

<Example 3>
(1) Activated carbon fiber sheet A needle-punched non-woven fabric made of rayon fiber (3.3 dtex, fiber length 76 mm) with a basis weight of 300 g/m ² is impregnated with a 6-10% aqueous solution of diammonium hydrogen phosphate, squeezed out, and dried. to deposit 8 to 10% by weight. The obtained pretreated nonwoven fabric was heated to 900° C. in 50 minutes in a nitrogen atmosphere and held at this temperature for 2 minutes. Subsequently, activation treatment was performed for 9 minutes in a stream of nitrogen containing steam with a dew point of 60° C. at that temperature (ACF-2).

(2) Non-Woven Fabric Sheet As the water-permeable base sheet, a polypropylene spunbond non-woven fabric having a basis weight of 20 g/m ² , which is the same as in Example 1, was used.

(3) Filter for water purification A filter for water purification was obtained in the same manner as in Example 1.

<Comparative Example 1>
An activated carbon fiber sheet prepared in Example 1 and a polypropylene spunbond nonwoven fabric having a basis weight of 60 g/m ² were prepared. After winding the water purification filter so that the inner circumference is covered with the nonwoven fabric alone, the activated carbon fiber sheet is wound alone on the nonwoven fabric covering the inner circumference of the water purification filter to cover it, and finally, the nonwoven fabric alone is wrapped again. A filter for water purification was produced by winding with and covering the outer periphery with a non-woven fabric.

<Comparative Example 2>
A commercially available filter for water purification (product name: FMH-B055C, manufactured by Z Kogyo Co., Ltd.) was purchased and used as Comparative Example 2.

<Comparative Example 3>
A commercially available filter for water purification (product name: FMH-C055C, manufactured by Z Kogyo Co., Ltd.) was purchased and used as Comparative Example 3.

<Measurement method>
Various items relating to the physical properties and performance of the activated carbon fiber sheet, the nonwoven fabric sheet and the water purification filter were measured and evaluated by the methods shown below. Various numerical values that define the present invention can be obtained by the following measurement methods and evaluation methods.

(1) Specific surface area Approximately 30 mg of the activated carbon fiber sheet to be measured was sampled, vacuum dried at 200°C for 20 hours, weighed, and measured using a high-precision gas/vapor adsorption measuring device BELSORP-maxII (Microtrac Bell). Measured using The amount of nitrogen gas adsorbed at the boiling point of liquid nitrogen (77K) was measured in a relative pressure range of 10 ^-8 order to 0.990 to create an adsorption isotherm for the sample. This adsorption isotherm is analyzed by the BET method in which the analysis relative pressure range is automatically determined under the conditions of adsorption isotherm type I (ISO9277), and the BET specific surface area per weight (unit: m ² /g) is obtained, This was defined as the specific surface area (unit: m ² /g).

(2) Total pore volume The total pore volume (unit: cm ³ /g) was calculated by the one-point method from the result of the isotherm adsorption line obtained in the above specific surface area section at a relative pressure of 0.960. .

(3) Average pore diameter (also referred to as average pore diameter)
It was calculated by the following formula 1.

[Formula 1]
Average pore diameter (unit: nm) = 4 x total pore volume x 10 ³ ÷ specific surface area

(4) Sheet basis weight Each sheet to be measured is allowed to stand in an environment with a temperature of 23 ± 2 ° C and a relative humidity of 50 ± 5% for 12 hours or more, and the sheet basis weight (unit: g / m ² ).

(5) Sheet thickness Each sheet to be measured is allowed to stand in an environment with a temperature of 23 ± 2 ° C. and a relative humidity of 50 ± 5% for 12 hours or more, and a digital compact thickness gauge FS-60DS (Daiei Kagaku Seiki Seisakusho Co., Ltd. ) was used to measure the sheet thickness (unit: mm) when a load of 0.3 kPa was applied.

(6) Sheet Density Before Filling The density of each sheet was calculated by the following formula 2.

[Formula 2]
Sheet density (unit: g/cm ³ ) = sheet basis weight/sheet thickness/10 ³

(7) Tensile strength (MD), tensile strength (CD)
Each sheet to be measured is allowed to stand in an environment with a temperature of 23 ± 2 ° C. and a relative humidity of 50 ± 5% for 12 hours or more, and from the Machine Direction (MD) direction and the Cross Direction (CD) direction perpendicular thereto, respectively A test piece (width 15 mm, length 50 to 60 mm) is cut so that each direction has a length, and a Tensilon universal testing machine RTG-1210 (A&D Co., Ltd.) is used. The tensile strength was calculated by the following formula 3.

[Formula 3]
Tensile strength (unit: kN/m) = maximum load applied during the test (unit: N) ÷ 15 mm

(8) Moisture content After leaving the activated carbon fiber sheet in an environment with a temperature of 23 ± 2 ° C and a relative humidity of 50 ± 5% for 12 hours or more, 0.5 to 1.0 g of a sample is collected and dried Moisture content (unit: %) was determined from the change in weight when dried at 115±5° C. for 3 hours or more.

(9) Methylene blue adsorption performance Methylene blue adsorption performance (unit: ml/g) was measured according to the methylene blue decolorizing power (unit: ml/g) of powdered activated carbon for water supply (JWWA K113) specified by the Japan Water Works Association.

(10) Filling amount of activated carbon fiber sheet From the total weight of the water purification filter, subtract the weight of the core material, the end cap, the weight of the inner circumference and the outer circumference of the water-permeable base sheet, and obtain the activated carbon fiber sheet and the water-permeable The filling amount (g) of the activated carbon fiber sheet was calculated by distributing it according to the basis weight ratio of the active carbon fiber sheet.

(11) Packing Density The packing density of the activated carbon fiber sheet used for each water purification filter was calculated by the following formula 4.

[Formula 4]
Packing density (unit: g/cm ³ )=filling amount/{(outer radius ² −inner radius ² )π×length}

In Equation 4, the filling amount indicates the filling amount of the activated carbon fiber sheet calculated in (10) above. As shown in Equation 4, the packing density indicates the weight (or abundance ratio) of the activated carbon fiber sheet per unit volume of the water purification filter body.
The outer dimensions of the water purification filter bodies used in Examples 1 to 3 and Comparative Examples 1 to 3 are as follows.
Outer radius: 3.25 cm, inner radius: 1.5 cm, length: 25 cm

(12) Residual chlorine concentration A water purification filter is filled into a 250 mm housing, and water adjusted to 20 ° C. with a residual chlorine concentration of 50 ppm using sodium hypochlorite is flowed from the outside to the inside at a flow rate of 4 L / min. After passing through, sampling was performed, and residual chlorine concentration (ppm) was measured with a portable residual chlorine meter HI 96771 (manufactured by Hanna Instruments Japan). A DPD (diethyl-p-phenylenediamine) reagent was used when the residual chlorine concentration was 0 to 5.00 ppm, and an absorptiometric method using a potassium iodide reagent was used when it was over 5.00 ppm.

(13) Pressure loss A water purification filter is filled in a 250 mm housing, and water adjusted to 20 ° C. with a residual chlorine concentration of 50 ppm using sodium hypochlorite is passed from the outside to the inside at a flow rate of 4 L / min. , the pressure loss (MPa) before and after passage was measured.

(14) Deformation of water purifying filter after passing water After conducting the above (12) pressure loss test, it was visually confirmed whether or not the water purifying filter used for the measurement was deformed.

Tables 1-1 and 1-2 show the results of measuring the physical properties and performance of Examples 1-3 and Comparative Examples 1-3.

1: Water purifying filter, cylindrical body 11: Water purifying filter, 12: End cap 11a: Inner peripheral part, 11b: Outer peripheral part, XX': Axial line (center line)
111: Non-woven fabric sheet, 112: Activated carbon fiber sheet

Claims (8)

At least two types of sheets, an activated carbon fiber sheet and a water-permeable substrate sheet, are included, and the activated carbon fiber sheet and the water-permeable substrate sheet are wound multiple times around the axis such that the activated carbon fiber sheet and the water-permeable substrate sheet are alternately overlapped multiple times. A tubular body having a scroll structure formed by winding and tightening ,
The water-permeable base sheet is a spunbond nonwoven fabric sheet formed of a single fiber selected from the group consisting of polypropylene, polyethylene, and polyethylene terephthalate, or two or more composite fibers selected from the group,
The tensile strength (MD) of the water-permeable base sheet is higher than the tensile strength (MD) of the activated carbon fiber sheet,
The packing density of the activated carbon fiber sheet in the tubular body is 0.055 to 0.09 g/cm 3 ^,
Filter for water purification. The tensile strength (CD) of the water-permeable base sheet is higher than the tensile strength (CD) of the activated carbon fiber sheet,
The tensile strength (MD) of the water-permeable base sheet is higher than the (CD) of the water-permeable base sheet.
The filter for water purification according to claim 1. The water purification filter according to claim 1 or 2 , wherein the inner peripheral portion and the outer peripheral portion of the cylindrical body are covered with the water-permeable base sheet. The water purification filter according to any one of claims 1 to 3 , wherein the water-permeable base sheet is a nonwoven fabric sheet having a tensile strength (MD) of 0.30 to 2.00 kN/m. The water purification filter according to any one of claims 1 to 4 , wherein the activated carbon fiber sheet has a specific surface area of 1200 to 2400 m ² /g. preparing at least two sheets, an activated carbon fiber sheet and a water-permeable substrate sheet having a tensile strength (MD) higher than that of the activated carbon fiber sheet;
The activated carbon fiber sheet and the water-permeable base sheet are wound a plurality of times around the axis so that the activated carbon fiber sheet and the water-permeable base sheet are alternately overlapped a plurality of times to form a rolled cylindrical body. Forming a water purification filter manufacturing method ,
The water-permeable base sheet is a spunbond nonwoven fabric sheet formed of a single fiber selected from the group consisting of polypropylene, polyethylene, and polyethylene terephthalate, or two or more composite fibers selected from the group,
The packing density of the activated carbon fiber sheet in the tubular body is 0.055 to 0.09 g/cm 3 ^,
The manufacturing method . After forming the inner peripheral portion by winding the water-permeable base sheet in a single layer, a multi-layer sheet in which the activated carbon fiber sheet and the water-permeable base sheet are superimposed is wrapped around the outer circumference of the water-permeable base sheet. Form a cylindrical body by winding it so that it appears on the surface,
The manufacturing method of the filter for water purification according to claim 6. The water-permeable base sheet is the spunbond nonwoven fabric sheet,
The spunbond nonwoven fabric sheet before winding has a tensile strength (MD) of 0.30 to 2.00 kN/m, a sheet density of 0.07 to 0.16 g/cm ³ , and a sheet The method for producing a water purification filter according to claim 6 or 7, wherein the thickness is 0.10 to 0.70 mm.

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