JP3143860B2 - Water purification filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water purification filter containing activated carbon fibers, and more particularly to a water purification filter suitable for low water pressure, such as an automatic ice maker or a water heater of a refrigerator.

[0002]

2. Description of the Related Art Generally, drinking tap water supplied to households contains about 1 to 2 ppm of chlorine for sterilization. For this reason, tap water gives a drinker discomfort due to chlorine odor.

[0003] In order to remove this chlorine odor from tap water, it is common practice to deodorize it with a filter made of granular activated carbon or activated carbon fiber. Activated carbon fibers are widely used because they have excellent shapeability and high chlorine removal performance per unit weight as compared with granular activated carbon.

As disclosed in Japanese Utility Model Laid-Open Publication No. Hei 6-72619, a filter using activated carbon fiber is provided with a water-permeable nonwoven fabric on the inner peripheral surface and the outer peripheral surface of a hollow cylindrical body made of activated carbon fiber, respectively. , And both ends of the filter are fixed with solid paraffin.

[0005] In this invention, the nonwoven fabric on the inner and outer peripheral surfaces protects the hollow cylindrical body, prevents the activated carbon fibers from falling off from the side surface of the molded body, and furthermore, the solid paraffin at both ends of the filter is free from the end. Activated carbon fibers are prevented from falling off the part. This prevents the activated carbon fibers from being mixed into the purified water.

[0006]

The nonwoven fabric used for the purpose of preventing the activated carbon fibers from falling off has a small filtration diameter, which causes a problem that water permeability is reduced.
In particular, when the above-described water purification filter is used in a low water pressure environment such as an automatic ice maker or a water heater of a refrigerator, the above problem is remarkable. Further, when a nonwoven fabric using a fiber having a large fiber diameter is used to improve water permeability, a problem occurs in that the filtration diameter of the nonwoven fabric becomes coarse, and the activated carbon fibers fall off.

[0007] In particular, a filter which is always used has a damp condition, so that initial water flow is not a problem. However, when a filter is not used for a long period of time such as a water purifier incorporated in an automatic ice making machine, the filter is dried. However, there is a problem with the initial resistance to water flow from the dry state.

Further, when an external force is applied in the diametrical direction of the filter due to washing of the filter and the like, when the filter is deformed, a crack such as delamination is generated at the end, so that there is a problem that the activated carbon fibers fall off.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a cylindrical filter made of activated carbon fibers has good water permeability at low water pressure and prevents the activated carbon fibers from falling off. It is another object of the present invention to provide a water purification filter suitable for use not only in households but also in automatic refrigerators and water heaters for refrigerators, by preventing mold collapse due to external force.

[0010]

According to the present invention, the inner peripheral layer and the outer peripheral layer of the cylindrical body are each formed of a nonwoven fabric, and the layer between the inner peripheral layer and the outer peripheral layer is formed of a mixture of activated carbon fibers and heat-meltable fibers. In the water purification filter which is made of paper and has both ends of a cylindrical body fixed with a thermoplastic resin, the fibers constituting the nonwoven fabric are a fiber having a fiber diameter of 10 to 50 μm and a fiber having a fiber diameter of 0.5 to 3 μm. And 65% R
H, a filter for water purification characterized by containing fibers having an equilibrium moisture content at 20 ° C. of 5% or more.

[0011] The filter of the present invention allows fluid to permeate in the radial direction from outside or inside the cylindrical body. The fluid passes through a mixed paper made of activated carbon fibers and heat-meltable fibers through the nonwoven fabric. At this time, the surface of the activated carbon fibers is brought into contact with the fluid to remove chlorine and the like contained in the fluid. And the purified fluid passes through the hollow part of the cylinder,
Alternatively, filtration is performed by discharging from the outer peripheral side.

The nonwoven fabric of the present invention has a fiber diameter of 10 to 50 μm.
By using a fiber having a fiber diameter of 0.5 to 3 μm, the passage of activated carbon fibers is prevented, and a good filtration diameter with good water permeability is obtained, so that the activated carbon fibers are prevented from being mixed into purified water, Further, by using a hydrophilic fiber having an equilibrium moisture content of 5% or more at 65% RH and 20 ° C., the nonwoven fabric becomes hydrophilic, and the initial water permeability is excellent even at a low water pressure.

Hereinafter, the present invention will be described in detail. Activated carbon fibers that can be used in the present invention are activated carbon fibers made from filaments or staples such as polyacrylonitrile, rayon, pitch, and phenolic resin, and are not particularly limited with the production method. As the specific surface area of the activated carbon fiber, those having a high chlorine removal performance of 700 m ² / g or more are often used, and those having an appropriate specific surface area can be used according to the application and required characteristics.

The heat-meltable fiber is a fiber that imparts shapeability to the mixed paper and is a heat-meltable fiber such as polyamide, polyester, or polyethylene. Those that do not degrade the performance are better. Specifically, fibers having a melting point higher than the melting point of the thermoplastic resin at both ends of the filter are used. It is preferable to use a core-sheath fiber having a configuration in which the melting point of the core material is higher than that of the sheath material. As such a core-sheath fiber, a core-sheath fiber whose core material is made of polyester and whose sheath material is made of polyethylene is particularly preferably used.

[0015] The mixed paper is composed of activated carbon fibers and hot melt fibers. From the viewpoint that the strength of the mixed paper is maintained and the shapeability of the mixed paper is good, the weight of the activated carbon fiber with respect to the mixed paper is preferably 50 to 80% by weight.

When the content of the activated carbon fibers is more than 80% by weight, the shapeability is reduced, and the activated carbon fibers fall off. 5
If the amount is less than 0% by weight, the purification ability of tap water per weight of the mixed paper or per volume of the cylindrical body is reduced.

In addition, the mixed paper has a difference in the magnitude of distortion between the inner periphery and the outer periphery during or after shaping into a molded article.
The thickness of the mixed paper is preferably 0.3 to 0.6 mm in order to reduce the difference in the magnitude of the strain and maintain the tensile strength of the mixed paper.

The cylindrical body made of the mixed paper has the nonwoven fabric wound around the outside and the inside, respectively.

The nonwoven fabric is necessary not only to prevent the activated carbon fibers from falling off but also to maintain the shape of the cylindrical body.
Functionally, those having good water permeability and filterability are preferred. Further, it is preferable that the filter retains its shape without impairing the functions of the nonwoven fabric and the activated carbon fiber when processed into a water purification filter. Specifically, a nonwoven fabric made of fibers having a melting point higher than the melting point of the thermoplastic resin at both ends of the filter is used.

In the nonwoven fabric, if only fibers having a small fiber diameter are used in order to prevent the activated carbon fibers from falling off, water permeability is impaired. Therefore, the nonwoven fabric has a fiber diameter of 10 so that the opposite properties of preventing the activated carbon fiber from falling off and improving water permeability can be satisfied at the same time.
Fibers distributed to 50 μm and fiber diameter of 0.5 to 3 μm
It is preferable to use a material containing fibers distributed in the polymer.

By using fibers having a fiber diameter of 10 to 50 μm and fibers having a fiber diameter of 0.5 to 3 μm, water permeability to the nonwoven fabric and a fiber diameter of 5 to 10
It is possible to prevent the activated carbon fibers of μm from falling off.

Further, in order to improve the initial water permeability of the nonwoven fabric, it is preferable to use fibers having an equilibrium moisture content of 5% or more. Equilibrium moisture content is 65% RH, 20 based on JIS-L-1015.
Represents the moisture content of the fiber at ° C. Specifically, the nonwoven fabric preferably contains 5 to 15% by weight of a fiber having an equilibrium moisture content of 5% or more.

When the fiber having an equilibrium moisture content of 5% or more is less than 5%, the nonwoven fabric cannot have sufficient hydrophilicity.
Poor initial water permeability. 15% fiber with equilibrium moisture content of 5% or more
When it exceeds, the initial water permeability is improved, but the water permeability after the initial water penetration is deteriorated. Rayon, cotton or the like is used as the fiber having an equilibrium moisture content of 5% or more, and rayon is particularly preferable.

The cut surface is fixed with a thermoplastic resin in order to prevent the activated carbon fibers from falling off from the cut surfaces at both ends of the cylindrical body. Specifically, a copolymer of vinyl acetate and ethylene, or a polyolefin, or a mixture of the copolymer and a polyolefin is preferable, and the melting temperature is 80 to
Those at 180 ° C. are preferred. In addition, use a resin that complies with the Food Sanitation Law.

The present invention will be described with reference to the drawings. FIG.
It is a figure which showed the partial cross section perspective view of the filter for water purification of this invention. FIG. 2 is a schematic diagram before fixing an end of the water purification filter of the present invention with a resin. 1 and 2, reference numeral 1 denotes a mixed paper, 2 denotes a nonwoven fabric, and 3 denotes an end resin fixing portion (hatched portion).

The method for producing the water purification filter of the present invention is as follows. First, a required amount of the nonwoven fabric, the mixed paper, and the nonwoven are wound on a long core rod in this order, and then heated to obtain the hot melt fiber contained in the mixed paper. The non-woven fabric and the mixed paper or the non-woven fabric are heat-set to each other.

Next, the long cylindrical body is cut and extracted from the core rod to obtain a filter having a predetermined length. FIG. 2 shows the state of the filter at this time. Then, the thermoplastic resin melted into a film shape is pressed against the end of the filter, impregnated with the resin, and then cooled, whereby the water purification filter of the present invention as shown in FIG. 1 can be formed.

Hereinafter, the present invention will be described specifically with reference to examples. An evaluation method for confirming the effects of the present invention will be described below.

The chlorine removal performance is such that room temperature model water having a chlorine concentration of 2 ppm is passed from the outer peripheral surface to the inner peripheral surface of the filter, and the chlorine concentration after passing the filter is defined as 0.4 which is the odor limit value.
It measured until it became ppm. The amount of water passed at this time was evaluated as chlorine removal performance.

To remove the activated carbon fibers, five unused filters were immersed in 2 liters of ion-exchanged water, fixed with a wire mesh, and rotated at a flow rate of 0.5 m / s with a propeller to rotate 30 water.
Stir for a minute and wash with water. The activated carbon fibers in the washing water were separated by filtration and weighed, and evaluated by the weight of activated carbon fibers per filter.

The initial water permeability is determined by placing an unused filter in the opening of the cylinder as shown in FIG. 3 and pouring 1 liter of tap water into the other opening to a depth of 9 cm so that the inner surface is inward from the outer peripheral surface. When the water passed toward the peripheral surface, the evaluation was based on the time required for the water to pass and emerge from the inner peripheral surface.

The water permeation after initial water permeation was evaluated by the amount of water per hour when 1 liter of water was passed using a filter after 100 liters of water permeation.

The flexibility of both ends of the filter is such that when the cylindrical body is deformed by 30% or more of the outer diameter in the diameter direction due to external force,
It was visually evaluated whether or not cracks such as delamination occurred at the ends.

[0034]

Example 1 Activated carbon fiber made from polyacrylonitrile (Fineguard FP3 manufactured by Toho Rayon Co., Ltd.)
41, a mixed paper made of heat-meltable fibers having a core-sheath structure using polyester as a core material and a polyethylene sheath material (basis weight: 60 g / m ² , density: 900 m ² / g, silver impregnated)
0.13 g / cm ³ ) and wrapped multiple
m, a cylindrical body having an outer diameter of 75 mm and a height of 25 mm, and a nonwoven fabric was wound around the inner and outer peripheral surfaces thereof and heated and set. Tables 1 and 2 show the fibers used in the nonwoven fabric, the fiber diameter, the equilibrium moisture content, and the blending ratio of each fiber. At this time, the basis weight of the non-woven fabric was 30 g / m ² , the thickness was 0.13 mm, and the density was 0.
23 g / cm ³ . Thereafter, a water purification filter was obtained using a vinyl acetate / ethylene copolymer as a fixing resin. Table 1 shows the performances of this filter.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

Example 2 and Example 3 A water purifying filter was manufactured in the same manner as in Example 1 except that the mixed paper and the nonwoven fabric were configured as shown in Table 1. Table 1 shows each performance of this filter.

[0038]

Comparative Example 1 As shown in Table 1, a filter comprising fibers in which the fibers constituting the nonwoven fabric were distributed in a fiber diameter of 10 to 20 μm was prepared. The performances of this filter are shown in Table 1. The fibers having an equilibrium moisture content of 5% or more are not included, so that the initial water permeability is poor. More.

[0039]

Comparative Example 2 As shown in Table 1, a filter was prepared in which the weight of activated carbon fibers was 90% by weight based on the mixed paper. The performances of this filter are shown in Table 1. As the weight of the activated carbon fibers relative to the mixed paper was large, the amount of the activated carbon fibers that had dropped out was also large, and the shapeability of the mixed paper was deteriorated, resulting in cracks at the edges. .

[0040]

COMPARATIVE EXAMPLE 3 As shown in Table 1, a filter using paraffin was prepared for fixing the ends. The performance of this filter is shown in Table 1. As a result of using paraffin at the end, the end was liable to crack.

[0041]

The filter for water purification of the present invention is a cylindrical filter, wherein the outer layer and the inner layer contain fibers having a fiber diameter of 10 to 50 μm and fibers having a fiber diameter of 0.5 to 3 μm. And the equilibrium moisture content at 65% RH and 20 ° C. is 5
% Of the fibers, which prevents the activated carbon fibers from falling off in the water passage direction, and has high water permeability from the beginning of water passage even when used at a low water pressure.

Further, since both ends of the filter are fixed by the thermoplastic resin, the activated carbon fibers are prevented from falling off from both ends, and the filter retains a good shape and is excellent in handleability. . Such a filter has a simple manufacturing process, has flexibility at the upper and lower ends of the filter, and is a water purifying filter suitable for use in a water purifier and excellent in handleability.

[Brief description of the drawings]

FIG. 1 is a sectional perspective view of a water purification filter of the present invention.

FIG. 2 is a perspective view before fixing an end of the water purification filter of the present invention with a thermoplastic resin.

FIG. 3 is a front view of an apparatus for evaluating initial water permeability of a water purification filter.

[Explanation of symbols]

 1. Mixed paper 2. Non-woven fabric 3. 3. Resin fixing portion at end (hatched portion) Filter for water purification -5. Cylinder 6. water

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B01D 39/16 C02F 1/28

Claims (6)

(57) [Claims] An inner layer and an outer layer of a cylindrical body are each made of a nonwoven fabric, and a layer between the inner layer and an outer layer is made of a mixed paper made of activated carbon fibers and heat-meltable fibers. In the water purification filter wherein both ends of the nonwoven fabric are fixed with a thermoplastic resin, the fibers constituting the nonwoven fabric are a fiber having a fiber diameter of 10 to 50 μm and a fiber having a fiber diameter of 0.5 to 3
A filter for water purification, comprising a fiber having a fiber of μm and an equilibrium moisture content at 65% RH and 20 ° C. of 5% or more. 2. The 65% RH, 20% relative to the nonwoven fabric
The weight of a fiber having an equilibrium moisture content at 5 ° C of 5% or more is 5-1.
The filter for water purification according to claim 1, wherein the content is 5% by weight. 3. The 65% R of the water-permeable nonwoven fabric
H, The fiber whose equilibrium water content at 20 ° C. is 5% or more is rayon. 4. The filter for water purification according to claim 1, wherein the heat-fusible fibers constituting the mixed paper are fibers having a core-sheath structure using polyester as a core material and polyethylene as a sheath material. 5. The weight of the activated carbon fiber relative to the mixed paper is 50 to 80% by weight, and the thickness of the mixed paper is 0.1%.
The filter for water purification according to claim 1, wherein the size of the filter is 3 to 0.6 mm. 6. The filter according to claim 1, wherein the thermoplastic resin is a copolymer of vinyl acetate and ethylene, a polyolefin, or a mixture of the copolymer and polyolefin.