WO2014025689A1

WO2014025689A1 - Filter for a water purifier, and a water purifier including the same

Info

Publication number: WO2014025689A1
Application number: PCT/US2013/053622
Authority: WO
Inventors: Yinshi JIN
Original assignee: 3M Innovative Properties Company
Priority date: 2012-08-06
Filing date: 2013-08-05
Publication date: 2014-02-13
Also published as: TW201420171A; KR20140019636A

Abstract

This invention provides a filter for a water purifier, comprising: at least one carbon-loaded web (CLW) layer; and a carbon blocking mesh sealing the CLW layer partially or entirely so that water can be permeated but carbon can be blocked.

Description

FILTER FOR A WATER PURIFIER, AND A WATER PURIFIER INCLUDING THE SAME

Background

This invention relates to a filter for a water purifier. Specifically, this invention relates to a filter for a water purifier comprising a carbon loaded web (CLW), and a water purifier including the same.

A water purifier is used for purifying water by removing heavy metals or other undesirable materials contained in the water to provide suitable drinking water based on purification including precipitation, filtration, and sterilization, etc. Various filters may be used in a water purifier, which can be classified into the following types of filters according to function: a sediment filter; an activated carbon filter; a UF hollow fiber filter; and an RO membrane filter. The filters are utilized in the precipitation, pre-carbon, membrane and post-carbon stages

A carbon loaded web (CLW) layer has been used in a filter of a water purifier to flush water at very low pressure or through the power of gravity to filter impurities.

Figs. 1 and 2 are cross-sectional views of a filter of a water purifier comprising carbon loaded webs, which is disclosed in Korean Patent Application No. 201 1-4981 1. The conventional filter represented in Fig. 1 has a structure that the first scrim (40), the first CLW layer (10), the second CLW layer (10), and the second scrim (40) are laminated from the top of the filter. Another conventional filter represented in Fig. 2 has a structure that a nanofiber (30) is further laminated under the second scrim (40) of the filter represented in Fig. 1.

While generally acceptable, these filters may experience problems of carbon particle leakage from the CLW layer (10). During die-cutting and assembling processes, many carbon particles are detached from the CLW layer and a filter housing is easily stained by the particles. As a result, the filtering speed of the filter will be reduced as it is used. In particular, in a filter comprising a hydrophilic nanofiber layer, carbon particles block the pores of the filter so that water can no longer be filtered.

Summary

Problems to be Solved

The present invention provides a filter for a water purifier, which has good filtering performance without causing carbon particle leakage, by overcoming the problems of the conventional technology; and a water purifier comprising the filter.

Means to Solve the Problem

In order to achieve the above, this invention provides a filter for a water purifier, comprising: at least one carbon loaded web (CLW) layer; and

a carbon blocking mesh sealing the CLW layer partially or entirely so that water can be permeated but carbon can be blocked.

In the filter described above, the carbon blocking mesh has a pore size ranging preferably from 30 to 75j¾m, and more preferably from 40 to 70j¾m. When the carbon blocking mesh seals the CLW layer partially, it preferably seals the side and the bottom of the CLW layer. The sealing is conducted by, for example, supersonic welding, heat welding, or sewing.

The carbon blocking mesh may be selected from the group of, for example, nylon, polyester, natural fiber, and scrim, and more preferably, nylon or polyester.

In one embodiment, the number of CLW layers is two. The CLW layer preferably further comprises a nanofiber layer thereon.

In terms of filtering performance, the nanofiber layer may be such that at least one nanofiber is selected from the group consisting of polyacrylonitrile (PAN), thermoplastic polyurethane, nylon, hydrophilic polyvinylidene fluoride (PVDF), and hydrophilic polytetrafluoroethylene (PTFE) is laminated on a nonwoven substrate, and the nanofiber layer is more preferably constituted such that polyacrylonitrile is laminated on a polyethylene terephthalate nonwoven substrate, and that the polyethylene terephthalate nonwoven substrate is laminated on the nanofiber layer. In one embodiment, the nanofiber layer has a pore size ranging from 0.5 to 2.5 j¾m.

This invention also provides a water purifier comprising the filter as described above.

Effect of Invention

According to this invention, a filter for a water purifier that has good filtering performance without causing carbon particle leakage, and a water purifier comprising the filter are provided.

Brief Description of the Drawings

Fig. 1 is a cross-sectional view of a conventional filter for a water purifier comprising a CLW layer.

Fig. 2 is a cross-sectional view of another conventional filter for a water purifier comprising a CLW layer.

Fig. 3 is a cross-sectional view of the filter for a water purifier, wherein the carbon blocking mesh seals the CLW layer entirely, according to one embodiment of this invention.

Fig. 4 is a cross-sectional view of the filter for a water purifier, wherein the carbon blocking mesh seals the CLW layer entirely, according to another embodiment of this invention.

Fig. 5 is a cross-sectional view of the filter for a water purifier, wherein the carbon blocking mesh seals the CLW layer partially, according to one embodiment of this invention.

Fig. 6 is a cross-sectional view of the filter for a water purifier, wherein the carbon blocking mesh seals the CLW layer partially, according to another embodiment of this invention.

Detailed Description

Referring to the drawings, this invention is explained in further detail below.

Fig. 3 is a cross-sectional view of the filter for a water purifier, according to one embodiment of this invention. As represented in Fig. 3, this invention provides a filter for a water purifier (100), comprising: at least one carbon loaded web (CLW) layer (10); and

a carbon blocking mesh (20) sealing the CLW layer (10) partially or entirely so that water can be permeated but carbon can be blocked.

In the filter (100) above, the carbon blocking mesh (20) has a pore size ranging preferably from 30 to 75j¾m, and more preferably from 40 to 70j¾m. The carbon blocking mesh (20) having a pore size of 30j¾m or higher is preferable in terms of filtering speed. The carbon blocking mesh (20) having a pore size ranging of 75j¾m or lower is preferable in terms of activated carbon blocking performance.

The carbon blocking mesh (20) may entirely cover the top, the bottom, and the side of the CLW layer (10) to seal the CLW layer (10) completely, as depicted in Figs. 3 and 4, and may seal the side and the bottom of the CLW layer (10), as depicted in Figs. 5 and 6. By sealing the CLW layer (10) as described above, water may be easily permeated, but the carbon particles detached from the CLW layer (10) are contained within the carbon blocking mesh (20).

The sealing of the carbon blocking mesh (20) can be conducted by general methods, such as supersonic welding, heat welding, or sewing. Adhesive bonding, heat bonding or supersonic bonding may also be used.

For the carbon blocking mesh (20), any material in which water can be permeated but the carbon particles from the CLW (10) can be blocked may be used. The material may be selected, for example, from the group consisting of nylon, polyester, natural fiber, and scrim. In particular, nylon or polyester is preferable.

The CLW layer (10) has the role of filtering impurities when the water supplied is permeated at very low pressure or by the power of gravity. There is no limitation to the types of materials that can be used for the CLW layer (10). Materials where the carbon particles are filled therein, such as polyethylene (PE), polypropylene (PP), or nylon, may be used. There is no particular limitation to the thickness of the CLW layer. The thickness of the CLW layer may be generally 3.0 to 5.0mm. The importance of the CLW (10) lies in having a low resistance to the flux of a fluid, which is particularly important when the flux of a fluid is great. The CLW has loose porosity. Preferably, activated carbon may be used as carbon for the CLW layer. There is no limitation with respect to the amount of carbon filled. The amount of carbon filled may be 40% by weight or the more, even more than 90% by weight, based on the total number of CLW layers. The CLW (10) may comprise at least one layer. The number of CLW layers (10) may be decided based on the desired filtering speed, purifying performance, etc. In one desirable embodiment, the number of CLW layers (10) is two.

The filter (100) for a water purifier may comprise a nanofiber layer on the CLW layer (10). Figs. 4 and 6 represent a cross-sectional view of a filter for a water purifier further comprising a nanofiber layer according to another embodiment of this invention. As illustrated in Figs. 4 and 6, the filter of this invention (100) comprises at least one CLW layer (10); a nanofiber layer (30) under the CLW layer (10); and a carbon blocking mesh (20) sealing both the CLW layer (10) and the nanofiber layer (30) partially or entirely so that water can be permeated but carbon can be blocked. The CLW mesh (20) may completely cover the top surface, the side, and the bottom of the CLW layer (10) and the nano fiber (30) to seal the CLW layer (10) entirely (Fig. 4), and may also cover only the side and the bottom of both the CLW layer (10) and the nanofiber layer (30) (Fig. 6). By doing so, water may be permeated but the carbon particles from the CLW layer (10) may be blocked.

The nanofiber layer (30) may comprise a nonwoven substrate. In one embodiment, the nanofiber layer (30) may be used wherein at least one nanofiber selected from the group consisting of polyacrylonitrile (PAN), thermoplastic polyurethane, nylon, hydrophilic polyvinylidene fluoride (PVDF), and hydrophilic polytetrafluoroethylene (PTFE) is comprised on a nonwoven fabric substrate such as polyethylene terephthalate (PET), polypropylene (PP), nylon, and rayon. In view of durability, pore size, and filtering speed, the weight of nanofiber (except for nonwoven) is preferably 0.5 to 3 grams/square meter (gsm), more preferably 0.8 to 2 gsm. More preferably, the nanofiber layer (30) is such that polyacrylonitrile is laminated on a polyethylene terephthalate nonwoven substrate, and the polyethylene terephthalate nonwoven substrate is laminated thereon.

There is no particular limitation to the method for providing a nanofiber layer on a nonwoven substrate. For example, a nanofiber obtained by a method, such as electrospinning, may be bonded to a nonwoven substrate by conventional heat bonding or by use of an adhesive. Further, the nanofiber may be directly spun on the nonwoven substrate.

In one embodiment, the nanofiber layer (30) has a pore size of 0.5 to 2.5j¾m.

There is no limitation to the thickness of the nanofiber layer (30). For example, in certain embodiments, the nanofiber layer (30) preferably has a thickness of 100 to 300j¾m, and more preferably,

The filter (100) of this invention may be used in a water purifier, together with a distribution plate located above the filter and a filter housing located under the filter.

Examples

Examples of this invention will be explained below. However, the examples show just one embodiment of this invention, and should not be interpreted to limit or reduce the scope of the claims of this invention.

Example 1

Example 1 was a filter wherein the carbon blocking mesh (20) covers two CLW layers (10) entirely, as illustrated in Fig. 3. For the carbon blocking mesh (20), a nylon mesh from Yueqing Sailaoau Gauze Filter Co. Ltd. was used. The nylon mesh seals the CLW layers (10) by supersonic welding. The feature of the nylon mesh used is shown in Table 1. Table 1

Example 2

Example 2 was a filter wherein a nano fiber layer (30) is provided under the lower CLW layer (10) of the two CLW layers (10), and wherein the carbon blocking mesh (20) covers both the CLW layers (10) and the nanofiber layer (30) entirely, as represented in Fig. 4. The carbon blocking mesh (20) used is the same as that of example 1. The nanofiber layer (30) used is such that polyacrylonitrile is laminated on a polyethylene terephthalate nonwoven substrate, and the polyethylene terephthalate nonwoven substrate is laminated thereon. The feature of the nanofiber used is shown in Table 2.

Table 2

Comparative Example 1

Comparative Example 1 was a conventional filter wherein scrim (40), a CLW layer (10), a CLW layer (10), and scrim (40) are laminated from the top of the filter, which is represented in Fig. 1.

Comparative Example 2

Comparative Example 2 was a conventional filter wherein the nanofiber layer (30) is laminated under the lower scrim (40) of Comparative Example 1 , which is illustrated in Fig. 2. The nanofiber (30) used is such that a blend of polyacrylonitrile (PAN) and thermoplastic polyurethane in a weight ratio of 7:3 is laminated on a polyethylene terephthalate (PET) nonwoven substrate. The features of the nanofiber used are as shown in Table 3.

Table 3

Evaluation

Experimental Example 1 - Observation as whether carbon remains in a filter housing

A water sample was supplied to a conventional filter represented in Figs. 1 and 2 (corresponding to Comparative Examples 1 and 2, respectively), and the filter of this invention is represented in Figs. 3 and 4 (corresponding to Examples 1 and 2, respectively). Thereafter, it was observed whether carbon particles remained in a filter housing or not.

(1) Comparison of Comparative Example 1 and Example 1

The results of a comparison of Comparative Example 1 and Example 1 are shown in Table 4.

As shown in Table 4, in the filter of Comparative Example 1, many black carbon particles are observed around the border of the filter housing and the distribution plate, whereas in the filter of Example 1 , black carbon particles are not observed.

(2) Comparison of Comparative Example 2 and Example 2

The results of a comparison of Comparative Example 2 and Example 2 are shown in Table 5. Table 5

As shown in Table 5, in the filter of Comparative Example 2, many black carbon particles are observed around the border of the filter housing and the distribution plate, whereas in the filter of Example 2, black carbon particles are not observed.

Experimental Example 2 - Observation as to whether carbon remains among the aqueous solution samples filtered

A water sample is filtered by the filter of Comparative Example 1 , and by the filter of Example 1. Thereafter, it is observed whether the water sample comprises carbon particles or not. The results are shown in Table 6.

Table 6

As shown in Table 6, many black carbon particles are observed in the aqueous solution filtered by the filter of Comparative Example 1 , whereas black carbon particles are not observed in the aqueous solution filtered by the filter of Example 1.

Experimental Example 3 - Filtering Speed Test

In order to obtain a filtering speed of the filter, a permeation rate of water was measured after supplying 2 liters of water to the filter of Comparative Example 2 and the filter of Example 2. The results are shown in Table 7.

Table 7

As shown in Table 7, it was observed that the filtering speed of the filter of Example 2 was two times faster than that of Comparative Example 2.

Experimental Example 4 - Filtering Speed Test

Water was supplied to the same filter as that disclosed in Example 1 except that a carbon blocking mesh with various pore sizes was used. Thereafter, the CLW was separated from the filter media and was shaken 10 times. After taking a picture of the remaining carbon, its weight was measured. The results are shown in Table 8.

Table 8

As shown in Table 8, virtually no remaining carbon was found when the carbon blocking mesh has a pore size of 75j¾m. Also, no remaining carbon was found when the carbon blocking mesh has a pore size of 70j¾m.

Claims

What is claimed is

1. A filter for a water purifier, comprising:

at least one carbon loaded web (CLW) layer; and

2. The filter of claim 1, wherein the carbon blocking mesh has a pore size ranging from 30 to 75j¾m.

3. The filter of claim 2, wherein the carbon blocking mesh has a pore size ranging from 40 to 70j¾m.

4. The filter of claim 1, wherein the carbon blocking mesh seals the CLW layer entirely.

5. The filter of claim 1, wherein the carbon blocking mesh seals the side and the bottom of the CLW layer.

6. The filter of claim 1, wherein sealing is conducted by supersonic welding, heat welding, or sewing.

7. The filter of claim 1, wherein the carbon blocking mesh is selected from the group consisting of nylon, polyester, natural fiber, and scrim.

8. The filter of claim 1, wherein the carbon blocking mesh is nylon or polyester.

9. The filter of claim 1, wherein the number of the CLW layer is two.

10. The filter of claim 1, further comprising a nanofiber layer on the CLW layer.

1 1. The filter of claim 10, wherein the nanofiber layer is such that at least one nanofiber selected from the group consisting of polyacrylonitrile (PAN), thermoplastic polyurethane, nylon, hydrophilic polyvinylidene fluoride (PVDF), and hydrophilic polytetrafluoroethylene (PTFE) is laminated on a nonwoven fabric substrate.

12. The filter of claim 11, wherein the nanofiber layer is such that polyacrylonitrile is laminated on a polyethylene terephthalate nonwoven substrate, and that polyethylene terephthalate nonwoven substrate is laminated on the nanofiber layer.

13. The filter of claim 10, wherein the nanofiber layer has a pore size ranging from 0.5 to 2.5j¾m.

14. A water purifier comprising the filter of claim 1.