JP2010137121A - Filter having high differential pressure-proof performance and gel foreign matter elimination performance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter canceling problems of variation in filtering accuracy due to differential pressure and shortening of a service life of the filter, and collecting soft gel solid matter even when pulse pressure and high differential pressure occur, in the filtration of a viscous fluid causing pulse pressure and high differential pressure. <P>SOLUTION: The filter is formed by laminating a first main filtering non-woven fabric formed of extremely thin fibers subjected to thermocompression bonding and having a porosity of 50-80% and a second main filtering non-woven fabric not subjected to thermocompression bonding and having the porosity of 80% or more. The filter is held between auxiliary filtering non-woven fabric sheets having a larger average flow rate hole diameter than the main filtering non-woven fabric. The second main filtering non-woven fabric is formed to have a porosity of 1.2 times or more of that of the first main filtering non-woven fabric, to provide the high differential pressure-proof performance and gel foreign matter elimination performance. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a filter having a high differential pressure resistance capable of obtaining stable filtration accuracy even under pulse pressure and high differential pressure, and suitable for removing gelled foreign substances.

  For filtration of fine gel-like solids, ultrafine fibers are used for the main filtration nonwoven fabric. As this main filtration nonwoven fabric, generally, a nonwoven fabric composed of fibers of 10 μm or less produced by a hot melt spinning method or the like is often used as the main filtration nonwoven fabric.

  However, the nonwoven fabric produced by the hot melt spinning method has low fiber strength and the fibers are not strongly heat welded to each other. A consolidation phenomenon occurs. For this reason, in the filtration of viscous fluid in which a high differential pressure is generated, a phenomenon of opening and consolidation of the filtration nonwoven fabric occurs, resulting in a problem that the filtration accuracy changes due to the differential pressure and the filter life is shortened.

  Moreover, since the shape of a soft gel-like solid changes due to a pulse pressure or a high differential pressure generated during filtration, a phenomenon of slipping through the filtration nonwoven fabric easily occurs. Therefore, due to the opening of the filtration nonwoven fabric and the change in shape of the gel-like solid matter, there is a problem that the gel-like solid matter is difficult to be captured by the filter.

  The present invention has been made paying attention to such points, and in the filtration of viscous liquids in which pulse pressure and high differential pressure occur, the filtration accuracy changes due to the differential pressure, and the filter life is shortened. The object is to provide a filter that eliminates this problem.

  Another object of the present invention is to provide a filter capable of capturing a soft gel-like solid without any trouble even when a pulse pressure or a high differential pressure occurs.

The filter of the present invention that meets the above-mentioned object is a first main filtration nonwoven fabric made of ultrafine fibers that has been subjected to pressure-bonding treatment to a porosity of 50 to 80%, and a second main filtration that has a porosity of 80% or more that has not been pressure-bonded. A filter laminated with a nonwoven fabric is sandwiched between auxiliary filtration nonwoven fabric sheets having an average pore diameter larger than that of the main filtration nonwoven fabric, and the second main filtration nonwoven fabric has a porosity of 1. It is characterized by being twice or more.
The second main filtration nonwoven fabric is preferably formed by laminating single or two or more types of non-woven fabrics having different fiber diameters, particularly by laminating two or more types of non-woven fabrics having different fiber diameters. It is extremely effective in high differential pressure resistance and removal of gel-like foreign matters (Claim 2).

  The basis weight of the first main filtration nonwoven fabric is 10 to 40% of the total of the first main filtration nonwoven fabric and the second main filtration nonwoven fabric, which is suitable as a filter for filtering gel solids. (Claim 3).

The basis weight of the first main filtration nonwoven fabric is preferably 30 to 60% of the total of the first main filtration nonwoven fabric and the second main filtration nonwoven fabric as a filter having high differential pressure resistance. (Claim 4).
The fiber diameter of the main filtration nonwoven fabric is 20 μm to 0.1 μm, and the fiber diameter of the second main filtration nonwoven fabric is 4 to 0.5 times the fiber diameter of the first main filtration nonwoven fabric. Is suitable as a filter for filtering a gel-like solid (claim 5).

A basis weight of the main filtration nonwoven fabric of 400 to 1000 g / m ² is suitable as a filter for filtering gel-like solids (Claim 6).

  According to the present invention, while maintaining good filtration accuracy even by pressure fluctuations, this type of conventional technology can effectively capture gel-like foreign matter that could not be caught by conventional filters due to deformation of the filter and gel-like foreign matter. This filter has a tremendous effect that cannot be seen at all.

  Next, an embodiment of the present invention will be described.

  The material of the nonwoven fabric used for this invention is not specifically limited. An ultrafine fiber having a fiber diameter of preferably 20 μm to 0.1 μm, which is produced from a synthetic fiber such as polypropylene, nylon or polyester by a hot melt spinning method, is preferably used.

  The 1st main filtration nonwoven fabric used for this invention makes the porosity 50-80% by carrying out the thermocompression-bonding process of the ultrafine fiber by the calendar process etc. FIG. When the porosity is smaller than this, the filtration life is deteriorated, and when it is larger than this, the differential pressure resistance performance and the gel foreign matter capturing performance are degraded. When the porosity is 85%, it has been confirmed by experiments that gel foreign substances cannot be completely captured even if other conditions are satisfied.

The 2nd main filtration nonwoven fabric used for this invention is a nonwoven fabric with the porosity of 80% or more which has not been crimped | bonded. When the porosity is smaller than this, clogging easily occurs. The upper limit of the porosity of the second main filtration nonwoven fabric is not particularly limited, but a maximum of 97 to 98% of commercially available products can be used without any problem.
The porosity of the second main filtration nonwoven fabric of the present invention is 1.2 times or more that of the first main filtration nonwoven fabric. If the difference is smaller than this, the differential pressure resistance performance deteriorates. Although an upper limit is not specifically limited, Since the upper limit of the porosity of a 2nd main filtration nonwoven fabric is 97-98% at the maximum now, it is less than 2 times.
The second main filtration nonwoven fabric is formed by laminating single or two or more types of non-woven fabrics having different fiber diameters, and particularly by laminating two or more types of non-woven fabrics having different fiber diameters in multiple layers. It is preferable to use it because good differential pressure resistance and gel-like foreign matter capturing performance can be obtained.
As the auxiliary filtration nonwoven fabric sheet for sandwiching the main filtration nonwoven fabric, a known nonwoven fabric used for this kind of net having a larger average pore diameter than the main filtration nonwoven fabric may be used.

  As a filter for filtering gel-like solids, the basis weight of the first main filtration nonwoven fabric should be 10 to 40% of the total of the first main filtration nonwoven fabric and the second main filtration nonwoven fabric. . If it is smaller than this range, the trapping ability of the gel-like foreign matter is lowered, and if it is larger, the filtration life of the filter is lowered. The removal of 0.5 μm gel-like solids is 32%, and the removal of 0.8 μm gel-like solids is 12%.

As a filter having differential pressure resistance, the basis weight of the first main filtration nonwoven fabric is preferably 30 to 60% of the total of the first main filtration nonwoven fabric and the second main filtration nonwoven fabric. It is preferable because accurate filtration accuracy can be obtained. If it is smaller than this, the differential pressure resistance performance will be inferior, and if it is larger than this, it will be easily clogged.
The fiber diameter of the main filtration nonwoven fabric is 20 μm to 0.1 μm, and the fiber diameter of the second main filtration nonwoven fabric is 4 to 0.5 times the fiber diameter of the first main filtration nonwoven fabric. Is suitable as a filter for filtering gel-like solids. Experiments have confirmed that when it is 6 times or more, the trapping ability of the gel-like solid is lowered even if other conditions are satisfied.

A basis weight of the main filtration nonwoven fabric of 400 to 1000 g / m ² is suitable as a filter for filtering gel-like solids. If it is smaller than this, the gel-like solids are likely to leak, and if it is more than this, the filter pleated shape cannot be formed. The removal of 0.8 μm gel-like solids is 444 g / m ² , and the removal of 0.5 μm gel-like solids is 417 g / m ^2. Has been. In addition, it was confirmed by experiments that the gelled solid was discharged at 260 g / m ² in removing the 0.5 μm gelled solid.

  The filter of the present invention is suitably used as a cartridge filter such as a pree filter or a depth filter.

  As shown in Table 1 below, 0.5 μm and 0.8 μm gel-like solid removal filters were manufactured using polypropylene ultrafine fibers. The vertical direction in Table 1 is the liquid passing direction.

第一の主濾過不織布と第二の主濾過不織布の合計の目付量は、０．５μｍフィルターの場合は、４１７ｇ／ｍ^２であり、０．８μｍフィルターの場合は、４４４ｇ／ｍ^２である。

Basis weight of the sum of the first main filtration nonwoven fabric and the second main filtration nonwoven For 0.5μm filter, a 417 g / ^{m 2,} in the case of 0.8μm filter, a 444 g / ^{m 2.}

  With respect to the conventional depth spray filter shown in the following Table 2 and the high differential pressure resistant filter of the present invention, filtration accuracy and removal efficiency for each differential pressure were measured. The results are shown in FIGS.

従来の２０μｍカット径フィルターは、第一の主濾過不織布の目付量が全体の目付量に占める割合は、２５％であるが、上記高耐差圧フィルターは、５０％である。

In the conventional 20 μm cut diameter filter, the ratio of the basis weight of the first main filtration nonwoven fabric to the total basis weight is 25%, but the high differential pressure filter is 50%.

  In the conventional 20 μm cut diameter filter, the ratio of the fiber diameters of the first and second main filtration nonwoven fabrics is 1.1 to 3.6 times, but the high differential pressure resistance filter is 0.92 times. .

  As is apparent from the results of FIG. 1, the conventional depth spread filter has a large variation in filtration accuracy for each differential pressure, but the high pressure filter of the present invention has a small variation in the filtration accuracy for each differential pressure.

  Further, as is apparent from the results of FIG. 2, the conventional depth spread filter has a filtration efficiency upper limit value as the pressure rises as shown by the line of the pressure upper limit value (A) and the pressure lower limit value (B). As shown by the line between (C) and the lower limit of filtration efficiency (D), the removal efficiency of the pleated filter decreases, but the high pressure filter of the present invention has an upper pressure limit (A) and a lower pressure limit (B). Even if the pressure rises as shown by the line of, as shown by the line of the filtration efficiency upper limit value (C) and the filtration efficiency lower limit value (D), the removal efficiency of the pre-filter does not decrease but rises conversely. .

  If a pleated filter is used for filtration in the coating process of the coating liquid and coating is performed, a substrate defect of a point defect that is presumed to be caused by the outflow of gel-like foreign matters after coating occurs.

  There is a strong demand for a filter that can maintain gel removal performance even in intermittent operation with pulsation. Therefore, with respect to the 0.5 μm cut diameter filter described in the following Table 3 and the 0.5 μm cut diameter gel-like foreign substance removal filter of the present invention, the change in filterability accuracy with time and the change of the gel-like foreign substance removal rate are shown in FIG. It measured by the test method in the intermittent operation shown.

  As shown in FIG. 3, the test conditions are as follows: filtration method: intermittent filtration, 1 cycle: liquid passage 15 seconds, stop 5 seconds, flow rate: 0.5 liter / minute, sample size: small capsule filter, pump ON / OFF A filtration test in intermittent operation was performed by turning OFF.

  The particle size distribution of test gel particles in a solution in which only gel particles synthesized with a water-soluble polymer were dispersed in pure water (RO water) was determined. The result was as shown in FIG.

従来の０．５μｍカット径フィルターは、第一の主濾過不織布の目付量が全体の目付量に占める割合は、２７％であるが、上記０．５μｍカット径ゲル状異物除去フィルターフィルターは、３２％である。

In the conventional 0.5 μm cut diameter filter, the ratio of the basis weight of the first main filtration nonwoven fabric to the total basis weight is 27%. However, the 0.5 μm cut diameter gel-like foreign substance removal filter is 32%. %.

  In the conventional 0.5 μm cut diameter filter, the ratio of the fiber diameters of the first and second main filtration nonwoven fabrics is 7 to 13 times. Is double.

  Using the test gel particles shown in FIG. 4 and using the filters shown in Table 3, a filtration test in intermittent operation was performed under the conditions shown in FIG. The results are shown in FIGS.

  As is clear from the results of FIG. 5, the conventional filter reduces the removal rate of the gel-like foreign matter with the amount of treatment, but as is clear from the results of FIG. 6, the gel-like foreign matter removal filter of the present invention is treated. The removal rate of the gel-like foreign material with respect to the amount is stable.

  Further, as apparent from the result of FIG. 7 (A), the filter of the present invention does not cause any gel-like foreign matter to flow out even if clogging occurs, but the conventional filter has a gel-like foreign matter against clogging. The removal rate becomes worse. As is clear from the results of FIG. 7B, the conventional depth spray filter has a reduced filter removal efficiency when the pressure is increased, but the high pressure filter of the present invention has an increased pressure. However, the filter removal efficiency does not decrease.

It is the graph which measured the filtration precision for every differential pressure about the conventional depth filter and the high pressure | voltage resistant filter of this invention. It is a graph which shows the relationship between a pressure rise and filtration accuracy with elapsed time about the conventional depth spray filter and the high pressure | voltage resistant filter of this invention. It is a figure which shows the test method in intermittent operation. It is a figure which shows the particle size distribution of the gel-like particle | grains used for the test of this invention. It is a figure which shows the time-dependent change of the filtration precision in the intermittent operation about the conventional depth spray filter. It is a figure which shows the time-dependent change of the filtration precision in intermittent operation about the high pressure | voltage resistant filter of this invention. (A) It is a graph which shows the change of a processing amount and a particle removal rate, and (B) is a graph which shows the change of a differential pressure | voltage and a particle removal rate about the conventional depth spray filter and the high pressure | voltage resistant filter of this invention.

Claims (6)

A filter obtained by laminating a first main filtration nonwoven fabric having a porosity of 50 to 80% by pressure-bonding treatment and a second main filtration nonwoven fabric having a porosity of 80% or more that has not been pressure-treated, It is sandwiched between auxiliary filtration nonwoven fabric sheets having an average pore diameter larger than that of the filtration nonwoven fabric, and the second main filtration nonwoven fabric has a porosity of 1.2 times or more that of the first main filtration nonwoven fabric. A filter having a high differential pressure resistance performance and a gel-like foreign matter removal performance for passing liquid in the direction from the second main filtration nonwoven fabric to the first main filtration nonwoven fabric. The filter according to claim 1, wherein the second main filtration nonwoven fabric is formed by laminating single or two or more types of nonwoven fabrics having different fiber diameters. 3. The gel-like foreign matter removing performance according to claim 1, wherein a basis weight of the first main filtration nonwoven fabric is 10 to 40% of a total of the first main filtration nonwoven fabric and the second main filtration nonwoven fabric. filter. 3. The high differential pressure resistance performance according to claim 1, wherein a basis weight of the first main filtration nonwoven fabric is 30 to 60% of a total of the first main filtration nonwoven fabric and the second main filtration nonwoven fabric. filter. The fiber diameter of the main filtration nonwoven fabric is 20 μm to 0.1 μm, and the fiber diameter of the second main filtration nonwoven fabric is 4 to 0.5 times the fiber diameter of the first main filtration nonwoven fabric. The filter which has the gel-like foreign material removal performance in any one of claim | item 1-3. Basis weight of the primary filtration nonwoven filter having a gel-like foreign substance removal performance according to any one of claims 1 to 3 and 5 is 400~1000g / m ^2.

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