JP3293180B2 - Liquid 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 liquid filter for removing contaminants in a liquid, and more particularly to a liquid filter exhibiting excellent performance for filtering a cleaning liquid for dry cleaning.

[0002]

2. Description of the Related Art Conventionally, Freon-based cleaning liquids have been used as dry cleaning cleaning liquids. However, due to recent global environmental conservation problems, mixed cleaning liquids of petroleum liquids and water have been used in place of Freon-based cleaning liquids. It has become to. On the other hand, a paper filter is used for filtering a cleaning liquid in a dry cleaning device. However, the paper filter has a low water resistance due to a decrease in tensile strength by absorbing water, and there has been a problem that the use of the above-mentioned water-mixed cleaning liquid greatly reduces the filter life.

[0003] That is, the cleaning liquid of the dry cleaning apparatus is filtered and re-used while being forcibly circulated, and is reused. However, as the filter accumulates impurities and increases the flow resistance, the liquid supply pressure gradually increases. If the pressure reaches the limit strength of the filter, it will break. However, since the paper filter has low water resistance as described above, the paper filter may be broken at a liquid sending pressure of about 1.2 kg / cm ² · G. Therefore, the appearance of a liquid filter having a longer life has been desired.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a long-life liquid filter which has a high impurity trapping effect while having a small flow resistance and has a large water resistance.

[0005]

Means for Solving the Problems A liquid filter of the present invention to achieve the above object, the long fibers having an average fineness 1~5d
Comprising thermoplastic synthetic fibers are randomly stacked, the entangled points of the fibers is an adhesive nonwoven with resin adhesive, the ratio of the basis weight / thickness of the nonwoven fabric (density) from 0.13 to 0.3
0 g / cm ³ and an air permeability of 0.9 to 1.8 sec.

[0006] In the case of a conventional paper filter, a surface filtering action of trapping impurities in the liquid on the filter surface has been performed. However, when the nonwoven fabric is configured as described above to form a liquid filter, foreign substances are trapped inside the filter, and a high foreign substance trapping effect is obtained while reducing the flow resistance of the liquid filter by this internal filtration action. It will be able to be done. Moreover, since it is based on a nonwoven fabric of thermoplastic synthetic fibers, it has high water resistance and can have a long life. Specifically, for example, when used for dry cleaning, the initial pressure is set to about 0.
It can be 6 kg / cm ² · G and the maximum pressure before breaking can be about 2.5 kg / cm ² · G.

In the present invention, a long fiber constituting a nonwoven fabric
The thermoplastic synthetic fiber consisting of is not particularly limited, and any of polyester, nylon, polypropylene, polyethylene and the like can be used. Among them, polyester is most preferable. For nonwoven production, spunbond method to directly cloth from melt spinning Engineering degree is Ru are preferably used. The nonwoven fabric in which the fibers are randomly laminated is impregnated with a resin adhesive so that the entangled points of the fibers are bonded, but preferably the fibers are mechanically entangled by needling before impregnation with the resin adhesive. It is desirable to have a three-dimensional structure.

In the present invention, the thermoplastic synthetic fibers constituting the nonwoven fabric have an average fineness of 1 to 5 d. When the average fineness is smaller than 1d, the flow resistance when a liquid filter is used increases, and the initial pressure increases. On the other hand, if it is larger than 5d, the effect of filtering impurities is reduced. In the present invention, the “average fineness” is defined as 10
A sample of cm × 10 cm is cut out, and the value is calculated as an average value of the sum of fineness measured for 50 fibers randomly extracted from the sample.

Needling applied to the nonwoven fabric causes the fibers to be three-dimensionally entangled, and has an advantageous internal filtering action of contaminants. This internal filtration action is extremely effective for further reducing the flow resistance and further improving the filtration performance. The needle density of such needling is 30 to 130 needles / cm ²
It is desirable to be within the range. Examples of the resin adhesive for bonding the fibers include a thermosetting resin adhesive such as a melamine resin, a urea resin, and an epoxy resin, a vinyl or acrylic resin adhesive having a crosslinking ability, or a thermosetting resin. A mixed system of an adhesive and a vinyl-based or acrylic-based resin adhesive having a crosslinking ability is preferably used. The fibers are firmly fixed to each other by the impregnation of the resin adhesive, and the shape retention (pleating property) when processed into a filter can be improved.

The content of the resin adhesive in the nonwoven fabric is preferably 15 to 40% by weight. Further, it is not always necessary to make the distribution of the resin adhesive uniform with respect to the nonwoven fabric, and the resin adhesive may be distributed non-uniformly. Rather, it is preferable that the non-woven fabric is unevenly distributed on one side of the nonwoven fabric to make the non-uniform distribution rather than the uniform distribution. In the case of a filter in which the resin adhesive is unevenly distributed on one side as described above, it is desirable that the liquid to be treated flows from a rough region to a dense region.

In the present invention, the nonwoven fabric impregnated with the resin adhesive as described above and preferably needled has a weight per unit area / thickness ratio (density) of 0.13 to 0.3.
It is adjusted so as to be 0 g / cm ³ and the air permeability is 0.9 to 1.8 sec. The basis weight for this purpose is 100 to 200 g / m ² , and the thickness is preferably 0.4 to 1.2 mm. More preferably, the air flow rate is set to 30 to 70 cc / cm ² / sec.

The characteristics such as the basis weight / thickness ratio, air permeability, and air permeability influence the flow resistance of the filter and the effect of trapping foreign substances, and include the amount of fibers, denier of fibers, density of needles for needles, and resin adhesive. It can be determined by appropriately adjusting the combination of the content and the like. In particular, the basis weight / thickness ratio and the air permeability of the nonwoven fabric are important, and by setting the above range, the internal filtration action of trapping foreign substances inside the filter is enabled, and the flow resistance is reduced by the internal filtration action. Thus, a high impurity filtering effect can be exhibited.

In the present invention, the air permeability of the nonwoven fabric is measured by the air permeability test method for paper and paperboard specified in JIS P8117, and the air permeability is defined by JIS L1.
It was measured by the Frangiple method specified in No. 096. The thickness of the nonwoven fabric is measured by a dial gage of 20 g / cm ² . Hereinafter, a specific description will be given with reference to the embodiment shown in the drawings.

FIG. 1 shows a liquid filter according to an embodiment of the present invention. The liquid filter F is constructed based on a nonwoven fabric 1. The nonwoven fabric 1 has three-dimensional thermoplastic synthetic fibers 2 such as polyester entangled three-dimensionally by needling, and is impregnated with a resin adhesive such as a melamine resin. The nonwoven fabric 1 is configured such that at least the ratio of the basis weight / thickness (density) is 0.13 to 0.30 g / cm ³ and the air permeability is 0.9 to 1.8 sec.

The non-woven fabric for forming the liquid filter F having the above-mentioned internal filtration action is formed by randomly laminating thermoplastic synthetic fibers, preferably performing needling, further impregnating with a resin adhesive, and then calendering the resultant with a calender roller. It can be obtained by processing. Instead of such processing,
If the crushing treatment is performed with an embossing roller and the thickness is made too thin, the filtration performance becomes surface filtration, which is not preferable.

The non-woven fabric used in the present invention can be directly manufactured by a manufacturing apparatus as shown in FIG. 3, for example. In FIG. 3, reference numeral 31 denotes a thermoplastic polymer melt spinning machine, and 32 denotes a duct provided below the base of the melt spinning machine 31, and compressed air is blown from a supply pipe 33. The molten filament f spun from the melt spinning machine 31 is injected from the outlet of the duct 32 together with the compressed air onto the lower net conveyor 34, and is deposited to form the nonwoven fabric S. The nonwoven fabric S thus formed is sent to the needling device 36 by the feed roller 35 and needled, and then sent to the next resin impregnation step.

In the resin impregnation step, a resin bath 37 and a drying device 3
8. The curing device 39 and the calender roller 40 are arranged in series. After the needling is completed, the nonwoven fabric S is impregnated with the resin adhesive in the resin bath 37, adjusted to a predetermined impregnation amount by the mangle roller 37a, and then cured through the drying device 38 and the curing device 39. . After the thickness of the nonwoven fabric S cured with the resin adhesive is adjusted by the calender roller 40, the nonwoven fabric S is finally wound up by the winding device 41.

The liquid filter F according to the present invention is preferably used, for example, in a filtration section of a dry cleaning device as shown in FIG. The liquid filter F is formed in a tubular shape, the tubular wall surface is formed of a nonwoven fabric 1 that is folded in a mountain valley shape and pleated, and is stored in the filtering unit 23. The dry cleaning device connects a liquid sending pump 22 and a filtration unit 23 to the washing tank 21 via a circulation pipe 24, and allows the washing liquid extracted from the washing tank 21 by the liquid sending pump 22 to pass through the filtering unit 23 to remove impurities. After the removal, it is returned to the washing tank 21 again. Of course, the liquid filter according to the present invention can be effectively used not only for the cleaning liquid for dry cleaning but also for filtering water, oil, and other liquids for cutting in a machine tool that performs electric discharge cutting, wire cutting, and the like.

[0019]

EXAMPLE A 13081 m ² web composed of polyester filaments having an average fineness of 2 d was collected by a spun bond method, and the web was collected by a needle punching machine at a rate of 4081 m ^2.
Needling treatment was performed at a density of 60 needles / cm ² and a depth of 8 mm using a needle of No. 9 barb (manufactured by Organ Needle Co., Ltd.). Next, the obtained nonwoven fabric was impregnated with an acrylic resin (“AN3814” manufactured by Dainippon Ink and Chemicals, Inc.), dried at 160 ° C., and cured at 180 ° C.
The properties of the obtained sheet were as follows.

Weight per unit area: 160 g / m ² Thickness: 0.70 mm Air permeability: 1.4 sec Air permeability: 63 cc / cm ² / sec Tensile strength: Vertical 51 kg / 5 cm, horizontal 47 kg / 5 cm Tensile elongation : Vertical 50%, horizontal 45% Tear strength: vertical 6.2kg, horizontal 6.7kg (tensile strength and elongation according to JIS L1096, tensile strength according to single tongue method) Dry cleaning device for nonwoven fabric obtained as above When used as a filter, the initial pressure was 0.6
kg / cm ² · G, and the maximum pressure before breaking could be set to 2.5 kg / cm ² · G, so that a very long life operation was possible.

[0021]

According to the liquid filter of the present invention described above, impurities in liquid are not filtered on the filter surface.
The filter has an internal filtering action inside the filter, and this internal filtering action enables the liquid filter to have a high impurity filtering effect while reducing the flow resistance. Moreover, since it is based on thermoplastic synthetic fibers, it has high water resistance and can have a long life.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a liquid filter according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a cleaning device using the liquid filter.

FIG. 3 is a schematic view illustrating an example of a manufacturing process of the liquid filter of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nonwoven fabric 2 Nonwoven fabric 3 Thermoplastic synthetic fiber F Liquid filter

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-86529 (JP, A) JP-A-5-329312 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 39/00-39/20

Claims (4)

(57) [Claims] 1. A thermoplastic synthetic fiber composed of long fibers having an average fineness of 1 to 5d is randomly laminated, and the entanglement point of the fibers is composed of a nonwoven fabric bonded with a resin adhesive. The ratio (density) is 0.13 to 0.30 g / cm
^3. A liquid filter having an air permeability of 0.9 to 1.8 sec. 2. The non-woven fabric according to claim 1, wherein said non-woven fabric has a ventilation rate of 30 to 70 cc / cm
The liquid filter according to claim 1, wherein the flow rate is ² / sec . 3. The thermoplastic synthetic fiber comprising the long fiber,
Claim 1 which is intertwined three-dimensionally by needling.
Or the liquid filter according to 2 . 4. A method for filtering a cleaning liquid for dry cleaning.
The liquid filter according to claim 1, 2 or 3 .