JPH07328356A - Cartridge filter and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture a cartridge filter having economical advantages for improving a problem that the filter life gets shorter when accuracy gets higher and retaining the given accuracy for longer filter life. CONSTITUTION:Latent solid crisped multi-filaments composed of a number of eccentric core sheath type composite single fibers are spinned by composite spinning two kinds of thermoplastic synthetic resins composed of a core component (A) and a sheath component (B) of different heat shrinkability, and the multi-filaments are stretched, heat treated and stabilized to manufacture a multi-filament bundle having single fiber fineness of 2-40 denier and total finness of 1000-10000 denier, which is formed into an untwisted flat tape shape and wound on a porous core cylinder and form a cylindrical filter layer. Thus a cartridge filter having the solid crisp number of the multi-filament bundle in the filter layer of 3-50 pieces/inch and the fiber density of 0.15-0.50g/cm<2> is manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical cartridge filter for filtering liquid such as water, oil, solvent and food, and a method for producing the same.

[0002]

2. Description of the Related Art Cylindrical cartridge type filters are roughly classified into a thread wound type and a non-woven cloth wound type. The non-woven cloth wound type has high accuracy but has a short filtration life and is expensive due to high manufacturing cost. Therefore, in the industry, a high-flow rate and low-price wound type is preferred.

The wound type includes a type using spun yarn (coarse yarn) and a type using multifilament for the filtration layer. The roving winding type is inexpensive and has the advantage that the filtration accuracy can be adjusted by changing the thickness and number of twists of the roving yarn, but it has the drawback that fluffs and fibers may fall off, and in recent years it has been a multifilament winding type. In particular, a crimped multifilament wound type has come into wide use.

As another cylindrical cartridge filter, for example, a fiber web spun by a melt blow method is wound directly on a porous core cylinder with a fineness gradient by a technique described in JP-A-60-216818. Cartridge filters formed by taking them have come into practical use.

[0005]

However, the crimped, multifilament wound type cartridge filter is superior to the wound type in that it has a uniform filtration filter fiber density and therefore has a high filtering performance and that the fibers do not fall out. However, the multifilament used in the conventional cartridge filter of this kind is costly because the desired crimp is applied by means of mechanical crimping or indentation crimping. Not only that, the crimped form is two-dimensional, and the oil agent remains on the multifilament to cause foaming at the beginning of use. In addition, improving the filtration life will decrease the accuracy, and increasing the accuracy will shorten the filtration life.
It is extremely difficult to improve these two conditions together, and there is a strong demand in the industry for a cartridge filter having a good balance between filtration life and precision.

Further, the cartridge filter obtained by the melt blow method has the advantage that it has a fineness gradient of the fibrous web from the outer layer to the inner layer and has a deep layer filtration function, but there is a difficulty in maintaining the initial accuracy. It has not yet been effective in improving the filtration life. Furthermore,
Since continuous production is difficult, production efficiency is poor and expensive.

The present invention solves the above-mentioned disadvantages of the conventional multi-filament winding type, and has a ratio of initial accuracy and filtration life that is significantly larger than that of a conventional cartridge filter, and therefore has the same initial accuracy. The present invention provides an economically advantageous cartridge filter having a long filtration life and a method for manufacturing the same.

[0008]

In the present invention, an unstretched multifilament having a latent crimp property is stretched and relaxed to develop a three-dimensional crimp having a three-dimensional helical structure, and further heat shrink treatment is performed. The above problem was solved by forming a filtration layer with multifilaments made of That is, the cartridge filter of the present invention has a multifilament having a three-dimensional crimp stabilized by a heat treatment with a single fiber fineness of 2 to 40 denier and a total fineness of 1,000 to 10,000 denier, forming a non-twisted flat tape shape and porous. A cylindrical filtration layer is formed by being wound on a flexible core tube, and the number of three-dimensional crimps in the filtration layer is 3 to 50 / inch, and the fiber density is 0.15 to 0.50 g / cm ^3. Is characterized by.

Further, in the manufacturing method, a latent solid consisting of a large number of eccentric core-sheath type composite single fibers is obtained by composite spinning of two kinds of thermoplastic synthetic resins having a sheath component having a heat shrinkage rate higher than that of the core component. The crimpable unstretched multifilament is spun, and the latent three-dimensional crimpable unstretched multifilament is stretched and relaxed to develop a three-dimensional crimp, and then heated and subjected to a shrinking treatment to stabilize the crimped form. It is characterized in that the three-dimensional crimped multifilament is wound around a porous cylindrical core material while being stretched in a state where 3 to 50 crimps / inch remain.

As the eccentric type core-sheath type composite single fiber having a three-dimensional latent crimp property, the core component is polypropylene or polypropylene terephthalate, the sheath component is ethylene-propylene copolymer, ethylene-propylene-butene 1 copolymer. Alternatively, high density polyethylene or the like can be preferably applied, and particularly when an ethylene-propylene copolymer is used as a sheath component, uniform fine three-dimensional crimps can be expressed by performing room temperature drawing or hot water drawing and further heating. By processing and shrinking the sheath component, a multifilament having more uniform fine three-dimensional crimps can be obtained.

A three-dimensional crimp obtained by stretching a latent three-dimensional crimpable unstretched multifilament to develop a three-dimensional crimp as described above, and subsequently subjecting this crimped multifilament to a shrinking treatment by heating, Rich in elastic recovery, the crimp shape is stable even when wound on a porous core tube, and a uniform number of crimps can be maintained to form a filtration layer.
In addition, the two-stage treatment of first stretching and relaxing to develop a three-dimensional crimp, and then performing shrinkage heat treatment is performed by varying the stretching ratio and heat treatment temperature to obtain the single fiber fineness of the latent three-dimensional crimpable unstretched multifilament. The number of crimps can be freely changed according to the filtration accuracy of the cartridge filter, which is convenient for obtaining a filtration layer of the cartridge filter suitable for the application.

The eccentric type core-sheath type composite single fiber constituting the latent three-dimensional crimpable unstretched multifilament has a fineness of about 2 to 40 denier after stretching, which is economical for a general cartridge filter. . If the fineness of the single fiber is less than 2 denier, the productivity is poor by the usual melt spinning method, and if the fineness is more than 40 denier, the three-dimensional crimp tends not to develop.

The total fineness is 1000 to 10
A range of 000 denier is desirable in terms of the balance between accuracy in filtration performance and filtration life. Total fineness is 10
If it is smaller than 00 denier, the winding density around the porous cylindrical core material is increased, the number of voids is reduced, and the filtration life is shortened. On the other hand, when it is more than 10,000 denier, the filament bundle becomes thick and unevenness occurs in the voids between the filaments, resulting in deterioration of accuracy.

The number of three-dimensional crimps in the relaxation contraction state after stretching of the multifilament is 12 to 100 per inch.
The number of individual pieces is practically desirable, and after the heat treatment, the three-dimensional crimped multifilament crimp remains, that is, it is wound on a porous cylindrical core material while being stretched with a tension equal to or less than the stretching ratio at the time of crimping treatment. Thus, the number of three-dimensional crimps in the filtration layer can be set to 3 to 50 per inch. When the number of three-dimensional crimps in the filtration layer is less than 8 / inch, the three-dimensional crimp characteristics important for the filtration function cannot be exhibited. The number of three-dimensional crimps in the filter layer is 50 /
If it is larger than an inch, the tension for winding around the porous cylindrical core material is insufficient and the shape maintenance as a cartridge filter becomes unstable.

On the other hand, the fiber density in the filtration layer is 0.15
It is preferably 0.50 g / cm ³ . 0.15 g / cm ³
If the size is made smaller, it is difficult to maintain the form as a cartridge filter, and the pressure resistance during use becomes poor.
If it exceeds 0.50 g / cm ³ , the accuracy is improved, but the filtration life becomes extremely short, and the balance between the accuracy and the filtration life is deteriorated.

[0016]

[Function] A tubular filtration layer formed by winding a multifilament having a three-dimensional crimp on a porous core tube in the form of a flat tape has a bulky nonwoven fabric function despite being a wound type. Even if a multifilament having a small fineness is used to form a uniform void in the entire area and improve the filtration performance, it has an effect of reducing the degree of reduction in filtration life as compared with the conventional case. And since the material of the filtration layer is an unstretched multifilament that develops crimps by stretching, the crimping step and the addition of a finishing oil agent are not necessarily required, and it is economical and a cartridge filter with less foaming by the oil agent can be formed. it can.

[0017]

【Example】

"Example 1" Using polypropylene as the core component (A) and ethylene-propylene copolymer as the sheath component (B), an eccentric core-sheath composite spinning nozzle (pore diameter 0.7 mm, number of holes 722)
Individually, 4 spindles were melt-spun and bundled to obtain a bundle of latently crimpable unstretched multifilaments having a fiber cross section as shown in FIG. 1 and a single fiber fineness of 6 denier. This is 95 ℃
After being stretched 3 times in hot water of 110 ° C., it is subjected to dry heat shrinkage in a hot air dryer at 110 ° C. for 15 minutes to obtain a single fiber fineness of 2.2 denier, a crimp number of 51.0 pieces / inch, and a total fineness of 635.
It was a bundle of multifilaments in which three-dimensional spiral crimps of 0 denier were developed.

Next, this three-dimensional crimped multifilament bundle in a relaxed and contracted state is formed into a tape shape having a width of about 8 mm, and while being stretched to almost twice the apparent length, an inner diameter of 32 mm and an outer diameter are obtained using a crosswinder. Wrap it around a polypropylene core tube with a diameter of 35 mm and a length of 250 mm with a wind angle of 45 degrees until the outer diameter becomes 65 mm,
It was a cartridge filter. The number of crimps of the multifilament in the filtration layer at this time was 25 pieces / inch on average, and the fiber density of the filtration layer was 0.30 g / cm ³ .

Comparative Example 1 The same bundle of latently crimpable unstretched multifilaments as in Example 1 was stretched 3 times in hot water at 95 ° C. and relaxed to develop a three-dimensional crimp, followed by dry heat treatment. Without doing so, a bundle of multifilaments in which a spiral three-dimensional crimp was developed was obtained. The bundle of multifilaments had a single fiber fineness of 2 denier, a crimp number of 25.2 / inch, and a total fineness of 5776 denier. Then, the bundle of multifilaments was stretched to approximately twice its apparent length in the same manner as in Example 1 above,
Using a crosswinder, inner diameter 32mm, outer diameter 35m
A polypropylene porous core cylinder having a length of m and a length of 250 mm was wound with a wind angle of 45 degrees until the outer diameter became 65 mm to obtain a cartridge filter. The average number of crimps of the multifilament in the filtration layer at this time was 12 / inch, and the fiber density of the filtration layer was 0.27 g / cm.
³ , the initial accuracy was 8 μm.

Comparative Example 2 A cartridge filter formed by directly winding a fiber web spun by the melt blow method on a porous core cylinder was obtained. This cartridge filter is provided with a fineness gradient in which the fiber diameter of the web gradually changes in 15 steps such that the fiber diameter of the web is 1.9 μm on the porous core cylinder side and 12.6 μm on the outermost layer side. Had a fiber density of 0.13 g / cm ³ and an initial accuracy of 7 μm.

Comparative Example 3 A polypropylene yarn (2 denier × 76 mm) was used to obtain a roving yarn having a cotton count of 1.0 ^S and a twist number of 2.3 T / inch by a wool spinning machine. This roving was wound around a polypropylene porous core cylinder using a crosswinder in the same manner as in Example 1 described above until the outer diameter became 65 mm to obtain a thread-wound cartridge filter. The fiber density of the filter layer of this cartridge filter was 0.33 g / cm ³ , and the initial accuracy was 15 μm.

After heating the iron plates to the upper and lower end faces of the cartridge filters of Example 1 and Comparative Examples 1, 2, and 3 to smooth the end faces, the filtration performances of the respective cartridge filters were measured and compared. The results are shown in Table 1.

[0023]

[Table 1]

[Example 2] As in Example 1, the core component
Using polypropylene as (A) and ethylene-propylene copolymer as the sheath component (B), melt spinning with one eccentric core-sheath composite spinning nozzle (hole diameter 0.7 mm, number of holes 140) and focusing, A latent crimpable unstretched multifilament having a single fiber fineness of 90 denier having a fiber cross section as shown in FIG. 1 was obtained. This was stretched 4.5 times in hot water at 95 ° C., then relaxed to develop a three-dimensional crimp, and further subjected to dry heat shrinkage treatment in a hot air dryer at 110 ° C. for 15 minutes to obtain a single fiber fineness of 3
It was a bundle of multifilaments expressing a spiral three-dimensional crimp having a denier of 4.5, a crimp number of 19.4 / inch, and a total fineness of 4830 denier.

Then, using a crosswinder, while stretching the three-dimensional crimped multifilament in the relaxed and contracted state to approximately twice the apparent length, a polypropylene porous core cylinder was used to wind a wire angle of 45 in the same manner as in Example 1. It was wound around until the outer diameter became 65 mm, and it was used as a cartridge filter. At this time, the number of crimps of the multifilament in the filtration layer was 10 pieces / inch on average, the fiber density of the filtration layer was 0.28 g / cm ³ , and the initial accuracy was 50 μm.

Comparative Example 4 The same latently crimpable unstretched multifilament as in Example 2 was stretched 3 times in hot water of 95 ° C. and relaxed to obtain a single fiber fineness of 30 denier and a crimp number. The bundle was a multifilament bundle having a spiral three-dimensional crimp having a number of 9.0 pieces / inch and a total fineness of 4,200 denier.

Then, as in Example 1, while expanding the three-dimensional crimped multifilament to approximately twice the apparent length, a polypropylene porous core cylinder was crosslinked with a wind angle of 45 degrees to obtain an outer diameter. Was wound until it became 65 mm to form a cartridge filter. At this time, the number of crimps of the multifilament in the filtration layer was 4.1 pieces / inch on average, and the fiber density of the filtration layer was 0.2.
The initial precision was ³ g / cm ³ and 51.0 μm.

[Comparative Example 5] As in "Comparative Example 2", the fiber density of the filtration layer formed by directly winding the fiber web spun by the melt-blowing method on the porous core cylinder was 0.13.
A cartridge filter having g / cm ³ and an initial accuracy of 51 μm was obtained.

Comparative Example 6 A polypropylene yarn (8 denier × 76 mm) was used to obtain a roving yarn having a cotton count of 1.0 ^S and a twist number of 2.3 T / inch by a wool spinning machine. Using this roving, a thread wound cartridge filter having a fiber density of the filtration layer of 0.30 g / cm ³ was prepared in the same manner as in Comparative Example 3 above. The initial accuracy of this cartridge filter is 4
It was 0 μm.

After heating the iron plates to the upper and lower end faces of the cartridge filters of Example 2 and Comparative Examples 4, 5, and 6 to smooth the end faces, the filtration performances of the respective cartridge filters were measured and compared. The results are shown in Table 2.

[0031]

[Table 2]

The filtration performances in Tables 1 and 2 were measured as follows.

Initial accuracy (μm): 100 ml of the filtrate in the tank (1) is sampled 3 minutes after the passage of the liquid, and the number of particles (N) according to the particle size in the filtrate is measured using a Coulter Counter ZM type. Similarly, the number of particles (M) for each particle size in 100 ml of the stock solution is measured, and the blocking rate for each particle size is calculated from [(M−N) ÷ M × 100]. From these results, a graph of particle size and blocking rate by particle size was plotted, and the particle size at a blocking rate of 90% was read.

Filtration life (l): 120 l in tank (1)
6 g of test dust (JIS 8 types for Examples 1 and 2 and Comparative Examples 1 to 4 and JIS 7 type for Examples 3 and Comparative Examples 5 and 6) were added thereto.
While stirring uniformly with a stirrer (2), undiluted solution (initial concentration 50 p
pm). Set the cartridge filters (4) of the example and the comparative example in the housing (3),
From the outside to the inside of the cartridge filter (4),
The pump (5) is set so that the flow rate is always 40 l / min and the solution is circulated. During this period, 6 g of the dust for the above test was put into the tank (1) every 6 minutes, and by the differential pressure gauge (6) placed between the inflow side and the outflow side of the housing (3) at this time. The total flow rate until the differential pressure reaches 2.0 kg / cm ² was measured.

Initial efficiency (%): Filtrate 1 3 minutes after the start of the passage
1 is taken, the filtrate is evaporated to dryness, and the test dust weight (A) is measured. On the other hand, undiluted solution (initial concentration is 50 pp
m) Calculated from the test dust weight (B) in 1 l by the following formula. Initial efficiency = [(B−A) ÷ B] × 100

Outflow rate of fiber waste (g / l): Water was passed through the cartridge filter (4) at a flow rate of 40 l / min, 1 l of filtrate was collected 3 minutes after the start of water passing, and the filtrate had a pore size of 0.8 μm.
m membrane filter. The membrane filter was dried, and the weight of the discharged fiber waste was measured.

Foaming property: 10 ml of the filtrate at the time of measuring the outflow amount of fiber waste was sampled in a glass test tube, the tip of the test tube was pressed with a finger, and shaken vigorously up and down, and the foaming property of the filtrate was visually judged.

[0038]

As described above, the cartridge filter according to the present invention has a non-twisted flat tape shape in which multifilaments having a three-dimensional crimp having a single fiber fineness of 2 to 40 denier and a total fineness of 1,000 to 10,000 denier are formed. Is wound on a porous core cylinder to form a cylindrical filtration layer,
The number of three-dimensional crimps in the filtration layer is 3 to 50 pieces / inch,
The fiber density is 0.15 to 0.50 g / cm ³ , and in particular, since the filter layer is composed of multifilaments having three-dimensional crimps, there are extremely many fine gaps between the fibers of the filter layer. As shown in Tables 1 and 2, even though the initial accuracy and the initial efficiency are the same as those of the conventional cartridge filter, the filtration life is remarkably improved and the replacement cycle of the cartridge filter during use is greatly extended. be able to.

And such a cartridge filter is
Two kinds of thermoplastic synthetic resins, in which the heat shrinkage rate of the sheath component is larger than that of the core component, are composite-spun to spin a latent three-dimensional crimpable unstretched multifilament composed of a large number of eccentric type core-sheath type composite single fibers, This latent three-dimensional crimped unstretched multifilament is stretched and relaxed to develop a three-dimensional crimp, and the crimped multifilament is subjected to a shrinking treatment by heating to impart crimp elasticity. In the state where 8 to 50 crimps remain, that is, by winding it on a porous cylindrical core material while elongating it with a tension equal to or less than the draw ratio at the time of crimp expression treatment, the efficiency is the same as that of the conventional wound cartridge filter. Can be manufactured well,
It is also advantageous in terms of manufacturing cost.

In addition, the three-dimensional crimped multifilament wound around the porous core tube is further heat-treated after being stretched and relaxed, so that the crimped form in the filtration layer is stable and the filtration life value with respect to the initial accuracy value is remarkably improved. be able to.

Further, the latent three-dimensional crimpable unstretched multifilament is crimped by hot water drawing treatment such as an ethylene-propylene copolymer as a sheath component and a polypropylene eccentric type core-sheath type composite single fiber as a core component. When a composite fiber expressing the above is used, it is not necessary to apply a finishing oil agent after the drawing treatment, and it is possible to obtain a cartridge filter with very little foaming during the initial liquid passage, which is convenient for the food industry and the pharmaceutical industry.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an eccentric type core-sheath type composite fiber.

FIG. 2 is a schematic explanatory view of a multi-pass type filtration performance measuring device.

[Explanation of symbols]

 A. Core component B. Sheath component

Claims (3)

[Claims] 1. A multi-filament having a three-dimensional crimp stabilized by a heat treatment with a single fiber fineness of 2 to 40 denier and a total fineness of 1,000 to 10,000 denier forms a non-twisted flat tape shape and is a porous core tube. It is wound up to form a tubular filter layer, and the number of three-dimensional crimps in the filter layer is 3 to 50 / inch, and the fiber density is 0.15 to 0.5.
Cartridge filter characterized by being 0 g / cm ³ . 2. A latent three-dimensional crimpable unstretched multi-fiber comprising a large number of eccentric type core-sheath type composite fibers obtained by composite spinning of two kinds of thermoplastic synthetic resins having a sheath component having a heat shrinkage rate higher than that of the core component. The filament is spun out, and the latent three-dimensional crimped unstretched multifilament is stretched and relaxed to develop a three-dimensional crimp, and then heated and subjected to a shrinking treatment to stabilize the crimped form. The number of crimps is 3 to 50
A method for manufacturing a cartridge filter, which comprises winding a porous cylindrical core material while stretching it into a state of remaining pieces / inch. 3. The production of a cartridge filter according to claim 2, wherein the latent three-dimensionally crimpable unstretched multifilament is an ethylene-propylene copolymer as a sheath component and a polypropylene eccentric type core-sheath type composite fiber as a core component. Method.