JP2009082899A - Filter element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive filter element which has a small pressure difference when passing liquid and demonstrates high bactericidal effect even if clogging of a filter medium is reduced, has water-resistance, causes very little elution of silver to the treating object liquid, has durability and a long life, and is easily processed. <P>SOLUTION: The filter element 10 has a filter medium layer 14 formed on an outer peripheral side face of a cylindrical core 12 having through-holes 12a on the peripheral side face, with at least one end opened, by winding twist yarn 14a. The twist yarn 14a contains 5-50 wt.% of organic fiber plated with silver at the ratio of 5-40 wt.% in relation to the fiber weight, and has an average pore diameter of the filter medium layer 14 of 20-90 μm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a filter element capable of capturing and sterilizing / removing microorganisms in a liquid to be treated by utilizing the sterilizing action of silver, thereby preventing the growth and proliferation of microorganisms.

  Traditionally, in the food production process from the agricultural field to the beverage and food manufacturing field, it is essential to remove microorganisms contained in water and liquid raw materials, preventing the occurrence of crop diseases in the agricultural field, and the microorganisms in washing water for raw vegetables Sterilization of microorganisms mixed in the liquid is indispensable for ensuring the safety of contamination and safety, as well as for the safety of raw water and food materials in the field of beverage and food production. Technologies such as disinfectant administration, filtration, heating, and ultraviolet treatment are required. Has been incorporated. Hydroponic cultivation in the agricultural field is a cultivation technique that provides high quality and high yield, and is a cultivation technique that increases by an area of 10% per year and is adopted by many large plant factories. However, when plant pathogens invade into the circulating culture solution, the pathogens spread throughout the facility and cause serious damage. Therefore, sterilization techniques using ozone sterilizers and ultraviolet sterilizers have been studied. However, these sterilization techniques have the disadvantage that they cause transformation of the culture solution and cause growth defects in crops such as iron deficiency, and the equipment cost is high, power is required, and it is difficult for general farmers to introduce It is in. Also in the beverage and food manufacturing field, a sterilization apparatus suitable for the processing amount has a high apparatus cost. In particular, it is troublesome to modify an existing line and cannot be easily introduced.

  Silver has a high bactericidal effect on microorganisms, but is a safe sterilizing material with low toxicity to higher animals. In an aqueous solution, it exhibits a bactericidal effect at a concentration of ppb, and also exerts a high bactericidal power against microorganisms by contact with silver atoms. Using this principle, products that apply the principle of sterilizing microorganisms by releasing silver ions into solution have been developed and used in the agricultural field, but materials that elute silver ions in large quantities are highly sterilized. While the effect is obtained, there is a problem of developing a growth disorder due to silver on the plant. In addition, depending on the type of solution, the elution rate is fast, so that there is a problem in durability and cost. On the other hand, in the beverage and food manufacturing field, there is a drawback that the silver ion concentration may exceed 50 ppb, which is the standard of WHO (World Health Organization), and cannot be used.

In order to solve these problems, attempts have been made to propose and commercialize a contact-type sterilizing filter that passes a liquid to be treated through a filter and sterilizes the liquid by bringing the liquid into contact with the silver surface. As products that have been commercialized, there is a filter in which silver is supported on an inorganic substance, is made into a sheet with paper, and is incorporated into a cylindrical shape as a filter medium. In addition, as a liquid filter using silver-plated fibers, a filter in which silver-plated fibers are packed between the outer tube and the inner tube for a bathtub, and a non-woven fabric made of silver-plated fibers is subjected to pleating so that the outer tube and the inner tube A filter installed as a filter medium between them and a thread wound filter made using a string including silver-plated fibers have been proposed (see Patent Document 1).
JP-A-8-71338

  However, since the former filter uses paper for the filter medium, the filter medium pore diameter is as small as 10 μm or less, and the differential pressure during liquid passage is large. In addition, this filter system has a serious problem in durability and life, coupled with the fact that clogging is fast despite the use of a pre-filter, and the filter medium itself is not water resistant.

  Furthermore, in the filter disclosed in Patent Document 1, although durable silver-plated fibers are used, in the filter in which silver-plated fibers are packed between the outer tube and the inner tube, the fibers are intertwined. Since it is weak, there have been problems such as the outflow of fibers and the increase in differential pressure and clogging during liquid flow due to the unevenness of the fibers. In addition, a filter made by applying pleating to a nonwoven fabric as a filter medium is troublesome in manufacturing, and the yield of silver-plated fibers is poor, and the number of parts constituting the filter increases, which increases the cost. is there. Furthermore, with a thread-wound filter made using a string containing silver-plated fibers, simply using silver-plated fibers as the filter material of the thread-wound filter eliminates the problems of differential pressure and clogging during liquid flow and provides a high sterilizing effect. Could not be obtained.

  Therefore, the object of the present invention is to produce a high bactericidal effect even if the pressure difference during the passage of liquid is small and clogging of the filter medium is reduced, and furthermore, it has water resistance, and the elution of silver to the liquid to be treated is negligible. It is to provide a filter element that is durable, has a long life, is easy to process and is low in cost.

The invention according to claim 1 is a filter element in which a filter medium layer is formed by winding a twisted yarn on an outer peripheral side surface of a cylindrical core having a through hole on a peripheral side surface and having at least one end opened. Is a filter element containing 5 to 50% by weight of organic fibers plated with silver at a ratio of 5 to 40% by weight with respect to the fiber weight, and having an average pore diameter of the filter medium layer in the range of 20 to 90 μm. .
The invention according to claim 2 is the filter element according to claim 1, wherein the organic fiber plated with silver is plated by electroless plating by a silver mirror reaction.

  The filter element according to the present invention has a small differential pressure at the time of liquid passing, so there is less burden on devices such as pumps, less clogging and water resistance, and silver elution into the target liquid is negligible and durability / lifetime However, it is advantageous in that it can be easily introduced by the user because it is long, yet easy to process, low in cost, and highly convenient. Furthermore, the filter element according to the present invention enables sterilization and removal of harmful microorganisms in water for agricultural use, and prevents harmful microorganisms such as prevention of crop diseases in hydroponic cultivation and prevention of market diseases by water sterilization for washing crop crops. Prevents harm caused by the production and contributes to the stabilization of production. In the field of beverage and food manufacturing, raw water and solution food processing materials can be filtered to prevent microbial contamination of food and to ensure its safety.

  FIG. 1 is a perspective view with a part broken away showing an embodiment of a filter element according to the present invention. The filter element 10 includes a core 12. The core 12 is disposed at the center of the filter element 10 and supports a filter medium layer 14 described later from the inside. The core 12 is made of a plastic such as polypropylene, polyethylene, or a fluororesin such as PTFE or PFA. As shown in FIG. 1, the shape is cylindrical with one end opened. In addition, a large number of through holes 12 a are provided on the peripheral side surface of the core 12. Thus, the liquid to be processed flows inward from the outer peripheral side surface of the core 12 and can be smoothly discharged from the opening. In the embodiment of FIG. 1, the opening portion is provided only at one end of the core. However, the present invention is not limited to this, and the opening portion is provided at both ends, and the liquid to be processed flowing from the outer peripheral side surface is provided. You may comprise so that it may discharge from the opening part of both ends.

  A filter medium layer 14 is formed on the outer peripheral side surface of the core 12. The filter medium layer 14 is formed by winding a twisted yarn 14 a so as to cover the outer peripheral side surface of the core 12. The twisted yarn 14a is made of a mixed fiber of an organic fiber having water resistance and an organic fiber plated with silver (hereinafter simply referred to as “silver-plated fiber”). As the organic fiber having water resistance, synthetic organic fibers such as polyester fiber, acrylic fiber, polyethylene fiber, polypropylene fiber, and polyimide fiber can be used alone or in combination of two or more. As the silver-plated fiber, a fiber made of a water-resistant material that can be silver-plated is applicable. For example, synthetic organic fibers such as polyester fiber, acrylic fiber, and polyimide fiber are used alone or in combination of two or more. be able to.

  Either electroless plating or vacuum deposition plating can be applied to silver plating on organic fibers, but there is no point in that the plating is stable and the productivity is excellent even if the amount of silver plating is large. It is preferable to use an electrolytic plating method. Furthermore, among electroless plating methods, the adhesion strength of plating to organic fibers is high, and silver elution is negligible. As a result, durability and life can be improved. Further preferred. The silver plating amount is preferably 5 to 40% by weight based on the fiber weight. This is because if the plating amount is less than 5% by weight, there is a problem in durability and life. On the other hand, if it exceeds 40% by weight, the fiber becomes inflexible and the workability becomes a problem, and the plated silver is peeled off. This is because there is a possibility. Moreover, it is preferable to make the ratio which contains silver plating fiber in the twisted yarn 14a into the range of 5 to 50 weight%. If the amount is less than 5% by weight, the chance of contact with the silver-plated fiber is small when the liquid to be treated is passed, so that the bactericidal effect is poor. This is because there is a possibility of exceeding 50 ppb, which is the standard of the institution), and it cannot be used in the beverage / food manufacturing field, and the cost increases.

  As a method for producing the twisted yarn 14a, it is preferable to use a spun spinning in which a large amount of crimp (crimp) remains in the fibers of the twisted yarn 14a. This is because a lot of crimp remains in the fibers of the twisted yarn 14a, so that a turbulent flow is generated in the liquid to be processed that passes through the filter medium layer 14, and the liquid to be processed efficiently comes into contact with the silver-plated fibers, This is because a high bactericidal effect is exhibited.

  The average pore diameter of the filter medium layer 14 is preferably adjusted to be in the range of 20 to 90 μm. This is because if the average pore size is smaller than 20 μm, the pressure difference during liquid passing is large, so the load on the pump and other devices is large, and even if a prefilter is used, clogging is fast, and there is a big problem in durability and life. is there. On the other hand, if the thickness exceeds 90 μm, there is a high possibility that the bacteria in the liquid to be treated pass through the filter medium layer 14 before coming into contact with the silver-plated fiber when the liquid is passed. The average hole diameter may be adjusted by adjusting the fiber diameter of the twisted yarn 14a, the number of yarns, and the density at which the twisted yarn 14a is wound around the outer peripheral side surface of the core 12.

  The filter element 10 according to the present invention has a high sterilization effect because the liquid to be treated comes into contact with the silver-plated fiber with high efficiency despite the fact that the differential pressure at the time of liquid flow is small and clogging is small due to the above-described configuration. Can be expressed. In addition, it is water resistant and has excellent durability and longevity due to minimal elution of silver. Furthermore, since the manufacturing process is simple, the cost is not increased.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, the core 12 of each Example used the cylindrical thing of 10 inches in height and 36 mm of outer diameters which provided many through-holes in the outer peripheral side surface in common. And the twisted yarn 14a was each wound by the outer peripheral side surface of this core 12, and it was set as the filter element of each Example.

  In Example 1, an acrylic fiber having a single yarn fineness of 2.2 dtex was used as the organic fiber serving as the base material of the silver-plated fiber. This acrylic fiber was silver-plated by electroless plating so that the plating ratio was 15% by weight. The electroless plating method used in this example is electroless plating based on a silver mirror reaction. The specific plating procedure will be explained. After immersing acrylic fiber in a scouring agent and washing with water, it is immersed in an aqueous solution containing 10 g / L of stannous chloride and 20 ml / L of hydrochloric acid. After the addition, an ammoniacal silver nitrate solution having a composition of 31.6 g / L silver nitrate and 100 mlg / 2 L aqueous ammonia was added to a mixed solution of ethylenediaminetetraacetic acid tetrasodium 200 g / 2 L, sodium hydroxide 50 g / 2 L and formalin 100 ml / 2 L at 25 °. It was dripped in C and silver was electrolessly deposited on the surface of the organic fiber and plated. In addition, since all the silver ions in the plating solution are reduced and deposited, the ratio of silver to the fiber can be accurately defined.

  Next, the yarn made of the silver-plated fiber and the polypropylene yarn having a fineness of 6.6 dtex are set so that the silver-plated fiber contains 15% by weight, and twisted, 0.6 cotton count, twisted yarn of 100 t / m It was. Then, 120 g of this twisted yarn was wound around the outer peripheral side surface of the core to produce a filter element having an average pore diameter of 70 μm. The flow rate characteristics, silver ion elution test and sterilization performance results of the produced filter element are as follows.

1. The differential pressure was 2 Kpa at a flow rate of 40 L / min per minute, the differential pressure was low, and there was almost no burden on the pump.
2. Silver ion elution test (1) Test conditions: 30 L of raw water was circulated through the filter element of Example 1 at a circulating water volume of 7 L / min, and the silver ion concentration in the raw water was measured with an ICP emission spectrometer. did. The test results are shown in Table 1.

As is apparent from the values in Table 1, the elution amount of silver ions from Example 1 was very small, 2 ppb or less per pass.
3. Bactericidal performance (1) Fluid flow test: Sprouting effect of spore of plant pathogenic fungi (Executing agency: Osaka Prefectural Food and Green Technology Center)
(A) Test conditions / Pathogen: Suspended in tap water to a concentration of 10 ⁵ cfu / ml each of a small conidia of Fusarium oxysporum and a zoospore of Pythium aphanidermatum The sample (pathogen suspension) was used as a specimen and subjected to a filtration test.
Treatment method: 75 L of pathogen suspension is passed through the filter element of Example 1 at a flow rate of 10 L per minute in one pass, and pathogens (conidia, migration) in the passing solution after 2 to 3 minutes have elapsed from the start of passage. The survivors were investigated.
・ Investigation by hanging drop culture: For zoospore germination of P. afanidelmartam, the passing solution was suspended and cultured on a slide glass (24 hours, room temperature), and the germination rate was examined with the naked eye using an optical microscope. did.
-Investigation of germination rate by culture: The bactericidal effect of small conidia of Fusarium oxysporum was investigated by a dilution plate method using a passage medium as a selective medium (potato-glucose agar medium added with 30 ppm streptomycin and 30 ppm myconazole). As Comparative Example 1, a normal PP prefilter not containing silver-plated fibers was applied, and the test was performed under the same conditions as described above. The test results are shown in Table 2.

  In Comparative Example 1, only 34% of Fusarium oxysporum conidia were killed and 41.8% of Psium aphanidermatum zoospores were killed, whereas in Example 1, Fusarium oxysporum small conidia were killed. Ninety-six percent of the offspring died, and all of them were killed in the Psium Aphanider Martam zoosporea. Thereby, it has confirmed that the filter element of Example 1 expressed the high bactericidal effect with respect to the phytopathogenic microbe mixed in the nutrient solution culture medium.

(2) Control test: Control test against cucumber root rot (Executing organization: Osaka Prefectural Food and Green Technology Center)
(A) Test conditions-Hydroponic culture solution volume 140L, Sonoken Okotsu prescription 1 unit, pH 6.4
・ Inoculate the hydroponic culture tank with phytopathogenic fungus Picium afanidelmartam (3 x 10 cfu / ml), circulate the hydroponic culture for 1 hour, then plant cucumber seedlings (2 leaves), hydroponic culture Was circulated twice a day (each for 30 minutes). FIG. 2 shows a graph of the test results. As is apparent from FIG. 2, in the case of no treatment, the disease incidence was 45% in about 4 weeks after inoculation with the phytopathogenic fungi, whereas the filter element of Example 1 was used. Was kept at 0%, and it was confirmed that it had the effect of preventing the occurrence of root rot caused by Pycium aphanidermartam.

  In Example 2, an acrylic fiber having a single yarn fineness of 2.2 dtex is used as an organic fiber serving as a base of the silver-plated fiber, and electroless plating is performed under the same conditions as in Example 1, and silver is added to 25% by weight. Plated.

  Next, the yarn made of the silver-plated fiber and the polypropylene yarn having a fineness of 5.5 dtex are set so that the silver-plated fiber contains 30% by weight, and then twisted, 0.6 cotton count, twisted yarn of 100 t / m It was. 150 g of this twisted yarn was wound around the outer peripheral side surface of the core to produce a filter element having an average pore diameter of 30 μm.

The flow characteristics and sterilization performance results of the filter element of Example 2 are as follows.
1. Flow rate characteristics The flow rate was 40 L / min and the differential pressure was as low as 8 Kpa, so there was almost no burden on the pump.
2. Bactericidal performance (a) Test conditions 7 tons of food processing fluid containing sugar was circulated for 6 hours while being filtered using Example 2, and then the circulation was stopped. ) Was measured over time. In Comparative Example 2, Comparative Example 2 was obtained by performing the same treatment without using the filter element of Example 2 and performing the filtration treatment. The results are shown in Table 3.

  In the case of Comparative Example 2, the number of general bacteria rapidly increased to 3,480 cells / ml after 10 hours (4 hours after the circulation was stopped). On the other hand, when Example 2 was used, the number of general bacteria was as low as 10 / ml even after 10 hours, and the growth of general bacteria in the food processing liquid was suppressed by the filter element of Example 2. It was confirmed that

  In addition, although the filter element concerning this invention was demonstrated using Example 1 and Example 2, this invention is not limited to these. What is necessary is just to set it as a desired filter element by changing suitably within the range as described in a claim.

It is the perspective view solution figure which fractured | ruptured partially which shows one Embodiment of the filter element concerning this invention. It is a graph which shows the test result of the control test with respect to the cucumber root rot performed using Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Filter element 12 Core 12a Through-hole 14 Filter material layer 14a Twisted thread

Claims (2)

A filter element in which a filter medium layer is formed by winding a twisted yarn on an outer peripheral side surface of a cylindrical core having a through hole on a peripheral side surface and having at least one end opened,
The twisted yarn contains 5 to 50% by weight of organic fiber plated with silver at a ratio of 5 to 40% by weight with respect to the fiber weight,
The filter element whose average pore diameter of the said filter medium layer exists in the range of 20-90 micrometers.   The filter element according to claim 1, wherein the organic fibers plated with silver are plated by electroless plating by a silver mirror reaction.

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