JP2008006320A - Cleaning regeneration filtering media and method for manufacturing cleaning regeneration filtering media - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning regeneration filtering media capable of easily cleaning dust fixed to the media with washing and a filter unit capable of performing regeneration with washing using the filtering media. <P>SOLUTION: The cleaning regeneration filtering media contain fluorine atom and carboxyl group in the molecular structure of a raw material comprising the filtering media. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an air purifier, a 24-hour ventilation system air conditioner used in general households, an air conditioner for general buildings and factories, home appliances, an on-vehicle air conditioner, etc. The present invention relates to a cleaning / regeneration filter medium that can be suitably used for a liquid cleaning / regeneration filter unit such as a solid-liquid separator.

  Many filter units currently used for air conditioning management in buildings are disposable, but in some filter units, the filter unit is immersed in a cleaning solution in which detergent is dissolved, and ultrasonic waves are irradiated in that state to dissolve the cleaning unit. Cleaning and regeneration are performed using the action and the physical action of ultrasonic waves. However, in air conditioning filter units and household air cleaning filter units whose purpose is to collect fine dust, ultrafine carbon particles and tobacco of about 0.1 μm contained in diesel exhaust gas are used as components of collected dust. Various dust components such as smoke, oil discharged from the kitchen, general atmospheric dust and fiber scraps are firmly fixed, and it is actually the case that they are not sufficiently removed just by immersing them in cleaning liquid and applying ultrasonic waves.

  For this reason, Patent Document 1 and Patent Document 2 disclose techniques for improving the cleaning and regeneration ability by treating the filter medium with a surfactant in advance and collecting dust on the filter medium. This method is a technique aimed at improving dust releasability by improving the hydrophilicity of the fiber. However, since the surface active agent is only applied to the surface of the filter medium, the first cleaning can provide some cleaning performance, but the surfactant is washed away with dust in the rinsing step after the cleaning, and the second and subsequent times. There has been a problem that the cleaning and regeneration ability of the above becomes extremely worse. Also, when cleaning household air purifier filter units, for example, high-collection filter units that collect 99% of particles with a particle size of 0.3 μm, there is no ultrasonic machine in the home, soak in running water. Since it was not possible to expect sufficient detachment of the dust with a flow rate of 1, the air permeability could not be fully recovered. Further, the filter medium constituting the high collection filter unit is usually subjected to electret treatment. However, if the filter medium made of polypropylene fiber is treated with a surfactant, electret conversion becomes impossible due to the influence of ions. . Therefore, until now, it has been impossible to make an electret filter with high cleaning and regeneration ability.

  On the other hand, as disclosed in Patent Document 3, a method of attaching a fluororesin is widely performed in order to impart water repellency to the filter medium. However, since this method applies the fluororesin to the filter medium with a size roll or the like, it acts in the direction of clogging the voids between the fibers. For this reason, in particular, when a material composed of ultrafine fibers such as a melt blown nonwoven fabric composed of ultrafine fibers having a fiber diameter of 3 to 6 μm is used as a filter medium, there is a drawback that the airflow resistance is greatly increased.

In addition, a technique for hydrophilizing the filtration material is also disclosed in Patent Document 4. The technique described in this document is to place a lipophilic ultra-high molecular weight polyethylene porous film in a hydrocarbon gas atmosphere such as argon to perform plasma processing to make it hydrophilic. According to this method, a hydrophilic group is attached to the surface of the fiber constituting the filter medium immediately after processing, but the hydrophilic group falls into the fiber as time passes, so that the hydrophilicity is lowered and the cleaning property is maintained. There was a problem of not doing. Patent Document 4 also introduces a method for treating the membrane with a fluorine-based surfactant or the like to increase the hydrophilicity of the hydrophobic membrane, and a method for surface treatment by contacting the membrane with fluorine gas. Has been. However, since these are all applied to the surface of the filter medium, there are problems as described above.
JP 2002-66222 A JP 2002-102620 A Japanese Patent Laid-Open No. 2003-080015 JP 2000-317280 A

  An object of the present invention is to provide a cleaning / regeneration filter medium and a cleaning / regeneration filter unit that can sufficiently reduce attached dust even after cleaning at home, and that can be improved in air permeability.

The present invention for solving the above-described problems is characterized by the following (1) to (5).
(1) A cleaning and regenerating filter medium containing a fluorine atom and a carboxyl group in the molecular structure of the material constituting the filter medium.
(2) The washed and regenerated filter medium according to (1), wherein the water suction height measured in accordance with the birec method described in JIS L1907 (2004) is 5 mm or more.
(3) The cleaning / regenerating filter medium according to (1) or (2), comprising at least an electret nonwoven fabric.
(4) A cleaning / regenerating filter unit using the cleaning / regenerating filter medium according to any one of (1) to (3).
(5) A method for producing a washed and regenerated filter medium, wherein fluorine atoms and carboxyl groups are introduced into the molecular structure of the material constituting the filter medium by reacting with fluorine, oxygen, and moisture.

  Since the carboxyl group is introduced into the molecular structure of the material constituting the filter medium, the washing and regenerating filter medium of the present invention has a melt blown nonwoven fabric, polyester fiber nonwoven fabric, microporous PTFE membrane, microporous material composed of polypropylene fibers of ultrafine fibers. Even a highly water-repellent material such as a PE film can exhibit high hydrophilicity and can exhibit high cleaning reproducibility. Moreover, by introducing a fluorine atom together with a carboxyl group into the molecular structure of the material constituting the filter medium, it is possible to effectively prevent the polar COOH group from eluting into water. As a result, the hydrophilic effect can be exhibited for a long time.

  Moreover, the filter medium of the present invention has high cleaning regenerative properties, and can exhibit high cleaning regenerative properties without using an ultrasonic cleaner or chemicals. It is also possible to use it suitably for the microfiltration of the liquid which becomes a problem.

  The cleaning / regenerating filter medium and the cleaning / regenerating filter unit of the present invention will be described taking an air filter as an example. A filter unit for use in an air filter is formed by, for example, stacking and integrating a filter medium made of an ultrafine fiber nonwoven fabric that exhibits collection performance and a nonwoven filter medium for reinforcing the filter medium. The collection performance under the rated air flow conditions determined for each filter unit is preferably 10% or more, preferably 15% or more and 99.99% or less for particles having a particle diameter of 0.3 to 0.5 μm. Preferably there is. The present technology is particularly suitable for a filter medium used in such a high-performance filter unit. Specifically, it is suitable for filter media used in filter units for home air purifiers, building air conditioners, and industrial use.

  The material of the filter medium constituting the filter unit is not particularly limited, and woven or knitted fabric or nonwoven fabric using a synthetic fiber such as polypropylene, polyester, polylactic acid, polyethylene, fluororesin, vinylon, nylon, rayon, or net-like. It can be used widely, such as a microporous film made of a product or an organic polymer.

  As described above, when the filter unit is composed of a plurality of filter media, it is preferable to use a non-woven fabric made of polypropylene fibers as a material for the filter media exhibiting the collection performance. Polypropylene fiber nonwoven fabric can be electretized to increase the collection efficiency. Moreover, it is preferable to use the nonwoven fabric which consists of a polyester fiber and a vinylon fiber with a small dimensional change rate and a large Young's modulus even if immersed in the washing | cleaning liquid (aqueous system) at the time of washing | cleaning as a reinforcing material of the filter medium which exhibits collection performance. Furthermore, PTFE, a fluororesin that exhibits excellent performance in terms of water repellency and chemical resistance, woven and knitted fabrics such as vinylidene fluoride, non-woven fabrics, and microporous membranes become hydrophilic and liquid-permeable by applying the present invention. Since it can be improved, it is a suitable material in that it has both high collection and chemical resistance.

When woven or knitted fabric or nonwoven fabric is used as the material of the filter medium that exhibits the collection performance, in order to obtain the collection performance of about 10% to 70% with respect to the particles having a particle diameter of 0.3 to 0.5 μm, the average fiber It is preferable to use a material having a diameter of 0.5 to 10 μm and a basis weight of 10 to 100 g / m ² . A finer fiber diameter has a lower basis weight and higher collection performance, but the physical detachability of the captured solid particles tends to deteriorate. For this reason, the average fiber diameter should be thick, and 2 μm or more is particularly preferable. On the other hand, if the average fiber diameter becomes too large, it is necessary to increase the basis weight in order to obtain the same collection performance, which is not economical. For this reason, the average fiber diameter is particularly preferably 7 μm or less. Since introduction of COOH groups and fluorine atoms is not subject to processing restrictions due to fiber diameter or basis weight, the material may be determined from the required collection performance, ventilation resistance, and dust detachability.

  In addition, when using a nonwoven fabric made of polyester fiber, vinylon fiber, rayon or the like as a reinforcing material, a nonwoven fabric produced by a dry method or a wet method can be widely used, and this also has restrictions related to the introduction of COOH groups and fluorine atoms. Therefore, it is only necessary to select the thickness, basis weight, and stiffness of the fiber from the viewpoint of the dust retention amount related to the life and the rigidity as the reinforcing material.

  In the present invention, the molecular structure of the material constituting the filter medium includes fluorine atoms and carboxyl groups. Next, a method of introducing fluorine atoms and carboxyl groups into the above materials (hereinafter referred to as F processing). ) Will be described using a polypropylene ultrafine fiber nonwoven fabric as an example.

First, a polypropylene ultrafine fiber nonwoven fabric is put in a sealed tank, the air in the tank is evacuated, and oxygen gas is introduced into the tank from the outside together with fluorine gas prepared by electrolyzing hydrogen fluoride. As a result, C—H bonds on the polymer surface and C—F bonds are introduced into C—CH ₃ , and the reaction of the following formula proceeds.

(CH ₂ CHCH ₃ ) _n + F ₂ + O ₂ → (CF ₂ CFCOF) _n → (CF ₂ CFCOOH) _n
The methyl group of the polypropylene side chain is divided into those that become CF ₃ and those that change to —COF, but because —COF is unstable, it immediately reacts with moisture in the air and the moisture of the substrate— Change to COOH. As a result, the material constituting the filter medium is polarized on the polymer surface, and water repellent and hydrophilic parts are mixed at the molecular structure level, but on the whole, there are carboxyl groups located on the outside in terms of molecular structure. This is because it exerts a dominant effect or is hydrophilic.

  At this time, it is also possible to adjust the balance between water repellency and hydrophilicity by adjusting the ratio of substitution with carboxyl groups, which can be adjusted by the mixed concentration of oxygen gas.

  Subsequently, the principle of improving the cleaning and regeneration ability of the filter medium by imparting hydrophilicity as described above will be described.

  The particles to be collected by the filter unit are usually solid particles and liquid particles, and these particles are considered to be composed of oily components and water-soluble components. In the air purifier filter used in homes and buildings, in addition to dust contained in the general atmosphere, sand dust, fiber scraps, tobacco smoke, fine dust and the like specific to the use environment are collected particles. For example, in a filter unit used in a place facing a road, fine carbon particles and oil components estimated to be derived from diesel exhaust gas are also collected particles. When the state of these particles collected in the fiber is actually observed with a microscope, only the solid particles retain the shape of the particles before adhesion, and the liquid particles having high hydrophilicity are spread and adhered. Further, it is considered that the liquid particles spread and adhered fill the gaps between the solid particles, and as a result, act as an adhesive for the solid particles. This situation can be particularly observed with a domestic air purifier filter unit that mainly collects tobacco smoke. In other words, it is presumed that tobacco smoke is abundantly water-containing particles, spreads on the filter medium surface, adheres, dries and adheres.

  In order to wash off the collected particles from the filter medium in such a state, it is necessary that the cleaning liquid is sufficiently infiltrated into the particle collecting portion. In particular, it is necessary that the cleaning liquid penetrates into the interface portion between the surface of the filter medium to which the particles adhere and the particles, so that components soluble in the cleaning liquid are dissolved and the particles are easily dropped.

  However, when the material constituting the filter medium is made of a conventional polypropylene ultrafine fiber nonwoven fabric, the filter medium has high water repellency. Therefore, synthetic detergent for home laundry, for example, P & G Co., Ltd. Arière, Lion Co., Ltd. top, Kao ( Even if it is dipped in a cleaning solution in which an attack of Co., Ltd. is dissolved, the cleaning solution hardly penetrates. Therefore, even if the cleaning liquid permeates the particles fixed on the surface of the filter medium, the cleaning liquid does not easily permeate the particles trapped in the spaces formed between the fibers inside the filter medium, and the particles are sufficiently washed out in a short time. Is difficult.

  On the other hand, even if the material constituting the filter medium is a polypropylene ultrafine fiber non-woven fabric, the washed and regenerated filter medium of the present invention is made hydrophilic by incorporating a polar carboxyl group and a fluorine atom into a fiber constituent molecule. If the filter medium is immersed in the cleaning liquid, the cleaning liquid quickly penetrates into the inside of the filter medium together with the particles on the surface of the filter medium, and further to the particles trapped in the filter medium, and the particles swell and dissolve components soluble in the cleaning liquid from the particles. As a result, the scaffold for the particles adhering to the filter medium is lost, and the particles can be washed off quickly.

  Further, when the liquid particles having high hydrophilicity are brought into contact with the fiber surface having high hydrophilicity, the liquid particles spread and adhere to the surface of the filter medium as compared with the liquid particles having low hydrophilicity. For example, in a cigarette smoke particle adhesion experiment, solid particles such as dust contained in the atmosphere also adhere to the fiber, but the tobacco smoke particles rich in water contact the filter medium and spread to adhere to the microscope. Can be seen by observation. At this time, the washing regenerated filter medium of the present invention is likely to spread the liquid particles further laterally because the material constituting the filter medium has both a water-repellent part and a hydrophilic part when viewed locally. As a result, the adhesion enhancement of the solid particles due to the liquid particles spreading and weakened is weakened, and it becomes easier to wash away with the cleaning liquid.

  Furthermore, techniques for introducing hydroxyl groups and carboxyl groups by corona discharge treatment and plasma treatment as surface modification techniques have been known, but the hydrophilic effect was not sustained sufficiently with these techniques, In the filter medium of the present invention, the hydrophilic effect is maintained over a long period of time. The reason is not clear, but it is thought that the presence of the fluorine atom together with the carboxyl group makes it difficult for the carboxyl group to enter the fiber.

  The F processing can be applied only to a part of the filter media when the filter unit is constituted by a plurality of filter media. However, it is preferable to apply to all the filter media in order to improve the washing reproducibility.

  Further, unlike the conventional surface treatment with a surfactant, the F processing is a dry process that does not use water, and therefore does not require dip mangle processing for removing excess water, and the filter medium is not crushed. For this reason, a bulky hydrophilic filter medium can be obtained, the penetration of the cleaning liquid becomes better, and the detachability of the collected particles is further improved.

In the present invention, when the fluorine atom and the carboxyl group are included in the molecular structure of the material constituting the filter medium, the concentration and treatment time of fluorine and oxygen are controlled, and the birec described in JIS L1907 (2004). It is preferable that the water suction height measured in accordance with the law is 5 mm or more. By setting this value to 5 mm or more, the cleaning method that can be performed at home, that is, by immersing it in water in which general laundry detergent or kitchen detergent is dissolved, and then washing it with running water, the collected particles The dropout is effectively improved and the recovery rate of the filter air permeability (pressure loss) is drastically improved. Expressed by the pressure loss recovery rate of the filter, this value is about 85% when it is 4 mm or less, but it is about 95% when it is 5 mm or more. The concept of the pressure loss recovery rate can be said to be extremely high because, for example, the industry is trying to set the industry standard of regeneration capacity to 90% or more for air-conditioning cleaning regeneration filters. The more preferable range is 10 mm or more, while the upper limit is preferably 200 mm, and more preferably 20 to 150 mm. Furthermore, in the present invention, the filter medium constituting the filter unit may include at least an electret nonwoven fabric. preferable. The electret processing may be performed by a known method, and can be performed on, for example, polypropylene woven or knitted fabric, non-woven fabric, fiber or fluororesin microporous film. In addition, when performing an electret process and the said F process to the same filter-medium constituent material, it is necessary to pay attention to the order. For example, when electret processing is performed by the corona discharge method disclosed in Japanese Patent Application Laid-Open No. 1-287914, there is almost no difference in collection performance regardless of whether it is performed before or after F processing. In the case of performing the hydrocharge method disclosed in Japanese Patent No. 501604, it is preferable to perform F processing first and then perform electret processing. By performing the F processing first, the hydrophilicity of the polypropylene is increased, and water penetrates into every corner of the fiber entanglement inside the nonwoven fabric, increasing the wetted area. As a result, a high charge amount can be given to the workpiece, and an electret filter medium with high collection performance can be obtained.

  The F processing can be verified by ESCA analysis.

  Hereinafter, although the washing | cleaning reproduction | regeneration filter material and washing | cleaning reproduction | regeneration filter unit of this invention are demonstrated concretely using an Example, it is not limited to description content.

  In addition, the water suction height of the filter medium performed in the Examples was measured by the birec method (water absorption time 10 minutes) described in the water absorption test method JIS L1907 (2004) for textiles.

  The pressure loss measurement and the collection efficiency measurement of the filter medium were carried out according to the air filter unit type 1 for ventilation described in JIS B9908 (1991).

  The pressure loss measurement of the filter unit was performed according to the air filter unit type 3 for ventilation described in JIS B9908 (1991).

  The dust load is based on the air filter unit type 3 for ventilation described in JIS B9908 (1991) using JIS15 type dust described in JIS Z8901 (1974) (test dust sold by Japan Powder Industry Association) It was carried out until the speed of dust passing through the filter medium was 6.5 m / min and tripled the pressure loss before dust load.

  Also, the load of 10 cigarette smoke (brand mild seven 10 mg) was introduced by introducing tobacco smoke burned with air into the wind tunnel of the evaluation device used in the JIS 15 class dust load, and the reinforcing material side of the evaluation filter medium Loaded as the upper side. At this time, the wind speed at which the tobacco smoke passed through the filter medium was 0.5 m / min.

The average fiber diameter was obtained by photographing the filter medium at a magnification of 200 times using a model VE7800 type SEM sold by Keyence Corporation, and randomly using the fiber diameter analysis software standardly installed in the SEM from the obtained image. The basis weight obtained from the fiber width of 500 fibers extracted in (1) was obtained by measuring the weight of a 50 cm square and multiplying this value by four.

  The collection efficiency is the number of particles on the upstream side of the filter medium for atmospheric dust with a particle diameter of 0.3 to 0.5 μm contained in atmospheric air using a test machine according to type 1 described in JIS B9908 (1991). Ci) and the number of particles on the downstream side of the filter medium (Co) were evaluated using a particle counter (trade name KC01D manufactured by Rion Co., Ltd.), and the collection efficiency was determined from the following formula.

Collection efficiency (%) = (1-Co / Ci) × 100%
In addition, F processing was carried out using the on-site fluorine generation system (owned by F Technical Support Center), which was jointly developed by Toyo Tanso Co., Ltd. and Takamatsu Tei Co., Ltd. with the cooperation of BNFL. did.

(Example 1)
A polypropylene ultrafine fiber nonwoven fabric (average fiber diameter 2.4 μm, basis weight 20 g / m ² ) produced by the melt blow spinning method was prepared, and F processing was performed on the nonwoven fabric under the following conditions. That is, the polypropylene ultrafine fiber nonwoven fabric was exposed for 5 minutes in a tank filled with a mixed gas (fluorine gas concentration 2%, temperature 80 ° C.) composed of fluorine gas and oxygen gas generated by electrolysis of the electrolytic solution KF · 2HF. Thereafter, the polypropylene ultrafine fiber nonwoven fabric was taken out and left in air at 25 ° C. and 75% RH for 1 hour to complete the F processing.

  The water sucking height before and after the F processing was 0 mm before the processing, but 40 mm after the F processing, and it was confirmed that the water permeability was clearly improved.

(Example 2)
Short fiber resin processed non-woven fabric (web consisting of polyester short fiber (7 dtx) and vinylon short fiber (15 dtx) in a ratio of 4 to 6 is solidified with acrylate resin to a basis weight of 50 g / m ² ) I went there. That is, the non-woven fabric processed with short fibers for 5 minutes in a tank filled with a mixed gas (fluorine gas concentration 2%, temperature 80 ° C.) composed of fluorine gas and oxygen gas generated by electrolysis of the electrolytic solution KF · 2HF. After the exposure, it was removed from the tank and left in air at 25 ° C. and 75% RH for 1 hour to complete the F processing.

  The water sucking height before and after the F processing was 1 mm before the processing, but after the F processing, it was 24 mm, and it was confirmed that the water permeability was clearly improved.

(Example 3 and Comparative Example 1)
^Two polypropylene ultrafine fiber nonwoven fabrics (average fiber diameter 2.4 μm, basis weight 20 g / m ² ) produced by the melt blow spinning method are prepared as filter material constituent materials that exhibit the collection performance, and F processing is performed on one of the nonwoven fabrics. Was performed under the following conditions. That is, the polypropylene ultrafine fiber nonwoven fabric was exposed for 5 minutes in a tank filled with a mixed gas (fluorine gas concentration 2%, temperature 80 ° C.) composed of fluorine gas and oxygen gas generated by electrolysis of the electrolytic solution KF · 2HF. Thereafter, the polypropylene ultrafine fiber nonwoven fabric was taken out and left in air at 25 ° C. and 75% RH for 1 hour to complete the F processing.

Subsequently, two polyester spunbond nonwoven fabrics (manufactured by Lutraville: product number LDH7270W, weight per unit area: 70 g / m ² ) were prepared as reinforcing materials. The polypropylene ultrafine fiber nonwoven fabric subjected to F processing and the polypropylene ultrafine fiber not subjected to F processing. Two types of filter media were prepared by laminating the nonwoven fabric with a polyester spunbond nonwoven fabric.

  For these two types of filter media, when the water suction height was evaluated, the filter media (A) in which the polypropylene ultrafine fiber nonwoven fabric and the polyester spunbond nonwoven fabric that had not been subjected to F processing were 0 mm, The filter medium (B) obtained by laminating the F-processed polypropylene ultrafine fiber nonwoven fabric and the polyester spunbond nonwoven fabric was 25 mm, and it was confirmed that the water permeability was clearly improved.

Next, three samples each having a filter medium effective area of 100 cm ² were collected from the two types of filter media (A) and (B), and the cleaning and reproducibility of each filter media was evaluated by the following procedure.

  (1) For each of the two types of filter media (A) and (B), the average pressure loss of the three test pieces was determined, and the pressure loss Δp1 of the filter media of (A) and the pressure loss Δp2 of the filter media of (B) were obtained.

  (2) Next, 10 pieces of tobacco smoke were loaded on the test pieces of the two types of filter media (A) and (B) with the reinforcing material side as the windward side.

  (3) Next, JIS 15 type dust was loaded on each of the two types of filter media (A) and (B), and adhered until the pressure loss was three times greater than Δp1 and Δp2, respectively.

  (4) After that, the filter medium on which JIS15 type dust adhered is floated with an ultrasonic cleaner (product type W113 manufactured by Honda Electronics Co., Ltd.) with tap water 2L, with the reinforcing material side facing downward, 28 MHz, 45 Megahertz and 100 megahertz ultrasonic waves were allowed to act in this order for 1 minute, then removed and dried at 100 ° C. for 5 hours.

  (5) Finally, for each of the two types of filter media (A) and (B), the pressure loss average value of the three test pieces is obtained, and the pressure loss Δp3 of the filter media in (A) and the pressure loss Δp4 of the filter media in (B) are obtained. The pressure loss change rate was determined from the value based on the following formula.

Rate of change in pressure loss of filter medium (A) (W _P ) = (Δp3 / Δp1-1) × 100%
Pressure drop change rate of the filter medium _{(B) (U P) =} (Δp4 / Δp2-1) × 100%
As a result, W _P = 20% and U _P = 4%. Apparently, it was confirmed that the dust removability was improved by the effect of F processing.

(Examples 4 and 5)
Polypropylene ultrafine fiber nonwoven fabric (average fiber diameter 2.4 μm, basis weight 20 g / m ² ) produced by the melt blow spinning method is subjected to F processing under two conditions shorter than Example 1, and these are processed into polyester spunbond nonwoven fabric ( Two types of filter media were obtained by laminating with Lutraville Corporation: product number LDH7270W, basis weight 70 g / m ² ). That is, a polypropylene ultrafine fiber nonwoven fabric with a water suction height of 4 mm and a polypropylene ultrafine fiber nonwoven fabric with a water suction height of 5 mm were prepared in the same manner as in Example 1 except that the time for exposure to the mixed gas was 30 seconds and 40 seconds. Each was prepared and laminated with a polyester spunbonded nonwoven fabric (manufactured by Lutraville: product number LDH7270W, basis weight 70 g / m ² ) to obtain two types of filter media (C) and (D).

Subsequently, the washing reproducibility of each filter medium was evaluated under the same conditions and procedures as in Example 3. As a result, _{U P} is the filter medium (C) is 7%, the filter medium (D) was 5%.

Then was evaluated for cleaning regeneration of each filter media performs dust load again just the same way to these samples, U _P is the filter medium (C) is 12%, the filter medium (D) is changed to 6%, durability It was confirmed that the filter medium (D) having a long F processing time was superior.

(Example 6)
After laminating a polypropylene spunbond nonwoven fabric (Lutraville, product number LDH7270W, weight per unit area 70 g / m ² ) on a polypropylene ultrafine fiber nonwoven fabric (average fiber diameter 2.4 μm, basis weight 20 g / m ² ) manufactured by the melt blow spinning method to obtain a filter medium F processing was performed under the conditions of Example 1. The water suction height of this filter medium was 0 mm before treatment, but was 28 mm immediately after F processing. Furthermore, when this filter medium was left in the room for half a year and the water suction height was evaluated, it was found that there was almost no decrease at 27 mm, and the sustainability of the hydrophilic effect was high.

Next, the cleaning reproducibility of the filter medium was evaluated under exactly the same conditions and procedures as in Example 3. As a result, _UP was 2.5%, which was found to be better than Example 3. It is thought that good results were obtained because the entire filter medium was made hydrophilic and the dust detachability was further improved.

Further Evaluation of the washing regeneration of the filter medium a second time dust load in the same conditions, 3% and leaving the U _P was also confirmed that the effect lasts not decrease little.

(Examples 7 and 8)
Two types of polypropylene ultrafine fiber nonwoven fabrics e and f (e: average fiber diameter 2.4 μm, basis weight 40 g / m ² , f: average fiber diameter 4.1 μm, basis weight 40 g / m ² manufactured by the melt blow spinning method and having different fiber diameters ) Was prepared. Next, each of these polypropylene ultrafine fiber nonwoven fabrics e and f is made of a short fiber resin processed nonwoven fabric (polyester short fiber (7 dtx) and vinylon short fiber (15 dtx) in a ratio of 4 to 6, and a basis weight of 50 g is set with an acrylic ester resin. / M ² ), and the laminate is subjected to F processing under the conditions of Example 1 to obtain a filter medium (E) using the polypropylene ultrafine fiber nonwoven fabric e and a filter medium using the polypropylene ultrafine fiber nonwoven fabric f (F ) The water suction height of these filter media was almost the same as 23 mm for the filter media (E) and 24 mm for the filter media (F).

Next, the cleaning reproducibility of the filter medium was evaluated under exactly the same conditions and procedures as in Example 3. As a result, _{U P} is 2.5% of the filter medium (E), _{U P} of the filter medium (F) was 1.8%. It was confirmed that the filter medium (F) using the polypropylene ultrafine fiber nonwoven fabric having a large average fiber diameter had better dust detachability.

(Example 9 and Comparative Example 2)
Two sheets of PTFE membrane (average pore size 0.2 μm, thickness 0.05 mm) are laminated as a reinforcing material polyester spunbond nonwoven fabric (Toray Industries, Inc .: product number H30601, basis weight 60 g / m ² ) to prepare two filter media One of them was subjected to F processing by the method of Example 1. When the water suction height of these two types of filter media was evaluated, the water suction height of the filter material (G) not subjected to F processing was 0 mm, and the water suction height of the filter material (H) subjected to F processing was It was 10 mm.

Next, the cleaning reproducibility of each filter medium was evaluated under exactly the same conditions and procedures as in Example 3. As a result, while the pressure drop change rate W _P of the filter medium not subjected to F processing (G) is 56%, the pressure loss change rate U _P of the filter medium which has been subjected to F machining (H) is 18%, It was found that the detachability can be greatly improved by F processing even when a PTFE membrane is used.

(Examples 10 and 11)
Two types of melt blown nonwoven fabrics having different average fiber diameters were prepared. That is, a polypropylene ultrafine fiber nonwoven fabric having an average fiber diameter of 2.4 μm (weight per unit 20 g / m ² , collection efficiency 30%) and a polypropylene ultrafine fiber nonwoven fabric having an average fiber diameter of 4.0 μm (weight per unit 50 g / m ² , collection efficiency 30%). And a polyester spunbonded non-woven fabric (manufactured by Lutraville: product number LDH7270W, basis weight 70 g / m ² ) as a reinforcing material and laminated to obtain a filter medium, followed by F processing by the method of Example 1. The water pick-up height after F processing is 25 mm for the laminated filter medium (I) of polypropylene fine fiber nonwoven fabric having an average fiber diameter of 2.4 μm and a polyester spunbond nonwoven fabric, and polypropylene fine fiber nonwoven fabric having an average fiber diameter of 4.0 μm and polyester span. The laminated filter medium (J) with the bond nonwoven fabric was 23 mm.

  Next, the electret process was performed by spraying pure water on each filter medium. The collection efficiency after processing was 93% for the filter medium (I) and 75% for the filter medium (J).

Thereafter, the cleaning reproducibility of each filter medium was evaluated under exactly the same conditions and procedures as in Example 3. As a result, _{U P} is the filter medium (I) is 4%, the filter media (J) was 2.5%. It was confirmed that electret processing is possible even with a highly hydrophilic polypropylene non-woven fabric, and that cleanability can be obtained.

(Example 12, Comparative Example 3)
Polypropylene ultrafine fiber nonwoven fabric (average fiber diameter 4.1 μm, basis weight 40 g / m ² ) produced by the melt blow spinning method and short fiber resin processed nonwoven fabric (polyester short fiber (1.5 dtx) and vinylon short fiber (15 dtx) 6 to 4 Two filter media were prepared by laminating the web blended in (1) with an acrylate resin and having a basis weight of 40 g / m ² ), and F processing was performed on one of them by the method of Example 1. The water suction height was 24 mm for the filter medium (K) subjected to F processing and 3 mm for the unprocessed filter medium (L).

  One filter unit having a width of 250 mm, a length of 320 mm, and a thickness of 30 mm was prepared for each filter medium, and the cleaning and reproducibility was evaluated. The unit creation conditions were a filter medium peak height of 28 mm and a filter medium storage area of 1.26 / piece.

  Subsequently, the cleaning reproducibility of the obtained filter unit was evaluated as follows.

(1) With respect to each of the two filter units, air was flowed at an air volume of 3.1 m ² / min, and pressure loss was measured. As a result, the pressure loss of any filter unit was 23 Pa.

  (2) Next, JIS 15 type dust was adhered until the pressure loss doubled the initial pressure loss in accordance with type 3 described in JIS B 9908 (1991).

  (3) After that, the filter unit with JIS 15 type dust adhered was immersed in a 40 L cleaning solution in which P & G's household detergent Arière was dissolved at a concentration of 2% for 1 hour, and then the water pressure of 0.2 MPa was applied to the filter unit. The dust was detached by spraying water, and then dried for 3 days in the sun.

  (5) For the filter unit after drying, the pressure loss was measured again in the same manner as in (1) above, and the rate of change in pressure loss was determined.

Pressure loss resulting filter unit pressure drop change rate W _P of the filter unit using the filter medium that has not been F machining (L) Whereas 25%, was used filter medium (K) subjected to F machining The change rate _UP was 5%, and it was confirmed that the F processing effect was clearly high even when viewed as a filter unit.

(Comparative Example 4)
Meltblown spinning polypropylene microfibrous non-woven fabric prepared in (average fiber diameter 2.4 [mu] m, basis weight 20 g / m ²⁾ polyester spunbonded nonwoven reinforcing material (Rutorabiru Co., Ltd. No. LDH7270W, basis weight 70 g / m ²⁾ was laminated, A filter medium was prepared in which octyldimethylammonium chloride (Sanyo Kasei Co., Ltd., trade name Cation DDC-50) as a surfactant was attached to 5% of the weight of the nonwoven fabric. The water suction height after processing the surfactant was 27 mm.

Subsequently, when the cleaning reproducibility was evaluated in the same manner as in Example 3, the _UP was 4%. Subsequently, when the second dust load was applied under the same conditions and the cleaning and regenerating property was evaluated, it was found that _UP was 7%, the desorbing property was deteriorated and the cleaning and regenerating capability was lowered. The cause was thought to be the disappearance of the surfactant.

(Comparative Example 5)
A filter medium obtained by laminating a polyester spunbond nonwoven fabric (manufactured by Lutraville, product number: LDH7270W, weight per unit area: 70 g / m ² ) on a polypropylene ultrafine fiber non-woven fabric (average fiber diameter: 2.4 μm, basis weight: 20 g / m ² ) manufactured by the melt blow spinning method. Next, 3% of the weight of the filter medium was attached (active ingredient after drying) with a fluororesin (Araji Glass Parajep PR New). The water suction height after processing the fluororesin was 0 mm.

  When the filter media pressure loss before and after the fluororesin processing was measured, it was 55 Pa before processing, but it was 67 Pa after processing, and clogging was promoted.

(Comparative Example 6)
A filter medium obtained by laminating a polyester spunbond nonwoven fabric (manufactured by Lutraville, product number: LDH7270W, weight per unit area: 70 g / m ² ) on a polypropylene ultrafine fiber non-woven fabric (average fiber diameter: 2.4 μm, basis weight: 20 g / m ² ) manufactured by the melt blow spinning method. In addition, plasma treatment was performed under the following conditions.

Frequency 5KHz
Application time 30 seconds Atmospheric gas Acetone-containing argon Atmospheric pressure 0.12 MPa
The water suction height immediately after processing was 13 mm. However, when the water suction height was evaluated after being left in the room for six months, it was reduced to 7 mm.

Then, when the cleaning reproducibility was evaluated in the same manner as in Example 3, the _UP was 8%. Subsequently, when the second dust load was applied under the same conditions and the cleaning and regenerating property was evaluated, it was found that _UP was 12%, the detaching property was deteriorated and the cleaning and regenerating capability was lowered.

  The cleaning / regenerating filter medium and cleaning / regenerating filter unit of the present invention can be used as a general-purpose air-conditioning to clean room high-performance filter unit, an air purifier filter, and an in-vehicle filter (liquid, air).

Claims (5)

  A washed and regenerated filter medium containing fluorine atoms and carboxyl groups in the molecular structure of the material constituting the filter medium.   The washing | cleaning reproduction | regeneration filter medium of Claim 1 whose water siphoning height measured based on the birec method of JISL1907 (2004) is 5 mm or more.   The washing | cleaning reproduction | regeneration filter medium of Claim 1 or 2 containing an electret nonwoven fabric at least.   A cleaning / regenerating filter unit using the cleaning / regenerating filter medium according to claim 1.   A method for producing a cleaning filter medium, comprising introducing fluorine atoms and carboxyl groups into a molecular structure of a material constituting the filter medium by reacting with fluorine, oxygen, and moisture.