JPH04305213A - Adsorptive filter - Google Patents

Abstract

PURPOSE:To obtain the filter which is low in pressure drop and has the high capacity to remove malodors and dust by spraying molten fibers directly to the surface of a honeycomb adsorbent molding by a melt blow spinning method to coat the surface with these fibers and converting these fibers to electrets. CONSTITUTION:The molten fibers are directly sprayed to the surface of the honeycomb adsorbent molding 1 by the melt blow spinning method to coat 3 the surface with these fiber and the fibers are converted to the electrets. A mixture composed of >=2 kinds of polymers varying in m.p. is used for the molten fibers. A nonwoven fabric 3 of the melt blow fibers formed along the wall surfaces of the molding down to the inside of the heneycomb of the molding is made into the filter having a large filter area. The increase in driving power, noise, heat generation, etc., is prevented by this filter coupled with the low pressure drop of the thin nonwoven fabric 3 of the melt blow fibers.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a filter that has the ability to absorb bad odors.More specifically, the present invention relates to a filter that has the ability to adsorb bad odors.More specifically, it has a filter made of ultrafine fibers formed on the surface of a honeycomb-like adsorbent material, and has the functions of deodorizing and dust removal. It is something that exists.

0002

BACKGROUND OF THE INVENTION Conventionally, an electret filter made of non-woven fabric and an adsorbent (activated carbon, etc.) have been used together in air purifiers and air conditioners for the purpose of collecting dust and removing bad odors.

[0003] This is because the adsorbent itself does not have dust-collecting ability, but in this method, there is a large increase in pressure loss due to the filter, and there are many problems such as increased power of the air circulation fan, noise, and heat generation.

[0004] Conventional deodorizing and dust removing filters consist of two parts, one for deodorizing and one for removing dust, so it is inevitable that the pressure loss will be large due to the structure.If the flow rate is reduced to reduce the pressure loss, the odor removal ability will also decrease. This resulted in a decrease. For this reason, there has not been a filter that has both a high dust collection function and a large odor adsorption capacity.

[0005]

[Problem to be solved by the invention]

[0006] The odor removing and dust removing filters widely used in air purifiers and air conditioners generally have the drawbacks of large pressure loss and a large drop in adsorption capacity. Therefore, in order to improve this, we focused on a honeycomb molded body with high adsorption properties and a nonwoven fabric layer of ultrafine fibers made by melt blow spinning method, which has high dust removal ability and low pressure loss, and made use of these two materials. The purpose of the present invention is to provide a filter with low pressure loss and high odor removal and dust removal capabilities.

[0007]

[Means for Solving the Problems] The present inventors have focused on the honeycomb structure of the adsorbent, which has excellent odor removal ability and has the lowest pressure loss when circulating air, and has further added a dust removal function. We researched ways to prevent the increase in pressure loss as much as possible. As a result, it is difficult to prevent an increase in pressure loss with the method of covering a honeycomb molded body with a flat non-woven fabric, but if the inner wall of the honeycomb is covered with a non-woven fabric made of melt-blown fibers with low pressure loss, the filtration area can be increased. The present invention was achieved by discovering that the pressure loss can be dramatically increased and the pressure loss can be significantly reduced.

[0008] That is, a honeycomb adsorbent filter is obtained by directly spraying and coating the surface of a honeycomb adsorbent molded body with molten fibers using a melt blow spinning method to convert the fibers into electret.

The present invention will be explained in detail below.

The adsorbent used in the honeycomb molded body of the present invention is not particularly limited. Usually, a material having a large surface area of several hundred square meters or more per gram and exhibiting high adsorption properties, such as activated carbon, can be used in a wide range of applications. Such adsorbents also have an excellent ability to remove bad odors from the air. Among these, preferred are activated carbon, zeolite, silica gel, alumina gel, zinc hydroxide, and the like.

[0011] As the zeolite, both natural zeolite and synthetic zeolite can be used. The shape of the adsorbent may be crushed, pellet, granular, fibrous, felt, or
It can be used in any form such as woven fabric or sheet form.

The particle size of the adsorbent used in the present invention is not particularly limited. Various particles having an average particle diameter of about 0.1 μm to 1.0 mm can be used. It can be selected as appropriate depending on the purpose, but in order to maintain a high adsorption rate, the average particle size should be 0.
．． The thickness is preferably about 1 to 200 μm.

In the present invention, the plastic used as the binder is not particularly limited. A wide range of options are available. For example, thermoplastic resins include polyethylene, polypropylene, ABS (acrylonitrile butadiene styrene resin), PET (polyethylene terephthalate resin), nylon, PBT (polybutadiene terephthalate resin), ethylene acrylic resin, PM
MA (polymethyl methacrylate resin), mesophase pitch, etc. are preferred.

Further, as the thermosetting resin, furan resin,
Phenolic resins are preferred.

[0015] As the hydrophilic resin, polyvinyl alcohol resin and EVAL resin are preferable.

However, among these, those that can be heat-fused without using water or organic solvents are preferred, such as thermoplastic resins, thermosetting resins, hydrophilic resins, and conductive resins.

The particle size of the plastic powder used as a binder is not limited, but is preferably 0.5 to 50 μm.
More preferably 5 to 30 μm. When the particle size of the plastic fine powder is 0.5 μm or less, the bulk specific gravity becomes large, and it becomes difficult to mold the plastic powder with high strength and high density. Furthermore, if the particle size exceeds 50 μm, the adhesive strength will be low, making it impossible to obtain a filter with high mechanical strength.

The amount of plastic to be used is not particularly limited, but it goes without saying that as long as the mechanical properties of the molded product allow, it is preferable to use a smaller mixing ratio because the adsorbent ratio will be higher. However, in normal applications, 1 to 50 parts by weight of plastic powder is preferable, and 2 to 2 parts by weight per 100 parts by weight of adsorbent.
5 parts by weight is more preferred.

If a fibrous reinforcing material is further mixed, a molded product with even better mechanical properties can be obtained. Examples of fibrous reinforcing materials include metal, titanium, aluminum, iron,
Copper, brass, stainless steel, metal fibers, silicon carbide, boron nitride, barium titanate, glass fibers, carbon fibers, activated carbon fibers, and other inorganic fibers, or polypropylene, vinylon, polyester, nylon, polyester-polyethylene, polypropylene-polyethylene Organic fibers such as conjugated fibers can be used.

[0020] The form of the reinforcing material is not particularly limited, but the length is 0.
．． Monofilament or multifilament fibers with a diameter of 2 to 20 mm and a diameter of 3 μm to 100 μm are preferred.

[0021] The molding raw materials can be mixed using a conventional industrial mixing method such as a mixer, ribbon mixer, static mixer, ball mill, sample mill, kneader, etc. Although the plastic powder can be attached to the surface of the adsorbent by mixing, the plastic powder can be more uniformly attached to the surface of the adsorbent by stirring while heating. As the heating method, for example, microwave, infrared rays, far infrared rays, high frequency, etc. can be used. This is thought to be due to the action of static electricity generated by stirring.

The mixed molding raw materials are usually filled into a desired mold, heated to a temperature above the softening point of the binder, and then heated to a temperature of 0.1 to 1
It is compression molded under a pressure of 0 kg/cm2. A honeycomb-shaped molded body is obtained by cooling after molding. FIG. 1 shows the shapes of honeycomb molded bodies according to various embodiments of the present invention.

[Figure 1]

The resulting honeycomb molded body generally has a wall thickness of 0.
．． A cell size of 3 mm to 20 mm and a cell density of 1 to 50 are preferred for the air purifier of the present invention. Here, cell density refers to the number of cells per square inch.

[0024] A predetermined polymer is sprayed onto the honeycomb-shaped adsorbent thus obtained by a method such as a melt-blowing method, an Exxon method, a biax method, or a centrifugal overflow method, so that the wall surface of the honeycomb is covered with melt-blown fibers. It can be covered with a non-woven layer. The polymer used in this case is preferably one whose chargeability does not easily decrease after the electret treatment, such as polyvinylidene fluoride, polymethyl methacrylate,
polystyrene, polyethylene, polypropylene, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, acrylic acid, methacrylic acid, or copolymer of maleic acid and ethylene or styrene; Polyethylene terephthalate, aromatic polycarbonate, ABS (acrylonitrile, butadiene,
Styrene copolymer), PET (polyethylene terephthalate), nylon, PBT (polybutylene terephthalate), ethylene-acrylic resin, mesophase pitch, etc. can be used.

The melt-blown fiber non-woven fabric formed along the wall surface to the inside of the honeycomb of the molded body in this way becomes a filter with a large filtration area, which, combined with the low pressure loss of the thin melt-blown fiber non-woven fabric, achieves the purpose of the present invention. It is possible to prevent certain increases in power, noise, heat generation, etc. Figures 2 and 3 show a state in which a nonwoven fabric of meltblown fibers is formed as a membrane at the entrance of the honeycomb of a molded body, and a state in which a nonwoven fabric of meltblown fibers is formed along the wall surface of the honeycomb of the present invention to the inside, respectively. Shown below.

[Figure 2]

[Figure 3]

Furthermore, as a method of electret processing,
Methods for imparting homo-charged charges include the thermal electret method, which involves passing through a DC high voltage, the electroelectret method using corona discharge, the photoelectret method, which applies voltage while irradiating light, and the use of high-energy radiation such as gamma rays. A radioelectret method using irradiation or the like can be applied.

[0027] Due to the electret treatment, high static electricity is generated on the surface of the ultrafine melt-blown fibers, resulting in a structure that retains residual electrostatic polarization within the polymer on the surface of the nonwoven fabric.
Static electricity is maintained semi-permanently on the fiber surface.

[0028] At this time, if a melt-blown fiber made of a mixture of two or more polymers with different melting points is used, it is possible to perform the electret treatment under more severe conditions than in the case of a single component. The degree of deterioration of the charge over time can be considerably reduced. Incidentally, the term "two or more types of polymers" as used herein means a plurality of two or more types, but usually a mixture of two types of polymers is often used.

[0029] Particles with a diameter of 1 μm or less, such as those contained in purple cigarette smoke, cannot be removed with the melt-blown fiber coating layer alone, but if they are passed through the melt-blown fiber nonwoven fabric layer treated with electret, they can be removed. It can be easily removed.

[0030]

[Function] Since the honeycomb wall surface of the adsorptive filter of the present invention has the structure shown in FIG. 3, it has both the removal of bad odors due to the adsorption properties of the molded body and the dust removal effect due to the melt-blown fiber nonwoven fabric layer. Moreover, the honeycomb molded body has a high adsorption rate and adsorption capacity due to its structure, so it has a large odor removal ability, and the melt-blown fiber nonwoven fabric has a large filtration area because it covers the wall surface to the inside of the honeycomb.
Furthermore, since the melt-blown fiber nonwoven fabric layer is extremely thin, the pressure loss is also low.

Furthermore, particles with a diameter of 1 μm or less, such as ultrafine particles contained in purple cigarette smoke, cannot be removed with the melt-blown fiber coating alone, but the melt-blown fiber nonwoven fabric treated with electret treatment cannot remove such particles. can also be easily removed.

[0032]

EXAMPLES The present invention will be explained in more detail with reference to Examples below.

(Example 1) 100 parts by weight of activated carbon particles with a center particle diameter of 30 μm, 15 parts of polyethylene powder with a center particle diameter of 20 μm, and 2 parts of polypropylene fibers with a length of 2 mm were thoroughly mixed in a V-type blender, and a rubber mold was prepared. It was poured into a frame, heated to 120°C, and pressure-molded with 2 kg. The obtained honeycomb had a cell density of 5 and a thickness of 10 mm, and its shape is shown in Figure 1B.

[0034] This honeycomb-shaped molded body was melt-blown with a 50:50 mixture of polypropylene and polyethylene to a fiber diameter of 15 μm using a nozzle of the Biax method, and then covered with a nonwoven fabric having a basis weight of 30 g/m2 (the covering state is shown in the figure). 3). Regarding this, when the pressure loss at LV1 m/sec was measured, it was 0.12 mmaq.

The nonwoven fabric of the filter coated by the melt blow method of Example 1 was charged by corona discharge. The surface charge density of the nonwoven fabric thus obtained was 29 cgs.
It was esu/cm2.

(Comparative Example 1) The fabric weight 3 was added to the molded body prototyped in Example 1 using fibers made by spinning a 50:50 mixture of polypropylene and polyethylene to a fiber diameter of 15 μm.
The honeycomb pores were covered flat with a nonwoven fabric of 0 g/m2 (the state of the coating is shown in Fig. 2).

Regarding this, when the pressure loss at LV1/sec was measured, it was 0.23 mmaq.

(Example 2) Activated carbon 5 with a particle size of 0.1 mm
After thoroughly mixing 0 parts by weight of zeolite with a particle size of 50 μm, and 12 parts by weight of polyethylene with a particle size of 15 μm, a honeycomb body having a thickness of 10 mm and having the structure shown in FIG. 1B was molded by pressure molding. The surface of this honeycomb molded body was melt-blown with a mixed polymer of 60 parts of polymethyl methacrylate and 40 parts of polystyrene using a nozzle of the Exxon method with a fiber diameter of 12 μm, and then covered with a nonwoven fabric having a basis weight of 50 g/m (the state of the coating is shown in FIG. 3). Regarding this, LV
When the pressure loss was measured at 1 m/sec, it was 1.4 mm.
It was aq.

The nonwoven fabric of the filter coated by the melt blow method of Example 2 was heated to an acceleration voltage of 30
Irradiation treatment was carried out at KV and ion current of 10 μA for 1 minute. The surface charge density of the nonwoven fabric thus obtained was 73 cgs.
It was esu/cm2.

(Comparative Example 2) 60 parts of polymethyl methacrylate and 40 parts of polystyrene were added to the molded body prototyped in Example 2.
The honeycomb pores were flatly covered with a nonwoven fabric having a basis weight of 50 g/m2, which was made from fibers spun to a fiber diameter of 12 μm from a mixed polymer of 1.5 mm (covered state is shown in Fig. 2). Regarding this, when the pressure loss at LV1 m/sec was measured, it was 2.36 mmaq.

(Example 3) The filter obtained in Example 1 was attached to an air purifier in a room approximately 10 tatami in size, and the air purifier was started to operate while the room was filled with cigarette smoke. We investigated driving time and cigarette smoke conditions. As a result, smoke could be completely removed in 4 to 5 minutes.

For comparison, when the filter attached to the air purifier was replaced with that of Comparative Example 1, a considerable amount of cigarette smoke remained even 10 minutes after the start of operation.

[0043]

Effects of the Invention The adsorbent filter of the present invention has a high ability to remove bad odors due to the high adsorption rate and adsorption capacity due to the material and structure of the honeycomb molded body, and the melt-blown fiber nonwoven fabric is formed to cover the wall surface up to the inside of the honeycomb. The filtration area is large, and the melt-blown fiber nonwoven fabric layer is extremely thin, so the pressure loss is low.

Furthermore, particles with a diameter of 1 μm or less, such as ultrafine particles contained in purple cigarette smoke, cannot be removed by the coating layer of melt-blown fibers alone, but they can be passed through the melt-blown fiber nonwoven fabric layer that has been treated to be electret. Ba,
Such particles can also be easily removed.

[Brief explanation of the drawing]

FIG. 1 shows a sketch of several embodiments of the honeycomb of the adsorptive filter of the invention.

[Explanation of symbols]

1 Adsorbent (honeycomb wall) 2 Honeycomb hole

FIG. 2 shows a cross-sectional view of a state in which a nonwoven fabric of melt-blown fibers is formed at the entrance of honeycomb pores of an adsorptive filter.

[Explanation of symbols]

3 Melt-blown fiber nonwoven fabric layer

FIG. 3 shows a cross-sectional view of an adsorbent filter in which a nonwoven fabric of melt-blown fibers is formed along the wall surface of the honeycomb up to the inside.

Claims (2)

[Claims] 1. A honeycomb adsorbent filter obtained by directly spraying and coating the surface of a honeycomb adsorbent molded body with molten fibers using a melt blow spinning method to convert the fibers into electret. 2. The honeycomb adsorptive filter according to claim 1, wherein the molten fibers are composed of a mixture of two or more types of polymers having different melting points.