JP3429072B2 - Filter material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter material for separating solid particles from a gas containing solid particles, and in particular, it collects and removes dust and other particles contained in high temperature exhaust gas generated from an incinerator or the like. However, the present invention relates to a filter medium which is good for taking out only purified air to the outside, has excellent mechanical strength, and is not easily damaged.

[0002]

2. Description of the Related Art Gas discharged from factory production lines, various devices, dryers, or high-temperature furnaces such as incinerators and melting furnaces contains soot and other solid particles, which causes environmental problems. It cannot be disposed outside as it is,
Only the air that has been cleaned by removing and collecting the particles by using a dust collector is taken out to the outside.

The filter material of the dust collector has a high dust collection rate and a low dust concentration in the clean gas after filtration, and also has an excellent filtering ability, and can be easily manufactured, resulting in low material cost and mechanical strength. It is desired to be excellent. As a conventional technique, for example, a filter medium described in Japanese Patent Publication No. 2-39926 has polyethylene particles having a medium molecular weight and “macromolecular polyethylene”, that is, ultra-high molecular weight polyethylene particles having a molecular weight of several million. Obtained by mixing, filling the mold and heating. In this filter medium, polyethylene particles having a medium molecular weight act as a binder to maintain the shape as a filter medium, and ultra-high molecular weight polyethylene particles penetrate between polyethylene particles having a medium molecular weight to form voids. Is fulfilling. The solid particles in the dust-containing gas cannot be passed through the fine voids formed by the ultra-high molecular weight polyethylene particles and are collected, and only air passes through these fine voids to perform filtration.

[0004]

However, in the filter medium constructed as described above, the polyethylene particles having a medium molecular weight have a large diameter of about 300 μm in order to function as a binder and have a large contact area. Therefore, it is formed in an irregular shape. On the other hand, the ultra-high molecular weight polyethylene particles are controlled to have a small diameter of about 100 to 150 μm and a spherical shape to form voids. Therefore, when these particles are mixed or transported to the mold, the particles may be filled in the mold without being sufficiently mixed due to the difference in shape.

When both particles are nonuniformly filled in a mold and sintered, a portion rich in polyethylene particles having a medium molecular weight and a portion rich in ultrahigh molecular weight polyethylene particles are contained in the filter medium. Will be mixed. Here, since the ultra high molecular weight polyethylene particles have a large molecular weight, the fluidity is extremely low. Therefore, at the sintering temperature at the time of forming the filter medium, the ultra high molecular weight polyethylene particles are not bonded to each other, and the portion rich in the ultra high molecular weight polyethylene particles becomes a defective portion in terms of strength. On the other hand, since polyethylene particles having a medium molecular weight function as a binder, they are melted at the sintering temperature and adjacent particles are easily bonded to each other. As a result, a portion rich in polyethylene particles having a medium molecular weight has no void, that is, a portion having no filtering function. Further, in order for the filtration material to have good filtration performance and mechanical strength, it is necessary that, when it is heat-sintered, the ultra-high molecular weight polyethylene particles and the polyethylene particles having a medium molecular weight have an appropriate compatibility. However, since both the particles have remarkably different melting points and fluidity, appropriate compatibility is not exhibited.

In addition to the problems caused by the difference in the shape and physical properties of the constituent particles as described above, the ultra-high molecular weight polyethylene particles have a large molecular weight of several million, and therefore do not melt even when the melting point exceeds 135 ° C. Therefore, the additive cannot be blended,
It is difficult to impart heat stability, weather resistance, antistatic property, or the like to the filtering material, or to color the filtering material. Further, ultra-high molecular weight polyethylene particles also have the drawback of being expensive.

Therefore, the present invention has been made in view of the above problems, and of course it is excellent in filtration performance.
It is an object of the present invention to provide a filter medium which is excellent in mechanical strength, can impart heat stability, weather resistance, antistatic property and the like satisfactorily and easily, and is also excellent in processability such as coloring at low cost.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide polio.
This can be achieved by a filtering material obtained by heating and sintering the reffin particles and the crosslinked polyolefin particles.

The polyolefin used in the present invention is not particularly limited, but for example, polyethylene, chlorinated polyethylene, polypropylene, polyvinyl chloride, ethylene.
Vinyl acetate copolymer and ethylene / ethyl acrylate copolymer are preferred. These polyolefins are processed into particles having an average particle size of about 300 μm.

The crosslinked polyolefin used in the present invention
The resin is not particularly limited, but cross-linked polyethylene, cross-linked chlorinated polyethylene, cross-linked polypropylene, cross-linked polyvinyl chloride, cross-linked ethylene / vinyl acetate copolymer, cross-linked ethylene / ethyl acrylate copolymer and the like are preferable. As these crosslinked polyolefins , those already crosslinked can be used, or they can be newly crosslinked and prepared. And the cross-linked polyolefin is
It is processed into particles having an average particle size of about 100 μm.

The cross-linking can be carried out by the usual cross-linking methods used for cables, pipes, etc., such as chemical cross-linking with organic peroxides, silane cross-linking with silane coupling agents, and radiation cross-linking with electron beam irradiation. If necessary, a crosslinking aid may be added to the resin. Also, cross-linked polyolefin
The fins melt above the melting point before cross-linking, so
It is possible to add various fillers by kneading, to impart heat stability, weather resistance, antistatic property, etc. to the filter material, and to add coloring by adding a pigment. On the other hand, if a cross-linked polyethylene insulated power cable that has already been cross-linked is used as the cross-linked polyolefin , waste can be reused, the cost of the product can be suppressed, and the raw material can be prepared simply by mechanical grinding. You can

[0012] filtration material according to the present invention, obtained by the polio fins <br/> and those processed with the polyolefin particles, was filled in a mold and mixed with the mixing ratio, heated sintered To be At this time, polyolefin particles and cross-linked poly
The mixing ratio of olefin particles are polyolefin particles from 20 to 70 wt%, 30 to the cross-linked polyolefin particles
When the content is 80% by weight, each performance of the filter medium can be further improved, which is preferable. In other words, the port in the filtration material
Liolefin particles serve as a binder,
On the other hand, the crosslinked polyolefin particles serve as a void forming material. Therefore, the blending ratio of polyolefin particles is 2
If it is less than 0% by weight, the mechanical strength of the filter material may be poor, and if it exceeds 70% by weight, voids may not be sufficiently formed.
It causes a problem in filtration performance. Further, a more preferable blending ratio is 30 to 60% by weight. On the other hand, cross-linked polyolefin
If the proportion of the tin particles is less than 30% by weight, the voids formed will be insufficient to cause a problem in filtering performance, and if it exceeds 80% by weight, sufficient mechanical strength as a filtering material cannot be obtained. Further, a more preferable blending ratio is 40 to 70% by weight.

The gel fraction of the crosslinked polyolefin is
It is preferably 40% or more. The air permeability required for the filter of the powder separator is empirically 1 cm ³ / cm ² ·
It is known that the gel fraction is 40 seconds or more.
If it is less than%, the air permeability cannot be achieved. Moreover, the upper limit is not particularly limited. The gel fraction is obtained by immersing the resin in an appropriate solvent to extract the uncrosslinked component, and calculating the weight ratio between the resin and the uncrosslinked component before extraction.

By the way, the molecular weight of the crosslinked polyolefin varies depending on the degree of crosslinking, and usually has a wide molecular weight distribution ranging from tens of thousands to tens of millions. Moreover, its molecular weight distribution is
Includes the molecular weight distribution of thermoplastics. Therefore, cross-linked port
Liolefin has an appropriate compatibility with the above-mentioned polyolefin , a good bond is obtained when particles made of both resins are sintered, and it is uniform and has high mechanical strength when used as a filter medium. can get. In particular, polyolefins and cross-linked polyolefins
When the fin and the fin are made of the same type of resin and are crosslinked or non-crosslinked, further excellent compatibility can be obtained.

Furthermore, polyolefins and cross-linked polyolefins
By crushing the fins by mechanical pulverization to obtain the particles having the predetermined particle diameter, both particles have an irregular shape, the mixing property of both particles is improved, and the separation of the particles can be suppressed.

[0016]

EXAMPLES The present invention can be clarified below based on Examples. Example 1 Cross-linked polyethylene particles having an average particle size of 140 μm and a gel fraction of 85% and a melt flow rate of 350 μm.
The linear low-density polyethylene particles of 5 g / 10 min were mixed for 30 minutes with a 21 V type blender while changing the mixing ratio as shown in Table 1. This mixed particle, height 3mm, width 1
It is filled in a mold having a cavity of 00 mm and a length of 150 mm, kept in an electric furnace at 160 ° C for 1 hour, and has a thickness of 3 m.
An air-permeable porous body having m, a width of 100 mm and a length of 150 mm was obtained. The air permeability of this air-permeable porous body was measured by a gas permeability tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.) according to JIS L 1004. Also, from the breathable porous body, the width 100
A strip-shaped test piece having a length of 120 mm and a length of 120 mm was cut out and the tensile strength was measured. The measurement results are shown in Table 1.

[0017]

[Table 1]

It is empirically known that the filter material of the powder separating apparatus needs to have an air permeability of at least 1 cm ³ / cm ² · sec. From the measurement results shown in Table 1, 30% by weight of crosslinked polyethylene particles is obtained. As described above, it was found that when the linear low-density polyethylene particles are 70% by weight or less, the air permeability is sufficient. Further, it is empirically known that a tensile strength of 0.2 kg / mm ² or more is required as a filter material of a powder separation device, and from the measurement results shown in Table 1, the cross-linked polyethylene particles are 80% by weight or less, It was found that the mechanical strength was sufficient when the linear low density polyethylene particles were 20% by weight or more. The gel fraction was determined by immersing the resin in xylene at 120 ° C. for 5 hours to extract the uncrosslinked component, and calculating the weight ratio of the resin and the uncrosslinked component before extraction.

Example 2 65% by weight of electron beam irradiation crosslinked ethylene / vinyl acetate copolymer (vinyl acetate content 10%) particles having an average particle diameter of 130 μm and different gel fractions as shown in Table 2, Particle size 2
Ethylene / vinyl acetate copolymer with a melt flow rate of 5.5 g / 10 min at 90 μm (vinyl acetate content 10%)
35% by weight of particles were mixed for 30 minutes in a 2 LV type blender. The gel fraction was determined by immersing the resin in xylene at 120 ° C. for 5 hours to extract the uncrosslinked component, and calculating the weight ratio of the resin and the uncrosslinked component before extraction. An air-permeable porous body was obtained from the mixed particles in the same manner as in Example 1. However, 130
It was kept in an electric furnace at ℃ for 1 hour. This breathable porous body is
The air permeability was measured by an air permeability tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.) according to IS L 1004. The measurement results are shown in Table 2.

[0020]

[Table 2]

From Table 2, when the gel fraction of the cross-linked ethylene / vinyl acetate copolymer (vinyl acetate content 10%) is 40% or more, the air permeability is 1 cm ³ required as a filter material for the powder separating apparatus. / Cm ² · sec or more was found.

Example 3 True specific gravity 0.922, average particle size 140 μm, gel fraction 85
% 50% by weight of crosslinked polyethylene particles and 50% by weight of polypropylene particles having a black true specific gravity of 0.910 and an average particle size of 330 μm kneaded and added with 1% of carbon black were mixed for 30 minutes with a 21V type blender. ,
A gray mixed particle in which both particles were mixed was obtained. Take 100 ml of this mixed particle in a 300 ml Erlenmeyer flask,
After shaking with a small shaker NW-DR type (manufactured by Miyamoto Riken Kogyo) at an amplitude of 45 mm and a shaking rate of 200 times / min for 30 minutes, the presence or absence of separation of particles was observed, but not observed. On the other hand, true specific gravity is 0.935, average particle size is 110μ
50% by weight of ultra-high molecular weight polyethylene particles of m and 1% of carbon black were kneaded and added to give a black true specific gravity of 0.90.
When 50% by weight of polypropylene particles having an average particle diameter of 330 μm and 50% by weight were mixed for 30 minutes with a 2 LV type blender, gray mixed particles in which both particles were mixed were obtained.
As a result of observing the mixed particles by shaking under the same conditions, it was found that a black layer (a layer rich in polypropylene particles) in the upper part and a white layer (a layer rich in ultra high molecular weight polyethylene particles) in the lower part were 2
It was observed that the layers were separated. Even considering the difference in specific gravity of the constituent particles of each mixed particle, the mixed particles of the crosslinked polyethylene particles and the polypropylene particles have a better mixed state than the mixed particles of the ultrahigh molecular weight polyethylene particles and the polypropylene particles. It turns out that

Example 4 3 kg of cross-linked polyethylene particles having a gel fraction of 87% recovered from the insulating layer of a used 6 KV cross-linked polyethylene insulated power cable and pulverized to an average particle size of 90 μm, and an average particle size of 3
A high-pressure method low-density polyethylene particle (3 kg) having a melt flow rate of 0.5 μm / 10 min of 10 μm was mixed for 30 minutes with a 15V type blender. The mixed particles were filled in a mold having a cylindrical cavity and held in an electric furnace at 150 ° C. for 1 hour to have a thickness of 5 mm, an outer diameter of 60 mm and an inner diameter of 50.
A cylindrical air-permeable porous body having a length of 500 mm and a length of 500 mm was obtained.
Then, as shown in FIG. 1, this cylindrical air-permeable porous body 1
A lower part of the filter was closed with a metal lid 2 to form a filter medium 3. The filtering material 3 was attached to the fixing member 12 of the top plate 11 of the powder separating apparatus 10 shown in FIG. The filtration test is conducted in accordance with JIS in the powder separating device 10 from the gas supply port 13.
A dust-containing gas containing 5 g / Nm ^{3 of} the 7th type “Kanto Loam” (median diameter 27 to 31 μm) specified by Z 8901 “test dust” is introduced, and the dust-containing gas is passed through the filter medium 3. Suction at a ventilation rate of 1 m / min, filter,
24 hours of filtered gas discharged from the gas outlet 14
Was time and measuring the dust-containing concentration after 120 hours, respectively ^{2.5mg / Nm 3, 0.5mg / Nm} 3
And 0.6 mg / Nm ³ , which proved to be useful as a filter medium.

As shown in the above results, the proper range of the mixing ratio of the polyolefin and the crosslinked polyolefin is shown in Example 1, and the optimum range of the gel fraction of the crosslinked polyolefin is shown in Example 2. found. In addition, it was confirmed from Example 3 and Example 4 that both particles were not separated during mixing, and when used as a filtering material, the filtering performance was excellent and the particles could be sufficiently used as the filtering material. on the other hand,
From the comparative example of Example 3, poor mixing properties were confirmed when ultra-high molecular weight polyethylene particles were used.

[0025]

According to the present invention, by combining polyolefin particles and crosslinked polyolefin particles,
There is no separation at the time of air transportation or mold filling of the both particles as a raw material, and it is possible to mix uniformly, and since the compatibility of the both particles at the time of heating and sintering can be appropriately obtained, the filtering material has a uniform structure. The mechanical strength of the entire filter material can be increased. Further, it becomes possible to impart heat stability, weather resistance, antistatic property, or the like to the filtering material, or to color the filtering material. Further, as a crosslinking polyolefin particles, by utilizing the recovered cross-linked polyethylene crosslinked polyethylene insulated power cables disposal, as well as to be able to reduce the material cost, preferable from the viewpoint of recycling of resources.

[Brief description of drawings]

FIG. 1 is a perspective view showing a filter medium manufactured in Example 4.

FIG. 2 is a cross-sectional view of essential parts showing a powder separation device used in Example 4.

[Explanation of symbols]

1 Breathable porous body 2 lid 3 Filter material 10 Powder separation device 11 Top plate 12 fixing members 13 Gas supply port 14 Gas outlet

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Claims (3)

(57) [Claims] 1. A polyolefin particles and the cross-linking polyolefin
A filter material, which is obtained by heating and sintering carbon particles. 2. The polyolefin particles are 20 to 70% by weight, and the crosslinked polyolefin particles are 30 to 80%.
The filtering material according to claim 1, wherein the filtering material is wt%. 3. The filter medium according to claim 1, wherein the gel fraction of the crosslinked polyolefin particles is 40% or more.