JPH0245484B2 - ROZAI - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improved material, particularly a new material for air filters that has high dust collection efficiency and a long service life. In recent years, with the spread of expressways and paved roads, the road environment has seen a decline in large-sized dust such as dust on unpaved roads, and carbon dust contained in exhaust gas emitted from automobiles has been replaced. There is a tendency for small-sized dust, which consists of soot from boilers and heavy oil boilers, to increase. Under these circumstances, laminated non-woven fabric materials that have been traditionally used for internal combustion engines, for example, have a sufficient service life against large-sized dust particles, but their service life is extremely short when used against small-sized dust particles. The drawback was that it only showed the lifespan. The reason for this is that laminated nonwoven fabric materials tend to have surface roughness in the most downstream layer, where the collection efficiency of the material is determined by the collection of small-sized dust particles, and clogging occurs with a small amount of dust. This is because the cake layer grows and the service life is reached in a relatively short period of time.Even if the composition of the material is changed to delay the occurrence of clogging, the dust-trapping effect of the material will be significantly reduced. It was hot. As a result of intensive studies to solve this problem, the inventors of the present invention have found that they have a high dust collection effect, a large amount of dust retention for both large and small particle sizes, and a long service life. The present invention was achieved by developing a long material. That is, the present invention uses 35 to 70% by weight of thin fibers having a fineness of 0.5 denier to 2 denier, and 10 to 62% by weight of thick fibers having a fineness of 3 denier or more.
and a nonwoven fabric layer consisting of a fiber blending ratio of 3 to 20% by weight of fusion fibers and having a continuous packing density gradient in the thickness direction, and 50 to 90% by weight of thick fibers having a fineness of 3 denier or more, 0.5 denier to A nonwoven fabric layer consisting of a fiber blending ratio of 0 to 20% by weight of thin fibers having a fineness of 2 denier and 10 to 40% by weight of fusion fibers and having a substantially uniform packing density in the thickness direction is mutually superposed. The present invention provides a material having the following characteristics. As mentioned above, the material of the present invention has two layers: a continuous packing density gradient nonwoven fabric layer and a uniform packing density nonwoven fabric layer. What is a continuous packing density gradient type nonwoven fabric layer? The packing density of the layer has a continuous gradient (preferably an approximately exponential continuous gradient) from high density to low density from the downstream side to the upstream side of the air in the thickness direction of the layer. This is a nonwoven fabric layer that has the entire thickness range or a part of the thickness range. This layer is formed by a suitable method, for example, by infiltrating a particulate adhesive perpendicularly to the surface of a homogeneous fiber web from one direction, depositing the particulate adhesive richly on the inflow side and sparsely on the outflow side, and then thermocompression bonding. , and then by measuring the compressive elasticity recovery of the fibers. A nonwoven fabric layer with such a structure allows dust to pass through deep layers, making it less likely to become clogged and yet exhibiting high collection efficiency. On the other hand, a uniform packing density type nonwoven fabric layer is a nonwoven fabric layer whose packing density is approximately uniform in the layer thickness direction. The present invention is characterized in that a uniform packing density nonwoven fabric layer is polymerized on top of the continuous packing density gradient nonwoven fabric layer (that is, on the upstream side). It has become possible to extend the service life, which could never be achieved with layers, and in addition, it has achieved the unprecedented effect of exhibiting a collection efficiency that is much higher than that of conventional laminated nonwoven fabric materials. It is. In the present invention, among the fibers constituting the continuous packed density gradient type nonwoven fabric layer, thin fibers with a fineness of 0.5 to 2 deniers mainly exhibit the effect of increasing the dust collection efficiency of the material, and are 3 deniers or more (preferably 3 to 2 deniers). Thick fibers with a fineness of 15 denier are necessary to recover the compressive elasticity of the fiber web in order to develop a continuous packing density gradient, and the fused fibers prevent interlayer separation of the material and maintain its shape. It is a necessary ingredient. In the present invention, the fibers constituting the uniform packing density nonwoven fabric layer are mainly thick fibers with a fineness of 3 deniers or more (preferably 3 to 15 deniers), and the reason for using such thick fibers is that this layer This is to form a nonwoven fabric layer that can maintain a low fiber packing density and retain dust through deep layer filtration with low pressure loss. Note that in order to control the fiber packing density, thin fibers of 0.5 to 2 deniers may be mixed in part. Further, the fused fibers are necessary to prevent interlayer peeling of the nonwoven fabric layer and to prevent the fibers from fuzzing. The main fibers constituting the material in the present invention are thin fibers and thick fibers as described above, but the fiber materials include synthetic fibers such as polyester, polyamide, polyacrylonitrile, polypropylene, polyvinylidene fluoride, rayon, and viscose. , semi-synthetic fibers such as acetate, inorganic fibers such as carbon, metal, glass, etc. can be used. The fused fibers used in the nonwoven fabric layer constituting the material in the present invention have a lower melting point than the main constituent fibers of the material, and can be fused with the main constituent fibers during thermocompression bonding during material production, and have a fineness of 1 denier to 6 denier. A denier range is preferred, and examples of the fiber material include copolyester polyester, copolyamide, polyethylene and the like. The fiber length of the various fibers used in the present invention is 150 mm or less, preferably 30 to 100 mm. The continuous packing density gradient type nonwoven fabric layer in the present invention is preferably formed by infiltrating a particulate adhesive perpendicularly to the surface of a uniform fiber web so as to create a distribution concentration gradient in the thickness direction, as described above, and then bonding by thermocompression. It is then manufactured by restoring the compressive elasticity of the fibers, but the important point in this case is that the particulate adhesive (preferably with an average particle size of 10 to 200 μm) is applied from the inflow side to the outflow side to form the desired shape. The two methods are to distribute the deposited amount according to a concentration gradient, preferably an approximately exponential gradient, and to select a thermocompression bonding operation that does not eliminate the compressive elastic recovery of the fibers. The amount becomes smaller as the amount of adhered particulate adhesive becomes richer and becomes larger as the amount becomes poorer, thereby creating a continuous gradient in the packing density of the fibers. The continuous packing density gradient type nonwoven fabric layer in the present invention has a maximum packing density of 0.1 to 0.2 cm ³ /cm ³ on the downstream side of air, and a minimum packing density of 0.03 to 0.1 cm ³ /cm ³ as it goes upstream. Preferably, it has a slope that approaches an exponential change. The packing density of the uniform packing density type nonwoven fabric layer in the present invention is preferably 0.02 to 0.06 cm ³ /cm ³ in order to retain dust with low pressure loss through deep layer filtration. In general, the thickness of the continuous packing density gradient type nonwoven fabric layer is 0.3 to 2 mm, the thickness of the uniform packing density type nonwoven fabric layer is 1 to 5 mm, and the thickness of the material obtained by polymerizing the two is approximately
It is 1.5 to 7 mm. The cross-sectional shapes of the fibers constituting the material of the present invention include round, triangular, star, Y-shaped, and U-shaped. In addition, the particulate adhesive used in manufacturing the above-mentioned continuous packing density gradient type nonwoven fabric layer includes thermoplastic resins such as copolymerized polyester, copolymerized nylon, and polyethylene, and thermosetting resins such as phenol, epoxy, melamine, and alkyd. Examples include resin, synthetic rubber, natural rubber, natural wax, and pine resin, and their forms include liquid particles, solid powder, etc. in the form of particles of 200 μm or less. In the material of the present invention, if desired, a porous sheet may be polymerized under the continuous packing density gradient nonwoven fabric layer in order to increase the bending rigidity of the material, for example, when the material is used to a state where a high pressure loss occurs. can. Porous sheets that can be polymerized with such materials include dry nonwoven fabrics, wet nonwoven fabrics, synthetic paper, cheesecloth, nets, and the like. As mentioned above, when using the material of the present invention, not only large particle size dust but also small particle size dust can be effectively removed over a long period of time. Note that large particle size dust such as sand smoke includes JIS Z 8901 Type 3 test dust and Type 8 test dust, which have an average particle size of 8μ. In addition, small particle size dust emitted from automobiles, heavy oil boilers, etc. includes carbon dust in light oil combustion exhaust gas that is combusted under controlled conditions, and the particle size distribution of this carbon dust is The analytical value of the number of pieces by the measuring device 218 is 5μ.
Range: 0.05-0.1%, 3μ range: 0.3-2%, 2μ
The range is 5-11%, the 1μ range is 9-22%, and the 0.5μ range is 65-86%. The present invention will be explained below using specific examples. Example 1 A uniform packing density type nonwoven fabric layer with a fiber content of 100 g/m ² consisting of 6 denier polyester fibers containing 25% of 3 denier polyethylene/polypropylene fused fibers and 5% of the same fused fibers as the fiber web (lower layer). Phenol resin was applied from the upper layer side to a web consisting of two layers, a fiber web (upper layer) for a continuous packed density gradient type nonwoven fabric layer with a fiber amount of 120 g/m ² in which the ratio of 1 denier and 6 denier polyester fibers was 1:1. 50 g of initial condensate powder per 1 m ² was dropped to infiltrate and adhere the resin powder to the upper web layer, and the web laminate was heat-treated at 130°C for 1 minute between hot plates fixed at a spacing of 1.5 mm, and then taken out. Example 1 with 2.2mm thickness
The material was obtained. As Comparative Example 1, the same two-layer web as in Example 1 was subjected to the same heat treatment as in Example 1 without adhering the initial condensate powder of phenolic resin, and 2.4
A material of Comparative Example 1 with a thickness of mm was obtained. As Comparative Example 2, a laminated nonwoven fabric material, which is a commercially available air cleaner material for internal combustion engines, was provided.
This material is made by laminating three layers of uniform fiber webs with different finenesses, immersing them in an aqueous synthetic resin emulsion solution, and then drying them.The resulting uniform packing density nonwoven fabric layer has a coarse density from the air inflow side to the air outflow side. The basis weight changes gradually from to dense density to 270g/
It is a laminated non-woven fabric material of ^m2 . For these three types of materials, the initial collection efficiency and amount of dust retained using JIS class ₈ test dust and the amount of retained dust due to carbon dust in light oil exhaust gas were determined, respectively, using a wind speed of 0.3 m/sec and an increased resistance of 300 mm H 2 O as the service life. I was equipped. Table 1 shows the results. The material of Comparative Example 1 to which no adhesive was attached had a large amount of dust retention for both types of dust, but the initial collection efficiency was quite low and was not suitable for practical use.
On the contrary, the material of Example 1, which had a nonwoven layer with a continuous packing density gradient, had a large amount of dust retained, although the initial collection efficiency was significantly high. In Comparative Example 2, which is a commercially available material, the amount of JIS class 8 dust retained was the same as that of Example 1, but the amount of carbon dust retained was extremely low, and the initial collection efficiency was also inferior to that of Example 1.

[Table] Examples 2 and 3 Fiber web for a uniform packing density nonwoven fabric layer with a fiber amount of 80 g/m ² and comprising 25% of 1.5 denier polyethylene/polypropylene fused fibers and 3 denier Y-shaped cross-sectional polyester fibers. (lower layer), and 1.5 denier polyethylene/polypropylene fused fiber; 1 denier and 10 denier polyester fiber with a fiber content of 100 g/m ² continuous packing density gradient nonwoven fabric web (upper layer). A material was prepared under the same conditions as in Example 1 by changing the fiber composition of the upper layer as shown in Table 2 and dropping 30 g of initial condensate powder of phenolic resin per 1 m ² . Comparative example 3,
I got 4, 5, 6 and 7. These materials were subjected to a dust test under the same conditions as in Example 1. Table 2 shows the results.

[Table] Comparative Example 3 contains too much 1-denier polyester fiber, so the layer thickness recovery after thermocompression bonding is small, and although the initial collection efficiency is at a high level, the amount of dust retained, especially the amount of carbon dust retained, is low. was a low value.
Comparative Examples 4 and 7 contain a larger amount of 10 denier polyester fiber and smaller amount of 1 denier polyester fiber than Comparative Example 3, so the layer thickness recovery after thermocompression bonding should be greater. Since the blended amount of fused fibers was large, the thickness recovery was small, and for this reason, the amount of dust retained was low in both cases. Comparative Example 5 had poor shape retention as a material because no fused fibers were mixed in. Comparative Example 6 had an extremely large amount of 1 denier polyester fiber, so the initial collection efficiency was not within a practical range. In contrast to these comparative examples, Examples 2 and 3, in which the fused fibers in the upper layer were within the range specified by the present invention and the blending ratio of 1 denier and 10 denier fibers were also within the range specified by the present invention, were used for initial collection. It showed excellent performance in terms of both efficiency and the amount of dust retention for JIS Class 8 test dust and carbon dust. Example 4 Fiber amount containing 8% of 1.5 denier polyethylene/polypropylene fused fibers and a 1:1 blending ratio of 1 denier and 6 denier polyester fibers
A uniform fiber web of 150g/m ² consisting of a 150g/m ² continuous packing density gradient nonwoven fabric web (upper layer), fused fibers similar to the upper layer, and 1 denier and 6 denier polyester fibers. One layer of copolymerized polyester resin powder is applied from the upper layer side to a web consisting of two layers: a fiber web for packed density type nonwoven fabric (lower layer).
The resin powder was deposited at 60 g per m ² to permeate and adhere to the upper web, and the web was heat-treated at 140° C. for 1 minute between hot plates fixed at a spacing of 2.0 mm, and then taken out.
The fiber blending ratio of the lower layer was varied as shown in Table 3.
Materials of Example 4 and Comparative Examples 8, 9 and 10 were obtained.
These materials were subjected to a dust test under the same conditions as in Example 1, and the results are shown in Table 3.

[Table] In Comparative Example 8, the amount of fused fibers in the lower layer web was not small, so the fibers had a lot of fluff, and could not be used as a material from the viewpoint of shape retention. On the other hand, in Comparative Example 9, it is thought that the fiber density of this layer became too high due to too much fused fiber, resulting in a small amount of dust retention, while in Comparative Example 10, although the amount of fused fiber was appropriate, It is thought that the initial collection efficiency was high due to the large amount of 1 denier polyester fibers, which caused clogging in the uniform packing density nonwoven fabric layer. In Example 4, the amount of fused fibers in the lower layer is 10~
40%, and since the 1 denier polyester fiber is in the blending range specified by the present invention, it exhibits excellent initial collection efficiency and performance against both JIS Class 8 test dust and carbon dust. Ta.

Claims (1)

[Claims] 1 35 to 70% by weight of thin fibers with a fineness of 0.5 to 2 denier, 10 to 62% by weight of thick fibers with a fineness of 3 or more denier, and fibers for fusing 3
A nonwoven fabric layer with a fiber blending ratio of ~20% by weight and a continuous packing density gradient in the thickness direction, and 50~90% by weight of thick fibers with a fineness of 3 denier or more and a fineness of 0.5 denier to 2 denier. A nonwoven fabric layer having a fiber blending ratio of 0 to 20% by weight of fine fibers and 10 to 40% by weight of fusion fibers and having a substantially uniform packing density in the thickness direction is superimposed on each other. material to do.