JP2009028617A - Filter nonwoven fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter nonwoven fabric which contains nano-fiber, has excellent filtering performance and good durability and is suitable for fuel-type filters. <P>SOLUTION: The filter nonwoven fabric is formed by forming a nano-fiber 2 of a fiber diameter of 50-900 nmϕ and a basis mass weight of 0.01-1.0 g/m<SP>2</SP>, by the electro-spinning method, on a substrate 1 selected from meshes, long-fiber nonwoven fabrics and short-fiber nonwoven fabrics having a binder-adhered short-fiber layer of a basis mass weight of 20-100 g/m<SP>2</SP>, laminating a nonwoven fabric 3 selected from melt-blown nonwoven fabrics or short-fiber nonwoven fabrics formed by the needle punch method on the nano-fiber-formed surface of the resultant nano-fiber-formed substrate, and integrating the substrate with the laminated nonwoven fabric by partial thermal adhesion and setting a permeability of the laminated nonwoven fabric to be 1.0-50 ccm/cm<SP>2</SP>/sec. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a filter nonwoven fabric, and more particularly to a filter nonwoven fabric for fuel used in a process of supplying fuel from a fuel tank provided mainly in an internal combustion engine or the like to a fuel injection device.

  A fuel filter is provided to filter and supply fuel to the fuel injection valve in internal combustion engines, etc., but this fuel filter does not allow foreign matters mixed in the fuel to pass through, filtration performance, flow characteristics, durability, and chemical resistance. Various characteristics are required.

  Conventionally, such a fuel filter is provided in the fuel tank and in the fuel filter device in the process in which the fuel is supplied from the fuel tank to the fuel injection valve, and the filter material used is a wire mesh, sintered metal, nylon Nets and non-woven fabrics have been commonly used. Among them, many recently use nonwoven fabric as a fuel filter material, and a filter material (for example, refer to Patent Document 1) in which a reinforcing material made of a synthetic resin and a synthetic long-fiber nonwoven fabric are joined together, and various finenesses and basis weights. A filter material (see, for example, Patent Document 2) in which a plurality of different long fiber layers are laminated as a rough layer, a middle layer, and a dense layer and integrated is proposed.

However, filter media for fuel filters, particularly gasoline filters, have been mainstream because filter paper has excellent filtration performance because of its fine fiber diameter, and has good durability. The filtration performance was low and not sufficient. On the other hand, as a synthetic paper used for the filter paper, a synthetic paper that is thinner, has a uniform basis weight, and has a high strength is required, and it is also proposed to use a synthetic paper containing nanofibers for the filter. (For example, see Patent Document 3)
JP 2003-236321 A JP 2004-218599 A JP 2005-264420 A

  However, the synthetic fiber filter material containing nanofibers has just started, and has not yet achieved a specific configuration. Furthermore, forming nanofibers not on synthetic paper but on non-woven fabrics and using them as filter materials is not in the examination stage.

  The present invention addresses the actual situation as described above, particularly focusing on filter nonwoven fabrics that utilize nanofibers, and achieves filtration performance that exceeds filter paper performance by combining nanofiber basis weight, fineness, fineness distribution, etc., as a fuel filter The object is to provide a suitable filter nonwoven fabric.

That is, the feature of the present invention that achieves the above-described object is that, in a laminated nonwoven fabric of two or more layers including a nanofiber layer, the fiber diameter of the nanofiber is 50 to 900 nmφ and the basis weight is 0.01 to 1.0 g / m ^2. A filter nonwoven fabric characterized in that the air permeability of the laminate nonwoven fabric is 1.0 to 50 cc / cm ² / sec, more specifically, a mesh having a basis weight of 20 to 100 g / m ² . A base material selected from either a long-fiber non-woven fabric or a short-fiber non-woven fabric obtained by attaching and bonding a binder to a short-fiber layer is electrospun to have a fiber diameter of 50 to 900 nmφ and a basis weight of 0.01 to 1.0 g / m. ² nanofiber layers are formed, and either the melt-bron nonwoven fabric or the nonwoven fabric obtained by the needle punch method is laminated on the nanofiber layer forming surface of the resulting nanofiber layer forming substrate and integrated by partial thermal bonding In addition, the laminated nonwoven fabric obtained is made of a filter nonwoven fabric having an air permeability of 1.0 to 50 cc / cm ² / sec.

Here, the fusion area ratio of the heat-bonded portion of the laminated nonwoven fabric in the filter nonwoven fabric is preferably 1.0 to 15%. In addition, the basis weight of the melt-blown nonwoven fabric laminated on the nanofiber layer forming substrate with the filter nonwoven fabric is 20 to 80 g / m ² , or the basis weight of the needle punched nonwoven fabric is 100 to 300 g / m ^2. Preferably, when the filter is used, the filtration inflow surface is a melt-bron nonwoven fabric or a short fiber nonwoven fabric obtained by a needle punch method, and the filtration outflow surface is either a mesh or a base fabric obtained by resin bonding to a short fiber nonwoven fabric. Is preferred.

  According to the filter nonwoven fabric of the present invention, the filtration performance is improved as compared with the conventional filter, filter paper, or filter paper containing nanofibers, and some of the filter paper containing nanofibers is nanofibers. However, these are also improved and excellent in durability and have a good effect as a fuel filter.

  Hereinafter, the specific aspect of this invention filter nonwoven fabric is explained in full detail. The filter nonwoven fabric of the present invention uses a nonwoven fabric in which nanofibers are formed on a base material selected from a mesh, a long-fiber nonwoven fabric, and a short-fiber nonwoven fabric obtained by attaching a binder to a short-fiber layer as described above. Basically, the short fiber nonwoven fabric obtained by the method is laminated and integrated by partial thermal bonding.

  Here, the base material is for holding nanofibers, and a mesh, a long fiber nonwoven fabric, or a short fiber nonwoven fabric in which a resin bond is applied to the short fiber layer is used. This is because it is important that the filtering material does not flow out to the filtering outflow surface described later, and the mesh or the long-fiber nonwoven fabric has no fiber ends and hardly generates fiber waste. On the other hand, since the short fiber nonwoven fabric has short fiber ends, it is easy to generate fiber waste. Therefore, it is necessary to securely bond the fibers, and resin bonding is essential. Adhesion between fibers using adhesive fibers is insufficient and not preferable.

This substrate preferably has a basis weight of 20 to 100 g / m ² . If the mass per unit area is less than 20 g / m ² , the amount of fibers is small, so that the substrate is thin and lacks in strength, and is easily damaged during filtration. If the mass per unit area exceeds 100 g / m ² , the amount of fibers is large, so that the pressure loss after applying nanofibers tends to be large, the filtration life is shortened, and the capacity tends to decrease, which is not preferable. Further, since the strength as a base material is sufficient, it becomes an excessive amount, which is not preferable from the viewpoint of cost.

  And this invention forms a nanofiber layer as an important structure with respect to the said base material. Nanofibers are made into ultrafine fibers down to the nano level. Examples of general production include a split fiber method, an electrospinning method, and a laser method. For example, in the case of the electrospinning method, when a polymer is dissolved in an electrolyte solution and extruded from a die, a high voltage of several thousand to several tens of thousands of volts is applied to the polymer solution to make it ultrafine. It is collected as a non-woven fabric by focusing. When this technique is used, a fine diameter of several tens of nanometers can be obtained, and the fineness of the fine diameter can be achieved. Of course, the production method for obtaining the nanofiber is not particularly limited. Nanofibers are processed into a base material, and in that case, processing into melt bron (short fibers) is also conceivable.

  The fine diameter of the nanofiber formed in the present invention is preferably in the range of 50 to 900 nmφ, and if the fine diameter is less than 50 nmφ, the fine diameter is small, the strength is weak and breakage easily occurs, and as a result, foreign matter is generated. . On the other hand, if the fine diameter exceeds 900 nmφ, it is not preferable because it becomes thick and the size formed between the fibers becomes large, and foreign matters having a small filtration particle diameter cannot be removed.

Also, the basis weight mass ranging from nano fiber formed may have a range of 0.01 to 1.0 g / m ^2, it is less than the basis weight mass 0.01 g / m ² can not hold foreign matter for a small amount of fibers Since it passes through the filter medium, sufficient filtration cannot be performed. On the other hand, when the mass per unit area exceeds 1.0 g / m ² , the amount of fibers is large, so that the pressure loss is large, the filtration life is shortened, and the ability is low, which is not preferable. Moreover, since it becomes excessive amount, it is not preferable also from a cost surface.

  In the present invention, the filtration inflow surface is a melt-bron nonwoven fabric or a short fiber nonwoven fabric obtained by a needle punch method as a filter for the nanofiber layer-forming substrate, and the filtration outflow surface is a resin adhesion of the long fiber nonwoven fabric or mesh or short fiber nonwoven fabric. In other words, the melt blown nonwoven fabric or needle punched short fiber nonwoven fabric is laminated and adhered so as to be the base material surface. As the constitution of the layer, either a melt-bron nonwoven fabric, a short fiber nonwoven fabric obtained by a needle punch method, or both nonwoven fabrics are used. This is because the filter mechanism is a coarse layer, a middle layer, and a dense layer. In addition, it is not preferable to dispose the nanofiber layer directly on the outflow side because peeling easily occurs and the filtration performance is impaired.

In addition, the nonwoven fabric on the inflow side has a role of a coarse layer, and as described above, a melt blown nonwoven fabric or a needle punched nonwoven fabric (short fiber nonwoven fabric) is used. In this case, the basis weight of the melt blown nonwoven fabric is preferably in the range of ^{20 to} 80 g / m ² . If the mass per unit area is less than 20 g / m ² , the amount of fibers is small and the role as a coarse layer is insufficient, which is not preferable. If the mass per unit area exceeds 80 g / m ² , the amount of fibers is large and the role of the coarse layer is sufficient. However, the thickness of the non-woven fabric is increased, which is not suitable for making the filter structure compact, and is excessively large, which is not preferable from the viewpoint of cost. On the other hand, the basis weight mass of needle-punched nonwoven fabric is preferably 100 to 300 g / m ^2.

  The polymer of each layer containing the nanofibers constituting the above-mentioned adhesion is not particularly limited. For example, polyacrylonitrile, polyethylene, polypropylene, polyethylene oxide, polyethylene glycol, polyethylene terephthalate, polyethylene naphthalate, poly- m-phenylene terephthalate, poly-p-phenylene isophthalate, polymethacrylic acid, polymethyl methacrylate, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropyrene copolymer, polyvinyl chloride, polyvinylidene chloride-acrylate copolymer, Polytetrafluoroethylene, polyvinyl alcohol, polyarylate, polyacetal, polycarbonate, polystyrene, polyphenylene sulfide, polyamide, polyimide, poly Midoimido, aramid, polyimide polybenzazole, polybenzimidazole, polyglycolic acid, polylactic acid, polyurethane, cellulose compounds, polypeptides, nucleosides, polynucleotides, proteins, enzymes and the like can be used. Polymer compounds other than these can also be used, and two or more kinds of polymer compounds including these polymer compounds can be mixed and used.

  FIG. 1 is a structural example showing each layer of the above laminated and bonded nonwoven fabric. The filtration inflow surface is a melt-bron nonwoven fabric or a short fiber nonwoven fabric 3 obtained by a needle punch method, and the filtration outflow surface is a long fiber nonwoven fabric or mesh or short. The substrate 1 is selected from those made of resin-bonded fiber nonwoven fabric, and a nanofiber layer 2 is formed and arranged in the middle.

  The non-woven fabric is laminated and bonded by a nonwoven fabric in which a nanofiber layer 2 is formed on a substrate 1 made of either a mesh, a long-fiber non-woven fabric, or a non-woven fabric bonded with a binder to a short fiber layer, and a melt-bron non-woven fabric or a needle punch method. It is preferable to laminate the short fiber nonwoven fabrics 3 obtained in step 1 and integrate them by partial thermal bonding. In this case, if adhesion between layers is performed with a powder resin or a binder (resin), these adhesions are not preferable because the structure in the layers is changed or adhesion between the layers becomes insufficient. In addition, as an adhesive rate of partial heat bonding, the range whose fusion | melting area ratio is 1.0 to 15% is preferable. If the fused area ratio is less than 1.0%, the amount of adhesion is small, so that the adhesion between the layers is insufficient, delamination occurs, and the workability and handleability are inferior. On the other hand, if the fused area ratio exceeds 15.0%, the amount of adhesion is large, and therefore the filtration area is reduced, the filtration life is shortened, and the ability is lowered, which is not preferable.

Thus, it is preferable that the laminated filter nonwoven fabric obtained as described above has a permeability of the laminated nonwoven fabric in the range of 1.0 to 50 cc / cm ² / sec. An air permeability of less than 1.0 cc / cm ² / sec is not preferable because the resistance of the filtrate to be passed increases, the load during filtration increases, and the trapped amount decreases. If the air permeability exceeds 50.0 cc / cm ² / sec, the flow resistance of the filtrate is low, but it is not preferable because the filtration capacity is low because fine dust in the filtrate is allowed to pass through.

  Hereinafter, specific examples of the present invention will be described together with comparative examples.

Example 1
Nylon nanofibers with a diameter of 500 nmφ and a basis weight of 0.4 g / m ² are electrolyzed on a base material made of a polyester long fiber layer with a diameter of 14.2 μm and a basis weight of 60 g / m ² made by the spunbond method. Processed by spinning method to form a laminated structure, a short fiber nonwoven fabric layer having a polyester short fiber diameter of 14.9 μm and a mass per unit area of 200 g / m ² is layered, and the spunbond layer side is ultrasonically fused to pin spacing of 4 mm. Layer bonding was performed with a 2-inch diamond pattern with an interval of 40 mm to obtain a laminated filter nonwoven fabric with a fusion area ratio of 3.7%. The air permeability of this laminated filter nonwoven fabric was 7.1 cc / cm ² / sec.
Example 2
Nylon nanofibers with a diameter of 500 nmφ and a basis weight of 0.4 g / m ² are electrolyzed on a base material made of a polyester long fiber layer with a diameter of 14.2 μm and a basis weight of 60 g / m ² made by the spunbond method. A laminated structure is processed by a spinning method, and a melt-blown nonwoven fabric having a polypropylene fiber diameter of 3.5 μm and a mass per unit area of 40 g / m ² is stacked, and ultrasonic fusion is performed from the spunbond layer side with a pin interval of 4 mm and a pin row interval of 40 mm. Layer adhesion was performed with a 2-inch diamond pattern to obtain a laminated filter nonwoven fabric with a fusion area ratio of 3.4%. The laminated filter non-woven fabric had an air permeability of 10.2 cc / cm ² / sec.
Example 3
Electrospinning of nylon nanofibers with a diameter of 500 nmφ and a basis weight of 0.4 g / m ^{2 on} a base material made of a polyester long fiber layer of 14.2 μm and a basis weight of 60 g / m ² made by the spunbond method And a laminated structure having a polypropylene fiber diameter of 3.5 μm and a fabric weight of 40 g / m ² , and a polyester short fiber fiber diameter of 14.9 μm and a weight of 200 g / m ² . A laminated filter nonwoven fabric with a fusion area ratio of 3.6% is formed by stacking short fiber layers, layering the ultrasonic bond from the spunbond layer side with a 2 inch diamond pattern with a pin spacing of 4 mm and a pin row spacing of 40 mm. Obtained. The air permeability of the multilayer filter nonwoven fabric was 9.2 cc / cm ² / sec.
Example 4
70% by weight of polyester fiber with a fineness of 2.2 decitex and 52 mm in fiber length and 30% by weight of rayon fiber with a fineness of 1.4 decitex and fiber length of 52 mm are mixed and carded, then needle punched, and then acrylic resin A short fiber nonwoven fabric was obtained by processing. Nylon nanofibers with a diameter of 320 nmφ and a mass per unit area of 0.40 g / m ² are processed by this electrospinning method into a laminated structure, and a polypropylene fiber diameter of 3.5 μm and a basis weight of 40 g / m ² of Merutoburon nonwoven superposed short fiber layer side from the ultrasonic welding pins spacing 4 mm, and the layer adhesion 2 inches diamond pattern pin row spacing 40 mm, fused area ratio of 3.5% of the laminate filter A nonwoven fabric was obtained. The air permeability of the multilayer filter nonwoven fabric was 12.2 cc / cm ² / sec.
Comparative Example 1
Electrospinning of nylon nanofibers with a diameter of 500 nmφ and a basis weight of 0.4 g / m ^{2 on} a base material made of a polyester long fiber layer of 14.2 μm and a basis weight of 60 g / m ² made by the spunbond method In order to obtain a laminated structure, a short fiber layer having a polyester short fiber diameter of 14.9 μm and a mass per unit area of 200 g / m ² is overlapped, and the pin interval is 4 mm and the pin row interval is 40 mm by ultrasonic fusion from the nanofiber side. The layers were bonded with a 2-inch diamond pattern to obtain a filter nonwoven fabric with a fusion area ratio of 3.4%. The air permeability of the laminated filter nonwoven fabric was 8.0 cc / cm ² / sec.
Comparative Example 2
A base material consisting of a polyester long fiber layer of 14.2 μm and a basis weight of 60 g / m ² made by a spunbond method is laminated with a melt bron layer having a polypropylene fiber diameter of 3.5 μm and a basis weight of 40 g / m ^2. Ultrasonic fusion was bonded from the bond layer side with a 2-inch diamond pattern having a pin interval of 4 mm and a pin row interval of 40 mm to obtain a filter nonwoven fabric having a fusion area ratio of 3.4%. The air permeability of the laminated filter nonwoven fabric was 24.0 cc / cm ² / sec.
Comparative Example 3
A filter paper composed mainly of cellulose fibers, mixed with glass fibers and polyester fibers and bonded with a phenol resin, had an average fiber diameter of 7.0 μm and a weight per unit area of 67.0 g / m ² . Further, the air permeability of this filter paper was 16.8 cc / cm ² / sec. Comparative Example 4
Electrospinning of nylon nanofibers with a diameter of 500 nmφ and a basis weight of 0.4 g / m ^{2 on} a base material made of a polyester long fiber layer of 14.2 μm and a basis weight of 60 g / m ² made by the spunbond method The laminated structure is processed into a laminate structure, and melt blown nonwoven fabrics having a polypropylene fiber diameter of 3.5 μm and a mass per unit area of 120 g / m ² are stacked, and ultrasonic fusion is performed from the spunbond layer side by 2 mm with a pin interval of 4 mm and a pin row interval of 40 mm. A layered filter nonwoven fabric having a fused area ratio of 3.4% was obtained by layer bonding with a diamond pattern. The air permeability of the multilayer filter nonwoven fabric was 0.83 cc / cm ² / sec.

The filter performances of the filter nonwoven fabrics of the Examples and Comparative Examples thus obtained were compared. The results are shown in Table 1. Each item in Table 1 was measured and evaluated according to the following procedure.
Mass per unit area; g / m ²
A size of 50 cm × 50 cm is cut out, the weight at that time is measured, and converted to a weight per 1 m ² .
Thickness: mm
A size of 15 cm × 15 cm is cut out, an initial load of 15 g / cm ² is applied, the heights of the four corners are measured, and the average value is shown.
Fine diameter; nmφ
The portion of the nonwoven fabric is enlarged to a predetermined magnification by a scanning electron microscope (S-510, manufactured by Hitachi, Ltd.), and the fiber diameters at 100 locations are calculated and shown as the average.
Apparent density; g / cc
Calculate with the basis weight and thickness.

Apparent density = (weight per unit area / thickness) g / cc
Air permeability: cc / cm ² / sec
It was measured by A method of 827.1 of JIS L1096-1999.
Ultrasonic fusion area ratio:%
The ultrasonic fusion part of a nonwoven fabric is expanded 25 times with a microscope (made by Keyence Corporation), and one fusion area (S) of ultrasonic fusion is calculated. Ten fused portions are selected at random and the average fused area (S) is obtained. Next, the number of fusions (n) existing in the area of 5 cm × 5 cm square on the nonwoven fabric surface is counted and applied to the following formula to obtain the ultrasonic fusion area ratio (Ts) (%).

Average fusion area (s) = (Σsi / 10) (cm ² )
Ultrasonic fusion area ratio (Ts) = (S × n) / (5 × 5) × 100 (%)
Evaluation of Filtration Performance Water in which dust was mixed at a constant concentration was flowed, and the difference in turbidity after filtration with respect to turbidity before filtration in which turbidity was measured with a turbidimeter was determined and evaluated by turbidity efficiency.

Turbidity efficiency (%) = (Turbidity before filtration−Turbidity after filtration) / Turbidity before filtration Evaluation condition Dust: JIS 8 type powder / JIS 11 type powder = 50/50 (% by weight)
Dust input amount: 0.25 g / 1 L (dust concentration 0.025% by weight)
Test liquid: Distilled water Test liquid volume: Continue until the specified pressure loss is reached Test liquid flow rate: 200 cc / min
Evaluation Initial filtration efficiency is evaluated by turbidity after 30 seconds (%)
The amount collected was the amount until the pressure loss reached 2.0 kPa. Durability Durability The shape retention of the filter nonwoven fabric before and after the filtration evaluation was determined.

No change without peeling between nonwoven fabrics ○
Peeling between nonwoven fabrics and nanofibers are broken ×

上記表１より、本発明によるフィルター不織布は比較フィルター不織布に比し濾過効率，捕集量ならびに耐久性の総合において優れており、燃料フィルターに使用し、頗る効果的であることが分かる。

From Table 1 above, it can be seen that the filter nonwoven fabric according to the present invention is superior to the comparative filter nonwoven fabric in terms of filtration efficiency, collected amount and durability, and is effective for use in fuel filters.

  The filter nonwoven fabric of the present invention is not limited to gasoline filters and fuel filters, and can be widely used for fluid filters.

It is a cross-sectional schematic diagram of the filter nonwoven fabric which concerns on this invention.

Explanation of symbols

1: Base material 2: Nanofiber layer 3: Melt bron nonwoven fabric or needle punched nonwoven fabric

Claims (3)

In the laminate nonwoven fabric including two or more layers including the nanofiber layer, the fiber diameter of the nanofiber is 50 to 900 nmφ, the mass per unit area is 0.01 to 1.0 g / m ² , and the air permeability of the laminate nonwoven fabric is 1. A filter nonwoven fabric characterized by being from 0 to 50 cc / cm ² / sec. ^2. The filter nonwoven fabric according to claim 1, wherein the support substrate of the nanofiber is any one of a mesh having a mass per unit area of 20 to 100 g / m ² , a long fiber nonwoven fabric, or a short fiber layer bonded to a binder. 3. The filter nonwoven fabric according to claim 1, wherein the filtration inflow surface has a mass weight of the melt blown nonwoven fabric of 20 to 80 g / m ² or a needle punch nonwoven fabric of 100 to 300 g / m ² .

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