JP2017127832A - Nonwoven fabric for filters - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonwoven fabric for filters that has sufficient conductivity even in an environment with explosive dust to be treated, and is excellent in terms of ventilation amount and rigidity.SOLUTION: A nonwoven fabric for filters is a nonwoven fabric that comprises thermoplastic continuous fibers and has a surface coverage with conductive material of 70-95%. The nonwoven fabric is partially subjected to thermocompression bonding, and the part subjected to thermocompression bonding has an average depth of 80-350 μm.SELECTED DRAWING: None

Description

  The present invention relates to a filter nonwoven fabric and a filter provided with a conductive layer composed of a conductive substance.

  Conventionally, it is generally well known to use a filter to remove dust from the air. For example, various shaped surface filters such as tube filters, cartridge filters and filter plates are utilized. The filter layer is formed from a nonwoven fabric, a fleece, and paper. In particular, recently, a nonwoven fabric excellent in rigidity is suitably used as a pleated filter.

  Among the filters, it is necessary to impart conductivity to the filter in order to remove explosive dust. When a nonwoven fabric is used as a filter, a method of imparting conductivity to the nonwoven fabric is a method in which a conductive material such as a thermoplastic elastomer or conductive carbon is previously contained in a specific amount of raw material polymer and then spun (see Patent Document 1). ) And a method of making a conductive substance exist on the surface of the nonwoven fabric (see Patent Document 2). As a method for causing the conductive material to be present on the surface of the latter nonwoven fabric, a method using mangle rolls of an epoxy resin in which conductive fine particles are uniformly dispersed has been proposed.

JP 2009-256815 A JP 2003-89969 A

  However, when spinning by adding a conductive material proposed in Patent Document 1 to a polymer, there is a problem that spinning for a long period of time deteriorates the spinnability and takes time to clean the line after spinning.

  As proposed in Patent Document 2, this problem is considered to be solved by a method in which a conductive substance is present on the surface of the nonwoven fabric as a post-processing after the production. However, the method proposed in Patent Document 2 does not propose any detailed structure and physical properties that are suitable for the nonwoven fabric to which the conductive material is applied. Since rolls are used, there is a problem that the fiber structure is crushed after application of the conductive agent, the thickness of the nonwoven fabric is reduced, and the air flow rate is significantly reduced.

  Accordingly, an object of the present invention is to solve the above-described problems of the prior art, and to provide a conductive filter nonwoven fabric excellent in conductivity and airflow retention.

  Another object of the present invention is to provide a conductive filter comprising the above-described nonwoven fabric for a filter and having excellent air permeability and strength while having conductivity.

  As a result of diligent research, the present inventors have found that in the method of applying a conductive material to the surface, the air flow rate retention of the nonwoven fabric is related to the surface structure of the nonwoven fabric, and by selecting appropriate crimping features. The present inventors have found that a filter nonwoven fabric capable of solving the above-described problems can be obtained.

  The non-woven fabric for filter of the present invention is a non-woven fabric composed of thermoplastic continuous long fibers and having a surface coverage of 70 to 95% with a conductive substance, and the non-woven fabric is partially thermocompression bonded, and the heat The nonwoven fabric for filters is characterized in that the average depth of the crimping part is 80 to 350 μm.

  According to the preferable aspect of the nonwoven fabric for filters of this invention, the air flow rate retention after the surface coating of the nonwoven fabric with the conductive material is 70% or more before the coating of the conductive material.

According to the preferable aspect of the nonwoven fabric for filters of this invention, the surface electrical resistance value of the said nonwoven fabric is 10 < ⁵ > ohm / cm or less.

  According to the preferable aspect of the nonwoven fabric for filters of this invention, the bending resistance of the said nonwoven fabric is 800 mg or more and less than 7000 mg.

According to the preferable aspect of the nonwoven fabric for filters of this invention, the coating amount of the conductive substance of the said nonwoven fabric is 1-15 g / m < ² >.

  The filter nonwoven fabric of the present invention can be preferably produced by applying a conductive material by a gravure printing method.

  The nonwoven fabric for filters of the present invention is used for filter applications.

  ADVANTAGE OF THE INVENTION According to this invention, the nonwoven fabric for filters excellent in ventilation | flow_amount keeping and intensity | strength is obtained, having uniform electroconductivity on the surface.

  The non-woven fabric for filter of the present invention is suitably used for cleaning a gas mainly containing explosive dust as a filter.

  The non-woven fabric for filter of the present invention is a non-woven fabric having a surface coverage of 70 to 95% made of conductive continuous fibers, and the non-woven fabric is partially thermocompression-bonded. This is a non-woven fabric for a filter having an average depth of 80 to 350 μm.

  The nonwoven fabric for a filter of the present invention is a nonwoven fabric in which thermoplastic continuous long fibers constituting the nonwoven fabric for a filter are partially thermocompression bonded and integrated. The area ratio of the crimped part of the partial thermocompression bonding of the nonwoven fabric for filters of the present invention is preferably 5 to 30% with respect to the total area of the nonwoven fabric.

  The area ratio of the crimping part is a ratio of the entire area of the nonwoven fabric of the thermocompression bonding part. When the area ratio of the thermocompression bonding portion is less than 5%, the strength of the nonwoven fabric cannot be sufficiently obtained, and the surface is more likely to fluff. In addition, when the area ratio of the crimped part is larger than 30%, the strength of the nonwoven fabric can be obtained, but the gap between the fibers decreases, the pressure loss increases, and the collection performance decreases. A more preferable crimp area ratio is 6 to 25%, and a most preferable crimp area area is 8 to 20%.

  The area ratio of the crimping part can be appropriately designed so that the area ratio of the crimping part is 5 to 30% depending on the combination of the area per crimping part and the density of the crimping part.

The area per pressure-bonded part of the nonwoven fabric for a filter of the present invention is preferably in the range of 1.0 to 5.0 mm ² , more preferably in the range of 1.3 to 4.0 mm ² , still more preferably. The range is 1.5 to 3.0 mm ² .

  The arrangement of these thermocompression bonding portions is not particularly defined, and those arranged at equal intervals, those arranged randomly, and different shapes can be mixed. Among these, from the viewpoint of the uniformity of the nonwoven fabric, those in which the thermocompression bonding portions are arranged at equal intervals are preferable.

The pressure-bonded portion density of the nonwoven fabric for a filter of the present invention is preferably in the range of 4.0 to 10.0 pieces / cm ² , more preferably in the range of 5.0 to 9.0 pieces / cm ² , preferably in the range of 6.0 to 8.0 pieces / cm ^2.

  By setting the area and density of the crimping part in the above ranges, a filter nonwoven fabric can be obtained that maintains filter performance and is excellent in rigidity.

  The filter nonwoven fabric of the present invention is partially thermocompression bonded. However, as a method of partially thermocompression bonding, thermocompression bonding using a hot embossing roll, or thermocompression bonding using a combination of an ultrasonic oscillator and an embossing roll. Is a preferred method. In particular, the method of thermocompression bonding with a hot embossing roll is the most preferable aspect in terms of improving the strength of the nonwoven fabric.

  Further, it is possible to perform press-contact treatment using a flat roll before or after partial thermocompression bonding. The thermocompression bonding part forms a hollow and is formed by fusing thermoplastic continuous long fibers constituting the nonwoven fabric by heat and pressure. That is, the portion where the thermoplastic continuous long fibers are fused and aggregated compared to the other portions is the thermocompression bonding portion.

  When adhesion by a hot embossing roll is adopted as a method of thermocompression bonding, a portion where the thermoplastic continuous long fibers are fused and aggregated by the convex portion of the embossing roll becomes a thermocompression bonding portion. For example, when a roll having irregularities of a predetermined pattern is used only on the upper side or the lower side and a flat roll having no irregularities is used for the other rolls, the thermocompression bonding part is a convex part of the roll having irregularities and the flat roll. The portion where the thermoplastic continuous long fibers of the nonwoven fabric are aggregated by thermocompression bonding. In addition, for example, it is composed of a pair of upper roll and lower roll having a plurality of parallel grooves arranged on the surface, and the upper roll groove and the lower roll groove intersect at a certain angle. When using the embossing roll provided to do, the thermocompression bonding part means the part where the thermoplastic continuous long fibers of the nonwoven fabric are aggregated by thermocompression bonding between the convex part of the upper roll and the convex part of the lower roll. . In this case, the portion that is press-contacted by the upper convex portion and the lower concave portion or the upper concave portion and the lower convex portion is not included in the thermocompression bonding here.

  Examples of the shape of the thermocompression bonding portion include a triangle, a rectangle, a parallelogram, a circle, an ellipse, and a rhombus.

  Among them, the upper roll is composed of a pair of upper and lower rolls in which a plurality of linear grooves arranged in parallel are formed on the surface in terms of partial thermocompression bonding without peeling the nonwoven fabric. A parallelogram that is formed by thermocompression bonding between the convex part of the upper roll and the convex part of the lower roll using an embossing roll provided so that the groove of the lower roll and the groove of the lower roll intersect at a certain angle The thermocompression bonding part is a preferred embodiment.

  It is important that the average depth of the thermocompression bonding part in the nonwoven fabric for filters of the present invention is 80 to 350 μm. When the average depth of the thermocompression bonding portion is smaller than 80 μm, the conductive material is coated on the entire surface of the nonwoven fabric without gaps, and the penetration of the conductive material in the thickness direction is large and the air flow rate retention rate is reduced. The use of more conductive material than necessary increases the cost. When the average depth of the thermocompression bonding part is larger than 350 μm, the strength of the nonwoven fabric is excellent, but since the fabric weight or thickness is more than necessary, the air flow rate of the nonwoven fabric itself is lowered, and it becomes difficult to handle as a filter application. The range of the average depth of a more preferable thermocompression bonding part is 100-300 micrometers. As a result, the surface coverage of the conductive material is equivalent to the value obtained by dividing the thermocompression bonding area ratio from the entire nonwoven fabric surface, and the conductive material does not penetrate more than necessary in the thickness direction. A nonwoven fabric for a filter having excellent rigidity while maintaining the amount can be obtained.

  It is a preferable aspect that the nonwoven fabric for filters of the present invention has a bending resistance of 800 to 7000 mg. When the bending resistance is less than 800 mg, the strength and form retention of the nonwoven fabric tend to be low, and the pleatability is lowered. On the other hand, when the bending resistance exceeds 7000 mg, it is too hard to handle.

  The more preferable bending resistance is 900 to 6500 mg, the further preferable bending resistance is 1000 to 3000 mg, and the more preferable bending resistance is 1200 to 2800 mg.

  Examples of the raw material resin for the thermoplastic continuous long fiber include polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, polyolefin such as ethylene-vinyl acetate copolymer, polycaprolactam (nylon 6), Polyhexamethylene adipamide (nylon 66), polyhexamethylene sebamide (nylon 610), polyundeca 1 lactam (nylon 11), polyamide (PA) such as polydodeca 1 lactam (nylon 12), polytetrafluoroethylene, chlorine Polyolefin (CPE) and other halogenated polyolefins, polyester polymers such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), and polyphenylene sulfide (PP ), Polyoxymethylene, polyether ether ketone (PEEK), liquid crystal polymers, polymethyl pentene, polyvinyl alcohol, polyvinylidene chloride, and thermoplastic resins such as a fluorine resin like.

  Said thermoplastic resin is used for a polymer alloy individually or in combination of 2 or more types. The most preferable thermoplastic resin is a polyester polymer that has a high melting point and is excellent in heat resistance and rigidity.

  To the above-mentioned thermoplastic continuous long fiber, a crystal nucleating agent, a matting agent, a pigment, an antifungal agent, an antibacterial agent, a flame retardant, a hydrophilic agent, and the like can be added as long as the effects of the present invention are not impaired. . In particular, during thermocompression bonding of a nonwoven fabric composed of thermoplastic continuous long fibers, metal oxides such as titanium oxide have the effect of improving the adhesiveness of the nonwoven fabric composed of thermoplastic continuous long fibers by increasing the thermal conductivity, It is preferable to add an aliphatic bisamide such as ethylenebisstearic acid amide and / or an alkyl-substituted aliphatic monoamide that has an effect of improving the releasability between the thermocompression-bonding roll and the fiber web. . These various additives can be present in the thermoplastic continuous continuous fiber, and can also be present on the surface thereof.

  In the present invention, it is a preferred embodiment that a polyester-based high-melting polymer and a polyester-based low-melting polymer are respectively melt spun to form a nonwoven fabric composed of thermoplastic continuous fibers as the mixed continuous fibers. Furthermore, it is the most preferable aspect to use a nonwoven fabric made of thermoplastic continuous long fibers as a composite continuous long fiber in which a polyester low melting point polymer is arranged around a polyester high melting point polymer.

  Here, the content ratio of the polyester-based high melting point polymer constituting the composite continuous continuous fiber is preferably 50 to 95% by mass, more preferably 70 to 90%, and still more preferably 80 to 90%. The range is 85%. If the content ratio of the polyester-based high melting point polymer exceeds 95% by mass, the strength of the thermocompression bonded nonwoven fabric becomes insufficient. On the other hand, when the content ratio of the polyester-based high melting point polymer is less than 50% by mass, fusion of the low melting point component due to thermocompression bonding increases, and the pressure loss increases.

  Furthermore, the polyester-based high melting point polymer is preferably a polymer containing polyethylene terephthalate, and more preferably a polymer containing polyethylene terephthalate as a main component. As the polyester-based low-melting polymer, a polyethylene terephthalate copolymer or polybutylene terephthalate is preferably used. Here, examples of the copolymer include a copolymer copolymerized with isophthalic acid or adipic acid. Among these, a copolymer having a copolymerization ratio of adipic acid or isophthalic acid of 5 to 20 mol% is preferably used.

  In the present invention, the melting point of the polyester high-melting polymer and the polyester low-melting polymer is preferably 230 to 290 ° C., more preferably 250 to 280 ° C. The melting point of the coalescence is preferably 200 to 260 ° C, more preferably 220 to 240 ° C, and the difference is preferably 15 ° C or more, more preferably 20 ° C or more.

  The melting point of the polymer in the present invention is measured using a differential scanning calorimeter under the condition of a heating rate of 20 ° C./min, and is a temperature that gives an extreme value in the obtained melting endothermic curve. For a polymer whose melting endotherm curve does not exhibit an extreme value in a differential scanning calorimeter, the polymer is heated on a hot plate, and the temperature at which the resin is melted by microscopic observation is defined as the melting point.

  In the present invention, a composite continuous continuous fiber in which a polyester-based low-melting polymer is arranged around a polyester-based high-melting polymer has a form in which the low-melting polymer is completely covered around the high-melting polymer, A preferred embodiment is that the low melting point polymer is partially arranged around the high melting point polymer.

  The single fiber fineness of the thermoplastic continuous long fibers constituting the nonwoven fabric for filter of the present invention is preferably in the range of 1 to 10 dtex. When the single fiber fineness of the thermoplastic continuous long fibers is less than 1 dtex, the air flow rate of the nonwoven fabric tends to be low, and further, yarn breakage tends to occur during production, which is not preferable from the viewpoint of production stability. In addition, when the single fiber fineness of the thermoplastic continuous long fiber exceeds 10 dtex, the air flow rate becomes too high to function as a filter, and the production is stable because the filament is not easily cooled during production. It is not preferable from the viewpoint of sex. A more preferable range of single fiber fineness is 1 to 8 dtex. Moreover, when multiple types of fiber are mixed, it is preferable that the single fiber fineness of each fiber is in the said range.

  Furthermore, as the cross-sectional shape of the thermoplastic continuous long fiber used in the present invention, there are a round shape, a hollow round shape, an oval shape, a flat shape, a deformed shape such as an X shape and a Y shape, a polygonal shape, and a multileaf shape. This is a preferred form. In the case of adopting cross-sections such as X-type, Y-type, etc., polygonal and multi-leaf type, etc., with composite continuous continuous fiber with polyester-type low-melting polymer arranged around the polyester-type high melting point polymer In order to facilitate thermocompression bonding of the nonwoven fabric, the polyester-based low melting point polymer component is preferably present in the vicinity of the outer peripheral portion of the fiber cross section so as to contribute to thermocompression bonding.

The basis weight of the non-woven fabric for a filter of the present invention is appropriately selected according to the filter application, but a range of 100 to 350 g / m ² is preferable. If the basis weight is less than 100 g / m ² , sufficient rigidity cannot be obtained, and if the basis weight exceeds 350 g / m ² , the basis weight is too high and the air flow rate may decrease. A more preferable range of the basis weight is 100 to 320 g / m ² , and further preferably 150 to 270 g / m ² .

  The thickness of the nonwoven fabric for filters of the present invention is preferably in the range of 0.2 to 1.5 mm. When the thickness is less than 0.2 mm, sufficient rigidity cannot be obtained, and when the thickness exceeds 1.5 mm, the thickness is too large and pleatability may be deteriorated. A more preferable thickness range is 0.3 to 1.0 mm, and further preferably 0.4 to 0.7 mm.

  As the conductive substance used in the present invention, fine particles of metal or conductive organic substance can be used. Among these, graphite or carbon black is particularly preferably used from the viewpoint of processability and cost. Specific examples of graphite or carbon black include natural graphite, artificial graphite, furnace black, acetylene black and kettin black. The conductive fine particles need to be uniformly dispersed in the non-woven fabric to be coated and coated. Therefore, it is preferable that the particles are as fine as possible. If the conductive fine particles are too fine, when dispersed in a binder, the viscosity of the dispersion becomes too high. Therefore, the particle diameter is preferably 1 to 100 μm, more preferably 15 to 50 μm.

  Since the conductive material is uniformly coated and fixed on the nonwoven fabric surface, the conductive material can be used in a state of being dispersed in the binder. Examples of the binder include epoxy resins, acrylic resins, and urethane resins. Of these, epoxy resins are preferably used in terms of water resistance and chemical resistance.

  Since the conductive substance is coated and fixed on the nonwoven fabric surface, the conductive substance is fixed on the nonwoven fabric surface in a state of being uniformly dispersed in the binder. As the binder, a synthetic resin or a natural resin can be used, but an epoxy resin is preferably used in terms of conductivity, chemical resistance and adhesiveness.

  Examples of preferable dispersions include nonionic surfactants, styrene-based and xylene-based copolymer resins, and organic solvents such as ethylene glycol.

The coating amount of the conductive material is 1 to 15 g / m ² as a solid content. When the coating amount is less than 1 g / m ² , the volume resistance value becomes large and the conductivity becomes insufficient, and it is difficult to obtain a suitable conductive non-woven fabric for a filter. On the other hand, when the coating amount exceeds 15 g / m ² , the air flow rate of the obtained conductive nonwoven fabric is remarkably lowered, and the filter life is shortened. Regarding the amount of the conductive material coated on the surface of the nonwoven fabric, the electrical resistance value of the obtained conductive filter nonwoven fabric is 10 ⁵ Ω · cm or less, and the air flow rate is maintained after the conductive material is applied to the nonwoven fabric. Since the rate is preferably 70% or more, the amount of coating (application) of the conductive material is more preferably 5 to 10 g / m ² .

  The nonwoven fabric ventilation rate retention after coating the conductive material of the present invention is preferably 70% to 100% before coating the conductive material. When the airflow retention rate is less than 70%, the pressure loss when used as a filter increases, and there is a concern about the load on the device. A more preferable ventilation rate retention is 80 to 100%.

It is preferable that the electrical resistance value of the nonwoven fabric for filters of the present invention is 10 ² to 10 ⁵ Ω · cm. When the electric resistance value exceeds 10 ⁵ Ω · cm, the electric conductivity is insufficient and it cannot be used in an environment where explosive dust is handled. A more preferable electric resistance value is 10 ³ to 10 ⁴ Ω · cm.

  Next, the manufacturing method of the nonwoven fabric for filters of this invention is demonstrated.

  As a method for producing a nonwoven fabric for a filter comprising the thermoplastic continuous long fibers of the present invention, a method such as a spunbond method or a melt blow method, or a yarn is drawn up once at a low speed, or is continuously wound up at a high speed. Any method for forming a long-fiber nonwoven fabric such as a method of collecting a nonwoven fabric on a porous collection surface while opening with a traction fluid can be employed.

  In spinning, the high-melting point polymer and the low-melting point polymer are separately melted and kneaded, and after the measurement, they are merged and discharged in the composite spinneret. As a production method, from the viewpoint of productivity, the spunbond method is preferred in which the yarn spun from the die is pulled at a high speed and is injected onto the collection net for collection.

  Here, the speed of the high-speed traction is usually set in a range of 3000 to 8000 m / min, and the spun yarn is pulled at a high speed by the ejector or the air soccer at the above speed. The refined product obtained by high-speed traction is collected on the collection net while being opened.

  The temperature of heat bonding by the hot embossing roll can be appropriately selected according to the type of resin constituting the thermoplastic continuous long fiber. The heat bonding temperature is preferably 5 to 60 ° C., more preferably 10 to 50 ° C. lower than the melting point of the polymer having the lowest melting point present on the fiber surface of the nonwoven fabric. When the temperature difference between the temperature of heat bonding by the hot embossing roll and the melting point of the polymer having the lowest melting point present on the fiber surface of the nonwoven fabric is less than 5 ° C, the heat bonding tends to be too strong, and the temperature difference is higher than 60 ° C. May cause insufficient thermal bonding.

  Since the nonwoven fabric for filters of the present invention is excellent in rigidity, it can be easily processed into a pleated shape and has excellent pleated form retention. Therefore, the filter nonwoven fabric of the present invention is preferably used as a pleated filter.

  As a method for coating the conductive material on the nonwoven fabric and applying it, any of spray coating, roll coating and blade coating can be applied. Preferably, since a conductive substance can be applied so as to follow the surface of the nonwoven fabric, a coating method by gravure printing that does not collapse the fibers constituting the nonwoven fabric and is excellent in maintaining the air flow rate is preferable.

  The nonwoven fabric composed of the continuous thermoplastic fibers obtained as described above is a nonwoven fabric composed of thermoplastic continuous fibers having a surface coverage of 70 to 95% with a conductive substance, and the nonwoven fabric is partially It is essential that the depth of the thermocompression bonding portion is 80 to 350 μm.

  Further, the filter nonwoven fabric of the present invention is used for a filter. When used as a filter, the filter nonwoven fabric improves the collection performance on at least one side of the filter nonwoven fabric of the present invention, and is excellent in the separation of collected dust. It is a preferred embodiment that the films are bonded together. The filter film to be bonded is preferably a filter film containing polytetrafluoroethylene or polyvinylidene fluoride.

  As a method of laminating a filter membrane containing polytetrafluoroethylene or a filter membrane containing polyvinylidene fluoride to a long-fiber nonwoven fabric, the filter membrane is bonded to the nonwoven fabric surface with an adhesive from the viewpoint of productivity and simplicity. A method and a method of melting the surfaces of the filter membrane or the nonwoven fabric and bonding them together are preferably used.

  The use of the non-woven fabric for filter of the present invention is not limited at all, but it is preferably used as an industrial filter because of its excellent mechanical strength and rigidity and excellent dust collection performance. Preferably, as a pleated cylindrical unit, for use in liquid filters such as bag filters such as dust collectors and electric discharge machines, and further to clean the intake air of gas turbines, automobile engines, and building air conditioners It is used for the filter for intake used. Especially, since electroconductivity is provided, the use in the environment containing explosive dust is preferable.

  Next, based on an Example, the nonwoven fabric for filters of this invention is demonstrated concretely. Each characteristic value in the following examples is measured by the following method.

(1) Melting point (° C):
The melting point was measured using a differential scanning calorimeter DSC-2 manufactured by Perkin Elma Co., Ltd. under the condition of a heating rate of 20 ° C./min. It was. Further, for a resin whose melting endotherm curve does not exhibit an extreme value in a differential scanning calorimeter, the resin was heated on a hot plate, and the temperature at which the resin was melted by microscopic observation was taken as the melting point.

(2) Intrinsic viscosity IV:
The intrinsic viscosity of the thermoplastic resin (polyester) was measured by the following method.
8 g of a sample was dissolved in 100 ml of orthochlorophenol, and a relative viscosity η _r was determined by the following equation using an Ostwald viscometer at a temperature of 25 ° C.
η _r = η / η ₀ = (t × d) / (t ₀ × d ₀ )
(Where η is the viscosity of the polymer solution, η ₀ is the viscosity of the orthochlorophenol, t is the drop time (seconds) of the solution, d is the density (g / cm ³ ) of the solution, and t ₀ is the ortho. The falling time (second) of chlorophenol, and d ₀ represent the density (g / cm ³ ) of orthochlorophenol.
Next, the intrinsic viscosity IV was calculated from the above relative viscosity η _r by the following formula.
IV = 0.0242η _r +0.2634.

(3) Measurement of the crimping part of the nonwoven fabric:
For the area per crimping part, 10 small 10mm x 10mm sample pieces were randomly collected from the nonwoven fabric, and the magnification was set so that at least one embossed pattern could be confirmed with a scanning electron microscope. 1 to 2 from each sample, select a total of 10 embossed crimped parts, calculate the area per crimped part, round off the second decimal place of the average of 10 And ask. The pressure-bonding portion density is calculated by measuring 10 points of the repeated pattern of the pressure-bonding portion, calculating the number of pressure-bonding portions per 1 cm ² , and rounding off the second decimal place of the average value. Even when the repetitive pattern is irregular, 10 points are measured, and the average value of the number of crimped parts per 1 cm ² obtained is defined as the density of the crimped parts.

(4) Surface coverage by conductive material (%):
The surface coverage by the conductive material, a conductive material was applied coated nonwoven, random Ten pieces samples were collected, the viewing 2.25 mm ² or more photos at 100x the nonwoven surface with a microscope The occupied area ratio of the conductive material was calculated from the surface image taken and projected, and the average value of the obtained values was calculated as the surface coverage (%).

(5) Average depth (μm) of thermocompression bonding part:
About the average depth of the thermocompression bonding part, 10 small piece samples are randomly collected from the non-woven fabric, the sample is thinly cut with a razor, and the portion where the thermocompression bonding portion of the non-woven fabric can be observed with a scanning electron microscope is increased 100 to 500 times. The line is connected to the vertices of the convex part (= non-thermocompression part) at both ends of the concave part (= thermocompression bonding part) on the nonwoven fabric surface, and the concave part intersection when the perpendicular line is drawn from the midpoint of the line segment Was measured at least one from each sample, and the average value of the obtained values was calculated.

(6) Single fiber fineness (decitex):
For the single fiber fineness, 10 small piece samples were randomly collected from the nonwoven fabric, photographed at 500 to 3000 times with a scanning electron microscope, 10 fibers from each sample, 100 fibers in total, arbitrarily selected, Measure its thickness. The fiber is assumed to have a circular cross section, and the thickness is the fiber diameter. The single fiber fineness is calculated from the fiber diameter calculated by rounding off the first decimal place of the average value and the density of the polymer, and the first decimal place is rounded off.

(7) Fabric weight of nonwoven fabric (g / m ² ):
The basis weight of the nonwoven fabric was obtained by taking three samples of 50 cm in the vertical direction and 50 cm in the horizontal direction, measuring the mass of each sample, converting the average value of the obtained values per unit area, and placing the first decimal place Was calculated by rounding off.

(8) Conductive substance coating amount (g / m ² ):
The conductive material application amount (g / m ² ) is determined by measuring the basis weight (7) before and after application of the conductive substance, and subtracting the basis weight before application from the basis weight after application of the conductive substance.

(9) Surface electrical resistance (Ω · cm):
The surface electrical resistance value was measured in accordance with the general test method for thermosetting plastics of JIS-K6911 (2006 edition).

(10) Bending softness (mg):
The measurement of the bending resistance was performed using a Gurley tester (Gare / flexibility tester manufactured by Toyo Seiki Seisakusyo Co., Ltd.) described in 6.10.3 (a) of JIS-L1085 (1998 edition). The bending resistance with the Gurley tester was determined by the following method. That is, test pieces having a length of L3.81 cm (effective sample length of 2.54 cm) and a width d of 2.54 cm are collected from arbitrary three points of the sample. Here, in the nonwoven fabric composed of continuous long fibers, the longitudinal direction of the nonwoven fabric is vertical and the width direction is horizontal. Each of the collected test pieces is attached to the chuck, and the chuck is fixed in accordance with the scale 1-1 / 2 ″ (1.5 inch = 3.81 cm) on the movable arm A. In this case, the sample length is ½. “(0.5 inch = 1.27 cm) is 1/4” (0.25 inch = 0.635 cm) on the chuck, and 1/4 ”(0.25 inch = 0) on the tip of the pendulum at the free end of the sample. Therefore, the effective sample length for the measurement is obtained by subtracting 1/2 ″ (0.5 inch = 1.27 cm) from the test piece length L. Next, the lower part from the fulcrum of the pendulum B When an appropriate weight W _a , W _b , and W _c (g) is attached to the weight attachment holes a, b, and c (cm), the movable arm A is rotated at a constant speed, and the test piece is separated from the pendulum B Read the scale RG, which is the first decimal place. Here, the weight attached to the weight attachment hole was set so that the scale RG would be 4 to 6. The measurement was carried out 5 times for each of the three test pieces, and 30 times in total. From the value of the obtained scale RG, the following formula:
Br = RG × (aW _a + bW _b + cW _c ) × (((L-12.7) ² ) / d) × 3.375 × 10 ⁻¹
Using, find the softness value by rounding off to the second decimal place. The bending resistance (mg) of the sample is calculated by rounding the average value of 30 measurements to the first decimal place.

Example 1
Polyethylene terephthalate (PET) having an intrinsic viscosity of 0.65 and a melting point of 260 ° C., dried to a moisture content of 50 mass ppm or less, and an intrinsic viscosity IV of 0 to 50 mass ppm or less. .66, a copolymerized polyester (CO-PET) having an isophthalic acid copolymerization ratio of 11 mol% and a melting point of 230 ° C. is melted at temperatures of 295 ° C. and 280 ° C., respectively, and using polyethylene terephthalate as a core component, A polymer polyester is used as a sheath component, a die temperature is set to 300 ° C., a core component: sheath component = 80: 20, and a filament having a circular cross-sectional shape is spun at a spinning speed of 4300 m / min by air soccer. , The filament collides with the metal collision plate installed at the air soccer exit, and the fiber is charged by triboelectric charging, opened, and moved. It was collected as a fiber web on the Ttokonbea. After the collected fiber web is heated and pressed with a flat roll on a net conveyor at a temperature of 120 ° C. and a linear pressure of 50 kg / cm, a plurality of linear grooves arranged in parallel are formed on the surface. A pair of upper rolls and lower rolls, and an embossing roll provided so that the groove of the upper roll and the groove of the lower roll intersect at a certain angle. Using an embossing roll that was thermocompression bonded with the convex portion of the roll on the side and adjusted so that the crimping area ratio was 18%, thermocompression bonding was performed at a temperature of 200 ° C. and a linear pressure of 70 kg / cm, A spunbonded nonwoven fabric having a single fiber fineness of 3 dtex, a basis weight of 200 g / m ² , an emboss average depth of 170 μm on the front side, and 220 μm on the back side was obtained.

Thereafter, “Bunny Height UCC-2” (manufactured by Nippon Graphite Industries Co., Ltd.) is diluted 7-fold with xylene, and using a gravure roll, the processing speed is 20 m / min, and the adhesion amount (solid content) is 5 g / m ^2. Was applied to a nonwoven fabric and dried in an oven at a temperature of 150 ° C. for 5 minutes to obtain a conductive nonwoven fabric having a surface coverage of 82%, a resistance value of 10 ⁴ Ω · cm, and an airflow retention of 80%. . The results are shown in Table 1.

(Example 2)
A conductive nonwoven fabric was obtained in the same manner as in Example 1 except that the basis weight was 260 g / m ^{2. The} surface coverage was 82%, the electrical resistance value was 10 ⁴ Ω · cm, and the air flow rate retention rate Of 86% of conductive nonwoven fabric was obtained. The results are shown in Table 1.

(Example 3)
A conductive nonwoven fabric was obtained by the same method as in Example 1 except that the area ratio of the crimping part was 10.4% and the basis weight was 260 g / m ^{2. The} surface coverage was 90% and the electric resistance value was 10 ^4. A conductive nonwoven fabric with Ω · cm and an airflow retention rate of 83% was obtained. The results are shown in Table 1.

  The properties of the obtained nonwoven fabric are as shown in Table 1. The nonwoven fabrics of the examples were excellent in conductivity and airflow retention, and had the rigidity necessary for pleating.

(Comparative Example 1)
The conductive nonwoven fabric was obtained by the same method as in Example 1 except that the conductive agent adhesion amount was 25 g / m ^2, and the air permeability retention rate of the obtained conductive nonwoven fabric was 43%. The results are shown in Table 1.

(Comparative Example 2)
When the nonwoven fabric was obtained by the same method as in Example 2 except that the conductive agent coating process was not performed, it was impossible to measure the resistance value of the obtained nonwoven fabric. The results are shown in Table 1.

(Comparative Example 3)
A conductive nonwoven fabric was obtained by the same method as in Example 1 except that the basis weight was 40 g / m ^{2. The} obtained conductive nonwoven fabric had a conductive agent coverage of 100% and a ventilation rate retention of 50. %, The bending resistance was 120 mg for the vertical and 80 mg for the horizontal. The results are shown in Table 1.

  The characteristics of the nonwoven fabric obtained in the comparative example are as shown in Table 1, and none of the nonwoven fabric was excellent in airflow retention and conductivity.

Claims (6)

  A nonwoven fabric composed of continuous thermoplastic fibers and having a surface coverage of 70 to 95% with a conductive material, wherein the nonwoven fabric is partially thermocompression bonded, and the average depth of the thermocompression bonding portion is 80 to 350 μm. A nonwoven fabric for filters, characterized by   The non-woven fabric for a filter according to claim 1, wherein the air permeability retention after the surface coating of the non-woven fabric with the conductive material is 70% or more before the coating with the conductive material. The non-woven fabric for a filter according to claim 1 or 2, having an electric resistance value of 10 ⁵ Ω · cm or less.   The nonwoven fabric for filters according to any one of claims 1 to 3, wherein the bending resistance is 800 mg or more and less than 7000 mg. The coating amount of the conductive material is 1 to 15 g / m ² , The filter nonwoven fabric according to claim 1.   The manufacturing method of the nonwoven fabric for filters in any one of Claims 1-5 which provides an electroconductive substance with the gravure printing method.