Spunbond nonwoven fabric, filter media for pleated filters of dust collectors, pleated filters of dust collectors, and high-volume pulse jet type dust collectors

Abstract

To provide a spun-bonded nonwoven fabric excellent in balance between dust collecting performance and air permeability, high in rigidity, and excellent in pleat processability, shape retention property and dust removing property, and to provide a filter medium for a dust collector pleat filter, a dust collector pleat filter, and a pulse jet type dust collector having a large amount of air capacity.SOLUTION: A spun-bonded nonwoven fabric is composed of a thermoplastic continuous filament comprising a high melting point component and a low melting point component. The nonwoven fabric is formed by partially fusing the thermoplastic continuous filament, and has fused parts in which the fibers are partially fused and non-fused parts in which the fibers are not fused, and has a weight per unit area-CV value of 5% or less. Angles R1 and R2 of curves from fused parts to non-fused parts, which are angles of surfaces different from each other, are 15° or more and they satisfy R1<R2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a spunbond nonwoven fabric used for pleated filter substrates and the like, and to a filter medium for a pleated filter of a dust collector, a pleated filter of a dust collector, and a high-volume pulse jet type dust collector, each using the nonwoven fabric. [Background technology]

[0002] Conventionally, dust collectors have been used for removing and collecting dust in working environments where dust is generated, and among them, pulse jet type dust collectors that can reduce the frequency of replacing filters are known. In this pulse jet type dust collector, the outside of the filter becomes the filtering surface, and the filter is attached to a filter gauge and operated. The pulse jet type dust collector has a mechanism that can perform backwashing by sending compressed air into the filter when the filter reaches a certain pressure. The filter is used repeatedly after dust accumulated on the outer surface of the filter is brushed off by backwashing. In addition, it is known that the filter of this pulse jet type dust collector is used in a pleated folded shape, and the pleated shape makes it possible to significantly increase the filtering area, reduce pressure loss, and improve collection performance. Therefore, the characteristics required for the nonwoven fabric used as a pleated filter are high rigidity for pleating, breathability for suppressing pressure loss, and the ability to filter dust at the surface layer and brush it off are important, and various woven and nonwoven fabrics have been proposed so far.

[0003] For example, it has been proposed to use a long-fiber nonwoven fabric that has been heat-sealed by an embossing roll as a pleated filter (see Patent Document 1).

[0004] On the other hand, as a heat-sealing method other than the embossing roll method, a so-called air-through method has been proposed in which hot air is passed through the nonwoven fabric to effect heat-sealing (see Patent Document 2).

[0005] Also proposed are a method of laminating nonwoven fabrics (see Patent Document 3) and a method of combining a nonwoven fabric with a mixed layer of ultrafine fibers (filter medium) (see Patent Document 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 3534043 [Patent Document 2] Japanese Patent Application Publication No. 7-157960 [Patent Document 3] Patent No. 4543332 [Patent Document 4] Patent No. 5918641 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the technique of heat-sealing with an embossing roll as disclosed in Patent Document 1 has the problem that dust easily accumulates in the heat-sealed portion that has no breathability, resulting in a short life. In addition, in the case of a nonwoven fabric obtained by the air-through method as disclosed in Patent Document 2, there is no heat-sealed portion as in the case of an embossing roll, and there is no problem of impairing breathability, but there is a problem that dust easily gets inside due to poor density due to the manufacturing process, and dust cannot be removed by backwashing, resulting in a short life. Furthermore, even in the techniques disclosed in Patent Documents 3 and 4, although pressure loss can be reduced, there is a problem that accumulated dust cannot be sufficiently removed, making it difficult to extend the service life.

[0008] Incidentally, in the above-mentioned pulse jet type dust collector, in places such as chemical plants where a large amount of air containing fine powder dust must be treated at 300 to 1500 L per minute, a large air volume pulse jet type dust collector is used. In order to improve the collection performance of the dust collector filter, a filter in which a porous film made of polytetrafluoroethylene (hereinafter sometimes referred to as "PTFE") and a nonwoven fabric are bonded together is also known. However, since the filter used in the large air volume pulse jet type dust collector is subjected to high air volume and repeated backwashing, a base material such as a PTFE film that may peel off is not bonded, and a spunbond nonwoven fabric alone is used as the spunbond nonwoven fabric for the filter. In addition, the spunbond nonwoven fabric for the filter used must have a rigidity that has a pleat shape retention property to withstand dust collection under a large air volume and repeated backwashing. However, conventional spunbond nonwoven fabrics for filters used for dust collection and removal have not been able to achieve both dust collection performance and breathability while also having sufficient rigidity to maintain the pleat shape and pleat processability under high airflow. In other words, if the fusion between the fibers is strengthened in an attempt to improve collection performance, the mesh size becomes smaller, leading to a decrease in breathability, while if the fusion between the fibers is loosened in an attempt to improve breathability, the mesh size becomes larger, not only decreasing dust collection performance, but also making it impossible to maintain the pleat shape under high airflow due to the decrease in rigidity, and causing fluffing, which also causes problems with appearance.

[0009] In view of the above problems, an object of the present invention is to provide a spunbond nonwoven fabric, a pleated filter for a dust collector, and a large-volume pulse jet type dust collector that achieve a balance between dust collection performance and breathability, have high rigidity that is excellent in pleat shape retention and pleat processability even under large capacity, and also have excellent dust brushing off properties. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention employs the following means. That is, the spunbonded nonwoven fabric of the present invention is made of thermoplastic continuous filaments consisting of a high melting point component and a low melting point component, has a partially fused fused part and a non-fused part that is not fused, has a basis weight CV value of 5% or less, and has angles R1 and R2 of the curves from the fused part to the non-fused part, which are different from each other, and are both 15° or more, and R1 <R2である。

[0011] In a preferred embodiment of the spunbonded nonwoven fabric of the present invention, the thermoplastic continuous filaments use polyethylene terephthalate as the high melting point component and a copolymer polyester or polybutylene terephthalate as the low melting point component.

[0012] In a preferred embodiment of the spunbonded nonwoven fabric of the present invention, the area ratio of the fused portions is in the range of 5% to 20%.

[0013] In a preferred embodiment of the spunbonded nonwoven fabric of the present invention, the thermoplastic continuous filaments have an average single fiber diameter of 12 μm or more and 26 μm or less.

[0014] The fused portion is formed by fusion bonding from both the top and bottom sides of the spunbonded nonwoven fabric.

[0015] The filter material for the pleated filter of a dust collector of the present invention is made of the above-mentioned spunbond nonwoven fabric.

[0016] The pleated filter for a dust collector of the present invention is formed by using the above-mentioned filter material for a pleated filter for a dust collector.

[0017] In a preferred embodiment of the high volume pulse jet type dust collector of the present invention, the filter material for the pleated filter of the dust collector described above is used. Effect of the Invention

[0018] According to the present invention, a spunbond nonwoven fabric is obtained which has an excellent balance between dust collection performance and air permeability, has high rigidity excellent in pleating processability and pleat shape retention property, and is also excellent in dust removal property. Therefore, the spunbond nonwoven fabric of the present invention can be suitably used as a filter medium for a pleat filter used by being bonded to a pleat filter, a PTFE film, nanofibers, or the like.

Brief Description of the Drawings

[0019] [Figure 1] FIG. 1 is a cross-sectional view of a spunbond nonwoven fabric according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic perspective view showing an example of a filter medium for a dust collector pleat filter of the present invention. [Diagram 3] FIG. 3 is a diagram for explaining the configuration of a test system for conducting a dust collection performance test according to an example of the present invention. [Figure 4] FIG. 4 is a diagram for explaining the configuration of a test system for conducting a dust removal property test according to an example of the present invention.

Embodiments for Carrying Out the Invention

[0020] The spunbond nonwoven fabric of the present invention is composed of thermoplastic continuous filaments made of a high melting point component and a low melting point component, and has a fused portion that is partially fused and a non-fused portion that is not fused. The basis weight CV value is 5% or less, and the angles of the curves from the fused portion to the non-fused portion, the angles R1 and R2 of different surfaces, are both 15° or more and R1 < R2. Hereinafter, the embodiments for carrying out the present invention will be described in detail. Note that the present invention is not limited by the following embodiments.

[0021] (Thermoplastic Continuous Filament) As the thermoplastic resin that is the raw material of the thermoplastic continuous filaments that constitute the spunbonded nonwoven fabric of the present invention, polyester is particularly preferably used. Polyester is a polymer having an acid component and an alcohol component as monomers. As the acid component, aromatic carboxylic acids such as phthalic acid (ortho form), isophthalic acid, and terephthalic acid, aliphatic dicarboxylic acids such as adipic acid and sebacic acid, and alicyclic dicarboxylic acids such as cyclohexane carboxylic acid can be used. As the alcohol component, ethylene glycol, diethylene glycol, polyethylene glycol, and the like can be used.

[0022] Examples of polyesters include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate, polylactic acid, polybutylene succinate, etc. As the polyester used as the high melting point polymer described later, PET is most preferably used because it has a high melting point, excellent heat resistance, and excellent rigidity.

[0023] Additives such as crystal nucleating agents, matting agents, pigments, mildewproofing agents, antibacterial agents, flame retardants, metal oxides, aliphatic bisamides and / or aliphatic monoamides, and hydrophilic agents can be added to these polyester raw materials within the scope of the present invention. Among them, metal oxides such as titanium oxide have the effect of improving spinnability by reducing surface friction of fibers and preventing fusion between fibers, and also of improving the fusion property of nonwoven fabrics by increasing thermal conductivity during fusion molding of nonwoven fabrics with heated rolls. In addition, aliphatic bisamides such as ethylene bisstearic acid amide and / or alkyl-substituted aliphatic monoamides have the effect of increasing the releasability between the heated roll and the nonwoven fabric web, improving transportability.

[0024] Next, the thermoplastic continuous filaments constituting the spunbonded nonwoven fabric for filters of the present invention are composed of a high melting point component and a low melting point component. In a preferred embodiment, the high melting point component is polyethylene terephthalate, and the low melting point component is copolymerized polyester or polybutylene terephthalate. In a preferred embodiment, the thermoplastic continuous filaments are composite filaments in which a polyester-based low melting point polymer, which is a low melting point component having a melting point 10°C to 140°C lower than the melting point of the polyester-based high melting point polymer, is disposed around the polyester-based high melting point polymer, which is a high melting point component. In this way, when the spunbonded nonwoven fabric is formed by fusion, the composite polyester fibers (filaments) constituting the spunbonded nonwoven fabric are firmly fused to each other, so that the spunbonded nonwoven fabric for filters has excellent mechanical strength and can fully withstand dust processing under high airflow.

[0025] In the present invention, the melting point of a thermoplastic resin is measured using a differential scanning calorimeter (for example, "DSC-2" model manufactured by PerkinElmer Japan Co., Ltd.) at a heating rate of 20°C / min and a measurement temperature range of 30°C to 300°C, and the temperature at which the obtained melting endothermic curve gives an extreme value is defined as the melting point of the thermoplastic resin. For resins whose melting endothermic curve does not show an extreme value in the differential scanning calorimeter, the resin is heated on a hot plate, and the temperature at which the resin melts under a microscope is defined as the melting point.

[0026] When the thermoplastic resin is polyester, examples of the combination of a pair of a polyester-based high melting point polymer and a polyester-based low melting point polymer (hereinafter, the order may be polyester-based high melting point polymer / polyester-based low melting point polymer) include combinations such as PET / PBT, PET / PTT, PET / polylactic acid, and PET / copolymerized PET, and among these, the combination of PET / copolymerized PET is preferably used because of its excellent spinnability. As the copolymerization component of the copolymerized PET, isophthalic acid copolymerized PET is preferably used because of its excellent spinnability.

[0027] The composite filament may have a composite form, for example, a concentric sheath-core type, an eccentric sheath-core type, or an island-in-the-sea type, among which the concentric sheath-core type is preferred because it can fuse the filaments uniformly and firmly. The cross-sectional shape of the composite filament may be a circular cross-section, a flat cross-section, a polygonal cross-section, a multi-lobal cross-section, a hollow cross-section, or the like. Among these, a preferred embodiment is one in which the filament has a circular cross-sectional shape.

[0028] Incidentally, the form of the composite filament may be, for example, a method of mixing fibers made of a polyester-based high melting point polymer with fibers made of a polyester-based low melting point polymer, but in the case of the mixing method, uniform fusion is difficult, and for example, fusion is weak in a portion where the fibers made of the polyester-based high melting point polymer are densely packed, resulting in poor mechanical strength and rigidity, and thus unsuitable for a spunbonded nonwoven fabric for a filter. On the other hand, there is also a method of applying a low melting point polymer to fibers made of a polyester-based high melting point polymer by immersion or spraying, but in either case, it is difficult to apply the low melting point polymer uniformly on the surface layer or in the thickness direction, and the mechanical strength and rigidity are poor, making the spunbonded nonwoven fabric for a filter unsuitable.

[0029] The melting point of the polyester-based low melting point polymer in the present invention is preferably 10° C. or more and 140° C. or less lower than the melting point of the polyester-based high melting point polymer. By lowering the melting point by 10° C. or more, preferably 20° C. or more, more preferably 30° C. or more, it is possible to obtain a suitable fusion property in the spunbonded nonwoven fabric. On the other hand, by lowering the melting point of the polyester-based low melting point polymer by 140° C. or less, preferably 120° C. or less, more preferably 100° C. or less than the melting point of the polyester-based high melting point polymer, it is possible to suppress a decrease in the heat resistance of the spunbonded nonwoven fabric.

[0030] The melting point of the polyester-based high melting point polymer is preferably in the range of 200° C. or more and 320° C. or less. By setting the melting point of the polyester-based high melting point polymer to preferably 200° C. or more, more preferably 210° C. or more, and even more preferably 220° C. or more, a filter having excellent heat resistance can be obtained. On the other hand, by setting the melting point of the polyester-based high melting point polymer to preferably 320° C. or less, more preferably 300° C. or less, and even more preferably 280° C. or less, a large consumption of thermal energy for melting during the production of the nonwoven fabric and a decrease in productivity can be suppressed.

[0031] The melting point of the polyester-based low melting point polymer is preferably in the range of 160° C. or more and 250° C. or less. By setting the melting point of the polyester-based low melting point polymer to preferably 160° C. or more, more preferably 170° C. or more, and even more preferably 180° C. or more, the filter has excellent shape retention even after passing through a process in which heat is applied during the production of the pleated filter, such as heat setting during pleating. On the other hand, by setting the melting point of the polyester-based low melting point polymer to preferably 250° C. or less, more preferably 240° C. or less, a filter having excellent fusion properties during the production of the nonwoven fabric and excellent mechanical strength can be obtained.

[0032] The content ratio of the polyester-based high melting point polymer to the polyester-based low melting point polymer is preferably in the range of 90:10 to 60:40 by mass ratio, and more preferably in the range of 85:15 to 70:30. By making the polyester-based high melting point polymer 60% by mass or more and 90% by mass or less, the rigidity and heat resistance of the spunbonded nonwoven fabric can be excellent. On the other hand, by making the low melting point polyester 10% by mass or more and 40% by mass or less, when the spunbonded nonwoven fabric is formed by fusion and used, the composite polyester fibers (filaments) constituting the spunbonded nonwoven fabric can be firmly fused to each other, the mechanical strength is excellent, and the fabric can sufficiently withstand dust collection under a medium air volume.

[0033] The composite form of the composite polyester fiber may be, for example, a concentric sheath-core type, an eccentric sheath-core type, or an island-in-the-sea type, among which the concentric sheath-core type is preferred because it allows the filaments to be fused uniformly and firmly. Furthermore, the cross-sectional shape of the filament (single fiber) may be a circular cross-section, a flat cross-section, a polygonal cross-section, a multi-lobal cross-section, a hollow cross-section, or the like. Among these, the filament (single fiber) preferably has a circular cross-sectional shape.

[0034] The average single fiber diameter of the thermoplastic continuous filaments constituting the spunbonded nonwoven fabric of the present invention is preferably in the range of 12 μm or more and 26 μm or less. By making the average single fiber diameter of the thermoplastic continuous filaments 12 μm or more, preferably 13 μm or more, more preferably 14 μm or more, the breathability of the spunbonded nonwoven fabric can be improved and the pressure loss can be reduced. In addition, the number of thread breaks during the formation of the thermoplastic continuous filaments can be reduced, and the stability during production can be improved. On the other hand, by making the average single fiber diameter of the thermoplastic continuous filaments 26 μm or less, preferably 25 μm or less, more preferably 24 μm or less, the uniformity of the spunbonded nonwoven fabric can be improved, the surface of the nonwoven fabric can be made dense, and the collection performance can be improved, such as making it easier to filter dust at the surface layer.

[0035] In the present invention, the average single fiber diameter (μm) of the spunbonded nonwoven fabric is determined by the following method. (i) Ten small sample pieces are randomly taken from the spunbond nonwoven fabric. (ii) The surface of the collected small sample is photographed using a scanning electron microscope or the like at a magnification range of 500 to 2000 times so that the fiber thickness can be measured. (iii) From the photographs taken from each small sample, 10 fibers are randomly selected (100 fibers in total) and their thickness is measured. Assuming that the cross section of the fiber is circular, the thickness is taken as the fiber diameter. (iv) The average single fiber diameter is calculated by rounding off the arithmetic mean value to one decimal place.

[0036] (Manufacturing method of spunbond nonwoven fabric) Next, a method for producing the spunbonded nonwoven fabric of the present invention will be described. The spunbonded nonwoven fabric of the present invention is produced by sequentially carrying out the following steps (a) to (c). (a) A process in which a thermoplastic polymer is molten and extruded from a spinneret, and then pulled and drawn by an air sucker to obtain a thermoplastic continuous filament. (b) Opening the resulting filaments and depositing them onto a moving net conveyor to form a fibrous web. (c) subjecting the resulting fibrous web to partial fusion bonding. Each of the above steps will now be described in more detail.

[0037] (a) Thermoplastic continuous filament forming process First, a thermoplastic polymer is melt-extruded from a spinneret. In particular, when a composite filament in which a polyester-based low-melting point polymer having a melting point lower than that of a polyester-based high-melting point polymer is used as a thermoplastic continuous filament, the polyester-based high-melting point polymer and the polyester-based low-melting point polymer are melted at a temperature higher than or equal to the melting point and lower than or equal to (melting point + 70°C), respectively, and a composite filament in which a polyester-based low-melting point polymer having a melting point lower than that of the polyester-based high-melting point polymer by 10°C to 140°C is disposed around the polyester-based high-melting point polymer is spun out from a fine hole by a spinneret having a temperature higher than or equal to the melting point (melting point + 70°C), and then the filament is pulled and stretched by an air sucker at a spinning speed of 4000m / min to 6000m / min to spin a filament having a circular cross-sectional shape.

[0038] (b) Fiber web forming process The spunbond nonwoven fabric of the present invention has a process in which spun thermoplastic continuous filaments are opened and sprayed, and then deposited on a moving net conveyer to obtain a fiber web. The opening method includes, for example, an electrically charged opening method or a method using a opening plate, and the method using a opening plate is particularly preferable. The use of a opening plate increases the uniformity of the nonwoven fabric and provides excellent filter performance.

[0039] Even when composite polyester fibers are used, it is important that the nonwoven fabric is a spunbonded nonwoven fabric made of the filaments (long fibers) described above. This makes it possible to increase the rigidity and mechanical strength compared to short fiber nonwoven fabrics made of discontinuous fibers, making the fabric preferable for use as a pleated filter.

[0040] In the method for producing the spunbonded nonwoven fabric of the present invention, it is also a preferred embodiment to temporarily fuse the fiber web collected on the net conveyer. The temporary fusion is preferably performed by fusing the collected fiber web with a pair of flat rolls, or by placing a flat roll on the net conveyer and fusing the web between the net conveyer and the flat roll. The fusion by the flat roll is preferably performed by placing the web in an S-shape on a calendar roll made of a flat roll. This ensures the thickness of the nonwoven fabric, and a filter with high air permeability can be obtained.

[0041] In addition, the linear pressure for temporary fusion is preferably 30 kg / cm or more and 70 kg / cm or less. By setting the linear pressure for temporary fusion to 30 kg / cm or more, more preferably 40 kg / cm or more, the strength required for pleating can be imparted to the nonwoven fabric when used as a spunbonded nonwoven fabric for filters. By setting the linear pressure for fusion to 70 kg / cm or less, more preferably 60 kg / cm or less, the thickness becomes appropriate and the breathability as a filter can be ensured.

[0042] The fusion temperature for temporary fusion is preferably 70° C. to 120° C. lower than the melting point of the polyester-based low melting point polymer. By setting the temperature in this manner, the fibers are not excessively fused to each other, and the conveyability can be improved.

[0043] (c) Partial fusion process The spunbonded nonwoven fabric for filters of the present invention is partially fused, but the method of partially fusion is not particularly limited. Here, the fused portion of the spunbonded nonwoven fabric for filters is called the fused portion, and the other unfused portion is called the nonfused portion. Fusion by a hot embossing roll or a combination of an ultrasonic oscillator and an embossing roll is preferred. In particular, fusion by a hot embossing roll is most preferred from the viewpoint of improving the strength of the nonwoven fabric. The partial fusion step is preferably processed continuously from the web forming step. By processing continuously from the web forming step, the density of the fused portion is increased, and a nonwoven fabric with excellent waist strength and excellent pleat moldability can be obtained as a spunbonded nonwoven fabric for filters. The temperature of fusion by a hot embossing roll is preferably 5°C to 60°C lower than the melting point of the polymer with the lowest melting point present on the fiber surface of the nonwoven fabric, and more preferably 10°C to 50°C lower. Excessive fusion can be prevented by setting the temperature difference between the melting points of the polymers with the lowest melting points present on the fiber surface of the nonwoven fabric by the hot embossing roll to 5° C. or more, more preferably 10° C. or more. On the other hand, uniform fusion can be achieved within the nonwoven fabric by setting the temperature difference between the melting points to 60° C. or less, more preferably 50° C. or less.

[0044] The line pressure for fusion is preferably 30 kg / cm or more and 90 kg / cm or less. By setting the line pressure for fusion to 30 kg / cm or more, more preferably 40 kg / cm or more, the strength required for pleating can be imparted to the nonwoven fabric when used as a spunbonded nonwoven fabric for filters. By setting the line pressure for fusion to 90 kg / cm or less, more preferably 80 kg / cm or less, excessive fusion can be prevented.

[0045] The ratio of the area of ​​the fused portion of the spunbonded nonwoven fabric of the present invention (hereinafter, sometimes simply referred to as the fused area ratio) refers to the ratio of the fused portion (recess) to the total area of ​​the nonwoven fabric, and is preferably in the range of 5% to 20% of the total area of ​​the nonwoven fabric. If the fused area ratio is 5% or more, more preferably 6% or more, and even more preferably 8% or more, the nonwoven fabric has sufficient mechanical strength and is not prone to fluffing on the surface. On the other hand, if the fused area ratio is 20% or less, more preferably 19.5% or less, and even more preferably 19% or less, the gaps between the fibers are reduced, so that the pressure loss does not increase and the collection performance does not decrease.

[0046] The fusion area ratio of the spunbonded nonwoven fabric is measured using a digital microscope (for example, "VHX-5000" manufactured by Keyence Corporation) and 100 rectangular frames of 1.0 cm x 1.0 cm parallel to the longitudinal and transverse directions of the nonwoven fabric are taken from any part of the spunbonded nonwoven fabric at a magnification of 20 times using the microscope. The area of ​​the fusion part within the rectangular frame is measured for each of the 100 points and the average value is calculated as a percentage and rounded off to the first decimal place to obtain the fusion area ratio (%). When not expressed as a percentage, the area (cm2) of the fusion part within the rectangular frame is used. 2 ) to the area of ​​the rectangular frame, 1.0 cm 2 Then, the fused area ratio can be calculated by rounding off to two decimal places.

[0047] The fused portion forms a depression, and is formed by fusing the thermoplastic continuous filaments constituting the nonwoven fabric together with heat and pressure. That is, the fused portion is the portion where the thermoplastic continuous filaments are fused and aggregated compared to other portions. When fusing by a thermal embossing roll is adopted as the fusing method, the portion where the thermoplastic continuous filaments are fused and aggregated by the convex portion of the embossing roll becomes the fused portion. For example, when a roll having a predetermined pattern of unevenness only on the upper or lower side is used, and the other roll is a flat roll without unevenness, the fused portion refers to the portion where the thermoplastic continuous filaments of the nonwoven fabric are fused and aggregated by the convex portion of the roll having unevenness and the flat roll. In addition, for example, when an embossing roll is used, which is composed of a pair of upper and lower rolls having a plurality of parallel linear grooves formed on the surface, and the grooves of the upper roll and the grooves of the lower roll are arranged so as to intersect at a certain angle, the fused portion refers to the portion where the thermoplastic continuous filaments of the nonwoven fabric are fused and aggregated by the convex portion of the upper roll and the convex portion of the lower roll. In this case, the portion fused between the upper convex portion and the lower concave portion or between the upper concave portion and the lower convex portion is not included in the fused portion referred to here.

[0048] The area of ​​each fused part is 0.3 mm 2 More than 5.0mm 2 Less than 0.3mm is preferred. 2 By setting the thickness to 5.0 mm or more, sufficient mechanical strength can be obtained as a spunbond nonwoven fabric for filters, and fuzzing on the surface of the nonwoven fabric can be suppressed. 2 By setting the above, the mechanical strength and breathability required for a spunbonded nonwoven fabric for filters can be maintained, and sufficient collection performance can be obtained.

[0049] The shape of the fused portion is not particularly specified, and even when a roll having a predetermined pattern of unevenness only on the upper or lower side is used and the other roll is a flat roll without unevenness, or when an embossing roll is composed of a pair of upper and lower rolls having a plurality of parallel linear grooves formed on the surface, and the grooves of the upper roll and the grooves of the lower roll are arranged so as to intersect at a certain angle, and the convex portions of the upper roll and the convex portions of the lower roll are fused, the shape of the fused portion may be a circle, a triangle, a rectangle, a parallelogram, an ellipse, a rhombus, or the like. The arrangement of these fused portions is not particularly specified, and they may be arranged regularly at equal intervals, randomly, or a mixture of different shapes. Among them, it is preferable that the fused portions are arranged at equal intervals from the viewpoint of uniformity of the nonwoven fabric. Furthermore, in terms of achieving partial fusion without peeling off the nonwoven fabric, it is preferable to use an embossing roll consisting of a pair of upper and lower rolls having a plurality of parallel linear grooves formed on the surface thereof, in which the grooves of the upper roll and the grooves of the lower roll are arranged so as to intersect at a certain angle, and to form a parallelogram-shaped fused portion formed by fusion between the convex portions of the upper roll and the convex portions of the lower roll.

[0050] (Spunbond nonwoven fabric) Next, the spunbonded nonwoven fabric of the present invention will be described. The spunbonded nonwoven fabric of the present invention is made of the above-mentioned thermoplastic continuous filaments, and has a fused part that is partially fused and a non-fused part that is not fused. Fig. 1 is a cross-sectional view of a spunbonded nonwoven fabric according to one embodiment of the present invention. The spunbonded nonwoven fabric shown in Fig. 1 is ventilated from top to bottom when in use. The spunbonded nonwoven fabric is partially fused. Specifically, the spunbonded nonwoven fabric has a fused part 101 formed by fusing the nonwoven fabric, and a non-fused part 102 that is not fused.

[0051] Furthermore, in the spunbonded nonwoven fabric of the present invention, the angles R1 and R2 on the different surfaces of the curve extending from the fused portion 101 to the non-fused portion 102 (the angles formed by the boundary surfaces of the fused portion 101 and the non-fused portion 102) are both 15° or more, and <R2である。

[0052] When the curve angles on the upper and lower sides from the fused portion to the non-fused portion thus fused are R1 and R2, both the curve angle R1 and the curve angle R2 must be 15° or more, and R1 < R2. Here, the curve angles R1 and R2 are the angles formed by the boundary surface between the fused portion and the non-fused portion on different surfaces. If either one of the curve angles R1 or R2 is 15° or less, sufficient dust expelling property cannot be obtained. Also, even if R1 = R2, sufficient dust expelling property cannot be obtained, and there is a possibility that the rigidity and strength of the non-woven fabric may decrease. In order to obtain sufficient expelling property and the rigidity and strength of the non-woven fabric, both the curve angle R1 and the curve angle R2 must be 15° or more, and the curve angle R1 < R2. More preferably, the curve angle R1 is 15° or more and 30° or less, and the curve angle R2 is 45° or more and 75° or less. Note that the curve angle R1 is the angle of the surface on the side that takes in the air before filtration, and the curve angle R2 is the angle of the surface on the side that discharges the air after filtration (after passing through the non-woven fabric). In addition, as the values of the curve angles R1 and R2 (°) of the fused portion of the spunbond non-woven fabric in the present invention from the concave portion to the convex portion, the values measured and calculated as follows shall be adopted. (i) At an arbitrary fused portion, the intersection point of the center line in the MD direction and the center line in the CD direction is defined as the center point of the fused portion. (ii) Draw a straight line parallel to the CD direction passing through the center point of the fused portion. (iii) Starting from two points on the straight line 0.5 cm away from the center point of the fused portion, draw a straight line 1.0 cm along the MD direction, and draw a straight line connecting the endpoints. (iv) Cut out the area surrounded by the 1.0 cm × 1.0 cm square formed in (i) to (iii) with a razor blade. (v) Similarly, collect a total of 100 1.0 cm × 1.0 cm measurement samples for the fused portion from arbitrary locations within the spunbond non-woven fabric. (vi) Using a scanning electron microscope (SEM) (for example, "VHX-D500" manufactured by Keyence Corporation), observe the cross-section of the fused portion in the measurement sample for the fused portion with the magnification adjusted to 100 times. (vii) Draw tangent lines from the bottom two points of adjacent fused parts (concave parts). (viii) Starting from the tangent line drawn in (vii) at the boundary between the fused portion (concave portion) and the non-fused portion (convex portion), a tangent line is drawn along the non-fused portion. (ix) The angles formed by (vii) and (viii) are measured, and the average value obtained is rounded off to one decimal place to form the angle (°) of the curve from the concave portion to the convex portion of the spunbond nonwoven fabric. (x) The above (vii) to (ix) are carried out on one side and the other side of the spunbond nonwoven fabric, and the angles obtained are R1, R2 (R1 <R2)とする。 In the present invention, the MD direction refers to the sheet conveying direction during the production of the spunbond nonwoven fabric for powder coating filters, i.e., the winding direction of the nonwoven fabric roll, and the CD direction refers to the direction perpendicular to the sheet conveying direction, i.e., the winding direction of the nonwoven fabric roll. If the spunbond nonwoven fabric is not in a rolled state due to being cut, for example, the MD direction and CD direction are determined by the following procedure. (a) Within the plane of the spunbond nonwoven fabric, select one arbitrary direction and take a test piece 38.1 mm long and 25.4 mm wide along that direction. (b) Similarly, test pieces measuring 38.1 mm in length and 25.4 mm in width are taken at angles rotated 30 degrees, 60 degrees, and 90 degrees from the direction in which the test piece was taken. (c) For each test piece in each direction, the bending resistance of each test piece is measured based on the method for measuring the bending resistance of spunbond nonwoven fabric described below. (d) The direction in which the measured value is highest is the MD direction of the spunbond nonwoven fabric, and the direction perpendicular to this is the CD direction.

[0053] The basis weight of the spunbond nonwoven fabric in the present invention is 150 to 300 g / m 2 It is preferable that the weight per unit area is in the range of 150 g / m 2 If the fabric has a basis weight of 300 g / m or more, the required rigidity of the pleats can be obtained. 2If the weight is less than this, an increase in pressure loss can be suppressed, and this is also a preferred embodiment from the viewpoint of cost. A more preferred weight range is 150 to 260 g / m 2 and more preferably 180 to 230 g / m 2 It is.

[0054] The basis weight here is calculated by taking three samples of 50cm length x 50cm width, measuring the mass of each, and calculating the average value (g) of the obtained values ​​per unit area (1m 2 ) and round off to the first decimal place.

[0055] The CV value of the spunbonded nonwoven fabric of the present invention is 5% or less. It is preferably 4.5% or less, and more preferably 4% or less, since the nonwoven fabric can be made dense with improved uniformity of the nonwoven fabric, which improves collection performance and makes it easier to obtain a satisfactory filter life. On the other hand, in order to ensure a certain amount of air permeability of the spunbonded nonwoven fabric and reduce pressure loss to extend the filter life, it is more preferable that the CV value of the CV value of the spunbonded nonwoven fabric is 1% or more. In the present invention, the basis weight CV value (%) of the spunbond nonwoven fabric is determined as follows. (i) Take 100 small pieces of 5 cm x 5 cm from the spunbond nonwoven fabric. (ii) Measure the mass (g) of each piece and calculate the unit area (1 m 2 ) per unit. (iii) The average of the conversion results of (ii) (W ave ), standard deviation (W sdv ) are calculated respectively. (iv) Based on the results of (i) to (iii), calculate the basis weight CV value (%) using the following formula, and round off to one decimal place. Weight CV value (%) = W sdv / W ave ×100

[0056] The thickness of the spunbonded nonwoven fabric in the present invention is preferably 0.50 mm or more and 0.80 mm or less, more preferably 0.51 mm or more and 0.78 mm or less. By making the thickness 0.50 mm or more, the rigidity can be improved and the nonwoven fabric can be made suitable for use as a filter. In addition, by making the thickness 0.80 mm or less, the spunbonded nonwoven fabric can be made excellent in handleability and processability as a filter.

[0057] In the present invention, the thickness (mm) of the spunbond nonwoven fabric is determined by the following method. (i) Using a thickness meter (for example, "TECLOCK" (registered trademark) SM-114 manufactured by Teclock Corporation), the thickness of the nonwoven fabric is measured at 10 equally spaced points in the CD direction. (ii) The thickness of the nonwoven fabric (mm) is determined by rounding off the above arithmetic average value to two decimal places.

[0058] The apparent density of the spunbond nonwoven fabric in the present invention is 0.25 g / cm 3 More than 0.40g / cm 3 It is preferable that the apparent density is 0.25 g / cm or less. 3 More than 0.40g / cm 3 If the apparent density is less than 0.26 g / cm, the spunbond nonwoven fabric has a dense structure, which makes it difficult for dust to get inside, and the dust can be easily removed. A more preferable apparent density range is 0.26 g / cm. 3 More than 0.38g / cm 3 The range is as follows:

[0059] In the present invention, the apparent density (g / cm 3 ) is the apparent density obtained by calculating the apparent density from the basis weight and thickness of the spunbond nonwoven fabric using the following formula, and rounding off the value to two decimal places. Apparent density (g / cm 3 )=Weight (g / m 2 ) / Thickness(mm) / 1000

[0060] The air permeability of the spunbond nonwoven fabric of the present invention is 10 (cm 3 / (cm 2 ·sec)) or more 130(cm) 3 / (cm 2 It is preferable that the ventilation rate is 10 (cm 2 sec) or less. 3 / (cm 2 sec) or more, preferably 13 (cm 3 / (cm 2 When the airflow rate is 130 (cm sec) or more, the pressure loss can be suppressed from increasing. 3 / (cm 2 ·sec) or less, preferably 105 (cm 3 / (cm 2 If the time t1 is less than 1.0 s, dust is less likely to remain inside the filter, and the filter has good collection performance.

[0061] In the present invention, the air permeability (cm 3 / (cm 2 For the air permeability (sec), the value measured based on JIS L1913:2010 "General nonwoven fabric test methods" 6.8 "Air permeability (JIS method)" 6.8.1 "Fragile method" shall be adopted as follows. (i) Ten test pieces measuring 150 mm in length and 150 mm in width are taken at equal intervals in the CD direction of the spunbond nonwoven fabric. (ii) After attaching a test specimen to one end of the cylinder of the testing machine, adjust the suction fan and air hole so that the inclined barometer indicates a pressure of 125 Pa using the lower limit resistor, and measure the pressure indicated by the vertical barometer at that time. (iii) From the measured pressure and the type of air hole used, calculate the volume of air (cm3) passing through the test piece using the conversion table attached to the tester. 3 / (cm 2 100 seconds) (iv) The arithmetic mean value of the air permeability of the 10 test pieces obtained was rounded off to the first decimal place to obtain the air permeability (cm 3 / (cm 2 Calculate the time (seconds).

[0062] The spunbond nonwoven fabric of the present invention has a bending resistance in the MD direction of the nonwoven fabric of 40 mN or more and 80 mN or less. If the bending resistance is 40 mN or more, more preferably 45 mN or more, and even more preferably 50 mN or more, the strength and shape retention of the nonwoven fabric can be maintained while pleating. On the other hand, if the bending resistance is 80 mN or less, more preferably 75 mN or less, and even more preferably 70 mN or less, the folding resistance during pleating is reduced, and the pleats have a sharp peak-valley shape.

[0063] The bending resistance in the present invention is a value obtained as follows in accordance with JIS L1913:2010 "General nonwoven fabric testing methods" 6.7 "Bending resistance (JIS method and ISO method)" 6.7.4 "Gurley method (JIS method)". (i) Test pieces with a length of 38.1 mm (effective sample length L = 25.4 mm) and a width of d = 25.4 mm are taken from any five points on the sample. Here, in the present invention, the longitudinal direction of the nonwoven fabric is defined as the warp direction of the sample. (ii) Attach each of the collected test pieces to a chuck and fix the chuck so that it is aligned with the 1-1 / 2" (1.5 inches = 38.1 mm) scale on the movable arm A. In this case, 1 / 2" (0.5 inches = 12.7 mm) of the sample length is applied to the chuck by 1 / 4" (0.25 inches = 6.35 mm), and 1 / 4" (0.25 inches = 6.35 mm) is applied to the tip of the pendulum at the free end of the sample, so the effective sample length L for measurement is the test piece length minus 1 / 2" (0.5 inches = 12.7 mm). (iii) Next, insert a suitable weight W into the lower weight mounting holes a, b, and c (mm) from the fulcrum of the pendulum B. a , W b , W c (g) is attached to the movable arm A, and the movable arm A is rotated at a constant speed, and the scale RG (mgf) is read when the test piece separates from the pendulum B. The scale is read to the first decimal place. The weight to be attached to the weight attachment hole can be selected appropriately, but it is preferable to set the scale RG to 4 to 6. (iv) Measurements are performed on five test pieces, five times on each side, for a total of 50 times. (v) The bending resistance value was calculated from the obtained RG scale value by using the following formula (3), rounding off to one decimal place. The average value of 50 measurements was rounded off to one decimal place to calculate the bending resistance in the MD direction.

number

[0064] As described above, the spunbonded nonwoven fabric of the present invention has a good balance between dust collection performance and breathability, and is excellent in rigidity and pleat processability, so it can be suitably used as a filter material for pleated filters of dust collectors and pleated filters of dust collectors.Among them, the nonwoven fabric alone is particularly suitable for use as a filter material for pleated filters of large air volume pulse jet type dust collectors and filters of large air volume pulse jet type dust collectors, which require dust collection under a large air volume of more than 300 L / min and pleat shape retention that can withstand repeated backwashing.Such a filter material for pleated filters of dust collectors can be obtained, for example, by making the spunbonded nonwoven fabric into a pleated shape.

[0065] Fig. 2 is a schematic perspective view showing an example of the filter material for the pleated filter of the present invention. The filter material for the pleated filter of the dust collector 1 shown in Fig. 2 has a peak 2 and a valley 3 formed by folding back a spunbonded nonwoven fabric. When determining the MD direction and the CD direction from the filter material for the pleated filter of the dust collector that has been pleated, in the case of the filter material for the pleated filter of the dust collector 1 as exemplified in Fig. 2, the direction parallel to the ridge of the peak 2 (broken line arrow 5) is the CD direction, and the direction perpendicular to the CD direction (broken line arrow 4) is the MD direction.

[0066] In addition, this filter material for a dust collector pleated filter can be made into a cylindrical dust collector filter in which the entire filter material is formed into a cylindrical shape and then the upper and lower ends of the cylinder are fixed to it, or it can be made into a panel-type dust collector filter in which the ends of the filter material for a dust collector pleated filter are fixed to the inner wall of a rectangular or round frame material made of a metal material or a polymer resin material.

[0067] The pulse jet type dust collector of the present invention uses the pleated filter for dust collectors, and is particularly a high-volume pulse jet type dust collector that performs dust collection and repeated backwashing under a high air volume of more than 300 L / min. In this high-volume pulse jet type dust collector, the dust collector filter is used in an atmosphere in which the flow rate per dust collector filter is 3.0 L / min to 5.0 L / min and the pressure of the processing air acting on each dust collector filter is 0.5 MPa to 0.7 MPa.

[0068] The pulse jet type dust collector of the present invention is provided with at least one dust collector filter that filters the dust collected from the equipment to be collected, and a pulse jet mechanism that injects compressed air in a pulsed manner onto the inner surface of the dust collector filter to remove dust adhering to the outer surface of the filter. This pulse jet mechanism may be an online pulse type mechanism that can operate while the blower motor of the dust collector is operating, or an offline pulse type mechanism that can operate while dust collection is interrupted. EXAMPLES

[0069] Next, the spunbond nonwoven fabric of the present invention will be specifically described based on examples, although the present invention is not limited to these examples.

[0070] (Measurement method) The respective characteristic values ​​in the following examples were measured by the following methods. However, in the measurement of each physical property, unless otherwise specified, the measurement was carried out based on the above-mentioned method.

[0071] (1) Melting point of polyester (℃) A differential scanning calorimeter, "DSC-2 type" manufactured by PerkinElmer Japan Co., Ltd., was used, and measurements were performed under conditions of a heating rate of 20°C / min and a measurement temperature range of 30°C to 300°C, and the temperature at which the obtained melting endothermic curve gave an extreme value was determined as the melting point of the thermoplastic resin. For resins whose melting endothermic curves did not show an extreme value in the differential scanning calorimeter, the resin was heated on a hot plate, and the temperature at which the resin melted under a microscope was determined as the melting point.

[0072] (2) Intrinsic viscosity of polyester (IV) The intrinsic viscosity (IV) of the polyester was measured by the following method. Dissolve 8 g of sample in 100 mL of orthochlorophenol, and measure the relative viscosity η using an Ostwald viscometer at 25°C. r was calculated by the following formula. η r = η / η 0 =(t × d) / (t 0 ×d 0 ) (Here, η is the viscosity of the polymer solution, η 0 is the viscosity of orthochlorophenol, t is the time it takes for the solution to fall (sec), and d is the density of the solution (g / cm 3 ), t 0 is the fall time of orthochlorophenol (seconds), d 0 is the density of orthochlorophenol (g / cm 3 ) and Next, the relative viscosity η r The intrinsic viscosity (IV) was calculated from the following formula: Intrinsic viscosity (IV)=0.0242η r +0.2634

[0073] (3) Weight of spunbond nonwoven fabric (g / m 2 ), CV value (%) The basis weight and basis weight CV value of the spunbond nonwoven fabric were calculated by the method described above.

[0074] (4) Thickness of spunbond nonwoven fabric (mm) The thickness of the spunbond nonwoven fabric was measured and calculated by the above-mentioned method using a thickness gauge "TECLOCK" (registered trademark) SM-114 manufactured by TECLOCK Corporation.

[0075] (5) Apparent density of spunbond nonwoven fabric (g / cm 3 ) The apparent density of spunbond nonwoven fabric is defined as "(3) Basis weight of spunbond nonwoven fabric (g / m 2 The nonwoven fabric weight was calculated by the method described above from the basis weight of the spunbond nonwoven fabric obtained in "(4) Thickness of spunbond nonwoven fabric (mm)" and the basis weight CV value (%) of the spunbond nonwoven fabric obtained in "(5) Thickness of spunbond nonwoven fabric (mm)".

[0076] (6) Bending resistance of spunbond nonwoven fabric (mN) The bending resistance of the spunbond nonwoven fabric was measured and calculated using the Gurley flexibility tester "GAS-10" manufactured by Daiei Seiki Seisakusho Co., Ltd., in the manner described above.

[0077] (7) Angle (°) of the curve from the concave portion to the convex portion of the fused portion of the spunbond nonwoven fabric The scanning electron microscope used was a VHX-D500 manufactured by Keyence Corporation, and measurements and calculations were performed using the methods described above.

[0078] (8) Fused area ratio of spunbond nonwoven fabric (%) The fusion area ratio of the spunbonded nonwoven fabric was measured using a digital microscope "VHX-5000" manufactured by Keyence Corporation, and was measured and calculated by the method described above.

[0079] (9) Pleating processability of spunbond nonwoven fabric A sample measuring 50 cm wide and 1 m long was pleated with a rotary pleating machine at a pitch of 3 cm and evaluated according to the following criteria. A: The pleats are sharp and uniform, and the sheet does not meander. B: The pleats are slightly uneven and the sheet has slight meandering. C: The pleats are uneven and the sheet is meandering.

[0080] (10) Air permeability of spunbond nonwoven fabric (cm 3 / (cm 2 ·sec)) The air permeability of the spunbond nonwoven fabric was measured using the air permeability tester "FX3300-III" manufactured by Textest, Switzerland.

[0081] (11) Collection performance of spunbond nonwoven fabric (%) FIG. 3 is a diagram for explaining the configuration of a test system for carrying out a collection performance test according to an embodiment of the present invention. The test system 6 shown in FIG. 3 includes a sample holder 7 for setting a test sample M, a flowmeter 8, a flow rate control valve 9, a blower 10, a dust supply device 11, a changeover cock 12, and a particle counter 13. The dust supply device 11, the flowmeter 8, the flow rate control valve 9, the blower 10, and the dust supply device 11 are connected to the sample holder 7. The flowmeter 8 is connected to the blower 10 via the flow rate control valve 9. Dust is supplied from the dust supply device 11 to the sample holder 7 by the intake of the blower 10. The particle counter 13 is connected to the sample holder 7, and the number of dust particles on the upstream side and the downstream side of the test sample M can be measured via the changeover cock 12. First, three samples of 15 cm×15 cm are taken from any part of the nonwoven fabric, and the taken test sample M is set in the sample holder 7. The evaluation area of ​​the test sample is 115 cm 2 In measuring the collection performance, a 10% by weight solution of polystyrene 0.309U (manufactured by Nacalai Tesque, Inc.) was diluted 200 times with distilled water and filled into the dust supply device 11. The air volume was adjusted with the flow rate control valve 9 so that the filter passing speed was 3.0 m / min, and the dust concentration was set to 20,000 to 70,000 particles / (2.83×10 -4 m 3 (0.01ft 3The dust counts upstream and downstream of the test sample M were measured for dust particle sizes in the range of 0.3 to 0.5 μm using a particle counter 13 (KC-01D, manufactured by Rion Co., Ltd.). The values ​​obtained were substituted into the following calculation formula, and the resulting value was rounded off to the first decimal place to determine the collection performance (%). Collection performance (%)=[1-(D1 / D2)]×100 Here, D1 is the number of dust particles downstream (total of three measurements), and D2 is the number of dust particles upstream (total of three measurements).

[0082] (11) Dust removal properties of spunbond nonwoven fabric FIG. 4 is a diagram for explaining the configuration of a test system for carrying out a dust brushing off property test according to an embodiment of the present invention. The same components as those in FIG. 3 are given the same reference numerals. The test system 14 shown in FIG. 4 includes a sample holder 7 for setting a test sample M, a flowmeter 8, a flow rate control valve 9, a blower 10, a dust supply device 11, a pulse jet device 15, and a pressure gauge 16. The flowmeter 8, the dust supply device 11, the pulse jet device 15, and the pressure gauge 16 are connected to the sample holder 7. The flowmeter 8 is connected to the blower 10 via the flow rate control valve 9. The dust is supplied from the dust supply device 11 to the sample holder 7 by the intake of the blower 10. The pulse jet device 15 sprays compressed air to remove dust attached to the test sample M. First, three samples of 15 cm×15 cm are taken from any part of the nonwoven fabric, and the taken test sample M is set in the sample holder 7. The evaluation area of ​​the test sample is 115 cm 2 At this time, a pressure gauge 16 was connected to the sample holder 7 so that the pressure loss of the test sample M could be measured. In the test for the brushability, 15 types of standard powders specified by JIS were fed from the dust feeder 11 at 205 g / m 3The air volume was adjusted with the flow control valve 9 so that the filter passing speed was 1.5 m / min, and dust was continuously supplied at a constant concentration. After the pressure loss of the test sample M reached 1500 Pa, compressed air at 0.5 MPa was sprayed from the pulse jet device 15 for 0.1 sec to brush off the dust adhering to the test sample M. The operating time (hr) required for the number of brush-offs to reach 200 was measured, and the operating time (hr) was calculated by averaging the results of three tests and rounding off the average to the nearest 1 digit.

[0083] (Resin used) The resins used in the examples and comparative examples are as follows. Polyester resin A: Polyethylene terephthalate (PET) with a moisture content of 50 mass ppm or less, an intrinsic viscosity (IV) of 0.66, and a melting point of 260°C. Polyester resin B: Copolymerized polyethylene terephthalate (CO-PET) dried to a moisture content of 50 mass ppm or less, with an intrinsic viscosity (IV) of 0.68, an isophthalic acid copolymerization rate of 11 mol%, and a melting point of 230°C.

[0084] Example 1 The polyester resin A and the polyester resin B were melted at temperatures of 295°C and 280°C, respectively. Thereafter, the polyester resin A was used as the core component and the polyester resin B was used as the sheath component, and the spinneret temperature was 300°C. At a mass ratio of core:sheath = 80:20, the core-sheath type filaments were melt-spun at a discharge rate set so that the average single fiber diameter was 17 μm, and the filaments were continuously pulled at a high speed of about 5000 m / min with air pressure. Subsequently, the filaments were sprayed and opened with air pressure, and deposited on a moving net to form a nonwoven web, which was fused by a pair of heated embossing rolls under conditions of a linear pressure of 60 kg / cm, a roll surface temperature of 200°C, and a fusion area ratio of 10%, resulting in fabrics having basis weights of 150, 200, and 250 g / m. 2 The composition and results of Example 1 are shown in Table 1. [Table 1]

[0085] Example 2 The discharge rate was set so that the average single fiber diameter of the core-sheath type filament was 24 μm, and the fusion conditions of the heated embossing roll were a line pressure of 70 kg / cm, a roll surface temperature of 205° C., and a fusion area ratio of 20%, with all other conditions being the same as in Example 1. 2 The configuration and results of Example 2 are shown in Table 1.

[0086] Example 3 The amount of polyester resin A discharged was adjusted so that the average single fiber diameter was 17 μm, to obtain a single component filament. The amount of polyester resin B discharged was further adjusted so that the average single fiber diameter was 17 μm, to obtain a single component filament. The single component filament made of polyester resin A and the single component filament made of polyester resin B were spun and mixed, and continuously pulled at a high speed of about 5000 m / min by air pressure. The filaments were then sprayed, opened, and deposited on a moving net to form a nonwoven web, which was fused by a pair of heated embossing rolls under conditions of a linear pressure of 60 kg / cm, a roll surface temperature of 200° C., and a fusion area ratio of 18%, to obtain a basis weight of 150 g / m. 2 , 200g / m 2 , 250g / m 2 Thus, mixed fiber nonwoven fabrics were obtained, each consisting of a single component filament made of polyester resin A and a single component filament made of polyester resin B. The configuration and results of Example 3 are shown in Table 1.

[0087] The evaluation results of the bending resistance, basis weight CV value, angle of the curve from the fused portion to the non-fused portion, and pleating processability of the nonwoven fabrics described in Examples 1 to 3 are shown in Table 1. As is clear from Table 1, all of the nonwoven fabrics of Examples 1 to 3 had a bending resistance of 25 mN or more, a basis weight CV value of 5% or less, and were good in pleating processability and dust removal properties, and had satisfactory properties as a filter substrate.

[0088] Comparative Example 1 The discharge rate was set so that the average single fiber diameter of the core-sheath type filament was 27 μm, and the fusion conditions of the heated embossing roll were a line pressure of 70 kg / cm, a roll surface temperature of 205° C., and a fusion area ratio of 23%. All other conditions were the same as in Example 1. The basis weights were 150, 200, and 250 g / m. 2 The results of evaluation of various properties of the nonwoven fabric are shown in Table 1. As is clear from Table 1, the nonwoven fabric has a basis weight of 150 g / m 2 The pleat processability was somewhat uneven at 100% and the dust brushing off property was insufficient at all basis weights. In addition, because the thickness of the nonwoven fabric was low and the apparent density was high, when it was used as a filter substrate, the air permeability was low and the pressure increased due to the adhesion of dust over time, and the collection performance was also unfavorable.

[0089] Comparative Example 2 The polyester resin A was extruded at a rate adjusted so that the average single fiber diameter was 11 μm, and the polyester resin B was extruded at a rate adjusted so that the average single fiber diameter was 11 μm. Single component filaments were obtained from each resin, and these were mixed to obtain a nonwoven fabric. The other conditions were all the same as in Example 3, and nonwoven fabrics were produced with basis weights of 150, 200, and 250 g / m. 2 The results of evaluation of various properties of the nonwoven fabric are shown in Table 1. As is clear from Table 1, the nonwoven fabric has a basis weight of 150 g / m 2 At 200 g / m, the pleating process was uneven and the sheet was meandering. 2 The pleatability was somewhat non-uniform even in the nonwoven fabric, and the dust brushing off property was insufficient for all basis weights. In addition, since the thickness of the nonwoven fabric was low and the apparent density was high, when it was used as a filter substrate, the air permeability was low, pressure rise occurred due to dust adhesion over time, the collection performance was also inferior, and the pleatability was also inferior, making it undesirable. [Explanation of symbols]

[0090] 1 Filter media for pleated filters of dust collectors 2. Yamabe 3 Valley 4 Arrow indicating MD direction (dashed arrow) 5 Arrows indicating the CD direction (dashed arrows) 6, 14 Test System 7. Sample Holder 8 Flow meter 9 Flow Control Valve 10 Blower 11 Dust supply device 12 Switch cock 13 Particle Counter 15 Pulse jet device 16 Pressure gauge 101 Fusion part 102 Non-fused part M Test Sample

Claims

1. It is composed of thermoplastic continuous filaments consisting of a high melting point component and a low melting point component, The thermoplastic continuous filament has an average single fiber diameter of 12 μm or more and 26 μm or less, The sheet has a fused portion that is partially fused and a non-fused portion that is not fused, The basis weight CV value is 5% or less, The ratio of the area of ​​the fused portion is 5% or more and 20% or less, The apparent density of the spunbond nonwoven fabric is 0.25 g / cm 3 or more and 0.40 g / cm 3 or less, A spunbond nonwoven fabric, wherein angles R1 and R2 formed by boundary surfaces between the fused portion and the non-fused portion are different from each other, angle R1 being 15° or more and 31° or less, and angle R2 being 45° or more and 75° or less.

2. 2. The spunbond nonwoven fabric according to claim 1, wherein the thermoplastic continuous filaments are made of polyethylene terephthalate as the high melting point component and a copolymer polyester or polybutylene terephthalate as the low melting point component.

3. 3. The spunbonded nonwoven fabric according to claim 1, wherein the fused portion is formed by fusion bonding from both the top and bottom sides of the spunbonded nonwoven fabric.

4. A filter material for a pleated filter of a dust collector, comprising the spunbond nonwoven fabric according to any one of claims 1 to 3.

5. A pleated filter for a dust collector, comprising the filter material for a pleated filter for a dust collector according to claim 4.

6. A high volume pulse jet type dust collector using the pleated filter according to claim 5.

Images