JP5082365B2 - Nonwoven fabric for filters - Google Patents

Description

  The present invention relates to a non-woven fabric for a filter which is excellent in dust collection performance and further excellent in mechanical properties and dimensional stability.

  Conventionally, various nonwoven fabrics have been proposed as materials for air filters or liquid filters for removing dust. Particularly in recent years, thermocompression-type long fiber nonwoven fabrics having excellent rigidity have been suitably used as pleated filters. When a pleated filter material is used, it is possible to reduce the filtration wind speed because the filtration area can be widened, and there is an advantage that the dust collecting ability can be improved and the mechanical pressure loss can be reduced.

  However, the conventional thermocompression type long fiber nonwoven fabric has a fiber diameter of about 10 μm even if it is thin, and does not have a sufficient collection ability.

  For example, Patent Document 1 proposes a composite long-fiber nonwoven fabric for filters made of deformed fibers. According to this technology, the mechanical properties and dimensional stability of the nonwoven fabric for filters can be improved, but the fiber diameter of the constituent fibers is 2 to 15 dtex, that is, about 13 μm even if it is thin, and the particle diameter is several μm or less. It was not enough to collect the dust.

  Further, Patent Document 2 proposes a filter nonwoven fabric in which a plurality of nonwoven fabrics are laminated. According to this technique, it is easy to produce a non-woven fabric for a filter having a high basis weight, and it is possible to obtain a non-woven fabric for a filter excellent in air permeability. However, the nonwoven fabric proposed in this technology is a laminate of a nonwoven fabric having a fiber diameter of 7 to 20 μm and a nonwoven fabric having a fiber diameter of 20 to 50 μm. The following dust was not able to be collected enough.

  On the other hand, in order to improve the dust collection performance of the filter nonwoven fabric, various filter nonwoven fabrics containing ultrafine fibers have been proposed.

  For example, Patent Document 3 proposes a non-woven fabric for a filter which is a laminate of a low-melting point nonwoven fabric and a non-woven fabric containing ultrafine fibers and is integrated by melting the low-melting point nonwoven fabric. According to the technology, it is possible to make a non-woven fabric without melting the ultrafine fibers, and thereby the inter-fiber voids inside the non-woven fabric can be held in a fine state, so that a non-woven fabric with excellent dust collection performance can be obtained. It is possible to manufacture. However, in this technique, since the ultrafine fibers do not contribute to the integration of the nonwoven fabric, there is a problem that the ultrafine fiber portion is easily dropped from the nonwoven fabric, and further, the constituent ratio of the ultrafine fibers cannot be increased. Furthermore, the ultrafine fiber in the technology is substantially introduced from a split-type non-woven fabric of the ultrafine fiber expression type, and high pressure liquid flow treatment, needle punch processing, or buckling treatment is performed for the ultrafine fiber expression. It was necessary and it was not excellent in productivity.

Furthermore, Patent Document 4 proposes a non-woven fabric for a filter having a basis weight of 10 to 50 g / m ^{2 made} of an ultrafine fiber non-woven fabric having a fiber diameter of 1 to 6 μm and a long fiber non-woven fabric having a fiber diameter of 10 to 30 μm. According to this technology, it is possible to propose a non-woven fabric with less powder leakage when extracting coffee powder or the like. However, since the basis weight of the nonwoven fabric provided by this technique is about 10 to 50 g / m ^2, it does not have sufficient strength to be used as an industrial filter. Moreover, in the said technique, it was necessary to coat | cover the opening part of the surface of a long-fiber nonwoven fabric with an ultrafine fiber, and it was complicated as a manufacturing method. Further, the technology is substantially composed of an ultrafine fiber nonwoven fabric made of a melt blown nonwoven fabric and a long fiber nonwoven fabric made of a spunbond nonwoven fabric, and the raw material is made of a polyester or polyolefin resin. However, when a polyester resin is used as a raw material, orientation crystallization of the polyester is often insufficient in the melt blown nonwoven fabric, and when heat bonding is performed, the sheet cures or the sheet shrinks significantly. There was a point. Further, even when such a nonwoven fabric is used as a filter, there is a problem that the sheet is cured or contracted in a high temperature use environment. On the other hand, when a polyolefin-based resin is used as a raw material, since the melting point is low, the heat resistance is inferior, and the texture of the sheet is soft, which is not preferable for use as a pleated filter. there were. Furthermore, when the meltblown nonwoven fabric and the spunbonded nonwoven fabric are made of different resins, there is a problem in that the compatibility between the resins is insufficient, so that integration by thermal bonding becomes difficult.
JP 2001-276529 A JP 2004-124317 A Japanese Patent Laid-Open No. 2001-248056 JP 2004-154760 A

  In view of the above-mentioned problems of the prior art, the present invention provides a nonwoven fabric for a filter that is excellent in mechanical strength and dimensional stability and excellent in dust collection performance.

The present invention employs the following means in order to solve such problems .

( 1 ) A nonwoven fabric obtained by laminating and integrating a meltblown nonwoven fabric comprising fibers having an average fiber diameter of 1 to 8 μm and a spunbond nonwoven fabric comprising core-sheath fibers having an average fiber diameter of 10 to 30 μm, And the sheath component of the core-sheath fiber of the core-sheath-type spunbonded nonwoven fabric are made of the same polymer, and both comprise polybutylene terephthalate or polytrimethylene terephthalate, A nonwoven fabric for filters, wherein the core component comprises polyethylene terephthalate.

( 2 ) The melt-blown nonwoven fabric and the spunbond nonwoven fabric laminated and integrated have a partial thermocompression bonding portion, and the partial thermocompression bonding area ratio is 3 to 50%. non-woven fabric according to (1) to.

( 3 ) The basis weight of the laminated and integrated nonwoven fabric is 80 to 300 g / m ² , and the weight ratio of the melt blown nonwoven fabric is 3 to 60% of the total weight (1) Or the nonwoven fabric for filters as described in ( 2 ).

( 4 ) The filter nonwoven fabric according to any one of (1) to ( 3 ), wherein the collection efficiency of polystyrene dust having a particle size of 0.3 to 0.5 μm is 50 to 100%.

( 5 ) The nonwoven fabric for filters according to any one of (1) to ( 4 ), wherein the nonwoven fabric is processed into a pleated shape.

( 6 ) The filter nonwoven fabric according to any one of (1) to ( 5 ), wherein the filter is an industrial filter.

  ADVANTAGE OF THE INVENTION According to this invention, the nonwoven fabric for filters which is excellent in mechanical strength and thermal stability, and excellent in the dust collection performance can be provided.

  The melt blown nonwoven fabric in the present invention is represented by a method in which a melted polymer is extruded from a die, and the melted polymer is stretched while being blown with a heated high-speed gas fluid or the like to form ultrafine fibers and collected to form a sheet. It is manufactured by the so-called melt blow method.

  The average fiber diameter of the fibers constituting the meltblown nonwoven fabric is 1 to 8 μm, preferably 2 to 7 μm. When the average fiber diameter is smaller than 1 μm, when the polymer is stretched to form ultrafine fibers, the fibers are easily cut and a lump polymer may be mixed, which is not preferable. Furthermore, there is a tendency that the air permeability of the nonwoven fabric is lowered, which is not preferable. When the average fiber diameter is more than 8 μm, the fiber becomes too thick, which is not preferable because the dust collection performance tends to be lowered. In addition, the average fiber diameter here refers to a total of 100 fibers, 10 of which are randomly sampled from a nonwoven fabric, photographed 500 to 3000 times with a scanning electron microscope or the like, and 10 from each sample. It is obtained by measuring the diameter and rounding off the first decimal place of the average value.

  Moreover, the melt blown nonwoven fabric in the present invention contains polybutylene terephthalate or polytrimethylene terephthalate, and it is desirable that any one of them is a main component. Specifically, any of these is preferably 50% by weight or more, more preferably 70% by weight or more, and further preferably 90% by weight or more. A melt blown nonwoven fabric made of polybutylene terephthalate or polytrimethylene terephthalate is preferable because it has a relatively high melting point and is excellent in heat resistance and also has excellent dimensional stability due to heat. Particularly preferred is a melt blown nonwoven fabric made of polybutylene terephthalate from the viewpoint of high dimensional stability due to heat and less contamination of the die during injection of molten polymer.

  Furthermore, a crystal nucleating agent, a matting agent, a pigment, an antifungal agent, an antibacterial agent, a flame retardant, a hydrophilic agent, and the like may be added to the raw material resin of the melt blown nonwoven fabric as long as the effects of the present invention are not impaired. Moreover, as long as the original function is not impaired, it may contain a very small amount of a copolymer component.

  In addition, the spunbond nonwoven fabric used in the present invention is obtained by extruding a molten polymer from a die, sucking and stretching it with a high-speed suction gas, etc., and collecting it on a moving conveyor to form a web, and further continuously heat-treating it. , Manufactured by a so-called spunbond method, represented by a method of forming a sheet by entanglement or the like.

  The average fiber diameter of the fibers constituting the spunbonded nonwoven fabric is 10 to 30 μm, and preferably 12 to 25 μm. When the average fiber diameter is smaller than 10 μm, the air permeability of the nonwoven fabric is lowered and the rigidity of the nonwoven fabric tends to be lowered, which is not preferable. Further, yarn breakage tends to occur during the production of the spunbonded nonwoven fabric, which is not preferable from the viewpoint of production stability. When the average fiber diameter is larger than 30 μm, yarn breakage is liable to occur due to poor cooling of the yarn during production of the spunbond nonwoven fabric, which is not preferable from the viewpoint of production stability. In addition, the average fiber diameter here refers to a total of 100 fibers, 10 of which are randomly sampled from a nonwoven fabric, photographed 500 to 3000 times with a scanning electron microscope or the like, and 10 from each sample. It is obtained by measuring the diameter and rounding off the first decimal place of the average value.

  The spunbonded nonwoven fabric is a polyester-based nonwoven fabric. Polyester-based nonwoven fabrics are preferable because they have a high melting point and are excellent in heat resistance and also in rigidity. The polyester-based non-woven fabric is a spunbonded non-woven fabric made only of polyethylene terephthalate, or a core-sheathed fiber comprising a copolymer polyester whose core part contains polyethylene terephthalate and whose sheath part has a lower melting point than the polymer of the core part. A spunbonded nonwoven fabric is a preferred form in terms of the strength and rigidity of the nonwoven fabric. The copolymer polyester preferably has a melting point of 15 ° C. or more lower than that of polyethylene terephthalate contained in the core. The copolymer polyester is preferably copolymer polyethylene terephthalate, and the copolymer component is preferably isophthalic acid or adipic acid.

  Further, the spunbond nonwoven fabric is made of core-sheath type fibers, the core component includes polyethylene terephthalate, the sheath component includes polybutylene terephthalate or polypropylene terephthalate, and is structurally similar to the meltblown nonwoven fabric. Preferably, it is the most preferable form consisting of the same polymer. When such a core-sheath fiber is employed, polyethylene terephthalate, which is the core component, has a higher melting point than the polymer constituting the sheath component. . Furthermore, when the polymer of the sheath component is structurally similar to the meltblown nonwoven fabric, or in particular, the same polymer, the compatibility between the meltblown nonwoven fabric and the spunbonded nonwoven fabric is improved, and a strong integrated structure is obtained during thermocompression bonding. It becomes possible. Particularly preferred is a combination of a melt blown nonwoven fabric made of polybutylene terephthalate and a spunbonded nonwoven fabric made of core-sheath type fibers whose sheath component is polybutylene terephthalate.

  In the present invention, the core-sheath type means that the sheath component is coated concentrically or eccentrically around the core component, and the sheath component is arranged in a multi-leaf shape around the core component. Is a preferred form. The multileaf shape refers to the shape shown in FIG. 2, for example. Most preferred are concentric core-sheath fibers from the viewpoint of production simplicity. The weight ratio of the core: sheath is not particularly limited, but is preferably in the range of 30:70 to 95: 5, and more preferably in the range of 40:60 to 90:10.

  Furthermore, the cross-sectional shape of the fibers constituting the spunbonded nonwoven fabric is not limited in any way, but it is circular, hollow round, elliptical, flat, or deformed, such as X or Y, polygonal, multileaf A mold or the like is a preferred form. The fiber diameter of the non-circular fiber may be a circumscribed circle and an inscribed circle with respect to the fiber cross section, and the average value of the diameters may be the fiber diameter.

  Furthermore, the raw material resin of the spunbond nonwoven fabric according to the present invention includes a crystal nucleating agent, a matting agent, a pigment, an antifungal agent, an antibacterial agent, a flame retardant, a hydrophilic agent, etc., as long as the effects of the present invention are not impaired. May be. Moreover, as long as the original function is not impaired, it may contain a very small amount of a copolymer component.

  The integration of the meltblown nonwoven fabric and the spunbonded nonwoven fabric in the present invention is preferably performed by partial thermocompression bonding. It is also a preferred method to perform partial thermocompression bonding after mechanical entanglement by water jet punching or needle punching. The method of partially thermocompression bonding is not particularly limited, but bonding with a pair of hot embossing rolls or bonding with an ultrasonic oscillator and an embossing roll is preferable. The temperature of heat bonding by the hot embossing roll is preferably 5 to 50 ° C., more preferably 10 to 40 ° C. lower than the melting point of the fibers constituting the meltblown nonwoven fabric. When the temperature of heat bonding by the hot embossing roll is lower than the melting point of the fibers constituting the melt blown nonwoven fabric by less than 5 ° C., the resin melts severely, the sheet is taken to the embossing roll, and roll contamination occurs. Not only becomes hard, but also roll winding often occurs, making stable production impossible. When the temperature is lower than the melting point of the fibers constituting the melt blown nonwoven fabric by more than 50 ° C., the resin is not sufficiently fused, and the integrated nonwoven fabric tends to be weak in physical properties.

  When the partial thermocompression bonding is performed, the pressure-bonding area ratio is preferably 3 to 50% by area with respect to the total area of the nonwoven fabric. More preferably, it is 5-40 area%. When the said crimping | compression-bonding area ratio is less than 3 area%, integration of a melt blown nonwoven fabric and a spun bond nonwoven fabric becomes inadequate, and the interlayer of a nonwoven fabric peels and the intensity | strength tends to become low, and is unpreferable. When the pressure-bonding area ratio exceeds 50 area%, the number of fibers that are melt-deformed by thermocompression bonding increases, and voids between the fibers decrease, which tends to reduce dust collection performance. The area ratio of the partial thermocompression bonding is the ratio of the area of the thermocompression bonding part where the melt blown nonwoven fabric and the spunbond nonwoven fabric are laminated and integrated to the total contact area of both nonwoven fabrics. This does not include the area of thermocompression performed when manufacturing.

  In addition, the method for laminating the melt blown nonwoven fabric and the spunbonded nonwoven fabric in the present invention is not limited at all. A method of spraying and laminating yarns on the melt blow method, a method of spraying and laminating yarns on the melt blown nonwoven fabric once produced, and a combination thereof. Alternatively, the melt blow web and the spunbond web can be continuously laminated and then integrated by thermocompression bonding to form a nonwoven fabric.

  Furthermore, the lamination form of the melt blown nonwoven fabric (M) and the spunbond nonwoven fabric (S) in the present invention is not limited at all, but SM lamination, SMS lamination, SMMS lamination, etc. are preferable forms (for example, SMS Lamination refers to a laminate in which one layer of melt blown nonwoven fabric is sandwiched between one layer of spunbond nonwoven fabric from both sides. When a plurality of layers of melt blown nonwoven fabric or spunbonded nonwoven fabric are laminated, there is no problem as long as the average fiber diameter and fiber shape of each constituent fiber are different as long as they are within the above-mentioned average fiber diameter and fiber shape range.

In the present invention, the basis weight of the nonwoven fabric laminated and integrated is preferably in the range of 80 to 300 g / m ² . When the basis weight is less than 80 g / m ² , the strength and rigidity of the nonwoven fabric may be insufficient, which is not preferable. When the weight per unit area exceeds 300 g / m ² , the strength and rigidity of the nonwoven fabric are sufficient, but the air permeability tends to be lowered, and further, the cost is not preferable. A more preferable basis weight range of the nonwoven fabric formed by laminating and integrating is 100 to 270 g / m ² . The basis weight here refers to 5.2 of JIS L1906 (2000 edition), three samples were taken and each weight was measured, and the average value of the obtained values was converted per unit area, and the number after the decimal point It is calculated by rounding off the first place.

  Moreover, 3 to 60% is preferable, and, as for the weight ratio of the said melt blown nonwoven fabric to the nonwoven fabric formed by lamination | stacking integration, 5 to 50% is more preferable. When the weight ratio of the meltblown nonwoven fabric is less than 3%, the dust collection performance tends to be too low, and it is not preferable. When the weight percentage of the meltblown nonwoven fabric exceeds 60%, the dust collection performance is excellent. Further, the air permeability tends to be lowered, and further, it is not preferable from the viewpoint of cost.

  In the nonwoven fabric obtained by laminating and integrating in the present invention, an antifungal agent, an antibacterial agent, a flame retardant, a hydrophilic agent, a pigment, a dye, and the like are partially or wholly provided within a range that does not impair the effects of the present invention. Also good.

  Further, the nonwoven fabric for filter of the present invention has a particle size of 0.3 in the evaluation of the dust collection performance described in the column of Examples described later, or the evaluation of the dust collection performance capable of obtaining the same result. It is preferable that collection efficiency of polystyrene dust of ˜0.5 μm is 50 to 100%. A more preferable collection efficiency is 55 to 100%. When the collection efficiency is less than 50%, there is a lot of dust leakage, which is not preferable.

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

  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 dimensional stability and excellent dust collection performance. Particularly preferably, the pleated cylindrical unit is used for a bag filter such as a dust collector or a liquid filter such as an electric discharge machine. In particular, in a bag filter for a dust collector, the non-woven fabric of the present invention which is excellent in strength is preferable because the dust accumulated on the filter surface layer during use is subjected to a removal process using backwash air.

  EXAMPLES Hereinafter, although this invention is concretely demonstrated based on an Example, this invention is not limited by these Examples. In addition, each characteristic value of an above-described nonwoven fabric and each characteristic value in the following Example are measured with the following method.

(1) Melting point (° C)
Using a differential scanning calorimeter DSC-2 manufactured by Perkin Elma Co., Ltd., measurement was performed under the condition of a temperature rise temperature of 20 ° C./min, and the temperature giving an extreme value in the obtained melting endotherm curve was defined as the melting point. Each sample was measured three times, and the average value was taken as the melting point of each sample.

(2) Melt viscosity (poise)
The raw material resin was dried to a moisture content of 80 ppm by weight or less, and was measured three times under a nitrogen atmosphere under the conditions of a measurement temperature of 280 ° C. and a strain rate of 6080 sec ⁻¹ using a Toyo Seiki Capillograph 1B. It was set as melt viscosity.

(3) Average fiber diameter (μm)
Ten small piece samples are taken at random from the nonwoven fabric, photographed with a scanning electron microscope at a magnification of 500 to 3000 times, 10 from each sample, 100 fiber diameters are measured, and the number of decimals of the average value is subtracted. Calculated by rounding off the first place.

(4) Weight per unit (g / m ² )
In accordance with JIS L1906 (2000 edition) 5.2, three samples of 50 cm in the vertical direction and 50 cm in the horizontal direction were taken, the weight of each sample was measured, and the average value of the obtained values per unit area Converted to rounded off to the first decimal place.

(5) Tensile strength (N / 5cm)
According to JIS L1906 (2000 edition) 5.3.1, tensile tests were performed on three samples in both the longitudinal and lateral directions of the sheet under the conditions of a sample size of 5 cm × 30 cm, a gripping interval of 20 cm, and a tensile speed of 10 cm / min. . The maximum strength when the sample was pulled until it broke was taken as the tensile strength, and the average value in the longitudinal and lateral directions of the sheet was calculated by rounding off the first decimal place.

(6) Pleating processability A sample having a width of 1 m and a length of 300 m was pleated with a rotary pleating machine so as to have a peak height of 2.5 cm, and evaluated according to the following criteria.
○: The pleat is uniform and there is no problem in processing.
Δ: Pleated is slightly non-uniform.
X: The pleat is uneven and there is a problem in processing.

(7) Area shrinkage rate (%)
The area shrinkage ratio of the melt blown nonwoven fabric was measured by the following method.
Referring to JIS L1906 (2000 edition) 5.9.1, three 25cm long x 25cm wide samples were taken from any part of the non-woven fabric, and a mark representing the length of 20cm was placed at three vertical and horizontal positions. (Measured to a unit of 0.01 cm), left in a constant temperature dryer at 90 ° C. ± 2 ° C. × 10 minutes, taken out and cooled to room temperature. Measure the lengths of the three marked vertical and horizontal directions to the nearest 0.01 cm, and apply the following formula to the average value in the vertical and horizontal directions rounded to two decimal places. The area shrinkage rate was calculated by rounding off the second decimal place.
Area shrinkage (%) = 100 − (((L3 × L4) / (L1 × L2)) × 100)
Here, L1: Average length (cm) of the length in the vertical direction of the mark before heating,
L2: average value (cm) of the horizontal length of the mark before heating,
L3: average value (cm) of length in the vertical direction of the mark after heating,
L4: The average value (cm) of the horizontal length of the mark after heating.

(8) Dust collection performance (%)
The dust collection performance was measured by the following method.

Three samples of 15 cm × 15 cm were collected from an arbitrary portion of the nonwoven fabric, and the collection performance of each sample was measured with the collection performance measuring device shown in FIG. This collection performance measuring apparatus has a configuration in which a dust storage box 2 is connected to the upstream side of a sample holder 1 for setting a measurement sample M, and a flow meter 3, a flow rate adjusting valve 4 and a blower 5 are connected to the downstream side. Yes. Further, the particle counter 6 is connected to the sample holder 1, and the number of dusts on the upstream side and the number of dusts on the downstream side of the measurement sample M can be measured via the switching cock 7. In measuring the collection efficiency, a 10% by weight polystyrene 0.309U solution (manufactured by Nacalai Tech) is diluted 200 times with distilled water and filled in the dust storage box 2. Next, the sample M is set in the holder 1, and the air volume is adjusted by the flow rate adjusting valve 4 so that the filter passing speed is 3.0 m / min, and the dust concentration is 20,000 to 70,000 / (2.83 × 10 ⁻⁴ m ³ (0.01 ft ³ )), the dust number D2 upstream of the sample M and the dust number D1 downstream are sampled by a particle counter 6 (manufactured by Lion Co., Ltd., KC-01D) with a dust particle size of 0.1. Measured for each range of 3 to 0.5 μm, rounded off the first decimal place of the numerical value obtained by the following calculation formula to obtain the collection efficiency (%), and those with a collection efficiency of 50% or more were accepted. .
Collection efficiency (%) = [1- (D1 / D2)] × 100
Where D1: number of downstream dust (total of 3 times),
D2: Number of upstream dust (total of 3 times).

Production Example 1
Polybutylene terephthalate (PBT) having a melt viscosity of 390 poise and a melting point of 221 ° C. dried to a moisture content of 80 ppm by weight or less was melted at 280 ° C., and the average fiber diameter was 2 μm under the conditions of the die temperature of 280 ° C. and the heated air temperature of 285 ° C. The amount of hot air and the cooling conditions were adjusted so that a melt blown nonwoven fabric with a basis weight of 30 g / m ² was produced.

Production Example 2
Polytrimethylene terephthalate (PPT) having a melt viscosity of 500 poise and a melting point of 232 ° C. dried to a moisture content of 80 ppm by weight or less is melted at 280 ° C., and the average fiber diameter is 5 μm under the conditions of the die temperature of 280 ° C. and the heating air temperature of 285 ° C. The amount of hot air and the cooling conditions were adjusted so that a melt blown nonwoven fabric with a basis weight of 30 g / m ² was produced.

Comparative Example 1
Polyethylene terephthalate (PET) having a melt viscosity of 250 poise and a melting point of 255 ° C. dried to a moisture content of 80 ppm by weight or less is melted at 285 ° C., and the average fiber diameter becomes 7 μm under the conditions of the die temperature of 285 ° C. and the heated air temperature of 285 ° C. The amount of hot air and the cooling conditions were adjusted to produce a melt blown nonwoven fabric with a basis weight of 30 g / m ² .

  The properties of the obtained melt-blown nonwoven fabric are as shown in Table 1. However, the melt-blown nonwoven fabrics of Production Examples 1 and 2 have low thermal shrinkage (area shrinkage measured according to (7)) and excellent dimensional stability. It was. The melt blown nonwoven fabric made of polyethylene terephthalate of Comparative Example 1 had a high heat shrinkage rate and was inferior in dimensional stability.

Production Example 3
Polyethylene terephthalate (PET) having a melt viscosity of 800 poise and a melting point of 260 ° C. dried to a moisture content of 80 ppm by weight and a melt viscosity of 420 poise dried to a moisture content of 80 ppm by weight and an isophthalic acid copolymerization ratio of 11 mol% having a melting point of 230 ° C. Copolyester (CO-PET) is melted at 295 ° C. and 280 ° C., respectively, with polyethylene terephthalate as a core component and copolymer polyester as a sheath component, a base temperature of 300 ° C., and a weight ratio of core: sheath = 80: 20. After spinning from the pores, the web spun by an ejector at a spinning speed of 4400 m / min and collected on a moving net conveyor is heated with an embossing roll and a flat roll having a convex area of 16%. 140 ° C., and thermocompression bonding under the conditions of a linear pressure 60 kg / cm, fiber diameter 12 [mu] m, basis weight 50 g / m It was prepared spunbonded nonwoven fabric.

Production Example 4
A polyethylene terephthalate (PET) having a melt viscosity of 800 poise and a melting point of 260 ° C. dried to a moisture content of 80 ppm by weight and a polybutylene terephthalate (PBT) described in Production Example 1 dried to a moisture content of 80 ppm by weight are 295 ° C. And melted at 280 ° C., using polyethylene terephthalate as the core component and polybutylene terephthalate as the sheath component, spinning from the pores at a base temperature of 300 ° C. and a weight ratio of core: sheath = 80: 20, and spinning speed of 4400 m by ejector The web obtained by spinning on a moving net conveyor is thermocompression bonded with an embossing roll and a flat roll with a convex area of 16% under the conditions of a temperature of 140 ° C. and a linear pressure of 60 kg / cm. A spunbonded nonwoven fabric having a fiber diameter of 13 μm and a basis weight of 50 g / m ² was produced.

Production Example 5
A spunbonded nonwoven fabric with a basis weight of 120 g / m ² was produced under the same conditions as in Production Example 4 except that the weight ratio of core: sheath = 60: 40 was used.

Reference example 1
The polyester spunbond nonwoven fabric (PET / CO-PET-SB: S) obtained in Production Example 3 is laminated on both sides of the polybutylene terephthalate melt blown nonwoven fabric (PBT-MB: M) obtained in Production Example 1. (SMS lamination) An embossing roll having a pressure bonding area ratio of 16% was used and integrated under conditions of a temperature of 220 ° C. and a linear pressure of 60 kg / cm.

Example 2
The spunbonded nonwoven fabric (PET / PBT-SB: S) obtained in Production Example 4 is laminated on both sides of the polybutylene terephthalate melt blown nonwoven fabric (PBT-MB: M) obtained in Production Example 1 (SMS lamination). The embossing roll having a crimping area ratio of 16% was used and integrated under the conditions of a temperature of 185 ° C. and a linear pressure of 60 kg / cm.

Example 3
The spunbonded nonwoven fabric (PET / PBT-SB: S) obtained in Production Example 5 is laminated on both sides of the polybutylene terephthalate melt blown nonwoven fabric (PBT-MB: M) obtained in Production Example 1 (SMS lamination). Then, an embossing roll having a pressure bonding area ratio of 16% was used and integrated under the conditions of a temperature of 190 ° C. and a linear pressure of 60 kg / cm.

Example 4
^On a spunbonded non-woven fabric (PET / PBT-SB: S) having a basis weight of 50 g / m ² obtained in Production Example 4, a poly fiber having an average fiber diameter of 2 μm and a basis weight of 25 g / m ² was obtained in the same manner as in Production Example 1. Butylene terephthalate melt blown nonwoven fabric (PBT-MB: M) was laminated by jetting and collecting yarn. Further, a spunbond nonwoven fabric (PET / PBT-SB: S) with a basis weight of 125 g / m ² manufactured by the same method as in Production Example 4 was laminated (SMS lamination), and an embossing roll having a crimp area ratio of 16% was obtained. Used and integrated under the conditions of a temperature of 195 ° C. and a linear pressure of 60 kg / cm.

The properties of the obtained nonwoven fabric are as shown in Table 3. However, the nonwoven fabrics of Reference Example 1, Examples 2, 3, and 4 were all excellent in tensile strength and had no problem with pleatability. Also, the dust collection efficiency was all good at 50% or more.

Comparative Example 2
A melt blown nonwoven fabric (PBT-MB) was produced under the same conditions as in Production Example 1 except that the basis weight was 60 g / m ² .

Comparative Example 3
Spinning was performed under the same raw materials and conditions as in Production Example 3, and the resulting web was thermocompression bonded with an embossing roll and a flat roll having a convex area of 16% under conditions of a temperature of 195 ° C. and a linear pressure of 60 kg / cm, A spunbonded nonwoven fabric (PET / CO-PET-SB) having a crimp area ratio of 16%, a fiber diameter of 12 μm, and a basis weight of 130 g / m ² was produced.

Comparative Example 4
Spinning was performed under the same raw materials and conditions as in Production Example 3, and the obtained web was thermocompression bonded with an embossing roll and a flat roll having a convex area of 18% under conditions of a temperature of 200 ° C. and a linear pressure of 60 kg / cm, A spunbonded nonwoven fabric (PET / CO-PET-SB) having a crimped area ratio of 18%, a fiber diameter of 17 μm, and a basis weight of 270 g / m ² was produced.

  The properties of the obtained nonwoven fabric are as shown in Table 3. Although the melt-blown nonwoven fabric of Comparative Example 2 was excellent in dust collection efficiency, the tensile strength was weak and pleating was impossible. The nonwoven fabrics of Comparative Examples 3 and 4 were all excellent in tensile strength and pleatability, but the dust collection efficiency was as low as 15% and 41%, respectively.

  The non-woven fabric for filters of the present invention is excellent in dust collection performance and also has good mechanical strength, and therefore can be suitably used particularly as an industrial air filter or liquid filter.

It is the schematic of a collection performance measuring device. It is the schematic which shows the multileaf shape which is one shape of a core sheath type fiber.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sample holder 2 Dust storage box 3 Flowmeter 4 Flow control valve 5 Blower 6 Particle counter 7 Switching cock 8 Core component in core-sheath fiber (multi-leaf shape) 9 Sheath component M measurement in core-sheath fiber (multi-leaf shape) sample

Claims (6)

A nonwoven fabric in which a meltblown nonwoven fabric composed of fibers having an average fiber diameter of 1 to 8 μm and a spunbonded nonwoven fabric composed of core-sheath fibers having an average fiber diameter of 10 to 30 μm are laminated and integrated, The sheath component of the core-sheath type nonwoven fabric of the spunbond nonwoven fabric is made of the same kind of polymer, and both contain polybutylene terephthalate or polytrimethylene terephthalate, and the core component of the core-sheath type nonwoven fabric is polyethylene terephthalate. A non-woven fabric for a filter, comprising: The portion where the melt blown nonwoven fabric and the spunbonded nonwoven fabric are laminated and integrated has a partial thermocompression bonding portion, and the compression area ratio of the partial thermocompression bonding is 3 to 50%. the non-woven fabric as described in 1. The basis weight of the laminated integrated comprising nonwoven is 80~300g / m ^2, the weight ratio of these said meltblown nonwoven fabric, according to claim 1 or 2, characterized in that 3 to 60% of the total Nonwoven fabric for filters. The filter nonwoven fabric according to any one of claims 1 to 3 , wherein the collection efficiency of polystyrene dust having a particle size of 0.3 to 0.5 µm is 50 to 100%. The filter nonwoven fabric according to any one of claims 1 to 4 , which is processed into a pleated shape. The filter nonwoven fabric according to any one of claims 1 to 5 , wherein the filter is an industrial filter.

Images