JP2009209456A - Filter nonwoven fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter nonwoven fabric which holds a filtration performance, has a high nerve without enlarging a basis mass, and has improved pleat forming processability. <P>SOLUTION: This nonwoven fabric is prepared by laminating a rough layer portion web, a middle layer portion web, and a tight layer portion web containing thermally adhesive staple conjugated fibers, respectively, processing the laminate with needles, heating the processed laminate to apply a thermal adhesive treatment to the laminate, and then processing the treated laminate with a binder. The nonwoven fabric has characteristics comprising a basis mass of 180 to 280 g/m<SP>2</SP>, a tensile elongation of 20 to 50%, an initial tensile elastic modulus of 1,500 to 3,000 N/5 cm/100%, and a nerve of 8.0 to 20.0 N/cm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a filter nonwoven fabric, and particularly to a filter nonwoven fabric having a low basis weight, excellent filtration performance and waist strength, and good workability.

Conventionally, various multi-layer filters having good filter performance have been proposed for integral molding filters. (For example, refer to Patent Documents 1 and 2) For example, in Patent Document 1, a plurality of layers are laminated so that the average denier decreases from large to small from the fluid inflow side to the outflow side with fibers composed of adhesive fibers and high melting point fibers, and needle punches are formed. The denier is 4 to 12d, the porosity is 95 to 99%, the constituent fiber of the outflow side fiber layer is 0.6 to 3d, and the density is 0.07 to 0. A filter non-woven fabric has been proposed in which the adhesive fiber is melted by heating and bonded to the fiber to be bonded, and the average fiber diameter is 0.5 to 6.0 μm and the bulk density is 0. A molded filter in which ultrafine nonwoven fabrics of 0.05 to 0.50 g / m ² are laminated has been proposed. However, when these non-woven fabrics are pleated by integral molding from a flat plate, it is often seen that processing breaks and the filter performance of the finished product are reduced.

By the way, generally, in order to increase the filtration capacity of the filter product, the filter volume is increased. Although the filter volume is related to the filtration area and thickness, pleat processing for increasing the filter length is known as a method for increasing the filtration area. (For example, see Patent Document 3)
In the pleating process, the number of pleats needs to be increased as much as possible in order to obtain a larger filtration area. However, due to the characteristics of the flat plate, the pleat contact occurs even at the same pleat number, and the filtration ability is lowered. This is related to the structure, thickness and hardness of the filter itself. This is because some flat plates may be inferior in molding process, the filter structure may change during the molding process, or the filter performance may not be fully exhibited depending on the form after processing (pleating, etc.). . When the filter performance is actually evaluated for the product, it has been observed that the filter performance is inferior because the pleats contact each other and the actual filtration area decreases.

In general, the larger the mass per unit area, the greater the rigidity and the higher the ventilation resistance, but the filter performance tends to be good. However, from the results so far, in the mass range of 180 to 280 g / m ² , the rigidity is low, and as a result, the waist strength is low. Further, as a filter performance, there is a problem that if the ventilation resistance is lowered, the filtration performance is lowered.
Japanese Patent Laid-Open No. 10-180023 JP-A-4-180808 JP-A-9-173747

  The present invention pays attention to the problems such as the weight per unit area, waist strength, and processability as described above, and is particularly effective by finding the structure and characteristics that can improve the pleat processability without increasing the mass per unit area while maintaining the filtration performance. It aims at providing a typical filter nonwoven fabric.

In order to achieve the above object, the present inventors tried to evaluate the workability and the filter performance by setting the basis weight range of the filter nonwoven fabric to be in the range of 180 to 280 g / m ² . as a result,
(1) Generally, when the basis weight is lowered, the filtration performance and the waist strength tend to be lowered.
(2) When molding nonwoven fabrics, if the basis weight is low, tearing tends to occur during processing. If the mass per unit area decreases, the number of fibers required for filtration performance and waist strength decreases. This is because the intersections between the fibers become difficult to work effectively. For example, in order to increase the number of intersections, more heat-adhesive short fibers are used. Then, although it is effective for waist strength, the bulkiness of the nonwoven fabric is lowered, and the filtration performance is worsened.

  Also, when the number of intersections between the fibers decreases, a place where the deformation strain of the nonwoven fabric is large at the time of molding, for example, a side portion of the heel portion and a portion of the strain portion where the strain is large is broken and a hole is opened. This is particularly likely to occur where there are few heat-bondable short fibers. For this reason, binder bonding after heat bonding is effective in order to provide bulkiness and stabilize the intersection. Further, it has been found that the elongation of the nonwoven fabric is related to the molding process. That is, the filtration performance of the nonwoven fabric is mainly related to the coarse layer portion and the dense layer portion, and the middle layer portion is mainly related to the low back strength. It has been found that it is effective to have an elongation greater than or equal to a predetermined value.

That is, the feature of the present invention is that, based on the above knowledge, each of the coarse layer portion, the middle layer portion, and the dense layer portion containing the heat-adhesive composite short fibers is laminated and needle-processed, followed by heating and thermal bonding. A non-woven fabric obtained by processing a binder after the treatment, wherein the non-woven fabric has a basis weight of 180 to 280 g / m ² , a tensile elongation of 20 to 50%, and an initial tensile elastic modulus of 1500 to 3000 N / 5 cm / 100%. The waist strength has a characteristic of 8.0 to 20.0 N / cm.

Here, the coarse layer portion is composed of a mixed fiber of a high melting point short fiber and a heat-bonding composite short fiber, the fiber mixing ratio is 30/70 to 50/50, the high melting point short fiber is a high melting point resin, and is thermally bonded. The composite short fiber is a core / sheath composite of a low melting point resin of polyester and a high melting point resin, and the fineness of each short fiber is preferably 6.0 to 20.0 dtex, and the middle layer portion is It is preferably composed of 100% by weight of the heat-adhesive composite short fiber, the basis weight is 50 to 90 g / m ² , and the fineness of the short fiber is preferably in the range of 1.0 to 10.0 dtex.

The dense layer portion is composed of a mixture of high melting point short fibers and heat-bondable composite short fibers, the fiber mixture ratio is 30/70 to 50/50, and the fineness of the short fibers is 0.8 to 6.0. It is preferably in the range of decitex (dtex), and the adhesion amount of the binder is preferably 15 to 30 g / m ² .

  The nonwoven fabric of the present invention has the above-described configuration and characteristics, so that the filtration performance is mainly related to the coarse layer portion and the dense layer portion, and the waist strength is mainly related to the middle layer portion. The pleat processing which has low waist strength and does not cause wrinkle contact is possible, has a large filtration area, and has an effect of sufficiently obtaining filtration ability.

  Hereinafter, the specific aspect of this invention nonwoven fabric is explained in full detail. In the present invention, as described above, a nonwoven fabric obtained by first laminating each of webs having different layers, middle layers, and dense layers containing heat-adhesive composite short fibers, needle processing, subsequently heating and heat bonding treatment, and then binder processing. Consists of.

  Here, as each layer which comprises a nonwoven fabric, it is a fiber layer containing a heat bondable composite staple fiber, and a high melting point staple fiber is mixed in part. The melting point of the high melting point short fiber to be mixed is preferably a high melting point resin used for the high melting point short fiber or a melting point equivalent thereto, specifically, polyester resin, polyethylene resin, polypropylene resin, polyamide resin Examples include high-melting component fibers.

  On the other hand, the heat-bondable composite short fiber is preferably a core-sheath type, and the side-by-side type is not preferable because the bonding surface is opposite. The melting point of the high melting point component constituting the composite fiber is preferably higher by 50 ° C. than the melting point of the low melting point component, and the melting point of the component is preferably in the range of 100 ° C. to 180 ° C. When the melting point of the high melting point component is less than 50 ° C. than the melting point of the low melting point component, the high melting point fiber side is also softened during bonding between the single fibers, and a desired filter cannot be obtained. Also, if the melting point of the low melting point component is less than 100 ° C., the processing conditions for carrying out adhesion between the fibers are difficult, which is not preferable from the viewpoint of heat resistance, and if the melting point of the low melting point component exceeds 180 ° C., the heat of the high melting point fiber It affects the characteristics and is not preferable because the filter characteristics fluctuate by performing bonding.

  The polymer constituting the heat-fusible conjugate fiber is composed of, for example, a high melting point component and a low melting point component of a thermoplastic resin of any one of a polyester resin, a polyethylene resin, a polypropylene resin, and a polyamide resin. Specific examples include composite fibers of high-melting polyester fibers (melting point of about 250 ° C. to 270 ° C.) and low-melting polyester fibers (melting point of about 100 ° C. to 200 ° C.), similar melting point ester / nylon composite fibers, polyester / polyethylene composites. Examples thereof include fibers and polypropylene / polyethylene composite fibers, and in particular, composite fibers of high-melting polyester and low-melting polyester are most practical.

  And in each layer which comprises a nonwoven fabric, a coarse layer part is mainly related to filtration performance. The composition is composed of a mixture of high melting point short fibers and heat-adhesive composite short fibers, with a mixture ratio of 30/70 to 50/50, the high melting point short fibers being a high melting point resin, and the heat adhesive composite short fibers being polyester. A core-sheath composite of a low-melting resin and a high-melting resin, and the fineness of the short fibers is preferably in the range of 6.0 to 20.0 dtex.

  When the high melting point short fiber is less than 30 in the mixed fiber ratio of the high melting point short fiber and the heat-adhesive composite short fiber constituting the coarse layer portion, the bulkiness that exhibits filtration performance is poor, and when it exceeds 50, However, it is not preferable because the amount of the core of waist strength is reduced. The fineness of the heat-fusible fiber composite fiber is effectively 6.0 to 20.0 dtex (dtex), and if the fineness is less than 6.0 decitex, it is difficult to obtain a sufficiently bulky filter having filtration performance. . In addition, when the fineness exceeds 20.0 dtex, the number of fibers is reduced and the inter-fiber adhesion point is reduced to obtain bulkiness, but it is difficult to obtain a filter having desired filtration performance.

The middle layer is mainly related to waist strength. The composition is preferably 100% by weight of heat-adhesive composite short fibers, the weight per unit area is 50 to 90 g / m ² , and the fineness of the short fibers is preferably in the range of 1.0 to 10.0 dtex. The middle layer portion may contain a few high melting point short fibers, but the number of intersections between the fibers contributing to the waist strength is reduced, so the amount of fiber blending needs to be considered. Basis weight mass 50~90g / m ² C., is less than 50 g / m ^2, hardly out the effect of filtration performance becomes less weight contributes to lower back strength. If it exceeds 90 g / m ² , the waist strength is sufficient, but the amount of other coarse layers and dense layers related to the filtration performance is reduced, and the effect of the filtration performance is hardly obtained, which is not preferable.

  The fineness of the short fibers in the middle layer is preferably in the range of 1.0 to 10.0 decitex (dtex). If it is less than 1.0 dtex, the amount of fiber is large at the same basis weight, so it is good for the intersection between the fibers, but it is not preferable because the low strength of the short fiber is low and the waist strength becomes weak. On the other hand, if it exceeds 10.0 decitex (dtex), the amount of intersections between fibers is reduced, and the waist strength is lowered.

  The dense layer portion is mainly related to the filtration performance like the coarse layer portion. The composition consists of a mixture of high melting point short fibers and heat-bonding composite short fibers, the fiber mixing ratio is 30 / 70-50 / 50, the high melting point short fibers are high melting point resins, and the heat bonding composite short fibers are polyester. A low-melting resin and a core / sheath composite, and the fineness of the short fibers is preferably in the range of 0.8 to 6.0 dtex.

  In the mixed fiber ratio of the high melting point short fiber and the heat-adhesive composite short fiber constituting the dense layer portion, if the high melting point short fiber is less than 30, the bulkiness that exhibits filtration performance is poor, and if it exceeds 50, This is not preferable because the number of intersections is reduced and the amount of the core of waist strength is reduced. The fineness of the heat-fusible conjugate fiber is preferably 0.8 to 6.0 decitex (dtex), and if the fineness is less than 0.8 decitex, the fineness is too fine and the filtration performance is reduced. On the other hand, when the fineness exceeds 6.0 dtex, the number of fibers decreases, and the filtration performance at which the dense layer portion works decreases.

The present invention is a non-woven fabric obtained by laminating the rough layer portion, the middle layer portion, and the dense layer portion, confounding and integrating by needle punching, and subsequently bonding the constituent fibers by heat and heat bonding treatment, followed by binder processing. To form. Needle processing may be performed with a normal driving number, which is about 30 to 80 / cm ² , preferably 45 to 55 / cm ² . However, it is of course not limited to this.

Also, the heating is usually performed for 40 to 50 seconds with a pin tenter heat treatment machine, a hot roll having a surface temperature of 200 ° C. is brought into contact with the dense layer surface, and a roll at room temperature is brought into contact with the rough layer surface, and the clearance between both is set to about 2.5 mm. And calendered, cooled and wound on a non-woven fabric. Then, the wound nonwoven fabric is finally subjected to binder processing to finally ensure sufficient adhesion between the non-bonded fibers of the heat-bonded fibers between the constituent fibers. Although it is generally used, vinyl acetate may be used. Deposition amount may in the range of 15 to 30 g / m ^2, poor adhesion between unbonded fibers heat fusion fiber between the fibers is less than 15g / m ^2, since the degree contribute to the waist strength is lowered preferably As described above, it is not present.
If it exceeds 30 g / m ² , the adhesion between unbonded fibers of the heat-sealed fibers between the fibers is sufficient, but it is not preferable because the filtration performance is deteriorated.

In the nonwoven fabric thus formed, the present invention has a tensile elongation of 20 to 50% and an initial tensile elastic modulus of 1500 to 3000 N / 5 cm / 100, particularly in a nonwoven fabric having a basis weight of 180 to 280 g / m ^2. %, And having a characteristic that the waist strength is 8.0 to 20.0 N / cm. Tensile elongation is an important factor in the molding process, and is preferably in the range of 20 to 50%. If it is less than 20%, a portion having a large strain on the side surface of the buttock and the mountain portion is destroyed and a hole is opened. This is not preferable. On the other hand, if the elongation exceeds 50%, the moldability is good, but excessive performance is not preferable.

  The initial tensile elastic modulus is preferably in the range of 1500 to 3000 N / 5 cm / 100%, and if it is less than 1500 N / 5 cm / 100%, the shape of the ridge after pleating and the tension of the nonwoven fabric become weak. On the other hand, if it exceeds 3000 N / 5 cm / 100%, the state of the nonwoven fabric is scattered, and the shape of the crease part of the ridge during pleating is destroyed, which is not preferable. The waist strength is preferably 8.0 to 20.0 N / cm, and if it is less than 8.0 N / cm, the nonwoven fabric is soft even if the initial tensile elastic modulus is within a predetermined range. This is not preferable because it easily causes wrinkle contact. On the other hand, when the waist strength exceeds 20.0 N / cm, the filtration performance of the filter is lowered even if the initial tensile elastic modulus is within a predetermined range. Therefore, having the above characteristics is an important feature of the present invention.

  Examples of the present invention will be described below together with comparative examples.

30% by weight of polyester fiber (melting point: 260 ° C.) with a fineness of 16.7 decitex and a fiber length of 51 mm, 20% by weight of polyester fiber with a fineness of 2.2 decitex and a fiber length of 51 mm, a fineness of 4.4 decitex, a fiber length of 51 mm, Polyester / low-melting polyester composite fiber (melting point of low-melting polyester: 110 ° C.) 50% by weight of coarse layer fiber layer with a basis weight of 81 g / m ² , a fineness of 2.2 dtex and a fiber length of 51 mm polyester / low-melting polyester Composite fiber (melting point of low-melting polyester: 110 ° C.) 100% by weight per unit mass of 63 g / m ² middle layer fiber layer, polyester fiber having a fineness of 0.8 dtex and a fiber length of 51 mm (melting point: 260 ° C.) 50% by weight And a polyester / low-melting polyester composite fiber having a fineness of 2.2 decitex and a fiber length of 51 mm ( After laminating a dense fiber layer with a mass per unit area of 63 g / m ² consisting of 50% by weight (melting point of low-melting polyester: 110 ° C.), needle punching is performed, and heat treatment is performed for 47 seconds with a pin tenter heat treatment machine at 200 ° C. Then, the dense layer surface is brought into contact with a hot roll having a surface temperature of 200 ° C., the rough layer surface side is a roll having a temperature of about room temperature, the clearance between the two rolls is calendered, cooled, and the nonwoven fabric is wound. I took it. Subsequently, the nonwoven fabric was dipped in an acrylate binder and dried at 150 ° C. to give both 25 g / m ² . The obtained nonwoven fabric was a nonwoven fabric having a basis weight of 231 g / m ² and a thickness of 4.9 mm.

30% by weight of polyester fiber (melting point: 260 ° C.) with a fineness of 16.7 decitex and a fiber length of 51 mm, 20% by weight of polyester fiber with a fineness of 2.2 decitex and a fiber length of 51 mm, a fineness of 4.4 decitex, a fiber length of 51 mm, Polyester / low-melting polyester composite fiber (melting point of low-melting polyester: 110 ° C.) 50% by weight of coarse layer fiber layer with a basis weight of 81 g / m ² , a fineness of 2.2 dtex and a fiber length of 51 mm polyester / low-melting polyester Composite fiber (melting point of low-melting polyester: 110 ° C.) 100% by weight per unit mass of 63 g / m ² middle layer fiber layer, polyester fiber having a fineness of 0.8 dtex and a fiber length of 51 mm (melting point: 260 ° C.) 50% by weight And a polyester / low-melting polyester composite fiber having a fineness of 2.2 decitex and a fiber length of 51 mm ( After laminating a dense fiber layer having a basis weight of 63 g / m ² consisting of 50% by weight (melting point of low-melting polyester: 110 ° C.), needle punching is performed, and a pin tenter heat treatment machine at 200 ° C. for 47 seconds. Heat treatment is performed, a hot roll having a surface temperature of 200 ° C. is brought into contact with the dense layer surface, a rough layer surface side is a roll having a temperature of about room temperature, a clearance between both rolls is calendered to 2.5 mm, and the non-woven fabric is cooled. Winded up. Subsequently, the nonwoven fabric was immersed in an acrylate binder and dried at 150 ° C. to give 23 g / m ^{2 in an applied} amount. The obtained nonwoven fabric was a nonwoven fabric having a mass per unit area of 261 g / m ² and a thickness of 5.2 mm.

30% by weight of polyester fiber (melting point: 260 ° C.) with a fineness of 16.7 decitex and a fiber length of 51 mm, 20% by weight of polyester fiber with a fineness of 2.2 decitex and a fiber length of 51 mm, a fineness of 4.4 decitex, a fiber length of 51 mm, Polyester / low melting point polyester composite fiber (melting point of low melting point polyester: 110 ° C.) 50% by weight of coarse layer fiber layer having a basis weight of 69 g / m ² , a fineness of 2.2 dtex, and a fiber length of 51 mm polyester / low melting point polyester Composite fiber (melting point of low-melting polyester: 110 ° C.) 100% by weight Fiber mass for middle layer of 60 g / m ² and polyester fiber (melting point: 260 ° C.) 50% by weight with fineness of 0.8 dtex and fiber length of 51 mm And 50 weight of polyester fiber (melting point: 260 ° C.) having a fineness of 2.2 decitex and a fiber length of 51 mm. % And a fiber layer for a dense layer having a basis weight of 50 g / m ² and a polyester / low melting point polyester composite fiber having a fineness of 2.2 dtex and a fiber length of 51 mm (melting point of low melting point polyester: 110 ° C.) After lamination, needle punching is performed, and heat treatment is performed for 47 seconds with a 200 ° C. pin tenter heat treatment machine, a hot roll having a surface temperature of 200 ° C. is brought into contact with the dense layer surface, and the rough layer surface side is a roll having a temperature of about room temperature. The clearance between the rolls was set to 2.5 mm, calendared, cooled, and the nonwoven fabric was wound up. Subsequently, the nonwoven fabric was immersed in an acrylate binder and dried at 150 ° C. to give 20 g / m ^{2 in an applied} amount. The obtained nonwoven fabric was a nonwoven fabric having a basis weight of 199 g / m ² and a thickness of 4.9 mm.

30% by weight of polyester fiber (melting point: 260 ° C.) with a fineness of 16.7 decitex and a fiber length of 51 mm, 20% by weight of polyester fiber with a fineness of 2.2 decitex and a fiber length of 51 mm, a fineness of 4.4 decitex, a fiber length of 51 mm, Polyester / low-melting polyester composite fiber (melting point of low-melting polyester: 110 ° C.) 50% by weight of coarse layer fiber layer having a basis weight of 100 g / m ² , a fineness of 2.2 dtex and a fiber length of 51 mm polyester / low-melting polyester Composite fiber (melting point of low-melting polyester: 110 ° C.) 100% by weight fiber weight for middle layer of 88 g / m ² , polyester / low-melting polyester composite fiber (low-melting polyester) with fineness of 0.8 dtex and fiber length of 51 mm melting point: for 110 ° C.) 60 wt% dense layer having a basis weight of mass 90 g / m ² consisting of fiber After laminating the layers, needle punching is performed, heat treatment is performed for 47 seconds with a 200 ° C. pin tenter heat treatment machine, a hot roll having a surface temperature of 200 ° C. is brought into contact with the dense layer surface, and the rough layer surface side is at a room temperature. With a certain roll, the clearance between both rolls was set to 2.5 mm, calendared, cooled, and the nonwoven fabric was wound up. Subsequently, the nonwoven fabric was immersed in an acrylate binder and dried at 150 ° C. to give 20 g / m ^{2 in an applied} amount. The obtained nonwoven fabric obtained a nonwoven fabric having a mass per unit area of 278 g / m ² and a thickness of 5.4 mm.

[Comparative Example 1]
30% by weight of polyester fiber (melting point: 260 ° C.) with a fineness of 16.7 decitex and a fiber length of 51 mm, 20% by weight of polyester fiber with a fineness of 2.2 decitex and a fiber length of 51 mm, a fineness of 4.4 decitex, a fiber length of 51 mm, polyester / Low melting point polyester composite fiber (melting point of low melting point polyester: 110 ° C.) 50% by weight of fiber layer for coarse layer with basis weight of 101 g / m ² , polyester / low melting point polyester composite with fineness of 2.2 dtex and fiber length of 51 mm Fiber (melting point of low melting point polyester: 110 ° C.) 100% by weight basis weight 80 g / m ² middle layer fiber layer, fineness 0.8 decitex, fiber length 51 mm polyester fiber (melting point: 260 ° C.) 40% by weight Polyester / low-melting polyester composite fiber with a fineness of 2.2 decitex and a fiber length of 51 mm ( After laminating a dense fiber layer with a mass per unit mass of 79 g / m ² consisting of 60% by weight of a melting point of low-melting polyester: 110 ° C., needle punching was performed, followed by heat treatment for 47 seconds with a 200 ° C. pin tenter heat treatment machine. Then, a hot roll having a surface temperature of 200 ° C. is brought into contact with the dense layer surface, and the coarse layer surface side is a roll having a temperature of about room temperature. The clearance between the two rolls is calendered, cooled, and wound with a nonwoven fabric. I took it. The obtained nonwoven fabric was a nonwoven fabric having a basis weight of 260 g / m ² and a thickness of 5.2 mm [Comparative Example 2].
30% by weight of polyester fiber (melting point: 260 ° C.) with a fineness of 16.7 decitex and a fiber length of 51 mm, 20% by weight of polyester fiber with a fineness of 2.2 decitex and a fiber length of 51 mm, a fineness of 4.4 decitex, a fiber length of 51 mm, Polyester / low-melting polyester composite fiber (melting point of low-melting polyester: 110 ° C.) 50% by weight of coarse layer fiber layer having a weight of 90 g / m ² , polyester fiber having a fineness of 4.4 dtex and a fiber length of 51 mm (melting point: 260 ° C.) 50% by weight, fineness 4.4 decitex, fiber length 51 mm polyester / low melting point polyester composite fiber (melting point of low melting point polyester: 110 ° C.) 50% by weight basis weight mass 70 g / m ² middle layer fiber layer 50% by weight of polyester fiber having a fineness of 2.2 decitex and a fiber length of 51 mm (melting point: 260 ° C.) And a dense fiber layer having a basis weight of 70 g / m ² consisting of 50% by weight of a polyester / low melting point polyester composite fiber having a fineness of 2.2 dtex and a fiber length of 51 mm (melting point of low melting point polyester: 110 ° C.). After that, needle punching is performed, heat treatment is performed for 47 seconds with a 200 ° C. pin tenter type heat treatment machine, a hot roll having a surface temperature of 200 ° C. is brought into contact with the dense layer surface, and the rough layer surface side is a roll having a temperature of about room temperature. The clearance between the rolls was calendered to 2.5 mm, cooled, and the nonwoven fabric was wound up. Subsequently, the non-woven fabric was immersed in an acrylic ester binder and dried at 150 ° C. to give an applied amount of 220 g / m ² . The obtained nonwoven fabric was a nonwoven fabric having a mass per unit area of 252 g / m ² and a thickness of 1 mm.

[Comparative Example 3]
30% by weight of polyester fiber (melting point: 260 ° C.) with a fineness of 16.7 decitex and a fiber length of 51 mm, 20% by weight of polyester fiber with a fineness of 2.2 decitex and a fiber length of 51 mm, a fineness of 4.4 decitex, a fiber length of 51 mm, Polyester / low-melting polyester composite fiber (melting point of low-melting polyester: 110 ° C.) 50% by weight of the coarse layer fiber layer with a mass of 95 g / m ² , polyester fiber having a fineness of 1.3 dtex and a fiber length of 51 mm (melting point: 260 ° C.) 50% by weight and a dense layer having a basis weight of 126 g / m ² consisting of 50% by weight of polyester / low-melting polyester composite fiber having a fineness of 2.2 dtex and a fiber length of 51 mm (melting point of low-melting polyester: 110 ° C.). After laminating the fiber layer, a needle punching process is performed, and a pin tenter heat treatment machine at 200 ° C. is used. Heat-treat for 7 seconds, bring a hot roll with a surface temperature of 200 ° C. into contact with the dense layer surface, roll on the rough layer surface side at room temperature, and make a clearance between the rolls of 2.5 mm, calender and cool The nonwoven fabric was wound up. Subsequently, the nonwoven fabric was immersed in a styrene acrylic binder and dried at 150 ° C. to give 25 g / m ^{2 in an applied} amount. The obtained nonwoven fabric was a nonwoven fabric having a mass per unit area of 268 g / m ² and a thickness of 3.6 mm.

[Comparative Example 4]
30% by weight of polyester fiber (melting point: 260 ° C.) with a fineness of 16.7 decitex and a fiber length of 51 mm, 20% by weight of polyester fiber with a fineness of 2.2 decitex and a fiber length of 51 mm, a fineness of 4.4 decitex, a fiber length of 51 mm, Polyester / low-melting polyester composite fiber (melting point of low-melting polyester: 110 ° C.) 50% by weight of coarse layer fiber layer having a weight of 76 g / m ² , a fineness of 2.2 dtex, and a fiber length of 51 mm polyester / low-melting polyester Composite fiber (melting point of low-melting polyester: 110 ° C.) 100% by weight fiber layer for middle layer of 60 g / m ² , polyester / low-melting polyester composite fiber having a fineness of 1.3 dtex and a fiber length of 51 mm (low melting point: 260 ° C) 50% by weight, fineness 2.2 decitex, fiber length 51 mm polyester / low After laminating a fiber layer for a dense layer having a basis weight of 50 g / m ² consisting of 50% by weight of a melting point polyester composite fiber (melting point of low melting point polyester: 110 ° C.), needle punching is performed, and a pin tenter heat treatment at 200 ° C. Heat treatment with a machine for 47 seconds, a hot roll having a surface temperature of 200 ° C. is brought into contact with the dense layer surface, the coarse layer surface side is a roll having a temperature of about room temperature, and the clearance between both rolls is calendered to 2.5 mm, Cooled and wound up the nonwoven fabric. The obtained nonwoven fabric was a nonwoven fabric having a mass of 186 g / m ² and a thickness of 3.2 mm.

Next, the contents of each of the above Examples and Comparative Examples are summarized and described in Attached Table 1, and the filtration performance and moldability of the obtained nonwoven fabrics were compared. The results are shown in Appendix 2. Each item in the table was evaluated based on the following explanation and also based on the measurement method and the test method.
(A) Mass per unit area: g / m ²
A size of 50 cm × 50 cm is cut out, the weight at that time is measured, and converted to a weight per 1 m ² .
(B) Thickness: mm
A size of 15 cm × 15 cm is cut out, an initial load of 15 g / cm ² is applied, the heights of the four corners are measured, and the average value is shown.

Strength measurement The measurement was performed under the following conditions using Toyo Bald Inn 500 kg Tensilon.

Sample: 200 mm, Sample width: 15 mm
Measurement length: 150mm, Sample width: 15mm
Tensile speed: 200 mm / min
n = 5
Initial tensile modulus N / 5cm / 100%
The strength of the sample was measured and calculated from the initial slope of the strength elongation curve.

Breaking strength %
The strength of the sample was measured and calculated from the elongation at break of the strength-elongation curve.

Waist strength: N / cm
To prepare the sample, cut out a rectangle with a length of 80 mm and a width of 65 mm, and fold it into half (40 mm) uniformly from the center of the length with the rough surface as the front. Place the sample on the sample setting table, fold it up, and place a compression jig (10 mmφ) at the apex center of the peak with a V-shaped width of 40 mm. In the waist strength test, 100 kg of Tensilon manufactured by Toyo Bald Inn Co., Ltd. is used, and the waist strength is 10 mφ. The measurement is performed 5 times (n = 5), and the average value is shown. The unit is shown in terms of N.

Evaluation of Filtration Performance Dust collection performance was tested based on the JIS D1612 automotive air cleaner test method. However, a disk filter medium having an effective area of 1000 cm ² was used as an element of the test air cleaner. Experimental conditions, the filter medium passing apparent airflow and 40 cm / sec, in dust eight powder specified in JIS Z8901, concentration was 1 g / m ^3, relative Filtration area 1000 cm ³ during cleaning efficiency is increased resistance 300mmAq The collection efficiency was assumed.

Evaluation item Ventilation resistance ΔP (Pa) Initial pressure difference before and after sample setting Cleaning efficiency η (%) Dust collection efficiency at increased resistance of 300 mmAq Dust retention amount DHC (g / 0.1 mm ² ) Dust retention amount at increased resistance of 300 mmAq Formability evaluation Sheet material is folded and pleated to form a corrugated shape, then a width narrower than the sample width is applied to the thermal outer frame, and the lower part of the thermal mold is attached to the protrusion provided on the outer frame. The recesses were fitted and fixed, the position was determined, and heat fusion was performed to fix both sides and the outer frame at the same time. The molded product was evaluated as follows.

There is no tearing in the molded part, and the state of the heel is good. ○
There is no tear in the molded part, but there are a little more wrinkles. △
There are tears in the molding part, and there are many defects. ×

上記表２より本発明に係る不織布は比較不織布に比し、塵埃保持量が多く、捕集効率に優れていると共に、成形性においても極めて優れていることが理解される。

From Table 2 above, it is understood that the nonwoven fabric according to the present invention has a large amount of dust retention, excellent collection efficiency and extremely excellent moldability as compared with the comparative nonwoven fabric.

Claims (5)

A non-woven fabric formed by laminating the web of each of the rough layer portion, the middle layer portion, and the dense layer portion including the heat-adhesive composite short fiber, needle processing, subsequently heating and heat bonding treatment, and then binder processing, The nonwoven fabric has a basis weight of 180 to 280 g / m ² , a tensile elongation of 20 to 50%, an initial tensile elastic modulus of 1500 to 3000 N / 5 cm / 100%, and a waist strength of 8.0 to 20.0 N / cm. A filter nonwoven fabric characterized by having properties.   The coarse layer portion is composed of a mixed fiber of a high melting point short fiber and a heat-bonding composite short fiber, the fiber mixing ratio is 30/70 to 50/50, the high melting point short fiber is a high melting point resin, and the heat bonding property The filter nonwoven fabric according to claim 1, wherein the composite short fiber is a core-sheath composite of a low melting point resin of polyester and a high melting point resin, and the fineness of each short fiber is 6.0 to 20.0 dtex. The middle layer portion is composed of 100% by weight of a heat-adhesive composite short fiber, the basis weight is 50 to 90 g / m ² , and the fineness of the short fiber is in the range of 1.0 to 10.0 decitex (dtex). The filter nonwoven fabric according to 1 or 2.   The dense layer portion is composed of a mixture of high melting point short fibers and heat-bondable composite short fibers, the fiber mixture ratio is 30/70 to 50/50, and the fineness of the short fibers is 0.8 to 6.0 dtex ( The filter nonwoven fabric according to claim 1, 2 or 3, which is in a range of dtex). Filter nonwoven fabric according to any one of claims 1 to 4 attached amount of the binder is 15 to 30 g / m ^2.