JP2006069033A - Composite nonwoven fabric and air filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite nonwoven fabric which is high in pleat folding properties, makes the deformation of pleats by wind pressure difficult when used as an air filter, and can prevent the block of the filter by deformation. <P>SOLUTION: Composite strands (6) comprising at least two thermoplastic resins different in melting point in which the resin having the lowest melting point occupies at least 40% of fiber surfaces are arranged approximately in parallel to the width direction of a base cloth such as a heat-bonded nonwoven fabric and bonded to the base cloth while being extended in the length direction of the base cloth, and a melt-blown nonwoven fabric of thick composite fibers (4) comprising at least two thermoplastic resins different in melting point in which the resin having the lowest melting point occupies at least 40% of fiber surfaces is accumulated on the composite strands (6) and bonded/integrated to/with the base cloth to obtain the composite nonwoven fabric high in pleat folding properties. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a composite nonwoven fabric that is useful for applications such as air filters such as air conditioning filters for buildings, dust-absorbing curtains, and mask materials, and that is easy to fold pleats, and an air filter that is not easily deformed by wind pressure or the like when folded pleats. .

  Conventionally, as an air filter, a melt blown nonwoven fabric composed of a composite fiber composed of two different components has been proposed. For example, in Japanese Patent Application Laid-Open No. 2001-98453 (Patent Document 1), a sheath-core type composite fiber of polybutene-1 and polypropylene is spun onto a base fabric by a melt blow method, and in an atmosphere at or above the melting temperature of polybutene-1. An air filter that has been charged and then rapidly cooled under electric power has been proposed.

  On the other hand, as a pleated folded filter medium, for example, Japanese Utility Model Laid-Open No. 1-156715 (Patent Document 2) includes a nonwoven fabric made of synthetic fibers having an average fiber diameter of 0.5 to 20 μm manufactured by a melt blow method or a jet spinning method. A filter medium suitable for a liquid cartridge filter in which a spacer and a fiber constituting a nonwoven fabric are bonded has been proposed.

JP 2001-98453 A Japanese Utility Model Publication No. 1-156715

However, the conventional nonwoven fabric described above has the following problems. Since the conventional melt blown nonwoven fabric is manufactured so as to be laminated as uniformly as possible on the conveyor belt by hot air from a nozzle, the resulting nonwoven fabric is smooth and easily becomes a paper-like one without thickness. Such a melt blown nonwoven fabric is difficult to be applied to a gear roll of a pleat folding machine and has poor workability. Moreover, the bulk with respect to the fabric weight of a nonwoven fabric was small, and when trying to raise the collection efficiency as a filter, there was a tendency for pressure loss to become large easily. Furthermore, electret non-woven fabrics that are all composed of polyolefin resin fibers have high insulation resistance, and the basis weight of the non-woven fabric is increased to increase the thickness. If the basis weight exceeds 90 g / m ² , the penetration of the electric field suddenly becomes poor. Thus, the electret imparting effect is drastically reduced, and it may be difficult to obtain an electret filter with high collection efficiency.

  In addition, when the conventional meltblown nonwoven fabric is pleated in the longitudinal direction of the nonwoven fabric, if a reinforcing material is not used, especially when the pleat folding width exceeds 30 mm, filtration at a higher flow rate than the expected flow rate cannot withstand wind pressure. There was a problem that the pleats were deformed and the filtration was partially biased. For this reason, meshes and integrally formed nets are used as the reinforcing material, but there is a problem in that weft yarns or yarns extending in the width direction have an adverse effect on pleat folding and cannot be neatly folded.

  On the other hand, the filter medium proposed in Patent Document 2 is provided with a spacer, so that when the pleats are folded, the filter mediums do not come into contact with each other at the convex portion, thereby preventing adhesion of the filter mediums or generation of dead space. I'm trying to do it. However, the reinforcing effect of the filter medium is low, and when it is used for a liquid cartridge filter with a fold width of about 15 mm, there is no problem, but when it is used for a relatively wide fold width such as an air filter. There was a problem.

  The present invention is reinforced in the length direction of the nonwoven fabric, and in a reciprocating or rotary type pleated folding machine, has at least a pleat foldability enough to be fed out by a blade or a protrusion, and particularly when used as an air filter, An object of the present invention is to provide a composite nonwoven fabric that can withstand wind pressure and is difficult to deform a pleat fold and can prevent a filter from being blocked by deformation.

  The composite nonwoven fabric of the present invention is composed of a base fabric and two or more thermoplastic resins having different melting points, and 40% or more of the fiber surface has the lowest melting point among the thermoplastic resins (hereinafter referred to as low melting point component S1). And a component having a lowest melting point among the thermoplastic resins (hereinafter referred to as a low melting point component M1). The melt-blown nonwoven fabric composed of the composite fibers occupying in this order is bonded and integrated in this order, and the composite strands are arranged substantially parallel to the width direction of the base fabric and are arranged in the length direction of the base fabric. It extends and is bonded to the base fabric with a low melting point component S1, and the melt blown nonwoven fabric is bonded to the base fabric with a low melting point component M1 of a composite fiber.

  The air filter of the present invention is characterized in that the composite nonwoven fabric is pleated with a pleat folding width of 30 mm or more.

In the composite nonwoven fabric, it is preferable that the melt-blown nonwoven fabric has convex portions formed on the surface of the nonwoven fabric by a fiber lump in which a plurality of the fibers constituting the composite nonwoven fabric are partially aggregated and bonded. Specifically, a heat-bonding nonwoven fabric is used as the base fabric, the composite strand is reinforced with the composite strand, and the composite strand is covered with a meltblown nonwoven fabric to prevent peeling of the composite strand. It is preferable that the composite strand and the heat-bonding nonwoven fabric are further bonded to each other with the low melting point component M1. Further, in the melt blown nonwoven fabric, a plurality of fiber lumps in which a plurality of constituent fibers are partially aggregated and fused are present in the nonwoven fabric to form convex portions on the surface of the nonwoven fabric. It is preferable that the bulkiness (thickness μm / weight per unit area g / m ² ) at which the gap between the constituent fibers is widened and the fiber density is lowered from the non-existing portion is 8 or more.

  The fiber diameter (DS: μm) of the composite strand is preferably 100 <DS <2000. Further, the average fiber diameter (DM: μm) of the composite fiber is 0.3 <DM <200, and the fiber diameter (DS: μm) of the composite strand is 100 <DS <2000, which constitutes these. Each of the plurality of thermoplastic resin components has a melting point (Tm: ° C.) of 60 ≦ Tm <270, a melt flowable melt flow rate (MFR: g / 10 minutes; a measurement temperature is 230 ° C. when Tm ≦ 200, When 200 <Tm, it is preferably a thermoplastic resin in which 290 ° C., the load is 2.169 Kg, and JIS-K-6760 is in conformity with 5 <MFR <200.

The low melting point component S1 of the composite strand is at least one resin selected from a polybutene-1 resin and a high-density polyethylene resin, and the other thermoplastic resin component is preferably polypropylene. Furthermore, the low melting point component M1 of the composite fiber is a polybutene-1 resin having a density (ρ: g / cm ³ ) of 0.905 ≦ ρ <0.930 and a melting point (Tms: ° C.) of 115 <Tms <130. The low melting point component S1 of the composite strand is at least one resin selected from the polybutene-1 resin and the high density polyethylene resin, and the other thermoplastic resin component is a monomer such as polypropylene and polymethylpentene-1. The polyolefin resin is preferably a polyolefin resin having about 3 or more carbon atoms.

  Further, in the present invention, a surface nonwoven fabric composed of fibers having a fiber diameter of 5 μm or more is disposed on at least one surface of the composite nonwoven fabric, and at least one of the low melting point component S1 and the low melting point component M1 constituting the composite nonwoven fabric. It is preferable that they are bonded and integrated. Specifically, the surface non-woven fabric composed of fibers having a fiber diameter of 5 μm or more is arranged on the surface where the composite strand is bonded to the melt-blown non-woven fabric composed of a composite fiber composed of a combination of polybutene-1 and polypropylene. It is preferable that it is a composite nonwoven fabric integrated by thermal bonding with a low melting point component of at least one of the composite fibers and / or composite strands.

The composite nonwoven fabric preferably has a basis weight of the base fabric and the melt blown nonwoven fabric of 30 to 400 g / m ² and a basis weight of the composite strand of 50 to 1000 g / m ² . If the basis weight of the base fabric is 10 g / m ² or more, it is sufficient to maintain the toughness of the composite nonwoven fabric of the present invention. In order to enhance the adsorption effect, it is also preferable to use one having a basis weight of ^{20 to} 100 g / m2.

  The base fabric is preferably a heat-bonded nonwoven fabric. Furthermore, the base fabric is preferably a spunbonded nonwoven fabric composed of fibers made of one or more resins among a homopolymer mainly composed of propylene and a copolymer mainly composed of propylene.

  Further, in the composite nonwoven fabric, the base fabric is a heat-bonded nonwoven fabric made of polyolefin resin, and fibers made of polyester resin such as polyethylene terephthalate resin are entangled and integrated on one side of the heat-bonded nonwoven fabric, A non-woven fabric in which fibers are bonded with an adhesive resin is arranged, and one surface on which the thermo-bonding non-woven fabric is located is a state in which fibrous fixed matters melted by heat caused by the thermo-bonding non-woven fabric are scattered or the non-woven fabric It is preferable that the melt-blown nonwoven fabric and / or the composite strand is bonded and integrated on the heat-bonding nonwoven fabric surface of the nonwoven fabric maintaining the shape. The adhesive resin is preferably a resin that does not contain formalin, such as an acrylic resin, a vinylidene chloride resin, and an epoxy resin.

  Furthermore, the melt blown nonwoven fabric is a composite fiber composed of the polybutene-1 resin and the polypropylene resin, and an average fiber diameter (DM2) is further formed on the melt blown nonwoven fabric having an average fiber diameter (DM1: μm) of 10 <DM1 <200. : Μm) is preferably a melt blown nonwoven fabric composed of composite fibers of 0.3 <DM2 <20, and the layers of the nonwoven fabrics are preferably bonded and integrated by the low melting point component M1 of the composite fibers.

The one preferred embodiment of the composite nonwoven fabric, the basis weight excluding the weight per unit area of the composite strand 30 g / m ² or more, and more preferably a composite nonwoven is 60~400g / m ^2. The basis weight of the composite strand is 50 to 1000 g / m ² , more preferably 100 to 600 g / m ² .

  The composite nonwoven fabric of the present invention is preferably formed by electret processing. Furthermore, it is preferable that the composite nonwoven fabric is electret-processed, and at least composite fibers made of polybutene-1 resin and polypropylene resin are electretized.

  The composite nonwoven fabric of the present invention is preferably formed by pleat folding in the length direction of the nonwoven fabric.

  One of the preferred embodiments of the present invention is that the thermal bonding nonwoven fabric and the surface nonwoven fabric are composed of polypropylene fibers or polyethylene fibers to which a hydrophilic chemical substance such as a surfactant is not attached. A composite nonwoven fabric composed of the polybutene-1 resin and the polypropylene resin, which is occupied on both sides, and integrated by thermal bonding with at least a low melting point component of the composite fiber constituting the composite nonwoven fabric. Is electretized.

  Moreover, one of the preferable aspects of this invention is the composite fiber nonwoven fabric which consists of the said polybutene-1 resin and a polypropylene resin, A heat-bonding nonwoven fabric and / or a surface nonwoven fabric are the polypropylene fiber and / or fiber surface whose fiber diameter is 5 micrometers or more. A heat-bonded hydrophilic fiber non-woven fabric composed of a heat-adhesive fiber made of polyolefin resin and rayon fiber, and a composite non-woven fabric bonded and integrated by the low melting point component M1 of the composite fiber constituting the melt-blown non-woven fabric It is.

  One of the preferred embodiments of the present invention is a composite fiber comprising the composite nonwoven fabric in which a surface nonwoven fabric composed of fibers having a fiber diameter of 5 μm or more is disposed on at least one surface of the composite nonwoven fabric composed of the polybutene-1 resin and the polypropylene resin. A composite nonwoven fabric bonded and integrated with a low melting point component M1, wherein the surface nonwoven fabric is a laminated nonwoven fabric composed of three layers of a rayon fiber layer, an activated carbon fiber layer, and a polypropylene spunbond nonwoven fabric layer, This is a composite nonwoven fabric in which the composite nonwoven fabric is bonded and integrated by the low melting point component M1 of the composite fiber and is electretized.

  Moreover, one of the preferable aspects of this invention is the composite nonwoven fabric in which the fiber which comprises nonwoven fabrics other than a melt blown nonwoven fabric is flame-retarded.

  The composite nonwoven fabric of the present invention is formed by bonding and integrating a melt-blown nonwoven fabric made of composite fibers using a thermoplastic resin that is easy to fuse and a composite strand using a thermoplastic resin that is easy to fuse, so that each layer is strong. The non-woven fabric is reinforced by being bonded. As a result, it is possible to obtain a filter material that has a high pleat shape retaining property when folded into pleats and can withstand high wind pressure. In addition, the composite strand has a function of giving a bulk that can secure at least a pleat folding operation enough to be fed out by a blade or a protrusion in a reciprocating or rotary pleat folding machine, and after the pleat folding, The rigidity of the nonwoven fabric can be given, the shape workability with the pleated fold filter can be improved, and wind pressure deformation can be prevented.

  The composite nonwoven fabric of the present invention can increase the apparent thickness of the nonwoven fabric by forming convex portions on the nonwoven fabric surface with a fiber lump in which a plurality of fibers constituting the melt blown nonwoven fabric are partially aggregated and bonded. A nonwoven fabric having a thickness that could not be achieved with a conventional single-fiber meltblown nonwoven fabric can be obtained, and can be pleated without any problem even with a known pleat folder.

  The air filter using the composite nonwoven fabric of the present invention has high pleat shape retention, and can withstand high wind pressure even when pleated at a pleat folding width of 30 mm or more.

  The conventional melt-blowing method is based on a method in which a molten resin is ejected from a nozzle in a bowl shape and accumulated as fibers on a conveyor, and then the fibers are thermally bonded to form a melt-blown nonwoven fabric. The inventors of the present invention positively generate a fiber lump in which a plurality of adjacent fibers are partially brought into contact with each other until the fibers are agglomerated, entangled and thermally bonded, from the time when the molten resin is ejected to the conveyor. In addition, the above-mentioned problems can be solved in a pleated fold filter having a narrow pleat fold width by obtaining a new melt-blown nonwoven fabric by realizing the partial and local uneven distribution thereof. However, these measures may not be sufficient for further high flow rate filtration and for use in pleated filters with a larger folding width.

  On a base fabric such as a nonwoven fabric, as a reinforcing material and a thick material at almost regular intervals in the width direction of the pleats, a very thick composite fiber-like composite strand having a self-heat-adhesive ability is thermally bonded, and it is covered on the above, and is described above. During the period from the injection of the molten resin to the fall of the conveyor, the adjacent fibers are partially brought into contact with each other, and fibers are aggregated, entangled and heat-bonded fiber mass is actively generated. By electrifying the melt-blown non-woven fabric composed of composite fibers that have been localized locally, and by firmly bonding and integrating with the base fabric by thermal bonding of the low melting point component M1 of the composite fibers, electret processability To obtain a composite nonwoven fabric suitable for a pleated folding filter that does not have a significant effect, has sufficient thickness to be folded with a pleat folding machine, and has increased rigidity in the width direction of the pleat. Was Tsu. That is, the composite nonwoven fabric of the present invention comprises a base fabric and two or more thermoplastic resins having different melting points, and 40% or more of the fiber surface has the lowest melting point among the thermoplastic resins (hereinafter referred to as a low melting point). Component composed of a composite strand composed of component S1) and two or more thermoplastic resins having different melting points, and 40% or more of the fiber surface has the lowest melting point among the thermoplastic resins (hereinafter referred to as low melting point component) M1) is a composite nonwoven fabric in which melt-blown nonwoven fabrics composed of composite fibers are bonded and integrated in this order, and the composite strands are arranged substantially parallel to the width direction of the base fabric and the length of the base fabric The melt-blown non-woven fabric is bonded to the base fabric with a low-melting-point component M1 of a composite fiber. Here, “substantially parallel” refers to a state in which the composite strands are substantially aligned in parallel, and includes a concept in which the composite strands meander slightly.

  Of course, after pre-bonding the composite strand, the fiber mass is formed by aggregating and entangled the fibers by partially contacting multiple adjacent fibers as the original filter function material on the other side of the base fabric. Needless to say, it is more preferable to apply a melt-blown nonwoven fabric that is positively generated and partially or locally unevenly distributed.

  Melt-blown nonwoven fabric as a filter function material has many fiber clusters scattered in the nonwoven fabric, the thickness of the nonwoven fabric is increased by that amount, and the periphery of the fiber cluster is a gap between the fibers that are collected. It is preferable that the structure make a large. Furthermore, by accumulating fibers from above, fiber accumulation is actively performed to reduce the density by creating a three-dimensional accumulation condition in the thickness direction, and as a result, the inter-fiber gap is widened to improve the fluid permeability. Can do. That is, the effect of reducing the pressure loss can be produced and the bulk can be increased.

The present invention uses a heat-bonded nonwoven fabric as a base fabric, and heat-bonds a composite strand which is a composite fiber composed of two or more thermoplastic resin components having different melting points, and the low melting point component occupies 40% or more of the fiber surface. In order to prevent the composite strand from peeling off, it is composed of at least 10 g / m ² of two or more thermoplastic resin components having different low melting points, and the low melting point component occupies 40% or more of the fiber surface. Covered with a meltblown non-woven fabric composed of a composite fiber with the same fiber diameter as a staple, and further bonded to the composite strand and the base fabric with the low melting point component of the composite fiber to enhance the peel strength of the composite strand. A composite nonwoven fabric is preferred.

  The function of the composite strand is to give a bulk that can secure at least the bulk in the pleat folding operation so that it can be fed out by a blade or a protrusion when the pleat is folded by a reciprocating or rotary pleat folding machine, in other words, in the pleating folder After the pleat folding, the composite nonwoven fabric was given the rigidity of the nonwoven fabric in the pleat width direction, and in particular, the shape processing property of the pleated filter was improved and the wind pressure deformation was prevented. Is.

  Further, the composite strand can be sufficiently thermally bonded to the base fabric, but the heat-bonded portion may be weakened due to the heat of the strand, and when pleated, particularly when a reciprocating pleat folding machine is used, Folding impact may cause the thermobonding nonwoven fabric to break at this part, or the strands may peel off, covering these bonded composite strands and covering them with at least a low weight meltblown nonwoven fabric to avoid these phenomena It is. When using a heat-bonded non-woven fabric as the base fabric, the part that is bonded to the composite strand is not a line, but the surface is bonded to the composite strand as a surface, thereby reducing local impact on the heat-bonded non-woven fabric. It is most preferable to avoid peeling and breaking.

The upper surface of the melt-blown nonwoven fabric covering the composite strand, or the heat-bonded nonwoven fabric surface on the opposite side, is made of two or more thermoplastic resins with different melting points as a filter material, and the low melting point component is 40% or more of the fiber surface A melt-blown nonwoven fabric comprising a composite fiber that occupies a plurality of fiber bundles in which a plurality of constituent fibers are partially agglomerated and fused to form a convex portion on the nonwoven fabric surface, A meltblown nonwoven fabric having a bulkiness (thickness μm / weight per unit g / m ² ) of 8 or more, in which the periphery of the fiber lump has a gap between constituent fibers widened from the part where the fiber lump is not present and the fiber density is reduced. A composite nonwoven fabric that is sprayed and laminated is preferred.

  The composite fibers and composite strands constituting the melt blown nonwoven fabric are made of two or more thermoplastic resins having different melting points. For example, two components as shown in FIG. It is preferable that the fiber has a cross-sectional structure like a three-layer type separated into two by components and the low melting point component occupies most of the fiber surface. Further, a multi-core type, a three-layer type, and a divided type such as a mandarin orange type or a windmill type may be used in which the fiber cross section obtained by dividing one component into at least a plurality of components and other components. The fiber shape is basically a circular shape such as a circle or an ellipse, but may be an irregular shape with a corner. There may also be fibers having cavities such as hollows in the fibers.

  As the thermoplastic resin for forming the composite fiber and the composite strand, those having a melt viscosity for producing a general staple composite fiber may be used, and the melt flowable melt flow rate (MFR: g / 10 min; measurement temperature). Is 230 ° C. when Tm ≦ 200, 290 ° C. when 200 <Tm, the weight is 2.169 Kg, and conforms to JIS-K-6760), and is preferably a thermoplastic resin with 5 <MFR <200. The composite fiber uses a thermoplastic resin having such melt fluidity, and the adjacent fibers of the composite fiber spun from the nozzle are partially brought into contact with each other in the air while being ejected, so that the fiber in the structure. A meltblown nonwoven fabric with lumps can be formed.

  The average fiber diameter (DM: μm) of the composite fiber obtained by adjusting to the MFR is preferably 10 <DM <200. Of the composite fibers produced by the melt-blowing method, in a nonwoven fabric in which a plurality of nonwoven fabrics having different fiber diameters are laminated, the average fiber diameter (DM1: μm) of the composite fibers is 10 <DM1 <200. Further, a melt blown nonwoven fabric composed of composite fibers having an average fiber diameter (DM2: μm) of 0.3 <DM2 <20 is disposed, and each nonwoven fabric layer is bonded and integrated by a low melting point component M1 of the composite fibers. preferable. The composite fiber having an average fiber diameter of 0.3 <DM2 <20 is a melt flow rate melt flow rate (MFR: g / 10 minutes) of each thermoplastic resin used, and the measurement temperature is 230 ° C., 200 when Tm ≦ 200. <At 290 ° C. when Tm, the weight is 2.169 Kg, in accordance with JIS-K-6760) can be obtained by using a thermoplastic synthetic resin in which 30 <MFR <800. In particular, DM2 is preferably 5 μm or less.

  In the step of bringing adjacent fibers of the composite fiber spun from the nozzle into contact with each other partially in the air during ejection to generate a mass of fibers that are partially and locally unevenly agglomerated, entangled and fused and bonded. The distance between the nozzle discharge holes (distance between the centers of the circular discharge holes) is about 3 mm, which makes it difficult to make the fibers adjacent to each other between the heights of about 5 to 20 cm up to the conveyor. there were. Therefore, the present inventors can create a nozzle with many discharge holes and generate a lump of fibers that are agglomerated, entangled and fused and bonded intentionally by setting the discharge hole interval to less than 1.5 mm. It was. That is, when manufacturing a thick fiber nonwoven fabric with a large amount of agglomerated entangled fusion bonded fibers, it is better to increase the discharge rate and slightly reduce the hot air flow rate. Can be achieved by reducing the discharge rate and increasing the hot air flow velocity. This utilizes the ballast effect of the resin. The composite fibers spun in this way are substantially continuous, and a plurality of them are partly fused to form a fused part, and are continued as individual composite fibers.

  The fiber diameter of the composite fiber varies between the fused part and the non-fused part, the thick part is generally less than 200 μm, and the fact that it is substantially continuous means that the fiber is thousand for some individual reason. Unless it is cut, it means that the production condition is not intended to be cut.

  By producing a melt blown nonwoven fabric in this way, a nonwoven fabric having a thickness increased by 20 to 100% compared to the case where a melt blown nonwoven fabric having the same basis weight is produced using the same thermoplastic resin by the conventional melt blow method. Can do. In addition, in this invention, the thickness of the nonwoven fabric was measured by JISL-1913-6.1.2A method.

  In the present invention, it is preferable to use a resin having a high viscosity rather than a thermoplastic resin having a high flow (low viscosity), and it is convenient to set the MFR of the resin to be used to be less than 200 g / 10 minutes. In this respect, the direction may be less than 5 g / 10 minutes, but fibers having a fiber diameter of 5 μm or less are difficult to make. In this case, it is preferable to use a combination of high flow resins as described above.

  The melting point (Tm: ° C.) of the thermoplastic resin is the low melting point of the resin that covers 40% or more of the fiber surface (the melting point is Tms: ° C.) in forming a fiber mass that is agglomerated, entangled and fused and bonded. It is preferable that the range is 60 ≦ Tms <170. If the melting point is less than 60 ° C., it is not preferable because it is too fused and difficult to control. On the other hand, if the melting point is 170 ° C. or higher, the combination with the thermoplastic resin as the core component of the fiber is limited, which is not preferable. The melting point of the core component thermoplastic resin (whose melting point is Tmc: ° C.) is not preferable because it has a temperature restriction of the melt blow equipment used. It is appropriate that the temperature is less than 270 ° C. in the practical range. The relationship between the resin covering the majority of the fiber surface (the melting point is Tms: ° C.) and the melting point of the core component resin is preferably Tms + 20 ≦ Tmc.

  The thermoplastic resin used for the composite strand may have the same specifications and contents as the composite fiber, but is preferably a polybutene-1 resin or a high-density polyethylene resin, particularly considering the reinforcing effect and pleat foldability. The composite strand can be easily manufactured from a composite nozzle having nozzle holes formed at a pitch of 3 to 10 mm while being thermally bonded to a meltblown nonwoven fabric or a surface nonwoven fabric under a natural flow or a weak jet flow. When the crossing angle is given to the conveying direction, the composite strands can be easily arranged at a narrower pitch interval. In order to arrange the composite strands substantially in parallel, the non-woven fabric to be thermally bonded is preferably bonded while being moved at a speed of at least 10 m / min, and particularly preferably pressed with a pressure roll.

  The thermal bonding referred to in the present invention means that a low melting point thermoplastic resin is heated to a melting point or higher and melts and bonds, but when the heating temperature is low, the low melting point component maintains the shape of the fiber surface. Fusing to adjacent fibers in contact. As the heating temperature becomes higher than the melting point, the low melting point component is completely melted and aggregates at the bonding point, and the adjacent fibers covering the bonding point are more firmly bonded and integrated.

  Another feature of the present invention is that, as described above, the melt viscosity of the thermoplastic resin used matches the viscosity range of the resin when staple fibers are produced from the same resin. This is because the main purpose of the nonwoven fabric of the present invention is to form a nonwoven fabric using finer fibers that are subject to various limitations in the nonwoven fabric forming process such as a roller card in the case of staple fibers. In particular, in the case of staple fibers and multifilaments, the fusion of fibers during spinning is fatal, but this disadvantage is used as an advantage, and composite fibers containing a resin that is easily fused and bonded in fiber production as a sheath component are directly nonwoven fabrics. The main purpose is to make it easier.

  Therefore, unlike conventional melt-blown nonwoven fabrics, we are not aiming for finer fineness using low-viscosity resin, but rather creating nonwoven fabrics consisting of fibers with the characteristics of stiffness and stiffness of staple fibers. The resin used in the present invention has the same melt viscosity as that for producing staple fibers. However, if the melting point of the resin used is too high, the conveyor just below the nozzle is overheated, which is not preferable for forming a nonwoven fabric. This is different from the case of melt spinning the fiber, and there are restrictions on the equipment, and the temperature of the hot air used cannot be raised without darkness. If there are no restrictions, higher temperatures, for example 350 ° C., are possible.

  Except for the case of obtaining the thinness in the case of lamination, the melt fluidity of the resin used in the present invention is in the range of 5 to 200 g / 10 minutes when expressed in terms of the melt flow rate, and the measurement temperature is 230 ° C. Therefore, the melt fluidity at the melt temperature at the time of actual melt spinning does not always match. The melt fluidity preferred for melt spinning varies depending on the resin, and the most preferred melt fluid state of polyethylene terephthalate or polymethylpentene is around 100 g / 10 minutes, and polypropylene is lower than this.

  When further laminating a composite fiber nonwoven fabric layer for which thinness is required on a meltblown nonwoven fabric, thin composite fibers, that is, composite fibers having an average fiber diameter (DM2: μm) of 0.3 <DM2 <20 are used. Melt flow melt flow rate of thermoplastic resin (MFR: g / 10 min; measurement temperature is 230 ° C. when Tm ≦ 200, 290 ° C. when 200 <Tm, weight is 2.169 Kg, JIS-K-6760 However, it is preferable to use a thermoplastic synthetic resin in which 30 <MFR <800.

  For the above reasons, the main thermoplastic resin used in the present invention can be used conveniently if the resin used in the conventional staple fiber is devised, except for the case where fineness is required. Although not mentioned, thermoplastic resins having a melting point of 60 to 270 ° C. include polyolefin resins, polyester resins including low melting point ester copolymers and aliphatic polyesters, polyamide resins such as polyamide and polyimide, polycarbonate resins and melting points. Thermoplastic elastomer resins that have been read in terms of the flow start temperature can be conveniently used, including mixtures thereof, modified resins by polymer alloy, graft polymerization, low temperature plasma treatment, and the like. In addition, if the melting point is 60 ° C. or higher, for example, UCC microbial disintegrating polyester TONE (trade name) having a melting point of 60 ° C. is devised for cooling after it is made into a nonwoven fabric, but it is conveniently used in the present invention. . When obtaining the fineness, it is exactly the same except for melt fluidity.

  In particular, when the composite nonwoven fabric of the present invention is used as an electret nonwoven fabric, the composite fiber and the composite strand are preferably a polyolefin resin, and the electret material is particularly preferably a polybutene-1 resin. Polybutene-1 resin is a specific resin whose crystal form changes over time from a soft state to a hard and brittle form, but can be spun as a composite fiber with a polypropylene resin. Furthermore, the exclusion of low melting point resins is a practical problem for nonwoven fabrics and has no other reason. The polypropylene resin referred to in the present invention includes a copolymer such as ethylene, and the polybutene-1 resin also limits the density and melting point. However, the polybutene-1 resin having an excess of butene-1 as much as possible is an electret. It is a preferable meaning as a material and is not limited depending on the application. In particular, as a resin that is easily fused between fibers, a resin that is a copolymer such as ethylene or propylene or an amorphous resin and exhibits flexibility under heating such as semi-melting is applicable. Further, propylene-rich ethylene-propylene copolymer, ethylene-octene copolymer, low density polyethylene and the like are preferably used.

The melt blown nonwoven fabric for the purpose of the filter of the present invention specifically comprises a composite fiber composed of two or more thermoplastic resin components having different melting points and the low melting point component M1 occupying most of the fiber surface. A nonwoven fabric produced by the melt-blowing method, wherein a plurality of fiber lumps in which a plurality of constituent fibers are partially aggregated and fused exist in the nonwoven fabric to form convex portions on the surface of the nonwoven fabric. A composite non-woven fabric using a melt blown non-woven fabric having a thickness (μm) / weight per unit area (g / m ² ) of 8 or more in which the gap between the constituent fibers is widened and the fiber density is lower than the portion where no fiber lump exists. It is preferable that

  In this case, the fiber mass is intentionally produced regardless of the fineness by examining the equipment and the fiberization process in the melt-blowing method, rather than agglomerated and thermally bonded fiber mass because it is a thick fiber. However, the use of a resin that is easily heat-bonded as a sheath component only makes it easy to achieve the object, and if devised, fibers using a polyethylene resin as the sheath component can be similarly produced. For low-pressure loss filter applications, a layer composed of fibers thicker than an average fiber diameter of 10 μm (thick composite fiber layer) and a layer composed of fibers thinner than an average fiber diameter of 20 μm mainly having a filter function (fine composite fiber layer) A nonwoven fabric composed of at least two layers is convenient. Of course, the fibers constituting the thick composite fiber layer are naturally thicker than the fibers constituting the fine composite fiber layer.

The melt blown cloth can be obtained by peeling off the melt belt directly from the nozzles onto the conveyor and peeling it from the conveyor belt at the outlet. At this time, if a composite fiber is melt blown on a conveyor while supplying a base fabric, for example, a thin heat-bonded nonwoven fabric such as a spunbond nonwoven fabric in advance, it is convenient to smoothly peel the nonwoven fabric from the conveyor belt. In addition, since the fibers constituting the meltblown nonwoven fabric are not stretched and the oriented crystallization of the fibers is not so advanced, the base fabric is used as a reinforcing nonwoven fabric for assisting the point where the fibers are brittle and have low strength. It plays an important role, and is also effective for increasing the stiffness and stiffness of the nonwoven fabric. As the base fabric, point bonded spunbond nonwoven fabric, melt blown nonwoven fabric, hydroentangled nonwoven fabric, thermal bonding nonwoven fabric, needle punched nonwoven fabric, resin impregnated bonded nonwoven fabric and the like are convenient. Among them, the spunbonded nonwoven fabric is convenient because it also serves to improve the peelability from the conveyor when it is an electret nonwoven fabric, and is particularly convenient when the fineness is ² to 20 dtex and the basis weight is 10 to 50 g / m ^2. good. Such a base fabric is not limited to a fiber material, but for air filter applications, it is convenient that the fiber density is coarse, and when the melt blown nonwoven fabric of the present invention is made of a polyolefin resin, considering its adhesiveness, Nonwoven fabrics made of polyolefin resin, specifically spunbond nonwoven fabrics are preferred, and are particularly preferred for disposal.

  Further, in disposal such as incineration, it is preferable that the air filter material is made of an all-polyolefin resin and does not use any polyester material that can be smoked. However, polyolefin resin has high electrical insulation, and even if a melt-blown nonwoven fabric is simply laminated as in the past, a new problem has arisen that sufficient electret processing cannot be performed due to its electrical insulation. Even though the basis weight of the meltblown non-woven fabric was insufficient, the composite non-woven fabric of the present invention could be provided with electret characteristics. The air filter material made of all-polyolefin resin is easy to dispose of in particular and does not contain any environmental hormones or other harmful substances. Even if it encounters a fire, it is harmful, such as soot and hydrogen chloride. Since it does not generate gas, it is suitable as a non-woven fabric material considering humans and the environment.

In bonding the composite strand to the base fabric, there is not much difference in fineness with a basis weight of 10 to ²⁰ g / m ² , but a composite having a fiber diameter of more than 500 μm is particularly applied to a heat-bonded nonwoven fabric having a fineness of 15 to 22 dtex. When adhering the strands, an elongated rectangular nozzle is used, so the resin temperature when the semi-molten composite strand comes into contact with the heat-bonded nonwoven fabric is important, and at a temperature near the melting point of the resin of the fibers constituting the heat-bonded nonwoven fabric, There is a conflicting theory that it is most preferable to bond at this temperature, which is a particularly important issue, and the adhesive state of the composite strand at the center and end in the width direction of the thermobonded nonwoven fabric is controlled to be the same. It is extremely important to do. However, in general, the center part is well adhered and the end part is often difficult to adhere. Further, the end portion is also a portion where stress is easily applied and easily peeled off during a rewinding operation of the nonwoven fabric. Of course, simply bonding the composite strand to the heat-bonded nonwoven fabric can ensure the reinforcement effect, but there is a problem that the control range is narrow and difficult to manufacture in actual production. A melt blown nonwoven fabric composed of a composite fiber having a basis weight of at least 10 g / m ² is laminated so as to cover the composite strand, and a melt blown nonwoven fabric composed of the composite fiber is further bonded to any one of the composite nonwoven fabrics. It is convenient for production because it is easy to process and is laminated so that it is fused and adhered to the surface of the fabric. By incorporating the composite strand so as to be embedded in the nonwoven fabric, the rigidity of the nonwoven fabric and pleat folding, etc. Formability and shape retention are enhanced, which is extremely convenient.

  In the electret processing, since it is mainly used for a filter, lower pressure loss is desired, and from the viewpoint of electret processing, it is preferable that the fiber surface cover is denser and coarser. The composite fiber is preferably a fiber having an average fiber diameter larger than 15 μm, but even a thinner fiber is not inconvenient depending on the application. In these cases, the non-woven fabric to which a partial thickness such as a fiber lump or a composite strand, which is one form of the present invention, is added is a three-dimensional accumulation of fibers around these thick objects. By making the gap between them large, a device that roughens the surface cover of the fiber is added. Furthermore, the melt blown nonwoven fabric has a plurality of layers, and it is also very preferable to change the melt blow jet axis so that each layer crosses. In addition, electret non-woven fabric with non-woven fabric on both sides is intended for dust-absorbing curtains, wall hangings, wallpaper, etc., and the composite fiber is assumed to be polyolefin fiber. A non-woven fabric in which polyolefin fibers are at least partially arranged on the surface to be bonded is used.

  Furthermore, in order to achieve an increase in bulk, that is, increase in thickness, low pressure loss, and simplification of thermal bonding with the base fabric, the average fiber diameter of the composite fibers constituting the meltblown nonwoven fabric in contact with the base fabric is 10 to 200 μm thick. The fiber is made of fine fiber (thick composite fiber) and not only heat bonding to the base fabric, but also the physical entanglement effect of the thick fiber is added to reduce the amount of heat received by the base fabric or surface non-woven fabric. The increase in thickness was achieved by suppressing the formation of the nonwoven fabric into a film and increasing the thickness of the fiber mass that was agglomerated, entangled and fused and adhered.

When a composite non-woven fabric in which a melt-blown non-woven fabric composed of the above-mentioned thick composite fiber is bonded and integrated to a base fabric, for example, a heat-bonded non-woven fabric, or a composite non-woven fabric is bonded and integrated, the basis weight exceeds 90 g / m ^2. However, it has been found that it can be processed under a strong electric field and can be further laminated by a melt blown nonwoven fabric. In addition, a composite nonwoven fabric in which a thick-fiber meltblown nonwoven fabric is bonded and integrated has a lower stiffness than conventional nonwoven fabrics, becomes a hard nonwoven fabric, can be easily pleated, and has a higher shape retention effect. These effects can be further improved by bonding and integrating. That is, the composite fibers having different fiber diameters are arranged on the surface nonwoven fabric made of fibers having a fiber diameter of 15 μm or more. In the first stage, thick composite fibers having an average fiber diameter (DS: μm) of 10 <DS <200 are arranged on the base fabric to which the composite strands are bonded, but the average fiber diameter is 15 to 50 μm. The layers composed of thick composite fibers are ejected with the distance between the melt blow nozzle and the base fabric close to each other so that the basis weight is 5 to 15 g / m ^2, and then the thick composite fibers having a desired average fiber diameter are accumulated. Is most preferred. Thus, the thick composite fiber constituting the thick composite fiber layer does not cause any inconvenience even if the fibers have a plurality of types of fiber diameters.

The distance between the nozzle and the base fabric is preferably about 5 to 25 cm. This is a closer distance than in a normal melt blow spinning process. The reason is that the thick composite fiber penetrates into the base fabric and is physically entangled with the thick composite fiber, and the fusion bonding effect between the fibers constituting the base fabric and the thick composite fiber is This is to increase it. However, it is natural to set the distance between the nozzle and the base fabric so that the base fabric does not melt with the hot air of melt blow spinning. However, if the operation is continued for a long time, the temperature of the circulating conveyor belt rises, A problem that a part of the resin melts or forms a film is not preferable. In order to prevent this phenomenon, it is most convenient to use a thick composite fiber having a basis weight of 5 to 15 g / m ^{2 and} an average fiber diameter of 15 to 50 μm. If the basis weight is less than 5 g / m ² , the adhesion to the base fabric is weak, and if it exceeds 15 g / m ² , the problem of melting or film formation tends to occur. If the average fiber diameter of the thick composite fiber exceeds 50 μm, partial melting of the fibers constituting the base fabric tends to occur, and if it is less than 10 μm, the fiber accumulation effect on the surface of the base fabric is large, and The penetration of the composite fiber is small and the physical entanglement effect of the thick composite fiber is reduced, which is not preferable.

  Originally, thicker fibers are better for bulkiness, lower pressure loss, and higher hardness of the nonwoven fabric (higher nonwoven fabric and better pleat foldability). In addition, it is very convenient to laminate and integrate the fibers while fusing or fusing them with a low melting point resin that occupies the majority of the fiber surface.

  When the composite nonwoven fabric of the present invention is used for a filter application, a filter function is formed by laminating a thinner composite fiber layer on the base fabric and a thick composite fiber accumulation layer, and a function of mainly collecting dust. Can be given. The average fiber diameter (DM2: μm) of the fine composite fiber is 0.3 <DM2 <20, and the fiber diameter is arbitrarily selected according to the purpose. When a fine fiber is selected, it is also very preferable to select a resin having a high MFR depending on the fiber diameter.

  The composite strand used in the present invention is a composite fiber having a structure in which the low melting point component S1 occupies 40% or more of the fiber surface, as in the case of the composite fiber of the melt blown nonwoven fabric, as already described. As shown in Fig. 1, the two components have a cross-sectional structure such as a sheath-core type, a cat-eye type, or a three-layer type in which one component is separated into two by other components, and the low melting point component covers most of the fiber surface. The occupied fiber is preferable, and the sheath-core type composite fiber is particularly preferable in terms of reinforcement. Further, a multi-core type, a three-layer type, and a fiber in which one component is divided into at least a plurality and divided by other components may be a fiber having a split type such as a mandarin orange type or a windmill type. The fiber shape is basically a circular shape such as a circle or an ellipse, but may be an irregular shape with a rounded corner. A fiber having a hollow such as a hollow in the fiber is also preferable from the viewpoint of weight reduction.

  The average fiber diameter referred to in the present invention refers to the number average fiber diameter, and the melt blown nonwoven fabric of the present invention uses a heat-adhesive conjugate fiber and is arbitrarily partially fused and bonded. Therefore, the dispersion and distribution of the fiber diameter are wide, and the fiber diameter was determined by microscopic observation. The calculation was performed by excluding the fusion-bonded lump and fiber bundle.

  In the melt blown fiber, it is more advantageous to increase the bulk by the uneven method, especially when the aggregated and fusion-bonded fiber lump is scattered, and when thick composite fiber is used, the fiber is divided into a plurality of times and accumulated. Is particularly preferred. Even in the case of fine fibers, if air filter applications are assumed, in order to avoid unevenness in weight, it is particularly preferable that fibers are accumulated in a plurality of times as described above. In addition, in the fiber accumulation, the fibers are easily aligned in a certain direction by the melt blow method, and therefore, it is preferable to laminate the layers so as to intersect each other as much as possible. In the present invention, this point is taken into consideration in the equipment.

Considering the basis weight required for each layer as described above, the total basis weight of the base fabric and the meltblown nonwoven fabric excluding composite strands is preferably 30 to 400 g / m ² , depending on the application. If the basis weight exceeds 400 g / m ² , the state of hot air penetration is poor, and if it is less than 30 g / m ² , the required basis weight of each constituent layer cannot be secured, which is not convenient. For pleated fold filter applications, 60 g / m ² or more is preferable in view of its rigidity.

The basis weight of the composite strand of the present invention is 50 to 1000 g / m ^{2, which} is convenient for reinforcing applications. If the basis weight is less than 50 g / m ² , the reinforcing effect is small and is not convenient. Further, as the weight per unit area increases, the distance between the bonded nonwoven fabric and the nozzle is increased to produce, but if it exceeds 1000 g / m ² , it is difficult to bond the bonded nonwoven fabric without dissolving it, which is not preferable. Moreover, when increasing a fabric weight, it is preferable to narrow the space | interval of a composite strand, to increase the number per unit width, to make the fiber diameter of a strand thin, and to prevent a nonwoven fabric from melt | dissolving. The number of composite strands per unit width is preferably 2 to 20 mm, and particularly preferably 3 to 7 mm for reinforcement and production.

  The composite nonwoven fabric of this invention can select the fiber to be used and can apply it to various uses. For example, an electret non-woven fabric in which both surfaces of a polybutene-1 resin / polypropylene resin composite fiber as an intermediate layer are occupied by an olefin non-woven fabric to which a hydrophilic substance such as a surfactant is not attached, which is convenient for a dust-absorbing curtain, etc. Also related.

  In addition, the melt blown nonwoven fabric body has a phenomenon that a hole is quickly opened when it hits a flame, and is excellent in flame retardancy. Although it is flame retardant, the spunbond nonwoven fabric side has obtained inferior flame retardancy, and the flame retardant effect agent Flem Stub CGL- from Ciba Specialty Chemicals Co., Ltd. is used as the polypropylene resin constituting the composite strand with the spunbond nonwoven fabric. The composite nonwoven fabric made of spunbond nonwoven fabric and composite strand with at least 0.5% by mass of 116 is always flame retardant according to the flame retardancy evaluation method JIS L 1091, A-1 method, regardless of the surface from which the flame is applied. Since it becomes possible to obtain the third grade, it is further optimal as an air filter material. The above-mentioned flame retardant effect agent CGL-116 is a derivative of a Halus stabilizer which is a normal weathering stabilizer of polypropylene resin. Even in combination with the Hals stabilizer and other stabilizers, environmental hormones and harmful substances are used. Because it does not contain, it is very environmentally friendly.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating an example of a cross-sectional shape of a composite fiber and a composite strand constituting the composite nonwoven fabric of the present invention. FIG. 1A shows a cross-sectional shape that is a core component generally called a cat eye, in which a high-melting-point component (1) is elliptical, and a low-melting-point component (2) that is a sheath component surrounds the periphery. FIG. 1B shows a concentric core-sheath structure in which the core is a high melting point component and the sheath is a low melting point component. FIG. 1C shows a three-layer structure in which a high melting point component is sandwiched between low melting point components.

  FIG. 2 is an enlarged view of a side cross section of the composite fiber nonwoven fabric of the present invention. In the periphery of the fiber mass (3) where the composite fiber is partially thermally bonded, the composite fiber has a wide fiber gap in both the thick composite fiber (4) and the fine composite fiber (5), and the fiber density is low. It is bulky and forms a convex portion of the nonwoven fabric. On the other hand, the middle part of the fiber lump and the fiber lump is a part (6) having a high fiber density. Similar to the fiber mass (3), the composite strand also exhibits the effect of dispersing the same fine composite fiber (5).

  FIG. 3 is a diagram showing a state in which composite strands are arranged substantially in parallel and bonded and integrated on a base fabric. The composite strand (6) extends in the length direction at a substantially constant interval with respect to the width direction of the base fabric (9), and is bonded substantially in parallel to be integrated with the base fabric (9).

  Next, the effect of the present invention will be specifically described with reference to examples. In addition, although it mainly demonstrates with the melt blown nonwoven fabric which consists of composite fiber which makes the sheath component which is one Embodiment of this invention polybutene-1 resin, and makes a core component a polypropylene resin, the composite nonwoven fabric of another form is also an Example. Needless to say, it can be easily fabricated as well. The composite strand is basically the same as the production of an ordinary composite fiber, and will be described as a composite fiber in which the sheath component is polybutene-1 resin and the core component is polypropylene resin. Unless otherwise specified, the production conditions and configuration of the fibers of the meltblown nonwoven fabric are used.

  First, a conveyor net with a polypropylene spunbond nonwoven fabric preheated at 140 ° C. as a base fabric under a nozzle for composite fibers with a nozzle width of about 70 cm in a three-row arrangement and 132 holes mounted downward. The spunbond nonwoven fabric was fed at 15 m / min.

  Composite strands are extruded on two spun extruders, each thermoplastic resin is extruded by a gear pump, metered by a pump, and discharged from a row of orifices using a composite nozzle that can form composite fibers. The fiber was allowed to flow down, and was elongated to a shape that was pulled by the self-weight of the strand and the moving spunbonded nonwoven fabric to form a basically continuous very thick fiber, and was bonded to the spunbonded nonwoven fabric with a low melting point component.

Next, the composite fiber fiberized by the melt-blowing method is a composite of 850 holes with a width of less than 70 cm that can form a composite fiber by extruding individual thermoplastic resins from two extruders and quantitatively supplying them with a gear pump. A nozzle is used to discharge from a row of orifices into a high-speed heated airflow, and at the same time, the airflow is elongated to form basically continuous fibers, which are collected on a conveyor net equipped with suction equipment. A polypropylene spunbond nonwoven fabric having the composite strand bonded thereon is positioned with the composite strand as the upper surface, and a thick composite fiber having an average fineness of 6 to 10 dtex (average fiber diameter of 23 to 38 μm) is 15 g / m ² on the nonwoven fabric. Accumulate with basis weight, and change the traveling angle of conveyor net every time to make multiple layers of thick fiber or fine fiber with desired basis weight Sleep and laminated to produce a composite nonwoven fabric of the present invention. Each layer was accumulated by intersecting at an angle of at least 30 degrees.

The resins used in the present invention are as shown in Table 1. PP is a polypropylene resin, PB is a polybutene-1 resin (“Tuffmer” manufactured by Mitsui Chemicals, density ρ: 0.92 g / cm ³ ), and PE is a high density. Polyethylene resin, PET is a polyethylene terephthalate resin (using a resin having a normal viscosity IV of 0.64), PMP is a polymethylpentene resin (“TPX” manufactured by Mitsui Chemicals), and EP is an excess of propylene (ethylene content) 6-8% by weight) of ethylene-propylene copolymer was used. The composite ratio of the sheath component and the core component of the composite fibers and composite strands constituting the meltblown nonwoven fabric is 1: 1. The melt-flowable MFR has a measurement temperature of 290 ° C. for PET and PMP, and 230 for the others. The value in ° C. is in g / 10 minutes. The Q value is a ratio of weight average molecular weight / number average molecular weight.

[Examples 1 to 10, Comparative Examples 1 to 3]
Using the resins shown in Table 1, composite nonwoven fabrics were produced under the conditions shown in Table 2 using the production method. The spinning temperature is the nozzle temperature, and is ejected using high-pressure hot air at the same temperature, and is sucked with a suction amount that is five times or more the amount of hot air blown to obtain a basis weight of 15 g / m. ^2. Composite strands were bonded onto a spunbond nonwoven fabric of about 7 dtex, and meltblown nonwoven fabrics were accumulated thereon to obtain composite nonwoven fabrics of Examples and Comparative Examples. The composite strand is the same as the composite fiber, but the fiber cross section is always the sheath core type of FIG. 1B, the fiber diameter is about 400 μm, and the basis weight is 500 g / m ² at a pitch of 3 mm.

  Thermal electretization is a process in which a composite non-woven fabric is conveyed by a stainless steel mesh conveyor and is continuously placed in a dryer at 120 ° C and allowed to cool immediately thereafter, and needles installed in the vicinity of the conveyor are embedded at regular intervals. A direct high electric field of 15 to 45 Kv was generated between the applied electrodes, and electret processing was performed under this electric field to obtain an electret nonwoven fabric.

The average fiber diameter of the composite fibers shown in Table 2 was the number average fiber diameter (μm), and the fused fibers were excluded. Each fiber layer has a number of times of accumulation of at least two times and is indicated by its total weight (g / m ² ). The total thickness and the apparent thickness of the composite strand and the base fabric were measured by the JIS-L-1913-6.1.2A method. The thickness of the thick composite fiber layer and the thin composite fiber layer in the melt blown nonwoven fabric was measured by enlarging each layer in a state of being laminated on the base fabric and the composite strand with an electron microscope.

  The collection efficiency shown in Table 2 is the capture rate of air dust particles of 0.3 to 0.5 μmφ, and the measurement flow rate of the collection efficiency is 5.3 cm / s in accordance with JIS-B-9908. Instead of, the nonwoven fabric of each example was mounted, and the filtration surface was measured as 100 mmφ.

  Comparative examples 1 and 3 are examples in which the composite strands of the examples are not used. Table 2 shows the resin components used in the examples and comparative examples, and the nonwoven fabric performance of the composite fiber nonwoven fabric. Moreover, the comparative example 2 is an example when not performing electret processing.

  When the nonwoven fabric obtained in Examples 1 to 10 was subjected to pleat folding using a pleat folding machine, the degree of gear roll engagement was good, and pleat folding was possible smoothly. Particularly, the core component of the composite strand had a high glass transition point and was hard. Examples 6 to 9 which were resins were particularly good. The smooth non-woven fabric on which the composite strands of Comparative Examples 1 to 3 were not attached was difficult to hang and could be folded in pleats, but had a problem in workability.

  In addition, in the case of a composite nonwoven fabric using a melt blown nonwoven fabric without a conventional fiber lump, the processability can be improved by sticking the composite strand in addition to the fiber lump dispersion even if the electretization processability is reduced. There was no decrease in

[Example 11]
Instead of the polypropylene spunbond nonwoven fabric of Example 1, a laminate of melt blown nonwoven fabrics composed of composite fibers was produced, and a composite nonwoven fabric obtained by adhering the composite strands of Example 1 was produced thereon. (Appearance) The thickness was almost the same as in Example 1, and the pleat foldability was also the same.

[Example 12]
The nonwoven fabric of Example 2 and the polypropylene spunbonded nonwoven fabric of ² dtex and 40 g / m ² are bonded together with a hot air processing machine at 140 ° C. while being rubbed with a bar, and then the same as in Example 1. An electret non-woven fabric was then heat processed. When it was put in a box in which atmospheric dust was diffused, atmospheric dust was adsorbed remarkably, and the spunbond nonwoven fabric on the surface became grayish.

[Example 13]
An activated carbon fiber nonwoven fabric obtained by firing a 6 dtex rayon hydroentangled nonwoven fabric with a basis weight of 60 g / m ² under anaerobic conditions at 650 to 700 ° C. is placed on the 7 dtex spunbond nonwoven fabric used in Example 1, and from above A hydroentangled nonwoven fabric in which a web having a basis weight of 30 g / m ^{2 made} of ² dtex rayon fiber is placed and hydroentangled to form a hydroentangled nonwoven fabric integrated with the rayon fiber, and the hydroentangled nonwoven fabric of the spunbond nonwoven fabric of Example 1 is used. Instead, the composite strand and the meltblown nonwoven fabric were laminated in the same manner as in Example 1 to obtain a composite nonwoven fabric. The obtained composite nonwoven fabric retained at least the ability to collect hydrogen sulfide.

[Example 14]
0.1% by mass of Ciba weathering stabilizer 944, 1.5% by mass of flame retardant effect agent CGL116, and 0.3% by mass of phosphorous stabilizer 168 are added to the polypropylene resin constituting the polypropylene spunbonded nonwoven fabric of Example 1. A composite nonwoven fabric was produced in the same manner as in Example 1 except that% was added. The obtained composite nonwoven fabric always showed good flame retardancy.

[Example 15]
A composite nonwoven fabric was produced in the same manner as in Example 1 except that the composite strand of Example 1 was replaced with a high-density polyethylene resin having a sheath component of MFR 50 g / 10 min. When the obtained composite nonwoven fabric was evaluated for pleat folding, the shape of the folded pleats was slightly inferior to that of Example 8 but sharper and better than that of Example 1.

[Example 16]
In Example 3, a composite strand was applied to a polypropylene spunbond nonwoven fabric as a base fabric, and then a thick composite fiber was sprayed at a basis weight of 15 g / m ² , and then the remaining thick composite fiber was re-applied to the other surface of the base fabric. A composite nonwoven fabric having composite fiber layers on both sides, in which a thick composite fiber was sprayed at a basis weight of 25 g / m ² and fine fibers were laminated thereon. This was electret processed in the same manner as in Example 3 and the collection efficiency was measured. As a result, the filter material was improved by 92%.

  The composite nonwoven fabric of the present invention has rigidity, high pleatability and pleat shape retention, and is suitable for filter applications, particularly air filters. Further, the composite nonwoven fabric is electret processed and is useful as a material for air filters such as a building air-conditioning filter, a dust-absorbing curtain, and a mask material.

It is a figure which shows an example of the cross-sectional shape of the composite fiber and composite strand which comprise the composite nonwoven fabric of this invention. It is the figure which expanded the side cross section of the composite nonwoven fabric of this invention. It is the schematic which shows the state by which the composite strand was distribute | arranged substantially parallel to the base fabric, and it united and integrated.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High melting-point component 2 Low melting-point component 3 Fiber lump 4 Thick composite fiber 5 Fine composite fiber 6 Composite strand 7 Fiber which comprises base fabric (partial description, others are abbreviate | omitted)
8 High fiber density 9 Base fabric

Claims (11)

With the base fabric,
Composed of two or more thermoplastic resins having different melting points, and 40% or more of the fiber surface is composed of a component having the lowest melting point among the thermoplastic resins (hereinafter referred to as low melting point component S1);
A meltblown non-woven fabric comprising a composite fiber comprising two or more thermoplastic resins having different melting points, wherein 40% or more of the fiber surface is occupied by a component having the lowest melting point among the thermoplastic resins (hereinafter referred to as low melting component M1). , A composite non-woven fabric bonded and integrated in this order,
The composite strand is arranged substantially parallel to the width direction of the base fabric and extends in the length direction of the base fabric, and is bonded to the base fabric with a low melting point component S1,
A composite nonwoven fabric obtained by bonding the meltblown nonwoven fabric to the base fabric with a low melting point component M1 of a composite fiber.   The other surface of the base fabric is made of two or more components thermoplastic resins having different melting points, and is covered with a melt blown nonwoven fabric in which 40% or more of the fiber surface is occupied by the low melting point component M1, and is integrally bonded. The composite nonwoven fabric according to claim 1.   The composite nonwoven fabric according to claim 1 or 2, wherein the melt blown nonwoven fabric has a convex portion formed on a nonwoven fabric surface with a fiber lump in which a plurality of fibers constituting the melt blown fabric are partially aggregated and bonded.   The composite nonwoven fabric according to claim 1, wherein the composite strand has a fiber diameter (DS: μm) of 100 <DS <2000.   The low melting point component S1 of the composite strand is at least one resin selected from a polybutene-1 resin and a high-density polyethylene resin, and the other thermoplastic resin component is polypropylene. The composite nonwoven fabric described. Total basis weight of the base fabric and the meltblown nonwoven fabric is a 30 to 400 g / m ^2, the basis weight of the composite strands is 50 to 1000 g / m ^2, a composite nonwoven according to any one of claims 1 to 5 .   A surface nonwoven fabric composed of fibers having a fiber diameter of 5 μm or more is disposed on at least one surface of the composite nonwoven fabric, and is bonded and integrated by at least one of the low melting point component S1 and the low melting point component M1 constituting the composite nonwoven fabric. The composite nonwoven fabric according to any one of claims 1 to 6.   The composite nonwoven fabric according to any one of claims 1 to 7, wherein the base fabric is a spunbonded nonwoven fabric composed of fibers made of at least one resin selected from polypropylene and a propylene-based copolymer.   The composite nonwoven fabric according to claim 1, wherein the composite nonwoven fabric is electret processed.   The composite nonwoven fabric according to claim 1, wherein the composite nonwoven fabric is formed by pleat folding in the length direction of the nonwoven fabric. An air filter formed by pleat folding the composite nonwoven fabric with a pleat folding width of 30 mm or more.

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