JP2005076144A - Nonwoven fabric and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a nonwoven fabric that is integrated by splitting of a part of a split type conjugate fiber, has no reduction in air permeability and porosity and in which fibers are spilt not only on the surface but also in the inside. <P>SOLUTION: The nonwoven fabric comprises a fiber assembly composed of the split type conjugate fiber. The split type conjugate fiber has a fiber cross-section structure in which combinations of at least two kinds of segments made of different polyolefins are placed in a line. The nonwoven fabric comprises a nonsplit part (A) of the split type conjugate fiber, a part (B) in which split and finely separated segments of the split type conjugate fiber are dispersed and a part (C) in which the split and finely separated segments of the split type conjugate fiber are bundled in the direction of fiber axis in a mixed state. The split and finely separated segments of the split type conjugate fiber are three-dimensionally entangled. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a nonwoven fabric composed of a fiber assembly containing split-type conjugate fibers.

  Ultrafine fibers are used in various applications such as battery separators and wiping cloths, and can be obtained by peeling and dividing a separation-dividing composite fiber. The peelable split type composite fiber can be obtained by combining a plurality of thermoplastic resins with low compatibility as a segment and spinning. Examples of the thermoplastic resin combination include polyester and polyolefin, polyester and polyamide, and polyamide and polyolefin. Ultrafine fibers can be obtained by using the physical stress such as needle punching and the difference in shrinkage of the thermoplastic resin to chemicals to separate and divide the segments using such stress. . Thus, a nonwoven fabric for wipers has been proposed that includes a combination of thermoplastic resins that can be easily divided by applying a mechanical impact, and is divided and entangled by a needle punch (for example, patent literature). 1).

Further, there has been proposed an ink absorber for an ink jet printer that includes chemical fibers and / or natural fibers and ultrafine fibers, and has a total surface area A (cm ² / cm ³ ) per unit volume of the constituent fibers of 450 to 800. (For example, refer to Patent Document 2). This ink absorber has a configuration in which fibers made of different types of polymers such as polyester and polyamide are mixed. Therefore, although it can be easily divided by physical stress during needle punching, it has a problem of low chemical resistance. .

  On the other hand, split type composite fibers composed of a combination of polyolefins compared to the combination of different polymers are superior in chemical resistance and the like, but have a relatively high compatibility with thermoplastic resins. There was a problem that it was difficult. It should be noted that a larger mechanical impact is required when the split type composite fiber is split by high-pressure water flow processing or the like.

  In order to improve the splitting property of such a polyolefin-based split fiber, a polyolefin-based split composite fiber to which organosiloxane or a modified product thereof is added has been proposed (for example, see Patent Document 3). In addition, a polyolefin-based split composite fiber that defines the Q value (ratio of weight average molecular weight / number average molecular weight) of polypropylene and has a hollow portion at the center of the fiber cross section has also been proposed (see, for example, Patent Document 4). . Furthermore, a split type composite fiber made of polyolefin and having a hollow portion at the fiber center has been proposed (see, for example, Patent Document 5).

  However, the documents 3 to 5 mentioned above are spunlace processing (high-pressure liquid flow treatment) and nonwoven fabric obtained by this processing. Spunlace processing enables uniform and highly divided finening, but physical stress due to high-pressure water flow concentrates on the surface layer part of the fiber assembly (for example, web, sliver, etc.), so the divided segment is the surface layer part. It becomes easy to diffuse in two dimensions. For this reason, in processing with a high-pressure water stream, the surface layer portion is often seen to have a shape close to a film, and there is a problem in that the air permeability and the porosity are reduced. Furthermore, as the fiber aggregate becomes higher in weight, the problem becomes more prominent, and it is difficult to obtain a structure in which the inside of the nonwoven fabric is three-dimensionally divided and entangled.

Japanese Patent No. 3121185 JP 2000-318301 A JP-A-4-289222 JP 2002-220740 A Japanese Patent No. 3309181

  Therefore, the problem of the present invention is that a part of the split type composite fiber is integrated by splitting, there is no decrease in air permeability and porosity, and the fiber is split not only on the surface but also inside. It is to provide a non-woven fabric.

The inventors of the present invention have made extensive studies in order to solve the above problems. As a result, it has been found that the above-described problems can be solved by having the following configuration, and the present invention has been completed based on this finding.
The present invention has the following configuration.

[1] A nonwoven fabric composed of a fiber assembly containing split-type composite fibers, wherein the split-type composite fibers have a fiber cross-sectional structure in which a combination of at least two types of segments made of different polyolefins is continuous. The non-woven fabric is composed of an undivided portion (A) of a split-type conjugate fiber, a portion (B) in which a segmented fine segment of the split-type conjugate fiber is dispersed, and a segmented fine segment of the split-type conjugate fiber. A non-woven fabric characterized in that a part (C) converged along the axial direction is mixedly contained, and the segmented and refined segments of the segmented composite fiber are intertwined three-dimensionally .
[2] The nonwoven fabric according to item [1], wherein the fiber assembly is composed of only split-type composite fibers.
[3] The split-type conjugate fiber has a hollow portion of 15 to 40% with respect to the cross-sectional area of the fiber at the center of the fiber cross section, and the fineness is greater than 2.2 dtex and less than 5 dtex. The nonwoven fabric according to item [1] or item [2], wherein
[4] The nonwoven fabric according to any one of [1] to [3], wherein the nonwoven fabric is composed only of polyolefin fibers.
[5] The nonwoven fabric according to any one of [1] to [4], wherein the nonwoven fabric is a needle punched nonwoven fabric.
[6] A sound absorbing material using the nonwoven fabric according to any one of [1] to [5].
[7] The fineness of the fiber having a fiber cross-sectional structure having a hollow portion of 15 to 40% with respect to the cross-sectional area of the fiber and having a combination of at least two types of segments composed of different polyolefins in the center of the fiber cross-section. A method for producing a nonwoven fabric, comprising subjecting a fiber assembly including split-type composite fibers larger than 2.2 dtex to less than 5 dtex to needle punching to split-split the split-type composite fibers.
[8] The method for producing a nonwoven fabric according to the above [7], wherein the nonwoven fabric is composed only of polyolefin fibers.
[9] A sound absorbing material using a nonwoven fabric obtained by the production method according to the item [7] or [8].

The nonwoven fabric of the present invention is entangled not only with the surface of the fiber assembly, but also with the segmented composite fibers in the interior thereof, which are divided into finely divided segments (hereinafter referred to as “fiber segments” or “extra fine fibers”). By being combined, the air permeability and the porosity are not significantly reduced.
In the nonwoven fabric of the present invention, the undivided part (A) of the split composite fiber, the part (B) in which the fiber segments are dispersed, and the part (C) in which the fiber segments converge along the fiber axis direction are mixed three-dimensionally, Entangling and forming sufficient voids due to uneven distribution, so sound absorbing material, cushioning material, air filter, liquid filter, artificial leather base fabric, heat insulating material, carpet base material, automotive interior It can be suitably used for sanitary materials such as materials, interlinings, coated base fabrics, laminate base materials, agricultural materials, insulating materials, and diapers. In addition, because it contains fiber segments, it has excellent water absorption and oil absorption properties, as well as oil film and dust scraping and collecting properties, and can be used for wiping materials, oil adsorbents, ink tank adsorbents, abrasives, etc. It can be preferably used. Furthermore, since various functional agents can be included in the void layer of the split-type composite fiber, various functions can be imparted. The sound absorbing material using the nonwoven fabric of the present invention has excellent sound absorbing properties.

Hereinafter, the present invention will be described in detail.
The nonwoven fabric of the present invention is a nonwoven fabric composed of a fiber assembly containing split-type composite fibers, and the split-type composite fibers have a fiber cross-sectional structure in which a combination of at least two types of segments made of different polyolefins are continuous. The non-woven fabric was undivided part (A) of the split composite fiber, the part (B) in which the split fine segment of the split composite fiber was dispersed, and the split fine fiber of the split composite fiber. A portion (C) in which the segments converge along the fiber axis direction is included, and the segmented and refined segments of the segmented composite fibers are intertwined and integrated in three dimensions. Yes. Thus, the split type composite fiber is composed of at least two different polyolefins so that a combination of at least two types of segments is continuous.
In the present invention, in order to divide the split-type conjugate fiber, physical stress may be applied to the split-type conjugate fiber, and the most preferable processing method is needle punching, and the nonwoven fabric obtained by this processing method is It is a needle punched nonwoven fabric.

  The cross-sectional structure of the split-type conjugate fiber constituting the nonwoven fabric of the present invention is not particularly limited as long as it can be split, but preferably has a hollow portion inside the fiber, for example, as shown in FIGS. It is a cross-sectional structure in which a and b2 component polyolefins are alternately arranged. In the case of a split type composite fiber composed of a multi-component polyolefin, a fiber cross-sectional structure in which a combination of a plurality of segments composed of different polyolefins are formed without the same component being adjacent to each other. 1 to 3 is a model diagram of the cross-sectional structure of a split type composite fiber having a hollow portion illustrated in FIGS. 1 to 3 (hereinafter referred to as “hollow split type composite fiber”). In some cases, the cross-sectional structure and shape are deformed due to various external stresses. However, these deformations have no problem in practical use.

  In the present invention, the average single yarn fineness of the fiber segments after the division is preferably 1.0 dtex or less, and more preferably 0.7 dtex or less. Therefore, the number of segments of the hollow segmented composite fiber (this is the number of segments in the design) may be determined so that the average fineness of the ultrafine fibers is 1.0 dtex or less. If there is more, there exists an advantage which the fineness after a division | segmentation becomes small, but it is preferable to actually make it the number of segments of 4-32 from the ease on fiber manufacture. In addition, the fineness of each segment does not need to be the same, and if the split-type conjugate fiber is not completely split, a plurality of different sizes are placed between the unsplit split-type conjugate fiber and the completely split ultrafine fiber. However, there is no particular problem. In addition, when the non-woven fabric of the present invention is mixed with hollow split type composite fibers having the fiber cross section exemplified in FIG. 1, FIG. 2 or FIG. 3, the fineness and the number of segments change, and the appearance, texture Etc. become better.

  The ratio of the area of the hollow part to the cross-sectional area of the fiber occupied by the hollow part present in the fiber center part of the hollow split composite fiber used in the present invention, that is, the hollow ratio is preferably 15% to 40%, more preferably 20 to 20%. 35%. If the hollow ratio is within this range, the contact area between adjacent segments is appropriate, and therefore, the area can be divided only by physical stress during needle penetration such as needle punching. Moreover, although it is easy to divide | segment by the physical stress at the time of card machine passage, this causes the passage defect by subduction into a cylinder, or the formation defect by generation | occurrence | production of a nep, and workability does not fall significantly. Therefore, by setting the hollow ratio within the above range, it is possible to obtain a fiber that can be easily divided by needle punching while maintaining workability and productivity.

  The single yarn fineness before splitting of the split-type composite fiber used in the present invention is not particularly limited. However, in needle punching, physical stress during needle penetration through the web and physical stresses such as impact and friction due to barbs are applied. It is desirable that the fineness and shape be easy. Specifically, the fineness that is susceptible to physical stress is such that the fineness before division is greater than 2.2 dtex and less than 5 dtex. At 2.2 dtex or less, since the number of constituent fibers of the web is large, needle breakage due to excessive physical stress is likely to occur at the time of web penetration, and physical stress per single fiber is dispersed, making division difficult. In addition, at a fineness of 5 dtex or more, the splitting property is improved, but subsidence into the cylinder due to the segment divided when passing through the card machine is likely to occur, and the workability is lowered. The split-type conjugate fiber used in the present invention has a hollow portion of 15 to 40% with respect to the cross-sectional area of the fiber at the center of the fiber cross section, and the fineness is greater than 2.2 dtex and less than 5 dtex. It is most preferable that it is easily divided by needle punching. Moreover, when the fiber assembly is comprised only from a split type composite fiber, since the fineness of the fiber segment which comprises the nonwoven fabric obtained can be made low, it is preferable.

  In the needle punching process, by using split-type composite fibers, splitting by physical stress through the needle is facilitated, but the nonwoven fabric obtained by the production method of the present invention is an unsplit part of split-type composite fibers (A ) And the part (B) in which the segmented finely divided segments of the segmented composite fiber are dispersed are unevenly distributed in the nonwoven fabric, and the segmented and further refined segments are converged along the fiber axis direction. (C: hereinafter referred to as “continuous yarn bundle”) is mixed. Here, the continuous yarn bundle refers to a state in which the divided segments are not completely dispersed in the nonwoven fabric but are converged in a state where the segments are bundled while maintaining a certain distance. For example, most of the fibers immediately after passing through the fiber opening process such as a roller card machine, a web using an air laid machine, and a processing process into a sliver are occupied by the undivided portion (A). When passing, the part (B) and the yarn bundle (C) in which the segmented and finely divided segments are dispersed due to the physical stress at the time of penetrating the web of the needle and the physical stress such as impact and friction due to barb are developed. Further, when the needle further pushes down the web, (A), (B), and (C) are intertwined and unevenly distributed three-dimensionally. These structures are easily developed by concentrating the physical stress due to the needle in the point direction with respect to the flow direction of the web, but further, high pressure liquid flow treatment is performed so that the surface of the resulting nonwoven fabric is not too dense. By using them together, the distribution states (A) to (C) can be changed.

  In the case of high-pressure liquid flow treatment, which is a typical processing method for split-type composite fibers, which is generally performed, the hole diameter is 0.05 to 1.5 mm, particularly 0.1 to 0.5 mm. A high pressure liquid flow obtained by jetting at a high water pressure from the jet holes is arranged and processed in a direction perpendicular to the traveling direction of the web, using an apparatus arranged in a row or a plurality of rows at 1.5 mm. At this time, since the physical stress due to the high-pressure liquid flow is concentrated in the linear direction with respect to the flow direction of the web, the divided ultrafine fibers and the undivided fibers have a substantially two-dimensional distribution, The resulting nonwoven fabric is also very dense. In the present invention, the use of high-pressure fluid flow treatment is not excluded, but it can be used supplementarily, for example, to change the fiber distribution state on the surface of the nonwoven fabric as described above.

  On the other hand, in the case of the nonwoven fabric of the present invention, it is a structure in which the divided ultrafine fibers and undivided fibers, or continuous yarn bundles are unevenly distributed in the nonwoven fabric. That is, it has a structure in which a dense portion completely divided into each segment, a sparse portion in which some undivided fibers remain, and a portion with many continuous yarn bundles are unevenly distributed in the nonwoven fabric. Moreover, the segmented and refined segments are three-dimensionally entangled. For this reason, when the obtained nonwoven fabric satisfies both denseness and air permeability, it is possible to express characteristics excellent in form stability, dust collection ability, and the like.

  Polyolefins used for split type composite fibers include high density polyethylene (HDPE), linear low density polyethylene (LLDPE), polypropylene, polymethylpentene, 1,2-polybutadiene, and 1,4-polybutadiene, as well as ethylene, butene- 1. A crystalline copolymer with a homopolyolefin such as 1, hexene-1, octene-1, 4-methylpentene-1, or an aliphatic α-olefin. For example, copolymer polyolefin such as ethylene-propylene copolymer and ethylene-propylene-1-butene terpolymer can be used. The α-olefin is copolymerized with other olefins or a small amount of other ethylenically unsaturated monomers such as butadiene, isoprene, 1,3-pentadiene, styrene and α-methylstyrene. It may also be a mixture of the above polyolefin resins. Further, not only these polyolefins polymerized from ordinary Ziegler-Natta catalysts, but also polyolefins polymerized from metallocene catalysts and copolymers thereof can be exemplified. Furthermore, stereoregular polystyrene can be mentioned as other polyolefin.

Stereoregular polystyrene is a tacticity measured by the ¹³ C-NMR method. The presence ratio of a plurality of consecutive structural units is, for example, 2 dyads, 3 triads, 5 cases. The stereoregular polystyrene that can be used in the present invention, which can be represented by a pentad, is usually a polystyrene, polymethylstyrene, polyethyl having a syndiotacticity of a pentad fraction of 85% or more, preferably 95% or more. Polyalkyl styrene such as styrene, polyisopropyl styrene, polyhalogenated styrene such as polychlorostyrene, polybromostyrene, polyfluorostyrene, polyhalogenated alkyl styrene such as polychloromethyl styrene, polymethoxy styrene, polyethoxy styrene, etc. Polyalkoxys Tylene, polybenzoic acid ester styrene and the like, which can be used alone or in combination. Furthermore, a copolymer of monomers constituting these polymers or a copolymer containing these monomers as main components can also be used.

  That is, the copolymer includes at least one monomer selected from the monomers constituting the above-mentioned stereoregular polystyrene, olefinic monomers such as ethylene, propylene, butene, hexene, heptene, octene, and decene, butadiene, It is a copolymer having a syndiotactic styrene structure with a diene monomer such as isoprene, a cyclic olefin monomer, a cyclic diene monomer, or a polar vinyl monomer such as methyl methacrylate, maleic anhydride, or acrylonitrile. For these, commercially available homopolymers and copolymers can be used.

  The split-type conjugate fiber used in the nonwoven fabric of the present invention can be obtained by arbitrarily combining at least two different polyolefins, but particularly when used in the industrial material field and sanitary material field where chemical resistance is required. A combination of only polyolefins having high chemical resistance and cost advantage is preferable, and a combination of polypropylene and polyethylene is particularly preferable. Examples of the polypropylene include a propylene homopolymer and a copolymer of propylene containing 70% by weight or more of propylene and the above α-olefin other than propylene. Examples of such a copolymer include an ethylene-propylene binary copolymer and an ethylene-propylene-butene terpolymer.

  As the polyethylene, high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), a mixture of two or more of these, and the like can be used. Among these, high density polyethylene is preferable.

  The melt flow rate (hereinafter referred to as “MFR”) of the polyolefin used in the present invention may be within a range in which melt spinning is possible, and the MFR after fiber molding is in the range of 10 to 100 g / 10 min by changing the spinning conditions and the like. It is preferable to be within, more preferably 10 to 70 g / 10 minutes. If the MFR after fiber molding is in the range of 10 to 100 g / 10 min, the hollowness can be maintained high and the spinnability is also improved. Moreover, it is preferable that the melt flow rate ratio of 2 types of different polyolefin used by this invention is 0.1-5, More preferably, it is 0.5-3. Within this range, it is not affected by factors such as the flowability in the two-component die during melt spinning, the difference in melt tension after being discharged into a hollow shape, and the difference in viscosity increase during cooling increases. It becomes possible to spin with good spinnability while maintaining the hollow ratio.

  Physical properties of polyolefins other than the above MFR such as Q value (ratio of weight average molecular weight / number average molecular weight), Rockwell hardness, number of branched methyl chains, etc. are particularly limited as long as they satisfy the requirements of the present invention. Not.

The method for producing the nonwoven fabric of the present invention is exemplified by needle punching.
First, it is possible to divide and divide the split composite fiber by manufacturing a fiber assembly including the split composite fiber to be split and subjecting the fiber assembly to needle punching. When a web is used as the fiber assembly, a web having a required basis weight can be produced by using, for example, the short fiber of the split type composite fiber, using a card method, an airlaid method, or a papermaking method. In addition to short fibers, a web can be produced from long fiber tows using a splitting guide or the like. Further, the web may be directly produced by a melt blow method, a spun bond method or the like. The web produced by the above method can be passed through a needle punching machine using various processing needles such as a plain needle, a crown needle, a fork needle, etc., and divided into fine fibers to obtain a nonwoven fabric. Furthermore, this non-woven fabric can be further processed by a known processing method such as hot air, hot roll or hot press. Even when the nonwoven fabric of the present invention is formed into a film by a method such as a hot roll or a hot press and used as a molded product, an article excellent in flexibility, concealment property and the like can be obtained.

Although the fabric weight of the nonwoven fabric of this invention is not specifically limited, 70 g / m < ² > or more and 1,000 g / m < ² > or less are preferable, and 70 g / m < ² > or more and 600 g / m < ² > or less can be used more preferably. When the basis weight of the nonwoven fabric is within this range, it is rare that the nonwoven fabric is poorly formed when divided into fine fibers by physical stress during needle penetration.

  The nonwoven fabric of the present invention is preferably composed only of polyolefin fibers in consideration of various uses and chemical resistance. However, if necessary, the nonwoven fabric may be composed of a thermoplastic resin such as polyamide, polyester, or acrylic in addition to the polyolefin fibers. The fibers may be used in combination with the fiber assembly (mixed cotton, mixed fiber), or two or more kinds of nonwoven fabrics may be laminated. Further, when it is desired to impart hydrophilicity or impregnation with a hydrophilic drug, hydrophilic fibers can be used by blending, blending or laminating. Here, the hydrophilic fiber is not limited as long as it is a fiber exhibiting hydrophilicity. For example, regenerated fibers represented by rayon and cupra, semi-synthetic fibers represented by acetate and triacetate, and synthetic materials such as polyamide and acrylic. Examples thereof include natural fibers such as fiber, cotton, wool, and hemp.

  As the fiber form of the synthetic fiber made of a thermoplastic resin other than the polyolefin, for example, a single component type, a composite type or the like can be used. The cross-sectional structure of the fiber may be either circular or irregular, and these may be hollow or solid. The cross-sectional structure of the composite type (composite fiber) may be any of a sheath core type, an eccentric sheath core type, a parallel type, a multilayer type, a sea island type, a radial type, a hollow radial type, and the like.

  For the polyolefin or thermoplastic resin used in the present invention, an antioxidant, a light stabilizer, an ultraviolet absorber, a neutralizer, a nucleating agent, an epoxy stabilizer, a lubricant, You may add suitably additives, such as an antibacterial agent, a flame retardant, an antistatic agent, a pigment, a plasticizer, a hydrophilic agent, as needed.

  In the nonwoven fabric of the present invention, an adhesive component or a welding component can be used in combination, and the component can be more strongly integrated with the component. In the case where a thermoplastic resin is used as these components, it is preferable to blend fibers made of a thermoplastic resin. At this time, in order to bond the split type composite fiber to form a nonwoven fabric, the fiber made of the thermoplastic resin may be a fiber containing the same kind of thermoplastic resin as the thermoplastic resin constituting the split type composite fiber. preferable. Also, when the mixed cotton fiber is melted by heat treatment and bonded, the split composite fiber is melted by using a thermoplastic resin that melts at a temperature lower than the low melting point resin of the split composite fiber as an adhesive component. This is preferable because the nonwoven fabric can be formed without any problem, and the splitting and finening can easily proceed. Moreover, the strength of the nonwoven fabric can be further increased by using composite fibers as the adhesive fibers.

  In the case of blending and laminating the thermal adhesive fiber and the hydrophilic fiber to the nonwoven fabric of the present invention, the ratio of using the thermal adhesive fiber and the hydrophilic fiber together (mixed cotton, mixed fiber) is 10 to 80% by weight. It is preferable that it is 20 to 70% by weight. Within this range, the functions inherent to the ultrafine fibers can be expressed, and sufficient form stability and hydrophilicity can be obtained.

  Although the porosity of the nonwoven fabric of the present invention is not particularly limited, in order to effectively express the effect derived from the structure in which the ultrafine fibers after splitting and the unsplit fibers, or the bundle of bundles are unevenly distributed in the nonwoven fabric. It is necessary to have a sufficient porosity. Specifically, it is preferably 55 to 98%, more preferably 65 to 98%. If the porosity is 55% or more, the gap will be sufficient, and a dense part that is completely divided into each segment, a sparse part in which some undivided fibers remain, and a part with a lot of continuous yarn bundles will have the respective characteristics. It can be fully expressed. If the porosity is 98% or less, the shape stability of the nonwoven fabric is easily maintained.

  Furthermore, the non-woven fabric of the present invention can be provided with a function that is difficult to be imparted by other fiber blending and cotton blending methods by attaching or including a functional agent as necessary. In the present invention, conventionally known functional agents can be used. For example, an antibacterial deodorant, an antifungal agent, a deodorant, an adsorbent, an abrasive, an ion exchange resin, a polymer water-absorbing polymer and the like can be mentioned. When the functional agent is a solution, it may be used by impregnating the porous substrate. Porous base materials include allophane, imogolite, artificial zeolite, natural zeolite, synthetic zeolite, activated carbon, diatomaceous earth, clay minerals such as kaolin, wax, sepiolite, vermiculite, water-swellable grade mica, sericite, bentonite, etc. Can be illustrated. Moreover, the said porous base material can be used for adsorption agent. In the method of including the functional agent in the nonwoven fabric, when the functional agent is a powder such as zeolite, the split type composite fiber processed into a web is subjected to split finening and non-woven fabric simultaneously by needle punching, and then the functional agent is added. It is good to spread it uniformly on the nonwoven fabric with a sieve or the like, and then heat and bond at an appropriate temperature. As another method, the functional agent may be further dispersed in a liquid binder and adhered to the nonwoven fabric by a spray method or the like, and then heated and bonded.

  Antibacterial and deodorizing agents and fungicides used in the present invention are inorganic antibacterial agents represented by silver, copper, zinc, and composites of these metals and ceramics, benzalkonium chloride, cetylpyridinium chloride, and organic silicon type fourth. Examples include organic antibacterial agents typified by quaternary ammonium salts, polyhexamethylene biguanidine hydrochloride, chlorhexidine gluconate, natural antibacterial agents such as chitin, chitosan, polylysine, hiba oil, eucalyptus, catechin, and aloe. Deodorants include betaine amphoteric surfactants, carbonyl compounds, maleic anhydride, acrylic acid, methacrylic acid, and organic deodorants such as copolymers containing these as monomers, activated carbon, zeolite, metal ions, etc. Inorganic deodorants, natural deodorants such as catechins, photocatalysts typified by titanium dioxide, catalyst-type deodorants such as copper-phthalocyanine, iron-phthalocyanine, and the like can be exemplified.

  Examples of the abrasive used in the present invention include garnet, emery, fused alumina, silicon carbide and the like.

  When the functional agent is included in the nonwoven fabric of the present invention, dropping of the functional agent can be further suppressed by using together a fiber made of a thermoplastic resin having a function excellent in affinity with the functional agent. Examples of such thermoplastic resins include ethylene vinyl alcohol copolymer, polyvinyl acetate, polyacrylic ester, ethylene vinyl acetate copolymer, ethylene maleic anhydride graft copolymer, and the like.

  As described above, according to the production method of the present invention, even a split type composite fiber composed of polyolefin can be easily split by needle punching, and a bulky and dense nonwoven fabric can be obtained. This makes it suitable for use in the field of industrial materials such as sound absorbing materials, wiping materials, filters, cushion materials, oil adsorbing materials, ink tank adsorbing materials, and other hygienic materials and medical fields that take advantage of the chemical resistance of polyolefins. can do.

  When the nonwoven fabric of the present invention is used as a wiping material, fine components such as an oil film are scraped off at a dense part where ultrafine fibers are concentrated, and dust such as dust, mites, and hair is removed at an undivided part where there are many continuous yarn bundles. Can be held. Further, when used as an absorbent for ink tanks, it exhibits moderately excellent effects on the absorbability of high-viscosity liquids such as water-based pigments and oils, and capillary action.

  In addition, when the nonwoven fabric of the present invention is used as a sound absorbing material, it has a wide fineness distribution from the undivided portion to the fineness of each segment, so that it can cope with a wide range of frequencies, and the undivided portion (A) The uneven distribution of the part (B) in which the fibrillated segments are dispersed and the continuous yarn bundle (C) and the complicated gap due to the three-dimensional entanglement suppress the propagation of vibration, so that it is highly effective as a sound absorbing material. be able to.

  Since the bag filter is required to have both pressure loss suppression and dust retention, the nonwoven fabric obtained by the high-pressure liquid flow treatment is uniform and dense, so it is difficult to satisfy both of these requirements. On the other hand, in the nonwoven fabric of the present invention, a sparse portion where a few undivided fibers remain and a portion where there are many continuous yarn bundles contribute to suppression of pressure loss, and a dense portion where ultrafine fibers are concentrated is dust trapping. Since it contributes to the collection, it can exhibit sufficient performance as a bag filter. Moreover, when using for a bag filter, it can use more suitably by selecting processing conditions, such as needle depth, suitably, and providing the density gradient in the thickness direction by lamination | stacking of different fineness, and mixed cotton.

  Hereinafter, although an example and a comparative example explain the present invention, the present invention is not limited to these. In addition, the term and the measuring method of a physical property in an Example and a comparative example are as follows.

(Melt flow rate)
The measurement was performed according to JIS K 7210.
Raw material polypropylene: Condition 14 in Table 1
Raw material polyethylene: Condition 4 in Table 1

(Melting point)
The measurement was performed according to JIS K 7122 using a DuPont thermal analyzer DSC10 (trade name).

(Fineness before division)
JIS L 1015 Test method for chemical fiber staple Fineness The fineness converted with a fiber of 10,000 m based on the method A was used.

(Hollow rate)
It was calculated by the following formula from the undivided cross-sectional photograph.
Hollow ratio (%) = (cross-sectional area of hollow part / total cross-sectional area of fiber including hollow part of fiber) × 100

(Segment fineness)
Theoretical segment fineness (dtex) calculated by the following formula = fineness before division / number of divisions

(Segment ratio)
The divided nonwoven fabric was cut with a razor at a right angle to the fiber axis, and the cross section was photographed with an electron microscope. From the obtained photograph, 100 split-type composite fibers were arbitrarily selected, and the average fineness was calculated by the following formula.
Segment division rate (%) = (segment fineness / average fineness) × 100

(Card passability)
Under an atmosphere of 20 ° C. and a relative humidity of 60%, 50 g of sample fibers were formed into a web using a roller card machine at a speed of 7 m / min. At this time, card passability was evaluated according to the following criteria. Evaluation was performed by visual confirmation.
◯: Good with no formation failure due to fiber sinking or nep generation in the cylinder.
Δ: Slightly inferior formation due to sinking of fibers in the cylinder and generation of neps.
X: Sinking of fibers in the cylinder and generation of neps are remarkably difficult to process.

(NP processability)
The sample fiber was made into a web having a basis weight of 300 g / m ² with a roller card machine, then processed with a needle punch (NP) processing machine, and NP processability was evaluated according to the following criteria. Evaluation was performed by visual confirmation.
○: No breakage of needle during processing and good workability.
Δ: Needle breakage during processing is slightly confirmed.
X: Needle breakage is remarkable and processing is difficult.

(Form retention)
Five monitors used the samples as wiping materials to clean the flooring, walls, desks, and tatami mats by hand, received evaluations, and classified the evaluation results as follows.
○: Three or more people judged that “the nonwoven fabric was maintained and it was easy to use”.
(Triangle | delta): Two persons judged that it was "it is easy to use keeping a nonwoven fabric form."
X: Only one person judged that it was “easy to use”.

(Sound absorption)
The sound absorption rate was measured based on JIS A 1405.

Using polypropylene (propylene homopolymer, melting point 163 ° C., MFR 16 g / 10 min) as component a, high-density polyethylene (melting point 131 ° C., MFR 16 g / 10 min) as component b, and using a split composite fiber die, a volume ratio of 50 / 50, a split type composite fiber having a cross-sectional structure illustrated in FIG. 1 was spun into an undrawn yarn having a single yarn fineness of 21 dtex. The obtained unstretched yarn was stretched at 90 ° C. and 5.5 times, and mechanical crimping was imparted by a stuffer box to obtain a 4.5 dtex split type composite fiber. Next, the obtained fiber was carded with a roller card machine to obtain a web. Subsequently, the web was processed at a needle density of 300 / cm ² with a punching machine having a plain needle. Table 1 shows the structure, processability, and physical properties of the nonwoven fabric of the split-type composite fibers. When observed with an electron microscope, the obtained non-woven fabric has three-dimensional undivided parts (A) of split-type conjugate fibers, parts (B) in which segmented and finely divided segments are dispersed, and continuous yarn bundles (C). Confounded and unevenly distributed structure.

The components a and b have the same thermoplastic resin structure as in Example 1, and the split composite fiber having the volume ratio of 50/50 and the cross-sectional structure illustrated in FIG. Spinning was performed to obtain an undrawn yarn having a single yarn fineness of 15 dtex. The obtained undrawn yarn was drawn at 90 ° C. and 5 times to obtain a drawn yarn tow having a total of 100,000 dtex and a single yarn fineness of 3.3 dtex. This tow was opened with a spreader, laminated so as to have a predetermined basis weight, and then processed with a punching machine having a plain needle at a needle density of 300 / cm ² . Table 1 shows the structure, processability, and physical properties of the nonwoven fabric of the split-type composite fibers. When observed with an electron microscope, the obtained non-woven fabric has three-dimensional undivided parts (A) of split-type conjugate fibers, parts (B) in which segmented and finely divided segments are dispersed, and continuous yarn bundles (C). Confounded and unevenly distributed structure.

  A needle punched nonwoven fabric was produced in accordance with Example 1 under the conditions shown in Table 1.

Polypropylene (propylene homopolymer, melting point 163 ° C., MFR 16 g / 10 min) is a component, linear low density polyethylene (MFR: 23 g / 10 min) is a component b, and a split type composite fiber die is used. A split type composite fiber having a cross-sectional structure illustrated in FIG. 1 and having a volume ratio of component b of 50/50, a hollowness of 28%, and a fineness of 4.5 dtex was spun. Next, the obtained fiber was carded with a roller card machine to form a web, which was processed with a punching machine having a plain needle at a needle density of 300 / cm ² . Table 1 shows the structure, processability, and physical properties of the nonwoven fabric of the split-type composite fibers. When observed with an electron microscope, the obtained non-woven fabric has three-dimensional undivided parts (A) of split-type conjugate fibers, parts (B) in which segmented and finely divided segments are dispersed, and continuous yarn bundles (C). Confounded and unevenly distributed structure.

  A needle punched nonwoven fabric was produced in accordance with Example 1 under the conditions shown in Table 1.

  A needle punched nonwoven fabric was produced in accordance with Example 1 under the conditions shown in Table 1.

  A needle punched nonwoven fabric was produced in accordance with Example 1 under the conditions shown in Table 1.

  A needle punched nonwoven fabric was produced in accordance with Example 1 under the conditions shown in Table 1.

Using polypropylene (propylene homopolymer, melting point 163 ° C., MFR 16 g / 10 min) as component a and polymethylpentene (melting point 240 ° C., MFR 60 g / 10 min: 290 ° C., 2160 g) as component b, using a split composite fiber die A split type composite fiber having a cross-sectional structure illustrated in FIG. 1 and having a volume ratio of 50/50 between the a component and the b component, a hollow ratio of 30%, and a fineness of 4.8 dtex was spun. Next, the obtained fiber was carded with a roller card machine to obtain a web. Subsequently, the web was processed at a needle density of 300 / cm ² with a punching machine having a plain needle. Table 1 shows the structure, processability, and physical properties of the nonwoven fabric of the split-type composite fibers. When observed with an electron microscope, the obtained non-woven fabric has three-dimensional undivided parts (A) of split-type conjugate fibers, parts (B) in which segmented and finely divided segments are dispersed, and continuous yarn bundles (C). Confounded and unevenly distributed structure.

  A needle punched nonwoven fabric was produced in accordance with Example 1 under the conditions shown in Table 2.

Using polypropylene (propylene homopolymer, melting point 163 ° C., MFR 16 g / 10 min) as a core component, high-density polyethylene (melting point 131 ° C., MFR 16 g / 10 min) as a sheath component, using a sheath core type composite fiber die, a volume ratio of 50 / Two types of sheath-core type composite fibers (undrawn yarns) having different discharge amounts of 50 were spun. The obtained two types of undrawn yarns were drawn at 90 ° C. and 4.0 times, subjected to mechanical crimping with a stuffer box, and then cut into 51 mm. A 4.4 dtex sheath-core type composite fiber and a 6 dtex sheath-core type composite fiber were obtained. 4.4 dtex sheath-core type composite fiber (30 wt%), 6 dtex sheath-core type composite fiber (30 wt%) and the split type composite fiber (40 wt%) produced in Example 1 were each used in a roller card machine. After forming a web, the web was laminated in the order of a web consisting of a 6 dtex sheath-core type composite fiber / a web consisting of a 4.4 dtex sheath-core type composite fiber / a web consisting of a split type composite fiber to form a multilayer web. Subsequently, the laminated web was processed with a punching machine having a plain needle at a needle density of 450 needles / cm ² . When observed with an electron microscope, the obtained non-woven fabric has three-dimensional undivided parts (A) of split-type conjugate fibers, parts (B) in which segmented and finely divided segments are dispersed, and continuous yarn bundles (C). Confounded and unevenly distributed structure.

  50% by weight of the split-type composite fiber prepared in Example 1 and 50% by weight of rayon (1.7 dtex, fiber length: 44 mm) were mixed into a web using a roller card machine, and needle punched in the same manner as in Example 1. . When observed with an electron microscope, the obtained nonwoven fabric was entangled and unevenly distributed three-dimensionally in the undivided portion (A) of the split-type conjugate fiber, the segmented finely divided segment (B), and the continuous yarn bundle (C). The structure was shown.

Polypropylene (propylene homopolymer, melting point 163 ° C., MFR 16 g / 10 min) a component, high density polyethylene (melting point 131 ° C., MFR 26 g / 10 min) and modified polyethylene (linear low density polyethylene with a density of 0.931 g / cm ³ ) A polymer having a maleic anhydride graft modification rate of 0.15 mol / kg as a backbone polymer, MFR 14 g / 10 min) blended at a weight ratio of 80/20, and using a split type composite fiber die as a volume ratio. 50/50, a split type composite fiber having a cross-sectional structure illustrated in FIG. 1 was spun to obtain an undrawn yarn having a single yarn fineness of 21 dtex. The obtained undrawn yarn was drawn at 90 ° C. and 5 times, and mechanical crimping was imparted by a stuffer box to obtain a split type composite fiber. The obtained fiber was processed by a roller card machine and needle punched in the same manner as in Example 1 to make a nonwoven fabric. Observation with an electron microscope reveals that the obtained nonwoven fabric has three-dimensional undivided portions (A) of split-type conjugate fibers, portions (B) where segmented and finely divided segments are dispersed, and continuous yarn bundles (C). The structure was entangled and unevenly distributed. Next, the obtained nonwoven fabric for artificial zeolite comprising (average particle size 10 to 30 [mu] m, an average pore diameter of ^{20 × 10 -8 ~50 × 10 -8} cm, a specific surface area of 40 to 100 m ² / g) to 20 g / ^{m 2} It was sprayed uniformly on the nonwoven fabric and heated and bonded at 155 ° C. for 15 minutes. Table 2 shows the physical properties of the obtained nonwoven fabric.

  Below, Comparative Examples 1-5 are shown.

(Comparative Example 1)
Using polypropylene (propylene homopolymer, melting point 163 ° C., MFR 16 g / 10 min) as a core component, high-density polyethylene (melting point 131 ° C., MFR 16 g / 10 min) as a sheath component, using a sheath core type composite fiber die, a volume ratio of 50 / 50. A sheath-core type composite fiber having a cross-sectional structure illustrated in FIG. 4 was spun. The obtained undrawn yarn was drawn at 90 ° C. and 4.0 times to give mechanical crimp, and then cut to 51 mm to obtain a 4.4 dtex sheath-core type composite fiber. This short fiber was made into a web with a roller card machine and made into a nonwoven fabric by needle punching as in Example 1. Table 2 shows the performance of the obtained nonwoven fabric.

(Comparative Example 2)
In accordance with Example 1, a split type composite fiber having a hollowness of 25% and a cross-sectional structure of 1.5 dtex illustrated in FIG. 1 was obtained. This short fiber was processed into a non-woven fabric by processing with a roller card machine and needle punching in the same manner as in Example 1. In this processing, the split-type composite fiber had good card passing properties, but the fineness before split was as thin as 1.5 dtex, so needle breakage occurred frequently in the needle punch processing step. Moreover, the segment division ratio of the obtained nonwoven fabric was also low.

(Comparative Example 3)
Based on Example 1, a split composite fiber having a hollow ratio of 35% and a cross-sectional structure illustrated in FIG. In the same manner as in Example 1, this split type composite fiber was processed by a roller card machine and needle punched to make a nonwoven fabric. In this processing, the split type composite fiber had a fineness before splitting as thick as 6 dtex.

(Comparative Example 4)
According to Example 1, a split type composite fiber having a hollow ratio of 10% and a cross-sectional structure of 4.5 dtex illustrated in FIG. 1 was obtained. In the same manner as in Example 1, this split type composite fiber was processed by a roller card machine and needle punched to make a nonwoven fabric. In this processing, the split-type conjugate fiber was good in both card passing property and needle punching property. However, since the hollow ratio is as low as 10%, the obtained nonwoven fabric has many undivided parts (A) and is almost split. I did not.

(Comparative Example 5)
In accordance with Example 1, a split composite fiber having a hollow ratio of 45% and a cross-sectional structure of 4.5 dtex illustrated in FIG. 1 was obtained. In the same manner as in Example 1, this split type composite fiber was processed by a roller card machine and needle punched to make a nonwoven fabric. In this processing, the split-type composite fiber has a high hollowness ratio of 45%, and the subsidence and the generation of neps due to the splitting in the card process are remarkable, and the processing is difficult.

  Using the needle punched nonwoven fabric of Example 1 and Comparative Example 1 as a sound absorbing material, the sound absorption rate (normal incidence) at each frequency of 250 Hz to 5 kHz was examined. As a result, the needle punched nonwoven fabric of Comparative Example 1 has a sound absorption rate of 0.04 to 0.3, whereas the needle punched nonwoven fabric of Example 1 shows a sound absorption rate of 0.05 to 0.6, which is a comparative example. The sound absorbing property was superior to that of No. 1 needle punched nonwoven fabric.

  The non-woven fabric of the present invention is a non-divided portion (A) of split-type conjugate fibers, a portion (B) in which split fine segments are dispersed, and a portion in which split fine segments converge along the fiber axis direction. (C) is mixed and entangled three-dimensionally and forms sufficient voids derived from non-uniform distribution, so that sound absorbing materials, cushion materials, air filters, liquid filters, artificial leather base fabrics, It can be suitably used as sanitary materials such as heat insulating materials, carpet base materials, automotive interior materials, interlinings, coating base fabrics, laminate base materials, agricultural materials, insulating materials, and diapers. In addition to oil film, dust scraping and collecting properties, it also has excellent water absorption and oil absorption properties, so it can be suitably used for wiping materials, oil adsorbents, ink tank adsorbents, abrasives, etc. . Furthermore, since various functional agents can be included in the void layer of the split fibers, various functions can be imparted.

It is 1 schematic diagram of the cross section of the split type composite fiber used in the Example of this invention. It is 1 schematic diagram of the cross section of the split type composite fiber used in the Example of this invention. It is 1 schematic diagram of the cross section of the split type composite fiber used in the Example of this invention. It is 1 schematic diagram of the cross section of the sheath core type composite fiber used by the comparative example of this invention.

Explanation of symbols

A: a component B: b component

Claims (9)

  A non-woven fabric composed of a fiber assembly containing split-type composite fibers, wherein the split-type composite fibers have a fiber cross-sectional structure in which a combination of at least two types of segments made of different polyolefins is continuous, The undivided part (A) of the split-type conjugate fiber, the part (B) in which the segmented finely divided segment of the split-type conjugate fiber is dispersed, and the segmented finened segment of the split-type conjugate fiber in the fiber axis direction A non-woven fabric characterized in that the part (C) converged along the line is mixed and the segmented and refined segments of the segmented composite fiber are intertwined three-dimensionally.   The nonwoven fabric according to claim 1, wherein the fiber assembly is composed of only split-type composite fibers.   The split-type conjugate fiber has a hollow portion of 15 to 40% with respect to the cross-sectional area of the fiber at the center of the fiber cross section, and its fineness is greater than 2.2 dtex and less than 5 dtex. The nonwoven fabric according to claim 1 or 2.   The nonwoven fabric according to any one of claims 1 to 3, wherein the nonwoven fabric is composed only of polyolefin fibers.   The nonwoven fabric according to any one of claims 1 to 4, wherein the nonwoven fabric is a needle punched nonwoven fabric.   The sound-absorbing material using the nonwoven fabric of any one of Claims 1-5.   The fiber has a hollow cross section of 15 to 40% with respect to the cross-sectional area of the fiber at the center of the fiber cross section, and has a fiber cross section structure in which a combination of at least two kinds of different polyolefins are connected. A method for producing a nonwoven fabric, comprising subjecting a fiber assembly containing split-type composite fibers larger than 5 to less than 5 dtex to needle punching to split-split the split-type composite fibers.   The method for producing a nonwoven fabric according to claim 7, wherein the nonwoven fabric is composed only of polyolefin fibers. The sound-absorbing material using the nonwoven fabric obtained by the manufacturing method of Claim 7 or Claim 8.

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