JP4026279B2 - Split type composite fiber and fiber molded body using the same - Google Patents

Description

【００９４】
【表２】

【００９５】
表１、表２から明らかなように、本発明の実施例各例で得られた繊維成形体および積層繊維成形体は、比較各例に比べて同条件でも高分割率で分割している。即ち、従来のような高水圧の高圧液体流処理を行わなくても、分割、細繊化が容易に進行するため、比較的低目付の不織布でも地合が乱れることなく製造することができ、さらに高圧液体流処理のコストも大幅に削減することができる。
【００９６】
【発明の効果】
本発明の分割型複合繊維は、非常に分割し易いため、特別に易分割させるための添加剤を一切添加せずに、物理衝撃を大きくしなくても極細繊維化が容易に行える。このため、本発明の分割複合繊維を用いると緻密で地合いの良い繊維成形体および積層繊維成形体が得られる。
【図面の簡単な説明】
【図１】本発明に用いられる分割型複合繊維の繊維断面の１模式図
【図２】本発明に用いられる分割型複合繊維の繊維断面の１模式図
【図３】本発明に用いられる分割型複合繊維の繊維横断面の１模式図
【図４】本発明に用いられる分割型複合繊維の繊維横断面の１模式図
【図５】本発明に用いられる分割型複合繊維の繊維横断面の１模式図
【図６】屈曲もしくは湾曲により囲まれた面積（Ｓ１）と分割型複合繊維の断面積（Ｓ２）を示した模式図
【図７】本発明に用いられる分割型複合繊維の繊維横断面の１模式図
【図８】本発明に用いられる分割型複合繊維の繊維横断面の１模式図
【図９】比較例に用いられる分割型複合繊維の繊維横断面の１模式図
【図１０】比較例に用いられる分割型複合繊維の繊維横断面の１模式図
【符号の説明】
Ｌ：複合繊維の各成分が交互に隣接される方向で、かつ、断面形状の最も長い部分の長さを表す。
Ｗ：複合繊維の各成分の接触面方向で断面形状の厚みを表す。
ａ：複合繊維を構成する１成分の繊維外周面の長さを表す。
ｂ：複合繊維を構成する１成分の隣接成分との接触長さを表す。
Ｓ１：長軸の両端を結んだ直線と屈曲あるいは湾曲により囲まれた部分の面積を表す。
Ｓ２：複合繊維の繊維横断面積を表す。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a split type composite fiber excellent in splitting property. More specifically, a split type composite fiber excellent in splitting properties that can be suitably used in the field of industrial materials such as battery separators, wipers, filters, sanitary materials such as diapers and napkins, and clothing. The present invention relates to a fiber molded body and a laminated fiber molded body using the same.
[0002]
[Prior art]
Conventionally, sea-island type and split type composite fibers are known as methods for obtaining ultrafine fibers. In the method using sea-island type composite fibers, a plurality of components are spun together to form sea-island type composite fibers, and one component of the obtained composite fibers is dissolved and removed to obtain ultrafine fibers. Although this method can obtain very fine fibers, it is uneconomical for dissolving and removing one component. On the other hand, the method using a split-type composite fiber is a composite fiber obtained by spinning a combination of a plurality of component resins, and the obtained composite fiber is utilized, for example, by utilizing a physical stress or a difference in shrinkage of the resin with respect to chemicals. A split type composite fiber is divided into a large number of fibers to obtain ultrafine fibers.
[0003]
For example, when split fiber composites represented by a combination of polyester resin and polyolefin resin, a combination of polyester resin and polyamide resin, and a combination of polyamide resin and polyolefin resin are processed into a non-woven fabric, etc., high pressure liquid flow treatment The division finening process such as the above becomes the rate-limiting step of the non-woven fabric process. In addition, there is a problem in that the energy cost required for splitting and finening is large.
[0004]
On the other hand, in a combination of similar resins such as polyolefin resins, polyester resins, polyamide resins, etc., since the compatibility of the resin is relatively good compared to the heterogeneous polymer, the problem as described above is further increased. It is necessary to further increase the physical impact in order to divide into fine pieces. For this reason, the obtained nonwoven fabric has a divided portion and a portion that is not divided, or the fibers move due to physical impact, so that a thick portion and a thin portion are formed. And there is a problem that it is necessary to significantly reduce the processing speed of the high-pressure liquid flow treatment.
[0005]
In order to remedy this problem, Japanese Patent Laid-Open No. 4-28922 discloses that by adding organosiloxane and a modified product thereof to a resin, even a split type composite fiber of a combination of the same kind of polymers can be easily split. It is disclosed that it is possible. However, although the splitting property is somewhat improved, the nonwoven fabric obtained using the split fibers has problems such as reduced strength and poor workability in secondary processing.
[0006]
[Problems to be solved by the invention]
The inventors of the present invention have made extensive studies in order to solve the problems of the prior art. As a result, it is composed of at least two component thermoplastic resins, and in the fiber cross section, each component is alternately adjacent in the long axis direction, and the cross section is a composite fiber having a bent, curved or flat shape, When the split type composite fiber satisfying the ratio of the major axis L to the short axis W (L / W) of 3 to 20 is obtained, the split type composite fiber can be easily split, and the split type composite fiber is used. It was found that a dense and well-formed fiber molded body and a laminated fiber molded body were obtained, and the present invention was completed based on this finding.
As is clear from the above description, the purpose of the present invention is to add a split type composite fiber having excellent splitting ability even if it is a combination of similar resins without adding any additive for improving splitting ability. It is to provide a dense and well-formed fiber molded body and a product using the molded body.
[0007]
[Means for Solving the Problems]
  The present invention comprises the following.
(1) It is composed of at least two component thermoplastic resins, and in the fiber cross section, each component is alternately adjacent in the long axis direction, and the cross section is bent and curved.Or, as the flat shape, U-shaped, horseshoe-shaped, or a cross-sectional shape in which the curved portion of the U-shaped or horseshoe-shaped is compressed and flattenedA composite fiber ofThe composite ratio of the composite fiber is in the range of 10/90 to 90/10% by weight, and in the fiber cross section of the split composite fiber, the area S1 surrounded by bending or bending and the cross sectional area S2 of the split composite fiber Ratio (S1 / S2) is 0.2 to 1.0,The ratio of the major axis L to the minor axis W (L / W) of the cross section is 3 to 20For splitting and finening processing by physical stressSplit composite fiber.
[0008]
(2) In the fiber cross section of the split type composite fiber, the ratio (a / b) of the contact length b between the fiber outer peripheral surface length a of one component and the adjacent component constituting the fiber is 0.1 to 2.5 2. The split type composite fiber according to item 1.
[0010]
(3) The melt flow rate of at least two components of the thermoplastic resin constituting the fiber after fiber molding is 10 to 100 g / 10 min, and among the thermoplastic resins, the resin component having the highest melting point (hereinafter, The ratio (MFR-A / MFR-B) of the melt flow rate (MFR-A) of the component A) and the melt flow rate (MFR-B) of the resin component having the lowest melting point (hereinafter referred to as component B) is 0. 1 to 5 above.Or the second termThe split type composite fiber as described.
[0011]
(4The combination of at least two components of the thermoplastic resin is a polypropylene resin and a polyethylene resin.3The split type composite fiber according to any one of the items.
[0012]
(5) The first to second items, wherein the single yarn fineness before splitting of the composite fiber is 0.5 to 10 dtex, and the single yarn fineness after splitting is 0.5 dtex or less.4The split type composite fiber according to any one of the items.
[0013]
(61) to 1)Item 5A fiber molded body comprising at least 30% by weight or more of the split composite fiber according to any one of the above, and 50% or more of the split composite fiber being split.
[0014]
(7) The above-mentioned fiber molded body is a fiber assembly6The fiber molded body according to Item.
[0015]
(8) The fiber molded body is a fiber assembly obtained by the spunbond methodItem 6 or Item 7The fiber molded body described.
[0016]
(9)Item 6-8A laminated fiber molded body obtained by laminating sheets on one or both sides of the fiber molded body according to any one of the above.
[0017]
(10)Item 6-8A laminated fiber molded body obtained by laminating the fiber molded body according to any one of the above on both surfaces of a sheet.
[0018]
(11) The sheet is a sheet selected from at least one of a nonwoven fabric, a film, a knitted fabric, and a woven fabric.Item 9 or 10The laminated fiber molded body described.
[0019]
(12)Item 6-8The fiber molded body according to any one of the above or the aboveItems 9 to 11An absorbent article using any one of the laminated fiber molded articles.
[0020]
(13)Item 6-8The fiber molded body according to any one of the above or the aboveItem 9 to Item 11A wiper using the laminated fiber molded article according to any one of the above.
[0021]
(14)Item 6-8The fiber molded body according to any one of the above or the aboveItem 9 to Item 11A battery separator using the laminated fiber molded article according to any one of the above.
(15) A method for producing an ultrafine fiber, comprising subjecting the split type composite fiber according to the above item 1 to splitting and finening by physical stress.
(16) The method for producing ultrafine fibers according to the above item 15, wherein the division finening by physical stress is performed by a needle punch method, a high-pressure liquid flow treatment, or a pressurized calender roll.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The thermoplastic resin used for the split composite fiber of the present invention is not particularly limited as long as it has fiber formability in the melt spinning process. For example, polyester resins, polyamide resins, polyolefin resins and the like are preferably used. It can be mentioned as a resin.
[0023]
Examples of the polyester resin include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and 2,6-naphthalenedicarboxylic acid or aliphatic dicarboxylic acids such as adipic acid and sebacic acid as esters, and esters thereof. It is a homopolymer polyester or copolymer polyester synthesized from a diol compound such as ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-cyclohexanedimethanol as an alcohol component. Those having added or copolymerized paraoxybenzoic acid, 5-sodium sulfoisophthalic acid, polyalkylene glycol, pentaerythritol and the like are also included.
[0024]
As the polyamide-based polymer, 6,6-nylon, 6,10-nylon, 6-nylon, 1,1-nylon, 1,2-nylon, 4-nylon, 4,6-nylon, and these are mainly used. A copolymer etc. can be illustrated.
[0025]
On the other hand, as the polyolefin resin, an aliphatic α-olefin having 2 to 8 carbon atoms such as ethylene, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 3-methyl-1-butene, Homopolymers such as 1-hexene and 1-octene or copolymers of two or more of these α-olefins, the α-olefin and other olefins and / or a small amount of other ethylenically unsaturated monomers such as butadiene , Copolymers with unsaturated monomers such as isoprene, pentadiene-1, styrene, α-methylstyrene, and mixtures of two or more thereof.
[0026]
Typical examples include polypropylene resins and polyethylene resins. Examples of the polypropylene resins include propylene homopolymer, propylene containing 70% by weight or more, and 1 of the above α-olefin other than propylene. Copolymers with more than one species, such as ethylene-propylene copolymer and ethylene-propylene-butene copolymer, can be mentioned.
[0027]
Examples of the polyethylene resin include high density polyethylene (HDPE), low density polyethylene (LDPE), and linear low density polyethylene (L-LDPE).
[0028]
The melt flow rate (230 ° C., 2.18N, hereinafter referred to as MFR) of the polypropylene resin and the MFR (190 ° C., 2.18N) of the polyethylene resin are not particularly limited as long as they can be spun. However, in the case of any resin, 1 to 100 g / 10 min is preferable, and more preferably 5 to 70 g / 10 min.
[0029]
As the thermoplastic resin other than the above, for example, a vinyl polymer is used, and specifically, polyvinyl alcohol, polyvinyl acetate, polyacrylate ester, ethylene vinyl acetate copolymer, syndiotactic polystyrene or a copolymer thereof. Polymers can also be used.
[0030]
The split-type conjugate fiber of the present invention can be arbitrarily combined with at least two thermoplastic resins among the above, but in fields requiring dyeing such as garments, for example, polyester resins and polyamide resins Combinations based on resins are preferred. In the industrial material field and sanitary material field where chemical resistance, light weight, and low cost are required, a combination mainly composed of polyolefin resin having high chemical resistance and advantageous in cost can be exemplified. A combination of a polypropylene-based resin and a polyethylene-based resin is suitable for a field where properties are required.
[0031]
Here, the thermoplastic resin can be arbitrarily combined. For example, a combination of polyethylene terephthalate resin and polyethylene terephthalate resin, a combination of polypropylene resin and polypropylene resin, and a mixture having the same composition ratio. Is excluded from the scope of the present invention.
[0032]
In the combination of two components of a polypropylene resin and a polyethylene resin that are preferably used in the split composite fiber of the present invention, the polypropylene resin becomes a high melting point resin (component A). Specific examples of such polypropylene resins include syndiotactic polypropylene and isotactic polypropylene polymerized with a Ziegler-Natta catalyst, a metallocene catalyst, or the like. The MFR-A of the polypropylene resin, which is a high melting point resin, only needs to be in a range that can be melt-spun, and the MFR-A after fiber molding is within a range of 10 to 100 g / 10 minutes by changing the spinning conditions and the like. If there is no particular problem. The MFR-A after fiber molding is more preferably 10 to 70 g / 10 minutes. When MFR-A after fiber molding is less than 10 g / 10 minutes or more than 100 g / 10 minutes, it becomes difficult to spin into fine fibers with good spinnability.
[0033]
The polyethylene resin is a low melting point resin (component B) lower than the melting point of the polypropylene resin, and specific examples include high density polyethylene, linear low density polyethylene, and low density polyethylene. . Moreover, the mixture of 2 or more types of these polyethylene may be sufficient. The MFR-B of the polyethylene-based resin as a raw material may be in a range that can be melt-spun, and if the MFR-B after fiber molding is within a range of 10 to 100 g / 10 minutes due to changes in spinning conditions and the like, there is a particular problem. There is no. The MFR-B after fiber molding is more preferably 10 to 60 g / 10 minutes. When MFR-B is less than 1 g / 10 minutes or more than 100 g / 10 minutes, it becomes difficult to spin into fine fibers with good spinnability.
[0034]
Of the at least two thermoplastic resins constituting the split-type conjugate fiber of the present invention, when the resin having the highest melting point is the A component, the MFR of the A component is MFR-A, and the resin having the lowest melting point is B. When the MFR of the B component when used as a component is MFR-B, the ratio of the MFR (MFR-A / MFR-B) is preferably 0.1 to 5, more preferably 0. 5-3. If this value is less than 0.1 or exceeds 5, the flowability of these components during melt spinning, the difference in melt tension after being discharged into a bent, curved, or flat shape, during cooling It becomes difficult to maintain the spinnability due to factors such as a large difference in viscosity increase.
[0035]
The thermoplastic resin used in the present invention further includes an antioxidant, a light stabilizer, an ultraviolet absorber, a neutralizer, a nucleating agent, an epoxy stabilizer, a lubricant, an antibacterial agent within the range not impeding the effects of the present invention. Additives such as additives, flame retardants, antistatic materials, pigments, plasticizers and hydrophilic agents may be added as necessary.
[0036]
Next, the fiber cross section of the split type composite fiber of the present invention will be described.
The split composite fiber of the present invention is composed of, for example, a thermoplastic resin having at least two components as illustrated in FIG. 1, and in the fiber cross section, each component is alternately adjacent in the major axis direction, and the cross section is A bicomponent fiber having a bent, curved, or flat shape, and having a ratio (L / W) of a major axis L to a minor axis W of the cross section of 3-20. Here, the long axis L is the direction in which the components are alternately adjacent to each other and represents the length of the longest portion of the cross-sectional shape (see FIG. 1). The minor axis W represents the contact surface direction of each component, that is, the thickness of the cross-sectional shape (see FIG. 1). When the L / W ratio is 3 or more, the surface area is large when the number of divided segments and the fineness are the same as those of ordinary circular cross-section split conjugate fibers, for example, radial and laminated split conjugate fibers, Since the contact area between adjacent components becomes small, a high-pressure liquid flow can be effectively received by the composite fiber, and it becomes easy to divide even at the same water pressure. In addition, if the composite fiber exceeds 20, the composite fiber can effectively receive a high-pressure liquid flow, but problems such as maintaining the spinnability, reducing the number of holes per unit area of the die, and reducing productivity are generated. To do.
[0037]
Furthermore, the splitting property is further improved because the cross-sectional shape is bent, curved or flat. Compared to the case where the fiber cross-sectional shape is a straight line (see FIG. 9), when the undrawn yarn obtained in the spinning step is drawn in the drawing step, for example, when the undrawn yarn is drawn in the drawing step, the fibers are concentrated between the rolls having a speed difference Is stretched with a strong stress, but at this time, the fibers are pressed with a high pressure. Moreover, when setting it as a short fiber, fibers will be pressed in the cutting process with the strong pressure equivalent to or more than a drawing process. For this reason, the split-type conjugate fiber of the present invention having a bent or curved fiber cross section is very easily crushed as compared with a straight cross-sectional shape, that is, splitting partially proceeds. Moreover, even if it is not divided, the contact interface of each component of the composite fiber is distorted and is more easily divided, and the split type composite fiber of the present invention is very easy to be divided.
[0038]
In this way, when the division has already partially progressed during the yarn making process, the papermaking method can be suitably used. In the case of the papermaking method, it is preferable that the division has already progressed partially because a dense and good web is formed at the papermaking stage. Further, when it is desired to suppress the progress of division during the yarn making process as much as possible, it is effective to set the draw ratio low. Specifically, the drawn yarn elongation preferably has 20% or more of the undrawn yarn elongation. Here, the bent or curved cross-sectional shape is not particularly limited, and is, for example, C-shaped (see FIGS. 1 to 5), S-shaped (see FIG. 7), M-shaped, N-shaped, L-shaped. , V-shaped, W-shaped (see FIG. 8), corrugated, and the like, but the present invention is not limited to these cross-sectional shapes. Moreover, the mixture of various cross-sectional shapes may be sufficient.
Further, examples of the flat shape include U-shaped, horseshoe-shaped, and U-shaped and horseshoe-shaped curved portions that are compressed and flattened, but the present invention is limited to these cross-sectional shapes. It is not something.
[0039]
As mentioned above, since the fiber cross-sectional shape of the split composite fiber of the present invention is bent, curved or flat in the long axis direction, the same effect as the stretching and cutting process can be obtained by pressing between calender rolls. It can be carried out. Therefore, for example, even when long fibers in an unstretched yarn state such as the spunbond method are directly accumulated on a conveyor, they are divided and refined by passing between pressurized calender rolls. It can be a body. Compared to the fiber cross section of the split type composite fiber used in the conventional spunbond method, the split type composite fiber of the present invention is composed of ultrafine fibers having a more uniform fineness because each segment has almost the same fineness. A fiber molded body can be obtained.
[0040]
Further, the ratio (a / b) between the length a of the fiber outer peripheral arc of one component of the resin constituting the split-type conjugate fiber of the present invention and the contact length b of the adjacent component is 0.1 to 2.5. It is preferable to satisfy. When the (a / b) ratio is less than 0.1, the contact area with the adjacent component is larger than that of the outer peripheral surface of the fiber. Necessary. On the other hand, if it exceeds 2.5, the number of divisions is reduced or the thickness of the flat shape becomes too thin, so that it is very difficult to produce with good spinnability.
[0041]
Moreover, in the fiber cross section of the split-type conjugate fiber of the present invention, the ratio (S1 / S2) of the area S1 surrounded by bending and bending to the cross-sectional area S2 (see FIG. 6) of the split-type conjugate fiber is 0.2 to It is preferable to satisfy 1.0. Here, S1 represents a portion surrounded by a straight line connecting both ends of the major axis and a bend or curve in the fiber cross section of the split-type conjugate fiber of the present invention, and represents a degree of the bend or the curve. That is, if S1 is increased, the major axis is greatly bent or curved, and S1 / S2 preferably satisfies 0.2 or more. If it is less than 0.2, the bending and bending are small, and the effect of the bending and bending becomes small. On the other hand, if it exceeds 1.0, it becomes difficult to maintain productivity due to problems such as the long axis of the composite fiber becoming too long or the thickness becoming extremely thin.
[0042]
The split type composite fiber according to the present invention has a fiber cross-sectional shape as described above, so that the conventional split type composite fiber is very difficult to split and a combination of similar resins that required high energy to split. In particular, even a combination of polyolefin resins is excellent in splitting property and can be easily split. Furthermore, even a web composed of short fibers used in the papermaking method can be divided with a high division ratio with good texture. From the above, the split-type conjugate fiber of the present invention can be preferably used for a combination of resins that have been considered difficult to split. Here, the spinneret used for obtaining the fiber cross section of the split composite fiber of the present invention is not particularly limited as long as the split composite fiber can be obtained. A base disposed in an S shape, an M shape, an N shape, an L shape, a V shape, a W shape, a wave shape, a U shape, a horseshoe shape, or the like can be used.
[0043]
In the split type composite fiber of the present invention, the composite ratio of the composite fiber composed of at least two component thermoplastic resins is in the range of 10/90 to 90/10% by weight, and the total amount of the component resins used is 100%. %, More preferably 30/70 to 70/30% by weight, and most preferably 40/60 to 60/40. By setting it as the composite ratio of this range, it becomes a cross-sectional shape in which at least two types of thermoplastic resins are uniformly arranged, and a more uniform fiber molded body can be obtained.
[0044]
When the split type composite fiber obtained in the present invention is split by high-pressure liquid flow treatment or the like, the average fineness of the split ultrafine fiber is preferably 0.5 dtex or less, and particularly preferably 0.3 dtex or less. Therefore, the number of divided segments of the split type composite fiber may be determined so that the average fineness of the ultrafine fiber is 0.5 dtex or less, and if the number of divided segments is large, there is an advantage that the fineness after splitting is reduced. Is preferably 4 to 32 segments for ease of fiber production.
[0045]
Although the single yarn fineness before a division | segmentation is not specifically limited, It is preferable that it is 0.5-10.0 decitex, More preferably, it is 1.0-6.0 decitex. In addition, the fineness of each segment does not need to be the same, and if the split type composite fiber is not completely divided, a plurality of different finenesses are placed between the undivided split fiber and the completely split ultrafine fiber. Of fibers may be mixed.
[0046]
Hereinafter, as an example of the split type composite fiber of the present invention, a method for producing a split composite fiber in which two components of a polypropylene resin and a high density polyethylene resin are combined will be exemplified.
A long fiber made of the resin is spun using an ordinary melt spinning machine. At the time of spinning, it is preferable to spin at a spinning temperature of 200 to 330 ° C., and the take-up speed is preferably about 40 m / min to 1500 m / min. Stretching may be performed as necessary. When stretching is performed, the stretching ratio is usually about 3 to 9 times. Further, the obtained tow is cut into a predetermined length to make a short fiber. Although the manufacturing process of the short fiber has been disclosed above, the long fiber tow can be made into a web by a fiber separation guide or the like without cutting the tow. After that, it is formed into a fiber molded body according to various uses through high-order processing steps as required. Also, a fiber molded body that is wound up as a filament yarn after spinning and drawing, and knitted or woven into a knitted fabric, or a fiber molded body that is knitted or woven into a knitted fabric after the short fibers are spun into a spun yarn. You may form in.
[0047]
That is, here, the fiber molded body may be in any form as long as it is in the form of a cloth, and examples thereof include woven fabrics, knitted fabrics, nonwoven fabrics, and nonwoven fiber assemblies. Moreover, what was made into the form of cloth by methods, such as blended cotton, blended yarn, blended fiber, twisted twist, knit, and mixed fiber, is also included. Further, the non-woven fiber aggregate refers to a web-like material made uniform by a method such as a card method, an airlaid method or a papermaking method.
[0048]
In this step, after spinning the fiber, a surfactant can be attached to the fiber surface for the purpose of preventing the static electricity of the fiber and imparting smoothness for improving the processability of the fiber molded body. The type and concentration of the surfactant are appropriately adjusted according to the application. As a method of adhesion, a roller method, a dipping method, a pad dry method, or the like can be used. The attachment may be performed in any of a spinning process, a drawing process, and a crimping process. Furthermore, it is also possible to attach the surfactant after molding to, for example, a fiber molded body other than the spinning process, the stretching process, and the crimping process, regardless of whether the fibers are short fibers or long fibers.
[0049]
The fiber length of the split-type composite fiber of the present invention is not particularly limited. However, when a web is produced using a card machine, generally 20 to 76 mm is used. In the papermaking method and airlaid method, Those having a fiber length of 2 mm to 20 mm are preferably used. When the fiber length is less than 2 mm, the fiber moves due to physical impact, and the fiber itself is less likely to receive energy necessary for division. Further, when the fiber length greatly exceeds 76 mm, it is difficult to form a web with a card machine or the like, and it is difficult to obtain a uniform web.
[0050]
As an example of a method for producing a fiber molded body made of the split conjugate fiber of the present invention, a method for producing a nonwoven fabric is illustrated. For example, by using the short fiber manufactured by the split type composite fiber manufacturing method, a necessary basis weight web is prepared by a card method, an airlaid method, or a papermaking method. Further, the web may be directly produced by a melt blown method, a spun bond method or the like. The web produced by the above method can be divided and finely divided by a known method such as a needle punch method, a high-pressure liquid flow treatment, a pressurized calender roll, etc. to obtain a fiber molded body. Furthermore, the fiber molded body can be treated by a known processing method such as hot air or hot roll. When a web composed of very short fibers such as papermaking is divided and finely divided by a known method such as needle punching or high-pressure liquid flow treatment, the fibers are moved simultaneously with the physical stress. Since the formation may be poor, 5 to 30% by weight of a fiber that is heat-sealed at a melting point lower than the melting point of the resin constituting the split-type conjugate fiber of the present invention is previously blended, and this low-melting fiber By performing heat treatment at a temperature at which the material is fused and preparing a heat-bonded nonwoven fabric, formation defects can be suppressed.
[0051]
The basis weight of the fiber molded body of the present invention is not particularly limited, but is 10 to 200 g / m.²Are preferred. The basis weight is 10g / m²If the ratio is less than 1, the split composite fiber may be divided and refined by physical stress such as high-pressure liquid flow treatment to produce the nonwoven fabric, which may result in a poorly formed nonwoven fabric. The basis weight is 200 g / m²If it exceeds 1, the basis weight is high, a high-pressure water flow is required, and it may be difficult to perform uniform division with good texture.
[0052]
The fiber molded body of the present invention can be used by mixing other fibers with the split-type composite fiber of the present invention as needed, as long as it does not interfere with the present invention. Examples of such other fibers include synthetic fibers such as polyamide, polyester, polyolefin, and acrylic, natural fibers such as cotton, wool, and hemp, regenerated fibers such as rayon, cupra, and acetate, and semi-synthetic fibers.
[0053]
Next, the high-pressure liquid flow process will be described. As a high-pressure liquid flow apparatus used for high-pressure liquid flow treatment, for example, one or more injection holes having a hole diameter of 0.05 to 1.5 mm, particularly 0.1 to 0.5 mm, with a hole interval of 0.1 to 1.5 mm. A device arranged in multiple rows is used. A high-pressure liquid flow obtained by jetting from the jet holes at high water pressure is made to collide with the web placed on the porous support member. As a result, the undivided split composite fiber of the present invention is entangled and simultaneously refined by the high-pressure liquid flow. The injection holes are arranged in a row in a direction perpendicular to the traveling direction of the web. As the high-pressure liquid flow, normal temperature or warm water may be used, and other liquid may be arbitrarily used.
[0054]
The distance between the injection hole and the web is preferably 10 to 150 mm. If this distance is less than 10 mm, the formation of the fiber molded body obtained by this treatment is disturbed. On the other hand, if this distance exceeds 150 mm, the physical impact of the liquid flow on the web is weakened, resulting in entanglement and fine division. May not be adequately applied. The processing pressure of this high-pressure liquid stream is controlled by the production method and the required performance of the fiber molded body, but in general, it is 20 kg / cm.²~ 200kg / cm²It is better to inject a high pressure liquid stream. Although it depends on the basis weight to be treated, etc., within the range of the treatment pressure, if the high-pressure liquid flow is processed by increasing the pressure from the low water pressure to the high water pressure sequentially, the entanglement and the web formation are not disturbed. Splitting and finening are possible. As the porous support member on which the web is placed when the high-pressure liquid flow is applied, for example, as long as the high-pressure liquid flow penetrates the web, such as a mesh screen or a perforated plate made of 50-200 mesh metal mesh or synthetic resin There is no particular limitation.
[0055]
In addition, after performing the high-pressure liquid flow treatment from one side of the web, by subsequently inverting the entangled web and performing the high-pressure liquid flow treatment, it is possible to obtain a dense and well-formed fiber molded body on both sides. it can. Furthermore, after performing a high-pressure liquid flow process, a water | moisture content is removed from the fiber molded object after a process. In removing this moisture, a known method can be employed. For example, after removing moisture to some extent using a squeezing device such as Mangroll, moisture can be completely removed using a drying device such as a hot air circulation dryer to obtain the fiber molded body of the present invention.
[0056]
When a web containing the split-type conjugate fiber of the present invention is subjected to a high-pressure liquid flow treatment in the above-described manner to obtain a dense fiber molded body, a split-type conjugate fiber having a conventional fiber cross section (FIG. 9, Compared to FIG. 10), it is easier to divide and less physical impact is caused by the high-pressure liquid flow. For this reason, since the formation of high-pressure liquid flow, which is the rate-limiting step of the nonwoven fabric processing process, is improved by reducing the pressure of the high-pressure liquid flow, for example, the pressure of the high-pressure liquid flow can be lowered. Or problems such as opening of through holes can be improved.
[0057]
As described above, even split-type composite fibers composed of similar resins that were considered to be most difficult to split, can be easily split, and a dense and well-formed fiber molded body can be obtained. Using these fiber molded bodies, it can be suitably used not only in the field of industrial materials such as battery separators and wipers, but also in the field of sanitary materials and clothing.
[0058]
Furthermore, a laminated fiber molded body (hereinafter referred to as A type) in which at least one sheet selected from a nonwoven fabric, a film, a knitted fabric, a woven fabric and the like is laminated on one side or both sides of the fiber molded body of the present invention, and further the fiber On the contrary, a laminated fiber molded body (hereinafter referred to as B type) in which the molded body is laminated on both surfaces of the sheet can also be used.
In the case of the A type, it is preferable to laminate the divided fiber molded product on one side or both sides of the sheet because the division efficiency is good. In the case of the B type, the fiber molded body is divided before and after the lamination, but the division treatment after the lamination is particularly preferable because an entanglement effect between the sheet and the fiber molded body is obtained. Any of these laminated fiber molded products (A) and (B) can be suitably used in the field of sanitary materials represented by absorbent articles such as diapers and napkins, and in the field of industrial materials such as wipers and battery separators. .
[0059]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention in detail, this invention is not limited by this. The terms and methods for measuring physical properties in Examples and Comparative Examples are as follows.
[0060]
(1) Melt flow rate: measured in accordance with JIS K7210.
Raw material polypropylene resin: Condition 14
Raw material polyethylene resin: Condition 4
Polyolefin resin after fiber molding: Condition 14
[0061]
(2) L / W measurement method
The following values were calculated from cross-sectional photographs of 10 undivided fibers selected arbitrarily, and L / W was calculated from the average value.
L: represents the longest part of the fiber cross-sectional shape in the direction in which the components are alternately adjacent to each other (see FIG. 1)
W: represents the contact surface direction of each component, that is, the thickness of the cross-sectional shape (see FIG. 1).
[0062]
(3) a / b measurement method
The following values were calculated from cross-sectional photographs of 10 undivided fibers selected arbitrarily, and a / b was calculated from the average value.
a: Average length of the outer peripheral surface of the component 1 fiber (see FIG. 1)
b: Average value of contact length of 1 component (see FIG. 1)
[0063]
(4) S1 / S2 measurement method
The area of S1 and S2 was calculated from a fiber cross-sectional photograph of 10 undivided fibers selected arbitrarily, and S1 / S2 was calculated from the average value. (See Figure 6)
S1: Area of a portion surrounded by a straight line connecting both ends of the long axis and bending or bending
S2: Cross-sectional area of the split composite fiber of the present invention
[0064]
(5) Spinnability
The spinnability at the time of melt spinning was evaluated in the following three stages according to the occurrence rate of yarn breakage.
○: No thread breakage occurs and operability is good.
Δ: Thread breakage once or twice per hour
X: Yarn breakage occurs 4 times or more per hour, and there is a problem in operation.
[0065]
(6) Stretch ratio
The following formula was used for calculation.
Stretch ratio = take-up roll speed (m / min) / feed roll (m / min)
[0066]
(7) Fiber tensile strength and elongation
According to JIS-L1013 method, it was measured at a yarn length of 100 mm and a tensile speed of 100 mm / min using an autograph AGS500D manufactured by Shimadzu Corporation.
[0067]
(8) Tensile strength and elongation of nonwoven fabric
The nonwoven fabric breaking strength of MD direction was measured for the nonwoven fabric of 5 cm width using Shimadzu Corporation autograph AGS500D. Measurement was performed at a test length of 100 mm and a tensile speed of 200 mm / min, and the measurement temperature was room temperature.
[0068]
(9) Measurement of split ratio
The non-woven fabric after the division is included with wax, and is sliced at right angles to the fiber axis with a microtome to create a sample piece. This is observed with a microscope, the cross-sectional image of the fiber is image-processed, and the total cross-sectional area (A) of the fibers in which 70% or more of the segments are divided and the total cross-sectional area (B) of the undivided fibers are measured. It was calculated by the following formula.
Division rate (%) = {A / (A + B)} × 100
[0069]
(10) Single yarn fineness after division
From the fineness before division and the number of segments that can be divided, the single yarn fineness after division fineness was calculated from the following equation.
Fineness after division (dtex / f) = fineness before division (dtex / f) / number of segments that can be divided (pieces)
[0070]
(11) Formation
Ten panelists evaluated as follows by the result of visually observing the fiber unevenness of the non-woven fabric (1 m square) after the split fine processing.
○: Seven or more people felt that there were few spots and no through holes.
Δ: 4 to 6 people felt that there were few spots and no through holes.
X: 3 or less felt that there were few spots.
[0071]
(12) High pressure liquid flow treatment
A web created by a roller card machine, an airlaid machine, a paper machine, etc. is placed on a conveyor belt made of 80 mesh plain weave. The conveyor belt speed is 20 m / min, and the nozzle diameter is 0.1 mm and the nozzle pitch is 1 mm. Passed and jetted high pressure liquid stream. First, after preliminary treatment (2 stages) at 2 MPa, 4 stages treatment was performed with a high-pressure liquid flow having a water pressure of 5 MPa. The web was inverted, and further processed in four stages with a high-pressure liquid flow having a water pressure of 5 MPa, to obtain a non-woven fabric that had been divided and refined. Here, the step is the number of times that the nozzle has passed directly under the nozzle.
[0072]
(13) Pressure (split) roll
Induction heating hydraulic two-roll clearance machine (manufactured by Yuri Roll Co., Ltd.)
Processing temperature: Atmospheric temperature
Treatment linear pressure: 40 kg / cm
Processing speed: 10m / min
[0073]
(14) Water pressure resistance
The measurement was performed according to JIS L1092.
[0074]
Examples 1-3
Polypropylene resin (propylene homopolymer) is used as the high melting point resin (A component), high density polyethylene resin is used as the low melting point resin (B component), and both the A component and B component resins are used using the split composite fiber die. A split type composite fiber having a fiber cross-sectional shape shown in FIG. 1 and having a single yarn denier of 7.5 dtex was spun. In the take-off process, an alkyl phosphate potassium salt was deposited. The obtained undrawn yarn was drawn at 90 ° C. and 4.1 times, attached with a papermaking finish, and then cut into 10 mm to obtain short fibers having a moisture content of 20% by weight.
To this short fiber, 20% by weight of polypropylene (core) / low-density polyethylene (sheath) sheath-core composite fiber (EAC fiber, Chisso Corp.) is added, and a papermaking method is performed using a square sheet machine (25 cm × 25 cm). The web. Using a Yankee dryer manufactured by Kumagai Riki Kogyo Co., Ltd., a web was obtained by drying at 105 ° C. for 3 minutes and pre-bonding. The web was subjected to the high-pressure liquid flow treatment and then dried with a dryer at 80 ° C. to obtain a fiber molded body.
[0075]
Example 4
Polypropylene resin (propylene homopolymer) is used as the high melting point resin (component A), high density polyethylene resin is used as the low melting point resin (component B), and the split composite fiber base is used. A split type composite fiber having a fiber cross-sectional shape shown in FIG. 2 with a single yarn denier of 7.5 dtex was spun. In the take-off process, an alkyl phosphate potassium salt was deposited. The obtained undrawn yarn was drawn at 90 ° C. and 1.5 times to give crimps and cut into 51 mm.
The obtained short fiber was used as a web with a roller card machine, and the high-pressure liquid flow treatment was performed on the web, and then dried with a dryer at 80 ° C. to obtain a fiber molded body. When the fiber molded body was used as a surface material for adult diapers, it was excellent in touch (soft feeling), non-woven fabric strength, etc., and very good as an absorbent article.
[0076]
Example 5
In accordance with Example 1 except that the split type composite fiber die for obtaining the fiber cross section shown in FIG. 3 was used, the split type composite fiber was spun and a fiber molded body was produced.
[0077]
Example 6
Except that linear low-density polyethylene was used instead of high-density polyethylene, spinning of split-type composite fibers and production of a fiber molded body were performed in accordance with Example 1.
[0078]
Example 7
Except that low-density polyethylene was used instead of high-density polyethylene, spinning of split-type composite fibers and production of a fiber molded body were performed in accordance with Example 1.
[0079]
Example 8
Polypropylene resin (propylene homopolymer) is used as the high melting point resin (component A), high density polyethylene resin is used as the low melting point resin (component B), and the split composite fiber base is used. A split type composite fiber having a fiber cross-sectional shape shown in FIG. 1 and having a single yarn denier of 20.0 dtex was spun. In the take-off process, an alkyl phosphate potassium salt was deposited. The obtained unstretched yarn was stretched at 90 ° C. and 4.1 times, attached with a papermaking finish, and then cut into 10 mm to obtain short fibers having a moisture content of 20% by weight. To this short fiber, 20% by weight of polypropylene (core) / low-density polyethylene (sheath) sheath-core composite fiber (EAC fiber, Chisso Corp.) is added, and a papermaking method is performed using a square sheet machine (25 cm × 25 cm). The web. Using a Yankee dryer manufactured by Kumagai Riki Kogyo Co., Ltd., a web was obtained by drying at 105 ° C. for 3 minutes and pre-bonding. The web was subjected to the high-pressure liquid flow treatment and then dried with a dryer at 80 ° C. to obtain a fiber molded body.
[0080]
Example 9
In accordance with Example 8, spinning of the split-type composite fiber and preparation of the fiber molded body were performed except that the split-type composite fiber base for obtaining the fiber cross section shown in FIG. 2 was used.
[0081]
The spinning / drawing conditions, fiber properties, shapes, nonwoven fabric properties, split ratios, and the like of Examples 1 to 9 are shown in Table 1 below.
[0082]
Example 10
Relative viscosity (measured at 20 ° C using an equal mixture of phenol and ethane tetrachloride as a solvent) 0.60 PET (Kanebo Co., Ltd., K101) is a high melting point resin (component A) and a low melting point resin. Using polypropylene resin (MFR: propylene homopolymer of 16 g / 10 min) as (B component), using a split type composite fiber die, the volume ratio of both the A component and B component resins is 50/50, A split type composite fiber having a fiber cross-sectional shape shown in FIG. 1 having a single yarn denier of 15.0 dtex was spun. In the take-off process, an alkyl phosphate potassium salt was deposited. The obtained undrawn yarn was drawn at 90 ° C. and 3.3 times, attached with a papermaking finish, and then cut into 10 mm to obtain short fibers having a moisture content of 20% by weight. To this short fiber, 20% by weight of polypropylene (core) / low-density polyethylene (sheath) sheath-core composite fiber (EAC fiber, Chisso Corp.) is added, and a papermaking method is performed using a square sheet machine (25 cm × 25 cm). The web. Using a Yankee dryer manufactured by Kumagai Riki Kogyo Co., Ltd., a web was obtained by drying at 105 ° C. for 3 minutes and pre-bonding. After the high-pressure liquid flow treatment, it was further dried with a dryer at 80 ° C. to obtain a fiber molded body.
[0083]
Example 11
A split type composite fiber was spun and a fiber molded body was produced in accordance with Example 1 except that the split type composite fiber base for obtaining the fiber cross section shown in FIG. 4 was used.
[0084]
Example 12
Polypropylene resin (propylene homopolymer) is used as the high melting point resin (component A), high density polyethylene resin is used as the low melting point resin (component B), and the split composite fiber base is used. A split type composite fiber having a fiber cross-sectional shape shown in FIG. 1 and having a single yarn denier of 7.5 dtex was spun. In the take-off process, an alkyl phosphate potassium salt was deposited. The obtained undrawn yarn was drawn at 90 ° C. and 4.1 times, attached with a papermaking finish, and then cut into 10 mm to obtain short fibers having a moisture content of 20% by weight. To this short fiber, 20% by weight of polypropylene (core) / low-density polyethylene (sheath) sheath-core composite fiber (EAC fiber, Chisso Corp.) is added, and a papermaking method is performed using a square sheet machine (25 cm × 25 cm). The web. The web was dried at 105 ° C. for 3 minutes and pre-adhered using a Yankee dryer manufactured by Kumagai Riki Kogyo Co., Ltd. to obtain a web. The web was subjected to the high-pressure liquid flow treatment and then dried with a dryer at 80 ° C. to obtain a fiber molded body.
[0085]
Example 13
Polypropylene resin (propylene homopolymer) is used as the high melting point resin (A component), high density polyethylene resin is used as the low melting point resin (B component), and both the A component and B component resins are used using the split composite fiber die. A split type composite fiber having a fiber cross-sectional shape shown in FIG. 1 was spun by the spunbond method. A composite fiber group discharged from a spinneret is introduced into an air soccer ball and pulled and drawn to obtain a composite long fiber having a single yarn denier of 2.0 dtex. After the same charge is applied and charged, the fibers are opened by colliding with the reflector, and the opened long fiber group is collected as a long fiber web on an endless net-like conveyor provided with a suction device on the back surface. The long fiber web was divided by a pressure roll and then processed by an embossing roll machine having an area ratio of 15% heated to 120 ° C. to obtain a fiber molded body.
[0086]
The spinning / drawing conditions, fiber properties, shapes, nonwoven fabric properties, split ratios, etc. of Examples 10 to 13 are shown in Table 2 below.
[0087]
Comparative Examples 1 and 2
Polypropylene resin (propylene homopolymer) is used as the high melting point resin (component A), high density polyethylene resin is used as the low melting point resin (component B), and the split composite fiber base is used. A split type composite fiber having a fiber cross-sectional shape shown in FIG. 1 and having a single yarn denier of 7.5 dtex was spun. In the take-off process, an alkyl phosphate potassium salt was deposited. The obtained undrawn yarn was drawn at 90 ° C. and 4.1 times, attached with a papermaking finish, and then cut into 10 mm to obtain short fibers having a moisture content of 20% by weight. To this short fiber, 20% by weight of polypropylene (core) / low-density polyethylene (sheath) sheath-core composite fiber (EAC fiber, Chisso Corp.) is added, and a papermaking method is performed using a square sheet machine (25 cm × 25 cm). The web. This was dried at 105 ° C. for 3 minutes using a Yankee dryer manufactured by Kumagai Riki Kogyo Co., Ltd. and pre-bonded to obtain a web. The web was subjected to the high-pressure liquid flow treatment and then dried with a dryer at 80 ° C. to obtain a fiber molded body. The spinning / drawing conditions, fiber properties, shape, nonwoven fabric properties, split ratio, etc. are shown in Table 2 below.
[0088]
Comparative Example 3
In accordance with Example 1 except that the split type composite fiber die for obtaining the fiber cross section shown in FIG. 9 was used, the split type composite fiber was spun and a fiber molded body was produced. The spinning / drawing conditions, fiber properties, shape, nonwoven fabric properties, split ratio, etc. are shown in Table 2 below.
[0089]
Comparative Example 4
In accordance with Example 1 except that the split type composite fiber die for obtaining the fiber cross section shown in FIG. 10 was used, the split type composite fiber was spun and a fiber molded body was produced. The spinning / drawing conditions, fiber properties, shape, nonwoven fabric properties, split ratio, etc. are shown in Table 2 below.
[0090]
Comparative Example 5
Spinning of the split-type composite fiber and preparation of the fiber molded body were performed in accordance with Example 13 except that the split-type composite fiber die for obtaining the fiber cross section shown in FIG. 10 was used. The spinning / drawing conditions, fiber properties, shape, nonwoven fabric properties, split ratio, etc. are shown in Table 2 below.
[0091]
Examples 14 and 15
The basis weight of 10 g / m in the previous step (before the high-pressure liquid flow treatment) for obtaining a fiber molded body in accordance with Example 1²Web (abbreviated as A). Next, a high-density polyethylene (sheath) / polypropylene (core) sheath-core type composite fiber (ESC fiber, Chisso Corp.) 2.2 dtex × 51 mm short fiber was used, and the basis weight was 10 g / m.²Card web (abbreviated as B). After carrying out the said high pressure liquid flow process, what laminated | stacked A to the upper layer, B was laminated | stacked on the lower layer (Example 14), and A was laminated | stacked on the upper and lower layers, and B was laminated | stacked on the middle layer, respectively. The laminated fiber molded body was obtained by drying with a drier. Furthermore, when this laminated fiber molded body was used for a wiper for wiping, both Examples 14 and 15 showed very excellent wiping properties.
[0092]
Example 16
Polypropylene resin (propylene homopolymer) is used as the high melting point resin (component A), high density polyethylene resin is used as the low melting point resin (component B), and the split composite fiber base is used. A split type composite fiber having a fiber cross-sectional shape shown in FIG. 1 with a single yarn denier of 2.0 dtex is spun by the spunbond method, and the basis weight for the middle layer is 10 g / m.²Got the web. Next, in the combination of the resins, using a sheath core type composite fiber die, the A component is the core side, the B component is the sheath side, the volume ratio of both the A and B resins is 50/50, and the single yarn Spinning a composite fiber of denier 2.0dtex by the spunbond method, weight per unit area 5.0g / m²The above webs were laminated as upper and lower layers on the intermediate layer web, divided by a pressure roll, and then processed by an embossing machine having an area ratio of 15% heated to 120 ° C. to obtain a laminated fiber molded body. Furthermore, when the fiber molded body was used as a surface material for adult diapers, it was excellent in water pressure resistance, non-woven fabric strength, etc., and very good as an absorbent article.
[0093]
[Table 1]

[0094]
[Table 2]

[0095]
As is clear from Tables 1 and 2, the fiber molded body and the laminated fiber molded body obtained in each example of the examples of the present invention are divided at a higher split ratio even under the same conditions as in the comparative examples. That is, even without performing a high-pressure liquid flow treatment at a high water pressure as in the prior art, division and finening proceed easily, so even a nonwoven fabric with a relatively low basis weight can be produced without disturbing the formation, Furthermore, the cost of high pressure liquid flow treatment can be greatly reduced.
[0096]
【The invention's effect】
Since the split-type composite fiber of the present invention is very easy to split, it can be easily made into ultrafine fibers without adding any special additives for easy splitting and without increasing the physical impact. For this reason, when the split composite fiber of the present invention is used, a dense and well-formed fiber molded body and a laminated fiber molded body can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a fiber cross section of a split type composite fiber used in the present invention.
FIG. 2 is a schematic diagram of a fiber cross section of a split type composite fiber used in the present invention.
FIG. 3 is a schematic diagram of a fiber cross section of a split type composite fiber used in the present invention.
FIG. 4 is a schematic diagram of a fiber cross section of a split type composite fiber used in the present invention.
FIG. 5 is a schematic diagram of a fiber cross section of a split type composite fiber used in the present invention.
FIG. 6 is a schematic diagram showing an area (S1) surrounded by bending or bending and a cross-sectional area (S2) of a split-type conjugate fiber.
FIG. 7 is a schematic diagram of a fiber cross section of a split type composite fiber used in the present invention.
FIG. 8 is a schematic diagram of a fiber cross section of a split type composite fiber used in the present invention.
FIG. 9 is a schematic diagram of a fiber cross section of a split-type composite fiber used in a comparative example.
FIG. 10 is a schematic diagram of a fiber cross section of a split type composite fiber used in a comparative example.
[Explanation of symbols]
L: Represents the length of the longest section in the direction in which the components of the composite fiber are alternately adjacent to each other.
W: Represents the thickness of the cross-sectional shape in the contact surface direction of each component of the composite fiber.
a: Represents the length of the outer peripheral surface of a single component constituting the composite fiber.
b: Represents the contact length with one adjacent component constituting the composite fiber.
S1: An area of a portion surrounded by a straight line connecting both ends of the long axis and bending or bending.
S2: Represents the fiber cross-sectional area of the composite fiber.

Claims (16)

It is composed of at least two components of a thermoplastic resin, and in the fiber cross section, each component is alternately adjacent in the long axis direction, and the cross section is bent, curved , or flattened as a U shape, a horseshoe shape, or A composite fiber having a cross-sectional shape in which the U-shaped or horseshoe-shaped curved portion is compressed and flattened , and the composite ratio of the composite fiber is in the range of 10/90 to 90/10% by weight. In the fiber cross section of the composite fiber, the ratio (S1 / S2) of the area S1 surrounded by bending or bending to the cross sectional area S2 of the split composite fiber is 0.2 to 1.0, and the long axis L of the cross section A split type composite fiber for splitting and finening treatment by physical stress, wherein a ratio (L / W) of the axis to the minor axis W is 3 to 20. The ratio (a / b) of the contact length b between the outer peripheral surface length a of one component constituting the fiber and the adjacent component in the fiber cross section of the split-type conjugate fiber is 0.1 to 2.5. Split type composite fiber. The melt flow rate of at least two components of the thermoplastic resin constituting the fiber after fiber molding is 10 to 100 g / 10 minutes, and among the thermoplastic resins, the resin component having the highest melting point (hereinafter referred to as A) The ratio (MFR-A / MFR-B) of the melt flow rate (MFR-B) of the resin component having the lowest melting point (hereinafter referred to as component B) (MFR-B) is 0.1. The split-type conjugate fiber according to claim 1 or 2, which is -5. The split composite fiber according to any one of claims 1 to 3 , wherein the combination of at least two thermoplastic resins is a polypropylene resin and a polyethylene resin. The split-type composite fiber according to any one of claims 1 to 4 , wherein the split-type composite fiber has a single yarn fineness before splitting of 0.5 to 10 dtex and a single-fiber fineness after splitting of 0.5 dtex or less. A fiber molded body comprising at least 30% by weight or more of the split-type conjugate fiber according to any one of claims 1 to 5 , and 50% or more of the split-type conjugate fiber being split. The fiber molded body according to claim 6 , wherein the fiber molded body is a fiber assembly. The fiber molded body according to claim 6 or 7 , wherein the fiber molded body is a fiber assembly obtained by a spunbond method. The laminated fiber molded object formed by laminating | stacking a sheet | seat on the single side | surface or both surfaces of the fiber molded object of any one of Claims 6-8 . The laminated fiber molded object formed by laminating | stacking the fiber molded object of any one of Claims 6-8 on both surfaces of a sheet | seat. The laminated fiber molded body according to claim 9 or 10 , wherein the sheet is a sheet selected from at least one of a nonwoven fabric, a film, a knitted fabric, and a woven fabric. An absorbent article using the fiber molded body according to any one of claims 6 to 8 or the laminated fiber molded body according to any one of claims 9 to 11 . A wiper using the fiber molded body according to any one of claims 6 to 8 or the laminated fiber molded body according to any one of claims 9 to 11 . A battery separator using the fiber molded body according to any one of claims 6 to 8 or the laminated fiber molded body according to any one of claims 9 to 11 . A method for producing ultrafine fibers, comprising subjecting the split type composite fibers according to claim 1 to splitting and finening by physical stress. The method for producing ultrafine fibers according to claim 15, wherein the splitting and finening by physical stress is performed by a needle punch method, a high-pressure liquid flow treatment, or a pressurized calender roll.

Images