JP2010133044A - Hollow splittable conjugate fiber and method for producing ultrafine fiber nonwoven fabric using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hollow splittable conjugate fiber easily splittable at a final step while keeping the fiber shape in a midway step of post processing. <P>SOLUTION: The hollow splittable conjugate fiber is a conjugate fiber comprising two or more kinds of mutually noncompatible fiber-forming polymers and having a hollow shape, regulated so that the percentage of hollowness is within the range of 0.1-5%, and the proportion defective of hollow fiber formation is ≤5%. Preferably, the conjugate fiber is divided to 4-48 divisions, and the fineness is 0.15-10 dtex. Further preferably, the fiber-forming polymers are a polyamide-based polymer 1 and a polyester-based polymer 2, and the fiber-forming polymers are composed of two components in a volume ratio of from 20:80 to 80:20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a hollow split type composite fiber made of two or more types of fiber moldable polymers and having a hollow shape, and a method for producing an ultrafine fiber nonwoven fabric using the same. More specifically, the present invention relates to a hollow split type composite fiber that can be easily split in the final process while maintaining the fiber shape in the intermediate process of post-processing.

  Conventionally, fabrics that are excellent in quality and fine and have fine touch and drape properties have been put on the market, and ultrafine fibers are often used to obtain such fabrics. As a means for obtaining ultrafine fibers, there is a method of producing fine fibers from the beginning, but in order to produce more efficiently, many obtain composite fibers from different polymers of two or more components and obtain the fibers. A method is mainly employed in which the obtained fiber is divided and refined through processes such as extraction and extraction. In order to be superior in terms of process rationalization and process tone, a method is used in which a composite fiber that can be made into ultrafine fibers is manufactured in advance and made into a fabric, and then the fibers are thinned.

  For example, Patent Document 1 discloses that a separation-type composite fiber is divided into ultrafine fibers by applying a high-pressure membrane-like water stream to a long-fiber nonwoven fabric made of a separation-type composite fiber that does not require extraction equipment and an extraction process. Thus, there has been proposed a method for obtaining a bulky nonwoven fabric composed of ultrafine fibers that are not substantially three-dimensionally entangled. However, there is a problem that it is difficult to obtain three-dimensional entanglement, although the degree of fiber separation can be increased by the method of applying this high-pressure membrane water flow.

  Further, Patent Document 2 proposes a multi-divided hollow fiber having a hollow ratio of 25% or more and discontinuous divided holes in the fiber axis direction so that the division is more likely to occur. However, such a split splitting type fiber having a high hollow ratio and discontinuous split holes has a problem that halfway splitting is likely to occur in the middle of post-processing and the quality is not stable.

  In particular, in the production of non-woven fabrics made of ultrafine fibers, a method of making the split split composite fiber first non-woven fabric through a confounding process and then splitting it to make it ultrafine is essential to ensure the strength of the non-woven fabric. Otherwise, the fibers will be cut at the time of entanglement, and sufficient strength cannot be obtained, or the cut ends of the fibers will be scattered, resulting in a problem that the process environment is deteriorated and the quality of the nonwoven fabric is adversely affected. That is, there is a demand for a fiber that is not divided at the time of entanglement and that can be easily divided at the time of division processing after entanglement.

  However, with conventional exfoliated split type fibers, mechanically strong treatment that sufficiently entangles is liable to be damaged during entanglement, and conversely, exfoliated split fibers that do not divide during confounding do not cause subsequent division processing. There is a problem, and there has been a demand for a split type composite fiber that can achieve both splitting and confounding properties.

JP-A-4-30031 JP 2000-17519 A

  The present invention has been made against the background of the above-described prior art, and an object thereof is to provide a hollow split type composite fiber that can be easily split in the final process while maintaining the fiber shape in the intermediate process of post-processing. is there.

  The hollow split type composite fiber of the present invention is a composite fiber having a hollow shape composed of two or more types of fiber-forming polymers that are incompatible with each other, and the hollow ratio is in the range of 0.1 to 5%. And the hollow fiber formation defect rate is 5% or less. Furthermore, it is preferable that the composite fiber is divided into 4 to 48, and the fineness is 0.15 to 10 dtex. The fiber moldable polymer may be a polyamide polymer and a polyester polymer, or the fiber moldable polymer may be composed of two components, and the volume ratio may be 20:80 to 80:20. preferable.

  Another method for producing an ultrafine fiber nonwoven fabric of the present invention is characterized in that the hollow split type composite fiber of the present invention is entangled and split. Furthermore, it is preferable that the entanglement method is by needle punching, and the division method is a method in which the nonwoven fabric before division is immersed in a solution in advance and then divided by mechanical stress. Furthermore, the method for producing artificial leather is characterized in that the above-described hollow split type composite fiber of the present invention is entangled and split, and impregnated and solidified with a polymer elastic body.

  According to the present invention, there is provided a hollow split type composite fiber that can be easily split in the final process while maintaining the fiber shape in the intermediate process of post-processing.

  The hollow split type composite fiber of the present invention must be composed of two or more types of fiber-forming polymers that are incompatible with each other. The hollow split type composite fiber can form ultrafine fibers by splitting incompatible fiber-forming polymers in a later step.

  The fiber moldable polymer is not particularly limited as long as it is generally a polymer having fiber moldability, and has a separation ability between components by mechanical treatment. Among these, from the viewpoint of industrial productivity and high performance, the combination of incompatible polymers is preferably a combination of a polyamide polymer and a polyester polymer.

  Examples of polyamide polymers that are preferably used include nylon-6, nylon-66, nylon-610, nylon-11, nylon-12, and the like. On the other hand, examples of the polyester-based polymer include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, and a copolyester having these as a main component. In particular, in nonwoven fabrics that require denseness, such as nonwoven fabrics for artificial leather base materials, heat-shrinkable polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, and the main components thereof are used to impart heat shrinkability. It is preferable to use a copolyester.

  Among these, a combination of nylon-6 / polyethylene terephthalate is preferable in terms of production stability, cost, and the like. In addition, an additive such as polyoxyethylene glycol may be added to one or both of these fiber moldable polymers within the range that does not impair the object of the present invention, for the purpose of improving the separation property. it can. Similarly, carbon black, titanium oxide, aluminum oxide, silicon oxide, calcium carbonate, mica, metal fine powder, organic pigment, inorganic pigment, etc. are added to any of the fiber-forming polymers constituting the ultrafine fiber nonwoven fabric. In addition, these additives have an effect of increasing or decreasing the melt viscosity of the polymer as well as a coloring effect on the thermoplastic polymer, and are effective in adjusting the fiber cross-sectional shape.

  The hollow split type composite fiber of the present invention is further a composite fiber having a hollow shape, and it is essential that the hollow ratio is in the range of 0.1 to 5%. When the hollowness is less than 0.1%, the components adhere to each other at the center of the fiber, and the splitting property is lowered. Moreover, since it is difficult to maintain a uniform state in the central portion, there is a tendency that fiber division during the process passing due to non-uniformity tends to occur. On the other hand, if it exceeds 5%, the fiber breakage in the subsequent step, for example, the needle punching process proceeds, and it becomes difficult to obtain sufficient strength of the fiber structure. The hollowness is more preferably 1% or more, and particularly preferably 3 to 5%.

  Conventionally, it has been considered that a higher hollow ratio than 5% is preferable. However, the present inventors have found that this very low hollow ratio later generates ultrafine fibers. This was particularly noticeable in fibers that were very fine and divided by applying a strong physical impact in the subsequent process. One assumption is that when a physical impact is applied to the split-type fibers, if the hollowness is high, the impact is relaxed and does not contribute to the splitting. Only by limiting the hollow ratio to a very low value as in the present application, the fiber can be easily divided.

  In addition, it is essential that the hollow split type composite fiber of the present invention has a hollow fiber formation defect rate of 5% or less. If the hollow fiber formation defect rate exceeds 5%, even if the hollow rate is small and the division rate in the subsequent process is suppressed, it is divided before entering the subsequent process. It becomes difficult. Here, the hollow fiber formation defect rate is a ratio in which the components of the composite fiber are not bonded to each other and the hollow of the hollow fiber is not formed. Such a defect is likely to occur when, for example, each component discharged from each slit of the spinneret does not join immediately after the spinneret is discharged.

  The composite form of the hollow split type composite fiber of the present invention is a fiber having a hollow cross-sectional shape made of two or more types of fiber-forming polymers, and at least a part of the joining interface of each polymer is a fiber cross-sectional circle. It is preferable that it is in the form of a separation-dividing composite fiber that reaches the circumference and can be separated into each component by mechanical treatment or the like. In addition, it is desirable from the viewpoint of the separation property that one component is divided into a predetermined number by the other component. Among these, a cross-sectional shape in which one component is arranged radially between other components is preferable. Such a composite form can be obtained by performing composite spinning of two types of fiber-forming polymers using a known composite spinneret.

  The fineness before splitting of the hollow split type composite fiber of the present invention is suitably in the range of 0.15 to 10 dtex, and more preferably in the range of 2 to 5 dtex. If it is too thin, the productivity tends to be low, and if it is too high, it tends to be difficult to make ultrafine fibers even if it is divided. The fineness after division is preferably in the range of 0.01 to 0.35 dtex. The fineness after splitting of the hollow split composite fiber of the present invention is preferably as thin as possible, but if it is too thin, it tends to be difficult to ensure production stability. In addition, when the fineness is too high, it is difficult to secure a flexible texture peculiar to ultrafine fibers.

  Therefore, the number of divisions of the hollow split type composite fiber of the present invention is preferably 4 to 48 splits, and is particularly preferably 8 to 24 splits from the balance between the fineness of the ultrafine fibers after splitting and the ease of splitting. preferable. The volume ratio of each fiber-forming polymer constituting each divided ultrafine fiber is preferably in the range of 20:80 to 80:20, and particularly preferably in the range of 40:60 to 60:40. By changing the division ratio, it is possible to adjust the division property and strength.

  And it is preferable that the dispersion | variation in the fineness of the division component which consists of each fiber moldability polymer in a hollow division type composite fiber is small. By suppressing the variation in fineness to a low level, an impact is uniformly applied to each part of the composite fiber in the processing stage at the time of division, and a more uniform division can be performed.

  Furthermore, it is preferable that at least one of these divided ultrafine fibers is heat shrinkable. In order to impart heat shrinkability, for example, the spinning speed and the draw ratio after spinning, the drawing temperature, in the case of direct-spun type non-woven fabric, the temperature at the time of thinning by an air soccer or ejector used for pulling the fiber, the air pressure Can be obtained by adjusting.

  Further, as the length of the fiber in the present invention, it is more effective to be a continuous long fiber. Compared with the case of the short fiber form cut short, in the case of the long fiber, the quality deterioration due to the division in the middle process becomes large, so that the characteristics of the present application are sufficiently exhibited.

  Such a hollow split type composite fiber of the present invention is formed by, for example, laminating two or more types of fiber-forming polymers that are incompatible with each other, and continuously discharging from a slit hole, so that the hollow ratio is 1 to 5%. Can be obtained by the following method. And it is preferable that it is circular arc shape so that a hollow fiber may be easy to shape | mold as a slit hole. Furthermore, the slit hole is preferably one or two slit holes. When the number of slit holes is small, there are few bonding surfaces of the fiber-forming polymer with low adhesion that is bonded after being ejected from the slit holes, and it is not easily divided in the middle process, so the fiber has excellent passability in the subsequent process It becomes. Furthermore, it is industrially preferable that there are two slit holes. In addition, hollow cracking of fibers immediately after spinning (hollow fiber formation failure) is likely to occur when the hollow ratio is several percent or less. This is because the components adhere to each other due to slight disturbance in the central portion of the fiber, and non-uniformity is generated. However, by reducing the number of slits, the occurrence of non-uniformity can be reduced. .

  The value of L / W, which is the ratio of the width W of each slit to the length L of the slit, is preferably 4 or more. Furthermore, the L / W value is preferably in the range of 10 or less. When the value of L / W is smaller than 4, the strength of the joint portion tends to decrease and the hollow formability tends to decrease. So-called hollow cracks occur. More specifically, the slit width W is preferably 0.05 to 0.5 mm. The slit length L is preferably 0.2 to 5.0 mm.

  Another production method of the ultrafine fiber nonwoven fabric of the present invention is a production method which essentially involves entanglement and division treatment of the above-described hollow split type composite fiber of the present invention. Furthermore, as a method of entanglement, it is preferable to use a needle punch.

  More specifically, for example, the above-described hollow split type composite fiber is spunbonded, which is a typical spinning direct-bonding type nonwoven fabric molding method, or a drawn yarn that has been wound up by spinning / drawing is wound at high speed. It is also a preferred embodiment that the fibers are directly molded as a web by a known method such as collecting on the porous collecting surface as a web while weaving.

  The long fiber web made of the hollow split type composite fiber of the present invention thus obtained is laminated as necessary, or alone, preliminarily thermally bonded as necessary, once It is preferable to make a fiber structure such as a long-fiber non-woven fabric by winding or continuously performing an entanglement process such as a needle punch process.

  The hollow split type composite fiber of the present invention is suitable for a production method in which the fiber composite that has passed through the post-processing step as described above is further processed to be divided into ultrafine pieces. Since the hollow split type composite fiber of the present invention can be split ultrathinned at a stretch by a certain impact, etc., it keeps high process passability without causing ultrathinning until it becomes a fiber composite, and thereafter It was possible to obtain high-quality products by proceeding with ultra-fine division at once in the division process.

  As such a dividing method, the hitting-type dividing process is particularly desirable in that the division ultrafine division can be reliably performed. The striking-type splitting process can efficiently apply a shearing force in the thickness direction of the sheet, and can efficiently split the split split composite fiber into split ultrafine fibers. As equipment capable of performing the striking-type division process, a commercially available striking-type grinder for leather can be used. Furthermore, as a method of more completely dividing, it is preferable to immerse the nonwoven fabric before the division in a solution in advance and then divide it by mechanical stress.

  It is also possible to produce artificial leather by entanglement and division of the above-described hollow split type composite fiber of the present invention and impregnating and solidifying a polymer elastic body. As the polymer elastic body, those used in conventionally known artificial leather can be used. For example, water-based or solvent-based polyurethane is preferably used. Furthermore, when solvent-based polyurethane is used, it is preferable that the polymer elastic body obtained by coagulating a dimethylformamide solution of polyurethane by a wet coagulation method is porous coagulated.

  The hollow split type composite fiber of the present invention as described above can be applied to products with excellent quality because it can form ultrafine fibers with excellent processability and finally high split rate. Therefore, in addition to the above-mentioned ultrafine fiber nonwoven fabric and artificial leather, for example, the applications include clothing, interior materials, industrial materials such as interior materials, wipers such as industrial wipers and wiping cloth, bug filters and filtration. It can also be preferably used for filter applications such as cloth and medical hygiene materials.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In addition, unless otherwise indicated, the part and% in an Example are a basis of weight, and each measured value was calculated | required according to the following method, respectively, and unless otherwise indicated, a measured value measured 5 points | pieces. The average value.

(1) Hollow ratio Sampling is performed before dividing the split type composite fiber, and the percentage is obtained by dividing the area of the circle having the fiber outer diameter as the diameter and the area of the circle having the diameter of the hollow portion as the diameter. It calculated | required as the average value of a book.

(2) Hollow fiber formation defect rate (hollow crack rate)
Sampling is performed before splitting the split-type composite fiber, and when 100 fibers are discharged from the discharge slit, a part or more of the polymers are not connected to each other, and a hollow is not formed. The number of fibers in the state was counted and the ratio was expressed as a percentage.

(3) Splitting rate The splitting rate of the split type composite fiber is determined by taking a cross section after splitting at 200 times with an electron microscope, measuring the cross section of 100 fibers, and measuring the total area and undivided (completely split) The difference in the cross-sectional area of the filaments (not including, for example, those divided into about two or three) was divided by the total area. The larger the division ratio, the better the division.

(4) Fineness of ultrafine fiber The fineness of the undivided composite fiber was measured with a fineness measuring device (SERCH Co. LTD, model DC-21) at a test length of 2.5 cm and a load of 1 g, and this was measured. It was determined by dividing by the number (number of divisions) of the fiber moldable polymers existing in a mutually independent form within the cross section perpendicular to the fiber axis.

(5) Peel strength of non-woven fabric A test piece having a width of 2 cm and a length of 9 cm is cut out from the non-woven fabric after the division treatment, and a cello tape (registered trademark) having a width of 2 cm and a length of 1.5 cm is applied to the end of the test piece. Prepare PVC leathers of the same size, apply adhesives to each other, paste them together, leave a load of 30 kg and leave them at 80 ° C. for 3 hours. Thereafter, the test piece is taken out and cooled, and then, using a constant-speed extension type tensile tester, the test piece and the vinyl chloride leather are gripped on the non-adhered portion of the cello tape (registered trademark), and the tensile speed is 3 cm / min. The peeling stress after the initial peeling was taken as the peel strength, and was calculated per 1 cm width and per 100 g / m ^{2 of} sample weight.

(6) Polymer discharge state During composite spinning, the discharge state of the fiber-forming polymer discharged from the spinneret was observed, and the discharge state was rated according to the following criteria. Observations were made 4 hours and 24 hours after the start of composite spinning.
Level 1: The discharged yarn draws a substantially constant flow line and runs stably. Level 2: The discharged yarn repeatedly bends and bends when it is discharged from the die surface, and turns.
Level 3: The discharged yarn is greatly bent, repeatedly bent, or swiveled. Part of the polymer is in contact with the spinneret surface, and the yarn breakage occurs frequently.

(7) Non-woven fabric (fibre-molded body) fiber defects Each non-woven fabric obtained after 24 hours was rewound at a length of 500 m, and the mixed state of mass-formed drip etc. of the fiber-forming polymer was examined and counted as one defect. It was.

(8) Strength of non-woven fabric The test pieces after the split treatment with a width of 2 cm and a length of 9 cm were sampled with respect to the longitudinal direction and the transverse direction of the non-woven fabric, the test pieces were gripped with a chuck, the chuck interval was 5 cm, and the tensile speed was 5 cm / The strength at break was determined by taking the average value in the longitudinal direction and the transverse direction as the average value in terms of width 1 cm and sample weight per 100 g / m ² .

(9) Texture of nonwoven fabric Sensory evaluation of softness and tactile sensation by five evaluators was performed in five stages, and the average value was evaluated. It shows that it is so favorable that a number is large.

[Example 1]
Nylon-6 (intrinsic viscosity 1.2 in 98% concentrated sulfuric acid) dried at 120 ° C. was fed to the extruder, and 2 wt% of polyethylene glycol flakes with a molecular weight of 19000 and nylon were used before the extruder entrance on the nylon-6 side. 6 was mixed and melted at 245 ° C. Separately dried at 140 ° C., polyethylene terephthalate (intrinsic viscosity 0.62 in o-chlorophenol) copolymerized with 10 mol% of isophthalic acid was melted at 265 ° C. with an extruder different from the above. Subsequently, the nylon-6 mixture melt and the polyethylene terephthalate melt were weighed with a gear pump, introduced into a spin block kept at 260 ° C., and both polymer melt streams were combined at a weight ratio of 50/50 to be combined. A hollow forming slit having two slit holes on the same circumference and L / W of each slit being 4.3 (L: 0.65 mm, W: 0.15 mm) is a grid of 0.6 mm pitch It is continuously discharged at a rate of 1.0 g / min / hole from a rectangular spinneret of 20 cm × 120 cm in the array, cooled with cooling air, and then compressed with compressed air using an air soccer ball under the cap. Towed fast in minutes.

  The pulled composite fiber was collected with a width of 1 m on a net conveyor together with an air flow as a web composed of a long-fiber separated split composite fiber having a 16-part multilayer laminating section. Subsequently, the obtained web was passed through a pair of upper and lower embossed calender rolls heated to 100 ° C. and lightly heat-bonded.

Then, oil was applied to the web, 8 sheets were overlapped with a cross layer, and then entangled with a needle punch with a penetrate number of 1200 / cm ² to give a nonwoven fabric before division having a basis weight of 240 g / m ² and a thickness of 1.22 mm. Obtained. Next, after being immersed in warm water at 50 ° C., a peeling splitting process was performed at a speed of 6 m / min with a striking type splitting machine, and then a shrinking process was performed with a hot water bath at 70 ° C. to obtain an ultrafine fiber nonwoven fabric. Table 1 shows the physical properties of the obtained separation-dividing composite fiber and the ultrafine fiber nonwoven fabric.

[Example 2, Comparative Examples 1-3]
Except that the shape of the discharge slit was variously changed, a peelable split composite fiber and an ultrafine fiber nonwoven fabric were obtained in the same manner as in Example 1. Each physical property is shown in Table 1.

The schematic diagram which showed the fiber cross section of the split type composite fiber of this invention.

Explanation of symbols

1: Polyamide polymer component 2: Polyester polymer component

Claims (9)

  A composite fiber having a hollow shape made of two or more types of fiber moldable polymers that are incompatible with each other, the hollow ratio is in the range of 0.1 to 5%, and the hollow fiber formation defect rate is 5%. A hollow split type composite fiber characterized by:   The hollow split type composite fiber according to claim 1, wherein the composite fiber is divided into 4 to 48 parts.   The hollow split type composite fiber according to claim 1 or 2, wherein the fineness is 0.15 to 10 dtex.   The hollow split type composite fiber according to any one of claims 1 to 3, wherein the fiber moldable polymer is a polyamide polymer and a polyester polymer.   The hollow split type composite fiber according to any one of claims 1 to 4, wherein the fiber moldable polymer is composed of two components, and the volume ratio thereof is 20:80 to 80:20.   A method for producing an ultrafine fiber nonwoven fabric, comprising entangling and dividing the hollow split composite fiber according to any one of claims 1 to 5.   The method for producing an ultrafine fiber nonwoven fabric according to claim 6, wherein the entanglement method is a needle punch.   The method for producing an ultrafine fiber nonwoven fabric according to claim 6 or 7, wherein the dividing method is a method in which the nonwoven fabric before division is immersed in a solution in advance and then divided by mechanical stress.   A method for producing artificial leather, wherein the hollow split type composite fiber according to any one of claims 1 to 5 is entangled and split, and a polymer elastic body is impregnated and solidified.

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