Composite fiber manufacturing method

Abstract

To provide a manufacturing method capable of improving production efficiency and stably obtaining a composite fiber with excellent quality for an extended period of time, in a direct spinning drawing method.SOLUTION: The manufacturing method of the composite fiber, formed by bonding a polyester and a polyamide in a longer direction, carries out melt-spinning using the polyester with a melt index at 290°C of 1.50 g / 10 min or more and less than 2.50 g / 10 min, and the polyamide with the melt index at 290°C of 1.50 g / 10 min or more and less than 2.50 g / 10 min.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing bicomponent fibers made of polyester and polyamide. [Background technology]

[0002] Conventionally, a method for producing composite fibers containing polyester and polyamide as components has been the two-stage process (comb process) in which undrawn yarns collected in a spinning process are drawn in a draw-twisting process. However, this method has the problem of low production efficiency.

[0003] On the other hand, methods for improving production efficiency include the direct spinning and drawing method (hereinafter sometimes referred to as the SPD method), in which the fiber is drawn without being taken up once after spinning, and the high-speed spinning method. However, when polyester and polyamide are used as components with different properties, the SPD method has poor spinning operability, and production technology has not been established. There have been many proposals for methods for producing composite fibers made of polyester and polyamide. For example, Patent Documents 1 to 3 propose methods for obtaining composite fibers of good quality with stable spinning operability over long periods of time by using a copolymerized polyamide in the polyamide to devise a cross-sectional shape, incorporating a metal into the polyamide, or lowering the viscosity of the polyester. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-270207 [Patent Document 2] Japanese Patent Application Publication No. 4-11020 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-322131 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the SPD method was used with reference to the proposals in Patent Documents 1 to 3, many yarn breakages occurred during long-term spinning, and it was not possible to stably obtain high-quality composite fibers.

[0006] Therefore, an object of the present invention is to solve the above problems and to provide a production method that can improve production efficiency even in the SPD method and stably produce high-quality composite fibers for a long period of time. [Means for solving the problem]

[0007] The present inventors have found that by adjusting the melt index of the polyester and polyamide to fall within a specific range, it is possible to stably obtain high-quality conjugated fibers not only by the two-stage production method but also by the SPD method. That is, the present invention is intended to solve the above problems and has the following configurations. (1) A method for producing a composite fiber formed by bonding polyester and polyamide in the longitudinal direction, the method comprising the steps of: (a) producing a polyester fiber having a melt index at 290°C of 1.50 g / 10 min or more but less than 2.50 g / 10 min; Ru and and a polyamide having a melt index at 290°C of 1.50 g / 10 min or more but less than 2.50 g / 10 min. (2) A method for producing a composite fiber according to (1), characterized in that the composite fiber is produced by a direct spinning and drawing method. (3) The fineness is 30 dtex or more and 120 dtex or less. (1) (2) A method for producing a composite fiber. (4) (1) characterized in that the number of filaments is 15 to 60 or (2) A method for producing the composite fiber described above. (5) The above (1) characterized in that the fiber cross section has polyester and polyamide alternately arranged. or (2) A method for producing the composite fiber described above. (6) A fiber cross-sectional shape is characterized in that polyamide having a radial shape and polyester having a shape complementary to the radial shape are alternately arranged (1). or (2) A method for producing the composite fiber described above. (7) The composite fiber is a splittable composite fiber (1) or (2) The manufacturing method described above. [Effects of the Invention]

[0008] According to the present invention, high-quality composite fibers with few yarn breakages can be stably obtained over a long period of time by the SPD method. Furthermore, the improvement in yield due to the improvement in yarn breakages can provide composite fibers with reduced production costs. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is an example showing a cross-sectional view of a composite fiber of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention is described in detail below. The present invention is a method for producing a bicomponent fiber made of polyester and polyamide.

[0011] The method for producing the conjugated fiber of the present invention may be a two-stage process in which an undrawn yarn is wound and then drawn. However, production by the SPD method in which an undrawn yarn is not wound but is drawn and then drawn is preferred from the viewpoint of improving production efficiency and cost efficiency.

[0012] Known polyesters include, for example, polyethylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and copolymer polyesters containing these as components, with polyethylene terephthalate being preferred for general purpose.

[0013] On the other hand, known polyamides include nylon 6, nylon 66, nylon 4, nylon 7, nylon 11, nylon 12, polymetaxylene adipamide, etc., and nylon 6 is preferred for general purpose.

[0014] The melt index of each of the polyester and polyamide at 290°C, which is the most important point of the present invention, must be 1.50 g / 10 min or more and less than 2.50 g / 10 min. If it is within this range, good-quality conjugated fibers can be stably obtained with little yarn breakage even when using the SPD method.

[0015] In particular, when the melt index of the polyamide is less than 1.50 g / 10 min, many thread breaks occur during the spinning stage, making production by the SPD method difficult.

[0016] The polyesters and polyamides are pre-dried before being melt-spun. In the case of polyethylene terephthalate, the moisture content after drying is preferably 5 ppm to 25 ppm, more preferably 10 ppm to 20 ppm. On the other hand, in the case of nylon 6, the moisture content after drying is preferably 70 ppm or less, more preferably 50 ppm or less. If the moisture content is within this range, good quality composite fibers can be stably obtained with little yarn breakage during spinning.

[0017] The above-mentioned dried polyester and polyamide are prepared, melted, and extruded using a conjugate spinneret. The spinning temperature is preferably 295 to 300°C. After extrusion, the material is cooled, and then an oil is applied and stretched. After the oil is applied, the material is taken up, for example, by a pretension roller (PTR) and a first godet roller (GR1), stretched between the GR1 and a second godet roller (GR2), and wound onto a bobbin to obtain a conjugate fiber. Here, the volume ratio of polyester to polyamide is preferably 2:1 to 3:1.

[0018] The single yarn fineness of the conjugated fiber in the present invention is preferably 0.5 to 10 dtex, more preferably 1 to 5 dtex. Within this range, good quality conjugated fibers can be stably obtained with little yarn breakage during spinning.

[0019] The cross-sectional shape of the composite fiber in the present invention is preferably such that polyester and polyamide are alternately arranged, and more preferably such that polyamide having a radial shape and polyester having a shape complementary to the radial shape are alternately arranged, an example of which is shown in Figure 1. Figure 1(a) shows a polyester (shaded area) with a shape that complements the radial polyamide divided into eight parts, and Figure 1(b) shows a polyester (shaded area) with a shape that complements the radial polyamide divided into four parts. [Example]

[0020] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples described below. The property values ​​in the following examples were measured by the following methods.

[0021] The physical properties were measured as follows. (1) Melt index of polyester Samples were taken from the dried chips and dried in a vacuum dryer at 180°C for 2 hours to obtain the specimen. A Toyo Seiki melt indexer (model F-F01) was used for the measurement. The sample was placed in a melt indexer preheated to 290°C, and a 2.16 kg weight was placed on top. The sample was extruded through an orifice with a diameter of 0.500 mm and a length of 8,000 mm. The mass of the polymer extruded in 60 seconds was measured, and the melt index was calculated using the following formula: Melt index (g / 10min) = [(n1 + n2 + n3) / 3] x 10 (n1 to n3 = sample mass) (2) Melt index of polyamide A sample was taken from the chips after the drying treatment and dried in a vacuum dryer at 150°C for 2 hours to obtain a sample, and the melt index was calculated in the same manner as for polyester, except that the sample was dried. (3) Fineness measurement method In accordance with JIS-L-1013, a small skein of yarn length 100 m was made using a measuring machine with a frame circumference of 1.25 m, and its mass was measured to calculate the apparent fineness. (4) Strength and elongation measurement method In accordance with JIS-L-1013, the strength (cN / dtex) and elongation (%) were determined when the sample broke at elongation using an AGS 1KNG Autograph (registered trademark) tensile tester manufactured by Shimadzu Corporation, with a sample length of 200 mm and a tensile speed of 200 m / min. (5) Spinning operability Composite fibers were spun using the SPD method and the convex spinning method. Those with good operability, i.e., three or fewer thread breakages within 24 hours, were rated as ◯, and those with poor operability, i.e., four or more thread breakages within 24 hours, were rated as ×.

[0022] Example 1 Polyethylene terephthalate (PET) with a melt index of 1.62 g / 10 min at 290 °C and a moisture content of 15 ppm after drying was melted at 285 °C as the polyester, and nylon 6 with a melt index of 2.13 g / 10 min at 290 °C and a moisture content of 37 ppm after drying was melted at 260 °C as the polyamide. The PET / nylon 6 structure was then formed so that the nylon 6 fiber had a radial cross section and the polyethylene terephthalate fiber had a shape that complemented the radial shape was divided into eight sections, as shown in Figure 1(a). A composite spinneret with a volume ratio of 2 / 1 and 25 holes was used to extrude the fiber at a spinning temperature of 295°C. After cooling, an oil was added, and the fiber was wound six times around a pretension roller (PTR) with a peripheral speed of 1140 m / min and a first godet roller (GR1) with a peripheral speed of 1160 m / min (78°C) before being taken up. The fiber was then wound six times around a second godet roller (GR2) with a peripheral speed of 3800 m / min (118°C) and drawn between GR1 and GR2 using the SPD method to obtain a composite fiber of 84 dtex / 25 f.

[0023] Example 2 A 56 dtex / 25 f composite fiber was obtained by the same manufacturing method as in Example 1 except for changing the fineness.

[0024] Example 3 A 56 dtex / 28 f composite fiber was obtained by the same production method as in Example 1, except that the fineness and fiber cross-sectional shape were changed so that the radial nylon 6 and polyethylene terephthalate having a shape complementary to the radial shape were divided into four, as shown in Figure 1(b).

[0025] Comparative Example 1 Polyethylene terephthalate (PET) with a melt index of 1.62 g / 10 min at 290 °C and a moisture content of 13 ppm after drying was melted at 285 °C as the polyester, and nylon 6 with a melt index of 0.67 g / 10 min at 290 °C and a moisture content of 32 ppm after drying was melted at 270 °C as the polyamide. The nylon 6 fiber had a radial cross section, and the polyethylene terephthalate fiber had a shape that complemented the radial shape. The fibers were extruded at a spinning temperature of 295 °C using a composite spinneret with 25 holes and a PET / nylon 6 volume ratio of 2 / 1. After cooling, an oil agent was applied, and the peripheral speed was increased to 1000 rpm. Degree 1 The fiber was wound six times around the first godet roller (GR1) at 240 m / min (72°C) and taken up, then wound six times around the second godet roller (GR2) at a peripheral speed of 3800 m / min (130°C), and drawn between GR1 and GR2 using the SPD method to obtain a 56 dtex / 25 f composite fiber.

[0026] Comparative Example 2 A 56 dtex / 28 f composite fiber was obtained by the SPD method in the same manner as in Comparative Example 1, except that the cross-sectional shape of the fiber was changed so that the radial nylon 6 and the polyethylene terephthalate having a shape complementary to the radial shape were divided into four sections as shown in Figure 1(b).

[0027] [Reference example 1] The same raw materials as in Comparative Example 1 were used and melted at 270°C. The fiber cross section was divided into eight segments, as shown in Figure 1(a), consisting of radial nylon 6 and polyethylene terephthalate having a shape complementary to the radial shape. The fibers were extruded at a spinning temperature of 295°C using a conjugate spinneret with 25 holes and a PET / nylon 6 volume ratio of 2 / 1. After cooling, an oil was applied, and the undrawn yarn was taken up once at a spinning speed of 1,060 m / min using a convex spinning method and drawn in a drawing step to obtain a 56 dtex / 25 f composite fiber.

[0028] Table 1 shows the manufacturing methods of the conjugated fibers obtained in Examples 1 to 3, Comparative Examples 1 and 2, and Reference Example 1, as well as evaluations of the melt index, fineness, number of filaments, strength, elongation, and spinning operability of the polyester and polyamide.

[0029] [Table 1]

Claims

1. A method for producing a conjugated fiber formed by bonding polyester and polyamide in the longitudinal direction, comprising: A method for producing a composite fiber, comprising melt spinning a polyester having a melt index at 290°C of 1.50 g / 10 min or more and less than 2.50 g / 10 min and a polyamide having a melt index at 290°C of 1.50 g / 10 min or more and less than 2.50 g / 10 min.

2. 2. The method for producing the composite fiber according to claim 1, wherein the composite fiber is produced by a direct spinning and drawing method.

3. 3. The method for producing a conjugate fiber according to claim 1, wherein the fineness is 30 dtex or more and 120 dtex or less.

4. The method for producing a composite fiber according to claim 1 or 2, characterized in that the number of filaments is 15 to 60.

5. 3. The method for producing a composite fiber according to claim 1 or 2, wherein the cross-sectional shape of the fiber is such that polyester and polyamide are arranged alternately.

6. 3. The method for producing a conjugate fiber according to claim 1, wherein the polyamide fibers have a radial cross-sectional shape and the polyester fibers have a shape complementary to the radial cross-sectional shape and are arranged alternately.

7. 3. The method according to claim 1, wherein the composite fiber is a splittable composite fiber.

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