JPS6311445B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing irregular cross-section polyester fibers (including hollow polyester fibers) that have excellent dyeability (high degree of dyeability), particularly for use in clothing, carpets, and other applications requiring dyeability and bulk. The present invention relates to a method for producing polyester fibers of irregular cross-section useful in various fields of application using streamlined means with good productivity and operability. It has been known that polyester fibers mainly composed of ethylene terephthalate units containing metal salt sulfonate groups are dyeable with basic dyes and are used for clothing and carpets that require high dyeability. However, this type of basic dye-dyeable polyester fiber cannot be dyed in a deep color when dyed at 100°C under normal pressure (boil) unless the sulfonate group content is increased to 5 to 10 mol% or more based on terephthalic acid. Furthermore, the higher the sulfonate group content, the higher the production cost of the polymer, and the more difficult polymerization and spinning become. The method used was to melt-spun polyester (approximately 0.5 to 4 mol%) and dye the resulting fibers at high temperature and pressure, or to carryer dye at 100° C. and normal pressure. However, high-temperature and high-pressure dyeing is harsh for this type of polyester fiber, and there are disadvantages in that the mechanical properties of the fiber inevitably deteriorate, and the dyeing cost is also high. Further, carrier dyeing involves a cost-increasing factor in that the waste liquid must be treated to make it non-polluting, and is therefore not very preferable. In order to solve this problem, a method was proposed in 1973 that produced highly oriented undrawn yarn by high-speed spinning and stretched it under specific stretching conditions, thereby making it possible to dye it deeply by ordinary boiling dyeing at 100°C. - Shown in Publication No. 89632.
In addition, for carpets and clothing applications where particularly high bulkiness is required, it is widely practiced to impart bulkiness by making the cross-sectional shape of the fibers irregular, such as trilobal or hollow fibers. It is. However, when the basic dye-dyeable polyester fiber described above is drawn, many "cracks" occur on the fiber surface, which often causes fuzz or yarn breakage during the drawing process, mechanical crimping process, dyeing process, spinning process, etc. do. This tendency is especially increased in the case of irregular cross-section fibers. The cause of this "cracking" has not yet been elucidated, but it is thought to be unique to this type of polyester fiber.In particular, the longer the time the so-called undrawn yarn is left until the spun undrawn fiber is subjected to drawing, the more the fuzz will increase. It has also become clear that thread breakage increases. to solve this problem
If a direct spinning/drawing method is adopted in which the undrawn yarn obtained by spinning at a spinning speed of around 1000 m/min is immediately stretched without being wound up, the above-mentioned "cracking" problem can be solved to some extent, but the Because the drawn yarn has a low birefringence Δn, it is not possible to obtain deep dyeing properties with normal 100°C boil dyeing. In this direct spinning/drawing method, if the spinning speed is set to a high speed of about 3000 m/min and the spinning is highly oriented and undrawn, it is possible to obtain a polyester fiber with strong dyeability and no cracks by normal 100°C boil dyeing. The high-speed spinning and high-speed drawing require large-scale equipment, and there are also problems such as yarn unevenness due to yarn slipping on the rollers. The present inventors have solved all of the above-mentioned drawbacks and problems, and have produced polyester fibers that are deep dyed with basic dyes and have high bulk properties and are useful for applications such as clothing and carpets at low cost. As a result of extensive research into methods for achieving this goal, we have finally achieved the present invention, which achieves the desired objective. That is, in the present invention, a polyester mainly composed of ethylene terephthalate units containing a metal sulfonate group is melt-spun through a spinneret having a non-circular spinning hole, the spun yarn is once cooled by a cooling air flow directly under the spinneret, and then Before the yarn reaches the drawing device, it passes through a heating zone of 80°C or higher, and is drawn under a temperature gradient by the frictional force with the air, making it into drawn fibers all at once. Pickup speed V
(m/min), yarn take-up speed, and cooling air flow speed
The yarn is spun so that the relationship with Vq (m/sec) satisfies the following formulas (1) to (5) at the same time.It has excellent dyeability and has a cross-sectional deformation ratio S of 5000/√ or more. A method for producing polyester fibers with irregular cross sections. 2000≦V≦6000 ...(1) Vq≧-2.75 (V×10 ^-3 ) +8.5 ...(2) Vq≧0.09 (V×10 ^-3 ) ² −0.81 (V×10 ^-3 )+2 .3 ……(3) Vq≦−0.17 (V×10 ^-3 )+3.6 ……(4) Vq≦3.2 ……(5) [However, S is the length of the contour line in the fiber cross section (cm ) divided by the cross-sectional area of the fiber cross-section (cm ² ) (cm ⁻¹ ), d indicates the single yarn denier. ] In the present invention, the polyester mainly composed of ethylene terephthalate units containing a metal sulfonate group has the formula:

[Formula] (wherein Z is a trivalent aromatic or aliphatic hydrocarbon group, and R is

[Formula] lower alkyl,

【formula】

[Formula] lower alkyl, -(CH ₂ )nOH, - O-(CH ₂ )n-[O(CH ₃ )n]m-OH and

isophthalic acid, adipic acid, At least one difunctional acid such as p-oxybenzoic acid or a derivative thereof
seeds and/or diethylene glycol, propylene glycol, 1,4-butanediol, 1,
By copolymerization in the presence or absence of a dihydric alcohol such as 4-hydroxymethylcyclohexane, or by blending the polymer thus obtained into a polyester in which at least 80 mol% of the repeating units consist of ethylene terephthalate. Manufactured by As the dicarboxylic acid or diol containing a metal salt sulfonate group represented by the above formula which is particularly suitable for use in the present invention, 3,5-di(carbomethoxy)
Sodium benzenesulfonate, potassium 3,5-di(carbomethoxy)benzenesulfonate,
1,8-di(carbomethoxy)naphthalene-3-
Examples include sodium sulfonate, potassium 2,5-di(carbomethoxy)benzenesulfonate, potassium 2,5-bis(hydroxyethoxy)benzenesulfonate, and the like. It is necessary that the sulfonate group-containing ester unit in the raw material polyester be 0.5 mol% or more, preferably
1.5 mol% or more and 5 mol% or less. The intrinsic viscosity of the raw material polyester (measured at 30°C in a mixed solvent of phenol/tetrachloroethane = 6/4) is 0.35.
A range of ~0.55, particularly 0.37-0.52 is desirable. Furthermore, in order to obtain even deeper dyeing properties, it is preferable to use a polyester blended or copolymerized with polyoxyalkylene glycol or a functional derivative thereof. The irregular cross-section polyester fiber in the present invention is
The cross-sectional deformation ratio S satisfies 5000/√ or more. [However, in formula (5), S is the cross-sectional deformation ratio (cm ^-1 ) defined as the value obtained by dividing the length (cm) of the contour line in the fiber cross-section by the cross-sectional area (cm ² ) of the fiber cross-section ,
d indicates the single yarn denier. ] However, in the case of hollow fibers that have a hollow part in the cross section of the fiber (deformed hollow fibers, circular hollow fibers, etc.), the length of the contour line in the fiber cross section is the length of the outer peripheral contour line and the inner circumference of the hollow part. It shall be calculated as the total length of the contour line. Further, in order to obtain particularly high bulkiness, it is preferable that the cross-sectional deformation ratio S is 5200/√ or more. For example, the cross-sectional deformation ratio S of the hollow cross-section fiber shown in Figure 1a is 5000/√, and the cross-sectional deformation ratio S of the trilobal fiber shown in Figure 1b is
6950/√, and the cross-sectional deformation ratio S of the circular solid cross-section fiber shown in FIG. 1c is about 4000/√. Circular solid cross-section fibers or irregular cross-section fibers with a cross-sectional deformation ratio S of less than 5000/√ have low bulk and are unsuitable for carpets or clothing, which require bulk. In addition, the larger the cross-sectional deformation ratio of the fiber, the larger the bulkiness and the larger the birefringence Δn of the undrawn yarn.
Therefore, the dyeability is also likely to improve. As a spinneret for such a yarn with an irregular cross section, a conventionally known spinneret for producing yarn with an irregular cross section can be used. In other words, a spinneret with a non-circular spinning hole in which the cross-sectional shape of the fiber is hollow, flat, triangular, square, polygonal, such as pentagonal, hollow, porous, U-shaped, and various other variations thereof, is used. Can be used. Melt spinning is carried out in a conventional manner using such a spinneret. The yarn melt-spun from the spinneret is then cooled using a suitable cooling medium such as a cooling air stream or liquid mist. The use of liquid mist as a cooling medium increases cooling efficiency and is particularly advantageous for thick denier yarns. Furthermore, the greater the cooling effect, the greater the birefringence of the undrawn yarn, and thus the dyeability is improved. The yarn thus cooled once is then passed through a heating zone at 80° C. or higher and drawn under a temperature gradient by the frictional force with the air to form drawn fibers all at once.
There are no particular limitations on what forms the heating zone, and any means for heating the yarn may be used, but a non-contact type is particularly preferred when the take-up speed is high. However, the amount of heat required to heat the yarn is less with the contact type, so when using a contact type yarn heating means, it is important to select a surface material with a low coefficient of friction and high wear resistance. Good.
The temperature of the heating zone is preferably 80°C or higher, particularly 115°C or higher, and lower than the melting point of the yarn. As the heating means, electric heating, flame heating, heated air, heated steam, etc. can be used. Note that in order to prevent the yarn from being disturbed by the air entrained in the yarn and a decrease in heating efficiency, it is preferable to separate the entrained flow of the yarn immediately before introducing it into the heating zone. The temperature immediately before the yarn is introduced into the heating zone is not particularly limited, but it must be sufficiently cooled to a temperature that will not cause the yarn to melt when it comes into contact with an entrained flow separation device. It is preferable that the temperature is lower than the second-order transition temperature. The yarn is drawn in this heating zone under a temperature gradient.
This stretching is performed by a force generated by frictional force between the yarn and the atmosphere (air) surrounding the yarn. The thus drawn yarn is then applied with an oil agent by an oiling roller and then taken off by a take-off roller provided vertically below the spinneret. Any device that can regulate the yarn running speed may be used as a device for taking up the yarn, and a take-up roller called a godet roll is usually used, but in the field where it is used as a staple fiber, the yarn speed cannot be regulated. A tow cutter designed to simultaneously cut the yarn to a predetermined length can be used as the take-off device. In this case, it is very effective if the total denier of the yarn is 1000 denier or more. In the present invention, in order to draw the yarn in the heating zone, the drawing speed is 2000 m/min or more, preferably 3000 m/min or more.
A withdrawal speed of min or higher is required. When imparting bulkiness, it is required to crimp the fiber, but normally it is necessary to mechanically crimp the drawn fiber at any stage before it is taken up by a pulling device. Conventionally, it has been extremely difficult to provide satisfactory mechanical crimping at high speeds of 2000 m/min or higher. However, by adopting spinning conditions that simultaneously satisfy the above formulas (1) to (5), the present inventors have made it possible to apply crimp without a mechanical crimp-applying means, and also have a high degree of three-dimensional crimp. It has been found that bulky fibers particularly suitable for carpets and clothing can be obtained. In this case, the effect becomes even more pronounced by heat-treating the drawn yarn or staple fiber. Next, the meaning of each of the above formulas (1) to (5) will be explained. Regarding formula (1): If the yarn take-up speed is not less than 6000 m/min, the yarn running speed until reaching the heating zone will be 3000 m/min.
min, and yarn breakage directly under the spinneret increases. The reason why yarn breakage increases when the yarn running speed exceeds 3000 m/min before reaching the heating zone is not yet fully understood, but
In general, when spinning using a spinneret with a non-circular spinning hole, if the yarn traveling speed before reaching the heating zone exceeds 3000 m/min, oriented crystallization will progress significantly, and this It is thought that crystallization is the cause of thread breakage. For this reason, the yarn take-up speed needs to be 6000 m/min or less. Regarding formula (2): Formula (2) is a requirement for obtaining a yarn that satisfies the strength, elongation, and physical properties required for clothing or carpet use. That is, unless the flow rate Vq of the cooling air stream is increased as the yarn take-up speed V is lower, it is not possible to obtain fibers having sufficiently satisfactory strength and elongation physical properties by the method of the present invention. Regarding formula (3): Formula (3) is a requirement for obtaining a fiber having good bulk and three-dimensional crimp. In other words, equation (3) is 1/
ρ′ (ρ′ is defined as the average helical radius (mm) per 10 helical crimps that occurs when a single fiber is subjected to free shrinkage treatment at 160°C dry heat for 60 seconds) is 1.0 or more. . A fiber that satisfies 1/ρ'≧1 is a fiber that has three-dimensional crimp and is excellent in bulk. In order to obtain even better bulky fibers, it is recommended that the requirements expressed by the following formula be satisfied. Vq≧0.125 (V×10 ^-3 ) ² −1.25 (V×10 ^-3 ) + 3.75 ……(6) Equation (6) is 1/ρ (ρ is the single fiber of the taken yarn and the free Spiral curling that occurs when
The average helical radius (mm) per 10 pieces is
The condition is 1.0 or more. In this case, it is possible to obtain three-dimensionally crimped fibers with high bulkiness without heat-treating the pulled yarn or cut staple fibers, so the advantage is that the heat treatment step for developing latent crimping can be omitted. be. Regarding equations (4) and (5): Equations (4) and (5) are requirements for preventing single yarns from fusing together and causing yarn breakage due to yarn shaking caused by cooling air currents. The irregular cross-section fibers discharged from non-circular spinning holes have a larger surface area per unit volume than circular solid fibers of the same fineness, so they have a large cooling airflow resistance and are therefore prone to yarn shaking, which results in a high cooling airflow velocity. If it is too long, the yarn will swing violently, and the single yarns will fuse together, resulting in an increase in yarn breakage. As a result of various studies, the present inventors have found that adopting spinning conditions that satisfy equations (4) to (5) is effective in fusing single yarns together and breaking yarns by cooling air flow. Ta. In Figure 2, the vertical axis shows the flow velocity of the cooling air flow.
Vq (m/sec) is plotted on the horizontal axis, and spinning take-off speed V (m/sec) is plotted on the horizontal axis.
min), and displays the straight lines and curves for the cases indicated by equal signs with respect to equations (1) to (4) and (6) of the present invention, respectively, and is surrounded by diagonal lines in Figure 2. The above range is the spinning condition of the present invention that satisfies the above formulas (1) to (4) at the same time. The single fiber denier of the irregular cross-section polyester fibers used in the present invention varies depending on the use, but 1 to 5 deniers are used for general clothing, and 5 to 25 deniers are used for carpets. In order to use the irregular cross-section polyester fibers produced by the present invention as short fibers, it is necessary to apply mechanical crimp to improve spinnability, especially when the crimp properties are insufficient by spinning and drawing alone. Although necessary, a mechanical crimping step may be provided consecutively to the yarn take-up step of the present invention, or the yarn may be wound after being taken or stored in a tow can, and then the tows may be pulled together and crimped at a lower speed. Mechanical crimping may be applied. Furthermore, when used as long fibers, false twisting, air jet processing, etc. may be applied continuously or discontinuously. The first characteristic of the fibers produced according to the present invention is that they do not have any "scratches" on the surface, but they also have less sag when crimped under high loads (approximately 1 g/d) and are durable. It also has the characteristic of being expensive. The present invention makes it possible to obtain polyester fibers of irregular cross-section with high bulkiness and high dyeability for use in clothing or carpets by a streamlined method, and the fibers thus obtained have no "cracks" on their surfaces. The operability in post-processing is also much better than conventional ones. In order to more specifically demonstrate the effects of the present invention, examples are shown below.The dyeing rate in the examples is such that a dyeing solution was prepared such that the dye amounted to 5% (by weight) of the fiber to be dyed. It is calculated by measuring the dye concentration of the dye stock solution before dyeing and the residual dyeing solution after dyeing using a colorimetric method.If the dyeing solution becomes completely transparent, the dyeing rate is 100%. If the colorimetric concentration of the residual dye solution is half that of the dye stock solution, the dyeing rate is 50%, and if the colorimetric concentration of the dye residual solution and the dye stock solution are the same, the dyeing rate is 0%. Example 1 During transesterification polycondensation of dimethyl terephthalate and ethylene glycol, 2 mol% of sodium 3,5-di(carbomethoxy)benzenesulfonate was added to dimethyl terephthalate, and the intrinsic viscosity IV was 0.50 (phenol/tetra A copolymerized polyester (measured at 30°C in a mixed solvent of chloroethane = 6/4) was obtained. This polyester is melted and discharged at a spinning temperature of 290°C from a spinneret each having 50 spinning holes each having a Y-shape and a C-shape with different slit dimensions (width and length), and the flow rate is directly below the spinneret. A cooling air flow of 1.0 m/sec is blown almost orthogonally to the yarn, and the air is passed through the center of an 80 cm long annular electric heater (ambient temperature 310°C) located 3 m below the spinneret. After stretching due to frictional force with
Single yarn denier drawn at a speed of 3700m/min
Eight different cross-sectional polyester fibers with different cross-sectional shapes and cross-sectional deformation ratios were produced at 20 d. The cross-sectional shape is as shown in FIG. The physical properties of these eight types of fibers are shown in Table 1.

【table】

Table 1 shows that the present invention makes it possible to produce irregular cross-section polyester fibers with no cracks on the fiber surface and excellent dyeing rate and bulkiness.
In particular, it can be seen that unless the cross-sectional deformation ratio S is 5000/√ or more, bulky fibers with even better bulkiness and dyeing rate cannot be obtained. Comparative Example 1 For comparison, the same copolymerized polyester as in Example 1 was melt-spun using the same spinneret as in Example 1 by a normal melt-spinning method, cooled by blowing cooling air, and then spun for 1000 m. The undrawn yarn thus obtained was wound once at a spinning speed of /min.
Polyester fibers with irregular cross-sections having a single yarn denier of 20 d were produced by drawing the fibers at 105° C. by a factor of 3.1. The cross-sectional shapes of the fibers thus obtained were almost the same as those shown in Fig. 3, respectively. When the surfaces of these fibers were observed under a microscope, cracks were found on the surfaces of all of them, and the 3rd layer had a large cross-sectional deformation ratio.
This tendency was particularly remarkable for the fibers corresponding to D and H in the figure. Furthermore, the dyeing rates of the irregular cross-section fibers produced for comparison were all low, at 50% or less. Example 2 Intrinsic viscosity IV is 0.42 (measurement method is the same as Example 1)
The same copolymerized polyester as in Example 1 was spun using a spinneret in which 620 C-shaped slit-shaped spinning holes with an outer diameter of 1.2 mm, an inner diameter of 1.0 mm, and a bridge width of 0.2 mm were bored in an annular manner at different temperatures. The spun yarn was discharged at 275°C, and the spun yarn was cooled by a cooling air flow from the entire circumference of the spun yarn just below the spinneret, and then passed through the center of the same annular electric heater as in Example 1 to be cooled with air. After being stretched by the frictional force, the single yarn denier is 3D.
A polyester fiber with a modified cross section was produced. In this example, the yarn take-up speed and the cooling air flow speed were varied as shown in Table 2. In addition, the single yarn denier of the finished yarn was adjusted to 3d by changing the amount of polymer discharged depending on the take-up speed.
A tow cutter rotating at a predetermined circumferential speed was used as a take-up means, and the cut staple cotton was heat-treated if necessary. In this example, the spinning and drawing state, the mechanical properties of the complete yarn, and the crimp performance (1/ρ and 1/
ρ') and dyeing rate (dye and dyeing method are the same as in Example 1) are shown in Table 2.

【table】

[Table] As shown in Table 2, it can be seen that according to the present invention, hollow polyester fibers with no cracks on the fiber surface and excellent dyeing rate and crimp performance can be produced. Especially when spinning under conditions that simultaneously satisfy equations (1) to (5) described in the main text (Experiment Nos. 10, 11, 13, 14,
It can be seen that in Examples 17, 18, 19, 20, 22, and 25), fibers with good spinning and drawing conditions and even better crimp performance can be obtained. In addition, each experiment number of this example is described in FIG. 2, and the relationship between cases where the spinning conditions of the present invention are satisfied and cases where they are not satisfied is shown. In the case of Experiment No. 9, the yarn take-up speed was low and the cooling air flow velocity was insufficient, so the yarn did not become a drawn yarn but an undrawn yarn-like fiber. Experiment No. 15, 21, 23 and
In the case of No. 26, the flow rate of the cooling air current was too high, causing large yarn shaking, resulting in frequent yarn breakage due to fusion of the spun yarns and resulting single yarn breakage directly under the spinneret. In Experiment Nos. 12, 16, and 24, the flow rate of the cooling air stream was insufficient, so fibers with sufficient crimp could not be obtained, and only fibers with poor bulkiness were obtained. Experiment No.27
In the case of , yarn breakage occurred frequently because the yarn take-up speed exceeded 6000 m/min. For comparison, the same polyester polymer as in this example was melt-spun using the same spinneret as in this example by a normal melt-spinning method, and the spun yarn was cooled by blowing a cooling air stream from the outer circumferential direction. 1300m after
It was once wound up at a spinning speed of min, and then the undrawn yarn thus obtained was passed through hot water in the form of a tow and drawn in a conventional manner at a draw ratio of 2.6 times to produce a single-filament denier 3D hollow polyester fiber. . The fiber thus obtained had many cracks on its surface, and the dyeing rate was as low as 23%. Example 3 The amount of sodium 3,5-di(carbomethoxy)benzenesulfonate added is 0.7 mol% relative to dimethyl terephthalate, and the intrinsic viscosity
Example 1 except that the IV is 0.42 (the measurement method is the same as in Example 1) and the spinning temperature is 275°C.
A hollow polyester fiber with a single fiber denier of 20 d and a cross-sectional deformation S (cm ^-1 ) = 7425/√ was produced by spinning and drawing under exactly the same conditions as in Experiment No. 8. On the other hand, for comparison, the same polyester as in this example was melt-spun from the same spinneret as in this example, cooled in the same manner as in this example, and then spun according to the usual spinning method.
It is once wound up at a take-up speed of 1200 m/min, and then the undrawn yarn thus obtained is stretched by a conventional method at 110°C with a draw ratio of 3.0 times to obtain a single yarn denier of 20 d and cross-sectional deformation ratio S (cm ^-1 ) = 7150. /√ hollow polyester fibers were produced. There were almost no cracks on the fiber surface in both the fibers according to the present invention and the comparative example, but C.
I.Basic Red36 120℃90 without carrier
The dyeing rate when dyed for minutes was 82% for the fibers according to the present invention, while it was lower at 42% for the fibers of the comparative examples.Furthermore, the bulkiness of the fibers of the fibers according to the present invention was lower than that of the comparative examples. This was several orders of magnitude better, clearly demonstrating the excellence of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of various fibers for explaining the cross-sectional deformation ratio S of the present invention, and FIG. FIG. 3 is a schematic diagram showing the cross-sectional shape of the fiber obtained in Example 1 of the present invention.

Claims (1)

[Scope of Claims] 1 A polyester mainly composed of ethylene terephthalate units containing metal sulfonate groups is melt-spun through a spinneret having a non-circular spinning hole, and the spun yarn is once cooled by a cooling air stream directly below the spinneret. Then, the yarn is passed through a heating zone of 80°C or higher provided before reaching the drawing device, and is drawn under a temperature gradient by the frictional force with the air to form drawn fibers all at once. Yarn take-up speed V (m/min) and yarn take-up speed and cooling air flow velocity Vq (m/sec)
A polyester fiber with an irregular cross section having excellent dyeability and a cross-sectional deformation ratio S of 5000/√ or more, which is spun in a manner that satisfies the following equations (1) to (5) at the same time. Manufacturing method. 2000≦V≦6000 ...(1) Vq≧-2.75 (V×10 ^-3 ) +8.5 ...(2) Vq≧0.09 (V×10 ^-3 ) ² −0.81 (V×10 ^-3 )+2 .3 ……(3) Vq≦−0.17 (V×10 ^-3 )+3.6 ……(4) Vq≦3.2 ……(5) [However, S is the length of the contour line in the fiber cross section (cm ) divided by the cross-sectional area of the fiber cross-section (cm ² ) (cm ⁻¹ ), d indicates the single yarn denier. ]