JPH0380887B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to polyester fibers, and particularly to polyester fibers suitable for drawing and false twisting. (Prior art) Polyester fibers, especially polyester fibers subjected to stretching and false twisting, are
Partially oriented yarn spun at a speed of 1 minute, the so-called
POY (Partially Oriented Yarn) has been widely used recently. However, such polyester fibers do not necessarily have sufficient stability over time, so they not only cannot withstand long-term storage or transportation, but also the cross-sectional deformation of the filaments during the drawing and false-twisting process is large. The disadvantage is that the appearance and texture of the sublime processed yarn is inferior. Furthermore, especially during high-speed drawing false twisting, large drawing deformations occur at high speeds, which causes the filament to easily break, resulting in fluff and yarn breakage. For such POY,
Polyester fibers recently spun at high speeds of 4,000 to 6,000 m/min or spun yarns at 150℃
After instantaneous heat treatment with heated gas over 2000
It has been proposed to subject polyester fibers drawn at a speed of ~4500 m/min to stretching and false twisting (for example, Japanese Patent Publication No. 58-36086, Japanese Patent Publication No. 58-18446).
(Japanese Patent Publication No. 58-17294, Japanese Patent Publication No. 58-169513). Since such polyester fibers have a high degree of orientation and crystallinity, they have improved stability over time and have been shown to have improvement effects such as a reduction in the cross-sectional aspect ratio during drawing and false twisting. In the false twisting process, so-called crystal stretching, which involves destruction and rearrangement of crystals during stretching, occurs, which has the disadvantage that fuzz tends to occur. Furthermore, there was also a drawback that the resulting drawn and false twisted yarn had poor unwinding and weaving properties in subsequent steps. Furthermore, in recent years, research has been actively conducted on latent sublime multifilaments made by blending polyester fibers with differential shrinkage. The above-mentioned POY
Although it is widely used, it is difficult to handle it because of its poor stability over time as described above. On the other hand, if the spun yarn is heat-treated and then taken off at high speed instead of POY, the stability over time is good, but the difference in shrinkage between the filaments of the obtained latent sublime multifilament is not sufficiently provided. He was unable to achieve a satisfying level of sublimity. (Object of the Invention) The object of the present invention is to provide a polyester fiber that can eliminate the above-mentioned drawbacks, and in particular, a polyester fiber that can simultaneously satisfy the following required properties (1) to (4) and is suitable for stretching and false twisting. It is about providing. (1) It has stability over time that can withstand long-term storage. (2) The cross-sectional deformation of the filament during stretch false twisting is small. (3) Less fuzz occurs during stretch false twisting. (4) The resulting false-twisted yarn has good unwinding and fibre-making properties. (Configuration) In order to achieve this objective, the present inventors first studied the allowable levels of each of the required characteristics (1) to (4), and found that the stability over time is 150 days or more,
The cross-sectional deformation of the filament is determined by the cross-sectional flatness, which will be explained later.
I learned that it is necessary to have a fuzz of 1.5 or less, a fuzz of 10 strands/10 ⁴ m or less, and that there should be no defects in unwinding or fibre-making properties. The present inventors have arrived at the present invention as a result of extensive studies on polyester fibers that can simultaneously achieve such acceptable levels. That is, the present invention consists of a polyester whose main repeating unit is ethylene terephthalate,
And elongation is 40-60%, birefringence (Δn) is 0.09-
0.13, the peak temperature and peak value of thermal stress of the fiber are 75 to 100, respectively.
℃ and 0.3 to 0.5 g/de, and a boiling water shrinkage rate of 40% or more. Before describing the present invention in detail, a method for measuring each characteristic value used in the present invention will be described. Elongation A tensile test is performed using a Tensilon tensile tester with a sample length of 20 cm, and the elongation rate at cutting is indicated. Boiling water shrinkage rate The amount of shrinkage when a sample is heat treated in boiling water at 100°C for 30 minutes without restraint, expressed as a percentage of the test length before treatment. Thermal stress Thermal stress tester manufactured by Kanebo Engineering Co., Ltd.
Using KE-type, initial tension stress denier/30
Measurement was carried out under the following conditions: g, sample length 10 cm, and heating rate 2.5°C/sec. Stability over time The sample package was stored in a temperature-controlled room with a temperature of 35℃ and humidity of 55% RH, and after a predetermined number of days, it was taken out and subjected to stretching and false twisting as described below, and the resulting processed yarn was stockinette knitted and dyed. I went. The dyeing becomes darker as the number of days passes, but standard yarn (processed yarn that is stretched and false-twisted after being left in a room at 25℃ and 65% RH for just one day after winding under various standard conditions) ) was visually judged and expressed as the number of days in which the dyeing difference reached an acceptable limit. Cross-sectional flatness The cross-sectional flatness is when the length of the longest inner diameter (diagonal line) in the filament cross section of the obtained drawn and false-twisted yarn is b, and the longest diameter perpendicular to the longest diameter is a. It is defined as b/a of , and is expressed as the average value of the values measured for 20 pieces.
The closer the oblateness is to 1, the closer to a perfect circle it is. Fluff Toray Engineering's fluff tester (HAIRINESS COUNTER MODEL DT-104) is installed downstream of the twisting unit during stretch false twisting.
The number of fuzz generated was measured for 30 minutes, and the number of fuzz generated /
Converted to 10 ⁴ m units. The present invention will now be described in detail. The term "polyester" used in the present invention generally refers to polyethylene terephthalate homopolymers, polyester copolymers containing 90 mol% or more of ethylene terephthalate units, and blends containing these polyesters as main components. The polyester may contain small amounts of additives (for example, matting agents, pigments, dyes, stabilizers, flame retardants, surface modifiers, etc.) as necessary. Among these polyesters, those having an intrinsic viscosity (measured with an O-chlorophenol solution at 35° C.) of 0.5 or more, particularly 0.55 to 0.95 are preferable. In the present invention, first, it is necessary that the elongation (at break) of the polyester fiber is 40 to 60%. If the degree of elongation exceeds 60%, the stretching ratio during stretch false-twisting becomes high, resulting in flattening of the cross-section of the filament during stretch false-twisting. Also, the elongation is 40
If it is less than %, the elasticity of the fibers will be insufficient, and yarn shaking will occur during high-speed drawing and false twisting.
Ballooning cannot be absorbed by itself and causes crimp spots and fuzz. Next, the birefringence (Δn) is 0.09~
It needs to be 0.13. When Δn is less than 0.09,
Due to insufficient stability over time, during long-term transportation or storage, the fiber orientation gradually changes to a non-oriented direction, resulting in a dark dyeing phenomenon. Also,
When Δn exceeds 0.13, a phenomenon occurs in which the residual torque of the drawn and false-twisted yarn increases, resulting in poor unwinding properties and fiber-making properties in subsequent steps. Furthermore, the peak temperature of thermal stress (Tmax) is 75~
At 100℃ and peak value (TSTmax) is 0.3 to 0.5
It is necessary to be g/de. When Tmax exceeds 100° C. and when TSTmax exceeds 0.5 g/de, disadvantages such as generation of fuzz and decrease in crimp rate occur during stretch false twisting. This is thought to be due to the fact that in the case of polyester fibers with a high Tmax value, the flexibility of the fibers against heat decreases, which deteriorates the ability to follow deformation during stretching and false twisting. On the other hand, if Tmax is less than 75℃ and
If TSTmax is less than 0.3 g/de, the yarn is likely to melt and break in the heater during drawing and false twisting. In the polyester fiber of the present invention, even if the above-mentioned elongation, birefringence (Δn), peak temperature and peak value of thermal stress are within the range specified by the present invention, if the boiling water shrinkage rate is 40% or more, the The purpose of the invention cannot be achieved. The boiling water shrinkage rate referred to here is used as a characteristic that expresses the crystallinity of fibers, and as shown in the paper by Shimizu et al. in the Journal of the Japanese Society of Textile Technology 34 T-93 (1978), as crystallinity increases, boiling water shrinkage Shrinkage rate decreases. In the case of polyester fibers having a boiling water shrinkage rate of less than 40%, crystal stretching occurs during stretching and false twisting, resulting in crystal destruction and generation of high stretching tension, resulting in frequent filament breakage, that is, fluffing. In this way, the elongation is 40 to 60%, the birefringence (Δn) of the entire fiber is 0.09 to 0.13, the boiling water shrinkage rate is 40% or more, and the peak temperature of thermal stress is 75 to 100℃, and the peak value is 0.3. Only polyester fibers with ~0.5 g/de can provide stability over time, cross-sectional deformation resistance of the filament, fluff resistance, and good unwinding and fiber-making properties during drawing and false twisting. . Conventional polyester fiber, i.e. 4000~6000m/
High-speed spinning in minutes or spun yarn in 150 minutes
2000~4500 after heat treatment with heated gas above ℃
When the fibers are drawn at m/min, the fiber orientation (birefringence) increases, the crystallinity also increases rapidly, and the boiling water shrinkage rate decreases rapidly. For this reason, the elongation, birefringence, thermal stress, and boiling water shrinkage rate of the obtained polyester fibers cannot simultaneously satisfy the ranges specified in the present invention, resulting in changes over time, filament cross-sectional deformation during false twisting, fuzz, etc. Furthermore, it is impossible to simultaneously satisfy acceptable levels of unwinding properties and fibre-making properties. The polyester fiber of the present invention described above is produced by a method different from conventional melt spinning. For example, polyester is melted and discharged from a nozzle, the atmosphere immediately after being discharged from the nozzle is maintained at a high temperature of 200℃ or higher over a length of at least 130 mm, and immediately after that, cold air of 10 to 20℃ is blown to rapidly cool the polyester. Then, after being heat treated by running through a low temperature heat treatment zone of 70 to 110℃, the yarn was heated to 4500℃.
It is industrially advantageous to produce by taking off at a speed of ~6000 m/min. At this time, the temperature and take-off speed of the low-temperature heat treatment zone are important, and the polyester fiber of the present invention can only be obtained when the temperature and take-off speed are within the above ranges. It goes without saying that other methods may be employed as long as the properties of the polyester fibers finally obtained satisfy the range defined by the present invention. (Function) Conventionally, after heat treatment of spun yarn at 150℃ or higher, 2000℃
The polyester fiber drawn at ~4500 m/min has extremely high degree of orientation and crystallinity, so although its stability over time and cross-sectional deformation of the filament during stretching and false twisting are satisfactory, Crystallization and stretching occur during stretching and false twisting, and the deformation followability to heat is also poor, resulting in frequent fluffing. Moreover, the resulting processed yarn has a high residual torque, resulting in poor unwinding and fiber-making properties. On the other hand, the polyester fiber of the present invention has appropriate orientation, crystallinity, and ability to follow deformation due to heat, and as a result, its stability over time is limited to 150 days.
In the drawing/false twisting process, it is possible to adopt a drawing ratio that allows the filament cross-sectional flatness of the resulting processed yarn to be 1.5 or less. Furthermore, even when stretch-false-twisting is performed at such a stretching ratio, no crystallization stretching occurs, and the polyester fiber of the present invention has good deformation resistance to heat, so the fluff of the resulting processed yarn is 10 times less. /10 ⁴ m or less,
Furthermore, since the residual torque of the processed yarn obtained is low, the unwinding and fiber-spinning properties of the processed yarn are also good. As described above, the polyester fiber of the present invention simultaneously satisfies required properties (1) to (4), and the latent sublime multifilament using such polyester fiber as a high shrinkage filament has good stability over time of the high shrinkage filament. and the shrinkage difference between the constituent filaments can be made sufficiently large.
Both the ease of handling and the sublime quality of such a multifilament are satisfactory. (Effects of the Invention) According to the polyester fiber of the present invention, it is possible to easily manage the raw yarn and have good processability, especially in the drawing and false twisting process, and the appearance and texture of the resulting processed yarn are And the process passability in the weaving and knitting process can both be improved. (Example) Next, the present invention will be further described in detail with reference to Examples. intrinsic viscosity
0.64 polyethylene terephthalate (melting point 261℃,
A chip with a glass transition point of 68°C) is heated to 300°C with a pore size of 0.3.
The yarn is melted and discharged from a spinneret with 36 holes and heated by a cylindrical heating sleeve over a 150mm area directly below the spinneret, and subsequently cooling air is blown from the side on the spinning yarn in a pressure gap 1.3m below. After cooling, the yarn was passed through a heating zone with a length of 1.0 m, and then a finishing agent was applied with an oiling roller, taken up with a pair of godet rollers, and wound up with a winder. The physical properties of the fibers obtained under each condition are shown in Table 1. Next, the above-mentioned undrawn yarn is fed to a friction disk processing type SDS-8 drawn and false twisted processing machine made by Scratsug Co., Ltd., and the ratio of the disk surface speed to the yarn speed is D/Y.
is 1.708, heater temperature 210℃, winding speed 800m/
A 75 denier, 36 filament textured yarn was obtained by false twisting at the same time as stretching under conditions where the stretching ratio was selected so that the yarn tension before the disc was 35 g. The properties of the processed yarn obtained at this time are also shown in Table 1. In Table 1, Experiments Nos. 1 to 12 were conducted at a withdrawal speed of 5000 m/min with other manufacturing conditions changed, Experiments No. 13 to 14 were conducted at a different withdrawal speed, and Experiments Nos. 15 to 14 were conducted at different manufacturing conditions. 18 is an example in which the take-up speed was changed using the normal method in which heating is not performed after the yarn is air-cooled. Examples according to the present invention are Experiment Nos. 1, 2, 7, and 8.
The others are comparative examples. As is clear from Table 1, only polyester fibers within the range specified by the present invention have the required properties.
It is within the acceptable level of (1) to (4). 【table】

Claims (1)

[Claims] 1 Made of polyester whose main repeating unit is ethylene terephthalate, and has an elongation of 40~
60%, and a birefringence index (Δn) of 0.09 to 0.13, the peak temperature and peak value of thermal stress of the fiber are 75 to 100°C and 0.3 to 0.5, respectively.
g/de and a boiling water shrinkage rate of 40% or more.