JPS6143444B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel highly oriented undrawn polyester fiber tow blended with cotton that can be made into fibers with a large silk factor by drawing, and a method for producing the same. Recently, high-speed spinning is being adopted in the melt spinning of polyester fibers, and high-speed spinning with a take-off speed of 2500 m/min or more is also used in the manufacturing process of polyester fiber tow or sub-tow (hereinafter collectively referred to as "tow") for producing staple fibers. is being attempted. For example, in Japanese Patent Publication No. 51-24002, polyethylene terephthalate yarn with a birefringence index of 0.042, which was spun at a take-up speed of 3200 m/min and wound in a winder, was collected into a tow shape and drawn - crimped.
After heat treatment, oiling and cutting, the strength is 4.7g/
An example of producing a staple fiber with an elongation of 24.5% is described. Such high-speed spinning can be expected to improve spinning productivity compared to conventional low-speed spinning, and has advantages such as less change over time in undrawn fibers. When undrawn polyester fiber tow is drawn, no matter how the drawing conditions are selected, only fibers with a low silk factor can be obtained.In particular, fibers with an elongation of 20% and a silk factor of 32 or higher, which are useful as staple fibers for cotton blends, are obtained. The problem is that it is extremely difficult to manufacture. The present inventors investigated the above-mentioned problems specific to highly oriented undrawn polyester fiber tows obtained by high-speed spinning, and found that polyester fibers for staple fibers used for cotton blends have a single filament denier. Small (generally product denier 1.0
~1.5 de), and the single filament denier of high-speed spun highly oriented undrawn polyester fiber tow (birefringence of 0.03 or more) must also be 2.5 de or less. When trying to obtain a silk factor, crystal nuclei and/or microcrystals are generated in the fiber, so if the fiber is stretched, no matter how appropriate the conditions are chosen, sufficient molecular orientation cannot be imparted, and as a result, the silk factor It was found that only low fibers were obtained. Based on this knowledge, the present inventors conducted repeated research to provide a tow of highly oriented undrawn polyester fibers mixed with cotton that would have a sufficiently high silk factor after drawing, and found that (1) the birefringence was In the case of highly oriented undrawn polyester fibers with a high fine denier, only new fibers that combine a specific range of crystallinity and boiling water shrinkage rate can be used. (2) found that tows of highly oriented undrawn polyester fibers can be produced only by spinning polyester at high speed under very limited conditions. , which led to the present invention. That is, the first aspect of the present invention is that the birefringence is 0.03 or more (preferably 0.04 to 0.10) and the single yarn denier is
A tow consisting of polyester fibers of 2.5 de or less (preferably 1.0 to 2.2 de), wherein the polyester fibers have a crystallinity of 15% or less and boiling water of 55% or more (preferably higher than 60% and lower than 80%). The second aspect of the present invention is a highly oriented undrawn polyester fiber tow for blending with cotton having a shrinkage rate, and the second aspect of the present invention is to melt and discharge polyester from a spinneret, cool and solidify it with cooling air in a spinning tube, and spin it at a speed of 2500 m/min or more. When manufacturing a highly oriented undrawn polyester fiber tow made of polyester fibers with a birefringence of 0.03 or more and a single filament denier of 2.5 de or less, the temperature of the polymer melted and discharged from the spinneret is set to 285°C or higher, and as a spinning tube. In addition to using a closed-type spinning tube, the amount of cooling air in the spinning tube is determined by changing the amount of cooling air after heat exchange is completed within the spinning tube into a cooling air spinneret (theoretical). value) is Tg−15
(°C) to Tg (°C) [where Tg is the glass transition temperature of polyester]. The "polyester" used in the present invention mainly refers to polyethylene terephthalate, but it may also be one copolymerized with a small amount (for example, 5 mol% or less) of a third component, and may also include a small amount of a quenching agent, a coloring agent, It may also contain a modifier or the like. The degree of polymerization of polyester varies depending on the use and required properties of the fiber, but in the case of blending with cotton, the intrinsic viscosity of the fiber [η] (35
°C in O-chlorophenol) from 0.5 to 0.7. The tow of the present invention is composed of undrawn polyester fibers having a birefringence of 0.03 or more, preferably 0.04 to 0.10. Such tow is usually drawn within a range of 1.5 to 2.0 times depending on its birefringence index, and then subjected to treatments such as crimping, heat treatment, and cutting to make staple fibers, so the product denier In view of this, the single yarn denier of the undrawn fiber is
It is required to be 2.5de or less, especially 1.0~
2.2de is preferred. Although it is of course possible to obtain highly oriented undrawn polyester fibers with a birefringence of 0.03 or more and a single filament denier of 2.5 de or less by conventional high-speed spinning, such highly oriented undrawn polyester fibers cannot be obtained by the method described above. Because crystal nuclei and/or microcrystals are present in the fibers, the crystallinity is greater than 15% and the boiling water shrinkage is less than 55%. When tow made of such fibers is stretched, even if the optimal conditions are selected, if the elongation is in the 20% range, the silk factor of the stretched fibers is at most about 30, which is lower than the silk factor (32 or more) required for cotton blends. Not as good as that. Compared to such conventional highly oriented undrawn polyester fiber tow, the tow of the present invention has a lower fiber crystallinity.
It is characterized by a low boiling water shrinkage rate of 15% or less and a very high boiling water shrinkage rate of 55% or more (preferably more than 60% and up to 80%). Figure 1 is a graph showing the physical properties of a highly oriented undrawn polyester fiber produced by high-speed spinning and the physical properties of a fiber drawn from this fiber.The left side of the figure shows the data for the undrawn fiber, and the right side shows the data for the drawn fiber. (In each case, the conditions such as the spinning discharge amount and the draw ratio were selected so that the single fiber denier of the drawn fibers was 1.1 to 1.2 de and the elongation was 24 to 26%). In addition, the solid lines in the figure represent the highly oriented undrawn fibers (or fibers drawn from these fibers) constituting the conventionally known tow spun at high speed using a conventional method, and the broken lines represent the tow of the present invention spun at high speed using a special method described later. The constituent highly oriented undrawn fibers (or fibers obtained by drawing the same) are shown. As is clear from Figure 1, in the case of the conventionally known tow (solid line), when the spinning take-off speed exceeds 2500 m/min, the birefringence of the undrawn fiber becomes 0.03 or more, but the crystallinity begins to increase rapidly. , while the boiling water shrinkage rate decreases rapidly. Even though the stretching tension for stretching this tow becomes abnormally high, the silk factor of the stretched fibers also becomes low. In particular, if the crystallinity is greater than 15% or the boiling water shrinkage is less than 55%, the silk factor of the drawn fiber will be 32 or less, impairing its usefulness as a staple fiber for cotton blends. However, the tow of the present invention has almost the same relationship between the spinning speed and the birefringence of the fibers as the conventional tow, but the tow has a crystallinity of 15% or less despite the high birefringence of the undrawn fibers. within the range and boiling water shrinkage rate is 55%
It gradually increases in proportion to the birefringence, especially in a range higher than 60%. When this tow is stretched, it can be stretched to a high magnification even if the stretching tension is low, and the fibers stretched under optimal conditions have a silk factor useful as a cotton blend. The undrawn fibers also have a lower density than conventional highly oriented undrawn fibers, in most cases within the range of 1.34 to 1.35 g/cm ³ , and elongation.
250% or less, especially in the range of 100-220%. The take-off tow denier in the spinning process varies depending on the capacity of the spinning equipment, but generally a range of 10,000 to 200,000 de is industrially advantageous, and such tows are collected in the drawing process by converging several to several tens of tows. Stretching can be carried out in one stage or in multiple stages at an appropriate magnification within the range of 1.5 to 2.5 times.
The appropriate heating temperature during stretching is 80 to 200°C, and the heating method may be dry heat (heated roller or plate) or wet heat (hot water or steam). In either case, the stretching tension is lower (0.2 to 0.8 g/d) at the same stretching ratio than conventional highly oriented unstretched polyester fiber tow.
e) and can be stretched smoothly. The stretched fibers are subjected to treatments such as crimping, heat setting, and cutting as necessary to become staple fibers. The obtained staple fiber has a single yarn denier of 1.0 to 1.0 when stretched and heat-set under optimal conditions.
1.5 de, strength 6.0 to 7.5 g/de, elongation 18 to 30%, silk factor 32 to 36, and exhibits extremely excellent properties as a cotton blend. The highly oriented undrawn polyester fiber tow blended with cotton of the present invention, which has the above-mentioned advantages, is produced by melting and discharging polyester, particularly polyethylene terephthalate, through a spinneret and cooling and solidifying the discharged fibers in a spinning tube by blowing cooling air onto them. , after oiling if necessary, 2500m/min or more, preferably 3000m/min.
When taking off at a speed of 4,000 m/min, (a) the temperature of the polymer discharged from the spinneret is higher than that in the conventional method, at 285°C or higher, preferably 288 to 300°C, and (b) the spinning tube is a closed type (fiber). (c) use a spinning tube structure in which the fibers do not come into contact with the outside air until the solidification of the fibers is completed; The cooling air temperature (theoretical value) Ta (℃) is Tg−15 (℃) ~ Tg
(°C), preferably Tg-10 (°C) to Tg-2
(°C). In this way, it can be produced industrially advantageously. Hereinafter, the tow manufacturing method of the present invention will be described in detail with reference to FIG. FIG. 2 is a simplified cross-sectional view showing a spinning device for carrying out the tow manufacturing method of the present invention. The spinning tube is configured to blow cooling air toward the filament Y in the direction of the arrow, and 2a is a cooling air blowing part, 2b is a cooling air discharge part, and 2c is a filament discharge hole. In the present invention, a closed type spinning tube is used which is structured so that it does not come into contact with the outside air until the fibers Y are completely cooled and solidified. 3 is an oiling roller, and 4 is a guide roller. Generally, when producing polyester fiber tow for staple fiber production by high-speed spinning,
The molten polymer was discharged from the spinneret 1 at a temperature of 280°C or slightly higher to form filaments Y, and was cooled and solidified by exchanging heat with cooling air blown from around the filaments Y in the spinning tube 2. Thereafter, the filament is led out of the filament outlet 2c at the bottom of the spinning tube 2, treated with oil by an oiling roller 3, passed through a guide roller 4, and is combined with the filament Y' spun by an adjacent spindle. The waste is taken up by a take-up device (not shown) at a constant speed of 2500 m/min or more and collected in a can. According to the present invention, the temperature of the molten polymer discharged from the spinneret 1 is adjusted to 285°C or higher (preferably 288 to 300°C), which is higher than the conventional method, and
As the spinning tube 2, a closed type as shown in the figure is used, and the volume A (Nm ³ /min) of cooling air blown from the inner peripheral surface of the spinning tube 2 toward the fiber Y is made smaller than in the conventional method. The theoretical value Ta (°C) of the temperature of the cooling air after the heat exchange in the cylinder 2 is completed is Tg-15 (°C) to Tg (°C), depending on the glass transition temperature Tg (°C) of the polyester.
Preferably, the temperature is adjusted to Tg-10 (°C) to Tg-2 (°C). The theoretical value Ta (°C) of the cooling air temperature is defined by the following formula, and is industrially defined as the cooling air volume A (Nm ³ /min).
It can be adjusted by Here, θp: Polymer discharge temperature (℃) θa: Blown cooling air temperature (℃) Cp: Specific heat of polymer (cal/g・deg) Ca: Specific heat of cooling air (cal/g・deg) Gp: Polymer discharge amount (g/min) Ga: Cooling air volume (g/min) And cooling air volume (g/min) is A (Nm ³ /mi
n) by the following formula. Ga=ρaA Here, ρa: Specific gravity of cooling air (=1.2×10 ³ g/
m ³ ) The air flow rate A that satisfies the above conditions varies depending on the polymer discharge temperature, discharge amount, cooling air temperature, etc., as is clear from the previous equation, but if the polymer discharge amount is approximately 500g/
In the case of min, 3 to 5 Nm ³ /min is preferable. In addition, spinneret 1 has a hole diameter of 0.20 to 0.30 mmφ and a number of holes.
500 or more, preferably the distance H from the bottom surface of the spinneret 1 to the upper end of the cooling air blowing part 2a is 5 to 15 cm, and the length L of the cooling air blowing part 2a is 20 to 40 cm. Lowering the spinning draft to 150 to 300 is more effective. Further, the spinning take-off speed must be at least 2,500 m/min, and the effects of the present invention are particularly noticeable when it is set to 3,000 to 4,000 m/min. The spinning take-off denier is productivity,
A denier of 10,000 to 200,000 denier is appropriate from the viewpoint of both can collection performance. A conventionally known high-speed pulling device can be used to take off the tow, but since it is undesirable for the tow to be heated before it is stretched, the tow is not exposed to high temperatures when it is taken off. This should be kept in mind. By employing the above-described special spinning method, highly oriented undrawn polyester fibers containing the above-mentioned special substances can be produced industrially with good productivity. Next, the definition and measurement method of each physical property referred to in the present invention will be explained. Crystallinity: Measured by the method using X-ray diffraction described in US Pat. No. 3,249,597. Boiling water shrinkage rate: Sample length 500 mm, load according to JIS L 1073 measurement method for boiling water shrinkage rate of filament.
Measured under the conditions of 100g/1500de and immersion time of 30 minutes. Strength and elongation and silk factor: A tensile test was conducted according to the method of JIS L 1069 to determine the strength at break (S
g/de) and elongation (E%) are measured, and the silk factor is calculated using the following formula. Silk factor=S×√ Glass transition temperature (Tg): Measured by the method described in US Pat. No. 2,556,295. The Tg for polyethylene terephthalate is approximately 70°C. Example Intrinsic viscosity (O-chlorophenol at 35°C) 0.64
Number of spinneret holes for polyethylene terephthalate
720 holes, discharge rate 500g/min, cooling air temperature 25℃
Melt spinning was carried out under the same conditions as shown in the upper row of Table 1, and various highly oriented undrawn polyester fiber tows were produced. The physical properties of the undrawn fibers of the obtained tow were as shown in the lower row of Table 1. Next, each tow is focused and the supply roller temperature is
60℃, hot plate temperature 140℃, stretching speed 150
The film was stretched at the stretching ratio shown in the upper row of Table 2 under conditions of m/min. The stretched fiber physical properties of the obtained tow were as shown in the lower row of Table 2. From Tables 1 and 2, experiments according to the present invention
Nos. 2, 3, 4, and 5 have good silk factors after stretching and are suitable for cotton blends, but Experiment No. 1 using the conventional method and Experiment No. 6 which is a comparative example, It is clear that in both Nos. 7 and 8, the silk factor of the drawn fibers is insufficient even though the drawing tension is high, and they are unsuitable for use as a blend with cotton.

【table】

【table】 [Brief explanation of the drawing]

FIG. 1 is a graph showing the physical properties of various highly oriented undrawn polyester fibers obtained by high-speed spinning and the physical properties of fibers drawn from these fibers, in which the solid lines are those obtained by the conventional method, and the broken lines are those obtained by the present invention. shows. FIG. 2 is a simplified sectional view showing an example of a spinning apparatus for carrying out the method of the present invention, in which 1 is a spinneret, 2 is a spinning device;
represents the spinning tube.

Claims (1)

[Claims] 1. Birefringence is 0.03 or more and single yarn denier
A highly oriented undrawn polyester fiber tow mixed with cotton, which is a tow made of polyester fibers having a diameter of 2.5 de or less, wherein the polyester fibers have a crystallinity of 15% or less and a boiling water shrinkage rate of more than 55%. 2 Birefringence of polyester fiber is 0.04 to 0.010
A highly oriented undrawn polyester fiber tow blended with cotton according to claim 1. 3. The highly oriented undrawn polyester fiber tow blended with cotton according to claim 1 or 2, wherein the polyester fiber has a boiling water shrinkage rate of higher than 60% and lower than 80%. 4. The highly oriented undrawn polyester fiber tow mixed with cotton according to claim 1, which has a total denier of 10,000 to 200,000 de. 5. A highly oriented undrawn polyester fiber tow mixed with cotton according to claim 1, wherein the polyester fiber is a polyethylene terephthalate fiber. 6 Polyester is melted and discharged from a spinneret, cooled and solidified with cooling air in the spinning tube, and then heated to 2500 ml.
When manufacturing a highly oriented undrawn polyester fiber tow with a birefringence of 0.03 or more and a single filament denier of 2.5 de or less by taking it off at a speed of m/min or more, the temperature of the polymer melted and discharged from the spinneret is 285°C or more, and A closed spinning tube is used as the spinning tube, and the air volume of the cooling air in the tube is adjusted so that the temperature (theoretical value) of the cooling air after heat exchange within the tube is Tg-15 (℃) ~
A method for producing a highly oriented undrawn polyester fiber tow blended with cotton, which is characterized by adjusting the Tg (°C) [where Tg is the glass transition temperature of polyester]. 7 Distance H from the spinneret to the cooling air blowing start point
7. The method for producing a highly oriented undrawn polyester fiber tow mixed with cotton according to claim 6, wherein (cm) is 5 to 15 cm. 8 Set the temperature of the polymer discharged from the spinneret to 288~
300℃, and the cooling air temperature (theoretical value) after heat exchange in the spinning cylinder is Tg-10.
(°C) to Tg-2 (°C), the method for producing a highly oriented undrawn polyester fiber tow mixed with cotton according to claim 6 or 7.