JPS6218645B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for economically and efficiently producing high-grade, completely continuous, ultrafine multifilament yarn free from breakage, fluff, and fusion from polyester by a conventional melt spinning method. Ultrafine fibers are used in synthetic paper, filters, artificial leather, suede for clothing, etc., and have recently made remarkable progress in an industrial sense, with active research and development into the production of ultrafine fibers and their applications. Conventionally, methods for producing ultrafine fibers include peel-off type composite fiber splitting method;
A method for dissolving and removing sea components from sea-island type fibers has been proposed.
Although these methods have been industrialized, they have had various problems in terms of economy, operability, and yarn quality. Attempts have been made to produce ultra-fine yarns with a single denier of less than 1 denier using ordinary melt-spinning methods, but due to the surface tension of the spun polymer, ultra-fine yarns, especially single filaments,
It has not been possible to manufacture ultrafine yarns of 0.5 denier or less with good operability. Therefore, the present inventors conducted intensive research to produce a high-grade, fully continuous, ultra-fine polyester multifilament yarn with good operability by the usual melt spinning method, which is preferable in terms of economy and yarn quality performance, and as a result, they arrived at the present invention. did. In other words, the present invention reduces the amount of discharge per spinneret hole (g/
min) is 0.05 to 0.15g/min, and the withdrawal speed is 18×10 ³
× Qm/min or more and 3000m/min or more,
The present invention is a method for producing ultrafine polyester fibers having a single yarn fineness of 0.1 to 0.5 denier, which is characterized by satisfying the following conditions A and B. A: Use a spinneret in which the spinneret diameter (D) is 0.2 mm or less and the spinneret holes are arranged in a ring so that the value of K defined by the formula is 0 to 0.25, K = D ₂ - D ₁ /D ₁ [D ₁ and D ₂ are the minimum and maximum hole diameters of the spinneret holes] B: In the area within 10 cm directly below the spinneret, the flow rate M (Nl/ ) and set the atmospheric temperature T (°C) near the spun yarn within the range of the formula. [V is the take-up speed (m/min) of the spun yarn, H
is the number of holes in the spinneret, H≧34] [η is the relative viscosity of polyester, 1.30≦η
≦1.45, L is the distance from the spinneret surface (cm)] In the present invention, the relative viscosity η of the polyester is measured at 20°C using an equal weight mixture of phenol and tetrachloroethane as a solvent at a concentration of 0.5 g/100 ml. shows the value. Next, the present invention will be explained with reference to the drawings. FIG. 1 is an explanatory diagram of a melt spinning apparatus showing one embodiment of the present invention, in which 1 is a spinneret, 2 and 3 are installed within 10 cm directly below the spinneret surface, and gas is supplied from the outer circumferential direction toward the center of the spinneret. It is a cylindrical spray device (annular spray) that blows out water, and has a two-stage spray type (hereinafter, upper spray 2 is the first spray, and lower spray 3 is the second spray).
(referred to as spraying). 4 is a yarn spun from the spinneret 1, and 5 is a fulcrum guide located upstream of an oil treatment device 6 and a first take-off roller (hereinafter referred to as the first take-up roller) 7 that defines the yarn speed.
8 is a second roller that is paired with the first take-up roller 7;
A take-up roller, 9 is an interlace nozzle or false twist nozzle, 10 is a traverse fulcrum guide, 1
1 is a winding machine. FIG. 2 shows the bottom surface of the spinneret 1, and the spinneret holes 12 are arranged in an annular hole zone defined by a minimum hole diameter D ₁ and a maximum hole diameter D ₂ . As long as conventional spinning methods were employed, it was extremely difficult to spin uniform, completely continuous ultrafine fibers due to the surface tension of the polymer, etc. However, by adopting the present invention, the desired single fiber fineness can be easily achieved. 0.1~
Completely continuous ultrafine fibers of 0.5 denier polyester multifilament can be obtained. The reason for this has not yet been clearly elucidated, but it is probably due to three subtle factors: the bulge and surface tension of the polyester molten polymer just below the spinneret hole, and the falling speed (take-up speed). This is thought to be due to a combination of However, when the number of filaments in the spun yarn 4 increases, the yarn sways due to the interaction of accompanying air currents generated around the individual filaments of the spun yarn, which are other than the three basic factors mentioned above.
Problems arise such as differences in cooling thinning and solidification behavior caused by temperature fluctuations in the cooling atmosphere and differences in filament position between the outer periphery and the center. That is, eliminating tension, cooling, speed unevenness, etc. between filaments, and achieving ideal cooling, thinning and solidification must be considered as important factors for industrialization. The present invention will be specifically explained below. Spinneret hole diameter D (mm), discharge amount Q (g/min) per spinneret hole, yarn take-up speed V (m/min), single yarn fineness d of the obtained fiber, and spinning draft V/V ₀ The relationship with is shown by the following equation. d=9000Q/V V/V ₀ = πρD ² V/4Q Where, V ₀ is the discharge speed of the molten polymer discharged from the spinneret hole 12. V ₀ = 4Q/πρD ² (m/min) ρ: Discharge Density of the molten polymer (g/cm ³ ) It is necessary to reduce the amount Q of molten polymer. Producing ultrafine fibers by increasing only the take-up speed V of the yarn 4 is preferable from the viewpoint of productivity, but it has various problems in terms of equipment costs, spinnability, etc. In other words, considering the performance of the winding machine, the maximum winding speed of currently commercially available winding machines is 6,000 m/min, so it is impossible to manufacture products that can be wound at higher speeds. Even if a cutting machine were developed, the equipment costs would be enormous. Furthermore, if we try to obtain ultrafine fibers by increasing the yarn take-up speed V while keeping the discharge amount Q per 121 spinneret holes at the conventional level, as is clear from the equation, the spinning draft (V/V ₀ ) will increase. As a result, the accompanying airflow near the spun yarn 4 becomes extremely large, extremely disturbing the atmosphere under the spinneret 1, causing yarn shaking, uneven cooling, and a single yarn fineness of 0.7.
Take-up speed corresponding to denier (i.e. Q=
When V=5500 m/min at 0.45 g/min), stable spinning becomes impossible. Next, as is clear from the formula, decreasing the amount Q of the molten polymer discharged from each spinneret hole 121 is a preferable direction for obtaining thinner fibers. However, spinneret 1 with a normal spinneret hole diameter (0.25-1.0 mm)
gradually reduce the discharge amount Q using
If the amount is less than 0.2 g/min per hole, the spun yarn 4 becomes frosty, and is extremely unstable, making it impossible to obtain uniform continuous ultrafine fibers. Therefore, the present inventors conducted extensive research on how to reduce the discharge amount Q per spinneret hole 121 and achieve stable spinning without causing frosting, and as a result, the spinneret hole diameter D was reduced to 0.20 mm or less. It has been found that by reducing the size, even if the discharge amount Q per spinneret hole 121 is set to 0.15 g/min or less, the spun yarn 4 does not become frosty, and stable and good spinning can be performed. In order to obtain thinner ultrafine fibers, as mentioned above, it is preferable to reduce the discharge amount Q per spinneret hole 121 and increase the take-up speed V. As is clear from the equation, the spinning draft (V/
V ₀ ) becomes extremely large, draft breakage occurs in the spun yarn 4, and continuous winding becomes difficult. but,
By reducing the spinneret hole diameter D, the spinning draft can also be suppressed within the spinning possible limit, and the spinneret hole 1
Since the amount Q of the molten polymer discharged from the 21st hole can also be reduced, the withdrawal speed V proportional to the discharge amount Q, that is, 18×10 ³ ×Q(m /min) or more, it became possible to obtain ultrafine fibers. On the other hand, the diameter D of the mouthpiece hole and the discharge amount Q per 121 mouthholes are set within the range of the present invention, and the take-up speed V is set to 18
If the speed is lower than ×10 ³ ×Q (m/min), the spinning draft will be small, the take-up tension will be low, and the single yarn fineness will be large, resulting in insufficient cooling, which will cause yarn shaking and fusion between yarns. The yarn cannot be obtained until it is subjected to drawing. Therefore, the spinneret hole diameter D was set to 0.20 mm or less, the polymer discharge amount Q per 121 spinneret holes was set to 0.15 g/min or less, and the take-up speed V was set to
Taking it off at a rate of 18×10 ³ ×Qm/min or more is an essential requirement for producing ultrafine fibers, which is the object of the present invention. However, in order to reduce the discharge amount Q, the spinneret hole diameter D must be made smaller, and the lower limit of the discharge amount Q is 0.05 g/min in terms of spinneret manufacturing technology. Also,
If the take-up speed V is small, for example, 18×10 ³ ×Qm/
Even if the spinning time is more than 10 minutes, the spinning tension will not be adequate, yarn shaking, fusion between yarns, etc. will occur, making it impossible to produce uniform ultrafine fibers with good operability, and productivity will be poor and industrial difficult to implement,
The take-up speed must be 3000 m/min or more. On the other hand, when considering practical yarn properties, processability, and productivity, there is naturally a lower limit to the total denier of the spun yarn, and the lower the single yarn denier, the more it is necessary to increase the number of filaments. Therefore, it is absolutely necessary for industrialization to solve the problems associated with multifilament, such as productivity, yarn shaking, single yarn unevenness, and workability. According to the method of the present invention, as described above, spinning is performed at a low single-hole discharge rate and a high take-up speed, so the thinning and solidification of the spun yarn progresses rapidly, and is completed within a distance of about 25 cm from one surface of the spinneret. Therefore, it is most important to strictly adjust the atmospheric temperature and air flow in the vicinity of the many filaments from the spinneret surface until the spun yarn 4 is solidified. However, as long as a spinneret with a large number of 100 or more spinneret holes in the perforation zone where K in the above formula is larger than 0.25 is used, no matter how much the atmospheric temperature and air flow near the yarn are adjusted, the spun yarn will not be produced. There is a difference in cooling rate between the outer periphery and the center of the strip, which increases yarn bending and uneven fineness between filaments, making it impossible to stably produce high-quality ultrafine fibers. If the temperature is extremely high, measure the ambient temperature near the solidification point of the spun yarn, and the ambient temperature at the center will be 50 to 50°F compared to the outer periphery.
At a high temperature of 100℃, the solidification point of the yarn in the center shifts far downstream from the solidification point of the yarn in the outer periphery, and by the time the yarn is thinned and solidified, a difference in tension speed occurs between the yarns and at the same time occurs near the yarn. Due to the interaction of the air currents, yarn swaying, fusing, and cutting occur frequently. The inventors of the present invention conducted extensive research on this issue, and as a result, they were able to solve this problem by improving the arrangement of the spinneret holes and the method of cooling the spun yarn in the area within 10 cm directly below the spinneret surface. Ivy. That is, in order to make the thinning and solidification behavior of the spun polyester multifilament uniform, the arrangement of the spinneret holes 12 on one side of the spinneret is annular, and at the same time, the K value defined by the formula is set to 0 to 0.25, and the spinneret is Directly below 1st page 10
The flow rate M (Nl/min) of gas blown out from the outer circumferential direction toward the center of the spinneret in an area within cm is defined by the formula, and at the same time, the temperature T (℃) of the gas atmosphere near the spun yarn is determined within the range of the formula. By making adjustments, we have made it possible to produce a completely continuous ultrafine polyester multifilament yarn of high quality without yarn sway, fusion, or breakage. In particular, in the formula, K = 0 indicates that the number of 12 spinneret holes is 1 row, and when this spinneret is used, the thinning and solidification behavior between each filament is almost uniform, and there is no unevenness between single filaments. It is possible to stably obtain high-quality continuous ultra-fine yarn with a small size.
K with the intention of uniformly discharging the polymer from the entire surface of the mouth plate.
If the value is greater than 0.25, no matter what yarn cooling method is used, there will be a large difference in the thinning and solidification behavior between the filaments, and the effect of arranging the cap holes 12 in an annular shape will disappear, causing the problems described above. cause
Furthermore, even if a spinneret with annularly arranged spinneret holes is used so that the value of K defined by the formula is 0 to 0.25, the spinnerets are located within 10 cm directly below the spinneret surface and are blown from the outer periphery of the spinneret toward the center. Gas flow rate M
If (Nl/min) is less than the lower limit of the formula, the ambient temperature at the center of the yarn is higher than at the outer periphery, and the solidification of the yarn at the center is far downstream from the solidification point of the yarn at the outer periphery. , tension and speed differences between the yarns occur before they thin and solidify, and at the same time, it is not possible to completely adjust the accompanying airflow that occurs near the yarns, and even if the ambient temperature is measured at the same location, temperature fluctuations may occur. is 5-20
℃, yarn shaking, fusion, and breakage occur, and a positive spraying effect can hardly be expected. On the other hand, if the flow rate M of the blown gas is higher than the upper limit of the formula, it is possible to suppress the accompanying airflow near the yarn generated directly under the spinneret and the atmospheric temperature fluctuation, but the blown gas flow rate is too high and the blown air directly This is undesirable because a phenomenon of cutting the spun yarn occurs. In other words, it is basically preferable that the amount of gas blown onto the spun yarn be slightly larger than the amount of accompanying airflow caused by the spun yarn, and the amount of gas blown onto the spun yarn should be slightly larger than the amount of accompanying airflow caused by the spun yarn, and the amount of gas to be blown onto the spun yarn should be slightly larger than the amount of accompanying airflow caused by the spun yarn. A solution was reached by adjusting the problem to within the range of the experimental formula defined by the function. The blowing gas employed in the present invention is preferably air or an inert gas such as chiso gas, and the number of blowing stages may be one, or any of the multi-stage blowing methods of two or more stages as shown in FIG. 1 may be adopted. In particular, as the total number of spun filaments H increases and the take-up speed increases, it is necessary to increase the amount of blown gas, so a two-stage or more blowing method is adopted to reduce the amount of air blown from the upper blowing section. It is even better if the air volume blown in the lower part is lower than that in the lower part, and the temperature of the air blown in the upper part is higher than that in the lower part, and in order to extend the nozzle life, an inert gas such as heated titanium gas is distributed in the upper part. Effective. Next, even if a spinneret that satisfies the formula and an annular spraying method that satisfies the formula as described above are used, the yarn cooling rate (temperature of the atmosphere near the yarn) in the area within 10 cm directly below the spinneret
If the yarn cooling rate is inappropriate, that is, if the yarn cooling rate is high, draft breakage will occur frequently, and conversely, if the cooling rate is slow, the yarn tension will decrease, causing yarn shaking, adhesion, and draw resonance phenomena, resulting in high quality. It is not possible to obtain continuous ultrafine yarns of polyester multifilament. Therefore, the present inventors have determined that in order to produce continuous ultrafine yarn of high-quality polyester multifilament,
As a result of intensive research on the temperature of the atmosphere near the yarn directly under the spinneret (the temperature of the gas 5 mm away from the yarn, measured using a 0.25 mmφ CA thermocouple), we adjusted the temperature to within the temperature range of the above formula. I was able to solve the problem by doing this. Ideal for spun polyester multifilament (yarn swing, adhesion, draft cutting,
In order to uniformly cool, thin and solidify the spun polyester (without marbling), it is preferable to set the spinning tension at the solidification point to 0.5 to 1.0 g/d. It is essential to adjust the cooling, thinning and solidification rate of the spun yarn by changing the atmospheric temperature directly below the spinneret according to η). In other words, if the temperature T (°C) of the atmosphere near the spun yarn immediately below the spinneret surface is lower than the lower limit temperature of the formula for the degree of polymerization η of the polyester polymer used, the yarn will rapidly thin and solidify. As a result, draft cutting occurs and the desired yarn cannot be obtained. On the other hand, if this temperature is too high than the upper limit temperature of the formula, the cooling, thinning, and solidification of the spun yarn will be delayed, the spinning tension will decrease, and yarn shaking, adhesion, marbling, etc. will occur, resulting in high-grade polyester fibers. Continuous ultrafine filament fibers cannot be stably obtained. In the present invention, the polyester constituting the polyester yarn is a polyester in which at least 70% of the polyester structural units are polyethylene terephthalate. The high-quality polyester multifilament microfiber obtained by the method of the present invention has extremely excellent conformability and adhesiveness. This property can be used to prevent the hem of a dress shirt from rising, or as a substitute for hook-and-loop fasteners, and can also be used to tightly stack kimonos, and it exhibits a phenomenon similar to adhesion to human skin. It has special properties that were previously unknown. Furthermore, according to the method of the present invention, completely continuous ultrafine fibers can be obtained, so they can be used as they are, or they can be drawn and heat-treated in a normal drawing machine like conventional fibers to obtain various fiber properties. It is also possible to make ultrafine fibers. In particular, in terms of stretchability, it has a superior advantage over ultrafine fibers obtained by any manufacturing method. In addition, the present invention has outstanding industrial value, and because the ultrafine fibers are made of a single polyester polymer that is completely continuous, there is no need to remove one component in a solvent as in the sea-island fiber dissolution method, which is normally It can be treated in the same way as undrawn yarn or drawn yarn. That is, this fiber can be used alone, but it can also be used in combination with other thick denier fibers. Moreover, as a result, this fiber has a good feel, remarkable fit, conformability, light weight, thinness,
Significant improvements can be made in terms of drapability and handling. The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to the Examples. Example 1 The relative viscosity η=
After heating and melting 1.38 polyethylene terephthalate at a spinning temperature (spinneret surface temperature) of 285°C, using the spinneret shown in Table 1, the discharge amount Q (g/min) per 121 spinneret holes, the take-up roller 7, 8 speed (m/
A package was produced by spinning with different speeds (minutes). The spraying device used at this time was a cylindrical two-stage spraying type; the first spraying was at a position 5mm directly below the spinneret surface, and the heated titso gas was sprayed from the spraying surface with an inner diameter of 110mmψ and a width of 25mm, and the second spraying was at a position 5mm directly below the spinneret surface. Air at 50°C was blown from a spray surface with an inner diameter of 110 mmψ and a width of 50 mm at a position directly below the spray device. The blown air volume and the temperature of the heated titanium gas in the first spraying were adjusted so that the blown air volume M (Nl/min) and the temperature T (°C) of the atmosphere near the spun yarn satisfied the following formulas, respectively. The results are shown in Table 2.

【table】

【table】

[Table] Test No. 6 ~ in which the method of the present invention was adopted and the yarn was taken off
Test Nos. 8 and 11 to 14 were very good with no frosting, fusion, or yarn shaking during spinning, especially test No. 8 in which the spinneret hole diameter D and the discharge amount Q per spinneret hole were made small and the yarn was taken at high spinning speed. .11 to 14 were able to stably obtain high-quality completely continuous ultrafine fibers with a single fiber fineness of 0.20 denier or less and very small single fiber irregularities. In addition, in Test Nos. 1 to 3, which are outside the scope of the present invention, the discharge amount Q per nozzle hole was large, the cooling solidification rate was slow, the yarn sway was large, the single yarn unevenness was large, and the drawability was poor. . No.
4 and 5 have large nozzle holes D, so if the discharge amount Q per nozzle hole is reduced, the spun yarn 4 becomes frosty just below the nozzle 1, and single yarn unevenness increases to an extreme extent, causing breakage when it becomes severe. Continuous collection was impossible. In test No. 9, the spinneret hole diameter D and the discharge rate Q were within the range of the present invention, but due to the low take-up speed, the tension applied to the yarn 4 was low and unstable, and the spun yarn became frosty. Summer. Furthermore, due to the low tension, yarn sway was likely to occur, and fusion occurred between the yarns. Test No.10
Since the discharge amount Q per spindle hole is as high as 0.25 g/min for the spindle hole diameter D of 0.10 mm, the cooling and solidification of the spun yarn 4 is delayed, and the spinning draft (V/V ₀ ) is approximately 210 g/min. Because of the small size, the yarn swayed a lot and fusion occurred. The yarns of test Nos. 1, 3, 9, and 10 were drawn in a two-ply yarn so that the final single yarn fineness was 0.30 denier in one stage of hot drawing using a normal drawing machine, but fluffing and breakage occurred frequently during drawing. did. In Test No. 6, which adopted the method of the present invention, two yarns were drawn in the same manner at DR = 1.20, but there were no problems such as fluffing or cutting, and brand 120d/
A high-quality completely continuous ultrafine yarn with a strength of 480 f, a strength of 5.1 g/d, and a breaking elongation of 23% was obtained. Test No.7,
No. 8, 11 to 14 are uniform continuous ultrafine fibers of 0.20 denier or less without being stretched. For unevenness between single threads, 30 single thread diameters (2r) were randomly measured, and the average diameter of 5 thick single threads was 2max and the thin single thread diameter was 5.
Calculate the average 2min of the book, 2rmax-2rmin/2
It was calculated from r×100. (However, 2 is the average diameter of 30 single yarns.) For unevenness within a single yarn, measure the single yarn diameter at 30 random points in the length direction of a single single yarn with a length of 50 m, and calculate the average of 2'max for 5 thick single yarn diameters and the average of 5 thin single yarn diameters. 2'min is calculated and 2r'max-2r'mi
It was calculated from n/2r'×100. (However, 2' is the average single yarn diameter at 30 points.) Example 2 Using the same melt spinning apparatus as Example 1, the relative viscosity η=
Spinning polyethylene terephthalate temperature of 1.45
After heating and melting at 300° C., using the spinneret shown in Table 3, the yarn was taken at a constant take-up speed of 3500 m/min while changing the discharge amount Q per spinneret hole. At this time, from the first spray, heated chitsuso gas at 205°C was applied at 70°C so that the cooling conditions for the yarn directly below the spinneret surface satisfied the formula.
(Nl/min), from the second spray, air at 75℃ is 280℃
(Nl/min) was sprayed onto the spun yarn 4 and cooled and solidified. The spinning conditions and results are shown in Table 4.

【table】

【table】

[Table] In Test Nos. 1 and 2, the discharge amount Q per nozzle hole is high, so even if the yarn is taken at a take-up speed of 3500 m/min, the fineness of the single yarn does not decrease that much. Because the cooling and solidification of the spun yarn 4 is delayed and the spinning draft is small (the spinning drafts of No. 1 and 2 are 106 and 133, respectively), the tension applied to the yarn 4 is low, the spun yarn is unstable, and the spinning draft is small. Shaking and fusion tended to occur, and only yarns with large single yarn irregularities could be obtained.
Test Nos. 3 to 6 adopted the method of the present invention, and the spinning condition was good. In particular, yarns of Nos. 3 and 4 were drawn 1.95 times and 1.3 times, respectively, by the normal one-stage hot drawing, and the final single yarn We were able to create high-quality, completely continuous polyester ultrafine yarn with a fineness of 0.20 denier and no fuzz or yarn breakage.
Nos. 1 and 2 were drawn in the same manner at 3.2 and 2.6 times (final single yarn fineness 0.20 denier), respectively, but the fluff and
Continuous stretching was impossible due to frequent yarn breakage. still,
At this time, the vicinity of the yarn directly below the spinneret surface (5
The temperature T (℃) of the atmosphere at the position of 0.25mmψ
The results measured using a CA couple are shown in Table 5 below.

[Table] Test Nos. 1 to 6 were all within the temperature range that satisfied the formula. Moreover, the temperature fluctuation at each measurement point was stable within ±1°C. In the same manner as above test No. 1 to 6, Q=0.10g/
To obtain a yarn with a winding single yarn fineness of 0.26 denier, change the temperature of the heated titso gas and air that are blown onto the spun yarn in the same amount, and if the temperature falls within the temperature range of the formula (No. 8, 9) and cases where the temperature is outside the range of the formula (Nos. 7 and 10) were compared. The temperature of the atmosphere near the yarn is shown in Table 5, 2. In test Nos. 8 and 9, the single yarn unevenness was small and the spinning condition was good (some yarn shaking, no fused yarn), but in No. 7 and 10, the single yarn unevenness was large and the spinning condition was poor ( There was severe yarn sway, yarn breakage, or fused yarn occurrence.

[Table] Example 3 Polyethylene terephthalate with a relative viscosity η = 1.30 was produced using a melt spinning device with a cylindrical spraying device directly below the spinneret in a single stage spraying (at a position 30mm directly below the spinneret surface, inner diameter 110mmψ, spraying surface width 50mm). The spinning temperature
After heating and melting at 270°C, using the spinneret shown in Table 6, the discharge amount Q per spinneret hole was set to 0.075 g/min and the speed was 4500 m/min so that the average fineness of the single yarn was 0.15 denier. I picked it up and packaged it. In addition, air heated to 115℃ so that the temperature of the atmosphere near the yarn directly under the spinneret satisfies the formula is
= 120, 240, 200 (Nl/min), 300 respectively
(Nl/min) was sprayed. The spinning conditions and single grains at this time are as shown in Table 7.

【table】

【table】

[Table] In Test Nos. 1 to 3, the spinneret of the present invention was used, so the spinning condition was good, the single fiber unevenness was small, and high-quality continuous polyester ultrafine fibers were obtained. Especially exam no.
1 and 2 have one or two rows of holes and a very small K value, so they can be cooled uniformly, the thinning and solidification behavior between yarns is uniform, there is almost no yarn shaking, and there is no single yarn unevenness. We were able to stably obtain extremely small, high-quality continuous ultrafine threads. In Test Nos. 4 and 5, because the K value was large, a difference in cooling occurred between the yarns, making it difficult to achieve uniform thinning and solidification, and the spinning condition was also unstable, sometimes resulting in fusion and breakage. In particular, in Test No. 5 using an ordinary spinneret, there was frequent breakage (the yarn in the center swayed significantly and fusion occurred frequently), making it impossible to collect continuous yarn. Example 4 Using the same melt spinning apparatus as in Example 1, polyethylene terephthalate with a relative viscosity η = 1.36 was heated and melted at a spinning temperature of 280°C. Discharge amount Q is 0.075g/
The temperature T (°C) of the atmosphere near the spun yarn satisfies the formula, the first blowing is heated chitsuso gas, and the second blowing is blowing air at 50°C at various flow rates, and the take-up speed is A package was made at a constant speed of 4500 m/min. The spinning condition and single yarn unevenness at this time are as shown in Table 8.

[Table] Test Nos. 2 to 4 were conducted between 5 and 80 mm directly below the spinneret surface (blow surface width = 25 + 50 = 75 mm), and the blow air volume M (chitsuso gas air volume + air flow volume) was adjusted to satisfy the formula. It was sprayed onto the starting yarn, and the single yarn unevenness was small, and continuous spinning and winding was possible in a very stable manner. In test No. 1, the blowing air volume M was as small as 120 (Nl/min), so the accompanying airflow generated by the spun yarn could not be rectified, and the temperature of the atmosphere directly below the spinneret surface was over ±5°C. The yarn fluctuated and became frosty, and at the same time, the yarn swayed so much that continuous spinning was impossible. In addition, in test No. 5, the blowing air volume M was 500 (Nl/min)
Since the amount of spun yarn is larger than the amount of air taken out from under the spinneret surface as an accompanying air current, the blown wind disturbs the air flow directly under the spinneret, increases yarn sway, and sometimes induces breakage, making continuous spinning impossible. It was possible. Also, from the viewpoint of temperature control of the spinning chamber and economic efficiency, it is not preferable to spray heated gas onto the spun yarn more than necessary. Example 5 Using the same melt-spinning equipment and spinneret as in Example 4, polyethylene terephthalate/isophthalate copolyester with a relative viscosity η = 1.38 (isophthalate component 10 mol%) was heated and melted at a spinning temperature of 283°C. The discharge rate per spinneret hole was Q0.075 g/min, and the air volume of the gas blown from the first and second blowing was adjusted to change the yarn cooling conditions directly under the spinneret.
320 (Nl/min) constant, the temperature of the Chitsuso gas sprayed from the first spray, the air sprayed from the second spray,
The amount was changed variously, and the take-up package was created at a constant speed of 4500 m/min. At this time, the temperature T (°C) of the atmosphere in the vicinity of the spun yarn immediately below the spinneret surface, the spinning condition, and single yarn irregularities are as shown in Tables 9 and 10.

【table】

[Table] In Test Nos. 1 and 8, the temperature of the chitsuso gas and air in the first and second spraying was too high, so the temperature of the atmosphere near the yarn from 2 cm directly below the spinneret surface was higher than the upper limit temperature of the formula. , the tension of the spun yarn is extremely reduced (below 0.3g/d), the yarn sways violently, and the tightness and
There were many amputations. On the contrary, in Test Nos. 4 and 5, the temperature of the first sprayed Tituso gas was low, so the spinneret surface was 275
At the same time as the temperature drops to 1-3 cm directly below the spinneret.
The temperature of the atmosphere near the yarn was below the lower limit temperature of the formula, resulting in complete draft cutting and continuous winding was impossible. Test Nos. 2, 3, 6, and 7 were conducted using the method of the present invention, and the single yarn unevenness was small and the spinning condition was very good. Example 6 In Example 3, spinneret A and spinneret F
(D ₁ = 65 mm, number of hole arrangement rows = 3 rows, H = 350, K value =
Using the same spinneret A (except that the temperature was 0.123), the temperature of the heated air blown onto the spun yarn was changed so as to satisfy the formula, and the air was blown at the air volume shown in Table 11. The spinning conditions at this time are as shown in Table 11.

【table】

[Table] shows the method of the present invention.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a melt spinning apparatus showing one embodiment of the present invention, and FIG. 2 is a bottom view of a spinneret. 1... Spinneret, 2... First spraying, 3... Second spraying,
4... Spun yarn.

Claims (1)

[Claims] 1. When melt-spinning polyester, the discharge amount Q (g/min) per spinneret hole is 0.05 to
In the method for producing ultrafine fibers with a single yarn fineness of 0.1 to 0.5 denier of the spun drawn yarn, the following method is used ^: A method for producing ultrafine polyester fiber, characterized by satisfying conditions A and B. A: Use a spinneret in which the spinneret diameter (D) is 0.20 mm or less and the spinneret holes are arranged in a ring so that the value of K defined by the formula is 0 to 0.25, K = D ₂ - D ₁ /D ₁ [D ₁ and D ₂ are the minimum and maximum hole diameters of the spinneret holes] B: The flow rate M (Nl /min), and the atmospheric temperature T (°C) near the spun yarn is within the range of the formula. [V is the take-up speed (m/min) of the spun yarn, H
is the number of holes in the spinneret, H≧34] [η is the relative viscosity of polyester, 1.30≦η
≦1.45, L is the distance from the spinneret surface (cm)]