JPS6262161B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for drawing polyester undrawn yarn tow (hereinafter referred to as "tow"). Known methods for stretching tow include heating and stretching the tow in a heating bath, heating and stretching the tow by spraying heated liquid or steam, and heating and stretching the tow with heated rollers. . The methods of using a heating bath and the method of injecting heated liquid or steam have no problems with the operability and quality of stretching, but because they use high-temperature liquid or steam, there is a problem with work safety. Further, heat dissipation due to evaporation from the heating liquid or the like is largely dissipated by steam, which is wasteful from an energy saving standpoint. On the other hand, the method using roller heating has high operational safety and reduces thermal loss in terms of energy saving. When stretching a tow, it is important that the netting points are aligned in a straight line in the width direction of the tow. If the netting points are not lined up in a straight line across the width of the tow, as shown in Figure 2, the positions of the netting points of adjacent yarns are different, causing one yarn to drag the other. As the thread stretches, tension occurs and thread breakage occurs. In the case of roller heating, in order to align the netting points in a straight line in the width direction of the tow, as shown in Figure 1, a knipper roller 2 is attached to the exit of the heating roller to forcibly fix the netting points. There is. This is because the stretching point can be easily fixed by gripping the tow with the nip roller 2 so that the stretching tension is not transmitted to the tow before the nipping roller 2. In this case, the temperature of the heating roller influences the position of the netting point.
In other words, if the roller temperature is lower than the appropriate temperature,
As shown in FIG. 3, the netting point moves away from the knitting roller 2 and toward the second roller 3. The farther the netting points are from the knitting roller 2, the more the netting points become uneven, causing yarn breakage as described above, and yarns that are not drawn to pass through the drawing process.
On the other hand, if the temperature of the heating roller is higher than the appropriate temperature,
As shown in FIG. 4, the netting point moves to before the gripping point of the pinch roller 2. In this case, since the speed of the drawn yarn is several times higher than the circumferential speed of the nip roller 2, the drawn yarn and the nip roller cause severe friction, resulting in yarn breakage. Even if the heating roller temperature is appropriate, the position of the netting point will change if the stretching speed changes. When the netting points are aligned near the gripping point of the nip roller and the stretching is being performed normally, if the stretching speed has to be lowered due to occurrence of roller wrapping, etc., reducing the stretching speed will cause netting. The point crosses the gripping point of the nip roller (moves before the gripping point). At this time, the drawn yarn causes intense friction with the knit roller, resulting in frequent yarn breakage. This is because the heating time of the undrawn yarn by the heating roller becomes longer due to a decrease in the drawing speed, and the thermoplasticity of the undrawn yarn increases.
This state continues until the normal stretching speed is restored, and during this time, thread breakage occurs, causing roller wrapping and quality abnormalities. The present invention was arrived at as a result of various studies aimed at improving the above-mentioned situation. That is, in the present invention, in a method in which polyester undrawn yarn tow is heated with a heating roller and then stretched in two or more stages, when the stretching speed is changed: (a) When the stretching speed is decreased from a steady stretching speed; (b) The stretching ratio in the first stage is lowered without changing the temperature of the heating roller, and the stretching ratio in the second and subsequent stages is increased so that the total stretching ratio is constant; (b) The stretching speed is changed to the steady stretching speed. When increasing the polyester to This is a method of drawing fiber tow. The present invention is characterized in that the stretching tension is varied in order to prevent the position of the netting point from shifting due to a change in the heating time of the undrawn yarn with the heating roller. If the stretching tension is increased, the netking point will move closer to the gripping point of the nipping roller,
If the tension is lowered, the netting point will move away from the gripping point of the nip roller. Therefore, if the heating time is too long, the netting point will exceed the gripping point of the nipping rollers, so the stretching tension may be lowered to align the netting point near the gripping point of the nipping rollers. In order to change the stretching tension, the stretching ratio must be changed, but 2
It has been found that when stretching is carried out in stages or more, the same quality can be obtained as long as the total stretching ratio is constant. Therefore, in the present invention, the netting point can be adjusted by changing the stretching ratio in the first stage without changing the temperature of the heating roller, and changing the stretching ratio in the second and subsequent stages so that the total stretching ratio is constant. Adjust the position. Changing the draw ratio when the draw speed changes has to be done automatically in practice. It is practically impossible to manually change the drawing ratio in response to the drawing speed each time the drawing speed changes. Therefore, automatic equipment is required to continuously change the first-stage stretching ratio, second-stage stretching ratio, etc. in accordance with the stretching speed, and it is appropriate to control the speed of each roller using an inverter or the like. Also,
In the case of a common drive system in which all rollers are connected by a line shaft, as shown in Figure 5, a continuously variable transmission is installed in the drive system of the second roller so that the rotation ratio of this continuously variable transmission is linked to the drawing speed. do it. The present invention will be explained in detail below based on the drawings. FIG. 5 shows an embodiment of the drive system for each roller of the present invention. In FIG. 5, a constant number of revolutions (speed) is set by a motor 14 with a continuously variable transmission. The gearbox 11 is for transmitting rotation and changing the rotation speed at a fixed ratio. The continuously variable transmission 12 is for changing the rotation speed of the first roller. The continuously variable transmission 13 is for changing the rotation speed of the second roller. Therefore, when the rotation ratio of the continuously variable transmission 13 is changed, the first-stage stretching ratio and the second-stage stretching ratio change in inverse proportion while the total stretching ratio remains constant. In other words, since the rotational speed ratio of the first roller 1 and the third roller 4 is constant and the total stretching ratio remains constant, only the rotational speed of the second roller 3 changes. Allocation changes.
In FIG. 5, when yarn winding on the roller due to yarn breakage is detected and the drawing speed (speed of the third roller) decreases, the speed of the second roller 3 is reduced by the continuously variable transmission 13 to reduce the first-stage drawing ratio. Lower the netting point as much as possible to keep the netting point at the gripping point of the nip roller. That is, when the drawing speed decreases, the heating time of the tow with the first roller 1 becomes longer, so that the undrawn yarn becomes easier to draw, and the netting point moves toward the first roller. When the first-stage stretching ratio is lowered, the netting point moves toward the second roller, so the first-stage stretching ratio may be lowered while keeping the total stretching ratio constant. That is, the continuously variable transmission 13 may be operated to reduce the rotational speed of the second roller 3, thereby decreasing the first-stage stretching ratio and increasing the second-stage stretching ratio while keeping the total stretching ratio constant. On the other hand, when increasing the stretching speed (speed of the third roller), such as at the start of operation or when moving from low-speed operation to high-speed operation, the rotation speed of the second roller 3 is set so that the first-stage stretching ratio increases. Raise and hold the position of the netting point at the gripping point of the knitting roller. In this case as well, since the speed ratio of the first roller and the third roller is constant, the total stretching ratio is constant. In this way, even when the drawing speed is changed, the netting point remains at a constant position, so yarn breakage does not occur and stable operability and quality can be achieved. Next, an explanation will be given using an example. Example Using a polyethylene terephthalate chip with an intrinsic viscosity of 0.660 measured in a mixed solution of equal weights of phenol and tetrachloroethane at 20°C, the spinning temperature was 295°C,
500 at a discharge rate of 281g/min and a spinning speed of 1180m/min.
Melt spun from a hole spinneret. The obtained undrawn yarn sub-tow was bundled into an undrawn yarn tow of 2,500,000 Den, which was then fed into a drawing machine. The flow sheet of the stretching machine is as shown in Figure 1. The stretching speed is changed at the first roller temperature of 70°C, the second roller temperature of 70°C, the third roller temperature of 70°C, and the heating drum temperature of 185°C. Stretching was carried out by changing the stretching ratios in the first and second stages. (Test No. 13 is the steady stretching condition) The maximum stretching ratio when the stretching speed was varied is shown in Table 1. Position 0 of the stretching point is optimal. On the other hand, a case where the position of the stretching point exceeds the gripping point of the nip roller and moves toward the first roller, and a case where the stretching point moves toward the second roller are shown, respectively. Further, Table 2 shows the results obtained by changing the first roller temperature to 65°C and 75°C. In addition, the second
The temperature of the roller, third roller and heating drum is as follows when the first roller temperature is 65℃.
The temperature of the first roller is 70℃ and 185℃, respectively.
When the temperature was 75°C, the temperatures were 75°C, 75°C, and 185°C, respectively. Note 1: Location of the netting point; expressed as the distance from the nip gripping point. The first roller side was negative, and the second roller side was positive. Note 2 Heat shrinkage rate: Shrinkage rate (%) when processed in a hot air dryer at 170°C for 15 minutes. Note 3: Exhaustion rate: It is measured by the following measurement method, and is the amount of dyeing when dyed expressed as a ratio (%) to the fiber.

【table】

【table】

[Table] Measurement method (1) Scouring score roll #400 (manufactured by Kao Atlas Co., Ltd.)
2g/bath ratio 1:50 Temperature x time 60℃ x 30 minutes (2) Dyeing Dye Eastman Polyester Dark Red FL (manufactured by Eastman Kodak Co.) 5.5% owf Auxiliary agent Disper TL (manufactured by Meisei Chemical Co., Ltd.)
1g/ Ammonium sulfate 2g/ Formic acid 0.1g/ (3) Reduction cleaning Sunmol RC-100 (manufactured by NICCA Chemical Co., Ltd.)
2g/hydrosulfite 2g/sodium hydroxide 1g/bath ratio 1:50 Temperature x time 70℃ x 30 minutes (4) Hot water washing 60℃ x 10 minutes (5) Calculate the exhaustion rate using the residual liquid colorimetric method . Exhaustion rate = (1-D/D ₀ ) x 100 (%) D = Optical density of residual liquor after dyeing D ₀ = Optical density of dye liquor before dyeing

[Brief explanation of the drawing]

Figure 1 is a flow sheet of a polyester fiber tow drawing machine, Figure 2 is an explanatory diagram showing the state of the netting points, and Figures 3 and 4 are schematic diagrams of the vicinity of the knitting rollers to show the positions of the netting points. The perspective view and FIG. 5 are schematic explanatory diagrams showing the drive system of the stretching machine. 1: first roller, 2: nip roller, 3:
2nd roller, 4: 3rd roller, 5: heating drum, 6: netting point, 7: tow, 8: final roller of the first rollers, 1
0: Networking point position, 11: Gearbox, 12, 13: Continuously variable transmission, 14: Drive motor.

Claims (1)

[Scope of Claims] 1. In a method in which undrawn polyester yarn tow is heated with a heating roller and then stretched in two or more stages, when the stretching speed is changed, (a) the stretching speed is lowered from the steady stretching speed; (b) Keep the stretching speed constant by lowering the first-stage stretching ratio without changing the heating roller temperature, and increasing the second-stage and subsequent stretching ratios so that the total stretching ratio remains constant. When increasing the stretching speed, the stretching ratio in the first stage is increased without changing the temperature of the heating roller, and the stretching ratio in the second and subsequent stages is decreased so that the total stretching ratio is constant. A method for drawing polyester fiber tow.