JPH0444021B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention is applicable to tire reinforcing materials, power transmission belt reinforcing materials, conveyor belt reinforcing materials and ropes, tent fabrics, typewriter ribbons, computer ribbons, etc., which require high strength. The present invention relates to an apparatus for efficiently drawing thermoplastic synthetic fibers stably and with good yield. (Prior Art) Changing the surface morphology of a stretching roller is described in Japanese Utility Model Publications No. 7512-1982, Publication No. 22890-1980, and Japanese Patent Publication No. 19888-1988, and is well known. Also, 1987-74081, 1987-
It is also known from Japanese Patent No. 17779 to carve narrow grooves in the axial direction of the stretching roller. However, the above-mentioned changes in surface morphology were aimed at alleviating the sudden rise in tension and preventing troubles caused by oil scum. (Problem to be solved by the invention) In recent years, demand for higher strength synthetic fibers has been increasing from the viewpoint of resource and energy conservation, but simply increasing the draw ratio will cause a rapid deterioration in production yield. However, high-strength synthetic fibers cannot be produced. For this purpose, simply changing the surface morphology of the various rollers described above is ineffective, and it has not been possible to obtain high-strength synthetic fibers with excellent productivity. In response, the present inventor clarified the role of each part of the drawing roller by analyzing the deformation process occurring on the first-stage drawing roller, and achieved the optimal deformation process of thermoplastic synthetic fibers on the drawing roller. The company discovered a stretching roller that enables the production of higher-strength synthetic fibers with more stable yields. (Means for Solving the Problems) That is, the present invention provides a first-stage drawing roller in a two-stage drawing device for thermoplastic synthetic fibers such that: It has a surface characteristic that is lower than that of the introduction part and has a coefficient of friction against the yarn that changes continuously or stepwise; It is characterized by being made smaller continuously or stepwise compared to the introduction part. In order to improve productivity in the production of thermoplastic synthetic fibers, the drawing speed must be increased to over 1000 m/min, and the direct spinning/drawing method is widely used for yarn production in fields that require particularly high strength. . For this reason, in high-speed stretching, it is necessary to stretch in the first stage to a natural stretching ratio (stretching ratio at which the tension during stretching disappears), and then in the second stage to stretch between two pairs of rollers until a predetermined strength is developed. is necessary. The stretching device employed in this case includes three pairs of stretching rollers 1, 1', 2, 2', 3, as shown schematically in FIG.
3', the undrawn yarn Y supplied to the drawing section is preheated by rollers 1 and 1', and the first drawing is performed between the heated rollers 2 and 2'. A second stage of stretching is performed between the film 2' and rollers 3, 3', and the film is wound up into a winder 4. In such a drawing device, in the second stage drawing, the drawing deformation process from rollers 2, 2' to rollers 3, 3' causes single yarn breakage,
Although it was conceptually thought that it had a large effect on thread breakage, its details and function were unknown. The present inventor has discovered that such second stage stretching occurs substantially between the rollers 2 and 2' in the latter half of each turn wound around the rollers 2 and 2',
The mechanism of action was clarified. In other words, on the first stage stretching rollers 2, 2', the second
A considerable portion of stage stretching occurs, and in order to improve the stretching properties, it is necessary to smoothly deform the rollers 2 and 2'.
2', it is necessary that the coefficient of friction of the yarn outlet portion be lower than that of the yarn introduction portion. In this case, in order for the deformation to occur smoothly, it is necessary that the change be continuous or stepwise. On the other hand, in order to draw thermoplastic synthetic fibers in the second stage, it is necessary that the yarn drawn in the first stage be sufficiently warmed, but if it is heated too much, crystallization will progress too much. It is also well known that the stretchability decreases when Therefore, the optimal heating with rollers 2 and 2' is that the heat transfer contact surface is long at the roller yarn introduction part where the yarn temperature is low, and the heat transfer contact surface is long in the roller yarn outlet area where the yarn temperature increases due to heat. It is necessary to shorten the heat transfer contact surface in order to reduce the supply of heat to suppress crystallization. FIG. 1 shows a specific example of a shape in which the coefficient of friction decreases from the yarn introduction part to the yarn outlet part, and the heat transfer contact surface becomes shorter from the yarn introduction part to the yarn outlet part. In the figure, 11 is a roller main body.
In this case, the width a of the crest 12a gradually becomes narrower from the thread introduction part 13 on the root side to the thread lead-out part 14 on the tip side.
A groove 12 in which the width b of the valley 12b gradually becomes wider is carved along the entire circumference in the axial direction. With such a tapered peak/valley structure, _{the ratio a 1 /}
It is preferable that a ₂ is in the range of 0.7 to 0.4. When this ratio is over 0.7, there is a small difference in the coefficient of friction, making it difficult to perform smooth deformation, and when it is under 0.4, the heat transfer contact surface at the deformed part becomes too short, and the yarn tends to cool down and its drawability decreases. . Roller 11 in Figure 1
Fig. 2 shows an example of a roller 11' that changes stepwise. In the groove 12' formed in this case, the mountain width a' changes stepwise over three stages and decreases over four stages from the yarn introduction part 13' to the yarn outlet part 14'. It is something. (Example) Nylon 6 having an intrinsic viscosity [η] (measured as a solution in m-cresol at 35° C.) of 1.60 was melt-spun, oiled, and then stretched and wound using the apparatus shown in FIG. 3. The speed of rollers 1 and 1' was 450 m/min, and the rollers 2 and 2' had the shape shown in Figure 1, and were preheated at 60°C.
The mountain width of the yarn introduction part is 1.9m/m, and the valley width is 0.1
m/m, the mountain width of the yarn lead-out part is 0.7m/m, and the valley width is
A roller having a diameter of 1.3 m/m, 250 grooves, and a continuous tapered width was used as the first-stage stretching roller. The yarn was wound 5 turns at a temperature of 180℃, and rollers 1, 1' and rollers 2,
The first stage stretching was carried out at 3.5 times for 2'. Furthermore, the rollers 3 and 3' were heated to 210°C, and the second stage was stretched to 1.5°C.
The film was heat-treated by stretching at a double speed, and then wound into a winder at 2200 m/min with a slight overfeed. The single yarn denier of the obtained drawn yarn is 6de.
The results of the yarn quality and drawing yield are shown in the following table. For comparison, a first-stage drawing roller having a groove width of 1.0 m/m, a valley width of 1.0 m/m, and the same width from the yarn introduction section to the yarn exit section was used as the first-stage drawing roller. The results of stretching in the same manner as above are also shown in the table below.

[Table] (Effects of the invention) As is clear from the examples, when the roller according to the present invention is used as the first-stage drawing roller, even high-strength yarns of 10 g/de or more, which had conventionally had poor yields, can have good yields. Production is now possible at Tome.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a specific example of the present invention, FIG. 2 is a plan view showing another specific example, and FIG. 3 is a schematic diagram of a two-stage stretching apparatus using rollers of the present invention. 2, 2'...First stage stretching roller, 11...
Roller main body, 12...groove, 13...yarn introduction part, 14...yarn lead-out part.

Claims (1)

[Scope of Claims] 1. In the first stage drawing roller in a two-stage drawing device for thermoplastic synthetic fiber yarn, (1) the coefficient of friction between the threads at the thread outlet section is higher than that at the thread introduction section. It has a surface property in which the coefficient of friction against the yarn is low and changes continuously or stepwise; A stretching roller characterized by being made smaller or smaller in stages. 2. Claim 1, in which the surface friction coefficient and the heat transfer contact surface are changed continuously or stepwise by means of axial grooves in which the thread introduction part and the thread lead-out part have different mountain widths and valley widths. The stretching roller described in . 3. The stretching roller according to claim 2, which has a groove shape in which the mountain width becomes gradually narrower and the valley width gradually becomes wider from the yarn introduction part to the yarn outlet part. 4 The ratio of the mountain width of the thread-like lead-out part and the thread-like introduction part is 0.7~
Stretching roller according to claim 3 in the range of 0.4.