JPS627290B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention has at least two endless belts, both belts run intersectingly at a certain angle, and This invention relates to a method for temporarily twisting a low-strength yarn using a friction temporary twisting device that is arranged so that the surfaces of the two belts come into contact with each other at the intersection of both belts, and grips and twists the yarn at the intersection of both belts. A temporary twisting spindle is currently widely used as a temporary twisting device. However, the processing speed with the normal spindle type depends on the running speed of the thread.
The practical upper limit is 100 m/min to 200 m/min.
Further, although the temporary twisting spindle has sufficient twisting ability, it has no yarn feeding ability and the yarn is forcibly taken off by a take-up roller. Therefore, the unraveling tension becomes extremely high, which causes a decrease in strength and the generation of fuzz. In addition to these spindle types, various types of friction twisting devices have been proposed. As one type of conventional frictional temporary twisting device, a device is known in which a thread is passed through so as to come into contact with a plurality of frictional rotating bodies having surfaces with a large coefficient of friction, and the thread is twisted by the frictional rotating bodies. Such a friction twisting device can easily obtain a higher processing speed than a spindle type, and has a large yarn feeding effect, which can greatly reduce the loosening tension. However, it has the disadvantage that the minimum tension required to obtain a constant number of twists is higher than that of the spindle type. The present invention eliminates the drawbacks of the prior art as described above,
To provide a method for temporarily twisting low-strength yarn at high speed and in a stable quality state. In order to achieve this object, the present invention has the following configuration. That is, when temporarily twisting a thermoplastic synthetic fiber highly oriented undrawn filament yarn having a strength of natural draw ratio x strength of 4.5 g/d or less, at least two endless belts are provided, and both belts have an angle. The belt crossing angle (θ ) is 115°≦θ≦125
This is a temporary twisting method for low-strength yarn, which is characterized by performing temporary twisting under the conditions of belt speed ratio (VR) of 1.50≦VR≦1.60 and tension ratio (A) of 0.7≦A≦1.3. The method for temporarily twisting a low-strength yarn according to the present invention will be explained in more detail. When applying a temporary twist to the running yarn,
Theoretically, it can be explained that in order to insert a predetermined twist without imparting running resistance to the yarn, it is important to apply an external force that matches the twist angle with respect to the yarn axis. Therefore, in order to effectively twist the running yarn during friction twisting, it is necessary to apply a rotational force (twisting component) perpendicular to the yarn axis, and at the same time apply a running force (feeding component) in the direction of the yarn axis. It is necessary to apply a frictional force and a frictional velocity to the yarn to provide the component (component). In the friction temporary twisting device used in the present invention, the determining factors of the twisting component and the yarn feeding component are the belt crossing angle (Θ) and the belt speed ratio (VR). The belt crossing angle (Θ) is Θ in Figure 1,
This indicates the sum of angles Θ ₁ and Θ ₂ (Θ ₁ =Θ ₂ ) at which each twister belt intersects with the running thread (Y), and 115°≦Θ≦125° is required. This is the range for obtaining the number of tentative twists necessary to obtain a crimped yarn with normal crimp characteristics. If Θ is less than 115°, the normal number of temporary twists cannot be obtained, and only a low-crimp yarn can be obtained. If Θ exceeds 125°, the number of temporary twists will be too large, and the processing tension required for stable processing will increase, causing problems such as a decrease in strength and the generation of fuzz. The preferred belt crossing angle is 120°≦Θ
≦125°. The belt speed ratio (VR) is the ratio of the surface speed of the twister belt 5 to the surface speed of the Ist delivery roller 6 in Fig. 2, and is expressed as twister belt surface speed/processing speed, and must be in the range of 1.50≦VR≦1.60. It is. This is a range in which to obtain the desired crimped yarn, the necessary number of temporary twists is obtained, the processing tension is limited, and problems such as strength reduction and fluffing do not occur. If VR is less than 1.50, both the twisting component and the yarn feeding component are small, resulting in a decrease in the number of tentative twists and an increase in unraveling tension, resulting in an unfavorable state in which strength decreases and fuzz occurs in low-crimp yarns. . On the other hand, if VR exceeds 1.60, the process tension will increase due to the excessive number of twists, resulting in a decrease in strength and
Problems such as fuzz generation occur. A preferred belt speed ratio (VR) is 1.55≦VR≦1.58. The tension ratio (A) is the ratio of the tensions at two locations on the running yarn (Y) shown in FIG.
T ₁ is the tension in the tension zone immediately before the tension, and the temporary twisting device 5 is
If the tension in the immediately following unraveling zone is T ₂ , then T ₂ /
It is expressed as T ₁ (resolved tension/added tension), and the range of 0.7≦A1.3 is required. This is a range in which there is no generation of unresolved nen due to a decrease in the unresolved tension, and there is no decrease in strength due to an increase in the unresolved tension. In other words, if the tension ratio is less than 0.7, the actual unraveling tension will be very low, and sufficient unraveling will not occur, resulting in the generation of unresolved yarn, making it impossible to obtain a normal crimped yarn. Furthermore, if the tension ratio exceeds 1.3, the unraveling tension will increase, resulting in a decrease in strength and the generation of fuzz. The preferred tension ratio (A) is 0.8≦A≦
It is 1.0. The yarn used in the present invention is a thermoplastic synthetic fiber with particularly low strength, that is, a thermoplastic synthetic fiber highly oriented undrawn filament yarn having a strength of 4.5 g/d or less when the value of natural drawing ratio x strength is 4.5 g/d or less. A polyester yarn copolymerized with about 1 to 10 mol % of 5 sodium isophthalic acid units is most suitable. These low-strength yarns suffer from a large decrease in strength when used in the conventional temporary twisting method, and can only be temporarily twisted at a very low speed due to the problem of generating fuzz, but this is possible according to the present invention. . Since the present invention has the above configuration, it has the following features. In other words, the value of natural stretch ratio x strength is 4.5g/
d or less, low strength thermoplastic synthetic fiber highly oriented undrawn filament yarn can be stably processed at high speed.
Furthermore, a high-quality crimped yarn without fuzz can be obtained by suppressing the decrease in strength due to the temporary twisting process. Furthermore, since processing can be performed at a higher speed than the conventional temporary twisting method, processing costs are significantly reduced. In the present invention, highly oriented undrawn yarn means, in the case of polyester, one obtained at a spinning speed of about 2500 m/min or more. Example Processing was carried out using the manufacturing apparatus shown in FIG. 2 under the conditions shown in Table 1.

[Table] As shown in Table 1, experiment numbers 2, 3, 6, 7, 10, 11
was within the scope of the present invention, and thus a preferable crimped yarn was obtained. On the other hand, in Experiment No. 1, because the belt angle (Θ) was small, the number of twists was insufficient and only low crimp could be obtained. No. 4 had an excessive number of twists due to the large belt angle (Θ), and at the same time, the strength of the crimped yarn was significantly reduced due to the increase in the tension ratio. In No. 5, since the belt speed ratio (VR) was small, the strength of the crimped yarn decreased due to an increase in the tension ratio (A) due to an insufficient yarn feed component. No. 8 had a large belt speed ratio (VR), so the strength of the crimped yarn decreased due to an excessive number of twists. Number 9 had a large belt speed ratio (VR), so unresolved particles were observed due to a decrease in tension ratio (A). In No. 12, the strength of the crimped yarn decreased as the tension ratio (A) increased.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the relationship between the friction tentative twisting device and the running yarn used in the present invention. FIG. 2 is a schematic diagram of a manufacturing apparatus showing an embodiment of the present invention. 1... Supply yarn, 2... Tension adjustment device, 3... Feed roller, 4... Heat treatment device, 5... Temporary twist device, 6...
1st delivery roller, 7... Winding device, 8... Package cage, Y... Running thread.

Claims (1)

[Claims] 1. When temporarily twisting a highly oriented undrawn filament yarn of a thermoplastic synthetic fiber having a strength of natural stretch ratio x strength of 4.5 g/d or less, at least two endless belts are provided, and both ends are The belts are arranged to intersect at an angle and run so that their surfaces touch each other at the intersection, and a temporary twisting device is used to grip the yarn at the intersection of both belts and give it a twist. The feature is that the temporary twisting process is performed under the following conditions: belt crossing angle (θ) is 115°≦θ≦125°, belt speed ratio (VR) is 1.50≦VR≦1.60, and tension ratio (A) is 0.7≦A≦1.3. A temporary twisting method for low-strength yarn. 2. Temporary twist of low-strength yarn according to claim 1, characterized in that the thermoplastic synthetic fiber highly oriented undrawn filament yarn is a polyester yarn copolymerized with a 5-sodium sulfoisophthalic acid component. Method.