JPS5824527B2 - Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of cutting multifilament fibers into short fiber bundles.

BACKGROUND ART Conventionally, the technique of cutting multifilament consisting of long fibers into short fiber bundles is well known as tow spinning.

However, such conventional technology has a phenomenon known as "collective breakage", in which the ends of the cut fibers are aligned, resulting in "rebound".
However, there was an unavoidable defect that the ends of the cut fibers were disturbed due to the reaction of the tension before the cut.

In an attempt to reduce the number of group breaks, if the thickness of the multi-filament strip is made thinner and the arrangement density of the fibers that make up the multi-filament strip is made coarser, bounces will occur frequently.

Since we are trying to cut fibers that are symmetrical and have sufficient strength, the position in the drawing region at which the fibers are cut depends on the interaction of the fibers, that is, the state of convergence of the multifilaments.
The fibers in the vicinity of the stretched fibers are subjected to a large drafting force at that part, and inevitably break in groups.

Therefore, it is extremely difficult to cut multifilament yarns, which are called multifilament yarns and have a small number of constituent fibers that can be used as is for clothing, into short fiber bundles by cutting.

In particular, tows, which are made from multi-filament fibers consisting of several thousand to hundreds of thousands of fibers, are cut into short fiber bundles, and there are many group cuts and rebound fibers, so they are put directly into a spinning machine and spun. When made into yarn, the yarn has many neps and slubs, and yarn breakage occurs frequently during spinning. Therefore, in the normal long stable spinning process, drafting, combing, doubling, etc. are repeated to eliminate group breakage and rebound fibers. It is customary to make corrections before spinning into yarn.

Therefore, not only does the manufacturing process become longer and processing costs increase, but the multi-filament yarn, which originally had a completely uniform number of fibers in its cross section, has uneven thickness comparable to that of spun yarn obtained from raw cotton or wool. It becomes spun yarn.

Furthermore, the tension cutting device cuts thousands to hundreds of thousands of condensed single fibers that are strong enough to be used as clothing fibers, so they are sturdy, large, and complex. There was a drawback.

The present invention aims to improve each of the above-mentioned drawbacks,
The present invention provides a method for producing a multi-filament fiber that can be cut with a relatively weak force and that can be made into a uniform short fiber bundle just by passing through the tension cutting process.

In other words, the present invention provides ``a multifilament in which low-strength regions and high-strength regions alternate in the length direction of the constituent single fibers, and in which the low-strength regions exist randomly in the cross-sectional direction. When cutting into a short fiber bundle by tension cutting, a pair of rollers and a guide are used on the supply side of the tension cutting area, and the multi-filament is passed between the pair of rollers two or more times to be gripped and transferred. A method for producing a characteristic stretch-cut fiber bundle.

”.

It will be explained in more detail.

To form alternating low-strength parts and high-strength parts in single fibers, undrawn fibers are incompletely stretched below the natural stretching ratio to create stretched, unstretched, or semi-stretched parts, and thick parts and When thin parts are made alternately and heat treated at a temperature higher than the crystallization temperature of the fiber, the parts with a low degree of molecular orientation (thick parts) become more brittle and have lower strength than the parts with a higher degree of molecular orientation (thin parts). .

In order to cause the low-strength portions to exist randomly in the longitudinal direction and cross section of the multifilament, each single fiber constituting the multifilament may be individually subjected to the incomplete stretching and heat treatment described above.

In order to make the low-strength parts exist randomly by subjecting the undrawn multifilament to the incomplete stretching and heat treatment, it is necessary to make the undrawn multifilament have weak cohesiveness and to allow mutual movement of fibers. Good, multi-filament twist.

It is an undrawn multifilament yarn with a weak degree of intertwining of fibers and bonding of fibers with each other, and when expressed in terms of the number of twists, untwisted is preferable for thick multifilament yarns such as tow. In the case of thin multi-filament strips such as 20 times/m or less, it is desirable.

If the single fibers constituting the undrawn multifilament behave sufficiently independently, the incomplete drawing can be performed by cold drawing, but even if the fibers are somewhat bunched within the above limits, the purpose can be achieved by heating the drawing region. .

In this case, the heating body is preferably a non-contact type, but even a contact type heating body may be used as long as it has a small curvature.

If the curvature is large, for example, a so-called hot pin, the position of the stretching point is fixed and the purpose cannot be achieved.

Although there are many possible methods and conditions for performing the incomplete stretching and heat treatment, the method described below is particularly excellent.

First, an undrawn multifilament with weak bundling property is incompletely drawn in a zone heated to a temperature higher than the crystallization temperature of the fiber.

The multifilament yarn obtained in this way achieves the purpose as it is, but it also has the following properties: to reduce the stretching part, to promote the difference in strength between the low-strength part and the high-strength part, and to improve the heat-resistant dimensional stability. For the purpose of improving the level dyeing property, etc., it is preferable to carry out tension heat treatment at a temperature higher than the temperature of the heating zone in the above-mentioned stretching step.

In this second heat treatment, it is preferable that the fibers of the multifilament are restrained, and when the multifilament is thin, false twisting is suitable.

When the thus obtained multi-filament fiber having low-strength parts randomly is drawn, the fibers are cut at the low-strength parts, so that the occurrence of group breakage is extremely small.

Therefore, even thin multi-filament fibers can be uniformly collected, such as when short fiber bundles obtained by cutting multi-filament fibers are bundled without drafting to obtain yarn for general clothing. It is possible to obtain uniform short fiber bundles through tension cutting.

The present invention employs the steps described below in order to greatly shorten the spinning process.

That is, the multi-filament yarn having random low-strength portions obtained by the above method is cut into short fiber bundles, and the short fiber bundles are immediately bundled to form yarn without being stored once. .

The means of focusing is twisting or entangling the fibers.

Adhesion bonding or any other method may be used.

By adopting the above process, the spinning process can be greatly shortened, but it is meaningless unless the distance between the spindles is made compact, as in the spinning process of conventional spinning processes, especially ring spinning machines and open-end spinning machines. It becomes a thing.

For this purpose, the tension cutting device must be made simple.

To this end, in the above process, the present invention provides a drafting zone supply side for tension cutting with a pair of rollers that grip and transfer the multi-filament strip, and a pair of rollers that grip and transfer the multi-filament strip two or more times. It is made up of a guide that folds back the fibers.

The present invention will be explained in more detail.

FIG. 1 is a schematic diagram showing a multi-filament gripping method used in a conventional tension cutting device.

In order to increase the force with which the multi-filament is gripped, the number of gripping points is increased and the contact between the roller and the multi-filament is extended.

Conventionally, there have been many combinations of three rollers, and typical examples include the self-locking type (a), the two-point gripping type (b), and the three-stage clamping type (C).

This conventional method is mechanically complex and requires a large and sturdy device to tighten with a large force.

Since one of the purposes of the present invention is to make the space between the spindles compact, it is difficult to adopt such a conventional method.

Since the present invention supplies thin multifilament strips, the second
As shown in the figure, the multifilament yarn Y can be folded back by the folding guide 3 and gripped by the pair of rollers 1 and 2 as many times as necessary.

The folding guide 3 includes, for example, a rotary separate roller 3 as shown in FIG. 3d. Le grooved fixed separate guide 3.2. Snail wire 3.3 or the like can be used.

Next, an example will be described.

FIG. 4 shows a method of supplying the multifilament yarn Y to the drafting area according to the method of the present invention, in which the multifilament yarn Y is gripped and drafted by a pair of rollers 10 and 11.

Since the multi-filament yarn Y is processed by the above-mentioned method, the occurrence of group breaks is extremely low, and the fibers are cut uniformly to form uniform short fiber bundles.

If rebound fibers are a problem, it is preferable to cut the multifilament Y in a wet state as shown in FIG.

That is, the liquid in the liquid bath 13 is applied to the multifilament yarn Y by the liquid applying roller 12, and the excess liquid is removed by the liquid squeezing device 14, and then the tension is cut.

Alternatively, the drafting area may be lightly gripped with an apron, and FIG. 6 is a schematic diagram showing an embodiment in which a hollow type is used, and FIG. 7 is a schematic diagram showing an embodiment in which a solid type is used.

Next, an example will be described.

Example 1 An embodiment of the present invention as shown in FIG. 4 was compared with an embodiment in which the bank roller in FIG. 4 was replaced with a conventional method.

The following 5 items were evaluated for the 8 aspects.

Simplicity: Manufacturing cost of the device Operability: Thread hooking time when thread breaks: (V2-V)/(v,, -v,) The filament speed is determined by V=V2・D2/D1.

Dl: Thickness denier of multi-filament yarn before tension cutting) D2: Thickness denier of multi-filament thread after tension cutting) Workability: Number of yarn breaks Durability: Unified expression of evaluation results of number of days to replace rubber rollers among back rollers To do this, I converted it as follows.

Within each item, the smaller the number that appears in the evaluation results, the more preferable it is, that is, simplicity and operability.

Regarding operability, (minimum evaluation/evaluation of each aspect)
Convert with 0.

On the other hand, for items with higher numbers appearing in the evaluation results, that is, gripability and durability, the conversion is performed by (evaluation of each aspect/maximum evaluation) x100.

After conversion, a larger number is preferable, and the results are summarized in the table below.

In the table, "single gripping" means gripping only once with a pair of rollers.

The back roller has a diameter of 40 mm and is gripped (roller width) 4
Standardized to 0mm.

The front roller had a diameter of 40 mm, a grip width of 12 mm, and a grip force of 4 kg.

Gripability was confirmed by the fact that when the multifilament thread was held and pulled out by hand, it was cut without slipping.

The above table shows that the present invention is superior.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a multifilament gripping method used in a conventional tension cutting method. FIG. 2 is a schematic diagram showing a multi-filament gripping method in the tension cutting method of the present invention. FIG. 3 is a schematic diagram showing an example of the use of a folded guide in the tension cutting method of the present invention. FIG. 4, FIG. 5, FIG. 6, and FIG. 7 are schematic diagrams showing embodiments of the present invention. 1: Back bottom roller, 2: Back top roller, 3
, 3.1 , 3.2 , 3.3: Folding guide;
3.1: Separate roller, 3.2: Separate guide, 3.3 Varnish nail wire, 4: Bottom apron roller, 5: Hollowed top apron roller, 5': Solid top apron roller, 6: Bottom apron, 7 : Top apron, 8: Bottom apron roller, 9: Top apron tensor, 10: Front bottom roller, 11: Front top roller, 12: Liquid applying roller, 13: Liquid bath, 14
: Liquid squeezing device, Y: Multifilament.

Claims (1)

[Claims] 1 A multi-filament fiber in which low-strength parts and high-strength parts exist alternately in the length direction of the constituent single fibers, and in which low-strength parts exist randomly in the cross-sectional direction, is cut in tension. Stretch cutting characterized in that when forming short fiber bundles, a pair of rollers and a guide are used on the supply side of the tension cutting area, and the multi-filament fibers are passed between the pair of rollers two or more times to be gripped and transferred. Method for producing fiber bundles.