JPS6142013B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a processed yarn made of thermoplastic filament fibers, and relates to a specially processed yarn that is optimal for lock sewing.

(Prior Art) Various kinds of synthetic fiber yarns used for sewing have been known, and notable examples include yarns made of spun yarns and yarns subjected to false twisting and crimp processing.

However, the threads conventionally used for sewing are unsuitable for actual sewing, and have many disadvantages. For example, spun yarn inherently has uneven thickness, which causes large fluctuations in yarn strength, which tends to lead to thread breakage during sewing and poor quality of sewn products.
On the other hand, normal false-twisted crimped yarns are somehow more difficult to sew than spun yarns, and it is generally said that it is better for the yarns used for sewing to have fluff.

In view of the above points, the inventors of the present invention have conducted various studies and found that the most suitable thread for sewing is one that is actually easy to sew and gives a beautiful finished stitch, and in turn gives a beautiful finished product to the sewn product. In particular, with regard to ease of sewing, it has been found that the thread has extremely low torque and is converged at the same time, and has a fluffy or fluff-like protruding fiber structure. Fundamentally, as mentioned above, it is difficult to create such a yarn using spun yarn, and even using ordinary false-twisted crimped yarn is insufficient in terms of torque and the structure of the protruding fibers, so it is generally extremely difficult to realize this type of yarn. It is. In particular, according to the findings of the present inventors, the torque possessed by ordinary false-twisted crimped yarn is completely unnecessary and causes inconvenience for sewing, and in some cases, The shrinkage characteristics and structure itself are meaningless and unnecessary for sewing.

(Problems to be Solved by the Invention) The present invention uses thermoplastic fiber multifilament yarn and utilizes false twisting as the basic mechanical fiber processing method, which cannot be obtained with conventional technology. The aim is to provide a thread that is extremely suitable for sewing that would otherwise be impossible.

(Means for Solving the Problems) The thread of the present invention, which is most suitable for sewing, has the following structure.

That is, in a false twisted thermoplastic fiber multifilament yarn, the yarn is a substantially untwisted yarn and substantially all of the constituent filaments have the ability to twist in the same direction. Nevertheless, it is a special yarn characterized by having a threading ability of 4 times/50cm or less as defined below.

Here, "the yarn threading ability is 4 times/50cm or less" means that the yarn to be tested is hung as a single loop with a circumference of 1 m using the same thread (state 1), and then Apply a load W calculated as yarn denier x 2 grams = W (grams), and then apply the load W
(state 2), and the number of free static twists (applied This means that the number of rotations) is 4 or less.

As is clear from the constitutional requirement that substantially all of the constituent filaments of the yarn of the present invention having the above-mentioned structure have the ability to thread in the same direction,
The yarn of the present invention cannot be obtained through a process of aligning and integrating processed yarns having opposite twisting abilities; basically, the above-mentioned yarn of the present invention can be processed using a single false twisting weight. The monofilament produced by this method is made into a thread having characteristics suitable for sewing in the form of a monofilament. Of course, when used for actual sewing, the thread according to the present invention may be used as a single thread as it is, or may be used as a plurality of threads such as plying and twisting.

(Function) The thread that is most suitable for sewing according to the present invention will be explained in more detail below.

If there is torque in the thread used for sewing, when the thread passes through the cloth, the thread itself will form a twisted ball in the part of the thread before passing through, making it difficult to sew. Machine stitching especially increases skipped stitches and thread breakage caused by the tip of the knife. There are many defects, such as an increase in thread breakage due to thread entanglement with other sewing machine parts.

However, in the conventional technology, the following (1) ~
Various measures to reduce the torque as listed in item (5) have been taken as a general treatment method for false twisted yarn, but each of them has been used to reduce torque from a general industrial perspective and when used for sewing. There were also many negative aspects when viewed as a thread that could be used.

That is, (1) A yarn that appears to be a single yarn by aligning and intertwining S false-twisted yarn and Z false-twisted yarn in order to offset each other's torques. Although this yarn is excellent in that it can be made without any torque, it has the disadvantage that the manufacturing process is extremely complicated and the manufacturing cost is high.

(2) A yarn made by subjecting the false-twisted yarn to heat treatment again using dry heat or moist heat to reduce the torque.

In general, yarn processed using this method is well known, but there is a limit to how much torque can be naturally reduced in the conventional re-heat treatment described above, and within the range of conditions normally used, it is difficult to set the conditions. However, it was insufficient as a sewing thread. In other words, at the same time, the purpose was to maintain the strength of the yarn, the difficulty of stretching the yarn at low tension, and the crimp of the fibers, so high-temperature heat treatment and/or tension heat treatment after false twisting was unthinkable. Ta.

(3) Yarn made by additional twisting method (Japanese Patent Application Laid-Open No. 52-5348, etc.). With this method, it is possible to reduce the torque to zero under one apparent condition, for example, in a no-tension condition, but it is possible to
If tension is applied or the tension is further unwound, torque will develop, which is not preferable. This is because the torque characteristics of false twisting and actual twisting are different.

(4) In particular, when creating a double yarn structure, if the single yarn does not have torque, it is possible to obtain a satisfactory result by balancing the first and second twists.

Therefore, a good product can be obtained if the double yarn is made of apparently single yarn as described in item (1) above, but the process is complicated and the manufacturing process is more complicated than the negative aspects described in item (1) above. This will be costly.
The same applies to the case of a triplet structure or more, or a structure having first twist, middle twist, first twist, etc.

(5) It is also possible to use a plurality of yarns with false twisting torque to balance the false twisting torque, the first twist, and the second twist, but this method has the same disadvantages as described in item (3) above. be.

etc.

The present inventors successfully combined the processing conditions in the false twisting process and the heat treatment conditions in various heat treatment steps to create a false-twisted thermoplastic fiber multifilament yarn, in which the yarn is substantially Even though it is a non-twisted yarn and substantially all of the constituent filaments have a twisting ability in the same direction, the yarn's twisting ability as defined above is 4 times /
We succeeded in obtaining the yarn of the present invention, which has a length of 50 cm or less, which cannot be found in conventional examples.According to the knowledge of the present inventors, the yarn according to the present invention is different from any conventional yarn. It can be said that it is an extremely excellent thread for sewing when compared to the above, and it is a reasonable thread that does not cause a significant increase in cost or manufacturing process. The power is 4
Items exceeding 50cm per turn are hardly suitable for sewing.

In addition, the present invention has the idea of realizing a thread with extremely low threading ability as described above, and also the idea that the thread most suitable for sewing is a thread that is bundled and has protruding fibers. From this point of view, the formation mechanism of the protruding fiber structure adopts a unique technical idea of utilizing the crimp ability and twisting ability of the false-twisted fibers.

That is, in a preferred embodiment, the yarn suitable for sewing of the present invention is characterized in that it has a fiber portion that protrudes from the yarn axis, and furthermore, the yarn is characterized in that the constituent filaments are mutually connected. The yarn is characterized in that it has intertwined yarn portions and unentangled yarn portions alternately along the yarn axis direction, and furthermore, all of the yarns have substantially equal lengths. It is characterized in that the yarn is composed of filament fibers of polyester type.

Regarding the above-mentioned definition of "thread threading capacity is 4 times/50cm or less", this definition also applies to inconveniences during sewing, even in the sewing process where the sewing thread is subject to intermittent tension. This indicates that there is virtually no development of torque that would cause
Even if the threading ability is virtually zero in a state before the sewing process, for example, in a non-tension state, there will be a significant It is of no use if the thread exhibits threading ability, and as is clear from the content of the definition, this definition specifies the threading ability in two states, before and after applying a considerable amount of tension to the thread. Therefore, it is a useful and strict definition when compared with the way it is used as a sewing thread, and this definition will be specifically explained below with reference to the drawings.

That is, the thread is made into a single ring with a circumference of 1 m, and is hung with the same thread as the thread (the model diagram is shown in Figure 1A. 1 is the sample thread that forms a single ring with a circumference of 1 m, and 2 is the sample thread that forms a single ring with a circumference of 1 m. This is the same thread as the sample thread used to hang the ring.)

Furthermore, a load W calculated as the denier of yarn x 2 grams = W (grams) is applied to the ring (a model diagram is shown in Figure 1B. 3 is the load of W, and this load is also (The thread 2' is the same as the sample thread.)

Subsequently, the load on the W is removed (a model diagram is shown in FIG. 1C).

In the test process as described above, "the yarn threading ability is 4 times/50cm or less" defined in the present invention refers to the untensioned state (Fig. 1A) and the untensioned state after load removal (Fig. 1C). ) means that the number of free static twists (the number of twists and turns) of the ring is 4 or less in both states.

Hereinafter, the method for manufacturing such a special yarn will be explained in detail. As an example of the manufacturing process, the yarn of the present invention is made by applying a false twist through a special false twisting process followed by a relaxation treatment. A protruding fiber portion is formed based on the crimping and winding ability of the fibers, and then a fluid entangling process is performed to separate the yarn portions in which the component filaments are intertwined and the yarn portions that are not intertwined in the yarn axis direction. In this process, a special heat treatment is applied in combination with this process, which creates a special relationship with the false twist heat fixing effect during the false twist process. It is obtained by performing heat treatment under the effect of heat treatment.

The characteristics of this manufacturing process are that the sewing is performed using an optimal thread, the formation mechanism of the protruding fibers is based on the crimp ability and twisting ability of the fibers imparted by the false twisting process, and the above-mentioned intermittent An interlacing process that achieves target entanglement imparts cohesiveness to the yarn, and at the same time binds and fixes it to the protruding fiber portions by the interlacing, and in this way, a large number of protruding fiber portions are firmly formed in the yarn. is subjected to a strong "post-heat treatment" which has a higher heat treatment effect than the false-twisting heat-setting effect, substantially reducing the effect of the aforementioned false-twisting, and in this way, the material is optimal for sewing as described above. The purpose is to use specially processed yarn. In such a manufacturing process, even before the false-twisting process, "pre-heat treatment" which has a higher heat treatment effect than the false-twisting heat-setting effect is applied, which can also result in the final loss of the false-twisting effect. It is effective in obtaining the thread of invention.

That is, as mentioned above, in some cases, the false twist crimp characteristics and structure itself are particularly meaningless and unnecessary for threads used for sewing.

To explain the above process in detail,
The thermoplastic fiber multifilament yarn is subjected to a false twisting process consisting of a twisting-heat-setting-untwisting process or a stretching false-twisting process, and then treated with a fluid jet entangling device that achieves an intermittent entangling action. The protruding fiber portions are mainly produced by relaxing the yarn after the false twisting or drawing false twisting, and conveniently, after taking off the false twisting process, the protruding fiber portion is fed to a fluid jet entangling device at a high overfeed. By creating a relaxed state on the upstream side,
The filament naturally forms a large number of protruding fiber portions due to its crimping and rolling ability, and the protruding fiber portions are bound and fixed by the subsequent intermittent entangling process, thereby forming a strong structure. Ru. Therefore, this protruding fiber part is
It is not formed as a cut end of the filament, but is formed as a part of a continuous filament, such as a snarl or a loop, and does not move around in the yarn due to the above-mentioned intermittent entanglement. It will be fixed like this. The shape of the protruding fiber portion is
It may have one type of shape such as an arcuate shape, an annular shape, or a twisted shape, or it may have a mixed shape of multiple types thereof.

As is clear from the formation mechanism of such protruding fiber portions, although the yarn of the present invention has protruding fiber portions, all of the constituent filament fibers are essentially of the same length; By doing so, in addition to the effect of intermittent entanglement, it is possible to almost eliminate the aforementioned protruding fiber portions from sliding due to external forces such as squeezing action, thereby preventing the occurrence of neps, etc. Moreover, the strength of the filament used as a yarn is extremely high. On the other hand, for example, a yarn in which the constituent single yarn is formed of two multifilament yarns, one of which is overfeed, and the protruding fiber portion is formed by the fibers on the overfeed side, the protruding fibers are The parts tend to move around and become neps, and the intensive utilization of the constituent filaments is of course low, which is completely undesirable.

The yarn suitable for sewing, which is preferably formed from polyester filament fiber of the present invention, is as follows:
Even if the test (applying tension of 1 g/D - removing the tension) was repeated 10 times, the elongation rate with respect to the fiber length before the test was extremely small at 2% or less, which was due to the protruding fibers. This confirms that the portion is firmly bound and fixed in the thread, and also confirms that the fiber itself has been processed to prevent plastic deformation. The fact that the elongation rate of the thread with respect to tension is small and the thread is extremely stable in terms of dimensions improves the sewability and the beauty of sewn products.

The ability to crimp and twist the filament forming the protruding fiber portion as described above depends on the conditions of false twisting, but is largely influenced by the number of false twists. If the number of false twists is small, the crimp form becomes large and large protruding fiber parts can be formed, but the crimp development ability and
The twisting ability is weakened, and if the number of false twists is even smaller, it becomes almost impossible to form protruding fiber portions. On the other hand, if the number of false twists is large, the ability to develop crimps is strengthened, but the crimp form becomes finer, the protruding fibers are formed finely, and it becomes impossible to form any protruding fibers at all. The number of false twists applied in the production of fibers generally falls within a range in which it is not possible to form portions that can be called protruding fibers. Therefore, the number of false twists is preferably set slightly lower than the number of false twists used in the production of ordinary woolly textured yarns.

According to the findings of the present inventors, the range of the number of false twists T (twice/m) that preferably forms the protruding fiber portion is as follows: where D is the denier number of the thermoplastic fiber multifilament yarn to be false twisted, and ρ is the specific gravity of the fiber.

In addition, the relaxed state for revealing the protruding fiber portions is easily achieved by setting the relaxation rate to the fluid jet entangling device after taking off the false twisting process as described above, with a high overfeed. It seems best to set the range as follows: 4<{(V ₁ /V ₂ )-1}×100<20, where V ₁ is the take-up speed of false twisting, and V ₂ is the take-up speed of entangled processing. It's speed. After the false twisting process, when the zone in which the relaxed state is formed is divided by the fluid entanglement treatment zone and the take-up roller, the overfeed in the relaxed state zone should be 4% to 20% according to the above formula. Bye. Even when a relaxed state zone is formed in a process system other than these, it is basically preferable to configure the structure according to the range of the above-mentioned relaxation rate or overfeed rate.

In addition, in the above process, it is also possible to apply tension to the yarn by drafting it at an appropriate point such as before, during, or after fluid treatment after false twisting. The number, size, etc. of fiber parts can be adjusted. For example, when tension is applied once after false twisting and before relaxation, the number of protruding fiber portions formed can be larger and finer than when tension is not applied. In addition, if the yarn is subjected to a drafting action during or immediately after the fluid entanglement treatment, the weaker protruding fiber portions will disappear and the stronger ones will be selected and remain, especially those with high tensile strength. It can be used as a thread suitable for high-quality single-layer sewing.

According to the findings of the present inventors, a yarn in which 200 or more protruding fiber portions can be counted per meter of yarn is effective. The large number of protruding fiber portions reduce the coefficient of friction with metals and other substances such as sewing needles and guides, improving sewability, and ultimately giving the yarn of the present invention made of filaments the performance and appearance of a spun yarn. will be granted.

Through the above-mentioned process, the yarn has been strongly formed with protruding fiber parts that are highly effective during sewing, and is then subjected to a "post-heat treatment" to increase its strength, and is then subjected to a false twisting process, which is the previous process. The curling ability and crimp properties that have been applied are significantly reduced.

Such a strong post-heat treatment is the most important point in obtaining the yarn of the present invention, and it is necessary that the post-heat treatment has a strength that has a higher heat treatment effect than the heat-setting effect of at least the previous false-twisting step. Thus, for the first time, the most significant feature of the yarn according to the present invention is that even though substantially all of the constituent filaments have the ability to turn in the same direction, the yarn ability is less than 4 turns/50 cm. It is possible to obtain threads like this.

Therefore, the degree of the post-heat treatment is basically a temperature substantially higher than the false-twisting heat-setting temperature so as to have a higher heat-setting effect than the heat-setting effect of the false-twisting step, There is a large difference in the heat treatment effect depending on the mode of the post-heat treatment. In general, continuous heat treatment, in which the thread is heat-treated while running, has a lower heat treatment effect than batch heat treatment, in which the yarn is heat-treated for a long time while the yarn is wound, etc., and to obtain the same effect as batch heat treatment with continuous heat treatment, the batch heat treatment temperature value is It is necessary to take into account a difference of 30°C, and since dry heat treatment has a lower heat treatment effect than wet heat treatment, it is necessary to take into account a difference of about 45°C.

Based on the findings of the present inventors,
In order to obtain a yarn having the above-mentioned characteristics of the present invention, after the false twisting process, the temperature must be 35°C higher than the temperature of the false twisting process.
As mentioned above, it is important to perform the tension heat treatment at a temperature that is more preferably 40°C or higher.

In this way, the above-mentioned post-heat treatment can be carried out using dry heat or wet heat, and as a continuous treatment or a batch treatment, and by considering and setting these conditions appropriately, it is possible to achieve a yarn threading capacity of 4 times/50 cm or less. can be taken as a thing. If the post-heat treatment is not performed using moist heat, it may of course be performed at the same time as the dyeing process.

In the present invention, any type of fiber may be used as long as thermoplastic fibers are used, but in general, polyester fibers, which are highly effective in heat treatment, are used in the present invention which is subjected to special heat treatment as described above. It can be said that it is suitable for sewing threads, and it is generally possible to obtain threads with good properties such as relatively little elongation compared to other materials.

When trying to obtain the yarn of the present invention using a polyester multifilament yarn, according to the knowledge of the present inventors, when the post-heat treatment is continuous dry heat treatment, the post-heat treatment is a tension heat treatment, and after the As mentioned above, the heat treatment temperature is set to be higher than the false twisting temperature by 35°C or more, more preferably by 40°C or more.
It seems that the temperature should be 210℃ or higher. It is sufficient that the false-twisting temperature is at least about 150° C. or higher, and an appropriate value is set in combination with the post-heat treatment temperature. In general, the larger the difference between the post heat treatment temperature and the false twisting temperature, the more effective it is.

In addition to the post-heat treatment method described above, it is also effective to perform a "pre-heat treatment" before false twisting in order to obtain a yarn having the above-mentioned characteristics of the present invention. In the case of continuous dry heat treatment, the temperature of this preheat treatment is 20° higher than the false twisting temperature.
It is preferable to set the temperature higher than ℃ and 210℃ or higher. In this case too, the false twisting temperature is at least 150℃
It is better to set it to the above.

According to the findings of the present inventors as described above, in order to obtain a yarn having the above-described characteristics of the present invention by such pre-heat treatment before false twisting, It is important to perform the heat treatment at a temperature much higher than the twisting temperature, as a tension heat treatment, with an overfeed within a range smaller than the heat shrinkage rate of the yarn.

This kind of pre-heat treatment has the effect of stabilizing the thermal properties of the yarn, such as its strength, resistance to elongation, and heat shrinkage rate.
The effects of false twisting (crimping and torque), which are performed at a lower temperature than the pre-heat treatment, are made temporary (by going through the pre-heat treatment, the effects of the false-twisting process are further reduced in the post-heat treatment). It has the effect of making it easier to lose the heat, and when a post heat treatment is performed in addition to the pre-heat treatment, it also has the effect of making it possible to effectively turn the post-heat treatment into a relaxation heat treatment.Therefore, the post-heat treatment Even if the thread is subjected to bulk heat treatment using a wound body or the like, the strength and resistance to elongation of the thread can generally be maintained.

When attempting to obtain the yarn of the present invention using polyester fibers other than polyester fibers, such as polyamide multifilament yarns, the above-mentioned "post-heat treatment" and "pre-heat treatment" conditions may vary depending on the thermal properties (crystallization) of the fiber. The temperature may be changed as appropriate depending on the starting temperature, the temperature at which fusion occurs, etc., but the temperature difference between each heat treatment generally has little to do with the type of fiber, and is almost the same as when using polyester fibers above. It is best to keep it at a similar level.

The above-mentioned thread of the present invention is actually a thread suitable for sewing in a substantially untwisted state and exhibits an effective effect.In particular, by forming intertwined portions intermittently, The yarn of the invention can easily have adequate cohesiveness. The untwisted state refers to a state in which the twist insertion is less than that normally applied by a draw-twisting machine, and specifically refers to a state in which the twist is inserted less than 25 times/m. According to the findings of the present inventors, it is preferable that the number of the intertwined portions is about 40 pieces/m or more, and that the length of the non-entangled thread portion is about 15 mm or less.

(Example) Hereinafter, the specific structure and effects of the thread suitable for sewing of the present invention will be explained with reference to Examples.

Example 1 A multifilament drawn yarn of polyethylene terephthalate fiber (200 denier, 72 filaments) was subjected to false twisting at 180°C and 1400 T/m, and then entangled with a fluid jet intermittent entangling device while being relaxed by 13.6%. A heat set at 220° C. was then carried out under 6% underfeed. The denier of the yarn thus obtained was 222 denier.

The yarn thus obtained has a high rolling ability (see above 2).
The number of free static twists depending on the configuration is 1.1 in state 1.
The number of times/50cm was 2.4 times/50cm in state 2, and the fiber portion had many protruding fibers. When this thread was used for sewing, it was found to be excellent.

Example 2 Following the drawing process in which the supplied yarn used in Example 1 was produced, heat treatment (dry heat) at 230°C was performed while giving an overfeed of 0.6%, and the 200 denier yarn thus obtained was , 72 filament polyethylene terephthalate fiber multifilament yarn was subsequently subjected to false twisting at 170°C and 1500 T/m, and then, while being relaxed by 13.6%, it was entangled using a fluid jet intermittent entangling device and wound.

Further, the yarn was heat-treated in a wound state in water at 130° C. (cheese dyeing machine) for 40 minutes. The denier of the yarn thus obtained was 224 denier.

The threading ability of the yarn thus obtained is state 1
In state 2, it was 0.8 times/50cm, and in state 2, it was 1.0 times/50cm, and when it was used for sewing, it was extremely good.

Comparative Example 1 A yarn was produced in Example 1 except that only the false twisting temperature was changed to 210°C. When we investigated the yarn's threading ability, it was found that it could be threaded 24 times/50cm under no load (condition 1).
(The false twisting direction was S. The winding direction was S). The power in state 2 is 31
It was hot at times/50cm. This thread was unsuitable for sewing because of its high torque.

Comparative Example 2 The yarn obtained in Comparative Example 1 above was subjected to 70 times/m in the S direction.
(The twisting method was to suspend one thread without any load and allow it to twist freely until it stopped).

When we investigated the twisting ability of the twisted yarn obtained in this way, we found that it was 0 times/50cm in the unloaded state (state 1) and 18 times/50cm (in the S direction) after the load was removed (state 2).
The free static twist number of From this result, it was confirmed that this thread is undesirable because it develops torque once tension is applied during the actual sewing process.

Comparative Example 3 Processing was carried out according to the processing conditions described in Japanese Patent Application No. 54-41571 previously proposed by the present inventors.

That is, multifilament drawn yarn (70 denier, 24 filaments) of polyethylene terephthalate fiber was subjected to false twisting at 190°C and 1500 T/m, and then entangled with a fluid jet intermittent entangling device while being relaxed by 14%. A heat set of 220°C was carried out under 2% underfeed.

The yarn thus obtained has a denier of 79 denier, and the threading ability of the yarn is 3.5 in condition 1.
It was determined that it was a fairly good sewing thread as far as it could be seen in this condition.

However, when this thread was used for sewing, it was clear that it had better properties than conventional sewing threads, but although it did not occur frequently, it did cause beads to form during the sewing process. Seam skipping and sewing thread breakage may occur, and when viewed as a sewing thread, it is clearly inferior in actual industrial use compared to the thread of the present invention.

When we investigated the cause of this problem, we found that during sewing, the thread is subjected to tension many times from the time it is unwound from the thread body until the seam is actually formed. was also found to be increasing.

Based on this knowledge, the application ability in state 2 defined by the present invention was measured and was found to be 6.1 times/50cm.

The reason why this thread has such latent torque and is insufficient as a sewing thread is because the difference between the temperature conditions for false twisting and the heat set temperature conditions after false twisting is small. It was hot.

(Effects of the Invention) As described above, the yarn according to the present invention is produced using a mechanical fiber processing method called false twisting, which is the most rational and common processing process with high productivity. Compared to any known thread, it is an excellent thread that effectively exhibits excellent characteristics as a sewing thread.

[Brief explanation of the drawing]

FIGS. 1A, B, and C are model diagrams each illustrating a method for measuring yarn threadability as defined in the present invention. 1: A sample thread forming a single ring with a circumference of 1 m, 2: The same thread as the sample thread used to hang a ring made of sample thread, 2': The same thread as the sample thread used to hang a load of W, 3 : W load.

Claims (1)

[Claims] 1. A false twisted thermoplastic fiber multifilament yarn, which is a substantially non-twisted yarn, and substantially all of the constituent filaments have the ability to twist in the same direction. A thread suitable for sewing, characterized in that the thread has a threading capacity of 4 times/50cm or less as defined below, despite the fact that the thread is Here, "the yarn threading ability is 4 times/50cm or less" means that the yarn to be tested is hung as a single loop with a circumference of 1 m using the same thread (state 1), and then Apply a load W calculated as yarn denier x 2 grams = W (grams), and then apply the load W
(state 2), and the number of free static twists (applied This means that the number of rotations) is 4 or less. 2. A thread suitable for sewing according to claim 1, characterized in that the thread has a fiber portion protruding from the thread axis. 3. Claim 1 or claim 3, wherein the yarn alternately has yarn portions in which constituent filament fibers are intertwined with each other and yarn portions in which they are not intertwined along the yarn axis direction. Thread suitable for sewing as described in item 2. 4. A thread suitable for sewing according to claim 1, 2 or 3, characterized in that the thread is entirely composed of filament fibers of substantially equal length. 5. A thread suitable for sewing according to claim 1, 2, 3, or 4, characterized in that the thread is made of polyester filament fiber.