JPH1150336A - Sewing yarn and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain sewing yarn comprising polyester monofilament having excellent seam fitting property and sewability and provide a method for producing the sewing yarn. SOLUTION: This sewing yarn comprises polyester monofilament having >=0.64 intrinsic viscosity, <=20% flatness ratio Fr and >=10 and <=19 bending hardness index Bhi. In the polyester monofilament, the diameter is preferably 0.06 mm to 2.0 mm and the tensile strength is >=35 mN/d and <=88 mN/d and the dry heat shrinkage factor at 180 deg.C is <=18%. This method for producing the sewing yarn comprises melt-extruding a polyester or a mixture of the polyester with other thermoplastic polymer from a nozzle, leading the extruded linear melt to a coagulating bath kept at >=50 deg.C and <=90 deg.C within 2.0 sec. and quenching the linear material and carrying out first stage drawing of the resultant undrawn yarn at >=65 deg.C and <=120 deg.C and carrying out second stage drawing of the drawn yarn at a temperature higher than a temperature in the first stage drawing and <=260 deg.C and carrying out third stage drawing of the yarn at a temperature higher than a temperature in the second stage drawing and <=260 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewing thread made of polyester monofilament which is excellent in seam fit and is suitable for various sewing applications, and a method for efficiently producing the sewing thread.

[0002]

2. Description of the Related Art Polyester monofilaments are widely used not only for clothing but also for various industrial materials because of their excellent chemical and mechanical properties, especially excellent dimensional stability.

[0003] However, polyester monofilaments are used only as spun yarns and multifilaments as polyester sewing yarns because they are inferior in fit of seams when applied to sewing threads due to their rigidity and the like. However, in the case of a sewing thread composed of a polyester twisted yarn, there is a drawback that poor unwinding due to twisting and twist cracks are liable to occur, and in the case of a sewing thread composed of a polyester multifilament entangled thread, a so-called Velcro having a protruding loop is used. There was a problem that unwinding was also poor due to the phenomenon.

As a solution to these problems, there is a method of forming a non-twist structure and cutting a protruding loop (Japanese Patent Laid-Open No. 51-1369).
No. 47, Japanese Patent Application Laid-Open No. Sho 61-289150, and Japanese Patent Application Laid-Open No. 2-293
No. 429) has been proposed, but these methods cannot sufficiently cope with the cost because the manufacturing process is complicated.

On the other hand, a nylon sewing thread has been proposed as a sewing thread made of a monofilament which has a simple manufacturing process and is economically advantageous in view of its flexibility (Japanese Patent Laid-Open Publication No. Hei 5 (1993) -205).
300803). However, although this sewing thread made of nylon monofilament is excellent in seam fitting at the time of sewing, it has a disadvantage that it is inferior in environmental resistance due to yellowing deterioration peculiar to nylon material, and furthermore, there is a change in outside air humidity during use. Due to the change in the moisture absorption characteristic of the nylon material, only the portion becomes harder due to the tightening of the seam at the time of drying, and the seam is loosened at the time of high humidity.

[0006]

SUMMARY OF THE INVENTION The present invention has been achieved as a result of studying to solve the problems in the prior art described above.

Accordingly, an object of the present invention is to provide a sewing thread made of polyester monofilament which is excellent in seam fit and is suitable for various sewing applications, and a method for efficiently producing the sewing thread.

[0008]

Means for Solving the Problems To achieve the above object, the present inventor has proposed polyethylene terephthalate (hereinafter referred to as P
Abbreviated as ET. ) As a result of evaluating various properties of the monofilament, the monofilament has a specific intrinsic viscosity, a specific flatness, and a favorable seam fit as a sewing thread when the bending hardness is within a specific range. And arrived at the present invention.

That is, the sewing thread of the present invention comprises a polyester monofilament having an intrinsic viscosity of 0.6 or more,
The flattening factor Fr defined in the text is 20% or less, and the flexural hardness index Bhi defined in the text is 10 or more and 19 or less.

The polyester monofilament constituting the sewing thread of the present invention comprises PET containing ethylene terephthalate units in an amount of 85% by weight or more and PET containing ethylene terephthalate units in an amount of 85% by weight or more.
Above and 85% by weight of tetramethylene terephthalate unit
Polybutylene terephthalate (hereinafter referred to as PBT)
Abbreviated. A) 60% by weight or less of a mixture or PET containing 85% by weight or more of ethylene terephthalate units
It is more preferable to be made of a mixture of 50% by weight or more and a thermoplastic elastomer having a JIS-A hardness of 60 or more and 50% by weight or less, since the above-mentioned properties are easily obtained.

Further, the sewing thread according to the present invention has a polyester monofilament constituting the sewing thread having a diameter of 0.06 m.
m to 2.0 mm, tensile strength 35 m
It is preferable from a practical point of view that the N / d is not less than 88 mN / d and the dry heat shrinkage at 180 ° C. is not more than 18%.

In the method for producing a sewing thread according to the present invention having the above-mentioned respective properties, the polyester is melt-extruded from a nozzle, and then rapidly cooled by being introduced into a coagulation bath at 50 ° C. to 90 ° C. within 2.0 seconds. It is characterized in that it is stretched in three stages, and then an oil agent is applied to the stretched monofilament and wound up.

[0013] Then, in this method of manufacturing a sewing thread,
The above-mentioned three-stage stretching is performed at a temperature of 65 ° C or more and 120 ° C or less, a first-stage stretching at a magnification of 2.0 times or more and 3.5 times or less, at a temperature higher than the first-stage stretching and 260 ° C or less, Second stage stretching at a stage stretching ratio or more and a first stage stretching ratio or less, at a temperature higher than the second stage stretching and at a temperature of 260 ° C. or less, a ratio at which the total stretching ratio becomes 5.0 times or more and 7.3 times or less. It is preferred to carry out by the third stage stretching.

The flattening factor Fr in the present invention is a numerical value obtained by the following equation (1). Fr = (L−1) × 100 / φ (1) Here, in the formula (1), L is the major axis of the monofilament, and 1 is the minor axis. Further, φ is the average diameter of the monofilament obtained from the arithmetic average of the major axis and the minor axis.

The flexural hardness index Bhi referred to in the present invention is a numerical value obtained by the following equation (2).
Is the bending hardness of the yarn, specifically, as shown in FIG.
The maximum bending force (unit) when the sample is bent by pulling up the center of the sample passed over two pins (steel wire of 2 mmφ each) set in cm with a J-shaped hook (steel wire of 1 mmφ) : MN). Φ in the equation (2) is the average diameter (mm) of the yarn.

[0016]

(Equation 1)

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

PET used as a polymer component of the polyester monofilament constituting the sewing thread of the present invention
Is substantially obtained by polycondensation of terephthalic acid and ethylene glycol, but a part of the acid component and a part of the glycol component are replaced with various dicarboxylic acids and glycols well known in the art. It may be something. Here, examples of the acid component include 2,6-naphthalenedicarboxylic acid, isophthalic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, dimer acid, and isophthalic acid substituted with a sulfonic acid metal salt. Examples of the glycol component include propylene glycol, tetramethylene glycol, diethylene glycol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, and polyalkylene glycol.

The PBT used in the present invention is substantially obtained by polycondensation of terephthalic acid and 1,4-butanediol, and a part of the acid component and a part of the glycol component are used in the art. May be replaced with various dicarboxylic acids and glycols well known in the above. Specific examples of these other components include the acid component and glycol component shown in the above PET.

The intrinsic viscosity of PET and PBT is usually 0.6 or more, but it is preferably 0.7 or more for PET, and especially 0.8 or more for PBT. It is preferable because a sewing thread can be obtained. From this point, the higher the intrinsic viscosity, the better,
If it exceeds 1.5, spinning becomes difficult, which is not preferable.

Here, the intrinsic viscosity referred to in the present invention is an intrinsic viscosity obtained from a viscosity measured at 25 ° C. in an orthochlorophenol solution, and is a value represented by [η].

The intrinsic viscosity of a monofilament composed of a mixture with an elastomer was determined from the viscosity of an orthochlorophenol solution obtained by filtering an undissolved suspended substance obtained by dissolving the monofilament in orthochlorophenol at 25 ° C. Intrinsic viscosity.

The elastomer which is another thermoplastic polymer component used in the present invention is defined as having a JIS-A hardness of 6
Zero or more thermoplastic elastomers. Specific examples of these thermoplastic elastomers include polyester, polyamide, polyolefin, polystyrene, polyurethane and 1,2-polybutadiene elastomers.

The polymer constituting the monofilament includes various inorganic particles such as titanium oxide, silicon oxide, calcium carbonate, silicon nitride, clay, talc, kaolin, zirconate, crosslinked polymer particles, various metal particles, and the like. In addition to the above-mentioned particles, conventionally known antioxidants, sequestering agents, ion exchangers, anti-coloring agents, light-proofing agents, flame retardants, various coloring agents, antistatic agents, waxes, silicone oils, various surfactants , Various reinforcing fibers and various plasticizers may be added.

The polyester monofilament constituting the sewing thread of the present invention has a flatness Fr of 20% or less, preferably 10% or less, and a flexural hardness index Bhi of 10 or more and 19 or less, preferably 13 or more 1
It is a polyester monofilament in the range of 7.0 or less.

If the flatness ratio Fr exceeds 20%, the thread passing property of the sewing needle hole is deteriorated at the time of sewing, the thread is broken, the seam is cracked even if the thread is not broken, and the seam becomes uneven. It is not preferable because the seam fit is poor. On the other hand, if the flexural hardness index Bhi exceeds 19, the seam rises and the seam portion becomes rigid, resulting in poor seam fit. Therefore, the lower the flexural hardness index Bhi, the better the seam fit, but the higher the flexural hardness index Bhi.
If the ratio is less than 10, it is not preferable because the seam is too soft and the seam is inferior in fixability, so that a stitch having a stable shape cannot be obtained.

The sewing thread of the present invention composed of PET monofilament has sufficient properties required for the sewing thread. However, PET monofilaments have a flexural hardness index Bhi of only about 16 or more even by the method of the present invention due to the rigidity of the material.
Accordingly, a more preferable polyester monofilament for a sewing thread is a mixture of PET and a thermoplastic polymer which is more flexible than PET.

PET and PET constituting the sewing thread of the present invention
The monofilament composed of a mixture with a more flexible thermoplastic polymer is composed of a mixture of 40% by weight or more of PET and 60% by weight or less of PBT, or a mixture of 50% by weight or more of PET and 50% by weight or less of a thermoplastic elastomer, and more preferably. 60% by weight or more of PET and PBT
It is a mixture of 40% by weight or less, or a mixture of 70% by weight or more of PET and 30% by weight or less of a thermoplastic elastomer.

When the mixing ratio of PBT or thermoplastic elastomer exceeds the above range, the flexural hardness index Bhi
Is not more than 10, and not only a seam having a stable shape cannot be obtained, but also a stretch-back property peculiar to PBT and an elastomer is developed, so that the seam is easily cracked and the seam fitting property is unfavorably impaired.

When the polyester monofilament is made of a mixture of PET and PBT, the bending hardness index Bhi of the polyester monofilament can be in the range of 13 to 19, and the polyester monofilament is made of a mixture of PET and elastomer. In this case, the bending hardness index Bhi of the polyester monofilament can be in the range of 10 or more and 17 or less.

The diameter of the polyester monofilament constituting the sewing thread of the present invention is from 0.06 mm to 2.0 m.
m, preferably in the range of 0.10 mm to 1.00 mm. If the diameter of the polyester monofilament is less than 0.06 mm, the absolute strength is low, and the yarn tends to be broken by an extremely small impact. On the other hand, when the diameter of the polyester monofilament exceeds 2.0 mm,
Even if the flatness ratio Fr and the flexural hardness index Bhi are within the ranges of the above values, the seam tends to rise when sewing is performed, and the seam fit tends to be poor. This is considered to be due to the fact that the absolute bending hardness of the monofilament becomes harder as the diameter of the monofilament increases.

The method for producing the polyester monofilament of the present invention having the above properties is as follows. The undrawn yarn cooled and solidified at the time of melt spinning is measured for the outer diameter with a magnifying mirror equipped with a gauge, and the desired yarn thickness is measured. The method of adjusting the discharge amount and the like in order to obtain the undrawn yarn and drawing the obtained undrawn yarn in three stages is the main point. The cooling method and the drawing method will be described below.

First, the PET of the present invention or a mixture of pre-mixed PET and another thermoplastic polymer is melt-extruded from a nozzle by a conventional method. Next, the extruded filament melt is heated to 50 ° C. or more and 90 ° C. within 2 seconds after extrusion.
Thereafter, preferably, the mixture is quenched in a coagulation bath at 60 ° C. to 80 ° C. within 1.5 seconds.

If the filament melt is not introduced into the coagulation bath within 2.0 seconds, even if the coagulation bath temperature is in the above range, undrawn yarn is liable to break during drawing, which is not preferable. Although the reason for this is not clear, it is considered that the filament is gradually cooled by air before entry into the coagulation bath, and undrawn crystallization proceeds.

On the other hand, if the coagulation bath temperature is lower than 50 ° C., it is not preferable because the filaments meander in the coagulation bath and tend to deteriorate the yarn shape. On the other hand, if the coagulation bath temperature exceeds 90 ° C., the roundness of the filaments is impaired, and the cross-sectional shape intended by the present invention tends to be difficult to obtain, which is not preferable. The reason for this is not clear, but the coagulation bath temperature is 50
If the temperature is lower than 0 ° C., it is considered that the filamentous melt solidifies into a glassy state and cannot absorb the resistance of the guide in the coagulation bath and meanders. When the temperature of the coagulation bath exceeds 90 ° C., the filaments become too flexible and easily deformed due to contact resistance with a guide or the like in the coagulation bath, and it is considered that the roundness is impaired.

The preferable cooling time in this cooling method depends on the thickness of the monofilament, but the filament is passed through the coagulation bath immediately after the nozzle for 2.0 seconds to 30 seconds.

The refrigerant used in the coagulation bath used herein is a substance that can be easily removed from the surface of the filamentous material and does not physically or chemically change the polymer. There is no particular limitation as long as the liquid can be maintained in the bath temperature range, and specific examples thereof include water, paraffin, ethylene glycol, glycerin, amyl alcohol, and xylene.

The undrawn yarn thus obtained is desirably subsequently drawn mildly in three steps so as to obtain an appropriate flexibility for a sewing thread.

The first-stage stretching is carried out at a relatively low temperature and a low magnification, that is, in a hot water bath at 65 ° C. to 120 ° C., particularly 85 ° C. to 95 ° C., 2.0 to 3.5 times, especially 2. 5 to 3 times.
Twice the conditions are employed. If the first-stage stretching temperature is too low, the yarn is liable to be broken at the time of stretching, while if it is too high, the stretching tension is remarkably reduced and stretching becomes difficult.

On the other hand, if the draw ratio of the first step is too small, unevenness of drawing occurs, and a uniform polyester monofilament cannot be obtained. Conversely, if it is too high, it becomes a rigid polyester monofilament, which impairs the seam fitting property, which is not preferable.

The second-stage stretching is set at a higher temperature than the first-stage stretching, and is performed at a temperature of 260 ° C. or less, particularly more than 120 ° C. and 200 ° C.
Under the following temperature, the stretching is performed in a range from the third-stage stretching ratio to the first-stage stretching ratio. As in the case of the first-stage drawing, if the second-stage drawing temperature is too low, the yarn is likely to be broken, and furthermore, a rigid polyester monofilament is not preferable. Conversely, if it is too high, the stretchability is improved, but it is not preferable because it is easily blown during stretching.

On the other hand, if the second-stage stretching ratio is too smaller than the third-stage stretching ratio, the subsequent third-stage stretching ratio becomes relatively large, and a flexible polyester monofilament cannot be obtained. It is not preferred because it inhibits the properties. On the other hand, if it is too large than the first stage stretching ratio,
Not only the thread tends to break easily, but also a rigid polyester monofilament even if the thread does not break, which is not preferable because it also impairs the seam fitting property.

The subsequent third-stage stretching is performed at a temperature higher than that of the second-stage stretching, and at a temperature of 260 ° C. or less, and particularly at a temperature of more than 180 ° C. and 250 ° C. or less, the total stretching ratio is 5.0 times or more.
7.3 times, especially in the range of 5.5 times to 6.8 times.
As in the case of the second-stage stretching, if the third-stage stretching temperature is too low, the yarn is likely to be broken, and furthermore, a rigid polyester monofilament is not preferable. Conversely, if it is too high, the stretchability is improved, but it is not preferable because it is easily blown during stretching.

On the other hand, if the third-stage draw ratio is too small, a polyester monofilament having sufficient strength cannot be obtained. Conversely, if the third-stage draw ratio is too high, not only the drawing becomes difficult due to the yarn breakage, but also the yarn breakage does not occur. It is not preferable because it becomes a rigid polyester monofilament and impairs the seam fitting property.

As described above, the polyester monofilament stretched in three steps can be heat-treated in order to further improve the dimensional stability. However, severe heat treatment which hinders the preferable characteristics as the above-mentioned polyester monofilament for sewing thread is required. Must be avoided.

The heating medium suitable for the second and third stretching and heat treatment can be easily removed from the surface of the monofilament. Any substance can be used as long as the substance is not given. Further, as the heating device, for example, a liquid bath having a high boiling point inert liquid, an air furnace, an inert gas furnace, an infrared furnace, a high-frequency furnace, a metal furnace, and the like can be used.

Subsequently, the obtained polyester monofilament is provided with an oil agent so as to obtain an antistatic property and an appropriate sliding property in order to improve the sewability for sewing thread. As a method for applying the oil agent, any known roller method or the like may be used, but a guide oiling system is preferable from the viewpoint of uniformity of oil agent adhesion.

The type of oil agent is selected depending on the use of the sewing thread. In general, antistatic agents include alkyl phosphate oil agents, and slipperiness improvers include fluorine, silicone, and mineral oils. These combinations are more preferable.

Incidentally, the physical properties of the polyester monofilament constituting the sewing thread of the present invention obtained as described above are such that the tensile strength is 35 mN / d or more and 88 mN / d or less.
Further, it is desirable that the dry heat shrinkage at 180 ° C. be 18% or less. Furthermore, the tensile strength is 45 mN / d to 75 mN /
More preferably, d and the dry heat shrinkage at 180 ° C. are 12% or less.

When the tensile strength of the polyester monofilament is less than 35 mN / d, it is not practical because the thread is easily broken at the time of sewing and also easily broken. On the other hand, if the tensile strength of the monofilament exceeds 88 mN / d, the impact resistance is inferior, although the reason is not clear, and it causes not only trouble such as thread breakage in the sewing process, but also breaks easily and has a short life. This is not preferable because it tends to be on the other hand,
If the dry heat shrinkage exceeds 18%, seam clogging tends to occur due to heat treatment such as ironing of the sewn product, which is not preferable. Therefore, the lower the dry heat shrinkage ratio, the better, but if it is desired to obtain a low shrinkage polyester monofilament, the heat treatment becomes severe, and the polyester monofilament becomes rigid as described above. The preferred shrinkage factor for the polyester monofilament for sewing thread is 180
It is desirable that the dry heat shrinkage at 5 ° C. be in the range of 5% to 18%.

The thus obtained sewing thread of the present invention is composed of the simplest monofilament, is economically advantageous, has a low bending hardness, has an excellent seam fitting property, does not easily break, and is used as a sewing thread. It has the required characteristics in equilibrium.

Therefore, according to the present invention, in addition to the various excellent properties of PET such as toughness, elastic modulus, chemical resistance and light resistance, it can be suitably applied as a sewing thread. The value is extremely large.

[0053]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which, however, are not intended to limit the scope of the present invention.

The measurement and evaluation of each characteristic in the following examples were performed according to the following criteria.

(1) Flatness Fr and Yarn Diameter The yarn diameter and the like were measured from a cross-sectional photograph of the monofilament by an optical microscope, and were calculated by the above-mentioned equation (1).

(2) Flexural Hardness Index The flexural hardness was measured in accordance with the method of FIG. 1 described above, and was determined from the measured value according to the method of the above equation (2).

(3) Tensile strength JIS L1013 Tensile strength and elongation were measured by a standard test method (unit: mN / d).

(4) Dry heat shrinkage at 180 ° C. Measured according to JIS L1013 dry heat shrinkage B method.

(5) Sewing evaluation Using a Juki DLU5490M sewing machine, two polyester drape curtain fabrics were piled up, and the needle thread was 4000 revolutions / minute.
Sewing at a seam pitch of 3 mm and 2 m long sewing were repeated three times, and the number of thread breaks and the seam fit were evaluated. The seam fit was visually evaluated as ◎: excellent, ×: poor. In addition, the evaluation of the seam fitting property of the sample that could not be sewn for a length of 2 m due to thread breakage was not performed.

[Example 1] [η] PET of 0.97 (J155 manufactured by Mitsui Pet Co., Ltd.) was melted at 290 ° C. with an extruder by a conventional method, and was spun from a nozzle through a filtration layer in a spinning pack via a gear pump. The spun yarn was introduced into a warm water bath at 75 ° C. within 1 second and rapidly cooled. The obtained unstretched yarn was first-stage stretched 3.0 times in a warm water bath at 90 ° C.
The film is stretched in the second stage 1.7 times in a hot-air drying oven at 0 ° C., and then stretched in a third stage in a hot-air drying oven at 220 ° C. so that the total stretching ratio becomes 6.5 times. The polyester monofilament was manufactured by carrying out a constant-length setting at ℃. Next, a silicone oil agent TRN-190 (manufactured by Takemoto Yushi Co., Ltd.) was lubricated with a guide lubricator to produce a winding sewing thread.

Next, using the obtained sewing thread, sewing evaluation was performed by the above method.

Table 1 shows the manufacturing conditions of the obtained polyester monofilament, and Table 2 shows the characteristics of the sewing thread and the results of the sewing evaluation.
It was also described in.

[Example 2] [η]: 0.97
80 parts by weight of PET (J155 made by Mitsui Pet),
[Η]: 1.20 PBT (1200s, manufactured by Toray Industries, Inc.)
A sewing thread was produced in the same manner as in Example 1 except that the mixture was changed to 20 parts by weight. Table 1 shows the production conditions of the obtained polyester monofilament, and Table 2 shows the characteristics of the sewing thread and the results of the sewing evaluation.

[Example 3] [η]: 0.97
A sewing thread was manufactured in the same manner as in Example 1 except that the mixture was changed to a mixture of 90 parts by weight of PET (J155 manufactured by Mitsui Pet) and 10 parts by weight of a polyamide-based thermoplastic elastomer (Pebax, 4033SN manufactured by Toray Industries, Inc.). . Table 1 shows the production conditions of the obtained polyester monofilament, and Table 2 shows the characteristics of the sewing thread and the results of the sewing evaluation.

[Comparative Example 1] [η]: 0.97
And 30 parts by weight of PET (Mitsui Pet J155),
[Η] 1.20 PBT (1200s, manufactured by Toray Industries, Inc.) 7
A sewing thread was produced in the same manner as in Example 1 except that the mixture was changed to 0 parts by weight. Table 1 shows the production conditions of the obtained polyester monofilament, and Table 2 shows the characteristics of the sewing thread and the results of the sewing evaluation.

[Comparative Example 2] [η]: 0.97
A sewing thread was manufactured in the same manner as in Example 1 except that the mixture was changed to a mixture of 40 parts by weight of PET (J155 manufactured by Mitsui Pet) and 60 parts by weight of a polyamide-based thermoplastic elastomer (Pebax, 4033SN manufactured by Toray Industries, Inc.). . Table 1 shows the production conditions of the obtained polyester monofilament, and Table 2 shows the characteristics of the sewing thread and the results of the sewing evaluation.

[Comparative Examples 3-4, 7-8, 10, 14-1
5] A sewing thread was manufactured in the same manner as in Example 2, except that the manufacturing conditions of the polyester monofilament were changed as shown in Table 1. Table 2 shows the properties of the obtained polyester monofilament sewing thread and the results of sewing evaluation.

[Comparative Example 5] When the first-stage stretching temperature was changed to 65 ° C in Example 2, half of the yarn was broken, and the production of the sewing thread was stopped.

[Comparative Example 6] When the first-stage stretching temperature was changed to 130 ° C in Example 2, the necking phenomenon disappeared, the stretching tension was remarkably reduced, stretching was impossible, and a sewing thread could not be produced.

[Comparative Example 9] When the second-stage stretching temperature was changed to 265 ° C in Example 2, fusing was impossible and stretching was impossible, and a sewing thread could not be produced.

[Comparative Example 11] In Example 2, when the second-stage stretching ratio was changed to 3.1 times, all the yarns were cut, and the production of the sewing thread was stopped.

[Comparative Example 12] When the third-stage stretching temperature was changed to 170 ° C in Example 2, thread breaks sporadically occurred, and the production of the sewing thread was stopped.

[Comparative Example 13] In Example 2, when the third-stage stretching temperature was changed to 265 ° C, fusing occurred and stretching became impossible, and a sewing thread could not be produced.

Comparative Example 16 When heat setting was not performed in Example 2, a sewing thread having a dry heat shrinkage of 180 ° C. of 22% was obtained. Sewing with the obtained sewing thread, and then 18
When the ironing was performed at 0 ° C., the seam was pulled and the seam fit was poor.

[Comparative Example 17] In Example 2, when the application of the oil agent was omitted, thread breakage occurred frequently and sewing was defective.

[0076]

[Table 1]

[Table 2]

[0077]

As described above, the sewing thread made of the polyester monofilament of the present invention does not suffer from twist cracks and the velcro phenomenon, which are disadvantages of the sewing thread made of spun yarn and multifilament, and the manufacturing process is simple and economical. In addition, there is no yellowing deterioration and dimensional change unlike a nylon monofilament sewing thread, and it also has excellent seam fitting properties and sewability which could not be conventionally achieved with a polyester monofilament.

Further, according to the method for producing a sewing thread of the present invention, a sewing thread having the above-mentioned performance can be efficiently produced.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a method for measuring the bending hardness of a polyester monofilament constituting a sewing thread according to the present invention.

Claims (11)

[Claims] 1. A flatness F defined by a polyester monofilament having an intrinsic viscosity of 0.6 or more and defined in the text.
r is not more than 20% and flexural hardness index B defined in the text
A sewing thread wherein hi is 10 or more and 19 or less. 2. The sewing thread according to claim 1, wherein the polyester monofilament comprises polyethylene terephthalate containing at least 85% by weight of ethylene terephthalate units. 3. The sewing thread according to claim 2, wherein the bending hardness index Bhi defined in the text of the polyester monofilament is 16 or more and 19 or less. 4. A polyester monofilament comprising a mixture of at least 40% by weight of polyethylene terephthalate containing at least 85% by weight of ethylene terephthalate units and at most 60% by weight of polybutylene terephthalate containing at least 85% by weight of tetramethylene terephthalate units. The sewing thread according to claim 1, characterized in that: 5. The sewing thread according to claim 4, wherein the bending hardness index Bhi defined in the text of the polyester monofilament is 13 or more and 19 or less. 6. A polyester monofilament comprising at least 50% by weight of polyethylene terephthalate containing at least 85% by weight of ethylene terephthalate units and JIS-
2. The sewing thread according to claim 1, comprising a mixture of a thermoplastic elastomer having an A hardness of 60 or more and 50% by weight or less. 7. The sewing thread according to claim 6, wherein the bending hardness index Bhi defined in the text of the polyester monofilament is 10 or more and 17 or less. 8. The sewing thread according to claim 1, wherein the diameter of the polyester monofilament is in the range of 0.06 mm to 2.0 mm. 9. The polyester monofilament has a tensile strength of 35 mN / d or more and 88 mN / d or less and 180 mN / d or less.
The sewing thread according to any one of claims 1 to 8, wherein the dry heat shrinkage at ℃ is 18% or less. 10. A polyester or a mixture of a polyester and another thermoplastic polymer is melt-extruded from a nozzle, guided to a coagulation bath at 50 ° C. to 90 ° C. within 2.0 seconds, quenched, and then stretched in three steps. The method for producing a sewing thread comprising a polyester monofilament according to any one of claims 1 to 9, wherein an oil agent is applied to the stretched monofilament and then wound up. 11. The three-stage stretching is performed at a temperature of 65 ° C. or more and 120 ° C. or less, a first stage stretching at a magnification of 2.0 times or more and 3.5 times or less, and a temperature of a higher temperature than the first stage stretching and 260 ° C. or less. Below, the second-stage stretching at a third stage stretching ratio or more and the first stage stretching ratio or less, at a temperature higher than the second stage stretching and 260 ° C. or less, the total stretching ratio is 5.0 times or more and 7.3 times. The method for producing a sewing thread according to claim 10, wherein the third step of stretching is performed at the following magnification.