JP3329406B2 - Polyester filament mixed yarn and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester filament-mixed yarn and a method for producing the same, and more particularly, to a polyester filament-mixed yarn and a false twisting machine which are preferably used for clothing having soft surface touch and bulkiness. The present invention relates to a production method that does not easily cause a defect of a cheese package during winding.

[0002]

2. Description of the Related Art Polyester multifilaments are widely used for clothing and the like because of their excellent mechanical properties and ease of texturing. In order to obtain a soft texture with the progress of technology, many attempts have been made to reduce single fiber denier. On the other hand, different shrink mixed yarns are well known as a method of giving a bulky feeling, and different shrink mixed yarns using polyester multifilaments having ultrafine single fiber denier as low shrink component yarns have also been proposed.

[0003] However, in the above-mentioned hetero-shrink mixed yarn using polyester multifilament having ultra-fine single fiber denier, individual filaments of ultra-fine single fiber denier yarn, which is a low-shrink component yarn, are almost aligned in parallel. It is blended as it is and shows a difference in yarn length between high and low shrinkage component yarns during dyeing, but there is little difference in yarn length between ultrafine single fiber denier filaments, and the softness of ultrafine single fiber denier It did not take full advantage of the natural surface touch.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a polyester multifilament having an ultrafine monofilament denier in which individual filaments have crimps, In the state that it is not arranged in parallel, it is included in the mixed fiber as a low shrinkage component yarn, and due to the different shrinkage effect, after dyeing, individual ultrafine single fiber denier filaments emerge without being aligned on the mixed yarn surface It is intended to bring out delicate soft touch. In addition, crimping the ultra-fine single fiber denier filament, and the production process of blending, while making it a reasonable one step by a false twisting machine, specific false twisting conditions, by making the fluid entanglement processing conditions An object of the present invention is to provide a manufacturing method that does not easily cause drawbacks such as twilling and ear breaks in a cheese package wound by a false twisting machine.

[0005]

The present invention employs the following means to solve the above-mentioned problems. That is, the present invention is a composite yarn that has been subjected to a tangling fluid entanglement process,
Polyester multifilament false twisted yarn A having a single fiber denier of 1.0 denier or less and a single fiber denier of 1.
A mixed yarn comprising at least two polyester multifilament yarns B having no false twist crimps of 0 denier or more, and satisfying the following formulas (1) to (5). Polyester filament mixed yarn. CC (A) ≧ 30 [%] (1) SHW (A) ≦ 7.0 [%] (2) SHW (B) ≧ 7.0 [%] (3) SHW (B) −SHW (A) ≧ 5.0 [%] (4) Di ≧ 50 [ke / m] (5) However, CC (A) is the crimp elongation rate (%) of polyester multifilament false twisted yarn A, and SHW (A) is The boiling water shrinkage (%) of the polyester multifilament false twisted yarn A, SHW (B) is the boiling water shrinkage (%) of the polyester multifilament B, and Di is the degree of confounding (ke / m) of the polyester filament mixed fiber. is there.

The present invention also relates to a polyester multifilament false twisted yarn A having a single fiber denier of 1.0 denier or less obtained by false twisting or stretch false twisting. Subsequently, a method for producing a mixed yarn in which a single fiber denier is subjected to fluid entanglement treatment by aligning with a polyester multifilament yarn B having no false twist crimp of 1.0 denier or more and comprising the following formulas (6) to (8) Is a method for producing a polyester multifilament mixed yarn. K (A) ≧ 18000 (6) HI (A) ≧ 160 [° C.] (7) OF ₂ ≧ 2.5 [%] (8) However, K (A) is used for false twisting or stretch false twisting. HI (A) indicates the heat setting temperature [° C.] during false twisting or stretch false twisting, and OF ₂ indicates the overfeed rate [%] during fluid entanglement.

Hereinafter, the present invention will be described in detail. The polyester referred to in the present invention means a polymer having an ester bond, and mechanical properties, hydrophobicity, and the like that can be used for clothing and the like.
As long as it has a dyeing property for dyes such as disperse dyes and cationic dyes, any dyes are possible, but polyethylene terephthalate, polybutylene terephthalate, copolymerized isophthalic acid component polyester and 5-metal sulfoisophthalic acid component are copolymerized. The cationic dye dyeable polyester, the normal pressure cationic dye dyeable polyester, and the like can be preferably used. A small amount of a matting agent such as titanium oxide, a fine pore-forming agent such as kaolinite, an antistatic agent, or the like may be added to these polymers.

The polyester filament mixed yarn of the present invention does not have a false twisted crimped polyester multifilament false twisted yarn A having a single fiber denier of 1.0 denier or less and a single fiber denier of 1.0 denier or more. It is necessary to include at least two of the polyester multifilament yarn B. The polyester multifilament false twisted yarn A needs to have a single fiber denier of 1.0 denier or less in order to exhibit a delicate soft touch on the surface. Single fiber denier is 1.0
If it exceeds denier, the soft touch of the surface touch is not sufficient, which is not preferable. More preferably, it is 0.5 denier or less.

The single fiber denier of the polyester multifilament yarn B must be 1.0 denier or more. The polyester multifilament B is mainly disposed on the core portion due to the heat history at the time of the dyeing processing of the polyester filament mixed fiber of the present invention, and is closely related to the woven and knitted fabric feeling and the feeling of waist. If the single fiber denier is less than 1.0 denier, it is not preferable because the tension and waist feeling are insufficient and the texture becomes rough. It is more preferably at least 1.5 denier, even more preferably at least 2.0 denier.

[0010] The polyester multifilament false twisted yarn A has a crimp elongation CC (A) of 3 as determined by the measurement method described below.
It needs to be 0% or more. Polyester multifilament false twisted yarn A is composed of ultrafine filaments having a single fiber denier of 1.0 denier or less. Unless false twist crimping is applied, individual filaments are relatively aligned in parallel in a minute section. Because it exists in the state of being in a state of being very thin, it cannot make full use of the feature of soft surface touch which is an ultrafine filament. It is important to disturb the parallelism in the minute section of each filament by false twist crimping in order to produce a delicate soft touch of the surface touch. False twisted crimp is CC
(A) is defined as being 30% or more.
If it is less than 30 [%], it is not preferable because a soft surface touch of each filament cannot be obtained. More preferably, it is 40% or more.

[0011] It is necessary that the polyester multifilament yarn B has no false twist crimp. When false twisted crimping is applied to the polyester multifilament yarn B, the whole polyester filament mixed yarn becomes substantially no different from the ordinary false twisted yarn, and becomes tight and lacks firmness. This is unfavorable because it gives a crisp texture.

In the polyester filament mixed yarn of the present invention, the difference in boiling water shrinkage between the polyester multifilament false twisted yarn A and the polyester multifilament yarn B having no false twist crimp is important. . The polyester multifilament false twisted yarn A is required to have a boiling water shrinkage rate such that it is relatively mainly located on the outer peripheral portion of the polyester filament mixed fiber yarn of the present invention due to heat history at the time of dyeing. SHW by the measuring method described later
(A) must be 7.0% or less.
If it exceeds 7.0%, even if the boiling water shrinkage of the polyester multifilament yarn B is increased, the processing shrinkage due to the heat history during the actual dyeing process cannot be as large as the boiling water shrinkage of the polyester multifilament yarn B. Therefore, a sufficient yarn length difference is not exhibited, and the bulky feeling is insufficient. SHW (A) of polyester multifilament false twisted yarn A
Is more preferably 6.0 [%] or less.

The polyester multifilament yarn B is
Due to the heat history at the time of the dyeing process, it is necessary to make the boiling water shrinkage ratio such that the polyester mixed fiber yarn of the present invention is relatively mainly located at the core. For that purpose, SHW (B) is set to 7.
It needs to be 0% or more. If the content is less than 7.0%, shrinkage due to heat history during dyeing cannot be increased even if SHW (A) is sufficiently small, so that a sufficient yarn length difference does not appear, and a bulky feeling is insufficient. Not preferred. SHW (B) is preferably 12.0% or more,
More preferably, it is 25.0% or more, and most preferably, 4% or more.
0.0 [%] or more.

The difference between SHW (B) and SHW (A) is
It is necessary to be 5.0% or more. SHW
When the difference between (B) and SHW (A) is less than 5.0 [%], the yarn length difference due to the heat history at the time of dyeing is insufficient, and SHW
(A) is 7.0% or less, and SHW (B) is 7.0%.
[%] Or more is not preferred.
The difference between SHW (B) and SHW (A) is preferably 6.
0% or more, more preferably 19.0% or more, and most preferably 34.0% or more.

Polyester multifilament yarn (B)
The SHW (B) should be at least 7.0 [%], but the maximum thermal stress measured by the below-mentioned measuring method is at least 0.12 [g / d], more preferably 0.25 [g / d]. It is preferable that it is above. This is effective in increasing the processing shrinkage of the woven or knitted fabric due to the heat history at the time of the dyeing process, and improving the bulky feeling.

The polyester filament mixed yarn of the present invention needs to have a Di of 50 [ke / m] or more as measured by a measuring method described later. This is for the purpose of handling in a later step and preventing defects in winding the mixed fiber into a cheese package. If it is less than 50 [m / m], the polyester filament mixed filaments from the package will have poor unwinding properties and, when the polyester filament mixed filaments are wound around a cheese package, polyester multifilaments having no false twist crimps It is not preferable because the tension hunting of (B) becomes large and package defects such as slippage and ear breakage are likely to occur, which is not preferable. is necessary. It is more preferably 100 [ke / m] or more, but if it is more than 200 [ke / m], it is not preferable because the soft touch of the delicate surface touch of the polyester multifilament false twisted yarn A is impaired.

The cross-section of the filaments of the polyester multifilament false twisted yarn A and the polyester multifilament yarn B is not particularly limited.
Any shape such as a polygonal cross section, a hollow cross section, a flat cross section, and a special deformed cross section can be used. Polyester multifilament false twisted yarn A and polyester multifilament yarn B have an average single fiber denier of 1.0% or less and 1.0 denier or more, respectively. Single fiber denier may be different.

It is preferable that the polyester multifilament false twisted yarn A and the polyester multifilament yarn B are each contained in the polyester filament mixed yarn of the present invention at a denier mixing ratio of 20% or more. If the denier mixture ratio of the polyester multifilament false twisted yarn A is less than 20%, the surface touch becomes coarse and the tension hunting when the polyester filament mixed yarn is wound into a cheese package becomes large, and the It is not preferable because defects easily occur. If the denier mixture ratio of the polyester multifilament yarn B is less than 20%, the tension and waist feel are insufficient, and the processing shrinkage at the time of dyeing cannot be increased, and the bulky feel is insufficient. If both are contained in a denier mixture ratio of 20% or more, three or more kinds of polyester filament mixed fibers containing one or more kinds of other polyester multifilaments may be used.

Next, a method for producing a polyester filament mixed yarn according to the second invention of the present invention will be described. The production method of the present invention is a rational one in which the process of false twisting or drawing false twisting to obtain a polyester multifilament false twisted yarn A and the process of fluid entanglement with the polyester multifilament yarn B are continuous. is there. First, a polyester multifilament false twisted yarn A is obtained such that the single fiber denier after false twisting or drawing false twisting becomes 1.0 denier or less. The supply raw yarn is obtained by drawing an undrawn yarn obtained by melt-spinning a polyester, but is a highly oriented undrawn yarn obtained by melt-spinning the polyester at a spinning speed of 2500 [m / min] to 4000 [m / min]; Ultra-high-speed spinning in which the yarn is drawn at a take-up speed of 4000 m / min or more, continuous drawn yarn, and the like can be applied.

The polyester multifilament false twisted yarn A is subjected to CC (A) by false twisting or drawing false twisting.
Is set to 30% or more. This is important in giving a delicate surface touch to the polyester filament mixed yarn, and is also important from the viewpoint of preventing defects of the package when winding the cheese package after the fluid entanglement treatment. Since the polyester multifilament yarn B does not have false twist crimping, the tension hunting when winding it into the cheese package of the false twisting machine is large, and only the polyester multifilament yarn B alone is used in the cheese package by the false twisting machine. Unless a special tension compensator is equipped, stable winding cannot be performed. For this reason, the polyester multifilament false twisted yarn A needs to have a crimp elongation CC (A) having a tension absorbing capacity that does not cause winding tension hunting after the fluid entanglement with the polyester multifilament yarn B. For this purpose, the twist coefficient K (A) of the false twist during the false twisting or the stretch false twisting is set to 18,000.
It is necessary that the heat setting temperature HI (A) at the time of false twisting or stretching false twisting be 160 ° C. or more.

The twist coefficient K (A) means that the total denier of the polyester multifilament false twisted yarn A after false twisting or drawing false twisting is D (A) [denier], and the number of false twists is T (A). ) [T / m], K (A) = T (A)
[D (A)] ^1/2 . K (A) is 1
If the molecular weight is less than 8,000, the crimp elongation of the polyester multifilament yarn (A) becomes insufficient, so that the soft touch of the surface touch of the polyester filament mixed fiber yarn is impaired. It is not preferable because the twill comes off and the ears are easily broken. More preferably, K (A) is 22,000 or more. However, from the viewpoint of false twisting operability, K (A) is preferably set to 35,000 or less.

Further, the heat setting temperature HI (A) needs to be 160 ° C. or higher in order to impart sufficient crimp elongation to the polyester multifilament false twisted yarn A. Although it is slightly affected by the heat setting property of the supply yarn and the type, length, yarn speed, etc. of the heater, it is required to be 160 ° C. or more, more preferably 180 ° C. or more. However, when the polyester multifilament false twisted yarn A is fused, the texture becomes coarse and hard. Therefore, it is preferable to set the upper limit to a temperature at which no fusion occurs between filaments. After false twisting or drawing false twisting, polyester multifilament false twisted yarn A is C
C (A) is 30% or more and SHW (A) is 7.0
[%] Is preferable.

The polyester multifilament false twisted yarn A obtained by the above false twisting or drawing false twisting
After the false twisting or the stretch false twisting, the polyester is multiplied with the polyester multifilament yarn B and subjected to a fluid entanglement treatment. In this case, the polyester multifilament yarn B preferably has an SHW (B) of 7.0% or more, and the difference from the SHW (A) of the polyester multifilament false twisted yarn (A) is 5.0. [%] Or more preferably has a large SHW (B). Since the polyester multifilament yarn B does not have false twist crimp, it is difficult to wind it alone into a cheese package of a false twisting machine. Therefore, the polyester entangled yarn having a small degree of tension hunting during winding is subjected to a fluid entanglement process with the polyester multifilament false twisted yarn A, so that the polyester filament mixed yarn reduces the degree of tension hunting during winding and the disadvantage of the wound cheese package. prevent. Therefore, it is necessary to the overfeed rate OF ₂ when the fluid entangling process +2.5 [%] or more. +2.5
If it is less than [%], the tension in the fluid entanglement treatment area becomes high, so that the degree of entanglement Di is insufficient, the winding tension hunting of the polyester multifilament B becomes apparent, and the polyester filament mixed yarn breaks off, and the ear breaks. This is not preferable because of the drawback of winding the cheese package. More preferably, it is 4.5% or more. When winding a different shrinkage mixed fiber composed only of filaments having no normal false twist crimp with a ring twister or the like, the overfeed rate in the fluid entangled treatment area is +0.2 to +0.5 [% ], A sufficient degree of entanglement that can satisfy the post-process passability is obtained, and if it exceeds +0.5 [%], yarn breakage tends to occur due to insufficient running tension.

However, the polyester filament mixed fiber yarn of the present invention requires a large overfeed rate of + 2.5% or more in order to be wound around a cheese package in a false twisting machine without any defect. In order that the polyester multifilament false twisted yarn (A) constituting the polyester filament mixed yarn of the present invention has sufficient crimp elongation,
Since the false twisting or the stretch false twisting is performed, even under such a high overfeed rate, the running can be performed while absorbing the excess and deficiency of the tension, and the fluid entanglement treatment can be performed. However, if the overfeed rate is too large, a large loop or slack occurs, and the unwinding property from the cheese package deteriorates. Therefore, it is preferable to keep the overfeed rate at about +10.0 [%].

For the fluid entanglement process, a general air entanglement nozzle can be widely used, and an interlace nozzle, a fluid disturbance nozzle, and the like are preferable. The air pressure is related to the total denier and the yarn speed of the polyester filament mixed yarn.
It is preferably about 0 to 4.0 kg / cm ² . After the fluid entanglement treatment, it is preferable that the entanglement degree Di has a large entanglement degree of 50 [ke / m] or more, more preferably 100 [ke / m] or more.

[0026]

【Example】

Example 1 Hereinafter, the present invention will be described with reference to examples. The measurement of the crimp elongation CC, the hot water shrinkage SHW, and the degree of confounding Di was performed as follows. Crimp elongation (%) Using a wrap reel (peripheral length: 1.125 m) having an appropriate tension adjusting device, apply a load of 1/10 (g / d) to make eight skeins. Put this on a hook, 100 ℃
The sample was immersed in hot water for 5 minutes under no load, taken out of the hot water and kept wet (2/10) × 8 × 2
X Apply a load of g of the indicated denier and measure the length a after 1 minute. Next, the load was removed, and the product was dried with a dryer at 60 ± 2 ° C. for 30 minutes while being hooked with no load, left in a test room in a standard condition for 1 hour or more.
/ 1000) × 8 × 2 × Apply the initial load of g of the indicated denier, and measure the length b after 1 minute. According to the following equation (9),
The crimp elongation rate is calculated using the above a and b. The number of tests is two or more, and the average value is shown (1 decimal place)
Digits). Crimp elongation (%) = (ab−a) × 100 (9)

Hot water shrinkage (%) A sample was measured at 0.1 g / d using a scale measuring machine with a frame circumference of 1.125 m.
The initial load is applied and the film is rewound at a rate of 120 turns / minute to form a small skein having 20 turns, and a weight of 40 times the initial load is applied to measure the skein length l ₀ (mm). Next, the weight is removed, immersed in boiling water for 30 minutes in such a manner that shrinkage is not hindered, taken out, wiped off with absorbent paper or cloth, and air-dried horizontally. Weight is again applied and the length is l ₁ (m
m) is measured. The hot water shrinkage is calculated by the following equation. The average value of five times of the test is taken as the measured value. Hot water shrinkage (%) = [(l ₀ −l ₁ ) / l ₀ ] × 100 (10)

Entanglement (K / m) A yarn of an appropriate length is taken out and suspended vertically by applying a load of 1/10 (g / denier) to the lower end. Then, an appropriate needle is inserted into the yarn, and the distance L (cm) for slowly lifting and moving until the load is lifted is measured 100 times, and the average value L (cm) is calculated from the following formula. Degree of confounding (q / m) = 100 / (2 × average L) (11)

Spinning speed of ordinary polyester is 30 in a conventional manner.
It was spun at a spinning temperature of 289 ° C. using a 108-hole nozzle at 00 m / min. The undrawn yarn is drawn by a draw-twisting machine 16S manufactured by Ishikawa Seisakusho Co., Ltd. at a hot roller temperature of 80 ° C., a hot plate temperature of 120 ° C., a draw ratio of 1.55 times, and a draw speed of 8
Drawing was performed at 50 m / min to obtain a drawn yarn A of 40 denier and 108 filaments. Next, a polyester obtained by copolymerizing 10% of isophthalic acid with a normal polyester was spun by a conventional method using a 24-hole nozzle at a spinning speed of 1700 m / min and a spinning temperature of 267 ° C. The undrawn yarn is drawn at a hot roller temperature of 84 ° C., a hot plate temperature of room temperature, and a draw ratio of 2.4 times using a draw-twisting machine 16S manufactured by Ishikawa Seisakusho Co., Ltd.
A drawn yarn B of d24f was obtained. The SHW of the drawn yarn (B) is 6
It was 0%.

Next, a TH311 type false twisting machine manufactured by Aiki Seisakusho Co., Ltd. was partially modified, and a second delivery roller was provided next to the delivery roller. The interlacer was installed. In this false twisting machine, the above-mentioned 40-denier 108 filament is drawn as a drawn yarn A at a spindle speed of 400,000 rpm, a twist number of 3500 T / M, and a false twisting temperature of 185 ° C., and then a drawn yarn (B) by a delivery roller.
And interlaced with an interlace between the second delivery roller. The delivery roller at this time and the second
Overfeed ratio between delivery rollers is +0.5
%, And the air pressure was 2.5 kg / cm ² . further,
The film was wound with a winding-type overfeed OF ₂ + 4.5%. In addition, CC of the processed yarn of only 40d108f is 40%,
SHW was 5%, and Di of the processed yarn after air entangling was 100 / m. After that, this processed yarn is double twisted with 4
A warp is obtained by adding a twist of 50 T / M to a warp, and one of commercially available Toyobo ester 150 denier 96 filaments is alternately twisted at 1800 T / M in S and Z for the weft. 152 warps / in, 67 wefts The plain weave was woven at / in and then dyed and finished in the usual steps of scouring, relaxing, presetting, weight loss, dyeing, final setting, and finishing. The weight loss rate was 20%.

Next, a comparative example will be described. Comparative Example 1 is the same as Example 1
Without false twisting of drawn yarn (SHW7%)
It was used. Comparative Example 2 is an example of drawn yarn B.
The hot plate temperature was set to 190 ° C.
HW was adjusted to 6.5%. Comparative example
3 is the same as in Example 1, except that the heater
At 140 ° C. and a crimp elongation of 25%.
You. In Comparative Example 4, the twist coefficient K (A) was 15,000 (twist number 2).
370 T / M) with a crimp elongation of 20%.
You. In Comparative Example 5, the air pressure of the interlacer was 0.5 k
g / cm^TwoThe one with G and the confounding degree of 20 / m
It is. Comparative Example 6 is overfeed OF _Two 1.5%
It is what it was.

Example 1 using the yarns of Comparative Examples 1 to 6 above
The same woven fabric as above was woven, dyed and finished. The woven fabric of Example 1 was excellent in soft surface touch and bulkiness, but Comparative Example 1 lacked the softness of the false twisted yarn and had a slimy feel. Comparative Example 2 showed that the drawn yarn (B )
Because of the small SHW, the softness and swelling were inferior. Comparative Examples 3 and 4 had low CCs and were similar to Comparative Example 1. In Comparative Example 4, the number of false twists was low, so that the false twist processability was also poor. In Comparative Example 5, since the Di was small, the false twisted yarn and the drawn yarn were separated from each other and caught, resulting in thread cutting and poor operability, and many woven fabrics had sink-like defects. Comparative Example 6 was inferior in unwinding property a shape defect of the package for OF ₂ is small.

[0033]

According to the present invention, it is possible to obtain a polyester mixed fiber having a soft surface touch and a bulky property, which is preferable for use in clothing.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI D02J 1/00 D02J 1/00 M (72) Inventor Kanji Togawa 2-8-2 Dojimahama, Kita-ku, Osaka-shi, Osaka Toyo Spinning Co., Ltd. In-house Examiner Kenji Sano (56) References JP-A-3-97933 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D02G 1/02 D02G 3/02- 3/04 D02J 1/00 D01F 6/62

Claims (2)

(57) [Claims] 1. A composite yarn which has been subjected to a fluid-entanglement process by means of a drawing process.
And a polyester multifilament false twisted yarn A having a single fiber denier of 1.0 denier or less and a polyester multifilament yarn B having a single fiber denier of 1.0 denier or more and having no false twist crimp. What is claimed is: 1. A polyester fiber blended yarn, comprising: a blended yarn configured to satisfy the following formulas (1) to (5). CC (A) ≧ 30 [%] (1) SHW (A) ≦ 7.0 [%] (2) SHW (B) ≧ 7.0 [%] (3) SHW (B) −SHW (A) ≧ 5.0 [%] (4) Di ≧ 50 [ke / m] (5) However, CC (A) is the crimp elongation rate (%) of polyester multifilament false twisted yarn A, and SHW (A) is Boiling water shrinkage rate (%) of polyester multifilament false twisted yarn A, SHW (B) is boiling water shrinkage rate (%) of polyester multifilament B, and Di is the degree of confounding (ke / m) of polyester filament mixed fiber. is there. 2. A polyester multifilament false twisted yarn A having a single fiber denier of 1.0 denier or less obtained by false twisting or stretch false twisting is subjected to single twisting after the false twisting or stretch false twisting. a method of manufacturing a crosstalk yarn fibers denier polyesters multifilament yarn B and Hikisoroe fluid entangling process no false twist crimping above 1.0 denier, satisfies the following formula (6) to (8) A method for producing a polyester multifilament mixed yarn, characterized by the following. K (A) ≧ 18000 (6) HI (A) ≧ 160 [° C.] (7) OF ₂ ≧ 2.5 [%] (8) However, K (A) is used for false twisting or stretch false twisting. HI (A) indicates the heat setting temperature [° C.] during false twisting or stretch false twisting, and OF ₂ indicates the overfeed rate [%] during fluid entanglement.