JPH10158932A - Polyester ultrafine yarn and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester yarn excellent in uniformity, dynamic characteristics such as mechanical strength and elongation and dyeability free from occurrence of loop and fluff and unevenness of fineness. SOLUTION: In cooling a polyester yarn of melt spinning to <=a glass transition temperature, traveling the yarn in a heating apparatus, drawing and heat- treating the yarn and taking up the yarn at >=4,000 minutes/minute, when an extruded amount of a single hole of a spinneret diameter (g/min)/an area (mm<2> ) of a single hole of the spinneret is M, an inlet, an inlet diameter of the heating apparatus is G (mm), a spinning speed is V (m/minute), a denier of single yarn after drawing is D, the number of filaments is N, the spinning is carried out under a condition satisfying the equations 10<=M+5D<=65, -20<=G-0.2N<=5 and -85<=M-0.02V<=-35 to make the denier of the single yarn <=1d and >=50% trans fraction of a crystal region in the whole trans fraction by infrared absorption method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester ultrafine fiber having a small fineness and extremely excellent yarn quality, and a method for producing the same.

[0002]

2. Description of the Related Art Polyester fibers are generally used after being drawn from the viewpoints of mechanical properties such as strength and elongation, dimensional stability, and other points. When the conventional polyester fiber is classified according to the manufacturing method, the yarn (FOY) obtained by two steps of spinning and drawing, the yarn (SDY) obtained by one step of direct spinning and drawing, and a high speed of 5000 m / min or more Thread (DS
Y) and the like.

[0003] However, the FOY process is divided into two processes, and often causes problems such as a decrease in quality due to movement between processes and a decrease in production efficiency in the next process. As a result, cost is reduced in terms of mass productivity. There were many difficulties such as.

[0004] In the case of SDY, by making spinning and drawing in one step, processability and mass productivity are excellent, but depending on the brand in heat treatment on a roller, thread breakage is remarkable and causes winding. Furthermore, in terms of fiber properties, FOY
In general, the shrinkage stress was lower than that of, and the swelling feeling was poor in the evaluation after processing. In addition, DSY has good processability and mass productivity, but this method of spinning can obtain only a low shrinkage (4 to 5%) yarn and is limited in application.

Further, as one type of the one-step method, a polyester fiber melt-spun is used, for example, at a rate of 4,000 m / min or more, or 2,000-45.
A method is known in which the material is once cooled to a temperature equal to or lower than its glass transition temperature while being taken up at a high speed of 00 m / min (while running at a high speed), and subsequently passed through a heating zone and stretched in the heating zone. (JP-B-45-1932 and JP-B-55-10684).

In this method, while the spun yarn is traveling at a high speed in the heating zone, air resistance acts on the traveling yarn in the heating zone, the tension of the yarn increases, and the yarn is drawn. Done. Therefore, it is not necessary to particularly use a mechanical drawing device such as using a plurality of rollers having different rotation speeds, and there is an advantage that drawn polyester fibers can be efficiently produced by simplified equipment. However, in this method, the quality of the fiber is greatly affected by the temperature of the heating zone, the running speed of the yarn, the tension applied to the running yarn, and the running speed of the yarn in the heating zone. There is a drawback that even if the tension applied to the running yarn or the running yarn delicately fluctuates, drawing unevenness is apt to occur, thereby easily causing yarn breakage, loop, fluff, fineness unevenness and the like. In particular, when the denier of a single yarn is 1.0 denier or less, the above-mentioned problem concerning the processability tends to be more remarkable.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a high-quality polyester which is excellent in uniformity without generation of loops and fluff, unevenness in fineness, and excellent in mechanical properties such as strength and elongation and dyeability. An object of the present invention is to provide an ultrafine fiber and a method for producing the same.

[0008]

Means for Solving the Problems In order to achieve the above object, the present inventors have studied the fiber structure properties of polyester fibers having good yarn quality, and furthermore, as a method for producing such fibers, When the spun polyester yarn is once cooled to a glass transition temperature or lower, and then passed through a heating zone while being taken off at a high speed, and then directly drawn in the heating zone to perform a direct spinning drawing method for producing polyester fibers. The heating zone temperature is determined by determining appropriate spinning conditions for the M value (single hole discharge amount Q / single hole area L) and single yarn denier, M value and spinning speed, heating zone diameter and number of filaments, etc.
Efficient processability of stretched polyester ultrafine fibers with little fluctuations in yarn running speed, tension applied to running yarns, no loops, no fluff, no unevenness of fineness, and excellent mechanical properties The inventors have found that they can be manufactured well, and arrived at the present invention.

That is, according to the present invention, the single yarn denier D is 1.
It is a polyester ultrafine fiber characterized by being not more than 0d and having a trans fraction of 50% or more in a crystalline region among all trans fractions measured by an infrared absorption method.

Furthermore, the present invention relates to a method for producing a fiber-forming polyester from a spinneret by melt-spinning a spun yarn to a temperature below the glass transition temperature, and then running the same in a heating device to carry out a drawing heat treatment. In the spinning method in which an oil agent is applied and drawn at 4000 m / min or more, the spinning conditions are as follows: spinneret single hole discharge amount Q (g / min) / sleeve single hole area L (mm ² );
When the inlet diameter of the heating device is G (mm), the spinning speed V (m / min), the denier of the single yarn after drawing is D, and the number of filaments is N, the conditions satisfying the following expressions (1) to (3) are satisfied. And spinning the polyester microfiber. 10 ≦ M + 5D ≦ 65 (1) −20 ≦ G−0.2N ≦ 5 (2) −85 ≦ M−0.02V ≦ 35 (3)

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester used in the present invention is not particularly limited as long as it is a melt-spinnable polyester, and the polyester is mainly polyethylene terephthalate, polyethylene terephthalate, or an ethylene terephthalate unit and / or a butylene terephthalate unit. It is preferably a copolyester containing a small amount of other copolymerized units as a structural unit, and more preferably polyethylene terephthalate.

When a copolyester mainly comprising ethylene terephthalate units and / or butylene terephthalate units is used as the polyester, the proportion of other copolymerized units in the copolyester is preferably 10 mol% or less. Examples of other copolymerized units in this case include aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, 2,6-naphthalene dicarboxylic acid, and 5-alkali metal sulfoisophthalic acid, oxalic acid, adipic acid, azelaic acid, and sebacic acid. Aliphatic dicarboxylic acids such as; trimellitic acid, polyfunctional carboxylic acids such as pyromellitic acid, or carboxylic acid units derived from their ester-forming components; diethylene glycol, propylene glycol, butanethiol or ethylene glycol, polyethylene glycol, Guri Phosphorus, may be mentioned units derived from pentaerythritol. The copolyester can contain one or more of the above-mentioned copolymer units.

Further, if necessary, the polyester may contain one of a fluorescent whitening agent, a stabilizer, an antioxidant, an ultraviolet absorber, a hydrolysis inhibitor, an antistatic agent, a flame retardant, an inorganic fine particle for matting, and other additives. Species or two or more species may be contained.

In the present invention, the viscosity and molecular weight of the polyester are not particularly limited, and may be any viscosity and molecular weight that can be melt-spun. However, the use of a polyester having an intrinsic viscosity [η] of 0.60 to 0.65 when measured at 30 ° C. in a mixed solution of phenol and tetrachloroethane in an Ubbelohde viscometer in terms of spinnability and physical properties of the obtained polyester fiber. Is preferred.

The polyester ultrafine fibers of the present invention are those having a single yarn denier of 1.0 denier or less, more preferably 0.8 denier or less. If it exceeds 1.0 denier, the texture of the target ultrafine fibers will be lacking when used for clothing fabrics and the like. There is no particular limitation on the number of filaments, but depending on the denier,
Alternatively, the number of filaments according to the application can be adopted.

Next, the fiber structure of the polyester ultrafine fiber of the present invention is such that the ratio (B / B) occupied by the trans fraction (B) of the crystal region to the total trans fraction (A) determined by the infrared absorption method.
A) needs to be 50% or more. That is, in the infrared absorption method, the amorphous portion can be classified into two types, trans and gouge, by conformation analysis as shown in Table 1 below and compared, but the total trans fraction (trans CTtotal)
At least 50%, more preferably at least 60%, must be trans (CTcrys) in the crystalline region. When the trans fraction in the crystal region is less than 50% of the total trans fraction, the heat shrinkage stress is low, and when it is made into a woven fabric, the feeling and surface feeling as ultrafine fibers are poor.

[0017]

[Table 1]

Next, the manufacturing method of the present invention will be described.
In the production method of the present invention, a fiber-forming polyester yarn melt-spun from a spinneret is once cooled to a temperature lower than the glass transition point, and then drawn in a heating device (sometimes called a heating zone). -Apply oil after heat treatment,
It winds at a take-up speed of 4000m / min or more. In this case, the melt spinning temperature, the melt spinning speed and the like are not particularly limited,
It can be carried out under the same conditions as those usually used for producing polyester fibers, but generally has a melt spinning temperature of (melting point of polyester + 20 ° C) to (polyester melting point + 40 ° C). (For example, generally about 280 to 300 ° C. in the case of polyethylene terephthalate),
And the melt spinning speed (melt spinning amount) is about 15-50g / spinning hole 1
The range of about mm ² · minute is preferable because a polyester fine fiber of good quality can be obtained with good spinning processability. The size and number of the spinning holes in the spinneret, the shape of the spinning holes, and the like are not particularly limited, and can be adjusted according to the desired single-fiber fineness, the total denier number, and the cross-sectional shape of the target polyester ultrafine fiber. The size of the spinning hole (single hole) is desirably about 0.018 to 0.07 mm ² .

Then, the polyester fiber melt-spun as described above is once cooled to a temperature lower than its glass transition temperature, preferably 10 ° C. or lower than the glass transition temperature. The cooling method and the cooling device in this case are not particularly limited as long as the method and the device can cool the spun polyester fiber to the glass transition temperature or lower, but are not particularly limited. It is preferable that a cooling air blowing device is provided, and cooling air is blown onto the spun polyester fiber to cool the polyester fiber to a temperature lower than the glass transition temperature. At this time, cooling conditions such as the temperature and humidity of the cooling air, the blowing speed of the cooling air, and the angle at which the cooling air is blown onto the spun yarn are not particularly limited, and the polyester fibers spun from the die may shake. Any conditions may be used as long as they can be rapidly and uniformly cooled to the glass transition temperature or lower while keeping the temperature below the glass transition temperature. Among them, the cooling air temperature is about 20 ~ 30 ℃, the cooling air humidity is 20 ~ 60%, and the cooling air blowing speed is 0.4 ~ 1.0m / sec. It is preferable to cool the spun polyester fiber in a direction perpendicular to the exit direction because high-quality polyester fiber can be smoothly obtained. In addition, when cooling is performed under the above conditions using a cooling air blowing cylinder, a cooling air blowing cylinder having a length of about 80 to 120 cm is provided with or without a slight interval directly below the spinneret. Is preferably arranged.

Next, the polyester fiber cooled to the glass transition temperature or lower is subsequently directly introduced into the heating zone as it is and stretched. The temperature of the heating zone may vary depending on the type of polyester, etc., but if the temperature is set at 40 ° C. or higher than the glass transition temperature of the polyester, the physical properties of the obtained polyester fiber can be made practically satisfactory. For example, in the case of polyethylene terephthalate fiber, the temperature of the heating zone is preferably set to about 100 ° C. or higher. The upper limit temperature of the heating zone may be any temperature that does not cause fusion between fibers, breakage of yarn, breakage of single yarn, and the like in the heating zone.

The type and structure of the heating zone are such that the polyester fiber running in the heating zone can be heated without contacting the heating means in the heating zone, and the yarn running in the heating zone and the filaments can be heated. Any structure may be used as long as it can generate resistance between the surrounding air and increase the yarn tension to cause drawing of the fiber. Among them, as the heating zone, a heating zone having a tubular structure is preferably used, and particularly a tube heater having an inner diameter of about 20 to 50 mm, in which the tubular wall itself is a heater, is preferred.

The installation position of the heating zone from the spinneret, the length of the heating zone, etc. depend on the type of polyester fiber, the amount of polyester spun, the cooling temperature of the polyester fiber, the running speed of the polyester fiber, the temperature of the heating zone, and the heating zone. It can be adjusted according to the inner diameter of the band, etc., but the distance from directly below the spinneret to the entrance of the heating zone is about 0.5 to 3.0 m. m
Is more preferable, and the length of the heating zone is 1.0 to 2.0 m
It is desirable to set the degree to such a degree that the polyester fiber can be uniformly and smoothly stretched by heating in the heating zone.

Then, an oil agent is applied to the polyester fiber drawn in the heating zone, if necessary, and then the polyester fiber is drawn at a high speed. In the present invention, the production process of the stretched polyester fiber consisting of the above-described series of processes requires that the take-up speed of the polyester fiber be 4000 m / min or more, and the take-up speed is preferably 4500 m / min or more. . When the take-up speed of the polyester fiber is less than 4000 m / min, the drawing of the fiber is not sufficiently performed in the heating zone, the mechanical properties of the obtained polyester fiber are reduced, and the present invention comprising the above-described series of steps is performed. The method is not carried out smoothly, and in particular, fluctuations in the tension of the yarn in the heating zone, overheating, etc. occur, making it difficult to perform uniform stretching.

In carrying out the present invention, the M value (single hole discharge amount Q / single hole area L) and single yarn denier D, the heating zone entrance G (mm), the number of filaments N, the M value and the spinning V (m /
Min) 10 ≦ M + 5D ≦ 65 (1) −20 ≦ G−0.2N ≦ 5 (2) −85 ≦ M−0.02V ≦ 35 (3) must be satisfied at the same time. In equation (1), M
If the value of + 5D is less than 10, the back pressure of the nozzle is low, which causes a sectional failure or winding due to a discharge failure. On the other hand, M
If the value of + 5D exceeds 65, the back pressure of the nozzle is too high, and the melt fracture tends to occur, and the uniformity of the cross section also deteriorates. More preferably, the range is 15 ≦ M + 5D ≦ 50.

Next, if the value of G-0.2N in the formula (2) is less than -20, the number of filaments during spinning is
The diameter of the inlet of the heating zone becomes too small, and the single yarn breakage due to the guide resistance is apt to occur, thereby deteriorating the processability. On the other hand, when the value of G-0.2N exceeds 5, the inlet diameter of the heating zone becomes too large, and the temperature in the heating zone is cooled, so that the drawing and heat treatment of the yarn are not sufficiently performed and the fiber properties are satisfactory. Can not be obtained. The exit diameter of the heating zone is desirably as small as possible in terms of quality, but considering the workability of lowering the yarn at the time of yarn introduction, 8 mm to 15 mm is appropriate depending on the brand such as the number of filaments.

Further, regarding the M value and the spinning speed V in the equation (3), M
When the value of -0.02V is less than -85, the nozzle back pressure becomes insufficient, and when the value of M-0.02V exceeds -35, the nozzle back pressure becomes too high. Cause. By satisfying the expressions (1) to (3), the yarn breakage due to the unevenness of the drawing caused by the fluctuation in the running speed and the tension applied to the running yarn, which has conventionally been a problem,
Loops, fluff, etc. are greatly improved. In the present invention,
The cross-sectional shape of the polyester ultrafine fiber is not particularly limited, and is not limited to a normal round cross-section, for example, an elliptical shape, a triangular shape,
Square, polygon, hollow, multi-lobe, array, V-shaped, T
It may have an irregular cross section such as a letter shape.

[0027]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited thereto. In addition, the physical property values in each Example and Comparative Example were measured by the following methods. <Strength and elongation of fiber> The strength and elongation were determined from a stress-strain curve obtained using a tensile tester manufactured by Instron. <Quantification of transformer fraction> JEOL FT-IR (JIR-5500)
And the peak area A _{988 of the 988} cm ^-1 band (crystallized band) and the peak area A _{793 of the 793} cm ^-1 band (internal standard) using a photoacoustic spectrometer manufactured by MTEX and a crystal fraction using the formula (1 ′). CTcrys were sought. _{CTcrys = {1.12 × (A 988} / A 793) + 0.092} × 100 (1 ') The 973 cm ^-1 band (trans): O-C stre
peak area A ₇₉₃ of tching peak area A ₉₇₃ and 793cm ^-1 band (internal standard) (2 ') and (3') trans fraction of all-trans fraction CTtotal and in amorphous from equation CT
amor sought. CTtotal = 0.12 × (A ₉₇₃ / A ₇₉₃ ) × 100 (2 ′) CTamor = CTtotal−CTcrys (3 ′) <Uniformity of polyester fiber (Wooster spots: U%)>
The yarn is passed between the electrodes at a constant speed using a Worcester spot tester manufactured by Zellbaker (yarn speed 100 m / min, range ± 1).
(2.5%, chart speed 10 cm / min) A change in electric capacity proportional to a change in cross section was continuously measured, and an average deviation coefficient U% of a constant length of the yarn was measured. <Evaluation of yarn-making process> Good process condition (○), level of mass production now (△), mass-production pear (×) <Dyeing / hand feeling evaluation> Plain fabric using polyester fiber obtained as warp and weft Was woven and subjected to ordinary weight loss dyeing and finishing to obtain a woven fabric, which was evaluated by panelists, and was evaluated as good (○), now one step (△), and poor (×).

Example 1 Polyethylene terephthalate ([η] = 0.65) was filled with 96 holes.
Spinning temperature of 295 ° C, single-hole discharge rate (Q) of 0.40 g / min, melt spinning temperature of 25 ° C, humidity of 60
% Cooling air at a speed of 0.5 m / sec onto the spun yarn.
After the temperature is reduced to 70 ° C or less, it is introduced into a tube heater (internal temperature: 180 ° C) with a length of 1.0m, an inlet diameter of 10mm, an outlet diameter of 10mm, and an inner diameter of 30mmφ, which is installed 1.0m below the spinneret. After that, the yarn coming out of the tube heater is lubricated with a crow mouth guide and passed through two take-off rollers.
At a speed of 4700 m / min, a drawn polyester fiber of 75d / 96f was obtained. Tables 2 and 3 show the yarn forming conditions at that time, and the structural properties and dyeing / feeling evaluation of the resulting fibers.

[0029]

[Table 2]

[Table 3]

Example 2 Polyethylene terephthalate ([η] = 0.65) was filled with 1 hole.
Spinning temperature 298 ℃, using 44 (0.15mmφ hole diameter)
Melt spinning at a single hole discharge rate (Q) of 0.26 g / min. Spraying the cooling air at a temperature of 25 ° C and a humidity of 60% onto the spun yarn at a speed of 0.5 m / sec. After being introduced into a tube heater (internal temperature 180 ° C) with a length of 1.0m, an inlet diameter of 12mm, an outlet diameter of 10mm, and an inner diameter of 30mmφ, which is installed 1.0m below the spinneret, stretched in the tube heater, The emerging yarn was lubricated with a crow's mouth guide and wound up at a speed of 4500 m / min via two take-up rollers to obtain a drawn polyester fiber of 75d / 144f. Tables 2 and 3 show the spinning conditions and the evaluation of the structure, physical properties and dyeing / feeling of the resulting fiber.

Example 3 Polyethylene terephthalate ([η] = 0.65) was filled with 96 holes.
Melt spinning at 295 ° C with a single hole (hole diameter 0.15mmφ) at a spinning temperature of 295 ° C and a single hole discharge rate (Q) of 0.23g / min.
A 60% cooling air is blown onto the spun yarn at a speed of 0.5 m / sec to reduce the yarn to 70 ° C. or less, and then placed 1.0 m below the spinneret at a length of 1.0 m, an inlet diameter of 10 mm, After being introduced into a tube heater (inner temperature 200 ° C) with an outlet diameter of 10 mm and an inner diameter of 30 mmφ and stretched in the tube heater, the crow mouth guide oil is supplied to the yarn coming out of the tube heater and passed through two take-off rollers. At a speed of 4000 m / min, a drawn polyester fiber of 50d / 96f was obtained. Tables 2 and 3 show the spinning conditions and the evaluation of the structure, physical properties and dyeing / feeling of the resulting fiber.

Comparative Example 1 The procedure of Example 1 was repeated except that the number of holes in the spinneret was 96 (hole number: 0.3 mmφ), the single hole discharge rate (Q) was changed to 0.35 g / min, and the winding speed was changed to 4000 m / min. In the same manner, a 75d / 96f drawn polyester fiber was obtained. The process was unsatisfactory with many thread breaks.
Further, the cross-sectional uniformity of the fiber was at an unsatisfactory level, and the U% waveform and the evaluation of the fabric were not good. Tables 2 and 3 show the structure, physical properties, dyeing, and texture evaluation of the resulting fiber.

Comparative Example 2 A yarn was produced in the same manner as in Example 1 except that the single hole discharge rate (Q) was changed to 0.32 g / min and the winding speed was changed to 3700 m / min, to obtain a 75d / 96f drawn polyester fiber. . The elongation was large in physical properties, the thermal stress value was low, and the fabric evaluation was poor. Tables 2 and 3 show the structure, physical properties, dyeing, and texture evaluation of the resulting fiber.

Comparative Example 3 A yarn was produced under the same conditions as in Example 2 except that the inlet diameter of the tube heater was 8 mm and the spinning speed was 4000 m / min.
/ 144f drawn polyester fiber was obtained. Process condition was remarkably bad, and thread breakage occurred frequently. Tables 2 and 3 show the structure and physical properties of the resulting fiber. However, the process condition was poor and could not be used for fabric evaluation.

Each of the fibers obtained in Examples 1 to 3 had a good condition in the spinning process, no fineness unevenness, and a good woven fabric evaluation. On the other hand, in Comparative Examples 1 to 3, the process condition was not obtained, or even if the process condition was obtained, the physical properties were insufficient, and as a result, the fabric evaluation was unsatisfactory.

Claims (2)

[Claims] 1. A single yarn denier D is 1.0d or less,
A polyester ultrafine fiber, wherein the trans fraction in the crystalline region accounts for 50% or more of the total trans fraction determined by an infrared absorption method. 2. A fiber-forming polyester is melt-spun from a spinneret, and the spun yarn is once cooled to a temperature below the glass transition temperature, then run in a heating device, subjected to a drawing heat treatment, and an oil agent is applied. In the spinning method of drawing at a speed of 4000 m / min or more, the spinning conditions include a single hole discharge rate Q (g / min).
Where M is the area of the single hole of the die, L (mm ² ), G is the inlet diameter of the heating device, V is the spinning speed, and D is the denier of the single yarn after drawing, and N is the number of filaments. The following equation (1)
The method for producing a polyester fiber according to claim 1, wherein the spinning is performed under conditions that simultaneously satisfy (3). 10 ≦ M + 5D ≦ 65 (1) −20 ≦ G−0.2N ≦ 5 (2) −85 ≦ M−0.02V ≦ −35 (3)