KR20050003122A - Polyethylene-2,6-naphthalate fibers by using high speed spinning and radial in to out quenching method, and process for preparing the same - Google Patents

Abstract

PURPOSE: A manufacturing method of polyethylene-2,6-naphthalate fiber is characterized by using a spin oiling agent having low viscosity and using a high velocity spinning method and a radial in to out quenching method. The polyethylene-2,6-naphthalate fiber has at least 7.5g/d of strength, under 4.7% of shrinkage, 2.5-6denier of single yarn fineness, at least 1000denier of total fineness and high coefficient of variation(CV%). A treated cord manufactured out of the polyethylene-2,6-naphthalate fiber has excellent dimensional stability and strength, and is useful for industry like a tire or a belt. CONSTITUTION: Polyethylene-2,6-naphthalate fiber is obtained by the steps of: (A) extruding spun yarn containing at least 85mol% of ethylene terephthalate unit and having 0.70-1.3 of inherent viscosity at 290-330deg.C; (B) passing the spun yarn through a delay-cooling area, followed by quenching the spun yarn with a radial in to out flow quenching method to solidify the spun yarn; (C) oiling the spun yarn at a distance of under 2m from an initial winding roller; (D) winding undrawn yarn at 1000-3500m/min. of spinning velocity to make the undrawn yarn having 0.015-0.1 of birefringence and 2-20% of crystallinity; and then (E) multistage-drawing the yarn in a total draw ratio of 1.3-4.0. The polyethylene-2,6-naphthalate fiber has (1)0.6-1.0 of inherent viscosity, (2)at least 7.5g/d of strength, (3)at least 6% of elongation, (4)at least 0.35 of birefringence, (5)1.355-1.375 of density, (6)under 6.0% of coefficient of variation(CV%) of filament sectional diameter and (7) 1-3% of shrinking percentage.

Description

Polyethylene-2,6-naphthalate fibers by using high speed spinning and radial in-out cooling methods and manufacturing method thereof the same}

The present invention relates to a method for producing polyethylene-2,6-naphthalate multifilament yarn by a high-speed spinning method and a radial in-out cooling method. Industrial yarn manufactured according to the present invention has high productivity and is advantageous in terms of economy. Rather, it provides a treated cord with excellent dimensional stability and tenacity.

Polyethylene-2,6-naphthalate has a bulky naphthalate unit, which has a higher glass transition temperature, crystallization temperature, melting temperature, and melting point than polyethylene terephthalate. That is, in order to lower the melt viscosity of the melt during spinning is spinning at a temperature relatively higher than the normal spinning temperature (310 to 320 ℃).

High strength polyethylene-2,6-naphthalate fibers are used in a variety of industrial applications, including rubber reinforcement tire cords, seat belts, conveyor belts, V-belts and hoses. In order to be applied as a fiber reinforcement to convert to a treatment cord by the latex treatment and heat treatment, better shape stability and strength is required.

US Pat. No. 4,101,525 (Davis et al.) And US Pat. No. 4,491,657 (Cyto et al.) Disclose industrial polyester multifilament yarns having high initial modulus and low shrinkage. Since then, efforts have been continuously made to make high strength yarns at higher speeds with higher spinning speeds.

At high intrinsic viscosity (IV), preferably within the high spinning speed range of 0.9 to 1.2 at intrinsic viscosity (IV) of 1,000 to 3,500 m / min, the polymer and the spinning temperature are the same. It is generally known in the manufacturing field of industrial polyester yarn that the dimensional stability of the processing cord and the strength utilization rate of the yarn tend to be further improved.

Considering this theoretically, when manufacturing industrial polyester yarns, the radial tension should be increased to increase the orientation of undrawn yarn and the formation of tie chains connecting crystals with crystals. And it is possible to increase the strong utilization of the yarn, and to obtain a higher strength treatment code, it is necessary to further improve the uniformity of fineness and orientation between the undrawn yarn filaments to enable high magnification of the stretched yarn with such a highly oriented undrawn yarn.

In this respect, a method of making improved polyester multifilament yarns with high strength and low shrinkage lies in making a more uniform undrawn yarn under more rapid quenching (more rapidly than It is a common phenomenon to obtain more non-uniform yarns than to cool them).

Radial in-to-out quenching is advantageous as a method of making uniform undrawn yarns in the US Pat. Nos. 3,858,386 (Richard Stoppan) and 3,969,462 (Richard Stoppan). It is well explained with uniformity. However, this method has been used to produce high strength polyethylene terephthalate at low spinning speeds of up to 1,000 m / min.

U.S. Patent No. 4,285,646 (Roland Wight) is characterized in that the cooling gas is supplied through the spin pack in the radial in-out cooling method, but it is difficult to apply to the actual process and technically difficult.

U.S. Patent 4,414,169 (Edward B. McClellry) mentions only the preferred radial in-out cooling method. The cooling unit also has a diameter of 1.5 inches and a length of 36 inches. It is not suitable for producing polyester low shrinkage high modulus tire cord spraying more than 1,000 denier.

U.S. Pat.No. 5,866,055 (Rymund, Schwarz et al.) Also used radial in-out cooling as a method for producing improved polyester multifilament yarns having high modulus and low shrinkage. . This method is theoretically possible to achieve uniform rapid cooling, but since the spinning filaments are fed to the angular filaments with a disk type emulsion feeder near the bottom of the radial in-out chiller, In order to avoid scattering, high viscosity spinning oil must be used and contact with the oil supply device near the nozzle, so that the damage to the single yarn is less than the conventional method of contacting the oil supply device near the lower winding roller. The degree is large.

In addition, the method of producing polyethylene-2,6-naphthalate multifilament yarn for tire cords having high strength and low shrinkage by high spinning stress by the high-speed spinning method is uniform adhesion of spinning oil, spinning filament Since there is a problem in the uniformity of the tension applied to the practically there was a problem in producing a high-density than 1000 denier or a high-speed spinning process with a spinning speed of 1,000 to 3500 m / min.

The present invention is to produce a polyethylene-2,6-naphthalate multifilament yarn for high strength tire cords manufactured from partially oriented non-stretched yarn by a high-speed spinning and radial in-out cooling method, uniform adhesion of spinning oil, spinning 1,000 denier or more of denier polyethylene-2 at high spinning speeds of 1000 to 3500 m / min, by improving the uniformity of the tension across the filaments and enabling the use of relatively low viscosity spinning oils, especially aqueous spinning oils. It enables the production of 6-naphthalate multifilament yarns, and the technical problem is to provide a method for producing high strength polyethylene-2,6-naphthalate multifilament yarns by applying a radial in-out cooling method.

Radial in to out flow quenching: Cooling uniformity between filaments by discharging cooling air from the inside of the filament bundle to the outside using a cylindrical cooling air discharge device using a filter under the spinneret Quenching method to improve the performance.

1 is a manufacturing process schematic diagram of the present invention.

The present invention comprises the steps of extruding the discharge yarn containing (A) more than 85 mol% ethylene terephthalate units and intrinsic viscosity in the range of 0.80 ~ 1.2 to a temperature of 290 ~ 330 ℃, (B) delay cooling the melt release yarn Quenching and solidifying by radial in-out flow cooling after passing through the zone, (C) imparting an emulsion at a distance within 2 m from the initial winding roller, and (D) the birefringence of the unstretched yarn being 0.015 to 0.1 And winding the yarn so that the degree of crystallinity is 2 to 20%, and (E) multistage stretching the wound yarn at a total draw ratio of 1.3 to 4.0 times. It relates to a manufacturing method of the company.

The polyethylene-2,6-naphthalate polymer used in the present invention contains at least 85 mole% of ethylene-2,6-naphthalate units and preferably consists only of ethylene-2,6-naphthalate units.

Optionally, the polyethylene-2,6-naphthalate may incorporate as a copolymer unit small amounts of units derived from one or more ester-forming components other than ethylene glycol and 2,6-naphthalene dicarboxylic acid or derivatives thereof. Can be. Examples of other ester forming components copolymerizable with polyethylene naphthalate units include glycols such as 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, and the like, terephthalic acid, isophthalic acid, hexahydroterephthalic acid, stilbene Dicarboxylic acids such as dicarboxylic acid, bibenzoic acid, adipic acid, sebacic acid, azelaic acid.

The polyethylene naphthalate chip according to the present invention preferably melt-mixes naphthalene-2,6-dimethylcarboxylate (NDC) and ethylene glycol raw materials at 190 ° C. at a ratio of 2.0 to 2.3 and transesterifies the melted mixture. Reaction (for about 2 to 3 hours at 220 to 230 ° C.) and condensation polymerization (about 2 to 3 hours at 280 to 290 ° C.) to produce raw chips having an intrinsic viscosity of 0.42 to 0.60, followed by 240 Solid phase polymerized to have an intrinsic viscosity of 0.80 to 1.20 and a moisture content of 30 ppm or less at a temperature of from 260 ° C. and a vacuum.

In the transesterification reaction, as a transesterification catalyst, a manganese compound, preferably manganese acetate, may be added in an amount such that the remaining amount of manganese metal in the final polymer is 30 to 70 ppm. If the exchange reaction rate is too slow, and more than 70 ppm, more than necessary manganese metal acts as a foreign matter and becomes a problem in solid state polymerization and spinning.

In the polycondensation reaction, as the polymerization catalyst, an antimony compound, preferably antimony trioxide, may be added in an amount such that the amount remaining as an antimony metal in the final polymer is 180 to 300 ppm. When the polymerization efficiency is lowered, the polymerization efficiency is lowered, and when it is more than 300 ppm, more than necessary antimony metal acts as a foreign matter, which degrades radio-stretching workability. In this case, a phosphorus heat stabilizer, preferably trimethyl phosphate, may be added in an amount such that the remaining amount of phosphorus element in the final polymer is 35 to 45 ppm, and the manganese / phosphorus content ratio is 2.0 or less. When the manganese / phosphorus content ratio is higher than 2.0, the oxidation is promoted during the solid phase polymerization, so that normal physical properties cannot be obtained during spinning.

The polyethylene naphthalate chip thus produced is fiberized according to the method of the present invention, and FIG. 1 schematically shows a manufacturing process according to one embodiment of this invention.

In the present invention, in step (A), the polyethylene-2,6-naphthalate chip having an intrinsic viscosity (IV) of 0.8 to 1.2 is extruded and melted to a temperature of 290 to 330 ° C through the spinning pack 1 and the nozzle 2. Reduction of the viscosity of the polymer by pyrolysis and hydrolysis was prevented by relatively low temperature melt spinning. At this time, the fine yarn fineness of the final stretched yarn is adjusted so that the fine yarn fineness of the discharge yarn is 2.5 to 8 denier.

In step (B), the melt discharged yarn (4) of step (A) is quenched by passing through the cooling zone (3), if necessary, the distance from the nozzle (2) directly below the starting point of the cooling zone (3). That is, a short heating device may be installed in the length (L) of the hood.

This zone is called delayed cooling zone or heating zone, which has a length of 50 to 250 mm and a temperature of 250 to 400 ° C. (air contact surface temperature).

In the cooling zone 3 a radial radial in-out chiller is used. The cross-sectional diameter (R) of the cooling device is 12 cm or more, the length of the cooling zone is preferably 60-100 cm, preferably 70-90 cm, and the quenching air temperature is 15-60 ° C., preferably 15 to 40 ℃ temperature. The speed of the cooling air is 0.4 to 1.2 m / sec at the maximum, preferably 0.8 to 1.0 m / sec. The velocity distribution of the cooling air is applied to the P type (the upper part is strong and weakens toward the bottom) or the I type (the upper part and the lower part is almost constant velocity).

The emitting yarns 4 should be as close to the radial in-out chiller as possible, without forcing them to come into contact with them, and they should be such that the radiation tension is not affected by natural contact. The discharge yarn 4 is provided with a spinning oil of 0.5 to 1.0% by the emulsion imparting device 5 in step (C) and can apply conventional oiling methods (roller oil ring, jet oil ring). In the present invention, an aqueous spinning oil is preferably used.

In step (D), the yarn is wound at a spinning speed such that the birefringence of the undrawn yarn is 0.015 to 0.1 and the crystallinity is 2 to 20% in the first stretching roller 6, and the preferred spinning speed is 1000 to 3500 m / Minutes.

In the present invention, the birefringence rate and crystallinity of the undrawn yarn are used as factors for controlling the microstructure of the undrawn yarn. If the birefringence and the crystallinity are less than 0.015 and 2%, respectively, the undrawn yarn has low orientation, and thus the initial crystallization rate is slowed in the drawing step, so that crystal formation cannot be sufficiently induced. If the birefringence and the crystallinity exceed 0.1 and 20%, respectively, Due to excessive crystal formation in the shrine, it is difficult to manufacture high-strength yarns because of its sharp elongation.

In particular, the present invention by producing a non-oriented yarn partially oriented by the high-speed spinning and radial in-out cooling method, the non-drawn yarn has a birefringence variation coefficient and cross-sectional diameter variation coefficient between the single yarn is 4.0% or less and excellent in birefringence and fineness uniformity Efficient elongation is achieved in the process.

In step (E), the yarn having passed through the first drawing roller 6 is passed through a series of drawing rollers 7, 8, 9 and 10 by spin draw method, and has a total draw ratio of 1.3 to 4.0 times. In the following, the final stretched yarn 11 is obtained by stretching 1.5 to 2.5 times.

While narrowing the distance between the nozzle and the top of the cooling section as possible during spinning, it is advantageous to have a high strength in the final stretched yarn.However, when spinning, the distance from the bottom of the nozzle to the bottom of the heating device is 50 mm or less (actually, Since there is a radial block of about 50mm, the distance from the bottom of the heater to the bottom of the heater is 100mm when using a heater of 50mm length.The distance between the bottom of the heater and the top of the radial in-out chiller is 50 ~ 150mm. Uneven stretching of cotton causes a considerable amount of unevenness, which makes stretching impossible.

Polyethylene-2,6-naphthalate unstretched yarn produced according to the present invention has an intrinsic viscosity of 0.60 to 1.1, the birefringence of the unstretched yarn is 0.015 to 0.1, the crystallinity is 2 to 20%, the coefficient of variation of the birefringence rate, and the variation of the cross section. The coefficient is superior to that of the conventional cooling method.

In addition, the drawn yarn produced according to the present invention can be converted into a treatment code by a conventional treatment method.

For example, two strands of stretched yarn of 1,500 deniers are plyed & cabling to 390 tpm (twist / m) (typical polyethylene-2,6-naphthalate treated cord number of twists) to prepare a cord yarn, and then 1 After immersing in adhesive liquid [Isocyanate + Epoxy or PCP resin + RFL (Resorcynol- Formalin- Latex)] in 1st Dipping Tank, 130 ~ 160 ℃ in Drying Zone Dry for 150-200 seconds under 1.0-4.0% stretch, and heat for 45-80 seconds with a stretch of 2.0-6.0% at a temperature of 235-245 ° C. in a hot stretching zone. After fixing (Heat Set), it was immersed in the adhesive liquid (RFL) again in the 2nd Dipping Tank and dried for 90 to 120 seconds at the temperature of 140-160 degreeC, and then the temperature of 235-245 degreeC- Manufactured dipped cord by heat setting for 45 to 80 seconds with 4.0 ~ 2.0% stretch The.

The treatment cord thus prepared (based on 1500 denier two-strand top and bottom 390 tpm) has a strength of 2.0 to 5.0% of E2.25 + FS and 6.0 to 8.0 g / d (E2.25; 2.25 g / d). Elongation at, FS; free shrinkage).

As such, the treatment cord made of the high strength and low shrinkage polyethylene-2,6-naphthalate multifilament yarn according to the present invention has excellent dimensional stability and strength, and thus is used as a reinforcement material for rubber products such as tires and industrial belts or for other industrial uses. It can be usefully used.

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are not intended to limit the present invention, but are not limited thereto. Various physical property evaluations of the yarns and treatment cords prepared in Examples and Comparative Examples of the present invention were performed by the following methods.

(1) Intrinsic viscosity (I.V.)

After dissolving 0.1 g of the sample in a reagent (90 ° C.) mixed with phenol and 1,1,2,3-tetrachloroethane at a weight ratio of 6: 4 for 90 minutes in a concentration of 0.4 g / 100 ml, Ubbelohde Transfer to a viscometer and hold | maintained for 10 minutes in 30 degreeC thermostat, The fall second of the solution was calculated | required using a viscometer and an aspirator.

The falling seconds of the solvent was also determined in the same manner, and then the R.V.value and the I.V.value were calculated by the following equations (1) and (2).

Equation 1

R.V. = Number of drops of sample / number of drops of solvent

Equation 2

I.V. = 1/4 × [(R.V.-1) / C] + 3/4 × (lnR.V./C)

Where C represents the concentration of the sample in solution (g / 100ml).

(2) strength

Using Instron 5565 (Instron, USA), measurements were made under standard conditions (20 ° C., 65% relative humidity) under a sample length of 250 mm, tensile rate of 300 mm / min and 80 turns / m in accordance with ASTM D 885.

(3) density and crystallinity

Density is measured in a density gradient at 23 ° C.

Equation 3

Crystallinity (%) = ρc / ρ × (ρ-ρa) / (ρc-ρa)

Where p represents the density (g / cm ³ ) of the sample, and p and c represent 1.407 and 1.325 g / cm ³ as the density of the crystal and amorphous, respectively.

(4) birefringence

It is measured by the following method using a polarizing microscope equipped with a Berek compensator.

Place the polarizer and analyzer in a vertical position (→ orthogonal polarization).

Insert the compensator with the analyzer at a 45 ° angle (45 ° in the microscope N-S direction).

Place the sample on the stage and place it in a diagonal position (45 ° angle with the polarizer) (the black compensation band appears at this position).

• Rotate the micrometer screw of the compensator to the right and read the scale at the darkest point of the sample.

· Rotate in the opposite direction again and read the scale at the darkest point.

• Divide the difference between the two readings above by 2 to get the retardation (γ, nm) referring to the table made by the manufacturer.

Remove the compensator and analyzer and measure the sample thickness (d, nm) using an eyefilar micrometer.

Obtain the birefringence (△ n) of the sample by substituting the retardation and thickness measured in the following equation.

Δn = γ / d

(5) shrinkage

The sample was left at 20 ° C. and 65% relative humidity for at least 24 hours, and then weighed at 0.05 g / d to measure the length (L 0), followed by 30 minutes at 150 ° C. using a dry oven under no tension. After the treatment was taken out and left for 4 hours or more, a load corresponding to 0.05 g / d was measured to measure the length L, and the shrinkage ratio was calculated by the following equation (4).

Equation 4

ΔS (%) = (L0-L) / L0 × 100

(6) Intermediate Shinto

On the elongation S-S curve, the yarn measured elongation at a load corresponding to 4.5 g / d, and the treatment cord measured elongation at a load of 2.25 g / d.

(7) Dimensional stability

The dimensional stability of the treatment cord is defined as a high modulus at a given shrinkage as properties related to tire sidewall indentation (SWI) and handling, and E2.25 (elongation at 2.25 g / d) + FS (freedom) Shrinkage) is useful as a measure of dimensional stability for treated cords that have undergone different heat treatments, and the lower the better the dimensional stability.

Example 1

An antimony compound was added as a polymerization catalyst so that the residual amount of antimony metal in the polymer was 220 ppm to prepare a solid-state polymerized polyethylene-2,6-naphthalate chip having an intrinsic viscosity (I.V.) of 0.95 and a water content of 20 ppm. The produced chip was melt-spun at an ejection amount of 900 g / min and a temperature of 312 ° C so that the single yarn fineness of the final stretched yarn was 3.5 denier using an extruder.

The discharge yarn was then solidified by passing a heating hood of 100 mm in length directly below the nozzle and a radial in-out cooling zone of 800 mm in length (20 ° C., cooling air blowing with a wind speed of 0.5 m / sec) and then from the take-up roller 12. Oiling with a water-based spinning emulsion at a position of 1 m, wound at a spinning speed of 2500 m / min to make a non-drawn yarn, followed by three-step stretching of a total draw ratio of 2.0, heat setting at a temperature of 230 ° C. and relaxation of 2.0% It was then wound up to prepare a final stretched yarn of 1,500 denier.

Two strands of the drawn yarn were twisted at 390 tpm (twist / m), and then twisted and cabbled & plyed to prepare a cord yarn. After immersion in RFL), it dries for 180 seconds at a stretch of 150% at 150 ℃ in a drying zone for 180 seconds, and heat-fixes for 60 seconds with a 4.0% stretch at a temperature of 240 ℃ in a high temperature stretching zone. After set), it is immersed in the adhesive liquid (RFL) again in the secondary dipping tank and dried for 110 seconds at a temperature of 150 ℃, then heat set for 60 seconds at a temperature of 240 ℃ and -1.0% dipping (dipping) Prepare the treatment code.

The following table is evaluated by evaluation of the physical properties of the undrawn yarn, the drawn yarn and the treatment cord manufactured as described above

It is shown to 1-1 and 1-2.

Table 1-1

division Chip Intrinsic Viscosity (I.V.) Radiation Beam Temperature (℃) Unextended Occupational Viscosity Single yarn fineness (denier) Heating hood Distance between heating hood bottom and cooling device top (mm) Radial Out Out Cooling Spinning speed (m / min) Unpainted Shrine Length (mm) Temperature (℃) Section diameter (mm) Length (mm) Wind speed (m / s) Birefringence Crystallinity (%) Example 1 0.95 312 0.85 3.5 100 330 80 180 800 0.6 2500 0.04 6.1

Table 1-2

division Total draw ratio Drawing company Deep Code Intrinsic viscosity Strength (g / d) Majority (%) Elongation (%) Shrinkage (%) Single yarn fineness (d) Single yarn CV% O.P.U. (%) Strength (g / d) Majority (%) Shrinkage (%) E + S (%) Example 1 1.98 0.835 8.0 2.0 11.2 2.5 3.5 5.8 0.7 6.8 1.5 2.0 3.5

Examples 2-4

The chip is manufactured and radiated in the same manner as in Example 1, but the heating hood temperature and length, the distance between the heating hood bottom and the top of the cooling device, the diameter of the cooling device, the length of the cooling zone and the cooling wind speed, spinning speed, fineness and total smoke The mystery was changed as shown in Tables 2 and 3, and the discharge amount was properly adjusted according to the fineness of the final drawn yarn to prepare the final drawn yarn and the treated cord, and the physical properties thereof are shown in Table 3.

Comparative Examples 1 to 3

The chip was prepared and spun in the same manner as in Example 1, but was manufactured using a conventional circular hermetic cooling device without using a radial in-out flow cooling device, and the netability is shown in Table 3.

Comparative Examples 4 to 5

The chip is manufactured and radiated in the same manner as in Example 1, but the heating hood temperature and length, the distance between the heating hood bottom and the top of the cooling device, the diameter of the cooling device, the length of the cooling zone and the cooling wind speed, spinning speed, fineness and total smoke The mystery is changed as shown in Tables 2 and 3 below, and the method of applying the spinning emulsion is also known (Fig. 1: U.S. Patent No. 5,866,055: Radial in-out flow chiller 50 cm, 1m disc type emulsion Using the imparting device, impart an undiluted solution type emulsion to the stretched yarn (final adhesion amount is 0.5 to 1.0% by weight) to prepare the stretched yarn and treatment cord, and the properties thereof are shown in Table 3. It was.

Table 2

division Chip specific viscosity Radiation Beam Temperature (℃) Unextended Occupational Viscosity Single yarn fineness (denier) Heating hood Between bottom of heating hood and top of cooling device Radial-out cooling Spinning speed (m / min) Unpainted Shrine Length (mm) Temperature (℃) Section diameter (mm) Length (mm) Wind speed (m / s) Birefringence Crystallinity (%) Example 2 0.95 313 0.85 3.5 130 330 60 180 800 0.6 2500 0.06 5.8 Example 3 0.95 313 0.85 3.5 100 350 100 180 800 0.8 2100 0.05 5.2 Comparative Example 1 0.95 313 0.85 3.5 100 350 200 Circular Sealed Cooling System 0.8 2100 0.05 5.2 Comparative Example 2 0.95 313 0.85 3.5 100 350 100 0.3 2100 0.05 5.2 Comparative Example 3 0.95 313 0.85 3.5 100 350 80 0.5 3000 0.08 7.2 Example 4 0.95 313 0.85 3.5 100 350 60 200 800 0.8 2100 0.05 5.2 Comparative Example 4 0.95 313 0.85 3.5 100 330 80 180 800 0.6 2100 0.05 5.2 Comparative Example 5 0.95 313 0.85 3.5 100 330 80 180 800 0.6 2800 0.07 6.7

Table 3

division Total draw ratio Drawing company Deep Code Remarks Intrinsic viscosity Strength (g / d) Majority (%) Elongation (%) Shrinkage (%) Single yarn fineness (d) Single yarn (CV%) O.P.U. (%) Strength (g / d) Majority (%) Shrinkage (%) E + S (%) Example 2 1.99 0.85 8.0 2.9 10.3 2.3 3.5 5.8 0.7 6.8 4.1 2.4 6.5 Example 3 1.98 0.85 8.0 2.9 10.4 2.2 3.5 5.8 0.7 6.8 4.1 2.5 6.6 Comparative Example 1 1.95 0.85 7.4 2.9 10.6 2.5 3.5 7.8 0.7 6.8 4.5 2.5 7.0 × Comparative Example 2 1.95 0.85 7.4 2.9 10.0 3.0 3.5 7.2 0.7 6.8 4.5 3.5 8.0 × Comparative Example 3 1.85 0.85 6.9 2.3 12.0 2.0 3.5 7.4 0.7 6.2 4.5 2.2 6.7 × Example 4 1.98 0.85 8.0 2.6 10.5 2.2 3.5 5.7 0.7 6.8 4.0 2.3 6.3 Comparative Example 4 1.95 0.85 7.4 2.6 10.3 2.7 3.5 9.5 0.5 6.4 4.0 4.0 8.0 ×× Comparative Example 5 1.85 0.85 7.1 2.6 10.0 2.7 3.5 7.5 0.5 6.6 4.0 3.2 7.2

X: poor appearance

××: Appearance extremely poor (Dip Test meaningless)

Note: The total draw ratio was determined at 97% of the draw ratio that can be wound for 5 minutes.

Industrial polyethylene-2,6-naphthalate multifilament yarn manufactured according to the present invention has a high strength and low shrinkage with a strength of 7.5g / d or more and a shrinkage of 4.7% or less, thereby providing a processing code having high dimensional stability and strength. As a result, it can be usefully used for industrial purposes such as tires and industrial belts.

In addition, the present invention can produce an industrial polyethylene-2,6-naphthalate multifilament yarn having a single yarn fineness of 2.5 to 6 denier, a total fineness of 1,000 denier or more, and a high degree of homogeneity (CV%).

Claims (5)

(A) extruding a discharge yarn containing at least 85 mol% of ethylene terephthalate units and having an intrinsic viscosity in the range of 0.70 to 1.3 at a temperature of 290 to 330 ° C., (B) quenching and solidifying the molten yarn through a delayed cooling zone and then using a radial in-out flow cooling method; (C) imparting an emulsion at a distance of less than 2 m from the first winding roller; Winding the, (E) Polyethylene naphthalate fibers having the following physical properties, prepared by a method comprising the step of multi-stretching the wound yarn at a total draw ratio of 1.3 to 4.0 times. (1) intrinsic viscosity of 0.6 to 1.0, (2) strength of 7.5g / d or more, (3) elongation of 6% or more, (4) birefringence of 0.35 or more, (5) density of 1.355 to 1.375, (6) filament cross section CV% is 6.0% or less and (7) 1 to 3% shrinkage The method of claim 1, A process for producing industrial polyethylene-2,6-naphthalate multifilament yarns, characterized by oiling using an aqueous emulsion emulsion. The method of claim 1, A method for producing industrial polyethylene-2,6-naphthalate filament yarn characterized by using a radial in-out flow cooling method having the following characteristics. (1) Cross section diameter (R) of the cooling device 12 cm or more (2) At least 60cm in length of cooling zone (3) Cooling air temperature 15 ~ 60 ℃ (4) Cooling air speed 0.4-1.2 m / s The method of claim 1, Single yarn fineness of the drawn yarn is 2.5 to 8 denier and total fineness of 1,000 denier or more method for producing industrial polyethylene-2,6-naphthalate multifilament yarn. The method of claim 1, Industrial polyethylene-2,6-na characterized by dimensional stability (E2.25 + FS) of 2 to 5.0% and strength of 6.0 to 8.0 g / d in the treatment cords prepared by RFL (Resorcynol- Formalin- Latex) treatment Method for producing phthalate multifilament yarns (E2.25; elongation at 2.25 g / d, FS; free shrinkage).