KR20110078414A - Process for preparing polyester multifilament for tire cord - Google Patents

Abstract

PURPOSE: A method of manufacturing high intensity polyester multi filament for tire is provided to easily secure yarn strength in the low drawing ratio and to solve problems of yarn shrinkage ratio increase and shape stability decrease by having a bigger hole diameter of nozzle than existing ones. CONSTITUTION: The polyethylene terephthalate multifilament is manufactured as follows. The polyethylene terephthalate multifilament is obtained by spinning a polyethylene terephthalate chip having an inherent viscosity of 1.0~1.2. The polyethylene terephthalate chip is melted through an extruder. The melted polymer is extruded through a nozzle having 100-500 holes, and passes through a hood heater. An oil ring focuses after cooling with air.

Description

Process for preparing polyester multifilament for tire cord

The multifilament fiber according to the present invention has high strength, high modulus and low elongation, and can be applied to the production of industrial high strength polyester fiber used as a material for tire cords, industrial ropes, civil reinforcement, webbing or seat belts. have.

A useful conventional method for increasing the strength of polyester fibers used for industrial purposes is to melt high-viscosity chips with an intrinsic viscosity of 1.0 or higher, and then melt and solidify the melted polymer by raising the temperature to 300 ° C. The unstretched yarn obtained by winding at a low speed was directly stretched to a stretching ratio of 5.0 or more in one and two stages, and then relaxed and wound. At this time, the orientation degree at the time of non-expansion was lowered by low-speed winding, the drawing of high magnification was provided, and the high strength characteristic was obtained. The conventional method as described above is characterized in that a high magnification is stretched after minimizing the orientation of the untwisted yarn by appropriately adjusting the temperatures of the heating hood and the cooling wind. When using a conventional spinning technique to increase the draw ratio to obtain a higher strength of the fiber, due to the high temperature of the heating hood during spinning, the viscosity during spinning, shrinkage of the yarn due to high magnification stretching and shape stability is poor. Due to the high process ratio and high number of spinning yarns caused by the high rate of stretching, pin yarn is generated, resulting in poor post-processability.

The present invention can maintain the draft more than 800 by spinning the hole diameter of the nozzle than the existing, according to the increased orientation of the undrawn yarn, it is easy to secure the yarn even at low draw ratio, increase the shrinkage of the yarn which is a problem at high magnification stretching And it can solve the problem that the shape stability is lowered.

According to a preferred embodiment of the present invention, in the method for producing a polyethylene terephthalate multifilament obtained by spinning a polyethylene terephthalate chip having an intrinsic viscosity of 1.0 to 1.2, the polyetherene terephthalate chip is melted through an extrudate Extruded molten polymer through a nozzle with a diameter of 0.8 to 1.2 mm and an odd number of 100 to 500, passed through a hood heater, cooled with air, concentrated and oiled, and directly below the nozzle and the speed of GR 1 (8) Provided is a method for producing a polyethylene terephthalate multifilament characterized in that the draft drawn in the multi-stage passing through the roller roller at 800 to 1100 and the final winding speed is 5000 to 6000 m / min.

According to another suitable embodiment of the present invention, the fineness of the polyethylene terephthalate multifilament is preferably 500 to 3000 denier.

According to another suitable embodiment of the present invention, the strength of the polyethylene terephthalate multifilament is 9.5 g / d or more.

According to another suitable embodiment of the present invention, there is provided an industrial product selected from the group consisting of a tire cord, an industrial rope, a civil reinforcement, a webbing and a seat belt comprising a high strength polyethylene terephthalate multifilament manufactured by the above method. To provide.

The present invention maintains the inherent physical properties of the polyester chip itself as much as possible and the present invention can maintain the draft during spinning by making the hole diameter of the nozzle larger than the conventional, excellent spinning workability and high modulus due to the low magnification stretching It is possible to manufacture industrial super strength polyester yarn which is useful for industrial rope, civil reinforcement, webbing, seat belt, etc., which have high strength and low elongation characteristics.

The present invention provides that polyethylene terephthalate polymers for the production of polyethylene terephthalate may contain at least 85 mole% of ethylene terephthalate units but may optionally comprise only ethylene terephthalate units.

Optionally, the polyethylene terephthalate may comprise, as copolymer units, small units derived from ethylene glycol and terephthalene dicarboxylic acid or derivatives thereof and one or more ester-forming components. Examples of other ester forming components copolymerizable with polyethylene terephthalate 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 terephthalic acid (TPA) and ethylene glycol raw materials are melt mixed in a ratio of 2.0 to 2.3 in the prepared polyethylene terephthalate chip, and the melt mixture is transesterified and axially-polymerized to produce low chips having an intrinsic viscosity of 0.60 to 0.70. raw chips). The low chip is then subjected to solid phase polymerization to have an intrinsic viscosity of 1.0 to 1.2 and a moisture content of 30 ppm or less under a temperature of 240 to 260 ° C and a vacuum.

If the intrinsic viscosity of the low chip is lower than 1.0, the intrinsic viscosity of the final drawn yarn is lowered, so that it is impossible to exhibit high strength as a treatment cord after heat treatment. It causes a lot of filament cuts during stretching, which results in poor stretching workability. In addition, if the moisture content of the chip exceeds 30ppm may cause hydrolysis during melt spinning.

Optionally, an antimony compound, preferably antimony trioxide, may be added as a polymerization catalyst in the course of the polycondensation reaction so that the amount of antimony metal remaining in the final polymer is 180 to 300 ppm. If the residual amount is less than 180 ppm, the polymerization reaction rate is lowered, and the polymerization efficiency is lowered. If the amount is more than 300 ppm, more than necessary antimony metal acts as a foreign material, which may lower the radio-stretching workability.

Polyethylene terephthalate chip produced in this way is fiberized through the process shown in FIG.

Referring to FIG. 1, the polyethylene terephthalate chip has a spinning temperature of 290 to 310 ° C. and a spinning draft of 800 to 1100 through an extrude 1, a gear pump 2, a nozzle 3 and a heating device 4. The low temperature melt spinning at a ratio (linear velocity on the first winding roller / linear velocity in the nozzle) prevents a decrease in the viscosity of the polymer by pyrolysis and hydrolysis. If the draft ratio is less than 800, the uniformity of the filament cross section worsens, and the drawing workability is significantly reduced. On the other hand, if the draft ratio exceeds 1100, the filament breakage occurs during spinning, which makes normal yarn production difficult.

The produced melt discharger is quenched and solidified through the cooling zones 5 and 6 and, if necessary, the distance to the start point of the cooling zones 5 and 6 immediately below the nozzle 3, ie the length L section of the hood. A short heating device 4 can be installed.

The length L section of the hood becomes a delay cooling zone or heating zone and has a length of 50 to 250 mm and a temperature of 250 to 400 ° C. (air contact surface temperature).

Depending on the method of blowing cooling air in the cooling zones 5 and 6, open quenching, circular closed quenching and radial outflow quenching may be applied. It is not limited. The discharged yarns solidified through the cooling zones 5 and 6 are oil ringed by 0.5 to 1.0% by the oil imparting device 7 to become unburned yarns.

Undrawn yarn is passed through a series of drawing rollers (8), (9), (10), (11), and (12) by a spin draw method to achieve a total draw ratio of 2.0 or more, preferably 2.0 to 2.5 times. It extends and is obtained as the final stretched yarn 13 by the winding roller.

In the stretching process, the undrawn yarn is three-stage stretched, and each stretching temperature is lower than 95 ° C., which is the glass transition temperature of the undrawn yarn. If the stretching temperature is lower than the glass transition temperature, the stretchability is inferior, and if the stretching temperature is higher than 95 ° C, crystallization during the stretching proceeds rapidly, making three-stage stretching difficult.

Making the distance between the nozzle and the top of the cooling unit as small as possible during spinning makes it advantageous to have high strength in the final stretched yarn. If the distance from the bottom of the heater to the bottom of the heater is 50 mm or less during spinning, the distance from the bottom of the heater to the bottom of the heater is 100 mm), or when the distance between the lower end of the heating device and the upper end of the cooling device is 50 to 150 mm, non-uniformity of undrawn yarn is generated to a considerable level, which makes it difficult to draw normal physical properties.

The stretched polyethylene terephthalate fiber thus prepared has (1) an inherent viscosity of 0.8 to 1.0; (2) a strength of at least 9.5 g / d; (3) at least 10% elongation; And (4) shrinkage of 3 to 5%.

The physical property evaluation of an Example and a comparative example was measured or evaluated as follows.

1) Intrinsic viscosity (I.V.)

After dissolving 0.1 g of the sample in a reagent (90 ° C.) mixed with phenol and 1,1,2,2-tetrachloroethanol 6: 4 (weight ratio) for 90 minutes, transfer to a Ubbelohde viscometer and place it in a 30 ° C. thermostat. The solution is held for 10 minutes at, and the drop seconds of the solution are obtained by using a viscometer and an aspirator. The number of seconds of falling of the solvent can also be obtained by the following equations obtained from the above equations. The value was calculated.

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

I.V. = 1/4 × (R.V.-1) / concentration + 3/4 × (In R.V./concentration)

2) Measuring method of modulus and elongation of multifilament

After leaving the yarn in a standard condition, that is, a constant temperature and humidity chamber at a temperature of 25 ° C. and a relative humidity of 65% for 24 hours, the sample is measured by a tensile tester using the ASTM 2256 method.

3) Dry heat shrinkage (%, Shrinkage) and ES value

After standing at 25 ° C. and 65% RH for 24 hours, the length (L ₀ ) measured at a static load of 0.05 g / d and the length (L ₁ ) after treatment at a static load of 0.05 g / d for 30 minutes at 150 ° C. Dry heat shrinkage was measured using the ratio. Building contraction rate (S) can be expressed as follows.

S (%) = [(L ₀ -L ₁ ) / L _{0 ]} × 100

Elongation under a certain load is referred to as the median elongation (E) in the present invention, 'S' refers to the dry heat shrinkage, the sum of the median elongation (E) and dry heat shrinkage (S) is expressed as 'ES'.

ES = median elongation (%) + dry heat shrinkage (%)

4) radial draft

The speed of GR 1 (8) was calculated as the value divided by the speed of the polyethylene terephthalate polymer directly under the nozzle.

5) elongation ratio

The speed of GR 4 (11) divided by the speed of GR 1 (8).

Example 1

A solid-state polymerized polyethylene terephthalate chip having 1.15 intrinsic viscosity (I.V.) containing manganese and antimony metals of 40 and 220 ppm, 1.8 manganese / phosphorus content ratio and 20 ppm moisture content was prepared. The prepared chip was melt spun using an extruder at a discharge rate of 900 g / min and a spinning draft ratio of Table 1 at a temperature of 290 ° C. At this time, a static mixer having three units was installed in the polymer conduit of the pack to evenly mix the melt-spun polymer. Subsequently, the discharged yarn is solidified by passing through a heating zone of 100 mm in length (atmosphere temperature 320 ° C.) and a cooling zone of 500 mm in length (20 ° C., cooling air blowing with a wind speed of 0.5 m / sec) immediately after the nozzle, and then oiled with spinning oil. It was. The unstretched or POY yarns were wound at a spinning speed of 2,300 m / min, the first stage stretched 1.6 times at 60 ° C, the second stage stretched 1.2 times at 60 ° C, and the third stage stretched 1.3 times at 75 ° C. The final stretched yarn (yarn) of 1500 denier was carried out, heat-fixed at 230 ° C., relaxed 3%, and then wound.

The physical properties of the drawn yarn thus obtained were evaluated and shown in Table 2 below.

[Examples 2-3 and Comparative Examples 1-3]

A stretch yarn was prepared by performing experiments in the same manner as in Example 1 while changing the inherent viscosity of the chip, the odd number of spinnerets, the spinning speed, and the winding speed as shown in Table 1 below.

Evaluation of the drawn yarn physical properties thus prepared is shown in Table 2 below.

TABLE 1

TABLE 2

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1 schematically illustrates a process for producing a polyethylene terephthalate multifilament according to the present invention.

Claims (4)

In the method for producing a polyethylene terephthalate multifilament obtained by spinning a polyethylene terephthalate chip having an intrinsic viscosity of 1.0 to 1.2, The polyetherene terephthalate chip is melted through an extrudate, the molten polymer is extruded through a nozzle having a diameter of 0.8 to 1.2 mm and an odd number of 100 to 500, passed through a hood heater, cooled by air, and then focused. The method of producing a polyethylene terephthalate multifilament characterized in that the oiling, the spinning draft is stretched in multiple stages through the rollers at 800 to 1100 and the final winding speed is 5000 to 6000 m / min. The method of claim 1, The fineness of the polyethylene terephthalate multifilament is 500 to 3000 denier manufacturing method of polyethylene terephthalate multifilament. The method of claim 1, A method for producing a polyethylene terephthalate multifilament, characterized in that the strength of the polyethylene terephthalate multifilament is 9.5 g / d or more. An industrial product selected from the group consisting of tire cords, industrial ropes, civil engineering reinforcements, webbings and seat belts comprising a high strength polyethylene terephthalate multifilament made by the method of claim 1.

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