KR101551425B1 - High tenacity polyester filament and process for preparing polyester tire cord - Google Patents

Abstract

The present invention relates to a process for producing a melt-extruded polyether terephthalate chip having an intrinsic viscosity of 1.0 to 1.2 through melting extruder and extruding molten polymer through a nozzle having a diameter of 0.8 to 1.2 mm and an odd number of 100 to 500, 800 to 1100, stretched in multiple stages to produce polyethylene terephthalate, and the multifilament is made into a raw cord by applying lower and upper fines, and the raw cord is immersed in a dipping solution The present invention provides a method of producing a polyethylene terephthalate multifilament tire cord. The tire cord manufactured according to the present invention has almost no high modulus, high strength, low output, and permanent deformation, and thus can be used for tire, geogrid, industrial webbing, seat belt and the like.

Polyethylene terephthalate, tire cord, industrial spray, high strength, toughness, multifilament

Description

TECHNICAL FIELD [0001] The present invention relates to a high tenacity polyester filament and a process for preparing a polyester tire cord,

The polyester multifilament tire cord according to the present invention has high strength and high modulus characteristics and can be applied to industrial products used as a material for tires, industrial ropes, civil engineering reinforcements, webbing or seat belts.

A conventional method useful for increasing the strength of polyester fibers used for industrial purposes is to melt a highly viscous chip having an intrinsic viscosity of 1.0 or higher and then melt the polymer by raising the temperature of the molten polymer sufficiently to 300 ° C and then solidify it. Or less, and then unwinding the undrawn yarn obtained by direct winding at a draw ratio of 5.0 or more in a first stage and a second stage, followed by relaxation and winding. At this time, low-speed winding lowers the degree of orientation in the unstretched state and gives high-strength stretching to obtain high strength characteristics. The conventional method as described above is characterized in that the temperature of the heating hood and the cooling wind is appropriately adjusted to minimize the degree of orientation of the unstable yarn, followed by stretching at a high magnification. When the stretching magnification is increased to obtain fibers having higher strength by using the conventional spinning technique, the viscosity at the time of spinning, the increase in the shrinkage ratio of the yarn due to high-rate stretching, and the shape stability are lowered due to the high temperature of the heating hood during spinning. A large number of finishing threads and finishing problems occur due to a large number of spinning yarns caused by high-ratio stretching, resulting in poor post-processability.

By increasing the hole diameter of the nozzle in the present invention, it is possible to maintain the draft of 800 or more during the spinning, thereby increasing the degree of orientation of the undrawn yarn and thus securing the strength of the yarn even at a low stretching ratio and increasing the shrinking rate of the yarn And the problem that the shape stability is lowered can be solved.

According to a preferred embodiment of the present invention, a polyether terephthalate chip having an intrinsic viscosity of 1.0 to 1.2 is melted through an extruder and melted through a nozzle having a diameter of 0.8 to 1.2 mm and an odd number of 100 to 500 Extruded and extruded at 800 to 1100 through a godet roller to stretch the multifilament in multiple stages to produce polyethylene terephthalate. The multifilaments were then subjected to underfloor and topping to produce a raw cord, which was immersed in a dipping solution The present invention also provides a method for producing a polyethylene terephthalate multifilament tire cord.

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

According to another preferred embodiment of the present invention, the strength of the polyethylene terephthalate multifilament tire cord is 8.0 g / d or more.

According to another preferred embodiment of the present invention, there is provided an industrial product selected from the group consisting of tire cord, industrial rope, civil engineering reinforcement, webbing and seat belt comprising high tenacity polyethylene terephthalate multifilament prepared by the above method do.

In the present invention, the inherent physical properties of the polyester chip itself are maintained to the maximum, and the present invention can maintain the draft of 800 or more during spinning by making the hole diameter of the nozzle larger than conventional ones, High strength polyester yarns useful for tires, industrial ropes, civil engineering reinforcements, webbing, seat belts, and the like having high strength, low output characteristics can be produced.

The polyethylene terephthalate polymer for the production of polyethylene terephthalate yarns of the present invention may contain at least 85 mol% of ethylene terephthalate units, but may optionally contain only ethylene terephthalate units.

Optionally, the polyethylene terephthalate may comprise a small amount of units derived from ethylene glycol and terephthalenedicarboxylic acid or derivatives thereof and one or more ester-forming components as copolymer units. Examples of other ester forming components that can be copolymerized with the polyethylene terephthalate unit include glycols such as 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol and the like, and glycols such as terephthalic acid, isophthalic acid, hexahydroterephthalic acid, And dicarboxylic acids such as dicarboxylic acid, bibenzoic acid, adipic acid, sebacic acid, and azelaic acid.

The terephthalic acid (TPA) and the ethylene glycol raw material are melt-mixed in the ratio of 2.0 to 2.3 to the polyethylene terephthalate chip thus produced, and the molten mixture is subjected to an ester exchange reaction and a condensation polymerization to obtain a low- (raw chips). Subsequently, the low chip is subjected to solid phase polymerization so as to have an intrinsic viscosity of 1.0 to 1.2 and a water content of 30 ppm or less at a temperature of 240 to 260 DEG C and under vacuum.

If the intrinsic viscosity of the raw chips is lower than 1.0, the intrinsic viscosity of the final stretch yarn is lowered and the high strength can not be exhibited as a treated cord after heat treatment. On the other hand, if the intrinsic viscosity of the chips is higher than 1.20, the radiation tension is excessively increased, A lot of filament cuts are generated during stretching and the drawing workability is poor. In addition, when the moisture content of the chips exceeds 30 ppm, hydrolysis may be induced during melt spinning.

Alternatively, an antimony compound, preferably antimony trioxide, may be added as a polymerization catalyst in the condensation polymerization reaction so that the residual amount of antimony metal in the final polymer is 180 to 300 ppm. When the residual amount is less than 180 ppm, the polymerization reaction rate is slowed and the polymerization efficiency is lowered. When the residual amount is more than 300 ppm, unnecessary antimony metal acts as a foreign substance and the radiation-drawing workability may be deteriorated.

The polyethylene terephthalate chip produced by this method is fiberized through the process shown in Fig.

1, a polyethylene terephthalate chip is fed through an extruder 1, a gear pump 2, a nozzle 3 and a heating device 4 at a spinning temperature of 290 to 310 占 폚 and a radiation draft of 800 to 1100 (The linear velocity on the first winding roller / the linear velocity on the nozzle) to prevent the degradation of the viscosity of the polymer due to pyrolysis and hydrolysis. If the radiation draft ratio is less than 800, the uniformity of the filament cross section becomes poor and the drawing workability is significantly lowered. On the other hand, if it exceeds 1100, filament breakage occurs during spinning, and normal yarn production becomes difficult.

The produced melt release yarn passes through the cooling zones 5 and 6 and is quenched and solidified and if necessary the distance to the starting point of the cooling zones 5 and 6 immediately below the nozzle 3, A short heating device 4 may be installed.

The length (L) section of the hood becomes a delayed 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).

The open quenching method, the circular closed quenching method and the radial outflow quenching method can be applied according to the method of blowing the cooling air in the cooling zones 5 and 6, But is not limited to. The solidified discharged yarn passing through the cooling zones 5, 6 is oiled to 0.5 to 1.0% by the emulsion applying device 7 and becomes unleaded.

The unstretched yarn is passed through a series of stretching rollers 8, 9, 10, 11 and 12 by a spin draw method to have a total draw ratio of 2.0 times or more, preferably 2.0 to 2.5 times And is obtained as a final drawn yarn 13 on the winding roller.

In the stretching step, the unstretched yarn is stretched in three stages, and each stretching temperature is lower than 95 占 폚, which is the glass transition temperature of the non-stretched yarn. If the stretching temperature is lower than the glass transition temperature, the stretching property is lowered. If the stretching temperature is higher than 95 占 폚, the crystallization during the stretching rapidly proceeds and the 3-stage stretching becomes difficult.

Making the distance between the nozzle and the top of the cooling zone as small as possible during spinning makes it advantageous to have high strength in the final drawn yarn. If the distance from the bottom of the nozzle to the bottom of the heating device is less than 50 mm (actually, since there is an emission block having a length of about 50 mm directly under the nozzle, the distance from the bottom of the nozzle to the bottom of the heating device, 100 mm), or if the distance between the lower part of the heating device and the upper part of the cooling device deviates from 50 to 150 mm, non-uniformity of the non-drawn yarn is generated to a considerable level,

The drawn polyethylene terephthalate fiber thus produced has (1) an intrinsic viscosity of 0.8 to 1.0; (2) a strength of at least 9.5 g / d; (3) elongation of 10% or more; And (4) a shrinkage percentage of 1.5 to 5.0%.

The method according to the present invention for producing a hybrid dipped cord using the polyethylene terephthalate fiber produced comprises the step of applying a twist to the cord in a previous step to produce a raw cord (twisting process).

In the manufacturing method according to the present invention, the physical properties such as the strength of the cord, the tensile strength and the fatigue resistance of the cord are changed according to the degree of twisting (number of years) given to the polyethylene terephthalate fiber at the lower or upper side. Generally, when the twist is high, the strength decreases, and the midline and the twist tend to increase. My fatigue also shows a tendency to improve with increasing kinks. The polyethylene terephthalate tire cord prepared according to the present invention was manufactured so as to have a softener of 300/300 TPM to 500/500 TPM at the same time. The upper and lower edges are made to have the same numerical value in order to maximize the physical property expression by making the manufactured tire cord easy to maintain a straight line without showing rotation or twist. If it is less than 300/300 TPM, the output of the live cord is reduced and the fatigue resistance is likely to decrease. On the other hand, if it exceeds 500/500 TPM, the strength drop is too large to be suitable for tire cords.

The manufactured raw cord is woven using a weaving machine and the obtained fabric is immersed and cured in the dipping solution to produce a dip cord for a tire cord having a resin layer on the surface of the raw cord ).

In the manufacturing process according to the present invention, dipping refers to impregnating a resin layer called RFL (Resorcinol-Formaline-Latex) on the surface of the fiber. The dipping process is carried out in order to improve the disadvantage of the tire cord fabric which has poor adhesion to rubber.

In the present invention, an adhesive liquid for bonding a polyethylene terephthalate cord and a rubber can be produced by the following method.

Method of manufacturing adhesive liquid

29.4 wt% resorcinol 45.6 parts by weight;

255.5 parts by weight of distilled water;

37% formalin 20 parts by weight; And

10 wt% sodium hydroxide 3.8 parts by weight

Is prepared and reacted with stirring at 25 ° C for 5 hours, and the following components are added.

40 wt% VP-latex 300 parts by weight

Distilled water 129 parts by weight

28% ammonia water 23.8 parts by weight.

After the ingredients are added, they are aged at 25 ° C for 20 hours to maintain a solid content concentration of 19.05%.

After drying the polyethylene terephthalate cord, the adhesive liquid is attached. A stretch of 1 to 5% is required to adjust the adhesion amount of the adhesive liquid, and preferably 2 to 4% of the elongation can be achieved. If the elongation percentage is too high, the adhesion amount of the adhesive liquid can be adjusted but the yield is reduced and the fatigue resistance is reduced as a result. On the other hand, if the elongation percentage is too low, for example, if it is lowered to less than 1%, it is impossible to control the DPU (Defect Per Unit) due to penetration of the dipping solution into the polyhexamethylene adipamide cord.

The adhesion amount of the adhesive is preferably 4 to 6% based on the weight of the fibers based on the solid content. After the adhesive liquid is adhered, the polyethylene terephthalate dip cord is dried at 120 to 150 ° C. The drying time may be from 180 seconds to 220 seconds, and the drying process is performed with the polyethylene terephthalate dip cord stretched to about 1 to 2%. If the elongation ratio is low, the tensile strength and elongation of the cord may increase, which may result in a property that is difficult to apply to a tire cord. On the other hand, if the elongation ratio is more than 2%, the level of the medium is adequate but the turnover is too small and fatigue can be reduced.

After drying, heat treatment is performed at a temperature range of 130 to 170 캜. The elongation percentage during the heat treatment is maintained between -2 and 0%, and the heat treatment time is suitably between 50 and 90 seconds. If the heat treatment is performed for less than 50 seconds, the reaction time of the adhesive solution is insufficient and the adhesive force is lowered. Otherwise, if the heat treatment is performed for 90 seconds or more, the hardness of the adhesive solution is increased and the fatigue resistance of the cord is decreased .

The polyethylene terephthalate dip cord manufactured through such a process is applied as a carcass ply or a cap ply and is used for manufacturing a tire for a passenger car.

The physical properties of Examples and Comparative Examples were measured or evaluated as follows.

1) Intrinsic viscosity (I.V.)

0.1 g of the sample was dissolved in a reagent (90 ° C) mixed with phenol and 1,1,2,2-tetrachloroethanol 6: 4 (weight ratio) for 90 minutes, transferred to a Ubbelohde viscometer, For 10 minutes, and use a viscometer and an aspirator to determine the number of drops of the solution. The number of drops of the solvent The RV value and I.V. Values were calculated.

R.V. = Sample falling water / solvent falling water water

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

2) How to measure the modulus and strength of multifilament

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

3) Dry Heat Shrinkage (%, Shrinkage) and ES Value

On the 25 ℃, 65% RH for 24 hours, allowed to stand, is measured in the way of a 0.05g / d static load (L ₀₎ and a 150 ℃ after treatment in static load for 30 minutes. 0.05g / d length (L ₁₎ The dry heat shrinkage ratio was measured. The construction shrinkage ratio S can be expressed by the following equation.

S (%) = [(L ₀ - L ₁ ) / L _{0 ]} × 100

The elongation under a constant load is referred to as an intermediate elongation (E) in the present invention, and 'S' means the dry heat shrinkage ratio, and the sum of the elongation modulus (E) and dry heat shrinkage ratio (S) is represented by 'ES'.

ES = elongation at break (%) + dry heat shrinkage (%)

4) Radiation draft

The rate of GR 1 (8) was calculated by dividing by the speed of the polyethylene terephthalate polymer underneath the nozzle.

5) Pulling Ratio

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

6) My fatigue

The fatigue resistance was measured by measuring the residual strength after fatigue test using a belt fatigue tester commonly used in fatigue testing of tire cords. The fatigue test conditions were 40 ° C, 70 kg of load, and 34.58% of compression, and after the fatigue test, the rubber was swelled by immersing in a tetrachlorethylene solution for 24 hours, . The residual strength was measured by a conventional tensile strength tester after drying at 107 占 폚 for 2 hours in accordance with the above method (a).

7) Dry Heat Shrinkage Force (N, Shrinkage Force)

The maximum value (F) of the generated stress after treatment for 2 minutes at a constant load (F ') of 0.05 g / d using a Testrite apparatus after being left at 25 ° C. and 65% RH for 24 hours . The dry heat shrinkage force (SF) can be expressed by the following formula.

SF (N) = F '- F.

[Example 1]

A solid state polymerized polyethylene terephthalate chip having an intrinsic viscosity (I.V.) of 1.15, a manganese / phosphorus ratio of 1.8, and a water content of 20 ppm, containing 40 and 220 ppm of manganese and antimony metals, respectively, was prepared. The prepared chip was melt-spun using an extruder at a discharge temperature of 290 DEG C at a discharge rate of 900 g / min and a radiation draft ratio shown in Table 1. [ At this time, a static mixer having three units was installed in the polymer conduit of the pack to uniformly mix the melt-spun polymer. Then, the discharged yarn was solidified by passing through a heating zone (atmosphere temperature: 320 ° C) of 100 mm directly below the nozzle and a cooling zone (blowing of cooling air having a wind velocity of 0.5 m / sec at 20 ° C) of 500 mm in length, Respectively. The unstretched or POY yarn was wound at a spinning speed of 2,300 m / min. The first-stage stretching was carried out at a temperature of 60 ° C at 1.6 times, the second-stage stretching at a temperature of 60 ° C was carried out at 1.2 times, , Annealed at 230 ° C, relaxed by 3%, and then wound to produce a final drawn yarn (yarn) of 1500 denier.

The prepared cord yarn was wound up and down at 370 turns / m to prepare a cord yarn. The cord yarn was immersed in an adhesive solution (PCP resin + RFL) in a dipping tank, followed by 2.0% And dried for 150 seconds in a hot stretching zone at a temperature of 240 DEG C for 150 seconds and then immersed in RFL and then dried at 170 DEG C for 100 seconds and heat set at 240 DEG C for 4 seconds under 4% .

The physical properties of the thus-prepared drawn yarn and treated cord were evaluated and are shown in Table 2 below.

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

Experiments were conducted in the same manner as in Example 1 while changing the intrinsic viscosity of the chips, the number of spinnerets, the spinning speed, and the winding speed as shown in Table 1 below to prepare a drawn yarn and treated cord.

The physical properties of the thus-prepared drawn yarn and treated cord were evaluated and are shown in Table 2 below.

 ■: Appearance defect, ■■: Appearance is extremely bad, meaning no manufacturing of treated cord.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a process for producing a polyethylene terephthalate multifilament according to the present invention.

Claims (4)

A polyether terephthalate chip having an intrinsic viscosity of 1.0 to 1.2 is melted through an extruder and 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, A process for producing a polyethylene terephthalate film, comprising the steps of: preparing a polyethylene terephthalate by stretching in multiple stages through a Lochgodet roller to produce a multifilament with a raw cord by applying lower and upper flames to the multifilament, Method for manufacturing terephthalate multifilament tire cords. The method according to claim 1, Wherein the polyethylene terephthalate multifilament has a fineness of 500 to 3,000 denier. 2. A method for producing a polyethylene terephthalate multifilament tire cord, The method according to claim 1, Wherein the tensile strength of the polyethylene terephthalate multifilament cord is 8.0 g / d or more. An industrial product selected from the group consisting of a tire comprising polyethylene terephthalate multifilament tire cords produced by the method of claim 1, industrial ropes, civil engineering reinforcements, webbing and seat belts.

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