KR20170082891A - Process for preparing polyester dip cord for motercycle - Google Patents

Abstract

TECHNICAL FIELD The present invention relates to a tire cord for bias tires used in motorcycles, agricultural applications, and the like, and relates to an adhesive force of a polyether terephthalate cord having a price competitiveness for replacing nylon 6 and nylon 66 which have been conventionally used as bias tire cords And a method for improving heat resistance. The technical feature of the present invention is to reduce the compactness of the raw cord by controlling the life span of the raw cord to 420 TPM to 440 TPM to increase the content of the deepening cord so that the content of the deepening cord can be increased so that the polyethylene terephthalate Deep code is provided. The fatigue resistance of the polyethylene terephthalate dip cord manufactured by the method of the present invention measured at 40 DEG C under a load of 80 kg and 42,000 cycles is 96% or more.

Description

Technical Field [0001] The present invention relates to a process for preparing a polyethylene terephthalate dip cord for a motorcycle tire having excellent fatigue resistance,

The present invention relates to a yarn of polyethylene terephthalate for a tire cord of a bias tire and a dipped cord using the yarn, more particularly, to a method of regulating the denseness of a raw cord by controlling the softness of the raw cord, To a polyethylene terephthalate dip cord for motorcycles having an excellent adhesive strength and fatigue resistance at the same time.

Bias tires used in motorcycles, agriculture, etc., use Nylon 6 and Nylon 66, which are highly resistant to deformation and heat, and have excellent adhesion and durability. 'Polyethylene terephthalate', a typical polyester used for automobile tire cords, was first industrialized by ICI in 1949 for fibers, and grown as one of the three major synthetic fibers with nylon and acrylic fibers. In the non-textile sector, , High heat resistance, transparency, gas barrier properties, stretch processability, processing characteristics, and price competitiveness. Particularly, the polyethylene terephthalate fiber used for a tire cord is advantageous in terms of economical efficiency and high strength, but has a disadvantage that its form stability is poor. However, as the demand for reduction of production costs has expanded, interest in application of polyethylene terephthalate cords to replace high-speed tires for motorcycles and large-scale agricultural tires has been increasing. Therefore, SS curve behavior similar to nylon cord, In particular, it is urgent to develop a polyethylene terephthalate cord having a performance equivalent to or better than that of nylon.

The main object of the present invention is to provide a polyethylene terephthalate dip cord for motorcycles having excellent fatigue resistance.

 In order to accomplish the above object, the present invention provides a method for producing a polyethylene terephthalate, comprising: melting polyethylene terephthalate containing 85 mol% or more of ethylene terephthalate units and extruding the polyethylene terephthalate while passing through a nozzle to form a discharged yarn; Radiating the discharged yarn to form an undrawn yarn; Stretching the undrawn yarn through a stretching roller to produce a yarn; Spinning the yarn up and down at 420 to 440 TPM; And dipping the yarn woven through the weaving step in a dipping solution, followed by drying, stretching and heat setting to produce a dipping cord to maintain a dipping amount of at least 5% by weight based on the total weight of the dipping cord. A method for producing a polyethylene terephthalate tire cord for a tire.

At this time, if the life span of the raw cord is less than 420 TPM, the fatigue resistance of the dip cord is deteriorated. If it exceeds 440 TPM, the adhesion strength with the rubber is insufficient. If DPU (Dip Pick Up) is less than 5%, the fatigue is low.

Also, the fatigue resistance of the polyethylene terephthalate dip cord manufactured by the above method was 96% or more as measured at 40 DEG C, 80 kg load, and 42,000 cycle.

Further, the polyethylene terephthalate tire cord produced by the above method has an E-S value of 13 or less and a shrinkage ratio of 1.5% or less.

The tire cord using the yarn manufactured according to the present invention has the same or similar performance as the nylon 66 and has the fatigue resistance and the adhesive strength so that the range and market of the polyethylene terephthalate cord replacing the nylon 66 used in the bias tire for the motorcycle Can be enlarged.

1 shows a spinning and drawing process of a polyethylene terephthalate yarn according to the present invention.

Hereinafter, the present invention will be described in detail.

The present invention provides a polyethylene terephthalate fiber, a method for producing the fiber, and a tire cord comprising the same.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the configuration and operation of embodiments of the present invention will be described in detail with reference to the accompanying drawings.

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.

Terephthalic acid (TPA) and ethylene glycol raw material are melt-mixed in a ratio of 2.0 to 2.3 to the polyethylene terephthalate chip thus produced, and the molten mixture is transesterified and condensation-polymerized to form a low chip (intrinsic viscosity: 0.60 to 0.70 level raw chip). 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 spinning draft of 1200 to 1500 (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 1200, the uniformity of the filament cross section is deteriorated, and the drawing workability is significantly lowered. On the other hand, if the draft ratio is more than 1500, filament breakage occurs during spinning, and normal yarn production becomes difficult.

The polyether terephthalate chip having an intrinsic viscosity of 1.0 to 1.2 is preferably extruded through a nozzle having a diameter of 1.0 to 1.4 mm and an odd number of 300 to 500. At this time, if the diameter of the nozzle is less than 1.0, the drawability of the non-drawn yarn is lowered, and if the nozzle diameter exceeds 1.4 mm, the workability at the time of winding is lowered. If the number of odd number of nozzles is less than 300, the strength of the cord is lowered. If the number of odd number of nozzles is more than 500, uniform cooling is difficult to be performed. Also, the L / D of the nozzle is 4 or more. When the L / D is less than 4, the strength of the drawn yarn is decreased.

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 undrawn yarn is drawn by a series of stretching rollers 8, 9, 10, 11, and 11 at a spinning speed of 2800 to 3200 m / min and a winding speed of 5,500 m / 12 and stretched to a total draw ratio of 1.5 times or more, preferably 1.5 to 2.5 times, to obtain the final drawn yarn 13 on the take-up 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 process according to the invention for producing dipped cords using the prepared polyethylene terephthalate fibers comprises the step of imparting a twist to the cord in a pre-stage 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 420/420 TPM to 440/440 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 420/420 TPM, the loss of raw cord is reduced and the fatigue resistance is likely to decrease. On the other hand, if it exceeds 440/440 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 ).

  The dip cord of the present invention is produced by dipping a woven yarn into a dipping solution, drying, stretching and fixing the dope, immersing the dipping solution in the dipping solution, drying and heat setting the dipping cord. The dipping solution is not particularly limited, but it is preferably epoxy resin, para-chlorophenol resorcinol / formalin mixed resin (Pexul).

At this time, the drying should be avoided at a high temperature, and the drying is preferably performed at 90 to 180 ° C for 180 to 220 seconds. If the drying temperature is lower than 90 ° C, drying may not be sufficiently performed, and gelation may occur due to the dipping resin when dried and heat treated. When the drying temperature is higher than 180 ° C, Uneven adhesion of the cord and the deep liquid resin may occur.

The hot fixation is performed so that the cord impregnated in the deep liquid resin has an appropriate adhesive strength with the tire rubber, and the heat fixation temperature is preferably from 220 to 250 DEG C for 50 to 90 seconds. When the heat fixation is performed in less than 50 seconds, the adhesive force is insufficient due to the short reaction time of the adhesive solution, and when the heat fixation is performed for 90 seconds or more, the hardness of the adhesive solution becomes low and the fatigue resistance of the cord may be reduced.

The technical feature of the present invention is to reduce the compactness of the raw cord by controlling the life span of the raw cord to 420 TPM to 440 TPM to increase the content of the deepening cord so that the content of the deepening cord can be increased so that the polyethylene terephthalate Deep code is provided.

Hereinafter, the present invention will be described concretely with reference to Examples. However, the following Examples are merely illustrative of one embodiment of the present invention, and the scope of the present invention is not limited by the following Examples.

A solid phase polymerized polyethylene terephthalate chip having an intrinsic viscosity (I.V.) of 1.10 and a water content of 10 ppm containing 220 ppm of antimony metal was prepared. The prepared chips were melt-spun using an extruder in a spinning draft at a temperature of 290 ° C. Thereafter, the discharged yarn was solidified by passing through a heating zone (atmosphere temperature: 340 ° C) with a nozzle under the length of 60 nm and a cooling zone (blowing with cooling air having an air velocity of 20 ° C and a velocity of 0.5 m / s) having a length of 500 mm, (Containing 70% paraffin oil component). The unstretched yarn was wound by multi-stage stretching to produce the final yarn.

The thus-prepared cord yarn was dipped in a bonding liquid of resorcinol formalin latex (RFL) in a dipping tank, and then the cord yarn was subjected to 4.0% elongation at 170 ° C in a drying zone , Dried for 150 seconds under a 3.0% stretching at 245 ° C in a hot stretching zone, immersed in resorcinol formalin latex (RFL), then dried at 170 ° C for 100 seconds and then stretched at 4.55% at 245 ° C And then heat-set for 40 seconds to prepare a dip cord.

A dipped cord was prepared in the same manner as in Example 1, except that the cord yarn was prepared by spinning up and down the prepared 2 yarns at 440 TPM dm.

[Comparative Example 1]

A dipped cord was prepared in the same manner as in Example 1, except that the cord yarn was prepared by spinning up and down two strands of nylon 6 yarn at 450 TPM dm.

[Evaluation example]

The properties of the dip cords prepared in Examples 1 and 2 and Comparative Example 1 were evaluated by the following methods. The results are shown in Table 1 below.

Item/ Seed PET Nylon6 Example 1 Example 2 Comparative Example 1 Vulcanism Power (kg) 19.1 19.2 22.0 Chinese (%, @ 6.8kg) 10.7 10.9 10.1 Doubt (%) 26.8 27.2 25.9 Craggy
(@ 170 DEG C x 10 min) Power (kg) 19.5 19.2 22.2 Chinese (%, @ 6.8kg) 15.4 16.1 17.4 Doubt (%) 35.0 35.4 37.4 Shrinkage ratio (%, @ 177 ° C x 2 'x 0.05 g / d) 1.1 1.1 7.5 E-S (%) 11.8 12.0 17.6 Toughness (kgf * mm) 590 605 640 DPU (%) 7.4 6.9 4.2 Initial H-adhesion (kg, @ 170 DEG C x 10 min) 13.6 14.3 14.4 Heat peel adhesion force (kg, @ 170 ° C × 60 min) 11.5 11.0 12.0 Fatigue in Belt (%, @ 40 ℃, 80kg, 42kcycle) 97.9 96.6 90.9 Fatigue adhesion retention rate (%, @ 40 ℃, 80kg, 42kcycle) 64 62 65

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

1) Strength (kgf), medium elongation (%)

After standing at 25 ° C and 65% RH for 24 hours, a low tensile tensile tester of Instrong Co. was used. The tire cord was twisted at 80 TPM (Twist Per Meter) Measured at a speed of 300 m / min.

2) Shrinkage

The specimens were allowed to stand under standard conditions of 20 ° C and 65% relative humidity for 24 hours, and the length (L0) was measured by weighing 0.05 g / d and treated at 177 ° C. for 30 minutes under dry conditions using a dry oven And then left for more than 2 hours. Then, a load corresponding to 0.05 g / d was applied to measure the length (L), and the shrinkage ratio was calculated from the equation (1).

Equation 1

S (%) = [(L ₀ -L ₁ ) / L _0] × 100

3) E-S (morphological stability)

The shape stability of the treated cord is defined by the high modulus at a given shrinkage as the properties related to tire side wall indentation (SWI) and handling and is defined as E2.25 (elongation at 2.25 g / d) + FS Shrinkage) is useful as a measure of shape stability for treated cords subjected to different heat treatments, and exhibits better shape stability as the lower.

4) Adhesion (kgf) Evaluation method: H-test Peel adhesion (kg / inch)

The cords were vulcanized at 160 ° C for 20 minutes (initial) or 170 ° C for 60 minutes (heat resistance) at a pressure of 50 kgf / cm ^{2 in} a rubber block, The adhesive strength is measured at a tensile speed of 200 m / min using a low elongation tensile tester. The same test was conducted 10 times to obtain an average value. The other method was carried out according to ASTM D4776-98.

5) Evaluation method of fatigue resistance

As a measure showing the resistance value against the external stress of the heat treatment cords, the tire running condition is simulated. In the present invention, the shoe-shine type and the disk type were tested by the endothelium. In case of the shoe shine type, the rubber was topped with a code of 30 EPI (Ends Per Inch) After curing at 160 ° C for 20 minutes, a specimen was prepared. A load of 70 kg was applied to the specimen by a flexural fatigue tester. The specimens were subjected to a repeated load of 50,000 times and then cords were taken therefrom. The tensile strength was measured using a low speed tensile tester Strength is measured at 300 m / min to determine the strong residual ratio against fatigue power. The strength of the cord was measured by taking 10 cords before and after fatigue. The fatigue test was carried out with three endotoxins and the mean value was obtained. The code strength measurement method was carried out in accordance with ASTM D885.

In addition, the evaluation of the in-disk fatigue was carried out using UEShima Seisakusho Co., Ltd. FT-6110. The fatigue test conditions were 6% of tension and 12% of compression. After 8 hours of fatigue at 2500rpm at 120 ℃, the cords were taken and the strength was measured to determine the strong residual ratio against fatigue strength. The strength of the cord was measured in the same manner as the shoe fatigue measuring method.

1: Pack
2: Nozzle
3: Cooling zone
4: Released
5: Emulsion dispensing device
6: Drawing roller GR1
7: Stretch roller GR2
8: Drawing roller GR3
9: Stretch roller GR4
10: stretching roller GR5
11: Yarn
L: Length of hood

Claims (3)

Melting polyethylene terephthalate containing 85 mol% or more of ethylene terephthalate units and extruding the polyethylene terephthalate while passing through a nozzle to form a discharge yarn;
Radiating the discharged yarn to form an undrawn yarn;
Stretching the undrawn yarn through a stretching roller to produce a yarn;
Spinning the yarn up and down at 420 to 440 TPM; And
And dipping the woven yarn through the weaving step into a dipping solution, followed by drying, stretching and heat setting to produce a dipping cord so as to maintain a dipping amount of 5 wt% or more based on the total weight of the dipping cord;
Wherein the tire cord is made of polypropylene. A polyethylene terephthalate tire cord for motorcycle having a characteristic that the fatigue in the belt is 96% or more as measured by the method of claim 1 at 40 DEG C, 80 kg load, 42,000 cycle, A polyethylene terephthalate tire cord manufactured by the method of any one of claims 1 to 3, having a physical property of an E-S value of 13 or less and a shrinkage ratio of 1.5% or less,

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