KR20120072860A - Process for preparing high modulus polyester tire cord having an excellent dimensional satability - Google Patents

Abstract

PURPOSE: A method for fabricating a polyester tire cord of high modulus is provided to ensure high strength and low elongation and to be applied to a tire, an industrial rope, or a seat belt. CONSTITUTION: A method for fabricating a polyethylene terephthalate tire cord comprises: a step of melting a polyethylene terephthalate chip through an extruder(1); a step of melting and extruding molten polymers through a nozzle; a step of drawing spinning drafts; a step of preparing a raw cord from multifilaments; and a step of dipping and treating the raw cord in a dipping solution.

Description

Process for preparing high modulus polyester tire cord having an excellent dimensional satability

Polyester tire cord according to the present invention has a high strength, high modulus and low elongation characteristics can be applied to industrial products used as a material of tires, industrial ropes, civil reinforcement, webbing or seat belt.

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. In addition, problems of viscosity decrease during spinning of high-viscosity PET resins and problems of increased shrinkage and morphological stability of yarns due to high magnification stretching occur. Even in the HMLS method to overcome the above problems, if the strength in terms of strength and shape stability (shrinkage rate + entrepreneurship) is taken, there is a problem that the shape stability is lowered, and if the shape stability is improved, the strength is not obtained.

The present invention is easy to secure the yarn even at low draw ratio by increasing the hole diameter and spinning speed of the appropriate spinning nozzle to increase the orientation of the undrawn yarn, the existing tire when manufacturing a polyester deep cord using the yarn manufactured in this way A powerful cord that is about 10% better than the cord can be obtained and the weight can be reduced when the tire is manufactured.

According to a preferred embodiment of the present invention, a polyetherene terephthalate chip having an intrinsic viscosity of 1.0 to 1.2 is melted through an extruder, the diameter and L / D are each 1.0 to 1.4 mm and 4 or more, and the odd number is 300. After extruding the molten polymer through a nozzle of 500 to 500, the spinning draft is stretched in multiple stages through a high-speed roller to 1200 to 1500 to produce polyethylene terephthalate, and then the multifilament is added to the lower and upper edges to produce a raw cord, The present invention provides a method for producing a polyethylene terephthalate tire cord, wherein the raw cord is immersed in a dipping solution.

According to another suitable embodiment of the present invention, the shape stability index of the polyethylene terephthalate tire cord is 6.5% or less.

According to another suitable embodiment of the present invention, the strength of the polyethylene terephthalate tire cord is 22 kg (1500 D / 2) or more.

According to another suitable embodiment of the present invention, the elongation at break of the polyethylene terephthalate tire cord is 9.0% or more.

By increasing the hole diameter and spinning speed of the proper spinning nozzle, the draft can be maintained at 1200 ~ 1500 during spinning. As a result, the orientation of the unstretched yarn increases, making it easy to secure the yarn even at low draw ratios. Therefore, when manufacturing a polyester dip cord, a cord of about 10% more strength than an existing tire cord can be obtained, and the weight can be reduced when manufacturing a tire.

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

Hereinafter, with reference to the accompanying drawings will be described in detail the configuration and operation of the embodiment according to the present invention.

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. On the other hand, if the intrinsic viscosity of the chip is higher than 1.20, the radial tension is excessively increased and the cross section of the emitter is uneven. It causes a lot of filament cuts during stretching, resulting 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, a polyethylene terephthalate chip has a spinning temperature of 290 to 310 ° C. and a spinning draft of 1200 to 1500 through an extrude 1, a gear pump 2, a nozzle 3, and a heating device 4. 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 due to pyrolysis and hydrolysis. If the spinning draft ratio is less than 1200, the filament cross-section uniformity is worse, the drawing workability is significantly reduced, while if the spinning draft ratio exceeds 1500, filament breakage occurs during spinning, making normal yarn production difficult.

In addition, it is preferable to extrude a polyetherene terephthalate chip having an intrinsic viscosity of 1.0 to 1.2 through a nozzle having a diameter of 1.0 to 1.4 mm and an odd number of 300 to 500. At this time, when the diameter of the nozzle is less than 1.0, the stretchability of the undrawn yarn falls, and when the nozzle diameter exceeds 1.4mm, workability during winding is inferior. In addition, if the number of nozzles is less than 300, the cord strength is lowered. If the number of nozzles is more than 500, uniform cooling becomes difficult and the stretchability is lowered. In addition, the L / D of the nozzle is characterized by four or more, but less than four, the strength of the drawn yarn is inferior.

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.

The unstretched yarn is a spin draw method and has a series of stretching rollers (8), (9), (10), (11) and (with spinning speed of 2800 to 3200 m / min and winding speed of 5,500 m / min or more). 12) is drawn at a total draw ratio of at least 2.0 times, preferably at 2.0 to 2.5 times, to obtain a final stretched yarn 13 at the take-up 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 part 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 method according to the present invention for producing a deep cord using the produced polyethylene terephthalate fiber comprises a step (twist step) to produce a live cord by twisting the cord in the previous step.

In the manufacturing method according to the present invention, the physical properties such as the elongation, the core, the fatigue resistance, etc. of the cord change depending on the level (year) of twisting imparted to the polyethylene terephthalate fiber at the lower or upper edge. In general, when the twist is high, the strength decreases, and the trunk and the body tend to increase. In addition, fatigue fatigue tends to improve with increasing twist. Polyethylene terephthalate tire cord prepared according to the present invention was produced to have a soft water of 300/300 TPM to 500/500 TPM at the same time. The upper and lower edges are set to the same value so that the manufactured tire cords are easily maintained in a straight line without exhibiting rotation or twisting, thereby maximizing physical property expression. If it is less than 300/300 TPM, the elongation of the raw cord is reduced and fatigue resistance is likely to be lowered. On the other hand, if it exceeds 500/500 TPM, the force drop is so large that it is not suitable for tire cords.

Raw cords are woven using a weaving machine, and the resulting fabric is immersed and cured in a dipping solution to dip cords for tire cords having a resin layer attached to the surface of the raw cord. Is manufactured).

Dipping in the manufacturing process according to the present invention refers to the impregnation of a resin layer called Resorcinol-Formaline-Latex (RFL) on the surface of the fiber. The dipping process is carried out to ameliorate the disadvantages of the fibers for tire cords that are less adhesive with rubber.

In the present invention, the adhesive liquid for adhesion of the polyethylene terephthalate cord and rubber may be prepared using the following method.

Manufacturing method of adhesive liquid

45.6 parts by weight of 29.4 wt% resorcinol;

255.5 parts by weight of distilled water;

20 parts by weight of 37% formalin; And

10 wt% sodium hydroxide 3.8 parts by weight

Prepare a solution containing the reaction after stirring for 5 hours at 25 ℃ add the following components.

40wt% VP-latex 300 parts by weight

129 parts by weight of distilled water

23.8 parts by weight of 28% aqueous ammonia.

After the addition of the ingredients it is aged for 20 hours at 25 ℃ to maintain a solid concentration of 19.05%.

The polyethylene terephthalate cord is dried and then the adhesive liquid is attached. In order to control the adhesion amount of the adhesive liquid, a stretch of 1 to 5% is required, and preferably 2 to 4% of stretching can be made. If the elongation ratio is too high, the adhesion amount of the adhesive liquid can be controlled but the elongation is reduced and consequently the fatigue resistance is reduced. On the other hand, if the elongation ratio is too low, for example, when the elongation ratio is lowered to less than 1%, a problem arises in that the dipping liquid penetrates into the polyhexamethyleneadipamide cord, making it impossible to control the defect per unit (DPU).

The adhesive amount is preferably 4 to 6% by weight of the fiber based on the solid content. After attaching the adhesive solution, the polyethylene terephthalate deep cord is dried at 120 to 150 ° C. The drying time may be 180 seconds to 220 seconds, and the drying process is performed while the polyethylene terephthalate deep cord is stretched by 1 to 2%. When the elongation ratio is low, the core and the elongation of the cord may increase, indicating physical properties that are difficult to apply to the tire cord. On the other hand, if the elongation rate is more than 2%, the central body level is appropriate, but the body length may be too small, leading to poor fatigue resistance.

After drying, heat treatment is carried out in a temperature range of 130 to 170 ℃. The elongation rate during the heat treatment is maintained between -2 and 0%, and the heat treatment time is appropriate for 50 seconds to 90 seconds. If the heat treatment is performed for less than 50 seconds, the reaction time of the adhesive liquid is insufficient, resulting in low adhesive strength.In contrast, if the heat treatment is performed for 90 seconds or more, the hardness of the adhesive liquid is increased to reduce the fatigue resistance of the cord. Can be.

Polyethylene terephthalate deep cord manufactured through such a process is applied to the carcass ply or cap fly is used for the production of tires for passenger cars.

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).

6) Even with fatigue

The fatigue strength of the tire cord was measured by using a belt fatigue tester (Belt Fatigue Tester) commonly used for 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 immersion in tetrachloroethylene solution for 24 hours, and the rubber and cord were separated to measure residual strength. . The residual strength was measured after drying at 107 ° C. for 2 hours using a conventional tensile strength tester according to the method (a) above.

7) Shrinkage Force

After 24 hours at 25 ° C and 65% RH, the maximum value of stress (F) generated after treatment for 2 minutes at 177 ° C at 0.05g / d static load (F ') using a Testrite instrument It measured using. Dry heat shrink force (SF) can be expressed as follows.

F (N) = F '-F.

Example 1

A solid-state polymerized polyethylene terephthalate chip having an intrinsic viscosity (I.V.) 1.0 containing 40 and 220 ppm of manganese and antimony metals, a manganese / phosphorus content ratio of 1.8 and a moisture content of 20 ppm was prepared. The prepared chip was melt spun by using an extruder under the spinning conditions of Table 1 at a temperature of 295 ℃. 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. This POY was wound up at the spinning speed shown in Table 1 to prepare a final stretched yarn (yarn) of 1500 denier.

After two strands of yarn were rolled up and down at 370 turns / m to prepare cord yarns, the cord yarns were immersed in the adhesive solution of (PCP resin + RFL) in a dipping tank and then stretched 2.0% at 170 ° C. in a drying area. After drying for 150 seconds and heat setting for 150 seconds under 6.0% stretching at 240 ° C. in a high temperature stretching area, immersing in RFL again, drying for 100 seconds at 170 ° C. and heat setting for 40 seconds under -4% stretching at 240 ° C. Was prepared.

The physical properties of the drawn yarn and the treatment cord thus prepared are shown in Table 1 below.

[Examples 2 to 4 and Comparative Example 1]

The stretch yarn and the treatment cord were prepared by performing the experiment in the same manner as in Example 1 while changing the intrinsic viscosity of the chip, the odd number of spinnerets, the spinning speed and the winding speed as shown in Table 1 below.

The physical properties of the drawn yarn and the treatment cord thus prepared are shown in Table 1 below.

○: Good appearance, △: Normal appearance, X: Poor appearance

Although the present invention has been described with reference to the above embodiments, the present invention is not limited thereto. The above embodiments may be modified or changed without departing from the spirit and scope of the present invention, and those skilled in the art will recognize that such modifications and changes also belong to the present invention.

1: Extrude 2: Gear Pump
3: nozzle 4: heating device
5 ~ 6: Cooling area 7: Emulsion applying device
8-12: Stretching roller 13: Winding roller

Claims (4)

Melt the polyetherene terephthalate chip with an intrinsic viscosity of 1.0 to 1.2 through an extruder, and melt the polymer through a nozzle having a diameter and L / D of 1.0 to 1.4 mm and 4 or more and an odd number of 300 to 500, respectively. After extruding and spinning the draft draft through multiple rollers at 1200 to 1500 to multistage to produce polyethylene terephthalate, the multifilament was added to the lower and upper edges to produce a raw cord, and the raw cord was immersed in a dipping solution. Process for producing a polyethylene terephthalate tire cord, characterized in that the treatment. The method of claim 1,
Method for producing a polyethylene terephthalate tire cord characterized in that the shape stability index of the polyethylene terephthalate tire cord is 6.5% or less. The method of claim 1,
Method of producing a polyethylene terephthalate tire cord characterized in that the strength of the polyethylene terephthalate tire cord is 22.0kg or more. The method of claim 1,
Method for producing a polyethylene terephthalate tire cord, characterized in that the elongation at break of the polyethylene terephthalate tire cord is 9.0% or more.

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