KR19990066543A - Polyester multifilament yarns, deep cords and methods for their preparation - Google Patents

Abstract

The present invention relates to a fiber reinforcing material for application to fiber reinforced rubber products such as tires, according to the present invention is made of polyethylene terephthalate of 90 mol% or more, the intrinsic viscosity is 0.70-0.90, the strength is 5.5-7.0g / d and a polyester filament yarn having a terminal modulus of 20 g / d or less, and dipped into an adhesive such as RFL on the filament yarn and having a strength of 5.0 g / d or more and a dimensional stability index ( E _4.5 + SR ) A deep coated cord having less than 7.0% and an elongation at least 15% is provided, and the filament yarn and deep coated cord of the present invention have a high elasticity and a low shrinkage property in a balanced manner, and have excellent dimensional stability and fatigue resistance, thereby making fibers such as tires It can be very usefully applied as a fiber reinforcing material of reinforcement rubber products.

Description

Polyester multifilament yarns, deep cords and methods for their preparation

The present invention relates to a polyester multifilament yarn and a deep cord having high modulus and low shrinkage properties useful as a fiber reinforcing material used in the manufacture of tires, and more particularly, excellent dimensions even at high temperatures. The present invention relates to polyester multifilament yarns, deep cords and processes for their preparation that possess dimensional stability and fatigue resistance.

Representative examples of the fibers that are generally used as rubber reinforcements in rubber composites such as tires include nylon, rayon, and polyester.

Among these, polyester fibers have a benzene ring in their molecular structure, their molecular chains are rigid, and tire cords composed of them have good elastic modulus and fatigue resistance, low flat spots, and excellent creep resistance and durability. By retaining these properties, polyester is widely used as a rubber reinforcing fiber material such as tires, conveyor belts, safety belts, and V-belts.

However, despite these advantages, these conventional polyester tire cords reduce the side wall indentation of recent polyester monoply radial tires and also reduce the Rayon fibers that have been used mainly in radial tires. There is a need for improved dimensional stability in the polyester industry to replace it. In the latter case, the polyester has a strength and modulus comparable to that of rayon even at high temperatures.

As a method for imparting thermal dimensional stability, for example, in US Pat. Nos. 4,101,525 and US Pat. No. 4,195,052 to Davis et al., High-speed spinning is used to draw a highly oriented unstretched yarn using steam or the like. A highly oriented stretched yarn, that is, a single yarn fineness composed of more than 85 mol% of polyethylene terephthalate, 1-20 deniers, and a cord drawn by immersing a multi-stranded yarn having a work loss of 0.004-0.02 lb · in at 150 ° C. in a rubber solution. It is suggested to use for tires.

Japanese Patent Application Laid-Open No. 61-12952 discloses an intrinsic viscosity of 1.0, a diethylene glycol content of 1.0 mol%, and a carboxyl group content of 10 equivalents / 10 ⁶ Using a g-level polyester polymer, the unstretched yarn spun at a spinning speed of 2000 to 2500 m / min is stretched at a temperature of 160 ° C, and the yarn prepared by heat treatment at 210 to 240 ° C is immersed in a conventional rubber solution. A method for producing a cord having a strength of 7.0 g / d or more, an irrespective absorption peak temperature of 148 to 154 캜, and a dry heat shrinkage of 3.3 to 5% is described.

However, in these methods, yarns produced by high-speed spinning and stretching have an effect on improving fatigue resistance, but the molecular chain length in the amorphous region becomes uneven and longer, and loose molecular chains coexist, resulting in large loss of strength and fiber. Due to the failure to overcome the physical property difference between the inner and outer layers, there is a disadvantage in that the property change due to the deterioration of the elongation and the defect of the microstructure is large.

In addition, when a high viscosity polymer having an ultimate viscosity of 1.0 or more is used, there is a limit to having low shrinkage characteristics or a highly-oriented stretched yarn in which a yarn before being treated in a rubber solution, that is, a two-phase structure in which crystals and amorphous crystals are clear. During immersion heat treatment, strong deterioration occurs due to deterioration of crystal part due to high heat.

Accordingly, the present invention relates to a polyester multifilament yarn, a tire cord, and a manufacturing method thereof having excellent dimensional stability and fatigue resistance even after thermal aging in view of all the problems of the prior art as described above.

The polyester filament yarn manufacturing method of the present invention that solves the above problems is melt spinning the polyester resin of 90 mol% or more polyethylene terephthalate to less than 290 ℃ and after spinning the temperature directly below the nozzle 100 ℃ to less than 200 ℃ After the delay in cooling, there is provided a method for producing a polyester filament yarn, characterized in that the cooling, stretching, heat treatment.

In addition, the polyester filament yarn for rubber reinforcement according to the present invention is made of polyethylene terephthalate of 90 mol% or more, has an intrinsic viscosity of 0.70-0.90, strength of 5.5-7.0g / d and terminal modulus of 20g / d or less do.

In addition, the polyester diffused cord according to the present invention is twisted and weaved by weaving and weaving two or more polyester filament yarns of 90 mol% or more of polyethylene terephthalate based on 1000 deniers, respectively, and then weaving according to the conventional method. The code obtained is characterized by the following physical properties:

a) strength is at least 5.0 g / d,

b) dimensional stability index ( E _4.5 + SR ) <7.0%,

c) at least 15% elongation at break.

Hereinafter, the present invention will be described in more detail.

Preferably the method for producing the polyester filament yarn according to the invention comprises the following processes:

Iii) a process in which a polyester resin of 90 mol% or more polyethylene terephthalate and an intrinsic viscosity (I.V.) of 0.75-0.95 is melted at a temperature of less than 290 ° C and spun at a spinning speed of at least 3,000 m / min,

Ii) the process of cooling and delaying the unstretched winding tension of 0.3 g / d or more at the time of winding by maintaining a predetermined area of 100 mm or more directly below the nozzle after the spinning at a temperature of 100 ° C. or more and below 200 ° C .;

Iii) cooling and solidifying at a cooling wind temperature below the glass transition temperature of the polymer,

Iii) stretching the undrawn yarn obtained by cooling and solidifying at a temperature above the glass transition temperature or below the crystallinity degree temperature, and

I) A step of heat-setting the obtained stretched yarn at a temperature of 210 ° C or lower.

It is suitable that the polyester filament yarn of the present invention contains 90 mol% or more, preferably 95 mol% or more of polyethylene terephthalate. In addition, the polyester of the present invention may contain 10 mol% or less, preferably 5 mol% or less of a copolymer ester other than polyethylene terephthalate.

Examples of ester-forming components useful as copolymerized ester units other than polyethylene terephthalate include glycols such as diethylene glycol, trimethylene glycol, detramethylene glycol, hexamethylene glycol, and the like, isophthalic acid, hexahydroterephthalic acid, adipic acid, seba Dicarboxylic acid, such as a succinic acid and azelaic acid, is mentioned.

The polyester filament yarns of the present invention usually have a fineness of about 3 to 5 denier per filament, but this value can vary widely as will be apparent to those skilled in the art.

The polyester filament yarn having excellent dimensional stability of the present invention has excellent dimensional stability and toughness when impregnated with a fiber reinforcement in a rubber composite such as a tire, thereby effectively replacing rayon fibers used in recent monoply radial tires. It is possible to meet the needs of improving the dimensional stability of polyester in the future.

Maintaining high elastic modulus and low thermal shrinkage at high temperatures associated with tire sidewall indentation (abbreviated as SWI) and control are two important factors.

First, when excessive cord shrinkage occurs during the curing process, the elastic modulus of the cord decreases rapidly. Second, the shrinkage of the cord is a factor that hurts the uniformity of the tire. Therefore, the comparison of elastic modulus and dry heat shrinkage at high temperatures is very important for tire cords. Since tire cords experience a few percent deformation during manufacturing or use, LASE-5 (load value at 5% elongation) is useful as a measure of actual modulus of elasticity, or as a measure of compliance. Elongation E _4.5 (elongation at _4.5 kg load) can be used. The elastic modulus at high temperature is an important parameter as a factor governing the tire SWI and adjustability.

The polyester multifilament yarn in the present invention generally has a fineness of about 3-5 denier per filament and is generally composed of about 200 to 500 continuous filaments, but these values are obvious to those skilled in the art. Various changes can be applied.

The multifilament yarn in the present invention is suitable as an industrial cord for rubber reinforcement in which high-strength rayon deep cord is used when used as a deep cord, and particularly has a high strength and toughness even at a high temperature of 100 ° C. or higher, and shows a low shrinkage rate. It can be especially useful as a.

The deep cord of the present invention satisfies both high strength and low shrinkage at the same time, and thus can be usefully used as a reinforcing material for rubber products such as tires and belts or for other industries.

Polyester used as starting material has an intrinsic viscosity ( η ) Is 0.75-0.95. Where intrinsic viscosity ( η ) Is the relative viscosity of the solution of 8 g of sample dissolved in 100 ml of ortho-chlorophenol using an Ostwald viscometer. η _r ) Is the value calculated according to the following equation.

η = _r 0.0242η +0.2634

here,

t is the drop time of the solution in seconds, t ₀ is the drop time of ortho-chlorophenol in seconds

d is the density of solution (g / cm 3), d ₀ is the density of orthochlorophenol (g / cm 3)

Morphological stability and fatigue resistance are closely related to the degree of polymerization of polymers-concepts such as molecular weight and intrinsic viscosity. That is, the lower the molecular weight of the polymer is advantageous in terms of shape stability, the higher is advantageous in terms of fatigue resistance. In the present invention, by using a polymer having a relatively low intrinsic viscosity of 0.75-0.95, the spinning temperature is spun at 290 ° C, preferably 280-288 ° C, so as to secure excellent morphological stability and minimize fatigue resistance. By blocking it can have an intrinsic viscosity of about 0.70-0.90.

In order to obtain highly oriented undrawn yarn, the main technique is to increase the winding tension of undrawn yarn to 0.5 g / d or more, which is the tension that is received at the point where the emitter leaving the nozzle is cooled by the cooling wind and reaches the glass transition temperature. Depending on the size, this depends mainly on the spinning speed, the single hole discharge amount, the ambient temperature directly below the nozzle, and the temperature of the cooling wind.

Therefore, the discharger leaving the spinneret is cooled at the point where it is cooled by the cooling wind and reaches below the glass transition temperature. In the present invention, in order to increase the tensile strain rate of the emitter, the spinning speed is increased and the atmosphere temperature directly under the nozzle is controlled. Therefore, we propose a method of increasing the winding tension of undrawn yarn at the same spinning speed. By applying this method, it is possible to manufacture high-oriented undrawn yarn by minimizing single yarn and cut off due to the cooling unevenness, which is generally generated when manufacturing high-oriented undrawn yarn by high-speed spinning alone. .

In the present invention, cooling is delayed by adjusting the ambient temperature directly below the nozzle to 100 ° C or more and less than 200 ° C, preferably 150-195 ° C. As a general method for manufacturing high-strength yarns, such as industrial yarns, a thermostat is installed to heat the atmosphere temperature directly below the nozzle temperature above the nozzle temperature to lower the orientation of the undrawn yarn so that high magnification stretching is possible to make high-strength yarns. There is a disadvantage that the shrinkage is increased. Therefore, in order to improve the thermal dimensional stability, if the heating speed is kept at a high temperature while the spinning speed is high, the woolen and single yarn cuttings are frequently caused and the production efficiency is drastically reduced.

After the cooling is thus delayed, the filament yarn is cooled by the cooling wind. In this case, the cooling is preferably carried out at a glass transition temperature of the polymer, preferably 20 ° C. or higher, or below the glass transition temperature of the polymer, particularly preferably at a cooling wind temperature of 40-60 ° C. Cooling in this temperature range can reduce the temperature difference between the filament and the outer layer at the freezing point of the emitting yarn. In other words, it is possible to minimize the strong degradation caused by the structure difference between the filament and the outer layer.

If cooling unevenness occurs in the filament, it is difficult to maintain high strength at the same time with excellent dimensional stability due to the low viscosity polymer due to the strong decrease in yarn after the stretching process.

In this method, the undrawn yarn obtained by cooling in this manner is drawn at a low magnification at a temperature above the glass transition temperature or below the crystallinity temperature.

Stretching is performed in two or more stages of multi-stretching, but the crystallization temperature of the highly oriented unstretched yarn produced by high-speed spinning is usually 10 ° C. or more lower than slow spinning as the spinning speed increases, so the stretching temperature is preferably glass of the polymer. The transition temperature is 120 ° C. or less, more preferably 80 ° C. to 120 ° C., and most preferably 80 ° C. to 90 ° C. If the stretching temperature exceeds 120 ° C, microcrystals are already present before the molecular chains are oriented, thereby limiting the stretchability and, in severe cases, breaking the molecular chains. In addition, when extending | stretching below 80 degreeC, the fluidity | liquidity of a molecular chain will disappear and drawing efficiency will fall.

And the total draw ratio should be 1.4 times to 2.2 times, preferably 1.4 times to 1.9 times as a condition for maintaining the minimum strength (5.0 g / d). If the total draw ratio is less than 1.4 times, the strength of the fiber is insufficient, and if it exceeds 2.2 times, the high modulus value and the low shrinkage cannot be achieved, and the strength decrease rate is also high.

The reason why it is preferable to perform two or more multistage stretching in the present invention is as follows. In other words, in the case of stretching in the first drawing zone by 70% or more and performing only one step drawing, the entangled molecular chains remain short and entangled due to a short time to go to the fibril structure, which acts as a defect in the structure. This is because the shrinkage rate due to heat increases.

In the present invention, the dry heat shrinkage rate in deep cord is utilized by utilizing the unique property of the non-drawn yarn prepared by high stress spinning, that is, no shrinkage occurs when heat is applied after the undrawn yarn is drawn under specific conditions. It can be greatly reduced.

That is, elongation or contraction behavior occurring at high temperature is a phenomenon occurring according to the magnitude of elongation force due to crystallization of the oriented amorphous molecular chain. In the present invention, the mechanism of the elongation contraction behavior is applied to minimize the shrinkage rate.

In order to maximize the elongation behavior such as liquid, heat crystallization should not occur during stretching. To this end, in the present invention, the stretching is performed at a low magnification at a temperature below the crystallization temperature of the undrawn yarn.

In other words, when heat crystallization occurs before stretching, the stretched deformation occurring while the oriented amorphous region is oriented crystallization can no longer occur because the oriented amorphous region is changed into a crystalline region. Dry heat shrinkage becomes large because only shrinkage behavior occurs by disorientation of the non-molecular chain present in the amorphous region.

In the present invention, the stretched filament is heat treated. According to the present invention, since the yarn is heat-treated in a state where the orientation is almost completed, the yarn structure varies greatly depending on the temperature at that time. The heat treatment temperature is 100-210 ° C, preferably 100-180 ° C. If the heat treatment temperature exceeds 210 ° C, the crystal region and the amorphous region are already clearly distinguished, so the orientation of the crystal region is extremely increased and the orientation of the amorphous region is lowered, thereby minimizing physical property degradation due to abnormal crystal growth during subsequent dipping. There will be no.

In general, the unstretched yarn before stretching expresses its properties due to crystallization and orientation of molecular chains due to the stretching heat treatment during the stretching process. It takes a lot

According to the present production method described above, the filament yarn having an intrinsic viscosity of 0.70-0.90, strength of 5.5-7.0 g / d, and terminal modulus of 20 g / d or less can be manufactured.

In general, when the initial modulus is high or the terminal modulus is high, it is known that the strong deterioration during continuous shooting and dipping is large, but the inventors have found that the deterioration of the deterioration is greater than the initial modulus. However, if the yarn has already undergone much crystallization, no matter how low the terminal modulus, the strength is severely deteriorated. In other words, it is possible to reduce the terminal modulus by increasing the relaxation rate or to increase the heat treatment, and even have a negative value, but at this time, the crystallinity is high so that the strong deterioration during the twisting and dipping cannot be avoided.

This is because most of the accumulated stress is a stress caused by heat from drawing, heat treatment, and the like. Therefore, even when the orientation of the amorphous region is reduced to about 0.6 or less in order to reduce such stress (US Pat. Nos. 4101515 and 4195052), the folded molecular chain of the crystal surface during recrystallization by high crystallization and post-processing Many defects in the chain and the crystal interface do not completely free the restraint of the non-molecular chains, and it is not easy to obtain high elastic properties due to the decrease in the tie molecular chain fraction.

The yarn thus produced is twisted and woven at least two yarns on the basis of 1000 deniers, and then dipped in an adhesive solution such as RFL (Resorcinol-Formaldehyde-Latex) by a conventional dipping method, followed by drying and Water normalized heat-treated at temperature and tension to obtain a dipped cord cloth. Deep coded means a gradient code constituting a deep coded paper, the role of the weft is only to secure the gap between the gradient code. Therefore, the properties of the deep cord paper are mainly expressed by the properties of the deep cord, and the same is true in the case of the present invention.

By using the filament yarn according to the present invention, it is possible to obtain a tire cord having a dimensional stability index (ES) of 7.0 or less, strength of 5.0 g / d or more and cutting elongation of 15% or more.

As described above, the deep cord of the present invention has excellent dimensional stability and fatigue resistance even at high temperature, and is very effective for applying to rubber products such as tires and conveyor belts.

It is evaluated by the following method of the properties shown in the present specification.

Strength and elongation: It was measured under the conditions of tensile speed of 300 mm / min, sample length of 250 mm, ambient temperature of 25 ° C., and 65% RH by using a low-strength tensile tester of Instron according to JIS-L1017 method.

-Medium elongation (E _4.5 ): Elongation at load 4.5g / d in the extension load curve obtained by using Instron's low-speed extension type tensile tester according to JIS-L1017 method.

-Terminal modulus of yarn: The strength increase between the elongation at break of 2.4% before the cut elongation on the S-S curve was obtained and divided by the denier divided by 0.024.

- Dry heat shrinkage ratio (SR) of the cord: the length of a sample measured at after the cord support (cord fabric) 24 sigan allowed to stand in a 25 ℃ by taking the cord sample, 65% RH in the processing of rubber solution of 20g static load l _0, Further, the dry sample was heat-treated in an oven at 150 ° C. for 30 minutes under a static load of 20 g, and the length of the sample measured was determined to be l ₁ from the following formula.

-Dimensional stability index: The value obtained by adding the dry heat shrinkage of the intermediate elongation and the cord.

Features and other advantages of the present invention as described above will become more apparent from the embodiments described below.

[Examples and Comparative Examples]

Solid-phase polymerization of a polyester chip having an intrinsic viscosity of 0.65 was carried out by melt extrusion through a spinneret having a diameter of 0.60 mm and 300 detained holes under conditions as shown in Table 1 below. The temperature was carried out by various changes as shown in Table 1 below, after cooling solidified under the conditions of a temperature of 40 ℃ wind speed 0.6m / sec in the cooling zone was wound undrawn yarn at a speed of 3000m / min. The obtained non-drawn yarn was subsequently subjected to two-stage stretching (total drawing ratio 1.89 times) at 80 ° C. and 100 ° C. temperature using a high detroelator, and then heat-set by variously changing the heat treatment temperature on the high deatro controller as shown in Table 1 below. Winding 1000 denier yarns in the winder giving 2% relaxation. The physical properties of the yarn obtained in each example are shown in Table 2 below.

The two yarns of each example were 480 TPM in the upper and lower edges, respectively, and then dipped in RFL at 245 ° C. to produce a deep cord. Physical properties of the prepared deep cord are shown in Table 3 below.

division Chip Intrinsic Point Room temperature (℃) Thermal insulation temperature (℃) Undrawn drawability (g / d) U.S. stretch orientation High temperature (℃) Example 1 0.75 282 100 0.35 0.045 190 Example 2 0.75 282 190 0.32 0.041 190 Example 3 0.85 284 150 0.42 0.057 200 Example 4 0.85 284 195 0.40 0.051 200 Example 5 0.95 288 150 0.55 0.065 200 Comparative Example 1 0.70 295 250 0.25 0.035 230 Comparative Example 2 0.95 300 250 0.34 0.048 230 Comparative Example 3 0.95 300 320 0.32 0.044 230 Comparative Example 4 1.10 305 320 0.41 0.048 230

division Intensity (g / d) Elongation at break (%) Terminal Modulus (g / d) Yarn-specific viscosity Example 1 5.8 15.8 2.5 0.71 Example 2 5.8 15.5 2.0 0.70 Example 3 7.0 16.0 12.0 0.82 Example 4 7.0 16.0 10.8 0.82 Example 5 7.0 15.8 12.9 0.92 Comparative Example 1 5.4 12.9 26.6 0.64 Comparative Example 2 6.8 12.2 32.0 0.88 Comparative Example 3 6.9 12.5 32.8 0.88 Comparative Example 4 7.5 12.3 34.9 0.95

division Deep de Cod's Properties Remarks Strength (g / d) E _4.5 SR ES Example 1 5.2 3.5 2.3 5.8 - Example 2 5.2 3.5 2.5 6.0 - Example 3 6.2 3.5 2.8 6.3 - Example 4 6.2 3.5 3.0 6.5 - Example 5 6.3 3.5 3.1 6.6 - Comparative Example 1 4.7 3.5 3.0 6.5 Yarn strength is low Comparative Example 2 5.3 3.5 4.0 7.5 Comparative Example 3 5.5 3.5 4.0 7.5 Comparative Example 4 5.9 3.5 4.3 7.8

The filament yarn and the deep cord according to the present invention from the physical property measurement results of the above Examples and Comparative Examples have a balance of high elasticity and low shrinkage characteristics and excellent dimensional stability and fatigue resistance, so that the fiber reinforcement of the fiber reinforced rubber products such as tires As a very useful application.

Claims (6)

After melt-spun polyester resin of 90 mol% or more polyethylene terephthalate to less than 290 ℃ and cooling after delaying the temperature directly below the nozzle to 100 ℃ or more and less than 200 ℃, characterized in that the cooling, stretching, heat treatment Method for producing polyester filament yarn. 2. The polyester resin of claim 1, wherein the polyester resin of polyethylene terephthalate of 90 mol% or more and intrinsic viscosity (IV) of 0.75-0.95 is melted at a temperature of less than 290 ° C and spun at a spinning speed of 3,000 m / min or more. Process, ii) the process of cooling to delay the unstretched winding tension of 0.3g / d or more at the time of winding by keeping a certain area of 100mm or more directly below the nozzle after the spinning to the temperature of 100 ℃ or more and less than 200 ℃, i) the glass transition temperature of the polymer A process of cooling and solidifying at the following cooling wind temperature, i) a process of stretching undrawn yarn obtained by cooling and solidification at a temperature above the glass transition temperature and the crystallinity degree temperature, and b) heat-setting the obtained stretched yarn at a temperature of 210 ° C or below. Method for producing a polyester filament yarn containing. The method for producing a polyester filament yarn according to claim 1, wherein in the cooling delay step (ii), the temperature under the nozzle is 150-195 ° C. A polyester filament yarn made of polyethylene terephthalate of 90 mol% or more, intrinsic viscosity of 0.70-0.90, strength of 5.5-7.0 g / d, and terminal modulus of 20 g / d or less. The polyester filament yarn according to claim 4, wherein the elongation at break is 15% or more. Polyester dipped cord which is manufactured by dipping and weaving two or more polyester filament yarns of 90 mol% or more polyethylene terephthalate with upper and lower edges respectively, followed by dipping according to the conventional method, and satisfying the following properties: a) strength of at least 5.0 g / d, b) dimensional stability index ( E _4.5 + SR ) Less than 7.0%, c) at least 15% elongation at break.