Pneumatic vehicle tyre with a carcass

Abstract

The invention relates to a pneumatic vehicle tyre having a carcass, wherein the carcass has at least one carcass ply with reinforcement members, wherein the reinforcement members each take the form of a tyre cord comprising at least one polyester yarn consisting of at least 90 mol% polyethylene terephthalate (PET). The reinforcement member of the carcass is intended to provide sufficient tyre stability and durability over a broad fineness range, in particular in high speed use, and to allow the weight of the tyre to be reduced. This is achieved in that the tyre cord has a breaking strength of at least 8.0 g / den, a LASE @ 2% of at least 1.1 g / den and a LASE @ 5% of at most 2.5 g / den, a breaking energy of at least 183 (g / den)·mm and a sidewall indentation value of at most 5%.

Description

[0001] Description

[0002] Pneumatic vehicle tires with a carcass

[0003] The invention relates to a pneumatic vehicle tire with a carcass which extends from one bead region to the other bead region and is anchored there by wrapping tensile bead cores, wherein the carcass has at least one carcass ply with strength members embedded in elastomeric material, arranged parallel and spaced from one another, wherein the strength members are each designed as a tire cord comprising at least one polyester yarn which consists of at least 90 mol% of polyethylene terephthalate (PET).

[0004] A pneumatic vehicle tire generally has an air-impermeable inner layer, a carcass containing reinforcements that extends from the crown area of ​​the tire over the sidewalls to the bead areas and is anchored there by wrapping tensile bead cores, a radially outer profiled tread and a belt composite arranged between the tread and the carcass.

[0005] The carcass has one or more carcass layers.

[0006] The reinforcements of the carcass ply are embedded in a rubber mixture during the manufacturing process, for example by calendering, in order to be used as a rubberized reinforcement ply in the tire. The carcass must have sufficient strength to adequately absorb the forces occurring during tire operation and to be durable. In particular, the carcass must withstand the internal pressure of the tire. Typically, the reinforcements of the carcass are arranged in the area of ​​the sidewall at a small angle of no more than 10° to the radial direction. Polyester tire cords are known to be used as reinforcements in the carcass. In this case, two or more multifilament yarns of polyester are twisted together to form the cord. Cords made of high modulus low shrinkage PET (HMLS-PET) have proven to be particularly suitable. Well-known for the carcass is, for example,the use of HMLS-PET 2000 den x 2 and 3000 den x 2.

[0007] Tire cord is manufactured using an industrial yarn, such as polyester yarn. Polyester yarn can generally be produced by melting polyester granules, expelling the molten polyester through a spinneret to form filaments, cooling the semi-solidified filaments expelled from the spinneret, and bundling, stretching, and winding the cooled filaments.

[0008] Efforts are being made to optimize rolling resistance. The use of the thinnest possible reinforcements is advantageous for this. However, even with a reduction in their thickness, and thus their diameter, the reinforcements in the casing must still meet the various requirements placed on the casing. The tire must still meet the requirements regarding stability and durability, especially in high-speed applications.

[0009] When reducing the fineness of the carcass reinforcements, the requirements for the physical properties of breaking strength, elastic modulus, fracture energy, and shrinkage must still be met. However, this has not yet been achieved with current PET reinforcements with commercially available strength or the processes for their production.

[0010] The object of the invention is to provide a pneumatic vehicle tire whose carcass reinforcements provide sufficient stability and durability of the tire over a wide range of gauges, particularly in high-speed applications, and enable a weight reduction of the tire. This is achieved by the tire cord

[0011] • a tenacity of at least 8.0 g / den and

[0012] • a LASE@2% of at least 1.1 g / den and

[0013] • a LASE@5% of maximum 2.5 g / den and

[0014] • a breaking energy (toughness) of at least 183 (g / den) mm, each determined according to ASTM-D-885 standard test method,

[0015] • and a value of sidewall indentation (SWI: Side Wall Indentation) of at most 5%, preferably of at most 4%, particularly preferably of at most 3.6%, wherein the sidewall indentation SWI is given by the following equation 1:

[0016] [Equation 1 ] SWI (%) = [(D)-(C)] + [(A) - (B)] where in equation 1:

[0017] • (A) is a residual shrinkage of the tire cord, which is measured after measuring the hot shrinkage using a shrinkage tester (at a sample length of 250 mm, at 180°C and 2 minutes exposure time, measured under a preload of 20 to 45 g) and then allowing to cool for 1 min.,

[0018] • (B) is a residual shrinkage of the tire cord, which is measured after measuring the hot shrinkage using a shrinkage tester (at a sample length of 250 mm, at 180°C and 2 minutes exposure time, measured under a preload of 40 to 90 g) and then allowing to cool for 1 min.,

[0019] • (C) is an elongation of the tire cord at a load of 1.5 to 3.0 kg, measured according to ASTM-D-885 standard test method, and

[0020] • (D) is an elongation of the tire cord under a load of 3.0 to 6.0 kg, measured according to ASTM-D-885 standard test method.

[0021] The breaking strength is a tensile strength based on the denier (measured in grams per denier). The breaking strength, LASE@2%, LASE@5%, and breaking energy can each be determined according to ASTM D-885 standard test methods. The term "or more" is to be understood as "at least." A size that has a certain value or more has at least this value. The term "or less" is to be understood as "at most." A size that has a certain value or less has at most this value.

[0022] Physical measured variables, in particular physical measured variables of the tire cord and / or the raw cord of the tire cord and / or the polyester yarn of the tire cord, can be determined before the tire cord is embedded in the carcass ply of the pneumatic vehicle tire.

[0023] Amazingly, this results in a tire cord with a low weight that combines high breaking strength, a high modulus of elasticity, low shrinkage, and high elongation at break. Such a tire cord is ideally suited as a reinforcement for the carcass.

[0024] Thus, according to the invention, a pneumatic vehicle tire is provided whose carcass reinforcements ensure sufficient stability and durability of the tire over a wide range of finenesses, particularly in high-speed use, and enable a reduction in the weight of the tire.

[0025] The polyester yarn consists of at least 90 mol% PET, i.e., has a PET content of at least 90 mol%. The polyester yarn is thus made entirely or partially of PET. The polyester yarn can also have a PET content of 92 mol% or more, preferably 95 mol% or more, particularly preferably 99 mol% or more. The polyester yarn can also be made of 100 mol% PET.

[0026] It has been found that a tire cord according to the invention can be produced by a method comprising the following steps: spinning a molten polyester pellet which contains 90 mol% or more of PET and which has an intrinsic viscosity of 1.0 dl / g or more using a spinning package including a spinneret having a nozzle unit to produce a polyester yarn; producing a raw cord using the polyester yarn; and immersing the raw cord in an adhesive solution and heat-treating the raw cord.

[0027] The step of producing the yarn may specifically include a step of ejecting the polyester pellets through a spinneret including a nozzle unit having a shear rate of 220 to 260 1 / s and a polymer ejection rate of 2.0 m / min or less under the spin pack pressure condition of 1800 to 2500 psi to form a polyester multifilament including a polyester single filament having a fineness of 2.5 to 3.5 denier.

[0028] The tire cord provided according to the method for manufacturing the tire cord can have a breaking strength of 8.0 g / den or more, a LASE@2% of 1.1 g / den or more, and a LASE@5% of 2.5 g / den or less, and a breaking energy of 183 (g / den) mm or more, each determined according to ASTM-D-885 standard test methods, and satisfy a sidewall indentation (SWI) value of 3.6% or less.

[0029] The polyester multifilament can have 200 to 2000 polyester single filaments with a fineness of 2.5 to 3.5 denier.

[0030] The step of producing a polyester yarn may further comprise: a step of ejecting the molten polyester pellets having an intrinsic viscosity of 1.0 dl / g or more through a spinneret including a nozzle unit having a shear rate of 220 to 260 1 / s and a polymer ejection rate of 2.0 m / min or less under the spin pack pressure condition of 1800 to 2500 psi to produce a plurality of filaments; a step of heating the plurality of ejected filaments by a heating unit; a step of cooling the heated filaments by a cooling unit; a step of bundling the plurality of filaments to form a polyester multifilament; a step of drawing the polyester multifilament; and a step of winding the drawn multifilament.

[0031] The step of drawing the polyester multifilament may comprise a step of drawing the polyester multifilament in a total draw ratio of 1.0 to 3.0.

[0032] According to the present disclosure, although a low DPF (denier per filament) is applied during the production of the polyester yarn, the polymer ejection speed at the die can be adjusted to achieve a high spinning tension and a high draw, and at the same time, the ejection pressure from the spin pack can be set high to maintain a high shear rate at the die, thereby maintaining the excellent mechanical properties of the polyester yarn in the tire cord and satisfying all the properties required for weight reduction.

[0033] Therefore, according to the present disclosure, a tire having a tire cord with a low weight can be provided that satisfies both high breaking strength, high elastic modulus, low shrinkage and high breaking elongation.

[0034] The method is suitable for maintaining excellent mechanical-physical properties such as breaking strength and elongation of the polyester yarn by incorporating a polyester yarn produced by applying a high-denier multifilament spinning method that satisfies spinning conditions of low denier per filament, low jet ejection rate, and low shear rate, and by adjusting the spinning pack pressure. It has been found through experiments that incorporating the polyester yarn according to the above method can provide a high-strength tire cord capable of expressing all the physical properties of high elastic modulus and high breaking energy. The present disclosure has been made based on these findings.

[0035] A tire cord is manufactured through a three-step process consisting of yarn production, a twisting process using the yarn, and heat treatment, and it is necessary to maintain the above physical properties of the yarn in the tire cord in order to obtain a product with outstanding performance.

[0036] This means that the yarn undergoes a post-processing process called twisting and heat treatment, during which the yarn's physical properties deteriorate and change. For example, a decrease in strength and breaking energy may occur, and shrinkage and elongation behavior may also be altered. Therefore, it is necessary to maintain the yarn's physical properties even during the post-processing process.

[0037] In order to achieve the intended weight reduction, the tire cords must also meet all three physical properties: a high elastic modulus, high fracture energy, and low and stable shrinkage to replace the existing gauge range.

[0038] According to the invention, the factor that indicates the elastic modulus is LASE (Load At Specific Elongation), and the factor that indicates shrinkage is the sidewall indentation (SWI). Furthermore, it is necessary to adjust the elastic modulus so that it is low over a specific interval for a high fracture energy. This means that even if the elastic modulus is increased, it is necessary to avoid a deterioration of other physical properties, such as fracture energy. For example, it is necessary to control the LASE@5%, which is the value of the elastic modulus determined by the load (g / den) at elongation corresponding to 5% in the tensile load curve obtained by an ASTM-D-885 measurement method.Conventional tire cords do not satisfy all three physical properties, whereas the tire cord of the present embodiment exhibits high breaking strength even after yarn post-processing and satisfies all properties of excellent elastic modulus, excellent breaking energy, and excellent shrinkage.

[0039] Such a tire cord can be provided by incorporating a polyester yarn produced by adjusting the pressure of the spinning package together with a high-count multifilament spinning process.

[0040] The yarn production conditions, in particular, utilize the high-density multifilament spinning process, which means low deniers per filament (DPF), low jet ejection rates, and low shear rates at the jets. However, such manufacturing conditions can lead to a decrease in pressure in the spin pack / spinneret, which is associated with a decrease in the fracture energy of the tire cord.

[0041] This means that the spinning process for high-density multifilaments enables the physical properties of high strength, high elastic modulus, and stable shrinkage of the tire cord, but is accompanied by a decrease in fracture energy (elongation at break). This is due to the conflicting relationship between each property. Therefore, if spinning is performed using a conventional general process, it is extremely difficult to achieve a tire cord that meets all of the desired physical properties.

[0042] In the present description, the invention has been designed to maintain a high breaking energy while applying a high-count multifilament spinning process with specific spinning conditions by simultaneously adjusting the spin pack pressure. Furthermore, the breaking energy limits the elastic modulus range, the LASE@5%, to a specific range.

[0043] The tire cord produced by the above process fulfills all of the aforementioned properties, such as high strength, high elastic modulus, low heat shrinkage, and high elongation, while maintaining the excellent physical properties of the yarn. Thus, a weight-reduced tire with favorable rolling resistance is possible.

[0044] It is therefore possible to improve rolling resistance by reducing the fineness of the tire cord (e.g. from 2000 den to 1500 den or from 3000 den to 2000 den).

[0045] It is also possible to improve the physical properties of the tire, which are usually deteriorated when the fineness of the tire cord is reduced.

[0046] An advantageous embodiment is provided in that the LASE@2% value of the tire cord has a value of 1.15 g / den or more, preferably 1.20 g / den or more, wherein the force is indicated at 2% elongation. An advantageous embodiment is provided in that the LASE@2% value of the tire cord has a value of 1.5 g / den or less, preferably 1.45 g / den or less, particularly preferably 1.4 g / den or less. The LASE@2% value of the tire cord can have a value of 1.1 to 1.5 g / den.

[0047] An advantageous embodiment is provided in that the LASE@5% value of the tire cord has a value of 2.45 g / den or less, preferably 2.4 g / den or less. An advantageous embodiment is provided in that the LASE@5% value of the tire cord has a value of 2.0 g / den or more, preferably 2.05 g / den or more, particularly preferably 2.1 g / den or more. The LASE@5% value of the tire cord can have a value of 2.0 to 2.5 g / den. An advantageous embodiment is provided in that the breaking energy of the tire cord has a value of 200 (g / den)-mm or more, preferably 210 (g / den)-mm or more, determined according to ASTM-D-885 standard test methods.An advantageous embodiment is provided in that the breaking energy of the tire cord has a value of 300 (g / den) mm or less, preferably 280 (g / den) mm or less, particularly preferably 250 (g / den) mm or less, determined according to ASTM D-885 standard test methods. The breaking energy of the tire cord can have a value of 183 (g / den) mm to 300 (g / den) mm.

[0048] The sidewall necking value (SWI value) of the tire cord may be 3.55% or less, preferably 3.4% or less. The sidewall necking value (SWI value) of the tire cord may be 3.0% or more, preferably 3.1% or more, more preferably 3.2% or more, most preferably 3.3% or more. The SWI value of the tire cord may be 3.0% to 3.6%.

[0049] An advantageous embodiment is provided in that the tire cord has a breaking strength of 8.0 g / den to 11 g / den, a LASE@2% value of 1.1 to 1.5 g / den, a LASE@5% value of 2.0 to 2.5 g / den, a breaking energy of 183 (gZden) mm to 300 (gZden) mm and SWI value of 3.0% to 3.6%.

[0050] In the present specification, the residual shrinkage ratio before cooling of (A) and (B) may be a ratio in which the ratio between the length (Lo) measured under an initial tension load selected from the range after the tire cord having a sample length of 250 mm was conditioned for 24 hours at 25°C and 65% relative humidity and the length (Li) measured after treatment for 2 minutes at 180°C under the initial tension load of 0.011 g / den using a shrinkage tester. That is, the length change rate {=[(Lo-Li)Z Lo]X100} of the sample can be defined as the shrinkage rate AL1. Lo and Li can each be measured five times. In addition, the residual shrinkage rate after cooling can be determined using AL2 ({=[(Li - Ls) / Li]X100}) where Ls is the length after 1 minute of cooling at room temperature.

[0051] In addition, the tension loads of (A) and (B) and the loads of (C) and (D) can be measured by appropriately setting the load range within the above range according to the fineness of the tire cord without any fineness discrimination.

[0052] This means that the SWI is not limited to the tire cord gauge range and can be measured by adjusting the load range according to different gauge range conditions and determining the average value. Specifically, the SWI can be defined and adjusted as the respective load according to the tire cord gauge.

[0053] According to one embodiment of the present disclosure, the tire cord may include a raw cord having a total fineness of 1000 to 6000 denier. The initial tension range may be adjusted according to the total fineness of the raw cord included in the tire cord, which is adjusted according to the manufacturing conditions of the yarn.

[0054] Therefore, when the total fineness of the tire cord is set in the range of 3000 denier to 4000 denier, according to the embodiments of the present disclosure, the preload for measuring residual shrinkage (A) may be 35 to 45 g, the preload for measuring residual shrinkage (B) may be 70 to 90 g, the load for measuring elongation (C) may be 2.3 to 3.0 kg, and the load for measuring elongation (D) may be 4.6 to 6.0 kg.

[0055] When the total fineness of the tire cord is set to 2000 denier, 2600 denier, 3000 denier, or 4000 denier, the preload for measuring the residual shrinkage (A) can be 20 g, 30 g, 35 g, or 45 g, respectively. The preload for measuring the residual shrinkage (B) under the above denier conditions can be 40 g, 60 g, 70 g, or 90 g, respectively. Furthermore, the load for measuring (C) under the above denier conditions can be 1.5 kg, 2.0 kg, 2.3 kg, or 3.0 kg, respectively. Furthermore, the load for measuring (D) under the above denier conditions can be 3.0 kg, 4.0 kg, 4.6 kg, or 6.0 kg, respectively.

[0056] In addition, the residual shrinkage rate can be an average of the values ​​from at least 3, preferably at least 4, particularly preferably at least 5, measurements in the respective load range.

[0057] An advantageous embodiment is provided in that the tire cord has a hot shrinkage of less than 4%, preferably less than 3%, particularly preferably less than 2.5%, determined according to ASTM-D-885 standard test method.

[0058] An advantageous embodiment is given by the fact that in equation 1 (A) is 1.0 to 3.2%, (B) is 0.7 to 2.8%, (C) is 1.3 to 1.7% and (D) is 4.2 to 4.6%.

[0059] An advantageous embodiment is provided in that the carcass ply has a ply strength of at least 0.94 kg / dm / den.

[0060] The reinforcing capacity of a tire in specific areas is important for its performance. Therefore, to reduce a tire's weight, the ply strength, which is standardized to the fineness of the reinforcement members, is important. High ply strength enables excellent tire reinforcing capacity. Therefore, high-strength tire cords should be used for excellent tire reinforcing capacity, and the arrangement density of the tire cords should be increased by optimizing the spacing between the tire cords.

[0061] A ply strength of 0.94 kg / dm / den or more thus results in improved tire performance. The ply strength can be determined from the breaking strength of the tire cords according to ASTM-D-885 standard test methods, multiplied by the arrangement density of the tire cords in the ply, and normalized to the tire cord fineness. An advantageous embodiment is achieved by the tire cord having a strength utilization of at least 88% according to the following equation 2:

[0062] [Equation 2] Strength utilization (%) = [Breaking strength of tire cord (g / den) / Breaking strength of polyester yarn (g / den)] x 0.

[0063] Preferably, the tire cord has a strength utilization of 88.5% or more, more preferably 88.7% or more, most preferably 88.9% or more. It is also preferred if the tire cord has a strength utilization of 91.0% or less, more preferably 90.8% or less, most preferably 90.6% or less, and even more preferably 90.4% or less. Thus, the tire cord according to the present disclosure can have outstanding strength.

[0064] The tire cord can, for example, have a strength utilization of 88.5% to 91.0%, preferably of 88.7% to 90.8%, particularly preferably of 88.7% to 90.6%, very particularly preferably of 88.7% to 90.4%, even more particularly preferably of 88.9% to 90.4%.

[0065] In particular, the strength utilization of the tire cord can be at least 90% relative to the strength of the yarn.

[0066] An advantageous embodiment is provided in that the polyester yarn is a polyester multifilament made of 200 to 2000 polyester single filaments, each having a fineness of 2.5 to 3.5 denier; and in that the polyester yarn is impregnated with an adhesive layer.

[0067] The adhesive layer can be formed, in particular, by impregnating the raw cord in a well-known adhesive solution. For example, a resorcinol-formaldehyde latex adhesive solution (RFL adhesive solution) can be used as the adhesive solution for a conventional tire cord. The adhesive layer can be contained in an amount of 0.5 to 10 wt.%, preferably 1 to 8 wt.%, particularly preferably 1.5 to 6 wt.%, of the high-strength tire cord.

[0068] An advantageous embodiment is provided in that the polyester yarn is made from a polyester composition which consists of a molten PET granulate, in that the molten PET granulate comprises at least 90 mol% PET and in that the molten PET granulate has an intrinsic viscosity of at least 1.0 dl / g.

[0069] The molten PET granulate is thus a molten polyester granulate consisting of 90 mol% or more PET and having an intrinsic viscosity of 1.0 dl / g or more. The molten PET granulate can also contain 92 mol% or more, preferably 95 mol% or more, particularly preferably 99 mol% or more, and most particularly preferably 100 mol% PET.

[0070] If the molten PET pellets are less than 100% PET, various known additives can be added during the step of preparing the polyester composition that forms the undrawn yarn. Therefore, the type of additive is not limited.

[0071] In one embodiment, the molten PET granules may have an intrinsic viscosity of 1.0 dl / g or more, preferably from 1.1 dl / g to 1.9 dl / g. The molten PET granules may preferably have an intrinsic viscosity of 1.0 dl / g or more, preferably 1.1 dl / g or more. The molten PET granules may further have an intrinsic viscosity of 1.7 dl / g or less, preferably 1.6 dl / g or less, more preferably 1.5 dl / g or less, most preferably 1.4 dl / g or less. According to one embodiment of the invention, the polyester yarn can be produced into a PET-drawn yarn by a spinning process using granules consisting of 90 mol% or more PET.

[0072] Specifically, the PET-drawn yarn is produced by melt-spinning a PET pellet to produce an undrawn fiber and then drawing the undrawn fiber. Additionally, the PET tire cord can be produced as a dipped cord type by producing the PET-drawn yarn by twisting the PET-drawn yarns and dipping them in an adhesive solution.

[0073] Furthermore, according to one embodiment of the present invention, the PET-drawn yarn contains 90 mol% or more of PET to exhibit the properties of PET suitable for tire cord. If the PET-drawn yarn contains less than 90 mol% of PET, it is difficult for the PET-drawn yarn and the tire cord produced therefrom to have desirable physical properties.

[0074] Therefore, the term "PET" in this disclosure means a PET content of at least 90 mol%, unless otherwise explained in this disclosure.

[0075] An advantageous embodiment is provided in that the polyester yarn has a breaking strength of 7.5 to 11.0 g / den and an elongation at break of 10 to 20%.

[0076] An advantageous embodiment is provided in that the raw cord of the tire cord has a total fineness of 1000 to 9000 denier, preferably of 1000 to 6000 denier.

[0077] An advantageous embodiment is provided by the tire cord having a breaking strength of greater than 8.2 g / den, particularly preferably greater than 8.4 g / den, particularly preferably greater than 8.5 g / den. An advantageous embodiment is also provided by the tire cord having a breaking strength according to ASTM-D-885 standard test method of 11 g / den or less, preferably 10.0 g / den or less. The breaking strength of the tire cord can in particular be between 8.0 g / den and 11 g / den.

[0078] An advantageous embodiment is provided in that the tire cord comprises exactly two or exactly three polyester yarns, preferably exactly two polyester yarns, with the polyester yarns being secondarily twisted together. The tire cord thus has the construction x2 or x3, preferably x2.

[0079] An advantageous embodiment is provided in that the tire cord has a total fineness of 2500 den to 4500 den, preferably 3000 den to 4000 den.

[0080] An advantageous embodiment is provided by the polyester yarn having a fineness of 1500 den to 2000 den.

[0081] It has been found to be particularly advantageous if the tire cord has a construction of 1500 den x 2 or 2000 den x 2.

[0082] The raw cord of tire cord can be produced by feeding the drawn polyester yarn into a cable cord twister and twisting the yarn primarily and secondarily at a twist count of 200 to 500 TPM each. Tire cord (impregnated cord) can be produced by immersing the raw cord in an adhesive coating solution, followed by drying and heat treatment.

[0083] The pneumatic vehicle tire according to the invention is preferably a tire for a passenger car, a van, or a light truck. It is preferably a radial tire.

[0084] The pneumatic vehicle tire is manufactured in a manner known to those skilled in the art using devices known to those skilled in the art. In particular, an unvulcanized blank of an unvulcanized pneumatic vehicle tire, comprising the carcass with the tire cords as the reinforcement, including all described embodiments, is first prepared by stacking the corresponding components, which comprise unvulcanized rubber mixtures, on top of one another. The blank is then vulcanized.

[0085] The invention encompasses all advantageous embodiments, which are reflected, inter alia, in the patent claims. In particular, the invention also encompasses embodiments resulting from the combination of different features with varying degrees of preference, so that a combination of a first feature designated as "preferred" with another feature designated, for example, as "particularly preferred" is also encompassed by the invention.

[0086] A method for producing a tire cord according to the invention may comprise the following steps: spinning a molten polyester pellet comprising at least 90 mol% PET having an intrinsic viscosity of 1.0 dl / g or more by using a spin pack including a spinneret having a nozzle unit to produce a polyester yarn; producing a raw cord using the polyester yarn; and immersing the raw cord in an adhesive solution and heat-treating the cord. The step of producing the polyester yarn may include a step of ejecting the molten polyester pellets through a spinneret, the spinneret including a nozzle unit having a shear rate of 220 to 260 1 / s and a polymer ejection rate of 2.0 m / min or less under the spin pack pressure condition of 1800 to 2500 psi, to form polyester single filaments having a fineness of 2.5 to 3.5 denier.

[0087] To produce a tire cord that meets the properties of high breaking strength, high elastic modulus, low shrinkage, and high elongation, a low DPF of the polyester yarn is advantageous. In the present disclosure, the polymer ejection speed from the die and a low DPF for the polyester can be adjusted to achieve high spinning tension and high draw.

[0088] Furthermore, under yarn production conditions, the fracture energy of the polyester yarn and tire cord can be reduced due to the low nozzle discharge pressure. Therefore, the present disclosure has the feature of setting a high discharge pressure in the spin pack, so that the shear rate at the nozzle can be maintained high.

[0089] Therefore, the present disclosure has the feature that by adjusting the spinning conditions while maintaining the spinning pack pressure in a certain range, the physical properties of the polyester yarn can be excellently maintained in the tire cord after the yarn has undergone the post-treatment of twisting and heat treatment, thereby satisfying all the physical properties of the tire cord required for weight reduction.

[0090] The tire cord can otherwise be produced by a conventional process, except for adjusting the spinning process and the pressure condition of the spinning package in the production of the polyester yarn.

[0091] As described above, in particular, a high-strength polyester yarn for a tire cord can be produced by spinning a molten polyester pellet comprising at least 90 mol% of PET having an intrinsic viscosity of 1.0 dl / g or more by using a spinning package having a spinneret including a nozzle unit.

[0092] In one illustrative embodiment, the molten polyester granulate may include molten PET granulate comprising at least 90 mol% PET, which has an intrinsic viscosity of 1.0 dl / g or more, preferably from 1.1 dl / g to 1.9 dl / g. The molten PET granulate may preferably have an intrinsic viscosity of 1.0 dl / g or more, preferably of 1.1 dl / g or more. The molten PET granulate may further have an intrinsic viscosity of 1.7 dl / g or less, preferably of 1.6 dl / g or less, more preferably of 1.5 dl / g or less, most preferably of 1.4 dl / g or less.

[0093] The molten PET pellets may also contain 92 mol% or more, preferably 95 mol% or more, more preferably 99 mol% or more, most preferably 100 mol% PET. If the molten PET pellets are less than 100% PET, various known additives can be added in the step of preparing the polyester composition that forms the undrawn yarn. Therefore, the type of additive is not limited.

[0094] In addition, spinning may be carried out in a spinneret having a spinneret orifice number of 200 to 550 at 270 to 300°C, preferably at 275 to 300°C, particularly preferably at 275 to 290°C.

[0095] The step of producing the polyester yarn may further include, after the step of producing the plurality of filaments, a step of heating and cooling the plurality of ejected filaments, bundling the cooled filaments, and then drawing the filaments to produce a drawn polyester yarn and thereafter winding the same.

[0096] The method for producing a polyester yarn may preferably comprise: a step of ejecting the molten polyester pellets having an intrinsic viscosity of 1.0 dl / g or more through a spinneret including a nozzle unit having a shear rate of 220 to 260 1 / s and a polymer ejection rate of 2.0 m / min or less under the spin pack pressure condition of 1800 to 2500 psi to produce a plurality of filaments; a step of heating the plurality of ejected filaments by a heating unit; a step of cooling the heated filaments by a cooling unit; a step of bundling the plurality of filaments to form a polyester multifilament; a step of drawing the polyester multifilament; and a step of winding the drawn multifilament.

[0097] The high-strength polyester yarn can be produced, for example, by a process comprising: a step of melting and ejecting PET pellets containing at least 90 mol% PET and having an intrinsic viscosity of 1.0 dl / g or more, preferably 1.1 dl / g or more, particularly preferably 1.5 dl / g or more, through a nozzle unit into a plurality of filaments by adjusting spinning conditions and spin pack pressure under conditions within the ranges described above; a step of heating the plurality of heated filaments by a heating unit positioned around the nozzle unit; a step of cooling the plurality of heated filaments by a cooling unit; a step of bundling the plurality of filaments to form a polyester multifilament; a step of drawing the polyester multifilament;and a step of winding the drawn multifilament.;

[0098] At this time, the spin pack can adjust the discharge pressure range to 1800 to 2500 psi (approximately 126.55 to 175.8 kgf / cm2). However, if the spin pack discharge pressure is 1800 psi or less, the polymer discharge velocity at a nozzle may decrease, making it impossible to achieve the required performance. If the discharge pressure is 2500 psi or more, equipment problems such as pack leakage may occur due to excessive pressure.

[0099] Further, when the molten polyester pellets are ejected through the die including the die unit, the shear rate at the die may be 220 to 260 1 / s. If the shear rate is 220 1 / s or less, the orientation of the polymer in the die may decrease, which may reduce the breaking energy of the yarn. If the shear rate is 260 1 / s or more, a reduction in the yarn tension may impair the dimensional stability of the yarn. The polymer ejection speed at the die may be further reduced to 2.0 m / min or less along with the shear rate adjustment at the die. The polymer ejection speed at the nozzle can be in particular 0.1 to 2.0 m / min, preferably 0.5 to 2.0 m / min, particularly preferably 1.0 to 2.0 m / min, very particularly preferably 1 to 1.9 m / min, even more preferably 1.3 to 1.9 m / min, even more preferably 1.5 to 1.9 m / min.If the polymer ejection speed is 2 m / min or more, the polymer ejection speed at the nozzle may decrease, so that the required performance cannot be achieved.

[0100] Through this process, a polyester multifilament can be formed that includes a polyester single filament having a fineness of 2.5 to 3.5 denier. That is, according to the present disclosure, it is determined that a polyester multifilament is formed that includes a polyester single filament with a DPF of 2.5 to 3.5.

[0101] The polyester multifilament may contain 200 to 2,000 polyester single filaments having a fineness of 2.5 to 3.5 denier, preferably 400 to 1,200 corresponding polyester single filaments. The fineness of the polyester single filaments may preferably be 2.6 to 3.5 denier, particularly preferably 2.7 to 3.4 denier.

[0102] Meanwhile, in the method for producing the polyester yarn, a process of heating and cooling a plurality of discharged filaments, bundling the cooled filaments, and then drawing the filaments to produce a drawn polyester yarn, and then winding the yarn in a conventional manner may be carried out.

[0103] Further features, advantages and details of the invention and the method for producing the tire cord will now be explained in more detail with reference to the schematic drawing.

[0104] Fig. 1 shows a polyester yarn production facility. As shown in Fig. 1, the polyester yarn production facility 1 according to the embodiment of the present disclosure includes an extruder 10, a spinning pack 20, a cooling unit 30, a bundling unit 40, a drawing unit 50, and a winding unit 60.

[0105] A hopper 12 may be formed on top of the extruder 10 to receive the supply of polymer granules (arrow), and a heater and a transport device are provided within the extruder 10 to melt the polymer granules supplied through the hopper 12 and to transport the molten granules into the spin pack 20. Polyester may be used as the polymer, but is not limited to this.

[0106] For convenience of description, a yarn production device 1 capable of producing a polyester yarn using polyester pellets will be described below as an example. However, the yarn production device according to the embodiment of the present disclosure is not only used for the production of a polyester yarn, but can also be used for the production of other yarns known in the art.

[0107] In addition, the spinning pack 20 expels the molten polyester pellets transported from the extruder to form a plurality of filaments 2. The spinning pack 20 may include a spinning block, a pack body, a spinneret, and a heating unit, but its configuration is not limited thereto.

[0108] The apparatus for producing the polyester yarn may specifically include: a spinning pack including a spinneret having a nozzle unit with a plurality of ejection orifices for ejecting the molten granules; a heating unit positioned around the nozzle unit for heating a plurality of filaments ejected through a plurality of ejection orifices; a cooling unit for cooling the plurality of filaments heated by the heating unit; a bundling unit for bundling a plurality of filaments cooled by the cooling unit to form a multifilament; and a drawing unit for drawing the multifilament. The plurality of ejection orifices may be arranged in a circle in at least two or more rows.A distance between adjacent ejection ports in any one of the rows, a distance between adjacent ejection ports in any other row, and a distance between any one row and ejection ports disposed close to each other in any other row adjacent to any one row.

[0109] In the present disclosure, a general method for cooling the filament 2 by the cooling unit 30 may be used, but is not limited thereto.

[0110] In the present disclosure, a coolant, e.g., air, is introduced into the cooling chamber 32 through the coolant inlet 34 and may escape through the coolant outlet 36.

[0111] The high-strength polyester yarn for tire cord can be further produced by a method comprising a step of drawing the undrawn multifilament 4 in at least two stages including three or more godets 52, 54, 56, and 58. Currently, the at least three or more godets include a first, a second, and a third godet arranged sequentially based on the direction of travel of the multifilament, wherein the rotation speed of the first godet is 2000 to 4000 m / min and the rotation speed of the third godet is 5000 to 7000 m / min.

[0112] The step of drawing the polyester multifilament may include a step of drawing the polyester multifilament at a total draw ratio of 1.0 to 3.0, and a drawn polyester yarn can be produced by the above method. The total draw ratio may preferably be between 1.5 and 3.0 or between 1.5 and 2.5. That is, in order to increase the degree of orientation by drawing and thus have an appropriate strength level, the total draw ratio of the drawn polyester yarn is preferably 1.0 or more. However, in order to prevent yarn breakage due to excessive drawing, the total draw ratio of the drawn polyester yarn is preferably 3.0 or less.

[0113] The multi-stage draw speed ratio may further be defined as the ratio of the difference between the rotational speed of the first godet and the rotational speed of the second godet and the difference between the rotational speed of the second godet and the rotational speed of the third godet, wherein the multi-stage draw speed ratio may be between 30:70 and 60:40.

[0114] In the winding unit 60, the polyester yarn 6 is produced by winding the multifilament drawn by the drawing unit 50.

[0115] The high-strength polyester yarn produced according to the above process can have a breaking strength of 7.5 to 11.0 g / den and an elongation at break of 10 to 20%.

[0116] To produce a raw cord, the yarns can be twisted in a primary process, and the twisted yarns can be cabled into a cord (raw cord) in a secondary process. This can be done in a single-stage process on a direct cabling machine or in two consecutive individual stages on a ring twister. The twist can range from 200 to 500 TPM.

[0117] Further, the step of immersing the raw cord in an adhesive solution and heat-treating the yarn may be a step of immersing the raw cord in an adhesive solution followed by heat treatment to produce a tire cord (impregnated cord).

[0118] In particular, the adhesive layer can be formed by impregnating the raw cord in a generally known adhesive solution, wherein, for example, a resorcinol formaldehyde latex adhesive solution (RFL adhesive solution) can be used as the adhesive solution for a conventional tire cord.

[0119] After impregnation with the adhesive solution, a heat treatment step can be performed. The heat treatment step can be carried out for 90 to 360 seconds at a temperature of 220 to 260°C, preferably for 90 to 240 seconds at a temperature of 230 to 250°C, and more preferably for 90 to 120 seconds at a temperature of 240 to 245°C.

[0120] By immersing the high-strength polyester yarn in an adhesive solution and heat-treating the yarn under these conditions, the dimensional stability of the tire cord can be further improved and the change in physical properties during tire vulcanization can be further reduced.

[0121] Hereinafter, the present disclosure will be described in more detail with reference to examples and comparative examples. The following examples and comparative examples are only intended to aid understanding of the present

[0122] disclosure, but should not be construed as limiting the scope of this disclosure.

[0123] Further features, advantages and details of the invention and of the method for producing the tire cord will now be explained in more detail with reference to examples which may represent embodiments and reference examples.

[0124] [Examples and comparative examples: Production of a polyester yarn]<Beispiel 1>

[0125] For Example 1, a polyester yarn 6 comprising at least 90 mol% or more of PET and having a single filament fineness of the polyester single filaments of 2.7 to 3.4 denier and a total fineness of 1500 denier was produced using the yarn production device 1 shown in Fig. 1. Specifically, PET pellets containing at least 90 mol% of PET and having an intrinsic viscosity (IV) of 1.0 to 1.4 dl / g were melted with a single-screw extruder to produce molten polyester pellets. As described in Table 1, the molten polyester pellets were then spun through a spinneret 170 (L / D = 4.0 / 1.0, number of orifices: 500) at a spinning speed of 3200 m / min to produce a plurality of filaments 2.

[0126] At this time, the conditions for producing a variety of filaments including the spinneret throughput speed were adjusted as shown in Table 2 (DPF, polymer ejection speed at the nozzle, shear rate at the nozzle, spin pack pressure).

[0127] Thereafter, the plurality of filaments 2 were heated by a heating unit, then the plurality of filaments were cooled in the cooling unit 30, and the cooled filaments were bundled to produce an undrawn multifilament 4 (an undrawn yarn).

[0128] The melt for spinning was extruded through the spinneret to obtain a drawn polyester yarn having a total fineness of 1000 denier (individual fineness of approximately 4 denier per filament). The process of obtaining the drawn polyester yarn was carried out at a spinning temperature of 290°C, a spinning speed of 3200 m / min, a total draw ratio of 1.5, and a recovery rate of 1.5% (heat treatment at 180°C after drawing).

[0129] The drawn multifilament was wound to produce a polyester yarn (drawn yarn).

[0130] < Reference Example 1>

[0131] A polyester yarn was produced in the same manner as in Example 1 except that the spinneret diameter, the number of orifices, the spinning conditions and the spin pack pressure were changed as shown in Tables 1 and 2 below.

[0132] [Table 1 ]

[0133] [Table 2]

[0134] [Example 2 and Reference Example 2: Production of a tire cord

[0135] The tire cords of Example 2 and Reference Example 2 were each produced using the polyester yarns produced in Example 1 and Reference Example 1 under the same conditions.

[0136] Specifically, the polyester yarn was placed in a twister, two strands of primary twisted yarns (Z-direction) were produced, each having a twist number of 460 TPM. Then, the two primary twisted yarns were secondarily twisted (S-direction) together with a twist number of 460 TPM to produce a raw cord. The thus-produced raw cord was immersed in an adhesive solution containing a resorcinol-formaldehyde latex (RFL), then dried at 150°C for 100 seconds and heat-treated at 240°C for 100 seconds to form a tire cord (impregnated cord). The tension applied to the raw cord during the immersion, drying, and heat-treatment processes was 0.5 kg / cord.

[0137] In addition, the total fineness of the raw cord showed a value of 1000 to 6000 denier.

[0138] [Experimental Example A: Evaluation of physical properties of a polyester yarn and a tire cord]

[0139] The breaking strength and elongation at break were measured for polyester yarns produced according to the above explanations and for tire cords using the polyester yarns.

[0140] Tensile strength, elongation at break and elongation

[0141] According to ASTM-D-885 standard test methods, the breaking strength (g / den), elongation, and strength ratio of the drawn polyester yarn and tire cord were measured using a universal testing machine according to Equation 2, and the results are shown below in Tables 3 and 4. The sample length was 250 mm, the tensile speed was 300 mm / min, and the initial load was set to 0.05 g / den.

[0142] In the stress-strain curve obtained from the above test, the strain was determined at a load of 4.5 g / den. [Table 3]

[0143] [Table 4]

[0144] Referring to Tables 3 and 4, the polyester yarns of Example 1 and the tire cords of Example 2 utilize the demonstrated outstanding physical properties, which show improved properties compared to the respective Reference Example.

[0145] [Experimental Example B: Evaluation of physical properties of tire cords]

[0146] The physical properties of ultimate tensile strength, elastic modulus, fracture energy, and SWI were measured for tire cords manufactured in the examples and reference examples. The results are shown below in Table 5.

[0147] (1 ) Fracture strength and fracture energy

[0148] According to ASTM D-885 standard test methods, the ultimate tensile strength (g / den), elongation (%), and fracture energy of the tire cord were determined using a universal testing machine. The specimen length was 250 mm (cord length: 600 mm), the tensile rate was 300 mm / min, and the initial load was set at 0.05 g / den. (2) Elastic modulus (LASE@2%, LASE@5%)

[0149] A stress-strain curve was obtained according to ASTM D885 standard test methods. Using this stress-strain curve, loads were obtained when the elongation was at 2% and 5%, respectively, and the LASE@5% was measured during elongation. The sample before measurement was measured after being left in an atmosphere of 20°C and 65% relative humidity for 24 hours.

[0150] (3) SWI

[0151] The SWI was determined according to equation 1 according to claim 1. Furthermore, (A) may be 1.0 to 3.2%, (B) may be 0.7 to 2.8%, (C) may be 1.3 to 1.7%, and (D) may be 4.2 to 4.6%.

[0152] Specifically, the 250 mm sample, which had a total fineness of 1000 to 6000 denier, was left at 25°C and 65% relative humidity for 24 hours, and then the length (Lo) was measured under an initial tension load of 0.01 g / denier. The sample was then treated for 2 minutes at 180°C using a shrinkage tester under an initial tension load of 0.01 g / denier, and then the length (Li) of the sample was measured. Lo and Li were each measured three times. The length change rate {=[(Lo-Li) / Lo] x 100} of the sample was defined as the shrinkage rate DL1 before cooling.

[0153] Furthermore, the residual shrinkage of the sample was measured using a shrinkage tester. Afterward, the sample was removed from the oven under constant load and cooled at room temperature (25°C) for approximately 1 minute. Afterward, the residual shrinkage was measured in a state where the cord was stable. That is, the residual shrinkage after cooling represents the residual shrinkage rate of AL2({=[(Li-Ls) / Li]×100}), where the length (Ls) was measured 1 minute after cooling. [Table 5]

[0154] Referring to Table 5, the tire cords of Example 2 exhibit a breaking strength of 8.0 g / den or more, a LASE@2% of 1.1 g / den or more, a LASE@5% of 2.5 g / den or less, and a breaking energy of 183 (g / den) mm or more, as determined according to ASTM D-885 Standard Test Method, and satisfy a SWI value of 3.6% or less. This means that the tire cord of Example 2 exhibits a high elastic modulus, low shrinkage, and high elongation effects, meaning that the tire cord maintains excellent strength even after the yarn post-treatment process. This demonstrates advantageous properties compared to Reference Example 2.

[0155] In Reference Example 2, the stretching was lower than the inventive range of the present disclosure, the DPF was not less than 3.9, and the fracture energy value was not more than 175.0 (g / den) mm. Furthermore, in Reference Example 2, the LASE@2% value was 1.0%, which was lower than Example 2, thereby limiting the improvement in the elastic modulus.

[0156] When producing a yarn for providing tire cords, it is therefore necessary to adjust the spin pack pressure while applying the high-count multifilament spinning process with specified spinning conditions so that all physical properties are excellent and, in particular, the breaking energy can be kept high. The ply strength is given for an arrangement density of the respective strengthening elements in a carcass ply of 180 epdm ("ends per dm"). The ply strength is greater for a corresponding carcass ply comprising the tire cords according to Example 2 than for a corresponding carcass ply comprising the cords according to Reference Example 2. The ply strength can be determined from the breaking strength of the tire cords according to ASTM-D-885 Standard Test Method, multiplied by the arrangement density of the tire cords in the ply and normalized to the fineness of the tire cords.

[0157] [Tire examples: Rolling resistance rating]

[0158] Pneumatic tires for vans were built and tested. The tires differ only in the type and arrangement density of the reinforcements in the carcass ply. The arrangement density is chosen so that the cord-to-cord spacing of the carcass plies of the two tires is comparable. The carcass reinforcements consist of exactly two polyester yarns, which are secondarily twisted together, giving the tire cord a x2 construction.

[0159] The carcass reinforcements of the reference tires have a 2000 denier x 2 construction. The polyester yarns are conventional PET multifilament yarns with a count of 2000 denier. The carcass reinforcements of the reference tires are arranged in the carcass ply at a density of 105 epdm.

[0160] Example tires 1 are constructed according to the invention and feature tire cords according to the invention in their carcass ply as carcass strength members. The tire cords according to the invention have a 1500 denier x2 construction and are arranged in the carcass ply with an arrangement density of 118 epdm. The tire cord of the example tires can be the cord according to Example 2. [Table 6]

[0161] Table 6 shows the physical properties of the carcass cords of the tires as well as the respective ply strength of each carcass ply.

[0162] The properties are also standardized to the diameter (in mm) and / or the ply density (in epdm). Reducing the diameter and the associated reduction in ply thickness is key to improving rolling resistance. The ply density is selected so that the cord-to-cord spacing in the carcass plies of the two tires is comparable.

[0163] With the tire cord of the example tire according to the invention, a significantly higher breaking strength per cord as well as a significantly higher ply strength is achieved, which enables the reduction of the cord diameter, which in turn leads to better rolling resistance, see Table 7.

[0164] Tire tests were conducted on the tires, and it was found that the durability and high-speed performance of the compared tires are approximately at the same level. The thickness of the carcass reinforcements of the example tire is reduced compared to the reference tire. Table 7 shows that the rolling resistance of the example tires is advantageously improved by 1.5% compared to the reference tire of the respective example.

[0165] Values ​​greater than 100% correspond to a lower, i.e. improved, rolling resistance (RR).

[0166] [Table 7] Although preferred embodiments of the present disclosure have been described above, the present disclosure is not limited thereto. The embodiments of the present invention include all modifications within the scope that can be easily modified by a person skilled in the art to which the present disclosure belongs and is recognized as equivalent.

[0167] List of reference symbols

[0168] 1 polyester yarn production facility

[0169] 2 filaments

[0170] 4 non-drawn multifilament

[0171] 6 polyester yarn

[0172] 10 extruders

[0173] 12 funnels

[0174] 20 spinning packages

[0175] 30 cooling units

[0176] 32 Cooling chamber

[0177] 34 Coolant inlet

[0178] 36 Coolant outlet

[0179] 40 Bundling unit

[0180] 50 stretching unit

[0181] 52, 54,56,58 Galette

[0182] 60 changing unit

Claims

Patent claims 1. Pneumatic vehicle tire with a carcass which extends from one bead area to the other bead area and is anchored there by wrapping tensile bead cores, wherein the carcass has at least one carcass ply with reinforcements embedded in elastomeric material, arranged parallel and spaced from one another, wherein the reinforcements are each designed as tire cord comprising at least one polyester yarn (6) which consists of at least 90 mol% of polyethylene terephthalate (PET), characterized in that the tire cord • a tenacity of at least 8.0 g / den and • a LASE@2% of at least 1.1 g / den and • a LASE@5% of maximum 2.5 g / den and • a breaking energy (toughness) of at least 183 (g / den) mm, each determined according to the ASTM-D-885 standard test method, • and a value of sidewall indentation (SWI: Side Wall Indentation) of at most 5%, preferably of at most 4%, particularly preferably of at most 3.6%, wherein the sidewall indentation SWI is given by the following equation 1: [Equation 1 ] SWI (%) = [(D)-(C)] + [(A) - (B)], where in equation 1: • (A) is a residual shrinkage of the tire cord, which is measured after measuring the hot shrinkage using a shrinkage tester (at a sample length of 250 mm, at 180°C and 2 minutes exposure time, measured under a preload of 20 to 45 g) and then allowing to cool for 1 min., • (B) is a residual shrinkage of the tire cord, which is measured after measuring the hot shrinkage using a shrinkage tester (at a sample length of 250 mm, at 180°C and 2 minutes exposure time, measured under a preload of 40 to 90 g) and then cooling for 1 minute, • (C) is an elongation of the tire cord at a load of 1.5 to 3.0 kg, measured according to ASTM-D-885 standard test method, and • (D) is an elongation of the tire cord under a load of 3.0 to 6.0 kg, measured according to ASTM-D-885 standard test method.

2. Pneumatic vehicle tire according to claim 1, wherein the tire cord has a hot shrinkage of less than 4%, preferably less than 3%, more preferably less than 2.5%, determined according to ASTM-D-885 standard test method.

3. Pneumatic vehicle tyre according to one or more of the preceding claims, characterized in that (A) is 1.0 to 3.2%, (B) is 0.7 to 2.8%, (C) is 1.3 to 1.7% and (D) is 4.2 to 4.6%.

4. Pneumatic vehicle tire according to one or more of the preceding claims, characterized in that the carcass ply has a ply strength of at least 0.94 kg / dm / den.

5. Pneumatic vehicle tire according to one or more of the preceding claims, characterized in that the tire cord has a strength utilization of at least 88% according to the following equation 2: [Equation 2] Strength utilization (%) = [Breaking strength of tire cord (g / den) / Breaking strength of polyester yarn (g / den)] x 0.

6. Pneumatic vehicle tire according to one or more of the preceding claims, characterized in that the polyester yarn (6) is a polyester multifilament made of 200 to 2000 polyester individual filaments, each having a fineness of 2.5 to 3.5 den, and in that the polyester yarn is impregnated with an adhesive layer.

7. Pneumatic vehicle tire according to one or more of the preceding claims, characterized in that the polyester yarn (6) is made from a polyester composition consisting of a molten PET granulate, that the molten PET granulate has at least 90 mol% PET and that the molten PET granulate has an intrinsic viscosity of at least 1.0 dl / g.

8. Pneumatic vehicle tire according to one or more of the preceding claims, characterized in that the polyester yarn (6) has a breaking strength of 7.5 to 11.0 g / den and an elongation at break of 10 to 20%.

9. Pneumatic vehicle tire according to one or more of the preceding claims, characterized in that the raw cord of the tire cord has a total fineness of 1000 to 9000 denier, preferably 1000 to 6000 denier.

10. Pneumatic vehicle tire according to one or more of the preceding claims, characterized in that the breaking strength of the tire cord is greater than 8.2 g / den, particularly preferably greater than 8.4 g / den, particularly preferably greater than 8.5 g / den.

11. Pneumatic vehicle tire according to one or more of the preceding claims, characterized in that the tire cord has exactly two or exactly three of the polyester yarns, preferably exactly two of the polyester yarns, wherein the polyester yarns are secondarily twisted together.

12. Pneumatic vehicle tire according to one or more of the preceding claims, characterized in that the tire cord has a total fineness of 2500 den to 4500 den, preferably 3000 den to 4000 den.

13. Pneumatic vehicle tire according to one or more of the preceding claims, characterized in that the polyester yarn (6) has a fineness of 1500 den to 2000 den.

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