Pneumatic vehicle tire having carcass

Abstract

A vehicle pneumatic tire having a carcass wherein the carcass comprises at least one carcass ply having strength members wherein the strength members are each in the form of a tire cord comprising at least one polyester yarn consisting of polyethylene terephthalate (PET) to an extent of at least 90 mol%. The strength members of the carcass should make it possible to achieve sufficient stability and durability of the tire over a wide range of fineness, in particular during high-speed operation, and allow the weight of the tire to be reduced. This is achieved when the tire cord has a breaking strength of at least 8.0 g / den and a LASE at 2% of at least 1.1 g / den and a LASE at 5% of at most 2.5 g / den and a toughness of at least 183 (g / den) mm and a sidewall depression value of at most 5%.

Description

TECHNICAL FIELD

[0001] The present invention relates to a vehicle pneumatic tire comprising a carcass extending from one bead area to another bead area and anchored in the other bead area by being wrapped around a high strength bead core, wherein the carcass comprises at least one carcass ply having parallel and mutually spaced strength members embedded in an elastomeric material, wherein the strength members are in each case in the form of a tire cord comprising at least one polyester yarn which consists to an extent of at least 90 mol% of polyethylene terephthalate (PET). BACKGROUND

[0002] A vehicle pneumatic tire generally comprises a gas-impermeable inner layer, a carcass comprising strength members which extend from a crown area of the tire via a sidewall into a bead area and are anchored in the bead area by being wrapped around a high strength bead core, a radially outwardly arranged tread with tread pattern, and a belt band which is arranged between the tread and the carcass.

[0003] The carcass has one or more carcass plies.

[0004] The strength members of the carcass ply are embedded in a rubber compound during production, for example by calendering, in order to be used as rubberized strength member ply in the tire. The carcass must exhibit sufficient strength in order to be able to sufficiently absorb forces occurring during operation of the tire and to show durability. The carcass in particular provides resistance to internal pressure of the tire. The strength members of the carcass are typically arranged at a small angle of at most 10° to the radial direction in the area of the sidewall.

[0005] It is known to employ tire cords made of polyester as strength members of the carcass. Two or more polyester multifilament yarns are finally twisted together to form a cord. Cords made of high modulus low shrinkage PET (HMLS-PET) have proven to be particularly suitable. For example, it is known to use HMLS-PET 2000 den x 2 and 3000 den x 2 for the carcass.

[0006] Tire cords are produced using industrial yarns, for example polyester yarns. Very generally, a polyester yarn can be produced by melting polyester granulate, extruding the molten polyester using a spinneret to form filaments, cooling the semi-solid filaments extruded from the spinneret, and bundling, drawing and winding the cooled filaments.

[0007] Optimizing the rolling resistance is the focus of the current work. For this purpose, it is advantageous to use strength members of the finest possible strength. However, the strength members of the carcass must continue to meet the different requirements for the carcass as their fineness and thus their diameter is reduced. The tire must continue to meet the requirements in terms of stability and durability, especially in high-speed operation.

[0008] In the case of a reduction in the fineness of the carcass strength members, the requirements for the physical properties tenacity, modulus of elasticity, tenacity and shrinkage must also be met. However, this has not yet been achieved for current PET strength members or their production processes with commercially available strength. SUMMARY

[0009] It is the object of the present invention to provide a vehicle pneumatic tire whose carcass strength members make it possible to impart sufficient stability and durability to the tire, especially in high-speed operation, over a wide range of fineness and to achieve a weight reduction of the tire.

[0010] This is achieved when the tire cord has:

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

[0012] an LASE@2% of at least 1.1 g / den, and

[0013] an LASE@5% of at most 2.5 g / den, and

[0014] a tenacity of at least 183 (g / den)·mm,

[0015] each in the respective case determined according to the standard test method ASTM-D-885,

[0016] and a sidewall indentation (SWI) value of no more than 5%, preferably no more than 4%, particularly preferably no more than 3.6%,

[0017] wherein the sidewall indentation SWI is given by the following equation 1 :

[0018] [Equation 1] SWI (%) = [(D) - (C)] + [(A) - (B)]

[0019] wherein in equation 1 :

[0020] (A) is the residual shrinkage of the tire cord measured after the measurement of the heat shrinkage using a shrinkage tester (measured at a sample length of 250 mm, at 180°C and 2 minutes of exposure time, at an initial load of 20 g to 45 g) and subsequently allowed to cool for 1 minute,

[0021] (B) is the residual shrinkage of the tire cord measured after the measurement of the heat shrinkage (measured at a sample length of 250 mm, at 180 °C and an exposure time of 2 minutes, at an initial load of 40 g to 90 g) using a shrinkage tester and subsequently allowing to cool for 1 minute,

[0022] (C) is the elongation of the tire cord under a load of 1.5 kg to 3.0 kg measured according to the standard test method ASTM-D-885, and

[0023] (D) is the elongation of the tire cord under a load of 3.0 kg to 6.0 kg measured according to the standard test method ASTM-D-885.

[0024] Toughness is the toughness related to the fineness (measured in g / denier). Toughness, LASE@2%, LASE@5% and tenacity can be determined in each case according to the standard test method ASTM-D-885.

[0025] The term "or more" is to be understood as meaning "at least". Thus, an amount which covers a certain value or more is to be understood as including at least this value. The expression "or less" is to be understood as meaning "at most". Thus, an amount which covers a certain value or less is to be understood as including at most this value.

[0026] The physical measurement values, in particular the physical measurement values of the tire cord, and / or the physical measurement values of the original cord of the tire cord, and / or the physical measurement values of the polyester yarn of the tire cord, can be determined before embedding the tire cord in the carcass ply of a vehicle pneumatic tire.

[0027] Thus, surprisingly, a low-weight tire cord is provided which not only achieves a high toughness, a high modulus of elasticity and a low shrinkage, but also a high elongation at break. This tire cord is very suitable as a strength member of a carcass.

[0028] Accordingly, the present application provides a vehicle pneumatic tire, the strength member of the carcass of which provides sufficient stability and durability to the tire over a wide fineness range, in particular in high-speed operation, and makes it possible to achieve a weight reduction of the tire.

[0029] The polyester yarn consists to an extent of at least 90 mol% of PET, thus has a PET content of at least 90 mol%. Thus, the polyester yarn is formed wholly 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 formed to an extent of 100 mol% of PET.

[0030] It has been found that the tire cord according to the present application can be produced by a process including the steps of: spinning molten polyester pellets including 90 mol% or more of PET and having an intrinsic viscosity of 1.0 dl / g or more using a spinning assembly 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.

[0031] The step of producing the yarn can further include the steps of: extruding the molten polyester pellets having an intrinsic viscosity of 1.0 dl / g or more through the spinneret including the nozzle unit having a shear rate of 220 to 260 1 / s and a polymer extrusion rate of 2.0 m / min or less under a pressure of the spinning assembly of 1800 to 2500 psi to produce a plurality of filaments; heating the extruded plurality of filaments via a heating unit; cooling the heated filaments via a cooling unit; bundling the plurality of filaments to form a polyester multifilament; stretching the polyester multifilament; and winding the stretched multifilament.

[0032] The tire cord provided by the process for producing a tire cord can have a tenacity 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 tenacity of 183 (g / den)·mm or more, each determined according to the standard test method of ASTM-D-885, and achieve a sidewall indentation (SWI) value of 3.6% or less.

[0033] The polyester multifilament includes 200 to 2000 polyester filaments having a fineness of 2.5 to 3.5 den.

[0034] The step of producing the polyester yarn can further include the steps of: extruding the molten polyester pellets having an intrinsic viscosity of 1.0 dl / g or more through the spinneret including the nozzle unit having a shear rate of 220 to 260 1 / s and a polymer extrusion rate of 2.0 m / min or less under a pressure of the spinning assembly of 1800 to 2500 psi to produce a plurality of filaments; heating the extruded plurality of filaments via a heating unit; cooling the heated filaments via a cooling unit; bundling the plurality of filaments to form a polyester multifilament; stretching the polyester multifilament; and winding the stretched multifilament.

[0035] The step of stretching the polyester multifilament can include the step of stretching the polyester multifilament at a total draw ratio of 1.0 to 3.0.

[0036] Although the production of polyester yarns is performed with low DPF (denier per filament), according to the present disclosure, the polymer extrusion rate at the nozzle can be adjusted to achieve high spinning tension and high stretching, while high extrusion pressure is established from the spinning pack to maintain high shear rate at the nozzle, thus preserving the excellent mechanical properties of polyester yarns in the tire cord and enabling all the properties required for weight reduction.

[0037] Accordingly, the disclosure according to the present disclosure enables the production of a tire including a low-weight tire cord that not only achieves high tenacity, high modulus of elasticity, and low shrinkage, but also high elongation at break.

[0038] The process is suitable for preserving the excellent mechanical physical properties (such as tenacity and elongation) of polyester yarns by including polyester yarns produced by using a process for spinning high-count filaments and by adjusting the pressure of the spinning pack, the process for spinning high-count filaments achieving spinning conditions with low denier per filament, low nozzle extrusion rate, and low shear rate. It has been found through experiments that by using polyester yarns according to the above process, high-strength tire cords capable of exhibiting all the physical properties of high modulus of elasticity and high tenacity can be produced. The present disclosure is prepared on the basis of these findings.

[0039] Tire cords are produced through a three-stage process consisting of yarn production, a twisting process using the yarn, and heat treatment, and it is necessary to maintain the above-mentioned physical properties of the yarn in the tire cord to obtain a product with excellent performance.

[0040] This means that the yarn goes through a post-processing process called twisting and heat treatment, and at this time, the physical properties of the yarn are impaired and changed. For example, a decrease in strength and tenacity can occur, and the shrinkage and elongation characteristics can also change. Therefore, it is necessary to maintain the physical properties of the yarn even in the post-processing process.

[0041] For the intended weight reduction, the tire cord must also meet all three physical properties: high modulus of elasticity, high tenacity, and low and stable shrinkage, to replace the existing fineness range.

[0042] According to the present invention, a factor indicating the modulus of elasticity is LASE (load at a specific elongation), and a factor indicating the shrinkage is side wall indentation (SWI). Further, it is necessary to adjust the modulus of elasticity so that the modulus of elasticity is low within a certain range to obtain high tenacity. This means that even when the modulus of elasticity is increased, it is necessary to avoid impairment of other physical properties such as tenacity. For example, it is necessary to control LASE@5%, which is the size of the modulus of elasticity determined by the load (g / den) at an elongation rate corresponding to 5% in a tensile load curve obtained by the ASTM-D-885 measurement method.

[0043] The conventional tire cord does not achieve all three physical properties, whereas the entire cord of the present embodiment exhibits high tenacity even after post-processing of the yarn and achieves all of the excellent modulus of elasticity, excellent tenacity, and excellent shrinkage.

[0044] Such a tire cord can be provided by including a polyester yarn produced by adjusting the pressure of a spinning pack in combination with a spinning process for high denier multifilament.

[0045] The yarn production conditions particularly employ a spinning process for high denier multifilament, which means that a low denier per filament (DPF), a low nozzle extrusion rate, and a low shear rate at the nozzle are used. However, such production conditions can cause a decrease in the pressure in the spinning pack / spinneret, which is associated with a decrease in the tenacity of the tire cord.

[0046] This means that the spinning process for high denier multifilament is capable of achieving the physical properties of high strength, high modulus of elasticity, and stable shrinkage of the tire cord, but is accompanied by a decrease in tenacity (elongation at break). The reason for this is that each property has a conflicting relationship. If the spinning is performed by a conventional general process, it is thus very difficult to produce a tire cord that achieves all of the desired physical properties.

[0047] Therefore, in the present specification, the present invention is conceived to use a specific spinning condition to maintain high tenacity during application of a spinning process for high denier multifilament by simultaneously adjusting the pressure of a spinning pack. Further, the tenacity limits the modulus of elasticity range LASE@5% to a specific range.

[0048] The tire cord produced by the above process achieves all of the above-mentioned properties such as high strength, high modulus of elasticity, low heat shrinkage, and high elongation, while maintaining excellent physical properties of the yarn. This enables a weight-reduced tire to have an advantageous rolling resistance.

[0049] Therefore, the rolling resistance can be improved by implementing a down-regulation of the fineness of the tire cord (for example, from 2000 den to 1500 den or from 3000 den to 2000 den).

[0050] It is also possible to improve the physical properties of the tire which are typically impaired when the fineness of the tire cord is reduced.

[0051] Advantageous embodiments provide 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 determined at 2% elongation. Advantageous embodiments provide 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.

[0052] Advantageous embodiments provide 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. Advantageous embodiments provide 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.

[0053] Advantageous embodiments provide that the tenacity of the tire cord has a value of 200 (g / den) mm or more, preferably 210 (g / den) mm or more, determined according to the standard test method ASTM-D-885. Advantageous embodiments provide that the tenacity 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 the standard test method ASTM-D-885. The tenacity of the tire cord can have a value of 183 (g / den) mm to 300 (g / den) mm.

[0054] The sidewall indentation value (SWI value) of the tire cord can have a value of 3.55% or less, preferably 3.4% or less. The sidewall indentation value (SWI value) of the tire cord can have a value of 3.0% or more, preferably 3.1% or more, particularly preferably 3.2% or more, very particularly preferably 3.3% or more. The SWI value of the tire cord can be 3.0% to 3.6%.

[0055] Advantageous embodiments provide 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 tenacity of 183 (g / den) mm to 300 (g / den) mm, and a SWI value of 3.0% to 3.6%.

[0056] In the present specification, the residual shrinkage before cooling of (A) and (B) can be the ratio between the length (L0) measured after leaving a tire cord sample having a length of 250 mm at 25°C and 65% relative humidity for 24 hours under an initial tension load selected from the range; the length (L1) measured after treating at 180°C for 2 minutes under an initial tension load of 0.011 g / den using a shrinkage tester. This means that the length change rate of the sample {=[(L0-L1) / L0]x100} can be defined as the shrinkage ΔL1. L0 and L1 can each be measured five times. In addition, the residual shrinkage after cooling can be determined with ΔL2 ({=[(L1-L3) / L1]x100}) where L3 is the length after cooling for 1 minute at room temperature.

[0057] In addition, the tension load of (A) and (B) and the load of (C) and (D) can also be measured without distinguishing the fineness by appropriately adjusting the load range according to the fineness of the tire cord within the above range.

[0058] This means that the SWI is not limited to the fineness range of the tire cord, and can be measured by adjusting the load range according to different fineness range conditions and determining the average value. The SWI can be defined and adjusted as the corresponding load according to the fineness of the tire cord, in particular.

[0059] In one embodiment of the present disclosure, the tire cord can include a raw cord having a total fineness of 1000 to 6000 den. The initial tension range can be adjusted according to the total fineness of the raw cord present in the tire cord and determined according to the production conditions of the yarn.

[0060] Accordingly, according to the embodiment of the present disclosure, when the total fineness of the tire cord is determined to be in the range of 3000 den to 4000 den, the preload for measuring the residual shrinkage (A) can be 35 to 45 g, the preload for measuring the residual shrinkage (B) can be 70 to 90 g, the load for measuring the elongation (C) can be 2.3 to 3.0 kg, and the load for measuring the elongation (D) can be 4.6 to 6.0 kg.

[0061] 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. The preload for measuring the residual shrinkage (B) under the above denier number conditions can be 40 g, 60 g, 70 g, or 90 g. Further, the load for measuring (C) under the above denier number conditions can be 1.5 kg, 2.0 kg, 2.3 kg, or 3.0 kg. Further, the load for measuring (D) under the above denier number conditions can be 3.0 kg, 4.0 kg, 4.6 kg, or 6.0 kg.

[0062] Further, the residual shrinkage can be an average of values measured at least 3 times, preferably at least 4 times, particularly preferably at least 5 times in the respective load range.

[0063] An advantageous embodiment provides that the tire cord has a heat shrinkage of less than 4%, preferably less than 3%, particularly preferably less than 2.5%, determined according to the standard test method ASTM-D-885.

[0064] An advantageous embodiment provides 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% in Equation 1.

[0065] An advantageous embodiment provides that the carcass ply has a ply strength of at least 0.94 kg / dm / den.

[0066] The buildability of a tire in certain regions is important for tire performance. Therefore, the ply strength normalized with respect to the fineness of the strength member is important for reducing the weight of the tire. A high ply strength allows excellent buildability of the tire. Therefore, a high-strength tire cord should be used to achieve excellent tire buildability, and the placement density of the tire cord should be increased by optimizing the distance between the tire cords.

[0067] Therefore, a ply strength of 0.94 kg / dm / den or more results in improved tire performance. The ply strength can be determined by multiplying the tenacity of the tire cord by the placement density of the tire cord in the ply, and then normalizing with respect to the fineness of the tire cord according to the standard test method ASTM-D-885.

[0068] An advantageous embodiment provides that the tire cord has a strength utilization of at least 88% according to the following Equation 2:

[0069] [Equation 2]

[0070] Strength utilization rate (%) = [tire cord tenacity (g / den) / polyester yarn tenacity (g / den)] x 100.

[0071] The tire cord preferably has a strength utilization rate of 88.5% or greater, particularly preferably 88.7% or greater, very particularly preferably 88.9% or greater. It is also preferable that the tire cord has a strength utilization rate of 91.0% or less, particularly preferably 90.8% or less, very particularly preferably 90.6% or less, still more preferably 90.4% or less. Thus, the tire cord according to the present disclosure can have excellent strength.

[0072] The tire cord may, for example, have a strength utilization rate of 88.5% to 91.0%, preferably 88.7% to 90.8%, particularly preferably 88.7% to 90.6%, very particularly preferably 88.7% to 90.4%, still more particularly preferably 88.9% to 90.4%.

[0073] The strength utilization rate of the tire cord relative to the strength of the yarn can be at least 90%, in particular.

[0074] An advantageous embodiment provides that the polyester yarn is a polyester multifilament composed of 200 to 2000 polyester filaments each having a fineness of 2.5 to 3.5 den, and the polyester yarn is impregnated with an adhesive layer.

[0075] The adhesive layer can be formed, in particular, by impregnating the raw cord in an adhesive solution that is generally known, wherein the adhesive solution that can be used for conventional tire cords can be, for example, a resorcinol-formaldehyde-latex adhesive solution (RFL adhesive solution).

[0076] The adhesive layer can be present in an amount of 0.5% to 10% by weight, preferably 1% to 8% by weight, particularly preferably 1.5% to 6% by weight, of the high-strength tire cord.

[0077] An advantageous embodiment provides that the polyester yarn is manufactured from a polyester composition composed of melt PET pellets, the melt PET pellets including at least 90 mol% of PET, and the melt PET pellets having an intrinsic viscosity of at least 1.0 dl / g.

[0078] Thus, the melt PET pellets are melt polyester pellets composed of PET to the extent of 90 mol% or more and having an intrinsic viscosity of 1.0 dl / g or more. The melt PET pellets can also include 92 mol% or more, preferably 95 mol% or more, particularly preferably 99 mol% or more, very particularly preferably 100 mol% of PET.

[0079] When the molten PET particles are formed to an extent of less than 100% from PET, various known additives can be added in the step of producing the polyester composition forming the undrawn yarn. Thus, the type of the additives is not limited.

[0080] In one embodiment, the molten PET particles can have an intrinsic viscosity of 1.0 dl / g or more, preferably 1.1 dl / g to 1.9 dl / g. The molten PET particles can preferably have an intrinsic viscosity of 1.0 dl / g or more, preferably 1.1 dl / g or more. The molten PET particles can further have an intrinsic viscosity of 1.7 dl / g or less, preferably 1.6 dl / g or less, particularly preferably 1.5 dl / g or less, very particularly preferably 1.4 dl / g or less.

[0081] According to one embodiment of the present application, the polyester yarn can be made of a PET drawn yarn using particles consisting of 90 mol% or more of PET by a spinning process.

[0082] The PET drawn yarn is produced, inter alia, by melt spinning of PET particles to produce undrawn fibers and by subsequent drawing of the undrawn fibers. The PET tire cord can additionally be produced as one of an impregnated cord by twisting the PET drawn yarn and immersing it in a binder solution.

[0083] In one embodiment of the present application, the PET drawn yarn further contains 90 mol% or more of PET so as to exhibit the properties of PET suitable for tire cords. When the PET drawn yarn contains less than 90 mol% of PET, the PET drawn yarn and the tire cord produced therefrom are difficult to exhibit the desired physical properties.

[0084] Thus, in the context of the present disclosure, the term "PET" is to be understood to mean a PET content of at least 90 mol%, unless otherwise specified in the present disclosure.

[0085] An advantageous embodiment provides that the polyester yarn has a tenacity of 7.5 to 11.0 g / den and an elongation at break of 10% to 20%.

[0086] An advantageous embodiment provides that the original cord of the tire cord has a total fineness of 1000 to 9000 denier, preferably 1000 to 6000 denier.

[0087] Advantageous embodiments provide that the tire cord has a tenacity of more than 8.2 g / den, particularly preferably more than 8.4 g / den, particularly preferably more than 8.5 g / den. Advantageous embodiments further provide that the tire cord has a tenacity of 11 g / den or less, preferably 10.0 g / den or less, according to the standard test method ASTM-D-885. The breaking strength of the tire cord can in particular be from 8.0 g / den to 11 g / den.

[0088] Advantageous embodiments provide that the tire cord comprises exactly two or exactly three polyester yarns, preferably exactly two polyester yarns, wherein these polyester yarns are cabled together. Thus, the tire cord has a construction x 2 or x 3, preferably x 2.

[0089] Advantageous embodiments provide that the tire cord has a total denier of from 2500 den to 4500 den, preferably from 3000 den to 4000 den.

[0090] Advantageous embodiments provide that the tire cord has a total denier of from 2500 den to 4500 den, preferably from 3000 den to 4000 den.

[0091] Advantageous embodiments provide that the tire cord has a total denier of from 2500 den to 4500 den, preferably from 3000 den to 4000 den.

[0092] The polyester yarns have a denier of from 1500 den to 2000 den.

[0093] It has proven to be particularly advantageous when the tire cord has a construction of 1500 den x 2 or 2000 den x 2.

[0094] The original cord of the tire cord can be produced by feeding the stretched polyester yarns into a cable cord twister and subjecting the yarns to a primary twist and a secondary twist in each case at a twist number of from 200 TPM to 500 TPM. The tire cord (impregnated cord) can be produced by impregnating the original cord in a binder coating solution, followed by drying and heat treatment.

[0095] The vehicle pneumatic tire according to the application is preferably a tire for a passenger car or a van or a light truck. The vehicle pneumatic tire is preferably a tire having a radial construction.

[0096] The production of the vehicle pneumatic tire is carried out in a manner known to the person skilled in the art with devices known to the person skilled in the art.

[0097] This includes in particular initially providing an unvulcanized blank of an unvulcanized vehicle pneumatic tire by laying corresponding parts comprising an unvulcanized rubber mixture on top of one another, the unvulcanized blank comprising a carcass having a tire cord as a strength member, including all described embodiments. Subsequently, the blank is vulcanized.

[0098] The present invention encompasses all advantageous configurations reflected, inter alia, in the claims. The present invention also encompasses, inter alia, embodiments resulting from the combination of different features, wherein the features have different levels of preference, and therefore the present invention also encompasses the combination of a first feature described as "preferred" with another feature described, for example, as "particularly preferred".

[0099] The process for producing the tire cord according to the present invention can include the steps of spinning the molten polyester pellets comprising at least 90 mol% of PET and having an intrinsic viscosity of 1.0 dl / g or more using a spinning assembly comprising a spinneret having a nozzle unit to produce a polyester yarn; producing a green cord using the polyester yarn; and immersing the green cord in an adhesive solution and heat treating the cord. The step of producing the polyester yarn can include the step of extruding the molten polyester pellets through the spinneret to form polyester filaments having a fineness of 2.5 to 3.5 den under pressurization of the spinning assembly of 1800 to 2500 psi, wherein the spinneret comprises a nozzle unit having a shear rate of 220 to 260 1 / s and a polymer extrusion rate of 2.0 m / min or less.

[0100] To produce a tire cord that achieves the properties of high tenacity, high elastic modulus, low shrinkage, and high elongation, a low DPF of the polyester yarn is advantageous. In the present disclosure, the polymer extrusion rate from the nozzle and the low DPF of the polyester can be adapted to achieve high spinning tension and high draw.

[0101] Under the yarn production conditions, the tenacity of the polyester yarn and the tenacity of the tire cord can also decrease due to the low nozzle extrusion pressure. Therefore, the present disclosure has the feature of determining a high extrusion pressure in the spinning assembly, thereby allowing the shear rate at the nozzle to remain high.

[0102] Therefore, the present disclosure has the feature that by adjusting the spinning conditions and at the same time maintaining the spinning assembly pressure within a certain range, the excellent physical properties of the polyester yarn can be preserved in the tire cord once the yarn has undergone the post-processing of twisting and heat treatment, thereby achieving all the physical properties of the tire cord required for weight reduction.

[0103] The tire cord can be produced in other ways through a conventional process, except for adjusting the spinning process and the pressurization of the spinning assembly during the production of the polyester yarn.

[0104] As described above, the high-strength polyester yarn for a tire cord can be produced, inter alia, by spinning the molten polyester pellets comprising at least 90 mol% of PET and having an intrinsic viscosity of 1.0 dl / g or more using a spinning assembly comprising a spinneret having a nozzle unit.

[0105] In the illustrative embodiment, the molten polyester particles can comprise molten PET particles comprising at least 90 mol% of PET and having an intrinsic viscosity of 1.0 dl / g or more, preferably 1.1 dl / g to 1.9 dl / g. The molten PET particles can preferably have an intrinsic viscosity of 1.0 dl / g or more, preferably 1.1 dl / g or more. The molten PET particles can further have an intrinsic viscosity of 1.7 dl / g or less, preferably 1.6 dl / g or less, particularly preferably 1.5 dl / g or less, very particularly preferably 1.4 dl / g or less.

[0106] The molten PET particles can further comprise 92 mol% or more, preferably 95 mol% or more, particularly preferably 99 mol% or more, very particularly preferably 100 mol% of PET. When the molten PET particles are formed to less than 100% by PET, various known additives can be added in the step of producing the polyester composition that forms the undrawn yarn. Thus, the type of additive is not limited.

[0107] The spinning can additionally be performed at 270°C to 300°C, preferably at 275°C to 300°C, particularly preferably at 275°C to 290°C in a spinneret having 200 to 550 spinneret openings.

[0108] The step of producing the polyester yarn can further comprise the steps of heating and cooling the extruded plurality of filaments, bundling the cooled filaments, and subsequently drawing the filaments to produce drawn polyester yarn, followed by winding the drawn polyester yarn, after the step of producing the plurality of filaments.

[0109] The process for producing the polyester yarn can preferably comprise the steps of extruding molten polyester particles having an intrinsic viscosity of 1.0 dl / g or more through a spinneret comprising a nozzle unit having a shear rate of 220 to 260 1 / s and a polymer extrusion rate of 2.0 m / min or less at a pressure of the spinning pack of 1800 to 2500 psi to produce a plurality of filaments; heating the extruded plurality of filaments via a heating unit; cooling the heated filaments via a cooling unit; bundling the plurality of filaments to form a polyester multifilament; drawing the polyester multifilament; and winding the drawn multifilament.

[0110] The high-strength polyester yarn can be produced, for example, by a process including the following steps, in which PET particles including at least 90 mol% of 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, are melted and extruded into a plurality of filaments through a nozzle unit by adjusting the spinning conditions and the spinning pack pressure of the nozzle unit under the above-mentioned ranges; a step of heating the heated plurality of filaments via a heating unit positioned around the nozzle unit; a step of cooling the heated plurality of filaments via a cooling unit; a step of bundling the plurality of filaments to form a polyester multifilament; a step of stretching the polyester multifilament; and a step of winding the stretched multifilament.

[0111] At this moment, the spinning pack can adjust the extrusion pressure range to 1800 to 2500 psi (about 126.55 to 175.8 kgf / cm2). However, if the extrusion pressure of the spinning pack is 1800 psi or less, the polymer extrusion rate at the nozzle can decrease, as a result of which the desired performance capability cannot be achieved, and if the extrusion pressure is 2500 psi or more, excessive pressure can cause device problems such as pack leakage.

[0112] When the molten polyester particles are extruded through the nozzle including the nozzle unit, the shear rate at the nozzle can further be 220 to 260 1 / s. If the shear rate is 220 1 / s or less, the orientation of the polymer in the nozzle can decrease, thus potentially reducing the tenacity of the yarn, and if the shear rate is 260 1 / s or more, the reduction in the yarn tension can impair the dimensional stability of the yarn.

[0113] The polymer extrusion rate at the nozzle can be further reduced to 2.0 m / min or less together with the adjustment of the shear rate at the nozzle. The polymer extrusion speed at the nozzle can be, inter alia, 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, still more preferably 1.3 to 1.9 m / min, still more preferably 1.5 to 1.9 m / min. If the polymer extrusion rate is 2 m / min or more, the polymer extrusion rate at the nozzle can decrease, as a result of which the desired performance capability cannot be achieved.

[0114] The process makes it possible to form a polyester multifilament including a polyester filament having a fineness of 2.5 to 3.5 den. That is, it is determined in accordance with the present disclosure that a polyester multifilament including a polyester filament having a DPF of 2.5 to 3.5 is formed.

[0115] The polyester filaments can include 200 to 2000 polyester monofilaments having a fineness of 2.5 to 3.5 den, preferably 400 to 1200 corresponding polyester monofilaments. The fineness of the polyester monofilaments can preferably be 2.6 to 3.5 den, particularly preferably 2.7 to 3.4 den.

[0116] Meanwhile, the process for producing the polyester yarn can include performing processes for heating and cooling the extruded plurality of filaments, for bundling the cooled filaments, and then for stretching the filaments to produce stretched polyester yarns, and then for winding the yarns in a conventional manner. BRIEF DESCRIPTION OF DRAWINGS

[0117] Further features, advantages, and details of the present application and the process for producing a tire cord will now be set forth in connection with the attached drawings, in which:

[0118] Figure 1 A polyester yarn production apparatus is shown. DETAILED DESCRIPTION

[0119] As Figure 1 shown, a polyester yarn production apparatus 1 according to an embodiment of the present disclosure includes an extruder 10, a spinning assembly 20, a cooling unit 30, a bundling unit 40, a stretching unit 50, and a winding unit 60.

[0120] The upper surface of the extruder 10 can have a hopper 12 formed thereon to receive a supply (arrow) of polymer pellets, and a heating device and a transportation device are provided within the extruder 10 to melt the polymer pellets supplied via the hopper 12 and transport the molten pellets into the spinning assembly 20. The polymer employed can be polyester, but is not limited thereto.

[0121] The yarn production apparatus 1 capable of producing polyester yarns using polyester pellets will now be described by way of example below to ensure sufficiency of the description. However, the yarn production apparatus according to an embodiment of the present disclosure is not only used to produce polyester yarns, but can also be used to produce other yarns known in the prior art.

[0122] Further, the spinning assembly 20 extrudes the molten polyester pellets transported out of the extruder to form a plurality of filaments 2. The spinning assembly 20 can be a spinning block, an assembly body, a spinneret, and a heating unit, but its configuration is not limited thereto.

[0123] The device for producing a polyester yarn can particularly include a spinning assembly including a spinneret including a nozzle unit including a plurality of extrusion openings for extruding molten particles, a heating unit positioned around the nozzle unit to heat the plurality of filaments extruded through the plurality of extrusion openings, a cooling unit for cooling the plurality of filaments heated by the heating unit, a bundling unit for bundling the plurality of filaments cooled by the cooling unit to form a multifilament, and a drawing unit for drawing the multifilament. The plurality of extrusion openings can be arranged in a circle, in at least two rows or more. A distance between adjacent extrusion openings in any one row, a distance between adjacent extrusion openings in any other row, and a distance between extrusion openings arranged close to each other in any one row and in any other row adjacent to the any one row.

[0124] The disclosure can provide a general procedure for cooling the filaments 2 via the cooling unit 30, but is not limited thereto.

[0125] In the disclosure, the coolant (e.g., air) enters the cooling chamber 32 through the coolant inlet 34 and can escape via the coolant outlet 36.

[0126] The high-strength polyester yarn for a tire cord can be further produced by a process including a step for drawing the undrawn multifilament 4 in at least two stages including three or more godets 52, 54, 56, and 58. In the present case, the at least three or more godets include a first godet, a second godet, and a third godet arranged in series based on a movement direction 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.

[0127] The step of drawing the polyester multifilament can include a step of drawing the polyester multifilament at a total draw ratio of 1.0 to 3.0, and the drawn polyester yarn can be produced by the above-described process. The total draw ratio can preferably be between 1.5 and 3.0 or between 1.5 and 2.5. In other words, in order to increase the degree of orientation by drawing and thus exhibit 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.

[0128] The multi-stage draw rate ratio can be further defined as a ratio between a difference between the rotation speed of the first godet and the rotation speed of the second godet and a difference between the rotation speed of the second godet and the rotation speed of the third godet, wherein the multi-stage draw rate ratio can be between 30:70 and 60:40.

[0129] The winding unit 60 produces the polyester yarn 6 by winding the multifilament stretched by the stretching unit 50.

[0130] The high-strength polyester yarn produced through 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%.

[0131] To produce the original cord, the primary process can be twisting the yarn, and the secondary process can be twisting the twisted yarn into a cord (original cord). This can be done in a single step process in a direct cabler or in two successive separate steps in a ring twister. The twist number can be 200 TPM to 500 TPM.

[0132] Further, the step of immersing the original cord in the adhesive solution and heat treating the yarn can be a step of immersing the original cord in the adhesive solution, followed by heat treating to produce a tire cord (an impregnated cord).

[0133] The adhesive layer can be formed, inter alia, by impregnating the original cord in a generally known adhesive solution, wherein the adhesive solution usable for a conventional tire cord can be, for example, a resorcinol-formaldehyde-latex adhesive solution (RFL adhesive solution).

[0134] The heat treatment step can be performed after the impregnation with the adhesive solution. The heat treatment step can be performed at a temperature of 220°C to 260°C for 90 to 360 seconds, preferably at a temperature of 230°C to 250°C for 90 to 240 seconds, and still more preferably at a temperature of 240°C to 245°C for 90 to 120 seconds.

[0135] By immersing the high-strength polyester yarn in the 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 vulcanization of the tire can be further reduced.

[0136] The present disclosure will now be described in greater detail with reference to examples and comparative examples. The following examples and comparative examples are intended merely to facilitate an understanding of the present disclosure and are not intended to limit its scope.

[0137] The present invention and further features, advantages, and details of the process for producing a tire cord will now be more particularly described with reference to the examples, which can represent embodiments, and the reference examples.

[0138] [Examples and Comparative Examples: Production of Polyester Yarn]

[0139] <Example 1>

[0140] For Example 1, a 1000 m long multifilament yarn was used, which was stretched at a temperature of 80°C to 100°C at a speed of 1000 m / min to 1500 m / min, and then wound at a speed of 1000 m / min to 1500 m / min to produce a high-strength polyester yarn. Figure 1The yarn production apparatus 1 shown in the middle produces a polyester yarn 6 including PET to the extent of at least 90 mol% or more and having a filament fineness of the polyester filaments of 2.7 to 3.4 and a total fineness of 1500.

[0141] In particular, PET pellets including PET to the extent of at least 90 mol% and having an intrinsic viscosity (I.V.) of 1.0 to 1.4 dl / g were melted with a single screw extruder to produce molten polyester pellets. The molten polyester pellets were then spun using a 170 spinneret (L / D = 4.0 / 1.0, number of extrusion openings: 500) at a spinning speed of 3200 m / min to produce a plurality of filaments 2 as described in Table 1.

[0142] At this time, the conditions for producing the plurality of filaments (including the throughput of the spinneret) were adjusted as shown in Table 2 (DPF, polymer extrusion rate at the nozzle, shear rate at the nozzle, spinning pack pressure).

[0143] The plurality of filaments 2 were then heated by a heating unit, and then cooled in a cooling unit 30, and the cooled filaments were bundled to produce an unstretched yarn 4 (unstretched yarn).

[0144] The molten material for spinning was extruded through the spinneret to obtain a stretched polyester yarn having a total fineness of 1000 den (a single fineness of about 4 den per filament). The process of obtaining the stretched polyester yarn was performed at a spinning temperature of 290°C, a spinning rate of 3200 m / min, a total draw ratio of 1.5, and a relaxation rate of 1.5% (heat treatment at 180°C after drawing).

[0145] The stretched yarn was wound to produce a polyester yarn (stretched yarn).

[0146] [Reference Example 1]

[0147] A polyester yarn was produced in the same manner as in Example 1, except that the spinneret diameter, the number of openings, the spinning conditions, and the spinning pack pressure were changed as shown in Table 1 and Table 2 below.

[0148] [Table 1]

[0149]

[0150] [Table 2]

[0151]

[0152] [Example 2 and Reference Example 2: Production of a Tire Cord]

[0153] The tire cord of Example 2 and Reference Example 2 were each produced using the polyester yarn produced in Example 1 and Reference Example 1 under the same conditions.

[0154] In particular, the polyester yarn was introduced into a twister, two strands of the primary twisted yarn having a twist number of 460 TPM were manufactured (Z direction), and then the two strands of the primary twisted yarn were re-twisted (S direction) at a twist number of 460 TPM to produce a raw cord. The raw cord thus produced was dipped into an adhesive solution containing resorcinol formaldehyde latex (RFL), and then dried at 150°C for 100 seconds, and heat-treated at 240°C for 100 seconds to form a tire cord (dipped cord). The tension applied to the raw cord during the dipping, drying, and heat-treatment processes was 0.5 kg / cord.

[0155] Further, the raw cord showed a total fineness value of 1000 to 6000 denier.

[0156] [Experimental Example A: Evaluation of physical properties of polyester yarn and tire cord]

[0157] The tensile strength and elongation at break were measured for the polyester yarn produced according to the foregoing, and for the tire cord using the polyester yarn.

[0158] Tensile strength, elongation at break and elongation

[0159] The toughness (g / den), elongation, and strength ratio of the stretched polyester yarn and tire cord were tested according to the ASTM-D-885 standard test method using a universal testing machine according to Equation 2, and the results are shown below in Table 3 and Table 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.

[0160] In the stress-strain curve obtained by the above test, the elongation was determined at a load of 4.5 g / den.

[0161] [Table 3]

[0162]

[0163] [Table 4]

[0164]

[0165] With regard to Table 3 and Table 4, the polyester yarn of Example 1 and the tire cord of Example 2 exhibited the excellent physical properties described, which were improved compared to the corresponding reference examples.

[0166] [Experimental Example B: Evaluation of physical properties of tire cord]

[0167] The physical properties of tenacity, modulus of elasticity, tenacity, and SWI of the tire cord manufactured in the measurement example and the reference example were measured. The results are shown in Table 5 below.

[0168] (1) Tenacity and tenacity

[0169] The tenacity (g / den), elongation (%) and tenacity of the tire cord were determined using a universal testing machine according to the standard test method of ASTM-D-885. The sample length was 250 mm (cord length: 600 mm), the tensile speed was 300 mm / min, and the initial load was set to 0.05 g / den.

[0170] (2) Modulus of elasticity (LASE@2%, LASE@5%)

[0171] The stress-strain curve was obtained according to the standard test method of ASTM-D885. The load was determined using the stress-strain curve when the longitudinal elongation was 2% and 5% and LASE@5% was measured during elongation. The sample before measurement was measured after being stored in an atmosphere of 20°C and 65% relative humidity for 24 hours.

[0172] (3) SWI

[0173] The SWI was determined by Equation 1 according to claim 1. In addition, (A) can be 1.0% to 3.2%, (B) can be 0.7% to 2.8%, (C) can be 1.3% to 1.7%, and (D) can be 4.2% to 4.6%.

[0174] In particular, a sample of 250 mm having a total fineness of 1000 to 6000 den was stored at 25°C and 65% relative humidity for 24 hours, and then the length (L0) was measured under an initial tension load of 0.01 g / den. Then, the sample was treated at 180°C for 2 minutes using a shrinkage tester at an initial tension load of 0.01 g / den, and subsequently the length (L1) of the sample was measured. L0 and L1 were each measured three times. The length change rate of the sample {=[(L0-L1) / L0] x 100} was defined as the shrinkage DL1 before cooling of the sample.

[0175] In addition, the residual shrinkage of the sample was measured using a shrinkage tester, and then the sample was removed from the oven under a constant load and cooled at room temperature (25°C) for about 1 minute, and then the residual shrinkage was measured in a steady state of the cord. Accordingly, the residual shrinkage after cooling represents the residual shrinkage of ΔL2 ({=[(L1-L3) / L1] x 100}) where the length (L3) is measured 1 minute after cooling.

[0176] [Table 5]

[0177]

[0178] With respect to Table 5, the tire cord of Example 2 has tenacity of 8.0 g / den or more, LASE@2% of 1.1 g / den or more, and LASE@5% of 2.5 g / den or less, and tenacity of 183 (g / den)·mm or more, determined according to the ASTM-D-885 standard test method in each case, and achieves a SWI value of 3.6% or less. This means that the tire cord of Example 2 has a high modulus of elasticity, a low shrinkage rate, and a high elongation effect, that is, even after the yarn post-processing process, the tire cord maintains excellent strength. This is evident in terms of advantageous properties compared to Reference Example 2.

[0179] In Reference Example 2, the draw is less than the inventive range of the present disclosure, the DPF is not less than 3.9, and the value of tenacity is not greater than 175.0 (g / den)·mm. Further, in Reference Example 2, the LASE@2% value is 1.0%, which is lower than in Example 2, which limits the improvement in modulus of elasticity.

[0180] Therefore, when producing a yarn for providing a tire cord, it is necessary to adjust the pressure of the spinning assembly while using a spinning process for high denier multifilament having specified spinning conditions, so that all physical properties are excellent and especially tenacity can be maintained.

[0181] The cord strength is specified for the placement density of 180 epdm (“ends per dm”) of the respective strength member in the carcass ply. The cord strength of the corresponding carcass ply including the tire cord of Example 2 is greater than the cord strength of the corresponding carcass ply including the cord of Reference Example 2. The cord strength can be determined according to the ASTM-D-885 standard test method by multiplying the tenacity of the tire cord by the placement density of the tire cord in the ply, and normalizing with respect to the fineness of the tire cord.

[0182] [Assessment of rolling resistance of tires]

[0183] Vehicle pneumatic tires for vans were manufactured and tested. The tires only differ in the type and placement density of the strength members of the carcass ply. The placement density was chosen so that the cord-to-cord distance of the carcass ply of both tires is comparable. The carcass strength members include exactly two polyester yarns twisted together, the tire cord thus having a construction x 2.

[0184] The reference tire's carcass strength member has a construction 2000 den x 2. The polyester yarn is a conventional PET multifilament yarn having a fineness of 2000 den. The reference tire's carcass strength member is arranged in the carcass ply with a placement density of 105 epdm.

[0185] The example tire 1 is according to the invention and comprises in its carcass ply a tire cord according to the invention as a carcass strength member. The tire cord of the invention has a construction 1500 den x 2 and is arranged in the carcass ply with a placement density of 118 epdm. The tire cord of the example tire can be a cord according to example 2.

[0186] [Table 6]

[0187]

[0188] Table 6 shows the physical properties of the tire's carcass cord and the respective carcass ply's respective ply strength.

[0189] The properties are also normalized based on diameter (in mm) and / or placement density (in epdm). A reduction in diameter and the accompanying reduction in ply thickness is key to improving rolling resistance. The placement density is chosen such that the cord-to-cord distance in the carcass ply of both tires is comparable.

[0190] The example tire's tire cord of the invention achieves a significantly higher tenacity per cord and a significantly higher ply strength, thus allowing a reduction in core diameter, which in turn results in a better rolling resistance, see Table 7.

[0191] The tires were used to perform a tire test and it was found that the endurance and high speed characteristics of the comparative tire were at about the same level. The fineness of the carcass strength member in the example tire was reduced compared to the reference tire.

[0192] It is apparent from Table 7 that the rolling resistance of the example tire is advantageously improved by 1.5% compared to the reference tire of the respective example. Values greater than 100% correspond to a lower, i.e. improved, rolling resistance (RR).

[0193] [Table 7]

[0194]

[0195] Although the preferred embodiments of the disclosure have been described above, the disclosure is not limited thereto. Embodiments of the invention include all modifications that can be readily derived by those skilled in the art of the technical field of the disclosure and its acknowledged equivalents.

[0196] List of reference signs

[0197] 1 Polyester yarn production device

[0198] 2 filaments

[0199] 4 un-stretched filaments

[0200] 6 polyester yarns

[0201] 10 extruder

[0202] 12 hopper

[0203] 20 spinning assembly

[0204] 30 cooling unit

[0205] 32 cooling chamber

[0206] 34 coolant inlet

[0207] 36 coolant outlet

[0208] 40 bundling unit

[0209] 50 stretching unit

[0210] 52, 54, 56, 58 godets

[0211] 60 winding unit

Claims

1. A vehicle pneumatic tire comprising a carcass extending from one bead region to another bead region and anchored therein by wrapping around a high-tension bead core, wherein, The tire carcass includes at least one carcass ply having parallel and spaced-apart strength members embedded in an elastomeric material, wherein these strength members are in the form of tire cords, each tire cord comprising at least one polyester yarn (6) composed of polyethylene terephthalate (PET) to a degree of at least 90 mol%. Its features are, The tire cord has At least 8.0g / den of toughness, and At least 1.1 g / den of LASE@2%, and Up to 2.5g / den of LASE@5%, and At least 183 (g / den)·mm toughness, The above items are determined according to the ASTM-D-885 standard test method under their respective circumstances. And a sidewall indentation (SWI) value of no more than 5%, preferably no more than 4%, and particularly preferably no more than 3.6%. The sidewall indentation SWI is given by the following equation 1: [Equation 1] SWI (%) = [(D)-(C)]+[(A)–(B)], In Equation 1: (A) is the residual shrinkage rate of the tire cord measured after heat shrinkage was measured using a shrinkage testing machine (at a sample length of 250 mm, at 180°C and an exposure time of 2 minutes, under an initial load of 20 g to 45 g) and subsequently allowed to cool for 1 minute. (B) is the residual shrinkage rate of the tire cord measured after the heat shrinkage rate was measured using a shrinkage testing machine (at a sample length of 250 mm, at 180°C and an exposure time of 2 minutes, under an initial load of 40 g to 90 g) and subsequently allowed to cool for 1 minute. (C) is the elongation of the tire cord under a load of 1.5 kg to 3.0 kg, measured according to the ASTM-D-885 standard test method. (D) is the elongation of the tire cord under a load of 3.0 kg to 6.0 kg, as measured according to the ASTM-D-885 standard test method.

2. The vehicle pneumatic tire as described in claim 1, wherein, The tire cord has a heat shrinkage rate of less than 4%, preferably less than 3%, and particularly preferably less than 2.5%, as determined by the ASTM-D-885 standard test method.

3. A vehicle pneumatic tire as described in 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%, (D) is 4.2% to 4.6%.

4. A vehicle pneumatic tire as described in 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. A vehicle pneumatic tire as described in one or more of the preceding claims, characterized in that, According to Equation 2 below, the tire cord has a strength utilization rate of at least 88%: [Equation 2] Strength utilization rate (%) = [tire cord toughness (g / den) / polyester yarn toughness (g / den)] × 100.

6. A vehicle pneumatic tire as described in one or more of the preceding claims, characterized in that, The polyester yarn (6) is a polyester multifilament consisting of 200 to 2000 polyester monofilaments, each of which has a fineness of 2.5 to 3.5 denier, and wherein the polyester yarn is impregnated with an adhesive layer.

7. A vehicle pneumatic tire as described in one or more of the preceding claims, characterized in that, The polyester yarn (6) is made of a polyester composition consisting of molten PET particles comprising at least 90 mol% PET and having an intrinsic viscosity of at least 1.0 dl / g.

8. A vehicle pneumatic tire as described in one or more of the preceding claims, characterized in that, The polyester yarn (6) has a toughness of 7.5 to 11.0 g / den and an elongation at break of 10% to 20%.

9. A vehicle pneumatic tire as described in one or more of the preceding claims, characterized in that, The original cords of the tire cord have a total fineness of 1,000 to 9,000 deniers, preferably 1,000 to 6,000 deniers.

10. A vehicle pneumatic tire as described in one or more of the preceding claims, characterized in that, The tire cord has a toughness greater than 8.2 g / den, preferably greater than 8.4 g / den, and even more preferably greater than 8.5 g / den.

11. A vehicle pneumatic tire as described in one or more of the preceding claims, characterized in that, The tire cord comprises exactly two or exactly three polyester yarns, preferably exactly two polyester yarns, wherein these polyester yarns are twisted together.

12. A vehicle pneumatic tire as described in one or more of the preceding claims, characterized in that, The tire cord has a total fineness of 2,500 den to 4,500 den, preferably 3,000 den to 4,000 den.

13. A vehicle pneumatic tire as described in 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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