PNEUMATIC VEHICLE TIRES WITH A BELT BANDAGE

Description

[0001] The invention relates to a pneumatic vehicle tire comprising a carcass, in particular of a radial design, with textile carcass reinforcements, a belt arranged radially outside the carcass, and a belt bandage layer of a belt bandage arranged radially outside the belt, wherein the belt bandage layer comprises textile cords as reinforcements, which are arranged substantially parallel to one another and embedded in elastomeric material, wherein the cords each comprise exactly two yarns, wherein the two yarns are yarns made of polyamide 6.6 (PA 6.6), which have the same fineness and are end-twisted together to form the cord, characterized in that the cords (20) at an elongation of 4% have a tangent modulus of 9.3 N / % to 14 N / %, preferably from 9.5 N / % to 13 N / %, particularly preferably from 11 N / % to 12.5 N / %, and that the twist factor of the cord (20) is 120 to 220, wherein the twist factor is defined as twist factor = twist [t / m] x (fineness [dtex] / 10000) 1 / 2< .

[0002] Pneumatic vehicle tires with reinforcement layers are well known. For example, a carcass of a radial design, in particular, with textile reinforcements, is known for pneumatic vehicle tires. In a radial design carcass, the reinforcements of the carcass in the area of ​​the tire's sidewalls form an angle of a maximum of 10°, in particular a maximum of 6°, with the tire's radial direction rR. The belt can have two reinforcement layers, whose reinforcements have opposing pitch directions.

[0003] Furthermore, it is known for pneumatic vehicle tires to use a belt bandage comprising one or more belt bandage layers, covering at least the belt edges, wherein the one or more belt bandage layers contain parallel and essentially circumferentially extending reinforcements in the form of cords embedded in the rubber. This belt bandage serves to prevent the tire from lifting due to the centrifugal forces occurring during driving, particularly during high-speed use.

[0004] During tire production, the belt bandage is applied in the form of plies, strips, or individual cords with reinforcements embedded in an unvulcanized rubber compound, which are wound or spooled onto the belt. The reinforcements are embedded in the rubber by passing a group of essentially parallel, thread-like reinforcements, which are usually pretreated thermally and / or with an impregnation for better adhesion to the embedding rubber in a manner known to the expert, longitudinally through a calender or an extruder to be coated with the rubber compound.

[0005] The cords of the tire's belt bandage should allow sufficient elevation during tire manufacture and in the vulcanization mold to allow precise tire molding. They should also ensure good high-speed capability, i.e., good dimensional stability, during driving after the tire's completion. To meet these requirements, the cords should be able to be stretched up to an elongation of approximately 3 to 4% with moderate force, and beyond higher elongation only with very high force.

[0006] As a material for the reinforcements of the belt bandage layer, it is common practice to use cords made of one or two PA 6.6 yarns, as PA 6.6 exhibits advantageous shrinkage behavior for high-speed performance and good fatigue resistance to alternating tensile and compressive loads at and near the belt edge. For example, the use of a PA 6.6 1400 dtex x 2 cord is well-known and common.

[0007] EP 3 738 789 A1 relates to a reinforcement layer of a pneumatic vehicle tire, wherein the reinforcement layer comprises a reinforcement with at least one polyamide yarn made of twisted polyamide filaments. EP 3 254 870 A1 relates to a rubberized reinforcement layer for articles made of elastomeric material, wherein the reinforcement layer comprises a plurality of parallel and spaced-apart reinforcements, each reinforcement being a cord which is end-twisted from at least two twisted multifilament yarns of polyamide 6,6.

[0008] One disadvantage of PA 6.6, however, is its low tangent modulus, which limits its high-speed capability. To improve the tangent modulus, hybrid cords made from a PA 6.6 yarn and an aramid yarn are known. However, such cords are expensive and exhibit poor fatigue resistance, more sensitive adhesion properties, and lower shrinkage forces.

[0009] EP 3 350 363 A1 relates to a reinforcing cord for the cover ply, which forms the reinforcing layer for the cover ply arranged between the tread and the belt package in vehicle tires for motor vehicles.

[0010] The task is therefore to provide a pneumatic vehicle tire, in particular for a passenger car, which has further improved high-speed capability.

[0011] This is achieved by the cords having a tangent modulus of 9.3 N / % to 14 N / %, preferably 9.5 N / % to 13 N / %, particularly preferably 11 N / % to 12.5 N / %, at an elongation of 4%.

[0012] The tangent modulus of a cord at a specific elongation corresponds to the slope of the force-elongation curve at the respective elongation of the cord, whereby the force-elongation curve is determined according to ASTM D 885 / ASTM D 885 M. The force-elongation curve can be determined on the stretched and dipped cord provided with an adhesive before introduction into the elastomeric material.

[0013] Surprisingly, it has been shown that such a pneumatic vehicle tire has a further improved high-speed capability due to the increased tangent modulus of the cords of the belt bandage layer.

[0014] The cord, made of two PA 6.6 yarns, also exhibits advantageous shrinkage properties and good fatigue resistance for high-speed capability. The comparatively high tangent modulus of the cord at 4% elongation of at least 9.3 N / %, preferably at least 9.5 N / %, and particularly preferably 11 N / %, advantageously enables high circumferential forces in the tire, especially for use at high speeds. The high centrifugal forces occurring during high-speed operation can thus be better concentrated, improving high-speed capability. The high tangent modulus reduces dynamic growth and vibrations during high-speed operation. Limiting the cord's tangent modulus to a maximum of 14 N / % ensures sufficient elevation with moderate forces during tire construction.

[0015] Compared to a hybrid cord containing aramid, a tire equipped with a PA 6.6 cord is more cost-effective in terms of material costs. Furthermore, the PA 6.6 cord exhibits improved fatigue resistance, higher shrinkage forces, and easier processing than the hybrid cord containing aramid.

[0016] The belt bandage layer of the belt bandage, with its good shrinkage properties and its increased tangent modulus, is ideally suited to counteract the centrifugal forces occurring during high-speed use, keeping the belt edges down and thus forming a rounded contour of the tire, which is important for high speed.

[0017] The cords of the belt bandage layer of the belt bandage are arranged, as is usual for strength members of the belt bandage layer, at an angle between 0° and 5° to the circumferential direction of the tire, in particular wound or spooled along an axial width of the tire.

[0018] An advantageous embodiment is provided in that the belt bandage layer has a tangent modulus per cm width of the belt bandage layer of 8300 N / cm to 14000 N / cm, preferably of 8500 N / cm to 13000 N / cm, at 4% elongation of the belt bandage layer in the extension direction of the cords.

[0019] The tangent modulus per cm of the belt bandage layer width corresponds to the tangent modulus of the cords times the number of cords per cm of the belt bandage layer width. It has been shown that a pneumatic vehicle tire with this type of belt bandage layer offers particularly good high-speed capability while simultaneously providing sufficient tire construction relief.

[0020] An advantageous embodiment is characterized in that the cords have the construction PA 6.6 1880 dtex x 2.

[0021] Thus, two PA 6.6 yarns with a gauge of 1880 dtex are end-twisted together to form a cord. Measurements of the force-elongation curve of such a cord have shown that, compared to a PA 6.6 1400 dtex x 2 cord, such a cord already has a significantly increased tangent modulus, which is advantageous for high-speed performance, despite only a slight increase in diameter.

[0022] For example, a cord of PA 6.6 1880 dtex x 2 construction has a tangent modulus of 11.8 N / %, whereas the corresponding reference cord of PA 6.6 1400 dtex x 2 construction has a tangent modulus of only 9.0 N / %, 2.8 N / % lower, both measured at an elongation of 4%. The cord and the reference cord each have the same twist factor of 150.

[0023] The thicker cord with the increased use of PA 6.6 also has higher shrinkage forces, which is further advantageous for high-speed suitability.

[0024] A pneumatic vehicle tire with such a belt bandage layer thus offers improved high-speed capability with only slightly increased rolling resistance. At the same time, the tire is cost-effective in terms of material usage and production.

[0025] An advantageous embodiment is characterized in that the cords are arranged with a thread density of 80 epdm to 100 epdm, preferably from 85 epdm to 95 epdm, particularly preferably with a thread density of 90 epdm.

[0026] Surprisingly, it has been shown that such a belt bandage layer has an excellent tangent modulus per cm width of the belt bandage layer with good shrinkage properties.

[0027] An advantageous embodiment is provided in that the cords have the construction PA 6.6 1880 dtex x 2 and are arranged with a thread density of 80 epdm to 100 epdm, preferably from 85 epdm to 95 epdm, particularly preferably with a thread density of 90 epdm.

[0028] Surprisingly, it has been shown that a belt bandage layer F1 according to the invention, which has cords of construction 1880 dtex x 2 and an arrangement of the cords with a thread density of 90 epdm, has a tangent modulus at 4% elongation of the belt bandage layer in the extension direction of the cords that is over 2500 N / cm higher than the corresponding tangent modulus of a reference layer R1, which has reference cords of construction 1400 dtex x 2, which are also arranged with a thread density of 90 epdm. The belt bandage layer F1 according to the invention has a tangent modulus per cm of width of 10580 N / cm at an elongation of 4%. The cords and the reference cords each have the same twist factor of 150.

[0029] A pneumatic vehicle tire comprising such a belt bandage layer F1 according to the invention in the belt bandage exhibits excellent high-speed capability. The thickness and material used in the belt bandage layer are only slightly increased, so that rolling resistance is not significantly increased.

[0030] Furthermore, a comparison of the two belt bandage layers F1 and R1 showed that at an elongation of 19% of the respective layer, the strength of the aforementioned belt bandage layer F1 according to the invention is increased by 526 N / cm compared to the belt bandage layer R1. At the same time, the fracture energy of the belt bandage layer F1 according to the invention is increased compared to the belt bandage layer R1, resulting in advantages in the plunger.

[0031] Each yarn of the belt bandage layer can be twisted in the S- or Z-direction. An advantageous embodiment is achieved when the two yarns of the cord have the same twist direction. Thus, they are both twisted in either the S- and / or Z-direction. According to the invention, the two yarns of the cord are end-twisted together to form the cord in the S- or Z-direction. Preferably, the twist direction to the cord is opposite to the twist direction of the yarns. This reduces internal tensions in the cord.

[0032] To ensure reliable adhesion of the textile cord to the rubber, it is advantageous for the cords to be impregnated with an adhesive to ensure the cords' adhesion to the rubber. For example, this impregnation can be achieved with an RFL dip in a one- or two-bath process. However, all other impregnation methods and adhesives known to those skilled in the art are also conceivable.

[0033] According to the invention, the twist factor of the cord is 120 to 220, preferably 130 to 200, particularly preferably 140 to 180.

[0034] The twist factor is defined as Twist Factor = Twist [t / m] x (Fineness [dtex] / 10,000) 1 / 2< . The twist factor is a measure of the final twist per meter of the cord, relative to the cord's fineness. This twist factor represents a favorable compromise between fatigue resistance and strength. A lower twist factor would be detrimental to fatigue resistance, while a higher twist factor would result in lower cord strength.

[0035] An advantageous embodiment is characterized in that at least one cord is arranged over the entire axial extent of the belt and beyond.

[0036] Thus, the belt binding layer comprising the at least one cord is a continuous belt binding layer that extends over the entire axial extent of the belt and covers the belt edges. This allows the advantageous effect of the high tangent modulus to unfold over the entire axial extent of the belt, including the belt edges.

[0037] Pneumatic vehicle tires for passenger cars, vans, or light trucks typically have a belt construction with at least two reinforcement layers and a carcass with textile reinforcements. The belt is covered, at least in the area of ​​the belt edges, by a single- or multi-layer belt bandage. The carcass has textile reinforcements that can form an angle of up to 6° with the tire's radial direction rR in the area of ​​the sidewalls.

[0038] An advantageous embodiment is characterized in that it is a passenger car.

[0039] High-speed capability is of particular relevance and advantage for passenger car tires.

[0040] An advantageous embodiment is characterized in that it is a light truck or a van.

[0041] All embodiments of the pneumatic vehicle tire according to the invention presented in this description represent examples of the embodiment of the invention and are not to be considered restrictive. Accordingly, individual or multiple features of an embodiment alone, or the combination of features of various embodiments, provide further embodiments of the invention, which are the subject matter of the invention, unless explicitly stated otherwise in the description. Furthermore, combinations of preferred and particularly preferred embodiments can also be combined with one another.

[0042] Further features, advantages and details of the invention will now be explained in more detail with reference to the schematic drawing, which shows an embodiment. Fig. 1 a radial cross-section through a pneumatic vehicle tire according to the invention, Fig. 2a cut through a belt bandage layer.

[0043] The Figure 1shows a radial cross-section through a pneumatic vehicle tire according to the invention for a passenger car. However, the invention is equally suitable for a tire for a light motor vehicle. The essential components of the illustrated pneumatic vehicle tire are a largely air-impermeable inner layer 1, a carcass 2, in particular of a radial design, with textile carcass reinforcements, which extends in a conventional manner from the crown region of the pneumatic vehicle tire over the sidewalls 3 to the bead regions 4 and is anchored there by wrapping around high-tensile bead cores 5. The carcass reinforcements can enclose an angle of up to 6° with the radial direction rR of the tire in the region of the sidewalls.Furthermore, the pneumatic vehicle tire has a profiled tread 6 located radially outside the carcass 2 and a belt 7 arranged between the tread 6 and the carcass 2, in particular containing two reinforcement layers, which is covered radially outside with a single- or multi-layer belt bandage 8. The belt bandage 8 covers at least the belt edges 9 and includes at least one belt bandage layer.

[0044] The belt bandage layer comprises textile cords 20 as strength members, which are arranged essentially parallel to one another and embedded in elastomeric material 11, wherein the cords 20 each comprise exactly two yarns, and wherein the two yarns are yarns made of polyamide 6.6 (PA 6.6), which have the same fineness and are end-twisted together to form the cord 20. A section through a corresponding belt bandage layer is shown in Fig. 2The cords 20 are shown only schematically. The cords 20 of the belt bandage layer of the belt bandage 8 are arranged, as is usual for reinforcement members of the belt bandage layer, at an angle between 0° and 5° to the circumferential direction of the tire, in particular wound or spooled along an axial width of the tire.

[0045] The belt bandage 8 can have one, two, or more belt bandage layers according to the invention. Preferably, all belt bandage layers of the tire's belt bandage 8 are designed according to the invention. Preferably, at least one cord 20 is arranged over the entire axial extent of the belt 7 and beyond.

[0046] The cords 20 have a tangent modulus of 9.3 N / % to 14 N / %, preferably 9.5 N / % to 13 N / %, particularly preferably 11 N / % to 12.5 N / %, at an elongation of 4%. The tangent modulus of a cord at a specific elongation corresponds to the slope of the force-elongation curve at the respective elongation of the cord, wherein the force-elongation curve is determined according to ASTM D 885 / ASTM D 885 M. The force-elongation curve can be determined on the stretched and dipped cord provided with an adhesive prior to incorporation into the elastomeric material.

[0047] The belt bandage layer of the belt bandage 8 has a tangent modulus per cm width of the belt bandage layer of 8300 N / cm to 14000 N / cm, preferably of 8500 N / cm to 13000 N / cm, at 4% elongation of the belt bandage layer in the extension direction of the cords 20.

[0048] The cords 20 of the reinforcements can have a PA 6.6 1880 dtex x 2 construction. They can be arranged with a thread density of 80 epdm to 100 epdm, preferably 85 epdm to 95 epdm, particularly preferably 90 epdm. According to the invention, they can have a twist factor of 120 to 220, preferably 130 to 200, particularly preferably 140 to 180. List of reference symbols

[0049] 1Inner layer 2Carcass 3Sidewall 4Bead area 5Bead core 6Tread 7Belt 8Belt bandage 9Belt edge 11Elastomeric material 20Cord aRaxial direction rRradial direction UCircumferential direction

Claims

1. Pneumatic vehicle tyre having a carcass (2) with textile carcass strength elements, a belt (7) arranged radially outside the carcass, and a belt bandage ply of a belt bandage (8) arranged radially outside the belt (7), wherein the belt bandage ply has textile cords (20) as strength elements, which are arranged substantially parallel to one another and are embedded in elastomeric material (11), wherein the cords (20) each have precisely two yarns, wherein the two yarns are yarns of polyamide 6.6, which have the same linear density and are end-twisted together to form the cord (20), characterized in that the cords (20) at an elongation of 4% have a tangent modulus of 9.3 N / % to 14 N / %, preferably of 9.5 N / % to 13 N / %, particularly preferably of 11 N / % to 12.5 N / %, and in that the twist factor of the cord (20) is 120 to 220, wherein the twist factor is defined as twist factor = twist [t / m] x (linear density [dtex] / 10000)1 / 2.

2. Pneumatic vehicle tyre according to Claim 1, characterized in that the belt bandage ply at 4% elongation of the belt bandage ply in the direction of extent of the cord (20) has a tangent modulus per cm width of the belt bandage ply of 8300 N / cm to 14000 N / cm, preferably of 8500 N / cm to 13000 N / cm.

3. Pneumatic vehicle tyre according to at least one of the preceding claims, characterized in that the cords (20) have the structure PA 6.6 1880 dtex x 2.

4. Pneumatic vehicle tyre according to at least one of the preceding claims, characterized in that the cords (20) are arranged with a thread density of 80 epdm to 100 epdm, preferably of 85 epdm to 95 epdm, particularly preferably with a thread density of 90 epdm.

5. Pneumatic vehicle tyre according to at least one of the preceding claims, characterized in that the twist factor of the cord (20) is 130 to 200, preferably 140 to 180.

6. Pneumatic vehicle tyre according to at least one of the preceding claims, characterized in that the cords (20) have an adhesive impregnation to ensure the adhesion of the cords to the rubber.

7. Pneumatic vehicle tyre according to at least one of the preceding claims, characterized in that at least one cord (20) is arranged over the entire axial extent of the belt (7) and beyond.

8. Pneumatic vehicle tyre according to at least one of the preceding claims, characterized in that the vehicle is a passenger car.

9. Pneumatic vehicle tyre according to at least one of Claims 1-7, characterized in that the vehicle is a light-duty vehicle or a van.