Vehicle tyre

Abstract

The invention relates to a vehicle tyre having a tread (1) with at least one sipe-channel combination (2) which, seen in cross section, is made up of a radially inner channel region (5) and a radially outer sipe region (4), wherein the tread (1) has a radially inner tread layer (1a) and a radially outer tread layer (1b). The radially inner channel region (5) is embedded in the radially inner tread layer and in the radially outer tread layer (1a, 1b), wherein between the tread layers (1a, 1b) there is a material limit (1c) which borders the radially inner channel region (5) and is interrupted by same, wherein the first rubber material, of which the radially inner tread layer (1a) consists, has a CSRI of up to 110, calculated according to the following equation: (I) CSRI compound stone trapping retention index, G' (100%) [kPa] dynamic storage modulus at 100% expansion in kilopascal, determination in accordance with ASTM D6601-19, σ (300%) [MPa] tension value at 300% expansion in megapascal, determination in accordance with DIN 53504 (DIN 53504 : 2017-03).

Description

[0001] Description

[0002] vehicle tires

[0003] The invention relates to a vehicle tire, in particular a commercial vehicle tire, with a tread having at least one cut-channel combination extending from the tread periphery, which has a maximum depth of 70% to 100% of the tread depth in the radial direction and, viewed in cross-section, is composed of a radially inner channel region and a radially outer cut-channel region with a minimum width of 0.4 mm to 3.0 mm, determined parallel to the tread periphery, wherein the radially inner channel region has a larger cross-sectional area than the radially outer cut-channel region and a maximum width of 150% to 650% of the minimum width, determined parallel to the tread periphery, wherein the tread has a radially inner tread layer made of a first rubber material and, adjacent to the latter, a radially outer tread layer made of a second rubber material different from the first rubber material.

[0004] Such a vehicle tire is known, for example, from EP 3 984 775 A1. The vehicle tire has a profiled tread with profile positives in which cut-channel combinations consisting of a radially inner channel region and a radially outer cut region with a maximum width of 2.5 mm run. The tread is composed of three tread layers in the radial direction. In one embodiment, the radially inner channel region is located entirely in the middle tread layer. The rubber material of the middle tread layer is optimized with regard to abrasion properties and has a loss factor tan δ which is greater than the loss factor tan δ of the rubber material of the radially innermost tread layer and which is either smaller or greater than the loss factor tan δ of the rubber material of the radially outermost tread layer.The tire should have good water drainage properties while maintaining high abrasion resistance.

[0005] Another vehicle tire of the type mentioned above is known from JP 432 796 2 B2. This vehicle tire has a tread with rows of tread blocks with tread blocks separated from one another by transverse grooves, wherein the tread blocks are each provided in the center with a circumferentially running groove-sipe combination with a maximum depth of, for example, 7 mm. Viewed in cross-section, the groove-sipe combination is composed of a radially inner channel region and a radially outer sipe region. The radially outer sipe region has a constant width of, for example, 0.5 mm and a length in the radial direction of, for example, 4.0 mm. The radially inner channel region has a maximum width of, for example, 1.5 mm and therefore 300% of the width of the radially outer sipe region.According to one embodiment, the tread is composed of a radially outer tread layer and a radially inner tread layer, with the radially inner tread layer being curved into the tread blocks such that the radially inner channel region is embedded in the radially inner tread layer. The loss factor at 0°C of the rubber material of the radially inner tread layer is 5% to 45% greater than the loss factor at 0°C of the rubber material of the radially outer tread layer. The vehicle tire should have good wet performance, especially with progressive tread wear, and good stiffness properties.

[0006] WO 2018 / 118023 A1 discloses a commercial vehicle tire with a tread consisting of a radially inner tread layer and a radially outer tread layer. The rubber material of the radially inner tread layer has a loss factor (max tan (θ)) of at most 0.07, and the rubber material of the radially outer tread layer has a loss factor (max tan (θ)) of at least 0.15. In one embodiment, grooves are formed in a profile rib of the tread in the region of the radially outer tread layer, said grooves comprising a radially inner channel region and a radially outer cut region. The commercial vehicle tire is intended to exhibit uniform wear behavior regardless of the orientation of the grooves.

[0007] WO 2017 / 105496 A1 discloses a vehicle tire with a tread consisting of a radially outer tread layer and a radially inner tread layer. The tread has grooves composed of a radially inner channel region with a circular cross-section and a radially outer cut region. The radially inner channel region is intended to prevent or suppress the occurrence of cracks in the adjacent rubber material. The rubber material of the radially outer tread layer has an MFTR value according to ISO 6943-2011 (Rubber, vulcanized - Determination of fatigue under tensile load) of at least 130,000. The rubber material of the radially inner tread layer has an MFTR value according to ISO 6943-2011 of at least 200,000, is said to have high fatigue resistance, and is optimized with regard to cracking resistance.The radially inner channel region can be located either in the radially inner tread layer or in the radially outer tread layer.

[0008] US 2021 / 0155046 A1 discloses a pneumatic vehicle tire with a tread having central profile blocks traversed by grooves that, in the radial direction, are composed of a radially outer cut region and a radially inner channel region. The tread is composed of a radially outer tread layer and a radially inner tread layer, with the grooves formed exclusively in the radially outer tread layer. The rubber material of the radially outer tread layer is intended to have good abrasion resistance, and the rubber material of the radially inner tread layer is intended to have good snow and wet grip properties. The rubber compounds underlying the rubber materials contain rubbers with different glass transition temperatures. In vehicle tires of the type mentioned above, the cut-channel combinations provided on the tread are advantageous, for example, for rolling resistance.As the tire rolls along the ground, the respective tread elements or segments support each other via the radially outer cut area, which contributes to a reduction in rolling resistance. The channel area ensures good braking performance on wet roads when the tread is worn. The cut-channel combination also significantly reduces the likelihood of stones penetrating the channel base.

[0009] After corresponding tread wear, namely after abrasion across the radially outer cut area, the radially inner channel area is clearly open to the tread periphery, so that the risk of foreign bodies, such as gravel, causing cuts in the rubber material adjacent to the radially inner channel area is significantly increased.

[0010] The invention is therefore based on the object of increasing the cut resistance of the tread rubber material in a vehicle tire of the type mentioned above as tread wear progresses.

[0011] The stated object is achieved according to the invention in that the radially inner channel region is embedded in the radially inner and the radially outer tread layer and between the tread layers there is a material boundary adjacent to the radially inner channel region and interrupted by this, wherein the first rubber material from which the radially inner tread layer consists has a CSRI of up to 110 determined according to the following equation:

[0012] 693kPa ■ 100 12.3MPa ■ 100

[0013] G'(100%)[fcPa] + <j(300%)[MPa] ( .in / _ _ CSRI Compound Stone Trapping Retention Index

[0014] G' (100%) [kPa] Dynamic storage modulus at 100% elongation in kilopascals, determined according to ASTM D6601-19 o (300%) [MPa] Stress value at 300% elongation in megapascals, determined according to DIN 53504 (DIN 53504 : 2017-03).

[0015] The rubber material of the radially inner tread layer thus exhibits a specific value of an index developed in-house, namely a specific CSRI value. The CSRI value is based on standardized rubber properties (dynamic storage modulus and modulus of elasticity). Since the radially outer cut area already provides good stone-repelling properties, the rubber material of the radially inner tread layer can be optimized for cut resistance, at least largely independent of its stone-repelling properties.

[0016] Particularly after the tread has been worn down to the level of the radially inner channel area (wear of the entire cut area), the channel area gradually opens or exposes significantly towards the tread periphery, thus ensuring the high cut resistance to foreign matter in the rubber material of the radially inner tread layer. This high cut resistance is ensured by an upper limit for the CSRI value, i.e., by a special coordination of two rubber properties—namely, the dynamic storage modulus and the modulus (see equation above).

[0017] According to a preferred embodiment, the second rubber material from which the radially outer tread layer is made has an elongation at break according to DIN 53504 of at least 430%, in particular of at least 440%, preferably of at least 450%, particularly preferably of at least 460%, most preferably of at least 470%. The elongation at break is an indicator of the chip / chunk resistance, whereby the higher the elongation at break £R, the better the expected chip / chunk resistance. It has been shown that a rubber material with the specified elongation at break has significantly improved chip / chunk resistance (see tire tests conducted on this site under point 3), especially during longer journeys on unpaved roads.

[0018] The cut resistance of the tread rubber material is further improved when the CSRI of the first rubber material is up to 100, preferably up to 90.

[0019] According to a further preferred embodiment, the stress value at 300% elongation of the first rubber material from which the radially inner tread layer is made is at least 10.5 MPa, in particular at least 11.0 MPa, preferably at least 12.0 MPa, and particularly preferably 12.5 MPa. This contributes to a low CSRI value, so that the cut resistance is further improved.

[0020] Furthermore, it is advantageous if the dynamic storage modulus at 100% elongation of the first rubber material from which the radially inner tread layer is made is at least 640 kPa, in particular at least 660 kPa, preferably at least 700 kPa, and particularly preferably at least 750 kPa. This also contributes to a low CSRI value, thus further improving cut resistance.

[0021] According to a further advantageous embodiment, the second rubber material from which the radially outer tread layer is made has a rebound resilience at a temperature of 23°C, determined according to ISO 4662, of up to 60, in particular up to 57, preferably up to 55. This is advantageous for wet braking performance.

[0022] For the rolling resistance of the vehicle tire, it is advantageous if the second rubber material from which the radially outer tread layer is made has a rebound resilience at a temperature of 70°C, determined according to ISO 4662, of at least 65, in particular of at least 67, preferably of at least 68. Since particularly favorable support effects occur in the region of the radially outer tread layer due to the geometry of the sipe-channel combination, namely the radially outer sipe region of the sipe-channel combination, an optimization of the radially outer tread layer with regard to rolling resistance is ensured in a manner that is at least essentially free of conflicting objectives.

[0023] According to a further preferred embodiment, the material boundary between the tread layers runs parallel to the tread periphery.

[0024] According to a further preferred embodiment, the material boundary is at a distance from the level of the maximum depth of the cut-channel combination in the radial direction, which is 10% to 80%, in particular 20% to 70%, preferably 30% to 50%, of the radially determined extension length of the radially inner channel region. The tread therefore has the particularly cut-resistant, radially outer tread layer down to a corresponding depth.

[0025] It is further preferred if the point of the incision-channel combination with the maximum width has a distance in the radial direction of 60% to 85%, in particular of at least 70%, of the extension length of the radially inner channel region determined in the radial direction from the deepest point of the incision-channel combination, i.e. to the level of the maximum depth.

[0026] A further preferred embodiment provides that the radially inner channel region has an extension length determined in the radial direction of 25% to 70%, in particular of 30% to 65%, preferably of up to 50%, of the maximum depth of the associated incision-channel combination, or that the extension length of the radially inner channel region is determined in the radial direction of 25% to 70%, in particular of 30% to 65%, preferably of up to 50%, of the maximum depth of the associated incision-channel combination. Furthermore, it is advantageous if the radially inner channel region has an extension length determined in the radial direction of at most 120%, in particular of at most 115%, preferably of at most 110%, particularly preferably of at most 105%, of its maximum width, orif the extension length of the radially inner channel region determined in the radial direction is at most 120%, in particular at most 115%, preferably at most 110%, particularly preferably at most 105%, of its maximum width.

[0027] A further advantageous embodiment provides that the radially outer cut region, viewed in cross-section, is composed in the radial direction of a first section starting from the tread periphery and widening in a V-shape towards this, and a second section narrowing in the manner of a cut and having the minimum width, wherein the first section has a maximum width at its radially outer end and an extension length in the radial direction of 25% to 50%, in particular of 30% to 45%, of the extension length of the cut region, wherein the first section is delimited by two flanks which run straight and each at an angle of 20° to 60°, in particular of 30° to 50°, to the radial direction, and wherein the minimum width, the extension lengths and the angle are particularly preferably coordinated with one another in such a way that the maximum width is 250% to 750%, in particular of 270% to 650%, preferably of 300% to 500%,the minimum width.,

[0028] Furthermore, it is advantageous if the radially outer tread layer is made of a rubber mixture containing fillers from the group consisting of carbon black(s), silica(s), and zinc oxide, wherein at least 60%, in particular at least 65%, preferably at least 75%, particularly preferably 85% to 90%, of the total amount of filler is from the group consisting of silica(s). The invention further relates to a method for producing a vehicle tire, in particular a commercial vehicle tire, with a tread having at least a sipe-channel combination, which has a maximum depth of 70% to 100% of the tread depth in the radial direction and, viewed in cross-section, is composed of a radially inner channel region and a radially outer sipe region with a minimum width of 0.4 mm to 3.0 mm, determined parallel to the tread periphery.wherein the radially inner channel region has a larger cross-sectional area than the radially outer cut region and a maximum width determined parallel to the tread periphery of 150% to 650% of the minimum width, wherein the tread has a radially inner tread layer made of a first rubber material and an adjacent radially outer tread layer made of a second rubber material different from the first rubber material, wherein the radially inner channel region is embedded in the radially inner and the radially outer tread layer and there is a material boundary between the tread layers adjacent to the radially inner channel region and interrupted by the latter,the method comprising the following successive steps: a) extruding a green tread with at least two rubber mixture webs arranged one above the other in the radial direction to form the radially inner and the radially outer tread layer of the tread,

[0029] ■ wherein the extruded green tread strip is provided with grooves which extend into the two rubber compound sheets, and / or

[0030] ■ wherein grooves are introduced, in particular cut or pressed, into the extruded green tread, wherein the grooves extend into the two rubber mixture sheets, b) construction of a green tire with the green tread, and c) vulcanization of the green tire in a vulcanization mold with mold segments for forming the tread, wherein the mold segments have profile webs for forming the cut-channel combinations of the tread profile, and wherein, during the molding of the green tire in the vulcanization mold, profile webs move into the grooves of the green tread. The method allows for particularly precise production of the vehicle tire with the tread in the desired two-layer design, particularly also in the region of the grooves.

[0031] Further features, advantages and details of the invention will now be described in more detail with reference to the drawing, which schematically shows an embodiment of the invention.

[0032] Fig. 1 is a simplified plan view of a section of a tread of a commercial vehicle tire in the area of ​​a circumferential groove and

[0033] Fig. 2 is a section along the line ll-ll of Fig. 1.

[0034] Vehicle tires designed according to the invention are tires for multi-track motor vehicles, with the vehicle tires being, in particular, commercial vehicle tires, particularly preferably for trucks or buses. The commercial vehicle tires are also preferably pneumatic vehicle tires, particularly of radial design, and are particularly intended for rims with a rim diameter of 17.5, 19.5, or 22.5 inches.

[0035] The invention relates to a vehicle tire with a tread having at least one geometrically specifically designed sipe-channel combination in conjunction with at least one tread layer exhibiting one or more specific rubber properties. The geometry of a sipe-channel combination is first discussed, followed by the rubber properties of the tread layers. Finally, tire test results are presented.

[0036] 1. Description of an incision-channel combination

[0037] Fig. 1 shows a plan view of a section of a tread 1 of a commercial vehicle tire in the area of ​​a specially designed circumferential groove 2 running straight in the circumferential direction, which is an example of a cut-channel combination and separates two profile ribs 3 that are only indicated in Fig. 1.

[0038] The circumferential groove 2 is designed in the radial direction to the respective intended tread depth TUR (Fig. 2), which for the preferred tire type (commercial vehicle tire) is typically 9.0 mm to 26.0 mm. According to Fig. 2, the circumferential groove 2, viewed in a cross-section oriented in the axial direction in plan view (cf. position of line II-II in Fig. 1), is composed of a radially outer cut region 4 and a radially inner channel region 5.

[0039] The following statements regarding the circumferential groove 2, i.e. the radially outer incision area 4 and the radially inner channel area 5, refer to the cross-section mentioned.

[0040] The circumferential groove 2 is designed symmetrically with respect to a line L running in the radial direction. Consequently, the notch region 4 and the channel region 5 are each designed symmetrically with respect to the line L.

[0041] The incision region 4 has - based on the line L - an extension length ci of 30% to 75% of the tread depth TUR in the radial direction and a minimum width bmin (width at the narrowest point) of 0.4 mm to 3.0 mm, in particular of 0.5 mm to 2.5 mm, preferably of 1.0 mm to 2.0 mm, in the axial direction. In the exemplary embodiment shown, the incision region 4 is composed in the radial direction of a chamfer-like widened section 4a extending from the tread periphery and a section 4b narrowed like an incision and opening into the channel region 5.

[0042] The widened section 4a has the shape of an isosceles trapezoid, widens in a V-shape towards the tread periphery, has a maximum width b in the axial direction at its radially outer end, i.e. at the tread periphery a(Width at the widest point), at its radially inner end, i.e. at the connection to the narrowed section 4b, in the axial direction the minimum width bmin and - based on the line L - in the radial direction an extension length cia of 25% to 50%, in particular of 30% to 45%, of the extension length ci of the incision area 4. The section 4a is delimited by two flanks 6, which run straight and to the radial direction each at an angle a of 20° to 60°, in particular of 30° to 50°. The minimum width bmin, the extension lengths ci, cia and the angle a are preferably coordinated with one another in such a way that the maximum width b a 250% to 750%, in particular 270% to 650%, preferably 300% to 500%, of the minimum width bmin.

[0043] The narrowed section 4b runs straight and in the radial direction, is limited by two flanks 7 running in the radial direction, has the mentioned minimum width bmin in the axial direction and - with respect to the line L - an extension length cib in the radial direction, the size of which follows from the extension lengths ci, cia.

[0044] The radially inner channel region 5 has a larger cross-sectional area than the radially outer incision region 4, is composed of a radially outer channel section 5a and a radially inner channel section 5b, has at the mutual connection of the channel sections 5a, 5b in the axial direction a maximum width bmax (width at the widest point) of 150% to 650%, in particular of 200% to 600%, preferably of 300% to 500%, particularly preferably of 350% to 450%, of the minimum width bmin and - based on the line L - in the radial direction an extension length C2 of 25% to 70%, in particular of 30% to 65%, preferably of up to 50%, of the profile depth TUR. Preferably, the extension length C2 and the maximum width bmax are matched to one another such that the extension length C2 is at most 120%, in particular at most 115%, preferably at most 110%, particularly preferably at most 105%, of the maximum width bmax.

[0045] The channel area 5 is delimited by a channel base 8 which runs along the profile depth TUR and simultaneously forms the groove base of the circumferential groove 2 and has a width bc determined in the axial direction of 2.0 mm to 5.0 mm, in particular of at least 3.0 mm, as well as by channel walls 9 which are curved into one profile rib 3 or into the other profile rib 3 and which run overall in an inverted and tilted L-shaped manner.

[0046] The channel walls 9 each run between the channel base 8 and the respective flank 7 in the narrowed section 4b, each have a straight, radially outer ceiling flank 9a located in the radially outer channel section 5a and a straight, radially inner side flank 9b located in the radially inner channel section 5b. In the exemplary embodiment, the channel walls 9 further each have three transition curves 9c, one of which runs between the channel base 8 and the radially inner side flank 9b, another between the radially inner side flank 9b and the ceiling flank 9a and yet another between the ceiling flank 9a and the respective flank 7' in the narrowed section 4b. The transition curves 9c ensure tangential transitions and in particular each run along a radius of preferably 1.0 mm to 2.0 mm.

[0047] The widest point with the maximum width bmax has a distance ai of 60% to 85%, in particular of at least 70%, of the extension length C2 from the deepest point of the circumferential groove 1, i.e. from the channel base 8, in the radial direction.

[0048] The ceiling flanks 9a each run at an angle β to the radial direction, wherein a mutual distance determined in the axial direction between the ceiling flanks 9 continuously increases towards the channel base 8 and therefore towards the point of maximum width bmax. The radially outer channel section 5a therefore widens continuously from the incision region 4 towards the channel base 8 up to the point of maximum width bmax. The side flanks 9b each run at an angle γ of 10° to 25°, in particular from 15° to 23°, preferably of at least 17°, to the radial direction, wherein a mutual distance determined in the axial direction between the side flanks 9b continuously decreases towards the channel base 8. The radially inner channel section 5b therefore narrows continuously from the point of maximum width bmax towards the channel base 8.Preferably, the distance ai, the maximum width bmax and the extension length C2 are coordinated such that the angle ß is 50° to 70°, in particular 55° to 60°.

[0049] According to Fig. 2, the tread 1 (Fig. 1) and thus each profile rib 3 is composed in the radial direction of a radially inner tread layer 1a and a radially outer tread layer 1b, wherein the tread layers 1a, 1b each consist of a rubber material (vulcanizate of a rubber mixture) and wherein - as will be explained in more detail - the rubber material of the radially inner tread layer 1a differs from the rubber material of the radially outer tread layer 1b, so that there is a material boundary 1c between the tread layers 1a, 1b. The material boundary 1c points, viewed in the cross section oriented in the axial direction, towards the radially inner end of the radially inner channel section 5b, i.e. to the level of the profile depth TUR orto the channel base 8, in the radial direction, a distance a2 which amounts to 10% to 80%, in particular 20% to 70%, preferably 30% to 50%, of the extension length C2 of the channel region 5, so that the material boundary 1c is locally interrupted by the radially inner channel region 5. The channel base 8 is thus co-formed by the rubber material of the radially inner tread layer 1a.

[0050] 2. Further description of the tread layers 1a, 1b

[0051] 2. 1 To the radially inner tread layer 1a

[0052] The rubber material of the radially inner tread layer 1 a is optimized with regard to its cut resistance to foreign bodies, such as gravel, and has a specific “CSRI”.

[0053] The CSRI (Compound Stone Trapping Retention Index) serves as an indicator of the rubber material's cut resistance to foreign bodies and its stone-repelling effect. The CSRI compares these properties (cut resistance and stone-repelling effect) to an internal reference rubber material, as will be explained in more detail below.

[0054] The higher the CSRI, the "softer" the rubber material. Compared to a rubber material with a lower CSRI, a rubber material with a higher CSRI more easily releases stones caught (jammed) in the tread due to the centrifugal forces generated during driving (good stone-repelling effect), but is less favorable in terms of cut resistance.

[0055] The smaller the CSRI, the stiffer the rubber material. A rubber material with a lower CSRI is more cut-resistant than a rubber material with a higher CSRI.

[0056] Due to the special geometric design of the circumferential groove 1, optimizing the rubber material of the radially inner tread layer 1a with regard to its stone-repellent effect (highest possible CSRI) is not a priority because the radially outer incision area 4 ensures a good stone-repellent effect, so that the risk of stones penetrating into the area of ​​the radially inner tread layer 1a is low.

[0057] The rubber material of the radially inner tread layer 1a exhibits a "small" CSRI and is thus optimized with regard to cut resistance. Particularly after the tread is worn down to the level of the radially inner channel region 5 (wear of the entire cut region 4), the channel region 5 gradually opens or is exposed significantly toward the tread periphery, so that high cut resistance of the rubber material of the radially inner tread layer 1a is particularly favorable.

[0058] The CSRI is calculated according to the following equation: 693 kPa ■ 100 12.3 MPa ■ 100 +

[0059] The symbols used in the equation are as follows:

[0060] G' (100%) [kPa] Dynamic storage modulus at 100% strain in kilopascals:

[0061] - Determination according to ASTM D6601-19: o Standard Test Method for Rubber Properties — Measurement of Cure and After-Cure Dynamic Properties Using a Rotorless Shear Rheometer o Last update 15.05.2019 o Vulcanization parameters (production of the test specimens):

[0062] ■ Vulcanization temperature 170°C

[0063] ■ Vulcanization time 10 minutes

[0064] - Measurement parameters: o 2nd deformation sweep (2nd deformation run) o Deformation sequence 1 Hz o Temperature 70°C o (300%) [MPa] Stress value at 300% strain in megapascals:

[0065] - Determination according to DIN 53504 (DIN 53504 : 2017-03): o Testing of rubber and elastomers - Determination of tear strength, tensile strength, elongation at break and stress values ​​in the tensile test o Edition 2017-03 o Vulcanization parameters (production of the test specimens):

[0066] ■ Vulcanization temperature 140°C

[0067] ■ Vulcanization time 30 minutes

[0068] - Measurement parameters: As specified in the standard.

[0069] The values ​​of 693 kPa and 12.3 MPa in Equation I are the values ​​of the aforementioned internal reference rubber material (see Tables 1 and 2 below), which is primarily used in conventional radially outer tread plies. This reference rubber material has a dynamic storage modulus at 100% strain (G' (100%)) of 693 kPa and a stress value at 300% strain (o (300%)) of 12.3 MPa. The CSRI of the reference rubber material was thus set at 100 (see Table 2 below). Dividing by 2 (see equation above) provides an "average" between the dynamic storage modulus at 100% strain (G' (100%)) and the stress value at 300% strain (o (300%)).As is known, the respective value of the dynamic storage modulus at 100% strain (G' (100%)) correlates with the value of the stress at 300% strain (o (300%)), whereby a larger dynamic storage modulus at 100% strain is associated with a larger stress at 300% strain.

[0070] The rubber material of the radially inner tread layer 1a has a CSRI of up to 110, in particular up to 100, preferably up to 90.

[0071] The rubber material of the radially inner tread layer 1 a further has a stress value at 300% elongation (o (300%)) which is in particular at least 10.5 MPa, preferably at least 11.0 MPa, particularly preferably at least 12.0 MPa, most preferably at least 12.5 MPa.

[0072] The rubber material of the radially inner tread layer 1a also has a dynamic storage modulus at 100% elongation (G' (100%)) which is in particular at least 640 kPa, preferably at least 660 kPa, particularly preferably at least 700 kPa, and most preferably at least 750 kPa.

[0073] Table 1 shows recipes, i.e. compositions of rubber mixtures, wherein the rubber mixture R belonging to the mentioned internal reference rubber material, a comparison rubber mixture V1, which is a rubber mixture customary for radially inner tread layers, in particular for a so-called tread base, and three rubber mixtures E1 a, E1 b, E1 c, which are examples according to the invention, are indicated.

[0074] Table 1 : Recipes (composition of rubber compounds, tread layer 1 a)

[0075] Table 2 shows the stress values ​​at 300% elongation (o (300%)), the dynamic storage modulus at 100% elongation (G' (100%)) and the CSRI calculated according to equation I of the rubber materials made from the rubber compounds R, V1, E1 a, E1 b, E1 c given in Table 1.

[0076] Table 2: Properties of the rubber materials (tread layer 1 a)

[0077] The rubber material from the comparison compound V1 has a CSRI of 117. The rubber materials from the rubber compounds E1 a, E1 b, and E1 c have a lower CSRI than the rubber material from the comparison compound V1, namely a CSRI of 109 (E1 a), 95 (E1 b), and 85 (E1 c), respectively, and are therefore significantly improved in terms of cut resistance compared to the rubber material from the comparison compound V1. A radially inner tread layer 1a consisting of the rubber material from the rubber compounds E1a, E1 b, and E1 c is therefore expected to exhibit very good cut resistance to foreign bodies.

[0078] 2.2 To the radially outer tread layer 1b

[0079] The rubber material of the radially outer tread layer 1 b is optimized with regard to chip / chunk resistance, which reflects the resistance of the rubber material to delamination under slip load, in particular while maintaining good wet braking performance and low rolling resistance.

[0080] The rebound resilience at a temperature of 23°C (R (23°C)) is used as an indicator of wet braking performance. The lower the rebound resilience, R (23°C), the better the expected wet braking performance. The rebound resilience, R (23°C), is a measure of damping, with the damping increasing with the lower the rebound resilience. With lower rebound resilience (higher damping) of the rubber material that comes into contact with the ground when the tire rolls, more energy is "dissipated," thereby improving the tire's wet braking performance.

[0081] The rebound resilience at a temperature of 70°C (R (70°C)) is used as an indicator of rolling resistance. The higher the rebound resilience, the lower the expected rolling resistance. Low rolling resistance is known to require low energy dissipation during tire rolling.

[0082] The theoretical background to the above indicators results from the different frequency effects on the rubber material of a vehicle tire braking on wet (water) and a freely rolling vehicle tire (cf. Williams-Landel-Ferry transformation, frequency-temperature superposition, temperature dependence of relaxation mechanisms).

[0083] The rebound resilience R (23°C) and R (70°C) were determined as follows:

[0084] - Determination according to ISO 4662: o Elastomers or thermoplastic elastomers - Determination of the resilience of vulcanizates o Pendulum method (pendulum test) according to section 5, thickness of the test piece 6.3 mm ± 0.5 mm (see Annex A - Use of non-standard test pieces) o Edition 2017-06 o Vulcanization parameters (production of the test pieces):

[0085] ■ Vulcanization temperature 140°C

[0086] ■ Vulcanization time 30 minutes

[0087] - Measurement parameters: As specified in the standard and at a temperature (test specimen temperature) of 23°C (for R (23°C)) or 70°C (for R (70°C)).

[0088] The elongation at break £R is used as an indicator for the chip / chunk resistance, whereby the higher the elongation at break £R, the better the expected chip / chunk resistance.

[0089] The elongation at break £R is determined according to DIN 53504 (DIN 53504 : 2017-03) (see above for details on the determination).

[0090] The rubber material of the radially outer tread layer 1 b has a rebound resilience R (23°C) of up to 60, in particular up to 57, preferably up to 55.

[0091] The rubber material of the radially outer tread layer 1b further has a rebound resilience R (70°C) of at least 65, in particular of at least 67, preferably of at least 68. The rubber material of the radially outer tread layer 1b also has an elongation at break £R of at least 430%, in particular of at least 440%, preferably of at least 450%, particularly preferably of at least 460%, most preferably of at least 470%.

[0092] The radially outer tread layer 1b is made of a rubber mixture containing exclusively carbon black, silica, and zinc oxide as fillers, with at least 60% (mass %), in particular at least 65%, preferably at least 75%, and particularly preferably 85% to 90%, of the total amount of fillers being silica. The amount of silica contained in the radially outer tread layer 1b, i.e., in the rubber material, can be determined by burning a rubber material sample and subsequently analyzing the remaining ash.

[0093] Table 3 shows recipes, i.e. compositions of rubber mixtures, where three comparative rubber mixtures V2a, V2b, V2c and a rubber mixture E2 designed according to the invention are or are given.

[0094] Table 3: Recipes (composition of rubber mixtures,

[0095] The rubber compound E2 contains 60 phr of silica, 5 phr of carbon black, and 3 phr of zinc oxide as fillers. The total filler content is therefore 68 phr. The (mass) proportion of silica - based on the total filler content - is therefore approximately 88% (= (60 / 68) * 100).

[0096] Table 4 shows the mentioned properties of the rubber materials made from the rubber compounds given in Table 3.

[0097] Table 4: Properties of the rubber materials (tread layer 1 b)

[0098] Compared to the rubber materials from the rubber compounds V2a, V2b, and V2c, the rubber material from the rubber compound E2 exhibits the highest elongation at break ER, namely an elongation at break of 473%. This elongation at break is significantly greater than that of the rubber material from the rubber compounds V2a and V2b, and slightly or insignificantly greater than that of the rubber material V2c. A radially outer tread layer 1b made of the rubber material from the rubber compound E2 is therefore expected to offer very good chip / chunk resistance.

[0099] The rubber material made from the rubber compound E2 also has - in

[0100] Compared to the rubber materials from the rubber compounds V2a, V2b, and V2c, the tread exhibits the second-lowest rebound resilience R (23°C), namely a rebound resilience R (23°C) of 52.9. A radially outer tread layer 1b consisting of the rubber material from the rubber compound E2 is therefore expected to continue to provide good wet braking performance.

[0101] In addition, the rubber material from the rubber compound E2 has - in comparison to the rubber materials from the rubber compounds V2a, V2b, V2c

[0102] - the second-highest rebound resilience R (70°C), namely a rebound resilience R (70°C) of 68.2. A radially outer tread layer 1b consisting of the rubber material of the rubber compound E2 is therefore expected to continue to have good (low) rolling resistance.

[0103] As already mentioned, the rubber material of the radially outer tread layer 1 b is thus optimized with regard to chip / chunk resistance while maintaining good wet braking performance and low rolling resistance.

[0104] 3. Tire tests

[0105] Truck tires in the size 205 / 75 R 17.5 (tire designation CHS3 124L) were manufactured with a two-layer tread 1, with the radially inner tread layer 1a made of the rubber compound E1c and the radially outer tread layer 1b made of the rubber compounds V2a, V2b, V2c, or E2. The wet braking performance, rolling resistance, and chip / chunk resistance of the tires, i.e., the radially outer tread layer 1b, were tested. The test conditions are given below.

[0106] Test for wet braking performance:

[0107] - Air temperature: 17°C to 21°C

[0108] - Road temperature: 17°C to 21°C

[0109] - ABS: Yes

[0110] - Speed: 80 km / h Rolling resistance test:

[0111] - Determination according to ISO 28580 o Car, truck and bus tyre rolling resistance measurement method - Single-point test and correlation of the measurement results

[0112] Chip / Chunk resistance test:

[0113] - Axle position: drive axle

[0114] - Driving distance: 964 km

[0115] - Route condition: Rough road (gravel)

[0116] - Air temperature: 10°C to 15°

[0117] - Assessment: Relative comparison of damage to the treads by visual inspection

[0118] Table 5 contains the tire test results, with the values ​​for the tire featuring the radially outer tread layer 1b made of rubber compound V2a set to 100. Values ​​less than 100 indicate a deterioration in the respective tire property compared to the tire with the tread whose radially outer tread layer 1b was made of rubber compound V2a. Values ​​greater than 100 indicate an improvement in the respective tire property compared to the aforementioned tire.

[0119] Table 5: Tire test results

[0120] On chip / chunk resistance

[0121] According to Table 5, the tires with a tread featuring a radially outer tread layer made of rubber compound E2 showed significantly better chip / chunk resistance (116) than the tires with a tread featuring a radially outer tread layer made of one of the rubber compounds V2a (100), V2b (5), or V2c (95). The chip / chunk resistance of the tire with a tread featuring a radially outer tread layer made of rubber compound V2b was unacceptable.

[0122] For wet braking performance

[0123] In addition, the tires with a tread having the radially outer tread layer made of rubber compound E2 showed the best wet braking performance (120) of all tires, whereby the wet braking performance was significantly better than those tires whose tread had a radially outer tread layer made of rubber compound V2a or V2b, and whereby the wet braking performance was essentially comparable to those tires whose tread had the radially outer tread layer made of rubber compound V2c (119).

[0124] About rolling resistance

[0125] The rolling resistance (102) of the tires with the tread made of rubber compound E2, radially outer tread layer, was comparable to the rolling resistance of the tires with the tread made of rubber compounds V2a and V2c, respectively. While the rolling resistance of the tires with the tread made of rubber compound V2b, radially outer tread layer, was better (lower) than the rolling resistance of the tires with the radially outer tread layer made of rubber compound E2, the chip / chunk resistance (5) of the former tire was unacceptable, as already mentioned above.

[0126] The test results therefore show that a radially outer tread layer 1b made of the rubber material of rubber compound E2 improves chip / chunk resistance while maintaining good wet braking performance and low rolling resistance. Wet braking performance is also improved. 4. Method for producing a vehicle tire, in particular a commercial vehicle tire

[0127] A method for producing a vehicle tire according to the invention comprises the following steps: a) extruding a green tread with at least two rubber mixture webs arranged one above the other in the radial direction to form the tread layers, o wherein the extruded green tread is provided with grooves which extend into two rubber mixture webs, and / or o wherein grooves are introduced, in particular cut or pressed into, the extruded green tread, wherein the grooves extend into the two rubber mixture webs, b) building up a green tire with the green tread and c) vulcanizing the green tire in a vulcanization mold with mold segments for forming the tread, wherein the mold segments have profile webs for forming the grooves of the tread profile and wherein, when the green tire is molded in the vulcanization mold, profile webs move into the grooves of the green tread.

[0128] 5. Further examples

[0129] The invention is not limited to the described embodiment.

[0130] As already mentioned, the circumferential groove explained in the exemplary embodiment is an example of a notch-channel combination. The notch-channel combination can, for example, also be a correspondingly designed transverse groove that runs at an angle to the circumferential direction when viewed from above, and which, viewed from above, runs at an angle of, in particular, 0° to 50° to the axial direction.

[0131] The sipe-channel combination has a maximum depth (depth at the deepest point) of 70% to 100%, in particular of at least 80%, of the tread depth (depth of the respective deepest groove(s)) in the radial direction. The radially outer sipe region 4 can be designed without a widened section 4a, so that the radially outer sipe region 4 is formed exclusively by the sipe-like narrowed section 4b. In this design, the narrowed section 4b thus extends to the tread periphery.

[0132] The tread 1 can, in the radial direction, have one or more further tread layers in addition to the tread layers 1a, 1b. The radially inner channel region 5 is embedded in the radially inner and the radially outer tread layer 1a, 1b. The radially outer tread layer 1b therefore extends at least to the radially outer end of the radially inner channel region 5, and the radially inner tread layer 1a surrounds the lowest point of the radially inner channel region 5. The radially outer tread layer 1b is preferably spaced from the tread periphery in the radial direction by a maximum of 3.0 mm.

[0133] The radially outer tread layer 1b may consist of a rubber material which differs from the rubber material described in the context of the exemplary embodiment.

[0134] List of reference symbols 1 Tread

[0135] 1a radial inner tread layer

[0136] 1 b radial outer tread layer

[0137] 1c Material boundary

[0138] 2 circumferential groove 3 profile rib

[0139] 4 radial outer incision area

[0140] 4a widened section

[0141] 4b narrowed section

[0142] 5 radially inner channel area 5a radially outer channel section

[0143] 5b radial inner channel section

[0144] 6 flank

[0145] 7 flank

[0146] 8 Canal bottom 9 Canal wall

[0147] 9a Ceiling flank

[0148] 9b side flank

[0149] 9c Transition curve ai , a2 distance b a Maximum width bc Width bmax . Maximum width bmin . Minimum width ci, cia, cib, C2.. Extension length L > . Line

[0150] TUR profile depth a, ß, Y angle

Claims

Patent claims 1. Vehicle tire, in particular commercial vehicle tire, with a tread (1) with at least one cut-channel combination (2) extending from the tread periphery, which has a maximum depth (TUR) of 70% to 100% of the profile depth (TUR) in the radial direction and, viewed in cross-section, is composed of a radially inner channel region (5) and a radially outer cut-channel region (4) with a minimum width (bmin) of 0.4 mm to 3.0 mm, determined parallel to the tread periphery, wherein the radially inner channel region (5) has a larger cross-sectional area than the radially outer cut-channel region (4) and a maximum width (bmax) of 150% to 650% of the minimum width (bmin), determined parallel to the tread periphery,wherein the tread (1) has a radially inner tread layer (1a) made of a first rubber material and a radially outer tread layer (1b) adjacent thereto made of a second rubber material different from the first rubber material, characterized in that the radially inner channel region (5) is embedded in the radially inner and the radially outer tread layer (1a, 1b) and between the tread layers (1a, 1b) there is a material boundary (1c) adjacent to the radially inner channel region (5) and interrupted by the latter, wherein the first rubber material of which the radially inner tread layer (1a) consists has a CSRI of up to 110 determined according to the following equation: 693kPa ■ 100 12.3MPa ■ 100 + CSRI Compound Stone Trapping Retention Index G' (100%) [kPa] Dynamic storage modulus at 100% strain in kilopascals, Determined according to ASTM D6601-19 o (300%) [MPa] Stress value at 300% elongation in megapascals, determined according to DIN 53504 (DIN 53504 : 2017-03).

2. Vehicle tire according to claim 1, characterized in that the second rubber material from which the radially outer tread layer (1 b) consists has an elongation at break (ER) according to DIN 53504 of at least 430%, in particular of at least 440%, preferably of at least 450%, particularly preferably of at least 460%, most preferably of at least 470%.

3. Vehicle tire according to claim 1 or 2, characterized in that the CSRI of the first rubber material is up to 100, preferably up to 90.

4. Vehicle tire according to one of claims 1 to 3, characterized in that the stress value at 300% elongation (o (300%)) of the first rubber material from which the radially inner tread layer (1a) consists is at least 10.5 MPa, in particular at least 11.0 MPa, preferably at least 12.0 MPa, and particularly preferably 12.5 MPa.

5. Vehicle tire according to one of claims 1 to 4, characterized in that the dynamic storage modulus at 100% elongation (G' (100%)) of the first rubber material from which the radially inner tread layer (1a) consists is at least 640 kPa, in particular at least 660 kPa, preferably at least 700 kPa, and particularly preferably at least 750 kPa.

6. Vehicle tire according to one of claims 1 to 5, characterized in that the second rubber material from which the radially outer tread layer (1 b) consists has a rebound resilience at a temperature of 23°C (R (23°C)), determined according to ISO 4662, of up to 60, in particular of up to 57, preferably of up to 55.

7. Vehicle tire according to one of claims 1 to 6, characterized in that the second rubber material from which the radially outer tread layer (1 b) is made has a rebound resilience at a temperature of 70°C (R (70°C)), determined according to ISO 4662, of at least 65, in particular of at least 67, preferably of at least 68.

8. Vehicle tire according to one of claims 1 to 7, characterized in that the material boundary (1 c) between the tread layers (1 a, 1 b) runs parallel to the tread periphery.

9. Vehicle tire according to one of claims 1 to 8, characterized in that the material boundary (1 c) has a distance (a2) from the level of the maximum depth (TUR) of the cut-channel combination (2) in the radial direction, which distance is 10% to 80%, in particular 20% to 70%, preferably 30% to 50%, of the extension length (C2) of the radially inner channel region (5) determined in the radial direction.

10. Vehicle tire according to one of claims 1 to 9, characterized in that the point of the cut-channel combination (2) with the maximum width (bmax) to the deepest point of the cut-channel combination (2), i.e. to the level of the maximum depth (TUR), in the radial direction has a distance (ai) of 60% to 85%, in particular of at least 70%, of the extension length (C2) of the radially inner channel region (5) determined in the radial direction.

11. Vehicle tire according to one of claims 1 to 10, characterized in that the radially inner channel region (5) has an extension length (C2) determined in the radial direction of 25% to 70%, in particular of 30% to 65%, preferably of up to 50%, of the maximum depth (TUR) of the associated cut-channel combination (2) or that the extension length (C2) of the radially inner channel region (5) determined in the radial direction is 25% to 70%, in particular of 30% to 65%, preferably of up to 50% of the maximum depth (TUR) of the associated incision-channel combination (2).

12. Vehicle tire according to one of claims 1 to 11, characterized in that the radially inner channel region (5) has an extension length (C2) determined in the radial direction of at most 120%, in particular of at most 115%, preferably of at most 110%, particularly preferably of at most 105%, of its maximum width (bmax) or that the extension length (C2) of the radially inner channel region (5) determined in the radial direction is at most 120%, in particular of at most 115%, preferably of at most 110%, particularly preferably of at most 105%, of its maximum width (b max ).

13. Vehicle tire according to one of claims 1 to 12, characterized in that the radially outer cut region (4), viewed in cross section, is composed in the radial direction of a first section (4a) extending from the tread periphery and widening towards it in a V-shape, and a second section (4b) narrowing in the manner of a cut and having the minimum width (bmin), wherein the first section (4) has a maximum width (b a) and in the radial direction has an extension length (cia) of 25% to 50%, in particular of 30% to 45%, of the extension length (ci) of the incision region (4), wherein the first section (4a) is delimited by two flanks (6) which run straight and to the radial direction at an angle (a) of 20° to 60°, in particular of 30° to 50°, and wherein the minimum width (bmin), the extension lengths (ci, cia) and the angle (a) are particularly preferably coordinated with one another in such a way that the maximum width (ba) is 250% to 750%, in particular of 270% to 650%, preferably of 300% to 500%, of the minimum width (bmin).

14. Vehicle tyre according to one of claims 1 to 13, characterised in that the radially outer tread layer (1b) consists of a rubber mixture which contains fillers from the group carbon black(s), silica(s) and zinc oxide, wherein at least 60%, in particular at least 65%, preferably at least 75%, particularly preferably 85% to 90%, of the total amount of filler is or are from the group silica(s).

15. A method for producing a vehicle tire, in particular a commercial vehicle tire, with a tread (1) with at least a sipe-channel combination (2) which has a maximum depth (TUR) of 70% to 100% of the profile depth (TUR) in the radial direction and, viewed in cross-section, is composed of a radially inner channel region (5) and a radially outer sipe region (4) with a minimum width (bmin) of 0.4 mm to 3.0 mm, determined parallel to the tread periphery, wherein the radially inner channel region (5) has a larger cross-sectional area than the radially outer sipe region (4) and a maximum width (bmax) of 150% to 650% of the minimum width (bmin), determined parallel to the tread periphery,wherein the tread (1) has a radially inner tread layer (1a) made of a first rubber material and a radially outer tread layer (1b) adjacent thereto made of a second rubber material different from the first rubber material, wherein the radially inner channel region (5) is embedded in the radially inner and the radially outer tread layer (1a, 1b) and between the tread layers (1a, 1b) there is a material boundary (1c) adjacent to the radially inner channel region (5) and interrupted by the latter, wherein the method comprises the following successive steps: a) extruding a green tread with at least two rubber mixture webs arranged one above the other in the radial direction to form the radially inner and the radially outer tread layer (1a, 1b) of the tread (1), ■ wherein the extruded green tread is provided with grooves which extend into the two rubber mixture webs, and / or ■ wherein grooves are introduced into the extruded green tread, in particular cut or pressed in, wherein the grooves extend into the two rubber mixture sheets, b) construction of a green tire with the green tread and c) vulcanization of the green tire in a vulcanization mold with mold segments for forming the tread, wherein the mold segments have profile webs for forming the cut-channel combinations of the tread profile and wherein profile webs move into the grooves of the green tread when the green tire is formed in the vulcanization mold.

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