Vehicle pneumatic tires

Abstract

A radial-type pneumatic tire for vehicles, comprising a tread (1), a belt assembly (2) consisting of several belt layers (2a, 2b, 2c, 2d), a carcass ply (3), an inner layer (4), and a rubber component (6) in each shoulder area, wherein the rubber component (6) is made of a rubber compound containing 30 phr to 60 phr of carbon black as a filler, characterized in that the rubber compound of the rubber component further contains 80 phr to 140 phr of kaolin as a filler and at least one styrene-butadiene rubber in amounts of up to 100 phr, wherein the rubber component (6) is a shoulder pad (6) which extends radially outside and along the carcass ply (3) and, viewed in cross-section, has an inner section (6a) and an outer section (6b) which are formed by a segmentation of the shoulder pad (6) at the edge of the widest belt layer (2c).

Description

[0001] Pneumatic vehicle tyre of radial construction with a tread, a belt assembly consisting of several belt layers, a carcass ply, an inner layer and a rubber component in each shoulder area, wherein the rubber component is made of a rubber compound which contains carbon black as a filler.

[0002] It is well known that pneumatic vehicle tires, especially commercial vehicle tires, are subjected to particularly severe stress in the belt edge area during operation, resulting in heat generation at the belt edges, which impairs tire durability. The commonly used steel reinforcements also promote the transfer of the resulting heat to the shoulder areas of the tire. Since the vulcanizates of the rubber compounds commonly used in tires have poor thermal conductivity properties, the resulting heat builds up. The associated thermal aging of the rubber negatively impacts the durability of tire components and thus the retreading rate of commercial vehicle tires.

[0003] From DE 196 52 893 A1, it is known to arrange belt edge profiles in the area of ​​the belt edges between the belt layers. The vulcanizates of the rubber compounds underlying the belt edge profiles have a Shore A hardness corresponding to 60% to 95% of the Shore A hardness of the rubber coating compounds of the belt layers. The rebound resilience at 70°C of the rubber compound of the belt edge profile is greater than or equal to 60%. Such belt edge profiles are intended to reduce heat development in the area of ​​the belt edges.

[0004] EP 1 031 441 A2 discloses a pneumatic vehicle tire with a tread in whose grooves rubber with increased thermal conductivity is arranged, wherein this rubber occupies the space between the groove base and the radially outermost belt layer of the belt assembly. This rubber can also be arranged in the shoulder regions of the tire. Metals or metal-containing substances, such as aluminum hydroxide, aluminum oxide or silicon aluminum oxide, are added to the rubber mixture. Due to this increased thermal conductivity, the heat generated in the region of the belt assembly during operation is better dissipated into the outer regions and released there into the ambient air. The risk of thermal damage and the likelihood of belt detachment are thereby reduced.

[0005] According to EP 2 492 114 A1, it is possible to increase the thermal conductivity of rubber by incorporating metal particles in the area of ​​the belt edges and / or the belt layers. The metal particles are introduced directly into the rubber compound during the mixing process and consist of, for example, steel, copper, aluminum, brass, or zinc.

[0006] DE 10 2007 049 872 A1 discloses a method for better dissipating the heat generated at high speeds by inserting a rubberized metallic material placed near the belt edges, thereby extending tire life. Examples of suitable metallic materials include aluminum, galvanized copper, or brass.

[0007] JP 2006 076 414 A discloses the mixing of a metal powder into the rubber compound of the carcass lining. Examples of metals used include iron, nickel, aluminum, or copper.

[0008] JP 2010 116 093 A discloses a commercial vehicle tire with an inner layer with inner layer sections that also extend into the tire shoulder areas and contain platelets made of a mineral. The platelets consist of, for example, clay, mica, feldspar, silica, or kaolin and improve the airtightness of the inner layer to economically prevent damage to the carcass ply or the rubberized carcass cords caused by atmospheric oxygen.

[0009] US 2013 / 0150484 A1 discloses a pneumatic vehicle tire with one or more tire components made of a rubber material with a defined tear resistance according to ASTM D624 and certain dynamic mechanical properties. The rubber material is based on a rubber mixture containing at least one cellulose ester, at least one rubber, and at least one filler. The tire component in question is, for example, the tread, a tread layer, a carcass ply, a belt ply, a belt bandage, a belt edge pad, a shoulder pad, a bead filler, or a sidewall. The rubber mixture is said to be easy to process with large filler quantities.

[0010] State-of-the-art measures have so far failed to satisfactorily solve the problem of an undesirably strong temperature increase in certain tire areas. Such excessive heating promotes the diffusion of oxygen from the tire's interior to the outside, and the associated constant flow through the sensitive belt edge areas leads to damage to the affected rubber components, thereby reducing their durability.

[0011] The invention is therefore based on the object of designing a tire of the type mentioned at the outset in such a way that oxygen diffusion from the tire interior is largely prevented, but at the same time the heat generated in the region of the belt edges is to continue to be dissipated well, so that the service life of the tire is extended.

[0012] The stated object is achieved according to the invention in that the rubber mixture of the rubber component contains, in addition to 30 phr to 60 phr of carbon black as a further filler, 80 phr to 140 phr of kaolin and at least one styrene-butadiene rubber in amounts of up to 100 phr, wherein the rubber component is a shoulder pad which runs radially outside and along the carcass ply and, viewed in cross-section, has an inner section and an outer section which are formed by a division of the shoulder pad at the edge of the widest belt layer.

[0013] The hexagonal platelet structure of kaolin acts as a kind of molecular gas barrier in rubber components, significantly reducing oxygen diffusion from the tire's interior to the outside. Surprisingly, the added kaolin also increases the thermal conductivity of the rubber components made from this rubber compound, allowing the heat generated in the shoulder area during operation to be dissipated particularly effectively via these rubber components. Damage to the overlying rubber components caused by oxygen diffusion is thus largely prevented, significantly extending tire life.

[0014] The rubber compound of the rubber component contains kaolin in amounts of 80 phr to 140 phr, and particularly preferably in an amount of at least 100 phr. It has been shown that rubber components made from compounds containing such amounts of kaolin exhibit particularly low gas permeability and excellent thermal conductivity.

[0015] The inner section extends under the edge section of the radially innermost belt ply and extends out there. It is particularly preferred if the outer section has an extension length that is at most three times the extension length of the inner section. A shoulder pad with this local extension ensures optimal heat dissipation and particularly low oxygen diffusion in the belt edge areas, thus significantly extending the tire's service life.

[0016] Tires designed according to the invention are preferably commercial vehicle tires, since heating of the shoulder areas is particularly problematic in these tires. Tires designed according to the invention are also suitable for, for example, small trucks or similar vehicles with the same, similar, or comparable load index (light truck and van tires).

[0017] In the following description and in the tables, the quantities are given in the unit phr (parts per hundred rubber), which is common in rubber technology. The quantities refer to the mass parts of the base polymer or, in the case of polymer blends, to those of the base polymers.

[0018] Further features, advantages and details of the invention will now be explained with reference to the single figure, Fig. 1, which shows a partial cross-section through one half of a pneumatic vehicle tire in the area of ​​the belt and the tread, is explained in more detail.

[0019] The invention relates to rubber components arranged in the shoulder areas of pneumatic vehicle tires. These components are designed to largely prevent diffusion processes from the tire interior and, at the same time, effectively dissipate heat generated in the area of ​​the belt edges during operation. In the following description, the rubber component designed according to the invention is a shoulder pad.

[0020] The Fig. The tire design shown in Figure 1 corresponds to that of a commercial vehicle tire. However, the invention can also be applied to passenger car tires, as well as light truck and van tires.

[0021] In Fig.1 shows the essential components of a pneumatic vehicle tire for commercial vehicles: a tread 1, a belt assembly 2, a carcass ply 3, an airtight inner layer 4, the radially outer region of a sidewall 5, as well as a shoulder pad 6 and a belt edge pad 7. The tread 1 has a shoulder section 1a extending in the radial direction and tapering in cross-section, which is overlapped by the sidewall 5 tapering in the radial direction.

[0022] The belt assembly 2 located between the tread 1 and the carcass ply 3 has four belt plies 2a, 2b, 2c, 2d. The belt plies 2a, 2b, 2c, 2d consist of reinforcement members, particularly steel cord, that run essentially parallel to one another and are embedded in a rubber compound. The reinforcement members run at the usual acute angles to the circumferential direction of the tire, with the reinforcement members of adjacent belt plies preferably running in such a way that they cross one another.

[0023] The radially outermost belt layer 2a, also known as the protective layer in commercial vehicle tires, has the narrowest width of all layers and is the only belt layer that does not extend into the shoulder areas of the tire. The radially innermost belt layer 2d is also called the triangulation layer or barrier layer. The remaining middle belt layers 2b, 2c are referred to as the outer and inner working layers and, like the belt layer 2d, extend axially into the shoulder areas of the tire. The inner working layer 2c is the widest of all belt layers 2a, 2b, 2c, and 2d and has a width B. In deviation from the embodiment shown, three or five belt layers can also be present.

[0024] The shoulder pads 6 and the belt edge pads 7 are arranged in the shoulder regions of the pneumatic vehicle tire. The belt edge pad 7 is located radially outside the shoulder pad 6, with the shoulder pad 6 running radially outside as well as along and in contact with the carcass ply 3. The belt edge pad 7 runs from the shoulder section 1a, initially in contact with the shoulder pad 6, axially inwards between the two working plies 2b, 2c. The belt edge pad 7 is arranged in the shoulder region of the tire in such a way that, viewed in cross-section, it runs approximately halfway between the belt plies 2b and 2c. If more or fewer belt plies are present than shown, the belt edge pad 7 usually runs in such a way that it ends between the two widest belt plies.Deviating from the embodiment shown, two belt edge pads 7 can also be provided in each shoulder area, the second belt edge pad running between the innermost belt layer 2d and the belt layer 2c and in contact with the shoulder pad 6.

[0025] Each shoulder pad 6 is considered in cross-section to be divided into two sections 6a, 6b. The inner section 6a extends from the edge of the widest belt layer, in the illustrated embodiment, this is the belt layer 2c, a little way in under the edge section of the innermost belt layer 2d and out there, in the axial direction at most as far as the belt edge pad(s) 7. The outer section 6b extends axially outward at least as far as the belt edge pad 7. Its extension length along the carcass ply 3 is at most three times the extension length of section 6a.

[0026] In general, in passenger car tires, in contrast to the embodiment shown, no belt edge pads 7 and only two belt layers are provided, with the shoulder pads 6 extending radially within the first belt layer analogously as described.

[0027] The shoulder pad 6 is made of a rubber mixture which, according to the invention, contains kaolin as a filler. Table 1 lists four exemplary mixtures E1 to E4, which are constructed according to the invention, as well as a standard mixture S1, which does not contain kaolin, serving as a reference. Table 1: Mixture compositions ingredient Unit S1 E1 E2 E3 E4 Natural rubber phr 5 0 5 0 5 Styrene-butadiene rubber phr 95 100 95 100 95 kaolin phr 0 80 80 105 105 Carbon black N 660 phr 45 50 45 50 45 plasticizers phr 15 15 15 15 15 zinc oxide phr 3 3 3 3 3 accelerator phr 2 2 2 2 2 sulfur phr 2 2 2 2 2

[0028] Mixtures prepared according to the invention contain the filler kaolin in amounts of 80 phr to 140 phr, and particularly preferably in amounts of at least 100 phr. The mixtures E1, E2, E3, and E4 according to the invention listed and tested in Table 1 contained 80 phr and 105 phr of kaolin, respectively.

[0029] As a further filler, at least one carbon black, preferably of the N 660 type, but also, for example, carbon blacks of the N 339, N 375, N 326, N 234, or N 121 type, individually or in combination, is added to the mixtures according to the invention. Carbon black is added in amounts of 30 phr to 60 phr, and preferably in amounts of 40 phr to 55 phr.

[0030] Blends according to the invention further contain one or more styrene-butadiene rubbers and may also contain small amounts of natural rubber and / or synthetic polyisoprene. Natural rubber is added to the blends in an amount of up to 20 phr, preferably in an amount of up to 10 phr. The tested blends contained up to 5 phr of natural rubber.

[0031] To crosslink the rubber, elemental sulfur or sulfur donors are preferably added to the rubber mixtures, with certain sulfur donors also acting as vulcanization accelerators. The amount of sulfur added is up to 10 phr, preferably 0.5 phr to 5 phr, and particularly preferably 1 phr to 3 phr.

[0032] Accelerators are added in amounts of 0.1 phr to 10 phr, preferably in an amount of at least 1 phr, and particularly preferably in amounts of 2 phr to 7 phr. The accelerator is preferably selected from the group of sulfenamide accelerators, thiazole accelerators, thiuram accelerators, mercapto accelerators, dicarbamate accelerators, amine accelerators, dithiophosphates, or thioureas. Among the group of sulfenamide accelerators, CBS (N-cyclohexylbenzothiazole-2-sulfenamide) is particularly preferred.

[0033] The mixtures were prepared under standard conditions in several stages in a laboratory tangential mixer. Test specimens were produced from all mixtures by vulcanization, and the following material properties were tested using these test specimens: • Gas permeability according to DIN 53536, measurement at 70°C, device Zwick - Type 6201 • Thermal conductivity according to DIN 52612, DIN EN ISO 22007-1, measuring device from Kyoto Electronics

[0034] The test results are summarized in Table 2. Table 2: Test results Characteristic Unit S1 E1 E2 E3 E4 Gas permeability m 2 / (Pa*s) 29,5 * 10 -17 12,5 * 10 -17 13,5 * 10 -17 11,0 * 10 -17 12,0 * 10 -17 Thermal conductivity W / (m*K) 0,305 0,455 0,441 0,474 0,467

[0035] Table 2 shows that the vulcanizates of the tested mixtures E1, E2, E3, and E4, which are formulated according to the invention, exhibit over 50% lower gas permeability and significantly higher thermal conductivity than the vulcanizate from the standard mixture S1. The vulcanizates of mixtures E3 and E4, which contained the largest amounts of kaolin, exhibited particularly low gas permeability and the highest thermal conductivity values. List of reference numbers 1 tread 1a Shoulder section of the tread 2 belt bandage 2a radial outermost belt layer, protective layer 2b Belt layer, outer working layer 2c Belt layer, inner working layer 2d radial innermost belt layer, triangulation layer (blocking layer) 3 Carcass insert 4 inner layer 5 Side wall 6 shoulder pads 6a inner section of the shoulder pad 6b outer section of the shoulder pad 7 belt edge pads B Width of the widest belt layer

Claims

[1] Pneumatic vehicle tyre of radial design with a tread (1), a belt assembly (2) consisting of several belt layers (2a, 2b, 2c, 2d), a carcass insert (3), an inner layer (4) and a rubber component (6) in each shoulder area, wherein the rubber component (6) is made of a rubber mixture containing 30 phr to 60 phr of carbon black as filler, characterized by that the rubber mixture of the rubber component contains 80 phr to 140 phr of kaolin as a further filler and at least one styrene-butadiene rubber in amounts of up to 100 phr, wherein the rubber component (6) is a shoulder pad (6) which runs radially outside and along the carcass ply (3) and, viewed in cross-section, has an inner section (6a) and an outer section (6b), which are formed by an articulation of the shoulder pad (6) at the edge of the widest belt layer (2c). [2] Pneumatic vehicle tyre according to claim 1, characterized bythat the rubber compound of the rubber component (6) contains carbon black in amounts of 40 phr to 55 phr. [3] Pneumatic vehicle tyre according to claim 2, characterized by that the rubber mixture of the rubber component (6) contains kaolin in an amount of at least 100 phr. [4] Pneumatic vehicle tyre according to one of claims 1 to 3, characterized by that the rubber mixture of the rubber component (6) contains at least one styrene-butadiene rubber in amounts of up to 90 phr. [5] Pneumatic vehicle tyre according to claim 4, characterized by that the rubber compound of the rubber component (6) contains styrene-butadiene rubber in amounts of up to 80 phr. [6] Pneumatic vehicle tyre according to one of claims 1 to 5, characterized by that the rubber mixture of the rubber component (6) contains natural rubber and / or synthetic polyisoprene. [7] Pneumatic vehicle tyre according to one of claims 1 to 6, characterized bythat the inner section (6a) extends under the edge section of the radially innermost belt layer (2d) and ends there. [8] Pneumatic vehicle tyre according to one of claims 1 to 7, characterized by that the outer section (6b) has an extension length which is at most three times the extension length of the inner section (6a). [9] Pneumatic vehicle tyre according to one of claims 1 to 8, which is a commercial vehicle tyre with a belt assembly (2) consisting of at least three belt layers (2a, 2b, 2c, 2d), characterized by that it has one or two belt edge pads (7) which are arranged radially outside the shoulder pad (6). [10] Pneumatic vehicle tyre according to claim 9, characterized by that the or one of the belt edge pads (7) runs between the two widest belt layers (2b, 2c) and runs out there.

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