CA3122293A1

CA3122293A1 - Spike and pneumatic vehicle tyre

Info

Publication number: CA3122293A1
Application number: CA3122293A
Authority: CA
Inventors: Kristin Voiges; Hajo Weinreich
Original assignee: Continental Reifen Deutschland GmbH
Current assignee: Continental Reifen Deutschland GmbH
Priority date: 2018-12-13
Filing date: 2019-10-22
Publication date: 2020-06-18
Also published as: EP3894238B1; FI3894238T3; CN113165446A; WO2020119984A1; DE102018221587A1; EP3894238A1

Abstract

The invention relates to a spike (3) for anchoring in a spike hole (11) of a tread (2) of a pneumatic vehicle tyre (1), comprising at least one foot (6) and a spike pin (4) anchored therein, wherein the spike (3) is at least partly coated with at least one vulcanized rubber compound and/or a thermoplastic vulcanisate. For improving lateral guiding forces, traction and braking on ice, the vulcanized rubber compound and/or the thermoplastic vulcanisate has a Shore A hardness according to DIN ISO 7619-1 at room temperature of 63 to 78 Shore A .

Description

Description Spike and pneumatic vehicle tyre [0001] The invention relates to a spike for anchoring in a spike hole of a tread of a pneumatic vehicle tire, having at least a base and a spike pin anchored therein, wherein the spike is at least partially ensheathed with at least one vulcanized rubber mixture and/or with a thermoplastic vulcanizate. The invention also relates to a pneumatic vehicle tire having a tread with spikes of this kind.

[0002] In general, pneumatic vehicle tires with spikes composed of steel, aluminum or plastics are already known and in use. The spikes frequently consist of a spike pin with a free end protruding from the tread, and a base at the opposite end from this free end that has a greater area than that of the spike pin.

[0003] RU 2 148 498 Cl discloses that the spike pin, apart from the free end projecting out of the tread, is accommodated entirely within and surrounded by a polymer body. In this case, the polymer is used to reduce the weight of the spike and forms the base mentioned in the lower portion at the opposite end from the free end of the spike pin. Once produced, the entire spike is integrated into the pneumatic vehicle tire in the region of the tread.

[0004] It is also known that the spikes can be produced from a rubber material. Such a solution is apparent, for example, from JP H08300911 A or from JP 6239112, from EP 0 383 401 Al or from DE 697 17 544 T2, wherein, according to the content of disclosure of said documents, fiber materials for strengthening purposes and for improving the transmission of force are additionally embedded into the rubber. This has not been found to be successful in practice because the fiber materials do not exhibit sufficient wear resistance to be able to perform a force-transmitting function of a pin over the service life of a pneumatic vehicle tire. The pins are normally produced from cemented carbide.

[0005] Another variant of spikes is known from DE 10 2015 223 091 Al. In the case of these, the spike pin and/or the base that are generally formed from a cemented carbide and/or aluminum are at least partly integrated into a rubber sheath of a rubber material. This is intended to achieve reduced spike wear and road wear coupled with reduced component weight. The rubber sheath absorbs a certain proportion of the impact energy.

[0006] DE 10 2015 223 091 Al discloses that the Shore A
hardness of the rubber material ensheathing the spike may be equal to or different than that of the surrounding tread material, with the tread of a typical winter tire having a Shore A hardness of less than 60. Hardness values for the rubber sheath are unspecified. The rubber mixture used for the sheath of the spike may be a mixture that differs from the tread mixture. The spikes and the rubber sheath may have a wide variety of different shapes and positions.

[0007] Proceeding from this prior art, it is an object of the invention to further improve spikes for pneumatic vehicle tires of the type specified at the outset with regard to lateral side forces, traction and braking on ice.

[0008] The object is achieved in accordance with the invention in that, in the case of the spikes of the type specified at the outset, the vulcanized rubber mixture and/or the thermoplastic vulcanizate has a Shore A hardness to DIN ISO
7619-1 of 63 to 78 at room temperature.

[0009] Surprisingly, an optimum with regard to grip properties on icy terrain has been found for Shore A hardness.
It has always been assumed to date that maximum Shore A
hardness with otherwise identical vulcanizate properties is advantageous for an improvement in the spike with regard to grip properties on icy terrain and also the other desired properties, such as spike wear and road wear. It seems that a certain degree of mobility/yielding of the material surrounding the spike by virtue of a specific Shore A hardness is advantageous for the properties.

[0010] Particularly good lateral side forces on ice and greatly improved traction and improved braking on ice are achieved when the vulcanized rubber mixture and/or the thermoplastic vulcanizate of the sheath has a Shore A hardness to DIN ISO 7619-1 of 63 to 78 at room temperature.

[0011] According to the invention, the spike is at least partly ensheathed with at least one vulcanized rubber mixture and/or at least one thermoplastic vulcanizate. Thermoplastic vulcanizates are understood here to mean blends of thermoplastics and crosslinked elastomers that show elastomeric behavior in the range of customary use temperatures, but can be thermoplastically processed at higher temperatures. Thermoplastic vulcanizate (TPVs) are also referred to as elastomer alloys.

[0012] It is preferable when the thermoplastic(s) of the thermoplastic vulcanizate is/are selected from the group consisting of polyurethane, polypropylene, polystyrene, polyamide and acrylonitrile-butadiene-styrene copolymer. These thermoplastics impart an advantageous hardness to the thermoplastic vulcanizate.

[0013] The elastomer of the thermoplastic vulcanizate is preferably based on a rubber mixture comprising, as rubber(s), at least one of the rubbers selected from the group consisting of natural rubber (NR), synthetic polyisoprene (IR), polybutadiene (BR), styrene-butadiene rubber (SBR) and nitrile-butadiene rubber (NBR). These are rubbers that also find use in rubber mixtures of treads, which assists good bonding of the spike body to the rubber material of the tread.

[0014] In a preferred development of the invention, the spike is at least partly ensheathed with a vulcanized rubber mixture.
In this way, the spike body can be matched in an excellent manner to the surrounding material of the tread of the pneumatic vehicle tire.

[0015] The vulcanized rubber mixture preferably comprises at least a diene rubber, a filler, a plasticizer and crosslinking reagents. With these ingredients, the ensheathing material can be adjusted to the hardness of the invention.

[0016] Diene rubbers are rubbers which are formed by polymerization or copolymerization of dienes and/or cycloalkenes and thus have C=C double bonds either in the main chain or in the side groups.

[0017] The diene rubber is preferably selected from the group consisting of natural polyisoprene (NR), synthetic polyisoprene (IR), butadiene rubber (BR), solution-polymerized styrene-butadiene rubber (SSBR) and emulsion-polymerized styrene-butadiene rubber (ESBR).

[0018] The rubber mixture more preferably contains 40 to 80 phr of natural polyisoprene (NR) and/or synthetic polyisoprene (IR) and 20 to 60 phr of butadiene rubber (BR).

[0019] The unit "phr" (parts per hundred parts of rubber by weight) used in this document is the standard unit of quantity for mixture recipes in the rubber industry. The dosage of the parts by weight of the individual substances is always based here on 100 parts by weight of the total mass of all rubbers present in the mixture. The mass of all rubbers present in the mixture adds up to 100.

[0020] The rubber mixture may comprise different fillers, such as carbon blacks, silicas, aluminosilicates, chalk, starch, fibers, carbon nanotubes, graphite, graphenes, magnesium oxide, titanium dioxide or rubber gels, in customary amounts of up to 250 phr, where the fillers may be used in combination.

[0021] If carbon black is used in the rubber mixture, the types used are preferably those having a CTAB surface area (to ASTM D 3765) of more than 30 m2/g. These can be mixed in in a simple manner and ensure low buildup of heat.

[0022] If silicas are present in the mixture, they may be the silicas that are customary for tire rubber mixtures. It is particularly preferable when a finely divided, precipitated silica is used, having a CTAB surface area (to ASTM D 3765) of 30 to 350 m2/g, preferably of 110 to 250 m2/g. Silicas used may be either conventional silicas, such as those of the VN3 type (trade name) from Evonik, or highly dispersible silicas known as HD silicas (e.g. Ultrasil 7000 from Evonik).

[0023] If the rubber mixture contains silica or other polar fillers, silane coupling agents may be added to the mixture for improvement of processability and for binding of the polar filler to the rubber. The silane coupling agents react with the surface silanol groups of the silica or other polar groups during the mixing of the rubber/the rubber mixture (in situ) or in the context of a pretreatment (premodification) even before addition of the filler to the rubber. Silane coupling agents that may be used here include any silane coupling agents known to those skilled in the art for use in rubber mixtures.
Such coupling agents known from the prior art are bifunctional organosilanes having at least one alkoxy, cycloalkoxy or phenoxy group as a leaving group on the silicon atom and having, as another functionality, a group that, after cleavage if necessary, can enter into a chemical reaction with the double bonds of the polymer. The latter group may for example be the following chemical groups: -SCN, -SH, -NH2 or -Sx- (with x = 2-8). Silane coupling agents that may be used include, for example, 3-mercaptopropyltriethoxysilane, 3-thiocyanatopropyltrimethoxysilane or 3,3'-bis(triethoxysilylpropyl) polysulfides having 2 to 8 sulfur atoms, for example 3,3'-bis(triethoxysilylpropyl) tetrasulfide (TESPT), the corresponding disulfide, or else mixtures of the sulfides having 1 to 8 sulfur atoms with different contents of the various sulfides. The silane coupling agents may also be added here as a mixture with industrial carbon black, for example TESPT to carbon black (trade name: X505 from Evonik).
Blocked mercaptosilanes as known for example from WO 99/09036 may also be used as a silane coupling agent. It is also possible to use silanes as described in WO 2008/083241 Al, WO
2008/083242 Al, WO 2008/083243 Al and WO 2008/083244 Al. It is possible to use, for example, silanes which are sold under the NXT name in a number of variants by Momentive, USA, or those that are sold under the VP Si 363 name by Evonik Industries.
Also usable are "silated core polysulfides" (SCPs, polysulfides with a silylated core), which are described, for example, in US 20080161477 Al and EP 2 114 961 Bl.

[0024] The plasticizers include plasticizer oils or plasticizer resins. Processing auxiliaries, which are understood to mean oils and other viscosity-lowering substances. These processing auxiliaries may, for example, be plasticizer oils or plasticizer resins.

[0025] Plasticizer oils are, for example, aromatic, naphthenic or paraffinic mineral oil plasticizers, for example MES (mild extraction solvate) or TDAE (treated distillate aromatic extract), natural oils, for example rapeseed oil, or rubber-to-liquid oils (RTL) or biomass-to-liquid oils (BTL) or liquid polymers (such as liquid BR), the average molecular weight of which (determined by GPC = gel permeation chromatography, using a method based on BS ISO 11344:2004) is in the range from 500 to 20 000 g/mol. The plasticizer resins include, for example, hydrocarbon resins.

[0026] The crosslinking agents present in the rubber mixture include all substances known to those skilled in the art.
Preference is given to sulfur and/or sulfur donors, which are added to the rubber mixture in the last mixing step in the amounts commonly used by the person skilled in the art (0.4 to 8 phr).

[0027] The rubber mixture may additionally comprise vulcanization-influencing substances such as vulcanization accelerators, vulcanization retardants and vulcanization activators in customary amounts. These are added in order to control the time required and/or the temperature required for vulcanization and to improve the vulcanizate properties. The vulcanization accelerator may, for example, be selected from the following groups of accelerators: thiazole accelerators, for example 2-mercaptobenzothiazole, sulfenamide accelerators, for example benzothiazy1-2-cyclohexylsulfenamide (CBS) and benzothiazy1-2-dicyclohexylsulfenamide (DCBS), guanidine accelerators, for example N,N'-diphenylguanidine (DPG), dithiocarbamate accelerators, for example zinc dibenzyldithiocarbamate, disulfides, thiophosphates. The accelerators can also be used in combination with one another, which can give rise to synergistic effects.

[0028] It is also possible to use further network-forming systems, for example Vulkuren , Duralink or Perkalink , or systems as described in WO 2010/049261 A2 in the rubberizing mixture.

[0029] As well as the substances already mentioned, the rubber mixture for the ensheathing of the spikes may comprise customary additives in customary proportions by weight. These additives include aging stabilizers, for example N-phenyl-N'-(1,3-dimethylbuty1)-p-phenylenediamine (6PPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), 2,2,4-trimethy1-1,2-dihydroquinoline (TMQ) and other substances as known, for example, from J. Schnetger, Lexikon der Kautschuktechnik [Lexicon of Rubber Technology], 2nd edition, Hilthig Buch Verlag, Heidelberg, 1991, p. 42-48, activators, for example zinc oxide and fatty acids (e.g. stearic acid), waxes, tackifying resins, for example hydrocarbon resins and rosin, bonding systems, for example those based on resorcinol and formaldehyde, and masticating aids, for example 2,2'-dibenzamidodiphenyl disulfide (DBD).

[0030] In an advantageous development of the invention, the Shore A hardness of the vulcanized rubber mixture for the ensheathing of the spikes is adjusted via the level of filling with filler and/or the degree of crosslinking and/or the plasticizer content. With the aid of these measures, it is possible to adjust the Shore A hardness in a simple manner without needing to alter other mixing admixtures. Particular preference is given to adjusting the Shore A hardness via the plasticizer content, since other vulcanization and vulcanizate properties are then affected to a very minor degree.

[0031] In a further advantageous development of the invention, the vulcanized rubber mixture for the ensheathing of the spikes corresponds to the mixture of the surrounding tread in terms of the diene rubbers present. In this way, incompatibility between the rubber mixtures is avoided.

[0032] It has additionally been found to be advantageous when the vulcanized rubber mixture has reduced rolling resistance, i.e. contributes to reduced rolling resistance in driving operation. This gives a low energy loss.

[0033] The rubber mixture may preferably have reduced rolling resistance in that it comprises silica as filler.

[0034] The rolling resistance of the silica-containing rubber mixture can be reduced further when it comprises at least one silane coupling agent. This serves to bind the filler to the rubber.

[0035] Spikes for pneumatic vehicle tires may be different in terms of their shape. For instance, DE 10 20015 223 091 Al discloses some possible shapes of spikes, spike pins and spike bases.

[0036] According to the invention, the spike is at least partly ensheathed with at least one vulcanized rubber mixture and/or at least one thermoplastic vulcanizate. It is accordingly possible to use multiple different rubber mixtures and/or thermoplastic vulcanizates in different places on a spike.

[0037] The spike may firstly be fully ensheathed by the vulcanized rubber mixture and/or the thermoplastic vulcanizate. In this way, it is possible to produce a spike in a simple manner, for example, by insert molding with an unvulcanized rubber mixture, followed by vulcanization. The insert molding can be effected from various positions, for example from the base or from the spike pin.

[0038] Secondly, it is also possible that only the spike pin and/or the base is/are at least partly ensheathed by the vulcanized rubber mixture and/or the thermoplastic vulcanizate. It is advantageous when that part that is the main part responsible for the anchoring of the spike in the rubber material of the tread, namely the base flange, has a sheath made of the vulcanized rubber mixture and/or the thermoplastic vulcanizate.

[0039] This sheath with the vulcanized rubber mixture and/or the thermoplastic vulcanizate may have various external forms, such that these, at least in sections, have a circular cylindrical, conical, irregular, polygon or conical and/or fitted outer shape. Undercuts or fitted portions improve the adhesion of the spike in the tread of the pneumatic vehicle tire.

[0040] The spikes of the invention are produced by methods known to those skilled in the art. For example, a spike made of a cemented carbide and/or aluminum can be clamped in a device for holding the spike and then subjected to at least partial insert molding with an unvulcanized rubber mixture and/or a thermoplastic vulcanizate. It is optionally possible to apply an adhesion promoter to the regions of the spike that are ensheathed. This is followed by vulcanization. A spike thus produced is typically introduced and/or bonded into the outer surface of a ready-vulcanized pneumatic vehicle tire with the aid of spiking robots. Adhesives used are, for example, reactive adhesives or hotmelt adhesive for rubber-rubber or rubber-metal adhesion.

[0041] The invention further relates to a pneumatic vehicle tire having a tread with spikes executed in accordance with the invention.

[0042] Further features, advantages and details of the invention will now be described in detail with reference to the drawing, which illustrates a working example, and the table below. Fig. 1 shows a detailed side-on cross-sectional view of a spiked pneumatic vehicle tire in contact with a surface beneath.

[0043] Figure 1 shows a detailed side-on cross-sectional view of a spiked pneumatic vehicle tire 1 rolling on a surface 12 beneath and having a multitude of individual spikes 3 along its circumference. Each of the spikes 3 has been inserted into the profiled tread 2 of the pneumatic vehicle tire 1, with only a free end 5 of a spike pin 4 of the spike 3 protruding out of the tread 2 of the pneumatic vehicle tire 1. The spike pin 4 in the present case consists of a cemented carbide, which may be tungsten carbide for example, which is possible here without any problem because the spike 3 as a whole is surrounded by a rubber sheath 7 pressed into a corresponding recess 11 of the tread 2. On that side of the spike 3 opposite the free end 5 of the spike pin 4, said spike has a base 6 with a surface area 8, the projected area or cross-sectional area of which is greater than that of the spike pin 4. The base 6 of the spike 3, viewed in axial direction, merges into a pedestal 9 which serves firstly as adhesion surface for the rubber sheath 7 and secondly for connection to the spike pin 4. The spike pin 4 is inserted or pressed into the pedestal 9, or is bonded to the pedestal 9 by means of a cohesive bond.

[0044] Table 1 specifies example rubber mixtures for the ensheathing 7 of spikes 3. Comparative mixtures are labeled V;
mixtures for inventive spikes 3 are labeled E. The mixtures are altered in terms of their Shore A hardness by varying the plasticizer content.

[0045] The mixtures were produced under standard conditions with production of a base mixture and subsequently of the finished mixture in a tangential laboratory mixer.

[0046] All mixtures were used to produce test specimens by optimal vulcanization under pressure at 160 C, and these test specimens were used to determine the material properties typical for the rubber industry by the test methods specified hereinafter.
0 Shore A hardness at room temperature to DIN ISO 7619-1 0 Resilience at room temperature to DIN ISO 4662

[0047] In addition, the mixtures from table 1 were used for insert molding of spikes 3 according to figure 1 in the region of the spike pin 4 and at the pedestal 9 to the base 6, namely at the base of the flange, with the rubber mixtures, which were vulcanized and bonded into a 205/55 R 16 pneumatic vehicle tire 1 with the aid of a spike robot, followed by autoclaving.

[0048] These tires were used to conduct objective braking and traction tests, and tests of the lateral side force on ice according to the following test descriptions:

[0049] Braking: ABS braking tests and evaluation of average delay in a defined speed range.

[0050] Traction: Acceleration with traction control system (ASR) and evaluation of average acceleration within a defined speed range.

[0051] Lateral guiding: Rapid steering from a straight line at a constant defined speed, measurement of transverse acceleration in a constant time interval after commencement of steering.

[0052] The behavior of mixture 1(V) was set at 100%. Values greater than one hundred mean an improvement in the corresponding property.

Table 1 Constituents Unit 1(V) 2(E) 3(V) Polyisoprene phr 60 60 60 Polybutadiene phr 40 40 40 N121 carbon black phr 8 8 8 Silicaa) phr 103 103 103 Plasticizer phr 6 25 58 Vulcanization activators phr 10 10 10 and aging stabilizers Processing auxiliaries phr 2 2 2 (calcium soaps and fatty acid amides) Silane coupling agentb) phr - - -Accelerator phr 4.1 4.1 4.1 Sulfur phr 1.8 1.8 1.8 Properties Shore A hardness at RT Shore A 83 73 56 Resilience at RT % 37 36 35 Tire properties Traction and braking on % 100 106 102 ice Lateral side forces on ice % 100 103 100 a) Ultrasil VN3 from Evonik b) Blocked mercaptosilane, NXT silane from Momentive

[0053] It is apparent from table 1 that the tires with spikes ensheathed with a mixture having a Shore A hardness of 73 are notable for a distinct improvement in traction and braking characteristics on ice and also for improved lateral side forces on ice. Given equal damping (equal resilience), tires having spikes ensheathed with a harder (1(V)) or softer mixture (3(V)) do not show any such improvement in properties. It has also been found that the tires with the spikes of the invention have a distinct improvement in noise characteristics and improved driving performance on ice.

List of reference numerals 1 Pneumatic vehicle tire 2 Tread 3 Spike 4 Spike pin Free end (tip) 6 Base 7 Rubber sheath 8 Surface of the base 9 Pedestal 11Recess (in the tread), spike hole 12 Surface beneath tire

Claims

1. A spike (3) for anchoring in a spike hole (11) of a tread (2) of a pneumatic vehicle tire (1), having at least a base (6) and a spike pin (4) anchored therein, the spike (3) being at least partly ensheathed with at least one vulcanized rubber mixture and/or at least one thermoplastic vulcanizate, characterized in that the vulcanized rubber mixture and/or the thermoplastic vulcanizate has a Shore A hardness to DIN ISO
7619-1 at room temperature of 63 to 78.

2. The spike (3) as claimed in claim 1, characterized in that the vulcanized rubber mixture and/or the thermoplastic vulcanizate has a Shore-A hardness to DIN ISO 7619-1 of 67 to 77 at room temperature.

3. The spike (3) as claimed in claim 1 or 2, characterized in that the spike (3) is at least partly ensheathed with a vulcanized rubber mixture.

4. The spike (3) as claimed in claim 3, characterized in that the vulcanized rubber mixture comprises at least a diene rubber, a filler, a plasticizer and crosslinking agents.

5. The spike (3) as claimed in claim 4, characterized in that the Shore A hardness of the vulcanized rubber mixture is adjusted by the fill level with filler and/or the degree of crosslinking and/or the plasticizer content.

6. The spike (3) as claimed in claim 4 or 5, characterized in that the vulcanized rubber mixture corresponds to the mixture of the surrounding tread in terms of the diene rubbers present.

7. The spike (3) as claimed in at least one of claims 3 to 6, characterized in that the vulcanized rubber mixture has reduced rolling resistance.

8. The spike (3) as claimed in at least one of claims 3 to 7, characterized in that the vulcanized rubber mixture comprises silica as filler.

9. The spike (3) as claimed in claim 8, characterized in that the vulcanized rubber mixture comprises at least one silane coupling agent.

10. The spike (3) as claimed in at least one of the preceding claims, characterized in that the spike (3) is fully ensheathed by the vulcanized rubber mixture and/or the thermoplastic vulcanizate.

11. The spike (3) as claimed in at least one of the preceding claims 1 to 9, characterized in that at least the spike pin (4) is at least partly ensheathed by the vulcanized rubber mixture and/or the thermoplastic vulcanizate.

12. The spike as claimed in at least one of the preceding claims 1 to 9, characterized in that at least the base (6) is at least partly ensheathed by the vulcanized rubber mixture and/or the thermoplastic vulcanizate.

13. A pneumatic vehicle tire (1) with a tread (2) with spikes (3) executed according to at least one of the preceding claims.