EP4073127A1

EP4073127A1 - Sulfur-cross-linkable rubber blend and pneumatic vehicle tire

Info

Publication number: EP4073127A1
Application number: EP20800586.8A
Authority: EP
Inventors: Christoph Eichhorst; Marion Puppa; Catarina Sà; Dieter Jeromin; Viktoria Pavon Sierra; Pedro-Nuno Rodrigues; Jakob Hey
Original assignee: Continental Reifen Deutschland GmbH
Current assignee: Continental Reifen Deutschland GmbH
Priority date: 2019-12-09
Filing date: 2020-10-27
Publication date: 2022-10-19
Also published as: BR112022009659A2; US20220411613A1; DE102019219145A1; WO2021115677A1; CN114787201A

Abstract

The invention relates to a sulfur-cross-linkable rubber blend and to a pneumatic vehicle tire that comprises at least one rubber component consisting of the sulfur-vulcanized rubber blend. The rubber blend contains: 10 to 60 phr (parts by weight, relative to 100 parts by weight of the total of rubbers in the blend) of at least one functionalized polybutadiene A, the functionalized polybutadiene being functionalized by an amino-group- and/or ammonium-group-containing organosilyl group at one chain end, and the functionalized polybutadiene A being functionalized with an amino group at the other chain end; up to 90 phr of at least one further diene rubber; and 30 to 350 phr of at least one filler.

Description

description

Sulfur-crosslinkable rubber mixture and pneumatic vehicle tires

The invention relates to a sulfur-crosslinkable rubber mixture and a pneumatic vehicle tire which has at least one rubber component made from the rubber mixture vulcanized with sulfur.

Since the driving properties of a tire, in particular a pneumatic vehicle tire, depend to a large extent on the rubber composition of the tread, particularly high requirements are placed on the composition of the tread compound. Various attempts have been made to positively influence the properties of the tire by varying the polymer components, fillers and other additives in the tread compound. It must be taken into account here that an improvement in one tire property often leads to a deterioration in another property; an improvement in rolling resistance is usually associated with a deterioration in braking behavior. Other components of the tire also have an influence on the tire's rolling resistance.

To influence tire properties such as abrasion, wet slip behavior and rolling resistance, it is z. B. known to use solution-polymerized styrene-butadiene copolymers with different microstructure. In addition, styrene-butadiene copolymers can be modified by z. B. the styrene and vinyl proportions can be varied, end group modifications, couplings or hydrogenations are made. The different types of copolymer have different effects on the vulcanizate and thus also on the tire properties. EP 3 150403 A1 describes silica-containing rubber mixtures for tires with low rolling resistance which contain solution-polymerized styrene-butadiene copolymers which have alkoxysilyl groups containing amino groups on at least one chain end and a further group selected from the group consisting of alkoxysilyl groups and alkoxysilyl groups containing amino groups are functionalized. The reduction in rolling resistance is probably due to an increased filler-polymer interaction.

Also in EP 3 150402 A1, EP 3 150401 A1, DE 102015 218 745 A1 and DE 102015 218 746 A1, solution-polymerized styrene-butadiene copolymers are described, which at at least one chain end with amino groups-containing alkoxysilyl groups and a further group selected from the group consisting of alkoxysilyl groups and amino groups-containing alkoxysilyl groups are functionalized. They are used in combination with various other additives in the rubber compounds.

EP 2703 416 A1 discloses modified solution-polymerized styrene-butadiene copolymers, their production and their use in tires. The styrene-butadiene copolymers have nitrogen-containing groups (amino group-containing organosilyl groups) which were protected with protective groups during the preparation of the polymers. The rubber mixtures with such styrene-butadiene copolymers should be characterized by a balanced ratio of processability, wet grip and low hysteresis.

EP 2 853 558 A1 describes styrene-butadiene rubbers functionalized with phthalocyanine groups and / or hydroxyl groups and / or epoxy groups and / or silane sulfide groups, the styrene content of the styrene-butadiene Rubber can be 0 wt .-%. A styrene content of 0% by weight is a polybutadiene. The rubber compounds show improvements in rolling resistance and abrasion. The invention is based on the object of providing rubber mixtures which have a further improved damping behavior and thus lead to improved rolling resistance when used as a rubber mixture for pneumatic vehicle tires. At the same time, other properties of the rubber mixture should not be influenced negatively or only slightly.

This task is solved by a rubber mixture that

10-60 phr (parts by weight, based on 100 parts by weight of the total rubbers in the mixture) of at least one functionalized polybutadiene A, the functionalized polybutadiene A being functionalized at one chain end with an organosilyl group containing amino groups and / or ammonium groups, and where the functionalized Polybutadiene A is functionalized with an amino group at the other end of the chain,

- up to 90 phr of at least one further diene rubber and 30-350 phr of at least one filler.

The phrase phr (parts per hundred parts of rubber by weight) used in this document is the quantity specification for mixture recipes customary in the rubber industry. The dosage of the parts by weight of the individual substances is always based on 100 parts by weight of the total mass of all rubbers present in the mixture.

Surprisingly, it has been found that the use of a specially functionalized polybutadiene in a filler-containing rubber mixture can further improve the damping behavior of the mixture, as can be seen, for example, from the rebound resilience at 70 ° C and the tan d at 55 ° C. When using such a mixture in pneumatic vehicle tires, this leads to an improvement in the rolling resistance. When used as a tread compound, this rubber compound can also decouple the conflicting goals between rolling resistance and braking behavior (wet and dry braking). Due to the two different functional groups on polybutadiene A, interactions of the polymer with any polar fillers present in the mixture, such as silica, and with non-polar fillers possibly present in the mixture appear to be able to take place.

The functionalized polybutadiene A can be all types known to the person skilled in the art and having a molecular weight M _w of 250,000 to 500,000 g / mol. These include the so-called high-cis and low-cis types, with polybutadienes (BR) with a cis content greater than or equal to 90% by weight being the high-cis type and polybutadiene with a cis content less than 90 % By weight is referred to as low-cis type. A low-cis polybutadiene is z. B. Li-BR (lithium-catalyzed butadiene rubber) with a cis content of 20 to 50% by weight. The functionalized polybutadiene A is preferably a polybutadiene produced with a lithium catalyst. Particularly good results with regard to the improvement in rolling resistance are achieved if the functionalized polybutadiene has a cis content of 25 to 35% by weight, a trans content of 35 to 45% by weight and a vinyl content of 25 to 35% by weight .-% having. The functionalized polybutadiene preferably has a molecular weight M _w of 250,000 to 500,000 g / mol. The functionalized polybutadiene preferably has a glass transition temperature of -100 ° C. to -60 ° C. in order to contribute to good winter properties when used in tires.

The vinyl content of the polymers discussed in the context of the present invention is determined by means of ¹³ C-NMR (solvent deuterochloroform CDCh; NMR: "nuclear magnetic resonance") and comparison with data from infrared spectrometry (IR; FT-IR spectrometer from Nicolet, KBr window 25 mm diameter x 5 mm, 80 mg sample in 5 mL 1,2-dichlorobenzene). The glass transition temperature (T _g ) is determined using dynamic differential calorimetry (DSC according to DIN 53765: 1994-03 or ISO 11357-2: 1999-03, calibrated DSC with low-temperature device, calibration according to device type and manufacturer's instructions, sample in aluminum crucible with aluminum lid, cooling to temperatures lower than -120 ° C at 10 ° C / min).

The functionalized polybutadiene A is functionalized at one chain end with an organosilyl group containing amino groups and / or ammonium groups. Such functionalizations can be obtained by allowing the polymer to react with an amino group-containing alkoxysilyl compound with protective groups on the amino group. For example, N, N-

Bis (trimethylsily) aminopropylmethyldiethoxysilane can be used. After deprotection, the functionalized polybutadiene A.

The functionalized polybutadiene A is functionalized with an amino group at the other end of the chain. These can be primary, secondary or tertiary amino groups, which can also be present in the form of a ring. The functionalization can be achieved by adding lithium amides during the polymerization or the amides in situ by adding n-butyllithium and amines, e.g. B. cyclic amines such as piperidine or piperazines, are generated in the polymerization.

The amino group at the other end of the chain is preferably a ring-shaped diamine group. For this purpose, for example, N- (t-butyldimethylsilyl) piperazine in combination with n-butyllithium can be added during the polymerization.

The rubber mixture according to the invention contains 10 to 60 phr of at least one functionalized polybutadiene A. Several polymers of this type can also be used in a blend.

The rubber mixture according to the invention furthermore contains up to 90 phr of at least one further diene rubber. Diene rubbers are rubbers that 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. The other diene rubbers can be, for. B. around natural polyisoprene and / or synthetic polyisoprene and / or other polybutadienes (butadiene rubber) than the functionalized polybutadiene A and / or styrene-butadiene copolymer (styrene-butadiene rubber) and / or epoxidized polyisoprene and / or styrene Isoprene rubber and / or halobutyl rubber and / or polynorbornene and / or isoprene-isobutylene copolymer and / or ethylene-propylene-diene rubber act. The rubbers can be used as pure rubbers or in oil-extended form.

However, the further diene rubber is preferably selected from the group consisting of natural polyisoprene, synthetic polyisoprene, styrene-butadiene copolymers and further polybutadienes. These diene rubbers can be easily processed into the rubber mixture and give good tire properties in the vulcanized tires.

The natural and / or synthetic polyisoprene can be either cis-1,4-polyisoprene or 3,4-polyisoprene. However, the use of cis-1,4-polyisoprenes with a cis 1.4 proportion of> 90% by weight is preferred. On the one hand, such a polyisoprene can be obtained by stereospecific polymerization in solution with Ziegler-Natta catalysts or using finely divided lithium alkyls. On the other hand, natural rubber (NR) is such a cis-1,4 polyisoprene; the cis-1,4 share in natural rubber is greater than 99% by weight.

Furthermore, a mixture of one or more natural polyisoprenes with one or more synthetic polyisoprenes is also conceivable. Natural polyisoprene is understood as rubber that can be obtained by harvesting sources such as rubber trees (Hevea brasiliensis) or non-rubber tree springs (such as guayule or dandelion (e.g. Taraxacum koksaghyz)). Natural polyisoprene (NR) is not understood to mean synthetic polyisoprene.

The further polybutadiene can be all types known _{to the person skilled in the art and having an M w} of 250,000 to 500,000 g / mol. These include the so-called high-cis and low-cis types, with polybutadiene with a cis content greater than or equal to 90% by weight being the high-cis type and polybutadiene with a cis content less than 90% by weight. % is referred to as the low-cis type. A low-cis polybutadiene is e.g. B. Li-BR (lithium-catalyzed butadiene rubber) with a cis content of 20 to 50% by weight. With a high-cis BR, particularly good abrasion properties and a low hysteresis of the rubber mixture are achieved. The other polybutadiene used can be end group modified with other modifications and functionalizations and / or functionalized along the polymer chains than the functionalized polybutadiene A. The modification can be, for. B. are those with hydroxyl groups and / or ethoxy groups and / or epoxy groups and / or siloxane groups and / or carboxy groups and / or silane sulfide groups. Metal atoms can also be part of functionalizations.

The styrene-butadiene rubber (styrene-butadiene copolymer) can be either solution-polymerized styrene-butadiene rubber (SSBR) or emulsion-polymerized styrene-butadiene rubber (ESBR), with a mixture of at least one SSBR and at least one ESBR can be used. The terms “styrene-butadiene rubber” and “styrene-butadiene copolymer” are used synonymously in the context of the present invention. In any case, styrene-butadiene copolymers with an M _w of 250,000 to 600,000 g / mol (two hundred and fifty thousand to six hundred thousand grams per mol) are preferred. The styrene-butadiene copolymer (s) used can also be end-group modified with modifications and functionalizations and / or functionalized along the polymer chains.

The rubber mixture contains 30 to 350 phr of at least one filler. These can be fillers such as carbon blacks, silicas, aluminosilicates, chalk, starch,

Magnesium oxide, titanium dioxide or rubber gels act, it being possible for the fillers to be used in combination. Carbon nanotubes (CNT) including discrete CNTs, so-called hollow carbon tibers (HCF) and modified CNT containing one or more functional groups, such as hydroxyl, carboxy and carbonyl groups) are also conceivable. Graphite and graphene as well as so-called “carbon-silica dual-phase filier” can also be used as fillers. If the rubber mixture contains carbon black, all types of carbon black known to the person skilled in the art can be used. However, preference is given to using a carbon black which has an iodine adsorption number according to ASTM D 1510 of 30 to 180 g / kg, preferably 30 to 130 g / kg, and a DBP number according to ASTM D 2414 of 80 to 200 ml / 100 g, preferably 100 to 200 ml / 100g, particularly preferably 100 to 180 ml / 100g. This achieves particularly good rolling resistance indicators (rebound resilience at 70 ° C.) with good other tire properties for use in vehicle tires. The polybutadiene A can interact with the carbon black with its amino group functionalization.

To reduce the rolling resistance, it has proven to be advantageous if the rubber mixture contains silica as filler. The polybutadiene A can interact with the silica via its organosilyl groups containing amino groups and / or ammonium groups.

A wide variety of silicas, such as “low surface area” or highly dispersible silicic acid, also in a mixture, can be used. It is particularly preferred if a finely divided, precipitated silica is used which has a CTAB surface (according to ASTM D 3765) of 30 to 350 m ² / g, preferably 110 to 250 m ² / g. Both conventional silicas such as those of the type VN3 (trade name) from Evonik and highly dispersible silicas, so-called HD silicas (e.g. Ultrasil 7000 from Evonik), can be used as silicas.

The rubber mixture preferably contains 50 to 150 phr silica in order to achieve good processability with good tire properties.

To improve the processability and to bind the silica to the diene rubber in silica-containing mixtures, at least one silane coupling agent is preferably used in amounts of 1-15 phf (parts by weight, based on 100 parts by weight of silica) in the rubber mixture. The specification phf (parts per hundred parts of filier by weight) used in this document is the quantity specification customary in the rubber industry for coupling agents for fillers. In the context of the present application, phf relates to the silica present, which means that other fillers that may be present, such as carbon black, are not included in the calculation of the amount of silane coupling agent.

The silane coupling agents react with the superficial silanol groups of the silica or other polar groups during the mixing of the rubber or the rubber mixture (in situ) or even before the filler is added to the rubber in the sense of a pretreatment (pre-modification). All silane coupling agents known to the person skilled in the art for use in rubber mixtures can be used as silane coupling agents. Such coupling agents known from the prior art are bifunctional organosilanes which have at least one alkoxy, cycloalkoxy or phenoxy group as a leaving group on the silicon atom and which have a group as the other functionality which, optionally after cleavage, can enter into a chemical reaction with the double bonds of the polymer . In the latter group it can be, for. B. be the following chemical groups: -SCN, -SH, -NH2 or -S _x - (with x = 2-8). Thus, as silane coupling agents z. B. 3-mercaptopropyltriethoxysilane, 3-thiocyanato-propyltrimethoxysilane or 3,3'-bis (triethoxysilylpropyl) polysulfides with 2 to 8 sulfur atoms, such as. B. 3,3'-bis (triethoxysilylpropyl) tetrasulfide (TESPT), the corresponding disulfide or mixtures of the sulfides with 1 to 8 sulfur atoms with different contents of the various sulfides can be used. TESPT can also be added, for example, as a mixture with carbon black (trade name X50S from Degussa). Blocked mercaptosilanes, such as those used, for. B. from WO 99/09036, can be used as a silane coupling agent. Silanes, as described in WO 2008/083241 A1, WO 2008/083242 A1, WO 2008/083243 A1 and WO 2008/083244 A1, can also be used. Can be used e.g. B. Silanes, which are available under the name NXT® in different variants from the company Momentive, USA, or those available under the name VP Si 363 distributed by Evonik Industries. So-called “silated core poly sulfides” (SCP, polysulfides with a silylated core) can also be used. B. in US 20080161477 A1 and EP 2 114961 B1 are described.

The rubber mixture can also contain plasticizers in amounts from 1 to 300 phr, preferably from 5 to 150 phr, particularly preferably from 15 to 90 phr. All plasticizers known to the person skilled in the art, such as aromatic, naphthenic or paraffinic mineral oil plasticizers, such as MES (mild extraction solvate) or RAE (residual aromatic extract) or TD AE (treated distillate aromatic extract), or rubber-to-liquid oils ( RTL) or biomass-to-liquid oils (BTL) preferably with a polycyclic aromatic content of less than 3% by weight according to method IP 346 or rapeseed oil or factiss or liquid polymers such as liquid polybutadiene - also in modified form - be used. The plasticizer or plasticizers are preferably added in at least one basic mixing stage during the production of the rubber mixture according to the invention.

Furthermore, the rubber mixture can contain customary additives in customary parts by weight, which are preferably added in at least one basic mixing stage during their production. These additives include a) anti-aging agents such. B. N-phenyl-N '- (1,3-dimethylbutyl) -p-phenylenediamine (6PPD), N, N'-diphenyl-p-phenylenediamine (DPPD), N, N'-ditolyl-p-phenylenediamine (DTPD ), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), b) activators, such as. B. zinc oxide and fatty acids (z. B. stearic acid) or zinc complexes such as. B. zinc ethyl hexanoate, c) waxes, d) mastication aids, such as. B. 2,2'-dibenzamidodiphenyl disulfide (DBD), e) processing aids, such as fatty acid salts, such as zinc soaps, and fatty acid esters and their derivatives, and f) resins, such as aliphatic or aromatic hydrocarbon resins. The proportion of the total amount of further additives is 3 to 150 phr, preferably 3 to 100 phr and particularly preferably 5 to 80 phr.

If the rubber mixture is used for inner tire components, the so-called body mixtures, the rubber mixture can also contain substances that improve and / or support adhesion, such as adhesive systems made from methylene donor and methylene acceptor.

The vulcanization of the rubber mixture is carried out in the presence of sulfur and / or sulfur donors with the aid of vulcanization accelerators, some vulcanization accelerators also being able to act as sulfur donors. The accelerator is selected from the group consisting of thiazole accelerators and / or mercapto accelerators and / or sulfenamide accelerators and / or thiocarbamate accelerators and / or thiuram accelerators and / or thiophosphate accelerators and / or thiourea accelerators and / or xanthidine accelerators and / or guanidine accelerators.

The use of a sulfenamide accelerator selected from the group consisting of N-cyclohexyl-2-benzothiazolesufenamid (CBS) and / or N, N-dicyclohexylbenzothiazole-2-sulfenamide (DCBS) and / or benzothiazyl-2-sulfenmorpholide (MBS) is preferred ) and / or N-tert-butyl-2-benzothiazylsulfenamide (TBBS).

In addition, the rubber mixture can contain vulcanization retarders.

All sulfur-donating substances known to the person skilled in the art can be used as the sulfur-donating substance. If the rubber mixture contains a sulfur-donating substance, this is preferably selected from the group consisting of, for. B. thiuram disulfides, such as. B. tetrabenzylthiuram disulfide (TBzTD), tetramethylthiuram disulfide (TMTD) or tetraethylthiuram disulfide (TETD), thiuram tetrasulfides, such as. B. Dipentamethylene thiuram tetrasulfide (DPTT), dithiophosphates, such as. B. DipDis (bis (diisopropyl) thiophosphoryl disulfide), bis (0,0-2-ethylhexyl-thiophosphoryl) polysulfide (e.g. Rhenocure SDT 50 ^® , Rheinchemie GmbH, Zinc dichloro dithiophosphate (e.g. Rhenocure ZDT / S ^® , Rheinchemie GmbH) or zinc alkyl dithiophosphate, and 1,6-bis (N, N-dibenzylthiocarbamoyldithio) hexane and diaryl polysulphides and dialkyl polysulphides.

Even more network-forming systems as they are for example available under the trade names Vulkuren ^®, Duralink ^® or Perkalink ^®, or network-forming systems, such as are described in WO 2010/049216 A2 may be used in the rubber mixture. The latter system contains a vulcanizing agent which crosslinks with a functionality greater than four and at least one vulcanization accelerator.

The rubber mixture is preferably at least one vulcanizing agent selected from the group consisting of sulfur,

Sulfur donors, vulcanization accelerators and vulcanizing agents, which crosslink with a functionality greater than four, are added in the final mixing stage. As a result, a sulfur-crosslinked rubber mixture for use in pneumatic vehicle tires can be produced from the mixed ready-mixed mixture by vulcanization.

The terms “vulcanized” and “crosslinked” are used synonymously in the context of the present invention.

The rubber mixture is produced according to the process customary in the rubber industry, in which a basic mixture with all components except the vulcanization system (sulfur and vulcanization-influencing substances) is first produced in one or more mixing stages. The finished mixture is produced by adding the vulcanization system in a final mixing stage. The finished mixture is z. B. processed by an extrusion process and brought into the appropriate shape. Further processing then takes place by vulcanization, with sulfur crosslinking taking place due to the vulcanization system added in the context of the present invention. The rubber mixture is used for the production of pneumatic vehicle tires such as car, van, truck or two-wheeled tires.

In a pneumatic vehicle tire, the rubber mixture can be used for a wide variety of components. According to the invention, the pneumatic vehicle tire has at least one rubber component made from the rubber mixture according to the invention vulcanized (crosslinked) with sulfur. In the case of the tires, several components can accordingly also be formed from the rubber mixture according to the invention.

In the case of a pneumatic vehicle tire, the tread can consist of a single mixture which then contains a functionalized polybutadiene A, possibly a further diene rubber and a filler. Today, however, pneumatic vehicle tires often have a tread with a so-called cap / base construction. The term “cap” is understood to mean that part of the tread which comes into contact with the roadway and which is arranged radially on the outside (tread upper part or tread cap). The term “base” is understood to mean that part of the tread that is arranged radially on the inside and therefore does not come into contact with the road surface during ferry operation or only at the end of the tire's life (tread lower part or luster base).

According to a preferred embodiment of the invention, the rubber component from the mixture according to the invention is the part of the tread (cap) that comes into contact with the roadway. Here, the reduced damping behavior of the mixture has a particularly positive effect on rolling resistance, while good braking behavior is achieved with regard to wet and dry braking at the same time.

To reduce the rolling resistance of a pneumatic vehicle tire, however, the mixture according to the invention can also be used for so-called body components of the pneumatic vehicle tire. These body components include, for example, the rubber linings of the bead core, the bead covers, the bead reinforcement, the belt, the carcass or the belt bandages, but also others close to the strength support Mixtures such as apex, squeegee, belt edge pads, shoulder pads and tread pads.

In the manufacture of the pneumatic vehicle tire, the mixture is brought into the desired shape as a finished mixture prior to vulcanization and applied or introduced in the known manner during the manufacture of the vehicle tire blank. The component blanks can also be wound onto a green tire in the form of narrow strips.

The pneumatic vehicle tire is then vulcanized under normal conditions.

The invention will now be explained in more detail using comparative and exemplary embodiments which are summarized in Tables 1 and 2.

A functionalized polybutadiene A was synthesized according to the following description of the experiment:

2500 g of cyclohexane, 5 g of tetrahydrofuran, 490 g of 1,3-butadiene and 4.2 mmol of N- (t-butyldimethylsilyl) piperazine were placed in a 5 L autoclave under a nitrogen atmosphere. The temperature of the reaction mixture was adjusted to 30 ° C. and then a cyclohexane solution containing 2 mmol of n-butyllithium was added to start the polymerization reaction. The polymerization was carried out under adiabatic conditions. A maximum temperature of 90 ° C was reached. When a degree of conversion of 99% was reached, 5 g of 1,3-butadiene were added over 2 minutes and the monomers were polymerized for a further 5 minutes. A solution of 4.46 mmol of N, N-bis (trimethylsilyl) aminopropylmethyldimethoxysilane in cyclohexane was then added to the remainder of the reaction mixture and allowed to react for 15 min. 3 g of 2,6-di-tert-butyl-p-cresol were added to the resulting polymer solution with a diene-based polymer. The solvent was then removed with the aid of steam distillation, the pH being adjusted to 10 with the aid of sodium hydroxide. The remaining functionalized polybutadiene A was dried with heating rollers at a temperature of 110.degree. This functionalized polybutadiene A obtained in this way was used for the mixtures according to the invention in the tables below.

In Tables 1 and 2, comparative mixtures are marked with V, the mixtures according to the invention are marked with E.

The mixture was produced according to the usual procedures in the rubber industry under normal conditions in three stages in a laboratory mixer in which all components except the vulcanization system (sulfur and vulcanization-influencing substances) were initially mixed in the first mixing stage (basic mixing stage). In the second mixing stage, the basic mixture was mixed again. The finished mixture was produced by adding the vulcanization system in the third stage (final mixing stage), with mixing at 90 to 120 ° C.

Mixtures for different body components of the tire are listed in Table 1. Mixtures 1 and 2 are suitable, for example, for the sidewall, the wings, the rimstrip or the apex, the mixtures 3 and 4 for the rubber coating of the belt, the bandage, the carcass or the bead reinforcement as well as for the squeegee.

Test specimens were produced from the mixtures in Table 1 by vulcanization under pressure at 160 ° C. for 10 minutes ((1) V) and 2 (E)) or 15 minutes ((3) V) and 4 (E)) With these test specimens, typical material properties for the rubber industry were determined using the test methods specified below:

Shore A hardness at room temperature using a durometer in accordance with DIN ISO 7619-1 - rebound resilience at 70 ° C in accordance with DIN 53 512 as an indicator for rolling resistance (higher value correlates with better rolling resistance in tires) maximum (max) loss factor tan d from dynamic - mechanical measurement at 55 ° C in accordance with DIN 53 513, strain sweep (lower value correlates with better rolling resistance in tires) Furthermore, tests for adhesion to brass-coated steel cord (2 x 0.30 HT) according to ASTM 2229 / D1871 without aging were carried out with some mixtures from Table 2 (embedment length in the rubber coating mixture: 10 mm, extraction speed: 125 mm / min). The test specimens were heated at 150 ° C. for 30 minutes. The pull-out force and the coverage were determined.

The measured values determined for the aforementioned properties were based on mixtures 1 (V) and 3 (V) as reference mixtures. Their values were set equal to 100%. Values less than 100% reflect a decrease in the measured value compared to the reference value. Values greater than 100% reflect an increase in the measured value compared to the reference value.

Table 1 a high cis polybutadiene, co-polybutadiene, cis content: 96.1% by weight, trans content: 3.4% by weight, vinyl content. 0.5% by weight, not functionalized, M _w = 497000 g / mol, Tg = 105 ° C b functionalized polybutadiene A according to the description of the experiment, cis content: 30% by weight, trans content: 40% by weight , Vinyl content. 30% by weight, amine functionalization: piperazine group, M _w = 361000 g / mol, Tg = -75 ° C It can be seen from the data in Table 1 that an increase in the rebound resilience of the vulcanizates at 70.degree. C. or a decrease in the loss factor tan d at 55.degree. C. is achieved only through the presence of the specially functionalized polybutadiene. This correlates with a reduction in the rolling resistance of the tire with a component from the mixture. At the same time, the other properties remain at the desired high level.

Mixtures for the tread or the tread cap of pneumatic vehicle tires are listed in Table 2. The mixtures were used for the tread cap of tires of dimension 205/55 RI 6 and tire tests were carried out according to the following test methods:

• Rolling resistance: according to ISO 28580

• Wet braking: ABS braking from 80 km / h, wet asphalt, low m

• Dry braking: ABS braking from 100 km / h, dry asphalt, high m (high m)

The values determined were converted into performance, the comparison mixtures 5 (V) and 7 (V) being standardized to 100% performance for each property tested. The mixing capacities of 6 (E) and 8 (E) refer to these comparison mixtures. Values <100% here mean a deterioration in the property, while values> 100% represent an improvement.

Table 2 b functionalized polybutadiene A according to the description of the experiment, cis content: 30% by weight, trans content: 40% by weight, vinyl content. 30% by weight, amine functionalization: piperazine group, M _w = 361000 g / mol, Tg = -75 ° C. c functionalized polybutadiene B according to EP 2 853 558 A1, cis content: 39% by weight, trans content: 51 Wt%, vinyl content. 8% by weight, functionalized with (MeO) 2 (Me) Si- (CH2) 2- S-SiMe ₂ C (Me) ₃ and (MeO) ₃ Si- (CH ₂ ) 2-S-SiMe2C (Me) ₃ , M _w = 501000 g / mol,

Tg = - 94 ° C d Sprintan ^® SLR3402, Trinseo, Germany, functionalized solution polymerized styrene-butadiene copolymer Table 2 shows that the specially functionalized polybutadiene A with the organosilyl group containing amino groups and / or ammonium groups at one end of the chain and the amino group at the other end of the chain leads to a significant improvement in rolling resistance. With this special functionalization, rolling resistance values are obtained that are higher than those functionalized with another

Polybutadiene can be achieved with groups without nitrogen. At the same time, the wet braking behavior and the dry braking behavior can also be improved, which was not to be expected, since an improvement in the rolling resistance is usually associated with a deterioration in the braking behavior.

Claims

1. Sulfur-crosslinkable rubber mixture containing

2. Rubber mixture according to claim 1, characterized in that the functionalized polybutadiene A is a polybutadiene produced with a lithium catalyst.

3. Rubber mixture according to claim 1 or 2, characterized in that the functionalized polybutadiene A has a cis content of 25 to 35 wt .-%, a trans content of 35 to 45 wt .-% and a vinyl content of 25 to 35% by weight.

4. Rubber mixture according to claim 1 or 2, characterized in that the functionalized polybutadiene A has a molecular weight M _w of 300,000 to 400,000 g / mol.

5. Rubber mixture according to at least one of the preceding claims, characterized in that the functionalized polybutadiene A has a glass transition temperature of -100 to -60 ° C.

6. Rubber mixture according to at least one of the preceding claims, characterized in that the amino group at the other end of the chain is a ring-shaped diamine group.

7. Rubber mixture according to at least one of the preceding claims, characterized in that the further diene rubber is selected from the group consisting of natural polyisoprene, synthetic polyisoprene, styrene-butadiene copolymers and other polybutadienes.

8. Rubber mixture according to at least one of the preceding claims, characterized in that it contains silica as filler.

9. Rubber mixture according to claim 8, characterized in that it is 40 to

Contains 150 phr silica.

10. Pneumatic vehicle tire which has at least one rubber component made from a rubber mixture vulcanized with sulfur according to one of claims 1 to 9.

11. Pneumatic vehicle tire according to claim 10, characterized in that the rubber component is a part of the tread that comes into contact with the roadway.

12. Pneumatic vehicle tire according to claim 9 or 10, characterized in that the

Rubber component is a body component.