Rubber mixture containing ethoxylated alcohol

Abstract

The present invention relates to a rubber blend suitable for producing a vulcanized product which, in addition to a predetermined amount of synthetic rubber, filler, and crosslinking agent, contains 0.5 to 10 phr of at least one ethoxylated compound of formula (I): RO(CH2CH2O) x H [wherein R represents an alkyl (which may be branched or unbranched), and x represents an integer between 1 and 20], and has low rolling resistance.

Description

Technical Field

[0001] The present invention relates to novel rubber mixtures comprising at least one ethoxylated compound of formula (I), processes for their production, their use for producing rubber vulcanizates, the corresponding vulcanizates, and the use of at least one ethoxylated compound of formula (I) in rubber mixtures, vulcanizates obtainable therefrom, and molded articles, preferably tires, for reducing the rolling resistance of rubber mixtures, vulcanizates, and molded articles obtainable therefrom.

Background Art

[0002] The EU is obliged to reduce its greenhouse gas emissions and achieve climate neutrality by 2050. Reducing CO2 emissions from road traffic plays a major role in achieving those goals.

[0003] The new EU tire labeling system (effective May 1, 2021) is based on three important tire characteristics, namely rolling resistance (and thus fuel efficiency), grip when wet, and external rolling noise. This new EU tire label will enable consumers to actively select tires with higher fuel efficiency.

[0004] Tires with higher fuel efficiency contribute to reducing CO2 emissions in road traffic. Depending on the rolling resistance of the tire, the fuel efficiency is classified into classes A (highest fuel efficiency) to E. Fuel consumption is important from both economic and environmental viewpoints. A low fuel consumption has a positive effect on the CO2 balance in vehicles, especially commercial heavy vehicles.

[0005] In order to counter this background situation, tire manufacturers are exploring low-cost methods for achieving class A fuel efficiency targets in tires.

[0006] It is known to use silica-containing rubber mixtures for manufacturing passenger car tire treads. The silica contributes to a good combination of performance including rolling resistance, grip when wet, and abrasion resistance, which are required in passenger car tire treads. To achieve the desired combination of performance, the silica must be effectively dispersed in the rubber mixture and optimally bonded to the rubber matrix during vulcanization.

[0007] For the purpose of improving the processability of silica-containing rubber mixtures, it is possible to employ additional additives such as fatty acid esters, fatty acid salts, or mineral oils. The above-mentioned additives have the following drawbacks, namely, although they improve fluidity, they simultaneously reduce the stress at high elongation (e.g., 100% - 300%) or reduce the hardness of the vulcanizate, which has an adverse effect on the reinforcing effect of the filler. However, if the hardness or rigidity of the vulcanizate is insufficient, the driving characteristics of the tire, especially during cornering, will be insufficient.

[0008] The loss factor tanδ gives an important index for evaluating rolling resistance. The lower the loss factor tanδ, the lower the rolling resistance. The loss factor tanδ should be as low as possible at 60°C - 70°C (less than 0.2 in (Patent Document 1) and less than 0.12 in (Patent Document 2)).

[0009] In the disclosure of (Patent Document 2), in a rubber mixture containing 1 phr of 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane (CAS No: 151900 - 44 - 6) and 1 phr of a certain sulfur-containing additive, a vulcanizate having good dynamic properties, good hardness / rigidity, good rolling resistance, and low abrasion resistance can be obtained. The drawback is that the scorch time (t5) during vulcanization of this rubber mixture is significantly shortened, which is a major drawback in terms of processing reliability. From the perspective of the rubber processing industry, it is a greater advantage to use only a few types of mixture components.

[0010] In (Patent Document 3), the rolling resistance is reduced by adding a certain organosilicon polysulfide. According to the results in Table 2 of (Patent Document 3), it is shown that with 1 phr of organosilicon polysulfide, the loss factor (tanδ at 60 °C) can be extremely reduced by 10%. The mechanical properties such as tensile strength, elongation at break, and 300% modulus are not substantially changed. Also in this case, the drawback is that the scorch time becomes extremely short by adding the organosilicon polysulfide.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0012] Therefore, an object of the present invention is to provide an improved rubber mixture based on a hydroxyl-containing oxide filler, which overcomes the above-mentioned drawbacks, and the vulcanizates and molded articles produced therefrom have, for example, low rolling resistance as measured by the loss factor tanδ at 60 °C, and at the same time give a tire tread that does not substantially change properties such as the 300% modulus and hardness. The improved rubber mixture should preferably further have a shorter full vulcanization time (t95). The improved rubber compound should further preferably have a low rolling resistance (measured by the loss factor tanδ at 60 °C) while the 300% modulus and hardness remain unchanged.

Means for Solving the Problems

[0013] The low loss factor tanδ at 60 °C measured according to DIN 53513 (dynamic attenuation) is preferably less than 0.2, particularly preferably less than 0.12.

[0014] The scorch time t5 measured at 130 °C in accordance with ASTM D5289-95 is preferably in the range of 1000 to 1500 seconds, particularly preferably in the range of 1300 to 1500 seconds.

[0015] The short cure time t95 (95% conversion time) measured at a temperature of 170 °C in accordance with ASTM D5289-95 is preferably in the range of 500 to 1000 seconds.

[0016] A high 300 modulus value in the vulcanizate, particularly in the tire tread, is also advantageous. The 300 modulus (measured according to DIN 53504) is preferably 10 to 25 MPa.

[0017] The hardness measured according to DIN53505 should be in the range of 60 to 75 Shore A.

[0018] The unit "phr" hereinafter represents parts by weight based on 100 parts by weight of the total amount of rubber present in the rubber mixture, i.e., the total amount of synthetic rubber and natural rubber present.

[0019] Surprisingly, the above object is achieved by the rubber mixture according to the invention comprising: - 50 to 100 phr of at least one synthetic rubber, preferably BR rubber and / or SBR rubber, - 0 to 50 phr of at least one natural rubber, - 0.1 to 200 phr of at least one hydroxyl-containing oxide filler, - 0 to 120 phr, preferably 0.1 to 100 phr of at least one carbon black, - 0.1 to 20 phr of at least one crosslinking agent, preferably selected from the group of sulfur donors and / or sulfur, and - 0.5 to 10 phr of at least one ethoxylated compound of formula (I) RO(CH2CH2O) x H (I) [wherein, R represents an alkyl (the alkyl may be branched or unbranched), x represents an integer from 1 to 20].

[0020] The vulcanizate according to the present invention obtained by vulcanizing the rubber mixture according to the present invention surprisingly has a low loss factor tanδ at 60°C and even a short complete vulcanization time (t95), while maintaining equivalent good performance characteristics such as 300% modulus, hardness, and vulcanization characteristics.

Mode for Carrying Out the Invention

[0021] Rubber The rubber mixture according to the present invention preferably contains at least one synthetic rubber selected from the group consisting of polar and non-polar synthetic rubbers.

[0022] Preferred polar and non-polar synthetic rubbers include the following; BR: polybutadiene ABR: butadiene / C1-C4-alkyl acrylate copolymer CR: polychloroprene IR: polyisoprene SBR: styrene / butadiene copolymer (styrene content is 1 to 60% by weight, preferably 20 to 50%) IIR: isobutylene / isoprene copolymer NBR: butadiene / acrylonitrile copolymer (acrylonitrile content is 5 to 60% by weight, preferably 10 to 50%) HNBR: partially hydrogenated or fully hydrogenated NBR rubber EPDM: ethylene / propylene / diene copolymer SIBR: styrene-isoprene-butadiene rubber ENR: Epoxidized natural rubber SNBR: Acrylonitrile-styrene / butadiene rubber HNBR: Hydrogenated acrylonitrile / butadiene rubber XNBR: Carboxylated acrylonitrile / butadiene rubber HXNBR: Hydrogenated carboxylated acrylonitrile / butadiene rubber.

[0023] It is preferable that at least one of the synthetic rubbers is selected from the group consisting of SBR and BR rubbers.

[0024] The rubber mixture in the present invention preferably contains at least one SBR rubber and / or BR rubber, particularly preferably SBR rubber and BR rubber.

[0025] The SBR rubber may be a functionalized SBR rubber.

[0026] The functionalized SBR rubber should be understood to mean an SBR rubber in which the main chain and / or end groups are substituted by one or more functional groups, particularly carboxyl groups and / or mercaptan-containing groups.

[0027] In one preferred embodiment, the rubber mixture in the present invention contains at least one functionalized SBR rubber and optionally may contain one or more BR rubbers.

[0028] The rubber mixture in the present invention contains 50 to 100 phr, preferably 70 to 100 phr of at least one synthetic rubber.

[0029] The rubber mixture in the present invention preferably contains at least one SBR and at least one BR rubber in a weight ratio of (SBR):(BR) of preferably (100:0) to (0:100), particularly preferably (90:10) to (10:90), extremely particularly preferably (90:10) to (50:50), and extremely extremely particularly preferably (80:20) to (60:40).

[0030] In yet another advantageous embodiment, the rubber mixture according to the invention further comprises at least one natural rubber. The rubber mixture of the invention may contain from 0 to 50 phr, preferably from 0 to 30 phr of natural rubber.

[0031] Ethoxylated compound of formula (I) The rubber mixture according to the invention contains at least one ethoxylated compound of formula (I): RO(CH2CH2O) x H (I) [wherein, R represents an alkyl (which alkyl may be branched or unbranched), x represents an integer from 1 to 20].

[0032] R is preferably C1-C 20 -alkyl, particularly preferably C5-C 17 -alkyl, very particularly preferably C 10 ~C 15 -alkyl, extremely very particularly preferably iso-C 13 -alkyl, most preferably iso-C 13 H 27 represents.

[0033] x preferably represents an integer in the range from 2 to 15, particularly preferably in the range from 3 to 10, very particularly preferably in the range from 4 to 6, and most preferably 5.

[0034] At least one ethoxylated compound of formula (I) is present, for example, in LUTENSOL® TO5 from BASF.

[0035] The rubber mixture according to the invention generally contains at least one ethoxylated compound of formula (I) in an amount of from 0.5 to 10.0 phr, preferably from 1.0 to 8.0 phr, particularly preferably from 2.0 to 7.0 phr, and very particularly preferably from 4.0 to 6.0 phr.

[0036] Filler Preferably, at least one of the hydroxyl-containing oxide fillers is selected from the group consisting of silica, synthetic silicates, and natural silicates.

[0037] The content of the hydroxyl-containing oxide filler in the rubber mixture according to the present invention is 0.1 to 200 phr, preferably 20 to 160 phr, particularly preferably 25 to 140 phr, and most preferably 30 to 120 phr.

[0038] Suitable hydroxyl-containing oxide fillers are preferably selected from the following group: - Silica, especially having a specific surface area (BET method) of 5 to 1000, preferably 20 to 400 m 2 / g and preferably having a primary particle size of 100 to 400 nm (wherein the silica may in some cases be present as a mixed oxide with oxides of other metals such as Al, Mg, Ca, Ba, Zr, Ti). - Synthetic silicates such as aluminum silicate, alkaline earth metal silicates such as magnesium silicate or calcium silicate, having a specific surface area (BET method) of 20 to 400 m 2 / g and preferably having a primary particle size of 10 to 400 nm, and - Natural silicates such as kaolin and other natural silicas, and mixtures thereof.

[0039] The BET method surface area described above is measured in accordance with DIN ISO 9277. The indicated primary particle size is based on measurements using an apparatus for particle analysis using scattered light. The calculation of the particle size is based on Mie theory, which represents the interaction between light and matter (DIN / ISO 13320).

[0040] Preferably, the silica can be obtained by a precipitation method from a silicate solution or by a flame hydrolysis method of silicon halide.

[0041] The rubber mixture according to the invention preferably has a specific surface area (BET method) in the range of 5 to 1000, preferably 20 to 400 m 2 / g and contains at least one hydroxyl-containing oxide filler from the group of silicas in an amount in the range of 0.1 to 200 phr, preferably 20 to 160 phr, particularly preferably 25 to 140 phr, and very particularly preferably 30 to 120 phr.

[0042] The rubber mixture according to the invention may contain at least one carbon black as a filler.

[0043] In one preferred embodiment, the rubber mixture according to the invention contains at least one carbon black as a filler.

[0044] Preferably, the rubber mixture of the invention contains at least one carbon black in an amount of 0.1 to 120 phr, preferably 0.1 to 100 phr, particularly preferably 1 to 70 phr, and very particularly preferably 2 to 40 phr.

[0045] Preferably, it can be obtained by the lamp black, furnace black or gas black process and is a carbon black having a specific surface area (BET method) in the range of 20 to 200 m 2 / g, for example, SAF, ISAF, IISAF, HAF, FEF, or GPF carbon black. Preferably, the rubber mixture of the invention contains at least one carbon black having a specific surface area (BET method) in the range of 20 to 200 m 2 / g.

[0046] Preferably, the rubber mixture according to the invention contains as fillers at least one of the above-mentioned silicas and at least one of the above-mentioned carbon blacks.

[0047] It is highly particularly preferred that the rubber mixture according to the invention contains, as fillers, at least one of the above-described silicas in an amount of 25 to 140 phr, preferably 30 to 120 phr, and at least one of the above-described carbon blacks in an amount of 1.0 to 70 phr, preferably 2.0 to 40 phr.

[0048] The total amount of the carbon black and silica-based fillers in the rubber mixture according to the invention is preferably 26 to 210 phr, particularly preferably 32 to 160 phr.

[0049] Crosslinking agents and vulcanization accelerators The rubber mixture according to the invention may contain one or more crosslinking agents.

[0050] It is preferred that the rubber mixture according to the invention contains at least one crosslinking agent from the group of sulfur and sulfur donors.

[0051] Sulfur may be used in elemental form, in soluble or insoluble form.

[0052] It is particularly preferred that the rubber mixture according to the invention contains at least one sulfur donor and / or sulfur, and it is highly particularly preferred if it contains sulfur.

[0053] Examples of suitable sulfur donors include the following: dimorpholyldisulfide (DTDM), 2-morpholinodithiobenzothiazole (MBSS), caprolactam disulfide, dipentamethylenethiuram tetrasulfide (DPTT), tetramethylthiuram disulfide (TMTD), and tetrabenzylthiuram disulfide (TBzTB).

[0054] The rubber mixture according to the invention generally contains at least one crosslinking agent from the group of sulfur and sulfur donors in an amount of 0.1 to 20 phr, preferably 0.5 to 10 phr, particularly preferably 1.0 to 8 phr.

[0055] In a particularly preferred embodiment, the rubber mixture according to the invention contains sulfur in at least one of its crosslinking agents in an amount of from 0.1 to less than 1.8 phr, very particularly preferably from 1.0 to 1.7 phr, extremely very particularly preferably from 1.3 to 1.7 phr.

[0056] In another particularly preferred embodiment, the rubber mixture according to the invention contains sulfur in at least one of its crosslinking agents in an amount of from 1.8 to 20 phr, very particularly preferably from 1.9 to 8.0 phr, extremely very particularly preferably from 1.9 to 5 phr, most preferably from 1.9 to 3 phr.

[0057] This last-mentioned embodiment achieves a further object of providing an improved rubber mixture having a particularly low rolling resistance, measured by the loss factor tanδ at 60 °C, without changing the 300% modulus and hardness.

[0058] In the two above-mentioned embodiments, the term "phr of sulfur in at least one crosslinking agent" means that the phr of sulfur as described above refers to the amount of sulfur in at least one of its crosslinking agents and thus the sulfur employed in the form of a sulfur donor.

[0059] The rubber mixture according to the invention may further contain zinc oxide. This is a complexing agent for sulfur and sulfur donors and thus simplifies the binding of sulfur to the rubber matrix.

[0060] The preferred rubber mixture according to the invention contains zinc oxide having a BET surface area of from 2 to 100 m 2 / g, preferably from 2 to 70 m 2 / g. The BET surface area of the zinc oxide can be measured in accordance with ISO 9277.

[0061] Zinc oxide is generally present in the rubber mixture according to the invention in an amount of from 0 to 20 phr, preferably from 0.1 to 10 phr, particularly preferably from 1 to 5 phr.

[0062] The rubber mixture according to the present invention may contain one or more vulcanization accelerators.

[0063] The rubber mixture according to the present invention preferably contains at least one vulcanization accelerator, particularly preferably those from the following group: mercaptobenzothiazole, thiocarbamate, dithiocarbamate, thiuram, thiazole, sulfenamide, thiazole sulfenamide, xanthate, bi- or polycyclic amines, thiophosphate, dithiophosphate, caprolactam, thiourea derivatives, guanidine, cyclic disulfane, and amines, particularly zinc diaminediisocyanate, hexamethylenetetramine, 1,3-bis(citraconimidomethyl)benzene, and very particularly preferably those from the group of sulfenamides, very particularly preferably N-cyclohexylbenzothiazole sulfenamide (CAS No.: 95-33-0).

[0064] The rubber mixture of the present invention generally contains 0.1 to 20 phr, preferably 0.5 to 10 phr, more preferably 1.0 to 5 phr of at least one of the above-mentioned vulcanization accelerators.

[0065] It is preferred that the rubber mixture of the present invention contains at least one crosslinking agent and at least one vulcanization accelerator.

[0066] It is particularly preferred that the rubber mixture of the present invention contains the following: at least one crosslinking agent from the group of sulfur and sulfur donors, and at least one vulcanization accelerator from the following group: mercaptobenzothiazole, thiazole sulfenamide, thiuram, dithiocarbamate, xanthate, and thiophosphate, particularly preferably those from the group of sulfenamides, very particularly preferably N-cyclohexylbenzothiazole sulfenamide (CAS No.: 95-33-0).

[0067] The rubber mixture of the present invention particularly preferably contains at least one crosslinking agent selected from the group consisting of sulfur and sulfur donors, and at least one vulcanization accelerator selected from the group consisting of the following: mercaptobenzothiazole, thiazole sulfenamide, thiuram, dithiocarbamate, xanthate, and thiophosphate, particularly preferably those from the group of sulfenamides, and extremely particularly preferably N-cyclohexylbenzothiazole-2-sulfenamide (CAS No.: 95-33-0), and zinc oxide.

[0068] The total amount of the crosslinking agent and the vulcanization accelerator in the rubber mixture is preferably 1.0 to 20 phr, particularly preferably 2.0 to 13 phr.

[0069] Reinforcing additive The rubber mixture in the present invention may contain one or more reinforcing additives.

[0070] The rubber mixture in the present invention preferably contains at least one reinforcing additive from the group of sulfur-containing organic silanes, particularly a sulfur-containing silane having an alkoxysilyl group, and extremely particularly preferably a sulfur-containing organic silane having a trialkoxysilyl group.

[0071] The rubber mixture in the present invention particularly preferably contains one or more sulfur-containing silanes from the group of bis(triethoxysilylpropyl)tetrasulfane, bis(triethoxysilylpropyl)disulfane, and 3-(triethoxysilyl)-1-propanethiol.

[0072] In order to improve metering properties and / or dispersibility, the liquid sulfur-containing silane may be absorbed onto a carrier (dry liquid). The content of the sulfur-containing silane in those "dry liquids" is preferably between 30 and 70 parts by weight, particularly preferably between 40 and 60 parts by weight, per 100 parts by weight of the dry liquid.

[0073] The rubber mixture of the present invention generally contains at least one reinforcing additive in an amount of 0.1 to 20 phr, preferably 0.5 to 15 phr, more preferably 1.0 to 10 phr.

[0074] Rubber auxiliaries The rubber mixture according to the present invention may further contain one or more rubber auxiliaries. Examples of suitable rubber auxiliaries include the following: anti-aging stabilizers, binders, heat stabilizers, light stabilizers, flame retardants, processing aids, impact resistance improvers, plasticizers, tackifiers, foaming agents, dyes, pigments, waxes, extenders, organic acids such as stearic acid, retarders especially triethanolamine, polyethylene glycol, hexanetriol, reversion inhibitors for vulcanization, and secondary accelerators.

[0075] Those rubber auxiliaries may be added to the rubber mixture according to the present invention in amounts customary for those auxiliaries and also defined by the end use of the vulcanizates produced therefrom. Customary amounts are, for example, 0.1 to 30 phr.

[0076] The rubber mixture according to the present invention may contain one or more anti-aging agents. Suitable anti-aging agents include the following; amine-based anti-aging agents, for example, diaryl-p-phenylenediamine (DTPD), octylated diphenylamine (ODPA), phenyl-α-naphthylamine (PAN), phenyl-β-naphthylamine (PBN), preferably those based on phenylenediamine, for example, N,N'-dicyclohexyl-p-phenylenediamine (CCPD), N-isopropyl-N'-phenyl-p-phenylenediamine, N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD), N-1,4-dimethylpentyl-N'-phenyl-p-phenylenediamine (7PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), and phosphites such as tris(nonylphenyl) phosphite, polymerized 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), methyl-2-mercaptobenzimidazole (MMBI), and zinc methylmercaptobenzimidazole (ZMMBI), and mixtures thereof. It is particularly preferred that at least one of the anti-aging agents is selected from the group consisting of N,N'-dicyclohexyl-p-phenylenediamine (CCPD) and N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD).

[0077] The processing aid should be active among the rubber particles and should be able to resist the frictional forces during mixing, plasticization, and molding. Processing aids that can be present in the rubber mixture according to the present invention include all lubricants commonly used in plastic processing, for example, the following: hydrocarbons such as oil, paraffin, and PE wax, aliphatic alcohols having 6 to 20 carbon atoms, ketones, carboxylic acids such as fatty acids and montanic acids, oxidized PE wax, metal salts of carboxylic acids, carboxamides, and carboxylic acid esters from, for example, ethanol of alcohol, aliphatic alcohols, glycerol, ethanediol, pentaerythritol, and long-chain carboxylic acids as the acid component.

[0078] For the purpose of suppressing flammability and smoke generation during combustion, the rubber mixture of the present invention may contain a flame retardant. Examples of compounds used for this purpose include the following: antimony trioxide, phosphate esters, chlorinated paraffins, aluminum hydroxide, boron compounds, zinc compounds (excluding ZnO), molybdenum trioxide, ferrocene, calcium carbonate, or magnesium carbonate.

[0079] Before crosslinking, an additional thermoplastic resin may be added to the rubber mixture of the present invention, and they function, for example, as polymeric processing aids or impact resistance improvers. Those thermoplastic resins are preferably selected from the group consisting of: ethylene, propylene, butadiene, styrene, vinyl acetate, vinyl chloride, glycidyl acrylate, glycidyl methacrylate, homopolymers and copolymers based on acrylates and methacrylates having an alcohol component of a branched or unbranched C1 - C10 alcohol, particularly preferably polyacrylates having the same or different alcohol groups from the group of C4 - C8 alcohols, particularly butanol, hexanol, octanol and 2 - ethylhexanol, polymethyl methacrylate, methyl methacrylate - butyl acrylate copolymer, methyl methacrylate - butyl methacrylate copolymer, ethylene - vinyl acetate copolymer, chlorinated polyethylene, ethylene - propylene copolymer, ethylene - propylene - diene copolymer.

[0080] Known adhesives are the so - called RFS direct bonding system based on resorcinol, formaldehyde, and silica. These direct bonding systems can be employed in various desired amounts for the rubber mixture in the present invention at any point in time during the incorporation into the rubber mixture of the present invention.

[0081] In silica-based rubber mixtures, such as those suitably employed for tire manufacturing and the like, typically, diphenylguanidine (DPG) or structurally similar aromatic guanidines are employed as secondary accelerators.

[0082] As is known to those skilled in the art, there may be cases where it is advantageous to replace DPG with 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane, which is also known under the trade name Vulcuren®. It is also possible to replace DPG with secondary accelerators such as TBzTD (tetrabenzylthiuram disulfide) or dithiophosphates.

[0083] The rubber mixtures according to the invention generally contain 0 phr, or 0.1 to 10 phr, preferably 0.5 to 5 phr, particularly preferably 0.2 to 3.5 phr of at least one of the above-mentioned secondary accelerators.

[0084] Particularly preferred are the rubber mixtures according to the invention which contain: - 50 to 100 phr of at least one synthetic rubber, in particular BR rubber and / or SBR rubber, - 20 to 160 phr of at least one silica, in particular having a specific surface area (BET method) in the range of 5 to 1000 m 2 / g, preferably 20 to 400 m 2 / g and having a primary particle size of 100 to 400 nm, - 0.1 to 100 phr of at least one carbon black, in particular having a specific surface area (BET method) in the range of 20 to 200 m 2 / g, - 0.5 to 10 phr of at least one crosslinking agent, in particular from the group of sulfur donors and / or sulfur, - 0.1 to 10 phr of zinc oxide, - 0.5 to 10 phr of at least one vulcanization accelerator, in particular from the group of sulfenamides, - 0.1 to 10.0 phr of at least one secondary accelerator, - 0.5 to 15 phr of at least one reinforcing additive, in particular from the group of sulfur-containing silanes, - 0.1 to 30 phr of rubber auxiliaries, and - 0.5 to 10.0 phr of at least one ethoxylated compound of formula (I).

[0085] The above-mentioned further preferred ranges for the individual components also apply to these preferred mixtures.

[0086] Process for producing a rubber mixture The present invention further provides a process for producing the rubber mixture according to the present invention, which is characterized by mixing their respective components in a mixing process. This preferably includes at least one synthetic rubber, optionally at least one natural rubber, and at least one ethoxylated compound of formula (I), optionally in the presence of at least one filler as described above, optionally at least one crosslinking agent, optionally at least one vulcanization accelerator, optionally zinc oxide, optionally at least one secondary accelerator, optionally at least one reinforcing additive, and optionally one or more rubber auxiliaries, in the general and preferred amounts described above for these additives, at a temperature in the range of 30°C to 170°C, particularly preferably 140°C to 160°C, and mixing them with each other.

[0087] The rubber mixture of the present invention is produced in a known mixing device, for example, a roller, an internal mixer, a downstream mixing roller mill, and a mixing extruder, at a shear rate of 1 to 1000 sec -1 of.

[0088] The production of the rubber mixture according to the invention is preferably carried out in a two-stage mixing process. In the first mixing stage, first, the filler and at least one ethoxylated compound of formula (I) and optionally further rubber auxiliaries as described above are incorporated into the rubber in an internal mixer (kneader). The mixing temperature in the internal mixer may reach a value up to 170 °C. The mixing temperature in the internal mixer is preferably 130 °C to 170 °C, particularly preferably 140 °C to 160 °C.

[0089] Subsequently, it is preferable to carry out so-called post-kneading, preferably at 130 to 170 °C, particularly preferably at 150 °C. The post-kneading may be carried out, for example, in a kneader, i.e., an internal mixer.

[0090] In the second mixing stage, a crosslinking agent, a vulcanization accelerator, and optionally further rubber auxiliaries as described above, preferably a secondary accelerator and an aging stabilizer, are added to the mixture obtained in the first mixing stage. The mixing temperature in the second mixing stage is preferably 50 to 150 °C, preferably 55 to 140 °C, particularly 60 °C to 130 °C.

[0091] The second mixing stage is preferably carried out on a roller mill equipped with water-cooled rollers. This is possible at a lower mixing temperature than in the first mixing stage.

[0092] The addition of at least one ethoxylated compound of formula (I) is possible at any point in the mixing, but it is preferably carried out at a temperature in the range of 130 °C to 170 °C, preferably 140 to 160 °C, in the first step of the mixing operation.

[0093] At least one ethoxylated compound of formula (I) may be employed in pure form in its mixing process or, alternatively, in a form absorbed and / or adsorbed on an inert organic or inorganic carrier, preferably a carrier selected from the group consisting of: natural or synthetic silicates, in particular neutral, acidic or basic silica, aluminium oxide, carbon black or zinc oxide.

[0094] Bonding mixture The present invention further provides a bonding mixture comprising the rubber mixture according to the invention and at least one bonding agent.

[0095] The bonding mixture according to the invention preferably contains at least one bonding agent based on resorcinol, formaldehyde and silica.

[0096] The combination of resorcinol, formaldehyde and silica is also known from the prior art as an RFS direct bonding system. The bonding mixture according to the invention may contain these direct bonding systems in any amount.

[0097] The bonding mixture according to the invention can be produced in a known manner by mixing the rubber mixture according to the invention with at least one bonding agent based on resorcinol, formaldehyde and silica.

[0098] Among the bonding agents, formaldehyde may be present in the form of a formaldehyde donor. Suitable formaldehyde donors include not only hexamethylenetetramine but also methylolamine derivatives.

[0099] For the purpose of improving the bondability, one or more components capable of forming a synthetic resin, such as, for example, phenol and / or amine and / or an aldehyde or a compound releasing an aldehyde, may be added to the bonding mixture according to the invention.

[0100] Process for producing a vulcanized rubber A process for producing a vulcanized rubber, characterized in that the rubber mixture according to the invention is heated to a temperature of 120°C to 200°C, preferably 140°C to 180°C.

[0101] The process for producing a vulcanized rubber according to the invention can be carried out at a wide pressure range, preferably a pressure in the range of 10 to 200 bar.

[0102] The present invention further provides a vulcanized rubber that can be obtained by vulcanizing the rubber mixture according to the invention.

[0103] The vulcanized rubber according to the invention, when used particularly in tires, has a surprisingly low rolling resistance while having corresponding performance characteristics.

[0104] In the context of the present invention, the rolling resistance is measured via the loss factor tanδ at 60°C according to the dynamic damping of DIN 53513.

[0105] Molded article The rubber mixture of the present invention is suitable for manufacturing all types of molded articles, such as components of tires, industrial rubber articles such as damping elements, roller covers, covers for conveyor belts, transmission belts, spinning cops, seals, cores of golf balls, soles of footwear, etc. They are particularly suitable for manufacturing tires and tire components, such as tire treads, subtreads, carcasses, sidewalls of tires, reinforced sidewalls for run-flat tires, and apex mixtures. Tire treads further include summer, winter, and all-season tire treads, as well as tire treads for passenger cars, trucks, and light trucks.

[0106] Preferred molded articles are tires and tire parts containing the vulcanized rubber according to the invention.

[0107] The present invention further provides for the use of at least one ethoxylated compound of formula (I), in particular in an amount of 0.5 to 10.0 phr, at a vulcanization temperature of 120°C to 200°C, for producing a vulcanizate made from a sulfur-crosslinkable rubber mixture and having low rolling resistance.

[0108] The present invention also provides for the use of at least one ethoxylated compound of formula (I) in a rubber mixture, a vulcanizate, and a molded article producible therefrom, for reducing the rolling resistance of a molded article made from a rubber vulcanizate, preferably a tire and tire parts.

[0109] The details and preferred ranges described for the plurality of components present and, optionally, the components present in the rubber mixtures in the present invention, for example, at least one synthetic rubber, at least one natural rubber, at least one hydroxyl-containing oxide-based filler, at least one carbon black, at least one crosslinking agent, at least one vulcanization accelerator, zinc oxide, at least one secondary accelerator, at least one reinforcing additive, rubber auxiliaries, and at least one ethoxylated compound of formula (I) are equally applicable to the disclosed processes, uses, and vulcanizates, molded articles, and bonding mixtures.

[0110] The above details and preferred ranges are equally applicable to the rubber mixtures, vulcanizates, molded articles, bonding mixtures, processes, and uses in the present invention, regardless of whether they are disclosed in the plural (e.g., rubber mixtures) or singular (e.g., rubber mixture) above.

[0111] The present invention will be illustrated by the following examples, which, however, should not be construed as limiting the invention thereto.

Examples

[0112] Exemplary Embodiments

[0113]

Table 1

[0114]

Table 2

[0115] Production of vulcanizate The rubber mixture of Example 1 of the non-invention was prepared according to the composition of the reference mixture from European Patent Application Publication No. 2858831 A1, and Examples 2 and 3 of the present invention were prepared according to the formulations described in Table 2.

[0116] The production of the rubber mixture was carried out in the following steps.

[0117] First mixing stage: · BUNA® CB 24 and BUNA® VSL 4526-2 HM were first charged into an internal mixer and mixed for about 30 seconds. · 2 / 3 of VULKASIL® S and 2 / 3 of SI® 69 were added and the mixture was mixed for about 60 seconds. · 1 / 3 of VULKASIL® S, 1 / 3 of SI® 69, and further TUDALEN® 1849-TE were added and the mixture was mixed for about 60 seconds.

[0118] CORAX® N 339, PALMERA® A9818, VULKANOX® 4020 / LG, VULKANOX® HS, ZINKOXID (ROTSIEGEL), LUTENSOL® TO5 were added and the mixture was mixed for about 60 seconds.

[0119] This mixing operation was carried out at a temperature of 150 °C.

[0120] When the first mixing stage was completed, the mixing batch was passed through a downstream roller mill and formed into sheets, strips, or pellets and stored at room temperature for 24 hours.

[0121] The processing temperature is 70 °C.

[0122] Subsequently, it was mixed at 150 °C in a kneader / internal mixer (so-called post-kneading).

[0123] Second mixing stage: Additives such as MAHLSCHWEFEL 90 / 95 CHANCEL, VULKACIT® CZ / C, Rhenogran® DPG-80 were added at 70 °C on a roller.

[0124]

Table 3

[0125] Technical tests Vulcanizates prepared at 170 °C from the rubber mixtures of Examples 1 to 3 were subjected to the technical tests described below. The measured values are shown in Table 3.

[0126] Extremely good performance of the rubber mixtures / their vulcanizates was achieved, and their performance is within the specified "preferred range".

[0127] In the tests on the test pieces, the following test methods were adopted.

[0128] Adopted rheometer (vulcanization meter) and scorch / full vulcanization time The MDR (Moving Die Rheometer) vulcanization profile and the associated analysis data are measured with an MDR 2000 Monsanto rheometer in accordance with ASTM D5289-95.

[0129] The scorch time (t5) is the time when 5% of the rubber is crosslinked. The selected temperature was 130 °C.

[0130] The full vulcanization time (t95) is the time when 95% of the rubber is crosslinked. The selected temperature was 170 °C.

[0131] Measurement of 300 modulus These measurements were carried out at a temperature of 23 °C in accordance with DIN 53504 (tensile test, S2 rod).

[0132] Measurement of Shore A hardness: These measurements were carried out at room temperature (RT) in accordance with DIN 53505.

[0133] Measurement of rolling resistance The loss factor tan δ was determined at 60 °C in accordance with the dynamic damping of DIN 53513.

[0134]

Table 4

[0135] Conclusion Surprisingly, it was found that: The rubber mixtures of the present invention of Examples 2 and 3 achieve a shorter full vulcanization time (t95) and a significantly lower loss factor tan δ at 60 °C compared to the non-inventive rubber mixture of Example 1 (corresponding to the composition of the reference mixture from European Patent Application Publication No. 2858831 A1), while the other mechanical properties remain substantially unchanged. Example 3 of the mixture of the present invention achieved a lower loss factor tan δ at 60 °C while maintaining an equivalent 300 modulus and hardness compared to the non-inventive rubber mixture of Example 1.

[0136] The rubber mixtures of the present invention in Examples 2 and 3 further achieved an improved scorch time (t5) compared to Rubber Compound 1 from European Patent Application Publication No. 2858831 A1, and the rubber mixture of the present invention in Example 3 further achieved a lower loss factor tan δ at 60 °C.

[0137] Numbers 2 and 3 of the rubber mixture of the present invention showed no speckling on the surface, from which it is presumed that the mixing of the additives employed was good.

Claims

1. A rubber mixture comprising: - 50 to 100 phr of at least one synthetic rubber, preferably BR rubber and / or SBR rubber, - 0 to 50 phr of at least one natural rubber, - 0.1 to 200 phr of at least one hydroxyl-containing oxide filler, - 0 to 120 phr, preferably 0.1 to 100 phr of at least one carbon black, - 0.1 to 20 phr of at least one crosslinking agent, preferably selected from the group consisting of sulfur donors and / or sulfur, and - 0.5 to 10 phr of at least one ethoxylated compound of formula (I) RO(CH ２ CH ２ O) ｘ H (I) [wherein, R represents an alkyl which may be branched or unbranched, x represents an integer from 1 to 20] A rubber mixture containing the same.

2. R is C １ ~C ２０ -alkyl, preferably C ５ ~C １７ -alkyl, particularly preferably C １０ ~C １５ -alkyl, very particularly preferably iso-C １３ -alkyl, extremely very particularly preferably iso-C １３ H ２７ The rubber mixture according to claim 1, characterized in that it represents

3. The rubber mixture according to any one of Claims 1 or 2, characterized in that x represents an integer from 2 to 15, preferably from 3 to 10, particularly preferably from 4 to 6, and very particularly preferably 5.

4. The rubber mixture according to any one of Claims 1 to 3, characterized in that the at least one synthetic rubber is selected from the group consisting of polar and non-polar synthetic rubbers, preferably selected from the group consisting of SBR rubber and BR rubber.

5. The rubber mixture according to any one of Claims 1 to 4, characterized in that the at least one hydroxyl-containing oxide filler is selected from the group consisting of silica, synthetic silicates, and natural silicates, and is present in the rubber mixture in an amount of 0.1 to 200 phr, preferably 20 to 160 phr, particularly preferably 25 to 140 phr, and very particularly preferably 30 to 120 phr.

6. The rubber mixture according to any one of Claims 1 to 5, characterized in that the at least one crosslinking agent contains sulfur in an amount of from 0.1 to less than 1.8 phr, preferably 1.0 to 1.7 phr, particularly preferably 1.3 to 1.7 phr.

7. The rubber mixture according to any one of Claims 1 to 5, characterized in that the at least one crosslinking agent contains sulfur in an amount of 1.8 to 20 phr, preferably 1.9 to 8.0 phr, particularly preferably 1.9 to 5 phr, and very particularly preferably 1.9 to 3 phr.

8. A rubber mixture according to any one of claims 1 to 7, characterized in that it contains at least one reinforcing additive from the group of sulfur-containing organic silanes, in particular sulfur-containing silanes having an alkoxysilyl group, particularly preferably sulfur-containing organic silanes having a trialkoxysilyl group.

9. - 50 to 100 phr of at least one synthetic rubber, in particular BR rubber and / or SBR rubber, - at least one silica of 20 to 160 phr, in particular, 5 to 1000 m ２ / g, preferably 20 to 400 m ２ / g of specific surface area (BET method) and having a primary particle size of 100 to 400 nm - At least one carbon black in an amount of 0.1 to 100 phr, in particular having a specific surface area (BET method) in the range of 20 to 200 m ２ / g, - 0.5 to 10 phr of at least one crosslinking agent, in particular from the group of sulfur donors and / or sulfur, - 0.1 to 10 phr of zinc oxide, - 0.5 to 10 phr of at least one vulcanization accelerator, in particular from the group of sulfenamides, - 0.1 to 10.0 phr of at least one secondary accelerator, - 0.5 to 15 phr of at least one reinforcing additive, in particular from the group of sulfur-containing silanes, - 0.1 to 30 phr of rubber auxiliaries, and - 0.5 to 10.0 phr of at least one ethoxylated compound of formula (I), characterized in that it contains a rubber mixture according to claim 1.

10. A process for producing a rubber mixture according to any one of claims 1 to 9, characterized in that the respective components are mixed in a mixing process.

11. Use of a rubber mixture according to any one of claims 1 to 9 for producing vulcanizates and various rubber molded articles, in particular for producing tires and tire components.

12. A vulcanizate obtained by vulcanizing at least one of the rubber mixtures according to any one of claims 1 to 9, preferably at a temperature of 120 °C to 200 °C.

13. A vehicle tire characterized in that it contains at least one of the vulcanizates according to claim 12.

14. Use of at least one ethoxylated compound of formula (I), RO(CH ２ CH ２ O) ｘ H (I) [wherein, R represents alkyl (the alkyl may be branched or unbranched), x represents an integer from 1 to 20] In particular, in an amount of 0.5 to 10.0 phr, at a vulcanization temperature of 120 °C to 200 °C, for producing a vulcanizate having low rolling resistance from a sulfur-crosslinkable rubber mixture.

15. Use of at least one ethoxylated compound of formula (I), RO(CH ２ CH ２ O) ｘ H (I) [wherein, R represents alkyl (the alkyl may be branched or unbranched), x represents an integer from 1 to 20] Use for reducing the rolling resistance of a molded article made from a rubber vulcanizate, preferably a tire and tire parts, in a rubber mixture, a vulcanizate, and a molded article obtainable therefrom.

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