Rubber blends containing ethoxylated alcohol

Abstract

The invention relates to rubber blends that contain, in addition to specific amounts of synthetic rubber, fillers and cross-linking agents, 0.5 to 10 phr of the at least one ethoxylated compound of formula (I): RO(CH2CH2O)xH, wherein R represents alkyl, and the alkyl can be branched or unbranched, and x represents an integer between 1 and 20, and that are suitable for producing vulcanized products having a low rolling resistance.

Description

[0001] alcohol

[0002] The invention relates to novel rubber mixtures comprising at least one ethoxylated compound of the formula (I), processes for their preparation and their use for producing rubber vulcanizates, the corresponding vulcanizates and the use of at least one ethoxylated compound of the formula (I) in rubber mixtures, vulcanizates and moldings obtainable therefrom for reducing the rolling resistance of moldings comprising these vulcanizates, preferably of tires.

[0003] The EU has committed to reducing its greenhouse gas emissions to achieve climate neutrality by 2050. Reducing carbon emissions from road transport plays a major role in achieving these goals.

[0004] A new EU tire labeling system, which came into force on May 1, 2021, is based on three key tire characteristics: rolling resistance—and thus fuel efficiency—wet grip, and external rolling noise. The new EU tire label enables consumers to consciously choose more fuel-efficient tires.

[0005] More fuel-efficient tires contribute to reducing emissions in road traffic. Depending on the tire's rolling resistance, fuel efficiency ranges from Class A (best fuel efficiency) to Class E. Fuel consumption plays an important role from both an economic and ecological perspective. Low fuel consumption has a positive impact on the vehicle's CO2 footprint, especially for heavy-duty commercial vehicles.

[0006] Against this background, tire manufacturers are looking for economical ways to achieve the Class A fuel efficiency target for tires.

[0007] The use of silica-containing rubber compounds for the production of passenger car tire treads is well known. The silica contributes to a good combination of rolling resistance, wet skid resistance, and abrasion properties, as required for passenger car tire treads. To achieve the desired combination of properties, it is important to disperse the silica well in the rubber compound and optimally couple it to the rubber matrix during vulcanization.

[0008] To improve the processability of silicic acid-containing rubber compounds, other additives can be added, such as fatty acid esters, fatty acid salts, or mineral oils. These additives have the disadvantage that they increase flowability, but at the same time reduce the stress values ​​at greater elongation (e.g., 100% to 300%) or the hardness of the vulcanizates, thus impairing the reinforcing effect of the filler. However, insufficient hardness or stiffness of the vulcanizate results in unsatisfactory tire handling, particularly in curves. The loss factor tan δ provides important information for assessing rolling resistance. The lower the loss factor tan δ, the lower the rolling resistance. The loss factor tan δ should be as low as possible at 60 to 70 °C; according to US 9783658B2 < 0.2, and according to EP 2858831A2 < 0.12.

[0009] EP 2858831A2 discloses that rubber compounds containing 1 phr of 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane (CAS No.: 151900-44-6) and 1 phr of certain sulfur-containing additives result in vulcanizates with good dynamic behavior, good hardness / stiffness, good rolling resistance, and low abrasion. A disadvantage is that the scorch time (t5) is significantly shortened during vulcanization of this rubber compound, which is a major disadvantage in terms of processing reliability. From the perspective of the rubber processing industry, it is also more advantageous to use only a few compound components.

[0010] In US 9376551A1, rolling resistance is reduced by adding certain organosilicon polysulfides. The results in Table 2 of US 9376551A1 show that 1 phr of the organosilicon polysulfide reduces the loss factor (tan δ at 60°C) by more than 10 percent. Mechanical properties such as tensile strength, elongation at break, and 300 modulus remained virtually unchanged. Another disadvantage here is that the scorch time is drastically reduced by adding the organosilicon polysulfide.

[0011] The object of the present invention was therefore to provide improved rubber mixtures based on a hydroxyl-containing oxidic filler that overcome the aforementioned disadvantages and lead to vulcanizates and molded articles produced therefrom, such as tire treads, that exhibit low rolling resistance, measured by the loss factor tan δ at 60°C, while maintaining virtually constant properties such as modulus 300 and hardness. Preferably, the improved rubber mixtures should also exhibit shortened vulcanization times (t95). Further preferably, the improved rubber mixtures should exhibit low rolling resistance, measured by the loss factor tan δ at 60°C, while maintaining constant modulus 300 and hardness.

[0012] A low loss factor tan δ at 60 °C, determined according to dynamic damping DIN 53513, is preferably less than 0.2, particularly preferably less than 0.12. The scorching time t5, determined according to ASTM D5289-95, at 130 °C is preferably in the range of 1000-1500 seconds, particularly preferably in the range of 1300-1500 seconds.

[0013] A short curing time t95 (conversion time 95%), determined according to ASTM D5289-95, at a temperature of 170 °C is preferably in the range of 500 - 1000 seconds.

[0014] A high modulus 300 value is also advantageous for vulcanizates, especially for tire treads. The preferred modulus 300 value (determined according to DIN 53504) is 10-25 MPa.

[0015] The hardness, determined according to DIN53505, should be in the range of 60 - 75 Shore A.

[0016] In the following, the unit “phr” stands for parts by weight based on 100 parts by weight of the total amount of rubber contained in the rubber mixture, i.e. the total amount of synthetic rubber(s) and natural rubber(s).

[0017] Surprisingly, the above object is achieved by rubber mixtures according to the invention containing

[0018] - 50 to 100 phr of at least one synthetic rubber, preferably BR rubber and / or SBR rubber,

[0019] - 0 to 50 phr of at least one natural rubber,

[0020] - 0.1 to 200 phr of at least one hydroxyl-containing oxidic filler,

[0021] - 0 to 120 phr of at least one carbon black, preferably 0.1 to 100 phr,

[0022] - 0.1 to 20 phr of at least one crosslinker, preferably selected from the group of sulphur donors and / or sulphur, and

[0023] 0.5 to 10 phr of at least one ethoxylated compound of formula (I)

[0024] RO(CH2CH2O)XH (I) where

[0025] R represents alkyl, where alkyl may be branched or unbranched, and x represents an integer from 1 to 20. Surprisingly, the vulcanizates according to the invention, obtained by vulcanization of the rubber mixtures according to the invention, are characterized by a low loss factor tan δ at 60 °C and a short vulcanization time (t95) while maintaining equally good application properties such as modulus 300, hardness and vulcanization behavior.

[0026] Rubbers

[0027] The rubber mixtures according to the invention contain at least one synthetic rubber, preferably selected from the group consisting of polar and non-polar synthetic rubbers.

[0028] Preferred polar and non-polar synthetic rubbers are

[0029] BR - Polybutadien

[0030] ABR - Butadiene / acrylic acid C1-C4 alkyl ester copolymer

[0031] CR - Polychloroprene

[0032] IR - Polyisoprene

[0033] SBR - styrene / butadiene copolymers with styrene contents of 1 - 60, preferably 20-50 wt.%

[0034] II R - Isobutylene / isoprene copolymers

[0035] NBR - butadiene / acrylonitrile copolymers with acrylonitrile contents of 5-60, preferably 10-50 wt.%

[0036] HNBR - partially hydrogenated or fully hydrogenated NBR rubber

[0037] EPDM - ethylene / propylene / diene copolymers

[0038] SIBR - Styrene-Isoprene-Butadiene Rubber

[0039] ENR - Epoxidized natural rubber

[0040] SNBR - Acrylonitrile-styrene / butadiene rubber

[0041] HNBR - Hydrogenated acrylonitrile / butadiene rubber XNBR - Carboxylated acrylonitrile / butadiene rubber

[0042] HXNBR - Hydrogenated carboxylated acrylonitrile / butadiene rubber

[0043] Preferably, the at least one synthetic rubber is selected from the group consisting of SBR and BR rubber.

[0044] The rubber mixtures according to the invention preferably contain at least one SBR rubber and / or one BR rubber, particularly preferably one SBR and one BR rubber.

[0045] The SBR rubber can be a functionalized SBR rubber.

[0046] Functionalized SBR rubber is understood to mean an SBR rubber which is substituted on the main chain and / or on the end groups by one or more functional groups, in particular carboxyl groups and / or mercaptan-containing groups.

[0047] In a preferred embodiment, the rubber mixtures according to the invention contain at least one functionalized SBR rubber and optionally one or more BR rubbers.

[0048] The rubber mixtures according to the invention contain 50 to 100 phr of at least one synthetic rubber, preferably 70-100 phr.

[0049] The rubber mixtures according to the invention preferably contain at least one SBR and at least one BR rubber in a weight ratio SBR:BR of 100:0 to 0:100, particularly preferably of 90:10 to 10:90, very particularly preferably of 90:10 to 50:50, very particularly preferably of 80:20 to 60:40.

[0050] In an alternative advantageous embodiment, the rubber mixtures according to the invention contain at least one natural rubber. The rubber mixtures according to the invention can contain 0 to 50 phr of natural rubber, preferably 0-30 phr.

[0051] Ethoxylated compound of formula (I)

[0052] The rubber mixtures according to the invention contain at least one ethoxylated compound of the formula (I)

[0053] RO(CH2CH2O)XH (I) where

[0054] R represents alkyl, where alkyl may be branched or unbranched, and x represents an integer from 1 to 20.

[0055] R preferably represents C1-C20-alkyl, particularly preferably C5-C18-alkyl, very particularly preferably C10-C18-alkyl, very particularly preferably / 50-C13H27.

[0056] Preferably, x is an integer from 2 to 15, particularly preferably from 3 to 10, most preferably from 4 to 6, most preferably x is 5.

[0057] At least one ethoxylated compound of formula (I) is contained, for example, in LUTENSOL® TO 5 from BASF.

[0058] The rubber mixtures according to the invention generally contain the at least one ethoxylated compound of the 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.

[0059] Fillers

[0060] The at least one hydroxyl-containing oxidic filler is preferably selected from the group consisting of silicic acids, synthetic silicates and natural silicates.

[0061] The content of hydroxyl-containing oxidic fillers in the rubber mixtures according to the invention is 0.1 to 200 phr, preferably 20 to 160 phr, particularly preferably 25 to 140 phr and very particularly preferably 30 to 120 phr.

[0062] Oxidic fillers containing hydroxyl groups are preferably those from the series of

[0063] - Silicas, in particular with a specific surface area (BET) of 5 to 1000, preferably 20 to 400 m 2 / g, preferably with primary particle sizes of 100 to 400 nm, the silicas optionally also being present as mixed oxides with other metal oxides, such as Al, Mg, Ca, Ba, Zr, Ti oxides,

[0064] - synthetic silicates, such as aluminum silicate, alkaline earth silicates such as magnesium silicate or calcium silicate, with specific surface areas (BET) of 20 to 400 m 2 / g, preferably with primary particle sizes of 10 to 400 nm and natural silicates, such as kaolin and other naturally occurring silicic acids, as well as mixtures thereof.

[0065] The above-mentioned BET surface areas are determined according to DIN ISO 9277. The primary particle size specifications are based on measurements using a particle analysis device using scattered light. The particle size calculation is based on the Mie theory, which describes the interaction between light and matter (DIN / ISO 13320).

[0066] The silicas are preferably obtainable by precipitation of solutions of silicates or flame hydrolysis of silicon halides.

[0067] The rubber mixtures according to the invention preferably contain at least one hydroxyl-containing oxidic filler from the series of silicas, in particular with a specific surface area (BET) in the range from 5 to 1000, preferably 20 to 400 m 2 / g in an amount of 0.1 to 200 phr, preferably 20 to 160 phr, particularly preferably 25 to 140 phr, most preferably 30 - 120 phr.

[0068] The rubber mixtures according to the invention may contain at least one carbon black as filler.

[0069] In a preferred embodiment, the rubber mixtures according to the invention contain at least one carbon black as filler.

[0070] The rubber mixtures according to the invention preferably contain 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, very particularly preferably 2 to 40 phr.

[0071] Preferred carbon blacks are those obtainable by the lamp black, furnace black or gas black process and which have a specific surface area (BET) in the range of 20 to 200 m 2 / g, such as SAF, ISAF, IISAF, HAF, FEF, or GPF carbon blacks. The rubber mixtures according to the invention preferably contain at least one carbon black with a specific surface area (BET) in the range of 20 to 200 m 2 / g .

[0072] The rubber mixtures according to the invention particularly preferably contain as fillers at least one of the above-mentioned silicas and at least one of the above-mentioned carbon blacks.

[0073] The rubber mixtures according to the invention very particularly preferably contain, as fillers, 25 to 140 phr, preferably 30 to 120 phr, of at least one of the above-mentioned silicas and 1.0 to 70 phr, preferably 2.0 to 40 phr, of at least one of the above-mentioned carbon blacks. The total amount of 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.

[0074] Crosslinkers and vulcanization accelerators

[0075] The rubber mixtures according to the invention may contain one or more crosslinking agents.

[0076] The rubber mixtures according to the invention preferably contain at least one crosslinker from the group consisting of sulfur and sulfur donors.

[0077] Sulfur can be used in elemental soluble or insoluble form.

[0078] The rubber mixtures according to the invention particularly preferably contain at least one sulfur donor and / or sulfur, very particularly preferably sulfur.

[0079] Examples of sulfur donors include dimorpholyl disulfide (DTDM), 2-morpholinodithiobenzothiazole (MBSS), caprolactam disulfide, dipentamethylene thiuram tetrasulfide (DPTT), tetramethylthiuram disulfide (TMTD) and tetrabenzyl thiuram disulfide (TBzTD).

[0080] The rubber mixtures according to the invention generally contain from 0.1 to 20 phr, preferably from 0.5 to 10 phr and particularly preferably from 1.0 to 8 phr of at least one crosslinker from the group consisting of sulfur and sulfur donors.

[0081] In a particularly preferred embodiment, the rubber mixtures according to the invention contain 0.1 to less than 1.8 phr, very particularly preferably 1.0 to 1.7 phr, very particularly preferably 1.3 to 1.7 phr of sulfur in the at least one crosslinker.

[0082] In an alternative particularly preferred embodiment, the rubber mixtures according to the invention contain 1.8 to 20 phr, very particularly preferably 1.9 to 8.0 phr, very particularly preferably 1.9 to 5 phr, most preferably 1.9 to 3 phr of sulfur in the at least one crosslinker.

[0083] This latter embodiment achieves the additional objective of providing improved rubber compounds that exhibit particularly low rolling resistance, measured by the loss factor tan δ at 60°C, while maintaining a constant modulus of 300 and hardness. The term "phr of sulfur in the at least one crosslinker" in the two aforementioned embodiments expresses that the previously stated phr of sulfur refers to the amount of sulfur in the at least one crosslinker and, accordingly, also to sulfur used in the form of a sulfur donor.

[0084] Zinc oxide can be present in the rubber mixtures according to the invention. It acts as a complexing agent for sulfur and as a sulfur donor, thus facilitating the binding of the sulfur to the rubber matrix.

[0085] Preferred rubber mixtures according to the invention contain zinc oxide with a BET surface area of ​​2 to 100 m 2 / g, preferably 2 to 70 m 2 / g. BET surface areas of zinc oxide can be measured according to DIN ISO 9277.

[0086] In general, zinc oxide is present in the rubber mixtures according to the invention in an amount of 0 to 20 phr, preferably 0.1 to 10 phr, particularly preferably 1 to 5 phr.

[0087] The rubber mixtures according to the invention may contain one or more vulcanization accelerators.

[0088] The rubber mixtures according to the invention preferably contain at least one vulcanization accelerator, particularly preferably from the group of mercaptobenzothiazoles, thiocarbamates, dithiocarbamates, thiurams, thiazoles, sulfenamides, thiazolesulfenamides, xanthates, bi- or polycyclic amines, thiophosphates, dithiophosphates, caprolactams, thiourea derivatives, guanidines, cyclic disulfanes and amines, in particular zinc diamine diisocyanate, hexamethylenetetramine, 1,3-bis(citraconimidomethyl)benzene and very particularly preferably from the group of sulfenamides, very particularly preferably N-cyclohexylbenzothiazolesulfenamide (CAS No.: 95-33-0).

[0089] The rubber mixtures according to the invention generally contain 0.1 to 20 phr, preferably 0.5 to 10 phr and particularly preferably 1.0 to 5 phr of at least one of the vulcanization accelerators mentioned.

[0090] The rubber mixtures according to the invention preferably contain at least one crosslinker and at least one vulcanization accelerator.

[0091] The rubber mixtures according to the invention particularly preferably contain at least one crosslinker from the series of sulfur and sulfur donors and at least one vulcanization accelerator from the series of mercaptobenzothiazoles, thiazole sulfenamides, thiurams, dithiocarbamates, xanthates and thiophosphates, particularly preferably the sulfenamides, very particularly preferably N-cyclohexylbenzothiazole sulfenamides (CAS No.: 95-33-0).

[0092] The rubber mixtures according to the invention particularly preferably contain at least one crosslinker selected from the group consisting of sulfur and sulfur donors, at least one vulcanization accelerator selected from the group consisting of mercaptobenzothiazoles, thiazole sulfenamides, thiurams, dithiocarbamates, xanthates and thiophosphates, particularly preferably the sulfenamides, very particularly preferably N-cyclohexylbenzothiazole-2-sulfenamides (CAS No.: 95-33-0) and zinc oxide.

[0093] The total amount of crosslinker and vulcanization accelerator in the rubber mixtures is preferably 1.0 to 20 phr, particularly preferably 2.0 to 13 phr.

[0094] Reinforcing additives

[0095] The rubber mixtures according to the invention may contain one or more reinforcing additives.

[0096] The rubber mixtures according to the invention preferably contain at least one reinforcing additive from the series of sulfur-containing organic silanes, in particular sulfur-containing silanes containing alkoxysilyl groups and very particularly preferably sulfur-containing organic silanes containing trialkoxysilyl groups.

[0097] The rubber mixtures according to the invention particularly preferably contain one or more sulfur-containing silanes from the series bis-(triethoxysilylpropyl)-tetrasulfane, bis-(triethoxysilylpropyl)-disulfane and 3-(triethoxysilyl)-1-propanethiol.

[0098] Liquid sulfur-containing silanes can be coated on a carrier (dry liquid) for improved dosing and / or dispersibility. The content of sulfur-containing silanes in these "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 dry liquid.

[0099] The rubber mixtures according to the invention generally contain 0.1 to 20 phr, preferably 0.5 to 15 phr and particularly preferably 1.0 to 10 phr of at least one reinforcing additive.

[0100] Rubber auxiliaries

[0101] The rubber mixtures according to the invention may further contain one or more rubber auxiliaries. Examples of suitable rubber auxiliaries include anti-aging agents, coupling agents, heat stabilizers, light stabilizers, flame retardants, processing aids, impact modifiers, plasticizers, tackifiers, blowing agents, dyes, pigments, waxes, extenders, organic acids such as stearic acid, retarders, especially triethanolamine, polyethylene glycol, hexanetriol, and anti-reversion agents, as well as secondary accelerators.

[0102] These rubber auxiliaries can be added to the rubber mixtures according to the invention in the amounts customary for these auxiliaries, which also depend on the intended use of the vulcanizates produced therefrom. Typical amounts are, for example, 0.1 to 30 phr.

[0103] The rubber mixtures according to the invention can contain one or more age inhibitors. Suitable age inhibitors are amine-based age inhibitors such as diaryl-p-phenylenediamines (DTPD), octylated diphenylamine (ODPA), phenyl-anaphthylamine (PAN), phenyl-ß-naphthylamine (PBN), preferably those based on phenylenediamine, e.g. N,N'-dicyclohexyl-p-phenylenediamine (CCPD), N-isopropyl-N'-phenyl-p-phenylenediamine, N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD), N-1,4-

[0104] 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), as well as mixtures thereof. Particularly preferably, the at least one anti-aging agent is selected from the group consisting of N,N'-dicyclohexyl-p-phenylenediamine (CCPD) and N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD).

[0105] Processing aids are intended to act between the rubber particles and counteract frictional forces during mixing, plasticizing, and molding. The rubber mixtures according to the invention can contain all lubricants customary for processing plastics as processing aids, such as hydrocarbons such as oils, paraffins, and PE waxes; fatty alcohols with 6 to 20 carbon atoms; ketones; carboxylic acids such as fatty acids and montanic acids; oxidized PE wax; metal salts of carboxylic acids; carboxylic acid amides; and carboxylic acid esters, for example, with the alcohols ethanol, fatty alcohols, glycerol, ethanediol, pentaerythritol, and long-chain carboxylic acids as the acid component.

[0106] To reduce flammability and smoke development during combustion, the rubber mixtures according to the invention can contain flame retardants. Examples of flame retardants used include antimony trioxide, phosphoric acid esters, chlorinated paraffin, aluminum hydroxide, boron compounds, zinc compounds (except ZnO), molybdenum trioxide, ferrocene, calcium carbonate, or magnesium carbonate.

[0107] Before crosslinking, other plastics can also be added to the rubber mixtures according to the invention, which act, for example, as polymeric processing aids or impact strength improvers. These plastics are preferably selected from the group consisting of homo- and copolymers based on ethylene, propylene, butadiene, styrene, vinyl acetate, vinyl chloride, glycidyl acrylate, glycidyl methacrylate, acrylates and methacrylates with alcohol components of branched or unbranched C1 to C10 alcohols, with polyacrylates with identical or different alcohol radicals from the group of C4 to C8 alcohols, in particular butanol, hexanol, octanol and 2-ethylhexanol, polymethyl methacrylate, methyl methacrylate-butyl acrylate copolymers, methyl methacrylate-butyl methacrylate copolymers, ethylene-vinyl acetate copolymers, chlorinated polyethylene, ethylene-propylene copolymers, ethylene-propylene-diene copolymers being particularly preferred.

[0108] Known adhesives based on resorcinol, formaldehyde, and silica, the so-called RFS direct adhesion systems, are used. These direct adhesion systems can be used in any amount of the rubber mixture according to the invention at any time during mixing into the rubber mixtures according to the invention.

[0109] In silica-based rubber compounds, which are preferably used in tire production, diphenylguanidine (DPG) or structurally similar aromatic guanidines are typically used as secondary accelerators.

[0110] Those skilled in the art know that DPG can be advantageously substituted with 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane, also known under the trade name Vulcuren®. Replacing DPG with a secondary accelerator such as TBzTD (tetrabenzylthiuram disulfide) or dithiophosphates is also possible.

[0111] The rubber mixtures according to the invention generally contain 0 or from 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 secondary accelerators mentioned.

[0112] Particularly preferred rubber mixtures according to the invention are those containing

[0113] 50 to 100 phr of at least one synthetic rubber, in particular BR rubber and / or S BR rubber, - 20 to 160 phr of at least one silica, in particular with a specific surface area (BET) of 5 to 1000, preferably 20 to 400 m 2 / g and with primary particle sizes from 100 to 400 nm,

[0114] 0.1 to 100 phr of at least one carbon black, in particular with a specific surface area (BET) in the range of 20 to 200 m 2 / G,

[0115] 0.5 to 10 phr of at least one crosslinking agent, in particular from the series of sulphur donors and / or sulphur, 0.1 to 10 phr of zinc oxide,

[0116] 0.5 to 10 phr of at least one vulcanization accelerator, in particular from the sulfenamide series,

[0117] 0.1 to 10.0 phr of at least one secondary accelerator,

[0118] 0.5 to 15 phr of at least one reinforcing additive, in particular from the group of sulfur-containing silanes

[0119] 0.1 to 30 phr rubber additives and

[0120] 0.5 to 10.0 phr of at least one ethoxylated compound of formula (I).

[0121] The above-mentioned further preferred ranges of the individual components also apply to these preferred mixtures.

[0122] Process for producing rubber mixtures

[0123] The present invention further provides a process for producing the rubber mixtures according to the invention, characterized in that the respective components are mixed in a mixing process. Preferably, at least one synthetic rubber, optionally at least one natural rubber, and at least one ethoxylated compound of the formula (I) are mixed together, optionally in the presence of at least one filler, optionally at least one crosslinker, 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 of the rubber auxiliaries mentioned in the general and preferred amounts mentioned for these additives, at a temperature in the range from 30 to 170°C, particularly preferably from 140 to 160°C.

[0124] The rubber mixtures according to the invention are produced in the usual way in known mixing units, such as rollers, internal mixers, downstream mixing roll mills and mixing extruders at shear rates of 1 to 1000 see 1 The rubber mixtures according to the invention are preferably produced in a two-stage mixing process. In a first mixing stage, the fillers and the at least one ethoxylated compound of formula (I), as well as any other rubber auxiliaries mentioned above, are incorporated into the rubber in an internal mixer (kneader). Mixing temperatures in the internal mixer can reach values ​​of up to 170°C. The mixing temperature in the internal mixer is preferably 130 to 170°C, particularly preferably 140 to 160°C.

[0125] This is followed by the so-called post-tweezing, preferably at 130-170°C, particularly preferably at 150°C. Post-tweezing can be carried out, for example, in a kneader or internal mixer.

[0126] In a second mixing stage, crosslinkers, vulcanization accelerators, and optionally other rubber auxiliaries mentioned above, preferably secondary accelerators and anti-aging agents, are added to the mixture obtained from the first mixing stage. The mixing temperature in the second mixing stage is preferably 50-150°C, more preferably 55-140°C, in particular from 60 to 130°C.

[0127] The second mixing stage is preferably carried out on a rolling mill with water-tempered rollers. This allows for a lower mixing temperature than in the first mixing stage.

[0128] The addition of the at least one ethoxylated compound of formula (I) can take place at any time during the mixing, preferably in the first step of the mixing process at a temperature in the range of 130°C to 170°C, preferably at a temperature of 140 to 160°C.

[0129] The at least one ethoxylated compound of formula (I) can be used in the mixing process both in pure form and on an inert, organic or inorganic carrier, preferably a carrier selected from the group containing natural or synthetic silicates, in particular neutral, acidic or basic silica, aluminum oxide, carbon black or zinc oxide, and / or adsorbed thereon.

[0130] Adhesive mixtures

[0131] The present invention further relates to adhesive mixtures comprising a rubber mixture according to the invention and at least one adhesive.

[0132] The adhesive mixtures according to the invention preferably contain at least one adhesive based on resorcinol, formaldehyde, and silica. Combinations of resorcinol, formaldehyde, and silica are known in the art as so-called RFS direct adhesion systems. The adhesive mixtures according to the invention can contain these direct adhesion systems in any desired amount.

[0133] The adhesive mixtures according to the invention can be prepared in a known manner by mixing a rubber mixture according to the invention with at least one adhesive based on resorcinol, formaldehyde and silica.

[0134] Formaldehyde can be present in the adhesives in the form of formaldehyde donors. Suitable formaldehyde donors include hexamethylenetetramine and methylolamine derivatives.

[0135] To improve the adhesion, one or more components capable of forming synthetic resins, such as phenol and / or amines and / or aldehydes or compounds releasing aldehydes, can be added to the adhesive mixtures according to the invention.

[0136] Process for producing rubber vulcanizates

[0137] The present invention further relates to a process for producing rubber vulcanizates, characterized in that the rubber mixture according to the invention is heated at temperatures of 120 to 200°C, preferably at 140 to 180°C.

[0138] The process for producing the rubber vulcanizates according to the invention can be carried out in a wide pressure range, preferably it is carried out at a pressure in the range of 10 to 200 bar.

[0139] The present invention further relates to rubber vulcanizates which are obtainable by vulcanization of the rubber mixtures according to the invention.

[0140] The rubber vulcanizates according to the invention have an unexpectedly low rolling resistance, particularly when used in tires, with comparable application properties.

[0141] In the context of this invention, the rolling resistance is determined via the loss factor tan ö at 60°C according to dynamic damping DIN 53513.

[0142] molded body

[0143] The rubber vulcanizates according to the invention are suitable for the production of all types of molded articles, such as tire components, technical rubber articles such as damping elements, roller coverings, conveyor belt coverings, belts, spinning cops, seals, golf ball cores, shoe soles. They are particularly suitable for the production of tires and tire parts, such as tire treads, subtreads, carcasses, tire sidewalls, reinforced sidewalls for run-flat tires, and apex compounds. Tire treads also include treads for summer, winter, and all-season tires, as well as treads for passenger car, truck, and light truck tires.

[0144] Preferred molded articles are tires and tire parts containing a rubber vulcanizate according to the invention.

[0145] The present invention further relates to the use of the at least one ethoxylated compound of formula (I) for producing vulcanizates with low rolling resistance from sulfur-crosslinkable rubber mixtures, in particular in an amount of 0.5 to 10.0 phr at a vulcanization temperature of 120 to 200°C.

[0146] The present invention further relates to the use of the at least one ethoxylated compound of the formula (I) in rubber mixtures, vulcanizates and moldings obtainable therefrom for reducing the rolling resistance of moldings made from rubber vulcanizates, preferably tires and tire parts.

[0147] The descriptions and preferred ranges given for the components contained and optionally contained in the rubber mixture according to the invention, such as the at least one synthetic rubber, the at least one natural rubber, the at least one hydroxyl-containing oxidic filler, the at least one carbon black, the at least one crosslinker, the at least one vulcanization accelerator, the zinc oxide, the at least one secondary accelerator, the at least one reinforcing additive, the rubber auxiliaries and the at least one ethoxylated compound of the formula (I), apply analogously to, among other things, the disclosed processes and uses as well as the vulcanizates, moldings and adhesive mixtures.

[0148] The descriptions and preferred areas given also apply to, among other things, the rubber mixtures, vulcanizates, moldings, adhesive mixtures, processes and uses according to the invention, regardless of whether they were disclosed for the aforementioned in the plural (e.g. rubber mixtures) or in the singular (e.g. rubber mixture).

[0149] The invention will be explained using the following examples, but without being limited thereto.

[0150] Table 1 : List of ingredients, abbreviations and manufacturers the rubber vulcanizates

[0151] The rubber mixtures of non-inventive example 1 were prepared according to the composition of the reference mixture from EP2858831A1 and of inventive examples 2 and 3 according to the recipes given in Table 1.

[0152] The rubber compounds were produced in the following steps:

[0153] 1. Mixing stage:

[0154] • BUNA® CB 24 and BUNA® VSL 4526-2 HM are placed in an internal mixer and mixed for approximately 30 seconds

[0155] ■ Add two-thirds of VULKASIL® S, two-thirds of Sl® 69 and mix for about 60 seconds

[0156] ■ Add one-third of VULKASIL® S, one-third of Sl® 69, and TUDALEN® 1849-TE, mix for approx. 60 seconds

[0157] Add CORAX® N 339, PALMERA® A9818, VULKANOX® 4020 / LG, VULKANOX® HS, ZINC OXIDE (ROTSIEGEL), LUTENSOL® TO 5, mix for approx. 60 seconds.

[0158] This mixing process took place at a temperature of 150°C.

[0159] After completion of the first mixing stage, the mixed piece is taken up by a downstream rolling mill and formed into a plate, strip or pellets and stored for 24 hours at room temperature.

[0160] Processing temperatures are 70°C.

[0161] This was followed by mixing at 150°C in a kneader / internal mixer (the so-called post-tweezing).

[0162] 2nd mixing stage:

[0163] The addition of additives such as CHANCEL GROUND SULPHUR 90 / 95, VULKACIT® CZ / C, and Rhenogran® DPG-80 on a roller was carried out at 70°C. Table 2: Rubber formulations

[0164] Technical inspection

[0165] The rubber mixtures prepared at 170°C from Examples 1 to 3

[0166] Vulcanizates were subjected to the technical tests listed below. The results are shown in Table 3.

[0167] Excellent properties of the rubber compounds or their vulcanizates were achieved when their property values ​​were within the specified "preferred range." The following test procedures were used for the tests on test specimens:

[0168] Rheometer (vulcameter) used and vulcanization / curing time

[0169] The vulcanization process on the MDR (moving die rheometer) and its analytical data were measured using a Monsanto MDR 2000 rheometer according to ASTM D5289-95. The scorch time (t5) is determined as the time at which 5% of the rubber is cured. The selected temperature was 130°C.

[0170] The curing time (t95) is determined as the time required for 95% of the rubber to cure. The chosen temperature was 170°C.

[0171] Determination of the modulus 300 These measurements were carried out according to DIN 53504 (tensile test rod S 2) at a temperature of 23°C.

[0172] Determination of Shore A hardness

[0173] The measurements were carried out at room temperature (RT) according to DIN 53 505.

[0174] Determination of rolling resistance The loss factor tan ö was determined at 60°C according to dynamic damping DIN 53513.

[0175] Table 3: Test values

[0176] Conclusion:

[0177] Surprisingly, it was found that with the inventive rubber mixtures according to Examples 2 and 3, a shorter vulcanization time (t95) and a significantly lower loss factor tan δ at 60°C were achieved compared to the non-inventive rubber mixture of Example 1 (corresponding to the composition of the reference mixture from EP2858831A1), with virtually unchanged other mechanical properties. With the inventive mixture 3, a lower loss factor tan δ at 60°C was achieved compared to the non-inventive rubber mixture of Example 1, with the same modulus 300 and hardness.

[0178] With the rubber mixtures according to the invention according to Examples 2 and 3, an improved scorching time (t5) was even achieved compared to the rubber formulation 1 from EP2858831A1, and with the rubber mixture according to the invention according to Example 3, even a lower loss factor tan δ at 60°C was achieved.

[0179] The rubber mixtures 2 and 3 according to the invention did not show any specks on the surface, so that it is assumed that the additives used were well mixed.

Claims

Rubber compound containing - 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 of at least one carbon black, preferably 0.1 to 100 phr, - 0.1 to 20 phr of at least one crosslinking agent, preferably selected from the range of sulfur donors and / or sulfur, as well as 0.5 to 10 phr of the at least one ethoxylated compound of formula (I) RO(CH2CH2O)XH (I) wherein R represents alkyl, where alkyl can be branched or unbranched, and x represents an integer from 1 to 20. Rubber compound according to claim 1, characterized in that R represents Ci-C2o-alkyl, preferably Cs-Cn-alkyl, particularly preferably C-Cis-alkyl, very preferably / so-Cn-alkyl, and very, very preferably / so-CI3H 27 A rubber compound according to claim 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 most preferably 5. A rubber compound according to any one of claims 1-3, characterized in that the at least one synthetic rubber is selected from the group consisting of polar and nonpolar synthetic rubbers, preferably selected from the group consisting of SBR and BR rubbers. A rubber compound according to any one of claims 1-4, characterized in that the at least one hydroxyl-group-containing oxide filler is selected from the group consisting of silicic acids, synthetic silicates, and natural silicates, and is present in the rubber compound in an amount of 0.1 to 200 phr, preferably 20 to 160 phr, particularly preferably 25 to 140 phr, and most preferably 30 to 120 phr. A rubber compound according to any one of claims 1-5, characterized in that it contains 0.1 to less than 1.8 phr, preferably 1.0 to 1.7 phr, and particularly preferably 1.3 to 1.7 phr of sulfur in the at least one crosslinking agent. Rubber compound according to one of claims 1-5, characterized in that it contains 1.8 to 20 phr, preferably 1.9 to 8.0 phr, particularly preferably 1.9 to 5 phr, most preferably 1.9 to 3 phr of sulfur in the at least one crosslinking agent.A rubber compound according to any one of claims 1-7, characterized in that it contains at least one reinforcing additive from the group of sulfur-containing organic silanes, in particular alkoxysilyl group-containing sulfur-containing silanes and especially preferably trialkoxysilyl group-containing sulfur-containing organic silanes. A rubber compound according to claim 1, characterized in that it. - 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 with a specific surface area (BET) of 5 to 1000, preferably 20 to 400 m² 2 / g, and with primary particle sizes from 100 to 400 nm, - 0.1 to 100 phr of at least one carbon black, in particular with a specific surface area (BET) in the range of 20 to 200 m² 2 / G, - 0.5 to 10 phr of at least one crosslinking agent, in particular from the series of sulfur donors and / or sulfur, - 0.1 to 10 phr zinc oxide, - 0.5 to 10 phr of at least one vulcanization accelerator, in particular from the sulfenamide series, - 0.1 to 10.0 phr of at least one secondary accelerator, - 0.5 to 15 phr of at least one strengthening additive, in particular from the group of sulfur-containing silanes - 0.1 to 30 phr rubber auxiliaries and - 0.5 to 10.0 phr containing at least one ethoxylated compound of formula (I).

10. Method for producing the rubber compounds according to the invention according to one of claims 1-9, characterized in that the respective components are mixed in a mixing process.

11. Use of the rubber compounds according to any one of claims 1-9 for the production of vulcanizates and rubber molded bodies of all kinds, in particular for the production of tires and tire components.

12. Vulcanizate obtained by vulcanization of at least one rubber compound according to any one of claims 1-9, preferably at a temperature of 120 to 200°C.

13. Vehicle tire, characterized in that it comprises at least one vulcanizate according to claim 12.

14. Use of the at least one ethoxylated compound of formula (I) RO(CH2CH2O)XH (I) wherein R stands for alkyl, where alkyl may be branched or unbranched, and x stands for an integer from 1 to 20, for the production of low rolling resistance vulcanizates from sulfur-crosslinkable rubber mixtures, in particular in an amount of 0.5 to 10.0 phr at a vulcanization temperature of 120 to 200°C.

15. Use of the at least one ethoxylated compound of formula (I) RO(CH2CH2O)xH (I) wherein R stands for alkyl, where alkyl may be branched or unbranched, and x stands for an integer from 1 to 20, in rubber mixtures, vulcanizates and molded parts obtainable therefrom for reducing the rolling resistance of molded parts made of rubber vulcanizates, preferably tires and tire parts.

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