Rubber blends containing at least one functionalized synthetic rubber and at least one ethoxylated alcohol

Abstract

The invention relates to rubber blends that contain, in addition to fillers and cross-linking agents, 50 to 100 phr of at least one functionalized synthetic rubber and 0.5 to 20 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 a rational number between 1 and 25, and that are suitable for producing vulcanized products having a low rolling resistance.

Description

[0001] Rubber mixtures containing at least one functionalized synthetic rubber and at least one ethoxylated alcohol

[0002] The invention relates to novel rubber mixtures comprising at least one functionalized synthetic rubber and 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 the at least one functionalized synthetic rubber and 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 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 silica-containing rubber compounds, additional 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 even reduce 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, especially when cornering. Insufficient hardness also leads to increased abrasion of the vulcanizate by the road surface and thus to an increased proportion of so-called "microplastics" in the environment. Tire abrasion is the main source of microplastics in rivers and lakes, accounting for approximately 28 percent of the plastic particles in the oceans.

[0009] The loss factor tan δ provides an important indicator 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, < 0.2 according to US 9783658B2, and < 0.12 according to EP 2858831A2.

[0010] EP 2858831 A2 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) during vulcanization of this rubber compound is significantly shortened, 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.

[0011] In US 9376551 A1, rolling resistance is reduced by adding certain organosilicon polysulfides. The results in Table 2 of US 9376551 A1 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.

[0012] 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, preferably at a measurement frequency of 10 Hz, while maintaining or improving properties such as modulus 300, elongation at break, and hardness. The improved rubber mixtures should preferably also exhibit shortened vulcanization times (t95) and extended scorch times (t5). Further preferably, the improved rubber mixtures should lead to vulcanizates that exhibit lower DIN abrasion and are thus more environmentally friendly.

[0013] A low loss factor tan δ at 60 °C, preferably at a measurement frequency of 10 Hz, determined according to dynamic damping DIN EN ISO 6721-1, is preferably less than 0.2, particularly preferably less than 0.12. The scorching time t5, determined according to ASTM D5289-95, at 160 °C is preferably in the range of 70-150 seconds, particularly preferably in the range of 85-140 seconds.

[0014] A short vulcanization time t95 (conversion time 95%), determined according to ASTM D5289-95, at a temperature of 160 °C is preferably in the range of 800 - 1300 seconds, particularly preferably 900 - 1200 seconds.

[0015] The Mooney viscosity ML 1 +4, determined according to ASTM D1646 at 100 °C, is preferably in a range of 30 to 100 MU, particularly preferably in the range of 50 to 90 MU.

[0016] A high modulus 300 value is also advantageous for vulcanizates, especially for tire treads. The modulus 300 (determined according to DIN 53504) is preferably 8-20 MPa, particularly preferably 9.5-20 MPa.

[0017] The hardness, determined according to DIN53505, should preferably be in a range of 55 - 70 Shore A.

[0018] The DIN abrasion, determined according to ASTM D5963, should preferably be low and particularly preferably less than 120 mm 3 , especially preferably less than 1 10 mm 3 , be.

[0019] 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 functionalized and unfunctionalized synthetic rubber(s) and natural rubber(s).

[0020] Surprisingly, the above object is achieved by rubber mixtures according to the invention containing

[0021] - 50 to 100 phr of at least one functionalized synthetic rubber, preferably a functionalized BR rubber and / or functionalized SBR rubber,

[0022] - 0 to 50 phr of at least one natural rubber and / or unfunctionalized synthetic rubber,

[0023] - 0.1 to 250 phr of at least one hydroxyl-containing oxidic filler,

[0024] - 0 to 120 phr of at least one carbon black, preferably 0.1 to 100 phr,

[0025] - 0.1 to 20 phr of at least one crosslinker, preferably selected from the group of sulphur donors and / or sulphur, and

[0026] 0.5 to 20 phr of at least one ethoxylated compound of formula (I) RO(CH2CH2O)XH (I) wherein

[0027] R represents alkyl, where alkyl can be branched or unbranched, and x represents a rational number from 1 to 25. 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 an improved modulus 300 as well as a reduced Mooney viscosity, short vulcanization time (t95) and sufficiently long scorching time (t5) while maintaining equally good application properties such as elongation at break, hardness and vulcanization behavior.

[0028] Rubbers

[0029] The rubber mixtures according to the invention contain at least one functionalized synthetic rubber, preferably selected from the group consisting of polar and non-polar functionalized synthetic rubbers.

[0030] In the context of the present invention, functionalized synthetic rubber is understood to mean a synthetic rubber which is substituted on the main chain and / or on the end groups by one or more functional groups, preferably selected from carboxyl groups, mercaptan groups, alkoxysilane groups, siloxane groups, hydroxyl groups, ethoxy groups, epoxy groups, amino groups, phthalocyanine groups, silane sulfide groups and metal atom-containing groups, particularly preferably selected from mercaptan groups, alkoxysilane groups and hydroxyl groups, very particularly preferably selected from mercaptan groups and alkoxysilane groups.

[0031] Preferred polar and non-polar functionalized synthetic rubbers are functionalized

[0032] BR - Polybutadien

[0033] ABR - Butadiene / acrylic acid C1-C4-alkyl ester copolymer

[0034] CR - Polychloroprene

[0035] IR - Polyisoprene

[0036] SBR - styrene / butadiene copolymers with styrene contents of 1 - 60, preferably 20-50 wt.%

[0037] IIR - Isobutylene / isoprene copolymers

[0038] NBR - butadiene / acrylonitrile copolymers with acrylonitrile contents of 5-60, preferably 10-50 wt.%

[0039] HNBR - partially hydrogenated or fully hydrogenated NBR rubber

[0040] EPDM - ethylene / propylene / diene copolymers

[0041] SIBR - Styrene-Isoprene-Butadiene Rubber

[0042] ENR - Epoxidized natural rubber

[0043] SNBR - Acrylonitrile-styrene / butadiene rubber

[0044] HNBR - Hydrogenated acrylonitrile / butadiene rubber

[0045] XNBR - Carboxylated acrylonitrile / butadiene rubber

[0046] HXNBR - Hydrogenated carboxylated acrylonitrile / butadiene rubber. Preferably, the at least one functionalized synthetic rubber is selected from the group consisting of functionalized SBR, functionalized BR and functionalized IR rubber, particularly preferably from functionalized SBR and functionalized BR rubber.

[0047] The rubber mixtures according to the invention preferably contain at least one functionalized SBR rubber and / or one functionalized BR rubber, particularly preferably at least one functionalized SBR and at least one functionalized BR rubber.

[0048] Preferably, the at least one functionalized SBR rubber is substituted on the main chain and / or at the end groups by one or more functional groups, in particular selected from mercaptan groups, alkoxysilane groups, and hydroxyl groups, particularly preferably by several functional groups that are mercaptan groups and alkoxysilane groups. Preferably, the at least one functionalized SBR rubber is SPRINTAN® SLR 3402 from Trinseo.

[0049] The functionalized SBR rubber can be solution-polymerized styrene-butadiene rubber (SSBR) or emulsion-polymerized styrene-butadiene rubber (ESBR), whereby a mixture of at least one functionalized SSBR and at least one functionalized ESBR can also be used.

[0050] The molecular weight (Mw) of the styrene-butadiene copolymers can vary over a wide range. Styrene-butadiene copolymers with an Mw of 250,000 to 600,000 g / mol are preferred, and those with an Mw of 350,000 to 500,000 g / mol are particularly preferred.

[0051] Preferably, the at least one functionalized BR rubber is substituted on the main chain and / or at the end groups by one or more functional groups selected from mercaptan groups, alkoxysilane groups, and hydroxyl groups, particularly preferably by alkoxysilane groups. Preferably, the at least one functionalized BR rubber is NIPOL® BR 1261 from Zeon.

[0052] The molecular weight of butadiene polymers can vary over a wide range. Butadiene polymers with a molecular weight of 250,000 to 5,000,000 g / mol are preferred.

[0053] Polybutadiene with a cis content greater than or equal to 90 wt. % is referred to as high-cis type, and polybutadiene with a cis content less than 90 wt. % is referred to as low-cis type. An example of a low-cis polybutadiene is Li-BR (lithium-catalyzed butadiene rubber) with a cis content of 20 to 50 wt. %. Within the scope of the present invention, a high-cis type of functionalized BR rubber is preferred. The rubber mixtures according to the invention contain 50 to 100 phr of at least one functionalized synthetic rubber, preferably 70-100 phr.

[0054] The rubber mixtures according to the invention preferably contain at least one functionalized SBR and at least one functionalized 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 30:70, very particularly preferably of 80:20 to 50:50.

[0055] In addition to the above-mentioned functionalized synthetic rubbers, the rubber mixtures according to the invention can also contain at least one unfunctionalized synthetic rubber and / or at least one natural rubber. The above statements for the functionalized synthetic rubbers apply, with the difference that in the case of unfunctionalized synthetic rubbers, these are not functionalized.

[0056] The rubber mixtures according to the invention can contain 0 to 50 phr of at least one unfunctionalized synthetic rubber and / or at least one natural rubber, preferably 0-30 phr.

[0057] Ethoxylated compound of formula (I)

[0058] The rubber mixtures according to the invention contain at least one ethoxylated compound of the formula (I)

[0059] RO(CH2CH2O)XH (I) where

[0060] R is alkyl, where alkyl can be branched or unbranched, and x is a rational number from 1 to 25.

[0061] R preferably represents C1-C20-alkyl, particularly preferably C5-C17-alkyl, very particularly preferably C10-C15-alkyl, very particularly preferably C15-C13-alkyl, most preferably C15-C13H27.

[0062] Preferably, x represents a rational number from 2 to 22, particularly preferably from 4 to 20.

[0063] At least one ethoxylated compound of formula (I) is contained, for example, in MARLIPAL® O 13 / 50 from Sasol.

[0064] 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 20.0 phr, preferably from 1.0 to 15.0 phr, particularly preferably from 2.0 to 12.0 phr and very particularly preferably from 4.0 to 11.0 phr. Fillers

[0065] The at least one hydroxyl-containing oxidic filler is preferably selected from the group consisting of silicic acids, synthetic silicates and natural silicates.

[0066] The content of hydroxyl-containing oxidic fillers in the rubber mixtures according to the invention is 0.1 to 250 phr, preferably 20 to 200 phr, particularly preferably 25 to 180 phr and very particularly preferably 30 to 160 phr.

[0067] Oxidic fillers containing hydroxyl groups are preferably those from the series of

[0068] - 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,

[0069] - 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

[0070] - natural silicates, such as kaolin and other naturally occurring silicas, as well as mixtures thereof.

[0071] 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).

[0072] The silicas are preferably obtainable by precipitation of solutions of silicates or flame hydrolysis of silicon halides.

[0073] 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 250 phr, preferably 20 to 200 phr, particularly preferably 25 to 180 phr, most preferably 30 - 160 phr.

[0074] The rubber mixtures according to the invention can contain at least one carbon black as a filler. In a preferred embodiment, the rubber mixtures according to the invention contain at least one carbon black as a filler. 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, and most preferably 2 to 40 phr.

[0075] 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 .

[0076] 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. The rubber mixtures according to the invention very particularly preferably contain, as fillers, 25 to 180 phr, preferably 30 to 160 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.

[0077] The total amount of carbon black and silica-based fillers in the rubber mixture according to the invention is preferably 26 to 250 phr, particularly preferably 32 to 200.

[0078] Crosslinkers and vulcanization accelerators

[0079] The rubber mixtures according to the invention may contain one or more crosslinking agents.

[0080] The rubber mixtures according to the invention preferably contain at least one crosslinker from the group consisting of sulfur and sulfur donors.

[0081] Sulfur can be used in elemental, soluble, or insoluble form. The rubber mixtures according to the invention particularly preferably contain at least one sulfur donor and / or sulfur, most preferably sulfur.

[0082] 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).

[0083] The rubber mixtures according to the invention generally contain 0.1 to 20 phr, preferably 0.5 to 10 phr, particularly preferably from 1.0 to 8 phr and most preferably 1 to 4 phr of at least one crosslinker from the group consisting of sulfur and sulfur donors.

[0084] Zinc oxide may be present in the rubber mixtures according to the invention. It acts as a complexing agent for sulfur and sulfur donor, thus facilitating the binding of the sulfur to the rubber matrix. Preferred rubber mixtures according to the invention contain zinc oxide with a BET surface area of ​​2 to 100 m². 2 / g, preferably 2 to 70 m 2 / g. BET surface areas of zinc oxide can be measured according to DIN ISO 9277.

[0085] 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.

[0086] The rubber mixtures according to the invention may contain one or more vulcanization accelerators.

[0087] The rubber mixtures according to the invention preferably contain at least one vulcanization accelerator, particularly preferably from the group of mercapto-benzothiazoles, 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).

[0088] 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.

[0089] The rubber mixtures according to the invention preferably contain at least one crosslinker and at least one vulcanization accelerator.

[0090] 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 Nature: 95-33-0).

[0091] 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 sulfenamides, very particularly preferably N-cyclohexylbenzothiazole-2-sulfenamides (CAS No.: 95-33-0), and zinc oxide. 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.

[0092] Reinforcing additives

[0093] The rubber mixtures according to the invention may contain one or more reinforcing additives.

[0094] 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.

[0095] 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.

[0096] Liquid sulfur-containing silanes can be coated on a carrier (dry liquid) for improved metering 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.

[0097] 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.

[0098] Rubber auxiliaries

[0099] 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.

[0100] 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.

[0101] The rubber mixtures according to the invention may contain one or more anti-aging agents. Suitable anti-aging agents are amine-based agents such as diaryl-p-phenylenediamines (DTPD), octylated diphenylamine (ODPA), phenyl-α-naphthylamine (PAN), phenyl-β-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-dimethylpentyl-N'-phenyl-p-phenylenediamine

[0102] (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).

[0103] 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, as processing aids, all lubricants customary for processing plastics, such as hydrocarbons, such as oils, e.g., aromatic process 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, aromatically modified cycloaliphatic hydrocarbon resins, 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.

[0104] 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.

[0105] Prior to crosslinking, further plastics can also be added to the rubber mixtures according to the invention, which act, for example, as polymeric processing aids or impact modifiers. These plastics are preferably selected from the group consisting of homopolymers 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-

[0106] Butyl methacrylate copolymers, ethylene-vinyl acetate copolymers, chlorinated polyethylene, ethylene-propylene copolymers, and ethylene-propylene-diene copolymers are particularly preferred. Known adhesives based on resorcinol, formaldehyde, and silica, the so-called RFS direct adhesion systems, are 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] Particularly preferred rubber mixtures according to the invention are those containing

[0111] - 70 to 100 phr of at least one functionalized synthetic rubber, preferably a functionalized BR rubber and / or functionalized SBR rubber,

[0112] - 0 to 30 phr of at least one natural rubber and / or unfunctionalized synthetic rubber,

[0113] - 20 to 200 phr of at least one hydroxyl-containing oxidic filler,

[0114] - 0.1 to 120 phr of at least one carbon black, preferably 0.1 to 100 phr,

[0115] - 0.5 to 10 phr of at least one crosslinker, preferably selected from the group of sulphur donors and / or sulphur,

[0116] - 0.1 to 10 phr zinc oxide,

[0117] - 0.5 to 10 phr of at least one vulcanization accelerator, in particular from the sulfenamide series,

[0118] - 0.1 to 10.0 phr of at least one secondary accelerator,

[0119] - 0.5 to 15 phr of at least one reinforcing additive, in particular from the group of sulphur-containing silanes,

[0120] - 0.1 to 30 phr rubber additives and

[0121] - 1 to 15 phr of at least one ethoxylated compound of formula (I).

[0122] The above-mentioned further preferred ranges for the individual components also apply to these preferred mixtures. Process for producing the rubber mixtures

[0123] A further subject of the present invention is 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 functionalized synthetic rubber, optionally at least one natural rubber and / or unfunctionalized synthetic rubber, and at least one ethoxylated compound of formula (I) are mixed together in the presence of at least one filler, at least one crosslinker, optionally at least one carbon black, 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 130 to 180°C, particularly preferably from 140 to 170°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 .

[0125] The rubber mixtures according to the invention are preferably produced in a three-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, preferably anti-aging agents and secondary accelerators, are incorporated into the rubber in an internal mixer (kneader).

[0126] Mixing temperatures in the internal mixer can reach values ​​of up to 180°C. The mixing temperature in the internal mixer is preferably 130 to 180°C, particularly preferably 140 to 170°C.

[0127] The second step is preferably the so-called post-tweezing, preferably at 130-180°C, particularly preferably at 160°C. Post-tweezing can be carried out, for example, in an internal mixer.

[0128] In a third mixing stage, crosslinkers, vulcanization accelerators, and optionally other rubber auxiliaries mentioned above, preferably secondary accelerators and zinc oxide, are added to the mixture obtained from the first mixing stage. The mixing temperature in the second mixing stage is preferably 50-130°C, more preferably 55-130°C, in particular from 60 to 120°C.

[0129] The addition of the at least one ethoxylated compound of formula (I) can take place at any time during the mixing process, preferably in the first step of the mixing process at a temperature in the range from 130°C to 180°C, more preferably at a temperature of 140 to 170°C. 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 support, preferably a support selected from the group comprising 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.

[0133] 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.

[0134] 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.

[0135] Formaldehyde can be present in the adhesives in the form of formaldehyde donors. Suitable formaldehyde donors include hexamethylenetetramine and methylolamine derivatives.

[0136] 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.

[0137] Process for producing rubber vulcanizates

[0138] 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.

[0139] 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.

[0140] The present invention further relates to rubber vulcanizates obtainable by vulcanizing the rubber mixtures according to the invention. The rubber vulcanizates according to the invention exhibit unexpectedly low rolling resistance, particularly when used in tires, while maintaining comparable performance characteristics. In the context of this invention, rolling resistance is determined using the loss factor tan δ at 60°C according to dynamic damping DIN EN ISO 6721-1.

[0141] molded body

[0142] 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.

[0143] Preferred molded articles are tires and tire parts containing a rubber vulcanizate according to the invention.

[0144] use

[0145] The present invention further relates to the use of the at least one ethoxylated compound of the formula (I), in particular in an amount of 0.5 to 20 phr, particularly preferably 1.0 to 15.0 phr, and of the at least one functionalized synthetic rubber, in particular in an amount of 50-100 phr, particularly preferably 70-100 phr, for producing vulcanizates with low rolling resistance from sulfur-crosslinkable rubber mixtures, 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) and the at least one synthetic rubber in rubber mixtures, vulcanizates and moldings obtainable therefrom for reducing the rolling resistance of moldings made of 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 functionalized synthetic rubber, the at least one natural rubber, the at least one unfunctionalized synthetic 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 given descriptions and preferred areas also apply to, among others, the rubber mixtures, vulcanizates, moldings, adhesive mixtures, processes and uses according to the invention, regardless of whether they are used for the aforementioned in the plural (e.g.

[0149] rubber compounds) or in the singular (e.g. rubber compound).

[0150] The invention will be explained with reference to the following examples, but is not limited thereto.

[0151] Implementation examples

[0152] Table 1 : List of ingredients, abbreviations and manufacturers the rubber vulcanizates

[0153] The rubber mixtures of the non-inventive reference mixture were prepared based on EP2858831 A1, which represents a classic SBR- and BR-containing rubber mixture, as well as of the inventive examples 1 and 2 according to the recipes given in Table 2. The difference between the inventive examples and the reference mixture is that, in addition to the functionalized synthetic rubbers, they also contain MARLIPAL® O 13 / 50 and thus an ethoxylated compound of the formula (I).

[0154] The rubber compounds were produced in the following steps:

[0155] 1. Mixing stage:

[0156] ■ NIPOL® BR1261 and SPRINTAN® SLR 3402 are placed in an internal mixer and mixed for approximately 30 seconds

[0157] ■ Add the anti-aging agents VULKANOX® 4020 and VULKANOX® HS and mix for approx. 30 s

[0158] ■ Add half of ZEOSIL 1 165MP and mix Sl® 75 for about 60 seconds

[0159] ■ Add half of ZEOSIL 1 165MP, CORAX® N 234, as well as PALMERA® A9818, Vivatec 500, Escorez 5600, RHENOGRAN® DPG-80, and MARLIPAL® O 13 / 50. Mix for approximately 60 seconds, then sweep. Mix until a temperature of 160 °C is reached, then mix for 4 minutes at 160 °C.

[0160] After the first mixing stage, the mixed material is taken up by a downstream rolling mill and formed into a sheet, strip, or pellet. It is then stored at room temperature for 24 hours. Processing temperatures are 70°C.

[0161] 2nd mixing stage:

[0162] Afterwards, mixing took place in an internal mixer until a temperature of 160°C was reached (the so-called post-tweezing).

[0163] After completion of the second 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.

[0164] 3. Mixing stage:

[0165] The addition of additives such as sulfur, zinc oxide and Rhenogran®-CBS-80 took place in the internal mixer for 2 minutes at 100 °C.

[0166] After the third mixing stage, the mixed piece is formed into a sheet, strip, or pellet using a rolling mill and stored at room temperature for 24 hours. Processing temperatures are 70°C.

[0167] The inventive rubber mixtures 1 and 2 showed no specks on the surface, so it is assumed that the additives used were well mixed. Table 2: Rubber formulations (data in phr)

[0168] Technical inspection

[0169] The vulcanizates produced at 160°C from the rubber compounds of Examples 1 and 2, as well as from the reference compound, were subjected to the technical tests specified below. The determined values ​​are shown in Table 3.

[0170] Very good properties of the rubber compounds or their vulcanizates were achieved if their property values ​​were within the specified “preferred range”.

[0171] The following test procedures were used for the tests on test specimens:

[0172] Mooney viscosity measurement

[0173] The determination was carried out using a shear disk viscometer according to ASTM D 1646. Viscosity can be determined directly from the force that rubber (and rubber compounds) exert during processing. In the Mooney shear disk viscometer, a ribbed disk is enclosed at the top and bottom with sample substance and rotated in a heated chamber at approximately two revolutions per minute. The force required for this is measured as torque and corresponds to the respective viscosity. The sample is usually preheated to 100°C for one minute; the measurement lasts a further four minutes, during which the temperature is kept constant. The viscosity is specified together with the respective test conditions, for example, ML (1 + 4) 100°C (Mooney viscosity, rotor size L, preheating time and test time in minutes, test temperature). The rheometer (vulcameter) used and the curing / vulcanization time

[0174] The vulcanization process on the MDR (moving die rheometer) and its analytical data were measured on a Monsanto rheometer MDR 2000 according to ASTM D5289-95.

[0175] The scorch time (t5) is determined as the time required for 5% of the rubber to cure. The temperature chosen was 160°C.

[0176] The curing time (t95) is determined as the time required for 95% of the rubber to cure. The temperature chosen was 160°C.

[0177] The value of Delta S' is calculated from the difference between the highest and the lowest value of the rheometer curve, i.e. Smax - Smin.

[0178] Determination of elongation at break, tensile strength, modulus 300

[0179] These measurements were carried out according to DIN 53504 (tensile test, bar S2, 5-fold measurement).

[0180] Determination of Shore A hardness

[0181] Measurement of Shore hardness (Shore A) according to DIN 53505 at 23 °C (triple measurement).

[0182] Rebound resilience

[0183] Measurement of rebound resilience at 23 °C (triple measurement) according to DIN 53512.

[0184] Determination of DIN abrasion

[0185] The simplest method for determining abrasive wear is the so-called DIN abrasion test according to ASTM D5963. The test specimen made of the elastomer to be tested is moved under a constant contact force and at a constant speed (40 min-1) over a specified friction distance (40 m) over a test emery sheet mounted on a rotating cylinder. The material loss is then measured in mm. 3 certainly.

[0186] Determination of the loss factor

[0187] The loss factor tan ö was determined at 60°C and a measuring frequency of 10 Hz according to dynamic damping DIN EN ISO 6721 -1.

[0188] Table 3: Test values

[0189] Conclusion:

[0190] Surprisingly, it was found that with the rubber mixtures according to the invention according to Examples 1 and 2, a shorter vulcanization time (t95), a longer scorching time (t5) and a significantly lower loss factor tan δ at 60°C as well as significantly lower DIN abrasion are achieved compared to the non-inventive rubber mixture reference, with the same or improved other mechanical properties.

Claims

1. Rubber compound containing - 50 to 100 phr of at least one functionalized synthetic rubber, preferably one functionalized BR rubber and / or functionalized SBR rubber, - 0 to 50 phr of at least one natural rubber and / or unfunctionalized synthetic rubber, - 0.1 to 250 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 stands for alkyl, where alkyl can be branched or unbranched, and x stands for a rational number from 1 to 25.

2. Rubber compound according to claim 1, characterized in that R stands for Ci-C2o-alkyl, preferably for Cs-Ci7-alkyl, particularly preferably for Cio-Cis-alkyl, very particularly preferably for / so-Ci3-alkyl, very, very preferably for / so-Ci3H27.

3. Rubber compound according to one of claims 1 or 2, characterized in that x represents a rational number from 2 to 22, preferably from 4 to 20.

4. Rubber compound according to one of claims 1-3, characterized in that the at least one functionalized synthetic rubber is selected from the group consisting of functionalized SBR, functionalized BR and functionalized IR rubber, preferably functionalized SBR and functionalized BR rubber.

5. Rubber compound according to one of claims 1-4, characterized in that the at least one functionalized synthetic rubber is substituted at the main chain and / or at the end groups by one or more functional groups selected from carboxyl groups, mercaptan groups, alkoxysilane groups, siloxane groups, hydroxy groups, ethoxy groups, epoxy groups, amino groups, phthalocyanine groups, silane sulfide groups and metal atom-containing groups, preferably selected from mercaptan groups, alkoxysilane groups and hydroxy groups, particularly preferably selected from mercaptan groups and alkoxysilane groups.

6. Rubber compound according to one of claims 1-5, 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 contained in the rubber mixture in an amount of 0.1 to 250 phr, preferably 20 to 200 phr, particularly preferably 25 to 180 phr, most preferably 30 to 160 phr.

7. Rubber compound according to one of claims 1-6, characterized in that it contains 0.5 to 10 phr, preferably 1.0 to 8 phr and particularly preferably 1 to 4 phr of the at least one crosslinking agent from the group consisting of sulfur and sulfur donor.

8. Rubber compound according to one of claims 1-7, characterized in that it contains at least one reinforcing additive from the series of sulfur-containing organic silanes, in particular the alkoxysilyl group-containing sulfur-containing silanes and especially preferably the trialkoxysilyl group-containing sulfur-containing organic silanes.

9. Rubber compound according to claim 1, characterized in that it - 70 to 100 phr of at least one functionalized synthetic rubber, preferably one functionalized BR rubber and / or functionalized SBR rubber, - 0 to 30 phr of at least one natural rubber and / or unfunctionalized synthetic rubber, - 20 to 200 phr of at least one hydroxyl-containing oxide filler, - 0.1 to 120 phr of at least one carbon black, preferably 0.1 to 100 phr, - 0.5 to 10 phr of at least one crosslinking agent, preferably selected from the range 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 - 1 to 15 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.

1. Use of the rubber compounds according to 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. Vulcanizate obtained by vulcanizing at least one rubber compound according to any one of claims 1-9, preferably at a temperature of 120 to 200°C. Vehicle tire, characterized in that it comprises at least one vulcanizate according to claim 12. Use of the at least one ethoxylated compound of formula (I) RO(CH2CH2O)XH (I) wherein R represents alkyl, wherein alkyl may be branched or unbranched, and x represents a rational number from 1 to 25, particularly in an amount of 0.5 to 20 phr, especially preferably from 1.0 to 15.0 phr, and of at least one functionalized synthetic rubber, particularly in an amount of 50-100 phr, especially preferably from 70-100 phr, for the production of vulcanizates with low rolling resistance from sulfur-curing rubber mixtures at a vulcanization temperature of 120 to 200°C. Adhesive mixture comprising at least one rubber mixture according to any one of claims 1 to 9 and at least one adhesive based on resorcinol, formaldehyde, and silica.

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