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

Abstract

The invention relates to rubber mixtures containing, 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 at least one ethoxylated compound of formula (I): RO (CH2CH2O) xH (I), where R represents an alkyl group, where the alkyl group may be branched or unbranched, and x represents a rational number from 1 to 25, where x represents an alkyl group, where the alkyl group may be branched or unbranched, and x represents a rational number from 1 to 25. These rubber mixtures are suitable for producing cured products with low rolling resistance.

Description

Technical Field

[0001] The present invention relates to novel rubber mixtures containing at least one functionalized synthetic rubber and at least one ethoxylated compound of formula (I), to a process for their production, to their use for producing rubber vulcanizates, to the corresponding vulcanizates, and to the use of the at least one functionalized synthetic rubber and the at least one ethoxylated compound of formula (I) in rubber mixtures, vulcanizates obtainable therefrom and shaped articles for reducing the rolling resistance of shaped articles, preferably tires, containing these vulcanizates. Background Art

[0002] The EU is obliged to reduce greenhouse gas emissions in order to achieve climate neutrality by 2050. Reducing CO2 emissions from road traffic plays an important role in achieving these goals.

[0003] The new EU tyre labelling system, which comes into force on 1 May 2021, is based on three important tyre characteristics: rolling resistance (and therefore fuel efficiency), wet grip and external rolling noise. The new EU tyre labelling will enable consumers to proactively choose more fuel efficient tyres.

[0004] More fuel-efficient tires contribute to reducing emissions in road traffic. Depending on the rolling resistance of the tire, fuel efficiency ranges from class A (optimal fuel efficiency) to class E. Fuel consumption is important from both an economic and an environmental point of view. Low fuel consumption has a positive effect on the CO2 balance of a vehicle, especially for heavy commercial vehicles.

[0005] Against this backdrop, tire manufacturers are looking for economical ways to achieve Class A fuel efficiency targets for tires.

[0006] The use of rubber mixtures containing silica for the production of passenger car tire treads is known. Silica contributes to a good combination of properties, including rolling resistance, wet grip and wear, as required for passenger car tire treads. In order to achieve the desired combination of properties, the silica must be efficiently dispersed in the rubber mixture and optimally coupled to the rubber matrix during curing.

[0007] In order to improve the processability of silica-containing rubber mixtures, further additives may be used, such as, for example, fatty acid esters, fatty acid salts or mineral oils. The above-mentioned additives have the following disadvantages: they increase fluidity but at the same time reduce the stress values ​​at higher elongations (e.g., 100% to 300%), or reduce the hardness of the cured product, thereby adversely affecting the reinforcing effect of the filler. However, insufficient hardness or stiffness of the cured product leads to insufficient driving characteristics of the tire, especially during cornering. In addition, too low a hardness leads to increased wear of the cured product by the road and, therefore, to an increased proportion of so-called "microplastics" in the environment. Tire wear particles are the main source of microplastics in rivers and lakes and account for about 28% of plastic particles in the ocean.

[0008] The loss factor tan δ provides an important indication for assessing the 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°C to 70°C; according to US 9783658 B2, <0.2 and according to EP 2858831 A2, <0.12.

[0009] EP 2858831A2 discloses a rubber mixture containing 1 phr of 1,6-bis(N,N-dibenzylthiocarbamoyldisulfide)hexane (CAS number: 151900-44-6) and 1 phr of some sulfur-containing additives to produce a cured product with good dynamic characteristics, good hardness / rigidity, good rolling resistance and low wear. The disadvantage is that the scorch time (t5) during the curing of the rubber mixture is significantly reduced, 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 several mixture 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 organosilicon polysulfide reduces the loss factor (tan δ at 60°C) by more than 10%. Mechanical properties such as tensile strength, elongation at break and 300 modulus remain almost unchanged. Here, there is also the disadvantage that the scorch time is greatly reduced by adding organosilicon polysulfide. Summary of the invention

[0011] The object of the present invention is therefore to provide improved rubber mixtures based on hydroxyl-containing oxidic fillers which overcome the above-mentioned disadvantages and produce cured products and shaped articles produced therefrom, such as tire treads having low rolling resistance measured by the loss factor tan δ at 60° C., preferably at a measuring frequency of 10 Hz, and unchanged or improved properties such as 300 modulus, elongation at break and hardness. The improved rubber mixtures should also preferably have a reduced full cure time (t95). The improved rubber compounds should also preferably produce cured products having lower DIN wear and thus being more environmentally friendly.

[0012] The low loss factor tan δ determined by DIN EN ISO 6721-1 dynamic damping at 60° C., preferably at a measuring frequency of 10 Hz, is preferably less than 0.2, particularly preferably less than 0.12.

[0013] The scorch time t5 determined at 160° C. in accordance with ASTM D5289-95 is preferably in the range of 70 to 150 seconds, particularly preferably in the range of 85 to 140 seconds.

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

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

[0016] High 300 modulus values ​​are also advantageous for cured products, in particular for tire treads. The 300 modulus (determined in accordance with DIN 53504) is preferably 8-20 MPa, particularly preferably 9.5-20 MPa.

[0017] The hardness determined in accordance with DIN 53505 should preferably be in the range of 55-70 Shore A.

[0018] The DIN wear determined according to ASTM D5963 should preferably be low and particularly preferably less than 120 mm 3 , very particularly preferably less than 110 mm 3 .

[0019] Hereinafter, the unit "phr" represents parts by weight based on 100 parts by weight of the total amount of rubber present in the rubber mixture (ie the total amount of one or more functionalized and unfunctionalized synthetic rubbers and one or more natural rubbers).

[0020] The above objects are surprisingly achieved by the rubber mixture according to the invention, which contains

[0021] - 50 to 100 phr of at least one functionalized synthetic rubber, preferably a functionalized BR rubber and / or a 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, preferably 0.1 to 100 phr, of at least one carbon black,

[0025] - 0.1 to 20 phr of at least one crosslinking agent, preferably chosen from the group of sulfur donors and / or sulfur, and

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

[0027] RO(CH2CH2O) x H(I),

[0028] in

[0029] R represents an alkyl group, wherein the alkyl group may be branched or unbranched,

[0030] and

[0031] x represents a rational number from 1 to 25.

[0032] The cured products according to the invention obtained by curing the rubber mixtures according to the invention are surprisingly characterized by a low loss factor tan δ at 60° C. and an improved 300 modulus as well as a reduced Mooney viscosity, a short through cure time (t95) and a sufficiently long scorch time (t5), while retaining the same good performance characteristics, such as elongation at break, hardness and cure characteristics.

[0033] rubber

[0034] The rubber mixture according to the invention contains at least one functionalized synthetic rubber, preferably selected from the group consisting of polar and nonpolar functionalized synthetic rubbers.

[0035] In the context of the present invention, functionalized synthetic rubbers are understood to mean synthetic rubbers which are substituted in the main chain and / or at the end groups by one or more functional groups, these functional groups being preferably selected from carboxyl groups, thiol groups, alkoxysilane groups, siloxane groups, hydroxyl groups, ethoxy groups, epoxy groups, amino groups, phthalocyanine groups, silane-thioether groups and groups containing metal atoms, particularly preferably from thiol groups, alkoxysilane groups and hydroxyl groups, very particularly preferably from thiol groups and alkoxysilane groups.

[0036] Preferred polar and nonpolar functionalized synthetic rubbers are functionalized BR-Polybutadiene

[0037] ABR-Butadiene / C1-C4-alkyl acrylate copolymer

[0038] CR-Polychloroprene

[0039] IR-polyisoprene

[0040] SBR - styrene / butadiene copolymer, with a styrene content of 1% to 60%, preferably 20% to 50% by weight

[0041] IIR-isobutylene / isoprene copolymer

[0042] NBR - butadiene / acrylonitrile copolymer, having an acrylonitrile content of 5% to 60%, preferably 10% to 50%, by weight,

[0043] HNBR - partially or fully hydrogenated NBR rubber

[0044] EPDM-ethylene / propylene / diene copolymer

[0045] SIBR - Styrene-isoprene-butadiene rubber

[0046] ENR-Epoxidized Natural Rubber

[0047] SNBR-Acrylonitrile-Styrene / Butadiene Rubber

[0048] HNBR-Hydrogenated Acrylonitrile / Butadiene Rubber

[0049] XNBR-Carboxylated acrylonitrile / butadiene rubber

[0050] HXNBR-Hydrogenated Carboxylated Acrylonitrile / Butadiene Rubber

[0051] The at least one functionalized synthetic rubber is preferably selected from the group consisting of functionalized SBR rubbers, functionalized BR rubbers and functionalized IR rubbers, particularly preferably selected from functionalized SBR rubbers and functionalized BR rubbers.

[0052] It is preferred when the rubber mixture according to the invention contains at least one functionalized SBR rubber and / or a functionalized BR rubber, particularly preferably at least one functionalized SBR rubber and at least one functionalized BR rubber.

[0053] It is preferred when at least one functionalized SBR rubber is substituted in the main chain and / or at the end groups with one or more functional groups, in particular selected from thiol groups, alkoxysilane groups and hydroxyl groups, particularly preferably with two or more functional groups, which are thiol groups and alkoxysilane groups. SLR 3402 is preferred.

[0054] The functionalized SBR rubber may be a solution-polymerized styrene-butadiene rubber (SSBR) or an emulsion-polymerized styrene-butadiene rubber (ESBR), wherein it is also possible to use a mixture of at least one functionalized SSBR and at least one functionalized ESBR.

[0055] The molar weight (Mw) of the styrene-butadiene copolymers can vary within wide ranges. Preference is given to styrene-butadiene copolymers having an Mw of 250,000 to 600,000 g / mol, particularly preferably having an Mw of 350,000 to 500,000 g / mol.

[0056] At least one functionalized BR rubber is preferably substituted in the main chain and / or at the end groups with one or more functional groups selected from thiol groups, alkoxysilane groups and hydroxyl groups, particularly preferably with alkoxysilane groups. At least one functionalized BR rubber is preferably from Zeon BR 1261.

[0057] The molar weight of the butadiene polymer can vary within wide ranges. Preference is given to butadiene polymers having an Mw of from 250,000 to 500,000 g / mol.

[0058] Polybutadiene having a cis content of not less than 90% by weight is referred to as high cis, and polybutadiene having a cis content of less than 90% by weight is referred to as low cis. An example of a low cis polybutadiene is Li-BR (lithium catalyzed butadiene rubber) having a cis content of 20 to 50% by weight. In the context of the present invention, high cis functionalized BR rubbers are preferred.

[0059] The rubber mixture according to the invention contains 50 to 100 phr, preferably 70-100 phr, of at least one functionalized synthetic rubber.

[0060] The rubber mixture according to the invention preferably contains 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 90:10 to 10:90, very particularly preferably 90:10 to 30:70, very very particularly preferably 80:20 to 50:50.

[0061] Except above-mentioned functionalized synthetic rubber, rubber mixture of the present invention can also contain at least one unfunctionalized synthetic rubber and / or at least one natural rubber.Except when unfunctionalized synthetic rubber, described rubber is not functionalized, the above-mentioned embodiment of functionalized synthetic rubber is also applicable.

[0062] The rubber mixtures of the invention may contain 0 to 50 phr, preferably 0-30 phr, of at least one unfunctionalized synthetic rubber and / or at least one natural rubber.

[0063] Ethoxylated compounds having formula (I)

[0064] The rubber mixture according to the invention contains at least one ethoxylated compound of the formula (I)

[0065] RO(CH2CH2O) x H(I),

[0066] in

[0067] R represents an alkyl group, wherein the alkyl group may be branched or unbranched,

[0068] and

[0069] x represents a rational number from 1 to 20.

[0070] R preferably represents C1-C 20 -alkyl, particularly preferably C5-C 17 -alkyl, very particularly preferably C 10 -C 15 -alkyl, very particularly preferably iso-C 13 -alkyl, most preferably iso-C 13 H 27 .

[0071] x preferably represents a rational number from 2 to 22, particularly preferably from 4 to 20.

[0072] At least one ethoxylated compound of formula (I) is present, for example, in the O 13 / 50 / Medium.

[0073] The rubber mixtures according to the invention generally contain at least one ethoxylated compound of the formula (I) in an amount of 0.5 to 20.0 phr, preferably 1.0 to 15.0 phr, particularly preferably 2.0 to 12.0 phr and very particularly preferably 4.0 to 11.0 phr.

[0074] filler

[0075] The at least one hydroxyl-containing oxidic filler is preferably selected from the group consisting of silicon dioxide, synthetic silicates and natural silicates.

[0076] The content of hydroxyl-containing oxidic fillers in the rubber mixture according to the invention is from 0.1 to 250 phr, preferably from 20 to 200 phr, particularly preferably from 25 to 180 phr and very particularly preferably from 30 to 160 phr.

[0077] Suitable hydroxyl-containing oxidic fillers are preferably those selected from the group consisting of

[0078] - in particular silicon dioxide having a specific surface area (BET) of 5 to 1000, preferably 20 to 400 m2 / g, preferably having a primary particle size of 100 to 400 nm, wherein the silicon dioxide may optionally also be present as a mixed oxide with other metal oxides (such as Al, Mg, Ca, Ba, Zr, Ti oxides),

[0079] - synthetic silicates, such as aluminum silicates, alkaline earth metal silicates (such as magnesium silicate or calcium silicate), having a specific surface area (BET) of 20 to 400 m2 / g, preferably having a primary particle size of 10 to 400 nm,

[0080] as well as

[0081] - natural silicates, such as kaolin and other naturally occurring silicas,

[0082] and mixtures thereof.

[0083] The above BET surface areas are determined in accordance with DIN ISO 9277. The indicated primary particle sizes are based on measurements made using an instrument for particle analysis using scattered light. The calculation of the particle size is based on the Mie theory, which describes the interaction between light and matter (DIN / ISO 13320).

[0084] It is preferred when the silicon dioxide is obtainable by precipitation from silicate solutions or by flame hydrolysis of silicon halides.

[0085] It is preferred when the rubber mixture according to the invention contains at least one hydroxyl-containing oxidic filler from the group of silicon dioxides, in particular having a specific surface area (BET) in the range of 5 to 1000, preferably 20 to 400 m2 / g, in an amount of 0.1 to 250 phr, preferably 20 to 200 phr, particularly preferably 25 to 180 phr, very particularly preferably 30-160 phr.

[0086] The rubber mixture according to the invention may contain at least one carbon black as filler.

[0087] In a preferred embodiment, the rubber mixture according to the invention contains at least one carbon black as filler.

[0088] The rubber mixtures of 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.

[0089] Preferably, it is obtainable by lamp black, furnace black or gas black process and has a density of 20 to 200 m 2 / g range, for example SAF, ISAF, IISAF, HAF, FEF or GPF carbon black. The rubber mixture of the present invention preferably contains at least one carbon black having a specific surface area (BET) in the range of 20 to 200 m / g. 2 / g range of carbon black with a specific surface area (BET).

[0090] It is preferred when the rubber mixture according to the invention contains at least one of the abovementioned silicas and at least one of the abovementioned carbon blacks as fillers.

[0091] It is very particularly preferred when the rubber mixture according to the invention contains 25 to 180 phr, preferably 30 to 160 phr, of at least one of the abovementioned silicas and 1.0 to 70 phr, preferably 2.0 to 40 phr, of at least one of the abovementioned carbon blacks as fillers.

[0092] The total amount of carbon black and silica-based filler in the rubber mixture according to the invention is preferably from 26 to 250 phr, particularly preferably from 32 to 200 phr.

[0093] Crosslinkers and curing accelerators

[0094] The rubber mixtures according to the invention may contain one or more crosslinking agents.

[0095] It is preferred when the rubber mixture according to the invention contains at least one crosslinking agent from the group of sulfur and sulfur donors.

[0096] Sulfur can be used in elementally soluble or insoluble form. It is particularly preferred when the rubber mixture according to the invention contains at least one sulfur donor and / or sulfur, very particularly preferably sulfur.

[0097] Examples of suitable sulfur donors include dimorpholinyl disulfide (DTDM), 2-morpholinobenzothiazole disulfide (MBSS), caprolactam disulfide, dipentamethylenethiuram tetrasulfide (DPTT), tetramethylthiuram disulfide (TMTD), and tetrabenzylthiuram disulfide (TBzTD).

[0098] The rubber mixture according to the invention generally contains 0.1 to 20 phr, preferably 0.5 to 10 phr, particularly preferably 1.0 to 8 phr and most preferably 1 to 4 phr of at least one crosslinking agent from the group of sulfur and sulfur donors.

[0099] The rubber mixture according to the invention may also contain zinc oxide. This is a complexing agent for sulfur and sulfur donors and thus simplifies the bonding of sulfur to the rubber matrix.

[0100] Preferred rubber mixtures according to the invention contain 2 to 100 m 2 / g, preferably 2 to 70m 2 The BET surface area of ​​zinc oxide can be measured in accordance with DIN ISO 9277.

[0101] Zinc oxide is generally present in the rubber mixture according to the invention in an amount of 0 to 20 phr, preferably 0.1 to 10 phr, particularly preferably 1 to 5 phr.

[0102] The rubber mixtures according to the invention may contain one or more vulcanization accelerators.

[0103] The rubber mixture according to the invention preferably contains at least one vulcanization accelerator, which is particularly preferably from the group of mercaptobenzothiazoles, thiocarbamates, dithiocarbamates, thiurams, thiazoles, sulfenamides, thiazolesulfenamides, xanthates, bicyclic 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).

[0104] The rubber mixtures of the invention generally comprise from 0.1 to 20 phr, preferably from 0.5 to 10 phr and more preferably from 1.0 to 5 phr of at least one of the vulcanization accelerators mentioned.

[0105] The rubber mixtures of the invention preferably contain at least one crosslinking agent and at least one vulcanization accelerator.

[0106] The rubber mixture of the invention particularly preferably contains at least one crosslinker from the group of sulfur and sulfur donors and at least one vulcanization accelerator from the group of mercaptobenzothiazoles, thiazolesulfenamides, thiurams, dithiocarbamates, xanthates and thiophosphates, particularly preferably from the group of sulfonamides, very particularly preferably N-cyclohexylbenzothiazolesulfenamide (CAS No.: 95-33-0).

[0107] The rubber mixture of the invention particularly preferably contains at least one crosslinking agent selected from the group consisting of sulfur and sulfur donors, at least one vulcanization accelerator selected from the group consisting of mercaptobenzothiazoles, thiazolesulfenamides, thiurams, dithiocarbamates, xanthates and thiophosphates, particularly preferably from the group of sulfenamides, very particularly preferably N-cyclohexylbenzothiazole-2-sulfenamide (CAS No.: 95-33-0) and zinc oxide.

[0108] The total amount of crosslinking agent and vulcanization accelerator in the rubber mixture is preferably 1.0 to 20 phr, particularly preferably 2.0 to 13 phr.

[0109] Enhancement Additives

[0110] The rubber mixtures according to the invention may contain one or more reinforcing additives.

[0111] The rubber mixture according to the invention preferably contains at least one reinforcing additive from the group of sulfur-containing organosilanes, in particular sulfur-containing silanes containing alkoxysilyl groups and very particularly preferably sulfur-containing organosilanes containing trialkoxysilyl groups.

[0112] It is particularly preferred when the rubber mixture according to the invention contains one or more sulfur-containing silanes from the group of bis(triethoxysilylpropyl)tetrasulfane, bis(triethoxysilylpropyl)disulfane and 3-(triethoxysilyl)-1-propanethiol.

[0113] For better meterability and / or dispersibility, the liquid sulfur-containing silane can be absorbed on a carrier (dry liquid). The content of the sulfur-containing silane 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.

[0114] The rubber mixtures of the invention generally contain from 0.1 to 20 phr, preferably from 0.5 to 15 phr and more preferably from 1.0 to 10 phr of at least one reinforcing additive.

[0115] Rubber additives

[0116] The rubber mixture according to the invention may further contain one or more rubber additives. Examples of suitable rubber additives include aging stabilizers, adhesives, heat stabilizers, light stabilizers, flame retardants, processing aids, impact modifiers, plasticizers, tackifiers, foaming agents, dyes, pigments, waxes, fillers, organic acids such as stearic acid, retardants, in particular triethanolamine, polyethylene glycol, hexanetriol, reversion stabilizers and auxiliary accelerators.

[0117] These rubber additives can be added to the rubber mixture according to the invention in the amounts customary for these additives and also guided by the final use of the cured product produced therefrom. The usual amounts are, for example, 0.1 to 30 phr.

[0118] The rubber mixtures according to the invention may contain one or more aging stabilizers. Suitable aging stabilizers are amine aging stabilizers, such as diaryl-p-phenylenediamine (DTPD), octylated diphenylamine (ODPA), phenyl-α-naphthylamine (PAN), phenyl-β-naphthylamine (PBN), preferably those based on phenylenediamine, such as N,N′-dicyclohexyl-p-phenylenediamine (CCPD), N-isopropyl-N′-phenyl-p-phenylenediamine, N-1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine (6PPD), N-1,4-dimethylpentyl-N′-phenyl-p-phenylenediamine (7PPD), N,N′-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), and phosphites such as tris(nonylphenyl) phosphite, polymerized 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), methyl-2-mercaptobenzimidazole (MMBI) and zinc methylmercaptobenzimidazole (ZMMBI) and mixtures thereof. It is particularly preferred when the at least one aging stabilizer is selected from the group consisting of N,N′-dicyclohexyl-p-phenylenediamine (CCPD) and N-1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine (6PPD).

[0119] Processing aids should be active between the rubber particles and should counteract frictional forces during mixing, plasticizing and shaping. Processing aids that may be present in the rubber mixture according to the invention include all lubricants commonly used in plastics processing, for example 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 acid, oxidized PE waxes, aromatic modified alicyclic hydrocarbon resins, metal salts of carboxylic acids, formamides and carboxylic acid esters, for example alcohols such as ethanol, fatty alcohols, glycerol, ethylene glycol, pentaerythritol and long-chain carboxylic acids as acidic components.

[0120] In order to reduce flammability and to reduce the emission of smoke during combustion, rubber mixture of the present invention can contain flame retardants. Examples of compounds for this purpose include antimony trioxide, phosphoric acid esters, chlorinated paraffins, aluminum hydroxide, boron compounds, zinc compounds (but except ZnO), molybdenum trioxide, ferrocene, calcium carbonate or magnesium carbonate.

[0121] It is also possible to add further plastics to the rubber mixture of the invention before crosslinking, which plastics serve, for example, as polymer 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 an alcohol component of branched or unbranched C1 to C10 alcohols, particularly preferably polyacrylates with identical or different alcohol groups from the group of C4 to C8 alcohols (especially butanol, hexanol, octanol and 2-ethylhexanol), polymethyl methacrylates, methyl methacrylate-butyl acrylate copolymers, methyl methacrylate-butyl methacrylate copolymers, ethylene-vinyl acetate copolymers, chlorinated polyethylene, ethylene-propylene copolymers, ethylene-propylene-diene copolymers.

[0122] Known adhesives are based on resorcinol, formaldehyde and silica, so-called RFS direct bonding systems. These direct bonding systems can be used in the rubber mixture according to the invention in any desired amount at any time of incorporation into the rubber mixture according to the invention.

[0123] In silica-based rubber mixtures, such as are preferably used in tire production, diphenylguanidine (DPG) or a structurally similar aromatic guanidine is typically employed as a secondary accelerator.

[0124] It is known to those skilled in the art that DPG may advantageously be referred to also under the trade name It is also possible to replace DPG with an auxiliary accelerator such as TBzTD (tetrabenzylthiuram disulfide) or dithiophosphates.

[0125] The rubber mixtures according to the invention generally contain from 0 or 0.1 to 10 phr, preferably from 0.5 to 5 phr, particularly preferably from 0.2 to 3.5 phr, of at least one of the auxiliary accelerators mentioned.

[0126] Particularly preferred is the rubber mixture of the present invention containing

[0127] - 70 to 100 phr of at least one functionalized synthetic rubber, preferably a functionalized BR rubber and / or a functionalized SBR rubber,

[0128] - 0 to 30 phr of at least one natural rubber and / or unfunctionalized synthetic rubber,

[0129] - 20 to 200 phr of at least one hydroxyl-containing oxidic filler,

[0130] - 0.1 to 120 phr, preferably 0.1 to 100 phr, of at least one carbon black,

[0131] - 0.5 to 10 phr of at least one crosslinking agent, preferably chosen from the group of sulfur donors and / or sulfur,

[0132] - 0.1 to 10 phr of zinc oxide,

[0133] - 0.5 to 10 phr of at least one curing accelerator, in particular from the group of sulfenamides,

[0134] - 0.1 to 10.0 phr of at least one auxiliary accelerator,

[0135] - 0.5 to 15 phr of at least one reinforcing additive, especially from the group of sulfur-containing silanes,

[0136] - 0.1 to 30 phr of rubber additives

[0137] as well as

[0138] - 1 to 15 phr of at least one ethoxylated compound of formula (I).

[0139] The abovementioned further preferred ranges for the individual components also apply to the preferred mixtures.

[0140] Method for producing a rubber mixture

[0141] The invention further provides a method for producing a rubber mixture according to the invention, characterized in that the corresponding components are mixed during the mixing process. This preferably comprises mixing 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) in the presence of at least one filler, at least one crosslinking agent, optionally at least one carbon black, optionally at least one curing accelerator, optionally zinc oxide, optionally at least one auxiliary accelerator, optionally at least one reinforcing additive and optionally one or more of the rubber auxiliaries mentioned in conjunction with each other, in the general and preferred amounts mentioned for these additives, at a temperature in the range of 130° C. to 180° C., particularly preferably 140° C. to 170° C.

[0142] The rubber mixtures of the invention are mixed in the usual manner in known mixing apparatuses such as rolls, internal mixers, downstream mixing roll mills and mixing extruders at a rate of 1 to 1000 sec. -1Shear rate production.

[0143] The production of rubber mixture according to the present invention is preferably carried out in a three-stage mixing process. In the first mixing stage, filler and at least one ethoxylated compound with formula (I) and optionally other above-mentioned rubber auxiliary agents, preferably aging stabilizer and auxiliary accelerator are initially mixed in the rubber in an internal mixer (kneader).

[0144] The mixing temperature in the internal mixer can reach values ​​of up to 180° C. The mixing temperature in the internal mixer is preferably from 130° C. to 180° C., particularly preferably from 140° C. to 170° C.

[0145] This is preferably followed as a second step by so-called post-mastication, preferably at 130° C. to 180° C., particularly preferably at 160° C. The post-mastication can be carried out, for example, in an internal mixer.

[0146] In the third mixing stage, a crosslinking agent, a curing accelerator and optionally additional rubber additives, preferably an auxiliary accelerator 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°C-130°C, preferably 55°C-130°C, in particular 60°C to 120°C.

[0147] The addition of the at least one ethoxylated compound of formula (I) can be carried out at any time during mixing, preferably in the first step of the mixing operation, at a temperature in the range of 130 to 180°C, preferably at a temperature of 140 to 170°C.

[0148] At least one ethoxylated compound of formula (I) can be employed in pure form or else absorbed and / or adsorbed during mixing on an inert, organic or inorganic support, preferably a support selected from the group containing natural or synthetic silicates (in particular neutral, acidic or basic silicon dioxide), aluminum oxide, carbon black or zinc oxide.

[0149] Adhesive compound

[0150] The invention further provides an adhesive mixture containing the rubber mixture according to the invention and at least one adhesive.

[0151] The adhesive mixture according to the invention preferably contains at least one adhesive based on resorcinol, formaldehyde and silicon dioxide.

[0152] The combination of resorcinol, formaldehyde and silica is known in the art as RFS direct bonding systems. The bonding mixture of the present invention may contain any amount of these direct bonding systems.

[0153] The adhesive mixtures of the invention can be produced in a known manner by mixing the rubber mixtures of the invention with at least one adhesive based on resorcinol, formaldehyde and silicon dioxide.

[0154] In the binder, the formaldehyde may be present in the form of a formaldehyde donor. Suitable formaldehyde donors include not only hexamethylenetetramine but also hydroxymethylamine derivatives.

[0155] To improve the bonding, one or more components capable of forming synthetic resins, such as phenols and / or amines and / or aldehydes or aldehyde-eliminating compounds, can be added to the bonding mixture according to the invention.

[0156] Method for producing a rubber cured product

[0157] A method for producing a rubber vulcanizate, characterised in that the rubber mixture according to the invention is heated at a temperature of 120°C to 200°C, preferably 140°C to 180°C.

[0158] The process according to the invention for producing a rubber vulcanizate can be carried out under a wide pressure range, preferably under a pressure in the range from 10 to 200 bar.

[0159] The invention further provides a rubber vulcanizate obtainable by vulcanizing the rubber mixture according to the invention.

[0160] The rubber vulcanizates according to the invention have unexpectedly low rolling resistance, especially when used in tires, and comparable performance characteristics.

[0161] In the context of the present invention, the rolling resistance is determined by DIN EN ISO 6721-1 dynamic damping via the loss factor tan δ at 60° C.

[0162] Molded products

[0163] The rubber cured products of the present invention are suitable for the production of all kinds of shaped articles, for example tire parts, technical rubber products such as damping elements, roller coverings, conveyor belt coverings, transmission belt coverings, spinning cop coverings, seal coverings, golf ball core coverings, shoe sole coverings; they are particularly suitable for the production of tires and tire parts, such as tire treads, tire bases, carcasses, tire sidewalls, reinforced sidewalls of run-flat tires, and apex bead mixtures. Tire treads also include treads of summer, winter and all-weather tires, as well as treads of passenger car, truck and light truck tires.

[0164] Preferred shaped articles are tires and tire parts containing the rubber vulcanizate according to the invention.

[0165] use

[0166] The invention further provides the use of at least one ethoxylated compound of formula (I), in particular in an amount of 0.5 to 20 phr, particularly preferably 1.0 to 15.0 phr, and at least one functionalized synthetic rubber, in particular in an amount of 50-100 phr, particularly preferably 70-100 phr, for producing cured products having low rolling resistance made from sulfur-crosslinkable rubber mixtures at a curing temperature of 120° C. to 200° C.

[0167] The invention further provides for the use of at least one ethoxylated compound of formula (I) and at least one synthetic rubber in rubber mixtures, vulcanized products producible therefrom and shaped articles for reducing the rolling resistance of shaped articles made from the rubber vulcanized products, preferably tires and tire parts.

[0168] The descriptions and preferred ranges indicated for the components present and optionally present in the rubber mixture according to the invention, such as at least one functionalized synthetic rubber, at least one natural rubber, at least one unfunctionalized synthetic rubber, at least one hydroxyl-containing oxidic filler, at least one carbon black, at least one crosslinking agent, at least one vulcanization accelerator, zinc oxide, at least one auxiliary accelerator, at least one reinforcing additive, rubber auxiliary and at least one ethoxylated compound of formula (I), apply analogously, in particular, to the disclosed methods and uses as well as to the cured products, shaped articles and adhesive mixtures.

[0169] The indicated descriptions and preferred ranges also apply in particular to the rubber mixtures, cured products, shaped articles, adhesive mixtures, methods and uses according to the invention, regardless of whether they are disclosed in the plural (e.g. multiple rubber mixtures) or in the singular (e.g. one rubber mixture). DETAILED DESCRIPTION

[0170] The present invention will be illustrated by the following examples, but is not limited thereto.

[0171] Exemplary Embodiments

[0172] Table 1: List of input materials, abbreviations and manufacturers

[0173]

[0174]

[0175] Production of rubber cured products

[0176] The rubber mixture of the reference mixture not according to the invention was produced according to EP 2858831A1, which represents a conventional rubber mixture containing SBR and BR, and the examples 1 and 2 according to the invention were produced according to the formulations specified in Table 2. The difference between the examples according to the invention and the reference mixture is that the reference mixture contains, in addition to the functionalized synthetic rubber, O 13 / 50 and therefore contains an ethoxylated compound of formula (I).

[0177] The production of rubber mixture is carried out in the following steps:

[0178] First mixing stage:

[0179] ·Will BR1261 and SLR 3402 was initially charged to the internal mixer and mixed for approximately 30 seconds.

[0180] Add aging stabilizer 4020 and HS, and mix the mixture for about 30 seconds.

[0181] Add half of ZEOSIL 1165MP and 75, and blend the mixture for about 60 seconds.

[0182] Add half of ZEOSIL 1165MP, N 234 and A9818、Vivatec 500、Escorez 5600、 DPG-80 and O 13 / 50 and the mixture was mixed for about 60 seconds and then tumbled. Mixing was carried out until a temperature of 160°C was reached and then mixed at 160°C for 4 minutes.

[0183] After the first mixing stage, the mixed batch was fed to a downstream roller mill and formed into sheets, strips or pellets and stored at room temperature for 24 hours. The processing temperature was 70°C.

[0184] Second mixing stage:

[0185] This was followed by mixing in an internal mixer until a temperature of 160° C. was reached (so-called post-mastication).

[0186] After the second mixing stage, the mixed batch was fed to a downstream roller mill and formed into sheets, strips or pellets using the roller mill and stored at room temperature for 24 hours.

[0187] Third mixing stage:

[0188] Add additives such as sulfur, zinc oxide and

[0189]

[0190] After the third mixing stage is complete, the mixed batch is formed into sheets, strips or pellets using a roll mill and stored at room temperature for 24 hours. In this case, the processing temperature is 70°C.

[0191] The inventive rubber mixtures 1 and 2 showed no spots on the surface and therefore good mixing of the additives employed was assumed.

[0192] Table 2: Rubber formulation (data in phr)

[0193]

[0194]

[0195] Technical Testing

[0196] The cured products produced from the rubber mixtures of Examples 1 and 2 and from the reference mixtures at 160° C. were subjected to the technical tests specified below. The values ​​determined are reported in Table 3.

[0197] Very good properties of the rubber mixture / their cured products are achieved when the properties of the rubber mixture / their cured products are within the specified "preferred ranges".

[0198] The following test methods are used for testing the test specimens:

[0199] Mooney viscosity measurement

[0200] Determine using shear disc viscometer according to ASTM D 1646. Viscosity can be directly determined by the reaction force applied by rubber (and rubber mixture) during its processing. In the Mooney shear disc viscometer, a grooved disc is surrounded up and down with the test material, and the disc is moved in a heatable chamber at about two revolutions per minute. The force required for this is measured as torque and corresponds to the corresponding viscosity. The sample is usually preheated to 100°C for one minute, and the measurement lasts for another 4 minutes, and the temperature remains constant. The viscosity is reported together with the corresponding test conditions, such as ML (1+4) 100°C (Mooney viscosity, rotor size L, warm-up time in minutes and test time, test temperature).

[0201] Rheometer (curometer) used and scorch / full cure time

[0202] MDR (moving die rheometer) cure profiles and analytical data related thereto were measured on a MDR 2000 Monsanto rheometer according to ASTM D5289-95.

[0203] The scorch time (t5) is the time at which 5% of the rubber is crosslinked. The temperature chosen is 160°C.

[0204] The through cure time (t95) is the time at which 95% of the rubber is crosslinked. The temperature selected is 160°C.

[0205] The ΔS' value is calculated based on the difference between the highest and lowest values ​​of the rheometer curve, i.e. S max -S min .

[0206] Determination of elongation at break, tensile strength, and 300 modulus

[0207] The measurements were carried out in accordance with DIN 53504 (tensile test, S2 bar, 5 measurements).

[0208] Determination of Shore A Hardness

[0209] The Shore hardness (Shore A) was measured at 23° C. according to DIN 53505 (3 measurements).

[0210] Resilience

[0211] The rebound resilience was measured at 23° C. in accordance with DIN 53512 (three measurements).

[0212] Determination of DIN wear

[0213] The simplest method for determining abrasive wear is the so-called DIN wear according to ASTM D5963. A test specimen made of the elastomer to be tested is passed over a defined friction path (40 m) on a rotating cylinder with a constant pressing force and a constant speed (40 min-1) over an abrasive arc. The material loss (in mm) is then determined. 3 count).

[0214] Determination of loss factor

[0215] The loss factor tan δ was determined via DIN EN ISO 6721-1 dynamic damping at 60°C and a measuring frequency of 10 Hz.

[0216] Table 3: Test values

[0217]

[0218] in conclusion:

[0219] It has surprisingly been found that the rubber mixtures according to the invention according to Examples 1 and 2 achieve a shorter through-cure time (t95), a longer scorch time (t5) and a significantly lower loss factor tan δ at 60° C. and significantly lower DIN wear as well as unchanged or improved further mechanical properties compared to a non-inventive rubber mixture reference.

Claims

1. A rubber mixture comprising - 50 to 100 phr of at least one functionalized synthetic rubber, preferably a functionalized BR rubber and / or a 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 oxidic filler, - 0 to 120 phr, preferably 0.1 to 100 phr, of at least one carbon black, - 0.1 to 20 phr of at least one crosslinking agent, preferably chosen from the group of sulfur donors and / or sulfur, and 0.5 to 10 phr of at least one ethoxylated compound of formula (I) RO(CH2CH2O) x H(I), in R represents an alkyl group, wherein the alkyl group may be branched or unbranched, and x represents a rational number from 1 to 25.

2. The rubber mixture according to claim 1, characterized in that R stands for C1-C 20 -alkyl, preferably C5-C 17 -alkyl, particularly preferably C 10 -C 15 -alkyl, very particularly preferably iso-C 13 -alkyl, very particularly preferably iso-C 13 H 27 .

3. The rubber mixture according to any one of claims 1 or 2, characterized in that x represents a rational number of 2 to 22, preferably 4 to 20.

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

5. The rubber mixture according to any one of claims 1 to 4, characterized in that The at least one functionalized synthetic rubber is substituted in the main chain and / or at the end groups by one or more functional groups selected from carboxyl groups, thiol groups, alkoxysilane groups, siloxane groups, hydroxyl groups, ethoxy groups, epoxy groups, amino groups, phthalocyanine groups, silane-thioether groups and groups containing metal atoms, preferably selected from thiol groups, alkoxysilane groups and hydroxyl groups, particularly preferably selected from thiol groups and alkoxysilane groups.

6. The rubber mixture according to any one of claims 1 to 5, characterized in that The at least one hydroxyl-containing oxidic filler is selected from the group consisting of silicon dioxide, synthetic silicates and natural silicates and is present in the rubber mixture in an amount of 0.1 to 250 phr, preferably 20 to 200 phr, particularly preferably 25 to 180 phr, very particularly preferably 30-160 phr.

7. The rubber mixture according to any one of claims 1 to 6, characterized in that The rubber mixture contains 0.5 to 10 phr, preferably 1.0 to 8 phr and particularly preferably 1 to 4 phr of at least one crosslinking agent from the group of sulfur and sulfur donors.

8. The rubber mixture according to any one of claims 1 to 7, characterized in that The rubber mixture contains at least one reinforcing additive from the group of sulfur-containing organosilanes, in particular sulfur-containing silanes containing alkoxysilyl groups and particularly preferably sulfur-containing organosilanes containing trialkoxysilyl groups.

9. The rubber mixture according to claim 1, characterized in that The rubber mixture contains - 70 to 100 phr of at least one functionalized synthetic rubber, preferably a functionalized BR rubber and / or a 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 oxidic filler, - 0.1 to 120 phr, preferably 0.1 to 100 phr, of at least one carbon black, - 0.5 to 10 phr of at least one crosslinking agent, preferably chosen from the group of sulfur donors and / or sulfur, - 0.1 to 10 phr of zinc oxide, - 0.5 to 10 phr of at least one curing accelerator, in particular from the group of sulfenamides, - 0.1 to 10.0 phr of at least one auxiliary accelerator, - 0.5 to 15 phr of at least one reinforcing additive, especially from the group of sulfur-containing silanes, - 0.1 to 30 phr of rubber additives as well as - 1 to 15 phr of the at least one ethoxylated compound of formula (I).

10. A method for producing a rubber mixture according to the invention as claimed in any one of claims 1 to 9, characterized in that The corresponding components are mixed during the mixing process.

11. Use of the rubber mixture according to any one of claims 1 to 9 for producing vulcanized products of all kinds and rubber shaped articles, in particular for producing tires and tire components.

12. A cured product obtained by curing at least one rubber mixture as claimed in any one of claims 1 to 9, preferably at a temperature of 120°C to 200°C.

13. A vehicle tire, characterized in that: The vehicle tire has at least one cured product as claimed in claim 12 .

14. Use of at least one ethoxylated compound of formula (I), in particular in an amount of 0.5 to 20 phr, particularly preferably 1.0 to 15.0 phr, and at least one functionalized synthetic rubber, in particular in an amount of 50-100 phr, particularly preferably 70-100 phr, for producing vulcanized products having low rolling resistance from sulfur-crosslinkable rubber mixtures at a vulcanization temperature of 120° C. to 200° C., RO(CH2CH2O) x H(I), in R represents an alkyl group, wherein the alkyl group may be branched or unbranched, and x represents a rational number from 1 to 25.

15. An adhesive mixture comprising at least one rubber mixture as claimed in one of claims 1 to 9 and at least one binder based on resorcinol, formaldehyde and silicon dioxide.

Images