Rubber mixtures containing ethoxylated alcohols

Abstract

The invention relates to rubber blends containing, in addition to specific amounts of synthetic rubber, filler and cross-linking agent, 0.5 to 10 phr of at least one ethoxylated compound of formula (I): RO (CH2CH2O) xH, in which R represents an alkyl group, which may be branched or unbranched, and x represents an integer between 1 and 20, and these rubber blends 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 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 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 2 Emissions play 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 (best fuel efficiency) to class E. Fuel consumption is important from both an economic and environmental point of view. Low fuel consumption has a significant impact on the CO 2 Balancing has a positive impact, 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 the 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, thus adversely affecting the reinforcing effect of the filler. However, insufficient hardness or stiffness of the cured product leads to insufficient running characteristics of the tire, especially during cornering.

[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 2858831 A2 discloses that a rubber mixture containing 1 phr of 1,6-bis(N,N-dibenzylthiocarbamoyldisulfide)hexane (CAS number: 151900-44-6) and 1 phr of certain sulfur-containing additives produces 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 a few mixture components.

[0010] 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 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 loss factor tan δ at 60° C. and almost unchanged properties such as 300° modulus and hardness. The improved rubber mixture should also preferably have a reduced full cure time (t95). The improved rubber compound should also preferably have low rolling resistance measured by loss factor tan δ at 60° C. at unchanged 300° modulus and hardness.

[0012] The low loss factor tan δ at 60° C., determined by DIN 53513 dynamic damping, is preferably less than 0.2, particularly preferably less than 0.12.

[0013] The scorch time t5 determined at 130° C. in accordance with ASTM D5289-95 is preferably in the range of 1000 to 1500 seconds, particularly preferably in the range of 1300 to 1500 seconds.

[0014] The short through-cure time t95 (95% conversion time) determined at a temperature of 170° C. according to ASTM D5289-95 is preferably in the range of 500-1000 seconds.

[0015] High 300 modulus values ​​are also advantageous for cured products, in particular for tire treads. The 300 modulus (determined according to DIN 53504) is preferably 10-25 MPa.

[0016] The hardness determined according to DIN 53505 should be in the range of 60-75 Shore A.

[0017] 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 synthetic rubbers and one or more natural rubbers).

[0018] The above objects are surprisingly achieved by the rubber mixture according to the invention, which contains

[0019] - 50 to 100 phr of at least one synthetic rubber, preferably BR rubber and / or SBR rubber,

[0020] - 0 to 50 phr of at least one natural rubber,

[0021] - 0.1 to 200 phr of at least one hydroxyl-containing oxidic filler,

[0022] - 0 to 120 phr, preferably 0.1 to 100 phr, of at least one carbon black,

[0023] - 0.1 to 20 phr of at least one crosslinking agent, preferably chosen from the group of sulfur donors and / or sulfur, and

[0024] 0.5 to 10 phr of at least one ethoxylated compound of formula (I)

[0025] RO(CH 2 CH 2 O) x H(I),

[0026] in

[0027] R represents an alkyl group, wherein the alkyl group may be branched or unbranched,

[0028] and

[0029] x represents an integer from 1 to 20.

[0030] 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 a short through cure time (t95), while retaining equally good performance characteristics such as 300 modulus, hardness and cure characteristics.

[0031] rubber

[0032] The rubber mixture according to the invention contains at least one synthetic rubber, preferably selected from the group consisting of polar and nonpolar synthetic rubbers.

[0033] Preferred polar and nonpolar synthetic rubbers are

[0034] BR-Polybutadiene

[0035] ABR-Butadiene / C1-C4-alkyl acrylate copolymer

[0036] CR-Polychloroprene

[0037] IR-polyisoprene

[0038] SBR - styrene / butadiene copolymer, with a styrene content of 1% to 60%, preferably 20% to 50% by weight

[0039] IIR-isobutylene / isoprene copolymer

[0040] NBR - butadiene / acrylonitrile copolymer, having an acrylonitrile content of 5% to 60%, preferably 10% to 50%, by weight,

[0041] HNBR - partially or fully hydrogenated NBR rubber

[0042] EPDM-ethylene / propylene / diene copolymer

[0043] SIBR - Styrene-isoprene-butadiene rubber

[0044] ENR-Epoxidized Natural Rubber

[0045] SNBR-Acrylonitrile-Styrene / Butadiene Rubber

[0046] HNBR-Hydrogenated Acrylonitrile / Butadiene Rubber

[0047] XNBR-Carboxylated acrylonitrile / butadiene rubber

[0048] HXNBR-Hydrogenated Carboxylated Acrylonitrile / Butadiene Rubber

[0049] The at least one synthetic rubber is preferably selected from the group consisting of SBR and BR rubbers.

[0050] It is preferred when the rubber mixture according to the invention contains at least one SBR rubber and / or BR rubber, particularly preferably an SBR rubber and a BR rubber.

[0051] The SBR rubber may be a functionalized SBR rubber.

[0052] Functionalized SBR rubbers are understood to mean SBR rubbers which are substituted at the main chain and / or at the end groups by one or more functional groups, in particular carboxyl groups and / or thiol-containing groups.

[0053] In a preferred embodiment, the rubber mixture according to the invention contains at least one functionalized SBR rubber and optionally one or more BR rubbers.

[0054] The rubber mixture according to the invention contains 50 to 100 phr, preferably 70-100 phr, of at least one synthetic rubber.

[0055] The rubber mixture according to the invention preferably contains at least one SBR and at least one 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 50:50, very very particularly preferably 80:20 to 60:40.

[0056] In an alternative advantageous embodiment, the rubber mixture according to the invention contains at least one natural rubber.The rubber mixture according to the invention may contain 0 to 50 phr, preferably 0-30 phr, of natural rubber.

[0057] Ethoxylated compounds having formula (I)

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

[0059] RO(CH 2 CH 2 O) x H(I),

[0060] in

[0061] R represents an alkyl group, wherein the alkyl group may be branched or unbranched,

[0062] and

[0063] x represents an integer from 1 to 20.

[0064] R preferably represents C 1 -C 20 -alkyl, particularly preferably C 5 -C 17 -alkyl, very particularly preferably C 10 -C15 -alkyl, very particularly preferably iso-C 13 -alkyl, most preferably iso-C 13 H 27 .

[0065] x preferably represents an integer of 2 to 15, particularly preferably 3 to 10, very particularly preferably 4 to 6 and most preferably 5.

[0066] At least one ethoxylated compound of formula (I) is present, for example, in the ethoxylates from BASF. TO 5.

[0067] 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 10.0 phr, preferably 1.0 to 8.0 phr, particularly preferably 2.0 to 7.0 phr and very particularly preferably 4.0 to 6.0 phr.

[0068] filler

[0069] The at least one hydroxyl-containing oxidic filler is preferably selected from the group consisting of silicon dioxide, synthetic silicates and natural silicates.

[0070] The content of hydroxyl-containing oxidic fillers in the rubber mixture according to the invention is from 0.1 to 200 phr, preferably from 20 to 160 phr, particularly preferably from 25 to 140 phr and very particularly preferably from 30 to 120 phr.

[0071] Suitable hydroxyl-containing oxidic fillers are preferably those selected from the group consisting of

[0072] - especially having a range of 5 to 1000, preferably 20 to 400 m 2 / g of silicon dioxide with a specific surface area (BET) of 100 to 400 nm, preferably with 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),

[0073] - Synthetic silicates, such as aluminum silicates, alkaline earth metal silicates (such as magnesium silicate or calcium silicate), having a molecular weight of 20 to 400 m 2 / g of specific surface area (BET), preferably having a primary particle size of 10 to 400 nm,

[0074] as well as

[0075] - natural silicates, such as kaolin and other naturally occurring silicas,

[0076] and mixtures thereof.

[0077] 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).

[0078] It is preferred when the silicon dioxide is obtainable by precipitation from silicate solutions or by flame hydrolysis of silicon halides.

[0079] When the rubber mixture according to the invention contains 0.1 to 200 phr, preferably 20 to 160 phr, particularly preferably 25 to 140 phr, very particularly preferably 30-120 phr of at least one of the following: 2 Hydroxyl-containing oxidic fillers from the group of silica having a specific surface area (BET) in the range of 200 Å / g are preferred.

[0080] The rubber mixture according to the invention may contain at least one carbon black as filler.

[0081] In a preferred embodiment, the rubber mixture according to the invention contains at least one carbon black as filler.

[0082] 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.

[0083] 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).

[0084] 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.

[0085] It is very particularly preferred when the rubber mixture according to the invention contains 25 to 140 phr, preferably 30 to 120 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.

[0086] The total amount of carbon black and silica-based filler in the rubber mixture according to the invention is preferably from 26 to 210 phr, particularly preferably from 32 to 160 phr.

[0087] Crosslinkers and curing accelerators

[0088] The rubber mixtures according to the invention may contain one or more crosslinking agents.

[0089] 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.

[0090] Sulfur can be used in elemental soluble or insoluble form.

[0091] 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.

[0092] Examples of suitable sulfur donors include dimorpholinyl disulfide (DTDM), 2-morpholinobenzothiazole disulfide (MBSS), caprolactam disulfide, dipentamethylenethiuram tetrasulfide (DPTT), tetramethylthiuram disulfide (TMTD), and tetrabenzylthiuram disulfide (TBzTB).

[0093] The rubber mixture according to the invention generally contains from 0.1 to 20 phr, preferably from 0.5 to 10 phr and particularly preferably from 1.0 to 8 phr of at least one crosslinking agent from the group of sulfur and sulfur donors.

[0094] In a particularly preferred embodiment, the rubber mixture according to the invention contains 0.1 to less than 1.8 phr, very particularly preferably 1.0 to 1.7 phr, very very particularly preferably 1.3 to 1.7 phr of sulfur in the at least one crosslinking agent.

[0095] In an alternative particularly preferred embodiment, the rubber mixture according to the invention contains 1.8 to 20 phr, very particularly preferably 1.9 to 8.0 phr, very very particularly preferably 1.9 to 5 phr, most preferably 1.9 to 3 phr of sulfur in the at least one crosslinking agent.

[0096] The last-mentioned embodiment achieves the further object of providing improved rubber mixtures which, at unchanged 300 modulus and hardness, have a particularly low rolling resistance measured by the loss factor tan δ at 60° C.

[0097] In the two above-mentioned embodiments, the term “phr of sulfur in the at least one crosslinking agent” indicates that the above-mentioned phr of sulfur refers to the amount of sulfur in the at least one crosslinking agent and thus also to the amount of sulfur used in the form of sulfur donor.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] The rubber mixtures according to the invention may contain one or more vulcanization accelerators.

[0102] 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).

[0103] 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.

[0104] The rubber mixtures of the invention preferably contain at least one crosslinking agent and at least one vulcanization accelerator.

[0105] 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).

[0106] 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.

[0107] 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.

[0108] Enhancement Additives

[0109] The rubber mixtures according to the invention may contain one or more reinforcing additives.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] Rubber additives

[0115] The rubber mixture according to the present 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.

[0116] 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.

[0117] 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).

[0118] 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, 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, 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] Particularly preferred is the rubber mixture of the present invention containing

[0126] - 50 to 100 phr of at least one synthetic rubber, in particular BR rubber and / or SBR rubber,

[0127] - 20 to 160 phr of at least one silicon dioxide, in particular having a molecular weight of 5 to 1000, preferably 20 to 400 m 2 / g specific surface area (BET) and has a primary particle size of 100 to 400 nm,

[0128] - 0.1 to 100 phr of at least one carbon black, especially having a carbon black content of 20 to 200 m2 / g range of specific surface area (BET),

[0129] - 0.5 to 10 phr of at least one crosslinking agent, in particular from the group of sulfur donors and / or sulfur,

[0130] - 0.1 to 10 phr of zinc oxide,

[0131] - 0.5 to 10 phr of at least one curing accelerator, in particular from the group of sulfenamides,

[0132] - 0.1 to 10.0 phr of at least one auxiliary accelerator,

[0133] - 0.5 to 15 phr of at least one reinforcing additive, especially from the group of sulfur-containing silanes,

[0134] - 0.1 to 30 phr of rubber additives

[0135] as well as

[0136] - 0.5 to 10.0 phr of at least one ethoxylated compound of formula (I).

[0137] The abovementioned further preferred ranges for the individual components also apply to the preferred mixtures.

[0138] Method for producing a rubber mixture

[0139] 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 synthetic rubber, optionally at least one natural rubber and at least one ethoxylated compound of formula (I), optionally in the presence of one or more of at least one filler, optionally at least one crosslinking agent, optionally at least one vulcanizing 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 30° C. to 170° C., particularly preferably 140° C. to 160° C.

[0140] 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. -1 Shear rate production.

[0141] The production of the rubber mixture according to the present invention is preferably carried out in a two-stage mixing process. In the first mixing stage, filler and at least one ethoxylated compound with formula (I) and optionally other above-mentioned rubber additives are initially mixed into the rubber in an internal mixer (kneader). The mixing temperature in the internal mixer can reach values ​​up to 170° C. The mixing temperature in the internal mixer is preferably 130° C. to 170° C., particularly preferably 140° C. to 160° C.

[0142] This is preferably followed by so-called post-mastication, preferably at 130 to 170° C., particularly preferably at 150° C. Post-mastication can be carried out, for example, in a kneader or an internal mixer.

[0143] In the second mixing stage, a crosslinking agent, a curing accelerator and optionally additional rubber additives, preferably an auxiliary accelerator and an aging stabilizer are added to the mixture obtained from the first mixing stage. The mixing temperature in the second mixing stage is preferably 50°C-150°C, preferably 55°C-140°C, in particular 60°C to 130°C.

[0144] The second mixing stage is preferably carried out on a roller mill with water-cooled rollers. This allows lower mixing temperatures than in the first mixing stage.

[0145] 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 170°C, preferably at a temperature of 140 to 160°C.

[0146] 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.

[0147] Adhesive compound

[0148] The invention further provides an adhesive mixture containing the rubber mixture according to the invention and at least one adhesive.

[0149] The adhesive mixture according to the invention preferably contains at least one adhesive based on resorcinol, formaldehyde and silicon dioxide.

[0150] 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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] Method for producing a rubber cured product

[0155] 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.

[0156] 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.

[0157] The invention further provides a rubber vulcanizate obtainable by vulcanizing the rubber mixture according to the invention.

[0158] The rubber vulcanizates according to the invention have unexpectedly low rolling resistance, especially when used in tires, and comparable performance characteristics.

[0159] In the context of the present invention, the rolling resistance is determined by DIN 53513 dynamic damping via the loss factor tan δ at 60°C.

[0160] Molded products

[0161] 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.

[0162] Preferred shaped articles are tires and tire parts containing the rubber vulcanizate according to the invention.

[0163] The invention further provides the use of the at least one ethoxylated compound of formula (I) for producing vulcanized products having low rolling resistance made from sulfur-crosslinkable rubber mixtures, in particular in an amount of 0.5 to 10.0 phr at a vulcanization temperature of 120° C. to 200° C.

[0164] The invention further provides for the use of the at least one ethoxylated compound of the formula (I) in rubber mixtures, vulcanizates producible therefrom and shaped articles for reducing the rolling resistance of shaped articles made from the rubber vulcanizates, preferably tires and tire parts.

[0165] 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 synthetic rubber, at least one natural 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 and to the cured products, shaped articles and adhesive mixtures.

[0166] 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

[0167] The present invention will be illustrated by the following examples, but is not limited thereto.

[0168] Exemplary Embodiments

[0169] Table 1: List of input materials, abbreviations and manufacturers

[0170]

[0171]

[0172] Production of rubber cured products

[0173] The rubber mixture of non-inventive example 1 was produced according to the composition of the reference mixture from EP 2 858 831 A1, and inventive examples 2 and 3 were produced according to the recipes specified in table 1.

[0174] The production of rubber mixture is carried out in the following steps:

[0175] First mixing stage:

[0176] ■ CB 24 and VSL 4526-2HM was initially charged into the internal mixer and mixed for approximately 30 seconds.

[0177] ■Add two-thirds S and two-thirds 69 and mix the mixture for about 60 seconds.

[0178] ■Add one third S. One third 69 and 1849-TE, and mix the mixture for about 60 seconds.

[0179] Add to N 339, A9818, 4020 / LG, HS, ZINKOXID (ROTSIEGEL), TO 5, and mix the mixture for about 60 seconds.

[0180] The mixing operation was carried out at a temperature of 150°C.

[0181] 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.

[0182] The processing temperature is 70°C.

[0183] This is followed by mixing in a kneader / internal mixer at 150° C. (so-called post-massaging). Second mixing stage:

[0184] Additives such as MAHLSCHWEFEL 90 / 95CHANCEL, CZ / C, Addition of DPG-80.

[0185] Table 2: Rubber formula

[0186]

[0187] Technical Testing

[0188] The cured products produced at 170° C. from the rubber mixtures of Examples 1 to 3 were subjected to the technical tests specified below. The values ​​determined are reported in Table 3.

[0189] 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".

[0190] The following test methods are used for testing the test specimens:

[0191] Rheometer (curometer) used and scorch / full cure time

[0192] MDR (moving die rheometer) cure profiles and analytical data related thereto were measured on a MDR 2000 Monsanto rheometer according to ASTM D5289-95.

[0193] The scorch time (t5) is the time at which 5% of the rubber is crosslinked. The temperature chosen is 130°C.

[0194] The through cure time (t95) is the time at which 95% of the rubber is crosslinked. The temperature selected is 170°C.

[0195] 300 Determination of modulus

[0196] The measurements were carried out in accordance with DIN 53504 (tensile test S2 bar) at a temperature of 23°C.

[0197] Determination of Shore A Hardness

[0198] The measurements were carried out in accordance with DIN 53 505 at room temperature (RT).

[0199] Determination of rolling resistance

[0200] The loss factor tan δ is determined via DIN 53513 dynamic damping at 60 °C.

[0201] Table 3: Test values

[0202] Examples 1 2 3 This invention is / is not no yes yes Scorch time (t5) [s] 1279 1342 1234 Complete curing time (t95) [s] 1157 708 688 300Modulus[MPa] 15.7 13.5 15.7 Hardness [Shore A] 69 68 69 Loss factor tanδ at 60°C 0.117 0.113 0.100

[0203] in conclusion:

[0204] It has surprisingly been found that the inventive rubber mixtures according to Examples 2 and 3 achieve a shorter through-cure time (t95) and a significantly lower loss factor tan δ at 60° C., as well as virtually unchanged further mechanical properties, compared to the non-inventive rubber mixture of Example 1 (corresponding to the composition of the reference mixture from EP 2 858 831 A1). Compared to the non-inventive rubber mixture of Example 1, the inventive mixture 3 achieves a lower loss factor tan δ at 60° C. at the same 300 modulus and hardness.

[0205] Compared to rubber formulation 1 from EP 2858831 A1, the inventive rubber mixtures according to Examples 2 and 3 even achieve improved scorch times (t5), and the inventive rubber mixture according to Example 3 even achieves a lower loss factor tan δ at 60° C.

[0206] The inventive rubber mixtures 2 and 3 do not show any spots on the surface and therefore good mixing of the additives employed is assumed.

Claims

1. A rubber mixture comprising - 50 to 100 phr of at least one synthetic rubber, preferably BR rubber and / or SBR rubber, - 0 to 50 phr of at least one natural rubber, - 0.1 to 200 phr of at least one hydroxyl-containing 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 an integer from 1 to 20.

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 is an integer of 2 to 15, preferably 3 to 10, particularly preferably 4 to 6, very particularly preferably 5.

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

5. The rubber mixture according to any one of claims 1 to 4, 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 200 phr, preferably 20 to 160 phr, particularly preferably 25 to 140 phr, very particularly preferably 30-120 phr.

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

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

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 - 50 to 100 phr of at least one synthetic rubber, in particular BR rubber and / or SBR rubber, - 20 to 160 phr of at least one silicon dioxide, in particular having a molecular weight of 5 to 1000, preferably 20 to 400 m 2 / g specific surface area (BET) and has a primary particle size of 100 to 400 nm, - 0.1 to 100 phr of at least one carbon black, especially having a carbon black content of 20 to 200 m 2 / g range of specific surface area (BET), - 0.5 to 10 phr of at least one crosslinking agent, in particular from the group of sulfur donors and / or sulfur, - 0.1 to 10 phr of zinc oxide, - 0.5 to 10 phr of at least one 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 - 0.5 to 10.0 phr of 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. The use of at least one ethoxylated compound of formula (I) for producing vulcanized products having low rolling resistance from sulfur-crosslinkable rubber mixtures, in particular in an amount of 0.5 to 10.0 phr at a vulcanization temperature of 120° 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 an integer from 1 to 20.

15. Use of at least one ethoxylated compound of formula (I) in rubber mixtures, vulcanized products obtainable therefrom and shaped articles for reducing the rolling resistance of shaped articles made from the rubber vulcanized products, preferably tires and tire parts RO(CH2CH2O) x H(I), in R represents an alkyl group, wherein the alkyl group may be branched or unbranched, and x represents an integer from 1 to 20.

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