Rubber mixtures containing at least one non-aromatic, polar substance

Abstract

The invention relates to rubber mixtures containing at least one rubber, at least one hydroxyl-group-containing oxidic filler, at least one strengthening additive from the group of sulfurous organic silanes, at least one cross-linker from the group of sulfur and sulfur donors, and at least one non-aromatic, polar substance with 4-12 carbon atoms, a mixture A containing the at least one fatty acid and the at least one non-aromatic, polar substance with 4-12 carbon atoms, to the production and use thereof, and to the vulcanised materials obtained therefrom by means of the vulcanisation process, in particular in the form of tyres, parts of tyres, or technical rubber products.

Description

[0001] Rubber mixtures containing at least one non-aromatic, polar substance

[0002] The invention relates to rubber mixtures containing at least one rubber, at least one hydroxyl-containing oxidic filler, at least one reinforcing additive from the series of sulfur-containing organic silanes, at least one crosslinker from the series of sulfur and sulfur donors, at least one fatty acid and at least one non-aromatic, polar substance having 4-12 carbon atoms, a mixture A containing the at least one fatty acid and the at least one non-aromatic, polar substance having 4-12 carbon atoms, their preparation and use, and the vulcanizates obtainable thereby by the vulcanization process, in particular in the form of tires, parts of tires or technical rubber articles.

[0003] To optimize application-relevant properties of vulcanizates such as tires derived from rubber compounds, such as wet skid resistance and rolling resistance, increasingly large amounts of silica and reinforcing additives are being added to the rubber compounds. However, this results in a significant increase in the viscosity of the vulcanizates, necessitating the use of efficient processing aids.

[0004] EP1253167A1 discloses rubber mixtures containing, among other ingredients, at least one diene rubber with polar groups, silica, sulfur, and a non-aromatic, polar substance. Example E1 shows that the use of 1,1,1-trimethylolpropane (TMP) as a non-aromatic, polar substance in combination with the diene rubber acrylonitrile-styrene-butadiene terpolymer not only reduces viscosity, but also improves wet skid resistance and maintains consistent rolling resistance, compared to the analogous mixture without TMP.

[0005] In WO2010136345A1, functionalized rubbers are used together with a TMP fatty acid mixture in rubber compounds to improve rolling resistance and wet skid resistance.

[0006] However, TMP has since been classified as reprotoxic Category 2. Due to this classification of TMP, there is a great need to find toxicologically less harmful substitutes for TMP that have comparable activity to that of the trimethylolpropane fatty acid mixture in WO200136345A1 in rubber mixtures. The present invention is therefore based on the object of providing rubber mixtures that are toxicologically less harmful compared to rubber mixtures of WO2010136345A1, in which the application-relevant properties, preferably wet skid resistance and rolling resistance, are preferably equally good, and Mooney viscosity, scorch resistance, and filler dispersion are preferably equally good, particularly preferably better, than in the corresponding TMP-containing rubber mixtures or vulcanizates.Even more preferably, other application properties such as elongation at break are equally good, preferably better, than those of the corresponding TMP-containing rubber compounds or vulcanizates.

[0007] Surprisingly, it has now been found that when at least one non-aromatic, polar substance having 4-12 carbon atoms, which is different from TMP, is used in rubber mixtures containing at least one rubber, at least one hydroxyl-containing oxidic filler, at least one reinforcing additive from the series of sulfur-containing organic silanes, at least one crosslinker from the series of sulfur and sulfur donors and at least one fatty acid, rubber mixtures are obtainable which achieve this objective compared to the TMP-containing equivalents.

[0008] The present invention accordingly relates to rubber mixtures containing at least one rubber, at least one hydroxyl-containing oxidic filler, at least one reinforcing additive from the series of sulfur-containing organic silanes, at least one crosslinker from the series of sulfur and sulfur donors, and at least one fatty acid, wherein at least one non-aromatic, polar substance having 4-12 carbon atoms, preferably having 5-10 carbon atoms, is further contained, which:

[0009] Contains carbon, hydrogen and oxygen atoms, has a region of at least two chemically bonded carbon atoms, contains a hydroxyl group and at least one further oxygen-containing group selected from hydroxyl, ester, ether, acetal, ketal, aldehyde and carboxylic acid groups, wherein the hydroxyl group and the further oxygen-containing group are not more than 3 positions apart along a molecular chain, and is different from 1,1,1-trimethylolpropane (TMP).

[0010] The loss factor tan delta at 60 °C, preferably at a measurement frequency of 10 Hz, is used as an indicator of rolling resistance. The tan delta at 0 °C, preferably at a measurement frequency of 10 Hz, is used as an indicator of wet skid resistance.

[0011] The scorch safety is measured by measuring the Mooney scorch behavior (Ts05, Ts10).

[0012] The Payne effect (delta G') serves as an indicator for filler dispersion.

[0013] rubber

[0014] The rubber mixtures according to the invention contain at least one rubber. This can be, for example, natural rubber (NR) and / or a synthetic rubber.

[0015] Preferred polar and non-polar synthetic rubbers are

[0016] ACM - Polyacrylate Rubber

[0017] AEM - Ethylene acrylate rubber

[0018] BR - Polybutadien

[0019] ABR - Butadiene / acrylic acid C1-C4 alkyl ester copolymer

[0020] CR - Polychloroprene

[0021] IR - Polyisoprene

[0022] SBR - styrene / butadiene copolymers with styrene contents of 1 - 60, preferably 20-50 wt.%

[0023] II R - Isobutylene / isoprene copolymers

[0024] NBR - butadiene / acrylonitrile copolymers with acrylonitrile contents of 5-60, preferably 10-50 wt.%

[0025] HNBR - partially hydrogenated or fully hydrogenated NBR rubber

[0026] EPM - ethylene / propylene copolymers

[0027] EPDM - ethylene / propylene / diene copolymers

[0028] EVM - ethylene / vinyl acetate copolymers

[0029] SIBR - Styrene-Isoprene-Butadiene Rubber

[0030] ENR - Epoxidized natural rubber

[0031] SNBR - Acrylonitrile-styrene / butadiene rubber

[0032] HNBR - Hydrogenated acrylonitrile / butadiene rubber

[0033] XNBR - Carboxylated acrylonitrile / butadiene rubber

[0034] HXNBR - Hydrogenated carboxylated acrylonitrile / butadiene rubber Particularly preferred polar and non-polar synthetic rubbers are BR, SBR, SIBR, IR and ENR.

[0035] The at least one synthetic rubber may be unfunctionalized or functionalized.

[0036] The rubber mixtures according to the invention can contain at least one functionalized synthetic rubber. The above statements for the unfunctionalized synthetic rubbers apply, with the difference that in the case of functionalized synthetic rubbers, these are functionalized.

[0037] In the context of the present invention, functionalized synthetic rubber is understood to mean a synthetic rubber which is substituted on the main chain and / or on the end groups by one or more functional groups, preferably selected from carboxyl groups, mercaptan groups, alkoxysilane groups, siloxane groups, hydroxyl groups, ethoxy groups, epoxy groups, amino groups, phthalocyanine groups, silane sulfide groups and metal atom-containing groups, particularly preferably selected from mercaptan groups, alkoxysilane groups and hydroxyl groups, very particularly preferably selected from mercaptan groups and alkoxysilane groups.

[0038] Unfunctionalized synthetic rubbers within the scope of the present invention do not contain the aforementioned substitutions by functional groups.

[0039] The rubber mixtures according to the invention preferably contain at least one functionalized synthetic rubber, particularly preferably selected from the group consisting of polar and non-polar functionalized synthetic rubbers.

[0040] Preferably, the at least one functionalized synthetic rubber is selected from the group consisting of functionalized SBR, functionalized BR and functionalized IR rubber, particularly preferably from functionalized SBR and functionalized BR rubber.

[0041] The rubber mixtures according to the invention preferably contain at least one functionalized SBR rubber and / or one functionalized BR rubber, particularly preferably at least one functionalized SBR and at least one functionalized BR rubber.

[0042] In a preferred embodiment, the at least one rubber is selected from the group consisting of natural rubber and synthetic rubbers, preferably at least one functionalized synthetic rubber, particularly preferably at least one functionalized synthetic rubber selected from the group consisting of functionalized SBR, functionalized BR and functionalized IR rubber, very particularly preferably from functionalized SBR and functionalized BR rubber.

[0043] In the most preferred embodiment, the at least one rubber is a functionalized SBR rubber and a functionalized BR rubber.

[0044] Preferably, the at least one functionalized SBR rubber is substituted on the main chain and / or at the end groups by one or more functional groups, in particular selected from mercaptan groups, alkoxysilane groups, and hydroxyl groups, particularly preferably by several functional groups that are mercaptan groups and alkoxysilane groups. Preferably, the at least one functionalized SBR rubber is SPRINTAN® SLR 3402 from Trinseo.

[0045] The functionalized SBR rubber can be solution-polymerized styrene-butadiene rubber (SSBR) or emulsion-polymerized styrene-butadiene rubber (ESBR), whereby a mixture of at least one functionalized SSBR and at least one functionalized ESBR can also be used.

[0046] The molecular weight (Mw) of the styrene-butadiene copolymers can vary over a wide range. Styrene-butadiene copolymers with an Mw of 250,000 to 600,000 g / mol are preferred, and those with an Mw of 350,000 to 500,000 g / mol are particularly preferred.

[0047] Preferably, the at least one functionalized BR rubber is substituted on the main chain and / or at the end groups by one or more functional groups selected from mercaptan groups, alkoxysilane groups, and hydroxyl groups, particularly preferably by alkoxysilane groups. Preferably, the at least one functionalized BR rubber is NIPOL® BR 1261 from Zeon.

[0048] The molecular weight of butadiene polymers can vary over a wide range. Butadiene polymers with a molecular weight of 250,000 to 5,000,000 g / mol are preferred.

[0049] Polybutadiene with a cis content greater than or equal to 90 wt. % is referred to as high-cis type, and polybutadiene with a cis content less than 90 wt. % is referred to as low-cis type. An example of a low-cis polybutadiene is Li-BR (lithium-catalyzed butadiene rubber) with a cis content of 20 to 50 wt. %. Within the scope of the present invention, a high-cis type of functionalized BR rubber is preferred. The rubber mixtures according to the invention preferably contain 0 to 100 phr of at least one functionalized synthetic rubber, more preferably 50 to 100 phr, most preferably 70-100 phr.

[0050] The rubber mixtures according to the invention preferably contain at least one functionalized SBR and at least one functionalized BR rubber in a weight ratio SBR:BR of 100:0 to 0:100, particularly preferably of 90:10 to 10:90, very particularly preferably of 90:10 to 30:70, most preferably of 80:20 to 50:50.

[0051] The rubber mixtures according to the invention preferably contain 0 to 100 phr of at least one unfunctionalized synthetic rubber and / or at least one natural rubber, particularly preferably 0 to 50 phr, very particularly preferably 0 to 30 phr.

[0052] Fillers

[0053] The at least one hydroxyl-containing oxidic filler is preferably selected from the group consisting of silicic acids, synthetic silicates and natural silicates.

[0054] The content of hydroxyl-containing oxidic fillers in the rubber mixtures according to the invention is preferably 0.1 to 250 phr, particularly preferably 20 to 200 phr, very particularly preferably 50 to 180 phr and most preferably 110 to 160 phr.

[0055] Oxidic fillers containing hydroxyl groups are preferably those from the series of

[0056] - Silicas, in particular with a specific surface area (BET) of 5 to 1000, preferably 20 to 400 m 2 / g, preferably with primary particle sizes of 100 to 400 nm, the silicas optionally also being present as mixed oxides with other metal oxides, such as Al, Mg, Ca, Ba, Zr, Ti oxides,

[0057] - synthetic silicates, such as aluminum silicate, alkaline earth silicates such as magnesium silicate or calcium silicate, with specific surface areas (BET) of 20 to 400 m 2 / g, preferably with primary particle sizes of 10 to 400 nm and natural silicates, such as kaolin and other naturally occurring silicas, as well as mixtures thereof. The above-mentioned BET surface areas are determined according to DIN ISO 9277. The primary particle size specifications are based on measurements with a particle analysis device using scattered light. The particle size calculation is based on the Mie theory, which describes the interaction between light and matter (DIN / ISO 13320).

[0058] The silicas are preferably obtainable by precipitation of solutions of silicates or flame hydrolysis of silicon halides.

[0059] The rubber mixtures according to the invention preferably contain at least one hydroxyl-containing oxidic filler from the series of silicas, in particular with a specific surface area (BET) in the range from 5 to 1000, preferably 20 to 400 m 2 / g in an amount of 0.1 to 250 phr, preferably 20 to 200 phr, particularly preferably 50 to 180 phr, most preferably 110 to 160 phr.

[0060] In a particularly preferred embodiment, the rubber mixtures according to the invention contain at least one hydroxyl-containing oxidic filler from the series of silicas in an amount of 110 to 160 phr. This achieves the further preferred object of providing rubber mixtures with improved dispersibility of the fillers, such as the at least one hydroxyl-containing oxidic filler.

[0061] The rubber mixtures according to the invention may contain at least one carbon black as filler.

[0062] In a preferred embodiment, the rubber mixtures according to the invention contain at least one carbon black as filler.

[0063] The rubber mixtures according to the invention preferably contain at least one carbon black in an amount of 0.1 to 120 phr, particularly preferably 0.1 to 100 phr, very particularly preferably 1 to 70 phr, most preferably 2 to 40 phr.

[0064] Preferred carbon blacks are those obtainable by the lamp black, furnace black or gas black process and which have a specific surface area (BET) in the range of 20 to 200 m 2 / g, such as SAF, ISAF, IISAF, HAF, FEF, or GPF carbon blacks. The rubber mixtures according to the invention preferably contain at least one carbon black with a specific surface area (BET) in the range of 20 to 200 m 2 / g . The rubber mixtures according to the invention particularly preferably contain as fillers at least one of the above-mentioned silicas and at least one of the above-mentioned carbon blacks.

[0065] The rubber mixtures according to the invention very particularly preferably contain as fillers 50 to 180 phr, preferably 110 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.

[0066] The total amount of carbon black and silica-based fillers in the rubber mixture according to the invention is preferably 51 to 250 phr, particularly preferably 112 to 200 phr.

[0067] Networkers and

[0068] The rubber mixtures according to the invention contain at least one crosslinker selected from the group consisting of sulfur and sulfur donors. They may also contain at least one vulcanization accelerator.

[0069] Networker

[0070] The rubber mixtures according to the invention contain at least one crosslinker from the series sulfur and sulfur donors.

[0071] Sulfur can be used in elemental, soluble, or insoluble form. The rubber mixtures according to the invention particularly preferably contain at least one sulfur donor and / or sulfur, most preferably sulfur.

[0072] Examples of sulfur donors include dimorpholyl disulfide (DTDM), 2-morpholinodithiobenzothiazole (MBSS), caprolactam disulfide, dipentamethylene thiuram tetrasulfide (DPTT), tetramethylthiuram disulfide (TMTD) and tetrabenzyl thiuram disulfide (TBzTD).

[0073] The rubber mixtures according to the invention generally contain 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 crosslinker from the group consisting of sulfur and sulfur donors.

[0074] Zinc oxide may be present in the rubber mixtures according to the invention. Preferred rubber mixtures according to the invention contain zinc oxide with a BET surface area of ​​2 to 100 m 2 / g, preferably 2 to 70 m 2 / g. BET surface areas of zinc oxide can be measured according to DIN ISO 9277.

[0075] In general, zinc oxide is present in the rubber mixtures according to the invention in an amount of 0 to 20 phr, preferably 0.1 to 10 phr, particularly preferably 1 to 5 phr.

[0076] The rubber mixtures according to the invention may contain at least one vulcanization accelerator.

[0077] The rubber mixtures according to the invention preferably contain at least one vulcanization accelerator.

[0078] The amount of at least one vulcanization accelerator in the mixture according to the invention is 0 to 20 phr, preferably 0.1 to 10 phr and particularly preferably 0.2 to 5 phr.

[0079] Particularly preferably, the at least one vulcanization accelerator is selected from the group of mercaptobenzothiazoles, thiocarbamates, dithiocarbamates, thiurams, thiazoles, sulfenamides, thiazolesulfenamides, xanthates, bi- or polycyclic amines, thiophosphates, dithiophosphates, caprolactams, thiourea derivatives, guanidines, cyclic disulfanes and amines, in particular zinc diamine diisocyanate, hexamethylenetetramine, 1,3-bis(citraconimidomethyl)benzene, and very particularly preferably from the group of sulfenamides, most preferably N-cyclohexylbenzothiazolesulfenamide (CAS No.: 95-33-0).

[0080] The rubber mixtures according to the invention preferably contain at least one vulcanization accelerator which contains N-cyclohexylbenzothiazole sulfenamide.

[0081] In the mixture according to the invention, guanidine-containing compounds may be contained as the at least one vulcanization accelerator or may not be contained at all.

[0082] Guanidine-containing compounds include, for example, diphenylguanidine (DPG), di-ortho-tolylguanidine (DOTG), 1-(ortho-tolyl)biguanide, substituted diphenylguanidines, and other organic guanidine derivatives in which the guanidine function is substituted with one or more C1-C8 alkyl groups, C2-C8 alkenyl groups, C1-C8 aryl groups, C7-C10 aralkyl groups, and / or C1-C8 heteroalkyl groups. For the purposes of the present invention, the term substituted diphenylguanidines preferably refers to diphenylguanidines in which at least one phenyl ring is substituted, preferably both phenyl rings are substituted. A wide variety of substituents are possible.Preferably, a substituent of a phenyl ring is selected from the group consisting of C1-C2o-alkyl which is substituted or unsubstituted, C2-C2o-alkenyl which is substituted or unsubstituted and contains one or more double bonds, C2-C2o-alkynyl which is substituted or unsubstituted and contains one or more triple bonds, C3-C2o-aryl which is substituted or unsubstituted, heteroaryl which is substituted or unsubstituted, is five to twenty-membered and contains one or more heteroatoms, Ca-Cu-cycloalkyl which is substituted or unsubstituted, heterocycloalkyl which is substituted or unsubstituted, is three to eight-membered and contains one or more heteroatoms, and heteroatoms.

[0083] In a preferred embodiment, the mixture according to the invention contains at least one guanidine-containing compound in the at least one vulcanization accelerator, particularly preferably DPG.

[0084] Most preferably, the at least one vulcanization accelerator in the rubber mixture according to the invention contains N-cyclohexylbenzothiazole sulfenamide and DPG, most preferably the at least one vulcanization accelerator consists of N-cyclohexylbenzothiazole sulfenamide and DPG.

[0085] The total amount of crosslinker and vulcanization accelerator in the rubber mixtures is preferably 0.5 to 30 phr, particularly preferably 1.1 to 18 phr, most preferably 1.2 to 9 phr.

[0086] Non-aromatic, polar substance with 4-12 carbon atoms

[0087] The rubber mixtures according to the invention contain at least one non-aromatic, polar substance with 4-12 carbon atoms, preferably with 5-10 carbon atoms, which

[0088] Contains carbon, hydrogen and oxygen atoms,

[0089] - has a region of at least two chemically bonded carbon atoms,

[0090] - contains a hydroxyl group and at least one further oxygen-containing group selected from hydroxyl, ester, ether, acetal, ketal, aldehyde and carboxylic acid groups, wherein the hydroxyl group and the further oxygen-containing group are not more than 3 positions apart from each other along a molecular chain, and is different from 1,1,1-trimethylolpropane (TMP).

[0091] The at least one non-aromatic, polar substance contains 4-12 carbon atoms, preferably 5-10 carbon atoms.

[0092] Preferably, the at least one non-aromatic, polar substance with 4-12 carbon atoms contains a hydroxyl group and at least one further oxygen-containing group selected from hydroxyl, ester, and ether groups, particularly preferably selected from hydroxyl and ester groups, wherein the hydroxyl group and the further oxygen-containing group are separated by no more than 3 positions along a molecular chain. Most preferably, the at least one non-aromatic, polar substance with 4-12 carbon atoms contains a hydroxyl group and at least one further hydroxyl group, and optionally an ester group.

[0093] Preferably, the at least one non-aromatic, polar substance having 4-12 carbon atoms is selected from the group consisting of diethylene glycol, dipropylene glycol, 2-sec-butyl-2-methyl-1,3-propanediol, 2,2'-oxydi-1-propanol, 1,1'-oxydi-2-propanol, 2-(2-hydroxypropoxy)-1-propanol, 2-methyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, trimethylolethane, ditrimethylolpropane, 2,2,2',2',-tetrakis(hydroxymethyl)-3,3'-oxydipropan-1-ol (dipentaerythritol), 2,2-dimethylpropane-1,3-diol (CAS No. 126-30-7) and hydroxypivalic acid neopentyl glycol ester (2,2-dimethyl-1,3-propanediol mono(hydroxypivalate), CAS No: 1115-20-4), particularly preferably selected from dipropylene glycol, 2-sec-butyl-2-methyl-1,3-propanediol, 2,2,2',2',-tetrakis(hydroxymethyl)-3,3'-oxydipropan-1-ol (dipentaerythritol), 2,2-dimethylpropane-1,3-diol (CAS No.126-30-7) and hydroxypivalic acid neopentyl glycol ester (2,2-dimethyl-1,3-propanediol mono-(hydroxypivalate), CAS No: 1115-20-4), most preferably selected from 2,2-dimethylpropane-1,3-diol (CAS No: 126-30-7) and hydroxypivalic acid neopentyl glycol ester (2,2-dimethyl-1,3-propanediol mono(hydroxypivalate), CAS No: 1115-20-4).

[0094] In the context of the present invention, the at least one non-aromatic, polar substance having 4-12 carbon atoms is different from 1,1,1-trimethylolpropane (2-ethyl2(hydroxymethyl)-1,3-propanediol, TMP).

[0095] More preferably, the at least one non-aromatic, polar substance having 4-12 carbon atoms is different from 1,1,1-trimethylolpropane (2-ethyl2(hydroxymethyl)-1,3-propanediol, TMP) and one or more of the compounds selected from the group consisting of 1,2-pentanediol, 2-methyl-2-propyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, glycerol, pentaerythritol, erythritol, xylitol, sorbitol, mannitol and inositol, particularly preferably from 1,1,1-trimethylolpropane (2-ethyl2(hydroxymethyl)-1,3-propanediol, TMP) and all compounds of the group consisting of 1,2-pentanediol, 2-methyl-2-propyl-1,3-propanediol, 2-Butyl-2-ethyl-1,3-propanediol, glycerin, pentaerythritol, erythritol, xylitol, sorbitol, mannitol and inositol.

[0096] Preferably, the total amount of 1,1,1-trimethylolpropane, preferably of 1,1,1-trimethylolpropane and one or more of the compounds selected from the group consisting of 1,2-pentanediol, 2-methyl-2-propyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, glycerol, pentaerythritol, erythritol, xylitol, sorbitol, mannitol and inositol, particularly preferably of 1,1,1-trimethylolpropane and all compounds of the group consisting of 1,2-pentanediol, 2-methyl-2-propyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, glycerol, pentaerythritol, erythritol, xylitol, sorbitol, mannitol and inositol, in the rubber mixtures according to the invention is less than 0.1 phr, particularly preferably less than than 0.05 phr, most preferably less than 0.01 phr, most preferably less than 0.001 phr.

[0097] In the context of this invention, the at least one non-aromatic, polar substance having 4-12 carbon atoms serves to provide rubber mixtures which are less toxicologically harmful, compared to rubber mixtures of WO2010136345A1, in which the application-relevant properties, preferably the wet skid resistance and the rolling resistance, are equally good, and Mooney viscosity, scorch safety and filler dispersion are equally good, preferably better, than in the corresponding TMP-containing rubber mixtures.

[0098] Preferably, the at least one non-aromatic, polar substance having 4-12 carbon atoms in the context of the present invention is different from the other ingredients of the rubber mixture according to the invention, such as the at least one rubber, the at least one hydroxyl-containing oxidic filler, the at least one reinforcing additive from the series of sulfur-containing organic silanes, the at least one crosslinker from the series of sulfur and sulfur donors, the at least one fatty acid, the optional at least one vulcanization accelerator and the optional one or more rubber auxiliaries.

[0099] The at least one non-aromatic, polar substance having 4-12 carbon atoms is preferably contained in the rubber mixtures according to the invention in an amount of 0.1 - 10 phr, particularly preferably 0.2 - 8 phr, very particularly preferably 0.3 - 5 phr, most preferably 0.4 - 2 phr.

[0100] The rubber mixtures according to the invention contain at least one reinforcing additive from the series of sulfur-containing organic silanes.

[0101] Preferred sulfur-containing organic silanes are bifunctional sulfur-containing organic silanes which have at least one alkoxy, cycloalkoxy, or phenoxy group on the silicon atom and as other functionality a group selected from -SCN, -SH or -Sx- with x = 2 to 8.

[0102] Particularly preferred are sulfur-containing silanes containing alkoxysilyl groups and very particularly preferred are sulfur-containing organic silanes containing trialkoxysilyl groups.

[0103] Most preferably, the rubber mixtures according to the invention contain one or more sulfur-containing silanes from the series bis-(triethoxysilylpropyl)-tetrasulfane, bis-(triethoxysilylpropyl)-disulfane and 3-(triethoxysilyl)-1-propanethiol.

[0104] Liquid sulfur-containing silanes can be coated on a carrier (dry liquid) for improved dosing and / or dispersibility. The content of sulfur-containing silanes in these "dry liquids" is preferably between 30 and 70 parts by weight, particularly preferably between 40 and 60 parts by weight, per 100 parts by weight of dry liquid.

[0105] The rubber mixtures according to the invention generally contain 0.1 to 20 phr, preferably 0.5 to 15 phr and particularly preferably 1.0 to 10 phr of at least one reinforcing additive from the series of sulfur-containing organic silanes.

[0106] fatty acid

[0107] The rubber mixtures according to the invention contain at least one fatty acid.

[0108] Suitable fatty acids are naturally occurring and synthetic fatty acids and mixtures thereof. Preferred are saturated and unsaturated aliphatic straight-chain, branched, or cyclic carboxylic acids with a carbon number of 6 to 22, preferably 8 to 20, and mixtures thereof.

[0109] Examples include naturally occurring saturated fatty acids such as caproic acid (hexanoic acid), caprylic acid (octanoic acid), capric acid (decanoic acid), lauric acid (dodecanoic acid), myristic acid (tetradecanoic acid), palmitic acid (hexadecanoic acid), stearic acid (octadecanoic acid), arachidic acid (eicosanoic acid), behenic acid (docosanoic acid), lignoceric acid (tetracosanoic acid), and cerotic acid (hexacosanoic acid), as well as mixtures thereof. 2-Ethylhexanoic acid can also be used. Further examples are mono- or polyunsaturated fatty acids and mixtures thereof, such as myristoleic acid (9-tetradecenoic acid), palmitoleic acid (9-hexadecenoic acid), oleic acid (9-octadecenoic acid), vaccenic acid (11-octadecenoic acid), petroselinic acid (6-octadecenoic acid), gadoleic acid (9-eicosenoic acid), 11-eicosenoic acid, erucic acid (13-docosenoic acid), linoleic acid (9,12-octadecadienoic acid), linolenic acid (9,12,15-octadecatrienoic acid) and mixtures thereof.

[0110] Further examples are saturated or unsaturated hydroxy-substituted fatty acids, such as ricinoleic acid, as well as fatty acids with alicyclic side chains, especially cyclopentenyl fatty acids.

[0111] Mixtures of fatty acids are also suitable, such as those based on natural raw materials that arise, for example, during fatty acid cleavage, such as coconut, rapeseed and soy fatty acids, as well as their fractions, but also other technical mixtures that consist predominantly of fatty acids, such as tall oil fatty acids and in particular tallow fatty acids.

[0112] In a preferred embodiment, the at least one fatty acid is selected from palmitic acid and stearic acid, or mixtures thereof, particularly preferably stearic acid.

[0113] The rubber mixtures according to the invention contain the at least one fatty acid preferably in amounts of 0.3 - 15 phr, particularly preferably 0.5 - 10 phr, very particularly preferably 0.9 - 10 phr, most preferably 1.2 - 8 phr.

[0114] The rubber mixtures according to the invention contain the at least one non-aromatic, polar substance having 4-12 carbon atoms and the at least one fatty acid in a weight ratio preferably of 10:1 to 1:20, particularly preferably of 5:1 - 1:10, very particularly preferably of 2:1 - 1:10, most preferably of 1:1 - 1:6.

[0115] In a particularly preferred embodiment, the rubber mixtures according to the invention contain the at least one fatty acid in at least an equal amount based on the at least one non-aromatic, polar substance having 4-12 carbon atoms, preferably in a weight ratio of the at least one non-aromatic, polar substance having 4-12 carbon atoms to the at least one fatty acid of 1:1 - 1:20, very particularly preferably of 1:1 - 1:10, most preferably of 1:1 - 1:6.

[0116] The at least one non-aromatic, polar substance having 4-12 carbon atoms and the at least one fatty acid can be added to the rubber mixtures separately or together in the form of a mixture.

[0117] Preferably, the at least one non-aromatic, polar substance having 4-12 carbon atoms and the at least one fatty acid are added to the rubber mixtures in the form of a mixture containing them, the mixture A according to the invention.

[0118] The mixture A according to the invention contains at least one non-aromatic, polar substance with 4-12 carbon atoms, preferably with 5-10 carbon atoms, which:

[0119] Contains carbon, hydrogen and oxygen atoms, has a region of at least two chemically bonded carbon atoms, contains a hydroxyl group and at least one further oxygen-containing group selected from hydroxyl, ester, ether, acetal, ketal, aldehyde and carboxylic acid groups, wherein the hydroxyl group and the further oxygen-containing group are not more than 3 positions apart from each other along a molecular chain, and is different from 1,1,1-trimethylolpropane (TMP), to 10 - 40 wt.%, preferably to 20 - 35 wt.%, and the at least one fatty acid to 60 - 90 wt.%, preferably to 65 - 80 wt.%, based on the total amount of mixture A.

[0120] The descriptions and preferred ranges given above for the at least one non-aromatic, polar substance having 4-12 carbon atoms and the at least one fatty acid contained in the rubber mixtures according to the invention apply analogously to these components contained in mixture A.

[0121] Mixture A preferably consists of at least 80% by weight, particularly preferably at least 90% by weight, very particularly preferably at least 95% by weight of the at least one non-aromatic, polar substance having 4-12 carbon atoms and the at least one fatty acid, based on the total amount of mixture A.

[0122] Mixture A may further contain, for example, further processing aids, such as polyols, preferably polyethylene glycol, or extenders, etc., preferably in an amount of not more than 20% by weight, particularly preferably in an amount of not more than 10% by weight, very particularly preferably in an amount of not more than 5% by weight, based on the total amount of mixture A.

[0123] Mixture A contains the at least one non-aromatic, polar substance having 4-12 carbon atoms and the at least one fatty acid preferably in a weight ratio of 10:1 to 1:20, particularly preferably 5:1 - 1:10, very particularly preferably 2:1 - 1:5, most preferably 1:1 - 1:4.

[0124] In a particularly preferred embodiment, mixture A contains the at least one fatty acid in at least an equal amount based on the at least one non-aromatic, polar substance having 4-12 carbon atoms, preferably in a weight ratio of the at least one non-aromatic, polar substance having 4-12 carbon atoms to the at least one fatty acid of 1:1 - 1:20, very particularly preferably of 1:1 - 1:10, very particularly preferably of 1:1 - 1:5 and most preferably of 1:1 - 1:4.

[0125] The rubber mixtures according to the invention preferably contain the mixture A in an amount of 1 - 10 phr, particularly preferably 2 - 8 phr, very particularly preferably 2.5 - 6 phr.

[0126] The present invention further provides a process for preparing the mixtures A according to the invention, characterized in that the respective components are mixed in a mixing process.

[0127] Preferably, the at least one fatty acid and the at least one non-aromatic, polar substance having 4-12 carbon atoms and optionally further processing aids are mixed together in the general and preferred amounts mentioned.

[0128] Rubber auxiliaries

[0129] The rubber mixtures according to the invention may further contain one or more rubber auxiliaries. Examples of suitable rubber auxiliaries include anti-aging agents, coupling agents, heat stabilizers, light stabilizers, flame retardants, processing aids, impact modifiers, plasticizers, tackifiers, blowing agents, dyes, pigments, waxes, extenders, organic acids, retarders, and anti-reversion agents.

[0130] The rubber mixtures according to the invention may contain one or more anti-aging agents. Suitable anti-aging agents are amine-based agents such as diaryl-p-phenylenediamines (DTPD), octylated diphenylamine (ODPA), phenyl-anaphthylamine (PAN), and phenyl-ß-naphthylamine (PBN), preferably those based on phenylenediamine, e.g. B. 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) as well as phosphites such as tris-(nonylphenyl)phosphite, polymerized 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), methyl-2-mercapto-benzimidazole (MMBI) and zinc methylmercaptobenzimidazole (ZMMBI) and mixtures thereof.Particularly preferably, the at least one age-protecting agent is selected from the group consisting of N,N'-dicyclohexyl-p-phenylenediamine (CCPD), N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) and polymerized 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), most preferably N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) and polymerized 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ).

[0131] Processing aids are intended to act between the rubber particles and counteract frictional forces during mixing, plasticizing, and molding. The rubber mixtures according to the invention can contain all lubricants customary for processing plastics as processing aids, such as hydrocarbons, such as oils (e.g., aromatic process oils), paraffins and PE waxes, fatty alcohols with 6 to 20 carbon atoms, ketones, carboxylic acids (such as fatty acids and montanic acids), oxidized PE wax, aromatically modified cycloaliphatic hydrocarbon resins, metal salts of carboxylic acids, carboxylic acid amides, and carboxylic acid esters.

[0132] To reduce flammability and smoke development during combustion, the rubber mixtures according to the invention can contain flame retardants. Examples of flame retardants used include antimony trioxide, phosphoric acid esters, chlorinated paraffin, aluminum hydroxide, boron compounds, zinc compounds (except ZnO), molybdenum trioxide, ferrocene, calcium carbonate, or magnesium carbonate.

[0133] Before crosslinking, other plastics can also be added to the rubber mixtures according to the invention, which act, for example, as polymeric processing aids or impact strength improvers. These plastics are preferably selected from the group consisting of homo- and copolymers based on ethylene, propylene, butadiene, styrene, methylstyrene, coumarene, indene, vinyl acetate, vinyl chloride, glycidyl acrylate, glycidyl methacrylate, acrylates and methacrylates with alcohol components of branched or unbranched C1 to C10 alcohols, with polyacrylates with identical or different alcohol radicals from the group of C4 to C8 alcohols, in particular butanol, hexanol, octanol and 2-ethylhexanol, polymethyl methacrylate, methyl methacrylate-butyl acrylate copolymers, methyl methacrylate-butyl methacrylate copolymers, ethylene-vinyl acetate copolymers, chlorinated polyethylene, ethylene-propylene copolymers, ethylene-propylene-diene copolymers being particularly preferred.

[0134] Known adhesives based on resorcinol, formaldehyde, and silica, the so-called RFS direct adhesion systems, are used. These direct adhesion systems can be used in any amount of the rubber mixture according to the invention at any time during mixing into the rubber mixtures according to the invention.

[0135] In addition, the rubber mixtures according to the invention may contain at least one vulcanization retarder.

[0136] Suitable vulcanization retarders include, for example, sulfenamide retarders from the group of sulfenamide retarders based on acidic compounds such as phthalic acid, phthalic anhydride, benzoic acid or salicylic acid, and the group of / V-nitroso compounds based on diphenylamine or trimethyldihydroquinoline.

[0137] Preferably, the at least one vulcanization retarder is selected from the group consisting of sulfenamide retarders, very particularly preferably selected from N-cyclohexylthiophthalimide and N-phenyl-N-(trichloromethylsulfenyl)benzenesulfonamide, most preferably N-cyclohexylthiophthalimide. Typical amounts for the at least one vulcanization retarder are 0.01-10 phr.

[0138] The rubber auxiliaries contained in the mixture according to the invention are preferably different from the other ingredients of the rubber mixture according to the invention, such as the at least one rubber, the at least one hydroxyl-containing oxidic filler, the at least one reinforcing additive from the series of sulfur-containing organic silanes, the at least one crosslinker from the series of sulfur and sulfur donors, the at least one fatty acid, the optional at least one vulcanization accelerator and the at least one non-aromatic, polar substance having 4-12 carbon atoms.

[0139] The rubber auxiliaries can be added to the rubber mixtures according to the invention in the amounts customary for these auxiliaries, which also depend on the intended use of the vulcanizates produced therefrom. Typical amounts are, for example, 0.1 to 30 phr.However, if a rubber auxiliary overlaps with one of the other ingredients of the rubber mixtures according to the invention, for example the at least one rubber, the at least one hydroxyl-containing oxidic filler, the at least one reinforcing additive from the series of sulfur-containing organic silanes, the at least one crosslinker from the series of sulfur and sulfur donors, the at least one fatty acid, the optional at least one vulcanization accelerator and / or the at least one non-aromatic, polar substance with 4-12 carbon atoms, this rubber auxiliary is preferably only contained in the rubber mixture according to the invention as a supplement to the general and preferred quantities specified for this other ingredient.

[0140] Particularly preferred rubber mixtures according to the invention are those containing

[0141] 50 to 100 phr of at least one functionalized synthetic rubber, preferably 70 - 100 phr, preferably of a functionalized BR rubber and / or functionalized SBR rubber,

[0142] 0 to 50 phr of at least one natural rubber and / or unfunctionalized synthetic rubber, preferably 0 to 30 phr,

[0143] 20 to 200 phr of at least one hydroxyl-containing oxidic filler, 0.5 to 15 phr of at least one reinforcing additive from the group of sulfur-containing organic silanes, preferably bifunctional sulfur-containing organic silanes which have at least one alkoxy, cycloalkoxy, or phenoxy group on the silicon atom and as other functionality a group selected from -SCN, -SH or -Sx- with x = 2 to 8, particularly preferably alkoxysilyl-containing sulfur-containing silanes and very particularly preferably trialkoxysilyl-containing sulfur-containing organic silanes,

[0144] 0.1 to 120 phr of at least one carbon black, preferably 0.1 to 100 phr,

[0145] 0.5 to 10 phr of at least one crosslinker from the series sulfur donor and sulfur,

[0146] 0.1 to 10 phr zinc oxide,

[0147] 0.1 to 10 phr of at least one vulcanization accelerator,

[0148] 0.3 to 15 phr of the at least one fatty acid, preferably from 0.5 to 10 phr, particularly preferably from 0.9 to 10 phr, most preferably from 1.2 to 8 phr, and

[0149] 0.1 to 10 phr of the at least one non-aromatic, polar substance having 4-12 carbon atoms, preferably having 5-10 carbon atoms, preferably 0.2 - 8 phr, particularly preferably 0.3 - 5 phr, very particularly preferably 0.4 - 2 phr. Very particular preference is given to the aforementioned rubber mixtures according to the invention in which the at least one non-aromatic, polar substance having 4-12 carbon atoms and the at least one fatty acid are present in a weight ratio preferably of 10:1 to 1:20, particularly preferably of 5:1 - 1:10, very particularly preferably of 2:1 - 1:10, most preferably of 1:1 - 1:6.

[0150] The above-mentioned further preferred ranges of the individual components also apply to these preferred mixtures.

[0151] Process for producing rubber mixtures

[0152] A further subject of the present invention is a process for producing the rubber mixtures according to the invention, characterized in that the respective components are mixed in a mixing process.

[0153] Preferably, at least one rubber is mixed together in the presence of at least one hydroxyl-containing oxidic filler, at least one reinforcing additive from the group of sulfur-containing organic silanes, optionally at least one vulcanization accelerator, at least one fatty acid, at least one non-aromatic, polar substance having 4-12 carbon atoms and optionally further rubber auxiliaries in the stated general and preferred amounts at a temperature in the range from 50 to 180°C, particularly preferably 60 to 170°C.

[0154] The rubber mixtures according to the invention are produced in the usual way in known mixing units, such as rollers, internal mixers, downstream mixing mills and mixing extruders at shear rates of 1 to 1000 see 1 .

[0155] The rubber mixtures according to the invention are preferably produced in a three-stage mixing process.

[0156] Preferably, in a first mixing stage, rubber, the fillers and optionally further rubber auxiliaries mentioned above, preferably anti-aging agents, and optionally the at least one vulcanization accelerator, preferably the guanidine-containing vulcanization accelerator, the at least one fatty acid and the at least one non-aromatic, polar substance having 4-12 carbon atoms and optionally further rubber auxiliaries are incorporated into the rubber in an internal mixer (kneader).Preferably, the at least one rubber, the at least one hydroxyl-containing oxidic filler, the at least one reinforcing additive from the group of sulfur-containing organic silanes, optionally the at least one vulcanization accelerator, preferably the guanidine-containing vulcanization accelerator, the at least one fatty acid and the at least one non-aromatic, polar substance having 4-12 carbon atoms and optionally further rubber auxiliaries are mixed in the first mixing stage in the process for producing the rubber mixtures according to the invention.

[0157] Mixing temperatures in the internal mixer can reach values ​​of up to 180°C. The temperature in the first mixing stage is preferably 130 to 180°C, particularly preferably 140 to 170°C.

[0158] The second step is preferably the so-called post-tweezing, preferably at 130-180°C, particularly preferably at 160°C. Post-tweezing can be carried out, for example, in an internal mixer.

[0159] Preferably, in a third mixing stage, at least one crosslinker from the group consisting of sulfur and sulfur donor, as well as optionally at least one further vulcanization accelerator and optionally further rubber auxiliaries, are added to the rubber mixture obtained from the second mixing stage. The temperature in the third mixing stage is preferably 50-130°C, particularly preferably 60-120°C.

[0160] The addition of the at least one non-aromatic, polar substance having 4-12 carbon atoms can take place at any time during the mixing, preferably in the first mixing stage at a temperature in the range of 130°C to 180°C, preferably at a temperature of 140 to 170°C.

[0161] In a particularly preferred embodiment of the process for producing the rubber mixtures according to the invention,

[0162] - firstly the at least one rubber, the at least one hydroxyl group-containing oxidic filler, the at least one reinforcing additive from the group of sulfur-containing organic silanes, optionally the at least one vulcanization accelerator, preferably the guanidine-containing vulcanization accelerator, the at least one fatty acid and the at least one non-aromatic, polar substance with 4-12 carbon atoms and optionally further rubber auxiliaries are mixed, preferably at 130 to 180°C, - then the resulting mixture is subjected to post-lasting, preferably at 130 - 180°C, particularly preferably at 160°C, and subsequently the at least one crosslinker from the series sulfur and sulfur donor and optionally the at least one further vulcanization accelerator and optionally further rubber auxiliaries are added to the resulting rubber mixture, preferably at 50 - 130°C.

[0163] Process for producing rubber vulcanizates

[0164] The present invention further relates to a process for producing rubber vulcanizates, characterized in that the rubber mixture according to the invention is heated at temperatures of 120 to 200°C, preferably at 140 to 180°C.

[0165] The process for producing the rubber vulcanizates according to the invention can be carried out in a wide pressure range, preferably it is carried out at a pressure in the range of 10 to 200 bar.

[0166] The present invention further relates to rubber vulcanizates which are obtainable by vulcanization of the rubber mixtures according to the invention.

[0167] The rubber vulcanizates according to the invention are suitable for the production of all types of molded articles, such as tire components, technical rubber articles such as damping elements, roller coverings, conveyor belt coverings, belts, spinning cops, seals, golf ball cores, shoe soles. They are particularly suitable for the production of tires and tire parts, such as tire treads, subtreads, carcasses, tire sidewalls, reinforced sidewalls for runflat tires, and apex compounds. Tire treads also include treads for summer, winter, and all-season tires, as well as treads for passenger car, truck, and light truck tires.

[0168] Preferred molded articles are tires and tire parts containing a rubber vulcanizate according to the invention.

[0169] Another object of the present invention is the use of at least one non-aromatic, polar substance having 4-12 carbon atoms, preferably 5-10 carbon atoms, which:

[0170] Contains carbon, hydrogen and oxygen atoms, has a region of at least two chemically bonded carbon atoms, contains a hydroxyl group and at least one further oxygen-containing group selected from hydroxyl, ester, ether, acetal, ketal, aldehyde and carboxylic acid groups, wherein the hydroxyl group and the further oxygen-containing group are not more than 3 positions apart from each other along a molecular chain, and is different from 1,1,1-trimethylolpropane (TMP), in sulfur-crosslinkable rubber mixtures for improving the processability of the rubber mixtures and for improving the filler dispersion in the rubber mixtures.

[0171] Most preferred is the use of at least one non-aromatic, polar substance having 4-12 carbon atoms, preferably 5-10 carbon atoms, which:

[0172] Contains carbon, hydrogen and oxygen atoms, has a region of at least two chemically bonded carbon atoms, contains a hydroxyl group and at least one further oxygen-containing group selected from hydroxyl, ester, ether, acetal, ketal, aldehyde and carboxylic acid groups, wherein the hydroxyl group and the further oxygen-containing group are not more than 3 positions apart from one another along a molecular chain, and is different from 1,1,1-trimethylolpropane (TMP), in an amount of 0.1 - 10 phr, preferably 0.2 - 8 phr, particularly preferably 0.3 - 5 phr, very particularly preferably 0.4 - 2 phr, in sulfur-crosslinkable rubber mixtures for improving the processability of the rubber mixtures and for improving the filler dispersion in the rubber mixtures.In a particularly preferred embodiment, the use of the at least one non-aromatic, polar substance having 4-12 carbon atoms, preferably 5-10 carbon atoms, and the at least one fatty acid in a weight ratio preferably of 10:1 to 1:20, particularly preferably of 5:1 - 1:10, very particularly preferably of 2:1 - 1:10, most preferably of 1:1 - 1:6, in sulfur-crosslinkable rubber mixtures to improve the processability of the rubber mixtures and to improve the filler dispersion in the rubber mixtures.

[0173] The present invention also relates to the use of the mixture A according to the invention, preferably in an amount of 1-10 phr, particularly preferably of 2-8 phr, very particularly preferably of 2.5-6 phr, in sulfur-crosslinkable rubber mixtures to improve the processability of the rubber mixtures.

[0174] The descriptions and preferred ranges given for the components contained and optionally contained in the rubber mixture according to the invention apply analogously to, among other things, the disclosed processes and uses as well as the vulcanizates and moldings.

[0175] The descriptions and preferred areas given also apply to, among others, the rubber mixtures according to the invention, mixture A, vulcanizates, moldings, processes and uses, regardless of whether they were disclosed for the aforementioned in the plural (e.g. rubber mixtures) or in the singular (e.g. rubber mixture).

[0176] The invention will be explained with reference to the following examples, but is not limited thereto.

[0177] Implementation examples

[0178] Table 1 : List of ingredients, abbreviations and manufacturers

[0179] TMP / fatty acid: mixture of 70 wt% stearic acid, 25 wt% TMP, 5 wt% polyethylene glycol, based on the total weight of the mixture; NPG / fatty acid: mixture of 70 wt% stearic acid, 25 wt% NPG, 5 wt% polyethylene glycol, based on the total weight of the mixture; HPN / fatty acid: mixture of 70 wt% stearic acid, 25 wt% HPN, 5 wt% polyethylene glycol, based on the total weight of the mixture.

[0180] Production of rubber vulcanizates

[0181] The rubber mixtures according to the invention (Examples 1 and 2) and the non-inventive reference mixture (Example 3) were prepared according to the recipes given in Table 2. Example 3 was prepared based on WO2010136345A1.

[0182] All rubber compounds in the examples contain identical amounts of the starting materials and differ only in the presence of TMP, NPG and HPN.

[0183] The rubber compounds were produced in the following steps:

[0184] 1. Mixing stage:

[0185] ■ NIPOL® BR1261 and SPRINTAN® SLR 3402 are placed in an internal mixer and mixed for approximately 30 seconds.

[0186] ■ Add half of Zeosil®1165MP and mix Sl® 75 for about 60 seconds.

[0187] ■ Add half of Zeosil®1165MP, CORAX®N 234, as well as stearic acid, Vulkanox® 4020, Vulkanox® HS, Antilux® 654, Vivatec 500, Escorez® 5600, RHENOGRAN® DPG-80, and the respective polyol / fatty acid mixture. Mix for approximately 60 seconds, then sweep. Mix until a temperature of 160 °C is reached, then mix for 4 minutes at 160 °C.

[0188] After the first mixing stage, the mixed material is taken up by a downstream rolling mill and formed into a sheet, strip, or pellet. It is then stored at room temperature for 24 hours. Processing temperatures are 70°C.

[0189] 2nd mixing stage:

[0190] This was followed by mixing in an internal mixer until a temperature of 160°C was reached (the so-called post-tweezing). After the second mixing stage, the mixed piece is taken up by a downstream rolling mill and formed into a sheet, strip, or pellet, and stored at room temperature for 24 hours.

[0191] 3rd mixing stage: The addition of sulfur, zinc oxide and the vulcanization accelerator Rhenogran® CBS-80 took place in the internal mixer for 2 minutes at 100 °C.

[0192] After the third mixing stage, the mixture is formed into a sheet, strip, or pellet using a rolling mill and stored at room temperature for 24 hours. Processing temperatures are 70°C. Table 2: Components of the rubber mixtures according to the invention and the reference mixture.

[0193] Quantities in phr (parts by weight per 100 parts of rubber)

[0194] Technical inspection

[0195] The vulcanizates produced at 160°C from the rubber compounds of Examples 1-3 were subjected to the technical tests specified below. The results are shown in Table 3.

[0196] The following procedures were used for testing the rubber compounds and test specimens:

[0197] M oo ney-Vi s kos ity m ess ung

[0198] The determination was carried out using a shear disc viscometer in accordance with ASTM D 1646. Viscosity can be determined directly from the force that rubbers and rubber compounds exert during processing. In the Mooney shear disc viscometer, a ribbed disc is enclosed at the top and bottom with sample substance and rotated in a heated chamber at approximately two revolutions per minute. The force required for this is measured as torque and corresponds to the respective viscosity. The sample is usually preheated to 100°C for one minute; the measurement lasts a further four minutes, during which the temperature is kept constant. The viscosity is specified together with the respective test conditions, for example, ML (1+4) 100°C (Mooney viscosity, rotor size L, preheating time and test time in minutes, test temperature).

[0199] Mooney-Scorch measurement

[0200] The Mooney Scorch test is a standardized test used to characterize the pre-vulcanization behavior of a rubber sample at elevated temperatures. It determines the time after which the viscosity increases by a specified value, in this case by 5 or 10 Mooney units (Ts05 or Ts10). The determination was performed using a shear disk viscometer according to ASTM D 1646 at 130°C. Rheometer (vulcameter) used and pre-vulcanization / complete curing time.

[0201] The vulcanization process on the MDR (moving die rheometer) and its analytical data were measured using a Monsanto MDR 2000 rheometer according to ASTM D5289-95. The vulcanization time at 160°C was 15 minutes.

[0202] The value of Delta S' is calculated from the difference between the highest and the lowest value of the rheometer curve, therefore Sm ax - Smin.

[0203] Determination of elongation at break, tensile strength, modulus 50, 100, 300

[0204] These measurements were carried out according to DIN 53504 (tensile test, bar S2, 5-fold measurement).

[0205] Determination of Shore A hardness

[0206] The Shore hardness (Shore A) was measured according to DIN 53505 at 23 °C (triple measurement).

[0207] Rebound resilience

[0208] The rebound resilience was measured at 23 °C (triple measurement) according to DIN 53512.

[0209] Determination of the loss factor

[0210] The loss factor tan ö was determined at 0°C and 60°C and a measuring frequency of 10 Hz according to dynamic damping DIN 53513.

[0211] Determination of the Payne effect

[0212] Amplitude sweep (amplitude of deformation is varied) from 0.5% to 15% at 60 °C and 10 Hz. The Payne effect (delta G') is the difference between G' at 0.5% amplitude and G' at 15% amplitude.

[0213] Table 3: Results of the technical tests

[0214] Conclusion

[0215] If the inventive mixtures NPG / fatty acid (Example 1) or HPN / fatty acid (Example 2) are used in the rubber mixtures according to the invention instead of TMP / fatty acid, lower Mooney viscosities are achieved in all three mixing stages and thus mixtures are easier to process than in the analogous rubber mixture containing TMP (Example 3, comparison). At the same time, the polar filler silica is better dispersed in both inventive mixtures, as can be seen from the reduced Payne effect (delta G') in Examples 1 and 2. Scorching reliability also increases when using the inventive mixtures, which can be seen from the extended Ts05 and Ts10, thereby expanding the time window for reliable processing. The other application-relevant properties remain the same or even improve slightly.

Claims

1. Rubber mixtures containing at least one rubber, at least one hydroxyl-containing oxidic filler, at least one reinforcing additive from the series of sulfur-containing organic silanes, at least one crosslinker from the series of sulfur and sulfur donors, and at least one fatty acid, wherein at least one non-aromatic, polar substance with 4-12 carbon atoms, preferably with 5-10 carbon atoms, is further contained, which: Contains carbon, hydrogen and oxygen atoms, has a region of at least two chemically bonded carbon atoms, contains a hydroxyl group and at least one further oxygen-containing group selected from hydroxyl, ester, ether, acetal, ketal, aldehyde and carboxylic acid groups, wherein the hydroxyl group and the further oxygen-containing group are not more than 3 positions apart along a molecular chain, and is different from 1,1,1-trimethylolpropane (TM P).

2. Rubber mixture according to claim 1, characterized in that the at least one rubber is selected from the group consisting of natural rubber and synthetic rubbers, preferably at least one functionalized synthetic rubber, particularly preferably at least one functionalized synthetic rubber selected from the group consisting of functionalized SBR, functionalized BR and functionalized IR rubber, very particularly preferably from functionalized SBR and functionalized BR rubber.

3. Rubber mixture according to one of claims 1 or 2, characterized in that the at least one hydroxyl-containing oxidic filler is selected from the group consisting of silicas, synthetic silicates and natural silicates, and is contained in the rubber mixture in an amount of 0.1 to 250 phr, preferably 20 to 200 phr, particularly preferably 50 to 180 phr, very particularly preferably 110 - 160 phr.

4. Rubber mixture according to one of claims 1-3, characterized in that the at least one non-aromatic, polar substance having 4-12 carbon atoms contains a hydroxyl group and at least one further oxygen-containing group selected from hydroxyl, ester and ether groups, preferably selected from hydroxyl and ester groups, wherein the hydroxyl group and the further oxygen-containing group are not more than 3 positions apart from each other along a molecular chain, particularly preferably a hydroxyl group and at least one further hydroxyl group and optionally an ester group.

5. Rubber mixture according to one of claims 1-4, characterized in that the at least one non-aromatic, polar substance having 4-12 carbon atoms is selected from the group consisting of diethylene glycol, dipropylene glycol, 2-sec-butyl-2-methyl-1,3-propanediol, 2,2'-oxydi-1-propanol, 1,1'-oxydi-2-propanol, 2-(2-hydroxypropoxy)-1-propanol, 2-methyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, trimethylolethane, ditrimethylolpropane, 2,2,2',2',-tetrakis(hydroxymethyl)-3,3'-oxydipropan-1-ol (dipentaerythritol), 2,2-Dimethylpropane-1,3-diol (CAS No. 126-30-7) and hydroxypivalic acid neopentyl glycol ester (2,2-dimethyl-1,3-propanediol mono-(hydroxy-pivalate), CAS No: 1115-20-4), particularly preferably selected from dipropylene glycol, 2-sec-butyl-2-methyl-1,3-propanediol, 2,2,2',2',-tetrakis(hydroxymethyl)-3,3'-oxydipropan-1-ol (dipentaerythritol), 2,2-Dimethylpropane-1,3-diol (CAS No.126-30-7) and hydroxypivalic acid neopentyl glycol ester (2,2-dimethyl-1,3-propanediol mono-(hydroxypivalate), CAS No: 1115-20-4), most preferably selected from 2,2-dimethylpropane-1,3-diol (CAS No: 126-30-7) and hydroxypivalic acid neopentyl glycol ester (2,2-dimethyl-1,3-propanediol mono-(hydroxypivalate), CAS No: 1115-20-4).

6. Rubber mixture according to one of claims 1-5, characterized in that the at least one non-aromatic, polar substance having 4-12 carbon atoms is contained in the rubber mixture in an amount of 0.1 - 10 phr, preferably 0.2 - 8 phr, particularly preferably 0.3 - 5 phr, most particularly preferably 0.4 - 2 phr.

7. Rubber mixture according to one of claims 1-6, characterized in that the at least one fatty acid is selected from saturated and unsaturated aliphatic straight-chain, branched or cyclic carboxylic acids having a carbon number of 6 to 22, preferably 8 to 20, and Mixtures thereof, preferably selected from palmitic acid and stearic acid, or mixtures thereof, particularly preferably stearic acid.

8. Rubber mixture according to one of claims 1-7, characterized in that the at least one fatty acid is present in an amount of 0.3-15 phr, preferably 0.5-10 phr, particularly preferably 0.9-10 phr, most particularly preferably 1.2-8 phr.

9. Rubber mixture according to one of claims 1-8, characterized in that it 50 to 100 phr of at least one functionalized synthetic rubber, preferably 70 - 100 phr, preferably of a functionalized BR rubber and / or functionalized SBR rubber, 0 to 50 phr of at least one natural rubber and / or unfunctionalized synthetic rubber, preferably 0 to 30 phr, 20 to 200 phr of at least one hydroxyl-containing oxidic filler, 0.5 to 15 phr of at least one reinforcing additive from the group of sulfur-containing organic silanes, preferably bifunctional sulfur-containing organic silanes which have at least one alkoxy, cycloalkoxy, or phenoxy group on the silicon atom and as other functionality a group selected from -SCN, -SH or -Sx- with x = 2 to 8, particularly preferably alkoxysilyl-containing sulfur-containing silanes and very particularly preferably trialkoxysilyl-containing sulfur-containing organic silanes, 0.1 to 120 phr of at least one carbon black, preferably 0.1 to 100 phr, 0.5 to 10 phr of at least one crosslinker from the series sulfur donor and sulfur, 0.1 to 10 phr zinc oxide, 0.1 to 10 phr of at least one vulcanization accelerator, 0.3 to 15 phr of at least one fatty acid, preferably from 0.5 to 10 phr, particularly preferably from 0.9 to 10 phr, most preferably from 1.2 to 8 phr, and 0.1 to 10 phr of at least one non-aromatic, polar substance having 4-12 carbon atoms, preferably having 5-10 carbon atoms, preferably 0.2 - 8 phr, particularly preferably 0.3 - 5 phr, most particularly preferably 0.4 - 2 phr.

10. Mixture A, containing at least one non-aromatic, polar substance having 4-12 carbon atoms, preferably having 5-10 carbon atoms, which: Contains carbon, hydrogen and oxygen atoms, has a region of at least two chemically bonded carbon atoms, contains a hydroxyl group and at least one further oxygen-containing group selected from hydroxyl, ester, ether, acetal, ketal, aldehyde and carboxylic acid groups, wherein the hydroxyl group and the further oxygen-containing group are not more than 3 positions apart from each other along a molecular chain, and is different from 1,1,1-trimethylolpropane (TM P), at 10-40% by weight, preferably at 20-35% by weight, and at least one fatty acid at 60-90% by weight, preferably at 65-80% by weight, based on the total amount of mixture A.

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

12. Vulcanizates obtainable by vulcanization of rubber mixtures according to one of claims 1 to 9.

13. Shaped articles, preferably technical rubber articles and tires, containing one or more rubber vulcanizates according to claim 12.

14. Use of at least one non-aromatic, polar substance having 4-12 carbon atoms, preferably having 5-10 carbon atoms, which: Contains carbon, hydrogen and oxygen atoms, has a region of at least two chemically bonded carbon atoms, contains a hydroxyl group and at least one further oxygen-containing group selected from hydroxyl, ester, ether, acetal, ketal, aldehyde and carboxylic acid groups, wherein the hydroxyl group and the further oxygen-containing group are not more than 3 positions apart along a molecular chain, and is different from 1,1,1-trimethylolpropane (TM P), in an amount of 0.1 - 10 phr, preferably 0.2 - 8 phr, particularly preferably 0.3 - 5 phr, most preferably 0.4 - 2 phr, in sulfur-crosslinkable rubber mixtures to improve the processability of the rubber mixtures and to improve the filler dispersion in the Rubber compounds.

15. Use of the mixture A according to claim 10, preferably in an amount of 1 - 10 phr, particularly preferably 2 - 8 phr, most preferably 2.5 - 6 phr, in sulfur-curable rubber compounds to improve the processability of the rubber compounds and to improve the Filler dispersion in the rubber compounds.

Images