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EP-4739514-A1 - RUBBER MIXTURES CONTAINING POLYETHYLENEIMINE AND AT LEAST ONE PROCESSING AID CONTAINING AT LEAST ONE FATTY ACID

EP4739514A1EP 4739514 A1EP4739514 A1EP 4739514A1EP-4739514-A1

Abstract

The invention relates to rubber mixtures containing at least one rubber, at least one hydroxyl group-containing oxidic filler, at least one reinforcing additive from the series of sulfur-containing organic silanes, at least one crosslinking agent from the series of sulfur and sulfur donors, at least one vulcanisation accelerator containing polyethyleneimine, at least one processing aid containing at least one fatty acid, wherein the total content of diphenylguanidine (DPG), di-ortho-tolylguanidine (DOTG) and 1-(ortho-tolyl)biguanide in the rubber mixture is at most 0.4 phr, preferably at most 0.2 phr, particularly preferably at most 0.1 phr and very particularly preferably at most 0.01 phr, the production and use thereof, and the vulcanised products obtainable thereby by the vulcanisation process, in particular in the form of tyres, parts of tyres, or technical rubber articles.

Inventors

  • Albers, Antonia
  • WEIDENHAUPT, HERMANN-JOSEF
  • OPRISONI, Cristian

Assignees

  • LANXESS Deutschland GmbH

Dates

Publication Date
20260513
Application Date
20240702

Claims (15)

  1. 1 . Rubber mixture containing - at least one rubber, - at least one hydroxyl-containing oxidic filler, - at least one reinforcing additive from the series of sulphur-containing organic silanes, - at least one crosslinker from the series sulphur and sulphur donor, - at least one vulcanization accelerator containing polyethyleneimine, and - at least one processing aid containing at least one fatty acid, wherein the total content of diphenylguanidine (DPG), di-ortho-tolyl-guanidine (DOTG) and 1-(ortho-tolyl)biguanide in the rubber mixture is a maximum of 0.4 phr, preferably a maximum of 0.2 phr, particularly preferably a maximum of 0.1 phr and very particularly preferably a maximum of 0.01 phr.
  2. 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. 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 25 to 180 phr, very particularly preferably 30 - 160 phr.
  4. 4. Rubber mixture according to one of claims 1 -3, characterized in that the at least one fatty acid is selected from - fatty acids CnHznOz with n = 10 - 30, preferably from CnHznOz with n = 12 - 22, particularly preferably from CnHznOz with n = 10, 12, 14, 16 and 18, very particularly preferably from CnHznOz with n = 16 or n = 18, and - Fatty acids CnHzn-xOz with x = an even number greater than or equal to 2 and less than or equal to 10 and n = 10 - 30, preferably from CnHzn-xOz with x = an even number greater than or equal to 2 and less than or equal to 10 and n = 12 - 22, particularly preferably from CnHzn-xOz with x = an even number which is 2 or 4, and n = 16 or n = 18, very particularly preferably from CnHzn-xOz with x = 2 and n = 16 or 18, or CnHzn-xOz with x = 4 and n = 18.
  5. 5. Rubber mixture according to one of claims 1 - 4, characterized in that the at least one fatty acid is contained in the at least one processing aid in an amount of 40 - 85 wt. %, preferably 55 - 80 wt. %, wherein the wt. % is based on the total amount of the at least one processing aid.
  6. 6. Rubber mixture according to one of claims 1 - 5, characterized in that the rubber mixture contains 0.1 - 30 phr, preferably 0.5 - 25 phr, particularly preferably 1 - 15 phr, very particularly preferably 5 - 15 phr, of at least one processing aid, containing - 40 - 85 wt.%, preferably 55 - 80 wt.%, of at least one fatty acid selected from - fatty acids CnHznOz with n = 10 - 30, and - fatty acids CnHzn-xOz with x = an even number greater than or equal to 2 and less than or equal to 10 and n = 10 - 30, wherein at least 80% by weight, preferably at least 90% by weight, very particularly preferably at least 95% by weight, based on the total amount of the at least one fatty acid, is attributable to at least one fatty acid selected from fatty acids CnHznOz with n = 10 - 30, preferably from CnHznOz with n = 12 - 22, particularly preferably from CnHznOz with n = 10, 12, 14, 16 and 18, very particularly preferably from CnHznOz with n = 16 or n = 18, - 5-50 wt.%, preferably 8-25 wt.%, of at least one alcohol selected from CnHznO with n = 10-26 and 1,1,1-trimethylolpropane (TMP), - 5-20 wt.%, preferably 8-15 wt.% of at least one ester selected from Dodecanoic acid stearyl ester, myristic acid stearyl ester, palmitic acid stearyl ester, Palmitic acid docosyl ester, stearyl stearate, eicosyl stearate, stearic acid tetradecyl ester, stearic acid docosyl ester and arachidic acid docosyl ester, and - 1-10 wt.%, preferably 1-5 wt.%, polyethylene glycol, wherein the wt.% is based on the total amount of the at least one processing aid.
  7. 7. Rubber mixture according to one of claims 1-6, characterized in that the rubber mixture contains 0.01 to 10 phr, particularly preferably 0.1 - 5 phr and very particularly preferably 0.2 to 2.5 phr of the vulcanization accelerator polyethyleneimine.
  8. 8. Rubber mixture according to one of claims 1-7, characterized in that the total content of guanidine-containing compounds in the rubber mixture is at most 0.4 phr, preferably at most 0.2 phr, particularly preferably at most 0.1 phr and most preferably at most 0.01 phr.
  9. 9. Rubber mixture according to claim 1, characterized in that the rubber mixture - 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 sulfur-containing silanes containing alkoxysilyl groups and very particularly preferably sulfur-containing organic silanes containing trialkoxysilyl groups, - 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 sulphur donor and sulphur, - 0.1 to 10 phr zinc oxide, - 0.1 to 10 phr of at least one vulcanization accelerator containing polyethyleneimine, and - 0.1 to 30 phr of at least one processing aid, preferably 0.5 - 25 phr, particularly preferably 1 - 15 phr, very particularly preferably 5 - 15 phr, containing at least one fatty acid.
  10. 10. Rubber mixture according to one of claims 1-9, characterized in that the rubber mixture contains at least one vulcanization retarder, preferably 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, preferably in an amount of 0.01-10 phr, more preferably 0.05-5 phr, very particularly preferably 0.1-1 phr, most preferably 0.1-0.5 phr.
  11. 1 1. Process for producing the rubber mixtures according to the invention according to one of claims 1 -10, characterized in that the respective components are mixed in a mixing process.
  12. 12. Process according to claim 11, characterized in that in the process for producing the rubber mixture - firstly, the at least one rubber, the at least one hydroxyl-containing oxidic filler, the at least one reinforcing additive from the group of sulphur-containing organic silanes, the vulcanisation accelerator polyethyleneimine and the at least one processing aid and optionally further rubber aids are mixed, preferably at 130 to 180°C, and - then at least one crosslinker from the series sulfur and sulfur donor and optionally at least one further vulcanization accelerator and optionally further rubber auxiliaries are added to the rubber mixture obtained, preferably at 50 - 130°C.
  13. 13. Vulcanizates obtainable by vulcanization of rubber mixtures according to one of claims 1 to 10.
  14. 14. Shaped articles, preferably technical rubber articles and tires, containing one or more rubber vulcanizates according to claim 13.
  15. 15. Use of polyethyleneimine, preferably in an amount of 0.01 to 10 phr, particularly preferably 0.1 to 5 phr, very particularly preferably 0.2 to 2.5 phr, and of at least one processing aid containing at least one fatty acid, preferably in an amount of 0.1 to 30 phr, particularly preferably 1 to 15 phr, very particularly preferably 5 to 15 phr, in sulfur-crosslinkable rubber mixtures, the vulcanizates obtainable therefrom and the moldings obtainable therefrom, for treating, preferably improving, the conflicting objectives of rolling resistance/wet braking.

Description

Rubber mixtures containing polyethyleneimine and at least one processing aid containing at least one fatty acid 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 vulcanization accelerator containing polyethyleneimine, and at least one processing aid containing at least one fatty acid, their production 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. The vulcanization of natural rubber created a new material whose unique property profile contributed significantly to the development of modern technology. At the beginning of the 20th century, the accelerating effect of basic organic compounds on vulcanization was recognized. For example, aniline and other nitrogen-containing organic compounds such as hexamethylenetetramine or thiocarbanilide have been used as accelerators. Sulfur is often used to crosslink rubber mixtures. In general, crosslinking rubbers with sulfur accelerator systems offers the advantage that the use of different accelerators and their combinations allows the processing and product properties to be varied over a wide range, such as the setting of the induction period (scorch time), which should not be too short, and the reaction speed, which is preferably high and thus leads to a short vulcanization time. So-called secondary accelerators can be added to the rubber mixtures to regulate the induction and vulcanization time. Guanidine accelerators are among the best-known secondary accelerators. They are slow-acting accelerators that can be used to adjust the scorch and/or cure time. The stress value characteristic as an indicator of the vulcanization progress of rubber compounds with guanidine accelerators is typically characterized by a slow increase and relatively late reaching of the maximum. These accelerators, when used alone, usually lead to a relatively unfavorable flow time/heating time ratio and to a relatively strong reversion in the rubber vulcanizate. To avoid these disadvantages, they are often used in combination with primary accelerators, such as sulfenamide-based accelerators. Accelerators are usually added in processes for producing rubber compounds in the last mixing stage together with sulfur, as described in EP2858831 B1. This discloses the production and vulcanization of rubber compounds which, in addition to rubber, silica, silane and sulfur, contain the guanidine accelerator diphenylguanidine (DPG). DPG can also fulfil other functions beyond its pure function as an accelerator. In mixtures in which silica is used as a filler, which is further enhanced by the use of silanes, it accelerates the reaction between silane and silica, improves the filler dispersion, prevents the constant increase in the rheometer curve (marching modulus), which undesirably prevents a vulcanization plateau from being reached, and improves the scorch properties of the mixture. In these applications, DPG is used together with silica and silane in the first mixing stage in the process for producing rubber mixtures, as described, for example, in US2005/0016651 A1. These properties are important because an accelerated reaction between silica and silane and improved filler dispersion can reduce the mixing time in the internal mixer and thus create mixing capacity. In addition, improved dispersion of the filler leads to an improvement in the conflicting objectives of rolling resistance/wet braking, i.e. low rolling resistance on the one hand and good wet braking properties on the other, as well as an improvement in the abrasion properties of the vulcanized mixture. Good scorch properties of the mixture are important so that the mixture does not form vulcanized areas during production (mixing and extrusion) that have an increased viscosity and would lead to defects in the heated end product. A major challenge in the development of tire rubber compounds is improving the conflicting objectives between rolling resistance, wet braking and abrasion. The loss factor tan delta at 60 °C, preferably at a measuring frequency of 10 Hz, is used as an indicator for rolling resistance. The tan delta at 0 °C, preferably at a measuring frequency of 10 Hz, is used as an indicator for wet braking, and the DIN abrasion is considered an indicator for abrasion resistance. The Payne effect serves as an indicator for the quality of the filler dispersion. In WO2010136345A1, functionalized rubbers were used together with a trimethylolpropane fatty acid mixture in rubber mixtures to improve rolling resistance and wet skid resistance. However, the rubber mixtures contained DPG as a vulcanization accelerator. It is known to those skilled in the art that guanidine accelerators releas