CS245332B1 - Rubber mixtures - Google Patents

Abstract

The invention relates to rubber blends based on synthetic butadiene styrene rubber. The rubber compositions contain from 5 to 15 wt. parts of oligomeric polystyrene with bonded terminal dialkyldithiocarbam groups having an average molecular weight of polystyrene of less than 5,000 with respect to the rubber component.

Description

245332 3 4

The present invention relates to rubber compositions comprising synthetic butadiene styrene rubber.

Various additives such as softeners, fillers, lubricants, stabilizers, crosslinkers, vulcanization accelerators and the like are added to the rubber compositions. This is done in particular to influence their processing properties, resp. influencing the properties of their vulcanizers. In recent years, a number of works have been published which show that the technological properties of rubber compounds as useful properties of their vulcanizers can be positively influenced by the addition of oligomeric polysteyrenes with various reactive groups, e.g., amine groups, halogen, or hydroxyl groups. -pinami. In the periodic as well as patent literature, there are no described modifying procedures which utilize the application of oligomeric polystyrenes with terminally functional groups.

The above drawbacks are avoided by the rubber compositions of the present invention based on synthetic hutadiene-styrene rubber, consisting of fillers and base-vulcanizing additives which consist of 5 to 15 wt. parts of oligomeric polystyrene with bound dialkyldithiocarbamide groups having an average molecular weight of polystyrene of less than 5,000, based on the rubber component.

For this purpose, oligomeric polystyrenes with N, N-dimethyldithiocarbamide groups at the chain ends can be utilized, which are prepared by block or solution polymerization in the presence of tetramethylthiourea disulfide (TMTD) according to AO 231 235. rubber compositions as combined effect modifying agents. At the stage of preparation or processing of rubber mixtures at temperatures above 130 ° C, they influence their processing properties by reducing their viscosity. The decrease in the Mooney 1301 + 4 viscosity by the addition of a certain amount of oligomeric polystyrene is comparable to a decrease in the viscosity of the additive mixture of the commercially available Triumph.

The oligomeric polystyrene with N, N-dimethyldithiocarbamide groups also affects the further technological property of the mixture by vulcanization. During the vulcanization, the reactivity of the end groups in the acceleration of the vulcanization occurs, hence the TMTD accelerator itself is present in the system. This makes it possible to reduce the consumption of conventional accelerators, especially TMTDs, or to use them in combination with other accelerators, especially sulphonate type. Oligomeric polystyrene acting as a temporary wetting agent in the rubber compound processing process has beneficial effects on some physico-mechanical properties of filled and unfilled vulcanizates, since it acts as an active agent in the vulcanizate. Increases modulus, tensile strength and hardness values. This effect is manifested by the passage through the maximum, i.e. the highest values of physico-mechanical properties are achieved in a certain concentration region. Applying conventional types of wipers results in a reduction in the mechanical properties of the vulcanizates. Example 1

The torque SBR of rubbers (synthetic butadiene styrene rubbers) measured on a Brabender plastograph at 140 ° C showed a value of 25.3 Nm after 5 minutes of homogenization. In the presence of 13% by weight of oligomeric polystyrene, the value was 19.1 Nm. The amount of energy used to homogenize the rubber mixture was reduced by about 28 Savings were calculated from plastograns measured on a Brabender apparatus. Example 2

The torque SBR of the rubber measured by the Brabender naplastograph had a value of 22.8 Nm after homogenization at 160 ° C for five minutes. In the presence of 20 wt. % of the oligomeric polystyrene was 10 Nm. The amount of energy consumed was reduced by about 56%. Example 3

Viscosity ML13Ui + 4 SBR mixtures filled with 50 wt. parts of Nigros-K carbon black without oligomeric polystyrene were 49.8 ° ML. In the presence of 5 wt. parts of oligomeric polystyrene were 45.4 ° ML. The vulcanization optimum of the SBR blend without polystyrene was achieved in 30.5 minutes and in the presence of 5% by weight of the Monsanto rheometer at 150 degrees Celsius. of polystyrene in 25 minutes.

Physical-mechanical properties of SBR vulcanizers containing 5 wt. parts of polystyrene were: M10 = 6.1 MPa, M300 = 28.5 MPa, tensile strength 44.7 MPa, hardness 70 ° IRHD. The physical-mechanical properties of SBR vulcanizers without oligomeric polystyrene were: M100 = 5.3 MPa, M300 = 27.8 MPa, tensile strength was 38.4 MPa, hardness was 69 ° IRHD. Example 4

Viscosity ML130i + 4 SBR filled with 15 parts by weight of SiO2 and 15% by weight. parts of the kaolin of the oligomeric polystyrene are 20 ° ML. In the presence of 15 wt. parts of oligomeric polystyrene, the viscosity of ML130i + 4 was reduced to 16 ° ML. The optimum vulcanization of SBR mixture of oligomeric polystyrene was achieved in 56

Claims (1)

245332 5 minutes. In the presence of 15 wt. of polyolefin polystyrene in 31 minutes. The physico-mechanical properties of the polystyrene-free SBR vulcanisates were: M 10 = 1.0 MPa, M = 2.0 MPa, tensile strength was 5.0 MPa, hardness was 51 ° IRHD. 6 Physical-mechanical properties of SBR bullets containing 15 wt. parts of oligomeric polystyrene were: M 10 = 1.2 MPa, M 300 - 2.9 MPa, tensile strength was 9.7 MPa, hardness was 54 ° IRHD. SUBSTANCE Rubber blends based on synthetic butadiene styrene rubber consisting of fillers and base vulcanizing additives, characterized in that they contain 5 to 15 wt. parts of oligomeric polystyrene with depleted bound dialkyldithiocarbamide groups having an average molecular weight of polystyrene of less than 5,000 with respect to the rubber component.