Preparation Of Promoters Containing Selenium And Tellurium Dithiocarbamate And Their Properties In Rubber

Dithiocarbamate salts are speeding acid promoter with fast speed of vulcanization,has been widely used in the natural rubber and various synthetic rubber.But due to many dithiocarbamate salts will generate nitrosamines,such as diethyl dithiocarbamate tellurium(TDEC)and zinc diethyl dithiocarbamate(ZDC),that their application is limited.The introduction of benzyl into dithiocarbamate molecules,such as zinc dibenzyl dithiocarbamate(ZBEC),can effectively avoid this problem,but the introduction of benzyl dithiocarbamate can reduce the vulcanization activity and vulcanization efficiency of promoters.We noticed that promoter TDEC in rubber vulcanization accelerator efficiency is much better than ZDC,this may be related to the former is four ligand,the latter is two coordination,also may be because of tellurium is caused by the kin of sulfur element,so we will be introduced to the kin of sulfur element selenium,tellurium,promoter,the synthesis of five new and efficient promoter,studied their pure styrene butadiene rubber and add Si O2 vulcanization properties of EPDM and the influence of physical and mechanical properties,discussed the elements for the center with selenium,tellurium,zinc salt dithiocarbamate promoter in rubber vulcanization mechanism,the main contents are as follows:(1)the successful synthesis of diethyl dithiocarbamate selenium(SDEC),N-ethyl-N-phenyl dithiocarbamate selenium(SDPC),N-ethyl-N-phenyl dithiocarbamate tellurium(TDPC),dibenzyl(SBPC)dithiocarbamate selenium and dibenzyl dithiocarbamate tellurium(TBPC)five kinds of rubber accelerator,through the characterization of molecular structure and expectations,that selenium salt is second ligand structure,and tellurium salt is four ligand structure.(2)the vulcanization promotion effect of SDEC in pure SBR is better than that of TDEC and ZDC,which can bring greater cross-linking density and constant stretching stress to rubber.After the introduction of phenyl and benzyl,the promoter was passivated,so that when the dosage was less than 1 part,the sulfurization promotion effect of tellurium TDPC and TBPC was better than that of selenium SDPC and SBPC.When the dosage was more than 1 part,the sulfurization promotion effect of selenium salt SDPC and SBPC was better than that of tellurium salt TDPC and TBPC.(3)SBR/SDEC has a higher Tan value at 0?,while at 60?,it has a smaller Tan value;However,after the introduction of phenyl and benzyl groups,the Tan values of PX and ZBEC of zinc salt were relatively high at 0?,and the Tan values of SDPC and SBPC of selenium salt were slightly higher than those of TDPC and TBPC of tellurium salt.At 60?,the Tan values of selenium salt and tellurium salt were almost the same,but lower than those of zinc salt.(4)compared with ethyl,after the introduction of phenyl and benzyl,selenium,tellurium salt and zinc salt salt in pure scorch time corresponding increase in SBR,vulcanization rate also declined obviously,the torque of the glue is a downward trend,phenyl and benzyl can produce passivation effect of promoter,and benzyl degree than phenyl of promoter passivation.(5)five accelerators,SDEC,SDPC,TDPC,SBPC and TBPC,have the same effect on the sulfurization promotion law and mechanical properties of EPDM with 30 phr of silica,which further extends the application range of the new accelerators.(6)the mechanism of action of selenium salt and tellurium salt in rubber is different from that of zinc salt.Both selenium salt and tellurium react with ZnO to form free sulfur,selenium and tellurium.Zinc salts cannot interact with ZnO to produce sulfur-free sulfurization because they share the same element Zn with ZnO.