Preparation And Industrial Enlargement Of A Particular Kind Of Butadiene-acrylonitrile Rubber

The state of rubber includes lump,latex liquid,pellet and powder.Powdered rubber(PR) refers to the rubber which is the state of powder.Compared with the lump rubber,it owns many advantages;it can be processed directly by means of squeezing and injection;it's good for continuous and automatic processing;it can simplify the process,save energy and investment,reduce the cost and improve the work conditions,etc.Since 1950s,when USA developed the PR sucessfully,many countries have followed.At present,the main methods to produce PR are the mechanically qrinding ,spray-drying and coagulation.Through the processes such as coagulating into powder,seperating against adhesiveness,cleaning,dehydrating drying and screening etc,the coagulation method can find application in producing PR from the raw material-latex.Compared with the traditional methods of mechanically qrinding and spray-drying,the coagulation method to produce PR is more technical.Moreover,factories have the peten technology of powder and separating against adhesiveness.The product(PR) is of short diameter,spread narrowly,containing high percentage of rubber,waterproof,and widely used,which is the development direction of PR.This article researches into the process to produce NBR rubber with the method of positive coagulation.The water-dissolving one-valence and two-valence metal salts are used as coagulants.CoagulantⅠof low hardness is sprayed first,then coagulantⅠof high hardness,finally coagulantⅡto enable the rubber particles to coagulate completely.During the whole process the pH of coagulantⅠis always above 6,the temperature for coagulation is between 30℃and 40℃.The ratio of water to rubber is 5 to 6. The characteristic of this coagulation method is that during the whole process,the insulator is not added to because the emulsifier in the latex—the stearic acid saponifier and coagulantⅡtogether comes to produce it.But this generated insulator is not sure to meet the required amount,so sometimes a certain amount of saponifier needs adding to.Also a certain amount of insulator should de added during screening,cleaning and drying so as to oppose adhesiveness.The adaption of the two kinks of organic insulators can reduce the amount of insulator and improve the quality of PR.The portions of the added insulator can be controlled between 4 to 6.The key technology for the production of PNBR with the coagulation method is the one to coagulate into powder. At the end of the article,the experiment on selection of the cauldrons and mixers is discussed and so is the problem of its industrial enlargement.