The homogeneity of the rubber mixture is achieved by mixing it. After finishing the preparation of the mixture, it is removed in the form of a sheet with a thickness of 3-5 mm, put on the desktop and measures its temperature with a needle thermocouple. The rollers shut off and close the valves. A sample is cut from the mixture sheet for analysis, and then the sheet and sample are labelled with a wax pencil. They indicate the date of mixing, the cypher of the mixture, and the mode of mixing.
After marking the mixture is cooled in a bath and placed on a rack. The use of taical masterbatches, pastes and compositions in rubber mixtures does not fundamentally change the order of mixing. The masterbatch is developed at the beginning of the process at a minimum gap, then the gap is increased, and ingredients are introduced into it. Pastes and compositions are administered in the same sequence as the ingredients, which are their main part.
- However, in this case, one can use the same principles of construction of mixing modes, only by increasing the duration of the mixing cycle in proportion to the reduction of the rotor speed. In some factories, vulcanising agents are not introduced as masterbatches but are added in the second mixing stage on a roll mill. There are some arguments in favour of such a regime, but provides additional considerations confirming the feasibility of using masterbatches with accelerators.
- Economic calculations showed that the cost of producing extruded billets using powder technology using a high-speed mixer for powders, compactors, mixing extruders is 57% of their value with standard technology two-stage mixing method, rollers, extruders. The use of powdered rubber filled with technical carbon is especially effective. The method of extrusion of profiles from powdered uterine mixtures is quite promising.
The Two State Mixing
The two-stage mixing method is to manufacture a rubber mixture with soot and other ingredients in the first-stage rubber mixer – the so-called masterbatch, which is leafed, cooled and reloaded into the mixer, where sulfur and accelerators are introduced into the second stage. Sometimes in the first stage, only a mixture of rubber with soot is made, that is, a soot uterus, and in the second stage, the rest of the ingredients are added to the ace. This method has found wide application in foreign practice.
The degree of filling masterbatches set by regulating the flow of latex and particulate suspension entering the tank for mixing. For this purpose, use a nozzle of constant diameter or tilting the measuring capacitance. The resulting mixture of carbon black and latex (Carbex) is fed to a coagulation tank, where fast coagulation occurs. Initially, sulfuric acid and its salts were used as a coagulator. However, the use of salt was associated with some technical difficulties and adversely affected the properties of masterbatches; therefore, since 1950, salts have not been used. Animal glue and drop proteins, as well as polyamines, facilitating the agglomeration of small particles and providing complete coagulation and the ability to control the size of the particles of the coagulum, were also used as coagulators. After coagulation, the mixture is separated from water and dried.