What are the good methods for mixing rubber in the open mixer?
What are the good methods for mixing rubber in the open mill? Next, the editor of Karcher will explain to you:
Kneading with an open mill is an early mixing method in the rubber industry. Compared with mixing with an internal mixer, mixing with an open mixer is more labor-intensive, slanderous in production efficiency, unsafe, pollutes the environment, etc., and has poor mixing uniformity, so it has been gradually eliminated. However, mixing with an open mixer has greater flexibility, and the rubber compound is suitable for factories with small production scales, small batches of rubber materials and many varieties. For the production of some special rubber materials, such as sponge rubber, hard rubber, colored rubber, etc., it is particularly suitable to use an open mill for mixing. Therefore, the use of open mill for mixing still accounts for a certain proportion of small rubber factories.
The third stage of mixing and mixing is mixing. Due to the high viscosity of the rubber, the rubber material only flows in the circumferential direction along the rotation direction of the mill roll during mixing, and there is no axial flow. Moreover, the rubber flowing in the circumferential direction is only laminar, so it is about the thickness of the film. 1/3 of the glue layer close to the surface of the front roller cannot produce flow and become a "dead layer" or "sluggish layer". In addition, the accumulated glue on the upper part of the roll gap will also form a wedge-shaped "recirculation zone". The above reasons all cause uneven dispersion of the compounding agent in the rubber compound.
Due to the high viscosity of the rubber, the fluidity of the rubber near the surface of the roller is poor, and the shear force promotes the flow of the rubber to be laminar. The compounding agent of the inner layer of about 1/3 of the thickness of the film in contact with the roller surface cannot enter, forming a "dead layer".
Opening mixer mixing operation method When opening the mixer for mixing operation, generally first add raw rubber, masterbatch or combined rubber along one end of the big cone, and then add various ingredients according to the prescribed order of addition for mixing. There are two methods of dosing during mixing according to the rubber content of the formula: the one with high raw rubber content, the compounding agent is added in the middle of the roller, the mill is opened and the rubber dosing method is adopted to maintain a proper amount of accumulation between the two rollers Gum: For those with low raw rubber content, the compounding agent is added at one end, using the method of changing the rubber and adding the medicine. Compounding agents with a small amount of rubber compound and carbon black with high flying pollution are usually added in the form of masterbatch or paste.
Mixing generally adopts one-stage mixing method, but if it is natural rubber and a rubber compound with a larger amount of synthetic rubber and a large amount of carbon black filling, a two-stage mixing method can be used to make the rubber and compounding more uniformly mixed.
After all the ingredients have been added, it must be mixed to further mix the rubber. There are manual rubber tapping method and mechanical cutter method for mixing rubber. Manual rubber tapping generally uses left and right cutters, twisting, triangulation, and cutter rolling. The mechanical cutter method is to install a mechanical cutter near the front roller, cut along the surface of the roller to make the glue fall into the disc, and then send it between the rollers, repeating several times. After the tumbling is completed, widen the roll distance (4～5mm), and then use the cut-off method to supplement the tumbling for 2 to 3 times before unloading the film.