Ben Wang March 15 hearing, how to prevent scorch shoe production in the scorching problem.
One: What is scorch
Scorching is one of the common process problems in the production of vulcanized shoes, and occurs frequently in high temperature seasons. In a nutshell, it is a kind of advanced vulcanization behavior, namely the phenomenon of early vulcanization in the various processes before vulcanization (rubber, rubber storage, extrusion, calendering, forming), it can also be called early vulcanization. The scorch not only brings difficulties to the processing, but also reduces the physical and mechanical properties of the vulcanized shoe. The smoothness and smoothness of the outer surface can also be seriously affected, and even result in dead material.
II: Why scorched
(1) Improper formula design, unbalanced configuration of vulcanization system, and unusual amounts of vulcanizing agents and accelerators.
(2) For some types of plastics that need to be plasticized, the plasticity is not up to the requirements, the plasticity is too low, and the glue is too hard, which leads to a sharp rise in temperature when mixing. The roller temperature of the rubber extruder or extruder or the calender is too high and the cooling is not enough, which may also lead to on-site scorching.
(3) When the compounding material is unloaded, the film is too thick, the heat is not good, or it is not cooled, that is, it is piled up and stored in a hurry. In addition, the poor ventilation and temperature of the warehouse cause heat accumulation, which also causes scorch.
(4) The rubber stock is poorly managed during storage. After the remaining scorch time is exhausted, it is still stacked and used, and natural scorching occurs.
Three: How to prevent scorch
(1) The formula design of the vulcanized shoe compound should be appropriate and reasonable, for example, the accelerant should be as many as possible and combined. In formulas that use accelerators with a fast sulphur content, several accelerators with good aftereffects, long scorch times, and high critical temperatures must be used together to contain them. If sulfenamide accelerators such as CBS and NS are used together, scorch can be effectively suppressed. In addition, in order to adapt to the high-temperature, high-pressure, and high-efficiency refining processes in the production of vulcanized shoes, a suitable amount (0.3 to 0.5 parts) of anti-scorching agent can also be used in the formulation.
(2) Strengthen the cooling measures for the rubber compound in the rubber compound and subsequent processes, mainly by strictly controlling the machine temperature, roll temperature and guaranteeing sufficient cooling water circulation so that the operating temperature does not exceed the critical point of scorch.
(3) Pay attention to the management of semi-finished rubber products. Each batch of materials should follow the flow card, implement the "first-in-first-out" storage principle, and stipulate that the longest storage time of each vehicle material shall not be extended. The warehouse should have good ventilation conditions.
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