The scorching of rubber is a kind of advanced vulcanization behavior, that is, the early vulcanization phenomenon that occurs in various processes before vulcanization (rubber mixing, rubber storage, extrusion, calendering, molding), so it can also be called early vulcanization.
The scorching of rubber is a kind of advanced vulcanization behavior, that is, the early vulcanization phenomenon that occurs in various processes before vulcanization (rubber mixing, rubber storage, extrusion, calendering, molding), so it can also be called early vulcanization.
Reasons for scorching:
Improper formulation design, unbalanced configuration of curing system, and excessive dosage of curing agent and accelerator.
For some types of rubber that need to be molded, the molding fails to meet the requirements, the plasticity is too low, and the gum is too hard, resulting in a sharp temperature rise during rubber mixing. Too high roller temperature and insufficient cooling of rubber mixer or other roller devices (such as return mixer and calender) may also lead to on-site coking.
When discharging the mixed rubber, the flake is too thick, the heat dissipation is poor, or it is not cooled, that is, it is stored in a hurry, and the factors such as poor ventilation and high temperature in the warehouse cause heat accumulation, which will also lead to coking.
The rubber materials were poorly managed during storage. After the remaining scorching time was exhausted, they were still stacked and not used, resulting in natural scorching. Hazards of scorching: difficult processing; It affects the physical properties of the product and the smoothness of the external surface; It may even cause disconnection at the product connector.
Methods to prevent scorching:
The design of rubber compound shall be appropriate and reasonable. For example, the accelerator shall be used in multiple ways as far as possible. Suppress scorching. In order to adapt to high temperature, high pressure and high speed rubber mixing process, an appropriate amount of anti-coking agent (0.3~0.5 phr) can also be added in the formula.
Strengthen the cooling measures for rubber compound in rubber mixing and subsequent processes, mainly by strictly controlling the machine temperature and roll temperature and ensuring sufficient cooling water circulation, so that the operating temperature does not exceed the critical point of coking.
Pay attention to the management of rubber semi-finished products, each batch of materials should be followed by a flow card, implement the principle of "first in, first out" storage, and specify the maximum storage time of each vehicle of materials, which should not be exceeded. The warehouse shall have good ventilation conditions.
Disclaimer: The image materials and articles of this platform are from the network, so the copyright belongs to the original author. If it infringes your copyright and interests, please contact us, we apologize and delete it quickly. Source: Rubber Technology Network
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