Vulcanization is the last major process in the production of natural rubber products. It is a process of changing the internal linear structure of rubber molecules into a three-dimensional network structure. Increasing the vulcanization temperature and shortening the vulcanization time are common ways for rubber products manufacturers to improve production efficiency. Really okay? In actual production, blindly increasing the vulcanization temperature will cause irreversible damage to natural rubber products.
Compared with unvulcanized natural rubber, the elasticity, tensile strength, tensile strength, tear strength and hardness of vulcanized natural rubber will be significantly improved, elongation at break, compression set, fatigue heat reduction; natural The vulcanized rubber has a reduced gas permeability and water permeability, and the swelling heat resistance is improved; the chemical stability is improved. This is because the network structure formed by the reaction of the natural rubber inhibits the diffusion of low molecules, the diffusion of free radicals, the disappearance of highly reactive groups inside the rubber molecules, and the aging reaction cannot be carried out, so that many properties of the natural rubber vulcanizate are improved. Vulcanized natural rubber has the best overall performance.
It is well known that the higher the vulcanization temperature and the faster the vulcanization reaction rate, the vulcanization time is shortened by half for every 10 °C increase in the vulcanization temperature. The vulcanization temperature of the rubber refers to the temperature at which the rubber is vulcanized, the temperature and the rubber type, the vulcanization system, The structure of the rubber product has a direct relationship. The vulcanization temperature of the natural rubber vulcanization should not exceed 150-160 ° C. The mechanical properties, chemical stability and heat aging resistance of the rubber compound after vulcanization are obviously increased. Once the vulcanization temperature is too high, Lead to the decline of vulcanizate indicators:
1 The high vulcanization temperature of natural rubber will cause problems such as cracking of rubber molecular chain and vulcanization, which will lead to a significant decrease in the mechanical properties of natural rubber vulcanizates. 2 When using natural rubber to produce rubber products, when the textile is added, the vulcanization temperature will be too high, which will lead to textiles. The strength of the material is reduced; 3 the safety of the scorch directly affects the processing performance of the natural rubber and the quality of the finished product. The shortening of the scorch time will reduce the filling time of the natural rubber product, resulting in partial lack of rubber in the rubber product; 4 when using natural rubber to produce thick rubber products, If the vulcanization temperature is too high, the temperature difference between the inside and the outside of the rubber product will increase, and it is difficult to make the inner and outer rubber materials reach a flat range at the same time, and the vulcanization is uneven, resulting in the problem of "uncooked outside coke".
The hazard caused by too high vulcanization temperature can not only stop there. Therefore, when natural rubber products manufacturers want to increase the production efficiency by increasing the vulcanization temperature, they must not increase the vulcanization temperature without limitation, and do the corresponding technical measures to comprehensively consider the rubber type and vulcanization system. The vulcanization process and product structure set the vulcanization temperature which is most favorable for the performance of natural rubber products.