Mixing is the most important thing in the production process of rubber products, and the quality of the mixed rubber directly affects the quality of the finished rubber products. The relative molecular weight of natural rubber is high, the distribution is wide, and the molecular chain is easy to break. There are a certain number of gel molecules in the raw rubber, so natural rubber has good mixing performance. In actual production, choosing a suitable mixing process can prepare natural rubber compounds with good quality and high efficiency.
1. Natural rubber mixing characteristics
Natural rubber has good roll-wrapping properties, its plasticity increases rapidly during mechanical kneading, its heat generation is low, its calorific value is much smaller than that of synthetic rubber, it has good wettability to the compounding agent, eats powder quickly, and is easily dispersed. The mixing time is short during mixing, and the mixing operation 2YLYY416 is easy to master. In actual production, the order of addition has little effect on the degree of dispersion of the compounding agent, but too long mixing time has a greater impact on rubber performance than synthetic rubber; too long mixing time will easily lead to over-mixing, and the performance of natural rubber vulcanizates will be significantly reduced. , In severe cases, problems such as sticking rollers will occur.
2. Natural rubber mixing process
Natural rubber has good mixing performance, and the mixing process can be carried out in an open mixer or an internal mixer.
(1) Open mill mixing process: The mixing conditions of the open mill are based on the basic properties of rubber, such as viscoelasticity, relaxation time, and transition temperature. Appropriate mixing process parameters can be carried out after the natural rubber is in the state of covered rollers. Mixing. When natural rubber is mixed in an open mill, the roller temperature of the open mill is generally controlled at 50-60°C (the temperature of the front roll is 55-60°C, and the temperature of the back roll is 50-55°C). During the mixing process, the liquid softener in the natural rubber product formula needs to be added after the filler is added, and the mixing is about 20-30 minutes.
(2) Mixing process of internal mixer: The mixing methods of internal mixer mainly include one-stage mixing method, two-stage mixing method, priming method and reverse mixing method. When natural rubber is mixed with an internal mixer, a one-stage mixing is used, and the quality of the mixed rubber is better. The one-stage mixing method also has the characteristics of short production cycle and high efficiency. In actual production, when the natural rubber is mixed with an internal mixer for one-stage mixing, the discharge temperature is usually controlled at about 140°C, and should not exceed 170°C.
It should be noted that if the natural rubber product formula contains a large amount of compounding agents that are difficult to be uniformly dispersed in the rubber, it is not suitable to use the banburying for one stage mixing. The plastic compound needs to be fully mixed to avoid uneven mixing. .
In actual production, there are also certain differences in the mixing process performance of different brands of natural rubber. Rubber product manufacturers need to reasonably adjust the mixing process parameters according to actual needs to further improve the quality of natural rubber compounds. When natural rubber and reclaimed rubber are used together to produce rubber products, it is recommended that natural rubber be fully masticated and then mixed with reclaimed rubber to reduce more raw material costs while ensuring product quality.
Exclusive original article [commercial authorization] reprint, excerpt and excerpt in any form are prohibited without written authorization. Focus on Hongyun rubber: learn the process formula and raw material technology of producing rubber products from recycled rubber to help you reduce costs and increase profits