During the injection process of reclaimed rubber products, the rubber must have sufficient scorch time before the injection machine passes through the barrel, nozzle, and glue to fill the mold cavity and start crosslinking to ensure that the rubber does not undergo early vulcanization. The heat generation of the rubber filler during processing affects the scorching of the rubber, and the product manufacturer needs to pay special attention. So in actual production, how to consider the impact of rubber filler heat generation on the reclaimed rubber injection process? Whether manufacturers need to consider other factors when choosing rubber fillers for injection-type reclaimed rubber products.
2. Rubber filler heat generation and reclaimed rubber injection process
During the injection process, the rubber will heat up when it is plasticized and when it passes through the nozzle of the injection machine. There are many types of rubber, and the same rubber filler has different effects when used in different types of rubber.
(1) Comparison of common rubber fillers' heat generation: The commonly used rubber fillers in the production of reclaimed rubber products include carbon black, white carbon black, clay, calcium carbonate, etc., among which clay has the smallest heat generation, semi-reinforced carbon black and calcium carbonate 2LLYY930 The heat is small, and the heat generation of super wear-resistant carbon black, medium-super wear-resistant carbon black and high wear-resistant carbon black during processing is much higher than that of semi-reinforced carbon black.
(2) The effect of rubber filler in reclaimed rubber is different
In general, when using rubber fillers in rubbers with low temperature rise, increase the amount of rubber fillers to increase the temperature when the rubber passes through the nozzle to ensure the vulcanization temperature of the rubber, such as isoprene rubber; styrene butadiene rubber, nitrile butadiene rubber The rubber itself generates a lot of heat during the processing process, and the temperature rise of the rubber material is large when it passes through the nozzle. The heat generation factor after the rubber filler is added must be fully considered to avoid scorching of the rubber material.
Compared with natural rubber and synthetic rubber, reclaimed rubber generates less heat during processing, and its use with raw rubber can reduce heat generation to a certain extent and avoid scorching; all types of raw rubber have high heat sensitivity and temperature rise Afterwards, the rubber will soften and increase rapidly, and the addition of reclaimed rubber will reduce the thermal sensitivity of the rubber. When reclaimed rubber is used alone to produce injection-type rubber products, the heat of rubber filler has little effect on the scorching of the rubber; when reclaimed rubber is used with raw rubber, especially nitrile rubber and styrene butadiene rubber, it is important to accurately calculate the heat generation of rubber filler .
3. Problems to be considered when choosing fillers for injection-type reclaimed rubber products
Reinforced rubber fillers can significantly improve the mechanical strength of reclaimed rubber products, and non-reinforced rubber fillers can increase product volume and improve rubber processing performance; rubber fillers can increase the tensile strength, elongation and hardness of reclaimed rubber vulcanizates , Abrasion resistance and other indicators have a great influence. When selecting rubber fillers for injection-type reclaimed rubber products, it is not only necessary to consider the impact of rubber fillers on rubber fluidity, processing heat generation, and scorch safety, but also to comprehensively consider the physical and mechanical properties of reclaimed rubber products to balance the various indicators. relationship.
The rubber injection process is developed on the basis of the molding method and the shifting vulcanization process. There are strict requirements on the process performance of the rubber, and a careless operation will cause major losses. Therefore, when using reclaimed rubber to produce injection rubber products, many factors must be considered, including basic indicators of reclaimed rubber, vulcanization, rubber filler, softening, and anti-aging system, etc., to effectively improve the quality and yield of injection reclaimed rubber products.
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