When using reclaimed rubber to produce conveyor belts, hoses, rubber sheets, sealing products, and multilayer composite rubber products, the adhesive's self-adhesiveness is insufficient, causing bubbles and delamination at the bonding area; At worst, the interface bonding after vulcanization is weak, directly affecting product quality; The plasticity, Mooney viscosity, surface condition, and compatibility with other rubber materials all affect the bonding effect. Improving the adhesion of reclaimed rubber can be addressed from the following aspects.
1. Improve the adhesion of reclaimed rubber — Techniques for selecting rubber raw materials
The activity of rubber molecular chains is closely related to the adhesive strength of the rubber compound. Rubber with strong molecular chain activity and suitable strength for unvulcanized rubber tends to have relatively better self-adhesiveness.
When producing rubber products with high adhesion requirements using reclaimed rubber, it is recommended to choose reclaimed rubber with relatively stable Mooney viscosity, plasticity, and rubber content, and observe the surface condition and adhesion strength of the film E6LYY529 through small tests. When using reclaimed rubber and virgin rubber together, attention should also be paid to the self-adhesiveness of the base rubber. Natural rubber has the best self-adhesiveness, followed by neoprene rubber, followed by styrene-butadiene rubber, nitrile rubber, cis-butadiene rubber, etc., with butyl rubber and ethylene-propylene rubber having the worst self-adhesiveness.
2. Improve the adhesion of reclaimed rubber—use adhesives appropriately
Adding adhesive resin and other additives appropriately to the formulation of reclaimed rubber products can improve the surface viscosity of the compound and reduce the tension at the bonding interface, allowing the two layers of film to form more complete interfacial contact. Common tackifiers include coumalong, rosin and its derivatives, petroleum resin, and others. It should be noted that the more tackifiers added, the better; If the amount of tackifier used too high, the strength, hardness, and heat resistance of the reclaimed rubber can change after vulcanization.
3. Improving the adhesion of reclaimed rubber — reinforcement filler addition techniques
When using reclaimed rubber to produce rubber products, selecting carbon black with smaller particle size, suitable structural strength, and surface activity can improve the strength and adhesion of the compound, while light-colored reclaimed rubber products can use white carbon black. It should be noted that excessive reinforcing filler in the reclaimed rubber formulation can cause the compound to harden and dry out, reducing the actual contact strength among the rubber sheets and actually worsening self-adhesiveness. When using reclaimed rubber to prepare the compound that needs adhesion, it is recommended to find a balance among reinforcement, processability, and adhesion.
4. Improves the adhesion of reclaimed rubber—use less easily sprayed additives
When producing rubber products with reclaimed rubber, whether the film surface is clean and the activity is normal is very sensitive to bonding. If the amount of easily migratory additives such as sulfur and paraffin exceeds their solubility in the reclaimed rubber, they migrate to the film surface to form spray frost, forming a barrier layer at the bonding interface that hinders intermolecular contact and significantly reduces adhesion. To improve the adhesion of reclaimed rubber, it is recommended to use less easily sprayed additives.
When producing rubber products with high adhesion requirements using reclaimed rubber as the main raw material, it is necessary not only to select suitable reclaimed rubber, raw rubber, and various rubber additives, but also to pay special attention to mixing and storage conditions: during reclaimed rubber mixing, accelerators, sulfur, and other vulcanization system additives should be added reasonably according to the process to avoid excessive mixing temperatures that can cause premature reactions; The storage time, temperature, and surface condition of the compound compound must be stably controlled to ensure it "adheres" while maintaining sufficient strength, stability, and finished product performance.
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