What are the advantages of hot vulcanization technology compared to cold bonding technology?

In the heavy industry sector, the joints in the entire conveyor belt are often the weakest link, which directly determines the reliability of the conveying system and the total life cycle cost. Hot vulcanization is the gold standard for ensuring the integrity of the conveyor belt structure. This article will systematically analyze the advantages of hot vulcanization technology over cold bonding technology.

1. Hot Vulcanization Technology

Hot vulcanization utilizes heating, pressure, and time as three elements to cause irreversible chemical cross-linking reactions in the joint's rubber. During the operation, the belt ends need to be peeled layer by layer according to the process requirements, and the unvulcanized core rubber and surface rubber need to be laid down and then vulcanized. After heating, the vulcanization machine applies pressure to the interface and raises the temperature. During this process, the unvulcanized rubber undergoes cross-linking reactions, forming a three-dimensional network structure. The newly added phase and the original phase also undergo co-vulcanization, ultimately becoming one.

Hot vulcanization combines chemical covalent bonds and has no obvious interface layer. The joint is part of the belt.

2. Cold Bonding Joints

Cold bonding technology uses adhesives that solidify at room temperature. It is essentially a physical bonding method. After the adhesive cures, it forms a "glue film" that relies on intermolecular forces to bond the two ends of the rubber together. This layer of glue film is not of the same structure as the original rubber and always has a clear interface.

As the usage time increases, the residual solvents will gradually evaporate, and the glue layer will further age and harden, causing the bonding strength to continuously decline.

1. Mechanical Strength and Lifespan

• Cold Bonding Joints: The strength is usually only 60%-80% of the original strength. Under dynamic loads, the bonding interface will gradually peel off due to repeated bending and stretching. The lifespan of cold bonding joints is generally 3-12 months, and then edge rubber cracking, bulging, or even overall breakage will occur.
• Hot Vulcanization Joints: The strength can be restored to 90%-100% of the original strength. Under normal maintenance, they can be used for 3-5 years or even longer. Hot vulcanization is the only way to ensure that the steel wire rope and rubber fully penetrate and achieve "pull-out force" compliance.

2. Anti-Tear and Anti-Impact Performance

• Cold Bonding Joints: The glue layer and rubber are prone to layering when subjected to impact. Once a small damage occurs, it will rapidly expand under tension, causing the entire belt to tear open.
• Hot Vulcanization Joints: The joint area is continuous with the original material, without an interface. Stress can be uniformly transmitted. Even if it receives impact or scratches, the damage will not extend along the interface, significantly reducing the risk of longitudinal tearing. For applications with high tear resistance, hot vulcanization is a basic safety requirement.

3. Resistance to Environmental Factors

• Cold Bonding Joints: They are extremely sensitive to the usage environment. They will hydrolyze in humid environments; they will swell and soften when in contact with oils or chemical agents; and they will accelerate aging in high-temperature environments.
• Hot Vulcanization Joints: They inherit the weather resistance, water resistance, oil resistance, and temperature resistance of the conveyor belt itself. In harsh working conditions such as open-pit mines and coal washing plants, the stability advantage of hot vulcanization joints is extremely prominent.

4. Joint Flatness

• Cold Bonding Joints: The glue layer has thickness and is difficult to achieve absolute flatness when adhering. Therefore, the joint area often has steps or protrusions, which will increase the friction between the conveyor belt and the idler, cleaning device, etc.
• Hot Vulcanization Joints: The surface of the joint can be made to be completely flat with the local material of the belt, without steps or protrusions. This not only extends the service life of the cleaning device and idler but also reduces the accumulation of materials at the joint, reducing the risk of belt deviation.

5. Safety

• Cold Bonding Joints: They are a "ready-to-use" technology, but the actual curing requires a relatively long time. If applied in operation before complete curing, it is prone to instantaneous breakage of the joint, causing equipment damage and even casualties.
• Hot Vulcanization Joints: There is no need to wait for curing. After hot vulcanization, it can reach the design indicators immediately and be put into use. Safety is guaranteed, and there is no risk of sudden failure due to aging and failure.

1. Steel wire rope conveyor belt

Cold bonding cannot ensure the adhesion between the steel wire rope and the rubber, and the joint strength also fails to meet the strength requirements during use.

2. High tension, long-distance transportation system

In this scenario, the joints continuously bear high stress, so the fatigue life of cold-bonded joints is insufficient and it is not recommended to use them.

3. High impact, high tearing risk conditions

In the transportation of ores, coke, or large pieces of materials, cold-bonded joints are prone to become the starting point of tearing.

4. Extreme environments

In high-temperature, low-temperature, humid, and oily environments, the environmental adaptability of cold-bonding adhesives is extremely poor and they are not suitable for use.

5. High cleaning efficiency requirements

For factories with strict food or environmental protection requirements, such as food processing plants, hot vulcanization can ensure that the joints are flat and free of dead corners.

The joints of the conveyor belt are the key link that determines the reliability, safety, and economy of the entire conveyor system. The hot vulcanization joints achieve integration with the conveyor belt body through chemical cross-linking, and are superior to the cold bonding technology in terms of strength, lifespan, and environmental resistance.

If you are planning a new transportation system or renovating an existing one, and have any needs or questions, please feel free to contact our team at any time.