Reasons for the cold bonding opening
DCCD® has been working hard to improve the safety of cold bonding pulley lagging. In addition to the well-known factors such as installation process and construction management, we have summarized some less-known reasons for cold bonding opening, hope it will be helpful to you.
1.The site construction environment is too humid: the ideal operating humidity of cold bonding cement is ≤65°. When the humidity exceeds 65°, the adhesive coating both on the pulley surface and the pulley lagging will condense a layer of fine water droplets. Therefore, the bonding strength of the cement decreases. It is recommended to use drying equipment to dry the adhesive coating. When using the high-temperature drying lamp, keep a distance of 5 cm from the adhesive coating to prevent fire caused by high temperature.
2.The site temperature is too low: the ambient temperature during site installation should be above 5℃, when it is lower than 5℃, the active response of the cement will decrease, when the temperature is lower than 0℃, the active response of the cement will decrease ≥40 %. In low temperature environments, on-site heating facilities are necessary.
3.The operating temperature of the equipment is too high: when the temperature of the conveying equipment exceeds 80℃, the pulley lagging will gradually become embrittled; when the temperature exceeds 100℃, the cross-linking reaction of the cement will break and cause the cement to lose adhesive strength ; When the temperature exceeds 120℃, the cross-linking reaction of the pulley lagging will cause serious embrittlement and degumming from the adhesive coating; it is recommended to use the hot-vulcanization pulley coating process on the high-temperature conveyor line, and the pulley lagging uses high-temperature resistant EPDM And Viton.
4.Oxidation of the CN layer: The CN layer will be oxidized when the cold glue board is stored for more than 6 months, and the cross-linking reaction between the CN layer and the cement will decrease. DCCD® recommends that when using a cold bonding pulley lagging that has been stored for more than 6 months, lightly sand the CN layer with a tungsten steel sanding disc to remove the oxidized rubber layer on the surface, and the CN layer will resume the cross-linking reaction with the cement.
5.Unqualified sealing quality: The conveyor belt put a great deal of pressure on the seal when the pulley is running, the unqualified seal between the pulley laggings during the coating process will leads to a seal failure. DCCD® tests three sealing materials: polyurethane sealant, epoxy resin, and fast vulcanizing rubber. It is found that the bonding strength and toughness of epoxy resin and fast-vulcanized rubber are the best. But the hardness of epoxy resin is ≥80±5 Shore A, which will damage the conveyor belt. Therefore, the fast vulcanization rubber is the most scientific sealing material. DCCD® has improved the fast vulcanization rubber, divided into A and B two components, convenient storage. Only the two parts A+B are mixed and extruded by a glue gun can produce a fast vulcanization.
