CURING BAG

Lost-wax Also called RP molding, fusible-core. A bar (or any shape) of wax is wrapped with RP. After the RP is cured (bag molding, etc.) in a simplified restrictor mold to keep the RP-wax shape, the wax is removed by drilling a hole or removing the end caps by applying a low temperature so that the RP is not effected (review in this chapter INJECTION MOLDING, Modified... 

Another name for the inflatable diaphragm which takes the place of the curing bag in the automatic curing of pneumatic tyres in a diaphragm press. Blanc Fixe... 

Symmetrical diphenylthiourea, one of the oldest accelerators. It is slow-curing but scorchy and is little used nowadays. It survived as the accelerator for pneumatic tyre curing bags until the late 1960s. 

Resin cures utilise phenol-formaldehyde resins with reactive methylene groups and a small added amount of either a chlorinated rubber, e.g., polychloroprene, or stannous chloride. If halogenated phenolic resins are used the additional source of a halogen may not be required. Resin cures give butyl compounds excellent heat stability and are used to good effect where this is required, e.g., in tyre curing bags which have to resist service at 150 °C in a steam atmosphere. 

Use Nonsulfur vulcanizing agent, in tire-curing bags, gaskets, and wire insulation to impart heat resistance. 

Because of its impermeability, butyl rubber finds many uses in the manufacture of inflatable items such as life jackets, life boats, balloons, and inner tubes. The excellent resistance it exhibits in the presence of water and steam makes it suitable for hoses and diaphragms. Applications are also found as flexible electrical insulation, shock and vibration absorbers, curing bags for tire vulcanization, and molding. 

Uses of Butyl Ruhher. Butyl rubber is used in the manufacture of inner liners of tubeless tires, inner tubes, cable insulation, pharmaceutical stoppers, curing bags, and bladders for tire manufacture. When tires are in the molds for vulcanization, the inside of the tire is filled with a butyl rubber bag or bladder of steam under enough pressure to obtain the vulcanization temperature. This is possible only because of the good resistance of butyl rubber to heat and water. 

A significant use of acetylene black is in dry cell batteries where it contributes low electrical resistance and high capacity. In rubber it gives electrically conductive properties to heater pads, tapes, antistatic belt drives, conveyor belts, and shoe soles. It is also useful in electrically conductive plastics such as electrical magnetic interference (EMI) shielding enclosures. Its contribution to thermal conductivity has been useful in rubber curing bags for tire manufacture. 

The addition of 15-20phr of medium unsaturation EPDM will reduce these defects and will considerably improve low- and high-temperature behaviour. Furthermore, the addition of 10-15 phr of EPDM to butyl rubber compounds, used to produce curing bags, will considerably increase their service life. 

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