The process of making rubber sheets involves several steps.
1. Mastication: This is the first step in rubber processing, where the elastomer is sheared and the molecules are broken down to give easier flow. Mastication helps in reducing the viscosity of the rubber and improving its processability.
2. Mixing: After mastication, additives are incorporated into the rubber. These additives can include fillers, softeners, shaping aids, and other chemicals. The mixing process helps in distributing the additives uniformly throughout the rubber compound.
3. Shaping: The next step is to shape the rubber compound into sheets. There are two common methods for shaping rubber sheets: extrusion and calendering.
- Extrusion: In extrusion, the uncured rubber is forced through a die under pressure. This creates a shaped sheet or profile. The extruded material is then cut into slugs or pellets for further processing.
- Calendering: In calendering, the rubber compound is passed through horizontal rollers. This process is often used to combine rubber sheeting with another material or fabric.
4. Vulcanization: Vulcanization is a crucial step in rubber processing as it imparts strength, durability, and elasticity to the rubber. There are different methods of vulcanization depending on the desired product and application.
- Compression Molding: In compression molding, uncured rubber is placed between heated molds. The rubber compound fills the mold cavity and is cured, resulting in the finished product.
- Injection Molding: In injection molding, preheated rubber is forced into a mold cavity under high pressure. The rubber cures within the mold, producing precision-molded products.
- Latex Processing: To create latex, rubber particles are dispersed into an aqueous phase. Latex dipping machines use a mold that is dipped into the latex compound. After setting, the product is washed, dried, and vulcanized with steam.
- Polyurethanes: Polyurethanes are used to create a variety of products, including flexible foam. In the manufacturing process, gas is released into a reacting mixture of isocyanate and polyol, which forms around the gas bubbles.
Overall, the process of making rubber sheets involves mastication to improve flowability, mixing to incorporate additives, shaping through extrusion or calendering, and vulcanization to impart strength and durability. Each step plays a crucial role in producing high-quality rubber sheets with desired properties.
