Wax or oil based adhesives, water based adhesives and solid polymer solutions.
Wax-based adhesives usually contain 3-4 components. The polymer controls the flow viscosity, strength of the green product (green body before sintering), and degreasing characteristics.
The short molecular chain has good molding performance and can minimize the orientation effect in the molding element. Wax or oil is the main filler and is removed in the early stages of degreasing.
Surfactants are used to improve the compatibility of powders and binders.
Plasticizers are used to adjust the flow characteristics of polymers. Water-based binders contain water-soluble polymers, gels, or water glass. This type of binder is usually formed by low pressure to avoid powder and binder separation and reduce mold wear and residual stress. Since water is easily removed, this makes it possible to make thicker components.
The solidification or gelation of the binder solution gives the raw product strength. Before sintering, water is evaporated or sublimated from the raw product to minimize distortion. New binder formulations using polystyrene solid polymer solutions have been used to avoid distortion. The main filler is removed by solution impregnation. Since the structure of the polystyrene cannot be weakened, deformation of the product is avoided. The main filler is a small organic molecule that has both a benzene ring and a polar group. The benzene ring makes it soluble in polystyrene when mixed, and the polar group makes it soluble in solvents such as water or alcohol when degreasing.