Phenolic, Melamine, and Formaldehyde Resins Information
Phenolic, melamine, and formaldehyde resins are thermosetting adhesives that form strong bonds and have good resistance to high temperatures. As thermoset materials, they require heat or heat and pressure to cure and to form a secure bond.
Phenolic resins are fairly low in cost. These extremely durable resins are made from chemicals of the phenol group. Typically, phenolic resins are supplied in liquid, powder, and film form. Examples of phenol formaldehyde (PF) resins include phenol-formaldehyde, resorcinol-formaldehyde, resol, and novalac resins. Special PF resins are available that harden at moderate temperatures when mixed with suitable accelerators.
Formaldehyde resins are used in the production of coated abrasives or sanding media. They are also used to make insulation, and to treat textiles to make clothing wrinkle-resistant. In addition to use in resins, formaldehyde is used as an intermediate in the production of industrial chemicals, as a bactericide and fungicide, and as a chemical component in various consumer items.
Melamine resins are used to make yellow coloring for plastics and inks and are also used in the production of consumer products such as kitchenware. Melamine resins are made through a reaction of dicyandiamide with formaldehyde. Most of the resins in this group have excellent dielectric properties. Melamines have a lower molecular weight and are water-soluble, making them useful for laminating or impregnating objects made of other compounds, including paper or board. Melamine resin-impregnated composites are frequently used in furniture and flooring. Melamine resins can also be used to make plastics.
Urea resin adhesives are made from urea, formaldehyde, and catalysts or hardeners. Urea formaldehyde resins can harden rapidly and at moderate temperature. They do not have the properties of phenolic resins, however. Urea formaldehyde resins are used as glue in particleboard and plywood manufacturing. These industrial resins are also used in paper, textiles, laminates, and foundry sand molds.
The most important properties to consider are use temperature, tensile strength, and dielectric strength.
Use temperature is the allowable temperature range in which the compound can operate effectively which determines what environments the resin can be used in.
Tensile strength is the maximum stress a material can withstand while being stretched or pulled before necking deformation occurs.
Dielectric strength is the maximum electric field strength that a material can withstand without breaking down, and is most important when a resin is use with an electrical device.