Molding Compounds and Resins

Molding compounds and resins are industrial plastics and polymers that are suitable for forming. They are available as pellets, liquids, and powders and are used in processes such as injection molding, compression molding, reaction injection molding (RIM), resin transfer molding (RTM), and blow molding. Examples of molding compounds and resins include thermoset resins, gel elastomers, encapsulants, potting compounds, composites, and optical grade materials. Electrically conductive molding compounds and resins provide low resistivity and are used to prevent electrostatic discharge (ESD), electromagnetic interference (EMI), and radio frequency interference (RFI). Dielectric compounds and insulation materials are also available. Thermally conductive products are applied between a heat-generating electrical device and a heat sink. Dampening products form layers that can bend or flex without cracking or delaminating. Film grade, extrusion grade, and flame retardant molding compounds and resins are also available. 

Molding compounds and resins use many different chemical systems and filler materials. Some chemical systems contain acetals, acrylics, elastomers, natural or synthetic rubbers, epoxy resins, silicone compounds, vinyl systems, polyamides, polyimides, ketones, or styrenes. Other chemical systems contain bismaleimide (BMI) resins, cellulosic or cellulose compounds, cyanoacrylates, ionomers, ethylene copolymers, fluoropolymers, or liquid crystal polymers (LCPs). Commonly used chemical systems also include polybutadiene, polycarbonate (PC), polyethylene (PE), polyester, polyether block amide (PEBA), polyetherimide, polyolefin, polypropylene (PP), polypropylene oxide (PPO), polysulphide, polyphthalamide (PPA), and polyurethane (PU, PUR). For filler materials, some molding compounds and resins contain aramid, chopped, or wound fiber; carbon or graphite powder; or self-lubricated materials. Other products contain glass fillers, metal fillers, or inorganic compounds. Unfilled products are also available. Typically, these raw materials are used as starting components for the production of finished adhesives and compounds.

There are several curing technologies for molding compounds and resins. Most thermoplastics, hot melt adhesives, and thermoset resins are cured using heat or heat and pressure. Vulcanization, a thermosetting reaction, uses heat and/or pressure in conjunction with a vulcanizing agent to produce materials with greatly increased strength, stability, and elasticity. Some products cure or vulcanize at room temperature. Others cure with radiation, electron beam irradiation, visible light, or ultraviolet (UV) light. Single component curing systems consist of a resin that hardens through the application of heat or a reaction with surface moisture. Two-component and multi-component curing systems consist of two or more resins and a hardener, crosslinker, activator or catalyst. 

Selecting molding compounds and resins requires an analysis of physical, mechanical, thermal, electrical, and optical properties. Physical properties include viscosity, melt flow index (MFI), and water absorption. MFI is the output flow occurring in a 10-minute period through a standard die while a fixed pressure is applied via a piston to a 190° C melt. Mechanical properties include tensile strength, tensile modulus, and elongation. Use temperature, deflection temperature, thermal conductivity, and the coefficient of thermal expansion (CTE) are important thermal properties. Resistivity, dielectric strength, and dielectric constant are important electrical properties. Optical properties for molding compounds and resins include index of refraction, a measure of the speed of light in a material, and transmission. 

Molding compounds and resins are used in many industries and applications. Some products are used in aerospace, automotive, laminating marine, military, photonics, optical, or tooling applications. Others are designed for use with electrical power products, high voltage applications, semiconductors, or integrated circuit (IC) packaging. Materials that are suitable for medical, pharmaceutical and food processing applications meet requirements established by the Food and Drug Administration (FDA) and the U.S. Department of Agriculture (USDA). Original equipment manufacturers (OEMs) and repair, maintenance and overhaul (MRO) organizations also use specialty adhesives, sealants and compounds.

• Allyl
  Esters in the allyl family consist principally of diallyl phthalate (DAP) and diallyl isophthalate (DAIP). Both are used as monomers and as prepolymers, which are readily converted to thermoset...
  (read more)
• Phenolic Resins
  Phenolic resins are thermosetting molding compounds and adhesives that offer strong bonds and good resistance to high temperatures. Phenolic or phenol formaldehyde, urea formaldehyde, furan and...
  (read more)
• Two-part Casting Resin
  Two-part casting resins are plastic or elastomer compounds used to cast parts, molds or form a structure in place. They are available in the form of spray foams, "froth-packs", and A + B pourable...
  (read more)

Pages: 1 - 3 of 52