RESINS, EMULSION POLYMERS, SYNTHETIC RESINS, EMULSION POLMERS AND COATING PROJECTS

Resin in the most specific use of the term is a hydrocarbon secretion of many plants, particularly coniferous trees. Resins are valued for their chemical properties and associated uses, such as the production of varnishes, adhesives, and food glazing agents; as an important source of raw materials for organic synthesis; and as constituents of incense and perfume. Plant resins have a very long history that was documented in ancient Greece by Theophrastus, in ancient Rome by Pliny the Elder, and especially in the resins known as frankincense and myrrh, prized in ancient Egypt.[1] These were highly prized substances, and required as incense in some religious rites. Amber is a hard fossilized resin from ancient trees.

More broadly, the term "resin" also encompasses a great many synthetic substances of similar mechanical properties (thick liquids that harden into transparent solids), as well as shellacs of insects of the superfamily Coccoidea.

Other liquid compounds found in plants or exuded by plants, such as sap, latex, or mucilage, are sometimes confused with resin, but are not chemically the same. Saps, in particular, serve a nutritive function that resins do not. There is no consensus on why plants secrete resins. However, resins consist primarily of secondary metabolites or compounds that apparently play no role in the primary physiology of a plant. While some scientists view resins only as waste products, their protective benefits to the plant are widely documented. The toxic resinous compounds may confound a wide range of herbivores, insects, and pathogens; while the volatile phenolic compounds may attract benefactors such as parasitoids or predators of the herbivores that attack the plant.[2]

The word "resin" has been applied in the modern world to nearly any component of a liquid that will set into a hard lacquer or enamel-like finish. An example is nail polish, a modern product which contains "resins" that are organic compounds, but not classical plant resins. Certain "casting resins" and synthetic resins (such as epoxy resin) have also been given the name "resin" because they solidify in the same way as some plant resins, but synthetic resins are liquid monomers of thermosetting plastics, and do not derive from plants.

Synthetic resins are materials with a property of interest that is similar to natural plant resins: they are viscous liquids that are capable of hardening permanently. Otherwise, chemically they are very different from the various resinous compounds secreted by plants (see resin for discussion of the natural products).

The synthetics are of several classes. Some are manufactured by esterification or soaping of organic compounds. Some are thermosetting plastics in which the term "resin" is loosely applied to the reactant or product, or both. "Resin" may be applied to one of two monomers in a copolymer (the other being called a "hardener", as in epoxy resins). For those thermosetting plastics which require only one monomer, the monomer compound is the "resin." For example, liquid methyl methacrylate is often called the "resin" or "casting resin" while it is in the liquid state, before it polymerizes and "sets." After setting, the resulting PMMA is often renamed acrylic glass, or "acrylic." (This is the same material called Plexiglas and Lucite).
Types of synthetic resins

The classic variety is epoxy resin, manufactured through polymerization-polyaddition or polycondensation reactions, used as a thermoset polymer for adhesives and composites. Epoxy resin is two times stronger than concrete, seamless and waterproof. Accordingly, it has been mainly in use for industrial flooring purposes since the 1960s. Since 2000, however, epoxy and polyurethane resins are used in interiors as well, mainly in Western Europe.

Synthetic casting "resin" for embedding display objects in Plexiglass/Lucite (PMMA) is simply methyl methacrylate liquid, into which a polymerization catalyst is added and mixed, causing it to "set" (polymerize). The polymerization creates a block of PMMA plastic ("acrylic glass") which holds the display object in a transparent block.

Another synthetic polymer sometimes called by the same general category, is acetal resin. By contrast with the other synthetics, however, it has a simple chain structure with the repeat unit of form -[CH2O]-.

Ion exchange resins are used in water purification and catalysis of organic reactions. See also AT-10 resin, melamine resin. Certain ion exchange resins are also used pharmaceutically as bile acid sequestrants, mainly as hypolipidemic agents, although they may be used for purposes other than lowering cholesterol.

Solvent Impregnated Resins (SIRs) are porous resin particles, which contain an additional liquid extractant inside the porous matrix. The contained extractant is supposed to enhance the capacity of the resin particles.