Polyesters resin, cost

SiHcone resins provide coatings having outstanding heat resistance and exterior durabiHty. The cost is relatively high but for specialized appHcations these resins are important binders (64). Silicone-modified acryHc and polyester resins provide binders having intermediate durabiHty properties and cost. Fluorinated polymers also exhibit outstanding durabiHty properties. High cost, however, limits appHcabiHty. 

Vinyl ester resins generally offer mechanical properties superior to those of polyester matrices but at an increased cost. Vinyl esters are chemically similar to epoxy resins but are manufactured via a cold-curing process similar to that used in the manufacture of polyester resins. Vinyl esters offer superior resistance to water and chemical attack and are used in such appHcations as underground pipes, tank liners, and storage tanks (see Vinyl polymers). 

Thermosetting unsaturated polyester resins constitute the most common fiber-reinforced composite matrix today. According to the Committee on Resin Statistics of the Society of Plastics Industry (SPl), 454,000 t of unsaturated polyester were used in fiber-reinforced plastics in 1990. These materials are popular because of thek low price, ease of use, and excellent mechanical and chemical resistance properties. Over 227 t of phenoHc resins were used in fiber-reinforced plastics in 1990 (1 3). PhenoHc resins (qv) are used when thek inherent flame retardance, high temperature resistance, or low cost overcome the problems of processing difficulties and lower mechanical properties. 

Aroma.tic-AUpha.tic Polyester Resins. Unlike most other classes of engineering plastics, which are made by only a few manufacturers, aromatic-aHphatic polyester resins are produced and compounded by several dozen firms (66). The aHphatic polyester resin marketplace is characterized by wide product differentiation and competition. Some firms make only a few hundred tons per year and presumably retain profitabiHty because of the avadabiHty of low cost monomer and the simplicity of the processes employed. Low investment and low manufacturing costs are possible even for smaH-volume operations. 

The Ultem PEI resins compete with PAI, polyarylethersulfone, nylon, and polyester resins in certain markets. General Electric Co. is the sole U.S. manufacturer of PEI resins. High cost coupled with stiff competition from metals and ceramics have limited growth. 

Many other acids, glycols and reactive monomers have been described in the literature but these remain of either minor or academic importance. In a number of cases this is simply because of the high cost of the chemical and a reduction in cost due to its widespread use in some other application could well lead to extensive use in polyester resins. 

Glass fibres are the preferred form of reinforcement for polyester resins since they provide the strongest laminates. Fabrics from other fibres may, however, be used and can in some instances provide adequate reinforcement at lower cost. Glass fibres are available in a number of forms, of which the following are the most important ... 

Over the years many blends of polyurethanes with other polymers have been prepared. One recent example is the blending of polyurethane intermediates with methyl methacrylate monomer and some unsaturated polyester resin. With a suitable balance of catalysts and initiators, addition and rearrangement reactions occur simultaneously but independently to give interpenetrating polymer networks. The use of the acrylic monomer lowers cost and viscosity whilst blends with 20% (MMA + polyester) have a superior impact strength. 

Propylene glycol, i.e., 1,2-propanediol (1,2-PDO), is an important commodity chemical. It is used as biodegradable functional fluids and as precursors for the syntheses of unsaturated polyester resins and pharmaceuticals (9-10). Propylene glycol is currently produced from petroleum-derived propylene via oxidation to propylene oxide and subsequent hydrolysis (9, 11). However, the rising cost of propylene provides an incentive to find a substitute to propylene for this... 

Polyester cloth-backed flat PP sheets (fleece-backed sheets) are normally used to manufacture large reservoirs for liquid containment purposes. Typically, such reservoirs are reinforced on the outside with fiberglass. The polyester mat backing serves as an adhesion key between the PP and the fiberglass resin. Fluorine surface activation can be used as a substitute for the fleece-backed material at a considerable cost-saving. Table 16.12 shows a comparison between the adhesive performance of the materials with two polyester resins. 

Table 21.2 provides a general guide to the effect that chemical constituents can have on unsaturated polyester resin end-use performance. The routes to change an unsaturated polyester resin for a particular application is normally apparent and there can be several pathways available to achieve the desired properties. As the unsaturated polyester resin markets are highly competitive, raw material cost usually reduces the number of available routes available to the formulator. As noted previously, there are three main types or families of unsaturated polyesters, namely general purpose orthophthalic, isophthalic and DCPD resins. However, within each of these families, there are hundreds of variants that incorporate these various chemical constituents in different combinations and permutations to achieve the desired results. 

In addition, fillers can be used for both cost reduction and property modification. Table 21.3 presents some examples of typical fillers and their effects on the unsaturated polyester resin formulation properties. 

The marine industry represents one of the largest markets for unsaturated polyester resins. First introduced to the boating industry in the mid-to-late 1950s, the use of unsaturated polyesters, coupled with their relatively low manufacturing costs, can be credited with opening boating to the mass market. 

Bathtubs, showers and sinks account for significant consumption of unsaturated polyester resins. Fiberglass-reinforced bathtubs and shower stalls account for as much as 90% of the unsaturated polyester used in construction. Unsaturated polyesters have significantly replaced cast-iron bathtubs as a lower-cost material. Similarly, highly filled cast unsaturated polyesters have replaced ceramics and steel in bathroom sinks and countertops. 

Extenders. Materials used in chernical formulations to add bulk or volume and reduce cost.. Extenders range from materials like sawdust, glass fibers, and oils used to add bulk to phenolic resins to water held in a matnx, extending polyester resins. 

EXTENDER. A low-graxily material used in paint, ink. plastic, and rubber formulations chiefly to reduce cost per unit volume by increasing bulk, Extenders include dialomaccou.s earth, wood flock, mineral rubber, liquid asphalt, etc. Microscopic droplets of water fixed permanently in a plastic matrix are an efficient extender tor polyester resins. In the food industry, the term refers to certain extruded proteins, especially those derived from soybeans, which are used in meat products to provide equivalent nutrient values at lower cost. Made from defatted soy flour, they are often called textured proteins. 

This is a low cost material with limited fire-retardant properties. It has a low onset of decomposition (under 100°C), but it is reported to find some use as a fire retardant in unsaturated polyester resins.7... 

A sample calculation for raw material costs (RMC) of a conventional polyester resin synthesis is shown below. 

The high cost of resins used in the production of polymer concrete (PC) makes the material expensive relative to cement-based materials. Not surprisingly, a recent survey ranked lower cost resins as the most important future need for PC [1], Recently, some work has been done on the production of unsaturated polyester resins based on recycled poly (ethylene terephthalate), PET [2], The PET wastes are typically found in used beverage bottles, and many states have passed legislation to collect and recycle these bottles. If specially formulated, the unsaturated polyester could be used in the production of PC [3],... 

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