Speciality Polyester Resins

In speciality polyesters, raw materials are selected judiciously to improve the properties and performance of the resin with compromise of the cost. Speciality resins are used if high mechanical strength, and resistance to chemicals and corrosion, is required. Use of a non-polar glycol such as polypropylene glycol and poly(butylene glycol) contributes towards the water resistance and corrosion resistance. Three types of speciality resins are used isopthalic resin, chlorendic resin, and BPA fumerate resin. Typical formulations of speciality UPE resins are given in Table 2.5. 

Isopthalic resins are based on isopthalic acid and maleic anhydride. Incorporation of isopthalic acid causes an increase in UPE of the resulting polyesteg which exhibits good mechanical properties, chemical resistance, and thermal resistance. The correlation between corrosion resistance and polyester structure is not well established. In general, if the ester is sterically crowded and there are fewer ester groups in the chain, good chemical resistance and corrosion resistance are achieved [60]. 

BPA fumarate resins are prepared by the reaction of propoxylated BPA with fumeric acid. The use of BPA results in a significant reduction in the number of ester linkages and makes the resin comparatively non-polar. This resin therefore shows very good corrosion resistance and chemical resistance. BPA fumerate resin-based composites 

Cblorendic resins are prepared by reacting propylene glycol with a combination of endomethylenehexachloropthalic anhydride (cblorendic anhydride) and phthalic anhy-dride. This resin shows excellent corrosion resistance and fire retardancy (due to the presence of chlorine) when used as a matrix for fibre-reinforced composites. Cblorendic resins are used in applications that require exceptional resistance to acidic and oxidising environments. In recent years, BPA fumarate resins have been extensively replaced by cblorendic resins for various industrial applications. 

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Among various rubbery polymeric materials, a special polyester resin has been developed as a binder in view of its curing at ambient temperature, low viscosity (as a result of addition of vinyl monomers) without appreciable sedimentation of explosives. In addition, polyester resin has the greatest advantage of having an oxygen moiety in the skeleton which increases oxygen balance of the final sheet,... 

Specialized polyester resins are commonly used in processes such as hand lay-up and spray-up, to provide an attractive and weather-resistant surface finish to molded parts. These gel coats are sprayed onto the mold before the reinforcement is introduced. In addition to their cosmetic function, gel coats can also provide the RP surface with resistance to impact and abrasion. There is also anti-bacterial additive technology to gel coats, especially for applications such as baths and... 

Table 2.6 Themomechanical )roperties of speciality polyester resins ...

Synthetic Applications. Oxazolines, which ate synthesized as indicated above, have been utilized in many different appHcations (25). When used in resin formulations, AMP, AEPD, and TRIS AMINO can incorporate the oxazoline stmeture into the polymer stmeture (26). Because they ate polyols, both AEPD and TRIS AMINO can be used in polyester resin modification. Oxazoline alkyd films ate characterized by improved performance, particularly salt-spray resistance and gloss (see Alkyd resins Coatings, special purpose, high performance). 

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. 

Polyester resins, reinforced with fiberglass, have good strength and good chemical resistance except to alkalies. Some special materials in this class, based on bisphenol and vinyl esters are more alkali-... 

The demands on insulating materials in soil and fresh water are relatively low. Anodically evolved oxygen makes the use of aging-resistant insulating materials necessary. These consist of special types of rubber (neoprene) and stabilized plastics of polyethylene, and polyvinylchloride, as well as cast resins such as acrylate, epoxy, polyester resin and many others. 

Specially formulated polyester resin that is pigmented and contains fillers. Provides a smooth, pore-free surface for the plastic article. 

Polyurethane mortar flooring systems based on somewhat similar technology to this special polyester system have also been used in chemical plants and have given excellent service. The basic urethane polymer is more elastomeric than either epoxy or polyester resins and, as such, is reported to have excellent thermal properties up... 

Syntactic foams are less combustible than their chemically foamed counterparts for the same reason. A syntactic foam s fire resistance can be increased using modifiers and additives in much the same way as for ordinary plastics, the only additional precaution being that the filler—binder adhesion should not be impaired in the process. Specially compounded polyester resins have been used in the USSR to obtain syntactic foams, whose combustion times and mass losses are, respectively, 4-60 and 24 to 180 times lower than those of the unmodified plastic 155). 

Phosphate esters (alkyl or aryl, or mixed) of phosphoric acid constitute an important family of organophosphorus flame retardants.25 Triethylphosphate, a colorless liquid boiling between 209°C and 218°C, and containing 17 wt % phosphorus, has been used commercially as an additive for polyester resins/laminates and in cellulosics. In polyester resins, it functions as a viscosity depressant as well as a flame retardant. Trioctylphosphate is employed as a speciality flame-retardant plasticizer for vinyl composites where low temperature flexibility is critical. It can be also included in blends, along with general purpose plasticizers, such as phthalate esters, to improve low temperature flexibility. 

Epoxy vinyl ester resins are a special class of unsaturated resin. This resin is made by capping an epoxy resin with methacrylic acid and then dissolving in styrene monomer to the desired viscosity. This gives mechanical properties similar to epoxy resins, but the processibility (low viscosity allowing for resin infusion processes) of an unsaturated polyester resin. As with unsaturated vinyl esters, the most common fire retardant vinyl ester resin is based on a resin made from a halogenated system, tetrabromobisphenol A. The level of bromine in the resin and the presence of antimony will determine the fire performance of the resin. These resins are normally used for corrosion resistant equipment or when fire performance and high mechanical properties are required. It is very difficult to get a low smoke value with a brominated vinyl ester resin again due to the fact that bromine... 

There are basically two types of epoxy acrylate resins used in formulating adhesive systems. One is a vinyl ester resin that is used in two-component adhesive formulations much as a DGEB A epoxy or a polyester resin is. The other is a special type of resin that is used in radiation cure processes. This latter type of epoxy acrylate does not have any free epoxy groups, but reacts through its unsaturation. 

A wide variety of special durable surface treatments have been used on manufactured fibers. These include treatments for imparting such characteristics as soil resistance, antistatic behavior, and wearer comfort through moisture wicking and transport. Fiber finishes also have been used successfully in promoting adhesion between two materials, as, for example, between polyester tire cord and rubber, and between glass fiber and polyester resin. 

Provisional technical information is given for Uvecoat 3003, an unsaturated polyester resin for use in UV-curable powder coatings. The resin has been specially developed for use as a clear topcoat for PVC based resilient flooring,... 

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