Saturated polyester resins properties

Coil Coating. On account of their outstanding hardness-elasticity balance, good adhesion to metals, good application properties, and favorable cost, paints based on saturated polyester resins represent the most important system for coil coating. 

Cyclohexyl acetate [622-45-7] is very slightly miscible with water, but completely miscible with common organic solvents. Its solvency properties are comparable to those of amyl acetate. Cyclohexyl acetate dissolves oils, fats, resins, waxes, cellulose nitrate, cellulose tripropionate and acetobutyrate, alkyd resins, unsaturated and saturated polyester resins, phenolic resins and aminoplasts, poIy(vinyI chloride), vinyl chloride copolymers, poly(vinyl acetate), poly(vinyl ethers), epoxy resins, and acrylic resins, basic dyes, blown oils, crude rubber, metallic soaps, shellac, and bitumen. 

Polyester resins possess premium performance properties such as exterior durability, gloss, flexibility hardness, color stability, and versatility of cure. Polyesters are used in product finishes for household appliances, food and beverage containers, aircraft and equipment, automotive primers and bake coats, metal furniture, and fixtures. For example, water-soluble saturated polyesters are used in industrial baking paints, and in combination with melamine resin. Polyesters can be formulated in high solids and waterborne formulations to meet the requirements for the low VOC coatings being mandated by the EPA. 

Classification and Properties of Alkyd Resins Formulation and Design of Alkyd Resins Uses of Alkyd Resins Saturated Reactive Polyesters Resin Systems for Reduced Solvent Emissions Low-Solvent and Solvent-Free Alkyd Resins... 

The saturated acid (phthalic anhydride) helps to reduce the cross-link density and, hence, the brittleness of the cured polyester resin. Resin composition can be varied so that product properties can be tailored to meet specific end-use requirements. For example, a resin with enhanced reactivity and improved stiffness at high temperatures is obtained by increasing the proportion of unsaturated acid. On the other hand, a less reactive resin with reduced stiffness is obtained with a higher proportion of the saturated acid. 

These polyester resins use isophthalic acid in place of phthalic anhydride as the saturated monomer. This increases the cost to produce, but it improves physical properties and corrosion resistance. 

The constitution of the unsaturated polyester resin used to make a gelcoat is obviously a prime factor in determining its weathering performance. Base polyesters (which are subsequently dissolved in the monomer) are made by reacting together saturated and unsaturated diacids and diols, and variation of these ingredients enables properties such as flexibility, heat distortion... 

Polyethylene terephthalate (PET, polyethylene glycol terephthalate) n. A saturated, thermoplastic polyester resin made by condensing ethylene glycol, and terephthalic acid, used for textile fibers, water-clear, biaxially oriented film (e.g., Mylar ) and, more recently, for extruded, thermoform-able sheet (TV-dinner trays), injection-molded parts, and large, blow-molded, soft-drink bottles. It is extremely hard, wear- and chemical-resistant, dimensionally stable, and has good dielectric properties. See also polyester, saturated and crystallized polyethylene terephthalate (See image). 

Because of their lesser ability to control shrinkage, the non-polar polymers such as polystyrene and polyethylene are often classified as low shrink rather than low profile additives. Usually, low profile additives are supplied as 30-40% polymer solutions in styrene monomer. Polyester resin manufacturers also package the low profile additives dissolved in their resins. These are referred to as one pack systems. As the industry has expanded, other thermoplastics have been identified which have shrinkage control properties. These are also now used commercially in a variety of applications. Examples of these other polyers are saturated polyesters, polyurethanes, stryene-butadiene copolymers and polycapro-lactones. Polyfvinyl acetate) based materials are probably still the most used low profile additives, being useful with the broadest range of unsaturated polyester resin structures. Relative proportions of the organics used in most formulations are 30-50% polyester alkyd, 10-20% thermoplastic and 40-50% styrene. 

The compression, impact, and fracture properties of many cured unsaturated polyester resin formulations have been studied and reviewed.The compressive strengths of the rigid cured polyesters are of the order 15,000-30,000 psi. Cyclic glycols and specialty fumarate resins tend to raise this value, while aliphatic saturated acids lower the compressive strength. For aliphatic acids, the impact strength is proportional to the acid chain length. 

Polyacrylic resins were employed to study how immobilization resin particle size influences Candida antarctica Lipase B (CALB) loading, fraction of active sites, and catalytic properties for polyester synthesis. CALB adsorbed more rapidly on smaller beads. Saturation occurred in less than 30 seconds and 48 h for beads with diameters 35 and 560-710 pm, respectively. Infrared microspectroscopy showed that CALB forms protein loading fronts for resins with particle sizes 560-710 and 120 pm while CALB appears evenly distributed throughout 35 pm resins. The fraction of active CALB molecules adsorbed onto resins not influenced by particle size was less than 50 %. At about 5% w/w CALB loading, decrease in the immobilization support diameter from 560-710 to 120,75 and 35 pm increased conversion of s-CL to polyester (20 to 36, 42 and 61%, respectively, at 80 min). Similar trends were observed for condensation polymerizations of 1,8-octanediol and adipic acid. 

Polyester, epoxies, acrylics, vinyl esters, and silicones have aU been used in pultru-sion, but the largest percentage of the products are vinyl esters and polyesters because of their favorable costs, desirable properties, and easy handling characteristics. Liquid systems with low viscosity are used to ensure rapid saturation of the fiber bundles. The resin determines the weather resistance, thermal resistance, burning characteristics, moisture sensitivity, chemical resistance, and most of the electrical properties. 

Unsaturated polyesters (UP) are by far the most widely used resins in the composite industry [49]. UP resins are used in the highest volume due to their relatively low cost and good combination of thermo-mechanical properties and environmental durability. Typical properties of a cast UP resin are reported in Table 8.2. A UP resin is usually obtained from unsaturated polyesters dissolved in a reactive monomer. Unsaturated polyesters are linear polymers obtained by a condensation reaction between three chemical species saturated aromatic acids, unsaturated acids (maleic anhydride, fumaric acid), and glycols... 

Epoxy resins are widely used as protective coatings and adhesives, for structural applications such as adhesives to bulk out structural components, with extensive use in the aerospace, dental and other medical fields. Moreover, epoxies are widely used as insulating and structural materials in manufacturing microelectronic devices and components such as computer chip packing and circuit boards, due to their excellent combination of chemical and corrosion resistance and good electrical properties. On the other hand, unsaturated polyester (UPE) resin, a resin prepared from a polyester synthesized by esterification of glycol, unsaturated acid and saturated acid dissolved in styrene monomers, is widely used in many applications, such as electronic equipment, containers, automobiles, and cultured marble because of its clarity, and excellent chemical and corrosion resistance. 

Vinyl Esters. These resins include chemical features of both epoxies aud polyesters. Vinyl ester resins offer better chemical resistance, somewhat higher temperature limits, aud better solvent resistance than ordinary polyesters but generally do not compare to epoxies in these properties. Vinyl ester resins are preferred over polyesters because they are more chemical-resistant than the isophthalics and less brittle than the bisphenol A fumarates. Typical services are in fertilizer plants (acid lines), chlorine plants (chlorine-saturated briue hues), and paper mills (caustic and black-hquor lines). 

Chemical, electrical, and thermal properties The chemical building blocks of the polyester, the molar ratio of maleic anhydride to saturated dicarboxylic acid, and the choice and content of the monomer dictate to a large extent the mechanical properties (rigid or flexible), the glass transition temperature (Tg) or HOT (heat deflection temperature), and the thermal and chemical resistance of the cured products. Additives are available for use with many resin systems to provide properties such as color, high surface finish, UV resistance, and low shrinkage. 

Polyester. Polyesters are a large class of synthetic resins having widely varying properties. They may be divided into two distinct groups saturated and unsaturated. 

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