Unsaturated polyester binders

UP resins are soluble linear polycondensation products made from polyvalent -usually unsaturated - acids (e.g. maleic or fumaric acids) and bivalent alcohols (e.g. ethylene glycol and/or 1,2-propylene glycol). For special applications, it is common to substitute some of the a, -unsaturated dicarboxylic acids with phthalic acid and/or adipic acid. Seminal work on unsaturated polycondensation products made from maleic acid, maleic acid anhydride and glycols and on their copolymerisation with styrene is listed in [2.100], 

The wide range of UP resins on the market covers products which require the addition of paraffin wax through air-drying, UV-curing, amine-accelerated or flex-ibilising products to styrene-free and/or water-dispersible resins. 

World production of UP resins in 1995 - including those for captive use - is estimated at around 200,000 tonnes. Of this amount, 60,000 tonnes are produced in western Europe where roughly two-thirds are used in furniture coatings and the remaining one-third in fillers. 

UP Resins for Fillers. Tack-free films are also obtained if phthalic acid anhydride is substituted with tetrahydrophthalic acid anhydride [2.104]. The addition of en-domethyl tetrahydrophthalic acid anhydride (a cycloaddition product of maleic acid and cyclopentadiene) also has a positive effect on the air-drying properties [2.105]. Both product classes have become popular above all in the manufacture of binders for highly extended fillers for vehicle repair applications. 

Air-drying UP Resins. Air-drying UP resins, also known as gloss polyesters, are 

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Thermosets A number of thermosets have been used as adhesives. Phenolic resins were used as adhesives by Leo Baekeland in the early 1900s. Phenolic resins are still used to bind together thin sheets of wood to make plywood. Urea resins have been used since 1930 as binders for wood chips in the manufacture of particle board. Unsaturated polyester resins are used for body repair and PUs are used to bond polyester cord to rubber in tires, and vinyl film to particle board, and to function as industrial sealants. Epoxy resins are used in the construction of automobiles and aircraft and as a component of plastic cement. 

Other common binders include nitrocellulose (acetone as the solvent), polyvinyl alcohol (used with water), and Laminae (an unsaturated polyester crosslinked with styrene — the material is a liquid until cured by catalyst, heat, or both, and no solvent is required). Epoxy binders can also be used in hquid form during the mixing process and then allowed to cure to leave a final, rigid product. 

Many investigators have studied the effect of binders and their percentages on the efficiency of illuminating formulations. In general, the luminosity and luminous efficiency increase to a maximum at =4—6% of the binder and thereafter decrease. It has also been reported that binders with high oxygen content, such as unsaturated polyesters and epoxy resins, improve the efficiency... 

With the advancement of polymer chemistry, a wide range of polymers are now available for use as binders for HEMs. The extensive use of polymers such as unsaturated polyesters, epoxy resins, epoxy-PS blends and VAARs as binders for illuminating formulations has been reported in the literature. The chemistry of unsaturated polyesters and epoxy resins has already been discussed in Chapter 4 on propellants. Some salient features of liquid PS and its blends with epoxy resin and VAARs are given in this section. 

The matrix is considered to be the binder for the microspheres. Typical matrix materials include (a) thermosetting resins such as epoxy resins, unsaturated polyesters, vinyl esters, phenolics, polyurethanes, and silicones (b) thermoplastic resins such as polyethylene, polystyrene, polyvinyl chloride (c) asphalt and (d) gypsiun and cement. 

The recovered glassfiber-resin powder was tested as a filler for polymer mortars[3]. The mortars were composed of filler, silica sand and binder, dried for one day, and cured at 70°C for 15 hrs. A glassfiber-resin powder and a calcium carbonate powder for comparison (each with an average size of 52 // m) were used as fillers. Bisphenol F type epoxy resin, poly methacrylic methyl (PMMA), and unsaturated polyester (UP) were used as binders. 

This important product was successfully employed as a flame retardant cross-linker for curable unsaturated polyesters as well as for reinforced polyesters, epoxy resins, rigid polyurethanes and synthetic latioes and binders in textile and p>aper manufacturing (22, 25, 26). 

A typical two package polyester cement consists of an unsaturated polyester (41), cellulose acetate butyrate or polyvinyl acetate (1.8) and N,N-dimethylaniline (1) dissolved in styrene (18). This liquid (binder) is intimately mixed with a filler consisting of graded silica or solid glass spheres (15.5), talc (23), titanium dioxide (1.0) and benzoyl peroxide (1.0). 

When polymerization is used as the hardening principle, reactive components combine to form the binder, e.g., unsaturated polyesters with styrene or acrylate monomers. Here, one component often behaves as a reactive solvent for the other, and low-emission coating systems are the result. Cross-linking can be carried out at room temperature (cold curing) or by radiation curing. 

Polyester Paints. Binder based on unsaturated polyester resins (copolymerized with styrene), low emission of organic solvents, catalytic curing by organic peroxides or UV radiation, highly resistant to abrasion, alcohols, and other chemicals (cleaning agents). 

Formulation of SMC/BMC compounds is a very sophisticated balance of many ingredients to enhance specific properties and/or act synergistically with other components. Most SMC/BMC formulations have three main elements binder, filler and fiber reinforcement, from a choice of ingredients such as unsaturated polyester resin, monomer, catalyst, inhibitor, fillers, TP anti-shrinkage additives, flame-retardant, thickener, release agent, and glass fiber reinforcement. 

The plastic binder is added as a solution in acetone. Most of the solvent evaporates during mixing and granulation. This is not a standardized formula but similar "castable mixtures have been reported by others. Unsaturated polyester with added styrene has also been tried for this purpose. 

Lflmwffc—Proprietary name for a plastic binder material, a polymerizable unsaturated polyester. 

Other Binders. Unsaturated polyester resins are maleic acid-containing polyesters dissolved in styrene. The resin/styrene solution is cross-linked using free-radical initiators. The polymerization is oxygen inhibited. Inhibition is minimized by incorporating some insoluble semicrystalline paraffin wax. The wax layer results in a relatively uneven, low gloss surface, suitable for some applications. 

NIR is also being used to measure the binder and loss on ignition (LOI) of unsaturated polyester-... 

The unsaturated polyester resins are used as fire retardants, binders, and powder coatings [79], and in the reinforced plastics industry. Fire-retardant polyester resins generally contain halogen in the acid or glycol component, or other... 

Unsaturated polyesters are the main binders for the 2-billion-pound reinforced plastics industry, and they are of importance in automobile bodies, boat hulls, building panels, chemical piping, and so forth. Indeed, if binders for reinforced plastics were classified as adhesives, the unsaturated polyesters would top the list. 

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