Unsaturated polyester resins commercial

Chlorendic Acid. Chlorendic acid [115-28-6] and its anhydride [115-27-5] are widely used flame retardants. Chlorendic acid is synthesized by a Diels-Alder reaction of maleic anhydride and hexachlorocyclopentadiene (see CyclopentadlENE and dicyclopentadiente) in toluene followed by hydrolysis of the anhydride using aqueous base (60). The anhydride can be isolated directly from the reaction mixture or can be prepared in a very pure form by dehydration of the acid. The principal use of chlorendic anhydride and chlorendic acid has been in the manufacture of unsaturated polyester resins. Because the esterification rate of chlorendic anhydride is similar to that of phthalic anhydride, it can be used in place of phthalic anhydride in commercial polyester... 

Maleic anhydride itself has few, if any, consumer uses but its derivatives are of significant commercial interest (161). The distribution of end uses for maleic anhydride is presented in Table 9 for the year 1992 (182). The majority of the maleic anhydride produced is used in unsaturated polyester resin (see Polyesters, unsaturated). Unsaturated polyester resin is then used in both glass-reinforced appHcations and in unreinforced appHcations as shown in Table 10 (183). 

Commercially available MEKP formulations are mixtures of the dihydroperoxide (1), where X = OOH R = H, R = methyl, and R = ethyl (2,2-dihydroperoxybutane [2625-67 ]) and dialkyl peroxide (2), where X = OOH, Y = OOH, R = methyl, and R = ethyl (di(2-hydroperoxy-2-butyl) peroxide [126-76-1J). These formulations are widely used as free-radical initiators in the metal-promoted cure of unsaturated polyester resins at about 20°C. 

The di(hydroxyaLkyl) peroxide (2) from cyclohexanone is a soHd which is produced commercially. The di(hydroxyaLkyl) peroxide (2) from 2,4-pentanedione (11, n = 1 X = OH) is a water-soluble soHd which is also produced commercially (see Table 5). Both these peroxides are used for curing cobalt-promoted unsaturated polyester resins. Because these peroxides are susceptible to promoted decomposition with cobalt, they must exist in solution as equihbrium mixtures with hydroperoxide stmctures (122,149). 

Styrene [100-42-5] (phenylethene, viaylben2ene, phenylethylene, styrol, cinnamene), CgH5CH=CH2, is the simplest and by far the most important member of a series of aromatic monomers. Also known commercially as styrene monomer (SM), styrene is produced in large quantities for polymerization. It is a versatile monomer extensively used for the manufacture of plastics, including crystalline polystyrene, mbber-modifted impact polystyrene, expandable polystyrene, acrylonitrile—butadiene—styrene copolymer (ABS), styrene—acrylonitrile resins (SAN), styrene—butadiene latex, styrene—butadiene mbber (qv) (SBR), and unsaturated polyester resins (see Acrylonithile polya rs Styrene plastics). 

Development of the third class, i.e. unsaturated polyester resins, remained rather slow until the late 1930s, but after commercial production of maleic anhydride by catalytic oxidation of benzene began in 1933, maleic anhydride and fumaric acid rapidly became the most important sources of unsaturated groups in polyesters. The mechanism of drying of these resins on their own and with the addition of drying oils (i.e. unsaturated compounds such as linseed oil) was... 

Unsaturated polyester resins account for the majority of the commercial use of propylene glycol (40%). Other uses include liquid and laundry detergent (15%), cosmetics and pharmaceuticals (12%), antifreeze and deicers (10%), pet food (6%), functional fluids (6%), paint and coatings (4%), and tobacco humectants (3%). 

Ketone Peroxides. These materials are mixtures of compounds with hydroperoxy groups and are composed primarily of the two structures shown in Table 2. Ketone peroxides are marketed as solutions in inert solvents such as dimethyl phthalate. They are primarily employed in room-temperature-initiated curing of unsaturated polyester resin compositions (usually containing styrene monomer) using transition-metal promoters such as cobalt naphthenate. Ketone peroxides contain the hydroperoxy (—OOH) group and thus are susceptible to the same hazards as hydroperoxides. By far the most popular commercial ketone peroxide is methyl ethyl ketone peroxide [1338-23-4]. Smaller quantities of ketone peroxides such as methyl isobutyl ketone peroxide [28056-59-9], cyclohexanone peroxide [12262-58-7], and 2,4-pentanedione peroxide [37187-22-7] are used commercially (47). 

Unsaturated polyester resins account for the majority of the commercial use of propylene glycol. Other uses include food, cosmetics, pharmaceuticals, pet food, and tobacco humectants. 

On the other heind, the linear unsaturated polyester resins find use in memy commercial applications, such as in producing solventless lacquers, and thermosetting molding compounds. The resin is normally prepcured by the reaction of a saturated diol with a mixture of an unsaturated dibasic acid and a modifying dibasic acid or its corresponding anhydride. It is commonly referred to as... 

The materials employed for making hollow microspheres include inorganic materials such as glass and silica, and polymeric materials such as epoxy resin, unsaturated polyester resin, silicone resin, phenolics, polyvinyl alcohol, polyvinyl chloride, polyjM-opylene and polystyrene, among others, commercial jx oducts available are glass, silica, phenolics, epoxy resin, silicones, etc. Table 36 shows low-density hollow spheres. Table 37 shows physical properties of glass microspheres, and Table 38 shows comparison of some fillers on the physical properties of resulting foams (10). 

The products to be considered in this section are commonly called polyester resins. However, they need better definition to distinguish them from several other commercial polyesters which are also called resins. Perhaps the shortest definition is that an unsaturated polyester resin is composed of two major components, one of which is a linear polyester prepared from a glycol and an unsaturated dibasic acid, and the second is a vinyl monomer in which the first is soluble and with which it will copolymerize. The sirup so formed is commonly but incorrectly called a polyester resin. No really effective definition has been devised. The above definition is satisfactory for the sirup. The common name is used for both the copoly-merizable solution and the pol merized final product. In the latter state, the unsaturation has ceased to exist. 

Commercial development of this field was aided by a fortuitous set of circumstances. Maleic anhydride became available commercially shortly prior to World War II and cheap styrene for synthetic rubber during this conflict. Glass fibers in woven cloth form appeared at about the same time. A demand for radomes for aircraft caused a search for a strong lastic material which literally would be a window for radar waves. Glass cloth-reinforced unSaturated polyester resins provided the strength necessary as well as the desired electrical properties. From this commercial start "in 1944, the imsaturated polyester resin production has grown to an estimated 70 million lb in 1956. The major part of the resin is used with reinforcing fibers of some tj e. 

Commercial Uses. Examination of a chart of the physical properties of cured unsaturated polyester resins in cast unrein orced form would... 

Two types of commercially available orthophthalate-type unsaturated polyester resins (UP) were used as liquid resins, together with a 55% DMP(dimethyl phthalate) solution of methyl ethyl ketone peroxide (MEKPO) as a catalyst and a 8% mineral turpentine of cobalt octoate (CoOc) as an accelerator. UP-2 containing CoOc accelerator of 0.75phr (parts per hundred parts of resin). The properties of the unsaturated polyester resins are listed in Table I. 

Between 1930 and the onset of World War II (WWII) in 1939, several polymer families were invented and commercially developed through bulk processes. The most important ones include low density polyethylene (LDPE), poly(methyl methacrylate) (PMMA), polyurethanes (PU), poly(tetra-fluoro ethylene) (PTFE), polyamides (PAs), and polyesters (PEs). The last three are attributed to Dupont s scientists Roy Plunkett and Wallace Carothers, respectively. During WWll, bulk polymerization was still instrumental in the development and commercialization of new families of PEs such as polyethylene terephthalate (PET) developed by ICI and Dupont and unsaturated polyester resins (UPRs) [1, 6-8]. 

Maleination of soybean oil is interesting as it has been shown to produce two wildly different polymer structures. Maleic anhydride-modified soybean oil was polymerized with styrene to give a hard, rigid polymer modification improved modulus, strength and glass transition values when compared to the unmodified polymerized oil [45], These also showed comparable strengths to commercial unsaturated polyester resins. In contrast, by using diols as the comonomer, maleinated soybean oil was used to form soft, resilient rubbers at room temperature [46]. 

Flame-retarded unsaturated polyester resins are by now ordinary commercial products,... 

Finally, the unsaturated polyester is free-radically cross-linked by copolymerization with, for example, styrene or methyl methacrylate. Mixtures of the actual unsaturated polyester with these monomers are commercially known as unsaturated polyester resins. The properties of the thermosets can be matched to the application by variations in the acids, glycols, or vinyl monomers. Copolymerization with electronegative comonomers such as styrene or vinyl acetate leads, for example, to alternating copolymers, that is, to short cross-link bridges and therefore, to more rigid thermosets. Alternatively, electropositive comonomers such as methyl methacrylate form long methyl methacrylate bridges between the polyester chains and so produce more flexible polymerizates. 

Thermosets can be divided into several classes depending on the chemical composition of the monomers or pre-polymers (resins). Important thermosetting resins in current commercial applications are the condensation products of formaldehyde with phenol (phenolic resins), urea or melamine (amino resins). Other major classes are epoxy resins, unsaturated polyester resins, allyl resins and isocyanate resins. 

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