Resins end uses

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. 

Acrylics. Acetone is converted via the intermediate acetone cyanohydrin to the monomer methyl methacrylate (MMA) [80-62-6]. The MMA is polymerized to poly(methyl methacrylate) (PMMA) to make the familiar clear acryUc sheet. PMMA is also used in mol ding and extmsion powders. Hydrolysis of acetone cyanohydrin gives methacrylic acid (MAA), a monomer which goes direcdy into acryUc latexes, carboxylated styrene—butadiene polymers, or ethylene—MAA ionomers. As part of the methacrylic stmcture, acetone is found in the following major end use products acryUc sheet mol ding resins, impact modifiers and processing aids, acryUc film, ABS and polyester resin modifiers, surface coatings, acryUc lacquers, emulsion polymers, petroleum chemicals, and various copolymers (see METHACRYLIC ACID AND DERIVATIVES METHACRYLIC POLYMERS). 

Polyethylene. Polyethylene remains the largest volume film and sheet raw material. It is available in a wide range of types, with variations in copolymers, homopolymers, molecular weight, and other factors contributing to a long Hst of resins. Resins are designed specifically for end use, and in addition blends of the various types may be used by processors to optimize properties, processibiUty, and economics. Almost two-thirds of the volume of all polyethylene resins are used in film or sheet appHcations (see Olefin polymers). 

Engineering problems involved in the production of TEE seem simple compared with those associated with polymeriza tion and processing of PTEE resins. The monomer must be polymerized to an extremely high molecular weight in order to achieve the desired properties. The low molecular weight polymer does not have the strength needed in end use appHcations. 

Poly etrafluoroethylene is manufactured and sold in three forms granular, fine powder, and aqueous dispersion each requires a different fabrication technique. Granular resins are manufactured in a wide variety of grades to obtain a different balance between powder flows and end use properties (Pig. 1). Pine powders that are made by coagulating aqueous dispersions also are available in various grades. Differences in fine powder grades correspond to their usefulness in specific appHcations and to the ease of fabrication. Aqueous dispersions are sold in latex form and are available in different grades. A variety of formulation techniques are used to tailor these dispersions for specific appHcations. 

Flexo and gravure inks are both known as Hquid inks because of their low viscosity. The inks for both systems have basic components in common with inks for other printing processes. Vehicles disperse and carry the pigment, and also contribute most to the end use properties. Colorants provide color. Solvents dissolve resins in the vehicle and determine drying rate. Additives modify ink properties to overcome deficiencies. 

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). 

Formaldehyde. Worldwide, the largest amount of formaldehyde (qv) is consumed in the production of urea—formaldehyde resins, the primary end use of which is found in building products such as plywood and particle board (see Amino resins and plastics). The demand for these resins, and consequently methanol, is greatly influenced by housing demand. In the United States, the greatest market share for formaldehyde is again in the constmction industry. However, a fast-growing market for formaldehyde can be found in the production of acetylenic chemicals, which is driven by the demand for 1,4-butanediol and its subsequent downstream product, spandex fibers (see Fibers, elastomeric). 

Highly branched fractions of nonuniformly branched resins have low molecular weights and are easily soluble, even at room temperature, in saturated hydrocarbons. These highly branched fractions are called extractables, an excessive amount of which in an LLDPE resin can be detrimental to certain end use properties, especially in food packaging appHcations. 

The polymerisation process proceeds in a manner similar to that of other type AABB polyamides, such as nylon-6,6. The final resin had found apphcation in automotive and other high performance end uses but was withdrawn from the market in 1994. 

Proprietary blend formulations based on polysulfone, polyethersulfone, and polyphenylsulfone are sold commercially by Amoco Corporation to meet various end use requirements. The blends based on polysulfone are sold under the MINDEL trademark. A glass fiber-reinforced blend based on PES is offered under the trade name RADEL AG-360. This offers most of the performance characteristics of 30% glass fiber-reinforced polyethersulfone but at a lower cost. Two blend product lines are offered based on PPSF. These are designated as the RADEL R-4000 and R-7000 series of products. The former is a lower cost alternative to RADEL R PPSF homopolymer offering most of the performance attributes unique to PPSF. The R-7000 series of resins have been formulated for use in aircraft interiors for civil air transport. They exhibit a very high degree of resistance to flammabihty and smoke release. 

Amino resins are used by the paper industry in large volume for a variety of apphcations. The resins are divided into two classes according to the mode of appHcation. Resins added to the fiber slurry before the sheet is formed are called wet-end additives and are used to improve wet and dry strength and stiffness. Resins appHed to the surface of formed paper or board, almost invariably together with other additives, are used to improve the water resistance of coatings, the sag resistance in ceiling tiles, and the scuff resistance in cartons and labels. 

The three types of rosin perform differently because of different distributions of resin acids, as well as different types and quantities of impurities. These differences are reflected in end-use performance. 

Although reactivity ratios indicate that VP is the more reactive monomer, reaction conditions such as solvent polarity, initiator type, percent conversion, and molecular weight of the growing radical can alter these ratios (138). Therefore, depending on polymerization conditions, copolymers produced by one manufacturer may not be identical to those of another, especially if the end use appHcation of the resin is sensitive to monomer sequence distribution and MWD. 

Phenolics are consumed at roughly half the volume of PVC, and all other plastics are consumed in low volume quantities, mosdy in single apphcation niches, unlike workhorse resins such as PVC, phenoHc, urea—melamine, and polyurethane. More expensive engineering resins have a very limited role in the building materials sector except where specific value-added properties for a premium are justified. Except for the potential role of recycled engineering plastics in certain appHcations, the competitive nature of this market and the emphasis placed on end use economics indicates that commodity plastics will continue to dominate in consumption. The apphcation content of each resin type is noted in Table 2. Comparative prices can be seen in Table 5. The most dynamic growth among important sector resins has been seen with phenoHc, acryUc, polyurethane, LLDPE/LDPE, PVC, and polystyrene. 

Modified Bismaleimides. Bismaleknide resins may be further modified and blended with other thermoset resins or reactive diluents to achieve either specific end-use properties or processibiUty. Thermoset resins that can be used for modification are unsaturated polyesters, vinylesters, cyanate esters, and epoxies. 

Because of the unusual reactivity of the DCPD molecule, there are a number of wide and varying end use areas. The primary uses in the U.S. are DCPD-based unsaturated polyester resins (36%) hydrocarbon type resins, based on DCPD alone or with other reactive olefins (39%) EPDM elastomers via a third monomer ethylidenenorhornene or DCPD (16%) and miscellaneous uses (9%), including polychlorinated pesticides, polyhalogenated flame retardants, and polydicyclopentadiene for reaction injection mol ding (39). 

Another significant end-use for polyamines is in preparation of paper wet-strength resins. These are polyamide, modified formaldehyde, and polyamine resins used to improve the physical strength of tissue, toweling, and packaging paper products. The cationic formaldehyde resins include both urea—formaldehyde and melamine—formaldehyde types (248,249). Cationic functionaHty is imparted by incorporation of DETA, TETA, and/or TEPA in... 

Most polyesters (qv) are based on phthalates. They are referred to as aromatic-aHphatic or aromatic according to the copolymerized diol. Thus poly(ethylene terephthalate) [25038-59-9] (PET), poly(butyelene terephthalate) [24968-12-5] (PBT), and related polymers are termed aromatic-aHphatic polyester resins, whereas poly(bisphenol A phthalate)s are called aromatic polyester resins or polyarylates PET and PBT resins are the largest volume aromatic-aHphatic products. Other aromatic-aHphatic polyesters (65) include Eastman Kodak s Kodar resin, which is a PET resin modified with isophthalate and dimethylolcyclohexane. Polyarylate resins are lower volume specialty resins for high temperature (HDT) end uses (see HeaT-RESISTANT POLYAffiRS). 

Medical uses for Udel resin include surgical trays, nebulizers, flow controllers for blood, and respiration regulators. Transportation applications center around automotive fuse housings, electrical connectors, and switches. Electrical and electronic end uses include coil bobbins, housings, connectors, bushings, capacitor film, and business machine parts. EinaHy, water, heater dip tubes, milking machine parts, pollution control equipment, and some filtration membranes are made. 

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