Unsaturated polyester resin Isophthalic resins

Processes have been developed separating pure metaxylene from other Cj aromatics.Metaxylene is a raw material for the manufacture of isophthalic acid. The major outlets for the acid are in the synthesis of unsaturated polyester and alkyd resins, and for the production of isophthalic esters (plasticizers). 

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. 

The unsaturated polyester resins used to produce gel-coat formulations can be classified into three categories, i.e. orthophthalic-, isophthalic- and neopentyl-glycol-based. The first two types are used in perhaps two thirds of all... 

Unsaturated Polyester Resins. Unsaturated polyester resins are widely used as fiber-reinforced plastics, coating materials, tire cords, films, and casting or molding resins. Organic titanates such as TYZOR TPT, TYZOR TBT, or TYZOR TOT can be used to catalyze the preparation of the resins, which involves the polyesterification of a mixture of a- and p-unsaturated polybasic acids, such as maleic or fumade acid, and alicydic polybasic acids, such as adipic or isophthalic acid with polyhydroxyalcohols (489). 

Isophthalic Acid. Although m-xylene is an abundant material, it has limited demand as a chemical raw material. The only major outlet is in the manufacture of isophthalic acid. More than 220 million pounds were produced in the United States in 1992, primarily for use in preparing alkyd resins and unsaturated polyester resins. Small amounts also are used in PET bottle applications. 

Chem. Descrip. Isophthalic unsaturated polyester resin Uses Polyester tor gelcoats... 

Isophthalic add is produced by only a small number of companies in the USA (Amoco% Japan Mitsubishi Gas Chemical) and Italy Sisas). Its main use is in the production of unsaturated polyester resins. It yields polyesters of greater strength and higher resistance to corrosion than those derived from phthalic add. 

Isophthalic acid (benzene-1,3-dicarboxylic acid, IPA) n. C6H4-(COOH)2. Used instead of phthahc anhydride in making unsaturated polyester resins that, when cured, have good stifihess and resistance to heat and chemicals. Molecular weight, 166.13. Crystalline powder, which melts at 345-348° C sublimes without decomposition. Merck index, 13th edn. Merck and Co. Inc., Whitehouse Station, NJ, 2001. 

PCL (M =70,000-100,000) has been blended with uncured, unsaturated polyester resin which was subsequently cured [170]. The unsaturated oligomeric resin (M =1000) was a copolyester formed from isophthalic acid, fumaric acid and propylene glycol (in the molar ratio 1 1 2.2) and contained 33 wt % styrene monomer. The resins were cured by adding benzoyl peroxide and heating, in stages, from 60 °C to 120 °C. 

Unsaturated polyesters are generally very brittle materials. The tensile elongation for most UPRs is in the range of 1 % for dicyclopentadiene (DCPD)-based polyester resin to about 2.5 % for isophthalic acid and propylene glycol resins. This 1 % elongation posts a problem for using DCPD resin in making a... 

Polymer concretes show excellent mechanical properties and chemical resistance compared with conventional cement concretes. Polymer concretes can be cured quickly by the use of curing agents. Thus, the applications of polymer concretes are being increased. One of the popular polymers for polymer concretes is unsaturated polyester (UPE) resin. The properties of UPE resin can be modified by changing its molecular features. For the synthesis of the resin, phthalic anhydride or isophthalic acid as well as maleic anhydride can be employed to modify the mechanical properties or hydrothermal resistance. Terephthalic acid which is also used for the synthesis of poly ethylene terephthalate (PET) enhances the thermal resistance of the cured UPE resin. However, the synthesis of unsaturated polyester resin from terephthalic acid is difficult. One method to synthesize unsaturated polyester from terephthalic acid is the use of recycled PET. 

Unsaturated polyesters are the most versatile class of thermosetting polymers. They are macromolecules made up of an unsaturated component, (i.e., maleic anhydride or its trans isomer, fumaric acid, which provides the sites for further reaction) and a saturated dibasic acid or anhydride with dihydric alcohols or oxides (typically phthalic anhydride which can be replaced by aliphatic acid, like adipic acid, for improved flexibility). If blends of phthalic anydride (or isophthalic acid) and maleic anhydride/fumaric acid are used, ortho (or iso) resins (Figure 6.18) are obtained. On the other hand, if propoxylated or ethoxylated bisphenol A is used with fumaric acid, bisphenol A fumarates are obtained, if a blend of chlorendic... 

In the coating industry, polyesters are characterized by resins based on components that introduce unsaturation (—C=C—) directly into the polymer backbone. The most common polyester resins are polymerization products of maleic or isophthalic anhydride or their acids. In producing paint the polyester resin is dissolved in styrene monomer, together with pigment and small amounts of inhibitor. A free radical initiator, commonly a peroxide, and additional styrene are packaged in another container. When applied, the containers are mixed. Sometimes, because of the fast initiating reaction (short pot life) they are mixed in an... 

Every attempt has been made to ensure as comprehensive an index as possible, without an inordinant number of main or sub-classifications. It has therefore been necessary on occasion - and applying particularly to unsaturated polyesters - to be selective, choosing only those descriptions - typically the two which appear the most important - as sub-classification. However at the same time, much depends on the resin property, application or other description initially provided by the manufacturer or supplier, and here some assumptions have proved necessary. Further, such understood property descriptions such as for example corrosion-resistant for isophthalic-NPG resins, have not been included. 

Unsaturated Polyester - Laminating Resins - continued Isophthalic type - DCPD modiried... 

The properties similar to polycarbonates show polyarylate resins, synthesized usually by polycondensation process from terephthalic acid, isophthalic acid chloride, and BPA (Fig. 7.18). Polyarylates exhibit good impact strength, high deflection temperature, good chemical, thermal, weather and UV resistance as well as the dimensional stability higher than that of polycarbonates. Other important polymers with industrial significance, derived from BPA, are unsaturated polyesters (e.g., epoxyfuma-rate resins) [78], polyetherimides and polyether ether ketones (Fig. 7.18). 

In addition to MA, phthalic anhydride, and ethylene glycol, other common intermediates used for the production of unsaturated polyesters are fumaric acid, isophthalic acid, adipic acid, propylene glycol, diethylene glycol, and dipropylene glycol. Table 12.1 provides a summary of both common and specialty building blocks used in polyesters and contributions made by these intermediates to the properties of the products. Recycled polyethylene terephthalate beverage bottles may one day become an important raw material for unsaturated polyester resin production, providing an alternative for a substantial part of the petroleum-based intermediates. 

The resistance of cured unsaturated polyesters to chemical attack, i.e., corrosion resistance, has been the subject of many studiesand the subject of several reviews.In general, polyester resins containing cyclic hydroxy compounds, such as hydrogenated bisphenol-A and 1,3- or 1,4-cyclohexanediol or 1,4-cyclohexanedimethanol, have improved chemical resistance.Chemical resistance may also be obtained by employing neopentyl glycol, isophthalic acid trimethyl pentanediol, and propoxylated... 

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