Phthalic laminating resin

Phthalic laminating Isophthalic corrosion-resin resistant resin... 

The prime function of the saturated acid is to space out the double bonds and thus reduce the density of cross-linking. Phthalic anhydride is most commonly used for this purpose because it provides an inflexible link and maintains the rigidity in the cured resin. It has been used in increasing proportions during the past decade since its low price enables cheaper resins to be made. The most detrimental effect of this is to reduce the heat resistance of the laminates but this is frequently unimportant. It is usually produced by catalytic oxidation of o-xylene but sometimes naphthalene and is a crystalline solid melting at 131°C. 

Novel polyester compositions have also been derived from dicydopentadiene [77-73-6] (DCPD), which can enter into two distinct reactions with maleic anhydride to modify properties for lower cost. These compositions have effectively displaced 0-phthalic resins in marine and bathtub laminating applications. 

Fig. 8. Flexural properties at elevated temperatures. Laminates constructed from alternating plies of 46.7-g (1.5-oz) mat and 746-g/m2 (24-oz/yd2) woven roving at a nominal glass content of 45%. A represents bisphenol fumarate (Tg = 130° C) B, novolak epoxy methacrylate ( T = 130° C) C, epoxy dimethacrylate (Tg = 100° C) D, isophthalic resin (Tg = 100° C) and E, 0/ 0-phthalic resin (Tg = 80° C).

Deanin and Dossi used the propylene oxide-MA reaction to prepare cured polyester resin products in a one-step procedure. In the method explored, the epoxide, MA, phthalic anhydride, styrene, lithium bromide, and benzoyl peroxide were combined, heated to a melt, and cured as castings. The properties of the cured materials were inferior to conventional systems. Others have also studied this concept.A one-step (condensation-addition) polymerization procedure has also been studied as a method for preparing coatings " and laminates with epoxy resins. 

In another approach,hydroxyethyl acrylate was treated with an equimolar amount of phthalic anhydride to obtain 5. Compound 5 (2 moles) was treated with bisphenol-A diglycidyl ether, followed by esterification of the hydroxyl residues by MA to obtain 6. Resin 6 when blended with vinyl monomers, such as styrene, and cured provides excellent flexible coatings, castings, and corrosion-resistant laminates. Modification of this concept has also been used by others to prepare radiation-hardenable coating formulations. 

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