Radiation curing polyester resin

Polyester resins are cured by organic peroxides that initiate a free radical copolymerization reaction. This can occur at room temperature, under heat [60-90C (140-194F) or by UV or visible light radiation. The possibility of cold-curing polyester resins from the liquid state is one of... 

Uses Carboxylated comonomer for polyacrylic and polymethacrylic acids, other acrylic acids, acrylic polymers, styrene-butadiene, vinyl acetate, nitrile latex comonomer for radiation-cured polyester/polyurethane resin paints antimigrant for pigment pad dyeing pigment print emulsifier... 

The free radicals then initiate curing by attacking residual double bonds in acrylic oligomers and monomers, or in styrene and unsaturated polyester resins. Since most pigments absorb u.v. radiation and can prevent it reaching sufficient photoinitiator molecules, this technique is best suited to transparent coatings or thin pigmented layers (e.g. inks). 

Coating materials may be based on short or medium-oil alkyds (e.g. primers for door and window frames) nitrocellulose or thermoplastic acrylics (e.g. lacquers for paper or furniture finishes) amino resin-alkyd coatings, with or without nitrocellulose inclusions, but with a strong acid catalyst to promote low temperature cure (furniture finishes) two-pack polyurethanes (furniture, flat boards) unsaturated polyester resins in styrene with free-radical cure initiated by peroxides (furniture) or unsaturated acrylic oligomers and monomers cured by u.v. radiation or electron beams (coatings for record sleeves paperback covers, knock-down furniture or flush interior doors). 

The free-radical cure mechanism of the vinyl ester resins is well understood. In most respects, it is similar to that of the unsaturated polyester resins. To initiate the curing process, it is necessary to generate free radicals within Ike resm mass. Organic peroxides are tlie most common source of free radicals. These peroxides will decompose under the influence of elevated temperatures or chemical promoters, e.g., organometallics or tertiary amines, to form free radicals. Generation of free radicals also can be effected by ultraviolet or high-energy radiation applied directly to the resin system. The free radicals thus formed react to open the double bond... 

There are basically two types of epoxy acrylate resins used in formulating adhesive systems. One is a vinyl ester resin that is used in two-component adhesive formulations much as a DGEB A epoxy or a polyester resin is. The other is a special type of resin that is used in radiation cure processes. This latter type of epoxy acrylate does not have any free epoxy groups, but reacts through its unsaturation. 

Radiation curing adhesives are generally applied as solvent-free liquids. High-solids EB and uv curing liquid adhesives have been formulated from a variety of resins and elastomers. They include epoxy acrylates, epoxies, other acrylates, polyesters, blends of acrylate monomers with elastomers, and other compositions. 

As an alternative to PEG treatment of waterlogged wood, attempts have been made to use a radiation curing method involving a range of monomers and resins. The aim of such treatments is to reduce treatment times and achieve a more stable artefact. Styrene, vinyl acetate, acrylonitrile, acrylates and methacrylates are the most studied monomers in the treatment of waterlogged archaeological wood. The most widely used of these monomers is the water-soluble vinylpyrrolidone and methacrylamide and the non-water soluble chemicals such as n-butyl methacrylate monomer or unsaturated polyester resin. 

The polymerization kinetics were studied via time-conversion relationships at different dose rates (Figures 6-9). The radiation curing was carried out at room temperature in closed aluminum capsules. Percent monomer conversion was determined gravimetrically for N-vinylpyrrolidone. Evaporation was accomplished under vacuum in a ventilated oven at 50 °C until the weight was constant. For butyl methacrylate and polyester resins, the residual monomer content was determined by gas chromatographic analysis after immersion of the cured products in acetone. 

Jurkin, T. and Pudc, 1.2006. Post-irradiation crosslinking of partially cured unsaturated polyester resin. Radiat. Phys. Chem. 75 1060-1068. 

Pucid, I. and Ranogajec, F. 1995. DC-electrical conductivity as a method for monitoring radiation curing of unsaturated polyester resins. 1. Measurement conditions and comparison with extraction analysis data. Radiat. Phys. Chem. 46 365-370. 

Radiation Curing. The cross-linking of acrylate-modified polyester resins with U V radiation or an electron beam is an energy-saving alternative to the heat-curing systems. Reactive diluents (e.g., polyfunctional acrylates) are required to adjust the viscosity for application although they increase reactivity, they reduce the flexibility and substrate adhesion of the paint film. 

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). 

Chem. Descrip. Polyether triol containing primary hydroxyl groups Uses Flow aid, leveling agent, abrasion resist, aid for radiation-curable monomers, urethane and polyester resins, high-solids coatings, polyester resin synthesis reactive modifier for UV cationic cure systems Features Good compat. with resin systems Properties Lt. yel. clear liq. m.w. 240 sp. gr. 1.1 dens. 9.2 Ib/gal vise. 800-900 cps hyd. no. 680-710 pH 6-8 (2%) 0.5% moisture... 

Chem. Descrip. Unsat. polyester resin (68%) in styrene Uses Flexibilizer for unsat. polyester coatings cured by conventional methods or UV radiation, with and without paraffin wax Features Improves polishability of wax-free coatings and scratch resist. 

Chem. Descrip. Etherified acrylated melamine/formaldehyde resin (62-68%) in tripropylene glycol diacrylate Uses Crosslinking agent in radiation-cure applies, such as polyester and epoxy acrylates, unsat. polyesters, aliphatic and aromatic urethane acrylates, and most acrylate monomer diluents imparts hardness and gloss, stain and chem. resist, to coatings, paper coatings Features Cured by free radical polymerization initiated by U V or thermal processing... 

Uses Crosslinking agent in adhesives, coatings, inks, textile prods., photoresists, castings, modifiers for polyester, fiberglass, or polymers reactive diluent for radiation-cured inks, lacquers, photosensitive resins Manuf/Distrib. Aldrich CarboMer Fluka Monomer-Polymer Dajac Labs ... 

Uses Flow aid. leveling agent, abrasion resist, aid for radiation-curable monomers, urethane and polyester resins, high-solids coatings, polyester resin synthesis reactive modifier for UV cationic cure systems Trade Names Photonol PHO-7149... 

Solvents can be replaced with reactive diluents like some monomers, as is the practice with unsaturated polyesters and with radiation-curing polymers. Polyfunctional monomers like unsaturated melamine resins are becoming used as diluents for alkyd resins [61]. 

PSA adhesives A significant use for radiation curing is the advancement or curing of pressure-sensitive adhesives. High solid EB and UV curing liquid adhesives are being formulated from a variety of resins and elastomers. Such adhesive compositions include acrylics, blends of acrylic monomers with elastomers, polyesters and other compositions. These products are primarily used as pressure-sensitive adhesives. 

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