Radiation-curable polyester coating

Radiation-Curable Polyester Coatings. Radiation-curable polyester paints (see also Section 3.7) are particularly suitable for coating flat surfaces (strips, boards, sheets) and for temperature-sensitive substrates (paper, plastics). Acrylate-modified polyester resins are used for UV printing inks, UV varnishes for paper and plastics, as well as for pigmentable, electron beam-curable gloss and matt paints [2.86]. Radiation-curable polyester paints are also suitable for metal coatings with good elasticity. 

Polyester resins for waterborne paints mostly contain anionic groups (e.g., carboxyl groups) and become water soluble after amine neutralization. Waterborne paints based on polyesters also contain cosolvents, preferably glycol ethers. Powder coatings based on low molecular mass resins are solvent-free, like radiation-curable polyester paints. 

Polymers. The molecular weights of polymers used in high energy electron radiation-curable coating systems are ca 1,000—25,000 and the polymers usually contain acryUc, methacrylic, or fumaric vinyl unsaturation along or attached to the polymer backbone (4,48). Aromatic or aUphatic diisocyanates react with glycols or alcohol-terrninated polyether or polyester to form either isocyanate or hydroxyl functional polyurethane intermediates. The isocyanate functional polyurethane intermediates react with hydroxyl functional polyurethane and with acryUc or methacrylic acids to form reactive p olyurethanes. 

Solid urethane and polyester acrylates may be used as main components of radiation curable powders. Together with suitable unsaturated polyesters, powders are formed, which give low-film-flow temperatures and allow separating of film formation from curing. This technology has been used successfully in powder coating of wood and plastics. ... 

Most of the radiation curable raw material technology is based on acrylic or methacrylic acid deritive but may also include modified epoxies, polyesters, and polyurethanes. Thus the backbones of radiation curing and conventional coatings are similar. 

Most radiation-curable monomers contain single unsaturation sites and are high-boiling acrylic esters, although in the wood area some coatings use styrene as the monomer. Usually, where styrene is used, most or all of the polymer-polyester unsaturation is furaarate rather than acrylic. 

Acrylate-modified polyester resins have proved suitable as binders for radiation-curable coatings [2.86]. 

Chem. Descrip. Bis (1-2,2,6,6-pentamethyl4-piperidinyl) sebacate and methyl (1,2,2,6,6-pentamethyl-4-piperidir ) sebacate Uses Lt. stabilizer for exterior paints/coatings, automotive coatings, industrial coatings, wood stains, thermoplastics, acrylics, alkyds, polyes-ter/melamine, thermosetting acrylics, waterborne acrylics, phenolics, vinylics, radiation-curable acrylics, PU, PP, PE, styrenics, unsat. polyester... 

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... 

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... 

A large variety of addition copolymers and terpolymers, prepared from hydroxyalkyl acrylates and/or methacrylates have been treated with MA to prepare polymers with pendent maleate residues.An addition polymer prepared from ethyl acrylate-hydroxypropyl methacrylate-styrene was treated sequentially with MA and propylene oxide.Blends of these polymers with vinyl monomers were cured with peroxides to obtain films with physical properties better than regular cured unsaturated polyesters. In another example, a styrene-butyl acrylate-hydroxyethyl methacrylate terpoly-mer was treated with MA to obtain a molding resin.When blended with styrene and cured with peroxides, the molding exhibited low shrink (less than 5%) and Rockwell hardness (M scale) 55. The same chemistry and technology have been explored for preparing radiation-curable coatings. " ... 

---