Coating systems, acrylic-melamine resin

Uses Crosslinking agent in melamine resin coating systems, general industrial finishes, coil-coating enamels, appliance finishes, useful with alkyd, polyester, thermosetting acrylic, epoxy, and cellulose resins Properties Gardner 2 max. clear, vise, liq. limited water-sol. dens. 10.0 Ib/gal vise. (G-H) X-Z2 flash pt. > 180 F 98% NV Cymel 350 [Cytecind.j... 

Coatings containing P.Y.151 are very lightfast and durable. Systems based on acrylic melamine resin, for instance, were exposed to the Florida climate for one year and then evaluated. 1 1 reductions with TiOz equalled step 5 on the Gray Scale for weatherfastness, while 1 3 Ti02 reductions matched step 4, and 1 35 reduced samples coincided with step 3-4. Comparative values for P.Y.154 and 175 are listed for the respective pigments. P.Y.151 is fast to overcoating up to 160°C. 

Tsuge et al. [986] have reported DHS-GC-FID (wide-bore capillary column) in the study of paint coatings (acrylic/melamine resin/(LS-440 or LS-292 (HALS), Tinuvin 1130 or Tinuvin 900, surface modifier, organic solvent)). DHS-GC provides a sensitive technique for quantification of HALS and UVA occluded in cured polymeric materials such as coating paints. The optimum thermal desorption temperature was decided empirically. The system permitted fairly accurate determination of HALS (LS-440 and LS-292), which were almost quantitatively recovered, within an analysis time of 1.5 h. Reproducibility for Tinuvin 900 was less satisfactory, whereas Tinuvin 1130 was not observed because of its extremely low volatility. 

Branched acrylic polymers based upon the copolymerization of acrylates and related monomers with methacrylate macromonomers are particularly useful in waterborne coatings. A macromonomer based upon isobutyl methacrylate, 2-ethylhexyl methacrylate, and 2-hydroxyethyl methacrylate was copolymerized with butyl acrylate, 2-hydroxyethyl acrylate, meth-acrylic acid, methyl methacrylate, and styrene.518 After neutralization with dimethylethanolamine or inorganic bases, the polymer could be cross-linked with melamine resin on a metal surface. These systems may be used for either pigmented layers or clear coats. 

The acrylic resin used was Rohm and Haas Co.s QR-496 ( 4), so the exact nature of the polymer is not known. It is hydroxy functional, thus requiring an aminoplast for proper cure commercially modified hexa-methylol melamine resin was used for this purpose. During the first part of the investigation the acrylic resin was used without the melamine resin, but for final evaluation it was incorporated to give a more realistic commercial coating system. 

Side and cross members are pretreated by blasting and phosphating. An electrode-posited primer coating follows and is sometimes immediately overcoated with a topcoat based on an air-drying alkyd or epoxy ester, or on an oven-drying alkyd-melamine resin combination. After assembly of the truck, a third layer (i.e., a second topcoat) is applied that serves as a supply finish. These finishes are mostly two-pack acrylic aliphatic isocyanate topcoats. Water-based two-pack systems and powder coatings are the most recent developments. 

Anionic coatings systems for water-borne topcoats are emulsion polymers, miniemulsion polymers, polyurethane dispersions, different types of dispersions of acrylic resins in water and amino resins, water-borne polyesters, polyurethanes. Many of the polymers are hydroxyl containing and cured with various melamines and blocked isocyanates. The polymers are mainly stabilized in the water phase by neutralization of anionic groups with volatile amines (2-amino-2-methyl-l-propanol). Cross-linkers like aminoplast resins, alkoxy silanes, blocked epoxy resins, carbodi-imides can be used. 

Additives and comonomers in thermoset, moisture, UV, and catalytically curing resins or coatings (e.g., acrylic, epoxy, melamine, and unsaturated polyester systems)... 

Chert). Descrip. Butoxymethyl methylol melamine (60%) in n-butanol Uses Crosslinking agent for alkyd/polyester or acrylic resins, for use in solv.-borne systems, industrial stoving finishes, automotive finishes, metal decorating and dipping enamels, polymeric/resinous food-contact coatings... 

Conversion. The cure of many oxidative thermosetting coatings is accelerated by heating. In other resin systems, such as thermosetting acrylics and alkyd melamines, the reactions do not occur below tern-... 

These thermoplastic resins are obtained by the polymerization or copolymerization of acrylic and methacrylic esters. Acrylic resins may be combined with melamine, epoxy, alkyd, acrylamide, etc., to produce systems that bake to a film with excellent resistance to water, acids, alkalies, chemicals, and other corrosives. Acrylic resins are used in coatings for all types of appliances, cans, and automotive parts and for all types of metals. 

Chem. Descrip. Polysiloxane sol n. in 2,6-dimethyl4-heptanone Uses Defoamer for org. systems incl. chlorinated rubber, epoxy, two-part polyurethane, alkyd, alkyd/melamine, self-crosslinking acrylates, polyesters used in resinous and polymeric coatings in food pkg. 

A wide variety of other specialty monomers are also used to provide specialized performance properties for coating applications. For example, amine functional monomers can be used to improve adhesion to aged alkyd substrates. Specialized monomers can also be used to improve exterior durability, for example VEOVA (vinyl ester of vesatic acid) monomers can improve the hydrolysis resistance of vinyl acetate polymers, and n-butyl methacrylate can be used to enhance the durabiHty of BA-MMA acrylics. Polymer hydrophobicity can be fine tuned by varying the levels of hydrophobic and hydrophilic monomers in the composition and styrene or ethyl hexyl acrylate are used to increase film hydrophobicity and reduce water permeability in BA-MMA systems. Specialty monomers are also used to provide specific chemical functionality to polymer compositions. For example, hydroxyethyl methacrylate can be used to provide hydroxyl functionality to acrylic resins, allowing these polymers to be used in cross-linkable thermoset coatings which cure via melamine chemistry. While specialty monomers are used at relatively low levels in polymer compositions, they frequently provide the performance features needed for the successful application of emulsion polymers in many coating areas. 

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