Acrylic coating polymers composition

History of the Synthesis of Acrylic Monomers and Polymers Relation between the Properties and Composition of Acrylic Coating Polymers General... 

Relation Between the Properties and Composition of Acrylic Coating Polymers... 

General. The solution and film properties of an acrylic coatings polymer are determined by (1) the molecular weight, (2) the nature of the polymer solution, and (3) the composition of the polymer backbone. 

Acrylic paints have compositions similar to water-based house paints. Since they are synthetic, manufactures can design paints that fulfill specific requirements and that are the same from tube to tube. Because water is the main vehicle such paints are largely odorless. They are not completely odorless because while the overwhelming majority of the vehicle is water, there are often minute amounts, generally 1%-10%, of organic liquid added to help the particles of polymer remain sufficiently flexible so that they will lay down a thin smooth coating. 

The understanding of the relation between the macroscopic film properties of an acrylic coating and the polymer composition has been advanced significantly by the successful application and interpretation of two physical models (1) the glass transition temperature, Tg (2) the solubility parameter, 6. 

Apparently, pre-irradiating polyethylene containing a HALS with a low pressure Hg lamp imparts some surface stabilization toward sunlight exposure. Anthracene-HAS stabilizer molecules are found to be more effective stabilizers than the separate molecular moieties, while the nature of the polymer composition affects the distribution of nitroxyl radicals in stabilized materials. " Polyethylene with terminal HAS groups has been found to be very light stable, as were reactive acrylic coatings with acrylated HAS systems. A new epoxide amine based HAS has been found to be quite effective in... 

The direct and indirect effects of fillers oti the photostability of polymer compositions are well known. With the recent interest in nanopowdered fillers reports of their effectiveness as photostabilizers is beginning to be reported in the literature. For instance ZnO and Ti02 nanoparticles (primary particle size 25-70 nm) were studied in acrylic coatings. A layer that carried at least 5 weight percent of the nanoparticles was needed to shield the underlying layers from UV exposure and hence degradation [162]. Nanoscale titania was also evaluated as a stabilizer in epoxy coatings [163]. 

Plummer [120] provided an excellent review in his reflections on the use of microtomy for materials science specimen preparation, with a table of material classes, references, and comments. The review includes examples of polymer composites, blends, membranes, elastomers, and coatings. Kink bands and shear deformation were shown in polybenzobisoxazole (PBO) fibers microtomed and studied by TEM [121]. Fibers treated to cause compressive deformation were taped to sheet polycarbonate and coated with spray acrylic to fix them to the substrate. Small sections (<5mm) attached to the polycarbonate were cut, trimmed, and microtomed to a thickness of 40-80nm with a new area of a diamond knife and picked up on 400 mesh grids. Ericson and Lindberg [122] showed that when the sample holder of the... 

Top coats are of a similar composition to base coats but are not pigmented. Again these are usually two-component systems that comprise an acrylic comb polymer and a poly(isocyanate) hardener, which cross-links after application if a catalyst is used or cross-links under heating curing forming a clear, hard, chip-resistant coating. Maaomonomers synthesized by CCTP are again used in the formation of acrylic comb polymers. 

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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