Hardness acrylic polyols

The resulting performances of acrylic polyol based PU coatings depend profoundly on the chemical nature of the monomers used. Thus, methylmethacrylate (MMA) confers exterior durability, excellent light stability, hardness and water resistance. Styrene confers hardness, water stability but, unfortunately, poor light stability. Butyl and 2-ethylhexyl acrylates and methacrylates confer flexibility and acrylic and methacrylic acids confer adhesion to metals and solvent/grease resistance. 

Figure 10.2 A representative structure of an acrylic polyol for hard PU coatings (with a...

The MW of the acrylic polyol (Figure 10.2) is around 13000 daltons and the glass transition temperature (T ) is around 50 °C. The high content of methylmethacrylate confers hardness to the resulting PU coating. 

Chem. Descrip. Hexafunctional aliphatic urethane acrylate containing acrylated polyol diluent Uses Urethane-acrylic in coatings and inks Features Exceptional cure speed and scratch/abrasion resist, in combination with nonyellowing props. fast cure with exc. hardness, solv. resist. 

A generic urethane acrylate is shown in Figure 1. It is formed by the reaction of a diisocyanate with a polyol and a hydroxy alkyl acrylate. Two types of substructures are found in urethanes, hard and soft segments. The hard segment is derived from the dllsocyanate and urethane linkages. The soft segment Imparts... 

Uses Acrylic resin for powd. coatings polyol for PU coatings Features Hyd. functional exc. exterior durability/hardness and fair mechanical props. very fast dry with long pot life and exc. UV and chem. resist. 

The oligomeric polyol may be a low MW flexible polyester or a polyether (pp. 228-9). Urethane acrylates can possess a range of properties dependent on the contributions of the softer polyol centre block and the outer urethane hard segments. 

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