Brief Introduction to Waterborne Acrylic Resin
Compared with traditional solvent based coatings, water-based coatings have the advantages of low price, safe use, saving resources and energy, reducing environmental pollution and public hazards, and have become the main direction of the current development of the coating industry. Waterborne acrylic resin coatings are the fastest developing and most versatile pollution-free coatings among waterborne coatings.
Waterborne acrylic resin includes acrylic resin lotion, acrylic resin aqueous dispersion (also called water dilutable acrylic acid) and acrylic resin aqueous solution. The lotion is mainly synthesized by emulsification of oily olefin monomer in water initiated by water-based free radical initiator, while the aqueous dispersion of resin is synthesized by different processes such as free radical solution polymerization or gradual solution polymerization. From the particle size: lotion particle size> Resin aqueous dispersion particle size> The particle size of the aqueous solution. From the perspective of application, the former two are the most important.
Acrylic lotion is mainly used as the base material of latex paint, and has an important application in the building paint market. At present, its application is still expanding; In recent years, the development and application of acrylic resin aqueous dispersions have attracted increasing attention, and their applications in the fields of industrial coatings and civil coatings have been expanding. According to monomer composition, it is generally divided into pure acrylic lotion, styrene acrylic lotion, acetate acrylic lotion, silicone acrylic lotion, tert acetate (tert carbonate vinyl acetate) lotion, tert acrylate (tert carbonate acrylate) lotion, etc.
Acrylic waterborne paints can be divided into two categories: water dispersible paints and water soluble paints, the former being based on water emulsion or water sol. Water-soluble acrylate coatings are made of copolymerized resins with active cross-linkable functional groups. They are mostly thermosetting coatings, and are coated with or without cross-linking resin to cross-link the active functional groups during film formation to form a structured paint film. The development of waterborne acrylate coatings can greatly reduce atmospheric pollution by replacing most organic volatile solvents with water while ensuring various unique properties of acrylate coatings.
Water-soluble acrylic resins are mostly anionic, and the monomers of copolymerized resins use an appropriate amount of unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, maleic anhydride, and methylene succinic acid, to carry carboxylic groups on the side chains, and then neutralize with organic amines or ammonia to form a salt to obtain water solubility. In addition, the water solubility of the resin can be increased by selecting appropriate monomers to introduce hydrophilic groups such as - OH hydroxyl, - CONH2 amido, or - O ether bonds on the resin side chain. Acrylic resins that neutralize and form salts can be soluble in water, but their water solubility is not very strong, often forming milky liquids or highly viscous solutions. Therefore, a certain proportion of hydrophilic cosolvents must be added to the water-soluble resin to increase the water solubility of the resin.