Common crosslinking agents for water-based acrylic resins

Acrylic resin has the advantages of light color, color retention, weather resistance, corrosion resistance, and pollution resistance, and is widely used in furniture, buildings, leather products, daily necessities, paper printing and dyeing, wood processing, plastic synthesis, and other fields. Its main types are: (1) solvent based; (2) Water based, mainly including water-soluble, water emulsion type, water sol type, and water thick slurry type; (3) High solid and powder types.

Compared with organic solvent based resins, water-based resins have the characteristics of low price, safe use, energy saving, reduced environmental pollution and public hazards. However, in order to obtain a stable dispersion system, hydrophilic groups (such as carboxyl, hydroxyl, and amino groups) are often introduced into water-based resins, resulting in poor gloss, water resistance, solvent resistance, and pollution resistance of the coating film. The mechanical properties such as hardness and tensile strength cannot be compared to solvent based resins. 

Reducing the content of hydrophilic groups can reduce their negative impact on the coating, but the comprehensive performance of the resulting coating cannot meet the requirements for use. By using crosslinking agents to crosslink and modify water-based resins, a network structure can be formed after curing, which can increase molecular weight, block hydrophilic groups, greatly improve water and solvent resistance, and reduce the sensitivity of the coating to temperature, solving the problem of hot adhesion and cold brittleness of acrylic resin coatings. 

The common hydrophilic groups in water-based resins include carboxyl, hydroxyl, amino, and aldehyde groups. Among them, the carboxyl group can cross link with a variety of functional groups to obtain a three-dimensional network structure. Moreover, the presence of carboxyl monomer can also improve the adhesion of the coating film to the metal substrate, and make it easier to control the viscosity of lotion. Therefore, it is a functional group commonly used in the development of diplomatic lotion.