Problems to be considered in the formulation of water-based acrylic emulsion: the composition of water-based acrylic resin!

Problems to be considered in the formulation of water-based acrylic emulsion: composition of water-based acrylic resin

The choice of emulsion raw materials is an important decision for engineers when formulating water-based paints. The main properties of coatings are determined by resins. There are many kinds of water-based acrylate emulsions, including polystyrene-acrylate emulsions, which are mixed in the market. The composition of different water-based acrylate resins has a great influence on the film-forming property and cost of water-based paints. Here is a brief discussion of several influencing factors.

1. Main raw materials:
a. Styrene: The main reason for the introduction of this monomer into the polyacrylate emulsion is that it can provide a higher glass transition temperature (Tg), thereby increasing the hardness of the film; another reason is cost. Styrene is used in a large amount in the packaging industry and is one of the most important and mature downstream products in the petroleum industry. The price is low but it is greatly affected by the macro economy. However, the introduction of styrene, especially when its content is more than 15% of the total monomer content, also brings many negative effects on the film-forming properties of water-based paints. First of all, the polymer segment containing styrene lacks flexibility, and macroscopically, the water-based paint film is hard and not tough; there is also the benzene ring contained in styrene, which is an absorber of ultraviolet light. When the monomer content is high , ultraviolet rays will shear the polymer chain through the adjacent benzene ring, so that the water-based paint film becomes brittle, the gloss is reduced, and the lifespan is reduced; the structure of styrene also determines its affinity for many organic solvents, water-based paint The solvent resistance of the paint film is also significantly different from other resins.
 
b. Acrylate monomers: There are many types of acrylate monomers, and the performance and price vary greatly. Butyl acrylate is commonly used in China, and the cost of changing the monomer is low. It is the monomer used by most emulsion manufacturers to match with styrene to manufacture the emulsion of cheap wall paint. Its function is to provide the flexibility of the water-based paint film. Since the main chain of the acrylate polymer does not contain groups other than the ester group, the main chain and the side chain of the ester group have good flexibility, which makes the water-based paint film lack hardness. Although this type of polyacrylate emulsion is the choice for interior and exterior wall coatings of buildings, its performance is not enough as a wood paint that requires high hardness and toughness.
 
c. Methacrylate monomers: Methacrylate monomers have a higher performance than acrylate monomers. Due to the addition of methyl groups on the main chain of methacrylate polymers, the mobility of the main chain is limited, the rigidity of the main chain is enhanced, and the side chain of the ester group provides flexibility, making the methacrylate polymer monolithic. The body has a better balance of hardness and toughness. For example, polymethyl methacrylate (methyl methyl) is commonly known as plexiglass; methacrylate monomers, because they do not contain benzene rings, make them better than styrene Monomers have obvious advantages over styrene in terms of UV resistance, durability, and solvent resistance.
 
In summary, waterborne acrylate resin manufacturers have many choices of monomers, which can not only change their types, but also change the relative proportions and components. When choosing water-based acrylate emulsions, water-based paint manufacturers should not only consider empty concepts such as "pure acrylic" or "styrene-acrylic", but should take the actual performance of water-based acrylic resins and their formulations as the standard.