In the formulation of water-based paint, the choice of emulsion raw material is the most important decision for the engineer. The main properties of the paint are determined by the resin. There are a wide variety of water-based acrylate emulsions, including polystyrene-acrylate emulsions, which are mixed in the market. The different composition of water-based acrylate resin has great influence on the film-forming property and cost of water-based paint. A few influencing factors are briefly discussed here

Principal raw material

A. Styrene: The main reason for the introduction of this monomer in polyacrylate emulsion is that it can provide a higher glass transition temperature (Tg), thereby increasing the hardness of film formation; Another reason is cost. Styrene is used greatly in the packaging industry and is one of the most important and mature downstream products in the petroleum industry, with low prices but large macroeconomic impacts. However, the introduction of styrene, especially when its content is higher than 15% of the total monomer content, will also bring many negative effects on the film formation of water-based paint. First of all, the polymer chain segment containing styrene lacks flexibility, and the water-based paint film is hard but not tough at the macro level. There is also the benzene ring contained in styrene, which is the absorber of ultraviolet light. When the monomer content is high, the ultraviolet light will shear the polymer chain through the adjacent benzene ring, which makes the water-based paint film brittle, the gloss decreases, and the life decreases. The structure of styrene also determines that it has affinity for many organic solvents, and the solvent resistance of water-based paint film is also significantly different from that of other resins.

B. Acrylate monomers: There are many types of acrylate monomers, and their performance and price vary greatly. The most commonly used is butyl acrylate, which has the lowest cost of monomer, and is the monomer of emulsion used by most emulsion manufacturers to manufacture cheap wall paint with styrene. Its function is to provide the flexibility of water-based paint film. Because there is no group except ester group on the main chain of acrylate polymerization, the flexibility of the main chain and the ester group side chain is good, so that the water-based paint film lacks hardness. Although this kind of polyacrylate emulsion is the choice of building interior and exterior paint, it is not enough as a wood paint with high hardness and toughness requirements.

C. Methacrylate monomer: methacrylate monomer, compared with acrylic monomer in the performance of a further step. Because there are more methyl groups on the main chain of methacrylate polymerization, the activity of the main chain is limited, the steel of the main chain is enhanced, and the ester side chain provides flexibility, making the methacrylate monomer have the best balance of hardness and toughness, such as polymethyl methacrylate (methyl methyl ester) is commonly known as plexiglass; Methacrylate monomers, because they do not contain benzene rings, make them have obvious advantages over styrene monomers in UV resistance, durability, and solvent resistance. In summary, water-based acrylic resin manufacturers have a lot of choices for monomers, which can not only change their types, but also change the relative proportion and composition. Water-based coating manufacturers in the selection of water-based acrylic emulsion, can not only consider the "pure C" or "propylene" these empty concept words, should be measured by the practical performance of water-based acrylic resin and its formulation.

The phase structure of emulsion particles and the internal structure of film-forming agent water-based acrylic emulsion particles will affect several aspects of water-based paint formulation. According to the order of effect occurrence, the phase structure will first affect the selection and addition method of film forming additives. Different phases have different hydrophilic/lipophilic characteristics, and the lipophilicity of various film forming additives is also different, such as dipropylene glycol methyl ether (DPM) than dipropylene glycol butyl ether (DPnB), the hydrophilicity is higher, and the lipophilicity is lower. If the outer layer of water-based acrylic emulsion particles is a strong lipophilic phase, then the addition of DPM not only has no obvious effect on film formation, but also makes excess DPM free in water to affect other properties of water-based paint film.

Another effect of phase structure on the formulation of water-based paint is the effect on the film forming quality of water-based paint film. The key of film forming quality is to make the phases that need to be mixed fully mixed and the phases that need to be separated remain separated during the fusion process of water-based acrylic emulsion particles. If different phases need to participate in fusion, a mixed film-forming agent should be selected to achieve the best results. Many literatures on aqueous acrylic emulsion polymerization at home and abroad have mostly mentioned the structural problems of emulsion particles such as core-shell. For example, structures such as core-shell, semilunar, multicore, hollow, and strawberry have been reported. Although these structural descriptions are helpful in understanding the complexity of the particle structure of water-based acrylic emulsions, in reality the structure of water-based acrylic emulsions is much more complex. For example, only a single phase structure of the particles of the emulsion does not exist, the particles in the practical water-based acrylic emulsion is the distribution of various structures, may be more core shell, may be more strawberries, and so on. Aqueous acrylic emulsion manufacturers control the phase structure of aqueous acrylic emulsion through the selection of monomers, the order of addition, the use of surfactants and other technological conditions.

Since the phase structure of water-based acrylic emulsions is a technical secret of the emulsion manufacturer, this information is usually not disclosed. However, the supplier will provide the recommended additives and ratios for the water-based acrylic emulsion. This is why different water-based acrylic emulsions usually require different combinations of additives.

Sinograce Chemical production of different water-based resin and water-based acrylic emulsion, welcome to consult.