What is the problem of the selection of functional monomers prepared from styrene-acrylic emulsions?

Update:19-10-2018
Summary:

The comonomers of the emulsion polymer are selected in […]

The comonomers of the emulsion polymer are selected in three types: hard monomer (to impart hardness, abrasion resistance and structural strength to the coating film), soft monomer (to impart flexibility and durability to the coating film), and functional monomers (can be attached) Focus, wettability, emulsion stability, cross-linking).
The conventional styrene-acrylic emulsion is mainly composed of styrene, butyl acrylate and a small amount of acrylic acid. The styrene-acrylic emulsion obtained by polymerizing only three kinds of monomers has many problems, such as poor film forming property, high minimum film forming temperature, low coating strength, water resistance of the coating, erosion resistance, and poor light resistance. In order to impart more excellent properties to the styrene-acrylic emulsion, a small amount of functional monomer may be introduced by blending or copolymerization to effect modification of the styrene-acrylic emulsion.

Functional acrylate monomers are classified into monomers and oligomers. Monomers include monofunctional monomers, difunctional monomers, and polyfunctional monomers such as (meth)acrylic polyol esters, dimethylaminoethyl methacrylate, glycidyl acrylate, and the like. The oligomer refers to an oligomer formed by chemical reaction of two or more monomers having different functional groups, such as urethane acrylate, epoxy acrylate, acrylic polyester, and the like. The functional monomer acts as a comonomer and is incorporated into the polymer emulsion to impart a variety of properties to the polymer emulsion. The functional monomer is mainly an acrylate having a functional group such as a carboxyl group, a hydroxyl group, an epoxy group, and an amino group.

The presence of a hydroxyl group improves the overall performance of the crosslinked emulsion coating film. Therefore, in the formulation, the hydroxyl group-containing monomer is often combined with the carboxyl group-containing monomer to achieve optimum film properties.

A functional monomer having an amine group, NCH 2 OH, and an epoxy group can be copolymerized with an acrylic monomer, and a functional group thereof can be stabilized in a radical emulsion polymerization. N-methylol acrylamide cross-linking under heating and acid catalysis, can be used to prepare cross-linked polymer emulsion by propionic acid ester copolymerization; application of DMAEMA and acrylate emulsion Copolymerization can produce a cationic acrylic polymer emulsion; a glycidyl methacrylate (GMA) copolymerized with an acrylate emulsion can produce a reactive polymer emulsion, and the macromolecular chain of the latex particle contains an epoxy group in an amine catalytic heating condition. The crosslinking reaction can be carried out with a polymer having a carboxyl group.