Study on Elimination of Residual Monomer in Acrylic Resin by Solution Polymerization

Acrylic resin is widely used in coatings, inks, and adhesives because of its wide application. As a product form, it can be solvent-based, water-based, powder-based, and radiation-curable. Different types and quantities of monomers can be used to obtain different properties. And acrylics for different uses. In the polymerization of acrylic resins, bulk, solution, suspension, and emulsion methods are used. Each method has advantages and disadvantages. Among them, solution polymerization occupies an important position in the synthesis of acrylic resins, due to the inclusion of solvents. Can be directly used in some coatings, inks, adhesives, more convenient, coupled with the solution polymerization is more stable, the production is more convenient, but due to the late viscosity of the solution polymerization polymerization, leading to monomer conversion rate is not high, the product has a single The body odor, which also greatly limits its application in certain areas, for example, in ink applications. Here are some discussions on how to reduce the residual monomer content.

1. Chemical elimination method

1.1 increase the monomer conversion rate General practice is to extend the polymerization time, add initiator, increase the temperature of the reaction later, add solvent to reduce the viscosity of the system, increase the chance of free radical collisions.

1.2 Conversion of Residual Monomers The use of unsaturated double bond reaction properties of certain substances with acrylic esters to convert residual monomers into other low-odor substances and eliminate odors, for example, butyl acrylate can be greatly reduced by the addition of ethanolamine. Smell.

1. 3 adjustment of polymerization process method Under the premise of not affecting the performance and cost, we can increase the conversion rate of comonomer by choosing the monomer group with the same reactivity ratio. For example, the copolymer of butyl acrylate and methyl methacrylate The odor is much less than that of butyl acrylate and styrene. Different activity initiators are used for compounding, and less active monomers can be fed first.

2, physical law

2. 1 Distillation method Vacuum distillation, distilling off the reaction carrier solvent and entraining residual monomers, this method is effective, but due to a large number of solvent evaporation, the resin will withstand the temperature is too high, in the later period may make the resin become paste and Smelly.

2.2 Boiling method Residual monomer is carried away by adding hot inert gas such as N2.

2.3 Precipitation Elution The resin is precipitated by the addition of precipitants, such as low alcohols, water, and then washed to remove residual monomers.

Source: China Tobacco Packaging Ink Information Network