Acrylic pressure sensitive adhesive

Acrylic pressure sensitive adhesive

Acrylic polymer-like compositions have long been used as adhesive compositions, particularly in pressure-sensitive adhesive (” PSA “) compositions. They exhibit adhesion to a wide variety of surfaces, display good low-temperature properties, often produce attractive transparent adhesives, and possess excellent thermal, aging, and UV stability. Acrylic binder polymers can be obtained as organic (solvent) solutions, aqueous emulsions, and 100% solid thermoplastic systems applied as melts. Initially, the most common PSA is solvent acrylic, but market demand leads to the rapid growth of water-based acrylic, also known as emulsion acrylic adhesives. Traditionally, acrylic PSA compositions are characterized by the selection of acrylic monomers and polymerization conditions. Examples of such properties are cohesion (such as shear strength) and adhesion (such as adhesion and peel strength).

For example, acrylate monomers that reduce the glass transition temperature of acrylic polymers (e.g., butyl acrylate and 2-ethylhexyl acrylate) improve adhesion properties, while acrylate monomers and vinyl monomers that raise the glass transition temperature of acrylic polymers improve cohesion properties (e.g., methyl methacrylate, styrene, and vinyl acetate). Unfortunately, more use of one monomer leads to less of the other, so cohesion and adhesion are often inversely correlated, so an improvement in one property causes a decline in the other.

Usually, we use pure monomer synthesis emulsion acrylic PSA. Acrylate monomers that give adhesion properties usually include straight carbon chains (e.g., butyl acrylate) or single-branched carbon chains (e.g., (methyl) acrylate monomers of 2-ethylhexyl acrylate and C12-C322-alkyl alkanols). However, it is also possible to use mixtures of (methyl) acrylate alkyl monomers with carbon chains (or carbon numbers) of varying lengths and different branched carbon chains including two or more branches. Unconstrained by theory, it is believed that the diversification of carbon chain length and increased branching improves the cohesive properties of acrylic Psas (including, for example, more than a five-fold improvement in shear strength) while maintaining the adhesive properties of acrylic Psas.