Background of the invention of pressure sensitive adhesive for viscosifying emulsion

The emulsion pressure sensitive adhesive in this paper, when this adhesive is combined with the applicable viscosifier, it has good convertibility and good low temperature performance when the amount of glue is lower than that of the conventional system used for general labels.

Usually, pressure sensitive adhesives are prepared by solvent polymer, bulk polymer and emulsion polymer. Some polymers are pressure-sensitive adhesives because of their properties, that is, their intrinsic adhesion, while others require viscosification in order to achieve adhesion. My earlier patents, US Patent 5164444 and US Patent 5189126(both of which have been included herein for information), describe emulsion pressure-sensitive adhesive polymers with excellent properties and good convertibility at room and low temperatures.

It is well known that in order to improve the adhesion with non-polar substrates such as polyolefin, acrylic based pressure sensitive adhesives can be increased. However, most available viscosifiers have low molecular weights compared to adhesive polymers, and their addition to polymers reduces the shear properties and conversion properties of adhesives. The adhesion of this adhesive to other substrates (such as recycled corrugated cardboard) is often poor.

In addition, the viscosification of pressure-sensitive adhesives can usually improve the performance of room temperature, but can not improve the performance of low temperature, and in most cases the performance of viscosifying adhesives is worse than that of non-viscosifying pressure-sensitive adhesives. Thus, operational characteristics appear to be largely determined by the choice of viscosifiers, their functional groups and their concentrations.

Kealy et al., US Patent 4418120, discloses a crosslinked acrylic adhesive with high adhesion to a low-energy substrate. The adhesive is composed primarily of isooctyl acrylate and a solution polymer containing 3-7%(by weight) acrylic acid. It was prepared by mixing 100 parts of solution polymer with 20-50 parts of viscosifying rosin esters whose acid value was lower than 20. The adhesive also contains antioxidants and crosslinking agents, which are dried at 70℃ after coating and crosslinked. In order to achieve the specified performance, the composition is required to contain no surfactant.