Water resistant adhesive and methods of use
View Patent ↗The invention provides the art with an adhesive that may advantageously be used in the manufacture of water resistant paperboard products, such as laminated board and corrugated board. The adhesive has the required tack, water resistance and viscosity that allows its use at commercial speeds in a cold corrugating process.
1. The paperboard product prepared by a process comprising:
applying a thin layer of a synthetic waterborne adhesive to a first substrate, and
bringing a second substrate together with said first substrate such that said adhesive layer is located between said first substrate and said second substrate and wherein the substrates consist of at least one corrugated medium and at least one liner board, whereby the corrugated medium becomes bonded to the liner board; and
wherein said adhesive comprises from about 25 to about 35 wt % of a polyvinyl alcohol and surfactant stabilized ethylene vinyl acetate resin emulsion, from about 22 to about 28 wt % of a polyvinyl alcohol and surfactant stabilized carboxy functional ethylene vinyl acetate resin emulsion, from about 3 to about 7 wt % of a polyvinyl alcohol and surfactant stabilized N-methylol acrylamide containing ethylene vinyl acetate resin emulsion, up to about 5 wt % of a plasticizer, and containing from about 35 to about 45 wt % water, and
said adhesive has a solids content of greater than 40%, has a Brookfield viscosity (20 rpm, 72° F.) greater than 700 cps, is applied to a substrate at a coat weight of less than 0.004 inch and has a 2 second tack at 72° F., 50% Relative Humidity, of at least 50 gram force per linear inch flute length at an application level of 1.5 dry lbs/msf or less.
2. The paperboard product of claim 1 wherein the adhesive further comprises a preservative and/or a defoamer.
3. The paperboard product of claim 1 which is a corrugated board comprising at least two liner boards and at least one corrugated medium.