Fluid activatable adhesives for glue-free, liner-free labels for glass and plastic substrates and methods of use thereof
View Patent ↗Methods for applying a liner-free, or liner-less label, to a substrate, particularly glass or plastic (e.g., PET) substrates are described herein. The method includes applying an adhesive composition, such as a polymeric coating, to a label face sheet, activating the adhesive composition with an activating fluid, and contacting the label to the substrate. The activating fluid is preferably a mixture of water and one or more organic solvents, such as low molecular weight alcohols. In some embodiments, the labels exhibit a percent fiber tear greater than about 50, 55, 60, 65, 70, 75, 80, 85, 90, or 95% after one, two, three, four, or five minutes. In particular embodiments, the labels exhibits a percent fiber tear greater than 60, 65, 70, 75, 80, 85, 90, or 95% after two minutes.
1. A label comprising a face sheet and an adhesive coating in the form of a dry film, wherein the dry film is non-blocking and non-tacky,
wherein the adhesive coating is obtained from a fluid activatable adhesive composition, wherein the composition comprises one or more polymers that are soluble in a volatile-base neutralized aqueous solution, wherein the one or more polymers are insoluble in water at neutral pH and soluble in water at alkaline pH, wherein the one or more polymers have a glass transition temperature from about −15° C. to about −45° C.,
wherein the face sheet has a moisture vapor transmission rate (MVTR) of at least 160 g/m 2 /24 hr, wherein the face sheet exhibits no label drop-off after 72 hours immersed in ice water, and
wherein when the dry film is activated by an activating fluid comprising water and one or more organic solvents, the composition is tacky.
2. The label of claim 1 , wherein the fluid activatable adhesive composition further comprises a polyacrylate based on the polymerization of a monomer selected from the group consisting of methacrylates, methyl acrylate, ethyl acrylate, 2-chloroethyl vinyl ether, 2-ethylhexyl acrylate, hydroxyethyl methacrylate, butyl acrylate, butyl methacrylate, and combinations thereof.
3. The label of claim 1 , wherein the one or more polymers comprise styrene acrylate copolymer.
4. The label of claim 1 , wherein the concentration of the one or more polymers is from 10 to 70% wt/wt in the dry film.
5. The label of claim 4 , wherein the concentration of the one or more polymers is from 25 to 65% wt/wt in the dry film.
6. The label of claim 5 , wherein the concentration of the one or more polymers is from 30 to 60% wt/wt in the dry film.
7. The label of claim 2 , wherein the concentration of the polyacrylate is from 50 to 90% wt/wt in the dry film.
8. The label of claim 7 , wherein the concentration of the polyacrylate is from 50 to 80% wt in the film.
9. The label of claim 7 , wherein the concentration of the polyacrylate is from 60 to 80% wt in the film.
10. The label of claim 1 , wherein the one or more polymers have an acid number ranging from 150 to 225 mg KOH/g polymer.
11. The label of claim 10 , wherein the one or more polymers have an acid number ranging from 175 to 225 mg KOH/g polymer.
12. The label of claim 1 , wherein the fluid activatable adhesive composition further comprises one or more wetting agents, surfactants, humectants, or a combination thereof.