Acrylics work best for substrates that can't handle the heat necessary to apply hot-melt adhesives (HMAs), and they can handle a wider range of temperatures, mostly at the upper end of the scale. Most "all-temp" labels use emulsion acrylic adhesives, which don't perform as well at super-cold temperatures as HMAs or solvent acrylics, which are used for cryogenic environments.
Acrylic adhesives are made of acrylic, methacrylic, or cyanoacrylic resins. Superglues are probably the most famous of all acrylic adhesives, but the ones we use aren't formulated to hold quite that tightly—at least, not to their liners! Our acrylics offer excellent pressure sensitivity (which is very important in our business), with high initial tack and temperature resistance, and they age well. For those circumstances where it matters, they also have a high UV resistance.
We use two types of acrylic adhesives: solvent and emulsion. Solvent acrylic adhesives use an organic solvent other than water for a base (yes, water is a solvent, believe it or not). Our solvent acrylic is used exclusively for cryogenic labels, being long-term and stable right down to -320° F.
Emulsion acrylic adhesives result from mixing acrylic resins, Ethylene Vinyl Acetate (EVA), and acetic vinyl into water. This creates an opaque, gooey emulsion, which is basically a mix of tiny droplets of the abovementioned materials suspended in water, because they don't completely dissolve. Emulsions may sound weird, but you've probably dealt with them before, though you may not have realized it. You see, mayonnaise, which is made of egg yolks beaten with oil and vinegar, is one type of emulsion.
While emulsion acrylic mixes are a little less edible than mayo, they're non-toxic and non-flammable. Emulsion acrylic adhesives stick tightly to most materials, including porous materials like corrugated cardboard, and have high initial tack. They're ideal for packaging of all standard types, and some can handle temperatures down to around -65° F. However, many won't adhere to surfaces that are already frozen, which limits their usefulness. They have to be attached before freezing occurs. That's why HMAs are usually preferable for freezer labels.