Acrylic (water-based gel/acrylic latex) : Using water as the solvent or dispersion medium, it is relatively affordable, generally non-toxic, odorless, and non-flammable, with a wide range of solid content and viscosity. Most of them have good heat resistance, and some can withstand high temperatures of around 90℃ or even 150℃. However, their low-temperature labeling performance is weak. If there are slight water or oil stains on the object to be labeled, it is difficult to exert adhesion. The initial adhesion force is established slowly, and it takes more than 20 hours to fully adhere after labeling. They are often used for labels of food, medicine, daily chemicals, and industrial products with high environmental protection requirements. General-purpose permanent acrylic latexes like AF101 and AP103 all fall into this category and can also be used in non-direct contact labeling scenarios such as food and medicine.
Rubber-based adhesives (such as hot melt adhesives) : Hot melt adhesives fall into this category. They have strong fluidity and viscosity, are suitable for low-temperature labeling at -5℃ to 10℃, are environmentally friendly and non-toxic, and have better labeling effects than water-soluble adhesives when there is a trace amount of oil or water on the surface of the object to be labeled. The packaging and transportation cost is low, it does not freeze, no drying equipment is required, it is easy to bond impermeable surfaces, can quickly generate bonding strength, has good storage stability, the adhesive film is continuous, water-resistant and does not allow water vapor to pass through. However, it is not heat-resistant (generally used below 70℃), and is sensitive to temperature during processing and storage (it tends to become hard and brittle when the temperature drops below 15℃ in winter). It has poor re-adhesion and cannot be used for PVC materials or high-temperature labeling environments. It is more suitable for daily use in food, medicine, supermarket labels, etc., such as HP103 and other general-purpose permanent rubber-based adhesives.
Solvent-based adhesives (oil-based adhesives) : Generally, they are cured with soft monomers such as acrylate or vinyl acetate to maintain their stickiness. They have strong adhesive force and can be repeatedly adhered. It has a wide viscosity range, short curing time, low energy consumption, good film-forming property and fastness, excellent water resistance, wide drying rate and open time, and can produce high initial bonding strength. Its bonding strength to difficult-to-bond materials with low polarity (such as PP paper, PVC and other smooth materials) is better than that of water-based glue. However, it is not environmentally friendly. The solvent is volatile, and the solid content is low with a strong odor and flammability, which can easily irritate the respiratory tract. Some organic solvents (such as benzene and toluene) are toxic. After applying adhesive to the surface of the non-porous dense material, the solvent must be completely evaporated before bonding; otherwise, it is prone to bubbling.
Special function glue Some inkjet self-adhesive labels also use removable adhesives (which are easy to remove without leaving residue and are suitable for scenarios where labels need to be changed frequently), spacer adhesives (for labels with special structures), and adhesives developed specifically for extreme environments, such as those for high-temperature, low-temperature, corrosion-resistant, and wear-resistant adhesive label products. To meet the demands of variable message printing and short-run printing in industries such as electronics, electrical appliances, and mechanical manufacturing, adhesives that are suitable for inkjet printing, emphasize environmental protection, can be printed and pasted immediately, have strong adhesion and do not overflow, and are used for digital photos, labels, etc., also fall within the category of special functions.
