From the perspective of substrates, the core requirements for eco-friendly stickers are biodegradability, recyclability, and low pollution, with materials adapted according to the functional needs of different application scenarios. Biodegradable substrates are the first choice for “single-use, short-term adhesion” scenarios. These materials can break down into harmless substances in natural environments (e.g., soil, seawater) or under industrial composting conditions, avoiding long-term pollution. PLA (polylactic acid) film is a typical representative—it is derived from renewable plant starches such as corn or sugarcane. Not only is its raw material source sustainable, but it can also fully degrade into carbon dioxide and water within 180 days under industrial composting conditions. At the same time, it provides transparency and scratch resistance close to PET film, making it suitable for short-term labels in premium food and cosmetic applications (e.g., single-use mask packaging, bakery stickers). PBAT (polybutylene adipate terephthalate) film offers both flexibility and water resistance, and when blended with PLA, it improves PLA’s brittleness. This makes it suitable for curved surfaces or slightly moist conditions (e.g., beverage bottle labels, sample labels for personal care products).
For “long-term use, re-stickable applications,” or those that “must fit into recycling systems,” recyclable substrates are more advantageous. These materials do not degrade directly but can be reprocessed through established recycling streams, reducing resource waste. Recycled paper is the most classic choice. Made from waste paper, it reduces logging and water consumption during production, while its natural fiber texture conveys a “rustic, eco-conscious” feel. It is suitable for creative products or environmental campaigns, and when combined with water-based ink, it can enter paper recycling systems directly. In addition, mono-material PET films (without composite layers or special coatings) are also recyclable substrates. They offer high transparency and durability, making them suitable for eco-labels on electronics or household products. After disposal, they can be processed into recycled plastics through PET recycling systems. However, composite materials (e.g., paper-plastic, film-aluminum laminates) should be avoided. Despite certain eco-friendly claims, their difficulty in separation leads to extremely low recycling efficiency, undermining their environmental purpose.
The eco-friendliness of adhesives is a key factor that is often overlooked in eco-sticker material selection. Even if the substrate is biodegradable, adhesives containing formaldehyde or solvent-based aromatics can release harmful substances during production and use, while also hindering biodegradation. Eco-friendly stickers should therefore prioritize water-based adhesives or bio-based adhesives. Water-based adhesives use water as the solvent, contain no VOCs, emit no toxic gases during production, and are highly compatible with biodegradable films and recycled paper. They provide moderate bonding strength, suitable for most food and personal care stickers. Bio-based adhesives, derived from natural substances such as plant proteins or starches, are not only biodegradable themselves but also form a “fully degradable combination” with biodegradable substrates. They can decompose in soil without residue, making them especially suitable for agricultural labels (e.g., seed packets, organic food labels) or disposable outdoor campaign stickers. One must be cautious of so-called “eco hot-melt adhesives.” While solvent-free, they are still made from non-biodegradable petrochemical polymers, meaning they only work for recyclable substrates but cannot meet full lifecycle eco requirements. Ingredient disclosure and eco-certifications (e.g., EU ECOCERT, USDA BioPreferred) should be verified when selecting adhesives.
The safety and sustainability of printing auxiliaries are also vital in eco-friendly sticker material selection, covering inks, coatings, and surface treatments. Inks, as the main medium for communication and aesthetics, should replace traditional solvent-based inks with water-based inks or plant-based inks. Water-based inks use water as the diluent, are free from heavy metals and toxic solvents, cause no pollution during printing, and offer strong color adhesion—suitable for recycled paper and PLA films while maintaining vivid, long-lasting colors. Plant-based inks, made from natural oils such as soybean or linseed oil, provide stronger eco-friendliness and biodegradability. When paired with biodegradable substrates, they allow “ink and substrate to decompose simultaneously,” preventing secondary pollution from ink residues.
For coatings and surface treatments, fluorine- or silicone-based waterproof coatings should be avoided, as they are difficult to degrade and hinder recycling. When water or abrasion resistance is needed, bio-based coatings (e.g., chitosan or starch coatings) can be chosen. Derived from natural materials, they deliver functionality without compromising environmental attributes. For scenarios not requiring special protection, coatings can even be omitted, relying instead on the substrate’s texture and ink finish to convey eco aesthetics—reducing the environmental burden caused by layered materials.
