- Core Logic of Material Selection: Based on Processing Compatibility
The working principle of laser labels determines that the material must match the technical parameters of the laser equipment. This is the primary prerequisite in material selection. The interaction mechanisms between laser and material are generally classified into three types: ablation, color-change, and foaming. Each mechanism places different requirements on the material’s physical structure and chemical composition, which directly affect marking clarity, contrast, and processing efficiency.
From the perspective of laser type:
CO₂ lasers (wavelength 10.6 μm): Mainly applied to non-metallic materials. By vaporizing the molecular structure (ablation) or causing carbonization reactions on the surface, they form marks. Thus, suitable materials must have proper thermal sensitivity and vaporization threshold. For example, paper-based substrates should be pure wood pulp paper or synthetic paper with uniform fiber density to avoid rough edges or character breakage caused by impurities. For plastic substrates such as PET or PVC, thickness should be controlled within 50–150 μm—too thick prevents penetration, while too thin risks substrate damage.
Fiber lasers (wavelength 1064 nm): Mostly used for metals or high-hardness materials. They operate by oxidizing surface ions or forming micro-melting marks. Hence, materials must have good thermal conductivity and stable metal composition. For instance, aluminum alloy substrates must maintain stable magnesium and silicon levels to avoid uneven color in markings.
Processing compatibility also depends on balancing the laser absorption coefficient and thermal diffusivity. Ideal laser label materials should have a high absorption coefficient to concentrate energy on the surface, and low thermal diffusivity to prevent heat from spreading inward and deforming the substrate. For example, polyimide (PI) film used in electronic component marking should have an absorption coefficient above 0.8 and thermal diffusivity between 0.1–0.2 cm²/s to ensure clear edges without substrate shrinkage. Neglecting these parameters may result in blurry markings, substrate burning, or even compromised electronic performance.
- Environmental Resistance: Key Constraints in Material Selection
Laser labels are widely used in industries such as manufacturing, food and pharmaceuticals, logistics, and outdoor engineering. Different environments—temperature, humidity, chemical exposure, or mechanical wear—place unique demands on material durability.
Industrial Manufacturing: Labels often endure high temperatures, oil, and friction. Materials must prioritize heat and chemical resistance. For instance, engine compartment labels require PTFE substrates with ≥150°C heat resistance, paired with silicone adhesives, to ensure labels remain intact under prolonged heat. Machine tool labels, on the other hand, should use PET substrates with surface hardness ≥3H and protective coatings to resist abrasion and oil contamination.
Food & Pharmaceuticals: Materials must comply with safety regulations and feature moisture-proof and antibacterial properties. According to FSANZ (Australia) and FDA (U.S.) standards, laser label substrates in direct contact with food must pass migration tests—thus food-grade PP or PE with solvent-free adhesives are recommended. Pharmaceutical labels must also withstand sterilization. For example, syringe packaging requires PETG that endures 121°C steam sterilization without losing integrity or readability.
Outdoor Engineering: Labels face UV radiation, rain, and temperature fluctuations, so weatherability is crucial. For solar panel labels, fluorocarbon-coated polyester with UV stabilizers should withstand 1000 hours of UVB-313 exposure without discoloration or cracking. Outdoor construction labels require weather-resistant acrylic adhesives that maintain bonding strength between –30°C and 70°C on substrates like aluminum or concrete.
- End-Use Functional Requirements: Value-Driven Material Selection
Beyond basic marking, material choice should reflect end-user demands such as anti-counterfeiting, sustainability, and smart functionality, maximizing label value through feature alignment.
Anti-counterfeiting & Traceability: Materials should emphasize uniqueness and non-replicability. For instance, specialty synthetic paper with invisible fluorescent particles can reveal specific UV patterns after laser marking, with random particle distribution making replication difficult. Alternatively, laser-engraved metal foil can create micro/nano structures that display dynamic color effects through light interference, enhancing anti-counterfeiting. For example, high-end liquor often uses aluminum foil–PET composite substrates, where laser engraving produces nano-textures readable by special devices, enabling both traceability and authentication.
