Single-sided PET film is generally recommended for silicone heat transfer labels. Its core advantages lie in process compatibility, cost-effectiveness, and performance stability. A detailed analysis is provided below:
1. Process Compatibility: Single-sided PET film better meets the core requirements of heat transfer printing.
The heat transfer process uses high temperatures to transfer the silicone layer from a PET base film to the target material (such as fabric or plastic). This process places strict demands on the base film's release properties and surface treatment. Single-sided PET film forms a release layer after silicone oil coating, enabling precise silicone peeling. However, double-sided PET film, if silicone oil is applied only on one side, may suffer from insufficient adhesion to the untreated PET surface, leading to silicone peeling or image distortion during the transfer process. Furthermore, the more mature production process of single-sided PET film allows for better control of release force (typically, the industry standard peel force tolerance is ±15%), ensuring crisp label edges and no adhesive residue after transfer.
2. Cost-Effectiveness: Single-sided PET film offers lower overall costs.
Double-sided PET film requires coating on both sides, resulting in significantly higher material and processing costs than single-sided PET film. Taking standard thickness (25μm-150μm) as an example, the price of double-sided silicone-coated PET film is approximately 30%-50% higher than single-sided coated products. For large-scale applications such as silicone thermal transfer labels, the cost advantage of single-sided PET film can translate into significant economic benefits. Furthermore, since only one side of the coating needs to be processed during post-processing steps like die-cutting and waste disposal, single-sided PET film has lower scrap rates, further reducing overall costs.
3. Performance Stability: Single-sided PET film is more adaptable to complex application environments.
Heat resistance: During the thermal transfer process, PET film must withstand temperatures of 150°C-200°C. The optimized silicone coating formula of single-sided PET film ensures stable release force at high temperatures, preventing adhesion between the silicone layer and the base film. However, if the other side of double-sided PET film is not treated for high temperature resistance, the difference in thermal expansion coefficient may cause the film to curl, affecting transfer accuracy.
Chemical resistance: Silicone thermal transfer labels are commonly used in electronics and medical fields and must resist corrosion from chemicals such as alcohol and detergents. The silicone oil coating on single-sided PET film forms a dense protective layer, effectively blocking chemical penetration. However, the untreated side of double-sided PET film may suffer chemical corrosion, leading to label peeling or discoloration.
Static Control: During the thermal transfer process, friction between the PET film and the equipment easily generates static electricity, attracting dust and affecting label quality. Single-sided PET film can be treated with an antistatic coating (surface resistance ≤ 10⁹-10¹¹Ω/cm) to dissipate static electricity to the ground. However, double-sided PET film requires antistatic treatment on both sides, which is more expensive and difficult to achieve uniform results.
4. Industry Practice: Single-sided PET Film is the Mainstream Choice
Single-sided PET film dominates heat transfer label applications such as electronic packaging, flexible circuits, and insulation products due to these advantages. For example, in the manufacturing processes of mobile phone lenses, polarizers, and LCD optical lenses, single-sided PET film, as a surface protective film, meets stringent requirements for release strength, light transmittance (≥90%), and cleanliness (produced in Class 1000 cleanrooms). Double-sided PET film is more commonly used in scenarios that require double-sided protection or bonding (such as reflective signs and waterproof materials), which does not match the process requirements of heat transfer labels.